WorldWideScience

Sample records for interface exchange coupling

  1. Ultrathin Limit of Exchange Bias Coupling at Oxide Multiferroic/Ferromagnetic Interfaces

    NARCIS (Netherlands)

    Huijben, Mark; Yu, P.; Martin, L.W.; Molegraaf, Hajo; Chu, Y.H.; Holcomb, M.B.; Balke, N.; Rijnders, Augustinus J.H.M.; Ramesh, R.

    2013-01-01

    Exchange bias coupling at the multiferroic- ferromagnetic interface in BiFeO3/La0.7Sr0.3MnO3 heterostructures exhibits a critical thickness for ultrathin BiFeO3 layers of 5 unit cells (2 nm). Linear dichroism measurements demonstrate the dependence on the BiFeO3 layer thickness with a strong

  2. Interface adjustment and exchange coupling in the IrMn/NiFe system

    Energy Technology Data Exchange (ETDEWEB)

    Spizzo, F.; Tamisari, M.; Chinni, F.; Bonfiglioli, E.; Del Bianco, L., E-mail: lucia.delbianco@unife.it

    2017-01-01

    The exchange bias effect was investigated, in the 5–300 K temperature range, in samples of IrMn [100 Å]/NiFe [50 Å] (set A) and in samples with inverted layer-stacking sequence (set B), produced at room temperature by DC magnetron sputtering in a static magnetic field of 400 Oe. The samples of each set differ for the nominal thickness (t{sub Cu}) of a Cu spacer, grown at the interface between the antiferromagnetic and ferromagnetic layers, which was varied between 0 and 2 Å. It has been found out that the Cu insertion reduces the values of the exchange field and of the coercivity and can also affect their thermal evolution, depending on the stack configuration. Indeed, the latter also determines a peculiar variation of the exchange bias properties with time, shown and discussed with reference to the samples without Cu of the two sets. The results have been explained considering that, in this system, the exchange coupling mechanism is ruled by the glassy magnetic behavior of the IrMn spins located at the interface with the NiFe layer. Varying the stack configuration and t{sub Cu} results in a modulation of the structural and magnetic features of the interface, which ultimately affects the spins dynamics of the glassy IrMn interfacial component. - Highlights: • Exchange bias effect in IrMn/NiFe samples with interfacial Cu spacer. • A variation of exchange bias with time is observed in as-deposited samples. • Magnetic modification of the interface by varying the stack sequence and Cu thickness. • Interface adjustment affects the dynamics of interfacial IrMn spins. • The exchange bias properties can be tuned by interface adjustment.

  3. Study of the influence of Nb buffer layer on the exchange coupling induced at the Co/IrMn interface

    Energy Technology Data Exchange (ETDEWEB)

    Merino, I.L.C., E-mail: isabel5cas@gmail.com [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180 (Brazil); Figueiredo, L.C. [Instituto de Física, Universidade de Brasília, Brasília 70910-900 (Brazil); Passamani, E.C.; Nascimento, V.P. [Departamento de Física, Universidade Federal do Espírito Santo, Vitória 29075-910 (Brazil); Pelegrini, F. [Instituto de Física, Universidade Federal de Goiás, Goiânia 74560-900 (Brazil); Baggio Saitovitch, E. [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180 (Brazil)

    2017-06-15

    Highlights: • Nb buffer layer favors smooth/rough Co/IrMn interfaces, depending on its thickness. • Double and single-like hysteresis loop features depend on the Nb thickness. • Co uniaxial anisotropy induced exchange-bias in as-deposited sample. • Uniaxial and exchange-bias anisotropy directions depend on the Nb thickness. • Thicker Nb favors non-collinear anisotropies, while thinner Nb favors collinear. - Abstract: Hybrid Nb(t{sub Nb})/Co(10 nm)/IrMn(15 nm)/Nb(10 nm) heterostructured materials were prepared by DC Magnetron Sputtering and systematically studied by X-ray, magnetization and ferromagnetic resonance techniques. For thinner Nb buffer layer (≤10 nm), it was found that there is an inter-diffusion at Co/IrMn interface, which favors double-like hysteresis loop. For thicker Nb layers, however, a gradual transition from double to single-like hysteresis loops is observed and it is associated with the reduction of the Nb roughness, which also enhances the exchange coupling at the Co/IrMn interface. Nb grown on IrMn layer induces the formation of an NbIrMn alloy layer, while no evidence of inter-diffusion at the Co/Nb interface is observed. For rougher Nb buffer layers (t{sub Nb} < 50 nm), exchange bias and Co uniaxial anisotropies are pointing at the same direction (β∼zero), but for smoother Nb buffer layer (t{sub Nb} = 50 nm) a β angle of 150{sup o} is found. Exchange bias effect was measured in as-prepared and in field-cooled samples; being its presence, in as-prepared sample, attributed to the unidirectional anisotropy of the Co layer (its intensity is modified in case of sample with a CoIrMn alloy layer). Considering that the Si/Nb/Co/IrMn interfaces have different β values (t{sub Nb} = 35 and 50 nm), a study of the influence of magnetization direction, governed by exchange-biased layers, on superconducting properties of Nb films can be successfully done in this hybrid system.

  4. Tilt engineering of exchange coupling at G-type SrMnO3/(La,Sr)MnO3 interfaces

    Science.gov (United States)

    Li, F.; Song, C.; Wang, Y. Y.; Cui, B.; Mao, H. J.; Peng, J. J.; Li, S. N.; Wang, G. Y.; Pan, F.

    2015-11-01

    With the recent realization of hybrid improper ferroelectricity and room-temperature multiferroic by tilt engineering, “functional” octahedral tilting has become a novel concept in multifunctional perovskite oxides, showing great potential for property manipulation and device design. However, the control of magnetism by octahedral tilting has remained a challenging issue. Here a qualitative and quantitative tilt engineering of exchange coupling, one of the magnetic properties, is demonstrated at compensated G-type antiferromagnetic/ferromagnetic (SrMnO3/La2/3Sr1/3MnO3) interfaces. According to interfacial Hamiltonian, exchange bias (EB) in this system originates from an in-plane antiphase rotation (a-) in G-type antiferromagnetic layer. Based on first-principles calculation, tilt patterns in SrMnO3 are artificially designed in experiment with different epitaxial strain and a much stronger EB is attained in the tensile heterostructure than the compressive counterpart. By controlling the magnitude of octahedral tilting, the manipulation of exchange coupling is even performed in a quantitative manner, as expected in the theoretical estimation. This work realized the combination of tilt engineering and exchange coupling, which might be significant for the development of multifunctional materials and antiferromagnetic spintronics.

  5. Exchange processes at geosphere-biosphere interface. Current SKB approach and example of coupled hydrological-ecological approach

    Energy Technology Data Exchange (ETDEWEB)

    Woerman, Anders [Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dept. of Biometry and Technology

    2003-09-01

    The design of the repository for final disposal of spent nuclear fuel proposed by SKB is based on a multi-barrier system, in which the geosphere and biosphere are the utmost barrier surrounding the engineer barriers. This report briefly reviews the current approach taken by SKB to account for hydrological and ecological processes at the geosphere-biosphere interface (GBI) and their future plans in this area. A simple analysis was performed to shift the focus of performance assessment involving geosphere-biosphere interface modelling from the very simplistic assumption that the quaternary sediments are bypassed to one in which a more detailed model for sub-surface flows is included. This study indicated that, for many assumed ecosystem descriptions, the presence of the GBI leads to lower maximum doses to individual humans compared to a case when the GBI is neglected. This effect is due to the additional 'barrier' offered by the GBI. The main exposure pathways were assumed to occur through the food web. However, particularly the leakage on land through the stream-network and lakes can lead to higher doses due to ecosystem interaction with arable land. A scenario that gives particularly long duration of doses occurs due to land rise and with the transformation of the former bay and lake bed sediments into agricultural land. This effect is due to the significant retention or accumulation in aquatic sediment, which causes high activities to build up with time. Particularly, in combination with changing conditions in climate, humans life-style or geographic conditions (land rise, deforestation,etc.) doses to individual humans can be large.

  6. Exchange processes at geosphere-biosphere interface. Current SKB approach and example of coupled hydrological-ecological approach

    International Nuclear Information System (INIS)

    Woerman, Anders

    2003-09-01

    The design of the repository for final disposal of spent nuclear fuel proposed by SKB is based on a multi-barrier system, in which the geosphere and biosphere are the utmost barrier surrounding the engineer barriers. This report briefly reviews the current approach taken by SKB to account for hydrological and ecological processes at the geosphere-biosphere interface (GBI) and their future plans in this area. A simple analysis was performed to shift the focus of performance assessment involving geosphere-biosphere interface modelling from the very simplistic assumption that the quaternary sediments are bypassed to one in which a more detailed model for sub-surface flows is included. This study indicated that, for many assumed ecosystem descriptions, the presence of the GBI leads to lower maximum doses to individual humans compared to a case when the GBI is neglected. This effect is due to the additional 'barrier' offered by the GBI. The main exposure pathways were assumed to occur through the food web. However, particularly the leakage on land through the stream-network and lakes can lead to higher doses due to ecosystem interaction with arable land. A scenario that gives particularly long duration of doses occurs due to land rise and with the transformation of the former bay and lake bed sediments into agricultural land. This effect is due to the significant retention or accumulation in aquatic sediment, which causes high activities to build up with time. Particularly, in combination with changing conditions in climate, humans life-style or geographic conditions (land rise, deforestation,etc.) doses to individual humans can be large

  7. Micromagnetic simulation of exchange coupled ferri-/ferromagnetic heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Oezelt, Harald, E-mail: harald.oezelt@fhstp.ac.at [Industrial Simulation, St. Pölten University of Applied Sciences, Matthias Corvinus-Straße 15, A-3100 St. Pölten (Austria); Kovacs, Alexander; Reichel, Franz; Fischbacher, Johann; Bance, Simon [Industrial Simulation, St. Pölten University of Applied Sciences, Matthias Corvinus-Straße 15, A-3100 St. Pölten (Austria); Gusenbauer, Markus [Center for Integrated Sensor Systems, Danube University Krems, Viktor Kaplan-Straße 2, A-2700 Wiener Neustadt (Austria); Schubert, Christian; Albrecht, Manfred [Institute of Physics, Chemnitz University of Technology, Reichenhainer Straße 70, D-09126 Chemnitz (Germany); Institute of Physics, University of Augsburg, Universitätsstraße 1, D-86159 Augsburg (Germany); Schrefl, Thomas [Industrial Simulation, St. Pölten University of Applied Sciences, Matthias Corvinus-Straße 15, A-3100 St. Pölten (Austria); Center for Integrated Sensor Systems, Danube University Krems, Viktor Kaplan-Straße 2, A-2700 Wiener Neustadt (Austria)

    2015-05-01

    Exchange coupled ferri-/ferromagnetic heterostructures are a possible material composition for future magnetic storage and sensor applications. In order to understand the driving mechanisms in the demagnetization process, we perform micromagnetic simulations by employing the Landau–Lifshitz–Gilbert equation. The magnetization reversal is dominated by pinning events within the amorphous ferrimagnetic layer and at the interface between the ferrimagnetic and the ferromagnetic layer. The shape of the computed magnetization reversal loop corresponds well with experimental data, if a spatial variation of the exchange coupling across the ferri-/ferromagnetic interface is assumed. - Highlights: • We present a model for exchange coupled ferri-/ferromagnetic heterostructures. • We incorporate the microstructural features of the amorphous ferrimagnet. • A distribution of interface exchange coupling is assumed to fit experimental data. • The reversal is dominated by pinning within the ferrimagnet and at the interface.

  8. EPR of exchange coupled systems

    CERN Document Server

    Bencini, Alessandro

    2012-01-01

    From chemistry to solid state physics to biology, the applications of Electron Paramagnetic Resonance (EPR) are relevant to many areas. This unified treatment is based on the spin Hamiltonian approach and makes extensive use of irreducible tensor techniques to analyze systems in which two or more spins are magnetically coupled. This edition contains a new Introduction by coauthor Dante Gatteschi, a pioneer and scholar of molecular magnetism.The first two chapters review the foundations of exchange interactions, followed by examinations of the spectra of pairs and clusters, relaxation in oligon

  9. Microscopic origin of the unidirectional anisotropy on the exchange-coupled CoO/Co interface; Mikroskopischer Ursprung der unidirektionalen Anisotropie an der austauschgekoppelten CoO/Co-Grenzflaeche

    Energy Technology Data Exchange (ETDEWEB)

    Ghadimi, M.R.

    2006-03-03

    Exchange coupling at the interface between an antiferromagnet (AFM) and a ferromagnet (FM) causes unidirectional anisotropy of the FM layer, which induces a shift of the hysteresis loop along the magnetic field axis. In order to understand the microscopic origin of EB, the domain state (DS) model was proposed. This model is based on the physics of diluted antiferromagnets in an external magnetic field (DAFF) and yields the description of the most salient EB features of any model to date. The intentional dilution is realized by implementing non-magnetic defects in the bulk of the AFM. Under certain conditions, DAFF develops in a metastable domain state after cooling below the Neel-temperature in an external magnetic field. These domains carry a remanent domain state magnetization. One part of the domain state magnetization, the so-called irreversible domain state magnetization, provides the exchange coupling field at the interface to the FM layer giving rise to the EB. The stability and the size of the domains in the AFM and therefore the EB can be controlled by the number of defects and their different types throughout the volume part of the AFM. In this work, the experimental evidences of a direct influence of different types of defects (twins and 3d-growth as structural defects and dilution as substitutional defects) on the EB in epitaxially grown CoO/Co bilayers are presented. Furthermore, the influence of the crystal orientation of the CoO layer on EB is demonstrated. (orig.)

  10. Effect of nebulizer/spray chamber interfaces on simultaneous, axial view inductively coupled plasma optical emission spectrometry for the direct determination of As and Se species separated by ion exchange high-performance liquid chromatography

    International Nuclear Information System (INIS)

    Gettar, Raquel T.; Smichowski, Patricia; Garavaglia, Ricardo N.; Farias, Silvia; Batistoni, Daniel A.

    2005-01-01

    Different nebulizer/expansion chamber combinations were evaluated to assess their performance for sample introduction in the direct coupling with an axial view inductively coupled plasma multielement spectrometer for on-line determination of As and Se species previously separated by ion exchange-high performance liquid chromatography. The column effluents were injected into the plasma without prior derivatization. The instrument operation software was adapted for data acquisition and processing to allow multi-wavelength recording of the transient chromatographic peaks. After optimization of the chromatographic operating conditions, separation of mixtures of inorganic As and Se species, and of inorganic and two organic As species (monomethylarsonic and dimethylarsinic acids), was achieved with excellent resolution. Species discrimination from mixtures of As and Se oxyanions was further improved by the simultaneous element detection at specific analytical wavelengths. Three nebulizers and three spray chambers, employed in seven combinations, were tested as interfaces. Concentric nebulizers associated to a glass cyclonic chamber appear most suitable regarding sensitivity and signal to noise ratio. Measured element detection limits (3 σ) were around 10 ng ml -1 for all the species considered, making the method a viable alternative to similar procedures that employ volatile hydride generation previous to sample injection into the plasma. Analytical recoveries both for inorganic and organic species ranged between 92 and 107%. The method was demonstrated to be apt for the analysis of surface waters potentially subjected to natural contamination with arsenic

  11. Oscillatory exchange coupling in magnetic molecules

    International Nuclear Information System (INIS)

    Sevincli, H; Senger, R T; Durgun, E; Ciraci, S

    2007-01-01

    Recently, first-principles calculations based on the spin-dependent density functional theory (DFT) have revealed that the magnetic ground state of a finite linear carbon chain capped by two transition metal (TM) atoms alternates between ferromagnetic and antiferromagnetic configurations depending on the number of carbon atoms. The character of indirect exchange coupling in this nanoscale, quasi-zero-dimensional system is different from those analogous extended structures consisting of magnetic layers separated by a non-magnetic spacer (or magnetic impurities in a non-magnetic host material) and a formulation based on an atomic picture is needed. We present a tight-binding model which provides a theoretical framework to the underlying mechanism of the exchange coupling in molecular structures. The model calculations are capable of reproducing the essential features of the DFT results for the indirect exchange coupling and the atomic magnetic moments in the TM-C n -TM structures as functions of the number of carbon atoms. In nanostructures consisting of a few atoms the concepts of extended wavefunctions and the band theory lose their validity, and hence the oscillatory exchange coupling turns out to be a consequence of quantum interference effects due to the spin-dependent onsite and hopping energies

  12. Exchange Processes at Geosphere-Biosphere Interface

    International Nuclear Information System (INIS)

    Worman, A.; Sjogren, B.; Dverstorp, B.; Xu, S.

    2004-01-01

    The radioecological models included in performance assessments to date by the Swedish nuclear industry for existing and planned nuclear waste repositories do not explicitly represent the transport of radionuclides from bedrock into the near-surface geological environment. It has been argued that bypassing the transition zone from the bedrock to the quarternary deposits and the biosphere (the geosphere-biosphere interface, GBI) leads to conservative estimates of estimated doses and risk. This study demonstrates that this may not always be true. The study is based on an integrated model representation of a release of radionuclides from a hypothetical repository, transport through the crystalline bedrock and the near-surface deposits to the biosphere. A three-dimensional flow model is developed, which has a fairly accurate description of both surface and groundwater hydrology and is coupled to radioecological models. The development has great significance for estimation of flow field at the repository level as well as for estimation of transport pathways and residence time distributions for radionuclides. The modelling approach is based on the characterisation of radionuclide residence times in the bedrock and the quaternary deposits, as well as the distribution of radionuclides in ecosystems. Simulation examples are presented to illustrate the relative importance of transport processes in the quaternary sediments and the hydraulic interaction between the bedrock, quaternary deposits and various ecosystems. The modelling results show that, in many cases, taking into account the biosphere-geosphere interface leads to a delay of radionuclide arrival to the biosphere. For other conditions, the more precise prediction of radionuclide ex-filtration locations in the biosphere can result in higher environmental concentrations compared with estimates based on diluting radionuclide in a large area. An improved representation of these processes will enhance our understanding of

  13. The marketing-finance interface: A relational exchange perspective

    NARCIS (Netherlands)

    Ruyter, de J.C.; Wetzels, M.G.M.

    2000-01-01

    In marketing theory and practice the concept of relational exchanges has gained wide popularity particularly with regards to external exchange parties, such as consumers and marketing channel intermediaries. However, the concept of relational exchange could also be applied to marketing interfaces

  14. Mesh-based parallel code coupling interface

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, K.; Steckel, B. (eds.) [GMD - Forschungszentrum Informationstechnik GmbH, St. Augustin (DE). Inst. fuer Algorithmen und Wissenschaftliches Rechnen (SCAI)

    2001-04-01

    MpCCI (mesh-based parallel code coupling interface) is an interface for multidisciplinary simulations. It provides industrial end-users as well as commercial code-owners with the facility to combine different simulation tools in one environment. Thereby new solutions for multidisciplinary problems will be created. This opens new application dimensions for existent simulation tools. This Book of Abstracts gives a short overview about ongoing activities in industry and research - all presented at the 2{sup nd} MpCCI User Forum in February 2001 at GMD Sankt Augustin. (orig.) [German] MpCCI (mesh-based parallel code coupling interface) definiert eine Schnittstelle fuer multidisziplinaere Simulationsanwendungen. Sowohl industriellen Anwender als auch kommerziellen Softwarehersteller wird mit MpCCI die Moeglichkeit gegeben, Simulationswerkzeuge unterschiedlicher Disziplinen miteinander zu koppeln. Dadurch entstehen neue Loesungen fuer multidisziplinaere Problemstellungen und fuer etablierte Simulationswerkzeuge ergeben sich neue Anwendungsfelder. Dieses Book of Abstracts bietet einen Ueberblick ueber zur Zeit laufende Arbeiten in der Industrie und in der Forschung, praesentiert auf dem 2{sup nd} MpCCI User Forum im Februar 2001 an der GMD Sankt Augustin. (orig.)

  15. MD2065: Emittance exchange with linear coupling

    CERN Document Server

    Carver, Lee Robert; Persson, Tobias Hakan Bjorn; Amorim, David; Levens, Tom; Pesah, Arthur Chalom; CERN. Geneva. ATS Department

    2018-01-01

    In order to better understand the luminosity imbalance between ATLAS and CMS that was observed in 2016, it was proposed to perform a test whereby the horizontal and vertical emittances are exchanged by crossing the tunes in the presence of linear coupling. The luminosity before and after the exchange could be compared to see if the imbalance stems purely from the uneven emittances or if there is an additional mechanism in play. However, due to limited machine availability only tests at injection were able to performed.

  16. Magnetic exchange at realistic CoO/Ni interfaces

    KAUST Repository

    Grytsiuk, Sergii

    2012-07-30

    We study the CoO/Ni interface by first principles calculations. Because the lattice mismatch is large, a realistic description requires a huge supercell. We investigate two interface configurations: in interface 1 the coupling between the Ni and Co atoms is mediated by O, whereas in interface 2 the Ni and Co atoms are in direct contact. We find that the magnetization (including the orbital moment) in interface 1 has a similar value as in bulk Ni but opposite sign, while in interface 2 it grows by 164%. The obtained magnetic moments can be explained by the local atomic environments. In addition, we find effects of charge transfer between the interface atoms. The Co 3d local density of states of interface 2 exhibits surprisingly small deviations from the corresponding bulk result, although the first coordination sphere is no longer octahedral. © Springer-Verlag 2012.

  17. Magnetic exchange at realistic CoO/Ni interfaces

    KAUST Repository

    Grytsyuk, Sergiy; Cossu, Fabrizio; Schwingenschlö gl, Udo

    2012-01-01

    We study the CoO/Ni interface by first principles calculations. Because the lattice mismatch is large, a realistic description requires a huge supercell. We investigate two interface configurations: in interface 1 the coupling between the Ni and Co atoms is mediated by O, whereas in interface 2 the Ni and Co atoms are in direct contact. We find that the magnetization (including the orbital moment) in interface 1 has a similar value as in bulk Ni but opposite sign, while in interface 2 it grows by 164%. The obtained magnetic moments can be explained by the local atomic environments. In addition, we find effects of charge transfer between the interface atoms. The Co 3d local density of states of interface 2 exhibits surprisingly small deviations from the corresponding bulk result, although the first coordination sphere is no longer octahedral. © Springer-Verlag 2012.

  18. Temperature and cooling field dependent exchange coupling in [Cr/Gd]{sub 5} multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, Z.W.; Chen, H.J.; Jiang, W.D.; Wang, J.F.; Yu, S.J. [Department of Physics, China Jiliang University, Hangzhou (China); Hou, Y.L.; Lu, B.; Ye, Q.L. [Department of Physics, Hangzhou Normal University, Hangzhou (China)

    2016-09-15

    Exchange coupling has been investigated in the [Cr/Gd]{sub 5} multilayers deposited at 25, 200, and 400 C, where the Neel temperature (T{sub N}) of antiferromagnetic Cr is slightly higher than the Curie temperature (T{sub C}) of ferromagnetic Gd. It was found that the exchange coupling existed not only at T{sub C} < T < T{sub N}, but also above the temperature (T{sub N}) of antiferromagnetic orderings with incommensurate spin-density wave structures transiting to paramagnetic state. These results can be discussed in terms of the crucial role played by the antiferromagnetic spins of Cr with commensurate spin-density wave structures in the vicinity of the Cr/Gd interfaces. Moreover, the exchange coupling of the multilayers grown at different temperatures exhibited different dependencies on the measuring temperature and the cooling field, respectively. Positive exchange bias was observed in the multilayers grown at 200 and 400 C. The interfacial roughness, grain size, and the antiferromagnetic orderings of Cr may be responsible for the anomalous exchange coupling of the multilayers. In addition, the competition between the exchange coupling at Cr/Gd interfaces and the external field-Cr surface magnetic coupling can explain the appearance of negative or positive exchange bias. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Multiscale Universal Interface: A concurrent framework for coupling heterogeneous solvers

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Yu-Hang, E-mail: yuhang_tang@brown.edu [Division of Applied Mathematics, Brown University, Providence, RI (United States); Kudo, Shuhei, E-mail: shuhei-kudo@outlook.jp [Graduate School of System Informatics, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, 657-8501 (Japan); Bian, Xin, E-mail: xin_bian@brown.edu [Division of Applied Mathematics, Brown University, Providence, RI (United States); Li, Zhen, E-mail: zhen_li@brown.edu [Division of Applied Mathematics, Brown University, Providence, RI (United States); Karniadakis, George Em, E-mail: george_karniadakis@brown.edu [Division of Applied Mathematics, Brown University, Providence, RI (United States); Collaboratory on Mathematics for Mesoscopic Modeling of Materials, Pacific Northwest National Laboratory, Richland, WA 99354 (United States)

    2015-09-15

    Graphical abstract: - Abstract: Concurrently coupled numerical simulations using heterogeneous solvers are powerful tools for modeling multiscale phenomena. However, major modifications to existing codes are often required to enable such simulations, posing significant difficulties in practice. In this paper we present a C++ library, i.e. the Multiscale Universal Interface (MUI), which is capable of facilitating the coupling effort for a wide range of multiscale simulations. The library adopts a header-only form with minimal external dependency and hence can be easily dropped into existing codes. A data sampler concept is introduced, combined with a hybrid dynamic/static typing mechanism, to create an easily customizable framework for solver-independent data interpretation. The library integrates MPI MPMD support and an asynchronous communication protocol to handle inter-solver information exchange irrespective of the solvers' own MPI awareness. Template metaprogramming is heavily employed to simultaneously improve runtime performance and code flexibility. We validated the library by solving three different multiscale problems, which also serve to demonstrate the flexibility of the framework in handling heterogeneous models and solvers. In the first example, a Couette flow was simulated using two concurrently coupled Smoothed Particle Hydrodynamics (SPH) simulations of different spatial resolutions. In the second example, we coupled the deterministic SPH method with the stochastic Dissipative Particle Dynamics (DPD) method to study the effect of surface grafting on the hydrodynamics properties on the surface. In the third example, we consider conjugate heat transfer between a solid domain and a fluid domain by coupling the particle-based energy-conserving DPD (eDPD) method with the Finite Element Method (FEM)

  20. Failure of standard approximations of the exchange coupling in nanostructures

    DEFF Research Database (Denmark)

    Pedersen, Jesper Goor; Flindt, Christian; Mortensen, Asger

    2007-01-01

    We calculate the exchange coupling for a double dot system using a numerically exact technique based on finite-element methods and an expansion in two-dimensional Gaussians. Specifically, we evaluate the exchange coupling both for a quasi-one- and a two-dimensional system, also including an appli...

  1. Exchange bias in nearly perpendicularly coupled ferromagnetic/ferromagnetic system

    International Nuclear Information System (INIS)

    Bu, K.M.; Kwon, H.Y.; Oh, S.W.; Won, C.

    2012-01-01

    Exchange bias phenomena appear not only in ferromagnetic/antiferromagnetic systems but also in ferromagnetic/ferromagnetic systems in which two layers are nearly perpendicularly coupled. We investigated the origin of the symmetry-breaking mechanism and the relationship between the exchange bias and the system's energy parameters. We compared the results of computational Monte Carlo simulations with those of theoretical model calculation. We found that the exchange bias exhibited nonlinear behaviors, including sign reversal and singularities. These complicated behaviors were caused by two distinct magnetization processes depending on the interlayer coupling strength. The exchange bias reached a maximum at the transition between the two magnetization processes. - Highlights: ► Exchange bias phenomena are found in perpendicularly coupled F/F systems. ► Exchange bias exhibits nonlinear behaviors, including sign reversal and singularities. ► These complicated behaviors were caused by two distinct magnetization processes. ► Exchange bias reached a maximum at the transition between the two magnetization processes. ► We established an equation to maximize the exchange bias in perpendicularly coupled F/F system.

  2. Sheathless interface for coupling capillary electrophoresis with mass spectrometry

    Science.gov (United States)

    Wang, Chenchen; Tang, Keqi; Smith, Richard D.

    2014-06-17

    A sheathless interface for coupling capillary electrophoresis (CE) with mass spectrometry is disclosed. The sheathless interface includes a separation capillary for performing CE separation and an emitter capillary for electrospray ionization. A portion of the emitter capillary is porous or, alternatively, is coated to form an electrically conductive surface. A section of the emitter capillary is disposed within the separation capillary, forming a joint. A metal tube, containing a conductive liquid, encloses the joint.

  3. Exchange coupling in metallic multilayers with a top FeRh layer

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, S., E-mail: yamada@ee.es.osaka-u.ac.jp; Kanashima, T.; Hamaya, K., E-mail: hamaya@ee.es.osaka-u.ac.jp [Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531 (Japan); Tanikawa, K. [Department of Electronics, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Hirayama, J. [Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531 (Japan); Department of Electronics, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Taniyama, T. [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)

    2016-05-15

    We study magnetic properties of metallic multilayers with FeRh/ferromagnet interfaces grown by low-temperature molecular beam epitaxy. Room-temperature coercivity of the ferromagnetic layers is significantly enhanced after the growth of FeRh, proving the existence of the exchange coupling between the antiferromagnetic FeRh layer and the ferromagnetic layer. However, exchange bias is not clearly observed probably due to the presence of disordered structures, which result from the lattice strain at the FeRh/ferromagnet interfaces due to the lattice mismatch. We infer that the lattice matched interface between FeRh and ferromagnetic layers is a key parameter for controlling magnetic switching fields in such multilayer systems.

  4. Switching behaviour of coupled antiferro- and ferromagnetic systems: exchange bias

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    2009-01-01

    in NiO nanoparticles (Kodama and Berkowitz 1999 Phys. Rev. B 59 6321 and Lindgård 2003 J. Magn. Magn. Mater. 266 88)) in a field severely limits the exchange biasing potential. The interface between the different magnets is found to be that originally assumed by Meiklejohn and Bean (1956 Phys. Rev. 102...

  5. Exchange coupling mechanism for magnetization reversal and thermal stability of Co nanoparticles embedded in a CoO matrix

    International Nuclear Information System (INIS)

    Givord, Dominique; Skumryev, Vassil; Nogues, Josep

    2005-01-01

    A model providing a semi-quantitative account of the magnetic behavior of Co nanoparticles embedded in a CoO matrix is presented. The results confirm that exchange coupling at the interface between ferromagnetic (FM) and antiferromagnetic (AFM) nanostructures could provide an extra source of magnetic anisotropy, leading to thermal stability of the FM nanoparticles. It is shown that perpendicular coupling between the AFM and FM moments may result in large coercivities. The energy barrier, which works against reversal is due to the AFM susceptibility anisotropy. The experimentally observed exchange bias is tentatively ascribed to pre-existing intrinsic canting of the AFM moments at the interface

  6. Magnetic moments, coupling, and interface interdiffusion in Fe/V(001) superlattices

    Science.gov (United States)

    Schwickert, M. M.; Coehoorn, R.; Tomaz, M. A.; Mayo, E.; Lederman, D.; O'brien, W. L.; Lin, Tao; Harp, G. R.

    1998-06-01

    Epitaxial Fe/V(001) multilayers are studied both experimentally and by theoretical calculations. Sputter-deposited epitaxial films are characterized by x-ray diffraction, magneto-optical Kerr effect, and x-ray magnetic circular dichroism. These results are compared with first-principles calculations modeling different amounts of interface interdiffusion. The exchange coupling across the V layers is observed to oscillate, with antiferromagnetic peaks near the V layer thicknesses tV~22, 32, and 42 Å. For all films including superlattices and alloys, the average V magnetic moment is antiparallel to that of Fe. The average V moment increases slightly with increasing interdiffusion at the Fe/V interface. Calculations modeling mixed interface layers and measurements indicate that all V atoms are aligned with one another for tV<~15 Å, although the magnitude of the V moment decays toward the center of the layer. This ``transient ferromagnetic'' state arises from direct (d-d) exchange coupling between V atoms in the layer. It is argued that the transient ferromagnetism suppresses the first antiferromagnetic coupling peak between Fe layers, expected to occur at tV~12 Å.

  7. Pure spin current manipulation in antiferromagnetically exchange coupled heterostructures

    Science.gov (United States)

    Avilés-Félix, L.; Butera, A.; González-Chávez, D. E.; Sommer, R. L.; Gómez, J. E.

    2018-03-01

    We present a model to describe the spin currents generated by ferromagnet/spacer/ferromagnet exchange coupled trilayer systems and heavy metal layers with strong spin-orbit coupling. By exploiting the magnitude of the exchange coupling (oscillatory RKKY-like coupling) and the spin-flop transition in the magnetization process, it has been possible to produce spin currents polarized in arbitrary directions. The spin-flop transition of the trilayer system originates pure spin currents whose polarization vector depends on the exchange field and the magnetization equilibrium angles. We also discuss a protocol to control the polarization sign of the pure spin current injected into the metallic layer by changing the initial conditions of magnetization of the ferromagnetic layers previously to the spin pumping and inverse spin Hall effect experiments. The small differences in the ferromagnetic layers lead to a change in the magnetization vector rotation that permits the control of the sign of the induced voltage components due to the inverse spin Hall effect. Our results can lead to important advances in hybrid spintronic devices with new functionalities, particularly, the ability to control microscopic parameters such as the polarization direction and the sign of the pure spin current through the variation of macroscopic parameters, such as the external magnetic field or the thickness of the spacer in antiferromagnetic exchange coupled systems.

  8. Switching field of partially exchange-coupled particles

    International Nuclear Information System (INIS)

    Oliva, M.I.; Bertorello, H.R.; Bercoff, P.G.

    2004-01-01

    The magnetization reversal of partially exchange-coupled particles is studied in detail. The starting point is the observation of a complicated phenomenology in the irreversible susceptibility and FORC distribution functions of Ba hexaferrite samples obtained by means of different sintering conditions. Several peaks in the first-order reversal curve (FORC) distribution functions were identified and associated with clusters with different number of particles. The switching fields of these clusters were related to an effective anisotropy constant Keff that depends on the number of particles in the cluster. Keff is linked to the exchange-coupled volume between two neighboring particles and as a weighted mean between the anisotropy constants of the coupled and uncoupled volumes. By using the modified Brown's equation αex=0.322 is obtained.In order to interpret these results, the switching field of a two-particle system with partial exchange coupling is studied. It is assumed that the spins reorientation across the contact plane between the particles is like a Bloch wall. The energy of the system is written in terms of the fraction of volume affected by exchange coupling and the switching fields for both particles are calculated. At small interaction volume fraction each particle inverts its magnetization independently from the other. As the fraction of exchange-coupled volume increases, cooperative effects appear and the two particles invert their magnetization in a cooperative way.The proposed model allows to interpret for the first time the empirical factor αex in terms of physical arguments and also explain the details observed in the FORC distribution function

  9. Magnetic coupling at perovskite and rock-salt structured interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Matvejeff, M., E-mail: mikko.matvejeff@picosun.com [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8581 Chiba (Japan); Department of Chemistry, Aalto University, Kemistintie 1, 02150 Espoo (Finland); Ahvenniemi, E. [Department of Chemistry, Aalto University, Kemistintie 1, 02150 Espoo (Finland); Takahashi, R.; Lippmaa, M. [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8581 Chiba (Japan)

    2015-10-05

    We study magnetic coupling between hole-doped manganite layers separated by either a perovskite or a rock-salt barrier of variable thickness. Both the type and the quality of the interface have a strong impact on the minimum critical barrier thickness where the manganite layers become magnetically decoupled. A rock-salt barrier layer only 1 unit cell (0.5 nm) thick remains insulating and is able to magnetically de-couple the electrode layers. The technique can therefore be used for developing high-performance planar oxide electronic devices such as magnetic tunnel junctions and quantum well structures that depend on magnetically and electronically sharp heterointerfaces.

  10. Ferromagnetism and interlayer exchange coupling in thin metallic films

    Energy Technology Data Exchange (ETDEWEB)

    Kienert, Jochen

    2008-07-15

    This thesis is concerned with the ferromagnetic Kondo lattice (s-d,s-f) model for film geometry. The spin-fermion interaction of this model refers to substances in which localized spins interact with mobile charge carriers like in (dilute) magnetic semiconductors, manganites, or rare-earth compounds. The carrier-mediated, indirect interaction between the localized spins comprises the long-range, oscillatory RKKY exchange interaction in the weak-coupling case and the short-range doubleexchange interaction for strong spin-fermion coupling. Both limits are recovered in this work by mapping the problem onto an effective Heisenberg model. The influence of reduced translational symmetry on the effective exchange interaction and on the magnetic properties of the ferromagnetic Kondo lattice model is investigated. Curie temperatures are obtained for different parameter constellations. The consequences of charge transfer and of lattice relaxation on the magnetic stability at the surface are considered. Since the effective exchange integrals are closely related to the electronic structure in terms of the density of states and of the kinetic energy, the discussion is based on the modifications of these quantities in the dimensionally-reduced case. The important role of spin waves for thin film and surface magnetism is demonstrated. Interlayer exchange coupling represents a particularly interesting and important manifestation of the indirect interaction among localized magnetic moments. The coupling between monatomic layers in thin films is studied in the framework of an RKKY approach. It is decisively determined by the type of in-plane and perpendicular dispersion of the charge carriers and is strongly suppressed above a critical value of the Fermi energy. Finally, the temperature-dependent magnetic stability of thin interlayer-coupled films is addressed and the conditions for a temperature-driven magnetic reorientation transition are discussed. (orig.)

  11. Aqueous turbulence structure immediately adjacent to the air - water interface and interfacial gas exchange

    Science.gov (United States)

    Wang, Binbin

    Air-sea interaction and the interfacial exchange of gas across the air-water interface are of great importance in coupled atmospheric-oceanic environmental systems. Aqueous turbulence structure immediately adjacent to the air-water interface is the combined result of wind, surface waves, currents and other environmental forces and plays a key role in energy budgets, gas fluxes and hence the global climate system. However, the quantification of turbulence structure sufficiently close to the air-water interface is extremely difficult. The physical relationship between interfacial gas exchange and near surface turbulence remains insufficiently investigated. This dissertation aims to measure turbulence in situ in a complex environmental forcing system on Lake Michigan and to reveal the relationship between turbulent statistics and the CO2 flux across the air-water interface. The major objective of this dissertation is to investigate the physical control of the interfacial gas exchange and to provide a universal parameterization of gas transfer velocity from environmental factors, as well as to propose a mechanistic model for the global CO2 flux that can be applied in three dimensional climate-ocean models. Firstly, this dissertation presents an advanced measurement instrument, an in situ free floating Particle Image Velocimetry (FPIV) system, designed and developed to investigate the small scale turbulence structure immediately below the air-water interface. Description of hardware components, design of the system, measurement theory, data analysis procedure and estimation of measurement error were provided. Secondly, with the FPIV system, statistics of small scale turbulence immediately below the air-water interface were investigated under a variety of environmental conditions. One dimensional wave-number spectrum and structure function sufficiently close to the water surface were examined. The vertical profiles of turbulent dissipation rate were intensively studied

  12. Foundations and latest advances in replica exchange transition interface sampling

    Science.gov (United States)

    Cabriolu, Raffaela; Skjelbred Refsnes, Kristin M.; Bolhuis, Peter G.; van Erp, Titus S.

    2017-10-01

    Nearly 20 years ago, transition path sampling (TPS) emerged as an alternative method to free energy based approaches for the study of rare events such as nucleation, protein folding, chemical reactions, and phase transitions. TPS effectively performs Monte Carlo simulations with relatively short molecular dynamics trajectories, with the advantage of not having to alter the actual potential energy surface nor the underlying physical dynamics. Although the TPS approach also introduced a methodology to compute reaction rates, this approach was for a long time considered theoretically attractive, providing the exact same results as extensively long molecular dynamics simulations, but still expensive for most relevant applications. With the increase of computer power and improvements in the algorithmic methodology, quantitative path sampling is finding applications in more and more areas of research. In particular, the transition interface sampling (TIS) and the replica exchange TIS (RETIS) algorithms have, in turn, improved the efficiency of quantitative path sampling significantly, while maintaining the exact nature of the approach. Also, open-source software packages are making these methods, for which implementation is not straightforward, now available for a wider group of users. In addition, a blooming development takes place regarding both applications and algorithmic refinements. Therefore, it is timely to explore the wide panorama of the new developments in this field. This is the aim of this article, which focuses on the most efficient exact path sampling approach, RETIS, as well as its recent applications, extensions, and variations.

  13. Magnetic behavior of partially exchange-coupled particles

    International Nuclear Information System (INIS)

    Oliva, M.I.; Bercoff, P.G.; Bertorello, H.R.

    2005-01-01

    A system of particle pairs with partial exchange coupling is studied, considering identical particles and a fixed angle between their anisotropy axes. The energy of each pair is calculated in terms of the extent of interaction, β, as a function of the applied demagnetizing field. Using the probability per unit time for the inversion of magnetization, the coercive field H c and the viscosity S of the system are calculated. An unexpected result is that fully coupled particles are more stable against temperature than the uncoupled particles

  14. Exchangers man the pumps: Functional interplay between proton pumps and proton-coupled Ca(2+) exchangers

    Science.gov (United States)

    Tonoplast-localised proton-coupled Ca(2+) transporters encoded by cation/H(+) exchanger (CAX) genes play a critical role in sequestering Ca(2+) into the vacuole. These transporters may function in coordination with Ca(2+) release channels, to shape stimulus-induced cytosolic Ca(2+) elevations. Recen...

  15. Experimental study of energy exchanges between two coupled granular gases

    OpenAIRE

    Chastaing , J.-Y; Géminard , J.-C; Naert , A

    2016-01-01

    International audience; We report on the energy exchanges between two granular gases of different densities coupled electrome-chanically by immersed blades attached to dc motors. Zeroing the energy flux between the two subsystems, we demonstrate that an immersed blade is a convenient way to assess the properties of the granular gases, provided that the dissipation in the motor is properly taken into account. In addition, when the two gases have different densities, the fluctuations of the ene...

  16. Exchange bias induced at a Co2FeAl0.5Si0.5/Cr interface

    International Nuclear Information System (INIS)

    Yu, C N T; Vick, A J; Inami, N; Ono, K; Frost, W; Hirohata, A

    2017-01-01

    In order to engineer the strength of an exchange bias in a cubic Heusler alloy layer, crystalline strain has been induced at a ferromagnet/antiferromagnet interface by their lattice mismatch in addition to the conventional interfacial exchange coupling between them. Such interfaces have been formed in (Co 2 FeAl 0.5 Si 0.5 (CFAS)/Cr) 3 structures grown by ultrahigh vacuum molecular beam epitaxy. The magnetic and structural properties have been characterised to investigate the exchange interactions at the CFAS/Cr interfaces. Due to the interfacial lattice mismatch of 1.4%, the maximum offset of 18 Oe in a magnetisation curve has been measured for the case of a CFAS (2 nm)/Cr (0.9 nm) interface at 193 K. The half-metallic property of CFAS has been observed to remain unchanged, which agrees with the theoretical prediction by Culbert et al (2008 J. Appl. Phys . 103 07D707). Such a strain-induced exchange bias may provide insight of the interfacial interactions and may offer a wide flexibility in spintronic device design. (paper)

  17. Switching behaviour of coupled antiferro- and ferromagnetic systems: exchange bias

    Energy Technology Data Exchange (ETDEWEB)

    Lindgaard, Per-Anker [Materials Research Division, Risoe National Laboratory for Sustainable Energy, Danish Technical University, DK-4000 Roskilde (Denmark)

    2009-11-25

    The switching behaviour, under reversal of an external field, of a simple, ideal magnetic nanoparticle is studied and the interplay between antiferromagnets and ferromagnets elucidated. It is found that the switching between various multi- q ordering in fcc antiferromagnets (as found theoretically in NiO nanoparticles (Kodama and Berkowitz 1999 Phys. Rev. B 59 6321 and Lindgaard 2003 J. Magn. Magn. Mater. 266 88)) in a field severely limits the exchange biasing potential. The interface between the different magnets is found to be that originally assumed by Meiklejohn and Bean (1956 Phys. Rev. 102 1413).

  18. Vortex dynamics mediated by exchange coupling in permalloy double disks

    International Nuclear Information System (INIS)

    Liu Yan; Hu Yong; Du An

    2012-01-01

    The dynamics of magnetic vortices in double disks coupled with a bridge are studied by micromagnetic simulations. There are three types of magnetic configurations being found, which depend on the size of the bridge and the chiralities of the vortices. The exchange coupling between the vortices, which is mediated by the magnetizations in the bridge, influences the trajectories and oscillation frequencies of the vortices. Moreover, the frequency depends on the configurations of the double disks and the bridge size. - Highlights: ► Dynamics of vortices in double Permalloy disks coupled with a bridge are studied. ► Three types of equilibrium configurations are observed for the model. ► Oscillation of the cores depends on the magnetic configuration of the double disks. ► Variation of oscillating frequency with bridge length depends on polarity combination. ► Oscillating frequency decreases with the increasing of the bridge width.

  19. Antiferromagnetic exchange coupling measurements on single Co clusters

    Science.gov (United States)

    Wernsdorfer, W.; Leroy, D.; Portemont, C.; Brenac, A.; Morel, R.; Notin, L.; Mailly, D.

    2009-03-01

    We report on single-cluster measurements of the angular dependence of the low-temperature ferromagnetic core magnetization switching field in exchange-coupled Co/CoO core-shell clusters (4 nm) using a micro-bridge DC superconducting quantum interference device (μ-SQUID). It is observed that the coupling with the antiferromagnetic shell induces modification in the switching field for clusters with intrinsic uniaxial anisotropy depending on the direction of the magnetic field applied during the cooling. Using a modified Stoner-Wohlfarth model, it is shown that the core interacts with two weakly coupled and asymmetrical antiferromagnetic sublattices. Ref.: C. Portemont, R. Morel, W. Wernsdorfer, D. Mailly, A. Brenac, and L. Notin, Phys. Rev. B 78, 144415 (2008)

  20. Structure and magnetic exchange coupling of iron based trilayers

    International Nuclear Information System (INIS)

    Mendus, T.

    1998-12-01

    A study of the structural and magnetic properties of Fe based magnetic trilayers is presented. Sample preparation conditions were altered to achieve the best growth conditions and their effect on the magnetic properties determined. Structural information was obtained from RHEED, AES, STM and MEIS; this is believed to be the first time that MEIS has been used to look at this sort of sample. Magnetic characterisation was determined by MOKE with particular interest paid to the biquadratic coupling. The determination of magnetic coupling as a function of sample morphology was studied oil a series of Fe/Cr/Fe samples. Fe/Au/Fe samples oil MgO substrates were also prepared to facilitate MEIS studies. Results indicate that tile fluctuation model best describes tile observed biquadratic coupling in Fe/Cr/Fe trilayers and that the presence of clean, sharp interfaces is required. Annealing and growth at elevated temperature cause interdiffusion at the interfaces, weakening the biquadratic coupling. MEIS structural data from MgO/Fe/Au/Fe samples shows that tile layer structure is dependent oil thickness. There is an apparent reorganisation of tile Au interlayer between a 'bcc'-Iike phase towards tile bulk fcc phase as the layer thickness increases. MEIS is shown to be a very sensitive probe of the crystalline quality and is a powerful probe for the determination of postdeposition sample morphology. Results from an EC collaboration investigating Co/Cr/Co trilayers are also presented. They showed that interlayer coupling and anisotropy of the samples were very sensitive to the preparation conditions. A decrease in the coupling strength is found for sample growth under non-ideal conditions (growth in an applied field, growth at an angle and delays between layer growth). (author)

  1. The phase diagrams and the order parameters of the diluted transverse superlattice with antiferromagnetic interface coupling

    International Nuclear Information System (INIS)

    Oubelkacem, A.; El Aouad, N.; Benaboud, A.; Saber, M.

    2004-01-01

    Using the effective field theory with a probability distribution technique that accounts for the self-spin correlation functions, the magnetic properties of the Ising superlattice consisting of two ferromagnetic materials A and B, with L a layers of diluted spins S a =((1)/(2)) and L b layers of diluted spins S b =1 in an applied transverse field Ω with antiferromagnetic interface coupling are examined. For fixed values of the reduced exchange interactions and the concentration c of magnetic atoms, the phase diagrams and the total magnetization for the superlattice are studied as a function of the transverse field and the temperature. We find a number of characteristic phenomena. In particular, the effect of the concentration c of magnetic atoms, the interlayer coupling and the transverse field on both the compensation temperature and the magnetization profiles are clarified. Some of them may be related to the experimental works of rare-earth (RE)/transition metal (TM) multilayer films

  2. The phase diagrams and the order parameters of the diluted superlattice with antiferromagnetic interface coupling

    International Nuclear Information System (INIS)

    Oubelkacem, A.; El Aouad, N.; Bentaleb, M.; Laaboudi, B.; Saber, M.

    2004-01-01

    Using the effective field theory with a probability distribution technique that accounts for the self-spin correlation functions, the magnetic properties of the diluted Ising superlattice consisting of two ferromagnetic materials A and B, with L a layers of diluted spins S a =((1)/(2)) and L b layers of diluted spins S b =1 with antiferromagnetic interface coupling are examined. For fixed values of the reduced exchange interactions and the concentration c of magnetic atoms, the phase diagrams, the two sublattice magnetizations and the total magnetization for the superlattice with the same spin S a =S b =((1)/(2)) and for S a =((1)/(2)), S b =1 are studied as a function of the temperature. We find a number of characteristic phenomena. In particular, the effect of the concentration c of magnetic atoms, the interlayer coupling and the layer thickness on both the compensation temperature and the magnetization profiles are clarified

  3. Accurate gradient approximation for complex interface problems in 3D by an improved coupling interface method

    Energy Technology Data Exchange (ETDEWEB)

    Shu, Yu-Chen, E-mail: ycshu@mail.ncku.edu.tw [Department of Mathematics, National Cheng Kung University, Tainan 701, Taiwan (China); Mathematics Division, National Center for Theoretical Sciences (South), Tainan 701, Taiwan (China); Chern, I-Liang, E-mail: chern@math.ntu.edu.tw [Department of Applied Mathematics, National Chiao Tung University, Hsin Chu 300, Taiwan (China); Department of Mathematics, National Taiwan University, Taipei 106, Taiwan (China); Mathematics Division, National Center for Theoretical Sciences (Taipei Office), Taipei 106, Taiwan (China); Chang, Chien C., E-mail: mechang@iam.ntu.edu.tw [Institute of Applied Mechanics, National Taiwan University, Taipei 106, Taiwan (China); Department of Mathematics, National Taiwan University, Taipei 106, Taiwan (China)

    2014-10-15

    Most elliptic interface solvers become complicated for complex interface problems at those “exceptional points” where there are not enough neighboring interior points for high order interpolation. Such complication increases especially in three dimensions. Usually, the solvers are thus reduced to low order accuracy. In this paper, we classify these exceptional points and propose two recipes to maintain order of accuracy there, aiming at improving the previous coupling interface method [26]. Yet the idea is also applicable to other interface solvers. The main idea is to have at least first order approximations for second order derivatives at those exceptional points. Recipe 1 is to use the finite difference approximation for the second order derivatives at a nearby interior grid point, whenever this is possible. Recipe 2 is to flip domain signatures and introduce a ghost state so that a second-order method can be applied. This ghost state is a smooth extension of the solution at the exceptional point from the other side of the interface. The original state is recovered by a post-processing using nearby states and jump conditions. The choice of recipes is determined by a classification scheme of the exceptional points. The method renders the solution and its gradient uniformly second-order accurate in the entire computed domain. Numerical examples are provided to illustrate the second order accuracy of the presently proposed method in approximating the gradients of the original states for some complex interfaces which we had tested previous in two and three dimensions, and a real molecule ( (1D63)) which is double-helix shape and composed of hundreds of atoms.

  4. Kerr microscopy study of exchange-coupled FePt/Fe exchange spring magnets

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Zaineb; Kumar, Dileep [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452001 (India); Reddy, V. Raghavendra, E-mail: varimalla@yahoo.com [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452001 (India); Gupta, Ajay [Amity Center for Spintronic Materials, Amity University, Noida 201303 (India)

    2017-05-15

    Magnetization reversal and magnetic microstructure of top soft magnetic layer (Fe) in exchange spring coupled L1{sub 0} FePt/Fe is studied using high resolution Kerr microscopy. With remnant state of the hard magnetic layer (L1{sub 0} FePt) as initial condition, magnetization loops along with magnetic domains are recorded for the top soft magnetic layer (Fe) using Kerr microscopy. Considerable shifting of Fe layer hysteresis loop from center which is similar to exchange bias phenomena is observed. It is also observed that one can tune the magnitude of hysteresis shift by reaching the remanent state from different saturating fields (H{sub SAT}) and also by varying the angle between measuring field and H{sub SAT}. The hysteresis loops and magnetic domains of top soft Fe layer demonstrate unambiguously that soft magnetic layer at remanent state in such exchange coupled system is having unidirectional anisotropy. An analogy is drawn and the observations are explained in terms of established model of exchange bias phenomena framed for field-cooled ferromagnetic - antiferromagnetic bilayer systems. - Highlights: • Kerr microscopy of top soft magnetic Fe layer in exchange spring coupled L1{sub 0} FePt (30 nm)/Fe (22 nm) is reported. • Considerable shifting of Fe layer hysteresis loop from center which is similar to exchange bias phenomena is observed. • Tuneable nature of magnitude of hysteresis shift is shown. • It is unambiguously shown that the top soft Fe magnetic layer at remanent state is having unidirectional anisotropy.

  5. Interface-engineered oxygen octahedral coupling in manganite heterostructures

    Science.gov (United States)

    Huijben, M.; Koster, G.; Liao, Z. L.; Rijnders, G.

    2017-12-01

    Control of the oxygen octahedral coupling (OOC) provides a large degree of freedom to manipulate physical phenomena in complex oxide heterostructures. Recently, local tuning of the tilt angle has been found to control the magnetic anisotropy in ultrathin films of manganites and ruthenates, while symmetry control can manipulate the metal insulator transition in nickelate thin films. The required connectivity of the octahedra across the heterostructure interface enforces a geometric constraint to the 3-dimensional octahedral network in epitaxial films. Such geometric constraint will either change the tilt angle to retain the connectivity of the corner shared oxygen octahedral network or guide the formation of a specific symmetry throughout the epitaxial film. Here, we will discuss the control of OOC in manganite heterostructures by interface-engineering. OOC driven magnetic and transport anisotropies have been realized in LSMO/NGO heterostructures. Competition between the interfacial OOC and the strain further away from the interface leads to a thickness driven sharp transition of the anisotropic properties. Furthermore, octahedral relaxation leading to a change of p-d hybridization driven by interfacial OOC appears to be the strongest factor in thickness related variations of magnetic and transport properties in epitaxial LSMO films on NGO substrates. The results unequivocally link the atomic structure near the interfaces to the macroscopic properties. The strong correlation between a controllable oxygen network and the functionalities will have significant impact on both fundamental research and technological application of correlated perovskite heterostructures. By controlling the interfacial OOC, it is possible to pattern in 3 dimensions the magnetization to achieve non-collinear magnetization in both in-plane and out of plane directions, thus making the heterostructures promising for application in orthogonal spin transfer devices, spin oscillators, and low

  6. Exchangers man the pumps: Functional interplay between proton pumps and proton-coupled Ca2+ exchangers

    OpenAIRE

    Barkla, Bronwyn J; Hirschi, Kendal D; Pittman, Jon K

    2008-01-01

    Tonoplast-localised proton-coupled Ca2+ transporters encoded by cation/H+ exchanger (CAX) genes play a critical role in sequestering Ca2+ into the vacuole. These transporters may function in coordination with Ca2+ release channels, to shape stimulus-induced cytosolic Ca2+ elevations. Recent analysis of Arabidopsis CAX knockout mutants, particularly cax1 and cax3, identified a variety of phenotypes including sensitivity to abiotic stresses, which indicated that these transporters might play a ...

  7. Enhanced optical coupling and Raman scattering via microscopic interface engineering

    Science.gov (United States)

    Thompson, Jonathan V.; Hokr, Brett H.; Kim, Wihan; Ballmann, Charles W.; Applegate, Brian E.; Jo, Javier A.; Yamilov, Alexey; Cao, Hui; Scully, Marlan O.; Yakovlev, Vladislav V.

    2017-11-01

    Spontaneous Raman scattering is an extremely powerful tool for the remote detection and identification of various chemical materials. However, when those materials are contained within strongly scattering or turbid media, as is the case in many biological and security related systems, the sensitivity and range of Raman signal generation and detection is severely limited. Here, we demonstrate that through microscopic engineering of the optical interface, the optical coupling of light into a turbid material can be substantially enhanced. This improved coupling facilitates the enhancement of the Raman scattering signal generated by molecules within the medium. In particular, we detect at least two-orders of magnitude more spontaneous Raman scattering from a sample when the pump laser light is focused into a microscopic hole in the surface of the sample. Because this approach enhances both the interaction time and interaction region of the laser light within the material, its use will greatly improve the range and sensitivity of many spectroscopic techniques, including Raman scattering and fluorescence emission detection, inside highly scattering environments.

  8. Models of information exchange between radio interfaces of Wi-Fi group of standards

    Science.gov (United States)

    Litvinskaya, O. S.

    2018-05-01

    This paper offers models of information exchange between radio interfaces of the Wi-Fi group of standards by the example of a real facility management system for the oil and gas industry. Interaction between the MU-MIMO and MIMO technologies is analyzed. An optimal variant of information exchange is proposed.

  9. Tailor-made nano-structured materials for perpendicular recording media and head-precise control of direct/indirect exchange coupling

    International Nuclear Information System (INIS)

    Takahashi, Migaku; Tsunoda, Masakiyo; Saito, Shin

    2009-01-01

    Tailor-made nano-structured spin materials obtained by precisely controlled nano-scale fabrication technologies for use in ultra-high density hard disk drives (HDDs), as well as an understanding of their nanomagnetics, are essential from the view point of materials, processes, and physics. Artificial control of the exchange coupling among ferromagnetic layers through the RKKY interaction (indirect) and direct exchange coupling represented as the exchange bias at the ferromagnetic (FM)/antiferromagnetic (AFM) interface are of great interest and have received significant attention to induce new modulated spin structures in conventional simple FM materials. In particular, soft magnetic under layer (SUL) with strong synthetic antiferromagnetic (SAF) coupling between two adjacent soft magnetic layers, exchange coupled stacked media introducing exchange coupling between FM layers and giant exchange anisotropy at the FM/AFM interface have attracted significant attention from the view point of applications. Within the framework of the present paper, we discuss future technical trends for SUL, granular media and the spin-valve head from the viewpoint of direct and/or indirect exchange coupling based on our recent results

  10. Induced magnetic structure in exchange-coupled ferro-/antiferromagnet thin films

    Science.gov (United States)

    Morales, Rafael

    2007-03-01

    The most prominent feature observed in exchange-coupled ferromagnetic/ antiferromagnetic (FM/AF) bilayers is the so-called exchange bias field (HEB), i.e. the shift of the hysteresis loop along the magnetic field axis. However the exchange bias phenomenon can induce other interesting effects on the FM. In this talk we show two methods to establish a bi-domain state in the FM, due to the coexistence of domains with opposite sign of HEB [1-3]. Magneto-optical, polarized neutron and soft X-ray measurements show that this lateral structure becomes more complex for low magnetocrystalline anisotropy materials where a spin depth profile is created in the FM due to the exchange coupling with the AF [4-6]. The internal magnetic structure in the AF and its role on exchange bias has also been investigated using FM/AF/FM trilayers. These studies demonstrate that the bulk spin configuration in the AF plays a crucial role in the pinning of uncompensated spins at the interface thus determining the HEB . Supported by the US-DOE, European Marie-Curie-OIF and the Alfred P. Sloan Foundation. [1] O. Petracic et al. Appl. Phys. Lett. 87, 222509 (2005) [2] I. V. Roshchin et al. Europhys. Lett. 71, 297 (2005) [3] J. Olamit et al. Phys. Rev. B 72, 012408 (2005) [4] R. Morales et al. Appl. Phys. Lett. 89, 072504 (2006) [5] S. Roy et al. Phys. Rev. Lett. 95, 047201 (2005) [6] Z-P. Li et al. Phys. Rev. Lett. 96, 217205 (2006)

  11. Exchangers man the pumps: Functional interplay between proton pumps and proton-coupled Ca exchangers.

    Science.gov (United States)

    Barkla, Bronwyn J; Hirschi, Kendal D; Pittman, Jon K

    2008-05-01

    Tonoplast-localised proton-coupled Ca(2+) transporters encoded by cation/H(+)exchanger (CAX) genes play a critical role in sequestering Ca(2+) into the vacuole. These transporters may function in coordination with Ca(2+) release channels, to shape stimulus-induced cytosolic Ca(2+) elevations. Recent analysis of Arabidopsis CAX knockout mutants, particularly cax1 and cax3, identified a variety of phenotypes including sensitivity to abiotic stresses, which indicated that these transporters might play a role in mediating the plant's stress response. A common feature of these mutants was the perturbation of H(+)-ATPase activity at both the tonoplast and the plasma membrane, suggesting a tight interplay between the Ca(2+)/H(+) exchangers and H(+) pumps. We speculate that indirect regulation of proton flux by the exchangers may be as important as the direct regulation of Ca(2+) flux. These results suggest cautious interpretation of mutant Ca(2+)/H(+) exchanger phenotypes that may be due to either perturbed Ca(2+) or H(+) transport.

  12. Role of an ultrathin platinum seed layer in antiferromagnet-based perpendicular exchange coupling and its electrical manipulation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.Y., E-mail: wangyy@buaa.edu.cn [Department of Physics, Beihang University, Beijing 100191 (China); Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Song, C., E-mail: songcheng@mail.tsinghua.edu.cn [Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Zhang, J.Y. [Department of Physics, Beihang University, Beijing 100191 (China); Pan, F. [Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2017-04-15

    The requirement for low-power consumption advances the development of antiferromagnetic (AFM) spintronics manipulated by electric fields. Here we report an electrical manipulation of metallic AFM moments within IrMn/[Co/Pt] by interface engineering, where ultrathin non-magnetic metals are highlighted between IrMn and ferroelectric substrates. Ultrathin Pt seed layers are proved to be vital in elevating the blocking temperature and enhancing the perpendicular exchange coupling through modulating the domain structures of as-prepared IrMn AFM. Further electrical manipulations of perpendicular magnetic anisotropy crucially verify the indispensable role of pre-deposited ultrathin Pt layers in modulating IrMn antiferromagnetic moments, which is confirmed by the intimate correlation between the electrically manipulating AFM and improving its blocking temperature. Instead of immediate contact between IrMn AFM and ferroelectric substrates in a conventional way, interface engineering by adopting ultrathin seed layers here adds a new twist to the electrical modulation of AFM metals. This would provide scientific basis on how to manipulate AFM moments and optimize the design of practical AFM spintronics. - Highlights: • An alternative for manipulating antiferromagnet by interface engineering is provided. • Ultrathin Pt seed layers are vital in elevating the blocking temperature of IrMn. • Perpendicular exchange coupling in IrMn/[Co/Pt] can be modulated by seed layers. • Ultrathin Pt seed layers enable electrical control of perpendicular exchange coupling.

  13. Role of an ultrathin platinum seed layer in antiferromagnet-based perpendicular exchange coupling and its electrical manipulation

    International Nuclear Information System (INIS)

    Wang, Y.Y.; Song, C.; Zhang, J.Y.; Pan, F.

    2017-01-01

    The requirement for low-power consumption advances the development of antiferromagnetic (AFM) spintronics manipulated by electric fields. Here we report an electrical manipulation of metallic AFM moments within IrMn/[Co/Pt] by interface engineering, where ultrathin non-magnetic metals are highlighted between IrMn and ferroelectric substrates. Ultrathin Pt seed layers are proved to be vital in elevating the blocking temperature and enhancing the perpendicular exchange coupling through modulating the domain structures of as-prepared IrMn AFM. Further electrical manipulations of perpendicular magnetic anisotropy crucially verify the indispensable role of pre-deposited ultrathin Pt layers in modulating IrMn antiferromagnetic moments, which is confirmed by the intimate correlation between the electrically manipulating AFM and improving its blocking temperature. Instead of immediate contact between IrMn AFM and ferroelectric substrates in a conventional way, interface engineering by adopting ultrathin seed layers here adds a new twist to the electrical modulation of AFM metals. This would provide scientific basis on how to manipulate AFM moments and optimize the design of practical AFM spintronics. - Highlights: • An alternative for manipulating antiferromagnet by interface engineering is provided. • Ultrathin Pt seed layers are vital in elevating the blocking temperature of IrMn. • Perpendicular exchange coupling in IrMn/[Co/Pt] can be modulated by seed layers. • Ultrathin Pt seed layers enable electrical control of perpendicular exchange coupling.

  14. Magnetic short range order and the exchange coupling in magnets

    International Nuclear Information System (INIS)

    Antropov, V.P.

    2006-01-01

    We discuss our recent results of time-dependent density functional simulations of magnetic properties of Fe and Ni at finite temperatures. These results indicated that a strong magnetic short range order is responsible for the magnetic properties of elementary Ni and any itinerant magnet in general. We demonstrated that one can use the value of the magnetic short range order parameter to produce new quantitative classification of magnets. We also discuss the nature of the exchange coupling and its connection with the short range order. The spin-wave like propagating and diffusive excitations in paramagnetic localized systems with small short range order have been predicted while in the itinerant systems the short range order is more complicated. The possible smallness of the quantum factor in the itinerant magnets with short range order is discussed

  15. Wealth distribution of simple exchange models coupled with extremal dynamics

    Science.gov (United States)

    Bagatella-Flores, N.; Rodríguez-Achach, M.; Coronel-Brizio, H. F.; Hernández-Montoya, A. R.

    2015-01-01

    Punctuated Equilibrium (PE) states that after long periods of evolutionary quiescence, species evolution can take place in short time intervals, where sudden differentiation makes new species emerge and some species extinct. In this paper, we introduce and study the effect of punctuated equilibrium on two different asset exchange models: the yard sale model (YS, winner gets a random fraction of a poorer player's wealth) and the theft and fraud model (TF, winner gets a random fraction of the loser's wealth). The resulting wealth distribution is characterized using the Gini index. In order to do this, we consider PE as a perturbation with probability ρ of being applied. We compare the resulting values of the Gini index at different increasing values of ρ in both models. We found that in the case of the TF model, the Gini index reduces as the perturbation ρ increases, not showing dependence with the agents number. While for YS we observe a phase transition which happens around ρc = 0.79. For perturbations ρ <ρc the Gini index reaches the value of one as time increases (an extreme wealth condensation state), whereas for perturbations greater than or equal to ρc the Gini index becomes different to one, avoiding the system reaches this extreme state. We show that both simple exchange models coupled with PE dynamics give more realistic results. In particular for YS, we observe a power low decay of wealth distribution.

  16. Energy exchange in strongly coupled plasmas with electron drift

    International Nuclear Information System (INIS)

    Akbari-Moghanjoughi, M.; Ghorbanalilu, M.

    2015-01-01

    In this paper, the generalized viscoelastic collisional quantum hydrodynamic model is employed in order to investigate the linear dielectric response of a quantum plasma in the presence of strong electron-beam plasma interactions. The generalized Chandrasekhar's relativistic degeneracy pressure together with the electron-exchange and Coulomb interaction effects are taken into account in order to extend current research to a wide range of plasma number density relevant to big planetary cores and astrophysical compact objects. The previously calculated shear viscosity and the electron-ion collision frequencies are used for strongly coupled ion fluid. The effect of the electron-beam velocity on complex linear dielectric function is found to be profound. This effect is clearly interpreted in terms of the wave-particle interactions and their energy-exchange according to the sign of the imaginary dielectric function, which is closely related to the wave attenuation coefficient in plasmas. Such kinetic effect is also shown to be in close connection with the stopping power of a charged-particle beam in a quantum plasma. The effect of many independent plasma parameters, such as the ion charge-state, electron beam-velocity, and relativistic degeneracy, is shown to be significant on the growing/damping of plasma instability or energy loss/gain of the electron-beam

  17. SWATMOD-PREP: Graphical user interface for preparing coupled SWAT-modflow simulations

    Science.gov (United States)

    This paper presents SWATMOD-Prep, a graphical user interface that couples a SWAT watershed model with a MODFLOW groundwater flow model. The interface is based on a recently published SWAT-MODFLOW code that couples the models via mapping schemes. The spatial layout of SWATMOD-Prep guides the user t...

  18. All-Silicon Switchable Magnetoelectric Effect through Interlayer Exchange Coupling.

    Science.gov (United States)

    Liu, Hang; Sun, Jia-Tao; Fu, Hui-Xia; Sun, Pei-Jie; Feng, Y P; Meng, Sheng

    2017-07-19

    The magnetoelectric (ME) effect originating from the effective coupling between electric field and magnetism is an exciting frontier in nanoscale science such as magnetic tunneling junction (MTJ), ferroelectric/piezoelectric heterojunctions etc. The realization of switchable ME effect under external electric field in d0 semiconducting materials of single composition is needed especially for all-silicon spintronics applications because of its natural compatibility with current industry. We employ density functional theory (DFT) to reveal that the pristine Si(111)-3×3 R30° (Si3 hereafter) reconstructed surfaces of thin films with a thickness smaller than eleven bilayers support a sizeable linear ME effect with switchable direction of magnetic moment under external electric field. This is achieved through the interlayer exchange coupling effect in the antiferromagnetic regime, where the spin-up and spin-down magnetized density is located on opposite surfaces of Si3 thin films. The obtained coefficient for the linear ME effect can be four times larger than that of ferromagnetic Fe films, which fail to have the reversal switching capabilities. The larger ME effect originates from the spin-dependent screening of the spin-polarized Dirac fermion. The prediction will promote the realization of well-controlled and switchable data storage in all-silicon electronics. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Exchange coupling in permalloy/BiFeO3 heterostructures

    Science.gov (United States)

    Heron, John; Wang, Chen; Carlton, David; Nowakowski, Mark; Gajek, Martin; Awschalom, David; Bokor, Jeff; Ralph, Dan; Ramesh, R.

    2010-03-01

    BiFeO3 is a ferroelectric and antiferromagnetic multiferroic with the ferroelectric and antiferromagnetic order parameters coupled at room temperature. This coupling results in the reorientation of the ferroelectric and magnetic domains as applied voltages switch the electric polarization. Previous studies using ferromagnet/BiFeO3 heterostructures have shown that the anisotropy of the ferromagnetic layer can be tuned by the ferroelectric domain structure of the BiFeO3 film [1, 2]. The physical mechanism driving this exchange bias with BiFeO3 is still under investigation. We use patterned permalloy structures, with varying aspect ratios, on BiFeO3 thin films to investigate the physics of this interaction. The results of our studies using MFM, PEEM, and MOKE to understand this mechanism as a means to electric field control of magnetic structures will be presented. [4pt] [1] H. Bea et al., Physical Review Letters 100, 017204 (2008).[0pt] [2] L.W. Martin et al., Nanoletters 8, 2050 (2008).

  20. Magnetic properties of exchange-coupled trilayers of amorphous rare-earth-cobalt alloys

    International Nuclear Information System (INIS)

    Wuechner, S.; Toussaint, J.C.; Voiron, J.

    1997-01-01

    From amorphous thin films from alloys of rare earths (Gd, Sm), yttrium or zirconium with cobalt we have prepared trilayers with very clean interfaces appropriate for the study of magnetic coupling. The sandwiches were typically Y-Co/Gd-Co/Y-Co and Sm-Co/X/Sm-Co ' (X=Gd-Co, Co-Zr, Co). The three individual layers are coupled magnetically by exchange interactions between cobalt moments throughout the entire sample. This coupling associated with the specific properties of the given alloy (magnetic moment, anisotropy, coercivity) leads to ferrimagnetic or ferromagnetic structures of the magnetization of adjacent layers and to novel magnetization processes. For systems consisting of magnetically hard external layers with different coercivities and a soft central layer (Sm-Co/X/Sm-Co ' , X=Gd-Co, Co-Zr), the influence of the central layer close-quote s thickness and type of the material on coupling and magnetization processes have been studied quantitatively. Numerical simulations using a one-dimensional model for describing the magnetization processes observed in sandwich systems fit the magnetization curves of these model systems particularly well. copyright 1997 The American Physical Society

  1. Coupling compositional liquid gas Darcy and free gas flows at porous and free-flow domains interface

    Energy Technology Data Exchange (ETDEWEB)

    Masson, R., E-mail: roland.masson@unice.fr [LJAD, University Nice Sophia Antipolis, CNRS UMR 7351 (France); Team COFFEE INRIA Sophia Antipolis Méditerranée (France); Trenty, L., E-mail: laurent.trenty@andra.fr [Andra, Chatenay Malabry (France); Zhang, Y., E-mail: yumeng.zhang@unice.fr [LJAD, University Nice Sophia Antipolis, CNRS UMR 7351 (France); Team COFFEE INRIA Sophia Antipolis Méditerranée (France)

    2016-09-15

    This paper proposes an efficient splitting algorithm to solve coupled liquid gas Darcy and free gas flows at the interface between a porous medium and a free-flow domain. This model is compared to the reduced model introduced in [6] using a 1D approximation of the gas free flow. For that purpose, the gas molar fraction diffusive flux at the interface in the free-flow domain is approximated by a two point flux approximation based on a low-frequency diagonal approximation of a Steklov–Poincaré type operator. The splitting algorithm and the reduced model are applied in particular to the modelling of the mass exchanges at the interface between the storage and the ventilation galleries in radioactive waste deposits.

  2. Magneto-Spin-Orbit Graphene: Interplay between Exchange and Spin-Orbit Couplings.

    Science.gov (United States)

    Rybkin, Artem G; Rybkina, Anna A; Otrokov, Mikhail M; Vilkov, Oleg Yu; Klimovskikh, Ilya I; Petukhov, Anatoly E; Filianina, Maria V; Voroshnin, Vladimir Yu; Rusinov, Igor P; Ernst, Arthur; Arnau, Andrés; Chulkov, Evgueni V; Shikin, Alexander M

    2018-03-14

    A rich class of spintronics-relevant phenomena require implementation of robust magnetism and/or strong spin-orbit coupling (SOC) to graphene, but both properties are completely alien to it. Here, we for the first time experimentally demonstrate that a quasi-freestanding character, strong exchange splitting and giant SOC are perfectly achievable in graphene at once. Using angle- and spin-resolved photoemission spectroscopy, we show that the Dirac state in the Au-intercalated graphene on Co(0001) experiences giant splitting (up to 0.2 eV) while being by no means distorted due to interaction with the substrate. Our calculations, based on the density functional theory, reveal the splitting to stem from the combined action of the Co thin film in-plane exchange field and Au-induced Rashba SOC. Scanning tunneling microscopy data suggest that the peculiar reconstruction of the Au/Co(0001) interface is responsible for the exchange field transfer to graphene. The realization of this "magneto-spin-orbit" version of graphene opens new frontiers for both applied and fundamental studies using its unusual electronic bandstructure.

  3. Radon gas-exchange rate through the interface sea atmosphere in the coast

    International Nuclear Information System (INIS)

    Duenas, C.; Fernandez, M.C.; Perez Martinez, M.

