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Sample records for high-field pulsed epr

  1. High-field EPR spectroscopy of thermal donors in silicon

    DEFF Research Database (Denmark)

    Dirksen, R.; Rasmussen, F.B.; Gregorkiewicz, T.

    1997-01-01

    Thermal donors generated in p-type boron-doped Czochralski-grown silicon by a 450 degrees C heat treatment have been studied by high-field magnetic resonance spectroscopy. In the experiments conducted at a microwave frequency of 140 GHz and in a magnetic field of approximately 5 T four individual...

  2. Use of the Frank sequence in pulsed EPR

    DEFF Research Database (Denmark)

    Tseitlin, Mark; Quine, Richard W.; Eaton, Sandra S.;

    2011-01-01

    The Frank polyphase sequence has been applied to pulsed EPR of triarylmethyl radicals at 256MHz (9.1mT magnetic field), using 256 phase pulses. In EPR, as in NMR, use of a Frank sequence of phase steps permits pulsed FID signal acquisition with very low power microwave/RF pulses (ca. 1.5m......W in the application reported here) relative to standard pulsed EPR. A 0.2mM aqueous solution of a triarylmethyl radical was studied using a 16mm diameter cross-loop resonator to isolate the EPR signal detection system from the incident pulses. Keyword: Correlation spectroscopy,Multi-pulse EPR,Low power pulses...

  3. High-Field EPR Spectroscopy on Transfer Proteins in Biological Action

    Science.gov (United States)

    Möbius, K.; Schnegg, A.; Plato, M.; Fuchs, M. R.; Savitsky, A.

    2006-08-01

    In the last decade joint efforts of biologists, chemists, and physicists were made to understand the dominant factors determining specificity and directionality of transmembrane transfer processes in proteins. Characteristic examples of such factors are time varying specific H-bonding patterns and/or polarity effects of the microenvironment. In this overview, a few large paradigm biosystems are surveyed which have been explored lately in our laboratory. Taking advantage of the improved spectral and temporal resolution of high-frequency/high-field EPR at 95 GHz/3.4 T and 360 GHz/12.9 T, as compared to conventional X-band EPR (9.5 GHz/0.34 T), three transfer proteins in action are characterized with respect to structure and dynamics: (1) light-induced electron-transfer intermediates in wild-type and mutant reaction-centre proteins from photosynthetic bacteria Rhodobacter sphaeroides, (2) light-driven proton-transfer intermediates of site-specifically nitroxide spin-labelled mutants of bacteriorhodopsin proteins from Halobacterium salinarium, (3) refolding intermediates of site-specifically nitroxide spin-labelled mutants of the channel-forming protein domain of Colicin A bacterial toxin produced in Escherichia coli. The information obtained is complementary to that of protein crystallography, solid-state NMR, infrared and optical spectroscopy techniques. A unique strength of high-field EPR is particularly noteworthy: it can provide detailed information on transient intermediates of proteins in biological action. They can be observed and characterized while staying in their working states on biologically relevant time scales.

  4. Simultaneous acquisition of pulse EPR orientation selective spectra

    Science.gov (United States)

    Kaminker, Ilia; Florent, Marc; Epel, Boris; Goldfarb, Daniella

    2011-01-01

    High resolution pulse EPR methods are usually applied to resolve weak magnetic electron-nuclear or electron-electron interactions that are otherwise unresolved in the EPR spectrum. Complete information regarding different magnetic interactions, namely, principal components and orientation of principal axis system with respect to the molecular frame, can be derived from orientation selective pulsed EPR measurements that are performed at different magnetic field positions within the inhomogeneously broadened EPR spectrum. These experiments are usually carried out consecutively, namely a particular field position is chosen, data are accumulated until the signal to noise ratio is satisfactory, and then the next field position is chosen and data are accumulated. Here we present a new approach for data acquisition of pulsed EPR experiments referred to as parallel acquisition. It is applicable when the spectral width is much broader than the excitation bandwidth of the applied pulse sequence and it is particularly useful for orientation selective pulse EPR experiments. In this approach several pulse EPR measurements are performed within the waiting (repetition) time between consecutive pulse sequences during which spin lattice relaxation takes place. This is achieved by rapidly changing the main magnetic field, B0, to different values within the EPR spectrum, performing the same experiment on the otherwise idle spins. This scheme represents an efficient utilization of the spectrometer and provides the same spectral information in a shorter time. This approach is demonstrated on W-band orientation selective electron-nuclear double resonance (ENDOR), electron spin echo envelope modulation (ESEEM), electron-electron double resonance (ELDOR) - detected NMR and double electron-electron resonance (DEER) measurements on frozen solutions of nitroxides. We show that a factors of 3-6 reduction in total acquisition time can be obtained, depending on the experiment applied.

  5. High Field Pulse Magnets with New Materials

    Science.gov (United States)

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

    2004-11-01

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

  6. Accurate Extraction of Nanometer Distances in Multimers by Pulse EPR

    Science.gov (United States)

    Valera, Silvia; Ackermann, Katrin; Pliotas, Christos; Huang, Hexian; Naismith, James H.

    2016-01-01

    Abstract Pulse electron paramagnetic resonance (EPR) is gaining increasing importance in structural biology. The PELDOR (pulsed electron–electron double resonance) method allows extracting distance information on the nanometer scale. Here, we demonstrate the efficient extraction of distances from multimeric systems such as membrane‐embedded ion channels where data analysis is commonly hindered by multi‐spin effects. PMID:26865468

  7. Pulsed EPR in the method of spin labels and probes

    Energy Technology Data Exchange (ETDEWEB)

    Dzuba, Sergei A [Institute of Chemical Kinetics and Combustion, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2007-08-31

    Various pulsed EPR in the method of spin labels and probes based on electron spin echo spectroscopy (spin echo envelope modulation through electron-nuclear interactions, electron-electron double resonance, echo detected EPR, etc.) are considered. These methods provide information on the conformations of complex biomolecules, nanostructure of matter, depth of water penetration into biological membranes, supramolecular structure of multicomponent systems (membrane-peptide, etc.), co-operative orientational dynamics of molecules and dynamic low-temperature transitions in disordered molecular media and biosystems.

  8. Pulsed EPR in the method of spin labels and probes

    Science.gov (United States)

    Dzuba, Sergei A.

    2007-08-01

    Various pulsed EPR in the method of spin labels and probes based on electron spin echo spectroscopy (spin echo envelope modulation through electron-nuclear interactions, electron-electron double resonance, echo detected EPR, etc.) are considered. These methods provide information on the conformations of complex biomolecules, nanostructure of matter, depth of water penetration into biological membranes, supramolecular structure of multicomponent systems (membrane-peptide, etc.), co-operative orientational dynamics of molecules and dynamic low-temperature transitions in disordered molecular media and biosystems.

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

    Energy Technology Data Exchange (ETDEWEB)

    Campisi, I.E.

    1984-10-01

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

  10. A 140 GHz pulsed EPR/212 MHz NMR spectrometer for DNP studies

    Science.gov (United States)

    Smith, Albert A.; Corzilius, Björn; Bryant, Jeffrey A.; DeRocher, Ronald; Woskov, Paul P.; Temkin, Richard J.; Griffin, Robert G.

    2012-10-01

    We described a versatile spectrometer designed for the study of dynamic nuclear polarization (DNP) at low temperatures and high fields. The instrument functions both as an NMR spectrometer operating at 212 MHz (1H frequency) with DNP capabilities, and as a pulsed-EPR operating at 140 GHz. A coiled TE011 resonator acts as both an NMR coil and microwave resonator, and a double balanced (1H, 13C) radio frequency circuit greatly stabilizes the NMR performance. A new 140 GHz microwave bridge has also been developed, which utilizes a four-phase network and ELDOR channel at 8.75 GHz, that is then multiplied and mixed to obtain 140 GHz microwave pulses with an output power of 120 mW. Nutation frequencies obtained are as follows: 6 MHz on S = 1/2 electron spins, 100 kHz on 1H, and 50 kHz on 13C. We demonstrate basic EPR, ELDOR, ENDOR, and DNP experiments here. Our solid effect DNP results demonstrate an enhancement of 144 and sensitivity gain of 310 using OX063 trityl at 80 K and an enhancement of 157 and maximum sensitivity gain of 234 using Gd-DOTA at 20 K, which is significantly better performance than previously reported at high fields (⩾3 T).

  11. A 140 GHz pulsed EPR/212 MHz NMR spectrometer for DNP studies.

    Science.gov (United States)

    Smith, Albert A; Corzilius, Björn; Bryant, Jeffrey A; DeRocher, Ronald; Woskov, Paul P; Temkin, Richard J; Griffin, Robert G

    2012-10-01

    We described a versatile spectrometer designed for the study of dynamic nuclear polarization (DNP) at low temperatures and high fields. The instrument functions both as an NMR spectrometer operating at 212 MHz ((1)H frequency) with DNP capabilities, and as a pulsed-EPR operating at 140 GHz. A coiled TE(011) resonator acts as both an NMR coil and microwave resonator, and a double balanced ((1)H, (13)C) radio frequency circuit greatly stabilizes the NMR performance. A new 140 GHz microwave bridge has also been developed, which utilizes a four-phase network and ELDOR channel at 8.75 GHz, that is then multiplied and mixed to obtain 140 GHz microwave pulses with an output power of 120 mW. Nutation frequencies obtained are as follows: 6 MHz on S=1/2 electron spins, 100 kHz on (1)H, and 50 kHz on (13)C. We demonstrate basic EPR, ELDOR, ENDOR, and DNP experiments here. Our solid effect DNP results demonstrate an enhancement of 144 and sensitivity gain of 310 using OX063 trityl at 80 K and an enhancement of 157 and maximum sensitivity gain of 234 using Gd-DOTA at 20 K, which is significantly better performance than previously reported at high fields (≥3 T).

  12. New Developments in Spin Labels for Pulsed Dipolar EPR

    Directory of Open Access Journals (Sweden)

    Alistair J. Fielding

    2014-10-01

    Full Text Available Spin labelling is a chemical technique that enables the integration of a molecule containing an unpaired electron into another framework for study. Given the need to understand the structure, dynamics, and conformational changes of biomacromolecules, spin labelling provides a relatively non-intrusive technique and has certain advantages over X-ray crystallography; which requires high quality crystals. The technique relies on the design of binding probes that target a functional group, for example, the thiol group of a cysteine residue within a protein. The unpaired electron is typically supplied through a nitroxide radical and sterically shielded to preserve stability. Pulsed electron paramagnetic resonance (EPR techniques allow small magnetic couplings to be measured (e.g., <50 MHz providing information on single label probes or the dipolar coupling between multiple labels. In particular, distances between spin labels pairs can be derived which has led to many protein/enzymes and nucleotides being studied. Here, we summarise recent examples of spin labels used for pulse EPR that serve to illustrate the contribution of chemistry to advancing discoveries in this field.

  13. Active cancellation - A means to zero dead-time pulse EPR

    Science.gov (United States)

    Franck, John M.; Barnes, Ryan P.; Keller, Timothy J.; Kaufmann, Thomas; Han, Songi

    2015-12-01

    The necessary resonator employed in pulse electron paramagnetic resonance (EPR) rings after the excitation pulse and creates a finite detector dead-time that ultimately prevents the detection of signal from fast relaxing spin systems, hindering the application of pulse EPR to room temperature measurements of interesting chemical or biological systems. We employ a recently available high bandwidth arbitrary waveform generator (AWG) to produce a cancellation pulse that precisely destructively interferes with the resonant cavity ring-down. We find that we can faithfully detect EPR signal at all times immediately after, as well as during, the excitation pulse. This is a proof of concept study showcasing the capability of AWG pulses to precisely cancel out the resonator ring-down, and allow for the detection of EPR signal during the pulse itself, as well as the dead-time of the resonator. However, the applicability of this approach to conventional EPR experiments is not immediate, as it hinges on either (1) the availability of low-noise microwave sources and amplifiers to produce the necessary power for pulse EPR experiment or (2) the availability of very high conversion factor micro coil resonators that allow for pulse EPR experiments at modest microwave power.

  14. Arbitrary waveform modulated pulse EPR at 200 GHz

    Science.gov (United States)

    Kaminker, Ilia; Barnes, Ryan; Han, Songi

    2017-06-01

    We report here on the implementation of arbitrary waveform generation (AWG) capabilities at ∼200 GHz into an Electron Paramagnetic Resonance (EPR) and Dynamic Nuclear Polarization (DNP) instrument platform operating at 7 T. This is achieved with the integration of a 1 GHz, 2 channel, digital to analog converter (DAC) board that enables the generation of coherent arbitrary waveforms at Ku-band frequencies with 1 ns resolution into an existing architecture of a solid state amplifier multiplier chain (AMC). This allows for the generation of arbitrary phase- and amplitude-modulated waveforms at 200 GHz with >150 mW power. We find that the non-linearity of the AMC poses significant difficulties in generating amplitude-modulated pulses at 200 GHz. We demonstrate that in the power-limited regime of ω1 10 MHz) spin manipulation in incoherent (inversion), as well as coherent (echo formation) experiments. Highlights include the improvement by one order of magnitude in inversion bandwidth compared to that of conventional rectangular pulses, as well as a factor of two in improvement in the refocused echo intensity at 200 GHz.

  15. High-field optically detected EPR and ENDOR of semiconductor defects using W-band microwave Fabry-Pérot resonators.

    Science.gov (United States)

    Spaeth, J-M; Tkach, I; Greulich-Weber, S; Overhof, H

    2005-11-01

    The designs of W-band (approximately 95 GHz) Fabry-Pérot microwave resonators for optically detected EPR and ENDOR using the magnetic circular dichroism of the optical absorption (MCDA) as well as for photo-luminescence-detected EPR are briefly described. We report on the first MCDA-detected high-field EPR/ENDOR investigation of the paramagnetic EL2+ defect in semi-insulating GaAs. The higher-order effects, which prevented the unambiguous analysis of previous MCDA-detected K-band EPR/ENDOR experiments could be suppressed in W-band. The analysis of the ENDOR spectra showed that an extremely precise alignment of the samples is necessary. The paramagnetic El2+ defect turned out to be an As antisite defect, which has four almost equivalent nearest 75As neighbours differing less than 1.5% in the superhyperfine interactions suggestive of an isolated As antisite, while the third 75As shell (fifth neighbour shell) is clearly of lower symmetry than expected for an isolated As antisite. We discuss as a possible solution to this paradoxical situation that EL2+ is an isolated antisite at room temperature, which at low temperature, where all magnetic resonance experiments are performed, associates itself with shallow acceptors such as Zn(Ga)- more than two nearest neighbour distances away. According to recent theoretical calculations, such 'loose' complexes with binding energies between 0.01 eV and 0.05 eV and disturb the equivalence of the nearest neighbour superhyperfine (shf) interactions less than 1.5%. Also, W-band EPR was measured using the photo-luminescence for detection to investigate P dopants in 6H-SiC.

  16. Increasing sensitivity of pulse EPR experiments using echo train detection schemes

    Science.gov (United States)

    Mentink-Vigier, F.; Collauto, A.; Feintuch, A.; Kaminker, I.; Tarle, V.; Goldfarb, D.

    2013-11-01

    Modern pulse EPR experiments are routinely used to study the structural features of paramagnetic centers. They are usually performed at low temperatures, where relaxation times are long and polarization is high, to achieve a sufficient Signal/Noise Ratio (SNR). However, when working with samples whose amount and/or concentration are limited, sensitivity becomes an issue and therefore measurements may require a significant accumulation time, up to 12 h or more. As the detection scheme of practically all pulse EPR sequences is based on the integration of a spin echo - either primary, stimulated or refocused - a considerable increase in SNR can be obtained by replacing the single echo detection scheme by a train of echoes. All these echoes, generated by Carr-Purcell type sequences, are integrated and summed together to improve the SNR. This scheme is commonly used in NMR and here we demonstrate its applicability to a number of frequently used pulse EPR experiments: Echo-Detected EPR, Davies and Mims ENDOR (Electron-Nuclear Double Resonance), DEER (Electron-Electron Double Resonance|) and EDNMR (Electron-Electron Double Resonance (ELDOR)-Detected NMR), which were combined with a Carr-Purcell-Meiboom-Gill (CPMG) type detection scheme at W-band. By collecting the transient signal and integrating a number of refocused echoes, this detection scheme yielded a 1.6-5 folds SNR improvement, depending on the paramagnetic center and the pulse sequence applied. This improvement is achieved while keeping the experimental time constant and it does not introduce signal distortion.

  17. High Fidelity Single Qubit Operations using Pulsed EPR

    CERN Document Server

    Morton, J J L; Ardavan, A; Porfyrakis, K; Lyon, S A; Briggs, G A D; Morton, John J. L.; Tyryshkin, Alexei M.; Ardavan, Arzhang; Porfyrakis, Kyriakos

    2005-01-01

    The fidelity of quantum logic operations performed on electron spin qubits using simple RF pulses falls well below the threshold for the application of quantum algorithms. Using three independent techniques, we demonstrate the use of composite pulses to improve this fidelity by several orders of magnitude. The observed high-fidelity operations are limited by pulse phase errors, but nevertheless fall within the limits required for the application of quantum error correction algorithms.

  18. CW- and pulsed-EPR of carbonaceous matter in primitive meteorites: solving a lineshape paradox.

    Science.gov (United States)

    Delpoux, Olivier; Gourier, Didier; Binet, Laurent; Vezin, Hervé; Derenne, Sylvie; Robert, François

    2008-05-01

    Insoluble organic matter (IOM) of Orgueil and Tagish Lake meteorites are studied by CW-EPR and pulsed-EPR spectroscopies. The EPR line is due to polycyclic paramagnetic moieties concentrated in defect-rich regions of the IOM, with concentrations of the order of 4x10(19) spin/g. CW-EPR reveals two types of paramagnetic defects: centres with S=1/2, and centres with S=0 ground state and thermally accessible triple state S=1. In spite of the Lorentzian shape of the EPR and its narrowing upon increasing the spin concentration, the EPR line is not in the exchange narrowing regime as previously deduced from multi-frequency CW-EPR [L. Binet, D. Gourier, Appl. Magn. Reson. 30 (2006) 207-231]. It is inhomogeneously broadened as demonstrated by the presence of nuclear modulations in the spin-echo decay. The line narrowing, similar to an exchange narrowing effect, is the result of an increasing contribution of the narrow line of the triplet state centres in addition to the broader line of doublet states. Hyperfine sublevel correlation spectroscopy (HYSCORE) of hydrogen and (13)C nuclei indicates that IOM* centres are small polycyclic moieties that are moderately branched with aliphatic chains, as shown by the presence of aromatic hydrogen atoms. On the contrary the lack of such aromatic hydrogen in triplet states suggests that these radicals are most probably highly branched. Paramagnetic centres are considerably enriched in deuterium, with D/H approximately 1.5+/-0.5x10(-2) of the order of values existing in interstellar medium.

  19. Identification of slow relaxing spin components by pulse EPR techniques in graphene-related materials

    Directory of Open Access Journals (Sweden)

    Antonio Barbon

    2017-01-01

    Full Text Available Electron Paramagnetic Resonance (EPR is a powerful technique that is suitable to study graphene-related materials. The challenging ability requested to the spectroscopy is its capability to resolve the variety of structures, relatively similar, that are obtained in materials produced through different methods, but that also coexist inside a single sample. In general, because of the intrinsic inhomogeneity of the samples, the EPR spectra are therefore a superposition of spectra coming from different structures. We show that by pulse EPR techniques (echo-detected EPR, ESEEM and Mims ENDOR we can identify and characterize species with slow spin relaxing properties. These species are generally called molecular states, and are likely small pieces of graphenic structures of limited dimensions, thus conveniently described by a molecular approach. We have studied commercial reduced graphene oxide and chemically exfoliated graphite, which are characterized by different EPR spectra. Hyperfine spectroscopies enabled us to characterize the molecular components of the different materials, especially in terms of the interaction of the unpaired electrons with protons (number of protons and hyperfine coupling constants. We also obtained useful precious information about extent of delocalization of the molecular states.

  20. SPIDYAN, a MATLAB library for simulating pulse EPR experiments with arbitrary waveform excitation.

    Science.gov (United States)

    Pribitzer, Stephan; Doll, Andrin; Jeschke, Gunnar

    2016-02-01

    Frequency-swept chirp pulses, created with arbitrary waveform generators (AWGs), can achieve inversion over a range of several hundreds of MHz. Such passage pulses provide defined flip angles and increase sensitivity. The fact that spectra are not excited at once, but single transitions are passed one after another, can cause new effects in established pulse EPR sequences. We developed a MATLAB library for simulation of pulse EPR, which is especially suited for modeling spin dynamics in ultra-wideband (UWB) EPR experiments, but can also be used for other experiments and NMR. At present the command line controlled SPin DYnamics ANalysis (SPIDYAN) package supports one-spin and two-spin systems with arbitrary spin quantum numbers. By providing the program with appropriate spin operators and Hamiltonian matrices any spin system is accessible, with limits set only by available memory and computation time. Any pulse sequence using rectangular and linearly or variable-rate frequency-swept chirp pulses, including phase cycling can be quickly created. To keep track of spin evolution the user can choose from a vast variety of detection operators, including transition selective operators. If relaxation effects can be neglected, the program solves the Liouville-von Neumann equation and propagates spin density matrices. In the other cases SPIDYAN uses the quantum mechanical master equation and Liouvillians for propagation. In order to consider the resonator response function, which on the scale of UWB excitation limits bandwidth, the program includes a simple RLC circuit model. Another subroutine can compute waveforms that, for a given resonator, maintain a constant critical adiabaticity factor over the excitation band. Computational efficiency is enhanced by precomputing propagator lookup tables for the whole set of AWG output levels. The features of the software library are discussed and demonstrated with spin-echo and population transfer simulations.

  1. Structural and dynamical characteristics of trehalose and sucrose matrices at different hydration levels as probed by FTIR and high-field EPR.

    Science.gov (United States)

    Malferrari, M; Nalepa, A; Venturoli, G; Francia, F; Lubitz, W; Möbius, K; Savitsky, A

    2014-06-07

    Some organisms can survive complete dehydration and high temperatures by adopting an anhydrobiotic state in which the intracellular medium contains large amounts of disaccharides, particularly trehalose and sucrose. Trehalose is most effective also in protecting isolated in vitro biostructures. In an attempt to clarify the molecular mechanisms of disaccharide bioprotection, we compared the structure and dynamics of sucrose and trehalose matrices at different hydration levels by means of high-field W-band EPR and FTIR spectroscopy. The hydration state of the samples was characterized by FTIR spectroscopy and the structural organization was probed by EPR using a nitroxide radical dissolved in the respective matrices. Analysis of the EPR spectra showed that the structure and dynamics of the dehydrated matrices as well as their evolution upon re-hydration differ substantially between trehalose and sucrose. The dehydrated trehalose matrix is homogeneous in terms of distribution of the residual water and spin-probe molecules. In contrast, dehydrated sucrose forms a heterogeneous matrix. It is comprised of sucrose polycrystalline clusters and several bulk water domains. The amorphous form was found only in 30% (volume) of the sucrose matrix. Re-hydration leads to a structural homogenization of the sucrose matrix, whilst in the trehalose matrix several domains develop differing in the local water/radical content and radical mobility. The molecular model of the matrices provides an explanation for the different protein-matrix dynamical coupling observed in dried ternary sucrose and trehalose matrices, and accounts for the superior efficacy of trehalose as a bioprotectant. Furthermore, for bacterial photosynthetic reaction centers it is shown that at low water content the protein-matrix coupling is modulated by the sugar/protein molar ratio in sucrose matrices only. This effect is suggested to be related to the preference for sucrose, rather than trehalose, as a

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-06-17

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-01

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

  4. Applications of pulsed EPR spectroscopy to structural studies of sulfite oxidizing enzymes

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Eric L.; Astashkin, Andrei V.; Raitsimring, Arnold M.; Enemark, John H.

    2013-01-01

    Sulfite oxidizing enzymes (SOEs), including sulfite oxidase (SO) and bacterial sulfite dehydrogenase (SDH), catalyze the oxidation of sulfite (SO32-) to sulfate (SO42-). The active sites of SO and SDH are nearly identical, each having a 5-coordinate, pseudo-square-pyramidal Mo with an axial oxo ligand and three equatorial sulfur donor atoms. One sulfur is from a conserved Cys residue and two are from a pyranopterindithiolene (molybdopterin, MPT) cofactor. The identity of the remaining equatorial ligand, which is solvent-exposed, varies during the catalytic cycle. Numerous in vitro studies, particularly those involving electron paramagnetic resonance (EPR) spectroscopy of the Mo(V) states of SOEs, have shown that the identity and orientation of this exchangeable equatorial ligand depends on the buffer pH, the presence and concentration of certain anions in the buffer, as well as specific point mutations in the protein. Until very recently, however, EPR has not been a practical technique for directly probing specific structures in which the solvent-exposed, exchangeable ligand is an O, OH-, H2O, SO32-, or SO42- group, because the primary O and S isotopes (16O and 32S) are magnetically silent (I = 0). This review focuses on the recent advances in the use of isotopic labeling, variable-frequency high resolution pulsed EPR spectroscopy, synthetic model compounds, and DFT calculations to elucidate the roles of various anions, point mutations, and steric factors in the formation, stabilization, and transformation of SOE active site structures.

  5. Pulsed electron-electron double resonance (PELDOR) as EPR spectroscopy in nanometre range

    Energy Technology Data Exchange (ETDEWEB)

    Tsvetkov, Yu D; Milov, A D; Maryasov, A G [Institute of Chemical Kinetics and Combustion, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2008-06-30

    The results of development of pulsed electron-electron double resonance (PELDOR) method and its applications in structural studies are generalised and described systematically. The foundations of the theory of the method are outlined, some methodological features and applications are considered, in particular, determination of the distances between spin labels in the nanometre range for iminoxyl biradicals, spin-labelled biomacromolecules, radical ion pairs and peptide-membrane complexes. The attention is focussed on radical systems that form upon self-assembly of nanosized complexes (in particular, peptide complexes), spatial effects, and radical pairs in photolysis and photosynthesis. The position of PELDOR among other structural EPR techniques is analysed.

  6. The new high field photoexcitation muon spectrometer at the ISIS pulsed neutron and muon source

    CERN Document Server

    Yokoyama, K; Murahari, P; Wang, K; Dunstan, D J; Waller, S P; McPhail, D J; Hillier, A D; Henson, J; Harper, M R; Heathcote, P; Drew, A J

    2016-01-01

    A high power pulsed laser system has been installed on the high magnetic field muon instrument (HiFi) at the ISIS pulsed neutron and muon source, situated at the STFC Rutherford Appleton Laboratory in the UK. The upgrade enables one to perform light-pump muon-probe experiments under a high field, which opens up a brand-new area in the muon spin spectroscopy. In this report we overview the principle of the HiFi Laser system, and describe the newly developed techniques and devices that enable a controlled photoexcitation in the muon instrument. A demonstration experiment illustrates the unique combination of the photoexcited system and avoided level crossing technique.

  7. Water accessibility in a membrane-inserting peptide comparing Overhauser DNP and pulse EPR methods

    Science.gov (United States)

    Segawa, Takuya F.; Doppelbauer, Maximilian; Garbuio, Luca; Doll, Andrin; Polyhach, Yevhen O.; Jeschke, Gunnar

    2016-05-01

    Water accessibility is a key parameter for the understanding of the structure of biomolecules, especially membrane proteins. Several experimental techniques based on the combination of electron paramagnetic resonance (EPR) spectroscopy with site-directed spin labeling are currently available. Among those, we compare relaxation time measurements and electron spin echo envelope modulation (ESEEM) experiments using pulse EPR with Overhauser dynamic nuclear polarization (DNP) at X-band frequency and a magnetic field of 0.33 T. Overhauser DNP transfers the electron spin polarization to nuclear spins via cross-relaxation. The change in the intensity of the 1H NMR spectrum of H2O at a Larmor frequency of 14 MHz under a continuous-wave microwave irradiation of the nitroxide spin label contains information on the water accessibility of the labeled site. As a model system for a membrane protein, we use the hydrophobic α-helical peptide WALP23 in unilamellar liposomes of DOPC. Water accessibility measurements with all techniques are conducted for eight peptides with different spin label positions and low radical concentrations (10-20 μM). Consistently in all experiments, the water accessibility appears to be very low, even for labels positioned near the end of the helix. The best profile is obtained by Overhauser DNP, which is the only technique that succeeds in discriminating neighboring positions in WALP23. Since the concentration of the spin-labeled peptides varied, we normalized the DNP parameter ɛ, being the relative change of the NMR intensity, by the electron spin concentration, which was determined from a continuous-wave EPR spectrum.

  8. High Field Pulsed Magnets for Neutron Scattering at the Spallation Neutron Source

    Science.gov (United States)

    Granroth, G. E.; Lee, J.; Fogh, E.; Christensen, N. B.; Toft-Petersen, R.; Nojiri, H.

    2015-03-01

    A High Field Pulsed Magnet (HFPM) setup, is in use at the Spallation Nuetron Source(SNS), Oak Ridge National Laboratory. With this device, we recently measured the high field magnetic spin structure of LiNiPO4. The results of this study will be highlighted as an example of possible measurements that can be performed with this device. To further extend the HFPM capabilities at SNS, we have learned to design and wind these coils in house. This contribution will summarize the magnet coil design optimization procedure. Specifically by varying the geometry of the multi-layer coil, we arrive at a design that balances the maximum field strength, neutron scattering angle, and the field homogeneity for a specific set of parameters. We will show that a 6.3kJ capacitor bank, can provide a magnetic field as high as 30T for a maximum scattering angle around 40° with homogeneity of +/- 4 % in a 2mm diameter spherical volume. We will also compare the calculations to measurements from a recently wound test coil. This work was supported in part by the Lab Directors' Research and Development Fund of ORNL.

  9. Multi-frequency, multi-technique pulsed EPR investigation of the copper binding site of murine amyloid β peptide.

    Science.gov (United States)

    Kim, Donghun; Bang, Jeong Kyu; Kim, Sun Hee

    2015-01-26

    Copper-amyloid peptides are proposed to be the cause of Alzheimer's disease, presumably by oxidative stress. However, mice do not produce amyloid plaques and thus do not suffer from Alzheimer's disease. Although much effort has been focused on the structural characterization of the copper- human amyloid peptides, little is known regarding the copper-binding mode in murine amyloid peptides. Thus, we investigated the structure of copper-murine amyloid peptides through multi-frequency, multi-technique pulsed EPR spectroscopy in conjunction with specific isotope labeling. Based on our pulsed EPR results, we found that Ala2, Glu3, His6, and His14 are directly coordinated with the copper ion in murine amyloid β peptides at pH 8.5. This is the first detailed structural characterization of the copper-binding mode in murine amyloid β peptides. This work may advance the knowledge required for developing inhibitors of Alzheimer's disease.

  10. Measuring aortic pulse wave velocity using high-field cardiovascular magnetic resonance: comparison of techniques

    Directory of Open Access Journals (Sweden)

    Shaffer Jean M

    2010-05-01

    Full Text Available Abstract Background The assessment of arterial stiffness is increasingly used for evaluating patients with different cardiovascular diseases as the mechanical properties of major arteries are often altered. Aortic stiffness can be noninvasively estimated by measuring pulse wave velocity (PWV. Several methods have been proposed for measuring PWV using velocity-encoded cardiovascular magnetic resonance (CMR, including transit-time (TT, flow-area (QA, and cross-correlation (XC methods. However, assessment and comparison of these techniques at high field strength has not yet been performed. In this work, the TT, QA, and XC techniques were clinically tested at 3 Tesla and compared to each other. Methods Fifty cardiovascular patients and six volunteers were scanned to acquire the necessary images. The six volunteer scans were performed twice to test inter-scan reproducibility. Patient images were analyzed using the TT, XC, and QA methods to determine PWV. Two observers analyzed the images to determine inter-observer and intra-observer variabilities. The PWV measurements by the three methods were compared to each other to test inter-method variability. To illustrate the importance of PWV using CMR, the degree of aortic stiffness was assessed using PWV and related to LV dysfunction in five patients with diastolic heart failure patients and five matched volunteers. Results The inter-observer and intra-observer variability results showed no bias between the different techniques. The TT and XC results were more reproducible than the QA; the mean (SD inter-observer/intra-observer PWV differences were -0.12(1.3/-0.04(0.4 for TT, 0.2(1.3/0.09(0.9 for XC, and 0.6(1.6/0.2(1.4 m/s for QA methods, respectively. The correlation coefficients (r for the inter-observer/intra-observer comparisons were 0.94/0.99, 0.88/0.94, and 0.83/0.92 for the TT, XC, and QA methods, respectively. The inter-scan reproducibility results showed low variability between the repeated

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

    CERN Document Server

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

    2010-01-01

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

  12. Pulsed EPR/ENDOR characterization of perturbations of the Cu(A) center ground state by axial methionine ligand mutations.