    1985-01-01

    The Rn gas exchange velocity through the interface sea atmosphere has been estimated. Our measurements have been made in a sampler station located in Malaga bay, obtaining a mean value of 0.45 m/d. The corresponding magnitude of the thickness of boundary layer is 316μ. Experimental results are discussed. No clear relationship can be found between the gas exchange rate and wind speed. (author)

  4. Stokes-Darcy coupling for periodically curved interfaces

    DEFF Research Database (Denmark)

    Dobberschütz, Sören

    2014-01-01

    We investigate the boundary condition between a free fluid and a porous medium, where the interface between the two is given as a periodically curved structure. Using a coordinate transformation, we can employ methods of periodic homogenisation to derive effective boundary conditions for the tran...... be interpreted as a generalised law of Beavers and Joseph for curved interfaces....

  5. Study of switching behavior of exchange-coupled nanomagnets by transverse magnetization metrology

    Science.gov (United States)

    Dey, Himadri S.; Csaba, Gyorgy; Bernstein, Gary H.; Porod, Wolfgang

    2017-05-01

    We investigate the static switching modes of nanomagnets patterned from antiferromagnetically exchange-coupled magnetic multilayers, and compare them to nanomagnets having only dipole coupling between the ferromagnetic layers. Vibrating sample magnetometry experiments, supported by micromagnetic simulations, reveal two distinct switching mechanisms between the exchange-coupled and only dipole-coupled nanomagnets. The exchange-coupled nanomagnets exhibit gradual switching of the layers, dictated by the strong antiferromagnetic exchange coupling present between the layers. However, the layers of the only dipole-coupled nanomagnets show abrupt nucleation/growth type switching. A comprehensive understanding of the switching modes of such layered and patterned systems can add new insight into the reversal mechanisms of similar systems employed for spintronic and magneto-logic device applications.

  6. School Organization and Institutional Change: Exchange and Power in Loosely Coupled Systems.

    Science.gov (United States)

    Talbert, Joan E.

    This paper presents an exchange-theory view of school authority relations in order to identify patterns of coupling, or interdependencies, within school organizations and to analyze the potential for tighter coupling of administrative and teaching subsystems. The analysis proceeds from an argument that the social-exchange view of administrative…

  7. Exchange coupling interactions in a Fe6 complex: A theoretical study using density functional theory

    International Nuclear Information System (INIS)

    Cauchy, Thomas; Ruiz, Eliseo; Alvarez, Santiago

    2006-01-01

    Theoretical methods based on density functional theory have been employed to analyze the exchange interactions in an Fe 6 complex. The calculated exchange coupling constants are consistent with an S=5 ground state and agree well with those reported previously for other Fe III polynuclear complexes. Ferromagnetic interactions may appear through exchange pathways formed by two bridging hydroxo or oxo ligands

  8. SAIDE: A Semi-Automated Interface for Hydrogen/Deuterium Exchange Mass Spectrometry.

    Science.gov (United States)

    Villar, Maria T; Miller, Danny E; Fenton, Aron W; Artigues, Antonio

    2010-01-01

    Deuterium/hydrogen exchange in combination with mass spectrometry (DH MS) is a sensitive technique for detection of changes in protein conformation and dynamics. Since temperature, pH and timing control are the key elements for reliable and efficient measurement of hydrogen/deuterium content in proteins and peptides, we have developed a small, semiautomatic interface for deuterium exchange that interfaces the HPLC pumps with a mass spectrometer. This interface is relatively inexpensive to build, and provides efficient temperature and timing control in all stages of enzyme digestion, HPLC separation and mass analysis of the resulting peptides. We have tested this system with a series of standard tryptic peptides reconstituted in a solvent containing increasing concentration of deuterium. Our results demonstrate the use of this interface results in minimal loss of deuterium due to back exchange during HPLC desalting and separation. For peptides reconstituted in a buffer containing 100% deuterium, and assuming that all amide linkages have exchanged hydrogen with deuterium, the maximum loss of deuterium content is only 17% of the label, indicating the loss of only one deuterium molecule per peptide.

  9. Conformational analysis of g protein-coupled receptor signaling by hydrogen/deuterium exchange mass spectrometry.

    Science.gov (United States)

    Li, Sheng; Lee, Su Youn; Chung, Ka Young

    2015-01-01

    Conformational change and protein-protein interactions are two major mechanisms of membrane protein signal transduction, including G protein-coupled receptors (GPCRs). Upon agonist binding, GPCRs change conformation, resulting in interaction with downstream signaling molecules such as G proteins. To understand the precise signaling mechanism, studies have investigated the structural mechanism of GPCR signaling using X-ray crystallography, nuclear magnetic resonance (NMR), or electron paramagnetic resonance. In addition to these techniques, hydrogen/deuterium exchange mass spectrometry (HDX-MS) has recently been used in GPCR studies. HDX-MS measures the rate at which peptide amide hydrogens exchange with deuterium in the solvent. Exposed or flexible regions have higher exchange rates and excluded or ordered regions have lower exchange rates. Therefore, HDX-MS is a useful tool for studying protein-protein interfaces and conformational changes after protein activation or protein-protein interactions. Although HDX-MS does not give high-resolution structures, it analyzes protein conformations that are difficult to study with X-ray crystallography or NMR. Furthermore, conformational information from HDX-MS can help in the crystallization of X-ray crystallography by suggesting highly flexible regions. Interactions between GPCRs and downstream signaling molecules are not easily analyzed by X-ray crystallography or NMR because of the large size of the GPCR-signaling molecule complexes, hydrophobicity, and flexibility of GPCRs. HDX-MS could be useful for analyzing the conformational mechanism of GPCR signaling. In this chapter, we discuss details of HDX-MS for analyzing GPCRs using the β2AR-G protein complex as a model system. © 2015 Elsevier Inc. All rights reserved.

  10. Interface Magnetoelectric Coupling in Co/Pb(Zr,Ti)O3.

    Science.gov (United States)

    Vlašín, Ondřej; Jarrier, Romain; Arras, Rémi; Calmels, Lionel; Warot-Fonrose, Bénédicte; Marcelot, Cécile; Jamet, Matthieu; Ohresser, Philippe; Scheurer, Fabrice; Hertel, Riccardo; Herranz, Gervasi; Cherifi-Hertel, Salia

    2016-03-23

    Magnetoelectric coupling at multiferroic interfaces is a promising route toward the nonvolatile electric-field control of magnetization. Here, we use optical measurements to study the static and dynamic variations of the interface magnetization induced by an electric field in Co/PbZr0.2Ti0.8O3 (Co/PZT) bilayers at room temperature. The measurements allow us to identify different coupling mechanisms. We further investigate the local electronic and magnetic structure of the interface by means of transmission electron microscopy, soft X-ray magnetic circular dichroism, and density functional theory to corroborate the coupling mechanism. The measurements demonstrate a mixed linear and quadratic optical response to the electric field, which results from a magneto-electro-optical effect. We propose a decomposition method of the optical signal to discriminate between different components involved in the electric field-induced polarization rotation of the reflected light. This allows us to extract a signal that we can ascribe to interface magnetoelectric coupling. The associated surface magnetization exhibits a clear hysteretic variation of odd symmetry with respect to the electric field and nonzero remanence. The interface coupling is remarkably stable over a wide frequency range (1-50 kHz), and the application of a bias magnetic field is not necessary for the coupling to occur. These results show the potential of exploiting interface coupling with the prospect of optimizing the performance of magnetoelectric memory devices in terms of stability, as well as fast and dissipationless operation.

  11. All-optical measurement of interlayer exchange coupling in Fe/Pt/FePt thin films

    Science.gov (United States)

    Berk, C.; Ganss, F.; Jaris, M.; Albrecht, M.; Schmidt, H.

    2018-01-01

    Time Resolved Magneto Optic Kerr Effect spectroscopy was used to all-optically study the dynamics in exchange coupled Fe(10 nm)/Pt(x = 0-5 nm)/FePt (10 nm) thin films. As the Pt spacer decreases, the effective magnetization of the layers is seen to evolve towards the strong coupling limit where the two films can be described by a single effective magnetization. The coupling begins at x = 1.5 nm and reaches a maximum exchange coupling constant of 2.89 erg/cm2 at x = 0 nm. The films are ferromagnetically coupled at all Pt thicknesses in the exchange coupled regime (x ≤ 1.5 nm). A procedure for extracting the interlayer exchange constant by measuring the magnetic precession frequencies at multiple applied fields and angles is outlined. The dynamics are well reproduced using micromagnetic simulations.

  12. Interface requirements to couple thermal-hydraulic codes to 3D neutronic codes

    Energy Technology Data Exchange (ETDEWEB)

    Langenbuch, S.; Austregesilo, H.; Velkov, K. [GRS, Garching (Germany)] [and others

    1997-07-01

    The present situation of thermalhydraulics codes and 3D neutronics codes is briefly described and general considerations for coupling of these codes are discussed. Two different basic approaches of coupling are identified and their relative advantages and disadvantages are discussed. The implementation of the coupling for 3D neutronics codes in the system ATHLET is presented. Meanwhile, this interface is used for coupling three different 3D neutronics codes.

  13. Interface requirements to couple thermal-hydraulic codes to 3D neutronic codes

    International Nuclear Information System (INIS)

    Langenbuch, S.; Austregesilo, H.; Velkov, K.

    1997-01-01

    The present situation of thermalhydraulics codes and 3D neutronics codes is briefly described and general considerations for coupling of these codes are discussed. Two different basic approaches of coupling are identified and their relative advantages and disadvantages are discussed. The implementation of the coupling for 3D neutronics codes in the system ATHLET is presented. Meanwhile, this interface is used for coupling three different 3D neutronics codes

  14. A replica exchange transition interface sampling method with multiple interface sets for investigating networks of rare events

    Science.gov (United States)

    Swenson, David W. H.; Bolhuis, Peter G.

    2014-07-01

    The multiple state transition interface sampling (TIS) framework in principle allows the simulation of a large network of complex rare event transitions, but in practice suffers from convergence problems. To improve convergence, we combine multiple state TIS [J. Rogal and P. G. Bolhuis, J. Chem. Phys. 129, 224107 (2008)] with replica exchange TIS [T. S. van Erp, Phys. Rev. Lett. 98, 268301 (2007)]. In addition, we introduce multiple interface sets, which allow more than one order parameter to be defined for each state. We illustrate the methodology on a model system of multiple independent dimers, each with two states. For reaction networks with up to 64 microstates, we determine the kinetics in the microcanonical ensemble, and discuss the convergence properties of the sampling scheme. For this model, we find that the kinetics depend on the instantaneous composition of the system. We explain this dependence in terms of the system's potential and kinetic energy.

  15. Identification of the Dimer Exchange Interface of the Bacterial DNA Damage Response Protein UmuD.

    Science.gov (United States)

    Murison, David A; Timson, Rebecca C; Koleva, Bilyana N; Ordazzo, Michael; Beuning, Penny J

    2017-09-12

    The Escherichia coli SOS response, an induced DNA damage response pathway, confers survival on bacterial cells by providing accurate repair mechanisms as well as the potentially mutagenic pathway translesion synthesis (TLS). The umuD gene products are upregulated after DNA damage and play roles in both nonmutagenic and mutagenic aspects of the SOS response. Full-length UmuD is expressed as a homodimer of 139-amino-acid subunits, which eventually cleaves its N-terminal 24 amino acids to form UmuD'. The cleavage product UmuD' and UmuC form the Y-family polymerase DNA Pol V (UmuD' 2 C) capable of performing TLS. UmuD and UmuD' exist as homodimers, but their subunits can readily exchange to form UmuDD' heterodimers preferentially. Heterodimer formation is an essential step in the degradation pathway of UmuD'. The recognition sequence for ClpXP protease is located within the first 24 amino acids of full-length UmuD, and the partner of full-length UmuD, whether UmuD or UmuD', is degraded by ClpXP. To better understand the mechanism by which UmuD subunits exchange, we measured the kinetics of exchange of a number of fluorescently labeled single-cysteine UmuD variants as detected by Förster resonance energy transfer. Labeling sites near the dimer interface correlate with increased rates of exchange, indicating that weakening the dimer interface facilitates exchange, whereas labeling sites on the exterior decrease the rate of exchange. In most but not all cases, homodimer and heterodimer exchange exhibit similar rates, indicating that somewhat different molecular surfaces mediate homodimer exchange and heterodimer formation.

  16. On the coupling between molecular diffusion and solvation shell exchange

    DEFF Research Database (Denmark)

    Møller, Klaus Braagaard; Rey, Rossend; Masia, Marco

    2005-01-01

    The connection between diffusion and solvent exchanges between first and second solvation shells is studied by means of molecular dynamics simulations and analytic calculations, with detailed illustrations for water exchange for the Li+ and Na+ ions, and for liquid argon. First, two methods...

  17. Optically tunable spin-exchange energy at donor:acceptor interfaces in organic solar cells

    International Nuclear Information System (INIS)

    Li, Mingxing; Wang, Hongfeng; He, Lei; Zang, Huidong; Xu, Hengxing; Hu, Bin

    2014-01-01

    Spin-exchange energy is a critical parameter in controlling spin-dependent optic, electronic, and magnetic properties in organic materials. This article reports optically tunable spin-exchange energy by studying the line-shape characteristics in magnetic field effect of photocurrent developed from intermolecular charge-transfer states based on donor:acceptor (P3HT:PCBM) system. Specifically, we divide magnetic field effect of photocurrent into hyperfine (at low field   10 mT) regimes. We observe that increasing photoexcitation intensity can lead to a significant line-shape narrowing in magnetic field effect of photocurrent occurring at the spin-exchange regime. We analyze that the line-shape characteristics is essentially determined by the changing rate of magnetic field-dependent singlet/triplet ratio when a magnetic field perturbs the singlet-triplet transition through spin mixing. Based on our analysis, the line-shape narrowing results indicate that the spin-exchange energy at D:A interfaces can be optically changed by changing photoexcitation intensity through the interactions between intermolecular charge-transfer states. Therefore, our experimental results demonstrate an optical approach to change the spin-exchange energy through the interactions between intermolecular charge-transfer states at donor:acceptor interface in organic materials.

  18. Comparison of the function of exchange in couples of similar and differing physical attractiveness.

    Science.gov (United States)

    Murstein, Bernard I; Reif, Jeffrey A; Syracuse-Siewert, Gia

    2002-08-01

    Couples (22 young, married, 18 young unmarried) completed the Exchange Orientation Scale, which measures how much individuals believe equality of exchange should characterize their social relationships, as well as the Norman Personality Trait Scale, which gives measures for the self and ideal-self. Couples also rated their sexual satisfaction, their partners' physical attractiveness, their own attractiveness, and had their photographs evaluated for attractiveness by disinterested raters. Subgroups were formed of physically attractive couples, couples in which the members were of disparate attractiveness, and couples in which the individuals perceived themselves as equal to their partners in attractiveness or as inferior. In accordance with exchange theory, the hypotheses were (1) unmarried men would show higher exchange scores than married men, (2) attractive men in disparately attractive couples would show greater exchange scores than attractive men in both-attractive couples, (3) attractive members of disparately attractive couples would possess lower self-acceptance and (4) experience greater sexual satisfaction than attractive members of both-attractive couples. Results supported all hypotheses in varying extents.

  19. Fluxes and exchange rates of radon and oxygen across an air-sea interface

    International Nuclear Information System (INIS)

    Duenas, C.; Fernandez, M.C.; La Torre, M. de

    1986-01-01

    The flux of 222 Rn and O 2 from shallow water off the Bay of Malaga has been measured. The mean value of flux of 222 Rn is evaluated to be 74 atoms/m 2 · s. The Bay is a weak source of oxygen to the atmosphere, where the net production of oxygen is found to be 1.82 mol/m 2 · y. Moreover, the gas exchange rates of 222 Rn and O 2 across the air-sea interface has been determined by the radon method. The gas exchange rates and the wind speed have been estimated. (author)

  20. Interface model coupling in fluid dynamics: application to two-phase flows

    International Nuclear Information System (INIS)

    Galie, Th.

    2009-03-01

    This thesis is devoted to the study of interface model coupling problems in space between different models of compressible flows. We consider one-dimensional problems where the interface is sharp, fixed and separating two regions of space corresponding to the two coupled models. Our goal is to define a coupling condition at the interface and to solve numerically the coupling problem with this condition. After a state of art on the interface model coupling of hyperbolic systems of conservation laws, we propose a new coupling condition by adding in the equations of the coupled problem a measure source term at the interface. We first suppose a given constant weight associated to this source term. Two Riemann solvers are developed and one of them is based on a relaxation approach preserving equilibrium solutions of the coupled problem. This relaxation method is then used in an optimization problem, defined by several motivations at the interface, which permits to calculate a time dynamical weight. In a second part, we develop an approached Riemann solver for a two-phase two-pressure model in the particular case of a two-phase isentropic flow. Such a model contains non conservative terms that we write under the form of measure source terms. The previous relaxation method is thus extended to the case of the two-phase two-pressure model with an a priori estimation of the non conservative term contributions. The method allows us to solve, in the next and last chapter, the coupling problem of a two-fluid two-pressure model with a drift-flux model thanks to the father model approach. (authors)

  1. Mean field analysis of exchange coupling in amorphous DyFe2-B alloy ribbons

    International Nuclear Information System (INIS)

    Lee, J.M.; Jung, J.K.; Lim, S.H.

    2001-01-01

    Experimental magnetization-temperature curves for melt-spun ribbons of amorphous alloys (Dy 0.33 Fe 0.67 ) 1-x B x with x=0, 0.05, 0.1 and 0.15 (in atomic fraction) are fitted with theoretical equations based on the mean field theory in order to investigate exchange couplings between constituent elements as a function of the B content. The sign of the exchange coupling between Dy and Fe is negative, indicating that the magnetization direction of Dy is antiparallel to that of Fe. The sign of the other two couplings are positive. The exchange coupling between Fe ions are greatest, while that between Dy ions is negligible. The exchange couplings between Fe ions, and between Dy and Fe increase with increasing B content, the increase of the latter being much greater than the former. Resulting, the exchange coupling between Dy and Fe becomes about one half of that between Fe ions at the highest B content. The increase of the exchange coupling between Fe ions may be explained by the increase of the Fe-Fe separation with the increase of the B content. The total magnetization is dominated by the Dy sublattice magnetization. As the B content increases, the magnetization decreases over the whole temperature range, and the Curie temperature also decreases

  2. Mercury Exchange at the Air-Water-Soil Interface: An Overview of Methods

    Directory of Open Access Journals (Sweden)

    Fengman Fang

    2002-01-01

    Full Text Available An attempt is made to assess the present knowledge about the methods of determining mercury (Hg exchange at the air-water-soil interface during the past 20 years. Methods determining processes of wet and dry removal/deposition of atmospheric Hg to aquatic and terrestrial ecosystems, as well as methods determining Hg emission fluxes to the atmosphere from natural surfaces (soil and water are discussed. On the basis of the impressive advances that have been made in the areas relating to Hg exchange among air-soil-water interfaces, we analyzed existing problems and shortcomings in our current knowledge. In addition, some important fields worth further research are discussed and proposed.

  3. A generalized interface module for the coupling of spatial kinetics and thermal-hydraulics codes

    Energy Technology Data Exchange (ETDEWEB)

    Barber, D.A.; Miller, R.M.; Joo, H.G.; Downar, T.J. [Purdue Univ., West Lafayette, IN (United States). Dept. of Nuclear Engineering; Wang, W. [SCIENTECH, Inc., Rockville, MD (United States); Mousseau, V.A.; Ebert, D.D. [Nuclear Regulatory Commission, Washington, DC (United States). Office of Nuclear Regulatory Research

    1999-03-01

    A generalized interface module has been developed for the coupling of any thermal-hydraulics code to any spatial kinetics code. The coupling scheme was designed and implemented with emphasis placed on maximizing flexibility while minimizing modifications to the respective codes. In this design, the thermal-hydraulics, general interface, and spatial kinetics codes function independently and utilize the Parallel Virtual Machine software to manage cross-process communication. Using this interface, the USNRC version of the 3D neutron kinetics code, PARCX, has been coupled to the USNRC system analysis codes RELAP5 and TRAC-M. RELAP5/PARCS assessment results are presented for two NEACRP rod ejection benchmark problems and an NEA/OECD main steam line break benchmark problem. The assessment of TRAC-M/PARCS has only recently been initiated, nonetheless, the capabilities of the coupled code are presented for a typical PWR system/core model.

  4. A generalized interface module for the coupling of spatial kinetics and thermal-hydraulics codes

    International Nuclear Information System (INIS)

    Barber, D.A.; Miller, R.M.; Joo, H.G.; Downar, T.J.; Mousseau, V.A.; Ebert, D.D.

    1999-01-01

    A generalized interface module has been developed for the coupling of any thermal-hydraulics code to any spatial kinetics code. The coupling scheme was designed and implemented with emphasis placed on maximizing flexibility while minimizing modifications to the respective codes. In this design, the thermal-hydraulics, general interface, and spatial kinetics codes function independently and utilize the Parallel Virtual Machine software to manage cross-process communication. Using this interface, the USNRC version of the 3D neutron kinetics code, PARCX, has been coupled to the USNRC system analysis codes RELAP5 and TRAC-M. RELAP5/PARCS assessment results are presented for two NEACRP rod ejection benchmark problems and an NEA/OECD main steam line break benchmark problem. The assessment of TRAC-M/PARCS has only recently been initiated, nonetheless, the capabilities of the coupled code are presented for a typical PWR system/core model

  5. RKKY coupling in the gadolinium with shielded exchange interaction

    International Nuclear Information System (INIS)

    Aveline, A.

    1973-01-01

    The model of magnetic interation by indirect exchange mechanism (RKKY) is studied. The shielding effect is estimated and exchange integral J(K vector, K' vector) and magnetic interaction energy Jmn(r) analysis is made. The magnetic interaction energy is determinated in two approximations and compared to the Ruderman-Kittel formula. The free electrons model, to conduction electrons, and 4f wave functions, to localized electrons were utilized [pt

  6. Exchange bias coupling in La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/BiFeO{sub 3} heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Huijben, Mark; Chu, Ying-Hao; Martin, Lane W.; Seidel, Jan; Balke, Nina; Gajek, Martin; Yang, Chan-Ho; Yu, Pu; Holcomb, Micky; Ramesh, Ramamoorthy [Department of Physics and Department of Materials Science and Engineering, University of California, Berkeley (United States)

    2008-07-01

    Heterostructures based on perovskite transition-metal oxides have attracted much attention because of the possibility of tuning the magnetic and electronic properties of thin films through interface effects such as exchange interactions, charge transfer, and epitaxial strain. The development and understanding of multiferroic materials such as BiFeO{sub 3}, have piqued the interest with the promise of coupling between order parameters such as ferroelectricity and antiferromagnetism. In this study we investigate the magnetic properties in ferromagnetic-antiferromagnetic multiferroic heterostructures by using atomic scale controlled growth through laser-MBE in combination with real-time RHEED monitoring. We will show the controlled coupling at the interfaces in La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/BiFeO{sub 3} heterostructures. This coupling behavior is investigated by structural measurements, such as X-ray reciprocal space mapping to clarify strained states, and magnetic measurements to gain a deeper fundamental understanding of the interactions at these interfaces. The interface coupling displays a strong enhancement in the coercivity of the La{sub 0.7}Sr{sub 0.3}MnO{sub 3} layer and a large shift in the magnetization hysteresis loops, indicating the existence of exchange bias coupling.

  7. A facile way to realize exchange coupling interaction in hard/soft magnetic composites

    Energy Technology Data Exchange (ETDEWEB)

    Li, Dongyun, E-mail: lidongyun@cjlu.edu.cn [College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Wang, Fan [College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Xia, Ailin, E-mail: alxia@126.com [Anhui Key Laboratory of Metal Materials and Processing, School of Materials Science and Engineering, Anhui University of Technology, Maanshan 243032 (China); Zhang, Lijiao [School of Science, Hebei University of Science and Technology, Shijiazhuang 050018 (China); Li, Tingting; Jin, Chuangui; Liu, Xianguo [Anhui Key Laboratory of Metal Materials and Processing, School of Materials Science and Engineering, Anhui University of Technology, Maanshan 243032 (China)

    2016-11-01

    SrFe{sub 12}O{sub 19}/CoFe{sub 2}O{sub 4} and SrFe{sub 12}O{sub 19}/Fe–B hard/soft magnetic composites were obtained by using powders synthesized via a hydrothermal and a molten salt method, respectively. The exchange coupling interaction was found to exist in the composites after a facile grinding according to the results of magnetic hysteresis loops and irreversible sloping recoil loops. It can be found that different grinding time affects their magnetic properties slightly. Our study proves that the conditions of realizing exchange coupling interaction may not be so stringent. - Highlights: • SrM/CFO and SrM/Fe–B with exchange coupling were obtained via a grinding way. • Different grinding time affects their magnetic properties slightly. • The conditions of realizing exchange coupling may not be so stringent.

  8. Magnetic exchange couplings from noncollinear perturbation theory: dinuclear CuII complexes.

    Science.gov (United States)

    Phillips, Jordan J; Peralta, Juan E

    2014-08-07

    To benchmark the performance of a new method based on noncollinear coupled-perturbed density functional theory [J. Chem. Phys. 138, 174115 (2013)], we calculate the magnetic exchange couplings in a series of triply bridged ferromagnetic dinuclear Cu(II) complexes that have been recently synthesized [Phys. Chem. Chem. Phys. 15, 1966 (2013)]. We find that for any basis-set the couplings from our noncollinear coupled-perturbed methodology are practically identical to those of spin-projected energy-differences when a hybrid density functional approximation is employed. This demonstrates that our methodology properly recovers a Heisenberg description for these systems, and is robust in its predictive power of magnetic couplings. Furthermore, this indicates that the failure of density functional theory to capture the subtle variation of the exchange couplings in these complexes is not simply an artifact of broken-symmetry methods, but rather a fundamental weakness of current approximate density functionals for the description of magnetic couplings.

  9. Mechanical coupling and liquid exchanges in the pleural space.

    Science.gov (United States)

    Agostoni, E; Zocchi, L

    1998-06-01

    The pleural space provides the mechanical coupling between lung and chest wall: two views about this coupling are reported and discussed. Information on volume, composition, thickness, and pressure of the pleural liquid under physiologic conditions in a few species is provided. The Starling pressures of the parietal pleura filtering liquid into pleural space, and those of the visceral pleura absorbing liquid from the space are considered along with the permeability of the mesothelium. Information on the lymphatic drainage through the parietal pleura and on the solute-coupled liquid absorption from the pleural space under physiologic conditions and with various kinds of hydrothorax are provided.

  10. Magnetization switching behavior with competing anisotropies in epitaxial Co3FeN /MnN exchange-coupled bilayers

    Science.gov (United States)

    Hajiri, T.; Yoshida, T.; Jaiswal, S.; Filianina, M.; Borie, B.; Ando, H.; Asano, H.; Zabel, H.; Kläui, M.

    2016-11-01

    We report unusual magnetization switching processes and angular-dependent exchange bias effects in fully epitaxial Co3FeN /MnN bilayers, where magnetocrystalline anisotropy and exchange coupling compete, probed by longitudinal and transverse magneto-optic Kerr effect (MOKE) magnetometry. The MOKE loops show multistep jumps corresponding to the nucleation and propagation of 90∘ domain walls in as-grown bilayers. By inducing exchange coupling, we confirm changes of the magnetization switching process due to the unidirectional anisotropy field of the exchange coupling. Taking into account the experimentally obtained values of the fourfold magnetocrystalline anisotropy, the unidirectional anisotropy field, the exchange-coupling constant, and the uniaxial anisotropy including its direction, the calculated angular-dependent exchange bias reproduces the experimental results. These results demonstrate the essential role of the competition between magnetocrystalline anisotropy and exchange coupling for understanding and tailoring exchange-coupling phenomena usable for engineering switching in fully epitaxial bilayers made of tailored materials.

  11. Magneto-structural correlations in exchange coupled systems

    International Nuclear Information System (INIS)

    Willett, R.D.; Gatteschi, D.; Kahn, O.

    1985-01-01

    This book contains 19 chapters. Some of the chapter titles are: Optical Spectroscophy; The Basis of Spin-Hamiltonian Theory; Inelastic Neutorn Scattering From Clusters; Magneto-structural Correlations in Bioinorganic Chemistry; and Magnetic Exchange Interactions Propagated by Multi-Atom Bridges

  12. Influence of the Coulomb interaction on the exchange coupling in granular magnets.

    Science.gov (United States)

    Udalov, O G; Beloborodov, I S

    2017-04-20

    We develop a theory of the exchange interaction between ferromagnetic (FM) metallic grains embedded into insulating matrix by taking into account the Coulomb blockade effects. For bulk ferromagnets separated by the insulating layer the exchange interaction strongly depends on the height and thickness of the tunneling barrier created by the insulator. We show that for FM grains embedded into insulating matrix the exchange coupling additionally depends on the dielectric properties of this matrix due to the Coulomb blockade effects. In particular, the FM coupling decreases with decreasing the dielectric permittivity of insulating matrix. We find that the change in the exchange interaction due to the Coulomb blockade effects can be a few tens of percent. Also, we study dependence of the intergrain exchange interaction on the grain size and other parameters of the system.

  13. Transition from reversible to irreversible magnetic exchange-spring processes in antiferromagnetically exchange-coupled hard/soft/hard trilayer structures

    International Nuclear Information System (INIS)

    Wang Xiguang; Guo Guanghua; Zhang Guangfu

    2011-01-01

    The demagnetization processes of antiferromagnetically exchange-coupled hard/soft/hard trilayer structures have been studied based on the discrete one-dimensional atomic chain model and the linear partial domain-wall model. It is found that, when the magnetic anisotropy of soft layer is taken into account, the changes of the soft layer thickness and the interfacial exchange coupling strength may lead a transition of demagnetization process in soft layer from the reversible to the irreversible magnetic exchange-spring process. For the trilayer structures with very thin soft layer, the demagnetization process exhibits typical reversible exchange-spring behavior. However, as the thickness of soft layer is increased, there is a crossover point t c , after which the process becomes irreversible. Similarly, there is also a critical interfacial exchange coupling constant A sh c , above which the exchange-spring process is reversible. When A sh sh c , the irreversible exchange-spring process is achieved. The phase diagram of reversible and irreversible exchange-spring processes is mapped in the plane of the interfacial exchange coupling A sh and soft layer thickness N s . - Research highlights: → A differing magnetic exchange-spring process is found in antiferromagnetically exchange-coupled hard/soft/hard trilayers if the magnetic anisotropy of the soft layers is taken into account. → The change of the soft layer thickness may lead to a transition of demagnetization process in soft layer from the reversible to the irreversible exchange-spring process. → The change of the soft-hard interfacial exchange coupling strength may lead a transition of demagnetization process in soft layer from the reversible to the irreversible exchange-spring process. → The phase diagram of reversible and irreversible exchange-spring processes is mapped in the plane of the interfacial exchange coupling and soft layer thickness.

  14. Quantifying Hyporheic Exchanges in a Large Scale River Reach Using Coupled 3-D Surface and Subsurface Computational Fluid Dynamics Simulations.

    Energy Technology Data Exchange (ETDEWEB)

    Hammond, Glenn Edward; Bao, J; Huang, M; Hou, Z; Perkins, W; Harding, S; Titzler, S; Ren, H; Thorne, P; Suffield, S; Murray, C; Zachara, J

    2017-03-01

    Hyporheic exchange is a critical mechanism shaping hydrological and biogeochemical processes along a river corridor. Recent studies on quantifying the hyporheic exchange were mostly limited to local scales due to field inaccessibility, computational demand, and complexity of geomorphology and subsurface geology. Surface flow conditions and subsurface physical properties are well known factors on modulating the hyporheic exchange, but quantitative understanding of their impacts on the strength and direction of hyporheic exchanges at reach scales is absent. In this study, a high resolution computational fluid dynamics (CFD) model that couples surface and subsurface flow and transport is employed to simulate hyporheic exchanges in a 7-km long reach along the main-stem of the Columbia River. Assuming that the hyporheic exchange does not affect surface water flow conditions due to its negligible magnitude compared to the volume and velocity of river water, we developed a one-way coupled surface and subsurface water flow model using the commercial CFD software STAR-CCM+. The model integrates the Reynolds-averaged Navier-Stokes (RANS) equation solver with a realizable κ-ε two-layer turbulence model, a two-layer all y+ wall treatment, and the volume of fluid (VOF) method, and is used to simulate hyporheic exchanges by tracking the free water-air interface as well as flow in the river and the subsurface porous media. The model is validated against measurements from acoustic Doppler current profiler (ADCP) in the stream water and hyporheic fluxes derived from a set of temperature profilers installed across the riverbed. The validated model is then employed to systematically investigate how hyporheic exchanges are influenced by surface water fluid dynamics strongly regulated by upstream dam operations, as well as subsurface structures (e.g. thickness of riverbed and subsurface formation layers) and hydrogeological properties (e.g. permeability). The results

  15. The Rashba spin-orbit coupling for superconductivity in oxide interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Beyl, Stefan; Orth, Peter P.; Schmalian, Joerg [Institut fuer Theorie der Kondensierten Materie, Karlsruher Institut fuer Technologie, Karlsruhe (Germany)

    2014-07-01

    We investigate the role of the Rashba spin-orbit coupling on the superconducting order parameter and the phase stiffness at the interface of LaAlO{sub 3} and SrTiO{sub 3}. In particular, we analyze the gate controlled crossover between BCS superconductivity and Bose-Einstein condensation of Cooper pairs, amplified by the Rashba coupling and the possibility of a phase fluctuation induced quantum critical point.

  16. Carbon Corrosion at Pt/C Interface in Proton Exchange Membrane Fuel Cell Environment

    International Nuclear Information System (INIS)

    Choi, Min Ho; Beam, Won Jin; Park, Chan Jin

    2010-01-01

    This study examined the carbon corrosion at Pt/C interface in proton exchange membrane fuel cell environment. The Pt nano particles were electrodeposited on carbon substrate, and then the corrosion behavior of the carbon electrode was examined. The carbon electrodes with Pt nano electrodeposits exhibited the higher oxidation rate and lower oxidation overpotential compared with that of the electrode without Pt. This phenomenon was more active at 75 .deg. C than 25 .deg. C. In addition, the current transients and the corresponding power spectral density (PSD) of the carbon electrodes with Pt nano electrodeposits were much higher than those of the electrode without Pt. The carbon corrosion at Pt/C interface was highly accelerated by Pt nano electrodeposits. Furthermore, the polarization and power density curves of PEMFC showed degradation in the performance due to a deterioration of cathode catalyst material and Pt dissolution

  17. Gas exchange at the air-sea interface: a technique for radon measurements in seawater

    International Nuclear Information System (INIS)

    Queirazza, G.; Roveri, M.

    1991-01-01

    The rate of exchange of various gas species, such as O 2 , CO 2 etc. across the air-water interface can be evaluated from the 222 Rn vertical profiles in the water column. Radon profiles were measured in 4 stations in the NW Adriatic Sea, in September 1990, using solvent extraction and liquid scintillation counting techniques, directly on board the ship. The radiochemical procedure is described in detail. The lower limit of detection is approximately 0.4 mBq 1 -1 . The radon deficiency in the profiles gives estimates of the gas transfer rate across the air-sea interface ranging from 0.9 to 7.0 m d -1 . The suitability of the radon deficiency method in shallow water, enclosed seas is briefly discussed. (Author)

  18. Oligomerization interface of RAGE receptor revealed by MS-monitored hydrogen deuterium exchange.

    Directory of Open Access Journals (Sweden)

    Ewa Sitkiewicz

    Full Text Available Activation of the receptor for advanced glycation end products (RAGE leads to a chronic proinflammatory signal, affecting patients with a variety of diseases. Potentially beneficial modification of RAGE activity requires understanding the signal transduction mechanism at the molecular level. The ligand binding domain is structurally uncoupled from the cytoplasmic domain, suggesting receptor oligomerization is a requirement for receptor activation. In this study, we used hydrogen-deuterium exchange and mass spectrometry to map structural differences between the monomeric and oligomeric forms of RAGE. Our results indicated the presence of a region shielded from exchange in the oligomeric form of RAGE and led to the identification of a new oligomerization interface localized at the linker region between domains C1 and C2. Based on this finding, a model of a RAGE dimer and higher oligomeric state was constructed.

  19. Microscopic theory of the Coulomb based exchange coupling in magnetic tunnel junctions.

    Science.gov (United States)

    Udalov, O G; Beloborodov, I S

    2017-05-04

    We study interlayer exchange coupling based on the many-body Coulomb interaction between conduction electrons in magnetic tunnel junction. This mechanism complements the known interaction between magnetic layers based on virtual electron hopping (or spin currents). We find that these two mechanisms have different behavior on system parameters. The Coulomb based coupling may exceed the hopping based exchange. We show that the Coulomb based exchange interaction, in contrast to the hopping based coupling, depends strongly on the dielectric constant of the insulating layer. The dependence of the interlayer exchange interaction on the dielectric properties of the insulating layer in magnetic tunnel junction is similar to magneto-electric effect where electric and magnetic degrees of freedom are coupled. We calculate the interlayer coupling as a function of temperature and electric field for magnetic tunnel junction with ferroelectric layer and show that the exchange interaction between magnetic leads has a sharp decrease in the vicinity of the ferroelectric phase transition and varies strongly with external electric field.

  20. Evidence of interface exchange magnetism in self-assembled cobalt-fullerene nanocomposites exposed to air

    Czech Academy of Sciences Publication Activity Database

    Lavrentiev, Vasyl; Stupakov, Alexandr; Lavrentieva, Inna; Motylenko, M.; Barchuk, M.; Rafaja, D.

    2017-01-01

    Roč. 28, č. 12 (2017), č. článku 125704. ISSN 0957-4484 R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠk LM2015056 Institutional support: RVO:68378271 ; RVO:61389005 Keywords : fullerene * cobalt clusters * cobalt oxide * nanocomposite * interface exchange magnetism Subject RIV: BM - Solid Matter Physics ; Magnetism; JB - Sensors, Measurment, Regulation (FZU-D) OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.); Electrical and electronic engineering (FZU-D) Impact factor: 3.440, year: 2016

  1. Coupled Fluid-Solid Interaction Under Shock Wave Loading: Part II - Dynamic Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Tipton, David Gregory [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Christon, Mark Allen [CTO Offce, Dassault Systµemes SIMULIA, Providence, RI (United States); Ingber, Marc Stuart [Univ. of New Mexico, Albuquerque, NM (United States). Department of Mechanical Engineering

    2009-07-01

    This article is the second of two that consider the treatment of fluid-solid interaction problems where the solid experiences wave loading and large bulk Lagrangian displacements. In part-I, we presented the formulation for the edge-based unstructured-grid Euler solver in the context of a discontinuous- Galerkin framework with the extensions used to treat internal fluid-solid interfaces. A super-sampled L2 projection was used to construct level-set data from the Lagrangian interface, and a narrow-band approach was used to identify and construct appropriate ghost data and boundary conditions at the fluid-solid interface. A series of benchmark problems were used to verify the treatment of the fluid-solid interface conditions with a static interface position. In this paper, we consider the treatment of dynamic interfaces and the associated large bulk Lagrangian displacements of the solid.We present the coupled dynamic fluid-solid system, and develop an explicit, monolithic treatment of the fully-coupled system. The conditions associated with moving interfaces and their implementation are discussed. A comparison of moving vs. fixed reference frames is used to verify the dynamic interface treatment. Lastly, a series of two and and three-dimensional projectile and shock-body interaction calculations are presented. Ultimately, the use of the Lagrangian interface position and a super-sampled projection for fast level-set construction, the narrow-band extraction of ghost data, and monolithic explicit solution algorithm has proved to be a computationally efficient means for treating shock induced fluid-solid interaction problems.

  2. Laser vaporization/ionization interface for coupling microscale separation techniques with mass spectrometry

    Science.gov (United States)

    Yeung, E.S.; Chang, Y.C.

    1999-06-29

    The present invention provides a laser-induced vaporization and ionization interface for directly coupling microscale separation processes to a mass spectrometer. Vaporization and ionization of the separated analytes are facilitated by the addition of a light-absorbing component to the separation buffer or solvent. 8 figs.

  3. A Simple Estimation of Coupling Loss Factors for Two Flexible Subsystems Connected via Discrete Interfaces

    Directory of Open Access Journals (Sweden)

    Jun Zhang

    2016-01-01

    Full Text Available A simple formula is proposed to estimate the Statistical Energy Analysis (SEA coupling loss factors (CLFs for two flexible subsystems connected via discrete interfaces. First, the dynamic interactions between two discretely connected subsystems are described as a set of intermodal coupling stiffness terms. It is then found that if both subsystems are of high modal density and meanwhile the interface points all act independently, the intermodal dynamic couplings become dominated by only those between different subsystem mode sets. If ensemble- and frequency-averaged, the intermodal coupling stiffness terms can simply reduce to a function of the characteristic dynamic properties of each subsystem and the subsystem mass, as well as the number of interface points. The results can thus be accommodated within the theoretical frame of conventional SEA theory to yield a simple CLF formula. Meanwhile, the approach allows the weak coupling region between the two SEA subsystems to be distinguished simply and explicitly. The consistency and difference of the present technique with and from the traditional wave-based SEA solutions are discussed. Finally, numerical examples are given to illustrate the good performance of the present technique.

  4. Interface modulated currents in periodically proton exchanged Mg doped lithium niobate

    Energy Technology Data Exchange (ETDEWEB)

    Neumayer, Sabine M.; Rodriguez, Brian J., E-mail: brian.rodriguez@ucd.ie, E-mail: gallo@kth.se [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4 (Ireland); Manzo, Michele; Gallo, Katia, E-mail: brian.rodriguez@ucd.ie, E-mail: gallo@kth.se [Department of Applied Physics, KTH-Royal Institute of Technology, Roslagstullbacken 21, 10691 Stockholm (Sweden); Kholkin, Andrei L. [Department of Physics and CICECO-Aveiro Institute of Materials, 3810-193 Aveiro, Portugal and Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation)

    2016-03-21

    Conductivity in Mg doped lithium niobate (Mg:LN) plays a key role in the reduction of photorefraction and is therefore widely exploited in optical devices. However, charge transport through Mg:LN and across interfaces such as electrodes also yields potential electronic applications in devices with switchable conductivity states. Furthermore, the introduction of proton exchanged (PE) phases in Mg:LN enhances ionic conductivity, thus providing tailorability of conduction mechanisms and functionality dependent on sample composition. To facilitate the construction and design of such multifunctional electronic devices based on periodically PE Mg:LN or similar ferroelectric semiconductors, fundamental understanding of charge transport in these materials, as well as the impact of internal and external interfaces, is essential. In order to gain insight into polarization and interface dependent conductivity due to band bending, UV illumination, and chemical reactivity, wedge shaped samples consisting of polar oriented Mg:LN and PE phases were investigated using conductive atomic force microscopy. In Mg:LN, three conductivity states (on/off/transient) were observed under UV illumination, controllable by the polarity of the sample and the externally applied electric field. Measurements of currents originating from electrochemical reactions at the metal electrode–PE phase interfaces demonstrate a memresistive and rectifying capability of the PE phase. Furthermore, internal interfaces such as domain walls and Mg:LN–PE phase boundaries were found to play a major role in the accumulation of charge carriers due to polarization gradients, which can lead to increased currents. The insight gained from these findings yield the potential for multifunctional applications such as switchable UV sensitive micro- and nanoelectronic devices and bistable memristors.

  5. Magnetic properties of soft layer/FePt-MgO exchange coupled composite Perpendicular recording media

    Institute of Scientific and Technical Information of China (English)

    Yin Jin-Hua; Takao Suzuki; Pan Li-Qing

    2008-01-01

    The magnetic properties of exchange coupled composite(ECC)media that are composed of perpendicular magnetic recording media FePt-MgO and two kinds of soft layers have been studied by using an x-ray diffractometer,a polar Kerr magneto-optical system(PMOKE)and a vibrating sample magnetometer(VSM).The results show that ECC media can reduce the coercivities of perpendicular magnetic recording media FePt-MgO.The ECC media with granular-type soft layers have weaker exchange couplings between magnetic grains and the magnetization process,for ECC media of this kind mainly follow the Stoner-Wohlfarth model.

  6. Optimization of spring exchange coupled ferrites, studied by in situ neutron diffraction

    DEFF Research Database (Denmark)

    Ahlburg, Jakob; Christensen, Mogens; Granados-Miralles, Cecilia

    origins from the 4f orbitals which can contain up to 14 electrons. But since REM are both expensive and difficult to mine, a great demand has come for cheaper types of magnets with a similar magnetic performance. A candidate could be the transition metal oxides. Here the magnetic contribution origins from...... the magnetic energy product. For the exchange coupling to happen it is crucial to have the right ratio between the hard and the soft phase but also to control the size of the particles since exchange coupling is a very small range effect. In this study, nanoparticles of the spinel CoFe2O4 (hard magnet...

  7. Air-Sea Momentum and Enthalpy Exchange in Coupled Atmosphere-Wave-Ocean Modeling of Tropical Cyclones

    Science.gov (United States)

    Curcic, M.; Chen, S. S.

    2016-02-01

    The atmosphere and ocean are coupled through momentum, enthalpy, and mass fluxes. Accurate representation of these fluxes in a wide range of weather and climate conditions is one of major challenges in prediction models. Their current parameterizations are based on sparse observations in low-to-moderate winds and are not suited for high wind conditions such as tropical cyclones (TCs) and winter storms. In this study, we use the Unified Wave INterface - Coupled Model (UWIN-CM), a high resolution, fully-coupled atmosphere-wave-ocean model, to better understand the role of ocean surface waves in mediating air-sea momentum and enthalpy exchange in TCs. In particular, we focus on the explicit treatment of wave growth and dissipation for calculating atmospheric and oceanic stress, and its role in upper ocean mixing and surface cooling in the wake of the storm. Wind-wave misalignment and local wave disequilibrium result in difference between atmospheric and oceanic stress being largest on the left side of the storm. We find that explicit wave calculation in the coupled model reduces momentum transfer into the ocean by more than 10% on average, resulting in reduced cooling in TC's wake and subsequent weakening of the storm. We also investigate the impacts of sea surface temperature and upper ocean parameterization on air-sea enthalpy fluxes in the fully coupled model. High-resolution UWIN-CM simulations of TCs with various intensities and structure are conducted in this study to better understand the complex TC-ocean interaction and improve the representation of air-sea coupling processes in coupled prediction models.

  8. The role of spin–orbit coupling in topologically protected interface states in Dirac materials

    International Nuclear Information System (INIS)

    Abergel, D S L; Balatsky, Alexander V; Edge, Jonathan M

    2014-01-01

    We highlight the fact that two-dimensional (2D) materials with Dirac-like low energy band structures and spin–orbit coupling (SOC) will produce linearly dispersing topologically protected Jackiw–Rebbi modes at interfaces where the Dirac mass changes sign. These modes may support persistent spin or valley currents parallel to the interface, and the exact arrangement of such topologically protected currents depends crucially on the details of the SOC in the material. As examples, we discuss buckled 2D hexagonal lattices such as silicene or germanene, and transition metal dichalcogenides such as MoS 2 . (paper)

  9. Exchange bias in antiferromagnetic coupled Fe3O4+Cr2O3 nanocomposites

    International Nuclear Information System (INIS)

    Liu, X H; Cui, W B; Lv, X K; Liu, W; Zhao, X G; Li, D; Zhang, Z D

    2008-01-01

    Exchange bias (EB) and magnetic properties of ferrimagnetic (FI) Fe 3 O 4 and antiferromagnetic (AFM) Cr 2 O 3 nanocomposites prepared by mechanical alloying have been investigated. A large EB field of 2.2 kOe at 10 K is observed in one of the nanocomposites, which may be related to the uncompensated and pinned AFM spins at the interface between FI and AFM phases of the nanocomposites. The EB field varies with the strength of cooling field and the content of the Cr 2 O 3 phase, the phenomena observed are explained in terms of interfacial exchange interaction between the two phases

  10. Influence of ion bombardment induced patterning of exchange bias in pinned artificial ferrimagnets on the interlayer exchange coupling

    Energy Technology Data Exchange (ETDEWEB)

    Schmalhorst, Jan; Reiss, Guenter; Hoenik, V. [Thin Films and Nanostructures, Department of Physics, Univ. Bielefeld (Germany); Weis, Tanja; Engel, Dieter; Ehresmann, Arno [Institute of Physics and Center for Interdisciplinary Nanostructure Science and Technology, Kassel Univ. (Germany)

    2007-07-01

    Artificial ferrimagnets (AFi) have many applications as, e.g., pinned reference electrodes in magnetic tunnel junctions. It is known that the application of ion bombardment induced magnetic patterning with He ions on a single layer reference electrode of magnetic tunnel junctions is possible. For some applications a combination of ion bombardment induced magnetic patterning and artificial ferrimagnets as a reference electrode is desirable. The effect of ion bombardment induced magnetic patterning on pinned artificial ferrimagnets with a Ru interlayer which is frequently used in magnetic tunnel junctions as well as pinned AFis with a Cu interlayer has been tested. Special attention has been given to the question whether the antiferromagnetic interlayer exchange coupling can withstand the ion dose necessary to turn the exchange bias.

  11. Optimization of spring exchange coupled ferrites, studied by in situ neutron diffraction

    DEFF Research Database (Denmark)

    Ahlburg, Jakob; Christensen, Mogens; Granados-Miralles, Cecilia

    have a spin it will also be possible to measure a magnetic signal and investigate the exchange-coupling. After the reduction the samples was furthermore investigated using powder x-ray diffraction and VSM (vibrating sample magnetometer). To understand the reaction mechanism, a series of experiments...

  12. Ultrafast spin exchange-coupling torque via photo-excited charge-transfer processes

    Science.gov (United States)

    Ma, X.; Fang, F.; Li, Q.; Zhu, J.; Yang, Y.; Wu, Y. Z.; Zhao, H. B.; Lüpke, G.

    2015-10-01

    Optical control of spin is of central importance in the research of ultrafast spintronic devices utilizing spin dynamics at short time scales. Recently developed optical approaches such as ultrafast demagnetization, spin-transfer and spin-orbit torques open new pathways to manipulate spin through its interaction with photon, orbit, charge or phonon. However, these processes are limited by either the long thermal recovery time or the low-temperature requirement. Here we experimentally demonstrate ultrafast coherent spin precession via optical charge-transfer processes in the exchange-coupled Fe/CoO system at room temperature. The efficiency of spin precession excitation is significantly higher and the recovery time of the exchange-coupling torque is much shorter than for the demagnetization procedure, which is desirable for fast switching. The exchange coupling is a key issue in spin valves and tunnelling junctions, and hence our findings will help promote the development of exchange-coupled device concepts for ultrafast coherent spin manipulation.

  13. Exchange coupling in hybrid anisotropy magnetic multilayers quantified by vector magnetometry

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, C., E-mail: C.Morrison.2@warwick.ac.uk; Miles, J. J.; Thomson, T. [School of Computer Science, University of Manchester, Manchester M13 9PL (United Kingdom); Anh Nguyen, T. N. [Materials Physics, School of ICT, KTH Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden); Spintronics Research Group, Laboratory for Nanotechnology (LNT), VNU-HCM, Ho Chi Minh City (Viet Nam); Fang, Y.; Dumas, R. K. [Department of Physics, University of Gothenburg, 412 96 Gothenburg (Sweden); Åkerman, J. [Materials Physics, School of ICT, KTH Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden); Department of Physics, University of Gothenburg, 412 96 Gothenburg (Sweden)

    2015-05-07

    Hybrid anisotropy thin film heterostructures, where layers with perpendicular and in-plane anisotropy are separated by a thin spacer, are novel materials for zero/low field spin torque oscillators and bit patterned media. Here, we report on magnetization reversal and exchange coupling in a archetypal Co/Pd (perpendicular)-NiFe (in-plane) hybrid anisotropy system studied using vector vibrating sample magnetometry. This technique allows us to quantify the magnetization reversal in each individual magnetic layer, and measure of the interlayer exchange as a function of non-magnetic spacer thickness. At large (>1 nm) spacer thicknesses Ruderman-Kittel-Kasuya-Yosida-like exchange dominates, with orange-peel coupling providing a significant contribution only for sub-nm spacer thickness.

  14. Exchange bias mechanism in FM/FM/AF spin valve systems in the presence of random unidirectional anisotropy field at the AF interface: The role played by the interface roughness due to randomness

    Science.gov (United States)

    Yüksel, Yusuf

    2018-05-01

    We propose an atomistic model and present Monte Carlo simulation results regarding the influence of FM/AF interface structure on the hysteresis mechanism and exchange bias behavior for a spin valve type FM/FM/AF magnetic junction. We simulate perfectly flat and roughened interface structures both with uncompensated interfacial AF moments. In order to simulate rough interface effect, we introduce the concept of random exchange anisotropy field induced at the interface, and acting on the interface AF spins. Our results yield that different types of the random field distributions of anisotropy field may lead to different behavior of exchange bias.

  15. Chemical trend of exchange coupling in diluted magnetic II-VI semiconductors: Ab initio calculations

    Science.gov (United States)

    Chanier, T.; Virot, F.; Hayn, R.

    2009-05-01

    We have calculated the chemical trend of magnetic exchange parameters ( Jdd , Nα , and Nβ ) of Zn-based II-VI semiconductors ZnA ( A=O , S, Se, and Te) doped with Co or Mn. We show that a proper treatment of electron correlations by the local spin-density approximation (LSDA)+U method leads to good agreement between experimental and theoretical values of the nearest-neighbor exchange coupling Jdd between localized 3d spins in contrast to the LSDA method. The exchange couplings between localized spins and doped electrons in the conduction band Nα are in good agreement with experiment as well. But the values for Nβ (coupling to doped holes in the valence band) indicate a crossover from weak coupling (for A=Te and Se) to strong coupling (for A=O ) and a localized hole state in ZnO:Mn. This hole localization explains the apparent discrepancy between photoemission and magneto-optical data for ZnO:Mn.

  16. Oxygen exchange and ice melt measured at the ice-water interface by eddy correlation

    DEFF Research Database (Denmark)

    Long, M.H.; Koopmans, D.; Berg, P.

    2012-01-01

    heterotrophic with a daily gross primary production of 0.69 mmol O2 mĝ̂'2 dĝ̂'1 and a respiration rate of ĝ̂'2.13 mmol O2 mĝ̂'2 dĝ̂'1 leading to a net ecosystem metabolism of ĝ̂'1.45 mmol O2 mĝ̂'2 dĝ̂'1. This application of the eddy correlation technique produced high temporal resolution O2 fluxes and ice melt......This study examined fluxes across the ice-water interface utilizing the eddy correlation technique. Temperature eddy correlation systems were used to determine rates of ice melting and freezing, and O2 eddy correlation systems were used to examine O2 exchange rates driven by biological and physical...

  17. Tuning the metal-insulator transition in manganite films through surface exchange coupling with magnetic nanodots.

    Science.gov (United States)

    Ward, T Z; Gai, Z; Xu, X Y; Guo, H W; Yin, L F; Shen, J

    2011-04-15

    In strongly correlated electronic systems, the global transport behavior depends sensitively on spin ordering. We show that spin ordering in manganites can be controlled by depositing isolated ferromagnetic nanodots at the surface. The exchange field at the interface is tunable with nanodot density and makes it possible to overcome dimensionality and strain effects in frustrated systems to greatly increasing the metal-insulator transition and magnetoresistance. These findings indicate that electronic phase separation can be controlled by the presence of magnetic nanodots.

  18. An approach for the modeling of interface-body coupled nonlocal damage

    Directory of Open Access Journals (Sweden)

    J. Toti

    2010-04-01

    Full Text Available Fiber Reinforced Plastic (FRP can be used for strengthening concrete or masonry constructions. One of the main problem in the use of FRP is the possible detachment of the reinforcement from the support material. This paper deals with the modeling of the FRP-concrete or masonry damage interface, accounting for the coupling occurring between the degradation of the cohesive material and the FRP detachment. To this end, a damage model is considered for the quasi-brittle material. In order to prevent strain localization and strong mesh sensitivity of the solution, an integral-type of nonlocal model based on the weighted spatial averaging of a strain-like quantity is developed. Regarding the interface, the damage is governed by the relative displacement occurring at bond. A suitable interface model which accounts for the mode I, mode II and mixed mode of damage is developed. The coupling between the body damage and the interface damage is performed computing the body damage on the bond surface. Numerical examples are presented.

  19. Tool coupling for the design and operation of building energy and control systems based on the Functional Mock-up Interface standard

    Energy Technology Data Exchange (ETDEWEB)

    Nouidui, Thierry Stephane; Wetter, Michael

    2014-03-01

    This paper describes software tools developed at the Lawrence Berkeley National Laboratory (LBNL) that can be coupled through the Functional Mock-up Interface standard in support of the design and operation of building energy and control systems. These tools have been developed to address the gaps and limitations encountered in legacy simulation tools. These tools were originally designed for the analysis of individual domains of buildings, and have been difficult to integrate with other tools for runtime data exchange. The coupling has been realized by use of the Functional Mock-up Interface for co-simulation, which standardizes an application programming interface for simulator interoperability that has been adopted in a variety of industrial domains. As a variety of coupling scenarios are possible, this paper provides users with guidance on what coupling may be best suited for their application. Furthermore, the paper illustrates how tools can be integrated into a building management system to support the operation of buildings. These tools may be a design model that is used for real-time performance monitoring, a fault detection and diagnostics algorithm, or a control sequence, each of which may be exported as a Functional Mock-up Unit and made available in a building management system as an input/output block. We anticipate that this capability can contribute to bridging the observed performance gap between design and operational energy use of buildings.

  20. Coupled acoustic-gravity field for dynamic evaluation of ion exchange with a single resin bead.

    Science.gov (United States)

    Kanazaki, Takahiro; Hirawa, Shungo; Harada, Makoto; Okada, Tetsuo

    2010-06-01

    A coupled acoustic-gravity field is efficient for entrapping a particle at the position determined by its acoustic properties rather than its size. This field has been applied to the dynamic observation of ion-exchange reactions occurring in a single resin bead. The replacement of counterions in an ion-exchange resin induces changes in its acoustic properties, such as density and compressibility. Therefore, we can visually trace the advancement of an ion-exchange reaction as a time change in the levitation position of a resin bead entrapped in the field. Cation-exchange reactions occurring in resin beads with diameters of 40-120 microm are typically completed within 100-200 s. Ion-exchange equilibrium or kinetics is often evaluated with off-line chemical analyses, which require a batch amount of ion exchangers. Measurements with a single resin particle allow us to evaluate ion-exchange dynamics and kinetics of ions including those that are difficult to measure by usual off-line analyses. The diffusion properties of ions in resins have been successfully evaluated from the time change in the levitation positions of resin beads.

  1. NiO/Fe(001): Magnetic anisotropy, exchange bias, and interface structure

    Energy Technology Data Exchange (ETDEWEB)

    Mlynczak, E. [Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239 Krakow (Poland); Luches, P. [S3, Istituto Nanoscienze-CNR, Via G. Campi 213/a, I-41125 Modena (Italy); Valeri, S. [S3, Istituto Nanoscienze-CNR, Via G. Campi 213/a, I-41125 Modena (Italy); Dipartimento di Scienze Fisiche, Matematiche e Informatiche, Universita di Modena e Reggio Emilia, Via G. Campi 213/a, 41100 Modena (Italy); Korecki, J. [Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239 Krakow (Poland); Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al.Mickiewicza 30, 30-059 Krakow (Poland)

    2013-06-21

    The magnetic and structural properties of NiO/Fe epitaxial bilayers grown on MgO(001) were studied using magnetooptic Kerr effect (MOKE) and conversion electron Moessbauer spectroscopy (CEMS). The bilayers were prepared under ultra high vacuum conditions using molecular beam epitaxy with oblique deposition. Two systems were compared: one showing the exchange bias (100ML-NiO/24ML-Fe), ML stands for a monolayer, and another where the exchange bias was not observed (50ML-NiO/50ML-Fe). For both, the magnetic anisotropy was found to be complex, yet dominated by the growth-induced uniaxial anisotropy. The training effect was observed for the 100ML-NiO/24ML-Fe system and quantitatively described using the spin glass model. The composition and magnetic state of the interfacial Fe layers were studied using {sup 57}Fe-CEMS. An iron oxide phase (Fe{sup 3+}{sub 4}Fe{sup 2+}{sub 1}O{sub 7}), as thick as 31 A, was identified at the NiO/Fe interface in the as-deposited samples. The ferrimagnetic nature of the interfacial iron oxide film explains the complex magnetic anisotropy observed in the samples.

  2. A study of ion exchange at the poly(butyl viologen)-electrolyte interface by SECM

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Chih-Yu.; Vasantha, V.S. [Department of Chemical Engineering, National Taiwan University, Taipei 10617 (China); Ho, Kuo-Chuan [Department of Chemical Engineering, National Taiwan University, Taipei 10617 (China); Institute of Polymer Science and Engineering, National Taiwan University, Taipei 10617 (China)

    2008-09-01

    In this work, the ion exchange characteristics of poly(butyl viologen) (PBV) thin films on a platinum electrode has been investigated by cyclic voltammetric (CV) scans. Since ferrocyanide anions (Fe(CN){sub 6}{sup 4-}) were added during the polymerization of the PBV thin-film for its stability, Fe(CN){sub 6}{sup 4-} could form charge transfer complex with monomer and co-deposited with polymer. Scanning electrochemical microscopy (SECM) was used to probe the released Fe(CN){sub 6}{sup 4-} ions from PBV film with Os(bpy){sub 3}Cl{sub 2} as a mediator for the approaching process in 0.5 M KCl medium. Mass changes during the redox process of the film were also monitored in-situ by electrochemical quartz crystal microbalance (EQCM). The ion exchange and transport behavior was observed during CV cycling of the film of the SECM and EQCM. The insertion and extraction of anions were found to be potential-dependence. Moreover, the decrease in tip current of released Fe(CN){sub 6}{sup 4-} with increasing cycle number accounted for the ion exchange between Fe(CN){sub 6}{sup 4-} and Cl{sup -} in the KCl electrolyte. However, the Fe(CN){sub 6}{sup 4-}/Fe(CN){sub 6}{sup 3-} redox couple was found to be highly stable between 0.0 and 0.5 V (vs. Ag/AgCl/saturated KCl) in the phosphate buffer solution. Therefore, the electrochemical property of Fe(CN){sub 6}{sup 4-}/Fe(CN){sub 6}{sup 3-} redox couple was studied at different scan rates using CV technique. The peak currents were directly proportional to the scan rate as predicted for a surface confined diffusionless system. The surface coverage ({gamma}) and the concentration of Fe(CN){sub 6}{sup 4-} were determined to be 1.88 x 10{sup -8} mol/cm{sup 2} and 0.641 mol/dm{sup 3}, respectively. By neglecting cations incorporation during redox reaction of the PBV film and also based on the results obtained from energy-dispersive X-ray spectroscopy for the films of as-deposited, reduced and oxidized states, an ion exchange mechanism was

  3. Modification of interlayer exchange coupling in Fe/V/Fe trilayers using hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Skoryna, J., E-mail: jskoryna@ifmpan.poznan.pl [Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17 St., 60-179 Poznań (Poland); Marczyńska, A. [Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17 St., 60-179 Poznań (Poland); Lewandowski, M. [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85 St., 61-614 Poznań (Poland); Smardz, L. [Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17 St., 60-179 Poznań (Poland)

    2015-10-05

    Highlights: • Magnetic films and multilayers. • Thin films. • Hydrogen absorbing materials. • Magnetic measurements. • Exchange coupling. - Abstract: Fe/V/Fe trilayers with constant-thickness Fe and step-like wedged V sublayers were prepared at room temperature using UHV magnetron sputtering. The bottom Fe layer grows onto oxidised Si(1 0 0) substrate and shows relatively high coercivity. The top Fe layer grows on vanadium spacer and shows considerably lower coercivity. The planar growth of the Fe and V sublayers was confirmed in-situ by X-ray photoelectron spectroscopy. Results show that the Fe sublayers are weakly exchange coupled for d{sub V} > 1.4 nm. Results on the coercivity studies as a function of the V interlayer thickness show near d{sub V} ∼ 1.95 nm (∼2.45 nm) weak antiferromagnetic (ferromagnetic) coupling, respectively. The hydrogenation of the Fe/V/Fe trilayers leads to increase of the strength of the ferromagnetic interlayer exchange coupling.

  4. Oxygen exchange at gas/oxide interfaces: how the apparent activation energy of the surface exchange coefficient depends on the kinetic regime.

    Science.gov (United States)

    Fielitz, Peter; Borchardt, Günter

    2016-08-10

    In the dedicated literature the oxygen surface exchange coefficient KO and the equilibrium oxygen exchange rate [Fraktur R] are considered to be directly proportional to each other regardless of the experimental circumstances. Recent experimental observations, however, contradict the consequences of this assumption. Most surprising is the finding that the apparent activation energy of KO depends dramatically on the kinetic regime in which it has been determined, i.e. surface exchange controlled vs. mixed or diffusion controlled. This work demonstrates how the diffusion boundary condition at the gas/solid interface inevitably entails a correlation between the oxygen surface exchange coefficient KO and the oxygen self-diffusion coefficient DO in the bulk ("on top" of the correlation between KO and [Fraktur R] for the pure surface exchange regime). The model can thus quantitatively explain the range of apparent activation energies measured in the different regimes: in the surface exchange regime the apparent activation energy only contains the contribution of the equilibrium exchange rate, whereas in the mixed or in the diffusion controlled regime the contribution of the oxygen self-diffusivity has also to be taken into account, which may yield significantly higher apparent activation energies and simultaneously quantifies the correlation KO ∝ DO(1/2) observed for a large number of oxides in the mixed or diffusion controlled regime, respectively.

  5. Frequency Dependencies of the Exchange Spin Wave Reflection Coefficient on a One-Dimensional Magnon Crystal with Complex Interfaces

    Directory of Open Access Journals (Sweden)

    Serhii O. Reshetniak

    2017-09-01

    Conclusions. It is shown that the frequency dependencies are periodic, points of full transmission and areas, full of reflection. Decreasing exchange parameter value in interface causes the increase of reflectance coefficient. Changing the material parameters we get the necessary intensity value of the reflection coefficient depending on the frequency at a constant value of the external magnetic field.

  6. Effect of Moisture Exchange on Interface Formation in the Repair System Studied by X-ray Absorption

    NARCIS (Netherlands)

    Lukovic, M.; Ye, G.

    2015-01-01

    In concrete repair systems, material properties of the repair material and the interface are greatly influenced by the moisture exchange between the repair material and the substrate. If the substrate is dry, it can absorb water from the repair material and reduce its effective water-to-cement ratio

  7. Inelastic Neutron Scattering and Magnetisation Investigation of an Exchange-Coupled Dy2 SMM

    Science.gov (United States)

    Baker, Michael L.; Zhang, Qing; Sarachik, Myriam P.; Kent, Andrew D.; Chen, Yizhang; Butch, Nicholas; Pineda, Eufemio M.; McInnes, Eric

    The strong spin orbit coupling and weak crystal field energies of simple exchange-coupled rare earth SMMs makes the precise evaluation of their magnetic properties nontrivial. Here we report a detailed investigation of the single molecule magnet hqH2Dy2(hq)4(NO3)3MeOH. Inelastic neutron scattering is used to obtain direct access to several low energy crystal field excitations. The INS results display several features that are not found in earlier FIR absorption experiments, while other features found in the latter are absent. Based on the effective point charge model, numerical calculations are currently underway to resolve these apparent discrepancies using complementary magnetisation measurements to resolve the exchange between Dy ions. Work supported by ARO W911NF-13-1-1025 (CCNY) and NSF-DMR-1309202 (NYU).

  8. Properties of Exchange Coupled All-garnet Magneto-Optic Thin Film Multilayer Structures

    Directory of Open Access Journals (Sweden)

    Mohammad Nur-E-Alam

    2015-04-01

    Full Text Available The effects of exchange coupling on magnetic switching properties of all-garnet multilayer thin film structures are investigated. All-garnet structures are fabricated by sandwiching a magneto-soft material of composition type Bi1.8Lu1.2Fe3.6Al1.4O12 or Bi3Fe5O12:Dy2O3 in between two magneto-hard garnet material layers of composition type Bi2Dy1Fe4Ga1O12 or Bi2Dy1Fe4Ga1O12:Bi2O3. The fabricated RF magnetron sputtered exchange-coupled all-garnet multilayers demonstrate a very attractive combination of magnetic properties, and are of interest for emerging applications in optical sensors and isolators, ultrafast nanophotonics and magneto-plasmonics. An unconventional type of magnetic hysteresis behavior not observed previously in magnetic garnet thin films is reported and discussed.

  9. Properties of Exchange Coupled All-garnet Magneto-Optic Thin Film Multilayer Structures

    Science.gov (United States)

    Nur-E-Alam, Mohammad; Vasiliev, Mikhail; Kotov, Viacheslav A.; Balabanov, Dmitry; Akimov, Ilya; Alameh, Kamal

    2015-01-01

    The effects of exchange coupling on magnetic switching properties of all-garnet multilayer thin film structures are investigated. All-garnet structures are fabricated by sandwiching a magneto-soft material of composition type Bi1.8Lu1.2Fe3.6Al1.4O12 or Bi3Fe5O12:Dy2O3 in between two magneto-hard garnet material layers of composition type Bi2Dy1Fe4Ga1O12 or Bi2Dy1Fe4Ga1O12:Bi2O3. The fabricated RF magnetron sputtered exchange-coupled all-garnet multilayers demonstrate a very attractive combination of magnetic properties, and are of interest for emerging applications in optical sensors and isolators, ultrafast nanophotonics and magneto-plasmonics. An unconventional type of magnetic hysteresis behavior not observed previously in magnetic garnet thin films is reported and discussed. PMID:28788043

  10. Design precautions for coupling interfaces between nuclear heating reactor and heating grid or desalination plant

    International Nuclear Information System (INIS)

    Zheng Wenxiang

    1998-01-01

    Nuclear heating reactor (NHR) has been developed by INET since the early eighties. To achieve its economic viability and safety goal, the NHR is designed with a number of advanced and innovative features, including integrated arrangement, natural circulation, self-pressurized performance, dynamically hydraulic control rod drive and passive safety systems. As a new promising energy system, the NHR can serve for district heating, air conditioning, sea-water desalination and other industrial processes. For all of these applications, it is vital that the design and performance of the coupling interfaces shall insure protection of user ends against radioactive contamination. Therefore, an intermediate circuit is provided in the NHR as a physical barrier, and the operating pressure in the intermediate circuit is higher than that in the primary system. In addition, the radioactivity in the intermediate circuit is monitored continuously, and there are also other protection measures in the design for isolating the intermediate circuit and the heating grid or desalination plant under some emergency conditions. The excellent performance of the above design precautions for the coupling interfaces has been demonstrated by operational practice from the NHR-5, a 5 MW(thermal) experimental NHR, which was put into operation in 1989. This paper presents the main design features of the NHR as well as the special provisions taken in the design for coupling the NHR to the heating grid or desalination plant and some operating experience from the NHR-5. (author)

  11. Revealing the Interface Structure and Bonding Mechanism of Coupling Agent Treated WPC

    Directory of Open Access Journals (Sweden)

    Jiuping Rao

    2018-03-01

    Full Text Available This paper presents the interfacial optimisation of wood plastic composites (WPC based on recycled wood flour and polyethylene by employing maleated and silane coupling agents. The effect of the incorporation of the coupling agents on the variation of chemical structure of the composites were investigated by Attenuated total reflectance-Fourier Transform Infrared spectroscopy (ATR-FTIR and Solid state 13C Nuclear Magnetic Resonance spectroscopy (NMR analyses. The results revealed the chemical reactions that occurred between the coupling agents and raw materials, which thus contributed to the enhancement of compatibility and interfacial adhesion between the constituents of WPC. NMR results also indicated that there existed the transformation of crystalline cellulose to an amorphous state during the coupling agent treatments, reflecting the inferior resonance of crystalline carbohydrates. Fluorescence Microscope (FM and Scanning Electron Microscope (SEM analyses showed the improvements of wood particle dispersion and wettability, compatibility of the constituents, and resin penetration, and impregnation of the composites after the coupling agent treatments. The optimised interface of the composites was attributed to interdiffusion, electrostatic adhesion, chemical reactions, and mechanical interlocking bonding mechanisms.

  12. Oscillatory Energy Exchange Between Waves Coupled by a Dynamic Artificial Crystal

    OpenAIRE

    Karenowska, Alexy D.; Tiberkevich, Vasil S.; Chumak, Andrii V.; Serga, Alexander A.; Gregg, John F.; Slavin, Andrei N.; Hillebrands, Burkard

    2011-01-01

    We describe a general mechanism of controllable energy exchange between waves propagating in a dynamic artificial crystal. We show that if a spatial periodicity is temporarily imposed on the transmission properties of a wave-carrying medium whilst a wave is inside, this wave is coupled to a secondary counter-propagating wave and energy oscillates between the two. The oscillation frequency is determined by the width of the spectral band gap created by the periodicity and the frequency differen...

  13. InP/ZnS nanocrystals: coupling NMR and XPS for fine surface and interface description.

    Science.gov (United States)

    Virieux, Héloïse; Le Troedec, Marianne; Cros-Gagneux, Arnaud; Ojo, Wilfried-Solo; Delpech, Fabien; Nayral, Céline; Martinez, Hervé; Chaudret, Bruno

    2012-12-05

    Advanced (1)H, (13)C, and (31)P solution- and solid-state NMR studies combined with XPS were used to probe, at the molecular scale, the composition (of the core, the shell, and the interface) and the surface chemistry of InP/ZnS core/shell quantum dots prepared via a non-coordinating solvent strategy. The interface between the mismatched InP and ZnS phases is composed of an amorphous mixed oxide phase incorporating InPO(x) (with x = 3 and predominantly 4), In(2)O(3), and InO(y)(OH)(3-2y) (y = 0, 1). Thanks to the analysis of the underlying reaction mechanisms, we demonstrate that the oxidation of the upper part of the InP core is the consequence of oxidative conditions brought by decarboxylative coupling reactions (ketonization). These reactions occur during both the core preparation and the coating process, but according to different mechanisms.

  14. Interfacing capillary electrophoresis with inductively coupled plasma mass spectrometry for redox speciation of plutonium

    International Nuclear Information System (INIS)

    Ambard, C.; Delorme, A.; Baglan, N.; Aupiais, J.; Pointurier, F.; Madic, C.

    2005-01-01

    A robust and efficient interface between a capilary electrophoresis (CE) and an ICP-MS for actinide speciation studies was developed. This interface was made of two stainless steel T-shape pieces connected to the ICP-MS through a PFA-50 nebulizer. Fast separations (typically in less than 15 min) were obtained. The performances of the technique in terms of chemical separations carried out by the capillary electrophoresis and in terms of detection limits were investigated. Concerning the detection limit of the CE-ICP-MS system for plutonium, it was determined as 5 x 10 -10 mol L -1 or 9 x 10 -18 mol under our injection conditions. The coupling enables to separate at least three (III, V and VI) of the four plutonium oxidation states which can exist in aqueous solutions and to monitor oxidation and reduction processes. (orig.)