    Science.gov (United States)

    Slutter, C E; Gromov, I; Epel, B; Pecht, I; Richards, J H; Goldfarb, D

    2001-06-01

    The effect of axial ligand mutation on the Cu(A) site in the recombinant water soluble fragment of subunit II of Thermus thermophilus cytochrome c oxidase ba(3) has been investigated. The weak methionine ligand was replaced by glutamate and glutamine which are stronger ligands. Two constructs, M160T0 and M160T9, that differ in the length of the peptide were prepared. M160T0 is the original soluble fragment construct of cytochrome ba(3) that encodes 135 amino acids of subunit II, omitting the transmembrane helix that anchors the domain in the membrane. In M160T9 nine C-terminal amino acids are missing, including one histidine. The latter has been used to reduce the amount of a secondary T2 copper which is most probably coordinated to a surface histidine in M160T0. The changes in the spin density in the Cu(A) site, as manifested by the hyperfine couplings of the weakly and strongly coupled nitrogens, and of the cysteine beta-protons, were followed using a combination of advanced EPR techniques. X-band ( approximately 9 GHz) electron-spin-echo envelope modulation (ESEEM) and two-dimensional (2D) hyperfine sublevel correlation (HYSCORE) spectroscopy were employed to measure the weakly coupled (14)N nuclei, and X- and W-band (95 GHz) pulsed electron-nuclear double resonance (ENDOR) spectroscopy for probing the strongly coupled (14)N nuclei and the beta-protons. The high field measurements were extremely useful as they allowed us to resolve the T2 and Cu(A) signals in the g( perpendicular) region and gave (1)H ENDOR spectra free of overlapping (14)N signals. The effects of the M160Q and M160E mutations were: (i) increase in A( parallel)((63,65)Cu), (ii) larger hyperfine coupling of the weakly coupled backbone nitrogen of C153, (iii) reduction in the isotropic hyperfine interaction, a(iso), of some of the beta-protons making them more similar, (iv) the a(iso) value of one of the remote nitrogens of the histidine residues is decreased, thus distinguishing the two

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

    Science.gov (United States)

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

    2013-09-01

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

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

    CERN Document Server

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

    2011-01-01

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

  15. Pulsed EPR Spin-probe study of intracellular glasses in seed and pollen

    NARCIS (Netherlands)

    Buitink, J.; Dzuba, S.A.; Hoekstra, F.A.; Tsvetkov, Y.D.

    2000-01-01

    EPR spectra of 3-carboxy-proxyl (CP) in dry biological tissues exhibited a temperature-dependent change in the principal value A′zz of the hyperfine interaction tensor. The A′zz value changed sharply at a particular temperature that was dependent on water content. At elevated water contents, the bre

  16. In vivo preclinical cancer and tissue engineering applications of absolute oxygen imaging using pulse EPR

    Science.gov (United States)

    Epel, Boris; Kotecha, Mrignayani; Halpern, Howard J.

    2017-07-01

    The value of any measurement and a fortiori any measurement technology is defined by the reproducibility and the accuracy of the measurements. This implies a relative freedom of the measurement from factors confounding its accuracy. In the past, one of the reasons for the loss of focus on the importance of imaging oxygen in vivo was the difficulty in obtaining reproducible oxygen or pO2 images free from confounding variation. This review will briefly consider principles of electron paramagnetic oxygen imaging and describe how it achieves absolute oxygen measurements. We will provide a summary review of the progress in biomedical EPR imaging, predominantly in cancer biology research, discuss EPR oxygen imaging for cancer treatment and tissue graft assessment for regenerative medicine applications.

  17. Multishot versus single-shot pulse sequences in very high field fMRI: a comparison using retinotopic mapping.

    Directory of Open Access Journals (Sweden)

    Jascha D Swisher

    Full Text Available High-resolution functional MRI is a leading application for very high field (7 Tesla human MR imaging. Though higher field strengths promise improvements in signal-to-noise ratios (SNR and BOLD contrast relative to fMRI at 3 Tesla, these benefits may be partially offset by accompanying increases in geometric distortion and other off-resonance effects. Such effects may be especially pronounced with the single-shot EPI pulse sequences typically used for fMRI at standard field strengths. As an alternative, one might consider multishot pulse sequences, which may lead to somewhat lower temporal SNR than standard EPI, but which are also often substantially less susceptible to off-resonance effects. Here we consider retinotopic mapping of human visual cortex as a practical test case by which to compare examples of these sequence types for high-resolution fMRI at 7 Tesla. We performed polar angle retinotopic mapping at each of 3 isotropic resolutions (2.0, 1.7, and 1.1 mm using both accelerated single-shot 2D EPI and accelerated multishot 3D gradient-echo pulse sequences. We found that single-shot EPI indeed led to greater temporal SNR and contrast-to-noise ratios (CNR than the multishot sequences. However, additional distortion correction in postprocessing was required in order to fully realize these advantages, particularly at higher resolutions. The retinotopic maps produced by both sequence types were qualitatively comparable, and showed equivalent test/retest reliability. Thus, when surface-based analyses are planned, or in other circumstances where geometric distortion is of particular concern, multishot pulse sequences could provide a viable alternative to single-shot EPI.

  18. Can copper(II) mediate Hoogsteen base-pairing in a left-handed DNA duplex? A pulse EPR study.

    Science.gov (United States)

    Santangelo, Maria Grazia; Antoni, Philipp M; Spingler, Bernhard; Jeschke, Gunnar

    2010-02-22

    Pulse EPR spectroscopy is used to investigate possible structural features of the copper(II) ion coordinated to poly(dG-dC).poly(dG-dC) in a frozen aqueous solution, and the structural changes of the polynucleotide induced by the presence of the metal ion. Two different copper species were identified and their geometry explained by a molecular model. According to this model, one species is exclusively coordinated to a single guanine with the N7 nitrogen atom forming a coordinative bond with the copper. In the other species, a guanine and a cytosine form a ternary complex together with the copper ion. A copper crosslink between the N7 of guanine and N3 of cytosine is proposed as the most probable coordination site. Moreover, no evidence was found for an interaction of either copper species with a phosphate group or equatorial water molecules. In addition, circular dichroism (CD) spectroscopy showed that the DNA of the Cu(II)-poly(dG-dC).poly(dG-dC) adducts resembles the left-handed Z-form. These results suggest that metal-mediated Hoogsteen base pairing, as previously proposed for a right-handed DNA duplex, can also occur in a double-stranded left-handed DNA.

  19. Comparison of parabolic filtration methods for 3D filtered back projection in pulsed EPR imaging.

    Science.gov (United States)

    Qiao, Zhiwei; Redler, Gage; Epel, Boris; Halpern, Howard J

    2014-11-01

    Pulse electron paramagnetic resonance imaging (Pulse EPRI) is a robust method for noninvasively measuring local oxygen concentrations in vivo. For 3D tomographic EPRI, the most commonly used reconstruction algorithm is filtered back projection (FBP), in which the parabolic filtration process strongly influences image quality. In this work, we designed and compared 7 parabolic filtration methods to reconstruct both simulated and real phantoms. To evaluate these methods, we designed 3 error criteria and 1 spatial resolution criterion. It was determined that the 2 point derivative filtration method and the two-ramp-filter method have unavoidable negative effects resulting in diminished spatial resolution and increased artifacts respectively. For the noiseless phantom the rectangular-window parabolic filtration method and sinc-window parabolic filtration method were found to be optimal, providing high spatial resolution and small errors. In the presence of noise, the 3 point derivative method and Hamming-window parabolic filtration method resulted in the best compromise between low image noise and high spatial resolution. The 3 point derivative method is faster than Hamming-window parabolic filtration method, so we conclude that the 3 point derivative method is optimal for 3D FBP. Copyright © 2014. Published by Elsevier Inc.

  20. The EPR reactor; Le reacteur EPR

    Energy Technology Data Exchange (ETDEWEB)

    Lacoste, A.C.; Dupuy, Ph.; Gupta, O.; Perez, J.R.; Emond, D. [Direction Generale de la Surete Nucleaire et de la Radioprotection, 75 - Paris (France); Cererino, G.; Rousseau, J.M.; Jeffroy, F.; Evrard, J.M. [Institut de Radioprotection et de Surete Nucleaire (IRSN), Dir. de la Surete des Reacteurs, 92 - Clamart (France); Seiler, J.M. [CEA Cadarache (DEN/DTN), 13 - Saint-Paul-lez-Durance (France); Azarian, G. [FRAMATOME ANP, 92 - Paris-La-Defence (France); Chaumont, B. [Institut de Radioprotection et de Surete Nucleaire (IRSN/DSR), 92 - Fontenay-aux-Roses (France); Dubail, A. [Electricite de France (EDF), 78 - Chatou (France); Fischer, M. [Framatome ANP GmbH, Erlangen (Germany); Tiippana, P.; Hyvarinen, J. [Stuk, Autorite de Surete Nucleaire et de Radioprotection (Finland); Zaleski, C.P.; Meritet, S. [Paris-9 Univ. Dauphine, Centre de Geopolitique de l' Energie et des Matieres Premieres, 75 (France); Iglesias, F.; Vincent, C. [Direction Generale de l' Energie et des Matieres Premieres, 75 - Paris (France); Massart, S.; Graillat, G. [Electricite de France (EDF), 75 - Paris (France); Esteve, B. [AREVA/Framatome, 75 - Paris (France); Mansillon, Y. [Commission Nationale de Debat Public, 75 - Paris (France); Gatinol, C. [Assemblee Nationale, 75 - Paris (France); Carre, F. [CEA, Dir. de Programme Systemes du Futur, France (France)

    2005-05-01

    This document reviews economical and environmental aspects of the EPR project. The following topics are discussed: role and point of view of the French Nuclear Safety Authority on EPR, control of design and manufacturing of EPR by the French Nuclear Safety Authority, assessment by IRSN of EPR safety, research and development in support of EPR, STUK safety review of EPR design, standpoint on EPR, the place of EPR in the French energy policy, the place of EPR in EDF strategy, EPR spearhead of nuclear rebirth, the public debate, the local stakes concerning the building of EPR in France at Flamanville (Manche) and the research on fourth generation reactors. (A.L.B.)

  1. Physical characterization of the state of motion of the phenalenyl spin probe in cation-exchanged faujasite zeolite supercages with pulsed EPR

    Science.gov (United States)

    Doetschman, D. C.; Dwyer, D. W.; Fox, J. D.; Frederick, C. K.; Scull, S.; Thomas, G. D.; Utterback, S. G.; Wei, J.

    1994-08-01

    The molecular motion of the phenalenyl (PNL) spin probe in the supercages of cation-exchanged X and Y zeolites (faujasites) has been physically characterized by pulsed and continuous wave (CW) electron paramagnetic resonance (EPR). Both X and Y zeolites, whose cation sites were exchanged with the alkali metal ions, Li +, Na +, K +, Rb + and Cs + were examined. There is a good correspondence between the temperature dependences of the PNL electron spin phase memory time and the CW EPR spectra. Both display evidence of a thermal activation from a stationary, non-rotating molecular state to a low-temperature state of in-plane rotation (Das et al., Chem Phys. 143 (1990) 253). The rate of in-plane rotation is an activated process, with E* | / R=1289 |+- 35 K and 1462 ± 47 K in NaX and KX zeolites, respectively. The rotation appears to be about an axis along which the half-filled, non-bonding π orbital interacts with the exchanged cation in the supercage. Both CW and pulsed EPR also show a higher temperature activation from the in-plane rotating state to an effectively isoptropic state of rotation of PNL in which the PNL-cation bond is thought to be broken, with E* ⊥ / R=2050 ± 110 K, 1956 ± 46K, 1335 ± 97 K in LiX, NaX and KX zeolites, respectively. The strength of the PNL-cation bonding decreases with increasing cation atomic number as indicated by E* ⊥ and the peripheral repulsion (crowding) of PNL increases with cation size as indicated E* |. There are qualitative indications that the binding of PNL to the cations in the Y zeolite is stronger than in the X zeolite.

  2. A portable high-field pulsed-magnet system for single-crystal x-ray scattering studies.

    Science.gov (United States)

    Islam, Zahirul; Ruff, Jacob P C; Nojiri, Hiroyuki; Matsuda, Yasuhiro H; Ross, Kathryn A; Gaulin, Bruce D; Qu, Zhe; Lang, Jonathan C

    2009-11-01

    We present a portable pulsed-magnet system for x-ray studies of materials in high magnetic fields (up to 30 T). The apparatus consists of a split-pair of minicoils cooled on a closed-cycle cryostat, which is used for x-ray diffraction studies with applied field normal to the scattering plane. A second independent closed-cycle cryostat is used for cooling the sample to near liquid helium temperatures. Pulsed magnetic fields (approximately 1 ms in total duration) are generated by discharging a configurable capacitor bank into the magnet coils. Time-resolved scattering data are collected using a combination of a fast single-photon counting detector, a multichannel scaler, and a high-resolution digital storage oscilloscope. The capabilities of this instrument are used to study a geometrically frustrated system revealing strong magnetostrictive effects in the spin-liquid state.

  3. Terahertz cyclotron resonance spectroscopy of an AlGaN/GaN heterostructure using a high-field pulsed magnet and an asynchronous optical sampling technique

    Science.gov (United States)

    Spencer, B. F.; Smith, W. F.; Hibberd, M. T.; Dawson, P.; Beck, M.; Bartels, A.; Guiney, I.; Humphreys, C. J.; Graham, D. M.

    2016-05-01

    The effective mass, sheet carrier concentration, and mobility of electrons within a two-dimensional electron gas in an AlGaN/GaN heterostructure were determined using a laboratory-based terahertz cyclotron resonance spectrometer. The ability to perform terahertz cyclotron resonance spectroscopy with magnetic fields of up to 31 T was enabled by combining a high-field pulsed magnet with a modified asynchronous optical sampling terahertz detection scheme. This scheme allowed around 100 transmitted terahertz waveforms to be recorded over the 14 ms magnetic field pulse duration. The sheet density and mobility were measured to be 8.0 × 1012 cm-2 and 9000 cm2 V-1 s-1 at 77 K. The in-plane electron effective mass at the band edge was determined to be 0.228 ± 0.002m0.

  4. Spin signatures of photogenerated radical anions in polymer-[70]fullerene bulk-heterojunctions : high-frequency pulsed EPR spectroscopy.

    Energy Technology Data Exchange (ETDEWEB)

    Poluektov, O. G.; Filippone, S.; Martin, N.; Sperlich, A.; Deibel, C.; Dyakonov, V. (Chemical Sciences and Engineering Division); (Univ. Complutense de Madrid); (Univ. of Wurzburg)

    2010-04-14

    Charged polarons in thin films of polymer-fullerene composites are investigated by light-induced electron paramagnetic resonance (EPR) at 9.5 GHz (X-band) and 130 GHz (D-band). The materials studied were poly(3-hexylthiophene) (PHT), [6,6]-phenyl-C61-butyric acid methyl ester (C{sub 60}-PCBM), and two different soluble C{sub 70}-derivates: C{sub 70}-PCBM and diphenylmethano[70]fullerene oligoether (C{sub 70}-DPM-OE). The first experimental identification of the negative polaron localized on the C{sub 70}-cage in polymer-fullerene bulk heterojunctions has been obtained. When recorded at conventional X-band EPR, this signal is overlapping with the signal of the positive polaron, which does not allow for its direct experimental identification. Owing to the superior spectral resolution of the high frequency D-band EPR, we were able to separate light-induced signals from P{sup +} and P{sup -} in PHT-C{sub 70} bulk heterojunctions. Comparing signals from C{sub 70}-derivatives with different side-chains, we have obtained experimental proof that the polaron is localized on the cage of the C{sub 70} molecule.

  5. Spin Signatures of Photogenerated Radical Anions in Polymer-[70]Fullerene Bulk Heterojunctions: High Frequency Pulsed EPR Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Poluektov, Oleg G. [Argonne National Lab. (ANL), Argonne, IL (United States); Filippone, Salvatore [Universidad Complutense de Madrid (Spain); Martin, C. R. [Universidad Complutense de Madrid (Spain); Sperlich, Andreas [Julius-Maximilians Univ. of Wurzburg (Germany); Deibel, Carsten [Julius-Maximilians Univ. of Wurzburg (Germany); Dyakonov, Vladimir [Julius-Maximilians Univ. of Wurzburg (Germany)

    2010-11-18

    Charged polarons in thin films of polymer-fullerene composites are investigated by light-induced electron paramagnetic resonance (EPR) at 9.5 GHz (X-band) and 130 GHz (D-band). The materials studied were poly(3-hexylthiophene) (PHT), [6,6]-phenyl-C61-butyric acid methyl ester (C60-PCBM), and two different soluble C70-derivates: C70-PCBM and diphenylmethano[70]fullerene oligoether (C70-DPM-OE). The first experimental identification of the negative polaron localized on the C70-cage in polymer-fullerene bulk heterojunctions has been obtained. When recorded at conventional X-band EPR, this signal is overlapping with the signal of the positive polaron, which does not allow for its direct experimental identification. Owing to the superior spectral resolution of the high frequency D-band EPR, we were able to separate light-induced signals from P+ and P- in PHT-C70 bulk heterojunctions. Comparing signals from C70-derivatives with different side-chains, we have obtained experimental proof that the polaron is localized on the cage of the C70 molecule.

  6. Spin signatures of photogenerated radical anions in polymer-[70]fullerene bulk heterojunctions: high frequency pulsed EPR spectroscopy.

    Science.gov (United States)

    Poluektov, Oleg G; Filippone, Salvatore; Martín, Nazario; Sperlich, Andreas; Deibel, Carsten; Dyakonov, Vladimir

    2010-11-18

    Charged polarons in thin films of polymer-fullerene composites are investigated by light-induced electron paramagnetic resonance (EPR) at 9.5 GHz (X-band) and 130 GHz (D-band). The materials studied were poly(3-hexylthiophene) (PHT), [6,6]-phenyl-C61-butyric acid methyl ester (C(60)-PCBM), and two different soluble C(70)-derivates: C(70)-PCBM and diphenylmethano[70]fullerene oligoether (C(70)-DPM-OE). The first experimental identification of the negative polaron localized on the C(70)-cage in polymer-fullerene bulk heterojunctions has been obtained. When recorded at conventional X-band EPR, this signal is overlapping with the signal of the positive polaron, which does not allow for its direct experimental identification. Owing to the superior spectral resolution of the high frequency D-band EPR, we were able to separate light-induced signals from P(+) and P(-) in PHT-C(70) bulk heterojunctions. Comparing signals from C(70)-derivatives with different side-chains, we have obtained experimental proof that the polaron is localized on the cage of the C(70) molecule.

  7. Spin signatures of photogenerated radical anions in polymer-[70] fullerene bulk-heterojunctions : high-frequency pulsed EPR spectroscopy.

    Energy Technology Data Exchange (ETDEWEB)

    Poluektov, O. G.; Filippone, S.; Martin, N.; Sperlich, A.; Deibel, C.; Dyakonov, V. (Chemical Sciences and Engineering Division); (Univ. Complutense de Madrid); (Univ. of Wurzburg)

    2010-01-01

    Charged polarons in thin films of polymer-fullerene composites are investigated by light-induced electron paramagnetic resonance (EPR) at 9.5 GHz (X-band) and 130 GHz (D-band). The materials studied were poly(3-hexylthiophene) (PHT), [6,6]-phenyl-C61-butyric acid methyl ester (C{sub 60}-PCBM), and two different soluble C{sub 70}-derivates: C{sub 70}-PCBM and diphenylmethano[70]fullerene oligoether (C{sub 70}-DPM-OE). The first experimental identification of the negative polaron localized on the C{sub 70}-cage in polymer-fullerene bulk heterojunctions has been obtained. When recorded at conventional X-band EPR, this signal is overlapping with the signal of the positive polaron, which does not allow for its direct experimental identification. Owing to the superior spectral resolution of the high frequency D-band EPR, we were able to separate light-induced signals from P{sup +} and P{sup -} in PHT-C{sub 70} bulk heterojunctions. Comparing signals from C{sub 70}-derivatives with different side-chains, we have obtained experimental proof that the polaron is localized on the cage of the C{sub 70} molecule.

  8. A tunable general purpose Q-band resonator for CW and pulse EPR/ENDOR experiments with large sample access and optical excitation

    Science.gov (United States)

    Reijerse, Edward; Lendzian, Friedhelm; Isaacson, Roger; Lubitz, Wolfgang

    2012-01-01

    We describe a frequency tunable Q-band cavity (34 GHz) designed for CW and pulse Electron Paramagnetic Resonance (EPR) as well as Electron Nuclear Double Resonance (ENDOR) and Electron Electron Double Resonance (ELDOR) experiments. The TE 011 cylindrical resonator is machined either from brass or from graphite (which is subsequently gold plated), to improve the penetration of the 100 kHz field modulation signal. The (self-supporting) ENDOR coil consists of four 0.8 mm silver posts at 2.67 mm distance from the cavity center axis, penetrating through the plunger heads. It is very robust and immune to mechanical vibrations. The coil is electrically shielded to enable CW ENDOR experiments with high RF power (500 W). The top plunger of the cavity is movable and allows a frequency tuning of ±2 GHz. In our setup the standard operation frequency is 34.0 GHz. The microwaves are coupled into the resonator through an iris in the cylinder wall and matching is accomplished by a sliding short in the coupling waveguide. Optical excitation of the sample is enabled through slits in the cavity wall (transmission ˜60%). The resonator accepts 3 mm o.d. sample tubes. This leads to a favorable sensitivity especially for pulse EPR experiments of low concentration biological samples. The probehead dimensions are compatible with that of Bruker flexline Q-band resonators and it fits perfectly into an Oxford CF935 Helium flow cryostat (4-300 K). It is demonstrated that, due to the relatively large active sample volume (20-30 μl), the described resonator has superior concentration sensitivity as compared to commercial pulse Q-band resonators. The quality factor ( Q L) of the resonator can be varied between 2600 (critical coupling) and 1300 (over-coupling). The shortest achieved π/2-pulse durations are 20 ns using a 3 W microwave amplifier. ENDOR (RF) π-pulses of 20 μs ( 1H @ 51 MHz) were obtained for a 300 W amplifier and 7 μs using a 2500 W amplifier. Selected applications of the

  9. Regional in vivo transit time measurements of aortic pulse wave velocity in mice with high-field CMR at 17.6 Tesla

    Directory of Open Access Journals (Sweden)

    Rommel Eberhard

    2010-12-01

    Full Text Available Abstract Background Transgenic mouse models are increasingly used to study the pathophysiology of human cardiovascular diseases. The aortic pulse wave velocity (PWV is an indirect measure for vascular stiffness and a marker for cardiovascular risk. Results This study presents a cardiovascular magnetic resonance (CMR transit time (TT method that allows the determination of the PWV in the descending murine aorta by analyzing blood flow waveforms. Systolic flow pulses were recorded with a temporal resolution of 1 ms applying phase velocity encoding. In a first step, the CMR method was validated by pressure waveform measurements on a pulsatile elastic vessel phantom. In a second step, the CMR method was applied to measure PWVs in a group of five eight-month-old apolipoprotein E deficient (ApoE(-/- mice and an age matched group of four C57Bl/6J mice. The ApoE(-/- group had a higher mean PWV (PWV = 3.0 ± 0.6 m/s than the C57Bl/6J group (PWV = 2.4 ± 0.4 m/s. The difference was statistically significant (p = 0.014. Conclusions The findings of this study demonstrate that high field CMR is applicable to non-invasively determine and distinguish PWVs in the arterial system of healthy and diseased groups of mice.

  10. Arsenic speciation in synthetic gypsum (CaSO4·2H2O): A synchrotron XAS, single-crystal EPR, and pulsed ENDOR study

    Science.gov (United States)

    Lin, Jinru; Chen, Ning; Nilges, Mark J.; Pan, Yuanming

    2013-04-01

    Gypsum (CaSO4·2H2O) is a major by-product of mining and milling processes of borate, phosphate and uranium deposits worldwide and, therefore, potentially plays an important role in the stability and bioavailability of heavy metalloids, including As, in tailings and surrounding areas. Gypsum containing 1900 and 185 ppm As, synthesized with Na2HAsO4·7H2O and NaAsO2 in the starting materials, respectively, have been investigated by synchrotron X-ray absorption spectroscopy (XAS), single-crystal electron paramagnetic resonance spectroscopy (EPR), and pulsed electron nuclear double resonance spectroscopy (ENDOR). Quantitative analyses of As K edge XANES and EXAFS spectra show that arsenic occurs in both +3 and +5 oxidation states and the As3+/As5+ value varies from 0.35 to 0.79. Single-crystal EPR spectra of gamma-ray-irradiated gypsum reveal two types of arsenic-associated oxyradicals: [AsO3]2- and an [AsO2]2-. The [AsO3]2- center is characterized by principal 75As hyperfine coupling constants of A1 = 1952.0(2) MHz, A2 = 1492.6(2) MHz and A3 = 1488.7(2) MHz, with the unique A axis along the S-O1 bond direction, and contains complex 1H superhyperfine structures that have been determined by pulsed ENDOR. These results suggest that the [AsO3]2- center formed from electron trapping on the central As5+ ion of a substitutional (AsO4)3- group after removal of an O1 atom. The [AsO2]2- center is characterized by its unique A(75As) axis approximately perpendicular to the O1-S-O2 plane and the A2 axis along the S-O2 bond direction, consistent with electron trapping on the central As3+ ion of a substitutional (AsO3)3- group after removal of an O2 atom. These results confirm lattice-bound As5+ and As3+ in gypsum and point to potential application of this mineral for immobilization and removal of arsenic pollution.

  11. Pulse EPR, 55Mn-ENDOR and ELDOR-detected NMR of the S2-state of the oxygen evolving complex in photosystem II.

    Science.gov (United States)

    Kulik, Leonid; Epel, Boris; Messinger, Johannes; Lubitz, Wolfgang

    2005-06-01

    Pulse EPR, 55Mn-ENDOR and ELDOR-detected NMR experiments were performed on the S2-state of the oxygen-evolving complex from spinach Photosystem II. The novel technique of random acquisition in ENDOR was used to suppress heating artefacts. Our data unambiguously shows that four Mn ions have significant hyperfine coupling constants. Numerical simulation of the 55Mn-ENDOR spectrum allowed the determination of the principal values of the hyperfine interaction tensors for all four Mn ions of the oxygen-evolving complex. The results of our 55Mn-ENDOR experiments are in good agreement with previously published data [Peloquin JM et al. (2000) J Am Chem Soc 122: 10926-10942]. For the first time ELDOR-detected NMR was applied to the S2-state and revealed a broad peak that can be simulated numerically with the same parameters that were used for the simulation of the 55Mn-ENDOR spectrum. This provides strong independent support for the assigned hyperfine parameters.

  12. Pulsed EPR and NMR spectroscopy of paramagnetic iron porphyrinates and related iron macrocycles: how to understand patterns of spin delocalization and recognize macrocycle radicals.

    Science.gov (United States)

    Walker, F Ann

    2003-07-28

    Pulsed EPR spectroscopic techniques, including ESEEM (electron spin echo envelope modulation) and pulsed ENDOR (electron-nuclear double resonance), are extremely useful for determining the magnitudes of the hyperfine couplings of macrocycle and axial ligand nuclei to the unpaired electron(s) on the metal as a function of magnetic field orientation relative to the complex. These data can frequently be used to determine the orientation of the g-tensor and the distribution of spin density over the macrocycle, and to determine the metal orbital(s) containing unpaired electrons and the macrocycle orbital(s) involved in spin delocalization. However, these studies cannot be carried out on metal complexes that do not have resolved EPR signals, as in the case of paramagnetic even-electron metal complexes. In addition, the signs of the hyperfine couplings, which are not determined directly in either ESEEM or pulsed ENDOR experiments, are often needed in order to translate hyperfine couplings into spin densities. In these cases, NMR isotropic (hyperfine) shifts are extremely useful in determining the amount and sign of the spin density at each nucleus probed. For metal complexes of aromatic macrocycles such as porphyrins, chlorins, or corroles, simple rules allow prediction of whether spin delocalization occurs through sigma or pi bonds, and whether spin density on the ligands is of the same or opposite sign as that on the metal. In cases where the amount of spin density on the macrocycle and axial ligands is found to be too large for simple metal-ligand spin delocalization, a macrocycle radical may be suspected. Large spin density on the macrocycle that is of the same sign as that on the metal provides clear evidence of either no coupling or weak ferromagnetic coupling of a macrocycle radical to the unpaired electron(s) on the metal, while large spin density on the macrocycle that is of opposite sign to that on the metal provides clear evidence of antiferromagnetic coupling

  13. FID detection of EPR and ENDOR spectra at high microwave frequencies.

    Science.gov (United States)

    Blok, H; Akimoto, I; Milikisyants, S; Gast, P; Groenen, E J J; Schmidt, J

    2009-11-01

    High-frequency pulsed EPR spectroscopy allows FID detection of EPR spectra owing to the short dead time that can be achieved. This FID detection is particularly attractive for EPR and ENDOR spectroscopy of paramagnetic species that exhibit inhomogeneously broadened EPR lines and short dephasing times. Experiments are reported for the metalloprotein azurin at 275 GHz.

  14. FID detection of EPR and ENDOR spectra at high microwave frequencies

    Science.gov (United States)

    Blok, H.; Akimoto, I.; Milikisyants, S.; Gast, P.; Groenen, E. J. J.; Schmidt, J.

    2009-11-01

    High-frequency pulsed EPR spectroscopy allows FID detection of EPR spectra owing to the short dead time that can be achieved. This FID detection is particularly attractive for EPR and ENDOR spectroscopy of paramagnetic species that exhibit inhomogeneously broadened EPR lines and short dephasing times. Experiments are reported for the metalloprotein azurin at 275 GHz.

  15. Using rapid-scan EPR to improve the detection limit of quantitative EPR by more than one order of magnitude.

    Science.gov (United States)

    Möser, J; Lips, K; Tseytlin, M; Eaton, G R; Eaton, S S; Schnegg, A

    2017-08-01

    X-band rapid-scan EPR was implemented on a commercially available Bruker ELEXSYS E580 spectrometer. Room temperature rapid-scan and continuous-wave EPR spectra were recorded for amorphous silicon powder samples. By comparing the resulting signal intensities the feasibility of performing quantitative rapid-scan EPR is demonstrated. For different hydrogenated amorphous silicon samples, rapid-scan EPR results in signal-to-noise improvements by factors between 10 and 50. Rapid-scan EPR is thus capable of improving the detection limit of quantitative EPR by at least one order of magnitude. In addition, we provide a recipe for setting up and calibrating a conventional pulsed and continuous-wave EPR spectrometer for rapid-scan EPR. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Metallomic EPR spectroscopy.

    Science.gov (United States)

    Hagen, Wilfred R

    2009-09-01

    Based on explicit definitions of biomolecular EPR spectroscopy and of the metallome, this tutorial review positions EPR in the field of metallomics as a unique method to study native, integrated systems of metallobiomolecular coordination complexes subject to external stimuli. The specific techniques of whole-system bioEPR spectroscopy are described and their historic, recent, and anticipated applications are discussed.

  17. Broadband Transmission EPR Spectroscopy

    NARCIS (Netherlands)

    Hagen, W.R.