  15. Protein structural dynamics at the gas/water interface examined by hydrogen exchange mass spectrometry.

    Science.gov (United States)

    Xiao, Yiming; Konermann, Lars

    2015-08-01

    Gas/water interfaces (such as air bubbles or foam) are detrimental to the stability of proteins, often causing aggregation. This represents a potential problem for industrial processes, for example, the production and handling of protein drugs. Proteins possess surfactant-like properties, resulting in a high affinity for gas/water interfaces. The tendency of previously buried nonpolar residues to maximize contact with the gas phase can cause significant structural distortion. Most earlier studies in this area employed spectroscopic tools that could only provide limited information. Here we use hydrogen/deuterium exchange (HDX) mass spectrometry (MS) for probing the conformational dynamics of the model protein myoglobin (Mb) in the presence of N(2) bubbles. HDX/MS relies on the principle that unfolded and/or highly dynamic regions undergo faster deuteration than tightly folded segments. In bubble-free solution Mb displays EX2 behavior, reflecting the occurrence of short-lived excursions to partially unfolded conformers. A dramatically different behavior is seen in the presence of N(2) bubbles; EX2 dynamics still take place, but in addition the protein shows EX1 behavior. The latter results from interconversion of the native state with conformers that are globally unfolded and long-lived. These unfolded species likely correspond to Mb that is adsorbed to the surface of gas bubbles. N(2) sparging also induces aggregation. To explain the observed behavior we propose a simple model, that is, "semi-unfolded" ↔ "native" ↔ "globally unfolded" → "aggregated". This model quantitatively reproduces the experimentally observed kinetics. To the best of our knowledge, the current study marks the first exploration of surface denaturation phenomena by HDX/MS. © 2015 The Protein Society.

  16. Spin-wave resonance frequency in ferromagnetic thin film with interlayer exchange coupling and surface anisotropy

    Science.gov (United States)

    Zhang, Shuhui; Rong, Jianhong; Wang, Huan; Wang, Dong; Zhang, Lei

    2018-01-01

    We have investigated the dependence of spin-wave resonance(SWR) frequency on the surface anisotropy, the interlayer exchange coupling, the ferromagnetic layer thickness, the mode number and the external magnetic field in a ferromagnetic superlattice film by means of the linear spin-wave approximation and Green's function technique. The SWR frequency of the ferromagnetic thin film is shifted to higher values corresponding to those of above factors, respectively. It is found that the linear behavior of SWR frequency curves of all modes in the system is observed as the external magnetic field is increasing, however, SWR frequency curves are nonlinear with the lower and the higher modes for different surface anisotropy and interlayer exchange coupling in the system. In addition, the SWR frequency of the lowest (highest) mode is shifted to higher (lower) values when the film thickness is thinner. The interlayer exchange coupling is more important for the energetically higher modes than for the energetically lower modes. The surface anisotropy has a little effect on the SWR frequency of the highest mode, when the surface anisotropy field is further increased.

  17. Advanced Reactors-Intermediate Heat Exchanger (IHX) Coupling: Theoretical Modeling and Experimental Validation

    Energy Technology Data Exchange (ETDEWEB)

    Utgikar, Vivek [Univ. of Idaho, Moscow, ID (United States); Sun, Xiaodong [The Ohio State Univ., Columbus, OH (United States); Christensen, Richard [The Ohio State Univ., Columbus, OH (United States); Sabharwall, Piyush [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-12-29

    The overall goal of the research project was to model the behavior of the advanced reactorintermediate heat exchange system and to develop advanced control techniques for off-normal conditions. The specific objectives defined for the project were: 1. To develop the steady-state thermal hydraulic design of the intermediate heat exchanger (IHX); 2. To develop mathematical models to describe the advanced nuclear reactor-IHX-chemical process/power generation coupling during normal and off-normal operations, and to simulate models using multiphysics software; 3. To develop control strategies using genetic algorithm or neural network techniques and couple these techniques with the multiphysics software; 4. To validate the models experimentally The project objectives were accomplished by defining and executing four different tasks corresponding to these specific objectives. The first task involved selection of IHX candidates and developing steady state designs for those. The second task involved modeling of the transient and offnormal operation of the reactor-IHX system. The subsequent task dealt with the development of control strategies and involved algorithm development and simulation. The last task involved experimental validation of the thermal hydraulic performances of the two prototype heat exchangers designed and fabricated for the project at steady state and transient conditions to simulate the coupling of the reactor- IHX-process plant system. The experimental work utilized the two test facilities at The Ohio State University (OSU) including one existing High-Temperature Helium Test Facility (HTHF) and the newly developed high-temperature molten salt facility.

  18. The role of frictional strength on plate coupling at the subduction interface

    KAUST Repository

    Tan, Eh

    2012-10-01

    At a subduction zone the amount of friction between the incoming plate and the forearc is an important factor in controlling the dip angle of subduction and the structure of the forearc. In this paper, we investigate the role of the frictional strength of sediments and of the serpentinized peridotite on the evolution of convergent margins. In numerical models, we vary thickness of a serpentinized layer in the mantle wedge (15 to 25km) and the frictional strength of both the sediments and serpentinized mantle (friction angle 1 to 15, or static friction coefficient 0.017 to 0.27) to control the amount of frictional coupling between the plates. With plastic strain weakening in the lithosphere, our numerical models can attain stable subduction geometry over millions of years. We find that the frictional strength of the sediments and serpentinized peridotite exerts the largest control on the dip angle of the subduction interface at seismogenic depths. In the case of low sediment and serpentinite friction, the subduction interface has a shallow dip, while the subduction zone develops an accretionary prism, a broad forearc high, a deep forearc basin, and a shallow trench. In the high friction case, the subduction interface is steep, the trench is deeper, and the accretionary prism, forearc high and basin are all absent. The resultant free-air gravity and topographic signature of these subduction zone models are consistent with observations. We believe that the low-friction model produces a geometry and forearc structure similar to that of accretionary margins. Conversely, models with high friction angles in sediments and serpentinite develop characteristics of an erosional convergent margin. We find that the strength of the subduction interface is critical in controlling the amount of coupling at the seismogenic zone and perhaps ultimately the size of the largest earthquakes at subduction zones. © 2012. American Geophysical Union. All Rights Reserved.

  19. Magnetic Exchange Couplings from Semilocal Functionals Evaluated Nonself-Consistently on Hybrid Densities: Insights on Relative Importance of Exchange, Correlation, and Delocalization.

    Science.gov (United States)

    Phillips, Jordan J; Peralta, Juan E

    2012-09-11

    Semilocal functionals generally yield poor magnetic exchange couplings for transition-metal complexes, typically overpredicting in magnitude the experimental values. Here we show that semilocal functionals evaluated nonself-consistently on densities from hybrid functionals can yield magnetic exchange couplings that are greatly improved with respect to their self-consistent semilocal values. Furthermore, when semilocal functionals are evaluated nonself-consistently on densities from a "half-and-half" hybrid, their errors with respect to experimental values can actually be lower than those from self-consistent calculations with standard hybrid functionals such as PBEh or TPSSh. This illustrates that despite their notoriously poor performance for exchange couplings, for many systems semilocal functionals are capable of delivering accurate relative energies for magnetic states provided that their electron delocalization error is corrected. However, while self-consistent calculations with hybrids uniformly improve results for all complexes, evaluating nonself-consistently with semilocal functionals does not give a balanced improvement for both ferro- and antiferromagnetically coupled complexes, indicating that there is more at play with the overestimation problem than simply the delocalization error. Additionally, we show that for some systems the conventional wisdom of choice of exchange functional mattering more than correlation does not hold. This combined with results from the nonself-consistent calculations provide insight on clarifying the relative roles of exchange, correlation, and delocalization in calculating magnetic exchange coupling parameters in Kohn-Sham Density Functional Theory.

  20. Interfacial exchange coupling and magnetization reversal in perpendicular [Co/Ni]N/TbCo composite structures.

    Science.gov (United States)

    Tang, M H; Zhang, Zongzhi; Tian, S Y; Wang, J; Ma, B; Jin, Q Y

    2015-06-15

    Interfacial exchange coupling and magnetization reversal characteristics in the perpendicular heterostructures consisting of an amorphous ferrimagnetic (FI) TbxCo(100-x) alloy layer exchange-coupled with a ferromagnetic (FM) [Co/Ni]N multilayer have been investigated. As compared with pure TbxCo(100-x) alloy, the magnetization compensation composition of the heterostructures shift to a higher Tb content, implying Co/Ni also serves to compensate the Tb moment in TbCo layer. The net magnetization switching field Hc⊥ and interlayer interfacial coupling field Hex, are not only sensitive to the magnetization and thickness of the switched TbxCo(100-x) or [Co/Ni]N layer, but also to the perpendicular magnetic anisotropy strength of the pinning layer. By tuning the layer structure we achieve simultaneously both large Hc⊥ = 1.31 T and Hex = 2.19 T. These results, in addition to the fundamental interest, are important to understanding of the interfacial coupling interaction in the FM/FI heterostructures, which could offer the guiding of potential applications in heat-assisted magnetic recording or all-optical switching recording technique.

  1. Charge and field coupling phenomena at metal-oxide interfaces and their applications

    Science.gov (United States)

    Voora, Venkata M.

    Heterostructures composed of polar materials, such as ferroelectric and/or piezoelectric, are interesting due to their interface lattice charge coupling (LCC) effects. In this thesis, coupling effects between switchable ferroelectric and non-switchable piezoelectric semiconductor spontaneous polarizations are addressed. Also discussed is a dielectric continuum model approach for studying LCC effects in double layer piezoelectric semiconductor-ferroelectric and triple layer piezoelectric semiconductor-ferroelectric-piezoelectric semiconductor heterostructures. The dielectric continuum model augments the effects of electric field driven switchable polarization due to LCC with depletion layer formation in semiconductor heterostructures. Electrical investigations were used to study a reference single layer (BaTiO3), a double layer (BaTiO3-ZnO), and a triple layer (ZnO-BaTiO 3-ZnO) heterostructure grown by pulsed laser deposition. The coupling between the non-switchable spontaneous polarization of ZnO and the electrically switchable spontaneous polarization of BaTiO3 causes strong asymmetric polarization hysteresis behavior. The n-type ZnO layer within double and triple layered heterostructures reveals hysteresis-dependent capacitance variations upon formation of depletion layers at the ZnO/BaTiO 3 interfaces. Model analysis show very good agreement between the generated data and the experimental results. The dielectric continuum model approach allows for the derivation of the amount and orientation of the spontaneous polarization of the piezoelectric constituents, and can be generalized towards multiple layer piezoelectric semiconductor-ferroelectric heterostructures. Based on experimental results the polarization coupled ZnO-BaTiO 3-ZnO heterostructures is identified as a two-terminal unipolar ferroelectric bi-junction transistor which can be utilized in memory storage devices. Furthermore it is discussed, that the triple layer heterostructure with magnetically

  2. Spin quantum tunneling via entangled states in a dimer of exchange coupled single-molecule magnets

    Science.gov (United States)

    Tiron, R.; Wernsdorfer, W.; Aliaga-Alcalde, N.; Foguet-Albiol, D.; Christou, G.

    2004-03-01

    A new family of supramolecular, antiferromagnetically exchange-coupled dimers of single-molecule magnets (SMMs) has recently been reported [W. Wernsdorfer, N. Aliaga-Alcalde, D.N. Hendrickson, and G. Christou, Nature 416, 406 (2002)]. Each SMM acts as a bias on its neighbor, shifting the quantum tunneling resonances of the individual SMMs. Hysteresis loop measurements on a single crystal of SMM-dimers have now established quantum tunneling of the magnetization via entangled states of the dimer. This shows that the dimer really does behave as a quantum-mechanically coupled dimer. The transitions are well separated, suggesting long coherence times compared to the time scale of the energy splitting. This result is of great importance if such systems are to be used for quantum computing. It also allows the measurement of the longitudinal and transverse superexchange coupling constants [Phys. Rev. Lett. 91, 227203 (2003)].

  3. User Guide for the R5EXEC Coupling Interface in the RELAP5-3D Code

    Energy Technology Data Exchange (ETDEWEB)

    Forsmann, J. Hope [Idaho National Lab. (INL), Idaho Falls, ID (United States); Weaver, Walter L. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-04-01

    This report describes the R5EXEC coupling interface in the RELAP5-3D computer code from the users perspective. The information in the report is intended for users who want to couple RELAP5-3D to other thermal-hydraulic, neutron kinetics, or control system simulation codes.

  4. A coupled interface-body nonlocal damage model for the analysis of FRP strengthening detachment from cohesive material

    Directory of Open Access Journals (Sweden)

    J. Toti

    2011-10-01

    Full Text Available In the present work, a new model of the FRP-concrete or masonry interface, which accounts for the coupling occurring between the degradation of the cohesive material and the FRP detachment, is presented; in particular, a coupled interface-body nonlocal damage model is proposed. A nonlocal damage and plasticity model is developed for the quasi-brittle material. For the interface, a model which accounts for the mode I, mode II and mixed mode of damage and for the unilateral contact and friction effects is developed. Two different ways of performing the coupling between the body damage and the interface damage are proposed and compared. Some numerical applications are carried out in order to assess the performances of the proposed model in reproducing the mechanical behavior of the masonry elements strengthened with external FRP reinforcements.

  5. Bis(triisopropylsilylethynyl)pentacene/Au(111) interface: Coupling, molecular orientation, and thermal stability

    KAUST Repository

    Gnoli, Andrea; Ü stü nel, Hande; Toffoli, Daniele; Yu, Liyang; Catone, D.; Turchini, Stefano; Lizzit, Silvano; Stingelin, Natalie; Larciprê te, Rosanna

    2014-01-01

    The assembly and the orientation of functionalized pentacene at the interface with inorganics strongly influence both the electric contact and the charge transport in organic electronic devices. In this study electronic spectroscopies and theoretical modeling are combined to investigate the properties of the bis(triisopropylsilylethynyl)pentacene (TIPS-Pc)/Au(111) interface as a function of the molecular coverage to compare the molecular state in the gas phase and in the adsorbed phase and to determine the thermal stability of TIPS-Pc in contact with gold. Our results show that in the free molecule only the acene atoms directly bonded to the ligands are affected by the functionalization. Adsorption on Au(111) leads to a weak coupling which causes only modest binding energy shifts in the TIPS-Pc and substrate core level spectra. In the first monolayer the acene plane form an angle of 33 ± 2° with the Au(111) surface at variance with the vertical geometry reported for thicker solution-processed or evaporated films, whereas the presence of configurational disorder was observed in the multilayer. The thermal annealing of the TIPS-Pc/Au(111) interface reveals the ligand desorption at ∼470 K, which leaves the backbone of the decomposed molecule flat-lying on the metal surface as in the case of the unmodified pentacene. The weak interaction with the metal substrate causes the molecular dissociation to occur 60 K below the thermal decomposition taking place in thick drop-cast films.

  6. Bis(triisopropylsilylethynyl)pentacene/Au(111) interface: Coupling, molecular orientation, and thermal stability

    KAUST Repository

    Gnoli, Andrea

    2014-10-02

    The assembly and the orientation of functionalized pentacene at the interface with inorganics strongly influence both the electric contact and the charge transport in organic electronic devices. In this study electronic spectroscopies and theoretical modeling are combined to investigate the properties of the bis(triisopropylsilylethynyl)pentacene (TIPS-Pc)/Au(111) interface as a function of the molecular coverage to compare the molecular state in the gas phase and in the adsorbed phase and to determine the thermal stability of TIPS-Pc in contact with gold. Our results show that in the free molecule only the acene atoms directly bonded to the ligands are affected by the functionalization. Adsorption on Au(111) leads to a weak coupling which causes only modest binding energy shifts in the TIPS-Pc and substrate core level spectra. In the first monolayer the acene plane form an angle of 33 ± 2° with the Au(111) surface at variance with the vertical geometry reported for thicker solution-processed or evaporated films, whereas the presence of configurational disorder was observed in the multilayer. The thermal annealing of the TIPS-Pc/Au(111) interface reveals the ligand desorption at ∼470 K, which leaves the backbone of the decomposed molecule flat-lying on the metal surface as in the case of the unmodified pentacene. The weak interaction with the metal substrate causes the molecular dissociation to occur 60 K below the thermal decomposition taking place in thick drop-cast films.

  7. Peculiarities of MCD C-term saturation behavior of the exchange coupled Co(II) dimers

    International Nuclear Information System (INIS)

    Ostrovsky, S.M.

    2011-01-01

    Graphical abstract: The change of sign of the MCD signal with temperature and magnetic field increase can take place. The origin of this peculiarity is explained by the strong orbital contribution. Highlights: → MCD C-term saturation behavior of the exchange coupled cobalt dimer. → Strong orbital contribution to the magneto-optical behavior. → Change of sign of the MCD signal with temperature and magnetic field increase. - Abstract: The MCD C-term saturation behavior of the exchange coupled octahedrally coordinated cobalt dimers is studied for different types of distortion of the local surrounding of each interacting ion. It was found that in the case of antiferromagnetic exchange interaction the change of sign of the MCD signal with temperature and magnetic field increase can take place. This signal behavior is not the result of overlapping of different electronic transitions and it is characteristic of an individual MCD line. The origin of this magneto-optical behavior is explained by the strong contribution coming from the unquenched orbital angular momenta of interacting cobalt ions. The found peculiarity is inherent to complexes composed of nonequivalent cobalt ions as well as to the dimeric complexes with the equivalent Co ions with nonparallel local axes.

  8. Theoretical study of ferromagnetic resonance in exchange - coupled magnetic / nonmagnetic / magnetic multilayer structure

    International Nuclear Information System (INIS)

    Oezdogan, K.; Oezdemir, M.; Yalcin, O.; Aktas, B.

    2002-01-01

    The dispersion relation on ferromagnetic films was calculation by using torque equation of motion with a damping term. The total energy including zeeman, demagnetizing and anisotropy energy terms was used to get ferromagnetic resonance frequency for both uniform and higher order spin wave modes. In antiferromagnetic films, the torque equation of motion for each sub-lattice were written to derive an expression for the dispersion relation. The magnetic trilayer system under investigation consist of two ferromagnetic layers separated by a nonmagnetic layer. The dispersion relation of magnetic/nonmagnetic/magnetic three layers is calculated by using Landau-Lifshitz dynamic equation of motion for the magnetization with interlayer exchange energy. As for the exchange-coupled resonance of ferromagnetic resonance (FMR), the theoretical study has been calculated for both symmetrical and asymmetrical structures. In this systems, the exchange-coupling parameter A 12 between neighboring layers was used to get resonance fields as a function of the angle between the magnetization vectors of each magnetic layers

  9. Circuit QED with qutrits: Coupling three or more atoms via virtual-photon exchange

    Science.gov (United States)

    Zhao, Peng; Tan, Xinsheng; Yu, Haifeng; Zhu, Shi-Liang; Yu, Yang

    2017-10-01

    We present a model to describe a generic circuit QED system which consists of multiple artificial three-level atoms, namely, qutrits, strongly coupled to a cavity mode. When the state transition of the atoms disobeys the selection rules the process that does not conserve the number of excitations can happen determinatively. Therefore, we can realize coherent exchange interaction among three or more atoms mediated by the exchange of virtual photons. In addition, we generalize the one-cavity-mode mediated interactions to the multicavity situation, providing a method to entangle atoms located in different cavities. Using experimentally feasible parameters, we investigate the dynamics of the model including three cyclic-transition three-level atoms, for which the two lowest energy levels can be treated as qubits. Hence, we have found that two qubits can jointly exchange excitation with one qubit in a coherent and reversible way. In the whole process, the population in the third level of atoms is negligible and the cavity photon number is far smaller than 1. Our model provides a feasible scheme to couple multiple distant atoms together, which may find applications in quantum information processing.

  10. Implications of loading/unloading a subduction zone with a heterogeneously coupled interface

    Science.gov (United States)

    Herman, M. W.; Furlong, K. P.; Govers, R. M. A.

    2017-12-01

    Numerical models of subduction zones with appropriate physical properties may help understand deformation throughout great earthquake cycles, as well as associated observations such as the distribution of smaller magnitude megathrust earthquakes and surface displacements. Of particular interest are displacements near the trench, where tsunamis are generated. The patterns of co-seismic strain release in great megathrust earthquakes depend on the frictional coupling of the plate interface prior to the event. Geodetic observations during the inter-seismic stage suggest that the plates are fully locked at asperities surrounded by zones of apparent partial coupling. We simulate the accumulation (and release) of elastic strain in the subduction system using a finite element model with a relatively simple geometry and material properties. We demonstrate that inter-seismic apparent partial coupling can be dominantly explained by a distribution of completely locked asperities and zero friction elsewhere. In these models, the interface up-dip of the locked zone (displacements with little internal strain, potentially leading to large co-seismic block displacements (low displacement gradients) of the near-trench seafloor like those observed following the 2011 Mw 9.0 Tohoku earthquake. This is also consistent with anomalously low co-seismic frictional heating of the shallow megathrust indicated by borehole heat flow measurements after the Tohoku event. Our models also yield insights into slip partitioning throughout multiple earthquake cycles. In smaller ruptures, fault slip is inhibited by nearby locked zones; in subsequent multi-segment ruptures, the rest of this slip deficit may be released, producing significantly larger slip than might be expected based on historical earthquake magnitudes. Finally, because low-friction areas around asperities accumulate some slip deficit but may not rupture co-seismically, these regions may be the primary locations of afterslip following

  11. A Unified Air-Sea Interface in Fully Coupled Atmosphere-Wave-Ocean Models for Data Assimilation and Ensemble Prediction

    Science.gov (United States)

    Chen, Shuyi; Curcic, Milan; Donelan, Mark; Campbell, Tim; Smith, Travis; Chen, Sue; Allard, Rick; Michalakes, John

    2014-05-01

    The goals of this study are to 1) better understand the physical processes controlling air-sea interaction and their impact on coastal marine and storm predictions, 2) explore the use of coupled atmosphere-ocean observations in model verification and data assimilation, and 3) develop a physically based and computationally efficient coupling at the air-sea interface that is flexible for use in a multi-model system and portable for transition to the next generation research and operational coupled atmosphere-wave-ocean-land models. We have developed a unified air-sea interface module that couples multiple atmosphere, wave, and ocean models using the Earth System Modeling Framework (ESMF). This standardized coupling framework allows researchers to develop and test air-sea coupling parameterizations and coupled data assimilation, and to better facilitate research-to-operation activities. It also allows for future ensemble forecasts using coupled models that can be used for coupled data assimilation and assessment of uncertainties in coupled model predictions. The current component models include two atmospheric models (WRF and COAMPS), two ocean models (HYCOM and NCOM), and two wave models (UMWM and SWAN). The coupled modeling systems have been tested and evaluated using the coupled air-sea observations (e.g., GPS dropsondes and AXBTs, drifters and floats) collected in recent field campaigns in the Gulf of Mexico and tropical cyclones in the Atlantic and Pacific basins. This talk will provide an overview of the unified air-sea interface model and fully coupled atmosphere-wave-ocean model predictions over various coastal regions and tropical cyclones in the Pacific and Atlantic basins including an example from coupled ensemble prediction of Superstorm Sandy (2012).

  12. Numerical and Experimental Study of an Ambient Air Vaporizer Coupled with a Compact Heat Exchanger

    Science.gov (United States)

    Kimura, Randon

    The University of Washington was tasked with designing a "21st century engine" that will make use of the thermal energy available in cryogenic gasses due to their coldness. There are currently large quantities of cryogenic gases stored throughout the U.S. at industrial facilities whereupon the regasification process, the potential for the fluid to do work is wasted. The engine proposed by the University of Washington will try to capture some of that wasted energy. One technical challenge that must be overcome during the regasification process is providing frost free operation. This thesis presents the numerical analysis and experimental testing of a passive heat exchange system that uses ambient vaporizers coupled with compact heat exchangers to provide frost free operation while minimizing pressure drop.

  13. Integrated assessment of groundwater - surface water exchange in the hillslope - riparian interface of a montane catchment

    Science.gov (United States)

    Scheliga, Bernhard; Tetzlaff, Doerthe; Nuetzmann, Gunnar; Soulsby, Chris

    2016-04-01

    Groundwater-surface water dynamics play an important role in runoff generation and the hydrologic connectivity between hillslopes and streams. Here, we present findings from a suite of integrated, empirical approaches to increase our understanding of groundwater-surface water interlinkages in a 3.2 km ^ 2 experimental catchment in the Scottish Highlands. The montane catchment is mainly underlain by granite and has extensive (70%) cover of glacial drift deposits which are up to 40 m deep and form the main aquifer in the catchment. Flat valley bottom areas fringe the stream channel and are characterised by peaty soils (0.5-4 m deep) which cover about 10% of the catchment and receive drainage from upslope areas. The transition between the hillslopes and riparian zone forms a critical interface for groundwater-surface water interactions that controls both the dynamics of riparian saturation and stream flow generation. We nested observations using wells to assess the groundwater - surface water transition, LiDAR surveys to explore the influence of micro-topography on shallow groundwater efflux and riparian wells to examine the magnitude and flux rates of deeper groundwater sources. We also used electrical resistivity surveys to assess the architecture and storage properties of drift aquifers. Finally, we used isotopic tracers to differentiate recharge sources and associated residence times as well as quantifying how groundwater dynamics affect stream flow. These new data have provided a novel conceptual framework for local groundwater - surface water exchange that is informing the development of new deterministic models for the site.

  14. Topological phases in superconductor-noncollinear magnet interfaces with strong spin-orbit coupling

    Energy Technology Data Exchange (ETDEWEB)

    Menke, H.; Schnyder, A.P. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany); Toews, A. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany); Quantum Matter Institute, University of British Columbia, Vancouver, BC (Canada)

    2016-07-01

    Majorana fermions are predicted to emerge at interfaces between conventional s-wave superconductors and non-collinear magnets. In these heterostructures, the spin moments of the non-collinear magnet induce a low-energy band of Shiba bound states in the superconductor. Depending on the type of order of the magnet, the band structure of these bound states can be topologically nontrivial. Thus far, research has focused on systems where the influence of spin-orbit coupling can be neglected. Here, we explore the interplay between non-collinear (or non-coplanar) spin textures and Rashba-type spin-orbit interaction. This situation is realized, for example, in heterostructures between helical magnets and heavy elemental superconductors, such as Pb. Using a unitary transformation in spin space, we show that the effects of Rashba-type spin-orbit coupling are equivalent to the effects of the non-collinear spin texture of the helical magnet. We explore the topological phase diagram as a function of spin-orbit coupling, spin texture, and chemical potential, and find many interesting topological phases, such as p{sub x}-, (p{sub x} + p{sub y})-, and (p{sub x} + i p{sub y})-wave states. Conditions for the formation and the nature of Majorana edge channels are examined. Furthermore, we study the topological edge currents of these phases.

  15. Effect of Moisture Exchange on Interface Formation in the Repair System Studied by X-ray Absorption

    Directory of Open Access Journals (Sweden)

    Mladena Lukovic

    2015-12-01

    Full Text Available In concrete repair systems, material properties of the repair material and the interface are greatly influenced by the moisture exchange between the repair material and the substrate. If the substrate is dry, it can absorb water from the repair material and reduce its effective water-to-cement ratio (w/c. This further affects the hydration rate of cement based material. In addition to the change in hydration rate, void content at the interface between the two materials is also affected. In this research, the influence of moisture exchange on the void content in the repair system as a function of initial saturation level of the substrate is investigated. Repair systems with varying level of substrate saturation are made. Moisture exchange in these repair systems as a function of time is monitored by the X-ray absorption technique. After a specified curing age (3 d, the internal microstructure of the repair systems was captured by micro-computed X-ray tomography (CT-scanning. From reconstructed images, different phases in the repair system (repair material, substrate, voids can be distinguished. In order to quantify the void content, voids were thresholded and their percentage was calculated. It was found that significantly more voids form when the substrate is dry prior to application of the repair material. Air, initially filling voids and pores of the dry substrate, is being released due to the moisture exchange. As a result, air voids remain entrapped in the repair material close to the interface. These voids are found to form as a continuation of pre-existing surface voids in the substrate. Knowledge about moisture exchange and its effects provides engineers with the basis for recommendations about substrate preconditioning in practice.

  16. Effect of Moisture Exchange on Interface Formation in the Repair System Studied by X-ray Absorption.

    Science.gov (United States)

    Lukovic, Mladena; Ye, Guang

    2015-12-22

    In concrete repair systems, material properties of the repair material and the interface are greatly influenced by the moisture exchange between the repair material and the substrate. If the substrate is dry, it can absorb water from the repair material and reduce its effective water-to-cement ratio (w/c). This further affects the hydration rate of cement based material. In addition to the change in hydration rate, void content at the interface between the two materials is also affected. In this research, the influence of moisture exchange on the void content in the repair system as a function of initial saturation level of the substrate is investigated. Repair systems with varying level of substrate saturation are made. Moisture exchange in these repair systems as a function of time is monitored by the X-ray absorption technique. After a specified curing age (3 d), the internal microstructure of the repair systems was captured by micro-computed X-ray tomography (CT-scanning). From reconstructed images, different phases in the repair system (repair material, substrate, voids) can be distinguished. In order to quantify the void content, voids were thresholded and their percentage was calculated. It was found that significantly more voids form when the substrate is dry prior to application of the repair material. Air, initially filling voids and pores of the dry substrate, is being released due to the moisture exchange. As a result, air voids remain entrapped in the repair material close to the interface. These voids are found to form as a continuation of pre-existing surface voids in the substrate. Knowledge about moisture exchange and its effects provides engineers with the basis for recommendations about substrate preconditioning in practice.

  17. Theory of the formation of the electric double layer at the ion exchange membrane-solution interface.

    Science.gov (United States)

    Moya, A A

    2015-02-21

    This work aims to extend the study of the formation of the electric double layer at the interface defined by a solution and an ion-exchange membrane on the basis of the Nernst-Planck and Poisson equations, including different values of the counter-ion diffusion coefficient and the dielectric constant in the solution and membrane phases. The network simulation method is used to obtain the time evolution of the electric potential, the displacement electric vector, the electric charge density and the ionic concentrations at the interface between a binary electrolyte solution and a cation-exchange membrane with total co-ion exclusion. The numerical results for the temporal evolution of the interfacial electric potential and the surface electric charge are compared with analytical solutions derived in the limit of the shortest times by considering the Poisson equation for a simple cationic diffusion process. The steady-state results are justified from the Gouy-Chapman theory for the diffuse double layer in the limits of similar and high bathing ionic concentrations with respect to the fixed-charge concentration inside the membrane. Interesting new physical insights arise from the interpretation of the process of the formation of the electric double layer at the ion exchange membrane-solution interface on the basis of a membrane model with total co-ion exclusion.

  18. Quantum size effects in Pb layers with absorbed Kondo adatoms: Determination of the exchange coupling constant

    KAUST Repository

    Schwingenschlö gl, Udo; Shelykh, I. A.

    2009-01-01

    We consider the magnetic interaction of manganese phtalocyanine (MnPc) absorbed on Pb layers that were grown on a Si substrate. We perform an ab initio calculation of the density of states and Kondo temperature as a function of the number of Pb monolayers. Comparison to experimental data [Y.-S. Fu et al., Phys. Rev. Lett. 99, 256601 (2007)] then allows us to determine the exchange coupling constant J between the spins of the adsorbed molecules and those of the Pb host. This approach gives rise to a general and reliable method for obtaining J by combining experimental and numerical results.

  19. Spin waves in the soft layer of exchange-coupled soft/hard bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Zheng-min; Ge, Su-qin; Wang, Xi-guang; Li, Zhi-xiong; Xia, Qing-lin; Wang, Dao-wei; Nie, Yao-zhuang; Guo, Guang-hua, E-mail: guogh@mail.csu.edu.cn [School of Physics and Electronics, Central South University, Changsha 410083 (China); Tang, Wei [School of Physics and Electronics, Central South University, Changsha 410083 (China); Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Zeng, Zhong-ming [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215123 (China)

    2016-05-15

    The magnetic dynamical properties of the soft layer in exchange-coupled soft/hard bilayers have been investigated numerically using a one-dimensional atomic chain model. The frequencies and spatial profiles of spin wave eigenmodes are calculated during the magnetization reversal process of the soft layer. The spin wave modes exhibit a spatially modulated amplitude, which is especially evident for high-order modes. A dynamic pinning effect of surface magnetic moment is observed. The spin wave eigenfrequency decreases linearly with the increase of the magnetic field in the uniformly magnetized state and increases nonlinearly with field when spiral magnetization configuration is formed in the soft layer.

  20. Spin waves in the soft layer of exchange-coupled soft/hard bilayers

    Directory of Open Access Journals (Sweden)

    Zheng-min Xiong

    2016-05-01

    Full Text Available The magnetic dynamical properties of the soft layer in exchange-coupled soft/hard bilayers have been investigated numerically using a one-dimensional atomic chain model. The frequencies and spatial profiles of spin wave eigenmodes are calculated during the magnetization reversal process of the soft layer. The spin wave modes exhibit a spatially modulated amplitude, which is especially evident for high-order modes. A dynamic pinning effect of surface magnetic moment is observed. The spin wave eigenfrequency decreases linearly with the increase of the magnetic field in the uniformly magnetized state and increases nonlinearly with field when spiral magnetization configuration is formed in the soft layer.

  1. Quantum size effects in Pb layers with absorbed Kondo adatoms: Determination of the exchange coupling constant

    KAUST Repository

    Schwingenschlögl, Udo

    2009-07-01

    We consider the magnetic interaction of manganese phtalocyanine (MnPc) absorbed on Pb layers that were grown on a Si substrate. We perform an ab initio calculation of the density of states and Kondo temperature as a function of the number of Pb monolayers. Comparison to experimental data [Y.-S. Fu et al., Phys. Rev. Lett. 99, 256601 (2007)] then allows us to determine the exchange coupling constant J between the spins of the adsorbed molecules and those of the Pb host. This approach gives rise to a general and reliable method for obtaining J by combining experimental and numerical results.

  2. Simulation and experiment on the thermal performance of U-vertical ground coupled heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xinguo; Chen, Zhihao; Zhao, Jun [Department of Thermal Engineering, School of Mechanical Engineering, Tianjin University, Tianjin 300072 (China)

    2006-10-15

    This paper presented both the numerical simulations and experiments on the thermal performance of U-vertical ground coupled heat exchanger (UGCHE). The variation of the ground temperature and heat balance of the system were analyzed and compared in different operation modes in the numerical simulation. Experiments on the operation performance of the ground-coupled heat pump (GCHP) with the UGCHE were carried out. It shows that the ground source can be used as the heat source/sink for GCHP systems to have higher efficiency in saving energy. To preserve the ground resource for the sustainable utilization as heat source/sink, the heat emitted to ground and heat extracted from ground should be balanced. (author)

  3. Coupling of snow and permafrost processes using the Basic Modeling Interface (BMI)

    Science.gov (United States)

    Wang, K.; Overeem, I.; Jafarov, E. E.; Piper, M.; Stewart, S.; Clow, G. D.; Schaefer, K. M.

    2017-12-01

    We developed a permafrost modeling tool based by implementing the Kudryavtsev empirical permafrost active layer depth model (the so-called "Ku" component). The model is specifically set up to have a basic model interface (BMI), which enhances the potential coupling to other earth surface processes model components. This model is accessible through the Web Modeling Tool in Community Surface Dynamics Modeling System (CSDMS). The Kudryavtsev model has been applied for entire Alaska to model permafrost distribution at high spatial resolution and model predictions have been verified by Circumpolar Active Layer Monitoring (CALM) in-situ observations. The Ku component uses monthly meteorological forcing, including air temperature, snow depth, and snow density, and predicts active layer thickness (ALT) and temperature on the top of permafrost (TTOP), which are important factors in snow-hydrological processes. BMI provides an easy approach to couple the models with each other. Here, we provide a case of coupling the Ku component to snow process components, including the Snow-Degree-Day (SDD) method and Snow-Energy-Balance (SEB) method, which are existing components in the hydrological model TOPOFLOW. The work flow is (1) get variables from meteorology component, set the values to snow process component, and advance the snow process component, (2) get variables from meteorology and snow component, provide these to the Ku component and advance, (3) get variables from snow process component, set the values to meteorology component, and advance the meteorology component. The next phase is to couple the permafrost component with fully BMI-compliant TOPOFLOW hydrological model, which could provide a useful tool to investigate the permafrost hydrological effect.

  4. Gas exchange rates across the sediment-water and air-water interfaces in south San Francisco Bay

    Science.gov (United States)

    Hartman, Blayne; Hammond, Douglas E.

    1984-01-01

    Radon 222 concentrations in the water and sedimentary columns and radon exchange rates across the sediment-water and air-water interfaces have been measured in a section of south San Francisco Bay. Two independent methods have been used to determine sediment-water exchange rates, and the annual averages of these methods agree within the uncertainty of the determinations, about 20%. The annual average of benthic fluxes from shoal areas is nearly a factor of 2 greater than fluxes from the channel areas. Fluxes from the shoal and channel areas exceed those expected from simple molecular diffusion by factors of 4 and 2, respectively, apparently due to macrofaunal irrigation. Values of the gas transfer coefficient for radon exchange across the air-water interface were determined by constructing a radon mass balance for the water column and by direct measurement using floating chambers. The chamber method appears to yield results which are too high. Transfer coefficients computed using the mass balance method range from 0.4 m/day to 1.8 m/day, with a 6-year average of 1.0 m/day. Gas exchange is linearly dependent upon wind speed over a wind speed range of 3.2–6.4 m/s, but shows no dependence upon current velocity. Gas transfer coefficients predicted from an empirical relationship between gas exchange rates and wind speed observed in lakes and the oceans are within 30% of the coefficients determined from the radon mass balance and are considerably more accurate than coefficients predicted from theoretical gas exchange models.

  5. Spin-orbit torques from interfacial spin-orbit coupling for various interfaces

    Science.gov (United States)

    Kim, Kyoung-Whan; Lee, Kyung-Jin; Sinova, Jairo; Lee, Hyun-Woo; Stiles, M. D.

    2017-09-01

    We use a perturbative approach to study the effects of interfacial spin-orbit coupling in magnetic multilayers by treating the two-dimensional Rashba model in a fully three-dimensional description of electron transport near an interface. This formalism provides a compact analytic expression for current-induced spin-orbit torques in terms of unperturbed scattering coefficients, allowing computation of spin-orbit torques for various contexts, by simply substituting scattering coefficients into the formulas. It applies to calculations of spin-orbit torques for magnetic bilayers with bulk magnetism, those with interface magnetism, a normal-metal/ferromagnetic insulator junction, and a topological insulator/ferromagnet junction. It predicts a dampinglike component of spin-orbit torque that is distinct from any intrinsic contribution or those that arise from particular spin relaxation mechanisms. We discuss the effects of proximity-induced magnetism and insertion of an additional layer and provide formulas for in-plane current, which is induced by a perpendicular bias, anisotropic magnetoresistance, and spin memory loss in the same formalism.

  6. Coupled Hydrodynamic Instability Growth on Oblique Interfaces with a Reflected Rarefaction

    Science.gov (United States)

    Rasmus, A. M.; Flippo, K. A.; di Stefano, C. A.; Doss, F. W.; Hager, J. D.; Merritt, E. C.; Cardenas, T.; Schmidt, D. W.; Kline, J. L.; Kuranz, C. C.

    2017-10-01

    Hydrodynamic instabilities play an important role in the evolution of inertial confinement fusion and astrophysical phenomena. Three of the Omega-EP long pulse beams (10 ns square pulse, 14 kJ total energy, 1.1 mm spot size) drive a supported shock across a heavy-to-light, oblique, interface. Single- and double-mode initial conditions seed coupled Richtmyer-Meshkov (RM), Rayleigh-Taylor (RT), and Kelvin-Helmholtz (KH) growth. At early times, growth is dominated by RM and KH, whereas at late times a rarefaction from laser turn-off reaches the interface, leading to decompression and RT growth. The addition of a thirty degree tilt does not alter mix width to within experimental error bars, even while significantly altering spike and bubble morphology. The results of single and double-mode experiments along with simulations using the multi-physics hydro-code RAGE will be presented. This work performed under the auspices of the U.S. Department of Energy by LANL under contract DE-AC52-06NA25396. This work is funded by the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas, Grant Number DE-NA0002956. This material is partially supported by DOE Office of Science Graduate Student Research (SCGSR) program.

  7. Application of a generalized interface module to the coupling of PARCS with both RELAP5 and TRAC-M

    Energy Technology Data Exchange (ETDEWEB)

    Barber, D.A.; Wang, W. [SCIENTECH, Inc. (United States); Miller, R.M.; Downar, T.J. [Purdue Univ., West Lafayette, IN (United States); Joo, H.G. [Korean Atomic Energy Research Inst., Seoul (Korea, Republic of); Mousseau, V.A. [Los Alamos National Lab., NM (United States); Ebert, D.E. [Nuclear Regulatory Commission, Washington, DC (United States)

    1999-04-01

    In an effort to more easily assess various combinations of 3-D neutronic/thermal-hydraulic codes, the USNRC has sponsored the development of a generalized interface module for the coupling of any thermal-hydraulics code to any spatial kinetics code. In this design, the thermal-hydraulics, general interface, and spatial kinetics codes function independently and utilize the Parallel Virtual Machine (PVM) software to manage inter-process communication. Using this interface, the USNRC version of the 3D neutron kinetics code, PARCS, has been coupled to the USNRC system analysis codes RELAP5 and TRAC-M. RELAP5/PARCS assessment results are presented for an OECD/NEA main steam line break benchmark problem. The assessment of TRAC-M/PARCS has only recently been initiated; nonetheless, the capabilities of the coupled code are presented for the OECD/NEA main steam line break benchmark problem.

  8. Application of a generalized interface module to the coupling of PARCS with both RELAPS and TRAC-M

    International Nuclear Information System (INIS)

    Barber, D.A.; Wang, W.; Miller, R.M.; Downar, T.J.; Joo, H.G.; Mousseau, V.A.; Ebert, D.E.

    1999-01-01

    In an effort to more easily assess various combinations of 3-D neutronic/thermal-hydraulic codes, the USNRC has sponsored the development of a generalized interface module for the coupling of any thermal-hydraulics code to any spatial kinetics code. In this design, the thermal-hydraulics, general interface, and spatial kinetics codes function independently and utilize the Parallel Virtual Machine (PVM) software to manage inter-process communication. Using this interface, the USNRC version of the 3D neutron kinetics code, PARCS, has been coupled to the USNRC system analysis codes RELAP5 and TRAC-M. RELAP5/PARCS assessment results are presented for an OECD/NEA main steam line break benchmark problem. The assessment of TRAC-M/PARCS has only recently been initiated; nonetheless, the capabilities of the coupled code are presented for the OECD/NEA main steam line break benchmark problem

  9. Exchange-coupled nanoscale SmCo/NdFeB hybrid magnets

    Energy Technology Data Exchange (ETDEWEB)

    Wang Dapeng; Poudyal, Narayan; Rong, Chuanbing [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Zhang Ying [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Materials Science and Engineering, Ames Laboratory, USDOE, Iowa State University, Ames, IA 50011 (United States); Kramer, M.J. [Materials Science and Engineering, Ames Laboratory, USDOE, Iowa State University, Ames, IA 50011 (United States); Liu, J. Ping, E-mail: pliu@uta.edu [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States)

    2012-09-15

    Nanoscale hybrid magnets containing SmCo{sub 5} and Nd{sub 2}Fe{sub 14}B hard magnetic phases have been produced via a novel 'in-one-pot' processing route. The grain size of the processed bulk composite materials is controlled below 20 nm. The refinement of the nanoscale morphology leads to effective inter-phase exchange coupling that results in single-phase like magnetic properties. Energy product of 14 MGOe was obtained in the isotropic nanocomposite magnets at room temperature. At elevated temperatures, the hybrid magnets have greatly improved thermal stability compared to the Nd{sub 2}Fe{sub 14}B single-phase counterpart and have substantially increased magnetization and energy products compared to the single-phase SmCo{sub 5} counterpart. - Highlights: Black-Right-Pointing-Pointer We realize interphase exchange coupling in nanoscale SmCo{sub 5}/Nd{sub 2}Fe{sub 14}B magnets. Black-Right-Pointing-Pointer We observe homogenously distributed two-phase grains with size smaller than 20 nm. Black-Right-Pointing-Pointer We observe a common Curie temperature in the hybrid magnet. Black-Right-Pointing-Pointer High-temperature magnetic properties of the hybrid magnets greatly improved. Black-Right-Pointing-Pointer Plastic deformation of composite materials leads to self-nanoscaling of grains.

  10. Role of Detergents in Conformational Exchange of a G Protein-coupled Receptor*

    Science.gov (United States)

    Chung, Ka Young; Kim, Tae Hun; Manglik, Aashish; Alvares, Rohan; Kobilka, Brian K.; Prosser, R. Scott

    2012-01-01

    The G protein-coupled β2-adrenoreceptor (β2AR) signals through the heterotrimeric G proteins Gs and Gi and β-arrestin. As such, the energy landscape of β2AR-excited state conformers is expected to be complex. Upon tagging Cys-265 of β2AR with a trifluoromethyl probe, 19F NMR was used to assess conformations and possible equilibria between states. Here, we report key differences in β2AR conformational dynamics associated with the detergents used to stabilize the receptor. In dodecyl maltoside (DDM) micelles, the spectra are well represented by a single Lorentzian line that shifts progressively downfield with activation by appropriate ligand. The results are consistent with interconversion between two or more states on a time scale faster than the greatest difference in ligand-dependent chemical shift (i.e. >100 Hz). Given that high detergent off-rates of DDM monomers may facilitate conformational exchange between functional states of β2AR, we utilized the recently developed maltose-neopentyl glycol (MNG-3) diacyl detergent. In MNG-3 micelles, spectra indicated at least three distinct states, the relative populations of which depended on ligand, whereas no ligand-dependent shifts were observed, consistent with the slow exchange limit. Thus, detergent has a profound effect on the equilibrium kinetics between functional states. MNG-3, which has a critical micelle concentration in the nanomolar regime, exhibits an off-rate that is 4 orders of magnitude lower than that of DDM. High detergent off-rates are more likely to facilitate conformational exchange between distinct functional states associated with the G protein-coupled receptor. PMID:22893704

  11. Role of detergents in conformational exchange of a G protein-coupled receptor.

    Science.gov (United States)

    Chung, Ka Young; Kim, Tae Hun; Manglik, Aashish; Alvares, Rohan; Kobilka, Brian K; Prosser, R Scott

    2012-10-19

    The G protein-coupled β(2)-adrenoreceptor (β(2)AR) signals through the heterotrimeric G proteins G(s) and G(i) and β-arrestin. As such, the energy landscape of β(2)AR-excited state conformers is expected to be complex. Upon tagging Cys-265 of β(2)AR with a trifluoromethyl probe, (19)F NMR was used to assess conformations and possible equilibria between states. Here, we report key differences in β(2)AR conformational dynamics associated with the detergents used to stabilize the receptor. In dodecyl maltoside (DDM) micelles, the spectra are well represented by a single Lorentzian line that shifts progressively downfield with activation by appropriate ligand. The results are consistent with interconversion between two or more states on a time scale faster than the greatest difference in ligand-dependent chemical shift (i.e. >100 Hz). Given that high detergent off-rates of DDM monomers may facilitate conformational exchange between functional states of β(2)AR, we utilized the recently developed maltose-neopentyl glycol (MNG-3) diacyl detergent. In MNG-3 micelles, spectra indicated at least three distinct states, the relative populations of which depended on ligand, whereas no ligand-dependent shifts were observed, consistent with the slow exchange limit. Thus, detergent has a profound effect on the equilibrium kinetics between functional states. MNG-3, which has a critical micelle concentration in the nanomolar regime, exhibits an off-rate that is 4 orders of magnitude lower than that of DDM. High detergent off-rates are more likely to facilitate conformational exchange between distinct functional states associated with the G protein-coupled receptor.

  12. A vector radiative transfer model for coupled atmosphere and ocean systems with a rough interface

    International Nuclear Information System (INIS)

    Zhai Pengwang; Hu Yongxiang; Chowdhary, Jacek; Trepte, Charles R.; Lucker, Patricia L.; Josset, Damien B.

    2010-01-01

    We report on an exact vector (polarized) radiative transfer (VRT) model for coupled atmosphere and ocean systems. This VRT model is based on the successive order of scattering (SOS) method, which virtually takes all the multiple scattering processes into account, including atmospheric scattering, oceanic scattering, reflection and transmission through the rough ocean surface. The isotropic Cox-Munk wave model is used to derive the ref and transmission matrices for the rough ocean surface. Shadowing effects are included by the shadowing function. We validated the SOS results by comparing them with those calculated by two independent codes based on the doubling/adding and Monte Carlo methods. Two error analyses related to the ocean color remote sensing are performed in the coupled atmosphere and ocean systems. One is the scalar error caused by ignoring the polarization in the whole system. The other is the error introduced by ignoring the polarization of the light transmitted through the ocean interface. Both errors are significant for the cases studied. This code fits for the next generation of ocean color study because it converges fast for absorbing medium as, for instance, ocean.

  13. A Social-Learning Approach to Hazard-Related Knowledge Exchange: Boundary Workers at the Geoscience-Humanitarian Interface

    Science.gov (United States)

    Quinn, Keira; Hope, Max; McCloskey, John

    2014-05-01

    A Social-Learning Approach to Hazard-Related Knowledge Exchange: Boundary Workers at the Geoscience-Humanitarian Interface Keira Quinn (1), Dr Max Hope (1), Professor John McCloskey (1). (1)University of Ulster Peer-reviewed science has the potential to guide policy-makers and practitioners in developing robust responses to social problems and issues. Despite advances in hazard-related science, it can often be a challenge to translate findings into useful social applications. With natural hazards affecting 2.9 billion people between 2000 and 2012 the need for hazard science to be effectively communicated is undeniable. This is particularly so in humanitarian contexts as non-governmental organisations (NGOs) play a key role in the poorer nations most affected by natural disasters. Past methods of 'knowledge transfer' have tended to lead to misinterpretations and misrepresentations of science to the extent that it is often used incorrectly or not at all. 'Knowledge exchange' is currently heralded as a more effective means of bringing about successful communication and understanding, and is characterised by the presence of shared learning. Central to a knowledge exchange approach is an understanding of the social and organisational contexts within which learning takes place. Here we use Etienne Wenger's social-learning approach to analyse selected aspects of the social context influencing knowledge exchange across the geoscience-humanitarian interface. For Wenger (2000) Communities of Practice (CoP) are bounded organisational and social groups united by their own distinct values, goals and ways of working. The boundaries surrounding CoPs can act as barriers to knowledge exchange but can also create opportunities for new shared learning by challenging existing perspectives and practice. Drawing on the findings of ongoing qualitative research into communication and learning between earthquake scientists and humanitarian NGOs in UK/Ireland, this paper outlines a number

  14. Initialization method for triple-layer exchanged coupled direct overwrite MO disk (abstract)

    Science.gov (United States)

    Hatwar, T. K.; Genova, D. J.; Palumbo, A. C.

    1993-05-01

    Increasing efforts are directed at the development of direct overwrite (DOW) capability for achieving higher data transfer rate in MO media. DOW by light intensity modulation on a triple-layer medium has shown great promise. The three layers consist of memory, reference, and intermediate layers that are weakly coupled to each other. This scheme uses an auxiliary magnet to initialize the reference layer in one direction in addition to the bias magnet. DOW is between high and low power levels. High power aligns the magnetization of the coupled layers in one direction, and low power aligns the magnetization in the opposite direction. These high (Ph) and low (Pl) powers are generally widely separated. Since the focused writing beam has a Gaussian profile, when the center of the spot does the high power writing, the ``skirt'' is actually doing the low power writing. As a result, if the background is initialized in the direction of the high power written mark, a chain-like domain pattern is observed. This leads to high writing noise. We found that such writing noise can be eliminated by initializing the background in the direction of the low power written marks. We will discuss the spin structure in exchanged coupled triple-layer films and the DOW characteristics of the disk with the two different initialization methods.

  15. Gas exchange across the air - water interface determined with man-made and natural tracers

    International Nuclear Information System (INIS)

    Wanninkhof, R.H.

    1986-01-01

    Gas exchange coefficients were determined on Rockland Lake, NY; Crowley Lake, CA; and Mono Lake, CA which have surface areas of 1 km 2 , 20 km 2 , and 190 km 2 , respectively, by injecting a small amount of man made tracer gas, sulfur hexafluoride (SF 6 ) into the lake and measuring the rate of concentration decrease in the water column with time. The dependency of gas exchange on wind speed is similar for the three lakes indicating that wind fetch is not a critical parameter for the gas exchange coefficient for lakes with sizes greater than 1 km 2 . Little gas exchange occurs for wind speeds less than 2.5 m/s and gas exchange increases linearly with wind speed from 2.5 to 6 m/s. The relationship of gas exchange and wind speed for the lakes agrees well with a compilation of earlier single wind speed - exchange coefficient measurements on lakes and oceans but they are lower than most results obtained in wind tunnels

  16. Electrosynthesis of Copper-Tetracyanoquinodimethane Based on the Coupling Charge Transfer across Water/1,2-Dichloroethane Interface

    International Nuclear Information System (INIS)

    Huang, Li; Li, Pei; Pamphile, Ndagijimana; Tian, Zhong-Qun; Zhan, Dongping

    2014-01-01

    Graphical abstract: - Highlights: • Organic semiconductor CuTCNQ is synthesized through electrochemistry of liquid/liquid interface. • A coupling charge transfer (CCT) mechanism is proposed for organic electrosynthesis. • The obtained CuTCNQ has good electrochemical and electronic properties. - Abstract: The organic salt Copper-Tetracyanoquinodimethane (CuTCNQ) is an important semiconductor used in electronics for field-effect transistors, switches and memory devices. Here we present a novel electrosynthetic method of CuTCNQ microneedles based on the coupling charge transfer across water/1,2-dichloroethane (W/1,2-DCE) interface. A HOPG electrode is covered by a small volume of 1,2-DCE solution, which is further covered by an aqueous solution to construct the W/1,2-DCE interface. When TCNQ in 1,2-DCE phase is reduced on HOPG, Cu 2+ in the aqueous solution will transfer across the W/1,2-DCE interface in order to maintain the electric neutrality. Therein CuTCNQ microneedles are formed which have good solid-state electrochemical and electronic properties. This coupling charge transfer mechanism is valuable and broadens the applications of liquid/liquid interface in organic electrosynthesis

  17. Probing the Binding Interfaces of Protein Complexes Using Gas-Phase H/D Exchange Mass Spectrometry

    DEFF Research Database (Denmark)

    Mistarz, Ulrik H; Brown, Jeffery M; Haselmann, Kim F

    2016-01-01

    Fast gas-phase hydrogen/deuterium exchange mediated by ND3 gas and measured by mass spectrometry (gas-phase HDX-MS) is a largely unharnessed, fast, and sensitive method for probing primary- and higher-order polypeptide structure. Labeling of heteroatom-bound non-amide hydrogens in a sub-milliseco......Fast gas-phase hydrogen/deuterium exchange mediated by ND3 gas and measured by mass spectrometry (gas-phase HDX-MS) is a largely unharnessed, fast, and sensitive method for probing primary- and higher-order polypeptide structure. Labeling of heteroatom-bound non-amide hydrogens in a sub......-millisecond time span after electrospray ionization by ND3 gas can provide structural insights into protein conformers present in solution. Here, we have explored the use of gas-phase HDX-MS for probing the higher-order structure and binding interfaces of protein complexes originating from native solution...

  18. Molecular (Feshbach) treatment of charge exchange Li3++He collisions. I. Energies and couplings

    International Nuclear Information System (INIS)

    Martin, F.; Riera, A.; Yanez, M.

    1986-01-01

    We point out a fundamental difference between the molecular treatment of charge exchange X/sup n/++H(1s) and X/sup n/++He(1s 2 ) collisions, which is that the latter process involves molecular states that are formally autoionizing. Then standard ab initio methods do not, in general, yield the relevant wave functions that are needed in the collision treatment, irrespective of whether quasimolecular autoionization be significant or not during the collision. We implement a particularly simple and useful form of the Feshbach formalism to calculate the energies of those two electron systems, and a method to evaluate the corresponding dynamical couplings is presented for the first time. Our implementation of this formalism together with the new computational techniques involved are presented in detail

  19. Optimization of spring exchange coupled ferrites, studied by in situ neutron diffraction

    DEFF Research Database (Denmark)

    Ahlburg, Jakob; Christensen, Mogens; Granados-Miralles, Cecilia

    Strong permanent magnets with a high energy-product are vital for a great number of electronic devices, these can be found in transformers, loudspeakers, windmills etc. Normally the preferred type of magnets are Rare Earth Metals (REM) containing magnets. REM excels since the magnetic contributio...... with varying temperature (fixed flow) or varying flow (fixed temperature) has been performed. To optimize the exchange-coupling several experiments with fixed temperature and flow, have been performed where the conversion from spinel to metal has been varied....... reduced. These metal oxides are antiferromagnetically ordered an is therefore considered a parasitic phase. However by fine-tuning the reaction temperature and hydrogen flow rate the occurrence of the phase can be minimized. In order to distinguish between Co and Fe Neutrons are chosen. Since neutrons...

  20. Enhancement of exchange coupling interaction of NdFeB/MnBi hybrid magnets

    Science.gov (United States)

    Nguyen, Truong Xuan; Nguyen, Khanh Van; Nguyen, Vuong Van

    2018-03-01

    MnBi ribbons were fabricated by melt - spinning with subsequent annealing. The MnBi ribbons were ground and mixed with NdFeB commercial Magnequench powders (MQA). The hybrid powder mixtures were subjected thrice to the annealing and ball-milling route. The hybrid magnets (100 - x)NdFeB/xMnBi, x=0, 30, 40, 50 and 100 wt% were in-mold aligned in an 18 kOe magnetic field and warm compacted at 290 °C by 2000 psi uniaxial pressure for 10 min. An enhancement of the exchange coupling of NdFeB/MnBi hybrid magnets was obtained by optimizing the magnets' microstructures via annealing and ball-milling processes. The magnetic properties of prepared NdFeB/MnBi hybrid magnets were studied and discussed in details.

  1. Exchange-coupled nanoscale SmCo/NdFeB hybrid magnets

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dapeng; Poudyal, Narayan; Rong, Chuanbing; Zhang, Ying; Kramer, Matthew J.; Liu, J. Ping

    2012-05-11

    Nanoscalehybridmagnets containing SmCo5 and Nd2Fe14B hard magnetic phases have been produced via a novel “in-one-pot” processing route. The grain size of the processed bulk composite materials is controlled below 20 nm. The refinement of the nanoscale morphology leads to effective inter-phase exchange coupling that results in single-phase like magnetic properties. Energy product of 14 MGOe was obtained in the isotropic nanocomposite magnets at room temperature. At elevated temperatures, the hybridmagnets have greatly improved thermal stability compared to the Nd2Fe14B single-phase counterpart and have substantially increased magnetization and energy products compared to the single-phase SmCo5 counterpart.

  2. Molecular (Feshbach) treatment of charge exchange Li/sup 3 +/+He collisions. I. Energies and couplings

    Energy Technology Data Exchange (ETDEWEB)

    Martin, F.; Riera, A.; Yanez, M.

    1986-05-15

    We point out a fundamental difference between the molecular treatment of charge exchange X/sup n/++H(1s) and X/sup n/++He(1s/sup 2/) collisions, which is that the latter process involves molecular states that are formally autoionizing. Then standard ab initio methods do not, in general, yield the relevant wave functions that are needed in the collision treatment, irrespective of whether quasimolecular autoionization be significant or not during the collision. We implement a particularly simple and useful form of the Feshbach formalism to calculate the energies of those two electron systems, and a method to evaluate the corresponding dynamical couplings is presented for the first time. Our implementation of this formalism together with the new computational techniques involved are presented in detail.

  3. Autonomous quantum Maxwell's demon based on two exchange-coupled quantum dots

    Science.gov (United States)

    Ptaszyński, Krzysztof

    2018-01-01

    I study an autonomous quantum Maxwell's demon based on two exchange-coupled quantum dots attached to the spin-polarized leads. The principle of operation of the demon is based on the coherent oscillations between the spin states of the system which act as a quantum iSWAP gate. Due to the operation of the iSWAP gate, one of the dots acts as a feedback controller which blocks the transport with the bias in the other dot, thus inducing the electron pumping against the bias; this leads to the locally negative entropy production. Operation of the demon is associated with the information transfer between the dots, which is studied quantitatively by mapping the analyzed setup onto the thermodynamically equivalent auxiliary system. The calculated entropy production in a single subsystem and information flow between the subsystems are shown to obey a local form of the second law of thermodynamics, similar to the one previously derived for classical bipartite systems.

  4. The influence of magnetostatic interactions in exchange-coupled composite particles

    DEFF Research Database (Denmark)

    Vokoun, D.; Beleggia, Marco; De Graef, M.

    2010-01-01

    Exchange-coupled composite (ECC) particles are the basic constituents of ECC magnetic recording media. We examine and compare two types of ECC particles: (i) core-shell structures, consisting of a hard-magnetic core and a coaxial soft-magnetic shell and (ii) conventional ECC particles, with a hard-magnetic...... core topped by a soft cylindrical element. The model we present describes the magnetic response of the two ECC particle types, taking into account all significant magnetic contributions to the energy landscape. Special emphasis is given to the magnetostatic (dipolar) interaction energy. We find...... that both the switching fields and the zero-field energy barrier depend strongly on the particle geometry. A comparison between the two types reveals that core-shell ECC particles are more effective in switching field reduction, while conventional ECC particles maintain a larger overall figure of merit....

  5. Gas exchange rates across the sediment-water andd air-water interfaces in south San Francisco Bay

    International Nuclear Information System (INIS)

    Hartman, B.; Hammond, D.E.

    1984-01-01

    Radon 222 concentrations in the water and sedimentary columns and radon exchange rates across the sediment-water and air-water interfaces have been measured in a section of south San Francisco Bay. Two independent methods have been used to determine sediment-water exchange rates, and the annual averages of these methods agree within the uncertainity of the determinations, about 20%. The annual average of bethic fluxes from shoal areas is nearly a factor of 2 greater than fluxes from the channel areas. Fluxes from the shoal and channel areas exceed those expected from simple molecular diffusion by factors of 4 and 2, respectively, apparently due to macrofaunal irrigation. Values of the gas transfer coefficient for radon exchange across the air-water inteface were determined by constructing a radon mass balance for the water column and by direct measurement using floating chambers. The chamber method appears to yield results which are too high. Transfer coefficients computed using the mass balance method range from 0.4 m/day to 1.8 m/day, with a 6-year average of 1.0 m/day. Gas exchange is linearly dependent upon wind speed over a wind speed range of 3.2--6.4 m/s, but shows no dependence upon current velocity. Gas transfer coefficients predicted from an empirical relationship between gas exchange rates and wind speed observed in lakes and the oceans are within 30% of the coefficients determined from the radon mass balance and are considerably more accurate than coefficients predicted from theoretical gas exchange models

  6. Direct dimethyl ether (DME) synthesis through a thermally coupled heat exchanger reactor

    International Nuclear Information System (INIS)

    Vakili, R.; Pourazadi, E.; Setoodeh, P.; Eslamloueyan, R.; Rahimpour, M.R.

    2011-01-01

    Compared to some of the alternative fuel candidates such as methane, methanol and Fischer-Tropsch fuels, dimethyl ether (DME) seems to be a superior candidate for high-quality diesel fuel in near future. The direct synthesis of DME from syngas would be more economical and beneficial in comparison with the indirect process via methanol synthesis. Multifunctional auto-thermal reactors are novel concepts in process intensification. A promising field of applications for these concepts could be the coupling of endothermic and exothermic reactions in heat exchanger reactors. Consequently, in this study, a double integrated reactor for DME synthesis (by direct synthesis from syngas) and hydrogen production (by the cyclohexane dehydrogenation) is modelled based on the heat exchanger reactors concept and a steady-state heterogeneous one-dimensional mathematical model is developed. The corresponding results are compared with the available data for a pipe-shell fixed bed reactor for direct DME synthesis which is operating at the same feed conditions. In this novel configuration, DME production increases about 600 Ton/year. Also, the effects of some operational parameters such as feed flow rates and the inlet temperatures of exothermic and endothermic sections on reactor behaviour are investigated. The performance of the reactor needs to be proven experimentally and tested over a range of parameters under practical operating conditions.

  7. Evidence of exchange-coupled behavior in chromium-cobalt ferrite nanoparticles

    Science.gov (United States)

    Tanbir, Kamar; Sharma, Lalit Kumar; Aakash; Singh, Rakesh Kumar; Choubey, Ravi Kant; Mukherjee, Samrat

    2018-06-01

    Cr doped cobalt ferrite nanoparticles were synthesized with the generic formula Co1-xCrxFe2O4 (x = 0, 0.05, 0.15, 0.25) through standard chemical co-precipitation method. XRD studies confirmed the pure spinel cubic structure belonging to Fd 3 bar m space group. From the Williamson-Hall plots, crystallite sizes were found to lie within the range (42 ± 1) nm for the different doped samples. The lattice parameter was found to decrease linearly with increase in the concentration of Cr3+ ion. The magnetic behavior of the samples was determined by M-H studies at 300 K, field cooled (5 T) at 5 K and temperature dependent studies. The M-H at 300 K show soft magnetic behavior whereas the M-H plots at 5 K predict the existence of in-homogeneity of the exchange interactions due to strong exchange coupling between the spins at the core and the surface of the nanoparticles.

  8. Critical fields of an exchange coupled two-layer composite particle

    International Nuclear Information System (INIS)

    Goll, D.; Kronmueller, H.

    2008-01-01

    High-density recording systems require magnetic bits with perpendicular easy axis and large magnetocrystalline anisotropy to guarantee thermal stability. However, the large magnetic fields up to 10 T for the reversal of magnetization cannot be afforded by conventional write heads. Therefore, composite exchange coupled spring systems of soft and hard magnetic layers may be used to reduce the switching field. In this case the reversal of magnetization in general takes place in two steps: a nucleation process in the soft layer and a depinning process for the displacement of the domain wall at the phase boundary of the soft and the hard magnetic layer. The nucleation and depinning fields are determined on the basis of the continuum theory of micromagnetism. It is shown that the nucleation fields decrease according to a 1/L 2 law with increasing thickness L of the soft layer and the depinning field of the charged Neel wall may be reduced by factors of 3-6 in comparison with the ideal nucleation field of the hard magnetic phase. One-step rectangular hysteresis loops are obtained for thicknesses of the soft layer smaller than the exchange length of the magnetostatic field

  9. Large coercivity and unconventional exchange coupling in manganese-oxide-coated manganese—gallium nanoparticles

    International Nuclear Information System (INIS)

    Feng Jun-Ning; Liu Wei; Geng Dian-Yu; Ma Song; Yu Tao; Zhao Xiao-Tian; Dai Zhi-Ming; Zhao Xin-Guo; Zhang Zhi-Dong

    2014-01-01

    The microstructures and magnetic properties of nanoparticles, each composed of an antiferromagnetic (AFM) manganese-oxide shell and a ferromagnetic-like core of manganese—gallium (MnGa) compounds, are studied. The core-shell structure is confirmed by transmission electron microscope (TEM). The ferromagnetic-like core contains three kinds of MnGa binary compounds, i.e., ferrimagnetic (FI) D0 22 -type Mn 3 Ga, ferromagnetic (FM) Mn 8 Ga 5 , and AFM D0 19 -type Mn 3 Ga, of which the first two correspond respectively to a hard magnetic phase and to a soft one. Decoupling effect between these two phases is found at low temperature, which weakens gradually with increasing temperature and disappears above 200 K. The exchange bias (EB) effect is observed simultaneously, which is caused by the exchange coupling between the AFM shell and FM-like core. A large coercivity of 6.96 kOe (1 Oe = 79.5775 A·m −1 ) and a maximum EB value of 0.45 kOe are achieved at 300 K and 200 K respectively. (special topic — international conference on nanoscience and technology, china 2013)

  10. Exchange coupled CoPt/FePtC media for heat assisted magnetic recording

    Science.gov (United States)

    Dutta, Tanmay; Piramanayagam, S. N.; Ru, Tan Hui; Saifullah, M. S. M.; Bhatia, C. S.; Yang, Hyunsoo

    2018-04-01

    L10 FePtC granular media are being studied as potential future magnetic recording media and are set to be used in conjunction with heat assisted magnetic recording (HAMR) to enable recording at write fields within the range of current day recording heads. Media structures based on a FePtC storage layer and a capping layer can alleviate the switching field distribution (SFD) requirements of HAMR and reduce the noise originating from the writing process. However, the current designs suffer from SFD issues due to high temperature writing. To overcome this problem, we study a CoPt/FePtC exchange coupled composite structure, where FePtC serves as the storage layer and CoPt (with higher Curie temperature, Tc) as the capping layer. CoPt remains ferromagnetic at near Tc of FePtC. Consequently, the counter exchange energy from CoPt would reduce the noise resulting from the adjacent grain interactions during the writing process. CoPt/FePtC bilayer samples with different thicknesses of CoPt were investigated. Our studies found that CoPt forms a continuous layer at a thickness of 6 nm and leads to considerable reduction in the saturation field and its distribution.

  11. Exciton behavior in GaAs/AlGaAs coupled double quantum wells with interface disorder

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, E.M., E-mail: eldermantovani@yahoo.com.b [Departamento de Fisica, Universidade Estadual de Londrina, CP 6001, CEP 86051-970 Londrina, Parana (Brazil); Duarte, J.L.; Pocas, L.C.; Dias, I.F.L.; Laureto, E. [Departamento de Fisica, Universidade Estadual de Londrina, CP 6001, CEP 86051-970 Londrina, Parana (Brazil); Quivy, A.A.; Lamas, T.E. [Laboratorio de Novos Materiais Semicondutores, Instituto de Fisica, Universidade de Sao Paulo, CP 66318, CEP 05315-970 Sao Paulo (Brazil)

    2010-03-15

    In this work, we present a detailed study on the optical properties of two GaAs/Al{sub 0.35}Ga{sub 0.65}As coupled double quantum wells (CDQWs) with inter-well barriers of different thicknesses, by using photoluminescence (PL) spectroscopy. The two CDQWs were grown in a single sample, assuring very similar experimental conditions for measurements of both. The PL spectrum of each CDQW exhibits two recombination channels which can be accurately identified as the excitonic e{sub 1}-hh{sub 1} transitions originated from CDQWs of different effective dimensions. The PL spectra characteristics and the behavior of the emissions as a function of temperature and excitation power are interpreted in the scenario of the bimodal interface roughness model, taking into account the exciton migration between the two regions considered in this model and the difference in the potential fluctuation levels between those two regions. The details of the PL spectra behavior as a function of excitation power are explained in terms of the competition between the band gap renormalization (BGR) and the potential fluctuation effects. The results obtained for the two CDQWs, which have different degrees of potential fluctuation, are also compared and discussed.

  12. FORC-study of magnetization reversal of L10-FePt based exchange coupled composite films

    Directory of Open Access Journals (Sweden)

    Gongyuan Situ

    2017-05-01

    Full Text Available Perpendicular exchange coupled composite structures were prepared, utilizing L10-FePt as hard layer and [Co/Ni]N multilayer as soft layer. Magnetic characteristics revealed the gradually change of the magnetization reversal mechanism from incoherent rotational mode to dominant wall motion as the thickness of soft layer increases. Furthermore, FORC analysis were employed to characterize the interactions of our ECC magnetic system, the result indicates that the exchange coupling interaction were enhanced with the increasing thickness of soft layer.

  13. Interlayer exchange coupling, crystalline and magnetic structure in Fe/CsCl-FeSi multilayers grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Dekoster, J.; Degroote, S.; Meersschaut, J.; Moons, R.; Vantomme, A. [K.U. Leuven, Instituut voor Kern- en Stralingsfysica (Belgium); Bottyan, L.; Deak, L.; Szilagyi, E.; Nagy, D.L. [KFKI Research Institute for Particle and Nuclear Physics (Hungary); Baron, A.Q.R. [European Synchrotron Radiation Facility (France); Langouche, G. [K.U. Leuven, Instituut voor Kern- en Stralingsfysica (Belgium)

    1999-09-15

    Crystalline and magnetic structure as well as the interlayer exchange coupling in MBE grown Fe/FeSi multilayers are investigated. From conversion electron Moessbauer spectroscopy and ion beam channeling measurements the spacer FeSi material is found to be stabilized in a crystalline metastable metallic FeSi phase with the CsCl structure. Strong non-oscillatory interlayer exchange coupling is identified with magnetometry and synchrotron Moessbauer reflectometry. From the fits of the time spectrum and the resonant {phi}-{phi} scans a model for the sublayer magnetization of the multilayer is deduced.

  14. North American coastal carbon stocks and exchanges among the coupled ecosystems of tidal wetlands and estuaries

    Science.gov (United States)

    Windham-Myers, L.; Cai, W. J.

    2017-12-01

    The development of the 2nd State of the Carbon Cycle Report (SOCCR-2) has recognized a significant role of aquatic ecosystems, including coastal zones, in reconciling some of the gaps associated with the North American carbon (C) budget. Along with a large community of coauthors, we report major C stocks and fluxes for tidal wetlands and estuaries of Canada, Mexico and the United States. We find divergent patterns between these coupled ecosystems, with tidal wetlands largely serving as CO2 sinks (net autotrophic), and open-water estuaries largely serving as CO2 sources (net heterotrophic). We summarized measurements across 4 continental regions - East Coast, Gulf of Mexico, West Coast, and High Latitudes - to assess spatial variability and datagaps in our understanding of coastal C cycling. Subtracting estuarine outgassing of 10 ± 10 Tg C yr-1 from the tidal wetland uptake of 23 ± 10 Tg C yr-1 leaves a net uptake of the combined system of 13 ± 14 Tg C yr-1. High uncertainty for net atmospheric C exchange in this combined coastal system is further complicated by spatially and temporally dynamic boundaries, as well as terrestrial C sources. Tidal wetlands are among the most productive ecosystems on earth and are capable of continuously accumulating organic C in their sediments as a result of environmental conditions that inhibit organic matter decomposition. Estuaries have more interannual variability in C dynamics than those of tidal wetlands, reflecting the estuarine balance of exchanges with terrestrial watersheds, tidal wetlands, and the continental shelf. Whereas tidal, subtidal and estuarine maps are of limited accuracy at larger scales, North America likely represents less than 1/10 of global distributions of coastal wetland habitats. Coupled land-ocean C flux models are increasingly robust but lacking much of the data needed for parameterization and validation. Accurate boundary maps and synoptic monitoring data on air-water CO2 exchange may be developed

  15. A modified CAS-CI approach for an efficient calculation of magnetic exchange coupling constants

    Science.gov (United States)

    Fink, Karin; Staemmler, Volker

    2013-09-01

    A modification of the conventional wavefunction-based CAS-CI method for the calculation of magnetic exchange coupling constants J in small molecules and transition metal complexes is presented. In general, CAS-CI approaches yield much too small values for J since the energies of the important charge transfer configurations are calculated with the ground state orbitals and are therefore much too high. In the present approach we improve these energies by accounting for the relaxation of the orbitals in the charge transfer configurations. The necessary relaxation energies R can be obtained in separate calculations using mononuclear or binuclear model systems. The method is applied to a few examples, small molecules, binuclear transition metal complexes, and bulk NiO. It allows to obtaining fairly reliable estimates for J at costs that are not higher than those of conventional CAS-CI calculations. Therefore, extended and very time-consuming perturbation theory (PT2), configuration interaction (CI), or coupled cluster (CC) schemes on top of the CAS-CI calculation can be avoided and the modified CAS-CI (MCAS-CI) approach can be applied to rather large systems.

  16. Effect of Hartree-Fock exact exchange on intramolecular magnetic coupling constants of organic diradicals

    Science.gov (United States)

    Cho, Daeheum; Ko, Kyoung Chul; Ikabata, Yasuhiro; Wakayama, Kazufumi; Yoshikawa, Takeshi; Nakai, Hiromi; Lee, Jin Yong

    2015-01-01

    The intramolecular magnetic coupling constant (J) of diradical systems linked with five- or six-membered aromatic rings was calculated to obtain the scaling factor (experimental J/calculated J ratio) for various density functional theory (DFT) functionals. Scaling factors of group A (PBE, TPSSh, B3LYP, B97-1, X3LYP, PBE0, and BH&HLYP) and B (M06-L, M06, M06-2X, and M06-HF) were shown to decrease as the amount of Hartree-Fock exact exchange (HFx) increases, in other words, overestimation of calculated J becomes more severe as the HFx increases. We further investigated the effect of HFx fraction of DFT functional on J value, spin contamination, and spin density distributions by comparing the B3LYP analogues containing different amount of HFx. It was revealed that spin contamination and spin densities at each atom increases as the HFx increases. Above all, newly developed BLYP-5 functional, which has 5% of HFx, was found to have the scaling factor of 1.029, indicating that calculated J values are very close to that of experimental values without scaling. BLYP-5 has potential to be utilized for accurate evaluation of intramolecular magnetic coupling constant (J) of diradicals linked by five- or six-membered aromatic ring couplers.

  17. Magnetization reversal dynamics in exchange-coupled NiO - Co bilayers

    International Nuclear Information System (INIS)

    Camarero, J.; Pennec, Y.; Bonfim, M.; Vogel, J.; Pizzini, S.; Fontaine, A.; Cartier, M.; Fettar, F.; Dieny, B.

    2001-01-01

    We performed a detailed study of the magnetization reversal in polycrystalline exchange-coupled NiO/Co bilayers over 10 decades of field sweep rate dH/dt for different NiO and Co thicknesses. For all sweep rates and thicknesses, the symmetry of the hysteresis loops shows that an identical pinning strength has to be overcome in both directions of the reversal. At low dH/dt the reversal is governed by domain wall displacement while domain nucleation is dominant at higher ones. The dH/dt at which the transition between the two regimes takes place depends on the relative thickness of the NiO and Co layers. It increases (decreases) when the Co (NiO) thickness is increased. Experimentally, it was found that the energy barrier varies linearly with the square root of the area corresponding to the activation (Barkhausen) volume which is consistent with a random walk model of the coupling between antiferromagnetic and ferromagnetic layers. The results can be explained in terms of a thermally activated switching of the NiO magnetization dragged by the Co reversal. [copyright] 2001 American Institute of Physics

  18. Magnetic exchange couplings from constrained density functional theory: an efficient approach utilizing analytic derivatives.

    Science.gov (United States)

    Phillips, Jordan J; Peralta, Juan E

    2011-11-14

    We introduce a method for evaluating magnetic exchange couplings based on the constrained density functional theory (C-DFT) approach of Rudra, Wu, and Van Voorhis [J. Chem. Phys. 124, 024103 (2006)]. Our method shares the same physical principles as C-DFT but makes use of the fact that the electronic energy changes quadratically and bilinearly with respect to the constraints in the range of interest. This allows us to use coupled perturbed Kohn-Sham spin density functional theory to determine approximately the corrections to the energy of the different spin configurations and construct a priori the relevant energy-landscapes obtained by constrained spin density functional theory. We assess this methodology in a set of binuclear transition-metal complexes and show that it reproduces very closely the results of C-DFT. This demonstrates a proof-of-concept for this method as a potential tool for studying a number of other molecular phenomena. Additionally, routes to improving upon the limitations of this method are discussed. © 2011 American Institute of Physics

  19. Effect of Hartree-Fock exact exchange on intramolecular magnetic coupling constants of organic diradicals

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Daeheum; Ko, Kyoung Chul; Lee, Jin Yong, E-mail: jinylee@skku.edu [Department of Chemistry, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Ikabata, Yasuhiro; Wakayama, Kazufumi; Yoshikawa, Takeshi [Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555 (Japan); Nakai, Hiromi, E-mail: nakai@waseda.jp [Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555 (Japan); Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555 (Japan); CREST, Japan Science and Technology Agency, Tokyo 102-0075 (Japan); Elements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, Katsura, Kyoto 615-8520 (Japan)

    2015-01-14

    The intramolecular magnetic coupling constant (J) of diradical systems linked with five- or six-membered aromatic rings was calculated to obtain the scaling factor (experimental J/calculated J ratio) for various density functional theory (DFT) functionals. Scaling factors of group A (PBE, TPSSh, B3LYP, B97-1, X3LYP, PBE0, and BH and HLYP) and B (M06-L, M06, M06-2X, and M06-HF) were shown to decrease as the amount of Hartree-Fock exact exchange (HFx) increases, in other words, overestimation of calculated J becomes more severe as the HFx increases. We further investigated the effect of HFx fraction of DFT functional on J value, spin contamination, and spin density distributions by comparing the B3LYP analogues containing different amount of HFx. It was revealed that spin contamination and spin densities at each atom increases as the HFx increases. Above all, newly developed BLYP-5 functional, which has 5% of HFx, was found to have the scaling factor of 1.029, indicating that calculated J values are very close to that of experimental values without scaling. BLYP-5 has potential to be utilized for accurate evaluation of intramolecular magnetic coupling constant (J) of diradicals linked by five- or six-membered aromatic ring couplers.

  20. Effective Application of Bicelles for Conformational Analysis of G Protein-Coupled Receptors by Hydrogen/Deuterium Exchange Mass Spectrometry

    Science.gov (United States)

    Duc, Nguyen Minh; Du, Yang; Thorsen, Thor S.; Lee, Su Youn; Zhang, Cheng; Kato, Hideaki; Kobilka, Brian K.; Chung, Ka Young

    2015-05-01

    G protein-coupled receptors (GPCRs) have important roles in physiology and pathology, and 40% of drugs currently on the market target GPCRs for the treatment of various diseases. Because of their therapeutic importance, the structural mechanism of GPCR signaling is of great interest in the field of drug discovery. Hydrogen/deuterium exchange mass spectrometry (HDX-MS) is a useful tool for analyzing ligand binding sites, the protein-protein interaction interface, and conformational changes of proteins. However, its application to GPCRs has been limited for various reasons, including the hydrophobic nature of GPCRs and the use of detergents in their preparation. In the present study, we tested the application of bicelles as a means of solubilizing GPCRs for HDX-MS studies. GPCRs (e.g., β2-adrenergic receptor [β2AR], μ-opioid receptor, and protease-activated receptor 1) solubilized in bicelles produced better sequence coverage (greater than 90%) than GPCRs solubilized in n-dodecyl-β-D-maltopyranoside (DDM), suggesting that bicelles are a more effective method of solubilization for HDX-MS studies. The HDX-MS profile of β2AR in bicelles showed that transmembrane domains (TMs) undergo lower deuterium uptake than intracellular or extracellular regions, which is consistent with the fact that the TMs are highly ordered and embedded in bicelles. The overall HDX-MS profiles of β2AR solubilized in bicelles and in DDM were similar except for intracellular loop 3. Interestingly, we detected EX1 kinetics, an important phenomenon in protein dynamics, at the C-terminus of TM6 in β2AR. In conclusion, we suggest the application of bicelles as a useful method for solubilizing GPCRs for conformational analysis by HDX-MS.

  1. A Sweet Spot for Molecular Diagnostics: Coupling Isothermal Amplification and Strand Exchange Circuits to Glucometers

    Science.gov (United States)

    Du, Yan; Hughes, Randall A.; Bhadra, Sanchita; Jiang, Yu Sherry; Ellington, Andrew D.; Li, Bingling

    2015-06-01

    Strand exchange nucleic acid circuitry can be used to transduce isothermal nucleic acid amplification products into signals that can be readable on an off-the-shelf glucometer. Loop-mediated isothermal amplification (LAMP) is limited by the accumulation of non-specific products, but nucleic acid circuitry can be used to probe and distinguish specific amplicons. By combining this high temperature isothermal amplification method with a thermostable invertase, we can directly transduce Middle-East respiratory syndrome coronavirus and Zaire Ebolavirus templates into glucose signals, with a sensitivity as low as 20-100 copies/μl, equating to atto-molar (or low zepto-mole). Virus from cell lysates and synthetic templates could be readily amplified and detected even in sputum or saliva. An OR gate that coordinately triggered on viral amplicons further guaranteed fail-safe virus detection. The method describes has potential for accelerating point-of-care applications, in that biological samples could be applied to a transducer that would then directly interface with an off-the-shelf, approved medical device.

  2. PHYSICAL EXCHANGES AT THE AIR-SEA INTERFACE UK-SOLAS Field Measurements

    NARCIS (Netherlands)

    Brooks, Ian M.; Yelland, Margaret J.; Upstill-Goddard, Robert C.; Nightingale, Philip D.; Archer, Steve; d'Asaro, Ericic; Beale, Rachael; Beatty, Cory; Blomquist, Byron; Bloom, A. Anthony; Brooks, Barbara J.; Cluderay, John; Coles, David; Dacey, John; DeGrandpre, Michael; Dixon, Jo; Drennan, William M.; Gabriele, Joseph; Goldson, Laura; Hardman-Mountford, Nick; Hill, Martin K.; Horn, Matt; Hsueh, Ping-Chang; Huebert, Barry; de Leeuw, Gerrit; Leighton, Timothy G.; Liddicoat, Malcolm; Lingard, Justin J. N.; McNeil, Craig; McQuaid, James B.; Moat, Ben I.; Moore, Gerald; Neill, Craig; Norris, Sarah J.; O'Doherty, Simon; Pascal, Robin W.; Prytherch, John; Rebozo, Mike; Sahlee, Erik; Salter, Matt; Schuster, Ute; Skjelvan, Ingunn; Slagter, Hans; Smith, Michael H.; Smith, Paul D.; Srokosz, Meric; Stephens, John A.; Taylor, Peter K.; Telszewski, Maciej; Walsh, Roisin; Ward, Brian; Woolf, David K.; Young, Dickon; Zemmelink, Henk

    As part of the U. K. contribution to the international Surface Ocean-Lower Atmosphere Study, a series of three related projects-DOGEE, SEASAW, and HiWASE-undertook experimental studies of the processes controlling the physical exchange of gases and sea spray aerosol at the sea surface. The studies

  3. Interlayer exchange coupling, dipolar coupling and magnetoresistance in Fe/MgO/Fe trilayers with a subnanometer MgO barrier

    Energy Technology Data Exchange (ETDEWEB)

    Kozioł-Rachwał, A. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); Skowroński, W.; Frankowski, M. [AGH University of Science and Technology, Department of Electronics, al. Mickiewicza 30, 30-059 Kraków (Poland); Chęciński, J. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); AGH University of Science and Technology, Department of Electronics, al. Mickiewicza 30, 30-059 Kraków (Poland); Ziętek, S.; Rzeszut, P. [AGH University of Science and Technology, Department of Electronics, al. Mickiewicza 30, 30-059 Kraków (Poland); Ślęzak, M.; Matlak, K.; Ślęzak, T. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); Stobiecki, T. [AGH University of Science and Technology, Department of Electronics, al. Mickiewicza 30, 30-059 Kraków (Poland); Korecki, J. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Kraków (Poland)

    2017-02-15

    Fe/MgO/Fe trilayers with a subnanometer MgO tunnel barrier were grown by molecular beam epitaxy. Longitudinal magnetooptic Kerr effect measurements confirmed the existence of the antiferromagnetic interlayer exchange coupling (IEC) between the Fe layers for 2 Åcoupling was enhanced for the trilayer grown on a homoepitaxial MgO buffer layer, and its IEC constant was estimated to be −3.3 erg/cm{sup 2} at a MgO thickness of 2.7 Å. After magnetic characterization, the sample was patterned into circular-shaped pillars with diameters ranging from 200 nm to 520 nm. We showed that the dipolar coupling that appeared after the nanofabrication process modified the effective coupling between layers, and we determined dependence of the dipolar coupling on the pillar diameter. Finally, magnetoresistance (MR) was measured as a function of MgO thickness (d{sub MgO}), and a non-zero MR was found for the MgO as thin as 3.4 Å. Extrapolation of the MR (d{sub MgO}) dependence to MR=0 allowed us to determine the length of the pinholes in our sample, which was estimated to be (3.2±0.5) Å. - Highlights: • Strong antiferromagnetic (AFM) interlayer exchange coupling (IEC) between Fe layers in Fe/MgO/Fe. • After nanofabrication the effective AFM IEC is enhanced due to the dipolar coupling. • The dipolar coupling that appeared after the nanofabrication process modified the effective coupling between layers. • Non-zero magnetoresistance values registered for the Fe/MgO/Fe trilayers with the MgO spacers as thin as 3.4 Å.

  4. Origin of open recoil curves in L1_0-A1 FePt exchange coupled nanocomposite thin film

    International Nuclear Information System (INIS)

    Goyal, Rajan; Kapoor, Akanksha; Lamba, S.; Annapoorni, S.

    2016-01-01

    Mixed phase FePt systems with intergranular coupling may be looked upon as natural exchange spring systems. The coupling strength between the soft and hard phase in these systems can be analyzed using recoil curves. However, the origin of open recoil curves depicting the breakdown of exchange coupling or anisotropy variation in hard phase is still an ambiguity and requires an in-depth analysis. In order to investigate this, an analysis of the recoil curves for L1_0–A1 FePt nanocomposite thin films of varying thickness have been performed. The switching field distribution reveals that the maximum of openness of recoil curve is directly proportional to the amount of uncoupled soft phase present in the system. The coupling between the hard and soft phase is also found to increase with the thickness of the film. Monte Carlo simulations on a model three dimensional array of interacting nanomagnetic grains provide further insight into the effect of inter granular exchange interactions between the soft and hard phases. - Highlights: • L1_0-A1 FePt nanocomposites thin films of different thickness have been fabricated by DC sputtering. • Hysteresis curve measurements exhibit perfect single phase (L1_0) like behavior for thicker films. • SFD reveals that the openness of recoil curves is directly linked with the amount of uncoupled soft (A1) phase. • Monte Carlo simulation predicts that the extent of exchange interaction increases with thickness of the film.

  5. Origin of open recoil curves in L1{sub 0}-A1 FePt exchange coupled nanocomposite thin film

    Energy Technology Data Exchange (ETDEWEB)

    Goyal, Rajan [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Kapoor, Akanksha [M. Tech Nanoscience and Nanotechnology, University of Delhi, Delhi 110007 (India); Lamba, S. [School of Sciences, Indira Gandhi National Open University, New Delhi 110068 (India); Annapoorni, S., E-mail: annapoornis@yahoo.co.in [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

    2016-11-15

    Mixed phase FePt systems with intergranular coupling may be looked upon as natural exchange spring systems. The coupling strength between the soft and hard phase in these systems can be analyzed using recoil curves. However, the origin of open recoil curves depicting the breakdown of exchange coupling or anisotropy variation in hard phase is still an ambiguity and requires an in-depth analysis. In order to investigate this, an analysis of the recoil curves for L1{sub 0}–A1 FePt nanocomposite thin films of varying thickness have been performed. The switching field distribution reveals that the maximum of openness of recoil curve is directly proportional to the amount of uncoupled soft phase present in the system. The coupling between the hard and soft phase is also found to increase with the thickness of the film. Monte Carlo simulations on a model three dimensional array of interacting nanomagnetic grains provide further insight into the effect of inter granular exchange interactions between the soft and hard phases. - Highlights: • L1{sub 0}-A1 FePt nanocomposites thin films of different thickness have been fabricated by DC sputtering. • Hysteresis curve measurements exhibit perfect single phase (L1{sub 0}) like behavior for thicker films. • SFD reveals that the openness of recoil curves is directly linked with the amount of uncoupled soft (A1) phase. • Monte Carlo simulation predicts that the extent of exchange interaction increases with thickness of the film.

  6. Towards quantifying the role of exact exchange in the prediction hydrogen bond spin-spin coupling constants involving fluorine

    Energy Technology Data Exchange (ETDEWEB)

    San Fabián, J.; Omar, S.; García de la Vega, J. M., E-mail: garcia.delavega@uam.es [Departamento de Química Física Aplicada, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid (Spain)

    2016-08-28

    The effect of a fraction of Hartree-Fock exchange on the calculated spin-spin coupling constants involving fluorine through a hydrogen bond is analyzed in detail. Coupling constants calculated using wavefunction methods are revisited in order to get high-level calculations using the same basis set. Accurate MCSCF results are obtained using an additive approach. These constants and their contributions are used as a reference for density functional calculations. Within the density functional theory, the Hartree-Fock exchange functional is split in short- and long-range using a modified version of the Coulomb-attenuating method with the SLYP functional as well as with the original B3LYP. Results support the difficulties for calculating hydrogen bond coupling constants using density functional methods when fluorine nuclei are involved. Coupling constants are very sensitive to the Hartree-Fock exchange and it seems that, contrary to other properties, it is important to include this exchange for short-range interactions. Best functionals are tested in two different groups of complexes: those related with anionic clusters of type [F(HF){sub n}]{sup −} and those formed by difluoroacetylene and either one or two hydrogen fluoride molecules.

  7. Magnetic self-assembly for the synthesis of magnetically exchange coupled MnBi/Fe–Co composites

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Xia [Department of Chemical and Biological Engineering and MINT Center, The University of Alabama, Tuscaloosa, AL 35487 (United States); Hong, Yang-Ki, E-mail: ykhong@eng.ua.edu [Department of Electrical and Computer Engineering and MINT Center, The University of Alabama, Tuscaloosa, AL 35487 (United States); Park, Jihoon; Lee, Woncheol [Department of Electrical and Computer Engineering and MINT Center, The University of Alabama, Tuscaloosa, AL 35487 (United States); Lane, Alan M. [Department of Chemical and Biological Engineering and MINT Center, The University of Alabama, Tuscaloosa, AL 35487 (United States); Cui, Jun [Energy and Environment Directorate, Pacific Northwestern National Laboratory, Richland, WA 99354 (United States)

    2015-11-15

    Exchange coupled hard/soft MnBi/Fe–Co core/shell structured composites were synthesized using a magnetic self-assembly process. MnBi particles were prepared by arc-melting, and Fe–Co nanoparticles were synthesized by an oleic acid assisted chemical reduction method. Grinding a mixture of micron-sized MnBi and Fe–Co nanoparticles in hexane resulted in MnBi/Fe–Co core/shell structured composites. The MnBi/Fe–Co (95/5 wt%) composites showed smooth magnetic hysteresis loops, enhanced remanent magnetization, and positive values in the ΔM curve, indicating exchange coupling between MnBi and Fe–Co particles. - Graphical abstract: Both MnBi and Fe–Co particles were dispersed in hexane for grinding. Because of the oleic acid used during the Fe–Co nanoparticle synthesis, they could be well dispersed in hexane. During the grinding, the size of MnBi particles was decreased, hexane was evaporated, and the Fe–Co nanoparticles were concentrated in the solvent and magnetically attracted by MnBi particles, forming a core/shell structure. - Highlights: • Exchange coupled MnBi/Fe–Co composites are synthesized through magnetic selfassembly. • Magnetic exchange coupling is demonstrated by smooth magnetic hysteresis loops, enhanced remanent magnetization, and dominant positive peak in the ΔM curve. • The experimental results in magnetic properties are close to the theoretical calculation results.

  8. Coupled carbon-water exchange of the Amazon rain forest. I. Model description, parameterization and sensitivity analysis

    NARCIS (Netherlands)

    Simon, E.; Meixner, F.X.; Ganzeveld, L.N.; Kesselmeier, J.

    2005-01-01

    Detailed one-dimensional multilayer biosphere-atmosphere models, also referred to as CANVEG models, are used for more than a decade to describe coupled water-carbon exchange between the terrestrial vegetation and the lower atmosphere. Within the present study, a modified CANVEG scheme is described.

  9. Intricate but tight coupling of spiracular activity and abdominal ventilation during locust discontinuous gas exchange cycles.

    Science.gov (United States)

    Talal, Stav; Gefen, Eran; Ayali, Amir

    2018-03-15

    Discontinuous gas exchange (DGE) is the best studied among insect gas exchange patterns. DGE cycles comprise three phases, which are defined by their spiracular state: closed, flutter and open. However, spiracle status has rarely been monitored directly; rather, it is often assumed based on CO 2 emission traces. In this study, we directly recorded electromyogram (EMG) signals from the closer muscle of the second thoracic spiracle and from abdominal ventilation muscles in a fully intact locust during DGE. Muscular activity was monitored simultaneously with CO 2 emission, under normoxia and under various experimental oxic conditions. Our findings indicate that locust DGE does not correspond well with the commonly described three-phase cycle. We describe unique DGE-related ventilation motor patterns, coupled to spiracular activity. During the open phase, when CO 2 emission rate is highest, the thoracic spiracles do not remain open; rather, they open and close rapidly. This fast spiracle activity coincides with in-phase abdominal ventilation, while alternating with the abdominal spiracle and thus facilitating a unidirectional air flow along the main trachea. A change in the frequency of rhythmic ventilation during the open phase suggests modulation by intra-tracheal CO 2 levels. A second, slow ventilatory movement pattern probably serves to facilitate gas diffusion during spiracle closure. Two flutter-like patterns are described in association with the different types of ventilatory activity. We offer a modified mechanistic model for DGE in actively ventilating insects, incorporating ventilatory behavior and changes in spiracle state. © 2018. Published by The Company of Biologists Ltd.

  10. Spin Quantum Tunneling via Entangled States in a Dimer of Exchange-Coupled Single-Molecule Magnets

    Science.gov (United States)

    Tiron, R.; Wernsdorfer, W.; Foguet-Albiol, D.; Aliaga-Alcalde, N.; Christou, G.

    2003-11-01

    A new family of supramolecular, antiferromagnetically exchange-coupled dimers of single-molecule magnets (SMMs) has recently been reported. Each SMM acts as a bias on its neighbor, shifting the quantum tunneling resonances of the individual SMMs. Hysteresis loop measurements on a single crystal of SMM dimers have now established quantum tunneling of the magnetization via entangled states of the dimer. This shows that the dimer really does behave as a quantum mechanically coupled dimer, and also allows the measurement of the longitudinal and transverse superexchange coupling constants.

  11. Theoretical comparison of light scattering and guided wave coupling in multilayer coated optical components with random interface roughness

    International Nuclear Information System (INIS)

    Elson, J.M.

    1995-01-01

    In this work, we use first-order perturbation theory to calculate and then compare the (1) angular distribution of incident light scattered from a multilayer-coated optical component and (2) the angular distribution of incident light coupled into guided waves supported by the multilayer component. The incident beam is assumed to be a monochromatic plane wave and the scattering/coupling is assumed to be caused by roughness at the interfaces of the optical component. Numerical results show that for high quality (low root mean square roughness) optical components, comparison of the relative amounts of incident energy (1) scattered out of the specular beam and (2) coupled into guided waves are comparable. It follows that the guided wave energy will further contribute to the scattered field via radiative decay or be converted to heat. Thus, this work can help provide an estimation of when guided wave coupling can occur along with the expected magnitude. (orig.)

  12. Microwave-assisted shingled magnetic recording simulations on an exchange-coupled composite medium

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, T., E-mail: t-tanaka@ed.kyushu-u.ac.jp [Department of Electronics, Graduate School of Information Science and Electrical Engineering, Kyushu University, Motoota 744, Nishi-ku, Fukuoka 819-0395 (Japan); Kashiwagi, S. [Department of Electronics, Graduate School of Information Science and Electrical Engineering, Kyushu University, Motoota 744, Nishi-ku, Fukuoka 819-0395 (Japan); Kanai, Y. [Department of Information and Electronics Engineering, Niigata Institute of Technology, Fujihashi 1719, Kashiwazaki, Niigata 945-1195 (Japan); Matsuyama, K. [Department of Electronics, Graduate School of Information Science and Electrical Engineering, Kyushu University, Motoota 744, Nishi-ku, Fukuoka 819-0395 (Japan)

    2016-10-15

    The potential of microwave-assisted magnetic recording combined with the shingled recording scheme has been studied by simulating read/write processes on exchange-coupled composite media focusing on recording characteristics in the cross-track direction. Microwave fields enhance writability, especially at the track edge, resulting in lower noise and higher signal-to-noise ratio (SNR), which enables higher track density in the shingled recording scheme. Read/write simulations of microwave-assisted shingled recording achieve 1.4 Mtracks/in. while retaining high SNR. Further increases in SNR and track density will require either a narrower reader or track edge noise reduction. - Highlights: • Signal recording of shingled magnetic recording using an asymmetric single pole type head combined with a microwave assistance was numerically demonstrated. • Writability is improved by microwave fields with a moderate frequency at the track edge of the shielded side, resulting in higher signal-to-noise ratio. • 1.41 Mtpi of track density is feasible for the recording scheme of shingled magnetic recording with microwave assistance.

  13. Characterisation of brewpub beer carbohydrates using high performance anion exchange chromatography coupled with pulsed amperometric detection.

    Science.gov (United States)

    Arfelli, Giuseppe; Sartini, Elisa

    2014-01-01

    High performance anion exchange chromatography (HPAEC) coupled with pulsed amperometric detection (PAD) was optimised in order to quantify mannose, maltose, maltotriose, maltotetraose, maltopentaose, maltohexaose and maltoheptaose content of beer. The method allows the determination of above mentioned oligosaccharides, in a single chromatographic run, without any pre-treatment. Limit of detection and limit of quantification were suitable for beer. Accuracy and repeatability were good for the entire amount considered. Once optimised HPAEC PAD for the specific matrix, the second goal of this research was to verify the possibility to discriminate beers, depending on their style. The carbohydrates content of brewpub commercial beers was very variable, ranging from 19.3 to 1469mg/L (mannose), 34.5 to 2882mg/L (maltose), 141.9 to 20731mg/L (maltotriose), 168.5 to 7650mg/L (maltotetraose), 20.1 to 2537mg/L (maltopentaose), 22.9 to 3295mg/L (maltohexaose), 8.5 to 2492mg/L (maltoeptaose), even in the same style of beer. However, the carbohydrates content was useful, jointed with other compounds amount, to discriminate different styles of beer. As a matter of fact, principal component analysis put in evidence beer differences considering some fermentation conditions and colour. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Thermal modeling of a greenhouse integrated to an aquifer coupled cavity flow heat exchanger system

    Energy Technology Data Exchange (ETDEWEB)

    Sethi, V.P. [Department of Mechanical Engineering, Punjab Agricultural University, Ludhiana 141 008, Punjab (India); Sharma, S.K. [Energy Research Centre, Panjab University, Chandigarh 160 017, Punjab (India)

    2007-06-15

    A thermal model is developed for heating and cooling of an agricultural greenhouse integrated with an aquifer coupled cavity flow heat exchanger system (ACCFHES). The ACCFHES works on the principal of utilizing deep aquifer water available at the ground surface through an irrigation tube well already installed in every agricultural field at constant year-round temperature of 24 C. The analysis is based on the energy balance equations for different components of the greenhouse. Using the derived analytical expressions, a computer program is developed in C{sup ++} for computing the hourly greenhouse plant and room air temperature for various design and climatic parameters. Experimental validation of the developed model is carried out using the measured plant and room air temperature data of the greenhouse (in which capsicum is grown) for the winter and summer conditions of the year 2004-2005 at Chandigarh (31 N and 78 E), Punjab, India. It is observed that the predicted and measured values are in close agreement. Greenhouse room air and plant temperature is maintained 6-7 K and 5-6 K below ambient, respectively for an extreme summer day and 7-8 K and 5-6 K above ambient, respectively for an extreme winter night. Finally, parametric studies are conducted to observe the effect of various operating parameters such as mass of the plant, area of the plant, mass flow rate of the circulating air and area of the ACCFHES on the greenhouse room air and plant temperature. (author)

  15. Exchange coupled pairs of dangling bond spins as a new type of paramagnetic defects in nanodiamonds

    Energy Technology Data Exchange (ETDEWEB)

    Osipov, V. Yu., E-mail: osipov@mail.ioffe.r [Ioffe Physico-Technical Institute, Polytechnicheskaya 26, 194021 St. Petersburg (Russian Federation); Faculty of Electronics, St. Petersburg State Electrotechnical University (LETI), 197376 (Russian Federation); Shames, A.I. [Department of Physics, Ben-Gurion University of the Negev, 84105 Be' er-Sheva (Israel); Vul' , A. Ya. [Ioffe Physico-Technical Institute, Polytechnicheskaya 26, 194021 St. Petersburg (Russian Federation)

    2009-12-15

    EPR in detonation nanodiamonds (DND) reveals two different signals associated with intrinsic carbon inherited paramagnetic defects. Main carbon inherited EPR signal is narrow intensive Lorentzian-like singlet with g=2.0028 and spin concentration N{sub s}=(6-7)x10{sup 19} spin/g that yields on average 13-15 spins per each DND particle. Additional chemical treatment of DND powder allows practically complete removal of trace amounts of transition metal impurities that reveals a new doublet EPR signal consisting of two relatively narrow lines within the half-field region (gapprox4) separated by a distance of 10.4 mT. The intensity of the doublet signal is five orders of magnitude lower than that of the main singlet signal. The former signal has been observed in a wide variety of DND samples disregarding of the impurity level reached and thus may be attributed to some intrinsic defects in DND particles. Such half-field EPR signals correspond to 'forbidden' DELTAM{sub s}=2 transitions within thermally populated triplet (S=1) levels observed in polycrystalline samples containing exchange dimers-antiferromagnetically coupled spin pairs. Estimates suggest that the concentration of such defects is about one dimer per hundreds DND particles.

  16. Microwave-assisted shingled magnetic recording simulations on an exchange-coupled composite medium

    International Nuclear Information System (INIS)

    Tanaka, T.; Kashiwagi, S.; Kanai, Y.; Matsuyama, K.

    2016-01-01

    The potential of microwave-assisted magnetic recording combined with the shingled recording scheme has been studied by simulating read/write processes on exchange-coupled composite media focusing on recording characteristics in the cross-track direction. Microwave fields enhance writability, especially at the track edge, resulting in lower noise and higher signal-to-noise ratio (SNR), which enables higher track density in the shingled recording scheme. Read/write simulations of microwave-assisted shingled recording achieve 1.4 Mtracks/in. while retaining high SNR. Further increases in SNR and track density will require either a narrower reader or track edge noise reduction. - Highlights: • Signal recording of shingled magnetic recording using an asymmetric single pole type head combined with a microwave assistance was numerically demonstrated. • Writability is improved by microwave fields with a moderate frequency at the track edge of the shielded side, resulting in higher signal-to-noise ratio. • 1.41 Mtpi of track density is feasible for the recording scheme of shingled magnetic recording with microwave assistance.

  17. Event Handler II: a fast, programmable, CAMAC-coupled data acquisition interface

    International Nuclear Information System (INIS)

    Hensley, D.C.

    1979-01-01

    The architecture of the Event Handler II, a fast, programmable data acquisition interface linked to and through CAMAC is described. The special features of this interface make it a powerful tool in implementing data acquisition systems for experiments in nuclear physics. 1 figure, 1 table

  18. Event Handler: a fast programmable, CAMAC-coupled data acquisition interface

    International Nuclear Information System (INIS)

    Hensley, D.C.

    1978-01-01

    The purpose of this paper is to describe the architecture and performance of the Event Handler, a fast, programmable data acquisition interface which is linked to and through CAMAC. The special features of this interface make it a powerful tool in implementing data acquisition systems for experiments in nuclear physics

  19. Interfaces exchange bias and magnetic properties of ordered CoFe_2O_4/Co_3O_4 nanocomposites

    International Nuclear Information System (INIS)

    Zhang, B.B.; Xu, J.C.; Wang, P.F.; Han, Y.B.; Hong, B.; Jin, H.X.; Jin, D.F.; Peng, X.L.; Li, J.; Yang, Y.T.; Gong, J.; Ge, H.L.; Wang, X.Q.

    2015-01-01

    Graphical abstract: - Highlights: • CoFe_2O_4 nanoparticles were well-dispersed anchored in mesopores of Co_3O_4. • The magnetic behavior of nanocomposites changed greatly at low temperature. • CoFe_2O_4 nanoparticles reinforced the interfaces magnetic interaction of nanocomposites. • M increased with the doping of CoFe_2O_4 and the decreasing temperature. • Exchange bias effect was observed at 100 K and increased with the doping of CoFe_2O_4. - Abstract: Cobalt ferrites (CoFe_2O_4) nanoparticles were implanted into the ordered mesoporous cobaltosic oxide (Co_3O_4) nanowires to synthesize magnetic CoFe_2O_4/Co_3O_4 nanocomposites. X-ray diffraction (XRD), N_2 physical absorption–desorption, transmission electron microscope (TEM) and energy disperse spectroscopy (EDS) were used to characterize the microstructure of mesoporous Co_3O_4 and CoFe_2O_4/Co_3O_4 nanocomposites. The percent of pore-volume of mesoporous Co_3O_4 nanowires was calculated to be about 41.99% and CoFe_2O_4 nanoparticles were revealed to exist in the mesopores of Co_3O_4_. The magnetic behavior of both samples were investigated with superconducting quantum interference device (SQUID). Magnetization increased with the doping CoFe_2O_4 and decreasing temperature, while coercivity hardly changed. The exchange bias effect was obviously observed at 100 K and enhanced with the doping CoFe_2O_4. CoFe_2O_4 nanoparticles reinforced the interfaces magnetic interaction between antiferromagnetic Co_3O_4 and ferrimagnetic CoFe_2O_4.

  20. Clarifying roughness and atomic diffusion contributions to the interface broadening in exchange-biased NiFe/FeMn/NiFe heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, V.P., E-mail: valberpn@yahoo.com.br [Departamento de Física, Universidade Federal do Espírito Santo, 29075-910 Vitória (Brazil); Merino, I.L.C.; Passamani, E.C. [Departamento de Física, Universidade Federal do Espírito Santo, 29075-910 Vitória (Brazil); Alayo, W. [Departamento de Física, Universidade de Pelotas, 96010-610 Pelotas (Brazil); Tafur, M. [Instituto de Ciências Exatas, Universidade Federal de Itajubá, 37500-903 Itajubá (Brazil); Pelegrini, F. [Instituto de Física, Universidade Federal de Goiás, 74001-970 Goiânia (Brazil); Magalhães-Paniago, R. [Universidade Federal de Minas Gerais, Belo Horizonte (Brazil); Alvarenga, A.D. [Instituto Nacional de Metrologia, 25250-020 Xerém (Brazil); Saitovitch, E.B. [Coordenação de Física Experimental e Baixas Energias, Centro Brasileiro de Pesquisas Físicas, 22290-180 Rio de Janeiro (Brazil)

    2013-09-02

    NiFe(30 nm)/FeMn(13 nm)/NiFe(10 nm) heterostructures prepared by magnetron sputtering at different argon working pressures (0.27, 0.67 and 1.33 Pa) were systematically investigated by using specular and off-specular diffuse X-ray scattering experiments, combined with ferromagnetic resonance technique, in order to distinguish the contribution from roughness and atomic diffusion to the total structural disorder at NiFe/FeMn interfaces. It was shown that an increase in the working gas pressure from 0.27 to 1.33 Pa causes an enhancement of the atomic diffusion at the NiFe/FeMn interfaces, an effect more pronounced at the top FeMn/NiFe interface. In particular, this atomic diffusion provokes a formation of non-uniform magnetic dead-layers at the NiFe/FeMn interfaces (NiFeMn regions with paramagnetic or weak antiferromagnetic properties); that are responsible for the substantial reduction of the exchange bias field in the NiFe/FeMn system. Thus, this work generically helps to understand the discrepancies found in the literature regarding the influence of the interface broadening on the exchange bias properties (e.g., exchange bias field) of the NiFe/FeMn system. - Highlights: • Roughness and atomic diffusion contributions to the interface broadening • Clarification of the exchange bias field dependence on the interface disorder • Ferromagnetic, paramagnetic and antiferromagnetic phases at the magnetic interface • Magnetic dead layers formed by increasing the argon work pressure • Atomic diffusion in heterostructures prepared at higher argon pressure.

  1. First-order-reversal-curve analysis of exchange-coupled SmCo/NdFeB nanocomposite alloys

    International Nuclear Information System (INIS)

    Pan, Mingxiang; Zhang, Pengyue; Ge, Hongliang; Yu, Nengjun; Wu, Qiong

    2014-01-01

    Exchange-coupled SmCo 5 /Nd 2 Fe 14 B nanocomposite magnets have been fabricated by ball milling of the micrometer sized SmCo 5 and Nd 2 Fe 14 B powders. The influence of Nd 2 Fe 14 B content on the microstructure and magnetic properties of these hybrid alloys was investigated. The alloys that show strong intergrain exchange-coupling behavior with (BH) max =2.95 MGOe was obtained when the two hard phases are well coupled. A first-order-reversal-curve (FORC) analysis was performed for both SmCo 5 single-phase magnet and SmCo 5 /Nd 2 Fe 14 B hybrid magnet; the FORC diagrams results show two major peaks for the hybrid magnets. In both cases, the magnetization reversal behaviors for these alloys were discussed in detail and are consistent with the results of δM plots. - Highlights: • Exchange-coupled SmCo 5 /Nd 2 Fe 14 B nanocomposite magnets were studied. • Magnetization reversal behaviors of the hybrid magnet were discussed. • The FORCs analysis is taken to identify the optimal conditions for hybrid magnet

  2. Explicitly-correlated ring-coupled-cluster-doubles theory: Including exchange for computations on closed-shell systems

    Energy Technology Data Exchange (ETDEWEB)

    Hehn, Anna-Sophia; Holzer, Christof; Klopper, Wim, E-mail: klopper@kit.edu

    2016-11-10

    Highlights: • Ring-coupled-cluster-doubles approach now implemented with exchange terms. • Ring-coupled-cluster-doubles approach now implemented with F12 functions. • Szabo–Ostlund scheme (SO2) implemented for use in SAPT. • Fast convergence to the limit of a complete basis. • Implementation in the TURBOMOLE program system. - Abstract: Random-phase-approximation (RPA) methods have proven to be powerful tools in electronic-structure theory, being non-empirical, computationally efficient and broadly applicable to a variety of molecular systems including small-gap systems, transition-metal compounds and dispersion-dominated complexes. Applications are however hindered due to the slow basis-set convergence of the electron-correlation energy with the one-electron basis. As a remedy, we present approximate explicitly-correlated RPA approaches based on the ring-coupled-cluster-doubles formulation including exchange contributions. Test calculations demonstrate that the basis-set convergence of correlation energies is drastically accelerated through the explicitly-correlated approach, reaching 99% of the basis-set limit with triple-zeta basis sets. When implemented in close analogy to early work by Szabo and Ostlund [36], the new explicitly-correlated ring-coupled-cluster-doubles approach including exchange has the perspective to become a valuable tool in the framework of symmetry-adapted perturbation theory (SAPT) for the computation of dispersion energies of molecular complexes of weakly interacting closed-shell systems.

  3. First-order-reversal-curve analysis of exchange-coupled SmCo/NdFeB nanocomposite alloys

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Mingxiang; Zhang, Pengyue, E-mail: Zhang_pengyue@cjlu.edu.cn; Ge, Hongliang; Yu, Nengjun; Wu, Qiong

    2014-06-01

    Exchange-coupled SmCo{sub 5}/Nd{sub 2}Fe{sub 14}B nanocomposite magnets have been fabricated by ball milling of the micrometer sized SmCo{sub 5} and Nd{sub 2}Fe{sub 14}B powders. The influence of Nd{sub 2}Fe{sub 14}B content on the microstructure and magnetic properties of these hybrid alloys was investigated. The alloys that show strong intergrain exchange-coupling behavior with (BH){sub max}=2.95 MGOe was obtained when the two hard phases are well coupled. A first-order-reversal-curve (FORC) analysis was performed for both SmCo{sub 5} single-phase magnet and SmCo{sub 5}/Nd{sub 2}Fe{sub 14}B hybrid magnet; the FORC diagrams results show two major peaks for the hybrid magnets. In both cases, the magnetization reversal behaviors for these alloys were discussed in detail and are consistent with the results of δM plots. - Highlights: • Exchange-coupled SmCo{sub 5}/Nd{sub 2}Fe{sub 14}B nanocomposite magnets were studied. • Magnetization reversal behaviors of the hybrid magnet were discussed. • The FORCs analysis is taken to identify the optimal conditions for hybrid magnet.

  4. A density functional theory study of the magnetic exchange coupling in dinuclear manganese(II) inverse crown structures.

    Science.gov (United States)

    Vélez, Ederley; Alberola, Antonio; Polo, Víctor

    2009-12-17

    The magnetic exchange coupling constants between two Mn(II) centers for a set of five inverse crown structures have been investigated by means of a methodology based on broken-symmetry unrestricted density functional theory. These novel and highly unstable compounds present superexchange interactions between two Mn centers, each one with S = 5/2 through anionic "guests" such as oxygen, benzene, or hydrides or through the cationic ring formed by amide ligands and alkali metals (Na, Li). Magnetic exchange couplings calculated at B3LYP/6-31G(d,p) level yield strong antiferromagnetic couplings for compounds linked via an oxygen atom or hydride and very small antiferromagnetic couplings for those linked via a benzene molecule, deprotonated in either 1,4- or 1,3- positions. Analysis of the magnetic orbitals and spin polarization maps provide an understanding of the exchange mechanism between the Mn centers. The dependence of J with respect to 10 different density functional theory potentials employed and the basis set has been analyzed.

  5. Magnetization reversal and domain correlation for a non-collinear and out-of-plane exchange-coupled system

    International Nuclear Information System (INIS)

    Paul, Amitesh; Paul, N; Mattauch, Stefan

    2011-01-01

    We have investigated the impact of out-of-plane ferromagnetic (FM) anisotropy (which can be coincident with the direction of unidirectional anisotropy), where antiferromagnetic (AF) anisotropy is along the film plane. This provides a platform for non-collinear exchange coupling in an archetypal exchange coupled system in an unconventional way. We probe the in-plane magnetization by the depth-sensitive vector magnetometry technique. The experimental findings reveal a magnetization reversal (i) that is symmetric for both the branches of the hysteresis loop, (ii) that is characterized by vertically correlated domains associated with a strong transverse component of magnetization and (iii) that remains untrained (suppression of trained state) with field cycling. This scenario has been compared with in-plane magnetization reversal for a conventional in-plane unidirectional anisotropic case in the same system that shows usual asymmetric reversal and training for vertically uncorrelated domains. We explain the above observations for the out-of-plane case in terms of inhomogeneous magnetic states due to competing perpendicular anisotropies that result in non-collinear FM-AF coupling. This study provides direct evidence for the vertical correlation of domains mediated by out-of-plane exchange coupling.

  6. Interfacial Exchange Coupling Induced Anomalous Anisotropic Magnetoresistance in Epitaxial γ′-Fe 4 N/CoN Bilayers

    KAUST Repository

    Li, Zirun; Mi, Wenbo; Wang, Xiaocha; Zhang, Xixiang

    2015-01-01

    Anisotropic magnetoresistance (AMR) of the facing-target reactively sputtered epitaxial γ′-Fe4N/CoN bilayers is investigated. The phase shift and rectangular-like AMR appears at low temperatures, which can be ascribed to the interfacial exchange coupling. The phase shift comes from the exchange bias (EB) that makes the magnetization lag behind a small field. When the γ′-Fe4N thickness increases, the rectangular-like AMR appears. The rectangular-like AMR should be from the combined contributions including the EB-induced unidirectional anisotropy, intrinsic AMR of γ′-Fe4N layer and interfacial spin scattering.

  7. Interfacial Exchange Coupling Induced Anomalous Anisotropic Magnetoresistance in Epitaxial γ′-Fe 4 N/CoN Bilayers

    KAUST Repository

    Li, Zirun

    2015-02-02

    Anisotropic magnetoresistance (AMR) of the facing-target reactively sputtered epitaxial γ′-Fe4N/CoN bilayers is investigated. The phase shift and rectangular-like AMR appears at low temperatures, which can be ascribed to the interfacial exchange coupling. The phase shift comes from the exchange bias (EB) that makes the magnetization lag behind a small field. When the γ′-Fe4N thickness increases, the rectangular-like AMR appears. The rectangular-like AMR should be from the combined contributions including the EB-induced unidirectional anisotropy, intrinsic AMR of γ′-Fe4N layer and interfacial spin scattering.

  8. Exchange coupling and magnetic anisotropy of exchanged-biased quantum tunnelling single-molecule magnet Ni3Mn2 complexes using theoretical methods based on Density Functional Theory.

    Science.gov (United States)

    Gómez-Coca, Silvia; Ruiz, Eliseo

    2012-03-07

    The magnetic properties of a new family of single-molecule magnet Ni(3)Mn(2) complexes were studied using theoretical methods based on Density Functional Theory (DFT). The first part of this study is devoted to analysing the exchange coupling constants, focusing on the intramolecular as well as the intermolecular interactions. The calculated intramolecular J values were in excellent agreement with the experimental data, which show that all the couplings are ferromagnetic, leading to an S = 7 ground state. The intermolecular interactions were investigated because the two complexes studied do not show tunnelling at zero magnetic field. Usually, this exchange-biased quantum tunnelling is attributed to the presence of intermolecular interactions calculated with the help of theoretical methods. The results indicate the presence of weak intermolecular antiferromagnetic couplings that cannot explain the ferromagnetic value found experimentally for one of the systems. In the second part, the goal is to analyse magnetic anisotropy through the calculation of the zero-field splitting parameters (D and E), using DFT methods including the spin-orbit effect.

  9. Exchange of polycyclic aromatic hydrocarbons across the air-water interface in the Bohai and Yellow Seas

    Science.gov (United States)

    Chen, Yingjun; Lin, Tian; Tang, Jianhui; Xie, Zhiyong; Tian, Chongguo; Li, Jun; Zhang, Gan

    2016-09-01

    In this study, air and surface seawater samples collected from the Bohai (BS) and Yellow Seas (YS) in May 2012 were determined exchange of PAHs, especially of low-molecular-weight (LMW) PAHs (three- and four-ring PAHs) at the air-water interface. Net volatilization fluxes of LMW PAHs were 266-1454 ng/m2/d and decreased with distance from the coast, indicating that these PAHs transported from coastal runoff were potential contributors to the atmosphere in the BS and YS. Moreover, LMW PAHs were enriched in the dissolved phase compared with those in the particulate phase in the water column, possibly suggesting that the volatilized LMW PAHs were directly derived from wastewater discharge or petroleum pollution rather than released from contaminated sediments. The air-sea exchange fluxes of the three-ring PAHs were 2- to 20-fold higher than their atmospheric deposition fluxes in the BS and YS. The input to and output from the water reached equilibrium for four-ring PAHs. Differently, five- and six-ring PAHs were introduced into the marine environment primarily through dry and wet deposition, indicating that the water column was still a sink of these PAHs from the surrounding atmosphere.

  10. Exfoliated MoS2 nanosheets loaded on bipolar exchange membranes interfaces as advanced catalysts for water dissociation

    DEFF Research Database (Denmark)

    Li, Jian; Morthensen, Sofie Thage; Zhu, Junyong

    2018-01-01

    . Bipolar membranes are key factors for splitting water at the interface of a cation and anion exchange layer in an electric field. The ideal bipolar membrane should have a low energy consumption, a high current efficiency and long-term stability. In order to investigate the catalytic effect of a monolayer...... this prediction. Furthermore, a bipolar membrane prepared at 90°C had a low swelling ratio of about 7.5% while maintaining a high water uptake of 71.6%. From the calculation of current efficiency and energy consumption, the bipolar membrane with a monolayer of MoS2 has a higher current efficiency (45......%) and a lower energy consumption (3.6 kW/h·kg) compared to a current efficiency of 24% and an energy consumption of 6.3 kW/h·kg for a bipolar membrane without MoS2. This study proves the catalytic function of MoS2, which lays a foundation for further research on catalytic bipolar exchange membranes....

  11. Magnons and interface magnetic substructures

    International Nuclear Information System (INIS)

    Djafari-Rouhani, B.; Dobrzynski, L.

    1975-01-01

    The localized magnons at an interface between two Heisenberg ferromagnets and the ferromagnetic stability at the interface are studied. The authors consider simple cubic crystals having the same lattice parameter and the same spin value in the fundamental state on each site, but different exchange integrals between first and second nearest neighbours. An interface by coupling two semi-infinite crystals having the same crystallographic surface is defined. The conditions for the existence of localized magnons at (001) interfaces as well as the dispersion curves of localized and resonant magnons in the high symmetry directions of the Brillouin zone are studied. The effect of the interface interactions on these modes is determined. It is shown that magnetic superstructures may exist at (110) interfaces. Such an instability is given by the existence of a soft localized mode at the interface [fr

  12. The thermal stability of magnetically exchange coupled MnBi/FeCo composites at electric motor working temperature

    Science.gov (United States)

    Cheng, Ye; Wang, Hongying; Li, Zhigang; Liu, Wanhui; Bao, Ilian

    2018-04-01

    The magnetically exchange coupled MnBi/FeCo composites were synthesized through a magnetic self-assembly process. The MnBi/FeCo composites were then hot pressed in a magnetic field to form magnets. The thermal stability of the magnets were tested by annealing at electric motor working temperature of 200 °C for 20, 40 and 60 h, respectively. It was found that after heating for 20 h, there was negligible change in its hysteresis loop. However, when the heating time was increased 40 and 60 h, the magnetic hysteresis loops presented two-phase magnetic behaviors, and the maximum energy products of the magnet were decreased. This research showed that the magnetically exchange coupled MnBi/FeCo composites had low thermal stability at electric motor working temperature.

  13. Exchange-coupled hard magnetic Fe-Co/CoPt nanocomposite films fabricated by electro-infiltration

    Directory of Open Access Journals (Sweden)

    Xiao Wen

    2017-05-01

    Full Text Available This paper introduces a potentially scalable electro-infiltration process to produce exchange-coupled hard magnetic nanocomposite thin films. Fe-Co/CoPt nanocomposite films are fabricated by deposition of CoFe2O4 nanoparticles onto Si substrate, followed by electroplating of CoPt. Samples are subsequently annealed under H2 to reduce the CoFe2O4 to magnetically soft Fe-Co and also induce L10 ordering in the CoPt. Resultant films exhibit 0.97 T saturation magnetization, 0.70 T remanent magnetization, 127 kA/m coercivity and 21.8 kJ/m3 maximum energy density. First order reversal curve (FORC analysis and δM plot are used to prove the exchange coupling between soft and hard magnetic phases.

  14. Magnetism, spin-lattice-orbital coupling and exchange-correlation energy in oxide heterostructures: Nickelate, titanate, and ruthenate

    Science.gov (United States)

    Han, Myung-Joon

    Many interesting physical phenomena and material characteristics in transition-metal oxides (TMO) come out of the intriguing interplay between charge, spin, orbital, and lattice degrees of freedom. In the thin film and/or heterointerface form of TMO, this feature can be controlled and thus be utilized. Simultaneously, however, its detailed characteristic is more difficult to be identified experimentally. For this reason, the first-principles-based approach has been playing an important role in this field of research. In this talk, I will try to give an overview of current status of first-principles methodologies especially for the magnetism in the correlated oxide heterostructures or thin films. Nickelate, titanate, and ruthenate will be taken as representative examples to demonstrate the powerfulness of and the challenges to the current methodologies On the one hand, first-principles calculation provides the useful information, understanding and prediction which can hardly be obtained from other theoretical and experimental techniques. Nickelate-manganite superlattices (LaNiO3/LaMnO3 and LaNiO3/CaMnO3) are taken as examples. In this interface, the charge transfer can induce the ferromagnetism and it can be controlled by changing the stacking sequence and number of layers. The exchange-correlation (XC) functional dependence seems to give only quantitatively different answers in this case. On the other hand, for the other issues such as orbital polarization/order coupled with spin order, the limitation of current methodology can be critical. This point will be discussed with the case of tatinate superlattice (LaTiO3/LaAlO3) . For ruthenates (SrRuO3\\ and Sr2RuO4) , we found that the probably more fundamental issue could be involved. The unusually strong dependence on the XC functional parametrization is found to give a qualitatively different conclusion for the experimentally relevant parameter regions. This work was supported by National Research Foundation of

  15. Gas and aerosol radionuclide transfers in complex environments: experimental studies of atmospheric dispersion and interfaces exchanges

    International Nuclear Information System (INIS)

    Maro, Denis

    2011-01-01

    In situations of chronic or accidental releases, the atmosphere is the main pathway of radioactive releases from nuclear facilities to the environment and, consequently, to humans. It is therefore necessary to have sufficient information on this pathway to accurately assess the radiological impact on man and his environment. Institute for Radioprotection and Nuclear Safety develops its own tools of dispersion and atmospheric transfer for its expertise, under normal operation conditions of a facility, but especially in crisis or post-accident. These tools must have a national and international recognition in particular through scientific validation against benchmark experiments performed internationally, nationally or within the IRSN. The Radioecology Laboratory of Cherbourg-Octeville provides, and will increasingly make, a significant contribution to the scientific influence of the Institute in this field. The work presented in this report has contributed to the development or improvement of experimental techniques in the fields of atmospheric dispersion of radionuclides and transfer at interfaces, in complex environments (complex topography, urban area). These experimental techniques, applied during field campaigns, have allowed to acquire new data in order to get a better understanding of radionuclide transfers in the form of gases and aerosols. (author)

  16. The influence of interlayer exchange coupling in giant-magnetoresistive devices on spin diode effect in wide frequency range

    Energy Technology Data Exchange (ETDEWEB)

    Ziętek, Sławomir, E-mail: zietek@agh.edu.pl; Skowroński, Witold; Wiśniowski, Piotr; Czapkiewicz, Maciej; Stobiecki, Tomasz [Department of Electronics, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków (Poland); Ogrodnik, Piotr [Department of Electronics, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków (Poland); Faculty of Physics, Warsaw University of Technology, ul. Koszykowa 75, 00-662 Warszawa (Poland); Institute of Molecular Physics, Polish Academy of Sciences, ul. Smoluchowskiego 17, 60-179 Poznań (Poland); Barnaś, Józef [Institute of Molecular Physics, Polish Academy of Sciences, ul. Smoluchowskiego 17, 60-179 Poznań (Poland); Faculty of Physics, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Poznań (Poland)

    2015-09-21

    Spin diode effect in a giant magnetoresistive strip is measured in a broad frequency range, including resonance and off-resonance frequencies. The off-resonance dc signal is relatively strong and also significantly dependent on the exchange coupling between magnetic films through the spacer layer. The measured dc signal is described theoretically by taking into account magnetic dynamics induced by Oersted field created by an ac current flowing through the system.

  17. Interfacing capillary electrophoresis with inductively coupled plasma mass spectrometry by direct injection nebulization for selenium speciation

    DEFF Research Database (Denmark)

    Bendahl, Lars; Gammelgaard, Bente; Jons, O.

    2001-01-01

    A demountable direct injection high efficiency nebulizer operating at low sample uptake rates was developed and used for coupling of capillary electrophoresis (CE) with inductively coupled plasma mass spectrometry (ICP-MS). When the nebulizer was used for continuous sample introduction, detection...

  18. Inductively and capacitively coupled plasmas at interface: A comparative study towards highly efficient amorphous-crystalline Si solar cells

    Science.gov (United States)

    Guo, Yingnan; Ong, Thiam Min Brian; Levchenko, I.; Xu, Shuyan

    2018-01-01

    A comparative study on the application of two quite different plasma-based techniques to the preparation of amorphous/crystalline silicon (a-Si:H/c-Si) interfaces for solar cells is presented. The interfaces were fabricated and processed by hydrogen plasma treatment using the conventional plasma-enhanced chemical vacuum deposition (PECVD) and inductively coupled plasma chemical vapour deposition (ICP-CVD) methods The influence of processing temperature, radio-frequency power, treatment duration and other parameters on interface properties and degree of surface passivation were studied. It was found that passivation could be improved by post-deposition treatment using both ICP-CVD and PECVD, but PECVD treatment is more efficient for the improvement on passivation quality, whereas the minority carrier lifetime increased from 1.65 × 10-4 to 2.25 × 10-4 and 3.35 × 10-4 s after the hydrogen plasma treatment by ICP-CVD and PECVD, respectively. In addition to the improvement of carrier lifetimes at low temperatures, low RF powers and short processing times, both techniques are efficient in band gap adjustment at sophisticated interfaces.

  19. A dyadic model of the work-family interface: a study of dual-earner couples in China.

    Science.gov (United States)

    Ho, Man Yee; Chen, Xuefei; Cheung, Fanny M; Liu, Huimin; Worthington, Everett L

    2013-01-01

    This study adopted a spillover-crossover model to examine the roles of personality and perceived social support as antecedents of the work-family interface among dual-earner couples in China. Married couples (N = 306) from 2 major cities in China (Shanghai and Jinan) completed questionnaires measuring a relationship-oriented personality trait (i.e., family orientation), perceived family and work support, and work-family conflict and enhancement. The results showed that family orientation and perceived family support was positively associated with family-to-work enhancement and negatively associated with family-to-work conflict for both husbands and wives. Perceived work support was positively associated with family-to-work enhancement for wives and negatively associated with work-to-family conflict for husbands. Similarities in family orientation between partners were positively correlated with the individual's family-to-work enhancement. This study also illustrated the crossover of the work-family interface between dual-earner couples by using the actor-partner interdependence model. The pattern of associations between personality trait and perceived social support varied by gender. Husbands' family orientation was negatively correlated with work-to-family enhancement experienced by wives, and husbands' perceived work support was positively correlated with work-to-family enhancement experienced by wives. Wives' perceived work support was positively correlated with family-to-work conflict experienced by husbands.

  20. Interface COMSOL-PHREEQC (iCP), an efficient numerical framework for the solution of coupled multiphysics and geochemistry

    Science.gov (United States)

    Nardi, Albert; Idiart, Andrés; Trinchero, Paolo; de Vries, Luis Manuel; Molinero, Jorge

    2014-08-01

    This paper presents the development, verification and application of an efficient interface, denoted as iCP, which couples two standalone simulation programs: the general purpose Finite Element framework COMSOL Multiphysics® and the geochemical simulator PHREEQC. The main goal of the interface is to maximize the synergies between the aforementioned codes, providing a numerical platform that can efficiently simulate a wide number of multiphysics problems coupled with geochemistry. iCP is written in Java and uses the IPhreeqc C++ dynamic library and the COMSOL Java-API. Given the large computational requirements of the aforementioned coupled models, special emphasis has been placed on numerical robustness and efficiency. To this end, the geochemical reactions are solved in parallel by balancing the computational load over multiple threads. First, a benchmark exercise is used to test the reliability of iCP regarding flow and reactive transport. Then, a large scale thermo-hydro-chemical (THC) problem is solved to show the code capabilities. The results of the verification exercise are successfully compared with those obtained using PHREEQC and the application case demonstrates the scalability of a large scale model, at least up to 32 threads.

  1. Immediate drop on demand technology (I-DOT) coupled with mass spectrometry via an open port sampling interface.

    Science.gov (United States)

    Van Berkel, Gary J; Kertesz, Vilmos; Boeltz, Harry

    2017-11-01

    The aim of this work was to demonstrate and evaluate the analytical performance of coupling the immediate drop on demand technology to a mass spectrometer via the recently introduced open port sampling interface and ESI. Methodology & results: A maximum sample analysis throughput of 5 s per sample was demonstrated. Signal reproducibility was 10% or better as demonstrated by the quantitative analysis of propranolol and its stable isotope-labeled internal standard propranolol-d7. The ability of the system to multiply charge and analyze macromolecules was demonstrated using the protein cytochrome c. This immediate drop on demand technology/open port sampling interface/ESI-MS combination allowed for the quantitative analysis of relatively small mass analytes and was used for the identification of macromolecules like proteins.

  2. Analysis of a double-pipe heat exchanger performance using heat structure coupling of MARS and CUPID

    International Nuclear Information System (INIS)

    Amidua, M.; Kim, H.; Cho, H. K.

    2015-01-01

    Thermal hydraulic phenomena in the inner tube of the double-pipe heat exchanger are expected to be reproducible by one-dimensional system analysis codes (MARS) if a proper condensation heat transfer coefficient is applied. Jeon et al (2013) and Cho et al (2013) conducted comprehensive reviews of the predictive capability of the condensation heat transfer models for the steam-water stratified flow. On the contrary, in the outer tube, a multidimensional analysis tool is required to incorporate the influence of azimuthal angle on the heat transfer rate from the inner tube outer wall to the outer tube fluid. Therefore, a coupled calculation between one dimensional system analysis code and a multidimensional computational fluid dynamics code is an attainable way to predict this effect with a reliable accuracy. CUPID is a three-dimensional computational multiphase fluid dynamics code developed by KAERI (Korea Atomic Energy Research Institute). According to Jeong et al (2010), the objective of the development is to support a resolution for the thermal hydraulic issues regarding the transient multi-dimensional twophase phenomena which can arise in an advanced light water reactor. It uses two-fluid model for the governing equations, which uses two sets of Navier-Stokes' equations for two phases. It can be used as either a typical CFD code or a component code (porous CFD code) depending on the length scale of the phenomena that need to be resolved. On the other hand, MARS is a best estimate thermalhydraulic system code and it was developed at KAERI by consolidating and restructuring the RELAP5/MOD3.2 code and COBRA-TF code (Cho et al., 2014). The MARS code has the capability to analyze best-estimated thermal hydraulic system. In this study, the coupled CUPID-MARS code was used for the simulation of a double-pipe heat exchanger. This paper presents the description of the heat exchanger, the coupling method, and the simulation results using the coupled code. The coupling

  3. Exchange bias coupling in NiO/Ni bilayer tubular nanostructures synthetized by electrodeposition and thermal oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Yu, T., E-mail: work_tian@scu.edu.cn [College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Zhang, Z.W.; Xu, Y.H. [College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Liu, Y. [Analytical & Testing Center, Sichuan University, Chengdu 610064 (China); Li, W.J. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190 (China); Nie, Y.; Zhang, X. [College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Xiang, G., E-mail: gxiang@scu.edu.cn [College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China)

    2017-05-01

    In this paper, we reported the synthesis of NiO/Ni bilayer nanotubes by electrodeposition and thermal oxidation using anodic aluminum oxide templates. The morphology, structure, chemical composition and magnetic properties, especially magnetic exchange bias induced by subsequent magnetic field cooling, in this one-dimensional antiferromagnetic/ferromagnetic hybrid system were investigated. It was found that the effect of the annealing temperature, which mainly dominated the thickness of the NiO layer, and the annealing time, which mainly dominated the grain size of the NiO, on the exchange bias field showed competitive relationship. The optimized exchange bias field was achieved by the combination of the shorter annealing time and higher annealing temperature. - Highlights: • NiO-Ni bilayer tubular nanotubes were fabricated by electrodeposition and thermal oxidation. • The exchange bias effect in NiO-Ni nanotubes was induced by magnetic field cooling. • The competitive effect of annealing temperature and annealing time on the exchange bias coupling was analyzed.

  4. Development of a general coupling interface for the fuel performance code TRANSURANUS – Tested with the reactor dynamics code DYN3D

    International Nuclear Information System (INIS)

    Holt, L.; Rohde, U.; Seidl, M.; Schubert, A.; Van Uffelen, P.; Macián-Juan, R.

    2015-01-01

    Highlights: • A general coupling interface was developed for couplings of the TRANSURANUS code. • With this new tool simplified fuel behavior models in codes can be replaced. • Applicable e.g. for several reactor types and from normal operation up to DBA. • The general coupling interface was applied to the reactor dynamics code DYN3D. • The new coupled code system DYN3D–TRANSURANUS was successfully tested for RIA. - Abstract: A general interface is presented for coupling the TRANSURANUS fuel performance code with thermal hydraulics system, sub-channel thermal hydraulics, computational fluid dynamics (CFD) or reactor dynamics codes. As first application the reactor dynamics code DYN3D was coupled at assembly level in order to describe the fuel behavior in more detail. In the coupling, DYN3D provides process time, time-dependent rod power and thermal hydraulics conditions to TRANSURANUS, which in case of the two-way coupling approach transfers parameters like fuel temperature and cladding temperature back to DYN3D. Results of the coupled code system are presented for the reactivity transient scenario, initiated by control rod ejection. More precisely, the two-way coupling approach systematically calculates higher maximum values for the node fuel enthalpy. These differences can be explained thanks to the greater detail in fuel behavior modeling. The numerical performance for DYN3D–TRANSURANUS was proved to be fast and stable. The coupled code system can therefore improve the assessment of safety criteria, at a reasonable computational cost

  5. Controlled lateral anisotropy in correlated manganite heterostructures by interface-engineered oxygen octahedral coupling

    NARCIS (Netherlands)

    Liao, Zhaoliang; Huijben, Mark; Zhong, Z.; Gauquelin, N.; Macke, S.; Green, R.J.; van Aert, S.; Verbeeck, J.; van Tendeloo, G.; Held, K.; Sawatzky, G.A.; Koster, Gertjan; Rijnders, Augustinus J.H.M.

    2016-01-01

    Controlled in-plane rotation of the magnetic easy axis in manganite heterostructures by tailoring the interface oxygen network could allow the development of correlated oxide-based magnetic tunnelling junctions with non-collinear magnetization, with possible practical applications as miniaturized

  6. Interface requirements to couple thermal hydraulics codes to severe accident codes: ICARE/CATHARE

    Energy Technology Data Exchange (ETDEWEB)

    Camous, F.; Jacq, F.; Chatelard, P. [IPSN/DRS/SEMAR CE-Cadarache, St Paul Lez Durance (France)] [and others

    1997-07-01

    In order to describe with the same code the whole sequence of severe LWR accidents, up to the vessel failure, the Institute of Protection and Nuclear Safety has performed a coupling of the severe accident code ICARE2 to the thermalhydraulics code CATHARE2. The resulting code, ICARE/CATHARE, is designed to be as pertinent as possible in all the phases of the accident. This paper is mainly devoted to the description of the ICARE2-CATHARE2 coupling.

  7. Neuromorphic neural interfaces: from neurophysiological inspiration to biohybrid coupling with nervous systems

    Science.gov (United States)

    Broccard, Frédéric D.; Joshi, Siddharth; Wang, Jun; Cauwenberghs, Gert

    2017-08-01

    Objective. Computation in nervous systems operates with different computational primitives, and on different hardware, than traditional digital computation and is thus subjected to different constraints from its digital counterpart regarding the use of physical resources such as time, space and energy. In an effort to better understand neural computation on a physical medium with similar spatiotemporal and energetic constraints, the field of neuromorphic engineering aims to design and implement electronic systems that emulate in very large-scale integration (VLSI) hardware the organization and functions of neural systems at multiple levels of biological organization, from individual neurons up to large circuits and networks. Mixed analog/digital neuromorphic VLSI systems are compact, consume little power and operate in real time independently of the size and complexity of the model. Approach. This article highlights the current efforts to interface neuromorphic systems with neural systems at multiple levels of biological organization, from the synaptic to the system level, and discusses the prospects for future biohybrid systems with neuromorphic circuits of greater complexity. Main results. Single silicon neurons have been interfaced successfully with invertebrate and vertebrate neural networks. This approach allowed the investigation of neural properties that are inaccessible with traditional techniques while providing a realistic biological context not achievable with traditional numerical modeling methods. At the network level, populations of neurons are envisioned to communicate bidirectionally with neuromorphic processors of hundreds or thousands of silicon neurons. Recent work on brain-machine interfaces suggests that this is feasible with current neuromorphic technology. Significance. Biohybrid interfaces between biological neurons and VLSI neuromorphic systems of varying complexity have started to emerge in the literature. Primarily intended as a

  8. Operation strategy for grid-tied DC-coupling power converter interface integrating wind/solar/battery

    Science.gov (United States)

    Jou, H. L.; Wu, J. C.; Lin, J. H.; Su, W. N.; Wu, T. S.; Lin, Y. T.

    2017-11-01

    The operation strategy for a small-capacity grid-tied DC-coupling power converter interface (GDPCI) integrating wind energy, solar energy and battery energy storage is proposed. The GDPCI is composed of a wind generator, a solar module set a battery bank, a boost DC-DC power converter (DDPC), a bidirectional DDPC power converter, an AC-DC power converter (ADPC) and a five-level DC-AC inverter (DAI). A solar module set, a wind generator and a battery bank are coupled to the common DC bus through the boost DDPC, the ADPC and the bidirectional DDPC, respectively. For verifying the performance of the GDPCI under different operation modes, computer simulation is carried out by PSIM.

  9. Modeling and simulation of control system response to temperature disturbances in a coupled heat exchangers-AHTR system

    International Nuclear Information System (INIS)

    Skavdahl, I.; Utgikar, V.P.; Christensen, R.; Sabharwall, P.; Chen, M.; Sun, X.

    2016-01-01

    Highlights: • Control architecture defined for nuclear reactor-coupled heat exchangers system. • MATLAB code developed for simulation of system response for various temperature disturbances in the system. • Control system effective in maintaining controlled variables at desired set points. • New equilibrium steady state established using controllers. • Adaptive control system capable of switching manipulated variables based on system constraints. - Abstract: An effective control strategy is essential for maintaining optimum operational efficiency of the Advanced High Temperature Reactor (AHTR)-intermediate heat exchanger (IHX)-secondary heat exchanger (SHX) system for power conversion or process heat applications. A control system design is presented in this paper for the control of the coupled intermediate and secondary heat exchangers. The cold side outlet temperature of the SHX (T_c_o) and the hot side outlet temperature of the IHX (T_h_o_2) were identified as the controlled variables that were maintained at their set points by manipulating the flow rates of heat exchange media. Transfer functions describing the relationships between the controlled variables and the manipulated and load variables were developed and the system response to various temperature disturbances was simulated using a custom-developed MATLAB program. It was found that a step disturbance of ±10 °C in the process loop changed the thermal duty by ±650 kW, equal to 6.5% of the initial duty. Similar disturbances in the primary loop had a higher impact on the system. The control system design included a provision for the switching of manipulated variables to limit the adjustment in the magnitudes of the primary manipulated variables. Simulation results indicate that the controlled variables are maintained successfully at their desired points by the control system.

  10. Modeling and simulation of control system response to temperature disturbances in a coupled heat exchangers-AHTR system

    Energy Technology Data Exchange (ETDEWEB)

    Skavdahl, I. [Department of Chemical and Materials Engineering, University of Idaho, Moscow, ID 83844 (United States); Utgikar, V.P., E-mail: vutgikar@uidaho.edu [Department of Chemical and Materials Engineering, University of Idaho, Moscow, ID 83844 (United States); Christensen, R. [Nuclear Engineering Program, University of Idaho, Idaho Falls, ID 83402 (United States); Sabharwall, P. [Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Chen, M.; Sun, X. [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, OH 43210 (United States)

    2016-04-15

    Highlights: • Control architecture defined for nuclear reactor-coupled heat exchangers system. • MATLAB code developed for simulation of system response for various temperature disturbances in the system. • Control system effective in maintaining controlled variables at desired set points. • New equilibrium steady state established using controllers. • Adaptive control system capable of switching manipulated variables based on system constraints. - Abstract: An effective control strategy is essential for maintaining optimum operational efficiency of the Advanced High Temperature Reactor (AHTR)-intermediate heat exchanger (IHX)-secondary heat exchanger (SHX) system for power conversion or process heat applications. A control system design is presented in this paper for the control of the coupled intermediate and secondary heat exchangers. The cold side outlet temperature of the SHX (T{sub co}) and the hot side outlet temperature of the IHX (T{sub ho2}) were identified as the controlled variables that were maintained at their set points by manipulating the flow rates of heat exchange media. Transfer functions describing the relationships between the controlled variables and the manipulated and load variables were developed and the system response to various temperature disturbances was simulated using a custom-developed MATLAB program. It was found that a step disturbance of ±10 °C in the process loop changed the thermal duty by ±650 kW, equal to 6.5% of the initial duty. Similar disturbances in the primary loop had a higher impact on the system. The control system design included a provision for the switching of manipulated variables to limit the adjustment in the magnitudes of the primary manipulated variables. Simulation results indicate that the controlled variables are maintained successfully at their desired points by the control system.

  11. Cytocompatibility and Mechanical Properties of Short Phosphate Glass Fibre Reinforced Polylactic Acid (PLA Composites: Effect of Coupling Agent Mediated Interface

    Directory of Open Access Journals (Sweden)

    Gavin Walker

    2012-10-01

    Full Text Available In this study three chemical agents Amino-propyl-triethoxy-silane (APS, sorbitol ended PLA oligomer (SPLA and Hexamethylene diisocyanate (HDI were identified to be used as coupling agents to react with the phosphate glass fibre (PGF reinforcement and the polylactic acid (PLA polymer matrix of the composite. Composites were prepared with short chopped strand fibres (l = 20 mm, ϕ = 20 µm in a random arrangement within PLA matrix. Improved, initial composite flexural strength (~20 MPa was observed for APS treated fibres, which was suggested to be due to enhanced bonding between the fibres and polymer matrix. Both APS and HDI treated fibres were suggested to be covalently linked with the PLA matrix. The hydrophobicity induced by these coupling agents (HDI, APS helped to resist hydrolysis of the interface and thus retained their mechanical properties for an extended period of time as compared to non-treated control. Approximately 70% of initial strength and 65% of initial modulus was retained by HDI treated fibre composites in contrast to the control, where only ~50% of strength and modulus was retained after 28 days of immersion in PBS at 37 °C. All coupling agent treated and control composites demonstrated good cytocompatibility which was comparable to the tissue culture polystyrene (TCP control, supporting the use of these materials as coupling agent’s within medical implant devices.

  12. Magnetic exchange in {Gd(III)-radical} complexes: method assessment, mechanism of coupling and magneto-structural correlations.

    Science.gov (United States)

    Gupta, Tulika; Rajeshkumar, Thayalan; Rajaraman, Gopalan

    2014-07-28

    Density functional studies have been performed on ten different {Gd(III)-radical} complexes exhibiting both ferro and antiferromagnetic exchange interaction with an aim to assess a suitable exchange-correlation functional within DFT formalism. This study has also been extended to probe the mechanism of magnetic coupling and to develop suitable magneto-structural correlations for this pair. Our method assessments reveal the following order of increasing accuracy for the evaluation of J values compared to experimental coupling constants: B(40HF)LYP X3LYP < B3LYP < B2PLYP. Grimme's double-hybrid functional is found to be superior compared to other functionals tested and this is followed very closely by the conventional hybrid B3LYP functional. At the basis set front, our calculations reveal that the incorporation of relativistic effect is important in these calculations and the relativistically corrected effective core potential (ECP) basis set is found to yield better Js compared to other methods. The supposedly empty 5d/6s/6p orbitals of Gd(III) are found to play an important role in the mechanism of magnetic coupling and different contributions to the exchange terms are probed using Molecular Orbital (MO) and Natural Bond Orbital (NBO) analysis. Magneto-structural correlations for Gd-O distances, Gd-O-N angles and Gd-O-N-C dihedral angles are developed where the bond angles as well as dihedral angle parameters are found to dictate the sign and strength of the magnetic coupling in this series.