    2013-01-01

    EPR spectroscopy employs a resonator operating at a single microwave frequency and phase-sensitive detection using modulation of the magnetic field. The X-band spectrometer is the general standard with a frequency in the 9–10 GHz range. Most (bio)molecular EPR spectra are determined by a combination

  18. EPR-based distance measurements at ambient temperature

    Science.gov (United States)

    Krumkacheva, Olesya; Bagryanskaya, Elena

    2017-07-01

    Pulsed dipolar (PD) EPR spectroscopy is a powerful technique allowing for distance measurements between spin labels in the range of 2.5-10.0 nm. It was proposed more than 30 years ago, and nowadays is widely used in biophysics and materials science. Until recently, PD EPR experiments were limited to cryogenic temperatures (T relaxation enhancement; RE). In this paper, we review the features of PD EPR and RE at ambient temperatures, in particular, requirements on electron spin phase memory time, ways of immobilization of biomolecules, the influence of a linker between the spin probe and biomolecule, and future opportunities.

  19. Electron Paramagnetic Resonance Imaging: 1. CW-EPR Imaging

    Indian Academy of Sciences (India)

    2016-07-01

    Twentieth century bore witness to remarkable scientists whohave advanced our understanding of the brain. Among them,EPR (Electron Paramagnetic Resonance) imaging is particularlyuseful in monitoring hypoxic zones in tumors which arehighly resistant to radiation and chemotherapeutic treatment.This first part of the article covers aspects of CW(continuous wave) imaging with details of FT (pulsed FourierTransform)-EPR imaging covered in Part 2, to be publishedin the next issue of Resonance.

  20. Biomolecular EPR spectroscopy

    CERN Document Server

    Hagen, Wilfred Raymond

    2008-01-01

    Comprehensive, Up-to-Date Coverage of Spectroscopy Theory and its Applications to Biological SystemsAlthough a multitude of books have been published about spectroscopy, most of them only occasionally refer to biological systems and the specific problems of biomolecular EPR (bioEPR). Biomolecular EPR Spectroscopy provides a practical introduction to bioEPR and demonstrates how this remarkable tool allows researchers to delve into the structural, functional, and analytical analysis of paramagnetic molecules found in the biochemistry of all species on the planet. A Must-Have Reference in an Intrinsically Multidisciplinary FieldThis authoritative reference seamlessly covers all important bioEPR applications, including low-spin and high-spin metalloproteins, spin traps and spin lables, interaction between active sites, and redox systems. It is loaded with practical tricks as well as do's and don'ts that are based on the author's 30 years of experience in the field. The book also comes with an unprecedented set of...

  1. Electron spin dynamics of Ce3 + ions in YAG crystals studied by pulse-EPR and pump-probe Faraday rotation

    Science.gov (United States)

    Azamat, D. V.; Belykh, V. V.; Yakovlev, D. R.; Fobbe, F.; Feng, D. H.; Evers, E.; Jastrabik, L.; Dejneka, A.; Bayer, M.

    2017-08-01

    The spin relaxation dynamics of Ce3 + ions in heavily cerium-doped YAG crystals is studied using pulse-electron paramagnetic resonance and time-resolved pump-probe Faraday rotation. Both techniques address the 4 f ground state, while pump-probe Faraday rotation also provides access to the excited 5 d state. We measure a millisecond spin-lattice relaxation time T1, a microsecond spin coherence time T2, and a ˜10 ns inhomogeneous spin dephasing time T2* for the Ce3 + ground state at low temperatures. The spin-lattice relaxation of Ce3 + ions is due to modified Raman processes involving the optical phonon mode at ˜125 cm-1 . The relaxation at higher temperature goes through a first excited level of the 5/2 2F term at about ℏ ω ≈228 cm-1 . Effects provided by the hyperfine interaction of the Ce3 + with the 27Al nuclei are observed.

  2. Hydration structure of the Ti(III) cation as revealed by pulse EPR and DFT studies: new insights into a textbook case.

    Science.gov (United States)

    Maurelli, Sara; Livraghi, Stefano; Chiesa, Mario; Giamello, Elio; Van Doorslaer, Sabine; Di Valentin, Cristiana; Pacchioni, Gianfranco

    2011-03-21

    The (17)O and (1)H hyperfine interactions of water ligands in the Ti(III) aquo complex in a frozen solution were determined using Hyperfine Sublevel Correlation (HYSCORE) and Pulse Electron Nuclear Double Resonance (ENDOR) spectroscopies at 9.5 GHz. The isotropic hyperfine interaction (hfi) constant of the water ligand (17)O was found to be about 7.5 MHz. (1)H Single Matched Resonance Transfer (SMART) HYSCORE spectra allowed resolution of the hfi interactions of the two inequivalent water ligand protons and the relative orientations of their hfi tensors. The magnetic and geometrical parameters extracted from the experiments were compared with the results of DFT computations for different geometrical arrangements of the water ligands around the cation. The theoretical observable properties (g tensor (1)H and (17)O hfi tensors and their orientations) of the [Ti(H(2)O)(6)](3+) complex are in quantitative agreement with the experiments for two slightly different geometrical arrangements associated with D(3d) and C(i) symmetries.

  3. Broadband transmission EPR spectroscopy.

    Directory of Open Access Journals (Sweden)

    Wilfred R Hagen

    Full Text Available EPR spectroscopy employs a resonator operating at a single microwave frequency and phase-sensitive detection using modulation of the magnetic field. The X-band spectrometer is the general standard with a frequency in the 9-10 GHz range. Most (biomolecular EPR spectra are determined by a combination of the frequency-dependent electronic Zeeman interaction and a number of frequency-independent interactions, notably, electron spin - nuclear spin interactions and electron spin - electron spin interactions, and unambiguous analysis requires data collection at different frequencies. Extant and long-standing practice is to use a different spectrometer for each frequency. We explore the alternative of replacing the narrow-band source plus single-mode resonator with a continuously tunable microwave source plus a non-resonant coaxial transmission cell in an unmodulated external field. Our source is an arbitrary wave digital signal generator producing an amplitude-modulated sinusoidal microwave in combination with a broadband amplifier for 0.8-2.7 GHz. Theory is developed for coaxial transmission with EPR detection as a function of cell dimensions and materials. We explore examples of a doublet system, a high-spin system, and an integer-spin system. Long, straigth, helical, and helico-toroidal cells are developed and tested with dilute aqueous solutions of spin label hydroxy-tempo. A detection limit of circa 5 µM HO-tempo in water at 800 MHz is obtained for the present setup, and possibilities for future improvement are discussed.

  4. Pulse

    Science.gov (United States)

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

  5. Quantitative EPR A Practitioners Guide

    CERN Document Server

    Eaton, Gareth R; Barr, David P; Weber, Ralph T

    2010-01-01

    This is the first comprehensive yet practical guide for people who perform quantitative EPR measurements. No existing book provides this level of practical guidance to ensure the successful use of EPR. There is a growing need in both industrial and academic research to provide meaningful and accurate quantitative EPR results. This text discusses the various sample, instrument and software related aspects required for EPR quantitation. Specific topics include: choosing a reference standard, resonator considerations (Q, B1, Bm), power saturation characteristics, sample positioning, and finally, putting all the factors together to obtain an accurate spin concentration of a sample.

  6. Full cycle rapid scan EPR deconvolution algorithm

    Science.gov (United States)

    Tseytlin, Mark

    2017-08-01

    Rapid scan electron paramagnetic resonance (RS EPR) is a continuous-wave (CW) method that combines narrowband excitation and broadband detection. Sinusoidal magnetic field scans that span the entire EPR spectrum cause electron spin excitations twice during the scan period. Periodic transient RS signals are digitized and time-averaged. Deconvolution of absorption spectrum from the measured full-cycle signal is an ill-posed problem that does not have a stable solution because the magnetic field passes the same EPR line twice per sinusoidal scan during up- and down-field passages. As a result, RS signals consist of two contributions that need to be separated and postprocessed individually. Deconvolution of either of the contributions is a well-posed problem that has a stable solution. The current version of the RS EPR algorithm solves the separation problem by cutting the full-scan signal into two half-period pieces. This imposes a constraint on the experiment; the EPR signal must completely decay by the end of each half-scan in order to not be truncated. The constraint limits the maximum scan frequency and, therefore, the RS signal-to-noise gain. Faster scans permit the use of higher excitation powers without saturating the spin system, translating into a higher EPR sensitivity. A stable, full-scan algorithm is described in this paper that does not require truncation of the periodic response. This algorithm utilizes the additive property of linear systems: the response to a sum of two inputs is equal the sum of responses to each of the inputs separately. Based on this property, the mathematical model for CW RS EPR can be replaced by that of a sum of two independent full-cycle pulsed field-modulated experiments. In each of these experiments, the excitation power equals to zero during either up- or down-field scan. The full-cycle algorithm permits approaching the upper theoretical scan frequency limit; the transient spin system response must decay within the scan

  7. Localization of dexamethasone within dendritic core-multishell (CMS) nanoparticles and skin penetration properties studied by multi-frequency electron paramagnetic resonance (EPR) spectroscopy.

    Science.gov (United States)

    Saeidpour, S; Lohan, S B; Anske, M; Unbehauen, M; Fleige, E; Haag, R; Meinke, M C; Bittl, R; Teutloff, C

    2016-10-15

    The skin and especially the stratum corneum (SC) act as a barrier and protect epidermal cells and thus the whole body against xenobiotica of the external environment. Topical skin treatment requires an efficient drug delivery system (DDS). Polymer-based nanocarriers represent novel transport vehicles for dermal application of drugs. In this study dendritic core-multishell (CMS) nanoparticles were investigated as promising candidates. CMS nanoparticles were loaded with a drug (analogue) and were applied to penetration studies of skin. We determined by dual-frequency electron paramagnetic resonance (EPR) how dexamethasone (Dx) labelled with 3-carboxy-2,2,5,5-tetramethyl-1-pyrrolidinyloxy (PCA) is associated with the CMS. The micro-environment of the drug loaded to CMS nanoparticles was investigated by pulsed high-field EPR at cryogenic temperature, making use of the fact that magnetic parameters (g-, A-matrices, and spin-lattice relaxation time) represent specific probes for the micro-environment. Additionally, the rotational correlation time of spin-labelled Dx was probed by continuous wave EPR at ambient temperature, which provides independent information on the drug environment. Furthermore, the penetration depth of Dx into the stratum corneum of porcine skin after different topical applications was investigated. The location of Dx in the CMS nanoparticles is revealed and the function of CMS as penetration enhancers for topical application is shown.

  8. Multifrequency pulsed electron paramagnetic resonance on metalloproteins.

    Science.gov (United States)

    Lyubenova, Sevdalina; Maly, Thorsten; Zwicker, Klaus; Brandt, Ulrich; Ludwig, Bernd; Prisner, Thomas

    2010-02-16

    method, allowing us to obtain hyperfine (and dipolar) information from the individual species. Furthermore, performing pulsed EPR experiments at different magnetic fields is another important tool to disentangle the spectral components in such complex systems. Despite the fact that high magnetic fields do not usually lead to better spectral separation for metal centers, they provide additional information about the relative orientation of different paramagnetic centers. Our high-field EPR studies on cytochrome c oxidase reveal essential information regarding the structural arrangement of the binuclear Cu(A) center with respect to both the manganese ion within the enzyme and the cytochrome in the protein-protein complex with cytochrome c.

  9. EPR: the nuclear impasse; EPR: l'impasse nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Marillier, F. [Association Ecologiste Greenpeace (France)

    2008-07-01

    The questions relative to the climatic change constitute crucial challenges for the next ten years. In this context the author aims to show how the EPR project illustrates the nuclear french ''autism''. He presents and analyzes the international and environmental impacts of this obsolete technology, as a project useless and dangerous. (A.L.B.)

  10. EPR/PTFE dosimetry for test reactor environments

    Energy Technology Data Exchange (ETDEWEB)

    Vehar, D.W.; Griffin, P.J.; Quirk, T.J. [Sandia National Laboratories, Albuquerque, NM 87185-1146 (United States)

    2011-07-01

    The use of Electron Paramagnetic Resonance (EPR) spectroscopy with materials such as alanine is well established as a technique for measurement of ionizing radiation absorbed dose in photon and electron fields such as Co-60, high-energy bremsstrahlung and electron-beam fields [1]. In fact, EPR/Alanine dosimetry has become a routine transfer standard for national standards bodies such as NIST and NPL. In 1992 the Radiation Metrology Laboratory (RML) at Sandia National Laboratories implemented EPR/Alanine capabilities for use in routine and calibration activities at its Co-60 and pulsed-power facilities. At that time it also investigated the usefulness of the system for measurement of absorbed dose in the mixed neutron/photon environments of reactors such as the Sandia Pulsed Reactor and the Annular Core Research Reactor used for hardness testing of electronics. The RML concluded that the neutron response of alanine was a sufficiently high fraction of the overall dosimeter response that the resulting uncertainties in the photon dose would be unacceptably large for silicon-device testing. However, it also suggested that non-hydrogenous materials such as polytetrafluoroethylene (PTFE) would exhibit smaller neutron response and might be useful in mixed environments. Preliminary research with PTFE in photon environments indicated considerable promise, but further development was not pursued at that time. Because of renewed interest in absorbed dose measurements that could better define the individual contributions of photon and neutron components to the overall dose delivered to a test object, the RML has re-initiated the development of an EPR/PTFE dosimetry system. This effort consists of three stages: 1) Identification of PTFE materials that may be suitable for dosimetry applications. It was speculated that the inconsistency of EPR signatures in the earlier samples may have been due to variability in PTFE manufacturing processes. 2) Characterization of dosimetry in

  11. Nuclear spin-lattice relaxation in nitroxide spin-label EPR

    DEFF Research Database (Denmark)

    Marsh, Derek

    2016-01-01

    Nuclear relaxation is a sensitive monitor of rotational dynamics in spin-label EPR. It also contributes competing saturation transfer pathways in T1-exchange spectroscopy, and the determination of paramagnetic relaxation enhancement in site-directed spin labelling. A survey shows that the definit......Nuclear relaxation is a sensitive monitor of rotational dynamics in spin-label EPR. It also contributes competing saturation transfer pathways in T1-exchange spectroscopy, and the determination of paramagnetic relaxation enhancement in site-directed spin labelling. A survey shows...... that the definition of nitrogen nuclear relaxation rate Wn commonly used in the CW-EPR literature for 14N-nitroxyl spin labels is inconsistent with that currently adopted in time-resolved EPR measurements of saturation recovery. Redefinition of the normalised 14N spin-lattice relaxation rate, b = Wn/(2We), preserves...... the expressions used for CW-EPR, whilst rendering them consistent with expressions for saturation recovery rates in pulsed EPR. Furthermore, values routinely quoted for nuclear relaxation times that are deduced from EPR spectral diffusion rates in 14N-nitroxyl spin labels do not accord with conventional analysis...

  12. Nuclear spin-lattice relaxation in nitroxide spin-label EPR

    Science.gov (United States)

    Marsh, Derek

    2016-11-01

    Nuclear relaxation is a sensitive monitor of rotational dynamics in spin-label EPR. It also contributes competing saturation transfer pathways in T1-exchange spectroscopy, and the determination of paramagnetic relaxation enhancement in site-directed spin labelling. A survey shows that the definition of nitrogen nuclear relaxation rate Wn commonly used in the CW-EPR literature for 14N-nitroxyl spin labels is inconsistent with that currently adopted in time-resolved EPR measurements of saturation recovery. Redefinition of the normalised 14N spin-lattice relaxation rate, b = Wn/(2We), preserves the expressions used for CW-EPR, whilst rendering them consistent with expressions for saturation recovery rates in pulsed EPR. Furthermore, values routinely quoted for nuclear relaxation times that are deduced from EPR spectral diffusion rates in 14N-nitroxyl spin labels do not accord with conventional analysis of spin-lattice relaxation in this three-level system. Expressions for CW-saturation EPR with the revised definitions are summarised. Data on nitrogen nuclear spin-lattice relaxation times are compiled according to the three-level scheme for 14N-relaxation: T1n = 1/Wn. Results are compared and contrasted with those for the two-level 15N-nitroxide system.

  13. The strength of EPR and ENDOR techniques in revealing structure-function relationships in metalloproteins.

    Science.gov (United States)

    Van Doorslaer, Sabine; Vinck, Evi

    2007-09-01

    Recent technological and methodological advances have strongly increased the potential of electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) techniques to characterize the structure and dynamics of metalloproteins. These developments include the introduction of powerful pulsed EPR/ENDOR methodologies and the development of spectrometers operating at very high microwave frequencies and high magnetic fields. This overview focuses on how valuable information about metalloprotein structure-function relations can be obtained using a combination of EPR and ENDOR techniques. After an overview of the historical development and a limited theoretical description of some of the key EPR and ENDOR techniques, their potential will be highlighted using selected examples of applications to iron-, nickel-, cobalt-, and copper-containing proteins. We will end with an outlook of future developments.

  14. The Flamanville 3 EPR reactor; Le reacteur EPR Flamanville 3

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-07-01

    On April 10. 2007, the french government authorized EDF to create on the site of Flamanville ( La Manche) a nuclear base installation containing a pressurized water EPR type reactor. This nuclear reactor, conceived by AREVA NP and EDF, is the first copy of a generation susceptible to replace later, at least partly, the French nuclear reactors at present in operation.Within the framework of its mission of technical support of the Authority of Nuclear Safety ( A.S.N.), the I.R.S.N. widely contributed successively: to define the general objectives of safety assigned to this new generation of pressurized water nuclear reactors; to analyze the options of safety proposed by EDF for the EPR project; To deepen, upstream to the authorization of creation, the evaluation of the step of safety and the measures of conception retained by EDF that have to allow to respect the objectives of safety which were notified to it. (N.C.)

  15. A cryogenic receiver for EPR.

    Science.gov (United States)

    Narkowicz, R; Ogata, H; Reijerse, E; Suter, D

    2013-12-01

    Cryogenic probes have significantly increased the sensitivity of NMR. Here, we present a compact EPR receiver design capable of cryogenic operation. Compared to room temperature operation, it reduces the noise by a factor of ≈2.5. We discuss in detail the design and analyze the resulting noise performance. At low microwave power, the input noise density closely follows the emission of a cooled 50Ω resistor over the whole measurement range from 20K up to room temperature. To minimize the influence of the microwave source noise, we use high microwave efficiency (≈1.1-1.7mTW(-1/2)) planar microresonators. Their efficient conversion of microwave power to magnetic field permits EPR measurements with very low power levels, typically ranging from a few μW down to fractions of nW. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Hydrogen Analyses in the EPR

    Energy Technology Data Exchange (ETDEWEB)

    Worapittayaporn, S.; Eyink, J.; Movahed, M. [AREVA NP GmbH, P.O. Box 3220, D-91050 Erlangen (Germany)

    2008-07-01

    In severe accidents with core melting large amounts of hydrogen may be released into the containment. The EPR provides a combustible gas control system to prevent hydrogen combustion modes with the potential to challenge the containment integrity due to excessive pressure and temperature loads. This paper outlines the approach for the verification of the effectiveness and efficiency of this system. Specifically, the justification is a multi-step approach. It involves the deployment of integral codes, lumped parameter containment codes and CFD codes and the use of the sigma criterion, which provides the link to the broad experimental data base for flame acceleration (FA) and deflagration to detonation transition (DDT). The procedure is illustrated with an example. The performed analyses show that hydrogen combustion at any time does not lead to pressure or temperature loads that threaten the containment integrity of the EPR. (authors)

  17. Non-uniform sampling in EPR--optimizing data acquisition for HYSCORE spectroscopy.

    Science.gov (United States)

    Nakka, K K; Tesiram, Y A; Brereton, I M; Mobli, M; Harmer, J R

    2014-08-21

    Non-uniform sampling combined with maximum entropy reconstruction is a powerful technique used in multi-dimensional NMR spectroscopy to reduce sample measurement time. We adapted this technique to the pulse EPR experiment hyperfine sublevel correlation (HYSCORE) and show that experimental times can be shortened by approximately an order of magnitude as compared to conventional linear sampling with negligible loss of information.

  18. 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

  19. EPR techniques for space biodosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Haskell, E.; Hayes, R.; Kenner, G.; Sholom, S.; Chumak, V.

    1996-12-31

    Retrospective dosimetry of tooth enamel has become an increasingly complex and difficult discipline to undertake while still attaining accuracy. The paper provides a review of the major obstacles, advances and pertinent phenomenon associated with low level retrospective dosimetry of human tooth enamel. Also covered is the many sources of error in EPR dosimetry, their potential solutions, as well as the different analysis and scanning techniques in use with their prospective pros and cons. Prospective directions for new approaches, methods, and instruments are also reviewed.

  20. A special JMR issue: Methodological advances in EPR spectroscopy and imaging

    Science.gov (United States)

    2017-07-01

    Since about five decades, EPR spectroscopy provides important insights into the electronic structure of metalloproteins and transition-metal based catalysts. Somewhat later this spectroscopy was also applied to the study of electron transfer processes, often in radical enzymes. The study of diamagnetic proteins and nucleic acids with site-directed spin labeling (SDSL) techniques became really popular in the 1990s and early in the new millennium. The same applies to applications of pulsed EPR techniques to metalloproteins, although the pioneering work in this field by Mims and Peisach dates back to the early 1970s. Pulsed dipolar spectroscopy for the measurement of distance distributions in the nanometer range has become the major EPR-based tool in structural biology during the past 15 years and is still expanding its scope. EPR (or ESR) imaging may appear to be overshadowed by (nuclear) MRI, as it has not yet found clinical application. However, development of EPR-based imaging modalities has recently gained much momentum as they can provide information that is inaccessible by any established imaging technology.

  1. Overview of LBB implementation for the EPR

    Energy Technology Data Exchange (ETDEWEB)

    Cauquelin, C.

    1997-04-01

    This paper presents an overview of the use of leak-before-break (LBB) analysis for EPR reactors. EPR is an evolutionary Nuclear Island of the 4 loop x 1500 Mwe class currently in the design phase. Application of LBB to the main coolant lines and resulting design impacts are summarized. Background information on LBB analysis in France and Germany is also presented.

  2. EPR Dosimetry - Present and Future

    Energy Technology Data Exchange (ETDEWEB)

    Regulla, D.F. [GSF - National Research Centre for Environment and Health, Institute of Radiation Protection, 85764 Neuherberg (Germany)

    1999-07-01

    In the past, IAEA has played a central role in stipulating research and development in EPR high-dose standardisation as well as in coordinating and organising international dose intercomparison programs, within the Member States of the United Nations from the mid-seventies till today. The future tasks of EPR dosimetry seem to tend towards different subjects such as bio markers, biological radiation effects, post-accident dose reconstruction in the environment, and retrospective human dosimetry. The latter may be considered a promising tool for epidemiology on the way to re-define radiation risk of man for chronicle radiation exposures, based on e.g. South Ural civil population and radiation workers. There are on-going international activities in the field of standardising high-level dosimetry by the American Standards on Testing and Materials (Astm), and by the International Organisation of Standards (ISO). The International Commission on Radiation Units and Measurements (ICRU) is considering the establishment of relevant recommendations concerning industrial radiation processing, but also human dose reconstruction. (Author)

  3. Pulsed ELDOR detected NMR

    Science.gov (United States)

    Schosseler, P.; Wacker, Th.; Schweiger, A.

    1994-07-01

    A pulsed EPR method for the determination of small hyperfine interactions in disordered systems is described. A selective preparation pulse of frequency ω mw(1) excites allowed and forbidden transitions, thereby burning spectral holes into the EPR line. The positions of the holes caused by the excitation of forbidden transitions correspond to the nuclear transition frequencies of the spin system. A selective detection pulse of frequency ω mw(2) creates an FID with integrated intensity proportional to the magnetization at frequency ω mw(2). The entire hole pattern is obtained by recording the integrated intensity of the FID while varying the frequency difference Δω mw=ω mw(1)-ω mw(2) step by step.

  4. Nitrosyl hemoglobins: EPR above 80 K

    Energy Technology Data Exchange (ETDEWEB)

    Wajnberg, E.; Bemski, G.; El-Jaick, L.J.; Alves, O.C.

    1995-03-01

    The EPR spectra of nitrosyl hemoglobin and myoglobin in different conditions (native, denatured and lyophilized), as well as of hematin-NO were obtained in the temperature range of 80 K-280 K. There is a substantial and reversible.decrease of the areas of the EPR spectra of all the hemoglobin samples above 150 K. The interpretation of the results implies the existence of two conformational states in thermal equilibrium only one of which is EPR detectable. Thermodynamical parameters are determined for the hexa and penta-coordinated cases. (author). 25 refs, 3 figs.

  5. Solvent effect on librational dynamics of spin-labelled haemoglobin by ED- and CW-EPR.

    Science.gov (United States)

    Scarpelli, Francesco; Bartucci, Rosa; Sportelli, Luigi; Guzzi, Rita

    2011-03-01

    Two-pulse, echo-detected electron paramagnetic resonance (ED-EPR) spectra and continuous-wave EPR (CW-EPR) spectra were used to investigate the solvent effect on the librational motion of human haemoglobin spin-labelled on cysteine β93 with the nitroxide derivative of maleimide, 6-MSL. Protein samples fully hydrated in phosphate buffer solution (PBS), in a 60% v/v glycerol/water mixture and in the lyophilized form were measured at cryogenic temperature in the frozen state. The protein librational motion was characterized by the amplitude-correlation time product, τ(c), deduced from the ED-EPR spectra. The librational amplitude, τ(c), was determined independently, from the motionally averaged hyperfine splitting in the CW-EPR spectra, and the librational correlation time, τ(c), was derived from the combination of the pulsed and conventional EPR data. Rapid librational motion of small amplitude was detected in all samples. In each case, the librational dynamics was restricted up to 180 K, beyond which it increased steeply for the hydrated protein in PBS and in the presence of glycerol. In contrast, in the dehydrated protein, the librational dynamics was hindered and less dependent on temperature up to ~240 K. In all samples, deviated from small values only for T > 200 K, where a rapid increase of was evident for the hydrated samples, whereas limited temperature variation was shown in the lyophilized samples. The librational correlation time was in the sub-nanosecond regime and weakly dependent on temperature. The results evidence that solvent favours protein dynamics.

  6. The EPR in a few words: all you need to know about the EPR nuclear reactor; L'EPR en bref: ce qu'il faut savoir sur le reacteur nucleaire EPR

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-07-01

    After a brief presentation of the EPR (European - or Evolutionary - Pressurized Reactor) type nuclear reactor, this paper, proposed by the collective group 'Stop EPR', develops the following points: EPR is as dangerous as other reactors; EPR flouts democracy; France's energy demand do not need the construction of EPRs; the construction of EPRs is not a factor of economical and social development; EPR should not be constructed neither in France nor elsewhere and the present building sites should be cancelled; the EPR will not help France to increase its energy independence and protect itself from oil price increases; choosing the EPR is incompatible with the large investments to be made in energy conservation and renewable energies; the EPR is not a solution to climate change; the VHV line corridor that will starts at Flamanville is not justified and poses risks to the environment and public health

  7. Applications of EPR in radiation research

    CERN Document Server

    Lund, Anders

    2014-01-01

    Applications of EPR in Radiation Research is a multi-author contributed volume presented in eight themes: I. Elementary radiation processes (in situ and low temperature radiolysis, quantum solids); II: Solid state radiation chemistry (crystalline, amorphous and heterogeneous systems); III: Biochemistry, biophysics and biology applications (radicals in biomaterials, spin trapping, free-radical-induced DNA damage); IV: Materials science (polymeric and electronic materials, materials for treatment of nuclear waste, irradiated food); V: Radiation metrology (EPR-dosimetry, retrospective and medical

  8. Protocol for emergency EPR dosimetry in fingernails

    OpenAIRE

    Trompier, F; Kornak, L.; Calas, C.; Romanyukha, A.; LeBlanc, B.; Mitchell, C. A.; Swartz, H M; Clairand, I.

    2007-01-01

    There is an increased need for after-the-fact dosimetry because of the high risk of radiation exposures due to terrorism or accidents. In case of such an event, a method is needed to make measurements of dose in a large number of individuals rapidly and with sufficient accuracy to facilitate effective medical triage. Dosimetry based on EPR measurements of fingernails potentially could be an effective tool for this purpose. This paper presents the first operational protocols for EPR fingernail...

  9. Nitric oxide adsorbed on zeolites: EPR studies.

    Science.gov (United States)

    Yahiro, Hidenori; Lund, Anders; Shiotani, Masaru

    2004-05-01

    CW-EPR studies of NO adsorbed on sodium ion-exchanged zeolites were focused on the geometrical structure of NO monoradical and (NO)2 biradical formed on zeolites. The EPR spectrum of NO monoradical adsorbed on zeolite can be characterized by the three different g-tensor components and the resolved y-component hyperfine coupling with the 14N nucleus. Among the g-tensor components, the value of g(zz) is very sensitive to the local environment of zeolite and becomes a measure of the electrostatic field in zeolite. The temperature dependence of the g-tensor demonstrated the presence of two states of the Na-NO adduct, in rigid and rotational states. The EPR spectra of NO adsorbed on alkaline metal ion-exchanged zeolite and their temperature dependency are essentially the same as that on sodium ion-exchanged zeolite. On the other hand, for NO adsorbed on copper ion-exchanged zeolite it is known that the magnetic interaction between NO molecule and paramagnetic copper ion are observable in the spectra recorded at low temperature. The signals assigned to (NO)2 biradical were detected for EPR spectrum of NO adsorbed on Na-LTA. CW-EPR spectra as well as their theoretical calculation suggested that the two NO molecules are aligned along their N-O bond axes. A new procedure for automatical EPR simulation is described which makes it possible to analyze EPR spectrum easily. In the last part of this paper, some instances when other nitrogen oxides were used as a probe molecule to characterize the zeolite structure, chemical properties of zeolites, and dynamics of small molecules were described on the basis of selected literature data reported recently.

  10. Adsorption-desorption induced structural changes of Cu-MOF evidenced by solid state NMR and EPR spectroscopy.

    Science.gov (United States)

    Jiang, Yijiao; Huang, Jun; Kasumaj, Besnik; Jeschke, Gunnar; Hunger, Michael; Mallat, Tamas; Baiker, Alfons

    2009-02-18

    Adsorption-desorption induced structural changes of Cu(bpy)(H(2)O)(2)(BF(4)),(bpy) (bpy = 4,4'-bipyridine) [Cu-MOF] have been evidenced by combined NMR and EPR spectroscopy. Upon adsorption of probe molecules even at a few mbar, EPR spectra show that they are activated to form complexes at Cu(II) sites, which results in a change of the Cu-MOF's structure as indicated by a high-field shift of the (11)B MAS NMR. After desorption, both EPR and (11)B MAS NMR spectra evidenced that the structure of the Cu-MOF reversibly shifted to the original state. This observation indicates that MOFs can undergo structural changes during processes where adsorption-desorption steps are involved such as gas storage, separation, and catalysis.

  11. High-field ELDOR-detected NMR study of a nitroxide radical in disordered solids: Towards characterization of heterogeneity of microenvironments in spin-labeled systems

    Science.gov (United States)

    Nalepa, Anna; Möbius, Klaus; Lubitz, Wolfgang; Savitsky, Anton

    2014-05-01

    The combination of high-field EPR with site-directed spin-labeling (SDSL) techniques employing nitroxide radicals has turned out to be particularly powerful in probing the polarity and proticity characteristics of protein/matrix systems. This information is concluded from the principal components of the nitroxide Zeeman (g), nitrogen hyperfine (A) and quadrupole (P) tensors of the spin labels attached to specific sites. Recent multi-frequency high-field EPR studies underlined the complexity of the problem to treat the nitroxide microenvironment in proteins adequately due to inherent heterogeneities which result in several principal x-components of the nitroxide g-tensor. Concomitant, but distinctly different nitrogen hyperfine components could, however, not be determined from high-field cw EPR experiments owing to the large intrinsic EPR linewidth in fully protonated guest/host systems. It is shown in this work that, using the W-band (95 GHz) ELDOR- (electron-electron double resonance) detected NMR (EDNMR) method, different principal nitrogen hyperfine, Azz, and quadrupole, Pzz, tensor values of a nitroxide radical in glassy 2-propanol matrix can be measured with high accuracy. They belong to nitroxides with different hydrogen-bond situations. The satisfactory resolution and superior sensitivity of EDNMR as compared to the standard ENDOR (electron-nuclear double resonance) method are demonstrated.