  13. Influence of exchange coupling on current-driven domain wall motion in a nanowire

    International Nuclear Information System (INIS)

    Komine, Takashi; Takahashi, Kota; Murakami, Hiroshi; Sugita, Ryuji

    2010-01-01

    In this study, the effect of exchange stiffness constant on current-driven domain wall motion in nanowires with in-plane magnetic anisotropy (IMA) and perpendicular magnetic anisotropy (PMA) has been investigated using micromagnetic simulation. The critical current density in a nanowire with IMA decreases as the exchange stiffness constant decreases because the domain wall width at the upper edge of the nanowire narrows according to the decrease of the exchange stiffness constant. On the other hand, the critical current density in a nanowire with PMA slightly decreases contrary to that of IMA although the domain wall width reasonably decreases as the exchange stiffness constant decreases. The slight reduction rate of the critical current density is due to the increase of the effective hard-axis anisotropy of PMA nanowire.

  14. Light Spins of Cylindrical Electromagnetic Waves and their Jumps across Material Interfaces in the Presence of Energy Exchange

    Directory of Open Access Journals (Sweden)

    J. Mok

    2016-08-01

    Full Text Available We investigate light spins for cylindrical electromagnetic waves on resonance. To this goal, we consider both a dielectric cylinder of infinite length immersed in vacuum and a cylindrical hole punched through a dense dielectric medium. In order for waves of constant frequencies to be established through lossless media, energy absorption is allowed in the surrounding medium to compensate for radiation loss. The dispersion relation is then numerically solved for an asymmetry parameter implying a balance in energy exchange. Numerical studies are performed by varying parameters of refractive index contrast, azimuthal mode index, and size parameter of a cylindrical object. The resulting data is presented mostly in terms of a specific spin, defined as light spin per energy density. This specific spin is found to be bounded in its magnitude, with its maximum associated with either optical vortices or large rotations. Depending on parametric combinations, the specific spin could not only undergo finite jumps across the material interface but also exhibit limit behaviors.

  15. Monte Carlo study of a ferrimagnetic mixed-spin (2, 5/2) system with the nearest and next-nearest neighbors exchange couplings

    Science.gov (United States)

    Bi, Jiang-lin; Wang, Wei; Li, Qi

    2017-07-01

    In this paper, the effects of the next-nearest neighbors exchange couplings on the magnetic and thermal properties of the ferrimagnetic mixed-spin (2, 5/2) Ising model on a 3D honeycomb lattice have been investigated by the use of Monte Carlo simulation. In particular, the influences of exchange couplings (Ja, Jb, Jan) and the single-ion anisotropy(Da) on the phase diagrams, the total magnetization, the sublattice magnetization, the total susceptibility, the internal energy and the specific heat have been discussed in detail. The results clearly show that the system can express the critical and compensation behavior within the next-nearest neighbors exchange coupling. Great deals of the M curves such as N-, Q-, P- and L-types have been discovered, owing to the competition between the exchange coupling and the temperature. Compared with other theoretical and experimental works, our results have an excellent consistency with theirs.

  16. Nanoscale Affinity Chip Interface for Coupling Inhibition SPR Immunosensor Screening with Nano-LC TOF MS

    NARCIS (Netherlands)

    Marchesini, G.R.; Buijs, J.; Haasnoot, W.; Hooijerink, H.; Jansson, O.; Nielen, M.W.F.

    2008-01-01

    The on-line nanoscale coupling of a surface plasmon resonance (SPR)-based inhibition biosensor immunoassay (iBIA) for the screening of low molecular weight molecules with nano-liquid-chromatography electrospray ionization time-of-flight mass spectrometry (nano-LC ESI TOF MS) for identification is

  17. Long-Range Domain Structure and Symmetry Engineering by Interfacial Oxygen Octahedral Coupling at Heterostructure Interface

    NARCIS (Netherlands)

    Liao, Zhaoliang; Green, R.J.; Gauquelin, N.; Macke, S.; Li, Lin; Gonnissen, J.; Sutarto, R.; Houwman, Evert Pieter; Zhong, Z.; van Aert, S.; Verbeeck, J.; Sawatzky, G.A.; Huijben, Mark; Koster, Gertjan; Rijnders, Augustinus J.H.M.

    2016-01-01

    In epitaxial thin film systems, the crystal structure and its symmetry deviate from the bulk counterpart due to various mechanisms such as epitaxial strain and interfacial structural coupling, which is accompanyed by a change in their properties. In perovskite materials, the crystal symmetry can be

  18. The role of frictional strength on plate coupling at the subduction interface

    KAUST Repository

    Tan, Eh; Lavier, Luc L.; Van Avendonk, Harm J. A.; Heuret, Arnauld

    2012-01-01

    and serpentinized mantle (friction angle 1 to 15, or static friction coefficient 0.017 to 0.27) to control the amount of frictional coupling between the plates. With plastic strain weakening in the lithosphere, our numerical models can attain stable subduction

  19. Development of an interface for directly coupled solid-phase extraction and GC-MS analysis

    NARCIS (Netherlands)

    Öllers, M.J.H.; van Lieshout, H.P.M.; Janssen, J.G.M.; Cramers, C.A.M.G.

    Solid-phase extraction (SPE) is widely used as a sample preparation technique in numerous application areas of chromatography. Large-volume injection is an attractive technique for coupling SPE to gas chromatography (GC) because it provides improved detection limits and circumvents the need for

  20. Micromagnetic finite element study for magnetic properties of nanocomposite exchange coupled Nd{sub 2}Fe{sub 14}B/α-Fe multilayer systems

    Energy Technology Data Exchange (ETDEWEB)

    Ryo, Hyok-Su [School of Material Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Faculty of Physics, Kim Il Sung University, Pyongyang 999093, Democratic People’s Republic of Korea (Korea, Republic of); Hu, Lian-Xi [School of Material Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Kim, Jin-Guk [School of Material Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Faculty of Physics, Kim Il Sung University, Pyongyang 999093, Democratic People’s Republic of Korea (Korea, Republic of); Yang, Yu-Lin [School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2017-03-15

    In this study, magnetic properties of exchange coupled nanocomposite multilayer thin films constructed alternately with magnetic hard Nd{sub 2}Fe{sub 14}B layers and soft α-Fe layers have been studied by micromagnetic finite element method (FEM). According to the results, effects of the thicknesses of layers and the magneto-crystalline anisotropy on the magnetic properties of the Nd{sub 2}Fe{sub 14}B/α-Fe multilayer systems have been estimated. On the other hand, the results have been analyzed by means of efficiency of interphase exchange coupling, which can be estimated by volume ratios of exchange coupled areas between magnetically hard Nd{sub 2}Fe{sub 14}B and soft α-Fe phase layers. The results show that the magnetic properties of exchange coupled Nd{sub 2}Fe{sub 14}B/α-Fe multilayer systems can be enhanced by efficient interphase exchange coupling between magnetically hard Nd{sub 2}Fe{sub 14}B layers and soft α-Fe layers. - Highlights: • Phase layer thicknesses dependence of magnetic properties of Nd{sub 2}Fe{sub 14}B/α-Fe multilayers. • Analyzation of the effectiveness of exchange coupling between the Nd{sub 2}Fe{sub 14}B and α-Fe layers. • Dependence of the magnetic properties on direction of external field of exchange coupled Nd{sub 2}Fe{sub 14}B/α-Fe multilayers. • Dependence of the magnetic properties on magneto-crystalline anisotropy of exchange coupled Nd{sub 2}Fe{sub 14}B/α-Fe multilayers.

  1. Two ions coupled to an optical cavity : from an enhanced quantum computer interface towards distributed quantum computing

    International Nuclear Information System (INIS)

    Casabone, B.

    2015-01-01

    Distributed quantum computing, an approach to scale up the computational power of quantum computers, requires entanglement between nodes of a quantum network. In our research group, two building blocks of schemes to entangle two ion-based quantum computers using cavity-based quantum interfaces have recently been demonstrated: ion-photon entanglement and ion-photon state mapping. In this thesis work, we extend the first building block in order to entangle two ions located in the same optical cavity. The entanglement generated by this protocol is efficient and heralded, and as it does not rely on the fact that ions interact with the same cavity, our results are a stepping stone towards the efficient generation of entanglement of remote ion-based quantum computers. In the second part of this thesis, we discuss how collective effects can be used to improve the performance of a cavity-based quantum interface. We show that by using two ions in the so-called superradiant state, the coupling strength between the two ions and the optical cavity is effectively increased compared to the single-ion case. As a complementary result, the creation of a state of two ions that exhibits a reduced coupling strength to the optical cavity, i.e., a subradiant state, is shown. Finally, we demonstrate a direct application of the increased coupling strength that the superradiant state exhibits by showing an enhanced version of the ion-photon state mapping process. By using the current setup and a second one that is being assembled, we intend to build a quantum network. The heralded ion-ion entanglement protocol presented in this thesis work will be used to entangle ions located in both setups, an experiment that requires photons generated in both apparatuses to be indistinguishable. Collective effects then can be used to modify the waveform of photons exiting the cavity in order to effect the desired photon indistinguishability. (author) [de

  2. Interlayer Exchange Coupling: A General Scheme Turning Chiral Magnets into Magnetic Multilayers Carrying Atomic-Scale Skyrmions.

    Science.gov (United States)

    Nandy, Ashis Kumar; Kiselev, Nikolai S; Blügel, Stefan

    2016-04-29

    We report on a general principle using interlayer exchange coupling to extend the regime of chiral magnetic films in which stable or metastable magnetic Skyrmions can appear at a zero magnetic field. We verify this concept on the basis of a first-principles model for a Mn monolayer on a W(001) substrate, a prototype chiral magnet for which the atomic-scale magnetic texture is determined by the frustration of exchange interactions, impossible to unwind by laboratory magnetic fields. By means of ab initio calculations for the Mn/W_{m}/Co_{n}/Pt/W(001) multilayer system we show that for certain thicknesses m of the W spacer and n of the Co reference layer, the effective field of the reference layer fully substitutes the required magnetic field for Skyrmion formation.

  3. Potential of ion chromatography coupled to isotope ratio mass spectrometry via a liquid interface for beverages authentication.

    Science.gov (United States)

    Guyon, Francois; Gaillard, Laetitia; Brault, Audrey; Gaultier, Nicolas; Salagoïty, Marie-Hélène; Médina, Bernard

    2013-12-27

    New tools for the determination of characteristic parameters for food authentication are requested to prevent food adulteration from which health concerns, unfair competition could follow. A new coupling in the area of compound-specific carbon 13 isotope ratio (δ(13)C) analysis was developed to simultaneously quantify δ(13)C values of sugars and organic acids. The coupling of ion chromatography (IC) together with isotope ratio mass spectrometry (IRMS) can be achieved using a liquid interface allowing a chemical oxidation (co) of organic matter. Synthetic solutions containing 1 polyol (glycerol), 3 carbohydrates (sucrose, glucose and fructose) and 12 organic acids (gluconic, lactic, malic, tartaric, oxalic, fumaric, citric and isocitric) were used to optimize chromatographic conditions (concentration gradient and 3 types of column) and the studied isotopic range (-32.28 to -10.65‰) corresponds to the values found in food products. Optimum chromatographic conditions are found using an IonPac AS15, an elution flow rate of 0.3mLmin(-1) and a linear concentration gradient from 2 to 76mM (rate 21mMmin(-1)). Comparison between δ(13)C value individually obtained for each compound with the coupling IRMS and elemental analyzer, EA-IRMS, and the ones measured on the mixture of compounds by IC-co-IRMS does not reveal any isotope fractionation. Thus, under these experimental conditions, IC-co-IRMS results are accurate and reproducible. This new coupling was tested on two food matrices, an orange juice and a sweet wine. Some optimization is necessary as the concentration range between sugars and organic acids is too large: an increase in the filament intensity of the IRMS is necessary to simultaneously detect the two compound families. These first attempts confirm the good results obtained on synthetic solutions and the strong potential of the coupling IC-co-IRMS in food authentication area. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Self-assembled monolayer exchange reactions as a tool for channel interface engineering in low-voltage organic thin-film transistors.

    Science.gov (United States)

    Lenz, Thomas; Schmaltz, Thomas; Novak, Michael; Halik, Marcus

    2012-10-02

    In this work, we compared the kinetics of monolayer self-assembly long-chained carboxylic acids and phosphonic acids on thin aluminum oxide surfaces and investigated their dielectric properties in capacitors and low-voltage organic thin-film transistors. Phosphonic acid anchor groups tend to substitute carboxylic acid molecules on aluminum oxide surfaces and thus allow the formation of mixed or fully exchanged monolayers. With different alkyl chain substituents (n-alkyl or fluorinated alkyl chains), the exchange reaction can be monitored as a function of time by static contact angle measurements. The threshold voltage in α,α'-dihexyl-sexithiophene thin-film transistors composed of such mixed layer dielectrics correlates with the exchange progress and can be tuned from negative to positive values or vice versa depending on the dipole moment of the alkyl chain substituents. The change in the dipole moment with increasing exchange time also shifts the capacitance of these devices. The rate constants for exchange reactions determined by the time-dependent shift of static contact angle, threshold voltage, and capacitance exhibit virtually the same value thus proving the exchange kinetics to be highly controllable. In general, the exchange approach is a powerful tool in interface engineering, displaying a great potential for tailoring of device characteristics.

  5. Low-temperature, non-stoichiometric oxygen isotope exchange coupled to Fe(II)-goethite interactions

    Energy Technology Data Exchange (ETDEWEB)

    Frierdich, Andrew J. [Univ. of Wisconsin, Madison, WI (United States); Univ. of Iowa, Iowa City, IA (United States); Beard, Brian L. [Univ. of Wisconsin, Madison, WI (United States); Rosso, Kevin M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Scherer, Michelle M. [Univ. of Iowa, Iowa City, IA (United States); Spicuzza, Michael J. [Univ. of Wisconsin, Madison, WI (United States); Valley, John W. [Univ. of Wisconsin, Madison, WI (United States); Johnson, Clark M. [Univ. of Wisconsin, Madison, WI (United States)

    2015-07-01

    The oxygen isotope composition of natural iron oxide minerals has been widely used as a paleoclimate proxy. Interpretation of their stable isotope compositions, however, requires accurate knowledge of isotopic fractionation factors and an understanding of their isotopic exchange kinetics, the latter of which informs us how diagenetic processes may alter their isotopic compositions. Prior work has demonstrated that crystalline iron oxides do not significantly exchange oxygen isotopes with pure water at low temperature, which has restricted studies of isotopic fractionation factors to precipitation experiments or theoretical calculations. Using a double three-isotope method (¹⁸O-¹⁷O-¹⁶O and ⁵⁷Fe-⁵⁶Fe-⁵⁴Fe) we compare O and Fe isotope exchange kinetics, and demonstrate, for the first time, that O isotope exchange between structural O in crystalline goethite and water occurs in the presence of aqueous Fe(II) (Fe(II)aq) at ambient temperature (i.e., 22–50 °C). The three-isotope method was used to extrapolate partial exchange results to infer the equilibrium, mass-dependent isotope fractionations between goethite and water. In addition, this was combined with a reversal approach to equilibrium by reacting goethite in two unique waters that vary in composition by about 16‰ in ¹⁸O/¹⁶O ratios. Our results show that interactions between Fe(II)aq and goethite catalyzes O isotope exchange between the mineral and bulk fluid; no exchange (within error) is observed when goethite is suspended in ¹⁷O-enriched water in the absence of Fe(II)aq. In contrast, Fe(II)-catalyzed O isotope exchange is accompanied by significant changes in ¹⁸O/¹⁶O ratios. Despite significant O exchange, however, we observed disproportionate amounts of Fe versus O exchange, where Fe isotope exchange in goethite was roughly three times that of O. This disparity provides novel insight into the reactivity of oxide minerals in aqueous

  6. Exchange-coupled Fe3O4/CoFe2O4 nanoparticles for advanced magnetic hyperthermia

    Science.gov (United States)

    Glassell, M.; Robles, J.; Das, R.; Phan, M. H.; Srikanth, H.

    Iron oxide nanoparticles especially Fe3O4, γ-Fe2O3 have been extensively studied for magnetic hyperthermia because of their tunable magnetic properties and stable suspension in superparamagnetic regime. However, their relatively low heating capacity hindered practical application. Recently, a large improvement in heating efficiency has been reported in exchange-coupled nanoparticles with exchange coupling between soft and hard magnetic phases. Here, we systematically studied the effect of core and shell size on the heating efficiency of the Fe3O4/CoFe2O4 core/shell nanoparticles. The nanoparticles were synthesized using thermal decomposition of organometallic precursors. Transmission electron microscopy (TEM) showed formation of spherical shaped Fe3O4 and Fe3O-/CoFe2O4 nanoparticles. Magnetic measurements showed high magnetization (≅70 emu/g) and superparamagnetic behavior for the nanoparticles at room temperature. Magnetic hyperthermia results showed a large increase in specific absorption rate (SAR) for 8nm Fe3O4/CoFe2O4 compared to Fe3O4 nanoparticles of the same size. The heating efficiency of the Fe3O4/CoFe2O4 with 1 nm CoFe2O4 (shell) increased from 207 to 220 W/g (for 800 Oe) with increase in core size from 6 to 8 nm. The heating efficiency of the Fe3O4/CoFe2O4 with 2 nm CoFe2O4 (shell) and core size of 8 nm increased from 220 to 460 W/g (for 800 Oe). These exchange-coupled Fe3O4/CoFe2O4 core/shell nanoparticles can be a good candidate for advanced hyperthermia application.

  7. Entropy Exchange in Coupled Field-Superconducting Charge Qubit System with Intrinsic Decoherence

    Institute of Scientific and Technical Information of China (English)

    SHAO Bin; ZHANG Jian; ZOU Jian

    2006-01-01

    Based on the intrinsic decoherence effect, partial entropy properties of a super conducting charge qubitinside a single-mode cavity field is investigated, and entropy exchange which is recently regarded as a kind of anti-correlated behavior of the entropy between subsystems is explored. Our results show that although the intrinsic decoherenceleads to an effective irreversible evolution of the interacting system due to a suppression of coherent quantum features through the decay of off-diagonal matrix elements of the density operator and has an apparently influence on the partial entropy of two individual subsystems, it does not effect the entropy exchange between the two subsystems.

  8. Spin spring behavior in exchange coupled soft and high-coercivity hard ferromagnets.

    Energy Technology Data Exchange (ETDEWEB)

    Shull, R. D.; Shapiro, A. J.; Gornakov, V. S.; Nikitenko, V. I.; Jiang, J. S.; Kaper, H.; Leaf, G.; Bader, S. D.

    2000-11-01

    The magnetization reversal processes in an epitaxial Fe/Sm{sub 2}Co{sub 7} structure were investigated using the magneto-optical indicator film technique. The dependence of the magnitude and the orientation of the structure average magnetization have been studied on both cycling and rotating the external magnetic field. It was discovered that the magnetization reversal of the soft ferromagnet can proceed by formation of not only one-dimensional, but also two-dimensional, exchange spin springs. Experimental data is compared with a theoretical estimation of the rotational hysteresis loop for a spin system containing a one-dimensional exchange spring.

  9. Thermal stability, thermal expansion and grain-growth in exchange-coupled Fe-Pt-Ag-B bulk nanocomposite magnets

    International Nuclear Information System (INIS)

    Nicula, R.; Crisan, O.; Crisan, A.D.; Mercioniu, I.; Stir, M.; Vasiliu, F.

    2015-01-01

    Highlights: • Formation of the L10 FePt hard-magnetic phase (>90%) directly in the as-cast state. • Specific alternating hard/soft nanostructure is stable to 600 °C without grain growth. • Anisotropic and non-linear thermal expansion effects. • The FePtAgB alloy behaves like a single magnetic phase (full exchange coupling). - Abstract: Rare-earth free (RE-free) exchange coupling nanocomposite magnets are intensively studied nowadays due to their potential use in applications demanding stable high-temperature operation and corrosion resistance. In this respect, the FePt alloy system is one of the most actively addressed potential permanent magnet solutions. In FePt alloys, promising magnetic features arise from the co-existence of hard magnetic L1 0 FePt and soft magnetic L1 2 Fe 3 Pt phases emerged from the same metastable precursor. The present work deals with an in-situ temperature-resolved synchrotron radiation study of the thermal stability, thermal expansion and microstructure evolution in exchange-coupled FePtAgB alloys. The as-cast microstructural state as well as the optimized magnetic behavior are given as reference and correlated to the observed microstructural evolution with temperature. The melt-spun Fe 48 Pt 28 Ag 6 B 18 alloy ribbons were examined in situ by synchrotron X-ray powder diffraction from ambient temperature up to 600 °C. The FePt-Fe 3 Pt exchange-coupled microstructure achieved by rapid solidification is not significantly altered during the high temperature exposure. The thermal expansion of the FePt L1 0 unit cell has been found to be strongly anisotropic, being essentially an in-plane expansion which may be seen as an anisotropic invar effect. For the FePt L1 0 phase, a significant deviation from linear thermal expansion is observed at the Curie temperature T C = 477 °C. This non-linear behavior above T C is tentatively linked to a diffusion/segregation mechanism of Ag. The promising hard magnetic properties as well as the

  10. Exchange coupling behavior in bimagnetic CoFe{sub 2}O{sub 4}/CoFe{sub 2} nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Leite, G.C.P. [Instituto de Fisica, Universidade Federal de Mato Grosso, 78060-900 Cuiaba-MT (Brazil); Chagas, E.F., E-mail: efchagas@fisica.ufmt.br [Instituto de Fisica, Universidade Federal de Mato Grosso, 78060-900 Cuiaba-MT (Brazil); Pereira, R.; Prado, R.J. [Instituto de Fisica, Universidade Federal de Mato Grosso, 78060-900 Cuiaba-MT (Brazil); Terezo, A.J. [Departamento de Quimica, Universidade Federal do Mato Grosso, 78060-900 Cuiaba-MT (Brazil); Alzamora, M.; Baggio-Saitovitch, E. [Centro Brasileiro de Pesquisas Fisicas, Rua Xavier Sigaud 150 Urca, Rio de Janeiro (Brazil)

    2012-09-15

    In this work we report a study of the magnetic behavior of ferrimagnetic oxide CoFe{sub 2}O{sub 4} and ferrimagnetic oxide/ferromagnetic metal CoFe{sub 2}O{sub 4}/CoFe{sub 2} nanocomposite. The latter compound is a good system to study hard ferrimagnet/soft ferromagnet exchange coupled. Two steps were followed to synthesize the bimagnetic CoFe{sub 2}O{sub 4}/CoFe{sub 2} nanocomposite: (i) first, preparation of CoFe{sub 2}O{sub 4} nanoparticles using a simple hydrothermal method, and (ii) second, reduction reaction of cobalt ferrite nanoparticles using activated charcoal in inert atmosphere and high temperature. The phase structures, particle sizes, morphology, and magnetic properties of CoFe{sub 2}O{sub 4} nanoparticles were investigated by X-Ray diffraction (XRD), Mossbauer spectroscopy (MS), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) with applied field up to 3.0 kOe at room temperature and 50 K. The mean diameter of CoFe{sub 2}O{sub 4} particles is about 16 nm. Mossbauer spectra revealed two sites for Fe{sup 3+}. One site is related to Fe in an octahedral coordination and the other one to the Fe{sup 3+} in a tetrahedral coordination, as expected for a spinel crystal structure of CoFe{sub 2}O{sub 4}. TEM measurements of nanocomposite showed the formation of a thin shell of CoFe{sub 2} on the cobalt ferrite and indicate that the nanoparticles increase to about 100 nm. The magnetization of the nanocomposite showed a hysteresis loop that is characteristic of exchange coupled systems. A maximum energy product (BH){sub max} of 1.22 MGOe was achieved at room temperature for CoFe{sub 2}O{sub 4}/CoFe{sub 2} nanocomposites, which is about 115% higher than the value obtained for CoFe{sub 2}O{sub 4} precursor. The exchange coupling interaction and the enhancement of product (BH){sub max} in nanocomposite CoFe{sub 2}O{sub 4}/CoFe{sub 2} are discussed. - Highlights: Black-Right-Pointing-Pointer CoFe{sub 2}O{sub 4}/CoFe{sub 2} nanocomposite

  11. Exchange electron-hole interaction of two-dimensional magnetoexcitons under the influence of the Rashba spin-orbit coupling

    International Nuclear Information System (INIS)

    Moskalenko, S.A.; Podlesny, I.V.; Lelyakov, I.A.; Novikov, B.V.; Kiselyova, E.S.; Gherciu, L.

    2011-01-01

    The Rashba spin-orbit coupling (RSOC) in the case of two-dimensional (2D) electrons and holes in a strong perpendicular magnetic field was studied. The spinor-type wave functions are characterized by different numbers of Landau levels in different spin projections. For electrons they differ by 1 as was established earlier by Rashba, whereas for holes they differ by 3. Two lowest electron states and four lowest hole states of Landau quantization give rise to eight 2D magnetoexciton states. The exchange electron-hole interaction in the frame of these states is investigated.

  12. Preliminary SP-100/Stirling heat exchanger designs

    International Nuclear Information System (INIS)

    Schmitz, P.; Tower, L.; Blue, B.; Dunn, P.

    1994-01-01

    Analytic modeling of several heat exchanger concepts to couple the SP-100 nuclear reactor lithium loop and the Space Stirling Power Convertor (SSPC) was performed. Four 25 kWe SSPC's are used to produce the required 100 kW of electrical power. This design work focused on the interface between a single SSPC and the primary lithium loop. Manifolding to separate and collect the four channel flow was not modeled. This work modeled two separate types of heat exchanger interfaces (conductive coupling and radiative coupling) to explore their relative advantages and disadvantages. The minimum mass design of the conductively coupled concepts was 18 kg or 0.73 kg/kWe for a single 25 kWe convertor. The minimum mass radiatively coupled concept was 41 kg or 1.64 kg/kWe. The direct conduction heat exchanger provides a lighter weight system because of its ability to operate the Stirling convertor evaporator at higher heat fluxes than those attainable by the radiatively coupled systems. Additionally the conductively coupled concepts had relatively small volumes and provide potentially simpler assembly. Their disadvantages were the tight tolerances and material joining problems associated with this refractory to superalloy interface. The advantages of the radiatively coupled designs were the minimal material interface problems

  13. Correlation between charge transfer and exchange coupling in carbon-based magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Anh Tuan, E-mail: tuanna@hus.edu.vn [Faculty of Physics, VNU University of Science, 334 Nguyen Trai, Thanh Xuan, Ha Noi (Viet Nam); Science and Technology Department, Vietnam National University, Hanoi, 144 Xuan Thuy, Cau Giay, Hanoi (Viet Nam); Japan Advanced Institute of Science and Technology, 1-1, Asahidai, Nomi, Ishikawa, 923-1292 Japan (Japan); Nguyen, Van Thanh; Nguyen, Huy Sinh [Faculty of Physics, VNU University of Science, 334 Nguyen Trai, Thanh Xuan, Ha Noi (Viet Nam); Pham, Thi Tuan Anh [Faculty of Physics, VNU University of Science, 334 Nguyen Trai, Thanh Xuan, Ha Noi (Viet Nam); Faculty of Science, College of Hai Duong, Nguyen Thi Due, Hai Duong (Viet Nam); Do, Viet Thang [Faculty of Physics, VNU University of Science, 334 Nguyen Trai, Thanh Xuan, Ha Noi (Viet Nam); Faculty of Science, Haiphong University, 171 Phan Dang Luu, Kien An, Hai Phong (Viet Nam); Dam, Hieu Chi [Japan Advanced Institute of Science and Technology, 1-1, Asahidai, Nomi, Ishikawa, 923-1292 Japan (Japan)

    2015-10-15

    Several forms of carbon-based magnetic materials, i.e. single radicals, radical dimers, and alternating stacks of radicals and diamagnetic molecules, have been investigated using density-functional theory with dispersion correction and full geometry optimization. Our calculated results demonstrate that the C{sub 31}H{sub 15} (R{sub 4}) radical has a spin of ½. However, in its [R{sub 4}]{sub 2} dimer structure, the net spin becomes zero due to antiferromagnetic spin-exchange between radicals. To avoid antiferromagnetic spin-exchange of identical face-to-face radicals, eight alternating stacks, R{sub 4}/D{sub 2m}/R{sub 4} (with m = 3-10), were designed. Our calculated results show that charge transfer (Δn) between R{sub 4} radicals and the diamagnetic molecule D{sub 2m} occurs with a mechanism of spin exchange (J) in stacks. The more electrons that transfer from R{sub 4} to D{sub 2m}, the stronger the ferromagnetic spin-exchange in stacks. In addition, our calculated results show that Δn can be tailored by adjusting the electron affinity (E{sub a}) of D{sub 2m}. The correlation between Δn, E{sub a}, m, and J is discussed. These results give some hints for the design of new ferromagnetic carbon-based materials.

  14. Exchange coupling transformations in Cu (II) heterospin complexes of “breathing crystals” under structural phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Morozov, Vitaly A.; Petrova, Marina V.; Lukzen, Nikita N., E-mail: luk@tomo.nsc.ru [International Tomography Center SB RUS, Institutskaya Str. 3a, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090 (Russian Federation)

    2015-08-15

    Family of “breathing crystals” is the polymer-chain complexes of Cu(hfac){sub 2} with nitroxides. The polymer chains consist of one-, two- or three-spin clusters. The “breathing crystals” experience simultaneous magnetic and Jahn-Teller type structural phase transitions with change of total cluster spin and drastic change of bond lengths (ca. 10-12%). For the first time the intra-cluster magnetic couplings in ”breathing crystals” have been calculated both by band structure methods GGA + U and hybrid DFT (B3LYP and PBE0) for the isolated exchange clusters. The temperature dependence of the magnetic coupling constant was calculated for two polymer-chain compounds of the “breathing crystal” family - C{sub 21}H{sub 19}CuF{sub 12}N{sub 4}O{sub 6} with the chains containing two-spin clusters and C{sub 22}H{sub 21}CuF{sub 12}N{sub 4}O{sub 6} with the chains of alternating three-spin clusters and one-spin sites. It was found that adding a Hubbard-like parameter not only to the copper 3d electrons but also to the oxygen 2p electrons (GGA + U{sub d} + U{sub p} approach) results in an improved description of exchange coupling in the “breathing crystal” compounds. At the same time treatment of the isolated clusters by a large basis hybrid DFT with high computational cost provides a similar quality fit of the experimental magneto-chemical data as that for the GGA + U{sub d} + U{sub p} band structure calculation scheme. Our calculations also showed that in spite of the abrupt transformation of the magnetic coupling constant under the phase transition, the band gap in the “breathing crystals” remains about the same value with temperature decrease.

  15. Interface code between WIMS-AECL and RFSP-IST for coupling computing

    International Nuclear Information System (INIS)

    Xu Liangwang; Liu Yu; Jia Baoshan

    2007-01-01

    A code based on the protocols of Telnet and FTP is developed with C++ for coupling computing between WIMS-AECL and RFSP-IST. the input document of WIMS-AECL and RFSP-ISP cna be generated automatically and be submitted to server, the output document will be downloaded by the end of computing. the function of analyzing standard output document is also included in this code. After simple updating, this code can meet the requirement of other code using input document, e.g. CATHENA. A pilot study of the relation between void fraction and reactivity in TACR, some valuable conclusions has been achieved. (authors)

  16. Towards the blackbox computation of magnetic exchange coupling parameters in polynuclear transition-metal complexes: theory, implementation, and application.

    Science.gov (United States)

    Phillips, Jordan J; Peralta, Juan E

    2013-05-07

    We present a method for calculating magnetic coupling parameters from a single spin-configuration via analytic derivatives of the electronic energy with respect to the local spin direction. This method does not introduce new approximations beyond those found in the Heisenberg-Dirac Hamiltonian and a standard Kohn-Sham Density Functional Theory calculation, and in the limit of an ideal Heisenberg system it reproduces the coupling as determined from spin-projected energy-differences. Our method employs a generalized perturbative approach to constrained density functional theory, where exact expressions for the energy to second order in the constraints are obtained by analytic derivatives from coupled-perturbed theory. When the relative angle between magnetization vectors of metal atoms enters as a constraint, this allows us to calculate all the magnetic exchange couplings of a system from derivatives with respect to local spin directions from the high-spin configuration. Because of the favorable computational scaling of our method with respect to the number of spin-centers, as compared to the broken-symmetry energy-differences approach, this opens the possibility for the blackbox exploration of magnetic properties in large polynuclear transition-metal complexes. In this work we outline the motivation, theory, and implementation of this method, and present results for several model systems and transition-metal complexes with a variety of density functional approximations and Hartree-Fock.

  17. Measurements of gaseous mercury exchanges at the sediment-water, water-atmosphere and sediment-atmosphere interfaces of a tidal environment (Arcachon Bay, France).

    Science.gov (United States)

    Bouchet, Sylvain; Tessier, Emmanuel; Monperrus, Mathilde; Bridou, Romain; Clavier, Jacques; Thouzeau, Gerard; Amouroux, David

    2011-05-01

    The elemental mercury evasion from non-impacted natural areas is of significant importance in the global Hg cycle due to their large spatial coverage. Intertidal areas represent a dynamic environment promoting the transformations of Hg species and their subsequent redistribution. A major challenge remains in providing reliable data on Hg species variability and fluxes under typical transient tidal conditions found in such environment. Field experiments were thus carried out to allow the assessment and comparison of the magnitude of the gaseous Hg fluxes at the three interfaces, sediment-water, sediment-atmosphere and water-atmosphere of a mesotidal temperate lagoon (Arcachon Bay, Aquitaine, France) over three distinct seasonal conditions. The fluxes between the sediment-water and the sediment-atmosphere interfaces were directly evaluated with field flux chambers, respectively static or dynamic. Water-atmosphere fluxes were evaluated from ambient concentrations using a gas exchange model. The fluxes at the sediment-water interface ranged from -5.0 to 5.1 ng m(-2) h(-1) and appeared mainly controlled by diffusion. The occurrence of macrophytic covers (i.e.Zostera noltii sp.) enhanced the fluxes under light radiations. The first direct measurements of sediment-atmosphere fluxes are reported here. The exchanges were more intense and variable than the two other interfaces, ranging between -78 and 40 ng m(-2) h(-1) and were mostly driven by the overlying atmospheric Hg concentrations and superficial sediment temperature. The exchanges between the water column and the atmosphere, computed as a function of wind speed and gaseous mercury saturation ranged from 0.4 to 14.5 ng m(-2) h(-1). The flux intensities recorded over the intertidal sediments periodically exposed to the atmosphere were roughly 2 to 3 times higher than the fluxes of the other interfaces. The evasion of elemental mercury from emerged intertidal sediments is probably a significant pathway for Hg evasion in

  18. Development of Coupled Interface System between the FADAS Code and a Source-term Evaluation Code XSOR for CANDU Reactors

    International Nuclear Information System (INIS)

    Son, Han Seong; Song, Deok Yong; Kim, Ma Woong; Shin, Hyeong Ki; Lee, Sang Kyu; Kim, Hyun Koon

    2006-01-01

    An accident prevention system is essential to the industrial security of nuclear industry. Thus, the more effective accident prevention system will be helpful to promote safety culture as well as to acquire public acceptance for nuclear power industry. The FADAS(Following Accident Dose Assessment System) which is a part of the Computerized Advisory System for a Radiological Emergency (CARE) system in KINS is used for the prevention against nuclear accident. In order to enhance the FADAS system more effective for CANDU reactors, it is necessary to develop the various accident scenarios and reliable database of source terms. This study introduces the construction of the coupled interface system between the FADAS and the source-term evaluation code aimed to improve the applicability of the CANDU Integrated Safety Analysis System (CISAS) for CANDU reactors

  19. Interfacial exchange, magnetic coupling and magnetoresistance in ultra-thin GdN/NbN/GdN tri-layers

    Science.gov (United States)

    Takamura, Yota; Goncalves, Rafael S.; Cascales, Juan Pedro; Altinkok, Atilgan; de Araujo, Clodoaldo I. L.; Lauter, Valeria; Moodera, Jagadeesh S.; MIT Team

    Superconducting spin-valve structures with a superconductive (SC) spacer sandwiched between ferromagnetic (FM) insulating layers [Li PRL 2013, Senapati APL 2013, Zhu Nat. Mat. 2016.] are attractive since the SC and FM characteristics can mutually be controlled by the proximity effect. We investigated reactively sputtered GdN/NbN/GdN tri-layer structures with various (SC) NbN spacer thicknesses (dNbN) from superconducting to normal layers. Magnetoresistive behavior similar to GMR in metallic magnetic multilayers was observed in the tri-layers with dNbN between 5-10 monolayers (ML), where thinner NbN layers did not show superconductivity down to 4.2 K. The occurrence of GMR signal indicates the presence of a ML of FM metallic layers at the GdN/NbN interfaces. Susceptibility and transport measurements in these samples revealed that the interface layers (ILs) are ferromagnetically coupled with adjacent GdN layers. The thickness of each of the IL is deduced to be about 1.25 ML, and as a result for dNbN magnetically coupled and switched simultaneously. These findings and interfacial characterization by various techniques will be presented. Work supported by NSF and ONR Grants.

  20. The resonance susceptibility of two-layer exchange-coupled ferromagnetic film with a combined uniaxial and cubic anisotropy in the layers

    Energy Technology Data Exchange (ETDEWEB)

    Shul’ga, N.V., E-mail: shulga@anrb.ru; Doroshenko, R.A.

    2016-12-01

    A numerical investigation of the resonance dynamic susceptibility of ferromagnetic exchange-coupled two-layer films with a combined cubic and uniaxial magnetic anisotropy of the layers has been performed. It has been found that the presence of cubic anisotropy leads to the fact that much of the off-diagonal components of the dynamic susceptibility are nonzero. The change of the ferromagnetic resonance frequencies and dynamic susceptibility upon the magnetization along the [100], [010], and [011] directions have been calculated. The evolution of the profile of the dynamic susceptibility occurring during the magnetization has been described. The impact of changes in the distribution of equilibrium and dynamic components of the magnetization on the dependences of the components of the dynamic susceptibility and the ferromagnetic resonance frequency on the external magnetic fields has been discussed. - Highlights: • The extremes in the dependences of integrated dynamic susceptibility components are observed at low fields. • Lower extremes can be observed at a shift of the localization of the lower FMR mode toward the interface between the layers. • The features of the distribution of the dynamic susceptibility over the thickness have been discussed. • The cubic anisotropy leads to the fact that the off-diagonal integrated dynamic susceptibility components are essential. • FMR signal can be excited in vicinity of the interlayer boundary.

  1. Direct coupling of a dense (supercritical) gas chromatograph to a mass spectrometer using a supersonic molecular beam interface

    International Nuclear Information System (INIS)

    Randall, L.G.; Wahrhaftig, A.L.

    1981-01-01

    A detecting mass spectrometer has been successfully coupled to a dense gas (supercritical fluid) chromatograph to produce an instrument (DGC/MS) that may be an alternative to high performance liquid chromatograph/mass spectrometer instruments (HPLC/MS) and gas chromatograph/mass spectrometer instruments (GC/MS) for analysis of involatile and/or thermally labile compounds. The mobile phase in DGC is a gas held at temperatures above the critical temperature and at pressures sufficient to obtain nearly liquid-like densities. DGC combines advantages of GC and HPLC: rapid separations, moderate operating temperatures, and analysis of involatile compounds. An advantage unique to DGC is the solvent power dependence upon pressure. While several groups have studied DGC, its development has been limited by the lack of a sensitive and selective detector. Hence, work has been directed towards the design and construction of a DGC/MS resulting in a trial instrument capable of chromatographic pressures of at least 300 atm and temperatures from 10 0 to 60 0 C. The DGC/MS coupling has been accomplished by the use of a supersonic molecular beam interface. This application of molecular beam formation appears to be unique in its requirements of a large pressure ratio (approx.10 8 ), low flow rates, and low final pressures. The authors outline characteristics of supersonic jets and molecular beams pertinent to the design of such an instrument. The interface which uses pumping speeds of 2400 and 1200 l/s in the beam forming chambers is described in detail, while the other components: the detecting mass spectrometer, the dense gas supply, and the DGC: are briefly described. Preliminary work with this instrument has established the feasibility of DGC/MS as an analytical technique and further development is recommended

  2. Holographic method coupled with an optoelectronic interface applied in the ionizing radiation dosimetry

    International Nuclear Information System (INIS)

    Nicolau-Rebigan, S.; Sporea, D.; Niculescu, V.I.R.

    2000-01-01

    The paper presents a holographic method applied in the ionizing radiation dosimetry. It is possible to use two types of holographic interferometry like as double exposure holographic interferometry, or fast real time holographic interferometry. In this paper the applications of holographic interferometry to ionizing radiation dosimetry are presented. The determination of the accurate value of dose delivered by an ionizing radiation source (released energy per mass unit) is a complex problem which imposes different solutions depending on experimental parameters and it is solved with a double exposure holographic interferometric method associated with an optoelectronic interface and Z80 microprocessor. The method can determine the absorbed integral dose as well as the three-dimensional distribution of dose in given volume. The paper presents some results obtained in radiation dosimetry. Original mathematical relations for integral absorbed dose in irreversible radiolyzing liquids where derived. Irradiation effects can be estimated from the holographic fringes displacement and density. To measure these parameters, the obtained holographic interferograms were picked-up by a closed TV circuit system in such a way that a selected TV line explores the picture along the direction of interest using a special designed interface, a Z80 and our microprocessor system captures data along the selected TV line. When the integral dose is to be measured the microprocessor computes it from the information contained in the fringes distribution, according to the proposed formulae. Integral absorbed dose and spatial dose distribution can be estimated with an accuracy better than 4%. Some advantages of this method are outlined comparatively with conventional method in radiation dosimetry. The paper presents an original holographic set-up with an electronic interface, assisted by a Z80 microprocessor and used for nondestructive testing of transparent objects at the laser wave length

  3. Investigation of solvent dynamic effects on the electron self-exchange in two thianthrene couples with large inner reorganization energies.

    Science.gov (United States)

    Choto, P; Rasmussen, K; Grampp, G

    2015-02-07

    The large structural difference between thianthrene radical cations and their neutral parent molecules can possibly affect their electron self-exchange reactions. Before this can be investigated experimentally, it is necessary to first understand the influence of the solvent on such electron transfer reactions. To achieve this, the rate constants of the electron self-exchange reactions of the Th˙(+)/Th and MTh˙(+)/MTh (Th = thianthrene, MTh = 2,3,7,8-tetramethoxythianthrene) couples were investigated by means of ESR line broadening experiments in different solvents at 293 K. The diffusion corrected rate constants cover a range of 7.2 × 10(8)≤ket≤ 44 × 10(8) M(-1) s(-1) for Th˙(+)/Th and 2.0 × 10(8)≤ket≤ 11.6 × 10(8) M(-1) s(-1) for MTh˙(+)/MTh, respectively. The results were analysed within the framework of the Marcus Theory and the characteristic reorganization energy, λ, was determined. Both couples clearly show a solvent dynamic effect controlled by the longitudinal relaxation time τL of the solvents. However, the influence of the structural changes, in terms of λ, was smaller than expected at room temperature.

  4. Noise Reduction Based on an Fe -Rh Interlayer in Exchange-Coupled Heat-Assisted Recording Media

    Science.gov (United States)

    Vogler, Christoph; Abert, Claas; Bruckner, Florian; Suess, Dieter

    2017-11-01

    High storage density and high data rate are two of the most desired properties of modern hard disk drives. Heat-assisted magnetic recording (HAMR) is believed to achieve both. Recording media, consisting of exchange-coupled grains with a high and a low TC part, were shown to have low dc noise—but increased ac noise—compared to hard magnetic single-phase grains like FePt. We extensively investigate the influence of an Fe -Rh interlayer on the magnetic noise in exchange-coupled grains. We find an optimal grain design that reduces the jitter in the down-track direction by up to 30% and in the off-track direction by up to 50%, depending on the head velocity, compared to the same structures without FeRh. Furthermore, the mechanisms causing this jitter reduction are demonstrated. Additionally, we show that, for short heat pulses and low write temperatures, the switching-time distribution of the analyzed grain structure is reduced by a factor of 4 compared to the same structure without an Fe -Rh layer. This feature could be interesting for HAMR use with a pulsed laser spot and could encourage discussion of this HAMR technique.

  5. Magneto-hydrodynamics of coupled fluid–sheet interface with mass suction and blowing

    International Nuclear Information System (INIS)

    Ahmad, R.

    2016-01-01

    There are large number of studies which prescribe the kinematics of the sheet and ignore the sheet's mechanics. However, the current boundary layer analysis investigates the mechanics of both the electrically conducting fluid and a permeable sheet, which makes it distinct from the other studies in the literature. One of the objectives of the current study is to (i) examine the behaviour of magnetic field effect for both the surface and the electrically conducting fluid (ii) investigate the heat and mass transfer between a permeable sheet and the surrounding electrically conducting fluid across the hydro, thermal and mass boundary layers. Self-similar solutions are obtained by considering the RK45 technique. Analytical solution is also found for the stretching sheet case. The skin friction dual solutions are presented for various types of sheet. The influence of pertinent parameters on the dimensionless velocity, shear stress, temperature, mass concentration, heat and mass transfer rates on the fluid–sheet interface is presented graphically as well as numerically. The obtained results are of potential benefit for studying the electrically conducting flow over various soft surfaces such as synthetic plastics, soft silicone sheet and soft synthetic rubber sheet. These surfaces are easily deformed by thermal fluctuations or thermal stresses. - Highlights: • The momentum equation is modelled for both the surrounding MHD fluid and the sheet with the effects of mass suction and blowing. • The current study further investigates the heat and mass transfer characteristics between a permeable sheet and the surrounding electrically conducting fluid across the thermal and mass boundary layers. • Both the approximated and analytical techniques have been included for the purpose of comparison, and the perfect numerical agreements have been established with the previous studies. • Dual solutions for the skin friction coefficients are found for various categories of

  6. Absence of strain-mediated magnetoelectric coupling at fully epitaxial Fe/BaTiO{sub 3} interface (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Radaelli, G., E-mail: greta.radaelli@gmail.com; Petti, D.; Cantoni, M.; Rinaldi, C.; Bertacco, R. [LNESS Center - Dipartimento di Fisica del Politecnico di Milano, Como 22100 (Italy)

    2014-05-07

    Interfacial MagnetoElectric coupling (MEC) at ferroelectric/ferromagnetic interfaces has recently emerged as a promising route to achieve electrical writing of magnetic information in spintronic devices. For the prototypical Fe/BaTiO{sub 3} (BTO) system, various MEC mechanisms have been theoretically predicted. Experimentally, it is well established that using BTO single crystal substrates MEC is dominated by strain-mediated mechanisms. In case of ferromagnetic layers epitaxially grown onto BTO films, instead, no direct evidence for MEC has been provided, apart from the results obtained on tunneling junction sandwiching a BTO tunneling barrier. In this paper, MEC at fully epitaxial Fe/BTO interface is investigated by Magneto-Optical Kerr Effect and magnetoresistance measurements on magnetic tunnel junctions fabricated on BTO. We find no evidence for strain-mediated MEC mechanisms in epitaxial systems, likely due to clamping of BTO to the substrate. Our results indicate that pure electronic MEC is the route of choice to be explored for achieving the electrical writing of information in epitaxial ferromagnet-ferroelectric heterostructures.

  7. Absence of strain-mediated magnetoelectric coupling at fully epitaxial Fe/BaTiO3 interface (invited)

    International Nuclear Information System (INIS)

    Radaelli, G.; Petti, D.; Cantoni, M.; Rinaldi, C.; Bertacco, R.

    2014-01-01

    Interfacial MagnetoElectric coupling (MEC) at ferroelectric/ferromagnetic interfaces has recently emerged as a promising route to achieve electrical writing of magnetic information in spintronic devices. For the prototypical Fe/BaTiO 3 (BTO) system, various MEC mechanisms have been theoretically predicted. Experimentally, it is well established that using BTO single crystal substrates MEC is dominated by strain-mediated mechanisms. In case of ferromagnetic layers epitaxially grown onto BTO films, instead, no direct evidence for MEC has been provided, apart from the results obtained on tunneling junction sandwiching a BTO tunneling barrier. In this paper, MEC at fully epitaxial Fe/BTO interface is investigated by Magneto-Optical Kerr Effect and magnetoresistance measurements on magnetic tunnel junctions fabricated on BTO. We find no evidence for strain-mediated MEC mechanisms in epitaxial systems, likely due to clamping of BTO to the substrate. Our results indicate that pure electronic MEC is the route of choice to be explored for achieving the electrical writing of information in epitaxial ferromagnet-ferroelectric heterostructures

  8. Topological phase transition in anisotropic square-octagon lattice with spin-orbit coupling and exchange field

    Science.gov (United States)

    Yang, Yuan; Yang, Jian; Li, Xiaobing; Zhao, Yue

    2018-03-01

    We investigate the topological phase transitions in an anisotropic square-octagon lattice in the presence of spin-orbit coupling and exchange field. On the basis of the Chern number and spin Chern number, we find a number of topologically distinct phases with tuning the exchange field, including time-reversal-symmetry-broken quantum spin Hall phases, quantum anomalous Hall phases and a topologically trivial phase. Particularly, we observe a coexistent state of both the quantum spin Hall effect and quantum anomalous Hall effect. Besides, by adjusting the exchange filed, we find the phase transition from time-reversal-symmetry-broken quantum spin Hall phase to spin-imbalanced and spin-polarized quantum anomalous Hall phases, providing an opportunity for quantum spin manipulation. The bulk band gap closes when topological phase transitions occur between different topological phases. Furthermore, the energy and spin spectra of the edge states corresponding to different topological phases are consistent with the topological characterization based on the Chern and spin Chern numbers.

  9. Electrical measurement of antiferromagnetic moments in exchange-coupled IrMn/NiFe stacks

    Czech Academy of Sciences Publication Activity Database

    Martí, X.; Park, B.G.; Wunderlich, Joerg; Reichlová, Helena; Kurosaki, Y.; Yamada, M.; Yamamoto, H.; Nishide, A.; Hayakawa, J.; Takahashi, H.; Jungwirth, Tomáš

    2012-01-01

    Roč. 108, č. 1 (2012), , , "017201-1"-"017201-4" ISSN 0031-9007 EU Projects: European Commission(XE) 268066 - 0MSPIN Grant - others:AV ČR(CZ) AP0801 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100521 Keywords : tunneling magnetoresistance * antiferromagnetic spintronics * exchange bias Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 7.943, year: 2012

  10. Discrete ordinates solution of coupled conductive radiative heat transfer in a two-layer slab with Fresnel interfaces subject to diffuse and obliquely collimated irradiation

    International Nuclear Information System (INIS)

    Muresan, Cristian; Vaillon, Rodolphe; Menezo, Christophe; Morlot, Rodolphe

    2004-01-01

    The coupled conductive radiative heat transfer in a two-layer slab with Fresnel interfaces subject to diffuse and obliquely collimated irradiation is solved. The collimated and diffuse components problems are treated separately. The solution for diffuse radiation is obtained by using a composite discrete ordinates method and includes the development of adaptive directional quadratures to overcome the difficulties usually encountered at the interfaces. The complete radiation numerical model is validated against the predictions obtained by using the Monte Carlo method

  11. Relaxation dynamics and coherent energy exchange in coupled vibration-cavity polaritons (Conference Presentation)

    Science.gov (United States)

    Simpkins, Blake S.; Fears, Kenan P.; Dressick, Walter J.; Dunkelberger, Adam D.; Spann, Bryan T.; Owrutsky, Jeffrey C.

    2016-09-01

    Coherent coupling between an optical transition and confined optical mode have been investigated for electronic-state transitions, however, only very recently have vibrational transitions been considered. Here, we demonstrate both static and dynamic results for vibrational bands strongly coupled to optical cavities. We experimentally and numerically describe strong coupling between a Fabry-Pérot cavity and carbonyl stretch ( 1730 cm 1) in poly-methylmethacrylate and provide evidence that the mixed-states are immune to inhomogeneous broadening. We investigate strong and weak coupling regimes through examination of cavities loaded with varying concentrations of a urethane monomer. Rabi splittings are in excellent agreement with an analytical description using no fitting parameters. Ultrafast pump-probe measurements reveal transient absorption signals over a frequency range well-separated from the vibrational band, as well as drastically modified relaxation rates. We speculate these modified kinetics are a consequence of the energy proximity between the vibration-cavity polariton modes and excited state transitions and that polaritons offer an alternative relaxation path for vibrational excitations. Varying the polariton energies by angle-tuning yields transient results consistent with this hypothesis. Furthermore, Rabi oscillations, or quantum beats, are observed at early times and we see evidence that these coherent vibration-cavity polariton excitations impact excited state population through cavity losses. Together, these results indicate that cavity coupling may be used to influence both excitation and relaxation rates of vibrations. Opening the field of polaritonic coupling to vibrational species promises to be a rich arena amenable to a wide variety of infrared-active bonds that can be studied in steady state and dynamically.

  12. Large exchange-dominated domain wall velocities in antiferromagnetically coupled nanowires

    Science.gov (United States)

    Kuteifan, Majd; Lubarda, M. V.; Fu, S.; Chang, R.; Escobar, M. A.; Mangin, S.; Fullerton, E. E.; Lomakin, V.

    2016-04-01

    Magnetic nanowires supporting field- and current-driven domain wall motion are envisioned for methods of information storage and processing. A major obstacle for their practical use is the domain-wall velocity, which is traditionally limited for low fields and currents due to the Walker breakdown occurring when the driving component reaches a critical threshold value. We show through numerical and analytical modeling that the Walker breakdown limit can be extended or completely eliminated in antiferromagnetically coupled magnetic nanowires. These coupled nanowires allow for large domain-wall velocities driven by field and/or current as compared to conventional nanowires.

  13. Interface requirements to couple thermal-hydraulic codes to severe accident codes: ATHLET-CD

    Energy Technology Data Exchange (ETDEWEB)

    Trambauer, K. [GRS, Garching (Germany)

    1997-07-01

    The system code ATHLET-CD is being developed by GRS in cooperation with IKE and IPSN. Its field of application comprises the whole spectrum of leaks and large breaks, as well as operational and abnormal transients for LWRs and VVERs. At present the analyses cover the in-vessel thermal-hydraulics, the early phases of core degradation, as well as fission products and aerosol release from the core and their transport in the Reactor Coolant System. The aim of the code development is to extend the simulation of core degradation up to failure of the reactor pressure vessel and to cover all physically reasonable accident sequences for western and eastern LWRs including RMBKs. The ATHLET-CD structure is highly modular in order to include a manifold spectrum of models and to offer an optimum basis for further development. The code consists of four general modules to describe the reactor coolant system thermal-hydraulics, the core degradation, the fission product core release, and fission product and aerosol transport. Each general module consists of some basic modules which correspond to the process to be simulated or to its specific purpose. Besides the code structure based on the physical modelling, the code follows four strictly separated steps during the course of a calculation: (1) input of structure, geometrical data, initial and boundary condition, (2) initialization of derived quantities, (3) steady state calculation or input of restart data, and (4) transient calculation. In this paper, the transient solution method is briefly presented and the coupling methods are discussed. Three aspects have to be considered for the coupling of different modules in one code system. First is the conservation of masses and energy in the different subsystems as there are fluid, structures, and fission products and aerosols. Second is the convergence of the numerical solution and stability of the calculation. The third aspect is related to the code performance, and running time.

  14. Cobalamin speciation using reversed-phase micro-high-performance liquid chromatography interfaced to inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Yanes, Enrique G.; Miller-Ihli, Nancy J.

    2004-01-01

    Micro-high-performance liquid chromatography interfaced to inductively coupled plasma mass spectrometry was optimized for the determination and separation of a mixture of cobalt containing species. Four cobalamin species (cyanocobalamin, hydroxocobalamin, methylcobalamin, and 5'-deoxyadenosylcobalamin) representing the various forms of vitamin B12 as well as the harmful corrinoid analogue cobinamide dicyanide were separated using reversed-phase microcapillary chromatography with columns containing C18 packing material with a 2-μm particle size. Selection of organic solvents for the separation took into consideration compatibility with the inductively coupled plasma mass spectrometer being used for element specific detection. Optimized method conditions included use of a methanol gradient and make-up solution for the nebulizer. Some issues associated with dead volume were overcome by the extension of the gradient program. The total analysis time was 52 min. The column-to-column variability was evaluated and was found to be very reasonable (9% RSD on average), confirming that this method is rugged and that the technology should be easily transferred to other laboratories

  15. A Coupled Korteweg-de Vries System and Mass Exchanges among Solitons

    DEFF Research Database (Denmark)

    Miller, P. D.; Christiansen, Peter Leth

    2000-01-01

    V and the solution of a linear equation with nonconstant coefficients. The coupled KdV system may be viewed as a phenomenological model for the sharing of mass among interacting solitons of the (one-component) KdV equation. Results for the scattering theory of solutions of the nonconstant coefficient linear equation...

  16. Noise suppression and long-range exchange coupling for gallium arsenide spin qubits

    DEFF Research Database (Denmark)

    Malinowski, Filip

    This thesis presents the results of the experimental study performed on spin qubits realized in gate-defined gallium arsenide quantum dots, with the focus on noise suppression and long-distance coupling. First, we show that the susceptibility to charge noise can be reduced by reducing the gradien...

  17. Direct analysis of ultra-trace semiconductor gas by inductively coupled plasma mass spectrometry coupled with gas to particle conversion-gas exchange technique.

    Science.gov (United States)

    Ohata, Masaki; Sakurai, Hiromu; Nishiguchi, Kohei; Utani, Keisuke; Günther, Detlef

    2015-09-03

    An inductively coupled plasma mass spectrometry (ICPMS) coupled with gas to particle conversion-gas exchange technique was applied to the direct analysis of ultra-trace semiconductor gas in ambient air. The ultra-trace semiconductor gases such as arsine (AsH3) and phosphine (PH3) were converted to particles by reaction with ozone (O3) and ammonia (NH3) gases within a gas to particle conversion device (GPD). The converted particles were directly introduced and measured by ICPMS through a gas exchange device (GED), which could penetrate the particles as well as exchange to Ar from either non-reacted gases such as an air or remaining gases of O3 and NH3. The particle size distribution of converted particles was measured by scanning mobility particle sizer (SMPS) and the results supported the elucidation of particle agglomeration between the particle converted from semiconductor gas and the particle of ammonium nitrate (NH4NO3) which was produced as major particle in GPD. Stable time-resolved signals from AsH3 and PH3 in air were obtained by GPD-GED-ICPMS with continuous gas introduction; however, the slightly larger fluctuation, which could be due to the ionization fluctuation of particles in ICP, was observed compared to that of metal carbonyl gas in Ar introduced directly into ICPMS. The linear regression lines were obtained and the limits of detection (LODs) of 1.5 pL L(-1) and 2.4 nL L(-1) for AsH3 and PH3, respectively, were estimated. Since these LODs revealed sufficiently lower values than the measurement concentrations required from semiconductor industry such as 0.5 nL L(-1) and 30 nL L(-1) for AsH3 and PH3, respectively, the GPD-GED-ICPMS could be useful for direct and high sensitive analysis of ultra-trace semiconductor gas in air. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Magnetic coupling at rare earth ferromagnet/transition metal ferromagnet interfaces: A comprehensive study of Gd/Ni

    Science.gov (United States)

    Higgs, T. D. C.; Bonetti, S.; Ohldag, H.; Banerjee, N.; Wang, X. L.; Rosenberg, A. J.; Cai, Z.; Zhao, J. H.; Moler, K. A.; Robinson, J. W. A.

    2016-07-01

    Thin film magnetic heterostructures with competing interfacial coupling and Zeeman energy provide a fertile ground to study phase transition between different equilibrium states as a function of external magnetic field and temperature. A rare-earth (RE)/transition metal (TM) ferromagnetic multilayer is a classic example where the magnetic state is determined by a competition between the Zeeman energy and antiferromagnetic interfacial exchange coupling energy. Technologically, such structures offer the possibility to engineer the macroscopic magnetic response by tuning the microscopic interactions between the layers. We have performed an exhaustive study of nickel/gadolinium as a model system for understanding RE/TM multilayers using the element-specific measurement technique x-ray magnetic circular dichroism, and determined the full magnetic state diagrams as a function of temperature and magnetic layer thickness. We compare our results to a modified Stoner-Wohlfarth-based model and provide evidence of a thickness-dependent transition to a magnetic fan state which is critical in understanding magnetoresistance effects in RE/TM systems. The results provide important insight for spintronics and superconducting spintronics where engineering tunable magnetic inhomogeneity is key for certain applications.

  19. Magnetic exchange coupling in amorphous Fe80-xDy xB20 alloys

    International Nuclear Information System (INIS)

    Annouar, F.; Lassri, H.; Ayadi, M.; Omri, M.; Lassri, M.; Krishnan, R.

    2005-01-01

    Amorphous Fe 80-x Dy x B 20 alloys have been prepared by melt spinning and their magnetic properties have been studied. The mean field theory has been used to explain the temperature dependence of the magnetization. The exchange interactions between Co-Co and Dy-Co atom pairs have been evaluated. High-field magnetization studies on samples with stoichiometry close to that of a compensated ferrimagnet show a magnetic behavior that is characteristic of a non-collinear magnetic structure of the Dy and Fe sublattices. The region of the canted moments can be described by a phase diagram in the H-T plane

  20. A novel proton exchange membrane fuel cell based power conversion system for telecom supply with genetic algorithm assisted intelligent interfacing converter

    International Nuclear Information System (INIS)

    Kaur, Rajvir; Krishnasamy, Vijayakumar; Muthusamy, Kaleeswari; Chinnamuthan, Periasamy

    2017-01-01

    Highlights: • Proton exchange membrane fuel cell based telecom tower supply is proposed. • The use of diesel generator is eliminated and battery size is reduced. • Boost converter based intelligent interfacing unit is implemented. • The genetic algorithm assisted controller is proposed for effective interfacing. • The controller is robust against input and output disturbance rejection. - Abstract: This paper presents the fuel cell based simple electric energy conversion system for supplying the telecommunication towers to reduce the operation and maintenance cost of telecom companies. The telecom industry is at the boom and is penetrating deep into remote rural areas having unreliable or no grid supply. The telecom industry is getting heavily dependent on a diesel generator set and battery bank as a backup for continuously supplying a base transceiver station of telecom towers. This excessive usage of backup supply resulted in increased operational expenditure, the unreliability of power supply and had become a threat to the environment. A significant development and concern of clean energy sources, proton exchange membrane fuel cell based supply for base transceiver station is proposed with intelligent interfacing unit. The necessity of the battery bank capacity is significantly reduced as compared with the earlier solutions. Further, a simple closed loop and genetic algorithm assisted controller is proposed for intelligent interfacing unit which consists of power electronic boost converter for power conditioning. The proposed genetic algorithm assisted controller would ensure the tight voltage regulation at the DC distribution bus of the base transceiver station. Also, it will provide the robust performance of the base transceiver station under telecom load variation and proton exchange membrane fuel cell output voltage fluctuations. The complete electric energy conversion system along with telecom loads is simulated in MATLAB/Simulink platform and

  1. First-order exchange coefficient coupling for simulating surface water-groundwater interactions: Parameter sensitivity and consistency with a physics-based approach

    Science.gov (United States)

    Ebel, B.A.; Mirus, B.B.; Heppner, C.S.; VanderKwaak, J.E.; Loague, K.

    2009-01-01

    Distributed hydrologic models capable of simulating fully-coupled surface water and groundwater flow are increasingly used to examine problems in the hydrologic sciences. Several techniques are currently available to couple the surface and subsurface; the two most frequently employed approaches are first-order exchange coefficients (a.k.a., the surface conductance method) and enforced continuity of pressure and flux at the surface-subsurface boundary condition. The effort reported here examines the parameter sensitivity of simulated hydrologic response for the first-order exchange coefficients at a well-characterized field site using the fully coupled Integrated Hydrology Model (InHM). This investigation demonstrates that the first-order exchange coefficients can be selected such that the simulated hydrologic response is insensitive to the parameter choice, while simulation time is considerably reduced. Alternatively, the ability to choose a first-order exchange coefficient that intentionally decouples the surface and subsurface facilitates concept-development simulations to examine real-world situations where the surface-subsurface exchange is impaired. While the parameters comprising the first-order exchange coefficient cannot be directly estimated or measured, the insensitivity of the simulated flow system to these parameters (when chosen appropriately) combined with the ability to mimic actual physical processes suggests that the first-order exchange coefficient approach can be consistent with a physics-based framework. Copyright ?? 2009 John Wiley & Sons, Ltd.

  2. Metal/dielectric thermal interfacial transport considering cross-interface electron-phonon coupling: Theory, two-temperature molecular dynamics, and thermal circuit

    Science.gov (United States)

    Lu, Zexi; Wang, Yan; Ruan, Xiulin

    2016-02-01

    The standard two-temperature equations for electron-phonon coupled thermal transport across metal/nonmetal interfaces are modified to include the possible coupling between metal electrons with substrate phonons. The previous two-temperature molecular dynamics (TT-MD) approach is then extended to solve these equations numerically at the atomic scale, and the method is demonstrated using Cu/Si interface as an example. A key parameter in TT-MD is the nonlocal coupling distance of metal electrons and nonmetal phonons, and here we use two different approximations. The first is based on Overhauser's "joint-modes" concept, while we use an interfacial reconstruction region as the length scale of joint region rather than the phonon mean-free path as in Overhauser's original model. In this region, the metal electrons can couple to the joint phonon modes. The second approximation is the "phonon wavelength" concept where electrons couple to phonons nonlocally within the range of one phonon wavelength. Compared with the original TT-MD, including the cross-interface electron-phonon coupling can slightly reduce the total thermal boundary resistance. Whether the electron-phonon coupling within the metal block is nonlocal or not does not make an obvious difference in the heat transfer process. Based on the temperature profiles from TT-MD, we construct a new mixed series-parallel thermal circuit. We show that such a thermal circuit is essential for understanding metal/nonmetal interfacial transport, while calculating a single resistance without solving temperature profiles as done in most previous studies is generally incomplete. As a comparison, the simple series circuit that neglects the cross-interface electron-phonon coupling could overestimate the interfacial resistance, while the simple parallel circuit in the original Overhauser's model underestimates the total interfacial resistance.

  3. Managing the interface - An approach through the complexity of the collaborative process of design, integration and realization: a transactional model of the interface actor and dynamics of exchange spaces

    International Nuclear Information System (INIS)

    Nicquevert, B.

    2012-01-01

    In large projects such as particle accelerators or detectors, interfaces and boundaries reveal themselves to be both critical and underestimated. The technical manager, an actor among others, finds himself placed at network nodes where he must set up exchanges spaces in order to generate collaborative behaviours. Starting with case studies from the field of CERN, the thesis follows three principles based on the dia-logical, the hologramic and the self-eco-organization principles, as expanded in the writings on complexity. It puts forward an original methodological matrix construction leading to a transactional model of the interface actor. The collaborative exchanges spaces builds itself as a place for the dynamic transformation of the interface actor into a boundary actor. Intermediate objects, created during the design / integration process, are simultaneously transformed into boundary objects. They are instrumental in the realization of the product: this takes place in the framework of the project which has been determined through a recursive process. The interest generated by such a global and combined approach of this dynamic process leads to the proposal of a 'hyper-compass', with the aim of providing the means for the technical manager to orient his 'acting ↔ thinking'. (author)

  4. Interlayer exchange coupling in Er|Tb superlattices mediated by short range incommensurate Er order

    International Nuclear Information System (INIS)

    Pfuhl, E; Brueckel, T; Voigt, J; Mattauch, S; Korolkov, D

    2010-01-01

    We study the magnetic correlations in Er|Tb superlattices by means of off-specular scattering of polarized neutrons. We show here the co-existence of inhomogeneous magnetic states: i) ferromagnetic order of moments within the Tb layers below 230 K (FM), correlation length of about 10 bilayer, ii) an incommensurate modulated magnetic order, restricted to single Er layers and iii) antiferromagnetic coupling of ferromagnetic layers below 70K (AFC). Polarised off-specular neutron scattering under grazing incidence reveals that i) magnetic fluctuations appear when the sample is cooled below 70 K, ii) these fluctuations lead to AFC, when the sample is cooled to 10 K, which iii) persists, when the sample is subsequently heated up to 45 K, while the order is not present during the cooling cycle. Also the short range incommensurate order changes accordingly, implying that the magnetic order in the Er layers mediates the interlayer coupling between ferromagnetic Tb layers.

  5. Interface requirements for coupling a containment code to a reactor system thermal hydraulic codes

    International Nuclear Information System (INIS)

    Baratta, A.J.

    1997-01-01

    To perform a complete analysis of a reactor transient, not only the primary system response but the containment response must also be accounted for. Such transients and accidents as a loss of coolant accident in both pressurized water and boiling water reactors and inadvertent operation of safety relief valves all challenge the containment and may influence flows because of containment feedback. More recently, the advanced reactor designs put forth by General Electric and Westinghouse in the US and by Framatome and Seimens in Europe rely on the containment to act as the ultimate heat sink. Techniques used by analysts and engineers to analyze the interaction of the containment and the primary system were usually iterative in nature. Codes such as RELAP or RETRAN were used to analyze the primary system response and CONTAIN or CONTEMPT the containment response. The analysis was performed by first running the system code and representing the containment as a fixed pressure boundary condition. The flows were usually from the primary system to the containment initially and generally under choked conditions. Once the mass flows and timing are determined from the system codes, these conditions were input into the containment code. The resulting pressures and temperatures were then calculated and the containment performance analyzed. The disadvantage of this approach becomes evident when one performs an analysis of a rapid depressurization or a long term accident sequence in which feedback from the containment can occur. For example, in a BWR main steam line break transient, the containment heats up and becomes a source of energy for the primary system. Recent advances in programming and computer technology are available to provide an alternative approach. The author and other researchers have developed linkage codes capable of transferring data between codes at each time step allowing discrete codes to be coupled together

  6. Interface requirements for coupling a containment code to a reactor system thermal hydraulic codes

    Energy Technology Data Exchange (ETDEWEB)

    Baratta, A.J.

    1997-07-01

    To perform a complete analysis of a reactor transient, not only the primary system response but the containment response must also be accounted for. Such transients and accidents as a loss of coolant accident in both pressurized water and boiling water reactors and inadvertent operation of safety relief valves all challenge the containment and may influence flows because of containment feedback. More recently, the advanced reactor designs put forth by General Electric and Westinghouse in the US and by Framatome and Seimens in Europe rely on the containment to act as the ultimate heat sink. Techniques used by analysts and engineers to analyze the interaction of the containment and the primary system were usually iterative in nature. Codes such as RELAP or RETRAN were used to analyze the primary system response and CONTAIN or CONTEMPT the containment response. The analysis was performed by first running the system code and representing the containment as a fixed pressure boundary condition. The flows were usually from the primary system to the containment initially and generally under choked conditions. Once the mass flows and timing are determined from the system codes, these conditions were input into the containment code. The resulting pressures and temperatures were then calculated and the containment performance analyzed. The disadvantage of this approach becomes evident when one performs an analysis of a rapid depressurization or a long term accident sequence in which feedback from the containment can occur. For example, in a BWR main steam line break transient, the containment heats up and becomes a source of energy for the primary system. Recent advances in programming and computer technology are available to provide an alternative approach. The author and other researchers have developed linkage codes capable of transferring data between codes at each time step allowing discrete codes to be coupled together.

  7. Effect of multi-component ions exchange on low salinity EOR: Coupled geochemical simulation study

    Directory of Open Access Journals (Sweden)

    Ehsan Pouryousefy

    2016-09-01

    Upon combining the simulation and experimental results, we concluded that the multi-component ion exchange is not the sole mechanism behind low salinity effect for two reasons. First, almost 10% additional oil recovery was observed from the experiments by injecting the 2000 ppm CaCl2 compared with 50,000 ppm CaCl2 solutions. Even though in both cases the surface is expected to be fully saturated with Ca2+ according to the geochemical modelling. Second, 6% incremental oil recovery was achieved from the experiments by injecting 2000 ppm NaCl solution compared with that of 50,000 ppm NaCl. Although 25% incremental adsorption of divalent cations (Ca2+ were presented during the flooding of the 2000 ppm NaCl solution. Therefore, it is worth noting that the electrical double layer expansion due to the ion exchange needs to be taken into account to pinpoint the mechanism(s of low-salinity water effect.

  8. Sign of the electron exchange coupling in random radical encounter pairs in solution

    International Nuclear Information System (INIS)

    Thurnauer, M.C.; Chiu, T.M.; Trifunac, A.D.

    1985-01-01

    An important parameter in the study of reacting radical systems is the electron exchange interaction, J. The properties of interest are the sign and magnitude of J, and its functional dependence on distance between radicals. One source of information about J is from understanding the Chemically Induced Dynamic Electron Polarization (CIDEP) which is observed in the EPR spectra of reactive radical systems. For radicals reacting in solution to form new covalent bonds, it has generally been found that J O. It is suggested that F-pairs react at a separation greater than that at which spin correlated (geminate) pairs of the same radicals are formed, so that the intervening solvent molecules become involved in the exchange interaction giving rise to J>O via some sort of superexchange process. This is an interesting proposition since superexchange via solvent molecules may play a role in rates of long-distance electron transfer reactions and in the electron transfer reactions of photosynthesis. However, the model suggested runs contrary to all F-air radicals are produced. In order to clarify this important point, the authors present here a definitive study in which we examine several systems of radgenerated independently (exclusive F-pairs) by pulsed laser photolysis and pulsed radiolicals generatedysis in aqueous, alcoholic and hydrocarbon solvents

  9. The πNN coupling from high precision np charge exchange at 162 MeV

    International Nuclear Information System (INIS)

    Nilsson, J.; Blomgren, J.; Conde, H.; Elmgren, K.; Olsson, N.; Ericson, T.E.O.; Uppsala Univ.; Jonsson, O.; Nilsson, L.; Loiseau, B.; Ringbom, A.

    1995-02-01

    Differential cross sections for unpolarized neutrons of 162 MeV have been measured to high precision with particular attention to the absolute normalisation. These data can be extrapolated precisely and model-independently to the pion pole and give a πNN coupling constant g 2 =14.6±0.3 or f 2 =0.0808±0.0017. This is higher than recently suggested values. (author) 24 refs.; 3 figs.; 1 tab

  10. Lateral Variations of Interplate Coupling along the Mexican Subduction Interface: Relationships with Long-Term Morphology and Fault Zone Mechanical Properties

    Science.gov (United States)

    Rousset, Baptiste; Lasserre, Cécile; Cubas, Nadaya; Graham, Shannon; Radiguet, Mathilde; DeMets, Charles; Socquet, Anne; Campillo, Michel; Kostoglodov, Vladimir; Cabral-Cano, Enrique; Cotte, Nathalie; Walpersdorf, Andrea

    2016-10-01

    Although patterns of interseismic strain accumulation above subduction zones are now routinely characterised using geodetic measurements, their physical origin, persistency through time, and relationships to seismic hazard and long-term deformation are still debated. Here, we use GPS and morphological observations from southern Mexico to explore potential mechanical links between variations in inter-SSE (in between slow slip events) coupling along the Mexico subduction zone and the long-term topography of the coastal regions from Guerrero to Oaxaca. Inter-SSE coupling solutions for two different geometries of the subduction interface are derived from an inversion of continuous GPS time series corrected from slow slip events. They reveal strong along-strike variations in the shallow coupling (i.e. at depths down to 25 km), with high-coupling zones (coupling >0.7) alternating with low-coupling zones (coupling 0.7) and transitions to uncoupled, steady slip at a relatively uniform ˜ 175-km inland from the trench. Along-strike variations in the coast-to-trench distances are strongly correlated with the GPS-derived forearc coupling variations. To explore a mechanical explanation for this correlation, we apply Coulomb wedge theory, constrained by local topographic, bathymetric, and subducting-slab slopes. Critical state areas, i.e. areas where the inner subduction wedge deforms, are spatially correlated with transitions at shallow depth between uncoupled and coupled areas of the subduction interface. Two end-member models are considered to explain the correlation between coast-to-trench distances and along-strike variations in the inter-SSE coupling. The first postulates that the inter-SSE elastic strain is partitioned between slip along the subduction interface and homogeneous plastic permanent deformation of the upper plate. In the second, permanent plastic deformation is postulated to depend on frictional transitions along the subduction plate interface. Based on the

  11. Development of volume-reduction system for ion exchange resin using inductively coupled plasma

    International Nuclear Information System (INIS)

    Fujisawa, Morio; Katagiri, Genichi

    2002-01-01

    The spent ion exchange resin generated as radioactive waste in water purifying system at nuclear power stations or related facilities of nuclear power has been stored in the site, and its volume has been increasing year by year. We had developed a full-scale system of IC plasma volume-reduction system for the spent resin, and have performed basic performance test using some samples imitating the spent resin. As the results, the imitation of the resin can be reduced in volume by more than 90% so that the processing performance in actual scale was proved to be effective. In addition, it was clarified that the residuum after volume-reduction process is easy to mix with cement, and solidity containing 30wt% residuum provides high strength of 68 MPa. Therefore, we evaluate the application of this process to stabilization of the disposal to be very effective. (author)

  12. Isovector couplings for nucleon charge-exchange reactions at intermediate energies

    International Nuclear Information System (INIS)

    Love, W.G.; Nakayama, K.; Franey, M.A.

    1987-01-01

    The isovector parts of the effective nucleon-nucleon interaction are studied by examination of the reaction /sup 14/C(p,n) at intermediate energies near zero momentum transfer with use of recently developed G-matrix and free--t-matrix interactions. The spin-independent coupling (V/sub tau/) exhibits a strong energy and density dependence which, in the case of the G matrix based on the Bonn potential, significantly improves the agreement between calculated values of chemical bondV/sub σ//sub tau//V/sub tau/chemical bond 2 at q = 0 and those recently extracted from the reaction /sup 14/C

  13. Statistical properties of the energy exchanged between two heat baths coupled by thermal fluctuations

    DEFF Research Database (Denmark)

    Ciliberto, S.; Imparato, A.; Naert, A.

    2013-01-01

    Brownian particles kept at different temperatures and coupled by an elastic force. We measure the heat flowing between the two reservoirs and the thermodynamic work done by one part of the system on the other. We show that these quantities exhibit a long-time fluctuation theorem. Furthermore, we evaluate...... the fluctuating entropy, which satisfies a conservation law. These experimental results are fully justified by the theoretical analysis. Our results give more insight into the energy transfer in the famous Feynman ratchet, widely studied theoretically but never in an experiment....

  14. A microscopic approach based on particle-vibration coupling: application to charge-exchange transitions and multiplets in odd nuclei

    Directory of Open Access Journals (Sweden)

    Colò Gianluca

    2016-01-01

    Full Text Available In this contribution, we shall describe a formalism that goes beyond the simple time-dependent mean field and is based on particle-vibration coupling (PVC. Such a formalism has been developed with the idea of being self-consistent. It makes use of Skyrme effective forces, and has been used for several applications. We will focus on charge-exchange transitions, namely we will show that our model describes well both the Gamow-Teller giant resonance width, and the low-lying transitions associated with β-decay. In this latter case, including PVC produces a significant improvement of the half-lives obtained at mean-field level, and leads to a good agreement with experimental data. We will end by discussing particle-phonon multiplets in odd nuclei.

  15. Calculation of the exchange coupling constants of copper binuclear systems based on spin-flip constricted variational density functional theory.

    Science.gov (United States)

    Zhekova, Hristina R; Seth, Michael; Ziegler, Tom

    2011-11-14

    We have recently developed a methodology for the calculation of exchange coupling constants J in weakly interacting polynuclear metal clusters. The method is based on unrestricted and restricted second order spin-flip constricted variational density functional theory (SF-CV(2)-DFT) and is here applied to eight binuclear copper systems. Comparison of the SF-CV(2)-DFT results with experiment and with results obtained from other DFT and wave function based methods has been made. Restricted SF-CV(2)-DFT with the BH&HLYP functional yields consistently J values in excellent agreement with experiment. The results acquired from this scheme are comparable in quality to those obtained by accurate multi-reference wave function methodologies such as difference dedicated configuration interaction and the complete active space with second-order perturbation theory. © 2011 American Institute of Physics

  16. The quantum anomalous Hall effect on a star lattice with spin-orbit coupling and an exchange field

    International Nuclear Information System (INIS)

    Chen Mengsu; Wan Shaolong

    2012-01-01

    We study a star lattice with Rashba spin-orbit coupling and an exchange field and find that there is a quantum anomalous Hall effect in this system, and that there are five energy gaps at Dirac points and quadratic band crossing points. We calculate the Berry curvature distribution and obtain the Hall conductivity (Chern number ν) quantized as integers, and find that ν =- 1,2,1,1,2 when the Fermi level lies in these five gaps. Our model can be viewed as a general quantum anomalous Hall system and, in limit cases, can give what the honeycomb lattice and kagome lattice give. We also find that there is a nearly flat band with ν = 1 which may provide an opportunity for realizing the fractional quantum anomalous Hall effect. Finally, the chiral edge states on a zigzag star lattice are given numerically, to confirm the topological property of this system. (paper)

  17. Enhanced magnetic properties in ZnCoAlO caused by exchange-coupling to Co nanoparticles

    International Nuclear Information System (INIS)

    Feng, Qi; Dizayee, Wala; Li, Xiaoli; Score, David S; Neal, James R; Behan, Anthony J; Mokhtari, Abbas; Alshammari, Marzook S; Al-Qahtani, Mohammed S; Blythe, Harry J; Fox, A Mark; Gehring, Gillian A; Chantrell, Roy W; Heald, Steve M; Xu, Xiao-Hong

    2016-01-01

    We report the results of a sequence of magnetisation and magneto-optical studies on laser ablated thin films of ZnCoAlO and ZnCoO that contain a small amount of metallic cobalt. The results are compared to those expected when all the magnetization is due to isolated metallic clusters of cobalt and with an oxide sample that is almost free from metallic inclusions. Using a variety of direct magnetic measurements and also magnetic circular dichroism we find that there is ferromagnetism within both the oxide and the metallic inclusions, and furthermore that these magnetic components are exchange-coupled when aluminium is included. This enhances both the coercive field and the remanence. Hence the presence of a controlled quantity of metallic nanoparticles in ZnAlO can improve the magnetic response of the oxide, thus giving great advantages for applications in spintronics. (paper)

  18. Multi-interface roughness effects on electron mobility in a Ga0.5In0.5P/GaAs multisubband coupled quantum well structure

    International Nuclear Information System (INIS)

    Sahu, Trinath; Shore, K Alan

    2009-01-01

    We analyse the effect of interface roughness scattering on low temperature electron mobility μ n mediated by intersubband interactions in a multisubband coupled Ga 0.5 In 0.5 P/GaAs quantum well structure. We consider a barrier δ-doped double quantum well system in which the subband electron mobility is limited by the interface roughness scattering μ IR n and ionized impurity scattering μ imp n . We analyse the effect of the intersubband interaction and coupling of subband wavefunctions through the barrier on the intrasubband and intersubband transport scattering rates. We show that the intersubband interaction controls the roughness potential of different interfaces through the dielectric screening matrix. In the case of lowest subband occupancy, the mobility is mainly governed by the interface roughness of the central barrier. Whereas when two subbands are occupied, the interface roughness of the outer barrier predominates due to intersubband effects. The influence of the intersubband interaction also exhibits interesting results on the well width up to which the interface roughness dominates in a double quantum well structure

  19. Investigation of the field dependent spin structure of exchange coupled magnetic heterostructures

    International Nuclear Information System (INIS)

    Gurieva, Tatiana

    2016-05-01

    This thesis describes the investigation of the field dependent magnetic spin structure of an antiferromagnetically (AF) coupled Fe/Cr heterostructure sandwiched between a hardmagnetic FePt buffer layer and a softmagnetic Fe top layer. The depth-resolved experimental studies of this system were performed via Magneto-optical Kerr effect (MOKE), Vibrating Sample Magnetometry (VSM) and various measuring methods based on nuclear resonant scattering (NRS) technique. Nucleation and evolution of the magnetic spiral structure in the AF coupled Fe/Cr multilayer structure in an azimuthally rotating external magnetic field were observed using NRS. During the experiment a number of time-dependent magnetic side effects (magnetic after-effect, domain-wall creep effect) caused by the non-ideal structure of a real sample were observed and later explained. Creation of the magnetic spiral structure in rotating external magnetic field was simulated using a one-dimensional micromagnetic model.The cross-sectional magnetic X-ray diffraction technique was conceived and is theoretically described in the present work. This method allows to determine the magnetization state of an individual layer in the magnetic heterostructure. It is also applicable in studies of the magnetic structure of tiny samples where conventional x-ray reflectometry fails.

  20. Quantification of exploitable shallow geothermal energy by using Borehole Heat Exchanger coupled Ground Source Heat Pump systems

    International Nuclear Information System (INIS)

    Hein, Philipp; Zhu, Ke; Bucher, Anke; Kolditz, Olaf; Pang, Zhonghe; Shao, Haibing

    2016-01-01

    Highlights: • The amount of technically exploitable shallow geothermal energy was quantified. • Therefore, a comprehensive numerical borehole heat exchanger model was employed. • The concept of equivalent temperature drop is introduced. • For one BHE, an equivalent temperature drop of 1.8–2.8 °C over 30 years is realistic • The average extractable energy amount evaluates to be 3.5–5.4 kW h m"−"2 a"−"1. - Abstract: In previous studies, the amount of exploitable shallow geothermal energy was estimated by assuming a uniform temperature drop of 2–6 °C in the aquifer. In this work, a more comprehensive numerical model has been employed to evaluate the available amount of shallow geothermal energy by using Borehole Heat Exchanger coupled Ground Source Heat Pump systems. Numerical experiments have been performed by simulating the long-term evolution of the subsurface temperature field, which is subject to the operation of borehole heat exchangers and varying parameters like subsurface thermal conductivity and groundwater flow velocity. The concept of equivalent temperature drop is proposed as an auxiliary quantity for the subsurface. With the help of this parameter, a procedure has been established to quantify the amount of shallow geothermal potential. Following this approach, a realistic equivalent temperature reduction is found to be from −1.8 to −4.4 °C in the subsurface over a period of 30 years. This can be translated to an annual extractable geothermal energy value in a unit surface area, and it ranges from 3.5 to 8.6 kW h m"−"2 a"−"1. The exact value is site specific and heavily depends on the soil thermal conductivity, groundwater velocity, and borehole arrangement.

  1. Improved charge-coupled device detectors for high-speed, charge exchange spectroscopy studies on the DIII-D tokamak

    International Nuclear Information System (INIS)

    Burrell, K.H.; Gohil, P.; Groebner, R.J.; Kaplan, D.H.; Robinson, J.I.; Solomon, W.M.

    2004-01-01

    Charge exchange spectroscopy is one of the key ion diagnostics on the DIII-D tokamak. It allows determination of ion temperature, poloidal and toroidal velocity, impurity density, and radial electric field E r throughout the plasma. For the 2003 experimental campaign, we replaced the intensified photodiode array detectors on the central portion of the DIII-D charge exchange spectroscopy system with advanced charge-coupled device (CCD) detectors mounted on faster (f/4.7) Czerny-Turner spectrometers equipped with toroidal mirrors. The CCD detectors are improved versions of the ones installed on our edge system in 1999. The combination improved the photoelectron signal level by about a factor of 20 and the signal to noise by a factor of 2-8, depending on the absolute signal level. The new cameras also allow shorter minimum integration times while archiving to PC memory: 0.552 ms for the slower, lower-read noise (15 e) readout mode and 0.274 ms in the faster, higher-read noise (30 e) mode

  2. Simulating carbon exchange using a regional atmospheric model coupled to an advanced land-surface model

    International Nuclear Information System (INIS)

    Ter Maat, H.W.; Hutjes, R.W.A.; Miglietta, F.; Gioli, B.; Bosveld, F.C.; Vermeulen, A.T.; Fritsch, H.

    2010-08-01

    This paper is a case study to investigate what the main controlling factors are that determine atmospheric carbon dioxide content for a region in the centre of The Netherlands. We use the Regional Atmospheric Modelling System (RAMS), coupled with a land surface scheme simulating carbon, heat and momentum fluxes (SWAPS-C), and including also submodels for urban and marine fluxes, which in principle should include the dominant mechanisms and should be able to capture the relevant dynamics of the system. To validate the model, observations are used that were taken during an intensive observational campaign in central Netherlands in summer 2002. These include flux-tower observations and aircraft observations of vertical profiles and spatial fluxes of various variables.

  3. A novel cogeneration system: A proton exchange membrane fuel cell coupled to a heat transformer

    International Nuclear Information System (INIS)

    Huicochea, A.; Romero, R.J.; Rivera, W.; Gutierrez-Urueta, G.; Siqueiros, J.; Pilatowsky, I.

    2013-01-01

    This study focuses on the potential of a novel cogeneration system which consists of a 5 kW proton exchange membrane fuel cell (PEMFC) and an absorption heat transformer (AHT). The dissipation heat resulting from the operation of the PEMFC would be used to feed the absorption heat transformer, which is integrated to a water purification system. Therefore, the products of the proposed cogeneration system are heat, electricity and distilled water. The study includes a simulation for the PEMFC as well as experimental results obtained with an experimental AHT facility. Based on the simulation results, experimental tests were performed in order to estimate the performance parameters of the overall system. This is possible due to the matching in power and temperatures between the outlet conditions of the simulated fuel cell and the inlet requirements of the AHT. Experimental coefficients of performance are reported for the AHT as well as the overall cogeneration efficiency for the integrated system. The results show that experimental values of coefficient of performance of the AHT and the overall cogeneration efficiency, can reach up to 0.256 and 0.571, respectively. This represents an increment in 12.4% of efficiency, compared to the fuel cell efficiency working individually. This study shows that the combined use of AHT systems with a PEMFC is possible and it is a very feasible project to be developed in the Centro de Investigación en Energía (Centre of Energy Research), México.

  4. Simulating carbon exchange using a regional atmospheric model coupled to an advanced land-surface model

    Directory of Open Access Journals (Sweden)

    H. W. Ter Maat

    2010-08-01

    Full Text Available This paper is a case study to investigate what the main controlling factors are that determine atmospheric carbon dioxide content for a region in the centre of The Netherlands. We use the Regional Atmospheric Modelling System (RAMS, coupled with a land surface scheme simulating carbon, heat and momentum fluxes (SWAPS-C, and including also submodels for urban and marine fluxes, which in principle should include the dominant mechanisms and should be able to capture the relevant dynamics of the system. To validate the model, observations are used that were taken during an intensive observational campaign in central Netherlands in summer 2002. These include flux-tower observations and aircraft observations of vertical profiles and spatial fluxes of various variables.

    The simulations performed with the coupled regional model (RAMS-SWAPS-C are in good qualitative agreement with the observations. The station validation of the model demonstrates that the incoming shortwave radiation and surface fluxes of water and CO2 are well simulated. The comparison against aircraft data shows that the regional meteorology (i.e. wind, temperature is captured well by the model. Comparing spatially explicitly simulated fluxes with aircraft observed fluxes we conclude that in general latent heat fluxes are underestimated by the model compared to the observations but that the latter exhibit large variability within all flights. Sensitivity experiments demonstrate the relevance of the urban emissions of carbon dioxide for the carbon balance in this particular region. The same tests also show the relation between uncertainties in surface fluxes and those in atmospheric concentrations.

  5. Molecular couplings and energy exchange between DNA and water mapped by femtosecond infrared spectroscopy of backbone vibrations

    Directory of Open Access Journals (Sweden)

    Yingliang Liu

    2017-07-01

    Full Text Available Molecular couplings between DNA and water together with the accompanying processes of energy exchange are mapped via the ultrafast response of DNA backbone vibrations after OH stretch excitation of the water shell. Native salmon testes DNA is studied in femtosecond pump-probe experiments under conditions of full hydration and at a reduced hydration level with two water layers around the double helix. Independent of their local hydration patterns, all backbone vibrations in the frequency range from 940 to 1120 cm–1 display a quasi-instantaneous reshaping of the spectral envelopes of their fundamental absorption bands upon excitation of the water shell. The subsequent reshaping kinetics encompass a one-picosecond component, reflecting the formation of a hot ground state of the water shell, and a slower contribution on a time scale of tens of picoseconds. Such results are benchmarked by measurements with resonant excitation of the backbone modes, resulting in distinctly different absorption changes. We assign the fast changes of DNA absorption after OH stretch excitation to structural changes in the water shell which couple to DNA through the local electric fields. The second slower process is attributed to a flow of excess energy from the water shell into DNA, establishing a common heated ground state in the molecular ensemble. This interpretation is supported by theoretical calculations of the electric fields exerted by the water shell at different temperatures.

  6. Heat and fuel coupled operation of a high temperature polymer electrolyte fuel cell with a heat exchanger methanol steam reformer

    Science.gov (United States)

    Schuller, G.; Vázquez, F. Vidal; Waiblinger, W.; Auvinen, S.; Ribeirinha, P.

    2017-04-01

    In this work a methanol steam reforming (MSR) reactor has been operated thermally coupled to a high temperature polymer electrolyte fuel cell stack (HT-PEMFC) utilizing its waste heat. The operating temperature of the coupled system was 180 °C which is significantly lower than the conventional operating temperature of the MSR process which is around 250 °C. A newly designed heat exchanger reformer has been developed by VTT (Technical Research Center of Finland LTD) and was equipped with commercially available CuO/ZnO/Al2O3 (BASF RP-60) catalyst. The liquid cooled, 165 cm2, 12-cell stack used for the measurements was supplied by Serenergy A/S. The off-heat from the electrochemical fuel cell reaction was transferred to the reforming reactor using triethylene glycol (TEG) as heat transfer fluid. The system was operated up to 0.4 A cm-2 generating an electrical power output of 427 Wel. A total stack waste heat utilization of 86.4% was achieved. It has been shown that it is possible to transfer sufficient heat from the fuel cell stack to the liquid circuit in order to provide the needed amount for vaporizing and reforming of the methanol-water-mixture. Furthermore a set of recommendations is given for future system design considerations.

  7. Self-Powered Random Number Generator Based on Coupled Triboelectric and Electrostatic Induction Effects at the Liquid-Dielectric Interface.

    Science.gov (United States)

    Yu, Aifang; Chen, Xiangyu; Cui, Haotian; Chen, Libo; Luo, Jianjun; Tang, Wei; Peng, Mingzeng; Zhang, Yang; Zhai, Junyi; Wang, Zhong Lin

    2016-12-27

    Modern cryptography increasingly employs random numbers generated from physical sources in lieu of conventional software-based pseudorandom numbers, primarily owing to the great demand of unpredictable, indecipherable cryptographic keys from true random numbers for information security. Thus, far, the sole demonstration of true random numbers has been generated through thermal noise and/or quantum effects, which suffers from expensive and complex equipment. In this paper, we demonstrate a method for self-powered creation of true random numbers by using triboelectric technology to collect random signals from nature. This random number generator based on coupled triboelectric and electrostatic induction effects at the liquid-dielectric interface includes an elaborately designed triboelectric generator (TENG) with an irregular grating structure, an electronic-optical device, and an optical-electronic device. The random characteristics of raindrops are harvested through TENG and consequently transformed and converted by electronic-optical device and an optical-electronic device with a nonlinear characteristic. The cooperation of the mechanical, electrical, and optical signals ensures that the generator possesses complex nonlinear input-output behavior and contributes to increased randomness. The random number sequences are deduced from final electrical signals received by an optical-electronic device using a familiar algorithm. These obtained random number sequences exhibit good statistical characteristics, unpredictability, and unrepeatability. Our study supplies a simple, practical, and effective method to generate true random numbers, which can be widely used in cryptographic protocols, digital signatures, authentication, identification, and other information security fields.

  8. Motor Imagery-Based Brain-Computer Interface Coupled to a Robotic Hand Orthosis Aimed for Neurorehabilitation of Stroke Patients

    Directory of Open Access Journals (Sweden)

    Jessica Cantillo-Negrete

    2018-01-01

    Full Text Available Motor imagery-based brain-computer interfaces (BCI have shown potential for the rehabilitation of stroke patients; however, low performance has restricted their application in clinical environments. Therefore, this work presents the implementation of a BCI system, coupled to a robotic hand orthosis and driven by hand motor imagery of healthy subjects and the paralysed hand of stroke patients. A novel processing stage was designed using a bank of temporal filters, the common spatial pattern algorithm for feature extraction and particle swarm optimisation for feature selection. Offline tests were performed for testing the proposed processing stage, and results were compared with those computed with common spatial patterns. Afterwards, online tests with healthy subjects were performed in which the orthosis was activated by the system. Stroke patients’ average performance was 74.1 ± 11%. For 4 out of 6 patients, the proposed method showed a statistically significant higher performance than the common spatial pattern method. Healthy subjects’ average offline and online performances were of 76.2 ± 7.6% and 70 ± 6.7, respectively. For 3 out of 8 healthy subjects, the proposed method showed a statistically significant higher performance than the common spatial pattern method. System’s performance showed that it has a potential to be used for hand rehabilitation of stroke patients.

  9. Critical evaluation of a new passive exchange-meter for assessing multimedia fate of persistent organic pollutants at the air-soil interface

    International Nuclear Information System (INIS)

    Liu, Xiang; Ming, Li-Li; Nizzetto, Luca; Borgå, Katrine; Larssen, Thorjørn; Zheng, Qian; Li, Jun; Zhang, Gan

    2013-01-01

    A new passive exchange meter (PEM) to measure inter-compartment fluxes of persistent organic pollutants (POPs) at the interface between soil and the atmosphere is described. The PEM uses labeled reference compounds (RC) added in-situ to vegetation litter deployed in open cylinders designed to trap the vertical downward export of the RCs while allowing free exchange of POPs between litter and air. Fluxes of native compounds (bulk deposition, volatilization and downward export) are quantitatively tracked. One scope of the PEM is to investigate the influence of biogeochemical controls on contaminant re-mobilization. The PEM performance was tested in a subtropical forest by comparing measurements under dense canopy and in a canopy gap; conditions in which deposition and turn-over of organic matter (OM) occur at different rates. Significant differences in fate processes were successfully detected. Surprisingly, mobilization by leaching of more hydrophobic compounds was higher under canopy, possibly as a result of canopy mediated enhancement of OM degradation. -- Highlights: •A new tool for measuring multimedia exchange fluxes of POPs is described. •Deposition, volatilization and leaching, to and from soil surface are targeted. •Precision was sufficient to resolve fluxes differing by less than a factor of 2–5. •Gaps in forest canopy enhanced volatilization of POPs. •Higher leaching of heavier POPs from the litter in the understory is associated to rapid organic matter degradation. -- Time integrated multimedia exchange of POPs in vegetation litter is resolved under dynamic conditions of OM ageing

  10. Sensitivity of land-atmosphere exchanges to overshooting PBL thermals in an idealized coupled model

    Directory of Open Access Journals (Sweden)

    Ian T. Baker

    2009-11-01

    Full Text Available The response of atmospheric carbon dioxide to a given amount of surface flux is inversely proportional to the depth of the planetary boundary layer (PBL. Overshooting thermals that entrain free tropospheric air down into the boundary layer modify the characteristics and depth of the mixed layer through the insertion of energy and mass. In addition, entrainment "dilutes" the effects of surface fluxes on scalar quantities (temperature, water vapor, carbon dioxide, etc. in the PBL. Therefore, incorrect simulation of PBL depth can lead to linear errors in estimates of carbon dioxide fluxes in inverse models. Dilution by entrainment directly alters the surface-air gradients in scalar properties, which serve as the "driving force" for surface fluxes. In addition, changes in near-surface temperature and water vapor affect surface fluxes through physiological processes in plant canopies (e.g. stomatal conductance. Although overshooting thermals are important in the physical world, their effects are unresolved in most regional models. We explore the sensitivity of surface fluxes and PBL scalars to the intensity of PBL top entrainment by manipulating its strength in an idealized version of the coupled SiB-RAMS model. An entrainment parameterization based on the virtual potential temperature flux at the surface is implemented into SiB-RAMS to produce a warmer and drier mixed layer, to alter the surface fluxes, and to increase the depth of the PBL. These variations produce modified CO2 concentrations and vary with the strength of the parameterized entrainment.

  11. Liquid chromatography-mass spectrometry coupling by the intermediary of a liquid micro chromatography-electro spray interface; Couplage chromatographie liquide-spectrometrie de masse par l`intermediaire d`une interface electrospray-microchromatographie liquide

    Energy Technology Data Exchange (ETDEWEB)

    Gillard Factor, C

    1996-12-06

    The objective of this work is to realize a liquid chromatography- mass spectrometry coupling by the intermediary of an electro spray interface and the evaluation of performances of tis analytical tool to study pollutants in water, and more particularly pesticides whom maximum admissible concentration in a table water is 0.1{mu}g/l. This study has allowed to bring to the fore the interest of the ionization mode by electro spray in a LC/MS coupling to identify and quantify pesticides in the state of traces without treating the sample. Then, it was demonstrated the usefulness of this analytical tool to detect high molecular masses molecules. (N.C.)

  12. Separation of gold, palladium and platinum in chromite by anion exchange chromatography for inductively coupled plasma atomic emission spectrometric analysis

    International Nuclear Information System (INIS)

    Choi, Kwang Soon; Lee, Chang Heon; Park, Yeong Jae; Joe, Kih Soo; Kim, Won Ho

    2001-01-01

    A study has been carried out on the separation of gold, iridium, palladium, rhodium, ruthenium and platinum in chromite samples and their quantitative determination using inductively coupled plasma atomic emission spectrometry (ICP-AES). The dissolution condition of the minerals by fusion with sodium peroxide was optimized and chromatographic elution behavior of the rare metals was investigated by anion exchange chromatography. Spectral interference of chromium, a matrix of the minerals, was investigated on determination of gold. Chromium interfered on determination of gold at the concentration of 500 mg/L and higher. Gold plus trace amounts of iridium, palladium, rhodium and ruthenium, which must be preconcentrated before ICP-AES was separated by anion exchange chromatography after reducing Cr(VI) to Cr(III) by H 2 O 2 . AuCl - 4 retained on the resin column was selectively eluted with acetone- HNO 3 -H 2 O as an eluent. In addition, iridium, palladium, rhodium and ruthenium remaining on the resin column were eluted as a group with concentrated HCl. However, platinum was eluted with concentrated HNO 3 . The recovery yield of gold with acetone-HNO 3 -H 2 O was 100.7 ± 2.0 % , and the yields of palladium and platinum with concentrated HCl and HNO 3 were 96.1 ± 1.8% and 96.6 ± 1.3%, respectively. The contents of gold and platinum in a Mongolian chromite sample were 32.6 ± 2.2 μg/g and 1.6 ± 0.14 μg/g, respectively. Palladium was not detected

  13. Simultaneous determination of 13 carbohydrates using high-performance anion-exchange chromatography coupled with pulsed amperometric detection and mass spectrometry.

    Science.gov (United States)

    Zhao, Dan; Feng, Feng; Yuan, Fei; Su, Jin; Cheng, Yan; Wu, Hanqiu; Song, Kun; Nie, Bo; Yu, Lian; Zhang, Feng

    2017-04-01

    A simple, accurate, and highly sensitive method was developed for the determination of 13 carbohydrates in polysaccharide of Spirulina platensis based on high-performance anion-exchange chromatography coupled with pulsed amperometric detection and mass spectrometry. Samples were extracted with deionized water using ultrasonic-assisted extraction, and the ultrasound-assisted extraction conditions were optimized by Box-Behnken design. Then the extracted polysaccharide was hydrolyzed by adding 1 mol/L trifluoroacetic acid before determination by high-performance anion-exchange chromatography coupled with pulsed amperometric detection and confirmed by high-performance anion-exchange chromatography coupled with mass spectrometry. The high-performance anion-exchange chromatography coupled with pulsed amperometric detection method was performed on a CarboPac PA20 column by gradient elution using deionized water, 0.1 mol/L sodium hydroxide solution, and 0.4 mol/L sodium acetate solution. Excellent linearity was observed in the range of 0.05-10 mg/L. The average recoveries ranged from 80.7 to 121.7%. The limits of detection and limits of quantification for 13 carbohydrates were 0.02-0.10 and 0.2-1.2  μg/kg, respectively. The developed method has been successfully applied to ambient samples, and the results indicated that high-performance anion-exchange chromatography coupled with pulsed amperometric detection and mass spectrometry could provide a rapid and accurate method for the simultaneous determination of carbohydrates. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Couplings

    Science.gov (United States)

    Stošić, Dušan; Auroux, Aline

    Basic principles of calorimetry coupled with other techniques are introduced. These methods are used in heterogeneous catalysis for characterization of acidic, basic and red-ox properties of solid catalysts. Estimation of these features is achieved by monitoring the interaction of various probe molecules with the surface of such materials. Overview of gas phase, as well as liquid phase techniques is given. Special attention is devoted to coupled calorimetry-volumetry method. Furthermore, the influence of different experimental parameters on the results of these techniques is discussed, since it is known that they can significantly influence the evaluation of catalytic properties of investigated materials.

  15. Use of an Open Port Sampling Interface Coupled to Electrospray Ionization for the On-Line Analysis of Organic Aerosol Particles

    Science.gov (United States)

    Swanson, Kenneth D.; Worth, Anne L.; Glish, Gary L.

    2018-02-01

    A simple design for an open port sampling interface coupled to electrospray ionization (OPSI-ESI) is presented for the analysis of organic aerosols. The design uses minimal modifications to a Bruker electrospray (ESI) emitter to create a continuous flow, self-aspirating open port sampling interface. Considerations are presented for introducing aerosol to the open port sampling interface including aerosol gas flow and solvent flow rates. The device has been demonstrated for use with an aerosol of nicotine as well as aerosol formed in the pyrolysis of biomass. Upon comparison with extractive electrospray ionization (EESI), this device has similar sensitivity with increased reproducibility by nearly a factor of three. The device has the form factor of a standard Bruker/Agilent ESI emitter and can be used without any further instrument modifications.

  16. Energy and exergy analysis of a ground-coupled heat pump system with two horizontal ground heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Esen, Hikmet; Esen, Mehmet [Department of Mechanical Education, Faculty of Technical Education, Firat University, 23119 Elazig (Turkey); Inalli, Mustafa; Pihtili, Kazim [Department of Mechanical Engineering, Faculty of Engineering, Firat University, 23119 Elazig (Turkey)

    2007-10-15

    In this paper we investigate of energetic and exergetic efficiencies of ground-coupled heat pump (GCHP) system as a function of depth trenches for heating season. The horizontal ground heat exchangers (HGHEs) were used and it were buried with in 1 m (HGHE1) and 2 m (HGHE2) depth trenches. The energy efficiency of GCHP systems are obtained to 2.5 and 2.8, respectively, while the exergetic efficiencies of the overall system are found to be 53.1% and 56.3%, respectively, for HGHE1 and HGHE2. The irreversibility of HGHE2 is less than of the HGHE1 as about 2.0%. The results show that the energetic and exergetic efficiencies of the system increase when increasing the heat source (ground) temperature for heating season. And the end of this study, we deal with the effects of varying reference environment temperature on the exergy efficiencies of HGHE1 and HGHE2. The results show that increasing reference environment temperature decreases the exergy efficiency in both HGHE1 and HGHE2. (author)

  17. A fast charge coupled device detector for charge exchange recombination spectroscopy on the DIII-D Tokamak

    International Nuclear Information System (INIS)

    Thomas, D.M.; Burrell, K.H.; Groebner, R.J.; Gohil, P.; Kaplan, D.; Makariou, C.; Seraydarian, R.P.

    1997-01-01

    Charge exchange recombination (CER) spectroscopy has become a standard diagnostic for Tokamaks. CER measurements have been used to determine spatially and temporally resolved ion temperature, toroidal and poloidal ion rotation speed, impurity density, and radial electric field. Knowledge of the spatial profile and temporal evolution of the electric field shear in the plasma edge is crucial to understanding the physics of the L to H transition. High speed CER measurements are also valuable for edge localized mode studies. Since the 0.52 ms minimum time resolution of our present system is barely adequate to study the time evolution of these phenomena, we have developed a new charge coupled device (CCD) detector system with about a factor of 2 better time resolution. In addition, our existing system detects sufficient photons to utilize the shortest time resolution only under exceptional conditions. The new CCD detector has a quantum efficiency of about 0.65, which is a factor of 7 better than our previous image intensifier-silicon photodiode detector systems. We have also equipped the new system with spectrometers of lower f/number. This combination should allow more routine operation at the minimum integration time, as well as improving data quality for measurements in the divertor-relevant region outside of the separatrix. Construction details, benchmark data, and initial Tokamak measurements for the new system will be presented. copyright 1997 American Institute of Physics

  18. Evaluation of a commercial electro-kinetically pumped sheath-flow nanospray interface coupled to an automated capillary zone electrophoresis system.

    Science.gov (United States)

    Peuchen, Elizabeth H; Zhu, Guije; Sun, Liangliang; Dovichi, Norman J

    2017-03-01

    Capillary zone electrophoresis-electrospray ionization-mass spectrometry (CZE-ESI-MS) is attracting renewed attention for proteomic and metabolomic analysis. An important reason for this interest is the maturation and commercialization of interfaces for coupling CZE with ESI-MS. One of these interfaces is an electro-kinetically pumped sheath flow nanospray interface developed by the Dovichi group, in which a very low sheath flow is generated based on electroosmosis within a glass emitter. CMP Scientific has commercialized this interface as the EMASS-II ion source. In this work, we compared the performance of the EMASS-II ion source with our in-house system. The performance of the systems is equivalent. We also coupled the EMASS-II ion source with a PrinCE Next|480 capillary electrophoresis autosampler and an Orbitrap mass spectrometer, and analyzed this system's performance in terms of sensitivity, reproducibility, and separation performance for separation of tryptic digests, intact proteins, and amino acids. The system produced reproducible analysis of BSA digest; the RSDs of peptide intensity and migration time across 24 runs were less than 20 and 6%, respectively. The system produced a linear calibration curve of intensity across a 30-fold range of tryptic digest concentration. The combination of a commercial autosampler and electrospray interface efficiently separated amino acids, peptides, and intact proteins, and only required 5 μL of sample for analysis. Graphical Abstract The commercial and locally constructed versions of the interface provide similar numbers of protein identifications from a Xenopus laevis fertilized egg digest.

  19. Coherent interface structures and intergrain Josephson coupling in dense MgO/Mg{sub 2}Si/MgB{sub 2} nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Ueno, Katsuya; Takahashi, Kazuyuki; Uchino, Takashi, E-mail: uchino@kobe-u.ac.jp [Department of Chemistry, Graduate School of Science, Kobe University, Nada, Kobe 657-8501 (Japan); Nagashima, Yukihito [Nippon Sheet Glass Co., Ltd., Konoike, Itami 664-8520 (Japan); Seto, Yusuke [Department of Planetology, Graduate School of Science, Kobe University, Nada, Kobe 657-8501 (Japan); Matsumoto, Megumi; Sakurai, Takahiro [Center for Support to Research and Education Activities, Kobe University, Nada, Kobe 657-8501 (Japan); Ohta, Hitoshi [Molecular Photoscience Research Center, Kobe University, Nada, Kobe 657-8501 (Japan)

    2016-07-07

    Many efforts are under way to control the structure of heterointerfaces in nanostructured composite materials for designing functionality and engineering application. However, the fabrication of high-quality heterointerfaces is challenging because the crystal/crystal interface is usually the most defective part of the nanocomposite materials. In this work, we show that fully dense insulator (MgO)/semiconductor(Mg{sub 2}Si)/superconductor(MgB{sub 2}) nanocomposites with atomically smooth and continuous interfaces, including epitaxial-like MgO/Mg{sub 2}Si interfaces, are obtained by solid phase reaction between metallic magnesium and a borosilicate glass. The resulting nanocomposites exhibit a semiconductor-superconducting transition at 36 K owing to the MgB{sub 2} nanograins surrounded by the MgO/Mg{sub 2}Si matrix. This transition is followed by the intergrain phase-lock transition at ∼24 K due to the construction of Josephson-coupled network, eventually leading to a near-zero resistance state at 17 K. The method not only provides a simple process to fabricate dense nanocomposites with high-quality interfaces, but also enables to investigate the electric and magnetic properties of embedded superconducting nanograins with good intergrain coupling.

  20. Magnetoelectric coupling and spin-dependent tunneling in Fe/PbTiO3/Fe multiferroic heterostructure with a Ni monolayer inserted at one interface

    International Nuclear Information System (INIS)

    Dai, Jian-Qing; Zhang, Hu; Song, Yu-Min

    2015-01-01

    We report on first-principles calculations of a Ni monolayer inserted at one interface in the epitaxial Fe/PbTiO 3 /Fe multiferroic heterostructure, focusing on the magnetoelectric coupling and the spin-dependent transport properties. The results of magnetoelectric coupling calculations reveal an attractive approach to realize cumulative magnetoelectric effects in the ferromagnetic/ferroelectric/ferromagnetic superlattices. The underlying physics is attributed to the combinations of several different magnetoelectric coupling mechanisms such as interface bonding, spin-dependent screening, and different types of magnetic interactions. We also demonstrate that inserting a Ni monolayer at one interface in the Fe/PbTiO 3 /Fe multiferroic tunnel junction is an efficient method to produce considerable tunneling electroresistance effect by modifying the tunnel potential barrier and the interfacial electronic structure. Furthermore, coexistence of tunneling magnetoresistance and tunneling electroresistance leads to the emergence of four distinct resistance states, which can be served as a multistate-storage device. The complicated influencing factors including bulk properties of the ferromagnetic electrodes, decay rates of the evanescent states in the tunnel barrier, and the specific interfacial electronic structure provide us promising opportunities to design novel multiferroic tunnel junctions with excellent performances

  1. Magnetoelectric coupling and spin-dependent tunneling in Fe/PbTiO{sub 3}/Fe multiferroic heterostructure with a Ni monolayer inserted at one interface

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Jian-Qing, E-mail: djqkust@sina.com; Zhang, Hu; Song, Yu-Min [School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093 (China)

    2015-08-07

    We report on first-principles calculations of a Ni monolayer inserted at one interface in the epitaxial Fe/PbTiO{sub 3}/Fe multiferroic heterostructure, focusing on the magnetoelectric coupling and the spin-dependent transport properties. The results of magnetoelectric coupling calculations reveal an attractive approach to realize cumulative magnetoelectric effects in the ferromagnetic/ferroelectric/ferromagnetic superlattices. The underlying physics is attributed to the combinations of several different magnetoelectric coupling mechanisms such as interface bonding, spin-dependent screening, and different types of magnetic interactions. We also demonstrate that inserting a Ni monolayer at one interface in the Fe/PbTiO{sub 3}/Fe multiferroic tunnel junction is an efficient method to produce considerable tunneling electroresistance effect by modifying the tunnel potential barrier and the interfacial electronic structure. Furthermore, coexistence of tunneling magnetoresistance and tunneling electroresistance leads to the emergence of four distinct resistance states, which can be served as a multistate-storage device. The complicated influencing factors including bulk properties of the ferromagnetic electrodes, decay rates of the evanescent states in the tunnel barrier, and the specific interfacial electronic structure provide us promising opportunities to design novel multiferroic tunnel junctions with excellent performances.

  2. The role of the interface on the magnetic behaviour of granular Fe50Ag50 film

    International Nuclear Information System (INIS)

    Fdez-Gubieda, M.L.; Sarmiento, G.; Fernandez Barquin, L.; Orue, I.

    2007-01-01

    The magnetic behaviour of a Fe 50 Ag 50 granular thin film has been studied by means of AC and DC magnetic measurements. Exchange coupling between magnetic nanoparticles appears at T=<200K decreasing the coercive field of the sample. Additionally, an exchange bias is observed at low temperature related to the existence of a spin disordered interface around the nanoparticles

  3. [Summer Greenhouse Gases Exchange Flux Across Water-air Interface in Three Water Reservoirs Located in Different Geologic Setting in Guangxi, China].

    Science.gov (United States)

    Li, Jian-hong; Pu, Jun-bing; Sun, Ping-an; Yuan, Dao-xian; Liu, Wen; Zhang, Tao; Mo, Xue

    2015-11-01

    Due to special hydrogeochemical characteristics of calcium-rich, alkaline and DIC-rich ( dissolved inorganic carbon) environment controlled by the weathering products from carbonate rock, the exchange characteristics, processes and controlling factors of greenhouse gas (CO2 and CH4) across water-air interface in karst water reservoir show obvious differences from those of non-karst water reservoir. Three water reservoirs (Dalongdong reservoir-karst reservoir, Wulixia reservoir--semi karst reservoir, Si'anjiang reservoir-non-karst reservoir) located in different geologic setting in Guangxi Zhuang Autonomous Region, China were chosen to reveal characteristics and controlling factors of greenhouse gas exchange flux across water-air interface. Two common approaches, floating chamber (FC) and thin boundary layer models (TBL), were employed to research and contrast greenhouse gas exchange flux across water-air interface from three reservoirs. The results showed that: (1) surface-layer water in reservoir area and discharging water under dam in Dalongdong water reservoir were the source of atmospheric CO2 and CH4. Surface-layer water in reservoir area in Wulixia water reservoir was the sink of atmospheric CO2 and the source of atmospheric CH4, while discharging water under dam was the source of atmospheric CO2 and CH4. Surface-layer water in Si'anjiang water reservoir was the sink of atmospheric CO2 and source of atmospheric CH4. (2) CO2 and CH4 effluxes in discharging water under dam were much more than those in surface-layer water in reservoir area regardless of karst reservoir or non karst reservoir. Accordingly, more attention should be paid to the CO2 and CH4 emission from discharging water under dam. (3) In the absence of submerged soil organic matters and plants, the difference of CH4 effluxes between karst groundwater-fed reservoir ( Dalongdong water reservoir) and non-karst area ( Wulixia water reservoir and Si'anjiang water reservoir) was less. However, CO2

  4. Relativistic four-component calculations of indirect nuclear spin-spin couplings with efficient evaluation of the exchange-correlation response kernel

    Energy Technology Data Exchange (ETDEWEB)

    Křístková, Anežka; Malkin, Vladimir G. [Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84536 Bratislava (Slovakia); Komorovsky, Stanislav; Repisky, Michal [Centre for Theoretical and Computational Chemistry, University of Tromsø - The Arctic University of Norway, N-9037 Tromsø (Norway); Malkina, Olga L., E-mail: olga.malkin@savba.sk [Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84536 Bratislava (Slovakia); Department of Inorganic Chemistry, Comenius University, Bratislava (Slovakia)

    2015-03-21

    In this work, we report on the development and implementation of a new scheme for efficient calculation of indirect nuclear spin-spin couplings in the framework of four-component matrix Dirac-Kohn-Sham approach termed matrix Dirac-Kohn-Sham restricted magnetic balance resolution of identity for J and K, which takes advantage of the previous restricted magnetic balance formalism and the density fitting approach for the rapid evaluation of density functional theory exchange-correlation response kernels. The new approach is aimed to speedup the bottleneck in the solution of the coupled perturbed equations: evaluation of the matrix elements of the kernel of the exchange-correlation potential. The performance of the new scheme has been tested on a representative set of indirect nuclear spin-spin couplings. The obtained results have been compared with the corresponding results of the reference method with traditional evaluation of the exchange-correlation kernel, i.e., without employing the fitted electron densities. Overall good agreement between both methods was observed, though the new approach tends to give values by about 4%-5% higher than the reference method. On the average, the solution of the coupled perturbed equations with the new scheme is about 8.5 times faster compared to the reference method.

  5. Relativistic four-component calculations of indirect nuclear spin-spin couplings with efficient evaluation of the exchange-correlation response kernel

    International Nuclear Information System (INIS)

    Křístková, Anežka; Malkin, Vladimir G.; Komorovsky, Stanislav; Repisky, Michal; Malkina, Olga L.

    2015-01-01

    In this work, we report on the development and implementation of a new scheme for efficient calculation of indirect nuclear spin-spin couplings in the framework of four-component matrix Dirac-Kohn-Sham approach termed matrix Dirac-Kohn-Sham restricted magnetic balance resolution of identity for J and K, which takes advantage of the previous restricted magnetic balance formalism and the density fitting approach for the rapid evaluation of density functional theory exchange-correlation response kernels. The new approach is aimed to speedup the bottleneck in the solution of the coupled perturbed equations: evaluation of the matrix elements of the kernel of the exchange-correlation potential. The performance of the new scheme has been tested on a representative set of indirect nuclear spin-spin couplings. The obtained results have been compared with the corresponding results of the reference method with traditional evaluation of the exchange-correlation kernel, i.e., without employing the fitted electron densities. Overall good agreement between both methods was observed, though the new approach tends to give values by about 4%-5% higher than the reference method. On the average, the solution of the coupled perturbed equations with the new scheme is about 8.5 times faster compared to the reference method

  6. Coupled transport/reaction modelling with ion-exchange: Study of the long-term properties of bentonite buffer in a final repository

    International Nuclear Information System (INIS)

    Liu Jinsong; Neretnieks, I.

    1997-05-01

    Possible transformation of Na-montmorillonite to Ca-montmorillonite, by ion exchange, in the bentonite buffer in a final repository for spent nuclear fuel can lead to a drastic decrease in the swelling capacity and a significant increase in the permeability of the bentonite. The ion exchange mechanism has been studied, by using the coupled transport/reaction model. In most typical sites of the granite bedrock where there are no large fractures, groundwater flow is limited. The results of this study show that the ion-exchange process will be very slow in this case. Only a few percent of the total Na-montmorillonite is exchanged within 1 to 10 thousand years. When the groundwater flow in the bedrock is assumed to be unlimited, an upper bound of the conditions of the water flow, a sharp ion-exchange front can be formed and propagate within the bentonite buffer. When the groundwater is assumed to be the Aespoe water, with a high Ca concentration, the break-through time of the ion-exchange front can be a few thousand years. When the water is assumed to be Allard water with low Ca concentration, the break-through time can be as long as 10 5 to 10 6 years. When a canister has manufacturing defects, both the pyrite oxidation and the ion-exchange processes can occur simultaneously. A redox front and an ion-exchange front develop from both sides of the bentonite buffer. before the two fronts meet, they travel relatively independently in the bentonite. After they have met, they interact only marginally. Even if a large scale ion-exchange happens, the release of the dissolved uranium species from the bentonite to the rock can still be extremely small. The release is mainly controlled by the redox potential of pyrite oxidation

  7. Development of a sharp interface model that simulates coastal aquifer flow with the coupled use of GIS

    Science.gov (United States)

    Gemitzi, Alexandra; Tolikas, Demetrios

    A simulation program, which works seamlessly with GIS and simulates flows in coastal aquifers, is presented in the present paper. The model is based on the Galerkin finite element discretization scheme and it simulates both steady and transient freshwater and saltwater flow, assuming that the two fluids are separated by a sharp interface. The model has been verified in simple cases where analytical solutions exist. The simulation program works as a tool of the GIS program, which is the main database that stores and manages all the necessary data. The combined use of the simulation and the GIS program forms an integrated management tool offering a simpler way of simulating and studying saline intrusion in coastal aquifers. Application of the model to the Yermasogia aquifer illustrates the coupled use of modeling and GIS techniques for the examination of regional coastal aquifer systems. Pour étudier un système aquifère côtier, nous avons développé un modèle aux éléments finis en quasi 3-D qui simule les écoulements d'eau douce et d'eau salée en régime aussi bien permanent que transitoire. Les équations qui les régissent sont discrétisées par un schéma de discrétisation de Garlekin aux éléments finis. Le modèle a été vérifié dans des cas simples où il existe des solutions analytiques. Toutes les données nécessaires sont introduites et gérées grâce à un logiciel de gestion de SIG. Le programme de simulation est utilisé comme un outil du logiciel de SIG, constituant ainsi un outil de gestion intégrée dont le but est de simuler et d'étudier l'intrusion saline dans les aquifères côtiers. L'application du modèle à l'aquifère de Yermasogia illustre l'utilisation couplée de la modélisation et des techniques de SIG pour l'étude des systèmes aquifères côtiers régionaux. Se ha desarrollado un modelo casi tridimensional de elementos finitos para simular el flujo de agua dulce y salada, tanto en régimen estacionario como en

  8. Modeling coupled interactions of carbon, water, and ozone exchange between terrestrial ecosystems and the atmosphere. I: Model description

    International Nuclear Information System (INIS)

    Nikolov, Ned; Zeller, Karl F.

    2003-01-01

    A new biophysical model (FORFLUX) is presented to link ozone deposition with carbon and water cycles in terrestrial ecosystems. - A new biophysical model (FORFLUX) is presented to study the simultaneous exchange of ozone, carbon dioxide, and water vapor between terrestrial ecosystems and the atmosphere. The model mechanistically couples all major processes controlling ecosystem flows trace gases and water implementing recent concepts in plant eco-physiology, micrometeorology, and soil hydrology. FORFLUX consists of four interconnected modules-a leaf photosynthesis model, a canopy flux model, a soil heat-, water- and CO 2 - transport model, and a snow pack model. Photosynthesis, water-vapor flux and ozone uptake at the leaf level are computed by the LEAFC3 sub-model. The canopy module scales leaf responses to a stand level by numerical integration of the LEAFC3 model over canopy leaf area index (LAI). The integration takes into account (1) radiative transfer inside the canopy, (2) variation of foliage photosynthetic capacity with canopy depth, (3) wind speed attenuation throughout the canopy, and (4) rainfall interception by foliage elements. The soil module uses principles of the diffusion theory to predict temperature and moisture dynamics within the soil column, evaporation, and CO 2 efflux from soil. The effect of soil heterogeneity on field-scale fluxes is simulated employing the Bresler-Dagan stochastic concept. The accumulation and melt of snow on the ground is predicted using an explicit energy balance approach. Ozone deposition is modeled as a sum of three fluxes- ozone uptake via plant stomata, deposition to non-transpiring plant surfaces, and ozone flux into the ground. All biophysical interactions are computed hourly while model projections are made at either hourly or daily time step. FORFLUX represents a comprehensive approach to studying ozone deposition and its link to carbon and water cycles in terrestrial ecosystems

  9. Targeting Germinal Matrix Hemorrhage-Induced Overexpression of Sodium-Coupled Bicarbonate Exchanger Reduces Posthemorrhagic Hydrocephalus Formation in Neonatal Rats.

    Science.gov (United States)

    Li, Qian; Ding, Yan; Krafft, Paul; Wan, Weifeng; Yan, Feng; Wu, Guangyong; Zhang, Yixin; Zhan, Qunling; Zhang, John H

    2018-01-31

    Germinal matrix hemorrhage (GMH) is a leading cause of mortality and lifelong morbidity in preterm infants. Posthemorrhagic hydrocephalus (PHH) is a common complication of GMH. A sodium-coupled bicarbonate exchanger (NCBE) encoded by solute carrier family 4 member 10 gene is expressed on the choroid plexus basolateral membrane and may play a role in cerebrospinal fluid production and the development of PHH. Following GMH, iron degraded from hemoglobin has been linked to PHH. Choroid plexus epithelial cells also contain iron-responsive element-binding proteins (IRPs), IRP1, and IRP2 that bind to mRNA iron-responsive elements. The present study aims to resolve the following issues: (1) whether the expression of NCBE is regulated by IRPs; (2) whether NCBE regulates the formation of GMH-induced hydrocephalus; and (3) whether inhibition of NCBE reduces PHH development. GMH model was established in P7 rat pups by injecting bacterial collagenase into the right ganglionic eminence. Another group received iron trichloride injections instead of collagenase. Deferoxamine was administered intraperitoneally for 3 consecutive days after GMH/iron trichloride. Solute carrier family 4 member 10 small interfering RNA or scrambled small interfering RNA was administered by intracerebroventricular injection 24 hours before GMH and followed with an injection every 7 days over 21 days. NCBE expression increased while IRP2 expression decreased after GMH/iron trichloride. Deferoxamine ameliorated both the GMH-induced and iron trichloride-induced decrease of IRP2 and decreased NCBE expressions. Deferoxamine and solute carrier family 4 member 10 small interfering RNA improved cognitive and motor functions at 21 to 28 days post GMH and reduced cerebrospinal fluid production as well as the degree of hydrocephalus at 28 days after GMH. Targeting iron-induced overexpression of NCBE may be a translatable therapeutic strategy for the treatment of PHH following GMH. © 2018 The Authors

  10. Bounds on the g/sub K//sub N//sub Σ/ 2 coupling constant from positivity and charge-exchange data

    International Nuclear Information System (INIS)

    Antolin, J.

    1987-01-01

    Positivity of the imaginary part of the forward K - n elastic amplitude on the unphysical cut allows the calculation of bounds on the g/sub K//sub N//sub Σ/ 2 coupling constant using the forward differential cross sections of the charge-exchange reaction K - p→K-bar 0 n, the scarce K - n real-part data, and a Stieltjes parametrization of the K - p real-part data. The bounds on the coupling constant are 2.11 2 - n amplitude: (0.35 +- 0.05) +- (0.16 +- 0.04)i GeV/c

  11. Calculation of exchange coupling constants in triply-bridged dinuclear Cu(II) compounds based on spin-flip constricted variational density functional theory.

    Science.gov (United States)

    Seidu, Issaka; Zhekova, Hristina R; Seth, Michael; Ziegler, Tom

    2012-03-08

    The performance of the second-order spin-flip constricted variational density functional theory (SF-CV(2)-DFT) for the calculation of the exchange coupling constant (J) is assessed by application to a series of triply bridged Cu(II) dinuclear complexes. A comparison of the J values based on SF-CV(2)-DFT with those obtained by the broken symmetry (BS) DFT method and experiment is provided. It is demonstrated that our methodology constitutes a viable alternative to the BS-DFT method. The strong dependence of the calculated exchange coupling constants on the applied functionals is demonstrated. Both SF-CV(2)-DFT and BS-DFT affords the best agreement with experiment for hybrid functionals.

  12. Inclusive Σp and pp reactions. How can one learn the nature of π, K, Λ, N exchanges and determine the coupling constants

    International Nuclear Information System (INIS)

    Vasylev, A.M.; Ginzburg, I.F.; Perlovskij, L.I.

    1977-01-01

    Inclusive experiments pp → π + +..., Σp → Λ +..., pp → K + +... are proposed in which it is possible to come very close to the π, K, N, Λ poles. In these experiments it is possible, in principle, to extract the most precise values of the coupling constants KNY, Σ π Λ,... and to state the problem which is the nature of the exchanges. A critical analysis of the pp → π + + ... data is carried out

  13. Electron paramagnetic resonance study of exchange coupled Ce.sup.3+./sup. ions in Lu.sub.2./sub.SiO.sub.5./sub. single crystal scintillator

    Czech Academy of Sciences Publication Activity Database

    Buryi, Maksym; Laguta, Valentyn; Rosa, Jan; Nikl, Martin

    2016-01-01

    Roč. 90, Jul (2016), s. 23-26 ISSN 1350-4487 R&D Projects: GA ČR GAP204/12/0805; GA MŠk(CZ) LM2011029; GA MŠk LO1409 Institutional support: RVO:68378271 Keywords : electron paramagnetic resonance * scintillators * lutetium oxyorthosilicate * exchange coupled ions * cerium ions Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.442, year: 2016

  14. Equivalent Circuit Model of Low-Frequency Magnetoelectric Effect in Disk-Type Terfenol-D/PZT Laminate Composites Considering a New Interface Coupling Factor.

    Science.gov (United States)

    Lou, Guofeng; Yu, Xinjie; Lu, Shihua

    2017-06-15

    This paper describes the modeling of magnetoelectric (ME) effects for disk-type Terfenol-D (Tb 0.3 Dy 0.7 Fe 1.92 )/PZT (Pb(Zr,Ti)O₃) laminate composite at low frequency by combining the advantages of the static elastic model and the equivalent circuit model, aiming at providing a guidance for the design and fabrication of the sensors based on magnetoelectric laminate composite. Considering that the strains of the magnetostrictive and piezoelectric layers are not equal in actual operating due to the epoxy resin adhesive bonding condition, the magnetostrictive and piezoelectric layers were first modeled through the equation of motion separately, and then coupled together with a new interface coupling factor k c , which physically reflects the strain transfer between the phases. Furthermore, a theoretical expression containing k c for the transverse ME voltage coefficient α v and the optimum thickness ratio n optim to which the maximum ME voltage coefficient corresponds were derived from the modified equivalent circuit of ME laminate, where the interface coupling factor acted as an ideal transformer. To explore the influence of mechanical load on the interface coupling factor k c , two sets of weights, i.e., 100 g and 500 g, were placed on the top of the ME laminates with the same thickness ratio n in the sample fabrication. A total of 22 T-T mode disk-type ME laminate samples with different configurations were fabricated. The interface coupling factors determined from the measured α v and the DC bias magnetic field H bias were 0.11 for 500 g pre-mechanical load and 0.08 for 100 g pre-mechanical load. Furthermore, the measured optimum thickness ratios were 0.61 for k c = 0.11 and 0.56 for k c = 0.08. Both the theoretical ME voltage coefficient α v and optimum thickness ratio n optim containing k c agreed well with the measured data, verifying the reasonability and correctness for the introduction of k c in the modified equivalent circuit model.

  15. Equivalent Circuit Model of Low-Frequency Magnetoelectric Effect in Disk-Type Terfenol-D/PZT Laminate Composites Considering a New Interface Coupling Factor

    Directory of Open Access Journals (Sweden)

    Guofeng Lou

    2017-06-01

    Full Text Available This paper describes the modeling of magnetoelectric (ME effects for disk-type Terfenol-D (Tb0.3Dy0.7Fe1.92/PZT (Pb(Zr,TiO3 laminate composite at low frequency by combining the advantages of the static elastic model and the equivalent circuit model, aiming at providing a guidance for the design and fabrication of the sensors based on magnetoelectric laminate composite. Considering that the strains of the magnetostrictive and piezoelectric layers are not equal in actual operating due to the epoxy resin adhesive bonding condition, the magnetostrictive and piezoelectric layers were first modeled through the equation of motion separately, and then coupled together with a new interface coupling factor kc, which physically reflects the strain transfer between the phases. Furthermore, a theoretical expression containing kc for the transverse ME voltage coefficient αv and the optimum thickness ratio noptim to which the maximum ME voltage coefficient corresponds were derived from the modified equivalent circuit of ME laminate, where the interface coupling factor acted as an ideal transformer. To explore the influence of mechanical load on the interface coupling factor kc, two sets of weights, i.e., 100 g and 500 g, were placed on the top of the ME laminates with the same thickness ratio n in the sample fabrication. A total of 22 T-T mode disk-type ME laminate samples with different configurations were fabricated. The interface coupling factors determined from the measured αv and the DC bias magnetic field Hbias were 0.11 for 500 g pre-mechanical load and 0.08 for 100 g pre-mechanical load. Furthermore, the measured optimum thickness ratios were 0.61 for kc = 0.11 and 0.56 for kc = 0.08. Both the theoretical ME voltage coefficient αv and optimum thickness ratio noptim containing kc agreed well with the measured data, verifying the reasonability and correctness for the introduction of kc in the modified equivalent circuit model.

  16. Design and Micromagnetic Simulation of Fe/L10-FePt/Fe Trilayer for Exchange Coupled Composite Bit Patterned Media at Ultrahigh Areal Density

    Directory of Open Access Journals (Sweden)

    Warunee Tipcharoen

    2015-01-01

    Full Text Available Exchange coupled composite bit patterned media (ECC-BPM are one candidate to solve the trilemma issues, overcome superparamagnetic limitations, and obtain ultrahigh areal density. In this work, the ECC continuous media and ECC-BPM of Fe/L10-FePt/Fe trilayer schemes are proposed and investigated based on the Landau-Lifshitz-Gilbert equation. The switching field, Hsw, of the hard phase in the proposed continuous ECC trilayer media structure is reduced below the maximum write head field at interlayer exchange coupling between hard and soft phases, Aex, higher than 20 pJ/m and its value is lower than that for continuous L10-FePt single layer media and L10-FePt/Fe bilayer. Furthermore, the Hsw of the proposed ECC-BPM is lower than the maximum write head field with exchange coupling coefficient between neighboring dots of 5 pJ/m and Aex over 10 pJ/m. Therefore, the proposed ECC-BPM trilayer has the highest potential and is suitable for ultrahigh areal density magnetic recording technology at ultrahigh areal density. The results of this work may be gainful idea for nanopatterning in magnetic media nanotechnology.

  17. Anomalous photon-gauge boson coupling contribution to the exclusive vector boson pair production from two photon exchange in pp collisions at 13 TeV

    Energy Technology Data Exchange (ETDEWEB)

    Martins, D. E.; Vilela Pereira, A.; Sá Borges, J. [Universidade do Estado do Rio de Janeiro - UERJ, Rio de Janeiro-RJ, 20550-900 (Brazil); Rebello Teles, P. [Centro Brasileiro de Pesquisas Físicas - CBPF, Rio de Janeiro-RJ, 22290-180 (Brazil)

    2015-04-10

    We study the W and Z pair production from two-photon exchange in proton-proton collisions at the LHC in order to evaluate the contributions of anomalous photon-gauge boson couplings, that simulates new particles and couplings predicted in many Standard Model (SM) extensions. The experimental results of W{sup +} W{sup −} exclusive production (pp → pW{sup +}W{sup −} p) at 7 TeV from the CMS collaboration [1] updates the experimental limits on anomalous couplings obtained at the Large Electron-Positron Collider (LEP). This motivates our present analysis hopefully anticipating the expected results using the Precision Proton Spectrometer (PPS) to be installed as part of CMS. In this work, we consider the W{sup +}W{sup −} exclusive production to present the p{sub T} distribution of the lepton pair corresponding to the SM signal with p{sub T} (e, μ) > 10 GeV. Next, we consider the photon-gauge boson anomalous couplings by calculating, from the FPMC and MadGraph event generators, the process γγ → W{sup +}W{sup −} from a model with gauge boson quartic couplings, by considering a 1 TeV scale for new physical effects. We present our results for an integrated luminosity of 5 fb{sup −1} at center-of-mass energy of 7 TeV and for an integrated luminosity of 100 fb{sup −1} at 13 TeV. We present our preliminary results for Z pair exclusive production from two-photon exchange with anomalous couplings, where the ZZγγ quartic coupling is absent in the SM. We calculate the total cross section for the exclusive process and present the four lepton invariant mass distribution. Finally we present an outlook for the present analysis.

  18. Carbon X-ray absorption spectra of fluoroethenes and acetone: a study at the coupled cluster, density functional, and static-exchange levels of theory.

    Science.gov (United States)

    Fransson, Thomas; Coriani, Sonia; Christiansen, Ove; Norman, Patrick

    2013-03-28

    Near carbon K-edge X-ray absorption fine structure spectra of a series of fluorine-substituted ethenes and acetone have been studied using coupled cluster and density functional theory (DFT) polarization propagator methods, as well as the static-exchange (STEX) approach. With the complex polarization propagator (CPP) implemented in coupled cluster theory, relaxation effects following the excitation of core electrons are accounted for in terms of electron correlation, enabling a systematic convergence of these effects with respect to electron excitations in the cluster operator. Coupled cluster results have been used as benchmarks for the assessment of propagator methods in DFT as well as the state-specific static-exchange approach. Calculations on ethene and 1,1-difluoroethene illustrate the possibility of using nonrelativistic coupled cluster singles and doubles (CCSD) with additional effects of electron correlation and relativity added as scalar shifts in energetics. It has been demonstrated that CPP spectra obtained with coupled cluster singles and approximate doubles (CC2), CCSD, and DFT (with a Coulomb attenuated exchange-correlation functional) yield excellent predictions of chemical shifts for vinylfluoride, 1,1-difluoroethene, trifluoroethene, as well as good spectral features for acetone in the case of CCSD and DFT. Following this, CPP-DFT is considered to be a viable option for the calculation of X-ray absorption spectra of larger π-conjugated systems, and CC2 is deemed applicable for chemical shifts but not for studies of fine structure features. The CCSD method as well as the more approximate CC2 method are shown to yield spectral features relating to π∗-resonances in good agreement with experiment, not only for the aforementioned molecules but also for ethene, cis-1,2-difluoroethene, and tetrafluoroethene. The STEX approach is shown to underestimate π∗-peak separations due to spectral compressions, a characteristic which is inherent to this

  19. Dynamic spin filtering at the Co/Alq3 interface mediated by weakly coupled second layer molecules

    Science.gov (United States)

    Droghetti, Andrea; Thielen, Philip; Rungger, Ivan; Haag, Norman; Großmann, Nicolas; Stöckl, Johannes; Stadtmüller, Benjamin; Aeschlimann, Martin; Sanvito, Stefano; Cinchetti, Mirko

    2016-08-01

    Spin filtering at organic-metal interfaces is often determined by the details of the interaction between the organic molecules and the inorganic magnets used as electrodes. Here we demonstrate a spin-filtering mechanism based on the dynamical spin relaxation of the long-living interface states formed by the magnet and weakly physisorbed molecules. We investigate the case of Alq3 on Co and, by combining two-photon photoemission experiments with electronic structure theory, show that the observed long-time spin-dependent electron dynamics is driven by molecules in the second organic layer. The interface states formed by physisorbed molecules are not spin-split, but acquire a spin-dependent lifetime, that is the result of dynamical spin-relaxation driven by the interaction with the Co substrate. Such spin-filtering mechanism has an important role in the injection of spin-polarized carriers across the interface and their successive hopping diffusion into successive molecular layers of molecular spintronics devices.

  20. Perpendicular exchange coupling effects in ferrimagnetic TbFeCo/GdFeCo hard/soft structures

    Science.gov (United States)

    Wang, Ke; Wang, Yahong; Ling, Fujin; Xu, Zhan

    2018-04-01

    Bilayers consisting of magnetically hard TbFeCo and soft GdFeCo alloy were fabricated. Exchange-spring and sharp switching in a step-by-step fashion were observed in the TbFeCo/GdFeCo hard/soft bilayers with increasing GdFeCo thickness. A perpendicular exchange bias field of several hundred Oersteds is observed from the shift of minor loops pinned by TbFeCo layer. The perpendicular exchange energy is derived to be in the range of 0.18-0.30 erg/cm2. The exchange energy is shown to increase with the thickness of GdFeCo layer in the bilayers, which can be attributed to the enhanced perpendicular anisotropy of GdFeCo layer in our experimental range.

  1. Simultaneous determination of platinum group elements and rhenium in rock samples using isotope dilution inductively coupled plasma mass spectrometry after cation exchange separation followed by solvent extraction

    International Nuclear Information System (INIS)

    Shinotsuka, Kazunori; Suzuki, Katsuhiko

    2007-01-01

    A simple and precise determination method for platinum group elements (PGEs) and Re in rock samples was developed using isotope dilution coupled with inductively coupled plasma mass spectrometry (ID-ICP-MS). Cation exchange separation was employed for simplicity, because it is applicable to group separation and simultaneous isotopic measurement in contrast with the widely used anion exchange separation which entails separate elution. However, its application to ID-ICP-MS has been limited due to spectral interferences from impurities retained in the PGE fraction even after ion chromatography. To overcome this limitation, solvent extraction using N-benzoyl-N-phenylhydroxylamine (BPHA) in chloroform was successfully applied for further purification. After the examination of optimum experimental parameters in cation exchange separation and solvent extraction using synthetic PGE solution, the established procedure was applied to the determination of PGEs and Re in some geochemical reference materials. The obtained results agreed well with the literature data determined using the different digestion methods (NiS fire assay and the use of a high-pressure asher) within the analytical uncertainties of each other. Significant difference in reproducibility between Ru, Ir, Pt and Os group, and Pd and Re group was observed in the results for BHVO-2 and JA-2. By considering the error factors affecting analytical reproducibility, we concluded that the difference is ascribed to the sample heterogeneity of minor minerals enriched in Ru, Ir, Pt and Os

  2. A parallel interaction potential approach coupled with the immersed boundary method for fully resolved simulations of deformable interfaces and membranes

    Science.gov (United States)

    Spandan, Vamsi; Meschini, Valentina; Ostilla-Mónico, Rodolfo; Lohse, Detlef; Querzoli, Giorgio; de Tullio, Marco D.; Verzicco, Roberto

    2017-11-01

    In this paper we show and discuss how the deformation dynamics of closed liquid-liquid interfaces (for example drops and bubbles) can be replicated with use of a phenomenological interaction potential model. This new approach to simulate liquid-liquid interfaces is based on the fundamental principle of minimum potential energy where the total potential energy depends on the extent of deformation of a spring network distributed on the surface of the immersed drop or bubble. Simulating liquid-liquid interfaces using this model require computing ad-hoc elastic constants which is done through a reverse-engineered approach. The results from our simulations agree very well with previous studies on the deformation of drops in standard flow configurations such as a deforming drop in a shear flow or cross flow. The interaction potential model is highly versatile, computationally efficient and can be easily incorporated into generic single phase fluid solvers to also simulate complex fluid-structure interaction problems. This is shown by simulating flow in the left ventricle of the heart with mechanical and natural mitral valves where the imposed flow, motion of ventricle and valves dynamically govern the behaviour of each other. Results from these simulations are compared with ad-hoc in-house experimental measurements. Finally, we present a simple and easy to implement parallelisation scheme, as high performance computing is unavoidable when studying large scale problems involving several thousands of simultaneously deforming bodies in highly turbulent flows.

  3. Mercury speciation and exchanges at the air-water interface of a tropical artificial reservoir, French Guiana.

    Science.gov (United States)

    Muresan, B; Cossa, D; Richard, S; Burban, B

    2007-10-15

    The distribution and speciation of mercury (Hg) in air, rain, and surface waters from the artificial tropical lake of Petit-Saut in French Guiana were investigated during the 2003/04 period. In the air, total gaseous mercury (TGM) at the dam station averaged 12+/-2 pmol m(-3) of which >98% was gaseous elemental mercury (GEM). GEM distribution depicted a day-night cycling with high concentrations (up to 15 pmol m(-3)) at dawn and low concentrations (down to 5 pmol m(-3)) at nightfall. Reactive gaseous mercury (RGM) represented RGM variations were negatively related to GEM. In the rain, the sum of all Hg species in the unfiltered (HgT(UNF)) averaged 16+/-12 pmol L(-1). Temporal distribution of HgT(UNF) exhibited a pattern of high concentrations during the late dry seasons (up to 57.5 pmol L(-1)) and low concentrations (down to 2.7 pmol L(-1)) in the course of the wet seasons. Unfiltered reactive (HgR(UNF)), dissolved gaseous (DGM) and monomethyl (MMHg(UNF)) Hg constituted 20, 5 and 5% of HgT(UNF), respectively. All measured Hg species were positively related and displayed negative relationships with the pH of the rain. In the reservoir surface waters, dissolved total mercury (HgT(D)) averaged 3.4+/-1.2 pmol L(-1) of which 10% consisted of DGM. DGM showed a trend of high concentrations during the dry seasons (480+/-270 fmol L(-1)) and lower (230+/-130 fmol L(-1)) in the course of the wet seasons. Diel variations included diurnal photo-induced DGM production (of about 60 fmol L(-1) h(-1)) coupled to minute to hour oxidation/reduction cycles (of >100 fmol L(-1) amplitude). Finally, calculated atmospheric Hg inputs to the Petit-Saut reservoir represented 14 mol yr(-1) whereas DGM evasion reached 23 mol yr(-1). Apportionment among forms of Hg deposition indicated that up to 75% of the total Hg invasive flux follows the rainfall pathway.

  4. Effect of asymmetric interface on charge and spin transport across two dimensional electron gas with Dresselhaus spin-orbit coupling/ferromagnet junction

    Science.gov (United States)

    Srisongmuang, B.; Pasanai, K.

    2018-04-01

    We theoretically studied the effect of interfacial scattering on the transport of charge and spin across the junction of a two-dimensional electron gas with Dresselhaus spin-orbit coupling and ferromagnetic material junction, via the conductance (G) and the spin-polarization of the conductance spectra (P) using the scattering method. At the interface, not only were the effects of spin-conserving (Z0) and spin-flip scattering (Zf) considered, but also the interfacial Rashba spin-orbit coupling scattering (ZRSOC) , which was caused by the asymmetry of the interface, was taken into account, and all of them were modeled by the delta potential. It was found that G was suppressed with increasing Z0 , as expected. Interestingly, a particular value of Zf can cause G and P to reach a maximum value. In particular, ZRSOC plays a crucial role to reduce G and P in the metallic limit, but its influence on the tunneling limit was quite weak. On the other hand, the effect of ZRSOC was diminished in the tunneling limit of the magnetic junction.

  5. Interface unit

    NARCIS (Netherlands)

    Keyson, D.V.; Freudenthal, A.; De Hoogh, M.P.A.; Dekoven, E.A.M.