  12. Investigation of radical locations in various sesame seeds by CW EPR and 9-GHz EPR imaging.

    Science.gov (United States)

    Nakagawa, K; Hara, H

    2015-01-01

    We investigated the location of radical in various sesame seeds using continuous-wave (CW) electron paramagnetic resonance (EPR) and 9-GHz EPR imaging. CW EPR detected persistent radicals (single line) for various sesame seeds. The EPR linewidth of black sesame seeds was narrower than that of the irradiated white sesame seeds. A very small signal was detected for the white sesame seeds. Two-dimensional (2D) imaging using a 9-GHz EPR imager showed that radical locations vary for various sesame seeds. The paramagnetic species in black sesame seeds were located on the seed coat (skin) and in the hilum region. The signal with the highest intensity was obtained from the hilum part. A very low-intensity image was observed for the white sesame seeds. In addition, the 2D imaging of the irradiated white sesame seeds showed that free radicals were located throughout the entire seed. For the first time, CW EPR and 9-GHz EPR imaging showed the exact location of radical species in various sesame seeds.

  13. Computational and instrumental methods in EPR

    CERN Document Server

    Bender, Christopher J

    2006-01-01

    Computational and Instrumental Methods in EPR Prof. Bender, Fordham University Prof. Lawrence J. Berliner, University of Denver Electron magnetic resonance has been greatly facilitated by the introduction of advances in instrumentation and better computational tools, such as the increasingly widespread use of the density matrix formalism. This volume is devoted to both instrumentation and computation aspects of EPR, while addressing applications such as spin relaxation time measurements, the measurement of hyperfine interaction parameters, and the recovery of Mn(II) spin Hamiltonian parameters via spectral simulation. Key features: Microwave Amplitude Modulation Technique to Measure Spin-Lattice (T1) and Spin-Spin (T2) Relaxation Times Improvement in the Measurement of Spin-Lattice Relaxation Time in Electron Paramagnetic Resonance Quantitative Measurement of Magnetic Hyperfine Parameters and the Physical Organic Chemistry of Supramolecular Systems New Methods of Simulation of Mn(II) EPR Spectra: Single Cryst...

  14. Protocol for emergency EPR dosimetry in fingernails.

    Science.gov (United States)

    Trompier, F; Kornak, L; Calas, C; Romanyukha, A; Leblanc, B; Mitchell, C A; Swartz, H M; Clairand, I

    2007-08-01

    There is an increased need for after-the-fact dosimetry because of the high risk of radiation exposures due to terrorism or accidents. In case of such an event, a method is needed to make measurements of dose in a large number of individuals rapidly and with sufficient accuracy to facilitate effective medical triage. Dosimetry based on EPR measurements of fingernails potentially could be an effective tool for this purpose. This paper presents the first operational protocols for EPR fingernail dosimetry, including guidelines for collection and storage of samples, parameters for EPR measurements, and the method of dose assessment. In a blinded test of this protocol application was carried out on nails freshly sampled and irradiated to 4 and 20 Gy; this protocol gave dose estimates with an error of less than 30%.

  15. Can EPR non-locality be geometrical?

    Energy Technology Data Exchange (ETDEWEB)

    Ne`eman, Y. [Tel-Aviv Univ. (Israel). Raymond and Beverly Sackler Faculty of Exact Sciences]|[Univ. of Texas, Austin, TX (United States). Center for Particle Physics; Botero, A. [Texas Univ., Austin, TX (United States)

    1995-10-01

    The presence in Quantum Mechanics of non-local correlations is one of the two fundamentally non-intuitive features of that theory. The non-local correlations themselves fall into two classes: EPR and Geometrical. The non-local characteristics of the geometrical type are well-understood and are not suspected of possibly generating acausal features, such as faster-than-light propagation of information. This has especially become true since the emergence of a geometrical treatment for the relevant gauge theories, i.e. Fiber Bundle geometry, in which the quantum non-localities are seen to correspond to pure homotopy considerations. This aspect is reviewed in section 2. Contrary-wise, from its very conception, the EPR situation was felt to be paradoxical. It has been suggested that the non-local features of EPR might also derive from geometrical considerations, like all other non-local characteristics of QM. In[7], one of the authors was able to point out several plausibility arguments for this thesis, emphasizing in particular similarities between the non-local correlations provided by any gauge field theory and those required by the preservation of the quantum numbers of the original EPR state-vector, throughout its spatially-extended mode. The derivation was, however, somewhat incomplete, especially because of the apparent difference between, on the one hand, the closed spatial loops arising in the analysis of the geometrical non-localities, from Aharonov-Bohm and Berry phases to magnetic monopoles and instantons, and on the other hand, in the EPR case, the open line drawn by the positions of the two moving decay products of the disintegrating particle. In what follows, the authors endeavor to remove this obstacle and show that as in all other QM non-localities, EPR is somehow related to closed loops, almost involving homotopy considerations. They develop this view in section 3.

  16. TL and EPR dating: some applications

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, S. [Institute of Physics, University of Sao Paulo, Sao Paulo (Brazil)

    2006-07-01

    The intensity of thermoluminescence light emitted by a crystal is a function of radiation dose. The number of defects or of radicals in a crystal or organic substances is also a function of radiation dose. Since such defects or radicals present EPR signals, the EPR intensity is also a function of radiation dose. These facts are basis for radiation dosimetry and can be applied in dating of archaeological potteries or other materials, as well as in dating geological substances such as sediments, caves speleothemes, animal teeth and bones. Recent investigation on sensitized quartz based dosimeters and dating calcite covering ancient wall painting to find early settlers in Brazil will be presented. (Author)

  17. Identification of irradiated crab using EPR

    Energy Technology Data Exchange (ETDEWEB)

    Maghraby, A. [Radiation Dosimetry Department, National Institute for Standards (NIS), Ministry of Scientific Research, Haram, 12211- Giza, P.O. Box: 136 (Egypt)]. E-mail: maghrabism@yahoo.com

    2007-02-15

    EPR spectroscopy is a fast and powerful technique for the identification of irradiated food. Crab exoskeleton was divided into six parts: dactyl, cheliped, carapace, apron, swimming legs, and walking legs. Samples of the exoskeleton were prepared and irradiated to Cs-137 gamma radiation in the range (1.156-5.365 kGy). EPR spectra of unirradiated as well as irradiated samples were recorded and analyzed. Response to gamma radiation was plotted for each part of the exoskeleton, dactyl was found to be the most sensitive part, followed by the apron (38%), cheliped (37%), walking legs (30%), swimming legs (24%), and carapace (21%) relative to the dactyl response.

  18. How can EPR spectroscopy help to unravel molecular mechanisms of flavin-dependent photoreceptors?

    Directory of Open Access Journals (Sweden)

    Daniel eNohr

    2015-09-01

    Full Text Available Electron paramagnetic resonance (EPR spectroscopy is a well-established spectroscopic method for the examination of paramagnetic molecules. Proteins can contain paramagnetic moieties in form of stable cofactors, transiently formed intermediates, or spin labels artificially introduced to cysteine sites. The focus of this review is to evaluate potential scopes of application of EPR to the emerging field of optogenetics. The main objective for EPR spectroscopy in this context is to unravel the complex mechanisms of light-active proteins, from their primary photoreaction to downstream signal transduction. An overview of recent results from the family of flavin-containing, blue-light dependent photoreceptors is given. In detail, mechanistic similarities and differences are condensed from the three classes of flavoproteins, the cryptochromes, LOV (Light-oxygen-voltage, and BLUF (blue-light using FAD domains. Additionally, a concept that includes spin-labeled proteins and examination using modern pulsed EPR is introduced, which allows for a precise mapping of light-induced conformational changes.

  19. Electron Paramagnetic Resonance Imaging: 2. Radiofrequency FT-EPR Imaging

    Indian Academy of Sciences (India)

    2016-08-01

    In this part we shall outline the challenges one faces whiledeveloping time-domain radiofrequency (RF) EPR imagingspectrometer for in vivo studies. Time-domain or FT-EPR isquite a different animal compared to the CW modality. Theevolution of FT-EPR instrumentation at the National CancerInstitute, NIH, USA and representative examples of applicationin cancer research are outlined in this article.

  20. Pulsed electron-nuclear-electron triple resonance spectroscopy

    Science.gov (United States)

    Thomann, Hans; Bernardo, Marcelino

    1990-05-01

    A new experimental technique, pulsed electron-nuclear-electron triple resonance spectroscopy, is demonstrated. It is based on a modification of the pulse sequence for electron-nuclear double resonance (ENDOR) in which two EPR and one NMR transition are irradiated. The irradiation of one EPR transition is detected via a second EPR transition. The nuclear hyperfine coupling, which separates these EPR transition frequencies, is the irradiated NMR transition. The major advantages of triple resonance spectroscopy include the ability to resolve overlapping nuclear resonances in the ENDOR spectrum and a more direct quantitative assignment of nuclear hyperfine and quadrupole couplings. The triple resonance experiment is an alternative to the recently proposed method of employing rapid magnetic field jumps between microwave pulses for generating hyperfine selective ENDOR spectra.

  1. Monitoring enzymatic ATP hydrolysis by EPR spectroscopy.

    Science.gov (United States)

    Hacker, Stephan M; Hintze, Christian; Marx, Andreas; Drescher, Malte

    2014-07-14

    An adenosine triphosphate (ATP) analogue modified with two nitroxide radicals is developed and employed to study its enzymatic hydrolysis by electron paramagnetic resonance spectroscopy. For this application, we demonstrate that EPR holds the potential to complement fluorogenic substrate analogues in monitoring enzymatic activity.

  2. EPR spin trapping of protein radicals

    DEFF Research Database (Denmark)

    Davies, Michael Jonathan; Hawkins, Clare Louise

    2004-01-01

    Electron paramagnetic resonance (EPR) spin trapping was originally developed to aid the detection of low-molecular-mass radicals formed in chemical systems. It has subsequently found widespread use in biology and medicine for the direct detection of radical species formed during oxidative stress ...... examples of radical formation on proteins....

  3. High-field dipoles for future accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Wipf, S.L.

    1984-09-01

    This report presents the concept for building superconducting accelerator dipoles with record high fields. Economic considerations favor the highest possible current density in the windings. Further discussion indicates that there is an optimal range of pinning strength for a superconducting material and that it is not likely for multifilamentary conductors to ever equal the potential performance of tape conductors. A dipole design with a tape-wound, inner high-field winding is suggested. Methods are detailed to avoid degradation caused by flux jumps and to overcome problems with the dipole ends. Concerns for force support structure and field precision are also addressed. An R and D program leading to a prototype 11-T dipole is outlined. Past and future importance of superconductivity to high-energy physics is evident from a short historical survey. Successful dipoles in the 10- to 20-T range will allow interesting options for upgrading present largest accelerators.

  4. Simulation of multi-frequency EPR spectra for a distribution of the zero-field splitting

    Science.gov (United States)

    Azarkh, Mykhailo; Groenen, Edgar J. J.

    2015-06-01

    We present a numerical procedure called 'grid-of-errors' to extract the distribution of magnetic interactions from continuous-wave electron-paramagnetic-resonance (EPR) spectra at multiple microwave frequencies. The approach is based on the analysis of the lineshape of the spectra and explicitly worked out for high-spin systems for which the lineshape is determined by a distribution of the zero-field splitting. Initial principal values of the zero-field splitting tensor are obtained from the EPR spectrum at a microwave frequency in the high-field limit, and the initial distribution is taken Gaussian. Subsequently, the grid-of-errors procedure optimizes this distribution, without any restriction to its shape, taking into account spectra at various microwave frequencies. The numerical procedure is illustrated for the Fe(III)-EDTA complex. An optimized distribution of the zero-field splitting is obtained, which provides a proper description of the EPR spectra at 9.5, 34, 94, and 275 GHz. The proposed approach can be used as well for distributions of magnetic interactions other than the zero-field splitting.

  5. Triplet state in photosystem II reaction centers as studied by 130 GHz EPR

    Energy Technology Data Exchange (ETDEWEB)

    Pashenko, S.V.; Proskuryakov, I.I.; Germano, M.; Gorkom, H.J. van; Gast, P

    2003-11-01

    The triplet state in the reaction centers of photosystem II was studied by high-field/high-frequency (130 GHz) EPR in the temperature range 50-90 K. At 50 K, the zero-field splitting parameters of the EPR spectrum correspond well to those of a chlorophyll monomer, in agreement with earlier studies. In the high magnetic field of 4.6 T employed in this study, the g-anisotropy of the triplet state becomes apparent and leads to a shift of the canonical positions of the triplet EPR spectrum. Assuming that triplet g- and zero-field tensors are coaxial, the principal values of the triplet g-tensor are determined to be 2.00324, 2.00306 and 2.00231 with an error of {+-}0.00004. Lifting this assumption results in higher g-anisotropy. At higher temperatures, the shape of the spectra changes significantly. Triplet excitation hopping involving the accessory chlorophyll B{sub A} and P{sub A} or P{sub B} (equivalents of the special pair bacteriochlorophylls of the bacterial reaction centers) can partially explain those changes, but the most prominent features indicate that also the electron acceptor I{sub A} (a pheophytin molecule) must be involved.

  6. Synergistic effect of nanoclay and EPR-g-MA on the properties of nylon6/EPR blends.

    Science.gov (United States)

    Mallick, Sumana; Das, Tanya; Das, C K; Khatua, B B

    2009-05-01

    The effect of EPR-g-MA, nanoclay and a combination of the two on phase morphology and properties of (70/30 w/w) nylon6/EPR blends prepared by melt processing technique has been studied. We found that the number average domain diameter (D(n)) of the dispersed EPR phase in the blend decreased in presence of EPR-g-MA, and clay. This observation indicated that nanoclay could be used as an effective compatibilizer in nylon6/EPR blend. X-ray diffraction study and TEM analysis of the blend/clay nanocomposites revealed the delaminated clay morphology and preferential location of the exfoliated clay platelets in nylon6 phase. Thus, selective dispersion of the clay platelets with delaminated morphology in the matrix phase acted as the barrier and thereby prevented the coalescence of dispersed EPR domains during melt processing. However, addition of nanoclay in the blend did not improve the impact property of the blend. Interestingly, the impact strength of the nylon6/EPR/EPR-g-MA/clay blend was much higher than the nylon6/EPR/EPR-g-MA and nylon6/EPR/clay blends at certain compositions with comparable D(n) values. This could be explained by assuming the presence of delaminated clay platelets at the interface, which were stiffer than the polymers. Hence, the bending energy of the interfaces was high.

  7. EPR in characterization of seeds paramagnetic species

    Energy Technology Data Exchange (ETDEWEB)

    Luiz, A.P.C.; Mauro, M.F.F.L.; Portugal, K.O.; Barbana, V.M.; Guedes, C.L.B.; Mauro, E. di; Carneiro, C.E.A.; Zaia, D.A.M.; Prete, C.E.C. [Universidade Estadual de Londrina (UEL), PR (Brazil)

    2011-07-01

    Full text. In Brazil, since 1970s, renewable fuel programs has been developed in order to replace petroleum. Today a program that has been discussed is the bio diesel, which intend to replace diesel fuel, fossil oil, to bio diesel, renewal fuel. As seeds are the basis for production of oil and consequently processed into bio diesel, the goal of this work is to characterize and compare paramagnetic species present in the seeds by Electron Paramagnetic Resonance (EPR). Samples used in this study were seeds of sorghum, barley, corn, peanuts, soy beans, cotton, wheat, oats, mustard, rice, sunflower and turnip. Some paramagnetic species present in soil was also investigated as goethite (FeOOH), hematite (Fe{sub 2}O{sub 3}), magnetite (Fe{sub 3}O{sub 4}), and ferrihydrite (Fe{sub 5}HO{sub 8} {center_dot} 4H{sub 2}O), since, these species present in appreciable quantities in the soil can be present in the seeds and analyzed for comparison. The characterization of these species is essential to understand the EPR seeds spectra. Each sample is placed in a thin quartz tube 4 mm in diameter, and it is inserted into the cavity of the spectrometer at room temperature, at low temperature (77 K) and variable temperature using liquid nitrogen flow and hot flow through a compressor air. It was used as standard Mg O:Mn{sup 2+}, which is also inserted into the cavity. Shortly after the potency is regulated, frequency, amplitude and sweep the field. The spectroscopic analysis by EPR X-band ({approx} 9:5GHz), were performed at the Fluorescence and Electron Paramagnetic Resonance Laboratory, Exact Sciences Center, State University of Londrina, Parana state, Brazil, through an EPR spectrometer JEOL brand (JES-PE-3X). In the EPR spectra, spectroscopic factor or g factor and line width were determined in paramagnetic species. Studies from several seeds with EPR technique detected in all of them presence of same complex of Fe{sup 3+} present in the goethite at g {approx} 2, and in the seeds

  8. EPR spectroscopy of nitrite complexes of methemoglobin.

    Science.gov (United States)

    Schwab, David E; Stamler, Jonathan S; Singel, David J

    2010-07-19

    The chemical interplay of nitrogen oxides (NO's) with hemoglobin (Hb) has attracted considerable recent attention because of its potential significance in the mechanism of NO-related vasoactivity regulated by Hb. An important theme of this interplay-redox coupling in adducts of heme iron and NO's-has sparked renewed interest in fundamental studies of FeNO(x) coordination complexes. In this Article, we report combined UV-vis and comprehensive electron paramagnetic resonance (EPR) spectroscopic studies that address intriguing questions raised in recent studies of the structure and affinity of the nitrite ligand in complexes with Fe(III) in methemoglobin (metHb). EPR spectra of metHb/NO(2)(-) are found to exhibit a characteristic doubling in their sharper spectral features. Comparative EPR measurements at X- and S-band frequencies, and in D(2)O versus H(2)O, argue against the assignment of this splitting as hyperfine structure. Correlated changes in the EPR spectra with pH enable complete assignment of the spectrum as deriving from the overlap of two low-spin species with g values of 3.018, 2.122, 1.45 and 2.870, 2.304, 1.45 (values for samples at 20 K and pH 7.4 in phosphate-buffered saline). These g values are typical of g values found for other heme proteins with N-coordinated ligands in the binding pocket and are thus suggestive of N-nitro versus O-nitrito coordination. The positions and shapes of the spectral lines vary only slightly with temperature until motional averaging ensues at approximately 150 K. The pattern of motional averaging in the variable-temperature EPR spectra and EPR studies of Fe(III)NO(2)(-)/Fe(II)NO hybrids suggest that one of two species is present in both of the alpha and beta subunits, while the other is exclusive to the beta subunit. Our results also reconfirm that the affinity of nitrite for metHb is of millimolar magnitude, thereby making a direct role for nitrite in physiological hypoxic vasodilation difficult to justify.

  9. Holographic EPR Pairs, Wormholes and Radiation

    CERN Document Server

    Chernicoff, Mariano; Pedraza, Juan F

    2013-01-01

    As evidence for the ER=EPR conjecture, it has recently been observed that the string that is holographically dual to an entangled quark-antiquark pair separating with (asymptotically) uniform acceleration has a wormhole on its worldsheet. We point out that a two-sided horizon and a wormhole actually appear for much more generic quark-antiquark trajectories, which is consistent with the fact that the members of an EPR pair need not be permanently out of causal contact. The feature that determines whether the causal structure of the string worldsheet is trivial or not turns out to be the emission of gluonic radiation by the dual quark and antiquark. In the strongly-coupled gauge theory, it is only when radiation is emitted that one obtains an unambiguous separation of the pair into entangled subsystems, and this is what is reflected on the gravity side by the existence of the worldsheet horizon.

  10. EPR-dosimetry with carious teeth

    Energy Technology Data Exchange (ETDEWEB)

    Sholom, S.V. E-mail: sholom@leed1.kiev.ua; Haskell, E.H.; Hayes, R.B.; Chumak, V.V.; Kenner, G.H

    2000-12-15

    The effect of caries in EPR dosimetry of tooth enamel (in the dose range of 0-1 Gy) was investigated. The enamel of each tooth was divided into carious, non-carious and intermediate portions. The EPR signals of enamel at g=2.0018 (dosimetric) and g=2.0045 (native) were examined. The intensity of the dosimetric signal was the same for all three portions, while that of the native signal was higher for carious portions than for non-carious and intermediate portions. Reconstruction of the laboratory applied doses was done using all portions. Reasonable correlation between nominal and reconstructed doses was found in most cases. The effect of alkali treatment on the native and dosimetric signals of enamel was also tested. Reduction of the native signal intensity, particularly in the carious portions, was found to be the only significant effect. This resulted in a slight improvement in the accuracy of the reconstructed doses.

  11. Antenna development for high field plasma imaging.

    Science.gov (United States)

    Kong, X; Domier, C W; Luhmann, N C

    2010-10-01

    Electron cyclotron emission imaging (ECEI) and microwave imaging reflectometry (MIR) are two microwave nonperturbing plasma visualization techniques that employ millimeter-wave imaging arrays with lens-coupled planar antennas, yielding time-resolved images of temperature (via ECEI) and electron density (via MIR) fluctuations within high temperature magnetic fusion plasmas. A series of new planar antennas have been developed that extend this technology to frequencies as high as 220 GHz for use on high field plasma devices with toroidal fields in excess of 3 T. Antenna designs are presented together with theoretical calculations, simulations, and experimental measurements.

  12. Self-testing through EPR-steering

    Science.gov (United States)

    Šupić, Ivan; Hoban, Matty J.

    2016-07-01

    The verification of quantum devices is an important aspect of quantum information, especially with the emergence of more advanced experimental implementations of quantum computation and secure communication. Within this, the theory of device-independent robust self-testing via Bell tests has reached a level of maturity now that many quantum states and measurements can be verified without direct access to the quantum systems: interaction with the devices is solely classical. However, the requirements for this robust level of verification are daunting and require high levels of experimental accuracy. In this paper we discuss the possibility of self-testing where we only have direct access to one part of the quantum device. This motivates the study of self-testing via EPR-steering, an intermediate form of entanglement verification between full state tomography and Bell tests. Quantum non-locality implies EPR-steering so results in the former can apply in the latter, but we ask what advantages may be gleaned from the latter over the former given that one can do partial state tomography? We show that in the case of self-testing a maximally entangled two-qubit state, or ebit, EPR-steering allows for simpler analysis and better error tolerance than in the case of full device-independence. On the other hand, this improvement is only a constant improvement and (up to constants) is the best one can hope for. Finally, we indicate that the main advantage in self-testing based on EPR-steering could be in the case of self-testing multi-partite quantum states and measurements. For example, it may be easier to establish a tensor product structure for a particular party’s Hilbert space even if we do not have access to their part of the global quantum system.

  13. DAC-board based X-band EPR spectrometer with arbitrary waveform control.

    Science.gov (United States)

    Kaufmann, Thomas; Keller, Timothy J; Franck, John M; Barnes, Ryan P; Glaser, Steffen J; Martinis, John M; Han, Songi

    2013-10-01

    We present arbitrary control over a homogenous spin system, demonstrated on a simple, home-built, electron paramagnetic resonance (EPR) spectrometer operating at 8-10 GHz (X-band) and controlled by a 1 GHz arbitrary waveform generator (AWG) with 42 dB (i.e. 14-bit) of dynamic range. Such a spectrometer can be relatively easily built from a single DAC (digital to analog converter) board with a modest number of stock components and offers powerful capabilities for automated digital calibration and correction routines that allow it to generate shaped X-band pulses with precise amplitude and phase control. It can precisely tailor the excitation profiles "seen" by the spins in the microwave resonator, based on feedback calibration with experimental input. We demonstrate the capability to generate a variety of pulse shapes, including rectangular, triangular, Gaussian, sinc, and adiabatic rapid passage waveforms. We then show how one can precisely compensate for the distortion and broadening caused by transmission into the microwave cavity in order to optimize corrected waveforms that are distinctly different from the initial, uncorrected waveforms. Specifically, we exploit a narrow EPR signal whose width is finer than the features of any distortions in order to map out the response to a short pulse, which, in turn, yields the precise transfer function of the spectrometer system. This transfer function is found to be consistent for all pulse shapes in the linear response regime. In addition to allowing precise waveform shaping capabilities, the spectrometer presented here offers complete digital control and calibration of the spectrometer that allows one to phase cycle the pulse phase with 0.007° resolution and to specify the inter-pulse delays and pulse durations to ≤ 250 ps resolution. The implications and potential applications of these capabilities will be discussed.

  14. High-field magnetization in transuranium compound

    Energy Technology Data Exchange (ETDEWEB)

    Sugiyama, K. [Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan) and KYOKUGEN, Osaka University, Osaka 560-8531 (Japan)]. E-mail: sugiyama@phys.sci.osaka-u.ac.jp; Nakashima, H. [Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Aoki, D. [Institute of Material Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Ikeda, S. [Institute of Material Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Haga, Y. [Advanced Science and Research Centerer, JAEA, Tokai, Ibaraki 319-1195 (Japan); Yamamoto, E. [Advanced Science and Research Centerer, JAEA, Tokai, Ibaraki 319-1195 (Japan); Nakamura, A. [Advanced Science and Research Centerer, JAEA, Tokai, Ibaraki 319-1195 (Japan); Homma, Y. [Institute of Material Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Shiokawa, Y. [Institute of Material Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Kindo, K. [Institite of Solid State Physics, University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba 277-8581 (Japan); Hagiwara, M. [KYOKUGEN, Osaka University, Osaka 560-8531 (Japan); Onuki, Y. [Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Advanced Science and Research Centerer, JAEA, Tokai, Ibaraki 319-1195 (Japan)

    2007-03-15

    We measured the high-field magnetization up to 55T and constructed a magnetic phase diagram for a transuranium antiferromagnet NpRhGa{sub 5} with the tetragonal structure. The magnetization at 4.2K for H(parallel) [100] indicates a sharp metamagnetic transition with a step at H{sub c}=26T and saturates above H{sub s}=38T, reaching 0.43{mu}{sub B}/Np. An ordered moment of 0.96{mu}{sub B}/Np at zero field, which was determined from the neutron scattering experiment, is found to be reduced to 0.43{mu}{sub B}/Np at H{sub s}, together with an orientation of the magnetic moment from the (001) plane to the (100) plane.

  15. EPR study on gamma-irradiated fruits dehydrated via osmosis

    Energy Technology Data Exchange (ETDEWEB)

    Yordanov, N.D. [Laboratory EPR, Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria)]. E-mail: ndyepr@bas.bg; Aleksieva, K. [Laboratory EPR, Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria)

    2007-06-15

    The shape and time stability of the electron paramagnetic resonance (EPR) spectra of non- and {gamma}-irradiated papaya, melon, cherry and fig samples dehydrated via osmosis are reported. It is shown that non-irradiated samples are generally EPR silent whereas {gamma}-irradiated exhibit 'sugar-like' EPR spectra. The recorded EPR spectra are monitored for a period of 7 months after irradiation (stored at low humidity and in the dark). The results suggest longer period of unambiguous identification of the radiation processing of osmose dehydrated fruits. Therefore, the Protocol EN 13708,2001 issued by CEN is fully applicable for the studied fruit samples.

  16. Electron-mediating Cu(A) centers in proteins: a comparative high field (1)H ENDOR study.

    Science.gov (United States)

    Epel, Boris; Slutter, Claire S; Neese, Frank; Kroneck, Peter M H; Zumft, Walter G; Pecht, Israel; Farver, Ole; Lu, Yi; Goldfarb, Daniella

    2002-07-10

    High field (W-band, 95 GHz) pulsed electron-nuclear double resonance (ENDOR) measurements were carried out on a number of proteins that contain the mixed-valence, binuclear electron-mediating Cu(A) center. These include nitrous oxide reductase (N(2)OR), the recombinant water-soluble fragment of subunit II of Thermus thermophilus cytochrome c oxidase (COX) ba(3) (M160T9), its M160QT0 mutant, where the weak axial methionine ligand has been replaced by a glutamine, and the engineered "purple" azurin (purpAz). The three-dimensional (3-D) structures of these proteins, apart from the mutant, are known. The EPR spectra of all samples showed the presence of a mononuclear Cu(II) impurity with EPR characteristics of a type II copper. At W-band, the g( perpendicular) features of this center and of Cu(A) are well resolved, thus allowing us to obtain a clean Cu(A) ENDOR spectrum. The latter consists of two types of ENDOR signals. The first includes the signals of the four strongly coupled cysteine beta-protons, with isotropic hyperfine couplings, A(iso), in the 7-15 MHz range. The second group consists of weakly coupled protons with a primarily anisotropic character with A(zz) < 3 MHz. Orientation selective ENDOR spectra were collected for N(2)OR, M160QT0, and purpAz, and simulations of the cysteine beta-protons signals provided their isotropic and anisotropic hyperfine interactions. A linear correlation with a negative slope was found between the maximum A(iso) value of the beta-protons and the copper hyperfine interaction. Comparison of the best-fit anisotropic hyperfine parameters with those calculated from dipolar interactions extracted from the available 3-D structures sets limit to the sulfur spin densities. Similarly, the small coupling spectral region was simulated on the basis of the 3-D structures and compared with the experimental spectra. It was found that the width of the powder patterns of the weakly coupled protons recorded at g(perpendicular) is mainly

  17. Delocalisation of photoexcited triplet states probed by transient EPR and hyperfine spectroscopy

    Science.gov (United States)

    Richert, Sabine; Tait, Claudia E.; Timmel, Christiane R.

    2017-07-01

    Photoexcited triplet states play a crucial role in photochemical mechanisms: long known to be of paramount importance in the study of photosynthetic reaction centres, they have more recently also been shown to play a major role in a number of applications in the field of molecular electronics. Their characterisation is crucial for an improved understanding of these processes with a particular focus on the determination of the spatial distribution of the triplet state wavefunction providing information on charge and energy transfer efficiencies. Currently, active research in this field is mostly focussed on the investigation of materials for organic photovoltaics (OPVs) and organic light emitting diodes (OLEDs). As the properties of triplet states and their spatial extent are known to have a major impact on device performance, a detailed understanding of the factors governing triplet state delocalisation is at the basis of the further development and improvement of these devices. Electron Paramagnetic Resonance (EPR) has proven a valuable tool in the study of triplet state properties and both experimental methods as well as data analysis and interpretation techniques have continuously improved over the last few decades. In this review, we discuss the theoretical and practical aspects of the investigation of triplet states and triplet state delocalisation by transient continuous wave and pulse EPR and highlight the advantages and limitations of the presently available techniques and the current trends in the field. Application of EPR in the study of triplet state delocalisation is illustrated on the example of linear multi-porphyrin chains designed as molecular wires.

  18. Locations of radical species in black pepper seeds investigated by CW EPR and 9 GHz EPR imaging

    Science.gov (United States)

    Nakagawa, Kouichi; Epel, Boris

    2014-10-01

    In this study, noninvasive 9 GHz electron paramagnetic resonance (EPR)-imaging and continuous wave (CW) EPR were used to investigate the locations of paramagnetic species in black pepper seeds without further irradiation. First, lithium phthalocyanine (LiPC) phantom was used to examine 9 GHz EPR imaging capabilities. The 9 GHz EPR-imager easily resolved the LiPC samples at a distance of ∼2 mm. Then, commercially available black pepper seeds were measured. We observed signatures from three different radical species, which were assigned to stable organic radicals, Fe3+, and Mn2+ complexes. In addition, no EPR spectral change in the seed was observed after it was submerged in distilled H2O for 1 h. The EPR and spectral-spatial EPR imaging results suggested that the three paramagnetic species were mostly located at the seed surface. Fewer radicals were found inside the seed. We demonstrated that the CW EPR and 9 GHz EPR imaging were useful for the determination of the spatial distribution of paramagnetic species in various seeds.

  19. Public debate on the EPR reactor; Debat public sur le reacteur EPR

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-10-15

    In the framework of the new EPR European Pressurized Reactor implementation in France, the public asked the first Ministry on the protection of nuclear matters, transports and installations against the terrorism and the spiteful actions. This document provides information on the subject and shows the safety of the new reactor. (A.L.B.)