    2001-01-01

    The invention relates to an interface unit comprising at least a display unit for communication with a user, which is designed for being coupled with a control unit for at least one or more parameters in a living or working environment, such as the temperature setting in a house, which control unit

  6. Electric-field-modulated exchange coupling within and between magnetic clusters on metal surfaces: Mn dimers on Cu(1 1 1)

    International Nuclear Information System (INIS)

    Juárez-Reyes, L; Pastor, G M; Stepanyuk, V S

    2014-01-01

    The effects of external electric fields (EFs) on the magnetic state and substrate-mediated magnetic coupling between Mn dimers on Cu(1 1 1) have been studied using a first-principles theoretical method. The calculations show that a change in the ground-state magnetic order, from antiferromagnetic (AF) to ferromagnetic (FM), can be induced within an isolated Mn 2 on Cu(1 1 1) by applying a moderately strong EF of about 1 V Å −1 . The magnetic exchange coupling between pairs of dimers displays Ruderman–Kittel–Kasuya–Yosida-like oscillations as a function of the interdimer distance, which depend significantly on the magnetic order within the dimers (FM or AF) and on their relative orientation on the surface. Moreover, it is observed that applying EFs allows modulation of the exchange coupling within and between the clusters as a function of the intercluster distance. At short distances, AF order within the dimers is favoured even in the presence of EFs, while for large distances the EF can induce a FM order. EFs pointing outwards and inwards with respect to the surface favour parallel and antiparallel magnetic alignment between the dimers, resspectively. The dependence of the substrate-mediated interaction on the magnetic state of Mn 2 is qualitatively interpreted in terms of the differences in the scattering of spin-polarized surface electrons. (paper)

  7. Coupling fast water exchange to slow molecular tumbling in Gd3+ chelates: why faster is not always better.

    Science.gov (United States)

    Avedano, Stefano; Botta, Mauro; Haigh, Julian S; Longo, Dario L; Woods, Mark

    2013-08-05

    The influence of dynamics on solution state structure is a widely overlooked consideration in chemistry. Variations in Gd(3+) chelate hydration with changing coordination geometry and dissociative water exchange kinetics substantially impact the effectiveness (or relaxivity) of monohydrated Gd(3+) chelates as T1-shortening contrast agents for MRI. Theory shows that relaxivity is highly dependent upon the Gd(3+)-water proton distance (rGdH), and yet this distance is almost never considered as a variable in assessing the relaxivity of a Gd(3+) chelate as a potential contrast agent. The consequence of this omission can be seen when considering the relaxivity of isomeric Gd(3+) chelates that exhibit different dissociative water exchange kinetics. The results described herein show that the relaxivity of a chelate with "optimal" dissociative water exchange kinetics is actually lower than that of an isomeric chelate with "suboptimal" dissociative water exchange. When the rate of molecular tumbling of these chelates is slowed, an approach that has long been understood to increase relaxivity, the observed difference in relaxivity is increased with the more rapidly exchanging ("optimal") chelate exhibiting lower relaxivity than the "suboptimally" exchanging isomer. The difference between the chelates arises from a non-field-dependent parameter: either the hydration number (q) or rGdH. For solution state Gd(3+) chelates, changes in the values of q and rGdH are indistinguishable. These parametric expressions simply describe the hydration state of the chelate--i.e., the number and position of closely associating water molecules. The hydration state (q/rGdH(6)) of a chelate is intrinsically linked to its dissociative water exchange rate kex, and the interrelation of these parameters must be considered when examining the relaxivity of Gd(3+) chelates. The data presented herein indicate that the changes in the hydration parameter (q/rGdH(6)) associated with changing dissociative

  8. Exchange Coupling Interactions from the Density Matrix Renormalization Group and N-Electron Valence Perturbation Theory: Application to a Biomimetic Mixed-Valence Manganese Complex.

    Science.gov (United States)

    Roemelt, Michael; Krewald, Vera; Pantazis, Dimitrios A

    2018-01-09

    The accurate description of magnetic level energetics in oligonuclear exchange-coupled transition-metal complexes remains a formidable challenge for quantum chemistry. The density matrix renormalization group (DMRG) brings such systems for the first time easily within reach of multireference wave function methods by enabling the use of unprecedentedly large active spaces. But does this guarantee systematic improvement in predictive ability and, if so, under which conditions? We identify operational parameters in the use of DMRG using as a test system an experimentally characterized mixed-valence bis-μ-oxo/μ-acetato Mn(III,IV) dimer, a model for the oxygen-evolving complex of photosystem II. A complete active space of all metal 3d and bridge 2p orbitals proved to be the smallest meaningful starting point; this is readily accessible with DMRG and greatly improves on the unrealistic metal-only configuration interaction or complete active space self-consistent field (CASSCF) values. Orbital optimization is critical for stabilizing the antiferromagnetic state, while a state-averaged approach over all spin states involved is required to avoid artificial deviations from isotropic behavior that are associated with state-specific calculations. Selective inclusion of localized orbital subspaces enables probing the relative contributions of different ligands and distinct superexchange pathways. Overall, however, full-valence DMRG-CASSCF calculations fall short of providing a quantitative description of the exchange coupling owing to insufficient recovery of dynamic correlation. Quantitatively accurate results can be achieved through a DMRG implementation of second order N-electron valence perturbation theory (NEVPT2) in conjunction with a full-valence metal and ligand active space. Perspectives for future applications of DMRG-CASSCF/NEVPT2 to exchange coupling in oligonuclear clusters are discussed.

  9. Development of a general coupling interface for the fuel performance code transuranus tested with the reactor dynamic code DYN3D

    International Nuclear Information System (INIS)

    Holt, L.; Rohde, U.; Seidl, M.; Schubert, A.; Van Uffelen, P.

    2013-01-01

    Several institutions plan to couple the fuel performance code TRANSURANUS developed by the European Institute for Transuranium Elements with their own codes. One of these codes is the reactor dynamic code DYN3D maintained by the Helmholtz-Zentrum Dresden - Rossendorf. DYN3D was developed originally for VVER type reactors and was extended later to western type reactors. Usually, the fuel rod behavior is modeled in thermal hydraulics and neutronic codes in a simplified manner. The main idea of this coupling is to describe the fuel rod behavior in the frame of core safety analysis in a more detailed way, e.g. including the influence of the high burn-up structure, geometry changes and fission gas release. It allows to take benefit from the improved computational power and software achieved over the last two decades. The coupling interface was developed in a general way from the beginning. Thence it can be easily used also by other codes for a coupling with TRANSURANUS. The user can choose between a one-way as well as a two-way online coupling option. For a one-way online coupling, DYN3D provides only the time-dependent rod power and thermal hydraulics conditions to TRANSURANUS, but the fuel performance code doesn’t transfer any variable back to DYN3D. In a two-way online coupling, TRANSURANUS in addition transfers parameters like fuel temperature and cladding temperature back to DYN3D. This list of variables can be extended easily by geometric and further variables of interest. First results of the code system DYN3D-TRANSURANUS will be presented for a control rod ejection transient in a modern western type reactor. Pre-analyses show already that a detailed fuel rod behavior modeling will influence the thermal hydraulics and thence also the neutronics due to the Doppler reactivity effect of the fuel temperature. The coupled code system has therefore a potential to improve the assessment of safety criteria. The developed code system DYN3D-TRANSURANUS can be used also

  10. Development of salt-tolerance interface for an high performance liquid chromatography/inductively coupled plasma mass spectrometry system and its application to accurate quantification of DNA samples.

    Science.gov (United States)

    Takasaki, Yuka; Sakagawa, Shinnosuke; Inagaki, Kazumi; Fujii, Shin-Ichiro; Sabarudin, Akhmad; Umemura, Tomonari; Haraguchi, Hiroki

    2012-02-03

    Accurate quantification of DNA is highly important in various fields. Determination of phosphorus by ICP-MS is one of the most effective methods for accurate quantification of DNA due to the fixed stoichiometry of phosphate to this molecule. In this paper, a smart and reliable method for accurate quantification of DNA fragments and oligodeoxythymidilic acids by hyphenated HPLC/ICP-MS equipped with a highly efficient interface device is presented. The interface was constructed of a home-made capillary-attached micronebulizer and temperature-controllable cyclonic spray chamber (IsoMist). As a separation column for DNA samples, home-made methacrylate-based weak anion-exchange monolith was employed. Some parameters, which include composition of mobile phase, gradient program, inner and outer diameters of capillary, temperature of spray chamber etc., were optimized to find the best performance for separation and accurate quantification of DNA samples. The proposed system could achieve many advantages, such as total consumption for small amount sample analysis, salt-tolerance for hyphenated analysis, high accuracy and precision for quantitative analysis. Using this proposed system, the samples of 20 bp DNA ladder (20, 40, 60, 80, 100, 120, 140, 160, 180, 200, 300, 400, 500 base pairs) and oligodeoxythymidilic acids (dT(12-18)) were rapidly separated and accurately quantified. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Magnetic hybride layers. Magnetic properties of locally exchange-coupled NiFe/IrMn layers; Magnetische Hybridschichten. Magnetische Eigenschaften lokal austauschgekoppelter NiFe/IrMn-Schichten

    Energy Technology Data Exchange (ETDEWEB)

    Hamann, Christine

    2010-10-06

    By the lateral modification of the magnetic properties of exchange-coupled NiFe/IrMn layers soft-magnetic layers were produced, which show both new static and dynamic properties. As lateral structuration methods hereby the localoxidation as well as ion implantation were applied. By means of thes procedures it has been succeeded to mould specific magnetic domain configurations with strp structure into the layers. In dependence of the structure orientation as well as strip period the remagnetization behavior as well as the magnetic-resonance frequency and damping of the layers could directly be modified. The new dynamical properties are hereby discussed in the framework of the coupling via dynamical charges and the direct affection of the effective field of the artificially inserted domain state. The presented results prove by this the large potential of the lateral magneto-structuration for the tuning of specifical static as well as dynamic properties of magnetically thin layers.

  12. Garbage collector interface

    OpenAIRE

    Ive, Anders; Blomdell, Anders; Ekman, Torbjörn; Henriksson, Roger; Nilsson, Anders; Nilsson, Klas; Robertz, Sven

    2002-01-01

    The purpose of the presented garbage collector interface is to provide a universal interface for many different implementations of garbage collectors. This is to simplify the integration and exchange of garbage collectors, but also to support incremental, non-conservative, and thread safe implementations. Due to the complexity of the interface, it is aimed at code generators and preprocessors. Experiences from ongoing implementations indicate that the garbage collector interface successfully ...

  13. New Trends in Magnetic Exchange Bias

    Science.gov (United States)

    Mougin, Alexandra; Mangin, Stéphane; Bobo, Jean-Francois; Loidl, Alois

    2005-05-01

    The study of layered magnetic structures is one of the hottest topics in magnetism due to the growing attraction of applications in magnetic sensors and magnetic storage media, such as random access memory. For almost half a century, new discoveries have driven researchers to re-investigate magnetism in thin film structures. Phenomena such as giant magnetoresistance, tunneling magnetoresistance, exchange bias and interlayer exchange coupling led to new ideas to construct devices, based not only on semiconductors but on a variety of magnetic materials Upon cooling fine cobalt particles in a magnetic field through the Néel temperature of their outer antiferromagnetic oxide layer, Meiklejohn and Bean discovered exchange bias in 1956. The exchange bias effect through which an antiferromagnetic AF layer can cause an adjacent ferromagnetic F layer to develop a preferred direction of magnetization, is widely used in magnetoelectronics technology to pin the magnetization of a device reference layer in a desired direction. However, the origin and effects due to exchange interaction across the interface between antiferromagneic and ferromagnetic layers are still debated after about fifty years of research, due to the extreme difficulty associated with the determination of the magnetic interfacial structure in F/AF bilayers. Indeed, in an AF/F bilayer system, the AF layer acts as “the invisible man” during conventional magnetic measurements and the presence of the exchange coupling is evidenced indirectly through the unusual behavior of the adjacent F layer. Basically, the coercive field of the F layer increases in contact with the AF and, in some cases, its hysteresis loop is shifted by an amount called exchange bias field. Thus, AF/F exchange coupling generates a new source of anisotropy in the F layer. This induced anisotropy strongly depends on basic features such as the magnetocrystalline anisotropy, crystallographic and spin structures, defects, domain patterns etc

  14. Control of advanced reactor-coupled heat exchanger system: Incorporation of reactor dynamics in system response to load disturbances

    Energy Technology Data Exchange (ETDEWEB)

    Skavdahi, Isaac; Utgikar, Vivek [Dept. of Chemical and Materials Engineering, University of Idaho, Moscow (United States); Christensen, Richard [Nuclear Engineering Program, University of Idaho, Idaho Falls (United States); Chen, Ming Hui; Sun, Xiao Dong [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus (United States); Sabharwall, Piyush [Idaho National Laboratory, Idaho Falls (United States)

    2016-12-15

    Alternative control schemes for an Advanced High Temperature Reactor system consisting of a reactor, an intermediate heat exchanger, and a secondary heat exchanger (SHX) are presented in this paper. One scheme is designed to control the cold outlet temperature of the SHX (T{sub co}) and the hot outlet temperature of the intermediate heat exchanger (Th{sub o2}) by manipulating the hot-side flow rates of the heat exchangers (F{sub h}/F{sub h2}) responding to the flow rate and temperature disturbances. The flow rate disturbances typically require a larger manipulation of the flow rates than temperature disturbances. An alternate strategy examines the control of the cold outlet temperature of the SHX (T{sub co}) only, since this temperature provides the driving force for energy production in the power conversion unit or the process application. The control can be achieved by three options: (1) flow rate manipulation; (2) reactor power manipulation; or (3) a combination of the two. The first option has a quicker response but requires a large flow rate change. The second option is the slowest but does not involve any change in the flow rates of streams. The third option appears preferable as it has an intermediate response time and requires only a minimal flow rate change.

  15. Water exchange estimates derived from forcing for the hydraulically coupled basins surrounding Aespoe island and adjacent coastal water

    International Nuclear Information System (INIS)

    Engqvist, A.

    1997-08-01

    A numerical model study based on representative physical forcing data (statistically averaged from approximately 10 years) has been performed of the Aespoe area, subdivided into five separate basins, interconnected by four straits and connected to the Baltic coast through three straits. The water exchange of the shallow Borholmsfjaerden, with comparatively small section areas of its straits, is dominated by the sea level variations while the baroclinic exchange components (estuarine and intermediary circulation) also contribute. The average transit retention time (averaged over the basin volume for a full year cycle) is found to be a little over 40 days for exogenous water (i.e. coastal water and freshwater combined); this measure of the water exchange is comparable to the combined average of an ensemble consisting of 157 similarly analyzed basins distributed along the Swedish east and west coasts. The exchange mechanisms and model assumptions are discussed. The consequences for the retention times by short- and long-term variations of the forcing is also analyzed. The standard deviation (SD) of the retention time during an average year (intra-annual variation) is greater than the SD between years (interannual variation) for all basins except Borholmsfjaerden for which these two measures are in parity. The range of the retention times that results from an extreme combination of forcing factor variation between years is found to be greater the farther a particular basin is located from the coast, measured as the minimal number of separating straits. The results of an earlier investigation are also reviewed

  16. On the importance of exchangeable NH protons in creatine for the magnetic coupling of creatine methyl protons in skeletal muscle

    NARCIS (Netherlands)

    Kruiskamp, M.J.; Nicolaij, K.

    2001-01-01

    The methyl protons of creatine in skeletal muscle exhibit a strong off-resonance magnetization transfer effect. The mechanism of this process is unknown. We previously hypothesized that the exchangeable amide/amino protons of creatine might be involved. To test this the characteristics of the

  17. Control of Advanced Reactor-Coupled Heat Exchanger System: Incorporation of Reactor Dynamics in System Response to Load Disturbances

    Directory of Open Access Journals (Sweden)

    Isaac Skavdahl

    2016-12-01

    Full Text Available Alternative control schemes for an Advanced High Temperature Reactor system consisting of a reactor, an intermediate heat exchanger, and a secondary heat exchanger (SHX are presented in this paper. One scheme is designed to control the cold outlet temperature of the SHX (Tco and the hot outlet temperature of the intermediate heat exchanger (Tho2 by manipulating the hot-side flow rates of the heat exchangers (Fh/Fh2 responding to the flow rate and temperature disturbances. The flow rate disturbances typically require a larger manipulation of the flow rates than temperature disturbances. An alternate strategy examines the control of the cold outlet temperature of the SHX (Tco only, since this temperature provides the driving force for energy production in the power conversion unit or the process application. The control can be achieved by three options: (1 flow rate manipulation; (2 reactor power manipulation; or (3 a combination of the two. The first option has a quicker response but requires a large flow rate change. The second option is the slowest but does not involve any change in the flow rates of streams. The third option appears preferable as it has an intermediate response time and requires only a minimal flow rate change.

  18. Control of advanced reactor-coupled heat exchanger system: Incorporation of reactor dynamics in system response to load disturbances

    International Nuclear Information System (INIS)

    Skavdahi, Isaac; Utgikar, Vivek; Christensen, Richard; Chen, Ming Hui; Sun, Xiao Dong; Sabharwall, Piyush

    2016-01-01

    Alternative control schemes for an Advanced High Temperature Reactor system consisting of a reactor, an intermediate heat exchanger, and a secondary heat exchanger (SHX) are presented in this paper. One scheme is designed to control the cold outlet temperature of the SHX (T_c_o) and the hot outlet temperature of the intermediate heat exchanger (Th_o_2) by manipulating the hot-side flow rates of the heat exchangers (F_h/F_h_2) responding to the flow rate and temperature disturbances. The flow rate disturbances typically require a larger manipulation of the flow rates than temperature disturbances. An alternate strategy examines the control of the cold outlet temperature of the SHX (T_c_o) only, since this temperature provides the driving force for energy production in the power conversion unit or the process application. The control can be achieved by three options: (1) flow rate manipulation; (2) reactor power manipulation; or (3) a combination of the two. The first option has a quicker response but requires a large flow rate change. The second option is the slowest but does not involve any change in the flow rates of streams. The third option appears preferable as it has an intermediate response time and requires only a minimal flow rate change

  19. Reduction of intergranular exchange coupling and grain size for high Ku CoPt-based granular media: Metal-oxide buffer layer and multiple oxide boundary materials

    Directory of Open Access Journals (Sweden)

    Kim Kong Tham

    2018-05-01

    Full Text Available Investigation of magnetic properties and microstructure of granular media with various multiple oxides as the grain boundary material is reported. Saturation magnetization (Ms, uniaxial magnetocrystalline anisotropy (Ku, and magnetic grain diameter (GD of the granular media show linear correlation with volume weighted average for melting point (Tm of each oxides (Tmave. Ku of magnetic grains (Kugrain shows a trade-off relation with GD that it is a big challenge to satisfy both high Kugrain and small GD by only controlling Tmave. To obtain a granular medium with appropriate Kugrain, GD, and low degree of intergranular exchange coupling, the combination of Tmave control of grain boundary material by mixing oxides and employment of a buffer layer are required. Here the degree of intergranular exchange coupling is estimated from the slope of M-H loop at around coercivity (α. By applying this technique, a typical granular medium with Kugrain of 1.0×107 erg/cm3, GD of 5.1 nm, and α of 1.2 is realized.

  20. Influence of ligand-bridged substitution on the exchange coupling constant of chromium-wheels host complexes: a density functional theory study

    Science.gov (United States)

    Sadeghi Googheri, Motahare; Abolhassani, Mohammad Reza; Mirzaei, Mahmoud

    2018-05-01

    Designing and introducing novel wheel-shaped supramolecular as host complexes with new magnetic properties is the theme of the day. So in this study, new eight binuclear chromium (III) complexes, as models of real chromium-wheel host complexes, were designed based on changing of bridged-ligands and exchange coupling constants (J) of them were calculated using the broken symmetry density functional theory approach. Substitution of fluorine ligand in fluoro-bridged model [Cr2F(tBuCO2)2(H2O)2(OH)4]-1 by halogen anions (Cl-, Br- and I- ) decreased the antiferromagnetic exchange coupling between Cr(III) centres such that by going from F- to I- the J values became more positive. In the case of hydroxo-bridged model [Cr2OH(tBuCO2)2(H2O)2(OH)4]-1, replacement of hydroxyl by methoxy anion (OMe-) strengthened the antiferromagnetic property of the complex but substitution by sulfanide (SH-) and amide (NH2-) anions weakened it and changed the nature of complexes to ferromagnetic. Because of their different magnetic properties, these new investigated complexes can be suggested as interesting synthetic targets. Also, the J value changes due to ligand substitution were evaluated and it was found that the Cr-X bond strength and partial charges of involved atoms were the most effective factors on it.

  1. Reduction of intergranular exchange coupling and grain size for high Ku CoPt-based granular media: Metal-oxide buffer layer and multiple oxide boundary materials

    Science.gov (United States)

    Tham, Kim Kong; Kushibiki, Ryosuke; Kamada, Tomonari; Hinata, Shintaro; Saito, Shin

    2018-05-01

    Investigation of magnetic properties and microstructure of granular media with various multiple oxides as the grain boundary material is reported. Saturation magnetization (Ms), uniaxial magnetocrystalline anisotropy (Ku), and magnetic grain diameter (GD) of the granular media show linear correlation with volume weighted average for melting point (Tm) of each oxides (Tmave). Ku of magnetic grains (Kugrain) shows a trade-off relation with GD that it is a big challenge to satisfy both high Kugrain and small GD by only controlling Tmave. To obtain a granular medium with appropriate Kugrain, GD, and low degree of intergranular exchange coupling, the combination of Tmave control of grain boundary material by mixing oxides and employment of a buffer layer are required. Here the degree of intergranular exchange coupling is estimated from the slope of M-H loop at around coercivity (α). By applying this technique, a typical granular medium with Kugrain of 1.0×107 erg/cm3, GD of 5.1 nm, and α of 1.2 is realized.

  2. Giant Negative Magnetoresistance Driven by Spin-Orbit Coupling at the LaAlO3/SrTiO3 Interface.

    Science.gov (United States)

    Diez, M; Monteiro, A M R V L; Mattoni, G; Cobanera, E; Hyart, T; Mulazimoglu, E; Bovenzi, N; Beenakker, C W J; Caviglia, A D

    2015-07-03

    The LaAlO3/SrTiO3 interface hosts a two-dimensional electron system that is unusually sensitive to the application of an in-plane magnetic field. Low-temperature experiments have revealed a giant negative magnetoresistance (dropping by 70%), attributed to a magnetic-field induced transition between interacting phases of conduction electrons with Kondo-screened magnetic impurities. Here we report on experiments over a broad temperature range, showing the persistence of the magnetoresistance up to the 20 K range--indicative of a single-particle mechanism. Motivated by a striking correspondence between the temperature and carrier density dependence of our magnetoresistance measurements we propose an alternative explanation. Working in the framework of semiclassical Boltzmann transport theory we demonstrate that the combination of spin-orbit coupling and scattering from finite-range impurities can explain the observed magnitude of the negative magnetoresistance, as well as the temperature and electron density dependence.

  3. Spin- and valley-dependent electronic band structure and electronic heat capacity of ferromagnetic silicene in the presence of strain, exchange field and Rashba spin-orbit coupling

    Science.gov (United States)

    Hoi, Bui Dinh; Yarmohammadi, Mohsen; Kazzaz, Houshang Araghi

    2017-10-01

    We studied how the strain, induced exchange field and extrinsic Rashba spin-orbit coupling (RSOC) enhance the electronic band structure (EBS) and electronic heat capacity (EHC) of ferromagnetic silicene in presence of external electric field (EF) by using the Kane-Mele Hamiltonian, Dirac cone approximation and the Green's function approach. Particular attention is paid to investigate the EHC of spin-up and spin-down bands at Dirac K and K‧ points. We have varied the EF, strain, exchange field and RSOC to tune the energy of inter-band transitions and consequently EHC, leading to very promising features for future applications. Evaluation of EF exhibits three phases: Topological insulator (TI), valley-spin polarized metal (VSPM) and band insulator (BI) at given aforementioned parameters. As a new finding, we have found a quantum anomalous Hall phase in BI regime at strong RSOCs. Interestingly, the effective mass of carriers changes with strain, resulting in EHC behaviors. Here, exchange field has the same behavior with EF. Finally, we have confirmed the reported and expected symmetry results for both Dirac points and spins with the study of valley-dependent EHC.

  4. Interface exchange parameters in La{sub 2/3}Ca{sub 1/3}Mn{sub 3}O/La{sub 1/3}Ca{sub 2/3}Mn{sub 3}O bilayers: a Monte Carlo approach

    Energy Technology Data Exchange (ETDEWEB)

    Restrepo-Parra, E., E-mail: erestrepopa@unal.edu.co [Universidad Nacional de Colombia-Sede Manizales, PCM Computational Applications, Manizales (Colombia); Londoño-Navarro, J. [Universidad Nacional de Colombia-Sede Manizales, PCM Computational Applications, Manizales (Colombia); Restrepo, J. [Grupo de Magnetismo y Simulación. Instituto de Física. Universidad de Antioquia. A.A. 1226, Medellín (Colombia)

    2013-10-15

    Ferromagnetic/antiferromagnetic (FM/AF) bilayers have been widely studied because they exhibit special phenomena, such as exchange bias and magnetoresistance. These effects are strongly influenced by interface behavior. In this work, a study of hysteresis loops in La{sub 2/3}Ca{sub 1/3}MnO{sub 3}/La{sub 1/3}Ca{sub 2/3}MnO{sub 3} bilayers is presented. Simulations were carried out using the Monte Carlo method combined with the Metropolis algorithm and Heisenberg model. The study was focused on determining the most suitable exchange parameters at the interface by applying the model proposed by Kiwi. This model considers the use of two interface exchange parameters to represent the anisotropy that occurs at the interface because of the contact between two phases (ferromagnetic and antiferromagnetic). These two interface exchange parameters were named J{sub I1} and J{sub I2}. Initially, we assumed J{sub I1} to be equal to J{sub I2} without presenting exchange bias. Then, J{sub I1} and J{sub I2} were assumed to be different. In this configuration, the exchange phenomenon appeared in the hysteresis loops. It was also observed that the exchange bias is strongly dependent on the ratio of J{sub I1} to J{sub I2}. As J{sub I1} increases, the exchange bias decreases slowly and becomes comparable to the effective exchange bias field, assuming that it only depends on ΔJ{sub I}=J{sub I1}−J{sub I2}. - Highlights: • Exchange bias is influenced by the type of interaction ions and exchange parameters. • An interface asymmetric is required for observing the exchange bias phenomenon. • Monte Carlo method allows simulating the exchange bias phenomenon in FM/AF systems.

  5. Sheath liquid interface for the coupling of normal-phase liquid chromatography with electrospray mass spectrometry and its application to the analysis of neoflavonoids.

    Science.gov (United States)

    Charles, Laurence; Laure, Frédéric; Raharivelomanana, Phila; Bianchini, Jean-Pierre

    2005-01-01

    A novel interface that allows normal-phase liquid chromatography to be coupled with electrospray ionization (ESI) is reported. A make-up solution of 60 mM ammonium acetate in methanol, infused at a 5 microl min(-1) flow-rate at the tip of the electrospray probe, provides a sheath liquid which is poorly miscible with the chromatographic effluent, but promotes efficient ionization of the targeted analytes. Protonated molecules generated in the ESI source were subjected to tandem mass spectrometric experiments in a triple-quadrupole mass spectrometer. The main fragmentation reactions were characterized for each analyte and specific mass spectral transitions were used to acquire chromatographic data in the multiple reaction monitoring detection mode. Results obtained during optimization of the sheath liquid composition and flow-rate suggest that the electrospray process was mainly under the control of the make-up solution, and that it forms an external charged layer around a neutral chromatographic mobile phase core. This sheath liquid interface was implemented for the analysis of some neoflavonoid compounds and its performance was evaluated. Limits of detection were established for calophillolide, inophyllum B, inophyllum P and inophyllum C at 100, 25, 15 and 100 ng ml(-1), respectively.

  6. A comprehensive study of the electrically conducting water based CuO and Al2O3 nanoparticles over coupled nanofluid-sheet interface

    International Nuclear Information System (INIS)

    Ahmad, R

    2016-01-01

    Many studies on nanofluid flow over a permeable/impermeable sheet prescribe the kinematics of the sheet and disregard the sheet’s mechanics. However, the current study is one of the infrequent contributions that anticipate the mechanics of both the electrically conducting nanofluid (a homogeneous mixture of nanoparticles and base fluid) and the sheet. Two types of nanoparticles, alumina and copper, with water as a base fluid over the sheet are considered. With the help of the similarity transformations, the corresponding partial differential equations for the coupled nanofluid-sheet interface are transformed into a system of ordinary differential equations. The simulations are done by using the experimentally verified results from the previous studies for viscosity and thermal conductivity. Self-similar solutions are attained by considering both analytical and numerical techniques. Dual skin friction coefficients are attained with different copper and alumina nanoparticles over both the stretching and viscous sheets. The influence of the Eckert number, magnetic and mass suction/blowing parameters on the dimensionless velocity, temperature, skin friction and heat transfer rates over the nanofluid-sheet interface are presented graphically as well as numerically. The obtained results are of potential benefit for studying nanofluid flow over various soft surfaces such as synthetic plastics, soft silicone sheet and soft synthetic rubber sheet. These surfaces are easily deformed by thermal fluctuations. (paper)

  7. Defect assisted coupling of a MoS2/TiO2 interface and tuning of its electronic structure.

    Science.gov (United States)

    Chen, Guifeng; Song, Xiaolin; Guan, Lixiu; Chai, Jianwei; Zhang, Hui; Wang, Shijie; Pan, Jisheng; Tao, Junguang

    2016-09-02

    Although MoS2 based heterostructures have drawn increased attention, the van der Waals forces within MoS2 layers make it difficult for the layers to form strong chemical coupled interfaces with other materials. In this paper, we demonstrate the successful strong chemical attachment of MoS2 on TiO2 nanobelts after appropriate surface modifications. The etch-created dangling bonds on TiO2 surfaces facilitate the formation of a steady chemically bonded MoS2/TiO2 interface. With the aid of high resolution transmission electron microscope measurements, the in-plane structure registry of MoS2/TiO2 is unveiled at the atomic scale, which shows that MoS2[1-10] grows along the direction of TiO2[001] and MoS2[110] parallel to TiO2[100] with every six units of MoS2 superimposed on five units of TiO2. Electronically, type II band alignments are realized for all surface treatments. Moreover, the band offsets are delicately correlated to the surface states, which plays a significant role in their photocatalytic performance.

  8. Interface magnons. Magnetic superstructure

    International Nuclear Information System (INIS)

    Djafari-Rouhani, B.; Dobrzynski, L.

    1975-01-01

    The localized magnons at an interface between two Heisenberg ferromagnets are studied with a simple model. The effect of the coupling at the interface on the existence condition for the localized modes, the dispersion laws and the possible occurrence of magnetic superstructures due to soft modes are investigated. Finally a comparison is made with the similar results obtained for interface phonons [fr

  9. Extraction of butyltins from sediments and their determination by liquid chromatography interfaced to inductively coupled plasma atomic emission detector

    International Nuclear Information System (INIS)

    Rivaro, P.; Frache, R.

    2000-01-01

    A liquid-liquid extraction of the butyltin compounds from sediment, suitable for their subsequent following determination by high performance liquid chromatography-hydride generation inductively coupled plasma atomic emission detector system, is proposed. Recoveries of 86%, 80% and 42% for tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT) respectively were achieved. The relative detection limits of butyltin compounds by this method ranged from 27 to 62 ng of tin per gram of dry sediment. The method was applied to real sediment samples collected in the Venice lagoon (Italy). The results showed that, despite the restrictions on the use of butyltin contained in antifoulting paints, a considerable amount of organotin compounds is still present in Venice sediments [it

  10. Modeling and calculation of RKKY exchange coupling to explain Ti-vacancy-induced ferromagnetism in Ta-doped TiO2

    Science.gov (United States)

    Majidi, Muhammad Aziz; Bupu, Annamaria; Fauzi, Angga Dito

    2017-12-01

    We present a theoretical study on Ti-vacancy-induced ferromagnetism in anatase TiO2. A recent experimental study has revealed room temperature ferromagnetism in Ta-doped anatase TiO2thin films (Rusydi et al., 2012) [7]. Ta doping assists the formation of Ti vacancies which then induce the formation of localized magnetic moments around the Ti vacancies. As neighboring Ti vacancies are a few unit cells apart, the ferromagnetic order is suspected to be mediated by itinerant electrons. We propose that such an electron-mediated ferromagnetism is driven by Ruderman-Kittel-Kasuya-Yosida (RKKY) exchange interaction. To examine our hypothesis, we construct a tight-binding based model Hamiltonian for the anatase TiO2 system. We calculate the RKKY exchange coupling constant of TiO2 as a function of distance between local magnetic moments at various temperatures. We model the system by taking only the layer containing a unit of TiO2, at which the Ti vacancy is believed to form, as our effective two-dimensional unit cell. Our model incorporates the Hubbard repulsive interactions between electrons occupying Ti d orbitals treated within mean-field approximation. The density of states profile resulting from the model captures the relevant electronic properties of TiO2, such as the energy gap of 3.4 eV and the n-type character, which may be a measure of the adequacy of the model. The calculated RKKY coupling constant shows that the ferromagnetic coupling extends up to 3-4 unit cells and enhances slightly as temperature is increased from 0 to 400 K. These results support our hypothesis that the ferromagnetism of this system is driven by RKKY mechanism.

  11. Development of a Microfluidic Open Interface with Flow Isolated Desorption Volume for the Direct Coupling of SPME Devices to Mass Spectrometry.

    Science.gov (United States)

    Tascon, Marcos; Alam, Md Nazmul; Gómez-Ríos, Germán Augusto; Pawliszyn, Janusz

    2018-02-20

    Technologies that efficiently integrate the sampling and sample preparation steps with direct introduction to mass spectrometry (MS), providing simple and sensitive analytical workflows as well as capabilities for automation, can generate a great impact in a vast variety of fields, such as in clinical, environmental, and food-science applications. In this study, a novel approach that facilitates direct coupling of Bio-SPME devices to MS using a microfluidic design is presented. This technology, named microfluidic open interface (MOI), which operates under the concept of flow-isolated desorption volume, consists of an open-to-ambient desorption chamber (V ≤ 7 μL) connected to an ionization source. Subsequently, compounds of interest are transported to the ionization source by means of the self-aspiration process intrinsic of these interfaces. Thus, any ionization technology that provides a reliable and constant suction, such as electrospray ionization (ESI), atmospheric-pressure chemical ionization (APCI), or inductively coupled plasma ionization (ICP), can be hyphenated to MOI. Using this setup, the desorption chamber is used to release target compounds from the coating, while the isolation of the flow enables the ionization source to be continuously fed with solvent, all without the necessity of employment of additional valves. As a proof of concept, the design was applied to an ESI-MS/MS system for experimental validation. Furthermore, numerical simulations were undertaken to provide a detailed understanding of the fluid flow pattern inside the interface, then used to optimize the system for better efficiency. The analytical workflow of the developed Bio-SPME-MOI-MS setup consists of the direct immersion of SPME fibers into the matrix to extract/enrich analytes of interest within a short period of time, followed by a rinsing step with water to remove potentially adhering proteins, salts, and/or other interfering compounds. Next, the fiber is inserted into the

  12. Amorphous FeCoSiB for exchange bias coupled and decoupled magnetoelectric multilayer systems: Real-structure and magnetic properties

    International Nuclear Information System (INIS)

    Hrkac, V.; Strobel, J.; Kienle, L.; Lage, E.; Köppel, G.; McCord, J.; Quandt, E.; Meyners, D.

    2014-01-01

    The effect of field annealing for exchanged biased multilayer films is studied with respect to the resultant structural and magnetic film properties. The presented multilayer stacks comprise repeating sequences of Ta/Cu/(1 1 1) textured antiferromagnetic Mn 70 Ir 30 /amorphous ferromagnetic Fe 70.2 Co 7.8 Si 12 B 10 . Within the ferromagnetic layers crystalline filaments are observed. An additional Ta layer between the antiferromagnet and ferromagnet is used in order to investigate and separate the influence of the common Mn 70 Ir 30 /Fe 70.2 Co 7.8 Si 12 B 10 interface on the occurring filaments and structural changes. In situ and ex situ transmission electron microscopy is used for a comprehensive structure characterization of multilayer stacks for selected temperature stages. Up to 250 °C, the multilayers are structurally unaltered and preserve the as-deposited condition. A deliberate increase to 350 °C exhibits different crystallization processes for the films, depending on the presence of crystal nuclei within the amorphous ferromagnetic layer. The influence of volume-to-surface ratio of the multilayer stacks to the crystallization process is emphasized by the comparison of in situ and ex situ investigations as the respective specimen thickness is changed. Complementary magnetic studies reveal a defined exchange bias obtained at the first annealing step and a decrease of total anisotropy field with partial crystallization after the subsequent annealing at 350 °C.

  13. Use of phase-locking value in sensorimotor rhythm-based brain-computer interface: zero-phase coupling and effects of spatial filters.

    Science.gov (United States)

    Jian, Wenjuan; Chen, Minyou; McFarland, Dennis J

    2017-11-01

    Phase-locking value (PLV) is a potentially useful feature in sensorimotor rhythm-based brain-computer interface (BCI). However, volume conduction may cause spurious zero-phase coupling between two EEG signals and it is not clear whether PLV effects are independent of spectral amplitude. Volume conduction might be reduced by spatial filtering, but it is uncertain what impact this might have on PLV. Therefore, the goal of this study was to explore whether zero-phase PLV is meaningful and how it is affected by spatial filtering. Both amplitude and PLV feature were extracted in the frequency band of 10-15 Hz by classical methods using archival EEG data of 18 subjects trained on a two-target BCI task. The results show that with right ear-referenced data, there is meaningful long-range zero-phase synchronization likely involving the primary motor area and the supplementary motor area that cannot be explained by volume conduction. Another novel finding is that the large Laplacian spatial filter enhances the amplitude feature but eliminates most of the phase information seen in ear-referenced data. A bipolar channel using phase-coupled areas also includes both phase and amplitude information and has a significant practical advantage since fewer channels required.

  14. Coupling brain-machine interfaces with cortical stimulation for brain-state dependent stimulation: enhancing motor cortex excitability for neurorehabilitation

    Directory of Open Access Journals (Sweden)

    Alireza eGharabaghi

    2014-03-01

    Full Text Available Motor recovery after stroke is an unsolved challenge despite intensive rehabilitation training programs. Brain stimulation techniques have been explored in addition to traditional rehabilitation training to increase the excitability of the stimulated motor cortex. This modulation of cortical excitability augments the response to afferent input during motor exercises, thereby enhancing skilled motor learning by long-term potentiation-like plasticity. Recent approaches examined brain stimulation applied concurrently with voluntary movements to induce more specific use-dependent neural plasticity during motor training for neurorehabilitation. Unfortunately, such approaches are not applicable for the many severely affected stroke patients lacking residual hand function. These patients require novel activity-dependent stimulation paradigms based on intrinsic brain activity. Here, we report on such brain state-dependent stimulation (BSDS combined with haptic feedback provided by a robotic hand orthosis. Transcranial magnetic stimulation of the motor cortex and haptic feedback to the hand were controlled by sensorimotor desynchronization during motor-imagery and applied within a brain-machine interface environment in one healthy subject and one patient with severe hand paresis in the chronic phase after stroke. BSDS significantly increased the excitability of the stimulated motor cortex in both healthy and post-stroke conditions, an effect not observed in non-BSDS protocols. This feasibility study suggests that closing the loop between intrinsic brain state, cortical stimulation and haptic feedback provides a novel neurorehabilitation strategy for stroke patients lacking residual hand function, a proposal that warrants further investigation in a larger cohort of stroke patients.

  15. Study of coupled heat and water transfer in proton exchange membrane fuel cells by the way of internal measurements

    International Nuclear Information System (INIS)

    Thomas, A; Maranzana, G; Didierjean, S; Dillet, J; Lottin, O

    2012-01-01

    Measurements of electrode temperatures within a proton exchange membrane fuel cell were performed using platinum wires. A temperature difference of 7°C between the electrodes and the bipolar plates was observed for a cell operating at a current density of 1.5 A.cm −2 . These measurements show a strong non-uniformity of the temperature profile through membrane electrode assembly (MEA) that future phenomenological models must take into account. In addition, the simultaneous measurements of heat and water flux through the MEA leads to the conclusion that produced water crosses the diffusion layer in vapor phase. A very simple heat transfer model is proposed.

  16. Universal set of quantum gates for double-dot exchange-only spin qubits with intradot coupling

    International Nuclear Information System (INIS)

    Michielis, M De; Ferraro, E; Fanciulli, M; Prati, E

    2015-01-01

    We present a universal set of quantum gate operations based on exchange-only spin qubits in a double quantum dot, where each qubit is obtained by three electrons in the (2,1) filling. Gate operations are addressed by modulating electrostatically the tunneling barrier and the energy offset between the two dots, singly and doubly occupied respectively. We propose explicit gate sequences of single qubit operations for arbitrary rotations, and the two-qubit controlled NOT gate, to complete the universal set. The unswitchable interaction between the two electrons of the doubly occupied quantum dot is taken into account. Short gate times are obtained by employing spin density functional theory simulations. (paper)

  17. Exchange coupling and magnetic anisotropy in a family of bipyrimidyl radical-bridged dilanthanide complexes: density functional theory and ab initio calculations.

    Science.gov (United States)

    Zhang, Yi-Quan; Luo, Cheng-Lin; Zhang, Qiang

    2014-05-05

    The origin of the magnetic anisotropy energy barriers in a series of bpym(-) (bpym = 2,2'-bipyrimidine) radical-bridged dilanthanide complexes [(Cp*2Ln)2(μ-bpym)](+) [Cp* = pentamethylcyclopentadienyl; Ln = Gd(III) (1), Tb(III) (2), Dy(III) (3), Ho(III) (4), Er(III) (5)] has been explored using density functional theory (DFT) and ab initio methods. DFT calculations show that the exchange coupling between the two lanthanide ions for each complex is very weak, but the antiferromagnetic Ln-bpym(-) couplings are strong. Ab initio calculations show that the effective energy barrier of 2 or 3 mainly comes from the contribution of a single Tb(III) or Dy(III) fragment, which is only about one third of a single Ln energy barrier. For 4 or 5, however, both of the two Ho(III) or Er(III) fragments contribute to the total energy barrier. Thus, it is insufficient to only increase the magnetic anisotropy energy barrier of a single Ln ion, while enhancing the Ln-bpym(-) couplings is also very important. Copyright © 2014 Wiley Periodicals, Inc.

  18. Interface strain coupling and its impact on the transport and magnetic properties of LaMnO3 thin films grown on ferroelectrically active substrates

    International Nuclear Information System (INIS)

    Zheng, R.K.; Wang, Y.; Habermeier, H.-U.; Chan, H.L.W.; Li, X.M.; Luo, H.S.

    2012-01-01

    Highlights: ► Strong interface strain coupling in LaMnO 3 /PMN-PT heterostructure. ► In situ dynamic turning of the strain and lattice distortion of LaMnO 3 films. ► Coupling of electrons to lattice strain is crucial to understand the strain effect. - Abstract: Thin films of LaMnO 3 have been epitaxially grown on 〈0 0 1〉 oriented ferroelectric 0.67Pb(Mg 1/3 Nb 2/3 )O 3 -0.33PbTiO 3 (PMN-PT) single-crystal substrates. The poling of the PMN-PT crystal causes a decrease in the resistance and an increase in the magnetization and magnetoresistance of the LaMnO 3 film. In situ X-ray diffraction measurements revealed that these changes arise from the poling-induced strain in the PMN-PT substrate, which reduces the in-plane tensile strain and the Jahn–Teller (JT) distortion of MnO 6 octahedra of the LaMnO 3 film. Moreover, it was found that the transport properties of LaMnO 3 films are much more sensitive to the poling-induced strain than that of CaMnO 3 films for which there is no JT distortion, implying that the electron–lattice coupling is one of the most important ingredients in understanding the strain effect in LaMnO 3 films.

  19. Unravelling the tunable exchange bias-like effect in magnetostatically-coupled two dimensional hybrid (hard/soft) composites

    International Nuclear Information System (INIS)

    Hierro-Rodriguez, A; Teixeira, J M; Rodriguez-Rodriguez, G; Rubio, H; Vélez, M; Álvarez-Prado, L M; Martín, J I; Alameda, J M

    2015-01-01

    Hybrid 2D hard-soft composites have been fabricated by combining soft (Co 73 Si 27 ) and hard (NdCo 5 ) magnetic materials with in-plane and out-of-plane magnetic anisotropies, respectively. They have been microstructured in a square lattice of CoSi anti-dots with NdCo dots within the holes. The magnetic properties of the dots allow us to introduce a magnetostatic stray field that can be controlled in direction and sense by their last saturating magnetic field. The magnetostatic interactions between dot and anti-dot layers induce a completely tunable exchange bias-like shift in the system’s hysteresis loops. Two different regimes for this shift are present depending on the lattice parameter of the microstructures. For large parameters, dipolar magnetostatic decay is observed, while for the smaller one, the interaction between the adjacent anti-dot’s characteristic closure domain structures enhances the exchange bias-like effect as clarified by micromagnetic simulations. (paper)

  20. Supercritical fluid chromatography coupled with in-source atmospheric pressure ionization hydrogen/deuterium exchange mass spectrometry for compound speciation.

    Science.gov (United States)

    Cho, Yunju; Choi, Man-Ho; Kim, Byungjoo; Kim, Sunghwan

    2016-04-29

    An experimental setup for the speciation of compounds by hydrogen/deuterium exchange (HDX) with atmospheric pressure ionization while performing chromatographic separation is presented. The proposed experimental setup combines the high performance supercritical fluid chromatography (SFC) system that can be readily used as an inlet for mass spectrometry (MS) and atmospheric pressure photo ionization (APPI) or atmospheric pressure chemical ionization (APCI) HDX. This combination overcomes the limitation of an approach using conventional liquid chromatography (LC) by minimizing the amount of deuterium solvents used for separation. In the SFC separation, supercritical CO2 was used as a major component of the mobile phase, and methanol was used as a minor co-solvent. By using deuterated methanol (CH3OD), AP HDX was achieved during SFC separation. To prove the concept, thirty one nitrogen- and/or oxygen-containing standard compounds were analyzed by SFC-AP HDX MS. The compounds were successfully speciated from the obtained SFC-MS spectra. The exchange ions were observed with as low as 1% of CH3OD in the mobile phase, and separation could be performed within approximately 20min using approximately 0.24 mL of CH3OD. The results showed that SFC separation and APPI/APCI HDX could be successfully performed using the suggested method. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Assessing the performance of the random phase approximation for exchange and superexchange coupling constants in magnetic crystalline solids

    DEFF Research Database (Denmark)

    Olsen, Thomas

    2017-01-01

    The random phase approximation (RPA) for total energies has previously been shown to provide a qualitatively correct description of static correlation in molecular systems, where density functional theory (DFT) with local functionals are bound to fail. This immediately poses the question of whether...... the RPA is also able to capture the correct physics of strongly correlated solids such asMott insulators. Due to strong electron localization, magnetic interactions in such systems are dominated by superexchange, which in the simplest picture can be regarded as the analog of static correlation...... for molecules. In this paper, we investigate the performance of the RPA for evaluating both superexchange and direct exchange interactions in the magnetic solids NiO, MnO, Na3Cu2SbO6, Sr2CuO3, Sr2CuTeO6, and a monolayer of CrI3, which were chosen to represent a broad variety of magnetic interactions...

  2. Exchange bias and asymmetric hysteresis loops from a microscopic model of core/shell nanoparticles

    International Nuclear Information System (INIS)

    Iglesias, Oscar; Batlle, Xavier; Labarta, Amilcar

    2007-01-01

    We present Monte Carlo simulations of hysteresis loops of a model of a magnetic nanoparticle with a ferromagnetic core and an antiferromagnetic shell with varying values of the core/shell interface exchange coupling which aim to clarify the microscopic origin of exchange bias observed experimentally. We have found loop shifts in the field direction as well as displacements along the magnetization axis that increase in magnitude when increasing the interfacial exchange coupling. Overlap functions computed from the spin configurations along the loops have been obtained to explain the origin and magnitude of these features microscopically

  3. Interface-Induced Phenomena in Magnetism.

    Science.gov (United States)

    Hellman, Frances; Hoffmann, Axel; Tserkovnyak, Yaroslav; Beach, Geoffrey S D; Fullerton, Eric E; Leighton, Chris; MacDonald, Allan H; Ralph, Daniel C; Arena, Dario A; Dürr, Hermann A; Fischer, Peter; Grollier, Julie; Heremans, Joseph P; Jungwirth, Tomas; Kimel, Alexey V; Koopmans, Bert; Krivorotov, Ilya N; May, Steven J; Petford-Long, Amanda K; Rondinelli, James M; Samarth, Nitin; Schuller, Ivan K; Slavin, Andrei N; Stiles, Mark D; Tchernyshyov, Oleg; Thiaville, André; Zink, Barry L

    2017-01-01

    This article reviews static and dynamic interfacial effects in magnetism, focusing on interfacially-driven magnetic effects and phenomena associated with spin-orbit coupling and intrinsic symmetry breaking at interfaces. It provides a historical background and literature survey, but focuses on recent progress, identifying the most exciting new scientific results and pointing to promising future research directions. It starts with an introduction and overview of how basic magnetic properties are affected by interfaces, then turns to a discussion of charge and spin transport through and near interfaces and how these can be used to control the properties of the magnetic layer. Important concepts include spin accumulation, spin currents, spin transfer torque, and spin pumping. An overview is provided to the current state of knowledge and existing review literature on interfacial effects such as exchange bias, exchange spring magnets, spin Hall effect, oxide heterostructures, and topological insulators. The article highlights recent discoveries of interface-induced magnetism and non-collinear spin textures, non-linear dynamics including spin torque transfer and magnetization reversal induced by interfaces, and interfacial effects in ultrafast magnetization processes.

  4. Pentacene appended to a TEMPO stable free radical: the effect of magnetic exchange coupling on photoexcited pentacene.

    Science.gov (United States)

    Chernick, Erin T; Casillas, Rubén; Zirzlmeier, Johannes; Gardner, Daniel M; Gruber, Marco; Kropp, Henning; Meyer, Karsten; Wasielewski, Michael R; Guldi, Dirk M; Tykwinski, Rik R

    2015-01-21

    Understanding the fundamental spin dynamics of photoexcited pentacene derivatives is important in order to maximize their potential for optoelectronic applications. Herein, we report on the synthesis of two pentacene derivatives that are functionalized with the [(2,2,6,6-tetramethylpiperidin-1-yl)oxy] (TEMPO) stable free radical. The presence of TEMPO does not quench the pentacene singlet excited state, but does quench the photoexcited triplet excited state as a function of TEMPO-to-pentacene distance. Time-resolved electron paramagnetic resonance experiments confirm that triplet quenching is accompanied by electron spin polarization transfer from the pentacene excited state to the TEMPO doublet state in the weak coupling regime.

  5. Estimating the Mean Circulation and Water Exchange of the Gulf of Suez-Red Sea via a Validated One-Way Atmospheric-Hydrodynamic Coupled Model

    Science.gov (United States)

    Eladawy, Ahmed; Shaltout, Mohamed; Sousa, Magda Catarina; Dias, João Miguel; Nadaoka, Kazuo

    2018-05-01

    The Gulf of Suez, Northern Islands protected area, and Hurghada zone are experiencing mega developments in all sectors including tourism, industry, and logistics. The need for moderately accurate near-shore hydrodynamic models is increasing to support the sustainable development of this oceanic area. This can be accomplished by following a nesting approach including the downscaling of global atmospheric and oceanic models into local models using higher resolution datasets. This work aims to present the development of a one-way coupling between atmospheric and hydrodynamic models for the Gulf of Suez (GOS) to understand the local oceanic characteristics and processes. The Regional Climate Model system (RegCM4) is used to simulate moderate resolution atmospheric features and its results are used to force a local dedicated application of Delft3D model. The results indicate that the predicted water level, water temperature, and evaporation accurately follow in situ measurements, remotely sensed data, and re-analysis data. The results suggest that the annual sea surface temperature is averaged at 23 °C, while the annual average of evaporation rates equals 8.02 mm/day. The study suggests that the water level displays a marked seasonal and spatial variation. Moreover, the water balance in the Gulf of Suez was controlled by the difference between inflows and outflows through the Straits of Gubal and by the net precipitation. In addition, the water balance indicated a net loss of approximately 3.9 × 10-3 m of water during 2013. Moreover, the exchange through the Straits of Gubal showed a two-way exchange with a net inflow of 0.0007 Sv, where the outflow dominated in the surface layer along the western coast and the inflow dominated in the lower layers along the middle of the Straits. To conclude, the one-way coupling modeling technique proved to be a reliable tool for studying local features of the GOS region.

  6. Nuclear magnetic relaxation induced by exchange-mediated orientational randomization: longitudinal relaxation dispersion for a dipole-coupled spin-1/2 pair.

    Science.gov (United States)

    Chang, Zhiwei; Halle, Bertil

    2013-10-14

    In complex biological or colloidal samples, magnetic relaxation dispersion (MRD) experiments using the field-cycling technique can characterize molecular motions on time scales ranging from nanoseconds to microseconds, provided that a rigorous theory of nuclear spin relaxation is available. In gels, cross-linked proteins, and biological tissues, where an immobilized macromolecular component coexists with a mobile solvent phase, nuclear spins residing in solvent (or cosolvent) species relax predominantly via exchange-mediated orientational randomization (EMOR) of anisotropic nuclear (electric quadrupole or magnetic dipole) couplings. The physical or chemical exchange processes that dominate the MRD typically occur on a time scale of microseconds or longer, where the conventional perturbation theory of spin relaxation breaks down. There is thus a need for a more general relaxation theory. Such a theory, based on the stochastic Liouville equation (SLE) for the EMOR mechanism, is available for a single quadrupolar spin I = 1. Here, we present the corresponding theory for a dipole-coupled spin-1/2 pair. To our knowledge, this is the first treatment of dipolar MRD outside the motional-narrowing regime. Based on an analytical solution of the spatial part of the SLE, we show how the integral longitudinal relaxation rate can be computed efficiently. Both like and unlike spins, with selective or non-selective excitation, are treated. For the experimentally important dilute regime, where only a small fraction of the spin pairs are immobilized, we obtain simple analytical expressions for the auto-relaxation and cross-relaxation rates which generalize the well-known Solomon equations. These generalized results will be useful in biophysical studies, e.g., of intermittent protein dynamics. In addition, they represent a first step towards a rigorous theory of water (1)H relaxation in biological tissues, which is a prerequisite for unravelling the molecular basis of soft

  7. 3D numerical simulation of fluid–solid coupled heat transfer with variable property in a LBE-helium heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Fei, E-mail: chenfei@iet.cn [Institute of Engineering Thermophysics, Chinese Academy of Sciences, 11 Beisihuanxi Road, Beijing 100190 (China); North China University of Water Resources and Electric Power, 36 Beihuan Road, Zhengzhou, Henan 450011 (China); Cai, Jun, E-mail: caijun@iet.cn [Institute of Engineering Thermophysics, Chinese Academy of Sciences, 11 Beisihuanxi Road, Beijing 100190 (China); Li, Xunfeng, E-mail: lixunfeng@iet.cn [Institute of Engineering Thermophysics, Chinese Academy of Sciences, 11 Beisihuanxi Road, Beijing 100190 (China); Huai, Xiulan, E-mail: hxl@iet.cn [Institute of Engineering Thermophysics, Chinese Academy of Sciences, 11 Beisihuanxi Road, Beijing 100190 (China); Wang, Yongwei, E-mail: wangyongwei@iet.cn [Institute of Engineering Thermophysics, Chinese Academy of Sciences, 11 Beisihuanxi Road, Beijing 100190 (China)

    2014-07-01

    Highlights: • Heat transfer in heat exchanger can be improved by increasing helium's flow rate. • The outlet temperature of helium decreases with increasing helium's flow rate. • Balance is necessary between good heat transfer and high helium outlet temperature. - Abstract: LBE-helium experimental loop of ADS (LELA) and LBE-helium heat exchanger have been designed and constructed with the supporting of the “ADS Transmutation System” project of Chinese Academy of Sciences. In order to investigate the flow and heat transfer characteristics between LBE and helium, 3D numerical simulation of fluid–solid coupled heat transfer with variable property in the LBE-helium heat exchanger is conducted in the present study. The effects of mass-flow-rates of helium and LBE in the shell-side and tube-side on the heat transfer performance are addressed. It is found that the heat transfer performance can be significantly improved by increasing helium mass-flow-rate in the shell-side. In order to easily and quickly obtain the outlet temperatures of helium and LBE, a concept of modified effectiveness is introduced and correlated as the function of tube-side to shell-side heat capacity rate ratio. The results show that the outlet temperature of helium decreases with increasing helium mass-flow-rate. Therefore, considering the utilization of high-temperature helium in the future, for example power generation, there should be a tradeoff between good heat transfer performance and high outlet helium temperature when confirming helium mass-flow-rate.

  8. Ion Mobility Spectrometry-Mass Spectrometry Coupled with Gas-Phase Hydrogen/Deuterium Exchange for Metabolomics Analyses

    Science.gov (United States)

    Maleki, Hossein; Karanji, Ahmad K.; Majuta, Sandra; Maurer, Megan M.; Valentine, Stephen J.

    2018-02-01

    Ion mobility spectrometry-mass spectrometry (IMS-MS) in combination with gas-phase hydrogen/deuterium exchange (HDX) and collision-induced dissociation (CID) is evaluated as an analytical method for small-molecule standard and mixture characterization. Experiments show that compound ions exhibit unique HDX reactivities that can be used to distinguish different species. Additionally, it is shown that gas-phase HDX kinetics can be exploited to provide even further distinguishing capabilities by using different partial pressures of reagent gas. The relative HDX reactivity of a wide variety of molecules is discussed in light of the various molecular structures. Additionally, hydrogen accessibility scoring (HAS) and HDX kinetics modeling of candidate ( in silico) ion structures is utilized to estimate the relative ion conformer populations giving rise to specific HDX behavior. These data interpretation methods are discussed with a focus on developing predictive tools for HDX behavior. Finally, an example is provided in which ion mobility information is supplemented with HDX reactivity data to aid identification efforts of compounds in a metabolite extract.

  9. Strong sp-d exchange coupling in ZnMnTe/ZnMgTe core/shell nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Wojnar, Piotr; Janik, Elzbieta; Szymura, Malgorzata; Zaleszczyk, Wojciech; Kret, Slawomir; Klopotowski, Lukasz; Wojciechowski, Tomasz; Baczewski, Lech T.; Wiater, Maciej; Karczewski, Grzegorz; Wojtowicz, Tomasz; Kossut, Jacek [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Suffczynski, Jan; Papierska, Joanna [Institute of Experimental Physics, Warsaw University, ul. Hoza 69, 00-681 Warsaw (Poland)

    2014-07-15

    In this work, our recent progress in the growth and optical studies of telluride nanowire heterostructures containing a small molar fraction of magnetic Mn-ions of only a few percent is overviewed. ZnMnTe/ZnMgTe core/shell nanowires (NWs) are grown by molecular beam epitaxy by employing the vapor-liquid-solid growth mechanism assisted with gold catalyst. The structures are studied by means of photoluminescence and microphotoluminescence in an external magnetic field. In the first step, however, an activation of the near band edge emission from ZnTe and ZnMnTe nanowires is described, which is achieved by coating the nanowires with shells made of ZnMgTe. The role of these shells is to passivate Zn(Mn)Te surface states. The incorporation of Mn ions into the crystalline lattice of ZnMnTe nanowires is manifested as a considerable blue shift of near band edge emission with increasing Mn concentration inside the nanowire cores, which reflects directly the increase of their energy gap. In an external magnetic field the near band edge emission exhibits a giant spectral redshift accompanied by an increase of the circular polarization of the emitted light. Both effect are fingerprints of giant Zeeman splitting of the band edges due to sp-d exchange interaction between the band carriers and magnetic Mn-ions. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Effects of weakly coupled and dense quantum plasmas environments on charge exchange and ionization processes in Na+ + Rb(5s) atom collisions

    Science.gov (United States)

    Pandey, Mukesh Kumar; Lin, Yen-Chang; Ho, Yew Kam

    2017-02-01

    The effects of weakly coupled or classical and dense quantum plasmas environment on charge exchange and ionization processes in Na+ + Rb(5s) atom collision at keV energy range have been investigated using classical trajectory Monte Carlo (CTMC) method. The interaction of three charged particles are described by the Debye-Hückel screen potential for weakly coupled plasma, whereas exponential cosine-screened Coulomb potential have been used for dense quantum plasma environment and the effects of both conditions on the cross sections are compared. It is found that screening effects on cross sections in high Debye length condition is quite small in both plasma environments. However, enhanced screening effects on cross sections are observed in dense quantum plasmas for low Debye length condition, which becomes more effective while decreasing the Debye length. Also, we have found that our calculated results for plasma-free case are comparable with the available theoretical results. These results are analyzed in light of available theoretical data with the choice of model potentials.

  11. Anisotropic diffusion of volatile pollutants at air-water interface

    Directory of Open Access Journals (Sweden)

    Li-ping Chen

    2013-04-01

    Full Text Available The volatile pollutants that spill into natural waters cause water pollution. Air pollution arises from the water pollution because of volatilization. Mass exchange caused by turbulent fluctuation is stronger in the direction normal to the air-water interface than in other directions due to the large density difference between water and air. In order to explore the characteristics of anisotropic diffusion of the volatile pollutants at the air-water interface, the relationship between velocity gradient and mass transfer rate was established to calculate the turbulent mass diffusivity. A second-order accurate smooth transition differencing scheme (STDS was proposed to guarantee the boundedness for the flow and mass transfer at the air-water interface. Simulations and experiments were performed to study the trichloroethylene (C2HCl3 release. By comparing the anisotropic coupling diffusion model, isotropic coupling diffusion model, and non-coupling diffusion model, the features of the transport of volatile pollutants at the air-water interface were determined. The results show that the anisotropic coupling diffusion model is more accurate than the isotropic coupling diffusion model and non-coupling diffusion model. Mass transfer significantly increases with the increase of the air-water relative velocity at a low relative velocity. However, at a higher relative velocity, an increase in the relative velocity has no effect on mass transfer.

  12. A simple method using on-line continuous leaching and ion exchange chromatography coupled to inductively coupled plasma mass spectrometry for the speciation analysis of bio-accessible arsenic in rice.

    Science.gov (United States)

    Horner, Nolan S; Beauchemin, Diane

    2012-03-02

    A simple method for the speciation analysis of bio-accessible arsenic (As) in rice was developed using a continuous on-line leaching method to release the bio-accessible fraction. The continuous on-line leaching method has several advantages over commonly used batch methods including quicker and easier sample preparation, reduced risk of contamination and access to real time leaching data. The bio-accessibility of As in the samples was monitored using inductively coupled plasma mass spectrometry (ICP-MS). Results from a certified reference material as well as cooked and uncooked white rice showed that the majority of As was leached by saliva. Results obtained using the continuous on-line leaching method were comparable to those obtained using a batch method. Speciation analysis of the saliva leachate was performed using ion exchange chromatography coupled to ICP-MS. The four most toxic forms of As (As(III), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and As(V)) were clearly separated within 5 min in a single chromatographic run. Over 92% of bio-accessible As in the certified reference material and uncooked white rice sample was in the form of DMA and As(V), whereas it was present as DMA and As(III) in the cooked white rice. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. H/D exchange mass spectrometry and statistical coupling analysis reveal a role for allostery in a ferredoxin-dependent bifurcating transhydrogenase catalytic cycle.

    Science.gov (United States)

    Berry, Luke; Poudel, Saroj; Tokmina-Lukaszewska, Monika; Colman, Daniel R; Nguyen, Diep M N; Schut, Gerrit J; Adams, Michael W W; Peters, John W; Boyd, Eric S; Bothner, Brian

    2018-01-01

    Recent investigations into ferredoxin-dependent transhydrogenases, a class of enzymes responsible for electron transport, have highlighted the biological importance of flavin-based electron bifurcation (FBEB). FBEB generates biomolecules with very low reduction potential by coupling the oxidation of an electron donor with intermediate potential to the reduction of high and low potential molecules. Bifurcating systems can generate biomolecules with very low reduction potentials, such as reduced ferredoxin (Fd), from species such as NADPH. Metabolic systems that use bifurcation are more efficient and confer a competitive advantage for the organisms that harbor them. Structural models are now available for two NADH-dependent ferredoxin-NADP + oxidoreductase (Nfn) complexes. These models, together with spectroscopic studies, have provided considerable insight into the catalytic process of FBEB. However, much about the mechanism and regulation of these multi-subunit proteins remains unclear. Using hydrogen/deuterium exchange mass spectrometry (HDX-MS) and statistical coupling analysis (SCA), we identified specific pathways of communication within the model FBEB system, Nfn from Pyrococus furiosus, under conditions at each step of the catalytic cycle. HDX-MS revealed evidence for allosteric coupling across protein subunits upon nucleotide and ferredoxin binding. SCA uncovered a network of co-evolving residues that can provide connectivity across the complex. Together, the HDX-MS and SCA data show that protein allostery occurs across the ensemble of iron‑sulfur cofactors and ligand binding sites using specific pathways that connect domains allowing them to function as dynamically coordinated units. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Mechanistic model coupling gas exchange dynamics and Listeria monocytogenes growth in modified atmosphere packaging of non respiring food.

    Science.gov (United States)

    Chaix, E; Broyart, B; Couvert, O; Guillaume, C; Gontard, N; Guillard, V

    2015-10-01

    A mechanistic model coupling O2 and CO2 mass transfer (namely diffusion and solubilisation in the food itself and permeation through the packaging material) to microbial growth models was developed aiming at predicting the shelf life of modified atmosphere packaging (MAP) systems. It was experimentally validated on a non-respiring food by investigating concomitantly the O2/CO2 partial pressure in packaging headspace and the growth of Listeria monocytogenes (average microbial count) within the food sample. A sensitivity analysis has revealed that the reliability of the prediction by this "super-parametrized" model (no less than 47 parameters were required for running one simulation) was strongly dependent on the accuracy of the microbial input parameters. Once validated, this model was used to decipher the role of O2/CO2 mass transfer on microbial growth and as a MAP design tool: an example of MAP dimensioning was provided in this paper as a proof of concept. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. A 3-D functional-structural grapevine model that couples the dynamics of water transport with leaf gas exchange.

    Science.gov (United States)

    Zhu, Junqi; Dai, Zhanwu; Vivin, Philippe; Gambetta, Gregory A; Henke, Michael; Peccoux, Anthony; Ollat, Nathalie; Delrot, Serge

    2017-12-23

    Predicting both plant water status and leaf gas exchange under various environmental conditions is essential for anticipating the effects of climate change on plant growth and productivity. This study developed a functional-structural grapevine model which combines a mechanistic understanding of stomatal function and photosynthesis at the leaf level (i.e. extended Farqhuhar-von Caemmerer-Berry model) and the dynamics of water transport from soil to individual leaves (i.e. Tardieu-Davies model). The model included novel features that account for the effects of xylem embolism (fPLC) on leaf hydraulic conductance and residual stomatal conductance (g0), variable root and leaf hydraulic conductance, and the microclimate of individual organs. The model was calibrated with detailed datasets of leaf photosynthesis, leaf water potential, xylem sap abscisic acid (ABA) concentration and hourly whole-plant transpiration observed within a soil drying period, and validated with independent datasets of whole-plant transpiration under both well-watered and water-stressed conditions. The model well captured the effects of radiation, temperature, CO2 and vapour pressure deficit on leaf photosynthesis, transpiration, stomatal conductance and leaf water potential, and correctly reproduced the diurnal pattern and decline of water flux within the soil drying period. In silico analyses revealed that decreases in g0 with increasing fPLC were essential to avoid unrealistic drops in leaf water potential under severe water stress. Additionally, by varying the hydraulic conductance along the pathway (e.g. root and leaves) and changing the sensitivity of stomatal conductance to ABA and leaf water potential, the model can produce different water use behaviours (i.e. iso- and anisohydric). The robust performance of this model allows for modelling climate effects from individual plants to fields, and for modelling plants with complex, non-homogenous canopies. In addition, the model provides a

  16. Experimental evidence for anisotropic double exchange interaction driven anisotropic transport in manganite heterostructures

    NARCIS (Netherlands)

    Liao, Zhaoliang; Koster, Gertjan; Huijben, Mark; Rijnders, A.J.H.M.

    2017-01-01

    An anisotropic double exchange interaction driven giant transport anisotropy is demonstrated in a canonic double exchange system of La2/3Sr1/3MnO3 ultrathin films epitaxially grown on NdGaO3 (110) substrates. The oxygen octahedral coupling at the La2/3Sr1/3MnO3/NdGaO3 interface induces a planar

  17. Interplay of Electronic Cooperativity and Exchange Coupling in Regulating the Reactivity of Diiron(IV)-oxo Complexes towards C-H and O-H Bond Activation.

    Science.gov (United States)

    Ansari, Azaj; Ansari, Mursaleem; Singha, Asmita; Rajaraman, Gopalan

    2017-07-26

    Activation of inert C-H bonds such as those of methane are extremely challenging for chemists but in nature, the soluble methane monooxygenase (sMMO) enzyme readily oxidizes methane to methanol by using a diiron(IV) species. This has prompted chemists to look for similar model systems. Recently, a (μ-oxo)bis(μ-carboxamido)diiron(IV) ([Fe IV 2 O(L) 2 ] 2+ L=N,N-bis-(3',5'-dimethyl-4'-methoxypyridyl-2'-methyl)-N'-acetyl-1,2-diaminoethane) complex has been generated by bulk electrolysis and this species activates inert C-H bonds almost 1000 times faster than mononuclear Fe IV =O species and at the same time selectively activates O-H bonds of alcohols. The very high reactivity and selectivity of this species is puzzling and herein we use extensive DFT calculations to shed light on this aspect. We have studied the electronic and spectral features of diiron {Fe III -μ(O)-Fe III } +2 (complex I), {Fe III -μ(O)-Fe IV } +3 (II), and {Fe IV -μ(O)-Fe IV } +4 (III) complexes. Strong antiferromagnetic coupling between the Fe centers leads to spin-coupled S=0, S=3/2, and S=0 ground state for species I-III respectively. The mechanistic study of the C-H and O-H bond activation reveals a multistate reactivity scenario where C-H bond activation is found to occur through the S=4 spin-coupled state corresponding to the high-spin state of individual Fe IV centers. The O-H bond activation on the other hand, occurs through the S=2 spin-coupled state corresponding to an intermediate state of individual Fe IV centers. Molecular orbital analysis reveals σ-π/π-π channels for the reactivity. The nature of the magnetic exchange interaction is found to be switched during the course of the reaction and this offers lower energy pathways. Significant electronic cooperativity between two metal centers during the course of the reaction has been witnessed and this uncovers the reason behind the efficiency and selectivity observed. The catalyst is found to prudently choose the desired spin

  18. Reversed-phase liquid chromatography coupled on-line with capillary gas chromatography use of an anion-exchange membrane to remove an ion-pair reagent from the eluent.

    NARCIS (Netherlands)

    Brinkman, U.A.T.; Goosens, E.C.; de Jong, D.; de Jong, G.J.; Beerthuizen, I.M.

    1995-01-01

    In order to enable the coupling of reversed-phase liquid chromatography (RPLC) with capillary gas chromatography (GC), the performance of an anion-exchange micromembrane device has been studied to remove the ion-pair reagent methanesulphonic acid from an acetonitrile/water LC eluent. The regenerant

  19. Coupled C, N and P controls on photosynthesis, primary production and decomposition across a land use intensification gradient and implications for land atmosphere C exchange

    Science.gov (United States)

    Reinsch, Sabine; Glanville, Helen; Smart, Simon; Jones, Davey; Mercado, Lina; Blanes-Alberola, Mamen; Cosby, Jack; Emmett, Bridget

    2016-04-01

    The coupling of C, N and P cycles has rarely been studied through the air- land-water continuum. This is essential if we are to enhance land-atmosphere models to account for N and P limitations. It is also important for developing integrated catchment management solutions to deliver improved water quality combined with a wide range of other ecosystem functions and services. We present results from a project which is part of the interdisciplinary pan-UK NERC Macronutrient Cycles Programme (macronutrient-cycles.ouce.ox.ac.uk/). Our aim is to quantify how coupled C, N & P cycles change across a land use intensification gradient from arable to grass, woodland and bog ecosystems and identify the implications for land-atmosphere C exchange. We focus on three key processes; photosynthesis, annual net primary productivity and decomposition and explore their consequences for biodiversity. Other aspects of the project track delivery to, and transformations within, the freshwater and coastal systems. When we explore relationships between C, N and P, results indicate all habitat types fall on a single land use intensification gradient. Stoichiometry suggests plant productivity is primarily N limited. P limitation occurs rarely but at all levels of intensification. Soil priming shows our soils are primarily C limited and, surprisingly, soil acidity provides one of the most powerful single predictors of processes and ecosystem services perhaps as it is a good integrator of many soil properties. Incorporating this knowledge into the UK land-atmosphere model JULES will improve aNPP projections. These are then being used as inputs into a plant species model called MULTIMOVE to enable future scenarios of climate change, land use and air pollution on habitat suitability for > 1400 plant species to be explored. The enhanced Jules model will ensure both N and P limitations on C fluxes from above and below-ground are incorporated into future UK scenario applications.

  20. Determination of Cd, Cr, Hg and Pb in plastics from waste electrical and electronic equipment by inductively coupled plasma mass spectrometry with collision-reaction interface technology.

    Science.gov (United States)

    Santos, Mirian C; Nóbrega, Joaquim A; Cadore, Solange

    2011-06-15

    A procedure based on the use of a quadrupole inductively coupled plasma-mass spectrometer equipped with a collision-reaction interface (CRI) for control of spectral overlap interferences was developed for simultaneous determination of Cd, Cr, Hg, and Pb in plastics from waste electrical and electronic equipment (WEEE). The injection of H(2) and He (80 and 60 mL min(-1), respectively) into the sampled plasma, colliding and reacting with potentially interfering polyatomic ions, allows interference-free determination of chromium via its isotopes (52)Cr and (53)Cr that are freed from overlap due to the occurrence of (40)Ar(12)C(+), (40)Ar(12)C(1)H(+), (36)S(16)O(+) or (1)H(36)S(16)O(+). Cadmium, Hg and Pb were directly determined via their isotopes (110)Cd, (111)Cd, (112)Cd, (199)Hg, (200)Hg, (201)Hg, (202)Hg, (206)Pb, (207)Pb, and (208)Pb, without using CRI. The CRI can be quickly activated or deactivated before each analyte measurement. Limits of detection for (52)Cr were 0.04 or 0.14 μg L(-1) with He or H(2) injected in CRI. Cadmium and Pb have LODs between 0.02 and 0.08 μg L(-1) and Hg had 0.93-0.98 μg L(-1), without using CRI. Analyte concentrations for samples varied from 16 to 43, 1 to 11, 4 to 12, and 5 to 13 mg kg(-1) for Cr, Cd, Hg and Pb, respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Comparison of the Laryngeal Mask Airway (CTrachTM and Direct Coupled Interface-Video Laryngoscope for Endotracheal Intubation: a Prospective, Randomized, Clinical Study

    Directory of Open Access Journals (Sweden)

    Kamil Toker

    2012-09-01

    Full Text Available Objective: Video laryngoscopy was developed to facilitate tracheal intubation of difficult airways. We aimed to compare the efficacy of CTrach™ (CT and Direct Coupled Interface-Videolaryngoscope (DCI-VL in patients with normal airways. Material and Methods: Sixty ASA I–II (American Society of Anesthesiologists adult patients admitted for elective surgery were enrolled in this prospective study. The patients were randomly assigned to two groups, where intubation was performed via CT or DCI-VL. Time to obtain a good glottic view, total intubation time, success rates and the number of patients who required maneuvers for a good glottic view were recorded.Results: The mean time to obtaining a good glottic view was significantly longer with CT than with DCI-VL (29.4±20.3 seconds vs. 12.8±1.9 seconds, respectively; p=0.01. Intubation was achieved on the first attempt in 28 patients in the CT group (93.3% and in 24 in the DCI-VL group (80% (p=0.77. The total intubation time for CT was significantly longer compared to DCI-VL (99.9±36.0 seconds vs. 39.2±21.4 seconds, respectively; p=0.01. Optimization maneuvers were required in eight and two patients in the CT and DCI-VL groups, respectively (p=0.03.Conclusion: Although the normal airway endotracheal intubation success rates were similar in both groups, the time to obtain a good glottic view and the total intubation time were significantly shorter with DCI-VL.