  20. Alternative Contrast Mechanisms in High Field MR Microscopy.

    Science.gov (United States)

    Engelhardt, Robert Thomas

    1995-01-01

    In high-field MR Microscopy, the T_1 relaxation times may become long and converge while the T_2 relaxation times may become short and converge. As a result, much of the contrast is due solely to differences in spin density. The use of T_{1rho} as an alternative contrast parameter in high-field MR Microscopy has been explored here. To this end, MR Microscopy experiments have been performed using 2.0 and 9.4 Tesla Bruker MRI systems. Spectroscopy experiments at 9.4 Tesla were performed on several phantoms (5.75% agar gel, 1.0 mM MnCl_2, 7.3% and 20% gelatin). Imaging experiments were performed on two, 17.5 day old, perfusion fixed, mouse embryos, embedded in 7.3% gelatin to minimize drying and susceptibility differences. The relaxation times, T_1, T _2, and T_{1rho }, the signal to noise ratios (SNR) and contrast to noise ratios (CNR), have been measured for several types of tissue. The T_{1rho} relaxation times were measured at four locking field strengths, 0.7, 0.9, 1.3 and 1.7 G. T_1 and T_2 imaging experiments were performed using a conventional spin warp imaging sequence. T_{1rho } imaging experiments were performed using a presaturating spin locking pulse, followed by a conventional spin warp imaging sequence. Muscle, diencephalon, lung and liver were chosen for the relaxation time measurements as they offered both good tissue specificity and size. Both static and locking field dispersion of T _{1rho} were observed in the selected mouse embryo tissues. The observed T _{1rho} relaxation times were generally longer than the T_2 relaxation times, increased with locking field strength, and were consistently shorter at 9.4 Tesla than at 2.0 Tesla. The static field dispersion of T_ {1rho} and T_2 are both believed to be due, in part, to diffusion losses through susceptibility induced gradients. The losses are much smaller in the T_{1rho} images, and decrease as the locking pulse is increased. Finally, under certain circumstances, T_{1rho }-weighting could produce

  1. Sistemas de salvaguardia en reactores EPR

    OpenAIRE

    2015-01-01

    En este documento se describe brevemente el funcionamiento de los diversos sistemas de una planta nuclear operada con un reactor de tipo PWR. Más concretamente, el proyecto se centra en una descripción exhaustiva de los sistemas de salvaguardia y seguridad que regulan el funcionamiento de un reactor de tipo EPR, así como la central nuclear que contiene a dicho reactor. El proceso ha consistido en clasificar y resumir los distintos sistemas que operan en dicha planta, estudiando sus caracterís...

  2. EPR identification of intrinsic defects in SiC

    Energy Technology Data Exchange (ETDEWEB)

    Umeda, T.; Mizuochi, N. [University of Tsukuba, Tsukuba 305-8550 (Japan); Son, N.T.; Janzen, E. [Department of Physics, Chemistry and Biology, Linkoeping University, Linkoeping (Sweden); Ohshima, T. [Japan Atomic Energy Agency, Takasaki 370-1292 (Japan); Isoya, J.

    2008-07-15

    The structure determination of intrinsic defects in 4H-SiC, 6H-SiC, and 3C-SiC by means of EPR is based on measuring the angular dependence of the {sup 29}Si/{sup 13}C hyperfine (HF) satellite lines, from which spin densities, sp-hybrid ratio, and p-orbital direction can be determined over major atoms comprising a defect. In most cases, not only the assignment of the variety due to the inequivalent sites (h- and k-sites in 4H-SiC) but also the identification of the defect species is accomplished through the comparison of the obtained HF parameters with those obtained from first principles calculations. Our works of identifying vacancy-related defects such as the monovacancies, divacancies, and antisite-vacancy pairs in 4H-SiC are reviewed. In addition, it is demonstrated that the observation of the central line of the T{sub V2a} center of S=3/2 has been achieved by pulsed-ELDOR. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Implementation of GPU-accelerated back projection for EPR imaging.

    Science.gov (United States)

    Qiao, Zhiwei; Redler, Gage; Epel, Boris; Qian, Yuhua; Halpern, Howard

    2015-01-01

    Electron paramagnetic resonance (EPR) Imaging (EPRI) is a robust method for measuring in vivo oxygen concentration (pO2). For 3D pulse EPRI, a commonly used reconstruction algorithm is the filtered backprojection (FBP) algorithm, in which the backprojection process is computationally intensive and may be time consuming when implemented on a CPU. A multistage implementation of the backprojection can be used for acceleration, however it is not flexible (requires equal linear angle projection distribution) and may still be time consuming. In this work, single-stage backprojection is implemented on a GPU (Graphics Processing Units) having 1152 cores to accelerate the process. The GPU implementation results in acceleration by over a factor of 200 overall and by over a factor of 3500 if only the computing time is considered. Some important experiences regarding the implementation of GPU-accelerated backprojection for EPRI are summarized. The resulting accelerated image reconstruction is useful for real-time image reconstruction monitoring and other time sensitive applications.

  4. Nonselective excitation of pulsed ELDOR using multi-frequency microwaves

    Science.gov (United States)

    Asada, Yuki; Mutoh, Risa; Ishiura, Masahiro; Mino, Hiroyuki

    2011-12-01

    The use of a polychromatic microwave pulse to expand the pumping bandwidth in pulsed electron-electron double resonance (PELDOR) was investigated. The pumping pulse was applied in resonance with the broad (˜100 mT) electron paramagnetic resonance (EPR) signal of the manganese cluster of photosystem II in the S 2 state. The observation pulses were in resonance with the narrow EPR signal of the tyrosine radical, YDrad . It was found that in the case of the polychromatic pumping pulse containing five harmonics with the microwave frequencies between 8.5 and 10.5 GHz the PELDOR effect corresponding to the dipole interaction between the Mn cluster and YDrad was about 2.9 times larger than that achieved with a monochromatic pulse. In addition to the dipolar modulation, the nuclear modulation effects were observed. The effects could be suppressed by averaging the PELDOR trace over the time interval between the observation microwave pulses. The polychromatic excitation technique described will be useful for improving the PELDOR sensitivity in the measurements of long distances in biological samples, where the pair consists of a radical with a narrow EPR spectrum and slow phase relaxation, and a metal center that has a broad EPR spectrum and a short phase relaxation time.

  5. THE RADIATION CROSSLINKING OF EPR/SBR BLEND

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wanxi; L(U) Yingtao; SUN Jiazhen

    1990-01-01

    The radiation crosslinking of EPR/SBR blend has been studied. A relationship between sol fraction and radiation dose for the different weight ratio polymer blends and the method to calculate βb value of EPR/SBR blend system have been established.

  6. EPR study on tomatoes before and after gamma-irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Aleksieva, K. [Laboratory EPR, Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Georgieva, L.; Tzvetkova, E. [Institute of Cryobiology and Food Technology, 1162 Sofia (Bulgaria); Yordanov, N.D. [Laboratory EPR, Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria)], E-mail: ndyepr@bas.bg

    2009-09-15

    The results from the EPR studies on fresh, air-dried and lyophilized tomato samples before and after gamma-irradiation are reported. Before irradiation fresh and air-dried tomatoes exhibit one singlet EPR line characterized with common g-factor of 2.0048{+-}0.0005, whereas freeze-dried tomato does not show any EPR spectrum. After irradiation, a typical 'cellulose-like' triplet EPR spectrum appears in all samples, attributed to cellulose free radicals, generated by gamma-irradiation. It consists of intense central line with g=2.0048{+-}0.0005 and two weak satellite lines separated ca. 3 mT left and right of it. In air-dried and lyophilized tomatoes the 'cellulose-like' EPR spectrum is superimposed by an additional partly resolved carbohydrate spectrum. Fading measurements of the radiation-induced EPR signals indicate that the intensity of the EPR spectra of air-dried and freeze-dried tomato are reduced to about 50% after 50 days, whereas those of fresh irradiated tomatoes kept at 4 {sup o}C fade completely in 15 days. The reported results unambiguously show that the presence of two satellite lines in the EPR 'cellulose-like' spectra of tomato samples can be used for identification of radiation processing.

  7. Quantum Encryption Protocol Based on Continuous Variable EPR Correlations

    Institute of Scientific and Technical Information of China (English)

    HE Guang-Qiang; ZENG Gui-Hua

    2006-01-01

    A quantum encryption protocol based on Gaussian-modulated continuous variable EPR correlations is proposed. The security is guaranteed by continuous variable EPR entanglement correlations produced by nondegenerate optical parametric amplifier (NOPA). For general beam splitter eavesdropping strategy, the mutual information Ⅰ(α, ε)between Alice and Eve is calculated by employing Shannon information theory. Finally the security analysis is presented.

  8. EPR and NMR spectroscopy on spin-labeled proteins

    NARCIS (Netherlands)

    Finiguerra, Michelina Giuseppina

    2011-01-01

    Spin labeling and electron paramagnetic resonance (EPR) have been employed to study structure and dynamics of proteins. The surface polarity of four single cysteine mutants of the Zn-azurin in frozen solution were studied using 275 GHz EPR (J-band), with the advantage compared to 9 GHz (X-band) and

  9. Which Parts of a Clinical Process EPR Needs Special Configuration

    DEFF Research Database (Denmark)

    Barlach, Anders; Simonsen, Jesper

    2007-01-01

    Subject: Which parts of an electronic patient record (EPR) can initially form a stable standard solution to be used by all clinicians? And which parts of an EPR can we predict needs initial as well as on-going re-configuration to meet the needs from diverse medical specialties. Purpose: To analyz...

  10. High field terahertz emission from relativistic laser-driven plasma wakefields

    CERN Document Server

    Chen, Zi-Yu

    2015-01-01

    We propose a method to generate high field terahertz (THz) radiation with peak strength of GV/cm level in the THz frequency gap range 1-10 THz using a relativistic laser interaction with a gaseous plasma target. Due to the effect of local pump depletion, an initially Gaussian laser pulse undergoes leading edge erosion and eventually evolves to a state with leading edge being step function. Interacting with such a pulse, electrons gain transverse residual momentum and excite net transverse currents modulated by the relativistic plasma frequency. These currents give rise to the low frequency THz emission. We demonstrate this process with one and two dimensional particle-in-cell simulations.

  11. Derivation of the high field semiconductor equations

    Energy Technology Data Exchange (ETDEWEB)

    Hagan, P.S. (Los Alamos National Lab., NM (United States)); Cox, R.W. (Department of Computer Information Science, Indiana University, Purdue University, Indianapolis (USA)); Wagner, B.A. (Arizona Univ., Tucson, AZ (United States). Dept. of Mathematics)

    1991-01-01

    Electron and hole densities evolve in x-z phase space according to Boltzmann equations. When the mean free path of the particles is short and electric force on the particles is weak, a well-known expansion can be used to solve the Boltzmann equation. This asymptotic solution shows that the spatial density of electrons and holes evolves according to diffusion-drift equations. As devices become smaller, electric fields become stronger, which renders the Basic Semiconductor Equations increasingly inaccurate. To remedy this problem, we use singular perturbation techniques to obtain a new asymptotic expansion for the Boltzmann equation. Like the Hilbert expansion, the new expansion requires the mean free path to be short compared to all macroscopic length scales. However, it does not require the electric forces to be weak. The new expansion shows that spatial densities obey diffusion-drift equations as before, but the diffusivity D and mobility {mu} turn out to be nonlinear functions of the electric field. In particular, our analysis determines the field-dependent mobilities {mu}(E) and diffusivities D(E) directly from the scattering operator. By carrying out this asymptotic expansion to higher order, we obtain the high frequency corrections to the drift velocity and diffusivity, and also the corrections due to gradients in the electric field. Remarkably, we find that Einsteins's relation is still satisfied, even with these corrections. The new diffusion-drift equations, together with Poissons' equation for the electric field, form the high-field semiconductor equations, which can be expected to be accurate regardless of the strength of the electric fields within the semiconductor. In addition, our analysis determines the entire momentum distribution of the particles, so we derive a very accurate first moment model for semi-conductors by substituting the asymptotically-correct distribution back into the Boltzmann equation and taking moments.

  12. High-Gain High-Field Fusion Plasma

    Science.gov (United States)

    Li, Ge

    2015-01-01

    A Faraday wheel (FW)—an electric generator of constant electrical polarity that produces huge currents—could be implemented in an existing tokamak to study high-gain high-field (HGHF) fusion plasma, such as the Experimental Advanced Superconducting Tokamak (EAST). HGHF plasma can be realized in EAST by updating its pulsed-power system to compress plasma in two steps by induction fields; high gains of the Lawson trinity parameter and fusion power are both predicted by formulating the HGHF plasma. Both gain rates are faster than the decrease rate of the plasma volume. The formulation is checked by earlier ATC tests. Good agreement between theory and tests indicates that scaling to over 10 T at EAST may be possible by two-step compressions with a compression ratio of the minor radius of up to 3. These results point to a quick new path of fusion plasma study, i.e., simulating the Sun by EAST. PMID:26507314

  13. Generation of high-field narrowband terahertz radiation by counterpropagating plasma wakes

    CERN Document Server

    Timofeev, I V; Volchok, E P

    2016-01-01

    It is found that nonlinear interaction of plasma wakefields driven by counterpropagating laser or particle beams can efficiently generate high-power electromagnetic radiation at the second harmonic of the plasma frequency. Using a simple analytical theory and particle-in-cell simulations, we show that this phenomenon can be attractive for producing high-field ($\\sim 10$ MV/cm) narrowband terahertz pulses with the gigawatt power level and millijoule energy content.

  14. High field superconductor development and understanding

    Energy Technology Data Exchange (ETDEWEB)

    Larbalestier, David C. [Florida State Univ., Tallahassee, FL (United States); Lee, Peter J. [Florida State Univ., Tallahassee, FL (United States); Tarantini, Chiara [Florida State Univ., Tallahassee, FL (United States)

    2014-09-28

    All present circular accelerators use superconducting magnets to bend and to focus the particle beams. The most powerful of these machines is the large hadron collider (LHC) at CERN. The main ring dipole magnets of the LHC are made from Nb-Ti but, as the machine is upgraded to higher luminosity, more powerful magnets made of Nb3Sn will be required. Our work addresses how to make the Nb3Sn conductors more effective and more suitable for use in the LHC. The most important property of the superconducting conductor used for an accelerator magnet is that it must have very high critical current density, the property that allows the generation of high magnetic fields in small spaces. Nb3Sn is the original high field superconductor, the material which was discovered in 1960 to allow a high current density in the field of about 9 T. For the high luminosity upgrade of the LHC, much higher current densities in fields of about 12 Tesla will be required. The critical value of the current density is of order 2600 A/mm2 in a field of 12 Tesla. But there are very important secondary factors that complicate the attainment of this critical current density. The first is that the effective filament diameter must be no larger than about 40 µm. The second factor is that 50% of the cross-section of the Nb3Sn conductor that is pure copper must be protected from any poisoning by any Sn leakage through the diffusion barrier that protects the package of niobium and tin from which the Nb3Sn is formed by a high temperature reaction. These three, somewhat conflicting requirements, mean that optimization of the conductor is complex. The work described in this contract report addresses these conflicting requirements. They show that very sophisticated characterizations can uncover the way to satisfy all 3 requirements and they also suggest that the ultimate optimization of Nb3Sn is still not yet in sight

  15. EPR tooth dosimetry of SNTS area inhabitants

    Energy Technology Data Exchange (ETDEWEB)

    Sholom, Sergey [Scientific Center for Radiation Medicine, Melnikova str., 53, Kiev (Ukraine); Desrosiers, Marc [Ionizing Radiation Division, National Institute of Standards and Technology, Gaithersburg, MD (United States); Bouville, Andre; Luckyanov, Nicholas [Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, 6120 Executive Boulevard, Bethesda, MD (United States); Chumak, Vadim [Scientific Center for Radiation Medicine, Melnikova str., 53, Kiev (Ukraine); Simon, Steven L. [Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, 6120 Executive Boulevard, Bethesda, MD (United States)], E-mail: ssimon@mail.nih.gov

    2007-07-15

    The determination of external dose to teeth of inhabitants of settlements near the Semipalatinsk Nuclear Test Site (SNTS) was conducted using the EPR dosimetry technique to assess radiation doses associated with exposure to radioactive fallout from the test site. In this study, tooth doses have been reconstructed for 103 persons with all studied teeth having been formed before the first nuclear test in 1949. Doses above those received from natural background radiation, termed 'accident doses', were found to lie in the range from zero to approximately 2 Gy, with one exception, a dose for one person from Semipalatinsk city was approximately 9 Gy. The variability of reconstructed doses within each of the settlements demonstrated heterogeneity of the deposited fallout as well as variations in lifestyle. The village mean external gamma doses for residents of nine settlements were in the range from a few tens of mGy to approximately 100 mGy.

  16. Asymmetric EPR entanglement in continuous variable systems

    CERN Document Server

    Wagner, Katherine; Armstrong, Seiji; Morizur, Jean-Francois; Lam, Ping Koy; Bachor, Hans-Albert

    2012-01-01

    Continuous variable entanglement can be produced in nonlinear systems or via interference of squeezed states. In many of optical systems, such as parametric down conversion or interference of optical squeezed states, production of two perfectly symmetric subsystems is usually used for demonstrating the existence of entanglement. This symmetry simplifies the description of the concept of entanglement. However, asymmetry in entanglement may arise naturally in a real experiment, or be intentionally introduced in a given quantum information protocol. These asymmetries can emerge from having the output beams experience different losses and environmental contamination, or from the availability of non-identical input quantum states in quantum communication protocols. In this paper, we present a visualisation of entanglement using quadrature amplitude plots of the twin beams. We quantitatively discuss the strength of asymmetric entanglement using EPR and inseparability criteria and theoretically show that the optimal...

  17. Identification of gamma-irradiated fruit juices by EPR spectroscopy

    Science.gov (United States)

    Aleksieva, K. I.; Dimov, K. G.; Yordanov, N. D.

    2014-10-01

    The results of electron paramagnetic resonance (EPR) study on commercially available juices from various fruits and different fruit contents: 25%, 40%, 50%, and 100%, homemade juices, nectars and concentrated fruit syrups, before and after gamma-irradiation are reported. In order to remove water from non- and irradiated samples all juices and nectars were filtered; the solid residue was washed with alcohol and dried at room temperature. Only concentrated fruit syrups were dried for 60 min at 40 °C in a standard laboratory oven. All samples under study show a singlet EPR line with g=2.0025 before irradiation with exception of concentrated fruit syrups, which are EPR silent. Irradiation of juice samples gives rise to complex EPR spectra which gradually transferred to "cellulose-like" EPR spectrum from 25% to 100% fruit content. Concentrated fruit syrups show typical "sugar-like" spectra due to added saccharides. All EPR spectra are characteristic and can prove radiation treatment. The fading kinetics of radiation-induced EPR signals were studied for a period of 60 days after irradiation.

  18. Applications of high dielectric materials in high field magnetic resonance

    Science.gov (United States)

    Haines, Kristina Noel

    At high magnetic fields, radiation losses, wavelength effects, self-resonance, and the high resistance of components all contribute to losses in conventional RF MRI coil designs. The hypothesis tested here is that these problems can be combated by the use of high permittivity ceramic materials at high fields. High permittivity ceramic dielectric resonators create strong uniform magnetic fields in compact structures at high frequencies and can potentially solve some of the challenges of high field coil design. In this study NMR probes were constructed for operation at 600 MHz (14.1 Tesla) and 900 MHz (21.1 Tesla) using inductively fed CaTiO3 (relative permittivity of 156-166) cylindrical hollow bore dielectric resonators. The designs showed the electric field is largely confined to the dielectric itself, with near zero values in the hollow bore, which accommodates the sample. The 600 MHz probe has an unmatched Q value greater than 2000. Experimental and simulation mapping of the RF field show good agreement, with the ceramic resonator giving a pulse width approximately 25% less than a loop gap resonator of similar inner dimensions. High resolution images, with voxel dimensions less than 50 microm3, have been acquired from fixed zebrafish samples, showing excellent delineation of several fine structures. The 900 MHz probe has an unmatched Q value of 940 and shows Q performance five times better than Alderman-Grant and loop-gap resonators of similar dimensions. High resolution images were acquired of an excised mouse spinal cord (25 microm 3) and an excised rat soleus muscle (20 microm3). The spatial distribution of electromagnetic fields within the human body can be tailored using external dielectric materials. Here, a new material is introduced with high dielectric constant and low background MRI signal. The material is based upon metal titanates, which can be made into geometrically formable suspensions in de-ionized water. The suspension's material properties are

  19. Pulse on Pulse

    DEFF Research Database (Denmark)

    Schmidt, Ulrik; Carlson, Merete

    2012-01-01

    Pulse on Pulse” investigates the relation between signifying processes and non-signifying material dynamism in the installation Pulse Room (2006-) by Mexican Canadian artist Rafael Lozano-Hemmer. In Pulse Room the sense of pulse is ambiguous. Biorhythms are transmitted from the pulsing energy...... and pulsating ‘room’. Hence, the visitors in Pulse Room are invited into a complex scenario that continuously oscillates between various aspects of signification (the light bulbs representing individual lives; the pulse itself as the symbolic ‘rhythm of life’) and instants of pure material processuality...... a multilayered sense of time and space that is central to the sensory experience of Pulse Room as a whole. Pulse Room is, at the very same time, an anthropomorfized archive of a past intimacy and an all-encompassing immersive environment modulating continuously in real space-time....

  20. Comparing continuous wave progressive saturation EPR and time domain saturation recovery EPR over the entire motional range of nitroxide spin labels.

    Science.gov (United States)

    Nielsen, Robert D; Canaan, Stephane; Gladden, James A; Gelb, Michael H; Mailer, Colin; Robinson, Bruce H

    2004-07-01

    The measurement of spin-lattice relaxation rates from spin labels, such as nitroxides, in the presence and absence of spin relaxants provides information that is useful for determining biomolecular properties such as nucleic acid dynamics and the interaction of proteins with membranes. We compare X-band continuous wave (CW) and pulsed or time domain (TD) EPR methods for obtaining spin-lattice relaxation rates of spin labels across the entire range of rotational motion to which relaxation rates are sensitive. Model nitroxides and spin-labeled biological species are used to illustrate the potential complications that arise in extracting relaxation data under conditions typical to biological experiments. The effect of super hyperfine (SHF) structure is investigated for both CW and TD spectra. First and second harmonic absorption and dispersion CW spectra of the nitroxide spin label, TEMPOL, are all fit simultaneously to a model of SHF structure over a range of microwave amplitudes. The CW spectra are novel because all harmonics and microwave phases were acquired simultaneously using our homebuilt CW/TD spectrometer. The effect of the SHF structure on the pulsed free induction decay (FID) and pulsed saturation recovery spectrum is shown for both protonated and deuterated TEMPOL. We present novel pulsed saturation recovery measurements on biological molecules, including spin-lattice relaxation rates of spin-labeled proteins and spin-labeled double-stranded DNA. The impact of structure and dynamics on relaxation rates are discussed in the context of each of these examples. Collisional relaxation rates with oxygen and transition metal paramagnetic relaxants are extracted using both continuous wave and time domain methods. The extent of the errors inherent in the CW method and the advantages of pulsed methods for unambiguously measuring collisional relaxation rates are discussed. Spin-lattice relaxation rates, determined by both CW and pulsed methods, are used to determine

  1. Software for evaluation of EPR-dosimetry performance.

    Science.gov (United States)

    Shishkina, E A; Timofeev, Yu S; Ivanov, D V

    2014-06-01

    Electron paramagnetic resonance (EPR) with tooth enamel is a method extensively used for retrospective external dosimetry. Different research groups apply different equipment, sample preparation procedures and spectrum processing algorithms for EPR dosimetry. A uniform algorithm for description and comparison of performances was designed and implemented in a new computer code. The aim of the paper is to introduce the new software 'EPR-dosimetry performance'. The computer code is a user-friendly tool for providing a full description of method-specific capabilities of EPR tooth dosimetry, from metrological characteristics to practical limitations in applications. The software designed for scientists and engineers has several applications, including support of method calibration by evaluation of calibration parameters, evaluation of critical value and detection limit for registration of radiation-induced signal amplitude, estimation of critical value and detection limit for dose evaluation, estimation of minimal detectable value for anthropogenic dose assessment and description of method uncertainty.

  2. EPR detection of foods preserved with ionizing radiation

    Science.gov (United States)

    Stachowicz, W.; Burlinska, G.; Michalik, J.

    1998-06-01

    The applicability of the epr technique for the detection of dried vegetables, mushrooms, some spices, flavour additives and some condiments preserved with ionizing radiation is discussed. The epr signals recorded after exposure to gamma rays and to beams of 10 MeV electrons from linac are stable, intense and specific enough as compared with those observed with nonirradiated samples and could be used for the detection of irradiation. However, stability of radiation induced epr signals produced in these foods depends on storage condition. No differences in shapes (spectral parameters) and intensities of the epr spectra recorded with samples exposed to the same doses of gamma rays ( 60Co) and 10 MeV electrons were observed

  3. Most advanced HTP fuel assembly design for EPR

    Energy Technology Data Exchange (ETDEWEB)

    Francillon, Eric [AREVA - Framatome ANP, 10 rue Juliette Recamier - 69456 Lyon Cedex 06 (France); Kiehlmann, Horst-Dieter [AREVA - Framatome ANP GmbH, P.O. Box 3220, 91050 Erlangen (Germany)

    2006-07-01

    End 2003, the Finnish electricity utility Teollisuuden Voima Oy (TVO) signed the contract for building an EPR in Olkiluoto (Finland). Mid 2004, the French electricity utility EDF selected an EPR to be built in France. In 2005, Framatome ANP, an AREVA and Siemens company, announced that they will be pursuing a design certification in the U.S. The EPR development is based on the latest PWR product lines of former Framatome (N4) and Siemens Nuklear (Konvoi). As an introductory part, different aspects of the EPR core characteristics connected to fuel assembly design are presented. It includes means of ensuring reactivity control like hybrid AIC/B4C control rod absorbers and gadolinium as burnable absorber integrated in fuel rods, and specific options for in-core instrumentation, such as Aeroball type instrumentation. Then the design requirements for the EPR fuel assembly are presented in term of very high burnup capacity, rod cladding and fuel assembly reliability. Framatome ANP fuel assembly product characteristics meeting these requirements are then described. EPR fuel assembly design characteristics benefit from the experience feedback of the latest fuel assembly products designed within Framatome ANP, leading to resistance to assembly deformation, high fuel rod restraint and prevention of handling hazards. EPR fuel assembly design features the best components composing the cornerstones of the upgraded family of fuel assemblies that FRAMATOME ANP proposes today. This family is based on a set of common characteristics and associated features, which include the HMP grid as bottom end spacer, the MONOBLOC guide tube and the Robust FUELGUARD as lower tie plate, the use of the M5 Alloy, as cladding and structure material. This fully re-crystallized, ternary Zr-Nb-O alloy produces radically improved in-reactor corrosion, very low hydrogen uptake and growth and an excellent creep behavior, which are described there. EPR fuel assembly description also includes fuel rod

  4. EPR and NMR studies of amorphous aluminum borates

    NARCIS (Netherlands)

    Simon, S.; Pol, A. van der; Reijerse, E.J.; Kentgens, A.P.M.; Moorsel, G.J.M.P. van; Boer, E. de

    1994-01-01

    Amorphous aluminium borates, Al2(1–x)B2xO3 with O [less-than-or-eq]x[less-than-or-eq] 0.5, prepared from mixtures of aluminium nitrate, boric acid and glycerol, have been studied by EPR and 27Al MASNMR as a function of composition and heat-treatment temperature (Tt[less-than-or-eq] 860 °C). EPR stud

  5. EPR and NMR studies of amorphous aluminum borates

    NARCIS (Netherlands)

    Simon, S.; Pol, A. van der; Reijerse, E.J.; Kentgens, A.P.M.; Moorsel, G.J.M.P. van; Boer, E. de

    1994-01-01

    Amorphous aluminium borates, Al2(1–x)B2xO3 with O [less-than-or-eq]x[less-than-or-eq] 0.5, prepared from mixtures of aluminium nitrate, boric acid and glycerol, have been studied by EPR and 27Al MASNMR as a function of composition and heat-treatment temperature (Tt[less-than-or-eq] 860 °C). EPR stud

  6. Study of metalloproteins using continuous wave electron paramagnetic resonance (EPR).

    Science.gov (United States)

    Gambarelli, Serge; Maurel, Vincent

    2014-01-01

    Electron paramagnetic resonance (EPR) is an invaluable tool when studying systems with paramagnetic centers. It is a sensitive spectroscopic method, which can be used with dilute samples in aqueous buffer solutions. Here, we describe the basic procedure for recording an X-band EPR spectrum of a metalloprotein sample at low temperature. We also discuss basic optimization techniques to provide spectra with a high signal to noise ratio and minimum distortion.

  7. Lorentz symmetry breaking effects on relativistic EPR correlations

    Energy Technology Data Exchange (ETDEWEB)

    Belich, H. [Universidade Federal do Espirito Santo, Departamento de Fisica e Quimica, Vitoria, ES (Brazil); Furtado, C.; Bakke, K. [Universidade Federal da Paraiba, Departamento de Fisica, Caixa Postal 5008, Joao Pessoa, PB (Brazil)

    2015-09-15

    Lorentz symmetry breaking effects on relativistic EPR (Einstein-Podolsky-Rosen) correlations are discussed. From the modified Maxwell theory coupled to gravity, we establish a possible scenario of the Lorentz symmetry violation and write an effective metric for the Minkowski spacetime. Then we obtain the Wigner rotation angle via the Fermi-Walker transport of spinors and consider the WKB (Wentzel-Kramers-Brillouin) approximation in order to study the influence of Lorentz symmetry breaking effects on the relativistic EPR correlations. (orig.)

  8. Field-swept pulsed electron paramagnetic resonance of Cr{sup 3+}-doped ZBLAN fluoride glass

    Energy Technology Data Exchange (ETDEWEB)

    Drew, S.C. [School of Physics and Materials Engineering, Monash University, VIC (Australia)]. E-mail: simon.drew@spme.monash.edu.au; Pilbrow, J.R. [School of Physics and Materials Engineering, Monash University, VIC (Australia); Newman, P.J.; MacFarlane, D.R. [Department of Chemistry, Monash University, VIC (Australia)

    2001-10-07

    Field-swept pulsed electron paramagnetic resonance (EPR) spectra of a ZBLAN fluoride glass doped with a low concentration of Cr{sup 3+} are obtained using echo-detected EPR and hole-burning free induction decay detection. We review the utility of the pulsed EPR technique in generating field-swept EPR spectra, as well as some of the distorting effects that are peculiar to the pulsed detection method. The application of this technique to Cr{sup 3+}-doped ZBLAN reveals that much of the broad resonance extending from g{sup eff}=5.1 to g{sup eff}=1.97, characteristic of X-band continuous wave EPR of Cr{sup 3+} in glasses, is absent. We attribute this largely to the variation in nutation frequencies across the spectrum that result from sites possessing large fine structure interactions. The description of the spin dynamics of such sites is complicated and we discuss some possible approaches to the simulation of the pulsed EPR spectra. (author)

  9. EPC projects for EPR Flamanville 3 NPP

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, J.I.; Polo, J.; Aymerich, E.; Cubian, B. [Nuclear Generation Department, Iberdrola Ingenieria y Construccion, Avda. Manoteras 20, 28050 Madrid (Spain)

    2010-07-01

    IBERDROLA Ingenieria y Construccion is carrying out a handful of activities in the EPR Flamanville 3 -FA3 NPP- context since 2007 matching oriented to position the company in the emerging marketplace of new nuclear power plants Generation III+, whose expectation for the next years is highly promising. IBERDROLA Ingenieria y Construccion leads 5 EPC -Engineering, Procurement and Commissioning- projects for FA3 NPP from the Nuclear Island till Sea Water Pumping Station as follows: - Design, procurement. fabrication, installation and testing of 21 shell and tubes heat-exchangers for the nuclear island. 12 out of these 17 HXs are conventional and will be designed according to ASME BPV code Section VIII and have to comply with PED 97/23/CE and ESPN. The remaining 5 HXs are nuclear and will be designed according to ASME BPV code Section III and have also to comply with PED and ESPN. - Design, procurement, fabrication and assembly of 9 demineralizers for different plant systems. Three of these Important To Safety (IPS) equipments have been manufactured according with ASME VIII codes and six of them with EN 13445 code plus additional requirements to comply with PED and final client requirements for nuclear island. - Design, fabrication and installation of qualified travelling water screening filters. The equipments furnished will be two nuclear safety qualified filters and associated equipment (cleaning water system and control system). Additionally some auxiliary devices such as grids, automatic trash rakes and stop gates are included in the contract. - Engineering, procurement, fabrication, erection and commissioning for the condensate treatment plant. This system includes a demineralizer tank, 5 filters, reactive injection mixer, pneumatic and manual valves, piping and instrumentation and control systems. - Engineering, procurement erection and commissioning for the electro-chlorination plant to protect the IPS piping for Condensate Water System for FA3. This system

  10. EPR study on non- and gamma-irradiated herbal pills

    Energy Technology Data Exchange (ETDEWEB)

    Aleksieva, K., E-mail: katerina_bas@abv.b [Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Lagunov, O. [Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Dimov, K. [Institute of Cryobiology and Food Technologies, 1162 Sofia (Bulgaria); Yordanov, N.D. [Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria)

    2011-06-15

    The results of EPR studies on herbal pills of marigold, hawthorn, yarrow, common balm, tutsan, nettle and thyme before and after gamma-irradiation are reported. Before irradiation all samples exhibit one weak singlet EPR line with a g-factor of 2.0048{+-}0.0005. After irradiation herbal pills could be separated in two groups according to their EPR spectra. Radiation-induced free radicals in pills of marigold, yarrow, nettle, tutsan and thyme could be attributed mainly to saccharide excipients. Tablets of hawthorn and common balm show 'cellulose-like' EPR spectrum, superimposed on partly resolved carbohydrate spectrum, due to the active part (herb) and inulin, which is present in the pills as an excipient. Fading study of the radiation-induced EPR signals confirms that sugar radicals are more stable than cellulose species. The reported results show that the presence of characteristic EPR spectra of herbal pills due to excipients or active part can be used as unambiguous proof of radiation processing within 35 or more days after irradiation.

  11. EPR study on non- and gamma-irradiated herbal pills

    Science.gov (United States)

    Aleksieva, K.; Lagunov, O.; Dimov, K.; Yordanov, N. D.

    2011-06-01

    The results of EPR studies on herbal pills of marigold, hawthorn, yarrow, common balm, tutsan, nettle and thyme before and after gamma-irradiation are reported. Before irradiation all samples exhibit one weak singlet EPR line with a g-factor of 2.0048±0.0005. After irradiation herbal pills could be separated in two groups according to their EPR spectra. Radiation-induced free radicals in pills of marigold, yarrow, nettle, tutsan and thyme could be attributed mainly to saccharide excipients. Tablets of hawthorn and common balm show "cellulose-like" EPR spectrum, superimposed on partly resolved carbohydrate spectrum, due to the active part (herb) and inulin, which is present in the pills as an excipient. Fading study of the radiation-induced EPR signals confirms that sugar radicals are more stable than cellulose species. The reported results show that the presence of characteristic EPR spectra of herbal pills due to excipients or active part can be used as unambiguous proof of radiation processing within 35 or more days after irradiation.

  12. Pulse on Pulse

    DEFF Research Database (Denmark)

    Schmidt, Ulrik; Carlson, Merete

    2012-01-01

    and pulsating ‘room’. Hence, the visitors in Pulse Room are invited into a complex scenario that continuously oscillates between various aspects of signification (the light bulbs representing individual lives; the pulse itself as the symbolic ‘rhythm of life’) and instants of pure material processuality......“Pulse on Pulse” investigates the relation between signifying processes and non-signifying material dynamism in the installation Pulse Room (2006-) by Mexican Canadian artist Rafael Lozano-Hemmer. In Pulse Room the sense of pulse is ambiguous. Biorhythms are transmitted from the pulsing energy...... of the visitor’s beating heart to the blink of a fragile light bulb, thereby transforming each light bulb into a register of individual life. But at the same time the blinking light bulbs together produce a chaotically flickering light environment composed by various layers of repetitive rhythms, a vibrant...

  13. Methodological aspects of EPR dosimetry with teeth

    Energy Technology Data Exchange (ETDEWEB)

    Sholom, S.; Chumak, V. [Scientific Center for Radiation Medicine, Kiev (Ukraine)

    2001-07-01

    EPR dosimetry with tooth enamel is known today as one of the most reliable and accurate methods of retrospective dosimetry. In the present study a comprehensive analysis of influence of the major confounding factors (solar UV exposure and dental X-ray diagnostic procedures) on the accuracy of accidental dose reconstruction is given. In this analysis, the facts known from literature as well as own authors' results were considered. Among the latter it is worth to mention study of doses in enamel caused by X-ray diagnostic procedures as well as investigation of dose profiles in front teeth, which are most affected to solar radiation. As a main result, the variant of dosimetric technique is proposed. It comprises the optimal combination of strongest sides of existing techniques which allows to conduct routine reconstruction of accidental doses as low as few tens of mGy with errors of the same order of magnitude. The proposed technique is primarily destined for dosimetry of Chernobyl liquidators, but could be used for reconstruction of doses of other over-exposed categories. (orig.)

  14. Arbitrated Quantum Signature protocol using EPR pairs

    Directory of Open Access Journals (Sweden)

    Jun Zhang

    2012-11-01

    Full Text Available Arbitrated signature provides that the signatory signs a message with his private key by quantum cryptography, while the signature receiver verifies the signature with the arbitrator’s assistance. In this work, security analysis was given to the arbitrated quantum signature (AQS and results showed that the receiver Bob and the attacker can forge the signature. Then this paper gives a new quantum one-time pads encryption method, which is suit for the quantum signature. At last, a new AQS protocol using Einstein-Podoisky-Rosen (EPR pairs is proposed. By using of  quantum key distribution (QKD and new quantum one-time pads, the new scheme can resist Shor’s attack. The new scheme has following advantages: (1 The scheme reduces the complexity of implementation and provides a higher efficiency in transmission; (2 Compares with some AQS schemes, the scheme can avoid being disavowed by the receiver; (3 Compares with other AQS schemes, the scheme also guarantees the arbitrator cannot forge the signature and it also ensure the receiver and other attacker cannot forge the signature.

  15. Radiofrequency solutions in clinical high field magnetic resonance

    NARCIS (Netherlands)

    Andreychenko, A.|info:eu-repo/dai/nl/341697672

    2013-01-01

    Magnetic resonance imaging (MRI) and spectroscopy (MRS) benefit from the sensitivity gain at high field (≥7T). However, high field brings also certain challenges associated with growing frequency and spectral dispersion. Frequency growth results in degraded performance of large volume radiofrequency

  16. Electrochemical and EPR characterization of 1,4-dihydropyridines. Reactivity towards alkyl radicals.

    Science.gov (United States)

    Núñez-Vergara, Luis J; López-Alarcón, C; Navarrete-Encina, P A; Atria, A M; Camargo, C; Squella, J A

    2003-01-01

    This work reports the electrochemical oxidation of a series of three synthesized 4-substituted-1,4-dihydropyridine derivatives in different electrolytic media. Also, an EPR characterization of intermediates and the reactivity of derivatives towards ABAP-derived alkyl radicals are reported. Dynamic, differential pulse and cyclic voltammetry studies on a glassy carbon electrode showed an irreversible single-peak due to the oxidation of the 1,4-dihydropyridine (1,4-DHP) ring via 2-electrons to the corresponding pyridine derivative. Levich plots were linear in different media, indicating that the oxidation process is diffusion-controlled. Calculated diffusion coefficients did not exhibit significant differences between the derivatives in the same medium. The oxidation mechanism follows the general pathway (electron, H+, electron, H+) with formation of an unstable pyridinium radical. One-electron oxidation intermediate was confirmed with controlled potential electrolysis (CPE) and EPR experiments. On applying N-tert-butyl-alpha-phenylnitrone (PBN) and 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as the spin trap, these unstable radical intermediates from the oxidation of 1,4-DHP derivatives were intercepted. The final product of the CPE, i.e. pyridine derivative, was identified by GC-MS technique. Direct reactivity of the synthesized compounds towards alkyl radicals was demonstrated by UV-Vis. spectroscopy and GC-MS technique. Results indicate that these derivatives significantly react with the radicals, even compared with a well-known antioxidant drug such as nisoldipine.

  17. Generation of high-field narrowband terahertz radiation by counterpropagating plasma wakefields

    Science.gov (United States)

    Timofeev, I. V.; Annenkov, V. V.; Volchok, E. P.

    2017-10-01

    It is found that nonlinear interaction of plasma wakefields driven by counterpropagating laser or particle beams can efficiently generate high-power electromagnetic radiation at the second harmonic of the plasma frequency. Using a simple analytical theory and particle-in-cell simulations, we show that this phenomenon can be attractive for producing high-field ( ˜10 MV/cm) tunable terahertz radiation with a narrow line width. For laser drivers produced by existing petawatt-class systems, this nonlinear process opens the way to the generation of gigawatt, multi-millijoule terahertz pulses which are not presently available for any other generating schemes.

  18. High-Field Magnetization of the Pyrochlore Compound Gd2Ti2O7

    Science.gov (United States)

    Narumi, Yasuo; Kikkawa, Akiko; Katsumata, Koichi; Honda, Zentaro; Hagiwara, Masayuki; Kindo, Koichi

    2006-09-01

    High-field magnetization measurements have been preformed on a single crystal sample of the pyrochlore compound Gd2Ti2O7 using a pulse magnet in conjunction with a dilution refrigerator. The magnetization curve at 0.3 K reveals two magnetic phase transitions when the magnetic field is applied along b [111]. At temperatures slightly above TN, a magnetization plateau appears around 5 T and the magnetization increases again from about 15 T with a convex curvature. It is considered that this crossover is due to a competition among thermal fluctuations, short-range antiferromagnetic ordering and geometrical frustration.

  19. High-Field Faraday Effect of Tb-Doped Glass Above Paramagnetic Saturation

    Science.gov (United States)

    Chiba, Yoshiaki; Hori, Hidenobu; Yonenobu, Kenji; Yamagishi, Akio; Date, Muneyuki

    1987-08-01

    High-field Faraday effect is investigated in Tb-doped glass under a pulsed high magnetic field up to 40 tesla(T). The nonlinear Faraday effect due to saturation of the paramagnetic moment appears below about 20 T at 4.2 K. A considerably large Faraday rotation with the Verdet constant of -45.0 rad. T-1 m-1 is found above the paramagnetic saturation field, and this is explained by the field-induced level mixing in the multiplet levels.

  20. Saturation recovery EPR and ELDOR at W-band for spin labels

    Science.gov (United States)

    Froncisz, Wojciech; Camenisch, Theodore G.; Ratke, Joseph J.; Anderson, James R.; Subczynski, Witold K.; Strangeway, Robert A.; Sidabras, Jason W.; Hyde, James S.

    2008-08-01

    A reference arm W-band (94 GHz) microwave bridge with two sample-irradiation arms for saturation recovery (SR) EPR and ELDOR experiments is described. Frequencies in each arm are derived from 2 GHz synthesizers that have a common time-base and are translated to 94 GHz in steps of 33 and 59 GHz. Intended applications are to nitroxide radical spin labels and spin probes in the liquid phase. An enabling technology is the use of a W-band loop-gap resonator (LGR) [J.W. Sidabras, R.R. Mett, W. Froncisz, T.G. Camenisch, J.R. Anderson, J.S. Hyde, Multipurpose EPR loop-gap resonator and cylindrical TE 011 cavity for aqueous samples at 94 GHz, Rev. Sci. Instrum. 78 (2007) 034701]. The high efficiency parameter (8.2 GW -1/2 with sample) permits the saturating pump pulse level to be just 5 mW or less. Applications of SR EPR and ELDOR to the hydrophilic spin labels 3-carbamoyl-2,2,5,5-tetra-methyl-3-pyrroline-1-yloxyl (CTPO) and 2,2,6,6,-tetramethyl-4-piperidone-1-oxyl (TEMPONE) are described in detail. In the SR ELDOR experiment, nitrogen nuclear relaxation as well as Heisenberg exchange transfer saturation from pumped to observed hyperfine transitions. SR ELDOR was found to be an essential method for measurements of saturation transfer rates for small molecules such as TEMPONE. Free induction decay (FID) signals for small nitroxides at W-band are also reported. Results are compared with multifrequency measurements of T1e previously reported for these molecules in the range of 2-35 GHz [J.S. Hyde, J.-J. Yin, W.K. Subczynski, T.G. Camenisch, J.J. Ratke, W. Froncisz, Spin label EPR T 1 values using saturation recovery from 2 to 35 GHz. J. Phys. Chem. B 108 (2004) 9524-9529]. The values of T1e decrease at 94 GHz relative to values at 35 GHz.

  1. Accelerated dynamic EPR imaging using fast acquisition and compressive recovery

    Science.gov (United States)

    Ahmad, Rizwan; Samouilov, Alexandre; Zweier, Jay L.

    2016-12-01

    Electron paramagnetic resonance (EPR) allows quantitative imaging of tissue redox status, which provides important information about ischemic syndromes, cancer and other pathologies. For continuous wave EPR imaging, however, poor signal-to-noise ratio and low acquisition efficiency limit its ability to image dynamic processes in vivo including tissue redox, where conditions can change rapidly. Here, we present a data acquisition and processing framework that couples fast acquisition with compressive sensing-inspired image recovery to enable EPR-based redox imaging with high spatial and temporal resolutions. The fast acquisition (FA) allows collecting more, albeit noisier, projections in a given scan time. The composite regularization based processing method, called spatio-temporal adaptive recovery (STAR), not only exploits sparsity in multiple representations of the spatio-temporal image but also adaptively adjusts the regularization strength for each representation based on its inherent level of the sparsity. As a result, STAR adjusts to the disparity in the level of sparsity across multiple representations, without introducing any tuning parameter. Our simulation and phantom imaging studies indicate that a combination of fast acquisition and STAR (FASTAR) enables high-fidelity recovery of volumetric image series, with each volumetric image employing less than 10 s of scan. In addition to image fidelity, the time constants derived from FASTAR also match closely to the ground truth even when a small number of projections are used for recovery. This development will enhance the capability of EPR to study fast dynamic processes that cannot be investigated using existing EPR imaging techniques.

  2. High field terahertz emission from relativistic laser-driven plasma wakefields

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Zi-Yu, E-mail: Ziyu.Chen@uni-duesseldorf.de [Institut für Theoretische Physik I, Heinrich-Heine-Universität Düsseldorf, Düsseldorf 40225 (Germany); LSD, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621999 (China); Pukhov, Alexander [Institut für Theoretische Physik I, Heinrich-Heine-Universität Düsseldorf, Düsseldorf 40225 (Germany)

    2015-10-15

    We propose a method to generate high field terahertz (THz) radiation with peak strength of GV/cm level in the THz frequency gap range of 1–10 THz using a relativistic laser interaction with a gaseous plasma target. Due to the effect of local pump depletion, an initially Gaussian laser pulse undergoes leading edge erosion and eventually evolves to a state with leading edge being step function. Interacting with such a pulse, electrons gain transverse residual momentum and excite net transverse currents modulated by the relativistic plasma frequency. These currents give rise to the low frequency THz emission. We demonstrate this process with one and two dimensional particle-in-cell simulations.

  3. The Project for the New High Field Facility

    OpenAIRE

    Motokawa, M.

    1996-01-01

    Since High Field Laboratory for Superconducting Materials attached to Institute for Materials Research of Tohoku University started, 15 years has passed. We have had plenty of fruitful scientific and technological results not only in a field of superconductivity but also in areas of magnetism, semiconductors, organic conductors, chemical and biological materials and crystallography. The equipments in the Laboratory, however, are now getting aged and the available high field of 31 T obtained b...

  4. Modified-Bloch-equation description of EPR transient nutations and free induction decay in solids

    Energy Technology Data Exchange (ETDEWEB)

    Asadullina, N.Ya.; Asadullin, Ya.Ya. [Kazan State Technical University, Department of General Physics, Kazan (Russian Federation); Asadullin, T.Ya. [Kazan State Technical University, Department of General Physics, Kazan (Russian Federation). E-mail: atimur@physics.ktsu-kai.ru

    2001-04-09

    Based on the experimental work by Boscaino et al on the EPR transient nutations (TNs) and free induction decay (FID) in solids, we propose the modified Bloch equations (MBEs). In addition to the Tomita expression for power-dependent parameter T{sub 2u}, we give an original phenomenological expression for power-dependent parameter T{sub 2v} and tuning {delta}. Both analytical (in the form of a Torrey solution with these parameters) and numerical solutions of MBE are obtained for TN and for different FID regimes with very good agreement between theory and experiment. We also discuss the meaning and role of the instantaneous diffusion mechanism in the transient pulse experiments. (author)

  5. Retrospective dosimetry using EPR and TL techniques: a status report

    Energy Technology Data Exchange (ETDEWEB)

    Haskell, E.H.

    1996-12-31

    Methods of retrospective dosimetry, including luminescence and electron paramagnetic resonance spectroscopy (EPR), rely on measurement of accident dose absorbed by naturally occurring materials - ceramics in the case of both thermoluminescence (TL) and optically stimulated luminescence (OSL) and organic materials and bio- minerals in the case of EPR. Each of these methods relies on measurement of radiation defects resulting from accidental exposure. Since defects also result from natural sources of radiation over the lifetime of a sample, analysis is usually restricted to materials for which the natural dose may be determined and subtracted from the measured cumulative dose. Luminescence dating techniques rely heavily on an accurate assessment of cumulative dose from natural radiation sources, and dating research has provided us with the bulk of our knowledge in this area. Virtually all of the work on natural dose determination can be directly applied to retrospective techniques. With EPR techniques the cumulative dose from diagnostic x- rays is also of importance.

  6. EPR/Homotaurine: A possible dosimetry system for high doses

    Energy Technology Data Exchange (ETDEWEB)

    Maghraby, A., E-mail: maghrabism@yahoo.com [National Institute of Standards (NIS) - Radiation Dosimetry Department - Tersa st. 12211 Giza, P.O. Box 136 (Egypt); Salama, E. [Physics Department, Faculty of Science, Ain Shams University, 11566 Cairo (Egypt); Mansour, A. [National Center for Radiation Research and Technology, Atomic Energy Authority, Nasr City, Cairo (Egypt)

    2011-12-11

    An EPR investigation of radiation induced radicals in Homotaurine revealed that there are two types of radicals produced after exposure to gamma radiation ({sup 60}Co). EPR spectra were recorded and analyzed; also the microwave power saturation curves for both radicals were studied. The effect of change in modulation amplitude on peak-to-peak signal height and line width was investigated; this is in addition to the evaluation of energy dependence parameters compared to soft tissue and alanine dosimeters. Response of Homotaurine to different radiation doses (0.5 kGy-50 kGy) was studied and found to follow a linear relationship. Radiation induced radicals in Homotaurine persisted and showed a noticeable stability over 30 days following irradiation. It was found that Homotaurine possesses good dosimetric properties using EPR spectroscopy in high doses and is characterized by its simple spectrum.

  7. Identification and dosimetry of irradiated walnuts (Juglans regia) using EPR

    Science.gov (United States)

    Maghraby, A.; Salama, E.; Sami, A.; Mansour, A.; El-Sayed, M.

    2012-03-01

    Electron paramagnetic resonance (EPR) is an easy, fast, and reliable tool for identification of irradiated food. Untreated nuts may encounter hazards of carrying several pathogens or microbial contamination; walnuts are of specific importance due to their nutritional and medicinal values, and hence walnut processing via gamma irradiation is a necessary step. EPR was employed for the identification and dosimetry of Cs-137 gamma-irradiated walnuts (shells and kernels). Several important parameters were studied, such as spectral features, microwave power dependence of signal intensities, and short- and long-term time dependences. Responses of walnut shells and kernels to different radiation doses in the range 0-10 kGy were investigated. Results confirmed that EPR is a suitable tool for the identification and dosimetry of irradiated walnuts using either their shells or only kernels.

  8. EPR/Homotaurine: A possible dosimetry system for high doses

    Science.gov (United States)

    Maghraby, A.; Salama, E.; Mansour, A.

    2011-12-01

    An EPR investigation of radiation induced radicals in Homotaurine revealed that there are two types of radicals produced after exposure to gamma radiation (60Co). EPR spectra were recorded and analyzed; also the microwave power saturation curves for both radicals were studied. The effect of change in modulation amplitude on peak-to-peak signal height and line width was investigated; this is in addition to the evaluation of energy dependence parameters compared to soft tissue and alanine dosimeters. Response of Homotaurine to different radiation doses (0.5 kGy-50 kGy) was studied and found to follow a linear relationship. Radiation induced radicals in Homotaurine persisted and showed a noticeable stability over 30 days following irradiation. It was found that Homotaurine possesses good dosimetric properties using EPR spectroscopy in high doses and is characterized by its simple spectrum.

  9. ER=EPR, GHZ, and the Consistency of Quantum Measurements

    CERN Document Server

    Susskind, Leonard

    2014-01-01

    This paper illustrates various aspects of the ER=EPR conjecture.It begins with a brief heuristic argument, using the Ryu-Takayanagi correspondence, for why entanglement between black holes implies the existence of Einstein-Rosen bridges. The main part of the paper addresses a fundamental question: Is ER=EPR consistent with the standard postulates of quantum mechanics? Naively it seems to lead to an inconsistency between observations made on entangled systems by different observers. The resolution of the paradox lies in the properties of multiple black holes, entangled in the Greenberger-Horne-Zeilinger pattern. The last part of the paper is about entanglement as a resource for quantum communication. ER=EPR provides a way to visualize protocols like quantum teleportation. In some sense teleportation takes place through the wormhole, but as usual, classical communication is necessary to complete the protocol.

  10. ER=EPR, GHZ, and the consistency of quantum measurements

    Energy Technology Data Exchange (ETDEWEB)

    Susskind, Leonard [Stanford Institute for Theoretical Physics and Department of Physics, Stanford University, Stanford, CA (United States)

    2016-01-15

    This paper illustrates various aspects of the ER=EPR conjecture. It begins with a brief heuristic argument, using the Ryu-Takayanagi correspondence, for why entanglement between black holes implies the existence of Einstein-Rosen bridges. The main part of the paper addresses a fundamental question: Is ER=EPR consistent with the standard postulates of quantum mechanics? Naively it seems to lead to an inconsistency between observations made on entangled systems by different observers. The resolution of the paradox lies in the properties of multiple black holes, entangled in the Greenberger-Horne-Zeilinger pattern. The last part of the paper is about entanglement as a resource for quantum communication. ER=EPR provides a way to visualize protocols like quantum teleportation. In some sense teleportation takes place through the wormhole, but as usual, classical communication is necessary to complete the protocol. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Librational motion of spin-labeled lipids in high-cholesterol containing membranes from echo-detected EPR spectra.

    Science.gov (United States)

    Erilov, Denis A; Bartucci, Rosa; Guzzi, Rita; Marsh, Derek; Dzuba, Sergei A; Sportelli, Luigi

    2004-12-01

    Two-pulse, echo-detected (ED) electron paramagnetic resonance (EPR) spectroscopy was used to study the librational motions of spin-labeled lipids in membranes of dipalmitoylphosphatidylcholine + 50 mol % cholesterol. The temperature dependence, over the range 77-240 K, and the dependence on position of spin-labeling in the sn-2 chain (n=5, 7, 10, 12, and 14) of the phospholipid, were characterized in detail. The experimental ED-spectra were corrected for instantaneous spin diffusion arising from static spin-spin interactions, by using spectra recorded at 77 K, where motional contributions are negligible. Simulations according to a model of rapid, small-amplitude librations about an axis whose direction is randomly distributed are able to describe the experimental spectra. Calibrations, in terms of the amplitude-correlation time product, alpha2tauc, were constructed for diagnostic spectral line-height ratios at different echo delay times, and for relaxation spectra obtained from the ratio of ED-spectra recorded at two different echo delays. The librational amplitude, alpha2, was determined for a spin label at the 14-C position of the lipid chain from the partially motionally averaged hyperfine splitting in the conventional EPR spectra. The librational correlation time, tauc, which is deduced from combination of the conventional and ED-EPR results, lies in the subnanosecond regime and depends only weakly on temperature. The temperature dependence of the ED-EPR spectra arises mainly from an increase in librational amplitude with increasing temperature, and position down the lipid chain. A gradual transition takes place at higher temperatures, from a situation in which segmental torsional librations are cumulative, i.e., the contributions of the individual segments add up progressively upon going down the chain, to one of concerted motion only weakly dependent on chain position. Such librational motions are important for glass-like states and are generally relevant to

  12. Free radicals and antioxidants at a glance using EPR spectroscopy.

    Science.gov (United States)

    Spasojević, Ivan

    2011-01-01

    The delicate balance between the advantageous and detrimental effects of free radicals is one of the important aspects of human (patho)physiology. The controlled production of reactive oxygen and nitrogen species has an essential role in the regulation of various signaling switches. On the other hand, imbalanced generation of radicals is highly correlated with the pathogenesis of many diseases which require the application of selected antioxidants to regain the homeostasis. In the era of growing interest for redox processes, electron paramagnetic resonance (EPR) spectroscopy is arguably the best-suited technique for such research due to its ability to provide a unique insight into the world of free radicals and antioxidants. Herein, I present the principles of EPR spectroscopy and the applications of this method in assessing: (i) the oxidative status of biological systems, using endogenous long-lived free radicals (ascorbyl radical (Asc(•)), tocopheroxyl radical (TO(•)), melanin) as markers; (ii) the production of short-lived radicals (hydroxyl radical (OH(•)), superoxide radical anion (O(2)(•-)), sulfur- and carbon-centered radicals), which are implicated in both, oxidative stress and redox signaling; (iii) the metabolism of nitric oxide (NO(•)); (iv) the antioxidative properties of various drugs, compounds, and natural products; (v) other redox-relevant parameter. Besides giving a comprehensive survey of up-to-date literature, I also provide illustrative examples in sufficient detail to provide a means to exploit the potential of EPR in biochemical/physiological/medical research. The emphasis is on the features and characteristics (both positive and negative) relevant for EPR application in clinical sciences. My aim is to encourage fellow colleagues interested in free radicals and antioxidants to expand their base knowledge or methods used in their laboratories with data acquired by EPR or some of the EPR techniques outlined in this review, in order to

  13. The inner containment of an EPR trademark pressurized water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Ostermann, Dirk; Krumb, Christian; Wienand, Burkhard [AREVA GmbH, Offenbach (Germany)

    2014-08-15

    On February 12, 2014 the containment pressure and subsequent leak tightness tests on the containment of the Finnish Olkiluoto 3 EPR trademark reactor building were completed successfully. The containment of an EPR trademark pressurized water reactor consists of an outer containment to protect the reactor building against external hazards (such as airplane crash) and of an inner containment that is subjected to internal overpressure and high temperature in case of internal accidents. The current paper gives an overview of the containment structure, the design criteria, the validation by analyses and experiments and the containment pressure test.

  14. Resolving the EPR Paradox for the Case of entangled Photons

    CERN Document Server

    Muchowski, Eugen

    2016-01-01

    A system of two polarized photons in singlet state appears as being in one of two product states independent of any measurement. These states depend on the selected polarization angles. With the polarizers on either side perpendicular to each other, both photons pass the polarizers without any disturbance. Action at a distance is therefore not needed to explain the results of the measurements. In general, the elements of physical reality demanded by EPR are the polarization states of the two photons of the entangled pair. As these are local elements in the regions of space of the polarizers the EPR paradox for the case of entangled photons can be regarded as resolved.

  15. EPR studies of gamma-irradiated taurine single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Bulut, A. E-mail: abulut@samsun.omu.edu.tr; Karabulut, B.; Tapramaz, R.; Koeksal, F

    2000-04-01

    An EPR study of gamma-irradiated taurine [C{sub 2}H{sub 7}NO{sub 3}S] single crystal was carried out at room temperature. The EPR spectra were recorded in the three at mutually perpendicular planes. There are two magnetically distinct sites in monoclinic lattice. The principle values of g and hyperfine constants for both sites were calculated. The results have indicated the presence of {sup 32}SO{sup -}{sub 2} and {sup 33}SO{sup -}{sub 2} radicals. The hyperfine values of {sup 33}SO{sup -}{sub 2} radical were used to obtain O-S-O bond angle for both sites.

  16. Implementing a new EPR lineshape parameter for organic radicals in carbonaceous matter

    OpenAIRE

    Bourbin, Mathilde; Du, Yann Le; Binet, Laurent; Gourier, Didier

    2013-01-01

    Background Electron Paramagnetic Resonance (EPR) is a non-destructive, non-invasive technique useful for the characterization of organic moieties in primitive carbonaceous matter related to the origin of life. The classical EPR parameters are the peak-to-peak amplitude, the linewidth and the g factor; however, such parameters turn out not to suffice to fully determine a single EPR line. Results In this paper, we give the definition and practical implementation of a new EPR parameter based on ...

  17. High-field magnetization of Heusler compound Fe2Mn1 -xVxSi

    Science.gov (United States)

    Hiroi, Masahiko; Tazoko, Tomoya; Sano, Hiroaki; Shigeta, Iduru; Koyama, Keiichi; Kondo, Akihiro; Kindo, Koich; Manaka, Hirotaka; Terada, Norio

    2017-01-01

    Fe2MnSi exhibits a ferromagnetic transition at TC˜230 K and another transition to a phase with antiferromagnetic components at TA˜60 K. By substituting V for Mn, so as to obtain Fe2Mn1 -xVxSi , TA is revealed to decrease with x and then vanish around x ˜0.2 . In this study, the phase boundary of the transition at TA in the high-field range is found for 0 ≤x ≤0.15 with pulsed fields up to ˜70 T. The magnetization of Fe2Mn1 -xVxSi slowly increases even at the highest field of ˜70 T, though it occurs more gradually as x increases. We compare the magnetization for 0 ≤x ≤0.20 at 62 T with the Slater-Pauling rule, which holds when a Heusler compound is a half-metal, and find fairly good agreement. This suggests an intimate relation between the high-field phase and the half-metallic electronic structure, and that at the high-field limit the phase approaches the half-metallic state, which has been predicted by band-structure calculations.

  18. Development of high-pressure, high-field and multifrequency electron spin resonance system.

    Science.gov (United States)

    Sakurai, T; Taketani, A; Tomita, T; Okubo, S; Ohta, H; Uwatoko, Y

    2007-06-01

    The electron spin resonance (ESR) system which covers the magnetic field region up to 16 T, the quasicontinuous frequency region from 60 to 700 GHz, the temperature region from 1.8 to 4.2 K, and the hydrostatic pressure region up to 1.1 GPa has been developed. This is the first pulsed high-field and multifrequency ESR system with the pressure region over 1 GPa as far as we know. Transmission ESR spectra under hydrostatic pressure can be obtained by combining a piston-cylinder-type pressure cell and the pulsed magnetic field ESR apparatus. The pressure cell consists of a NiCrAl cylinder and sapphire or zirconia inner parts. The use of sapphire or zirconia as inner parts enables us to observe ESR under pressure because these inner parts have high transmittance for the electromagnetic wave with millimeter and submillimeter wavelengths. We have successfully applied this system for the pressure dependence measurements of an isolated spin system NiSnCl(6)6H(2)O up to 1.1 GPa. It was found that the single ion anisotropy parameter D of this compound strongly depends on pressure. The parameter D is approximately proportional to the pressure up to 0.75 GPa, and the relation between D and the pressure can be used for the pressure calibration of this high-field and high-pressure ESR system.

  19. Radicals as EPR probes of magnetization of gadolinium stearate Langmuir-Blodgett film

    DEFF Research Database (Denmark)

    Koksharov, Y.A.; Bykov, I.V.; Malakho, A.P.;

    2002-01-01

    In the present work we have applied the method of the EPR spin probes which allows performing simultaneously EPR and magnetization measurements to the investigation of magnetism of the Cid stearate Langmuir-Blodgett (LB) films. For this purpose we have prepared and studied by the EPR technique...

  20. Comparison of pulse sequences for R1-based electron paramagnetic resonance oxygen imaging

    Science.gov (United States)

    Epel, Boris; Halpern, Howard J.