  2. Ion beam induced modification of exchange interaction and spin-orbit coupling in the Co2FeSi Heusler compound

    International Nuclear Information System (INIS)

    Hamrle, J; Blomeier, S; Gaier, O; Hillebrands, B; Schneider, H; Jakob, G; Reuscher, B; Brodyanski, A; Kopnarski, M; Postava, K; Felser, C

    2007-01-01

    A Co 2 FeSi (CFS) film with L2 1 structure was irradiated with different fluences of 30 keV Ga + ions. Structural modifications were subsequently studied using the longitudinal (LMOKE) and quadratic (QMOKE) magneto-optical Kerr effect. Both the coercivity and the LMOKE amplitude were found to show a similar behaviour upon irradiation: they are nearly constant up to ion fluences of ∼6 x 10 15 ion cm -2 , while they decrease with further increasing fluences and finally vanish at a fluence of ∼9 x 10 16 ion cm -2 , when the sample becomes paramagnetic. However, contrary to this behaviour, the QMOKE signal nearly vanishes even for the smallest applied fluence of 3 x 10 14 ion cm -2 . We attribute this reduction of the QMOKE signal to an irradiation-induced degeneration of second or higher order spin-orbit coupling, which already happens at small fluences of 30 keV Ga + ions. On the other hand, the reduction of coercivity and LMOKE signal with high ion fluences is probably caused by a reduction of the exchange interaction within the film material

  3. Adiabatic physics of an exchange-coupled spin-dimer system: Magnetocaloric effect, zero-point fluctuations, and possible two-dimensional universal behavior

    International Nuclear Information System (INIS)

    Brambleby, J.; Goddard, P. A.; Singleton, John; Jaime, Marcelo; Lancaster, T.

    2017-01-01

    We present the magnetic and thermal properties of the bosonic-superfluid phase in a spin-dimer network using both quasistatic and rapidly changing pulsed magnetic fields. The entropy derived from a heat-capacity study reveals that the pulsed-field measurements are strongly adiabatic in nature and are responsible for the onset of a significant magnetocaloric effect (MCE). In contrast to previous predictions we show that the MCE is not just confined to the critical regions, but occurs for all fields greater than zero at sufficiently low temperatures. We explain the MCE using a model of the thermal occupation of exchange-coupled dimer spin states and highlight that failure to take this effect into account inevitably leads to incorrect interpretations of experimental results. In addition, the heat capacity in our material is suggestive of an extraordinary contribution from zero-point fluctuations and appears to indicate universal behavior with different critical exponents at the two field-induced critical points. Finally, the data at the upper critical point, combined with the layered structure of the system, are consistent with a two-dimensional nature of spin excitations in the system.

  4. Fast analysis of quaternary ammonium pesticides in food and beverages using cation-exchange chromatography coupled with isotope-dilution high-resolution mass spectrometry.

    Science.gov (United States)

    Nardin, Tiziana; Barnaba, Chiara; Abballe, Franco; Trenti, Gianmaria; Malacarne, Mario; Larcher, Roberto

    2017-10-01

    A fast separation based on cation-exchange liquid chromatography coupled with high-resolution mass spectrometry is proposed for simultaneous determination of chlormequat, difenzoquat, diquat, mepiquat and paraquat in several food and beverage commodities. Solid samples were extracted using a mixture of water/methanol/formic acid (69.6:30:0.4, v/v/v), while liquid samples were ten times diluted with the same solution. Separation was carried out on an experimental length-modified IonPac CS17 column (2 × 15 mm 2 ) that allowed the use of formic acid and acetonitrile as mobile phase. Detection limits for food and beverage matrices were established at 1.5 μg/L for chlormequat, difenzoquat and mepiquat, and 3 μg/L for diquat and paraquat, while for drinking water a pre-analytical sample concentration allowed detection limits of 9 and 20 ng/L, respectively. Precision, as repeatability (RSD%), ranged from 0.2 to 24%, with a median value of 6%, and trueness, as recovery, ranged from 64 to 118%, with a median value of 96%. The method developed was successfully applied to investigate the presence of herbicide residues in commercial commodities (mineral water, orange juice, beer, tea, green coffee bean, toasted coffee powder, cocoa bean, white corn flour, rice and sugar samples). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Anisotropy effects in magnetic hyperthermia: A comparison between spherical and cubic exchange-coupled FeO/Fe{sub 3}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Khurshid, H., E-mail: khurshid@usf.edu, E-mail: sharihar@usf.edu; Nemati, Z.; Phan, M. H.; Mukherjee, P.; Srikanth, H., E-mail: khurshid@usf.edu, E-mail: sharihar@usf.edu [Department of Physics, University of South Florida, Tampa, Florida 33620 (United States); Alonso, J. [Department of Physics, University of South Florida, Tampa, Florida 33620 (United States); BCMaterials Edificio No. 500, Parque Tecnológico de Vizcaya, Derio 48160 (Spain); Fdez-Gubieda, M. L.; Barandiarán, J. M. [BCMaterials Edificio No. 500, Parque Tecnológico de Vizcaya, Derio 48160 (Spain); Depto. Electricidad y Electrónica, Universidad del País Vasco, Leioa 48940 (Spain)

    2015-05-07

    Spherical and cubic exchange-coupled FeO/Fe{sub 3}O{sub 4} nanoparticles, with different FeO:Fe{sub 3}O{sub 4} ratios, have been prepared by a thermal decomposition method to probe anisotropy effects on their heating efficiency. X-ray diffraction and transmission electron microscopy reveal that the nanoparticles are composed of FeO and Fe{sub 3}O{sub 4} phases, with an average size of ∼20 nm. Magnetometry and transverse susceptibility measurements show that the effective anisotropy field is 1.5 times larger for the cubes than for the spheres, while the saturation magnetization is 1.5 times larger for the spheres than for the cubes. Hyperthermia experiments evidence higher values of the specific absorption rate (SAR) for the cubes as compared to the spheres (200 vs. 135 W/g at 600 Oe and 310 kHz). These observations point to an important fact that the saturation magnetization is not a sole factor in determining the SAR and the heating efficiency of the magnetic nanoparticles can be improved by tuning their effective anisotropy.

  6. Determination of Histamine in Silages Using Nanomaghemite Core (γ-Fe2O3-Titanium Dioxide Shell Nanoparticles Off-Line Coupled with Ion Exchange Chromatography

    Directory of Open Access Journals (Sweden)

    Natalia Cernei

    2016-09-01

    Full Text Available The presence of biogenic amines is a hallmark of degraded food and its products. Herein, we focused on the utilization of magnetic nanoparticles off-line coupled with ion exchange chromatography with post-column ninhydrin derivatization and Vis detection for histamine (Him separation and detection. Primarily, we described the synthesis of magnetic nanoparticles with nanomaghemite core (γ-Fe2O3 functionalized with titanium dioxide and, then, applied these particles to specific isolation of Him. To obtain further insight into interactions between paramagnetic particles’ (PMP surface and Him, a scanning electron microscope was employed. It was shown that binding of histamine causes an increase of relative current response of deprotonated PMPs, which confirmed formation of Him-PMPs clusters. The recovery of the isolation showed that titanium dioxide-based particles were able to bind and preconcentrate Him with recovery exceeding 90%. Finally, we successfully carried out the analyses of real samples obtained from silage. We can conclude that our modified particles are suitable for Him isolation, and thus may serve as the first isolation step of Him from biological samples, as it is demonstrated on alfalfa seed variety Tereza silage.

  7. Coupled eco-hydrology and biogeochemistry algorithms enable the simulation of water table depth effects on boreal peatland net CO2 exchange

    Science.gov (United States)

    Mezbahuddin, Mohammad; Grant, Robert F.; Flanagan, Lawrence B.

    2017-12-01

    Water table depth (WTD) effects on net ecosystem CO2 exchange of boreal peatlands are largely mediated by hydrological effects on peat biogeochemistry and the ecophysiology of peatland vegetation. The lack of representation of these effects in carbon models currently limits our predictive capacity for changes in boreal peatland carbon deposits under potential future drier and warmer climates. We examined whether a process-level coupling of a prognostic WTD with (1) oxygen transport, which controls energy yields from microbial and root oxidation-reduction reactions, and (2) vascular and nonvascular plant water relations could explain mechanisms that control variations in net CO2 exchange of a boreal fen under contrasting WTD conditions, i.e., shallow vs. deep WTD. Such coupling of eco-hydrology and biogeochemistry algorithms in a process-based ecosystem model, ecosys, was tested against net ecosystem CO2 exchange measurements in a western Canadian boreal fen peatland over a period of drier-weather-driven gradual WTD drawdown. A May-October WTD drawdown of ˜ 0.25 m from 2004 to 2009 hastened oxygen transport to microbial and root surfaces, enabling greater microbial and root energy yields and peat and litter decomposition, which raised modeled ecosystem respiration (Re) by 0.26 µmol CO2 m-2 s-1 per 0.1 m of WTD drawdown. It also augmented nutrient mineralization, and hence root nutrient availability and uptake, which resulted in improved leaf nutrient (nitrogen) status that facilitated carboxylation and raised modeled vascular gross primary productivity (GPP) and plant growth. The increase in modeled vascular GPP exceeded declines in modeled nonvascular (moss) GPP due to greater shading from increased vascular plant growth and moss drying from near-surface peat desiccation, thereby causing a net increase in modeled growing season GPP by 0.39 µmol CO2 m-2 s-1 per 0.1 m of WTD drawdown. Similar increases in GPP and Re caused no significant WTD effects on modeled

  8. Coupled eco-hydrology and biogeochemistry algorithms enable the simulation of water table depth effects on boreal peatland net CO2 exchange

    Directory of Open Access Journals (Sweden)

    M. Mezbahuddin

    2017-12-01

    Full Text Available Water table depth (WTD effects on net ecosystem CO2 exchange of boreal peatlands are largely mediated by hydrological effects on peat biogeochemistry and the ecophysiology of peatland vegetation. The lack of representation of these effects in carbon models currently limits our predictive capacity for changes in boreal peatland carbon deposits under potential future drier and warmer climates. We examined whether a process-level coupling of a prognostic WTD with (1 oxygen transport, which controls energy yields from microbial and root oxidation–reduction reactions, and (2 vascular and nonvascular plant water relations could explain mechanisms that control variations in net CO2 exchange of a boreal fen under contrasting WTD conditions, i.e., shallow vs. deep WTD. Such coupling of eco-hydrology and biogeochemistry algorithms in a process-based ecosystem model, ecosys, was tested against net ecosystem CO2 exchange measurements in a western Canadian boreal fen peatland over a period of drier-weather-driven gradual WTD drawdown. A May–October WTD drawdown of  ∼  0.25 m from 2004 to 2009 hastened oxygen transport to microbial and root surfaces, enabling greater microbial and root energy yields and peat and litter decomposition, which raised modeled ecosystem respiration (Re by 0.26 µmol CO2 m−2 s−1 per 0.1 m of WTD drawdown. It also augmented nutrient mineralization, and hence root nutrient availability and uptake, which resulted in improved leaf nutrient (nitrogen status that facilitated carboxylation and raised modeled vascular gross primary productivity (GPP and plant growth. The increase in modeled vascular GPP exceeded declines in modeled nonvascular (moss GPP due to greater shading from increased vascular plant growth and moss drying from near-surface peat desiccation, thereby causing a net increase in modeled growing season GPP by 0.39 µmol CO2 m−2 s−1 per 0.1 m of WTD drawdown. Similar increases in

  9. Ultrathin Interface Regime of Core-Shell Magnetic Nanoparticles for Effective Magnetism Tailoring.

    Science.gov (United States)

    Moon, Seung Ho; Noh, Seung-Hyun; Lee, Jae-Hyun; Shin, Tae-Hyun; Lim, Yongjun; Cheon, Jinwoo

    2017-02-08

    The magnetic exchange coupling interaction between hard and soft magnetic phases has been important for tailoring nanoscale magnetism, but spin interactions at the core-shell interface have not been well studied. Here, we systematically investigated a new interface phenomenon termed enhanced spin canting (ESC), which is operative when the shell thickness becomes ultrathin, a few atomic layers, and exhibits a large enhancement of magnetic coercivity (H C ). We found that ESC arises not from the typical hard-soft exchange coupling but rather from the large magnetic surface anisotropy (K S ) of the ultrathin interface. Due to this large increase in magnetism, ultrathin core-shell nanoparticles overreach the theoretical limit of magnetic energy product ((BH) max ) and exhibit one of the largest values of specific loss power (SLP), which testifies to their potential capability as an effective mediator of magnetic energy conversion.

  10. Investigations on the micro-scale surface interactions at the tool and workpiece interface in micro-manufacturing of bipolar plates for proton exchange membrane fuel cells

    Science.gov (United States)

    Peker, Mevlut Fatih

    Micro-forming studies have been more attractive in recent years because of miniaturization trend. One of the promising metal forming processes, micro-stamping, provides durability, strength, surface finish, and low cost for metal products. Hence, it is considered a prominent method for fabricating bipolar plates (BPP) with micro-channel arrays on large metallic surfaces to be used in Proton Exchange Membrane Fuel Cells (PEMFC). Major concerns in micro-stamping of high volume BPPs are surface interactions between micro-stamping dies and blank metal plates, and tribological changes. These concerns play a critical role in determining the surface quality, channel formation, and dimensional precision of bipolar plates. The surface quality of BPP is highly dependent on the micro-stamping die surface, and process conditions due to large ratios of surface area to volume (size effect) that cause an increased level of friction and wear issues at the contact interface. Due to the high volume and fast production rates, BPP surface characteristics such as surface roughness, hardness, and stiffness may change because of repeated interactions between tool (micro-forming die) and workpiece (sheet blank of interest). Since the surface characteristics of BPPs have a strong effect on corrosion and contact resistance of bipolar plates, and consequently overall fuel cell performance, evolution of surface characteristics at the tool and workpiece should be monitored, controlled, and kept in acceptable ranges throughout the long production cycles to maintain the surface quality. Compared to macro-forming operations, tribological changes in micro-forming process are bigger challenges due to their dominance and criticality. Therefore, tribological size effect should be considered for better understanding of tribological changes in micro-scale. The integrity of process simulation to the experiments, on the other hand, is essential. This study describes an approach that aims to investigate

  11. DIFFUSIVE EXCHANGE OF GASEOUS POLYCYCLIC AROMATIC HYDROCARBONS AND POLYCHLORINATED BIPHENYLS ACROSS THE AIR-WATER INTERFACE OF THE CHESAPEAKE BAY. (R825245)

    Science.gov (United States)

    Dissolved and gas-phase concentrations of nine polycyclic aromatic hydrocarbons and 46 polychlorinated biphenyl congeners were measured at eight sites on the Chesapeake Bay at four different times of the year to estimate net diffusive air-water gas exchange rates. Gaseous PAHs ar...

  12. Correlation between Crystallographic and Magnetic Domains at Co/NiO(001) Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ohldag, H.; van der Laan, G.; Arenholz, E.

    2008-12-18

    Using soft x-ray spectromicroscopy we show that NiO(001) exhibits a crystallographic and magnetic domain structure near the surface identical to that of the bulk. Upon Co deposition a perpendicular coupling between the Ni and Co moments is observed that persists even after formation of uncompensated Ni spins at the interface through annealing. The chemical composition at the interface alters its crystallographic structure and leads to a reorientation of the Ni moments from the <112> to the <110> direction. We show that this reorientation is driven by changes in the magnetocrystalline anisotropy rather than exchange coupling mediated by residual uncompensated spins.

  13. The role of the interface on the magnetic behaviour of granular Fe{sub 50}Ag{sub 50} film

    Energy Technology Data Exchange (ETDEWEB)

    Fdez-Gubieda, M.L. [Dpto. Electricidad y Electronica. Universidad del Pais Vasco Apdo 644. 48080 Bilbao (Spain)]. E-mail: malu@we.lc.ehu.es; Sarmiento, G. [Dpto. Electricidad y Electronica. Universidad del Pais Vasco Apdo 644. 48080 Bilbao (Spain); Fernandez Barquin, L. [CITIMAC, Universidad de Cantabria, Avda. de los Castros s/n, 39005 Santander (Spain); Orue, I. [SGIKER, Servicios Generales de medidas magneticas, Universidad del Pais Vasco (Spain)

    2007-03-15

    The magnetic behaviour of a Fe{sub 50}Ag{sub 50} granular thin film has been studied by means of AC and DC magnetic measurements. Exchange coupling between magnetic nanoparticles appears at T=<200K decreasing the coercive field of the sample. Additionally, an exchange bias is observed at low temperature related to the existence of a spin disordered interface around the nanoparticles.

  14. Quantitative aspects of directly coupled supercritical fluid extraction-capillary gas chromatography with a conventional split/splitless injector as interface

    NARCIS (Netherlands)

    Lou, X.W.; Janssen, J.G.M.; Cramers, C.A.

    1993-01-01

    The quant. aspects of online supercrit. fluid extn.-capillary gas chromatog. (SFE-GC) with a split/splitless injector as interface were studied. Special attention was paid to the discrimination behavior and the reproducibility of the split/splitless interface. A simple exptl. set-up is proposed that

  15. A method for scientific code coupling in a distributed environment

    International Nuclear Information System (INIS)

    Caremoli, C.; Beaucourt, D.; Chen, O.; Nicolas, G.; Peniguel, C.; Rascle, P.; Richard, N.; Thai Van, D.; Yessayan, A.

    1994-12-01

    This guide book deals with coupling of big scientific codes. First, the context is introduced: big scientific codes devoted to a specific discipline coming to maturity, and more and more needs in terms of multi discipline studies. Then we describe different kinds of code coupling and an example of code coupling: 3D thermal-hydraulic code THYC and 3D neutronics code COCCINELLE. With this example we identify problems to be solved to realize a coupling. We present the different numerical methods usable for the resolution of coupling terms. This leads to define two kinds of coupling: with the leak coupling, we can use explicit methods, and with the strong coupling we need to use implicit methods. On both cases, we analyze the link with the way of parallelizing code. For translation of data from one code to another, we define the notion of Standard Coupling Interface based on a general structure for data. This general structure constitutes an intermediary between the codes, thus allowing a relative independence of the codes from a specific coupling. The proposed method for the implementation of a coupling leads to a simultaneous run of the different codes, while they exchange data. Two kinds of data communication with message exchange are proposed: direct communication between codes with the use of PVM product (Parallel Virtual Machine) and indirect communication with a coupling tool. This second way, with a general code coupling tool, is based on a coupling method, and we strongly recommended to use it. This method is based on the two following principles: re-usability, that means few modifications on existing codes, and definition of a code usable for coupling, that leads to separate the design of a code usable for coupling from the realization of a specific coupling. This coupling tool available from beginning of 1994 is described in general terms. (authors). figs., tabs

  16. Online Simultaneous Hydrogen/Deuterium Exchange of Multitarget Gas-Phase Molecules by Electrospray Ionization Mass Spectrometry Coupled with Gas Chromatography.

    Science.gov (United States)

    Jeong, Eun Sook; Cha, Eunju; Cha, Sangwon; Kim, Sunghwan; Oh, Han Bin; Kwon, Oh-Seung; Lee, Jaeick

    2017-11-21

    In this study, a hydrogen/deuterium (H/D) exchange method using gas chromatography-electrospray ionization/mass spectrometry (GC-ESI/MS) was first investigated as a novel tool for online H/D exchange of multitarget analytes. The GC and ESI source were combined with a homemade heated column transfer line. GC-ESI/MS-based H/D exchange occurs in an atmospheric pressure ion source as a result of reacting the gas-phase analyte eluted from GC with charged droplets of deuterium oxide infused as the ESI spray solvent. The consumption of the deuterated solvent at a flow rate of 2 μL min -1 was more economical than that in online H/D exchange methods reported to date. In-ESI-source H/D exchange by GC-ESI/MS was applied to 11 stimulants with secondary amino or hydroxyl groups. After H/D exchange, the spectra of the stimulants showed unexchanged, partially exchanged, and fully exchanged ions showing various degrees of exchange. The relative abundances corrected for naturally occurring isotopes of the fully exchanged ions of stimulants, except for etamivan, were in the range 24.3-85.5%. Methylephedrine and cyclazodone showed low H/D exchange efficiency under acidic, neutral, and basic spray solvent conditions and nonexchange for etamivan with an acidic phenolic OH group. The in-ESI-source H/D exchange efficiency by GC-ESI/MS was sufficient to determine the number of hydrogen by elucidation of fragmentation from the spectrum. Therefore, this online H/D exchange technique using GC-ESI/MS has potential as an alternative method for simultaneous H/D exchange of multitarget analytes.

  17. Polycyclic aromatic hydrocarbon (PAH) deposition to and exchange at the air-water interface of Luhu, an urban lake in Guangzhou, China

    International Nuclear Information System (INIS)

    Li Jun; Cheng Hairong; Zhang Gan; Qi Shihua; Li Xiangdong

    2009-01-01

    Urban lakes are vulnerable to the accumulation of semivolatile organic compounds, such as PAHs from wet and dry atmospheric deposition. Little was reported on the seasonal patterns of atmospheric deposition of PAHs under Asian monsoon climate. Bulk (dry + wet) particle deposition, air-water diffusion exchange, and vapour wet deposition of PAHs in a small urban lake in Guangzhou were estimated based on a year-round monitoring. The total PAH particle deposition fluxes observed were 0.44-3.46 μg m -2 day -1 . The mean air-water diffusive exchange flux was 20.7 μg m -2 day -1 . The vapour deposition fluxes of PAHs ranged 0.15-8.26 μg m -2 day -1 . Remarkable seasonal variations of particulate PAH deposition, air-water exchange fluxes and vapour wet deposition were influenced by seasonal changes in meteorological parameters. The deposition fluxes were predominantly controlled by the precipitation intensity in wet season whereas by atmospheric concentration in dry season. - The PAH deposition fluxes were predominantly controlled by the precipitation intensity in wet season whereas by atmospheric concentration in dry season

  18. Freezing field dependence of the exchange bias in uniaxial FeF sub 2 -CoPt heterosystems with perpendicular anisotropy

    CERN Document Server

    Kagerer, B; Kleemann, W

    2000-01-01

    The exchange bias effect is measured for the first time in FeF sub 2 -CoPt heterosystems with perpendicular anisotropy. The exchange field exhibits a strong dependence on the axial freezing field. This behavior is explained in terms of the microscopic spin structure at the interface, which is established on cooling to below T sub N. We calculate the dependence of the spin structure on the freezing field within the framework of an Ising model. It takes into account the Zeeman energy as well as an antiferromagnetic exchange coupling between the adjacent layers at the interface.

  19. Exchange bias energy in Co/Pt/IrMn multilayers with perpendicular and in-plane anisotropy

    International Nuclear Information System (INIS)

    Czapkiewicz, M.; Stobiecki, T.; Rak, R.; Zoladz, M.; Dijken, S. van

    2007-01-01

    The magnetization reversal process in perpendicularly biased [Pt/Co] 3 /d Pt Pt/IrMn and in-plane biased Co/d Pt Pt/IrMn multilayers with 0nm= Pt = Pt =0.1nm. In both cases, the existence of large exchange bias fields correlates with a high domain density during magnetization reversal. The interface exchange coupling energy is larger for the in-plane biased films than for the perpendicularly biased multilayers

  20. Simultaneous separation and determination of six arsenic species in rice by anion-exchange chromatography with inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Ma, Li; Yang, Zhaoguang; Tang, Jie; Wang, Lin

    2016-06-01

    The simultaneous separation and determination of arsenite As(III), arsenate As(V), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenobetaine (AsB), and arsenocholine (AsC) in rice samples have been carried out in one single anion-exchange column run by high-performance liquid chromatography with inductively coupled plasma mass spectrometry. To estimate the effect of variables on arsenic (As) speciation, the chromatographic conditions including type of competing anion, ionic strength, pH of elution buffer, and flow rate of mobile phase have been investigated by a univariate approach. Under the optimum chromatographic conditions, baseline separation of six As species has been achieved within 10 min by gradient elution program using 4 mM NH4 HCO3 at pH 8.6 as mobile phase A and 4 mM NH4 HCO3 , 40 mM NH4 NO3 at pH 8.6 as mobile phase B. The method detection limits for As(III), As(V), MMA, DMA, AsB, and AsC were 0.4, 0.9, 0.2, 0.4, 0.5, and 0.3 μg/kg, respectively. The proposed method has been applied to separation and quantification of As species in real rice samples collected from Hunan Province, China. The main As species detected in all samples were As(III), As(V) and DMA, with inorganic As accounting for over 80% of total As in these samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Exchange bias in Co nanoparticles embedded in an Mn matrix

    International Nuclear Information System (INIS)

    Domingo, Neus; Testa, Alberto M.; Fiorani, Dino; Binns, Chris; Baker, Stephen; Tejada, Javier

    2007-01-01

    Magnetic properties of Co nanoparticles of 1.8 nm diameter embedded in Mn and Ag matrices have been studied as a function of the volume fraction (VFF). While the Co nanoparticles in the Ag matrix show superparamagnetic behavior with T B =9.5 K (1.5% VFF) and T B =18.5 K (8.9% VFF), the Co nanoparticles in the antiferromagnetic Mn matrix show a transition peak at ∼65 K in the ZFC/FC susceptibility measurements, and an increase of the coercive fields at low temperature with respect to the Ag matrix. Exchange bias due to the interface exchange coupling between Co particles and the antiferromagnetic Mn matrix has also been studied. The exchange bias field (H eb ), observed for all Co/Mn samples below 40 K, decreases with decreasing volume fraction and with increasing temperature and depends on the field of cooling (H fc ). Exchange bias is accompanied by an increase of coercivity

  2. The nature of the exchange coupling between high-spin Fe(III) heme o3 and CuBII in Escherichia coli quinol oxidase, cytochrome bo3: MCD and EPR studies.

    Science.gov (United States)

    Cheesman, Myles R; Oganesyan, Vasily S; Watmough, Nicholas J; Butler, Clive S; Thomson, Andrew J

    2004-04-07

    Fully oxidized cytochrome bo3 from Escherichia coli has been studied in its oxidized and several ligand-bound forms using electron paramagnetic resonance (EPR) and magnetic circular dichroism (MCD) spectroscopies. In each form, the spin-coupled high-spin Fe(III) heme o3 and CuB(II) ion at the active site give rise to similar fast-relaxing broad features in the dual-mode X-band EPR spectra. Simulations of dual-mode spectra are presented which show that this EPR can arise only from a dinuclear site in which the metal ions are weakly coupled by an anisotropic exchange interaction of J 1 cm-1. A variable-temperature and magnetic field (VTVF) MCD study is also presented for the cytochrome bo3 fluoride and azide derivatives. New methods are used to extract the contribution to the MCD of the spin-coupled active site in the presence of strong transitions from low-spin Fe(III) heme b. Analysis of the MCD data, independent of the EPR study, also shows that the spin-coupling within the active site is weak with J approximately 1 cm-1. These conclusions overturn a long-held view that such EPR signals in bovine cytochrome c oxidase arise from an S' = 2 ground state resulting from strong exchange coupling (J > 10(2) cm-1) within the active site.

  3. Determination of aminopolycarboxylic acids at ultra-trace levels by means of online coupling ion exchange chromatography and inductively coupled plasma-mass spectrometry with indirect detection via their Pd2+-complexes

    International Nuclear Information System (INIS)

    Nette, David; Seubert, Andreas

    2015-01-01

    Highlights: • 8 important APCA’s analyzed in one run instead of 3 in the previous method. • Pd 2+ extents the methods applicability to 3 and more dentate amino carboxylic acids. • Separation system optimized for the isocratic determination of important APCA’s. • Thermodynamic stability of APCA–Pd 2+ complexes is higher than for Fe 3+ and In 3+ . • Pd 2+ is kinetically much slower than Fe 3+ and In 3+ and makes the method more rugged. - Abstract: A new indirect IC-ICP-MS method for the determination of aminopolycarboxylic acids in water samples is described. It is based on the addition of an excess of Pd(II) to water samples. The analytes are forced into very strong and negatively charged palladium complexes, separated by ion exchange chromatography and detected by their palladium content, utilizing an on-line coupled ICP-MS. This method is suitable to determine the concentration of 8 aminopolycarboxylic acids (nitrilotriacetic acid (NTA), (2-carboxyethyl) iminodiacetic acid (β-ADA), methylglycinediacetic acid (MGDA), 2-hydroxyethyl) ethylenediamine triacetic acid (HEDTA), diethylene triamine pentaacetic acid (DTPA), ethylendiamine tetraacetic acid (EDTA), 1,3-diaminopropane tetraacetic acid (1,3-PDTA) and 1,2-diaminopropane tetraacetic acid (1,2-PDTA) at the ng kg −1 level. The method is faster and easier than the established gas chromatography (GC)-method ISO 16588:2002 [1] and up to two orders of magnitude more sensitive than the ion pair chromatography based method of DIN 38413-8. Analytic performance is superior to ISO 16588:2002 and the comparability is good

  4. Determination of aminopolycarboxylic acids at ultra-trace levels by means of online coupling ion exchange chromatography and inductively coupled plasma-mass spectrometry with indirect detection via their Pd{sup 2+}-complexes

    Energy Technology Data Exchange (ETDEWEB)

    Nette, David; Seubert, Andreas, E-mail: seubert@staff.uni-marburg.de

    2015-07-16

    Highlights: • 8 important APCA’s analyzed in one run instead of 3 in the previous method. • Pd{sup 2+} extents the methods applicability to 3 and more dentate amino carboxylic acids. • Separation system optimized for the isocratic determination of important APCA’s. • Thermodynamic stability of APCA–Pd{sup 2+} complexes is higher than for Fe{sup 3+} and In{sup 3+}. • Pd{sup 2+} is kinetically much slower than Fe{sup 3+} and In{sup 3+} and makes the method more rugged. - Abstract: A new indirect IC-ICP-MS method for the determination of aminopolycarboxylic acids in water samples is described. It is based on the addition of an excess of Pd(II) to water samples. The analytes are forced into very strong and negatively charged palladium complexes, separated by ion exchange chromatography and detected by their palladium content, utilizing an on-line coupled ICP-MS. This method is suitable to determine the concentration of 8 aminopolycarboxylic acids (nitrilotriacetic acid (NTA), (2-carboxyethyl) iminodiacetic acid (β-ADA), methylglycinediacetic acid (MGDA), 2-hydroxyethyl) ethylenediamine triacetic acid (HEDTA), diethylene triamine pentaacetic acid (DTPA), ethylendiamine tetraacetic acid (EDTA), 1,3-diaminopropane tetraacetic acid (1,3-PDTA) and 1,2-diaminopropane tetraacetic acid (1,2-PDTA) at the ng kg{sup −1} level. The method is faster and easier than the established gas chromatography (GC)-method ISO 16588:2002 [1] and up to two orders of magnitude more sensitive than the ion pair chromatography based method of DIN 38413-8. Analytic performance is superior to ISO 16588:2002 and the comparability is good.

  5. Quantitative aspects of directly coupled supercritical fluid extraction-capillary gas chromatography with a conventional split/splitless injector as interface

    OpenAIRE

    Lou, X.W.; Janssen, J.G.M.; Cramers, C.A.

    1993-01-01

    The quant. aspects of online supercrit. fluid extn.-capillary gas chromatog. (SFE-GC) with a split/splitless injector as interface were studied. Special attention was paid to the discrimination behavior and the reproducibility of the split/splitless interface. A simple exptl. set-up is proposed that allows accurate quantitation in online SFE-split GC. The results obtained in online SFE-GC compare favorably with those from conventional GC with split injection. Discrimination is absent when wor...

  6. Exotic baryonium exchanges

    International Nuclear Information System (INIS)

    Nicolescu, B.

    1978-05-01

    The prominent effects supposed to be associated with the exchange of exotic baryonium Regge trajectories are reviewed. The experimental presence of all expected effects leads to suggest that the baryonium exchange mechanism is a correct phenomenological picture and that mesons with isospin 2 or 3/2 or with strangeness 2, strongly coupled to the baryon-antibaryon channels, must be observed

  7. Marital Construction of Family Power among Male-out-Migrant Couples in a Chinese Village: A Relation-Oriented Exchange Model

    Science.gov (United States)

    Zuo, Jiping

    2008-01-01

    This study examines marital construction of family power among male-out-migrant couples in a Chinese village in Guangxi Province. In-depth interviews show that male-out-migrant couples prefer joint decision making. When couples are in disputes, power tends to go to the ones who shoulder greater household-based responsibilities; in this case, they…

  8. Temporal variability of exchange between groundwater and surface water based on high-frequency direct measurements of seepage at the sediment-water interface

    Science.gov (United States)

    Rosenberry, Donald O.; Sheibley, Rich W.; Cox, Stephen E.; Simonds, Frederic W.; Naftz, David L.

    2013-01-01

    Seepage at the sediment-water interface in several lakes, a large river, and an estuary exhibits substantial temporal variability when measured with temporal resolution of 1 min or less. Already substantial seepage rates changed by 7% and 16% in response to relatively small rain events at two lakes in the northeastern USA, but did not change in response to two larger rain events at a lake in Minnesota. However, seepage at that same Minnesota lake changed by 10% each day in response to withdrawals from evapotranspiration. Seepage increased by more than an order of magnitude when a seiche occurred in the Great Salt Lake, Utah. Near the head of a fjord in Puget Sound, Washington, seepage in the intertidal zone varied greatly from −115 to +217 cm d−1 in response to advancing and retreating tides when the time-averaged seepage was upward at +43 cm d−1. At all locations, seepage variability increased by one to several orders of magnitude in response to wind and associated waves. Net seepage remained unchanged by wind unless wind also induced a lake seiche. These examples from sites distributed across a broad geographic region indicate that temporal variability in seepage in response to common hydrological events is much larger than previously realized. At most locations, seepage responded within minutes to changes in surface-water stage and within minutes to hours to groundwater recharge associated with rainfall. Likely implications of this dynamism include effects on water residence time, geochemical transformations, and ecological conditions at and near the sediment-water interface.

  9. Kinetic Interface

    DEFF Research Database (Denmark)

    2009-01-01

    A kinetic interface for orientation detection in a video training system is disclosed. The interface includes a balance platform instrumented with inertial motion sensors. The interface engages a participant's sense of balance in training exercises.......A kinetic interface for orientation detection in a video training system is disclosed. The interface includes a balance platform instrumented with inertial motion sensors. The interface engages a participant's sense of balance in training exercises....

  10. Multi-Megawatt-Scale Power-Hardware-in-the-Loop Interface for Testing Ancillary Grid Services by Converter-Coupled Generation: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Koralewicz, Przemyslaw J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Gevorgian, Vahan [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Wallen, Robert B [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-07-26

    Power-hardware-in-the-loop (PHIL) is a simulation tool that can support electrical systems engineers in the development and experimental validation of novel, advanced control schemes that ensure the robustness and resiliency of electrical grids that have high penetrations of low-inertia variable renewable resources. With PHIL, the impact of the device under test on a generation or distribution system can be analyzed using a real-time simulator (RTS). PHIL allows for the interconnection of the RTS with a 7 megavolt ampere (MVA) power amplifier to test multi-megawatt renewable assets available at the National Wind Technology Center (NWTC). This paper addresses issues related to the development of a PHIL interface that allows testing hardware devices at actual scale. In particular, the novel PHIL interface algorithm and high-speed digital interface, which minimize the critical loop delay, are discussed.

  11. Accurate determination of trace amounts of phosphorus in geological samples by inductively coupled plasma atomic emission spectrometry with ion-exchange separation

    International Nuclear Information System (INIS)

    Asoh, Kazuya; Ebihara, Mitsuru

    2013-01-01

    Graphical abstract: -- Highlights: •We set up an effective ICP-AES procedure for determining trace P in rock samples. •Some certified values of P for reference rock samples were proved to be doubtful. •Accurate and reliable data were presented for a suite of geological reference rocks. -- Abstract: In order to determine trace amounts of phosphorus in geological and cosmochemical rock samples, simple as well as reliable analytical schemes using an ICP-AES instrument were investigated. A (conventional) ICP-AES procedure could determine phosphorus contents at the level of several 100 μg g −1 with a reasonable reproducibility ( −1 ; 1σ). An ICP-AES procedure coupled with matrix-separation using cation and anion exchange resins could lower the quantification level down to 1 μg g −1 or even lower under the present experimental conditions. The matrix-separation ICP-AES procedure developed in this study was applied to twenty-one geological reference samples issued by Geological Survey of Japan. Obtained values vary from 1250 μg g −1 for JB-3 (basalt) to 2.07 μg g −1 for JCt-1 (carbonate). Matrix-separation ICP-AES yielded reasonable reproducibility (less than 8.3%; 1σ) of three replicate analyses for all the samples analyzed. In comparison of our data with certificate values as well as literature or reported values, there appear to be an apparent (and large) discrepancy between our values and certificate/reported values regardless of phosphorus contents. Based on the reproducibility of our data and the analytical capability of the matrix-separation ICP-AES procedure developed in this study (in terms of quantification limit, recovery, selectivity of an analyte through pre-concentration process, etc.), it is concluded that certified values for several reference standard rocks should be reevaluated and revised accordingly. It may be further pointed that some phosphorus data reported in literatures should be critically evaluated when they are to be

  12. The N54-αs Mutant Has Decreased Affinity for βγ and Suggests a Mechanism for Coupling Heterotrimeric G Protein Nucleotide Exchange with Subunit Dissociation.

    Science.gov (United States)

    Cleator, John H; Wells, Christopher A; Dingus, Jane; Kurtz, David T; Hildebrandt, John D

    2018-05-01

    Ser54 of G s α binds guanine nucleotide and Mg 2+ as part of a conserved sequence motif in GTP binding proteins. Mutating the homologous residue in small and heterotrimeric G proteins generates dominant-negative proteins, but by protein-specific mechanisms. For α i/o , this results from persistent binding of α to βγ , whereas for small GTP binding proteins and α s this results from persistent binding to guanine nucleotide exchange factor or receptor. This work examined the role of βγ interactions in mediating the properties of the Ser54-like mutants of G α subunits. Unexpectedly, WT- α s or N54- α s coexpressed with α 1B -adrenergic receptor in human embryonic kidney 293 cells decreased receptor stimulation of IP3 production by a cAMP-independent mechanism, but WT- α s was more effective than the mutant. One explanation for this result would be that α s , like Ser47 α i/o , blocks receptor activation by sequestering βγ ; implying that N54- α S has reduced affinity for βγ since it was less effective at blocking IP3 production. This possibility was more directly supported by the observation that WT- α s was more effective than the mutant in inhibiting βγ activation of phospholipase C β 2. Further, in vitro synthesized N54- α s bound biotinylated- βγ with lower apparent affinity than did WT- α s The Cys54 mutation also decreased βγ binding but less effectively than N54- α s Substitution of the conserved Ser in α o with Cys or Asn increased βγ binding, with the Cys mutant being more effective. This suggests that Ser54 of α s is involved in coupling changes in nucleotide binding with altered subunit interactions, and has important implications for how receptors activate G proteins. Copyright © 2018 by The American Society for Pharmacology and Experimental Therapeutics.

  13. Exchange bias studied with polarized neutron reflectivity

    International Nuclear Information System (INIS)

    Velthuis, S. G. E. te

    2000-01-01

    The role of Polarized Neutron Reflectivity (PNR) for studying natural and synthetic exchange biased systems is illustrated. For a partially oxidized thin film of Co, cycling of the magnetic field causes a considerable reduction of the bias, which the onset of diffuse neutron scattering shows to be due to the loosening of the ferromagnetic domains. On the other hand, PNR measurements of a model exchange bias junction consisting of an n-layered Fe/Cr antiferromagnetic (AF) superlattice coupled with an m-layered Fe/Cr ferromagnetic (F) superlattice confirm the predicted collinear magnetization in the two superlattices. The two magnetized states of the F (along or opposite to the bias field) differ only in the relative orientation of the F and adjacent AF layer. The possibility of reading clearly the magnetic state at the interface pinpoints the commanding role that PNR is having in solving this intriguing problem

  14. Direct measurement of the long-range p -d exchange coupling in a ferromagnet-semiconductor Co/CdMgTe/CdTe quantum well hybrid structure

    Science.gov (United States)

    Akimov, I. A.; Salewski, M.; Kalitukha, I. V.; Poltavtsev, S. V.; Debus, J.; Kudlacik, D.; Sapega, V. F.; Kopteva, N. E.; Kirstein, E.; Zhukov, E. A.; Yakovlev, D. R.; Karczewski, G.; Wiater, M.; Wojtowicz, T.; Korenev, V. L.; Kusrayev, Yu. G.; Bayer, M.

    2017-11-01

    The exchange interaction between magnetic ions and charge carriers in semiconductors is considered to be a prime tool for spin control. Here, we solve a long-standing problem by uniquely determining the magnitude of the long-range p -d exchange interaction in a ferromagnet-semiconductor (FM-SC) hybrid structure where a 10-nm-thick CdTe quantum well is separated from the FM Co layer by a CdMgTe barrier with a thickness on the order of 10 nm. The exchange interaction is manifested by the spin splitting of acceptor bound holes in the effective magnetic field induced by the FM. The exchange splitting is directly evaluated using spin-flip Raman scattering by analyzing the dependence of the Stokes shift ΔS on the external magnetic field B . We show that in a strong magnetic field, ΔS is a linear function of B with an offset of Δp d=50 -100 μ eV at zero field from the FM induced effective exchange field. On the other hand, the s -d exchange interaction between conduction band electrons and FM, as well as the p -d contribution for free valence band holes, are negligible. The results are well described by the model of indirect exchange interaction between acceptor bound holes in the CdTe quantum well and the FM layer mediated by elliptically polarized phonons in the hybrid structure.

  15. Exploring the microscopic origin of exchange bias with photoelectron emission microscopy (invited)

    International Nuclear Information System (INIS)

    Scholl, A.; Nolting, F.; Stohr, J.; Regan, T.; Luning, J.; Seo, J. W.; Locquet, J.-P.; Fompeyrine, J.; Anders, S.; Ohldag, H.

    2001-01-01

    It is well known that magnetic exchange coupling across the ferromagnet - antiferromagnet interface results in an unidirectional magnetic anisotropy of the ferromagnetic layer, called exchange bias. Despite large experimental and theoretical efforts, the origin of exchange bias is still controversial, mainly because detection of the interfacial magnetic structure is difficult. We have applied photoelectron emission microscopy (PEEM) on several ferromagnet - antiferromagnet thin-film structures and microscopically imaged the ferromagnetic and the antiferromagnetic structure with high spatial resolution. Taking advantage of the surface sensitivity and elemental specificity of PEEM, the magnetic configuration and critical properties such as the Neel temperature were determined on LaFeO 3 and NiO thin films and single crystals. On samples coated with a ferromagnetic layer, we microscopically observe exchange coupling across the interface, causing a clear correspondence of the domain structures in the adjacent ferromagnet and antiferromagnet. Field dependent measurements reveal a strong uniaxial anisotropy in individual ferromagnetic domains. A local exchange bias was observed even in not explicitly field-annealed samples, caused by interfacial uncompensated magnetic spins. These experiments provide highly desired information on the relative orientation of electron spins at the interface between ferromagnets and antiferromagnets. [copyright] 2001 American Institute of Physics

  16. Nutrient and physical profile data from four Microbial Exchanges and Coupling in Coastal Atlantic Systems (MECCAS) cruises collected aboard the R/V Gyre at the mouth of the Chesapeake Bay and northern Atlantic Ocean from February 17, 1985 to September 7, 1986 (NODC Accession 8800324)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Microbial Exchanges and Coupling in Coastal Atlantic Systems (MECCAS) cruise data collected aboard the R/V Gyre at the mouth of the Chesapeake Bay and northern...

  17. Matchmaker Exchange.

    Science.gov (United States)

    Sobreira, Nara L M; Arachchi, Harindra; Buske, Orion J; Chong, Jessica X; Hutton, Ben; Foreman, Julia; Schiettecatte, François; Groza, Tudor; Jacobsen, Julius O B; Haendel, Melissa A; Boycott, Kym M; Hamosh, Ada; Rehm, Heidi L

    2017-10-18

    In well over half of the individuals with rare disease who undergo clinical or research next-generation sequencing, the responsible gene cannot be determined. Some reasons for this relatively low yield include unappreciated phenotypic heterogeneity; locus heterogeneity; somatic and germline mosaicism; variants of uncertain functional significance; technically inaccessible areas of the genome; incorrect mode of inheritance investigated; and inadequate communication between clinicians and basic scientists with knowledge of particular genes, proteins, or biological systems. To facilitate such communication and improve the search for patients or model organisms with similar phenotypes and variants in specific candidate genes, we have developed the Matchmaker Exchange (MME). MME was created to establish a federated network connecting databases of genomic and phenotypic data using a common application programming interface (API). To date, seven databases can exchange data using the API (GeneMatcher, PhenomeCentral, DECIPHER, MyGene2, matchbox, Australian Genomics Health Alliance Patient Archive, and Monarch Initiative; the latter included for model organism matching). This article guides usage of the MME for rare disease gene discovery. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley and Sons, Inc.

  18. Geological Disposal of Nuclear Waste: Investigating the Thermo-Hygro-Mechanical-Chemical (THMC) Coupled Processes at the Waste Canister- Bentonite Barrier Interface

    Science.gov (United States)

    Davies, C. W.; Davie, D. C.; Charles, D. A.

    2015-12-01

    Geological disposal of nuclear waste is being increasingly considered to deal with the growing volume of waste resulting from the nuclear legacy of numerous nations. Within the UK there is 650,000 cubic meters of waste safely stored and managed in near-surface interim facilities but with no conclusive permanent disposal route. A Geological Disposal Facility with incorporated Engineered Barrier Systems are currently being considered as a permanent waste management solution (Fig.1). This research focuses on the EBS bentonite buffer/waste canister interface, and experimentally replicates key environmental phases that would occur after canister emplacement. This progresses understanding of the temporal evolution of the EBS and the associated impact on its engineering, mineralogical and physicochemical state and considers any consequences for the EBS safety functions of containment and isolation. Correlation of engineering properties to the physicochemical state is the focus of this research. Changes to geotechnical properties such as Atterberg limits, swelling pressure and swelling kinetics are measured after laboratory exposure to THMC variables from interface and batch experiments. Factors affecting the barrier, post closure, include corrosion product interaction, precipitation of silica, near-field chemical environment, groundwater salinity and temperature. Results show that increasing groundwater salinity has a direct impact on the buffer, reducing swelling capacity and plasticity index by up to 80%. Similarly, thermal loading reduces swelling capacity by 23% and plasticity index by 5%. Bentonite/steel interaction studies show corrosion precipitates diffusing into compacted bentonite up to 3mm from the interface over a 4 month exposure (increasing with temperature), with reduction in swelling capacity in the affected zone, probably due to the development of poorly crystalline iron oxides. These results indicate that groundwater conditions, temperature and corrosion

  19. Superconductivity induced by interfacial coupling to magnons

    Science.gov (United States)

    Rohling, Niklas; Fjærbu, Eirik Løhaugen; Brataas, Arne

    2018-03-01

    We consider a thin normal metal sandwiched between two ferromagnetic insulators. At the interfaces, the exchange coupling causes electrons within the metal to interact with magnons in the insulators. This electron-magnon interaction induces electron-electron interactions, which in turn can result in p -wave superconductivity. We solve the gap equation numerically and estimate the critical temperature. In yttrium iron garnet (YIG)-Au-YIG trilayers, superconductivity sets in at temperatures somewhere in the interval between 1 and 10 K. EuO-Au-EuO trilayers require a lower temperature, in the range from 0.01 to 1 K.

  20. Biopolymers form a gelatinous microlayer at the air-sea interface when Arctic sea ice melts

    OpenAIRE

    Galgani, Luisa; Piontek, Judith; Engel, Anja

    2016-01-01

    The interface layer between ocean and atmosphere is only a couple of micrometers thick but plays a critical role in climate relevant processes, including the air-sea exchange of gas and heat and the emission of primary organic aerosols (POA). Recent findings suggest that low-level cloud formation above the Arctic Ocean may be linked to organic polymers produced by marine microorganisms. Sea ice harbors high amounts of polymeric substances that are produced by cells growing within the sea-ice ...

  1. The effect of higher order different meson exchange nucleon-nucleon interactions on the three-nucleon binding energy coupling problem

    International Nuclear Information System (INIS)

    Osman, A.; Ramadan, S.

    1989-01-01

    Faddeev equations of bound three-nucleon system are presented as a set of integral equations. To solve them, a sutable form of the nucleon-nucleon interactions is used: with the exchange of a scalar meson, a pseudoscalar meson and a massless vector meson. Higher orders of these different meson exchanges in the nucleon-nucleon interactions have been taken into account. With these nuclear forces and nucleon-nucleon interactions, the three-nucleon binding energy is calculated by solving the Faddeev integral equations. The obtained value of the three-nucleon binding energy is 8.441 MeV. The inclusion of the higher order terms of the different meson exchange in the nuclear nucleon-nucleon interaction is found to affect the three-nucleon binding by about 3.92%. 3 figs., 16 refs

  2. Coupling Strategies Investigation of Hybrid Atomistic-Continuum Method Based on State Variable Coupling

    Directory of Open Access Journals (Sweden)

    Qian Wang

    2017-01-01

    Full Text Available Different configurations of coupling strategies influence greatly the accuracy and convergence of the simulation results in the hybrid atomistic-continuum method. This study aims to quantitatively investigate this effect and offer the guidance on how to choose the proper configuration of coupling strategies in the hybrid atomistic-continuum method. We first propose a hybrid molecular dynamics- (MD- continuum solver in LAMMPS and OpenFOAM that exchanges state variables between the atomistic region and the continuum region and evaluate different configurations of coupling strategies using the sudden start Couette flow, aiming to find the preferable configuration that delivers better accuracy and efficiency. The major findings are as follows: (1 the C→A region plays the most important role in the overlap region and the “4-layer-1” combination achieves the best precision with a fixed width of the overlap region; (2 the data exchanging operation only needs a few sampling points closer to the occasions of interactions and decreasing the coupling exchange operations can reduce the computational load with acceptable errors; (3 the nonperiodic boundary force model with a smoothing parameter of 0.1 and a finer parameter of 20 can not only achieve the minimum disturbance near the MD-continuum interface but also keep the simulation precision.

  3. State-selective charge exchange in slow collisions of Si3+ ions with H atoms: A molecular state close coupling treatment

    International Nuclear Information System (INIS)

    Joseph, Dwayne C; Saha, Bidhan C

    2012-01-01

    Charge transfer cross sections are calculated by employing both the quantal and semiclassical ε(R) molecular orbital close coupling (MOCC) approximations in the adiabatic representation and compared with other theoretical and experimental results

  4. State-selective charge exchange in slow collisions of Si3+ ions with H atoms: A molecular state close coupling treatment*)

    Science.gov (United States)

    Joseph, Dwayne C.; Saha, Bidhan C.

    2012-11-01

    Charge transfer cross sections are calculated by employing both the quantal and semiclassical ɛ(R) molecular orbital close coupling (MOCC) approximations in the adiabatic representation and compared with other theoretical and experimental results

  5. Rapid isolation of plutonium in environmental solid samples using sequential injection anion exchange chromatography followed by detection with inductively coupled plasma mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Qiao Jixin, E-mail: jixin.qiao@risoe.d [Radiation Research Division, Riso National Laboratory for Sustainable Energy, Technical University of Denmark, DK-4000 Roskilde (Denmark); Hou Xiaolin; Roos, Per [Radiation Research Division, Riso National Laboratory for Sustainable Energy, Technical University of Denmark, DK-4000 Roskilde (Denmark); Miro, Manuel [Department of Chemistry, Faculty of Sciences, University of the Balearic Islands, Carretera de Valldemossa km. 7.5, E-07122 Palma de Mallorca, Illes Balears (Spain)

    2011-01-31

    This paper reports an automated analytical method for rapid determination of plutonium isotopes ({sup 239}Pu and {sup 240}Pu) in environmental solid extracts. Anion exchange chromatographic columns were incorporated in a sequential injection (SI) system to undertake the automated separation of plutonium from matrix and interfering elements. The analytical results most distinctly demonstrated that the crosslinkage of the anion exchanger is a key parameter controlling the separation efficiency. AG 1-x4 type resin was selected as the most suitable sorbent material for analyte separation. Investigation of column size effect upon the separation efficiency revealed that small-sized (2 mL) columns sufficed to handle up to 50 g of environmental soil samples. Under the optimum conditions, chemical yields of plutonium exceeded 90% and the decontamination factors for uranium, thorium and lead ranged from 10{sup 3} to 10{sup 4}. The determination of plutonium isotopes in three standard/certified reference materials (IAEA-375 soil, IAEA-135 sediment and NIST-4359 seaweed) and two reference samples (Irish Sea sediment and Danish soil) revealed a good agreement with reference/certified values. The SI column-separation method is straightforward and less labor intensive as compared with batch-wise anion exchange chromatographic procedures. Besides, the automated method features low consumption of ion-exchanger and reagents for column washing and elution, with the consequent decrease in the generation of acidic waste, thus bearing green chemical credentials.

  6. Interface Consistency

    DEFF Research Database (Denmark)

    Staunstrup, Jørgen

    1998-01-01

    This paper proposes that Interface Consistency is an important issue for the development of modular designs. Byproviding a precise specification of component interfaces it becomes possible to check that separately developedcomponents use a common interface in a coherent matter thus avoiding a very...... significant source of design errors. Awide range of interface specifications are possible, the simplest form is a syntactical check of parameter types.However, today it is possible to do more sophisticated forms involving semantic checks....

  7. Magnetism at the Interface of Magnetic Oxide and Nonmagnetic Semiconductor Quantum Dots.

    Science.gov (United States)

    Saha, Avijit; Viswanatha, Ranjani

    2017-03-28

    Engineering interfaces specifically in quantum dot (QD) heterostructures provide several prospects for developing multifunctional building block materials. Precise control over internal structure by chemical synthesis offers a combination of different properties in QDs and allows us to study their fundamental properties, depending on their structure. Herein, we studied the interface of magnetic/nonmagnetic Fe 3 O 4 /CdS QD heterostructures. In this work, we demonstrate the decrease in the size of the magnetic core due to annealing at high temperature by the decrease in saturation magnetization and blocking temperature. Furthermore, surprisingly, in a prominently optically active and magnetically inactive material such as CdS, we observe the presence of substantial exchange bias in spite of the nonmagnetic nature of CdS QDs. The presence of exchange bias was proven by the increase in magnetic anisotropy as well as the presence of exchange bias field (H E ) during the field-cooled magnetic measurements. This exchange coupling was eventually traced to the in situ formation of a thin antiferromagnetic FeS layer at the interface. This is verified by the study of Fe local structure using X-ray absorption fine structure spectroscopy, demonstrating the importance of interface engineering in QDs.

  8. Interface models

    DEFF Research Database (Denmark)

    Ravn, Anders P.; Staunstrup, Jørgen

    1994-01-01

    This paper proposes a model for specifying interfaces between concurrently executing modules of a computing system. The model does not prescribe a particular type of communication protocol and is aimed at describing interfaces between both software and hardware modules or a combination of the two....... The model describes both functional and timing properties of an interface...

  9. Free cooling potential of a PCM-based heat exchanger coupled with a novel HVAC system for simultaneous heating and cooling of buildings

    DEFF Research Database (Denmark)

    Maccarini, Alessandro; Hultmark, Göran; Bergsøe, Niels Christian

    2018-01-01

    . In particular, a model of a PCM-based heat exchanger was developed in this work by using the programming language Modelica. This device was designed to store cold energy during night-time and release it during daytime through the water circuit. Results for a typical office building model showed...... that the integration of free cooling devices can significantly reduce the primary energy use of the novel HVAC system. In particular, the thermal plant configuration including the PCM-based heat exchanger made it possible to almost completely avoid the use of mechanical cooling, leading to annual primary energy......This article presents a simulation-based study that estimates the primary energy use of a novel HVAC system for different configurations of a thermal plant. The main characteristic of the system is its ability to provide simultaneous heating and cooling to buildings by using a single hydronic...

  10. Probing the Conformational and Functional Consequences of Disulfide Bond Engineering in Growth Hormone by Hydrogen-Deuterium Exchange Mass Spectrometry Coupled to Electron Transfer Dissociation

    DEFF Research Database (Denmark)

    Seger, Signe T; Breinholt, Jens; Faber, Johan H

    2015-01-01

    Human growth hormone (hGH), and its receptor interaction, is essential for cell growth. To stabilize a flexible loop between helices 3 and 4, while retaining affinity for the hGH receptor, we have engineered a new hGH variant (Q84C/Y143C). Here, we employ hydrogen-deuterium exchange mass spectrom......Human growth hormone (hGH), and its receptor interaction, is essential for cell growth. To stabilize a flexible loop between helices 3 and 4, while retaining affinity for the hGH receptor, we have engineered a new hGH variant (Q84C/Y143C). Here, we employ hydrogen-deuterium exchange mass...

  11. Qualitative and quantitative analysis of branches in dextran using high-performance anion exchange chromatography coupled to quadrupole time-of-flight mass spectrometry.

    Science.gov (United States)

    Yi, Lin; Ouyang, Yilan; Sun, Xue; Xu, Naiyu; Linhardt, Robert J; Zhang, Zhenqing

    2015-12-04

    Dextran, a family of natural polysaccharides, consists of an α (1→6) linked-glucose main (backbone) chain having a number of branches. The determination of the types and the quantities of branches in dextran is important in understanding its various biological roles. In this study, a hyphenated method using high-performance anion exchange chromatography (HPAEC) in parallel with pulsed amperometric detection (PAD) and mass spectrometry (MS) was applied to qualitative and quantitative analysis of dextran branches. A rotary cation-exchange cartridge array desalter was used for removal of salt from the HPAEC eluent making it MS compatible. MS and MS/MS were used to provide structural information on the enzymatically prepared dextran oligosaccharides. PAD provides quantitative data on the ratio of enzyme-resistant, branched dextran oligosaccharides. Both the types and degree of branching found in a variety of dextrans could be simultaneously determined online using this method. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Addition by subtraction in coupled-cluster theory: a reconsideration of the CC and CI interface and the nCC hierarchy.

    Science.gov (United States)

    Bartlett, Rodney J; Musiał, Monika

    2006-11-28

    The nCC hierarchy of coupled-cluster approximations, where n guarantees exactness for n electrons and all products of n electrons are derived and applied to several illustrative problems. The condition of exactness for n=2 defines nCCSD=2CC, with nCCSDT=3CC and nCCSDTQ=4CC being exact for three and four electrons. To achieve this, the minimum number of diagrams is evaluated, which is less than in the corresponding CC model. For all practical purposes, nCC is also the proper definition of a size-extensive CI. 2CC is also an orbitally invariant coupled electron pair approximation. The numerical results of nCC are close to those for the full CC variant, and in some cases are closer to the full CI reference result. As 2CC is exact for separated electron pairs, it is the natural zeroth-order approximation for the correlation problem in molecules with other effects introduced as these units start to interact. The nCC hierarchy of approximations has all the attractive features of CC including its size extensivity, orbital invariance, and orbital insensitivity, but in a conceptually appealing form suited to bond breaking, while being computationally less demanding. Excited states from the equation of motion (EOM-2CC) are also reported, which show results frequently approaching those of EOM-CCSDT.

  13. Methodology for coupling computational fluid dynamics and integral transport neutronics

    International Nuclear Information System (INIS)

    Thomas, J. W.; Zhong, Z.; Sofu, T.; Downar, T. J.

    2004-01-01

    The CFD code STAR-CD was coupled to the integral transport code DeCART in order to provide high-fidelity, full physics reactor simulations. An interface program was developed to perform the tasks of mapping the STAR-CD mesh to the DeCART mesh, managing all communication between STAR-CD and DeCART, and monitoring the convergence of the coupled calculations. The interface software was validated by comparing coupled calculation results with those obtained using an independently developed interface program. An investigation into the convergence characteristics of coupled calculations was performed using several test models on a multiprocessor LINUX cluster. The results indicate that the optimal convergence of the coupled field calculation depends on several factors, to include the tolerance of the STAR-CD solution and the number of DeCART transport sweeps performed before exchanging data between codes. Results for a 3D, multi-assembly PWR problem on 12 PEs of the LINUX cluster indicate the best performance is achieved when the STAR-CD tolerance and number of DeCART transport sweeps are chosen such that the two fields converge at approximately the same rate. (authors)

  14. Transport processes at fluidic interfaces

    CERN Document Server

    Reusken, Arnold

    2017-01-01

    There are several physico-chemical processes that determine the behavior of multiphase fluid systems – e.g., the fluid dynamics in the different phases and the dynamics of the interface(s), mass transport between the fluids, adsorption effects at the interface, and transport of surfactants on the interface – and result in heterogeneous interface properties. In general, these processes are strongly coupled and local properties of the interface play a crucial role. A thorough understanding of the behavior of such complex flow problems must be based on physically sound mathematical models, which especially account for the local processes at the interface. This book presents recent findings on the rigorous derivation and mathematical analysis of such models and on the development of numerical methods for direct numerical simulations. Validation results are based on specifically designed experiments using high-resolution experimental techniques. A special feature of this book is its focus on an interdisciplina...

  15. Moessbauer-spectroscopic study of structure and magnetism of the exchange-coupled layer systems Fe/FeSn{sub 2}, and Fe/FeSi/Si and the ion-implanted diluted magnetic semiconductor SiC(Fe); Moessbauerspektroskopische Untersuchung von Struktur und Magnetismus der austauschgekoppelten Schichtsysteme Fe/FeSn{sub 2} und Fe/FeSi/Si und des ionenimplantierten verduennten magnetischen Halbleiters SiC(Fe)

    Energy Technology Data Exchange (ETDEWEB)

    Stromberg, Frank

    2009-07-07

    In line with this work the structural and magnetic properties of the exchange coupled layered systems Fe/FeSn{sub 2} and Fe/FeSi/Si and of the Fe ion implanted diluted magnetic semiconductor (DMS) SiC(Fe) were investigated. The main measuring method was the isotope selective {sup 57}Fe conversion electron Moessbauer spectroscopy (CEMS), mostly in connection with the {sup 57}Fe tracer layer technique, in a temperature range from 4.2 K to 340 K. Further measurement techniques were X-ray diffraction (XRD), electron diffraction (LEED, RHEED), SQUID magnetometry and FMR (Ferromagnetic Resonance). In the first part of this work the properties of thin AF FeSn{sub 2}(001) films and of the exchange-bias system Fe/FeSn{sub 2}(001) on InSb(001) were investigated. With the application of {sup 57}Fe-tracer layers and CEMS both the Fe-spin structure and the temperature dependence of the magnetic hyperfine field (B{sub hf}) of FeSn{sub 2} could be examined. The evaporation of Fe films on the FeSn{sub 2} films produced in the latter ones a high perpendicular spin component at the Fe/FeSn{sub 2} interface. In some distance from the interface the Fe spins rotate back into the sample plane. Furthermore {sup 57}Fe-CEMS provided a correlation between the absolute value of the exchange field vertical stroke He vertical stroke and the amount of magnetic defects within the FeSn{sub 2}. Temperature dependent CEMS-measurements yielded informations about the spin dynamics within the AF. The transition temperatures T{sub B}{sup *}, which were interpreted as superparamagnetic blocking temperatures, obtain higher values compared to the temperatures T{sub B} of the exchange-bias effect, obtained with magnetometry measurements. The second part of this work deals with the indirect exchange coupling within Fe/FeSi/Si/FeSi/Fe multilayers and FeSi diffusion barriers. The goal was to achieve Fe free Si interlayers. The CEMS results show that starting from a thickness of t{sub FeSi}=10-12 A of the

  16. On-line coupling of a miniaturized bioreactor with capillary electrophoresis, via a membrane interface, for monitoring the production of organic acids by microorganisms.

    Science.gov (United States)

    Ehala, S; Vassiljeva, I; Kuldvee, R; Vilu, R; Kaljurand, M

    2001-09-01

    Capillary electrophoresis (CE) can be a valuable tool for on-line monitoring of bioprocesses. Production of organic acids by phosphorus-solubilizing bacteria and fermentation of UHT milk were monitored and controlled by use of a membrane-interfaced dialysis device and a home-made microsampler for a capillary electrophoresis unit. Use of this specially designed sampling device enabled rapid consecutive injections without interruption of the high voltage. No additional sample preparation was required. The time resolution of monitoring in this particular work was approximately 2 h, but could be reduced to 2 min. Analytes were detected at low microg mL(-1) levels with a reproducibility of approximately 10%. To demonstrate the potential of CE in processes of biotechnological interest, results from monitoring phosphate solubilization by bacteria were submitted to qualitative and quantitative analysis. Fermentation experiments on UHT milk showed that monitoring of the processes by CE can provide good resolution of complex mixtures, although for more specific, detailed characterization the identification of individual substances is needed.

  17. A Slater parameter optimisation interface for the CIV3 atomic structure code and its possible use with the R-matrix close coupling collision code

    International Nuclear Information System (INIS)

    Fawcett, B.C.; Hibbert, A.

    1989-11-01

    Details are here provided of amendments to the atomic structure code CIV3 which allow the optional adjustment of Slater parameters and average energies of configurations so that they result in improved energy levels and eigenvectors. It is also indicated how, in principle, the resultant improved eigenvectors can be utilised by the R-matrix collision code, thus providing an optimised target for close coupling collision strength calculations. An analogous computational method was recently reported for distorted wave collision strength calculations and applied to Fe XIII. The general method is suitable for the computation of collision strengths for complex ions and in some cases can then provide a basis for collision strength calculations in ions where ab initio computations break down or result in unnecessarily large errors. (author)

  18. NCX-DB: a unified resource for integrative analysis of the sodium calcium exchanger super-family.

    Science.gov (United States)

    Bode, Katrin; O'Halloran, Damien M

    2018-04-13

    Na + /Ca 2+ exchangers are low-affinity high-capacity transporters that mediate Ca 2+ extrusion by coupling Ca 2+ efflux to the influx of Na + ions. The Na + /Ca 2+ exchangers form a super-family comprised of three branches each differing in ion-substrate selectivity: Na + /Ca 2+ exchangers (NCX), Na + /Ca 2+ /K + exchangers, and Ca 2+ /cation exchangers. Their primary function is to maintain Ca 2+ homeostasis and play a particularly important role in excitable cells that experience transient Ca 2+ fluxes. Research into the role and activity of Na + /Ca 2+ exchangers has focused extensively on the cardio-vascular system, however, growing evidence suggests that Na + /Ca 2+ exchangers play a key role in neuronal processes such as memory formation, learning, oligodendrocyte differentiation, neuroprotection during brain ischemia and axon guidance. They have also been implicated in pathologies such as Alzheimer's disease, Parkinson's disease, Multiple Sclerosis and Epilepsy, however, a clear understanding of their mechanism during disease is lacking. To date, there has never been a central resource or database for Na + /Ca 2+ exchangers. With clear disease relevance and ever-increasing research on Na + /Ca 2+ exchangers from both model and non-model species, a database that unifies the data on Na + /Ca 2+ exchangers is needed for future research. NCX-DB is a publicly available database with a web interface that enables users to explore various Na + /Ca 2+ exchangers, perform cross-species sequence comparison, identify new exchangers, and stay-up to date with recent literature. NCX-DB is available on the web via an interactive user interface with an intuitive design, which is applicable for the identification and comparison of Na + /Ca 2+ exchanger proteins across diverse species.

  19. 225-B ion exchange piping design documentation

    International Nuclear Information System (INIS)

    Prather, M.C.

    1996-02-01

    This document describes the interface between the planned permanent ion exchange piping system and the planned portable ion exchange system. This is part of the Waste Encapsulation and Storage Facility (WESF). In order to decouple this WESF from B-Plant and to improve recovery from a capsule leak, contaminated pool cell water will be recirculated through a portable ion exchange resin system

  20. Ultralow-frequency Raman system down to 10 cm{sup −1} with longpass edge filters and its application to the interface coupling in t(2+2)LGs

    Energy Technology Data Exchange (ETDEWEB)

    Lin, M.-L.; Qiao, X.-F.; Wu, J.-B.; Shi, W.; Tan, P.-H., E-mail: phtan@semi.ac.cn [State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China); Ran, F.-R.; Li, H. [Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials - SICAM, Nanjing Tech University - NanjingTech, 30 South Puzhu Road, Nanjing 211816 (China); Zhang, Z.-H.; Xu, X.-Z.; Liu, K.-H. [School of Physics, Center for Nanochemistry, Collaborative Innovation Center of Quantum Matter, Peking University, Beijing 100871 (China)

    2016-05-15

    Ultralow-frequency (ULF) Raman spectroscopy becomes increasingly important in the area of two-dimensional (2D) layered materials; however, such measurement usually requires expensive and nonstandard equipment. Here, the measurement of ULF Raman signal down to 10 cm{sup −1} has been realized with high throughput by combining a kind of longpass edge filters with a single monochromator, which are verified by the Raman spectrum of L-cystine using three laser excitations. Fine adjustment of the angle of incident laser beam from normal of the longpass edge filters and selection of polarization geometry are demonstrated how to probe ULF Raman signal with high signal-to-noise. Davydov splitting of the shear mode in twisted (2+2) layer graphenes (t(2+2)LG) has been observed by such system in both exfoliated and transferred samples. We provide a direct evidence of twist-angle dependent softening of the shear coupling in t(2+2)LG, while the layer-breathing coupling at twisted interfaces is found to be almost identical to that in bulk graphite. This suggests that the exfoliation and transferring techniques are enough good to make a good 2D heterostructures to demonstrate potential device application. This Raman system will be potentially applied to the research field of ULF Raman spectroscopy.

  1. Fluid mechanics of environmental interfaces

    CERN Document Server

    Gualtieri, Carlo

    2008-01-01

    Fluid Mechanics of Environmental Interfaces describes the concept of the environmental interface, defined as a surface between two either abiotic or biotic systems. These are in relative motion and exchange mass, heat and momentum through biophysical and/or chemical processes. These processes are fluctuating temporally and spatially.The book will be of interest to graduate students, PhD students as well as researchers in environmental sciences, civil engineering and environmental engineering, (geo)physics and applied mathematics.

  2. Offline coupling of low-pressure anion-exchange chromatography with MALDI-MS to determine the elution order of human milk oligosaccharides.

    Science.gov (United States)

    Finke, B; Mank, M; Daniel, H; Stahl, B

    2000-09-10

    Pooled human milk oligosaccharides were separated into neutral and several acidic oligosaccharide fractions by preparative anion-exchange chromatography (AEC) using AG 1-X2. The oligosaccharides were eluted stepwise using deionized water and three different concentrations of ammonium acetate buffer, pH 6.8. The elution order of the compounds was determined directly by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis of the AEC effluent without any cleanup or concentration steps. Up to a concentration of 500 mM ammonium acetate, the masses of acidic oligosaccharides could be detected by screening the fractions in an automated mode. The combination of the improved chromatographic procedure, the applied MALDI matrices, and operating parameters is suitable for the detection of neutral oligosaccharides as well as acidic oligosaccharides. The method provides high sensitivity and mass accuracy, including for the high-molecular-weight monosialylated oligosaccharides up to 2751.5 Da. The applied ionic strength of the anion-exchange eluents enables a rapid and an unambiguous composition assignment by MALDI-MS for neutral, monosialylated, and disialylated oligosaccharides from human milk. The acidic fractions have to be desalted by electrodialysis and were finally analyzed by HPAEC-PAD to get a high-resolution "fingerprint" of structures present in each fraction. From these analyses, it can be concluded that the isomeric variety of monosialylated oligosaccharides occurring in human milk is higher than estimated before. Copyright 2000 Academic Press.

  3. High temperature interface superconductivity

    International Nuclear Information System (INIS)

    Gozar, A.; Bozovic, I.

    2016-01-01

    Highlight: • This review article covers the topic of high temperature interface superconductivity. • New materials and techniques used for achieving interface superconductivity are discussed. • We emphasize the role played by the differences in structure and electronic properties at the interface with respect to the bulk of the constituents. - Abstract: High-T_c superconductivity at interfaces has a history of more than a couple of decades. In this review we focus our attention on copper-oxide based heterostructures and multi-layers. We first discuss the technique, atomic layer-by-layer molecular beam epitaxy (ALL-MBE) engineering, that enabled High-T_c Interface Superconductivity (HT-IS), and the challenges associated with the realization of high quality interfaces. Then we turn our attention to the experiments which shed light on the structure and properties of interfacial layers, allowing comparison to those of single-phase films and bulk crystals. Both ‘passive’ hetero-structures as well as surface-induced effects by external gating are discussed. We conclude by comparing HT-IS in cuprates and in other classes of materials, especially Fe-based superconductors, and by examining the grand challenges currently laying ahead for the field.

  4. Environmental materials and interfaces

    International Nuclear Information System (INIS)

    1991-11-01

    A workshop that explored materials and interfaces research needs relevant to national environmental concerns was conducted at Pacific Northwest Laboratory. The purposes of the workshop were to refine the scientific research directions being planned for the Materials and Interface Program in the Molecular Science Research Center (MSRC) and further define the research and user equipment to the included as part of the proposed Environmental and Molecular Science Laboratory (EMSL). Three plenary information sessions served to outline the background, objectives, and status of the MSRC and EMSL initiatives; selected specific areas with environmentally related materials; and the status of capabilities and facilities planned for the EMSL. Attention was directed to four areas where materials and interface science can have a significant impact on prevention and remediation of environmental problems: in situ detection and characterization of hazardous wastes (sensors), minimization of hazardous waste (separation membranes, ion exchange materials, catalysts), waste containment (encapsulation and barrier materials), and fundamental understanding of contaminant transport mechanisms. During all other sessions, the participants were divided into three working groups for detailed discussion and the preparation of a written report. The working groups focused on the areas of interface structure and chemistry, materials and interface stability, and materials synthesis. These recommendations and suggestions for needed research will be useful for other researchers in proposing projects and for suggesting collaborative work with MSRC researchers. 1 fig

  5. Organic interfaces

    NARCIS (Netherlands)

    Poelman, W.A.; Tempelman, E.

    2014-01-01

    This paper deals with the consequences for product designers resulting from the replacement of traditional interfaces by responsive materials. Part 1 presents a theoretical framework regarding a new paradigm for man-machine interfacing. Part 2 provides an analysis of the opportunities offered by new

  6. Interface Realisms

    DEFF Research Database (Denmark)

    Pold, Søren

    2005-01-01

    This article argues for seeing the interface as an important representational and aesthetic form with implications for postmodern culture and digital aesthetics. The interface emphasizes realism due in part to the desire for t