    2015-05-01

    Electron paramagnetic resonance (EPR) spin-lattice relaxation (SLR) oxygen imaging has proven to be an indispensable tool for assessing oxygen partial pressure in live animals. EPR oxygen images show remarkable oxygen accuracy when combined with high precision and spatial resolution. Developing more effective means for obtaining SLR rates is of great practical, biological and medical importance. In this work we compared different pulse EPR imaging protocols and pulse sequences to establish advantages and areas of applicability for each method. Tests were performed using phantoms containing spin probes with oxygen concentrations relevant to in vivo oxymetry. We have found that for small animal size objects the inversion recovery sequence combined with the filtered backprojection reconstruction method delivers the best accuracy and precision. For large animals, in which large radio frequency energy deposition might be critical, free induction decay and three pulse stimulated echo sequences might find better practical usage.

  1. HIGH FIELD Q-SLOPE AND THE BAKING EFFECT

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, Gianluigi [JLAB

    2009-11-01

    The performance of SRF cavities made of bulk Nb at high fields (peak surface magnetic field greater than about 90 mT) is characterized by exponentially increasing RF losses (high-field Q-slope), in the absence of field emission, which are often mitigated by a low temperature (100-140 °C, 12-48h) baking. In this contribution, recent experimental results and phenomenological models to explain this effect will be briefly reviewed. New experimental results on the high-field Q-slope will be presented for cavities that had been heat treated at high temperature in the presence of a small partial pressure of nitrogen. Improvement of the cavity performances have been obtained, while surface analysis measurements on Nb samples treated with the cavities revealed significantly lower hydrogen concentration than for samples that followed standard cavity treatments.

  2. Can high fields save the tokamak? The challenge of steady-state operation for low cost compact reactors

    Science.gov (United States)

    Freidberg, Jeffrey; Dogra, Akshunna; Redman, William; Cerfon, Antoine

    2016-10-01

    The development of high field, high temperature superconductors is thought to be a game changer for the development of fusion power based on the tokamak concept. We test the validity of this assertion for pilot plant scale reactors (Q 10) for two different but related missions: pulsed operation and steady-state operation. Specifically, we derive a set of analytic criteria that determines the basic design parameters of a given fusion reactor mission. As expected there are far more constraints than degrees of freedom in any given design application. However, by defining the mission of the reactor under consideration, we have been able to determine the subset of constraints that drive the design, and calculate the values for the key parameters characterizing the tokamak. Our conclusions are as follows: 1) for pulsed reactors, high field leads to more compact designs and thus cheaper reactors - high B is the way to go; 2) steady-state reactors with H-mode like transport are large, even with high fields. The steady-state constraint is hard to satisfy in compact designs - high B helps but is not enough; 3) I-mode like transport, when combined with high fields, yields relatively compact steady-state reactors - why is there not more research on this favorable transport regime?

  3. Nonlinear Simulation of the Tooth Enamel Spectrum for EPR Dosimetry

    Science.gov (United States)

    Kirillov, V. A.; Dubovsky, S. V.

    2016-07-01

    Software was developed where initial EPR spectra of tooth enamel were deconvoluted based on nonlinear simulation, line shapes and signal amplitudes in the model initial spectrum were calculated, the regression coefficient was evaluated, and individual spectra were summed. Software validation demonstrated that doses calculated using it agreed excellently with the applied radiation doses and the doses reconstructed by the method of additive doses.

  4. Non-local common cause explanations for EPR

    CERN Document Server

    Egg, Matthias

    2013-01-01

    The paper argues that a causal explanation of the correlated outcomes of EPR-type experiments is desirable and possible. It shows how Bohmian mechanics and the GRW mass density theory offer such an explanation in terms of a non-local common cause.

  5. On the Measurement Problem and the EPR Paradox

    OpenAIRE

    Muchowski, Eugen

    2016-01-01

    After a polarization measurement with photons in singlet state we know for certain the photons were in the measured state prior to measurement. Photons in singlet state do therefore not exhibit action at a distance. The EPR paradox with entangled photons has been challenged. It was also shown why quantum mechanics infringes Bells inequality.

  6. Security of EPR-based Quantum Key Distribution

    CERN Document Server

    Inamori, H

    2000-01-01

    We propose a proof of the security of EPR-based quantum key distribution against enemies with unlimited computational power. The proof holds for a protocol using interactive error-reconciliation scheme. We assume in this paper that the legitimate parties receive a given number of single photon signals and that their measurement devices are perfect.

  7. High-Field Electron Paramagnetic Resonance and Density Functional Theory Study of Stable Organic Radicals in Lignin: Influence of the Extraction Process, Botanical Origin, and Protonation Reactions on the Radical g Tensor.

    Science.gov (United States)

    Bährle, Christian; Nick, Thomas U; Bennati, Marina; Jeschke, Gunnar; Vogel, Frédéric

    2015-06-18

    The radical concentrations and g factors of stable organic radicals in different lignin preparations were determined by X-band EPR at 9 GHz. We observed that the g factors of these radicals are largely determined by the extraction process and not by the botanical origin of the lignin. The parameter mostly influencing the g factor is the pH value during lignin extraction. This effect was studied in depth using high-field EPR spectroscopy at 263 GHz. We were able to determine the gxx, gyy, and gzz components of the g tensor of the stable organic radicals in lignin. With the enhanced resolution of high-field EPR, distinct radical species could be found in this complex polymer. The radical species are assigned to substituted o-semiquinone radicals and can exist in different protonation states SH3+, SH2, SH1-, and S2-. The proposed model structures are supported by DFT calculations. The g principal values of the proposed structure were all in reasonable agreement with the experiments.

  8. Multifrequency EPR study on freeze-dried fruits before and after X-ray irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Yordanov, N.D. [Laboratory EPR, Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria)]. E-mail: ndyepr@bas.bg; Aleksieva, K. [Laboratory EPR, Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Dimitrova, A. [Laboratory EPR, Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Georgieva, L. [Institute of Cryobiology and Food Technologies, 1162 Sofia (Bulgaria); Tzvetkova, E. [Institute of Cryobiology and Food Technologies, 1162 Sofia (Bulgaria)

    2006-09-15

    X-, K- and Q-band EPR studies on lyophilized whole pulp parts of blue plum, apricot, peach, melon as well as achens and pulp separately of strawberry before and after X-ray irradiation are reported. Before irradiation all samples show in X band a weak singlet EPR line with g=2.0030+/-0.0005, except melon, which is EPR silent. Immediately after irradiation all samples exhibit complex fruit-depending spectra, which decay with time and change to give, in ca. 50days, an asymmetric singlet EPR line with g=2.0041+/-0.0005. Only apricot pulp gave a typical ''sugar-like'' EPR spectrum. Singlet EPR lines recorded after irradiation in X -band are K- and Q-band resolved as typical anisotropic EPR spectra with g{sub ||}=2.0023+/-0.0003 and g{sub -}bar =2.0041+/-0.0005. In addition, K- and Q-band EPR spectra of all samples show a superposition with the six EPR lines of Mn{sup 2+} naturally present in the fruits. The saturation behavior of the EPR spectra of achens of lyophilized and fresh strawberry is also studied. The differences in g factors of samples before and after X-ray irradiation might be used for the identification of radiation processing of fruits in the case of pulp and the differences in the EPR saturation behavior might be used for the achens of strawberry.

  9. Understanding natural semiquinone radicals--multifrequency EPR and relativistic DFT studies of the structure of Hg(II) complexes.

    Science.gov (United States)

    Witwicki, Maciej; Jerzykiewicz, Maria; Ozarowski, Andrzej

    2015-01-01

    Multifrequency EPR spectroscopy and DFT calculations were used to investigate Hg(II) complexes with semiquinone radical ligands formed in a direct reaction between the metal ions and tannic acid (a polyphenol closely related to tannins). Because of the intricate structure of tannic acid a vast array of substituted phenolic compounds were tested to find a structural model mimicking its ability to react with Hg(II) ions. The components of the g matrix (the g tensor) determined from the high field (208 GHz) EPR spectra of the Hg(II) complexes with the radical ligands derived from tannic acid and from the model compounds were analogous, indicating a similar coordination mode in all the studied Hg(II) complexes. Since catechol (1,2-dihydroxybenzene) was the simplest compound undergoing the reaction with Hg(II) it was selected for DFT studies which were aimed at providing an insight into the structural properties of the investigated complexes. Various coordination numbers and different conformations and protonation states of the ligands were included in the theoretical analyses. g Matrices were computed for all the DFT optimized geometries. A good agreement between the theoretical and experimental values was observed only for the model with the Hg(II) ion tetracoordinated by two ligands, one of the ligands being monoprotonated with the unpaired electron mainly localized on it.

  10. High Field Seeking State Atom Laser and Properties of Flux

    Institute of Scientific and Technical Information of China (English)

    XIA Lin; XIONG Wei; YANG Fan; YI Lin; ZHOU Xiao-Ji; CHEN Xu-Zong

    2008-01-01

    We present an experimental study on the continuous atom laser. The experiments show that a high field seeking state atom laser with stable flux can be formed by increasing the strength of outcoupling before large density fluctuations appear. It is easy to obtain a long length or high speed output with this kind of atom laser.

  11. Survey of high field superconducting material for accelerator magnets

    Energy Technology Data Exchange (ETDEWEB)

    Scahlan, R.; Greene, A.F.; Suenaga, M.

    1986-05-01

    The high field superconductors which could be used in accelerator dipole magnets are surveyed, ranking these candidates with respect to ease of fabrication and cost as well as superconducting properties. Emphasis is on Nb/sub 3/Sn and NbTi. 27 refs., 2 figs. (LEW)

  12. High-temperature superconductors in high-field magnets

    NARCIS (Netherlands)

    Weijers, Hubertus Wilhelmus

    2009-01-01

    The properties of both BSCCO conductors and YBCO coated conductors and coils are studied to assess their applicability in high-field magnets. First, the magnetic field dependence of the critical current density in these HTS conductors is measured at 4.2 K in magnetic field conditions ranging from s

  13. Optimizing brain tumor resection. High-field interventional MR imaging.

    Science.gov (United States)

    Tummala, R P; Chu, R M; Liu, H; Truwit, C L; Hall, W A

    2001-11-01

    High-field strength iMRI guidance is an effective tool for brain tumor resection. Although its use lengthens the average time for a craniotomy, the reward is a more extensive tumor excision compared with conventional neurosurgery without an increased risk to the patient (Table 4). Although intraoperative patient transfer into and out of the magnet is cumbersome, the possibility for complete resection, especially for a low-grade glioma, makes the effort worthwhile. The cost and technical support required for this system presently limits its use to only a few sites worldwide. As with any technology, further refinements will make this system less expensive and more attainable. Practical consideration aside, high-field strength iMRI is presently [table: see text] the most effective tool available for brain tumor resection. Because of its novelty, future studies are necessary to determine if this technology lowers the incidence of and extends the duration to tumor recurrence as the preliminary data in children suggests. These are the ultimate measures of efficacy for any brain tumor treatment. Based on the rapid advancement of technology, will today's high-field strength interventional magnet become tomorrow's low-field system? Very high-field strength designs may improve diagnostic capabilities through higher resolution, but their interventional applications may be hindered by increased sensitivity for clinically insignificant abnormalities and decreased specificity for clinically relevant lesions. As new technology is developed, clinicians must continue to explore and refine the existing high-field strength iMRI to make it cost-effective and widely applicable.

  14. Coiled transmission line pulse generators

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, Kenneth Fox (Columbia, MO)

    2010-11-09

    Methods and apparatus are provided for fabricating and constructing solid dielectric "Coiled Transmission Line" pulse generators in radial or axial coiled geometries. The pour and cure fabrication process enables a wide variety of geometries and form factors. The volume between the conductors is filled with liquid blends of monomers, polymers, oligomers, and/or cross-linkers and dielectric powders; and then cured to form high field strength and high dielectric constant solid dielectric transmission lines that intrinsically produce ideal rectangular high voltage pulses when charged and switched into matched impedance loads. Voltage levels may be increased by Marx and/or Blumlein principles incorporating spark gap or, preferentially, solid state switches (such as optically triggered thyristors) which produce reliable, high repetition rate operation. Moreover, these Marxed pulse generators can be DC charged and do not require additional pulse forming circuitry, pulse forming lines, transformers, or an a high voltage spark gap output switch. The apparatus accommodates a wide range of voltages, impedances, pulse durations, pulse repetition rates, and duty cycles. The resulting mobile or flight platform friendly cylindrical geometric configuration is much more compact, light-weight, and robust than conventional linear geometries, or pulse generators constructed from conventional components. Installing additional circuitry may accommodate optional pulse shape improvements. The Coiled Transmission Lines can also be connected in parallel to decrease the impedance, or in series to increase the pulse length.

  15. Magnetic, high-field EPR studies and catalytic activity of Schiff base tetranuclear CuII2FeIII2 complexes obtained by direct synthesis.

    Science.gov (United States)

    Nesterova, Oksana V; Chygorin, Eduard N; Kokozay, Vladimir N; Bon, Volodymyr V; Omelchenko, Irina V; Shishkin, Oleg V; Titiš, Ján; Boča, Roman; Pombeiro, Armando J L; Ozarowski, Andrew

    2013-12-28

    Two novel heterometallic complexes [Cu2Fe2(HL(1))2(H2L(1))2]·10DMSO (1) and [Cu2Fe2(HL(2))2(H2L(2))2]·2DMF (2) have been prepared using the open-air reaction of copper powder, iron(II) chloride and DMSO (1) or DMF (2) solutions of the polydentate Schiff base (H4L(1), 1; H4L(2), 2) formed in situ from salicylaldehyde (1) or 5-bromo-salicylaldehyde (2) and tris(hydroxymethyl)aminomethane. Crystallographic analysis revealed that both compounds are based on the centrosymmetric tetranuclear core {Cu(II)2Fe(III)2(μ-O)6} where metal centres are joined by μ-O bridges from the deprotonated ligands forming a nonlinear chain-like arrangement. Variable-temperature (1.8-300 K) magnetic susceptibility measurements of 1 and 2 showed a decrease of the effective magnetic moment value at low temperature, indicative of antiferromagnetic coupling (JCu-Fe/hc = -10.2 cm(-1), JFe-Fe/hc = -10.5 cm(-1) in 1, JCu-Fe/hc = -10.5 cm(-1), JFe-Fe/hc = -8.93 cm(-1) in 2) between the magnetic centres in both compounds. They reveal an exceptionally high catalytic activity in the oxidation of cyclohexane with hydrogen peroxide under mild conditions, with the best observed yield/TON combined values of 36%/596 and 44%/1.1 × 10(3) for 1 and 2, respectively.

  16. Multifrequency EPR Spectroscopy: A Toolkit for the Characterization of Mono- and Di-nuclear Metal Ion Centers in Complex Biological Systems

    Science.gov (United States)

    Hanson, Graeme R.

    Metalloenzymes are ubiquitous in nature containing complex metal ion cofactors intimately involved in the enzymes' biological function. The application of multifrequency continuous wave and orientation selective pulsed EPR in conjunction with computer simulation and density functional theory calculations has proven to be a powerful toolkit for the geometric and electronic structural characterization of these metal ion cofactors in the resting enzyme, enzyme-substrate and -product complexes, which in turn provides a detailed understanding of the enzymes' catalytic mechanism. In this chapter, a brief description of the multifrequency EPR toolkit used to structurally (geometric and electronic) characterize metal ion binding sites in complex biological systems and its application in the structural characterization of (i) molybdenum containing enzymes and model complexes, (ii) mono- and di-nuclear copper(II) cyclic peptide complexes (marine and synthetic analogues) and (iii) dinuclear metal ion centers in purple acid phosphatases will be presented.

  17. EPR identification of defects responsible for thermoluminescence in Cu-doped lithium tetraborate (Li{sub 2}B{sub 4}O{sub 7}) crystals

    Energy Technology Data Exchange (ETDEWEB)

    Brant, A.T., E-mail: Adam.Brant.ctr@afit.edu [Department of Engineering Physics, Air Force Institute of Technology, Wright-Patterson Air Force Base, OH 45433 (United States); Buchanan, D.A.; McClory, J.W. [Department of Engineering Physics, Air Force Institute of Technology, Wright-Patterson Air Force Base, OH 45433 (United States); Dowben, P.A. [Department of Physics and Astronomy, Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588 (United States); Adamiv, V.T.; Burak, Ya.V. [Institute of Physical Optics, 23 Dragomanov St., Lviv 79005 (Ukraine); Halliburton, L.E. [Department of Physics, West Virginia University, Morgantown, WV 26505 (United States)

    2013-07-15

    Electron paramagnetic resonance (EPR) is used to identify the electron and hole traps responsible for thermoluminescence (TL) peaks occurring near 100 and 200 °C in copper-doped lithium tetraborate (Li{sub 2}B{sub 4}O{sub 7}) crystals. As-grown crystals have Cu{sup +} and Cu{sup 2+} ions substituting for lithium and have Cu{sup +} ions at interstitial sites. All of the substitutional Cu{sup 2+} ions in the as-grown crystals have an adjacent lithium vacancy and give rise to a distinct EPR spectrum. Exposure to ionizing radiation at room temperature produces a second and different Cu{sup 2+} EPR spectrum when a hole is trapped by substitutional Cu{sup +} ions that have no nearby defects. These two Cu{sup 2+} trapped-hole centers are referred to as Cu{sup 2+}-V{sub Li} and Cu{sub active}{sup 2+}, respectively. Also during the irradiation, two trapped-electron centers in the form of interstitial Cu{sup 0} atoms are produced when interstitial Cu{sup +} ions trap electrons. They are observed with EPR and are labeled Cu{sub A}{sup 0} and Cu{sub B}{sup 0}. When an irradiated crystal is warmed from 25 to 150 °C, the Cu{sub active}{sup 2+} centers have a partial decay step that correlates with the TL peak near 100 °C. The concentrations of Cu{sub A}{sup 0} and Cu{sub B}{sup 0} centers, however, increase as the crystal is heated through this range. As the crystal is further warmed between 150 and 250 °C, the EPR signals from the Cu{sub active}{sup 2+} hole centers and Cu{sub A}{sup 0} and Cu{sub B}{sup 0} electron centers decay simultaneously. This decay step correlates with the intense TL peak near 200 °C. -- Highlights: ► We use EPR to identify a Cu{sup 2+} center and two Cu{sup 0} defects in Cu-doped Li{sub 2}B{sub 4}O{sub 7}. ► These defects form when our crystal is irradiated with X-rays at room temperature. ► We also observe two above-room-temperature thermoluminescence (TL) peaks. ► A pulsed anneal experiment correlates the decay of the EPR signals to two

  18. On the origin of high-field magnetic white dwarfs

    CERN Document Server

    García-Berro, E; Lorén-Aguilar, P; Aznar-Siguán, G; Camacho, J; Külebi, B; Isern, J; Althaus, L G; Córsico, A H

    2012-01-01

    High-field magnetic white dwarfs have been long suspected to be the result of stellar mergers. However, the nature of the coalescing stars and the precise mechanism that produces the magnetic field are still unknown. Here we show that the hot, convective, differentially rotating corona present in the outer layers of the remnant of the merger of two degenerate cores is able to produce magnetic fields of the required strength that do not decay for long timescales. We also show, using an state-of-the-art Monte Carlo simulator, that the expected number of high-field magnetic white dwarfs produced in this way is consistent with that found in the solar neighborhood.

  19. High field superconductor development and understanding project, Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Larbalestier, David C.; Lee, Peter J.

    2009-07-15

    Over 25 years the Applied Superconductivity Center at the University of Wisconsin-Madison provided a vital technical resource to the High Energy Physics community covering development in superconducting strand for HEP accelerator magnet development. In particular the work of the group has been to develop the next generation of high field superconductors for high field application. Grad students Mike Naus, Chad Fischer, Arno Godeke and Matt Jewell improved our understanding of the microstructure and microchemistry of Nb3Sn and their impact on the physical and mechanical properties. The success of this work has led to the continued funding of this work at the ASC after it moved to the NHMFL and also to direct funding from BNL for some aspects of Nb3Sn cable evaluation.

  20. Kinetic measurements using EPR imaging with a modulated field gradient.

    Science.gov (United States)

    Herrling, Thomas; Fuchs, Jürgen; Groth, Norbert

    2002-01-01

    EPR imaging with modulated field gradient was applied for the investigation of fast diffusion processes. Three different imaging methods are possible: spectral-temporal, spatio-temporal, and spectral-spatial imaging. The time resolution is on the order of seconds and the spatial resolution is in the micrometer region. The efficiency of this imaging technique is demonstrated for the penetration of the spin probe Tempol in the skin of hairless mice biopsies. The skin is normally protected against the penetration of water soluble substances by the horny layer, a resistive thin lipophilic layer. Overcoming this horny layer for water soluble ingredients is one of the main practical problems for the topical application of pharmaceutics which could be investigated by EPR imaging. Different images represent the penetration behavior of the water soluble Tempol in the skin after treatment with the penetration enhancer DMSO (Dimethylsulfoxide) and after removing the horny layer.

  1. Kinetic Measurements Using EPR Imaging with a Modulated Field Gradient

    Science.gov (United States)

    Herrling, Thomas; Fuchs, Jürgen; Groth, Norbert

    2002-01-01

    EPR imaging with modulated field gradient was applied for the investigation of fast diffusion processes. Three different imaging methods are possible: spectral-temporal, spatio-temporal, and spectral-spatial imaging. The time resolution is on the order of seconds and the spatial resolution is in the micrometer region. The efficiency of this imaging technique is demonstrated for the penetration of the spin probe Tempol in the skin of hairless mice biopsies. The skin is normally protected against the penetration of water soluble substances by the horny layer, a resistive thin lipophilic layer. Overcoming this horny layer for water soluble ingredients is one of the main practical problems for the topical application of pharmaceutics which could be investigated by EPR imaging. Different images represent the penetration behavior of the water soluble Tempol in the skin after treatment with the penetration enhancer DMSO (Dimethylsulfoxide) and after removing the horny layer.

  2. Structured Reporting Method for ePR Generation

    Directory of Open Access Journals (Sweden)

    Arash Ebrahimi

    2007-08-01

    Full Text Available Appropriate electronic medical report-making soft-wares help physicians to personally generate records for paper printing and ePR access. Flat data-sheets with check-boxes that have been already used in traditional medical paper reports, do not satisfy today's physician demands for more professional reports."nAlternatively, Structured Reporting (SR as the modified version of flat check-box based reporting method is being selected. In this method, items are nested in a hieratical tree so that each reporting item includes several substitutions. Hence, computer generates professional sentences with logical pre-defined combination of selected items. In our work, on the basis of SR method, we provided solution for reporting of Endoscopy procedures that is accepted by several Gastroenterologists as a proper software. In addi-tion, successful results in generation of ePRs using SR are newly achieved in Cardiology.

  3. Belgian primary care EPR: assessment of nationwide routine data extraction.

    Science.gov (United States)

    De Clercq, Etienne; van Casteren, Viviane; Bossuyt, Nathalie; Goderis, Geert; Moreels, Sarah

    2014-01-01

    Starting in 2009, the first ever Belgian nationwide data collection network using routine data extracted from primary care EPR (upload method) has been built from scratch. The network also uses a manual web-based data collection method. This paper compares these two methods by analysing missing and most recent values for certain parameters. We collected data from 4954 practices, pertaining to 29,180 patients. Mean values for the most recent parameters were similar regardless of which data collection method was used. Many missing recent values (>46%) were found for all of the parameters when using the upload method. It seems that, in Belgium, uploading routine data from primary care EPR on a large scale is suitable and allows the collection of chronological retrospective data. However, the method still requires major, carefully controlled improvements.

  4. Total loss of AC power analysis for EPR reactor

    Energy Technology Data Exchange (ETDEWEB)

    Darnowski, Piotr, E-mail: piotr.darnowski@itc.pw.edu.pl [Warsaw University of Technology, Institute of Heat Engineering, Nowowiejska 21/25, 00-665 Warsaw (Poland); Skrzypek, Eleonora, E-mail: eleonora.skrzypek@ncbj.gov.pl [Warsaw University of Technology, Institute of Heat Engineering, Nowowiejska 21/25, 00-665 Warsaw (Poland); National Centre for Nuclear Research (NCBJ), A. Sołtana 7, 05-400 Otwock-Świerk (Poland); Mazgaj, Piotr, E-mail: piotr.mazgaj@itc.pw.edu.pl [Warsaw University of Technology, Institute of Heat Engineering, Nowowiejska 21/25, 00-665 Warsaw (Poland); Świrski, Konrad [Warsaw University of Technology, Institute of Heat Engineering, Nowowiejska 21/25, 00-665 Warsaw (Poland); Gandrille, Pascal [AREVA NP SAS, Tour AREVA, 1 place Jean Millier, 92084 Paris La Défense (France)

    2015-08-15

    Highlights: • Total loss of AC power (Station Blackout) was simulated for the EPR reactor model. • In-vessel phase of the accident is under consideration. • Comparison of MELCOR and MAAP results is presented. • MELCOR and MAAP results are comparable. - Abstract: In this paper the results of severe accident simulations for the EPR reactor in the case of loss of offsite power combined with total failure of all diesel generators (total loss of AC power) are presented. Calculations were performed with MELCOR 2.1 computer code for in-vessel phase of the accident. In this scenario, the unavailability of all offsite and onsite power sources and the lack of cooling leads directly to core degradation, material relocation to the lower plenum and rupture of the reactor pressure vessel. MELCOR results were compared qualitatively and quantitatively with MAAP4 code results and show a good agreement.

  5. The Chernobyl accident: EPR dosimetry on dental enamel of children

    Energy Technology Data Exchange (ETDEWEB)

    Gualtieri, G. E-mail: gianni@fismedw2.univaq.it; Colacicchi, S.; Sgattoni, R.; Giannoni, M

    2001-07-01

    The radiation dose on tooth enamel of children living close to Chernobyl has been evaluated by EPR. The sample preparation was reduced to a minimum of mechanical steps to remove a piece of enamel. A standard X-ray tube at low energy was used for additive irradiation. The filtration effect of facial soft tissue was taken into account. The radiation dose for a group of teeth slightly exceeds the annual dose, whereas for another group the dose very much exceeds the annual dose. Since the higher dose is found in teeth whose enamel have much lower EPR sensitivity to the radiation, it can be suggested that for these teeth the native signal could alter the evaluation of the smaller radiation signal.

  6. A sensitive EPR dosimetry system based on sulfamic acid

    Science.gov (United States)

    Maghraby, A.

    2007-08-01

    There is a need for a sensitive dosimeter using electron paramagnetic resonance spectroscopy (EPR) for use in medical applications, since with this method non-destructive read-out and dose archival could be achieved. Sulfamic acid as a possible detector substance was investigated before and after irradiation, its EPR spectra were recorded and analyzed, some dosimetric characteristics were studied: microwave power saturation behavior, the effect of modulation amplitude on peak-to-peak signal intensity and the line width. Energy-dependence parameters were compared to soft tissue and alanine, and the response to ionizing radiation was studied, also the decay behavior along 133 days after irradiation is presented. It is found that sulfamic acid possesses high-sensitivity and reasonable signal stability which may make it useful as a sensitive dosimeter for medical applications.

  7. The Chernobyl accident: EPR dosimetry on dental enamel of children.

    Science.gov (United States)

    Gualtieri, G; Colacicchi, S; Sgattoni, R; Giannoni, M

    2001-07-01

    The radiation dose on tooth enamel of children living close to Chernobyl has been evaluated by EPR. The sample preparation was reduced to a minimum of mechanical steps to remove a piece of enamel. A standard X-ray tube at low energy was used for additive irradiation. The filtration effect of facial soft tissue was taken into account. The radiation dose for a group of teeth slightly exceeds the annual dose, whereas for another group the dose very much exceeds the annual dose. Since the higher dose is found in teeth whose enamel have much lower EPR sensitivity to the radiation, it can be suggested that for these teeth the native signal could alter the evaluation of the smaller radiation signal.

  8. High-field magnetization of dilute rare earths in yttrium

    DEFF Research Database (Denmark)

    Touborg, P.; Høg, J.; Cock, G. J.;

    1974-01-01

    Magnetization measurements have been performed on single crystals of Y containing small amounts of Tb, Dy, or Er at 4.2 K in fields up to 295 × 105 A/m (370 kOe). Crystal-field and molecular-field parameters obtained from measurements of the initial susceptibility versus temperature give...... a satisfactory quantitative account of the high-field magnetization. This includes characteristic features due to the crossing and mixing of crystal-field levels....

  9. High field optical nonlinearity and the Kramers-Kronig relations.

    Science.gov (United States)

    Wahlstrand, J K; Cheng, Y-H; Milchberg, H M

    2012-09-14

    The nonlinear optical response to high fields is absolutely measured for the noble gas atoms He, Ne, Ar, Kr, and Xe. We find that the response is quadratic in the laser field magnitude up to the ionization threshold of each gas. Its size and quadratic dependence are well predicted by a Kramers-Kronig analysis employing known ionization probabilities, and the results are consistent with calculations using the time-dependent Schrödinger equation.

  10. High-field Magnet Development toward the High Luminosity LHC

    Energy Technology Data Exchange (ETDEWEB)

    Apollinari, Giorgio [Fermilab

    2014-07-01

    The upcoming Luminosity upgrade of the LHC (HL-LHC) will rely on the use of Accelerator Quality Nb3Sn Magnets which have been the focus of an intense R&D effort in the last decade. This contribution will describe the R&D and results of Nb3Sn Accelerator Quality High Field Magnets development efforts, with emphasis on the activities considered for the HL-LHC upgrades.

  11. Karl R. Popper, 1992: About the EPR controversy

    Science.gov (United States)

    Combourieu, Marie-Christine

    1992-10-01

    Sir K. R. Popper's experimental schemes challenge the Copenhagen interpretation of quantum theory, principally Heisenberg's indeterminacy relations and the EPR paradox. “The so-called Einstein-Podolsky-Rosen paradox is not a paradox. It is a theoretical statement in expectation of an interpretation,” says K. R. Popper in this interview. “My experiment ought to be a classical experiment. It is very simple and free from any additional assumption. It should really be done.”

  12. EPR study of spermine interaction with multilamellar phosphatidylcholine liposomes.

    Science.gov (United States)

    Momo, F; Wisniewska, A; Stevanato, R

    1995-11-22

    The interaction of spermine with egg-yolk phosphatidylcholine liposomes was investigated. The EPR spin labeling technique evidenced that spermine induces modifications of some membrane functions of biological interest like water permeability and is a possible modulator of diffusion processes for charged and polar molecules. The association constant for a hypothesized complex between spermine and the phosphate group of phosphatidylcholine was evaluated by enzymatic methods.

  13. EPR = ER, scattering amplitude and entanglement entropy change

    Energy Technology Data Exchange (ETDEWEB)

    Seki, Shigenori, E-mail: sigenori@hanyang.ac.kr [Research Institute for Natural Science, Hanyang University, Seoul 133-791 (Korea, Republic of); Sin, Sang-Jin, E-mail: sjsin@hanyang.ac.kr [Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2014-07-30

    We study the causal structure of the minimal surface of the four-gluon scattering, and find a world-sheet wormhole parametrized by Mandelstam variables, thereby demonstrate the EPR = ER relation for gluon scattering. We also propose that scattering amplitude is the change of the entanglement entropy by generalizing the holographic entanglement entropy of Ryu–Takayanagi to the case where two regions are divided in space–time.

  14. Copenhagen vs Everett, teleportation, and ER=EPR

    Energy Technology Data Exchange (ETDEWEB)

    Susskind, Leonard [Stanford Institute for Theoretical Physics and Department of Physics, Stanford University, Stanford, CA (United States)

    2016-06-15

    Quantum gravity may have as much to tell us about the foundations and interpretation of quantum mechanics as it does about gravity. The Copenhagen interpretation of quantum mechanics and Everett's Relative State Formulation are complementary descriptions which in a sense are dual to one another. My purpose here is to discuss this duality in the light of the of ER=EPR conjecture. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Very high field magnetization and AC susceptibility of native horse spleen ferritin

    Energy Technology Data Exchange (ETDEWEB)

    Guertin, R.P. [Department of Physics and Astronomy, Room 201, Science and Technology Center, Tufts University, Medford, MA 02155 (United States)]. E-mail: robert.guertin@tufts.edu; Harrison, N. [National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Zhou, Z.X. [MS6056, Oak Ridge National Laboratory, Oak Ridge, TN 37830 (United States); McCall, S. [Lawrence Livermore National Laboratory, PO Box 808, Livermore, CA 94551 (United States); Drymiotis, F. [Department of Physics and Astronomy, Clemson University, Clemson, SC 29634 (United States)

    2007-01-15

    The magnetization of native horse spleen ferritin protein is measured in pulsed magnetic fields to 55 T at T=1.52 K. The magnetization rises smoothly with negative curvature due to uncompensated Fe{sup 3+} spins and with a large high field slope due to the underlying antiferromagnetic ferritin core. Even at highest fields the magnetic moment is only {approx}4% of the saturation moment of the full complement of Fe{sup 3+} in the ferritin molecule. The AC magnetic susceptibility, {chi} {sub AC}(T,f), responding to the uncompensated spins, reaches a maximum near the superparamagnetic blocking temperature with the temperature of the maximum, T {sub M}, varying with excitation frequency, T {sub M} {sup -1} {alpha} log f for 10{<=}f{<=}10{sup 4} Hz.

  16. EPR and magnetism of the nanostructured natural carbonaceous material shungite

    Science.gov (United States)

    Augustyniak-Jabłokow, Maria Aldona; Yablokov, Yurii V.; Andrzejewski, Bartłomiej; Kempiński, Wojciech; Łoś, Szymon; Tadyszak, Krzysztof; Yablokov, Mikhail Y.; Zhikharev, Valentin A.

    2010-04-01

    The X-band EPR and magnetic susceptibility in the temperature range 4.2-300 K study of the shungite-I, natural nanostructured material from the deposit of Shunga are reported. Obtained results allow us to assign the EPR signal to conduction electrons, estimate their number, N P, and evaluate the Pauli paramagnetism contribution to shungite susceptibility. A small occupation (~5%) of the localized nonbonding π states in the zigzag edges of the open-ended graphene-like layers and/or on σ ( sp 2+ x ) orbitals in the curved parts of the shungite globules has been also revealed. The observed temperature dependence of the EPR linewidth can be explained by the earlier considered interaction of conduction π electrons with local phonon modes associated with the vibration of peripheral carbon atoms of the open zigzag-type edges and with peripheral carbon atoms cross-linking different nanostructures. The relaxation time T 2 and diffusion time T D are found to have comparable values (2.84 × 10-8 and 1.73 × 10-8 s at 5.2 K, respectively), and similar dependence on temperature. The magnetic measurements have revealed the suppression of orbital diamagnetism due to small amount of large enough fragments of the graphene layers.

  17. EPR investigation of some traditional oriental irradiated spices

    Science.gov (United States)

    Duliu, Octavian G.; Georgescu, Rodica; Ali, Shaban Ibrahim

    2007-06-01

    The 9.50 GHz electron paramagnetic resonance (EPR) spectra of unirradiated and 60Co γ-ray irradiated cardamom ( Elettaria cardamomum L. Maton, Zingiberaceae), ginger (( Zingiber officinale Rosc., Zingiberaceae), and saffron ( Crocus sativus L., Iridaceae) have been investigated at room temperature. All unirradiated spices presented a weak resonance line with g-factors around free-electron ones. After γ-ray irradiation at an absorbed dose of up to 11.3 kGy, the presence of EPR spectra whose amplitude increase monotonously with the absorbed dose has been noticed with all spices. A 100 °C isothermal annealing of 11.3 kGy irradiated samples has shown a differential reduction of amplitude of various components that compose initial spectra, but even after 3.6 h of thermal treatment, the remaining amplitude represents no less then 30% of the initial ones. The same peculiarities have been noticed after 83 days storage at room temperature but after 340 days storage at ambient conditions only irradiated ginger displays a weak signal that differs from those of unirradiated sample. All these factors could be taken into account in establishing at which extent the EPR is suitable to evidence any irradiation treatment applied to these spices.

  18. Tetrachloridocuprates(II—Synthesis and Electron Paramagnetic Resonance (EPR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Peter Strauch

    2012-02-01

    Full Text Available Ionic liquids (ILs on the basis of metal containing anions and/or cations are of interest for a variety of technical applications e.g., synthesis of particles, magnetic or thermochromic materials. We present the synthesis and the results of electron paramagnetic resonance (EPR spectroscopic analyses of a series of some new potential ionic liquids based on tetrachloridocuprates(II, [CuCl4]2−, with different sterically demanding cations: hexadecyltrimethylammonium 1, tetradecyltrimethylammonium 2, tetrabutylammonium 3 and benzyltriethylammonium 4. The cations in the new compounds were used to achieve a reasonable separation of the paramagnetic Cu(II ions for EPR spectroscopy. The EPR hyperfine structure was not resolved. This is due to the exchange broadening, resulting from still incomplete separation of the paramagnetic Cu(II centers. Nevertheless, the principal values of the electron Zeemann tensor (g║ and g┴ of the complexes could be determined. Even though the solid substances show slightly different colors, the UV/Vis spectra are nearly identical, indicating structural changes of the tetrachloridocuprate moieties between solid state and solution. The complexes have a promising potential e.g., as high temperature ionic liquids, as precursors for the formation of copper chloride particles or as catalytic paramagnetic ionic liquids.

  19. EPR measurements of fingernails in Q-band

    Energy Technology Data Exchange (ETDEWEB)

    Romanyukha, Alex, E-mail: Alexander.Romanyukha@med.navy.mil [Naval Dosimetry Center, Bethesda, MD (United States); Trompier, Francois [Institut de Radioprotection et de Surete Nucleaire, Fontenay-aux-Roses Cedex (France); Reyes, Ricardo A. [Uniformed Services University of the Health Sciences, Bethesda, MD (United States); Melanson, Mark A. [Armed Forces Radiobiology Research Institute, Bethesda, MD (United States)

    2011-09-15

    Results of a feasibility study for the use of the Q-band EPR measurements of fingernails are presented. Details of the first protocol developed for Q-band (34 GHz) EPR dose measurements in fingernails and preliminary results of a dosimetry study in comparison with the commonly-used X-band (9 GHz) are reported. It was found that 1-5 mg sample mass was sufficient for EPR measurements in fingernails in the Q-band, which is significantly less than the 15-30 mg needed for the X-band. This finding makes it possible to obtain sufficient fingernail sample for dose measurements, practically from every finger of any person. Another finding was that the spectral resolution of the mechanically-induced signal (MIS) and radiation-induced signal (RIS) in the Q-band was significantly better than in the X-band. The RIS and MIS in the Q-band spectrum have a more complex structure than in the X-band, which potentially offers the possibility to do dose measurements in fingernails without treatment and immediately after clipping. These findings and recent results related to fingernail dosimetry in the Q-band and its perspectives are discussed here.

  20. EPR investigation of some traditional oriental irradiated spices

    Energy Technology Data Exchange (ETDEWEB)

    Duliu, Octavian G. [University of Bucharest, Department of Atomic and Nuclear Physics, Magurele, C.P. MG-11, RO-077125 Bucharest (Romania)]. E-mail: duliu@pcnet.ro; Georgescu, Rodica [National Institute for Physics and Nuclear Engineering -Horia Hulubei, C.P. MG-6, RO-077125 Bucharest (Romania); Ali, Shaban Ibrahim [University of Bucharest, Department of Atomic and Nuclear Physics, Magurele, C.P. MG-11, RO-077125 Bucharest (Romania)

    2007-06-15

    The 9.50 GHz electron paramagnetic resonance (EPR) spectra of unirradiated and {sup 60}Co {gamma}-ray irradiated cardamom (Elettaria cardamomum L. Maton, Zingiberaceae), ginger ((Zingiber officinale Rosc., Zingiberaceae), and saffron (Crocus sativus L., Iridaceae) have been investigated at room temperature. All unirradiated spices presented a weak resonance line with g-factors around free-electron ones. After {gamma}-ray irradiation at an absorbed dose of up to 11.3 kGy, the presence of EPR spectra whose amplitude increase monotonously with the absorbed dose has been noticed with all spices. A 100 {sup o}C isothermal annealing of 11.3 kGy irradiated samples has shown a differential reduction of amplitude of various components that compose initial spectra, but even after 3.6 h of thermal treatment, the remaining amplitude represents no less then 30% of the initial ones. The same peculiarities have been noticed after 83 days storage at room temperature but after 340 days storage at ambient conditions only irradiated ginger displays a weak signal that differs from those of unirradiated sample. All these factors could be taken into account in establishing at which extent the EPR is suitable to evidence any irradiation treatment applied to these spices.

  1. TL, EPR and optical absorption in natural grossular crystal

    Energy Technology Data Exchange (ETDEWEB)

    Yauri, J.M. [Institute of Physics, University of Sao Paulo, Rua do Matao, Travessa R, 187, CEP 05508-900, Sao Paulo (Brazil); Department of Physics, University of San Agustin, Av. Independencia S/N, Arequipa (Peru); Cano, N.F. [Institute of Physics, University of Sao Paulo, Rua do Matao, Travessa R, 187, CEP 05508-900, Sao Paulo (Brazil)], E-mail: nilocano@dfn.if.usp.br; Watanabe, S. [Institute of Physics, University of Sao Paulo, Rua do Matao, Travessa R, 187, CEP 05508-900, Sao Paulo (Brazil)

    2008-10-15

    Grossular is one of six members of silicate Garnet group. Two samples GI and GII have been investigated concerning their luminescence thermally stimulated (TL). EPR and optical absorption and the measurements were carried out to find out whether or not same point defects are responsible for all three properties. Although X-rays diffraction analysis has shown that both GI and GII have practically the same crystal structure of a standard grossular crystal, they presented different behavior in many aspects. The TL glow curve shape, TL response to radiation dose, the effect of annealing at high temperatures before irradiation, the dependence of UV bleaching parameters on peak temperature, all of them differ going from GI to GII. The EPR signals around g=2.0 as well as at g=4.3 and 6.0 have much larger intensity in GI than in GII. Very high temperature (>800 deg. C) annealing causes large increase in the bulk background absorption in GI, however, only very little in GII. In the cases of EPR and optical absorption, the difference in their behavior can be attributed to Fe{sup 3+} ions; however, in the TL case one cannot and the cause was not found as yet.

  2. Peptide-membrane Interactions by Spin-labeling EPR

    Science.gov (United States)

    Smirnova, Tatyana I.; Smirnov, Alex I.

    2016-01-01

    Site-directed spin labeling (SDSL) in combination with Electron Paramagnetic Resonance (EPR) spectroscopy is a well-established method that has recently grown in popularity as an experimental technique, with multiple applications in protein and peptide science. The growth is driven by development of labeling strategies, as well as by considerable technical advances in the field, that are paralleled by an increased availability of EPR instrumentation. While the method requires an introduction of a paramagnetic probe at a well-defined position in a peptide sequence, it has been shown to be minimally destructive to the peptide structure and energetics of the peptide-membrane interactions. In this chapter, we describe basic approaches for using SDSL EPR spectroscopy to study interactions between small peptides and biological membranes or membrane mimetic systems. We focus on experimental approaches to quantify peptide-membrane binding, topology of bound peptides, and characterize peptide aggregation. Sample preparation protocols including spin-labeling methods and preparation of membrane mimetic systems are also described. PMID:26477253

  3. Prostate MR imaging at high-field strength: evolution or revolution?

    Energy Technology Data Exchange (ETDEWEB)

    Rouviere, Olivier; Lyonnet, Denis [Hopital E. Herriot, Department of Genitourinary Radiology, Lyon (France); Hartman, Robert P. [Mayo Clinic, Department of Diagnostic Radiology, Rochester, MN (United States)

    2006-02-01

    As 3 T MR scanners become more available, body imaging at high field strength is becoming the subject of intensive research. However, little has been published on prostate imaging at 3 T. Will high-field imaging dramatically increase our ability to depict and stage prostate cancer? This paper will address this question by reviewing the advantages and drawbacks of body imaging at 3 T and the current limitations of prostate imaging at 1.5 T, and by detailing the preliminary results of prostate 3 T MRI. Even if slight adjustments of imaging protocols are necessary for taking into account the changes in T1 and T2 relaxation times at 3 T, tissue contrast in T2-weighted (T2w) imaging seems similar at 1.5 T and 3 T. Therefore, significant improvement in cancer depiction in T2w imaging is not expected. However, increased spatial resolution due to increased signal-to-noise ratio (SNR) may improve the detection of minimal capsular invasion. Higher field strength should provide increased spectral and spatial resolution for spectroscopic imaging, but new pulse sequences will have to be designed for overcoming field inhomogeneities and citrate J-modulation issues. Finally, dynamic contrast-enhanced MRI is the method of imaging that is the most likely to benefit from the increased SNR, with a significantly better trade-off between temporal and spatial resolution. (orig.)

  4. Assessment of an alanine EPR dosimetry technique with enhanced precision and accuracy

    CERN Document Server

    Hayes, R B; Wieser, A; Romanyukha, A A; Hardy, B L; Barrus, J K

    2000-01-01

    Dose reconstruction in the course of a series of blind tests demonstrated that an accuracy of 10 mGy for low doses and 1% for high doses can be achieved using EPR spectroscopy. This was accomplished using a combination of methodologies including polynomial filtration of the EPR spectrum, dosimeter rotation during scanning, use of an EPR standard fixed into the resonator and subtraction of all nonradiogenic signals. Doses were reconstructed over the range of 0.01-1000 Gy using this compound spectral EPR analysis. This EPR technique, being equally applicable to fractionated doses (such as those delivered during multiple radiotherapy treatments), was verified to exhibit dose reciprocity. Irradiated alanine dosimeters which were stored exhibited compound spectral EPR signal fading of ca 3% over 9 months. All error estimates given in this paper are given at the 1 standard deviation level and unless otherwise specified do not account for uncertainties in source calibration.

  5. Public debate about the EPR nuclear power plant at Flamanville; Debat public sur la centrale nucleaire EPR a Flamanville

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    The project of building of he EPR reactor at Flamanville (Manche, France) has been submitted to the public debate. This document includes a presentation of the project and of the rules of the public debate, a synthesis of the file made by the prime contractor (EDF), a synthesis of the collective book of national actors concerned by the project (a group of associations for environment protection, Areva company, the ministries of economy and ecology, Global Chance, association of pro-nuclear ecologists (AEPN), 'Sortir du Nucleaire' (out-of nuclear) network, group of scientists for the information about nuclear (GSIEN), association for the promotion of the Flamanville site (Proflam), French nuclear energy society (SFEN) in association with 'Sauvons le Climat' (let's save climate), regional collective association 'EPR non merci, ni ailleurs, ni ici' (EPR, no thanks, neither elsewhere, nor here), NegaWatt), and 5 detailed books of actors: ACRO (association for the control of radioactivity in Western France), CFDT and CGT syndicates, the economic and social council of Basse Normandie region, and Proflam. (J.S.)

  6. Homogenous BSCCO-2212 Round Wires for Very High Field Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Scott Campbell

    2012-06-30

    The performance demands on modern particle accelerators generate a relentless push towards higher field magnets. In turn, advanced high field magnet development places increased demands on superconducting materials. Nb3Sn conductors have been used to achieve 16 T in a prototype dipole magnet and are thought to have the capability for {approx}18 T for accelerator magnets (primarily dipoles but also higher order multipole magnets). However there have been suggestions and proposals for such magnets higher than 20 T. The High Energy Physics Community (HEP) has identified important new physics opportunities that are enabled by extremely high field magnets: 20 to 50 T solenoids for muon cooling in a muon collider (impact: understanding of neutrinos and dark matter); and 20+ T dipoles and quadrupoles for high energy hadron colliders (impact: discovery reach far beyond present). This proposal addresses the latest SBIR solicitation that calls for grant applications that seek to develop new or improved superconducting wire technologies for magnets that operate at a minimum of 12 Tesla (T) field, with increases up to 15 to 20 T sought in the near future (three to five years). The long-term development of accelerator magnets with fields greater than 20 T will require superconducting wires having significantly better high-field properties than those possessed by current Nb{sub 3}Sn or other A15 based wires. Given the existing materials science base for Bi-2212 wire processing, we believe that Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} (Bi-2212) round wires can be produced in km-long piece lengths with properties suitable to meet both the near term and long term needs of the HEP community. The key advance will be the translation of this materials science base into a robust, high-yield wire technology. While the processing and application of A15 materials have advanced to a much higher level than those of the copper oxide-based, high T{sub c} (HTS) counterparts, the HTS materials have

  7. Explosive Nucleosynthesis Study Using Laser Driven γ-ray Pulses

    Directory of Open Access Journals (Sweden)

    Takehito Hayakawa

    2017-03-01

    Full Text Available We propose nuclear experiments using γ-ray pulses provided from high field plasma generated by high peak power laser. These γ-ray pulses have the excellent features of extremely short pulse, high intensity, and continuous energy distribution. These features are suitable for the study of explosive nucleosyntheses in novae and supernovae, such as the γ process and ν process. We discuss how to generate suitable γ-ray pulses and the nuclear astrophysics involved.

  8. In Vivo Imaging of Tissue Physiological Function using EPR Spectroscopy | NCI Technology Transfer Center | TTC

    Science.gov (United States)

    Electron paramagnetic resonance (EPR) is a technique for studying chemical species that have one or more unpaired electrons.  The current invention describes Echo-based Single Point Imaging (ESPI), a novel EPR image formation strategy that allows in vivo imaging of physiological function.  The National Cancer Institute's Radiation Biology Branch is seeking statements of capability or interest from parties interested in in-licensing an in vivo imaging using Electron paramagnetic resonance (EPR) to measure active oxygen species.

  9. T1 and susceptibility contrast at high fields

    Science.gov (United States)

    Neelavalli, Jaladhar

    Clinical imaging at high magnetic field strengths (≥ 3Tesla) is sought after primarily due to the increased signal strength available at these fields. This increased SNR can be used to perform: (a) high resolution imaging in the same time as at lower field strengths; (b) the same resolution imaging with much faster acquisition; and (c) functional MR imaging (fMRI), dynamic perfusion and diffusion imaging with increased sensitivity. However they are also associated with increased power deposition (SAR) due to increase in imaging frequency and longer T1 relaxation times. Longer T1s mean longer imaging times for generating good T1 contrast images. On the other hand for faster imaging, at high fields fast spin echo or magnetization prepared sequences are conventionally proposed which are, however, associated with high SAR values. Imaging with low SAR is more and more important as we move towards high fields and particularly for patients with metallic implants like pacemakers or deep brain stimulator. The SAR limit acceptable for these patients is much less than the limit acceptable for normal subjects. A new method is proposed for imaging at high fields with good contrast with simultaneous reduction in power deposition. Further, T1 based contrast optimization problem in FLASH imaging is considered for tissues with different T1s but same spin densities. The solution providing optimal imaging parameters is simplified for quick and easy computation in a clinical setting. The efficacy of the simplification is evaluated and practical limits under which the simplification can be applied are worked out. The phase difference due to variation in magnetic susceptibility property among biological tissues is another unique source of contrast which is different from the conventional T1, T2 and T2* contrast. This susceptibility based phase contrast has become more and more important at high fields, partly due to contrast generation issues due to longer T 1s and shorter T2s and

  10. Homogenous BSCCO-2212 Round Wires for Very High Field Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Scott Campbell

    2012-06-30

    The performance demands on modern particle accelerators generate a relentless push towards higher field magnets. In turn, advanced high field magnet development places increased demands on superconducting materials. Nb3Sn conductors have been used to achieve 16 T in a prototype dipole magnet and are thought to have the capability for {approx}18 T for accelerator magnets (primarily dipoles but also higher order multipole magnets). However there have been suggestions and proposals for such magnets higher than 20 T. The High Energy Physics Community (HEP) has identified important new physics opportunities that are enabled by extremely high field magnets: 20 to 50 T solenoids for muon cooling in a muon collider (impact: understanding of neutrinos and dark matter); and 20+ T dipoles and quadrupoles for high energy hadron colliders (impact: discovery reach far beyond present). This proposal addresses the latest SBIR solicitation that calls for grant applications that seek to develop new or improved superconducting wire technologies for magnets that operate at a minimum of 12 Tesla (T) field, with increases up to 15 to 20 T sought in the near future (three to five years). The long-term development of accelerator magnets with fields greater than 20 T will require superconducting wires having significantly better high-field properties than those possessed by current Nb{sub 3}Sn or other A15 based wires. Given the existing materials science base for Bi-2212 wire processing, we believe that Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} (Bi-2212) round wires can be produced in km-long piece lengths with properties suitable to meet both the near term and long term needs of the HEP community. The key advance will be the translation of this materials science base into a robust, high-yield wire technology. While the processing and application of A15 materials have advanced to a much higher level than those of the copper oxide-based, high T{sub c} (HTS) counterparts, the HTS materials have

  11. Magnetic resonance imaging and spectroscopy at ultra high fields

    Energy Technology Data Exchange (ETDEWEB)

    Neuberger, Thomas

    2009-06-23

    The goal of the work presented in this thesis was to explore the possibilities and limitations of MRI / MRS using an ultra high field of 17.6 tesla. A broad range of specific applications and MR methods, from MRI to MRSI and MRS were investigated. The main foci were on sodium magnetic resonance spectroscopic imaging of rodents, magnetic resonance spectroscopy of the mouse brain, and the detection of small amounts of iron labeled stem cells in the rat brain using MRI Sodium spectroscopic imaging was explored since it benefits tremendously from the high magnetic field. Due to the intrinsically low signal in vivo, originating from the low concentrations and short transverse relaxation times, only limited results have been achieved by other researchers until now. Results in the literature include studies conducted on large animals such as dogs to animals as small as rats. No studies performed on mice have been reported, despite the fact that the mouse is the most important laboratory animal due to the ready availability of transgenic strains. Hence, this study concentrated on sodium MRSI of small rodents, mostly mice (brain, heart, and kidney), and in the case of the brain on young rats. The second part of this work concentrated on proton magnetic resonance spectroscopy of the rodent brain. Due to the high magnetic field strength not only the increasing signal but also the extended spectral resolution was advantageous for such kind of studies. The difficulties/limitations of ultra high field MRS were also investigated. In the last part of the presented work detection limits of iron labeled stem cells in vivo using magnetic resonance imaging were explored. The studies provided very useful benchmarks for future researchers in terms of the number of labeled stem cells that are required for high-field MRI studies. Overall this work has shown many of the benefits and the areas that need special attention of ultra high fields in MR. Three topics in MRI, MRS and MRSI were

  12. High-field spin dynamics of antiferromagnetic quantum spin chains

    DEFF Research Database (Denmark)

    Enderle, M.; Regnault, L.P.; Broholm, C.;

    2000-01-01

    The characteristic internal order of macroscopic quantum ground states in one-dimensional spin systems is usually not directly accessible, but reflected in the spin dynamics and the field dependence of the magnetic excitations. In high magnetic fields quantum phase transitions are expected. We...... present recent work on the high-field spin dynamics of the S = I antiferromagnetic Heisenberg chains NENP (Haldane ground state) and CsNiCl3 (quasi-1D HAF close to the quantum critical point), the uniform S = 1/2 chain CTS, and the spin-Peierls system CuGeO3. (C) 2000 Elsevier Science B,V. All rights...

  13. A Regional PD Strategy for EPR Systems: Evidence-Based IT Development

    DEFF Research Database (Denmark)

    Simonsen, Jesper; Hertzum, Morten

    2006-01-01

    systems. We present this PD strategy and our related research on evidence-based IT development. We report from a newly completed PD experiment with EPR in the region conducted through a close collaboration compris-ing a neurological stroke unit, the region’s EPR unit, the vendor, as well as the authors.......One of the five regions in Denmark has initiated a remark-able and alternative strategy for the development of Elec-tronic Patient Record (EPR) systems. This strategy is driven by Participatory Design (PD) experiments and based on evidence of positive effects on the clinical practice when using EPR...

  14. MEASUREMENTS OF HIGH-FIELD THZ INDUCED PHOTOCURRENTS IN SEMICONDUCTORS

    Energy Technology Data Exchange (ETDEWEB)

    Wiczer, M.; Lindenberg, A.

    2008-01-01

    THz pulses have provided a useful tool for probing the time-resolved dynamics of free carriers in a system. However, the development of methods to produce intense THz radiation has been slow. We have developed a method for producing intense ultra-short THz pulses, which have a full width at half maximum of 300 fs — approximately a half cycle of THz radiation. These intense half cycle pulses (HCPs) allowed us to use THz radiation as a source of excitation. By exposing the semiconductor indium antimonide (InSb) to intense THz HCP radiation, we have observed non-linear optical effects which suggest the generation of new free carriers by below band-gap THz photons. This generation of free carriers appears to be due to an avalanche multiplication process which then induces a current in the time-scale of our THz pulse. This amplifi cation on such a short timescale suggests the possibility of an ultrafast detector of weak above band-gap radiation. We constructed a device which detects these currents by painting an electrode structure on the surface of the semiconductor. The currents induced across the electrodes by this avalanche multiplication process were measured and compared with other measurements of this non-linear optical process. We successfully measured THz induced currents in InSb, suggesting promise towards the development of an ultra-fast detector. Further, we have gained insight into a possible physical explanation of the THz induced free carriers we observe in InSb.

  15. The new installation at the Nijmegen High Field Magnet Laboratory

    NARCIS (Netherlands)

    Perenboom, J.A.A.J.; Wiegers, S.A.J.; Christianen, P.C.M.; Zeitler, U.; Maan, J.C.

    2004-01-01

    For research in the highest continuous and pulsed magnetic fields large, complex and powerful installations are needed. A new 20 MW installation has been built at the University of Nijmegen. The ultra-low ripple power converter, delivering 40 kA at up to 500 V, provides the capability to perform exp

  16. High field – low energy muon ionization cooling channel

    Directory of Open Access Journals (Sweden)

    Hisham Kamal Sayed

    2015-09-01

    Full Text Available Muon beams are generated with large transverse and longitudinal emittances. In order to achieve the low emittances required by a muon collider, within the short lifetime of the muons, ionization cooling is required. Cooling schemes have been developed to reduce the muon beam 6D emittances to ≈300  μm-rad in transverse and ≈1–1.5  mm in longitudinal dimensions. The transverse emittance has to be further reduced to ≈50–25  μm-rad with an upper limit on the longitudinal emittance of ≈76  mm in order to meet the high-energy muon collider luminosity requirements. Earlier studies of the transverse cooling of low energy muon beams in high field magnets showed a promising performance, but did not include transverse or longitudinal matching between the stages. In this study we present the first complete design of the high field-low energy ionization cooling channel with transverse and longitudinal matching. The channel design was based on strong focusing solenoids with fields of 25–30 T and low momentum muon beam starting at 135  MeV/c and gradually decreasing. The cooling channel design presented here is the first to reach ≈50 micron scale emittance beam. We present the channel’s optimized design parameters including the focusing solenoid fields, absorber parameters and the transverse and longitudinal matching.

  17. Background field coils for the High Field Test Facility

    Energy Technology Data Exchange (ETDEWEB)

    Zbasnik, J.P.; Cornish, D.N.; Scanlan, R.M.; Jewell, A.M.; Leber, R.L.; Rosdahl, A.R.; Chaplin, M.R.

    1980-09-22

    The High Field Test Facility (HFTF), presently under construction at LLNL, is a set of superconducting coils that will be used to test 1-m-o.d. coils of prototype conductors for fusion magnets in fields up to 12 T. The facility consists of two concentric sets of coils; the outer set is a stack of Nb-Ti solenoids, and the inner set is a pair of solenoids made of cryogenically-stabilized, multifilamentary Nb/sub 3/Sn superconductor, developed for use in mirror-fusion magnets. The HFTF system is designed to be parted along the midplane to allow high-field conductors, under development for Tokamak fusion machines, to be inserted and tested. The background field coils were wound pancake-fashion, with cold-welded joints at both the inner and outer diameters. Turn-to-turn insulation was fabricated at LLNL from epoxy-fiberglass strip. The coils were assembled and tested in our 2-m-diam cryostat to verify their operation.

  18. High-field electrical and thermal transport in suspended graphene.

    Science.gov (United States)

    Dorgan, Vincent E; Behnam, Ashkan; Conley, Hiram J; Bolotin, Kirill I; Pop, Eric

    2013-10-09

    We study the intrinsic transport properties of suspended graphene devices at high fields (≥1 V/μm) and high temperatures (≥1000 K). Across 15 samples, we find peak (average) saturation velocity of 3.6 × 10(7) cm/s (1.7 × 10(7) cm/s) and peak (average) thermal conductivity of 530 W m(-1) K(-1) (310 W m(-1) K(-1)) at 1000 K. The saturation velocity is 2-4 times and the thermal conductivity 10-17 times greater than in silicon at such elevated temperatures. However, the thermal conductivity shows a steeper decrease at high temperature than in graphite, consistent with stronger effects of second-order three-phonon scattering. Our analysis of sample-to-sample variation suggests the behavior of "cleaner" devices most closely approaches the intrinsic high-field properties of graphene. This study reveals key features of charge and heat flow in graphene up to device breakdown at ~2230 K in vacuum, highlighting remaining unknowns under extreme operating conditions.

  19. High-field proton MRS of human brain

    Energy Technology Data Exchange (ETDEWEB)

    Di Costanzo, Alfonso E-mail: alfonso.dicostanzo@unina2.it; Trojsi, F.; Tosetti, M.; Giannatempo, G.M.; Nemore, F.; Piccirillo, M.; Bonavita, S.; Tedeschi, G.; Scarabino, T

    2003-11-01

    Proton magnetic resonance spectroscopy ({sup 1}H-MRS) of the brain reveals specific biochemical information about cerebral metabolites, which may support clinical diagnoses and enhance the understanding of neurological disorders. The advantages of performing {sup 1}H-MRS at higher field strengths include better signal to noise ratio (SNR) and increased spectral, spatial and temporal resolution, allowing the acquisition of high quality, easily quantifiable spectra in acceptable imaging times. In addition to improved measurement precision of N-acetylaspartate, choline, creatine and myo-inositol, high-field systems allow the high-resolution measurement of other metabolites, such as glutamate, glutamine, {gamma}-aminobutyric acid, scyllo-inositol, aspartate, taurine, N-acetylaspartylglutamate, glucose and branched amino acids, thus extending the range of metabolic information. However, these advantages may be hampered by intrinsic field-dependent technical difficulties, such as decreased T2 signal, chemical shift dispersion errors, J-modulation anomalies, increased magnetic susceptibility, eddy current artifacts, limitations in the design of homogeneous and sensitive radiofrequency (RF) coils, magnetic field instability and safety issues. Several studies demonstrated that these limitations could be overcome, suggesting that the appropriate optimization of high-field {sup 1}H-MRS would expand the application in the fields of clinical research and diagnostic routine.

  20. EPR detected polarization transfer between Gd3+ and protons at low temperature and 3.3 T: The first step of dynamic nuclear polarization

    Science.gov (United States)

    Nagarajan, Vijayasarathi; Hovav, Yonatan; Feintuch, Akiva; Vega, Shimon; Goldfarb, Daniella

    2010-06-01

    Electron-electron double resonance pulsed electron paramagnetic resonance (EPR) at 95 GHz (3.3 T) is used to follow the dynamics of the electron spin polarization during the first stages of dynamic nuclear polarization in solids. The experiments were performed on a frozen solution of Gd+3 (S =7/2) in water/glycerol. Focusing on the central |-1/2⟩→|+1/2⟩ transition we measured the polarization transfer from the Gd3+ electron spin to the adjacent H1 protons. The dependence of the echo detected EPR signal on the length of the microwave irradiation at the EPR "forbidden" transition corresponding to an electron and a proton spin flip is measured for different powers, showing dynamics on the microsecond to millisecond time scales. A theoretical model based on the spin density matrix formalism is suggested to account for this dynamics. The central transition of the Gd3+ ion is considered as an effective S =1/2 system and is coupled to H1 (I =1/2) nuclei. Simulations based on a single electron-single nucleus four level system are shown to deviate from the experimental results and an alternative approach taking into account the more realistic multinuclei picture is shown to agree qualitatively with the experiments.

  1. EPR dosimetry of radiation background in the Urals region

    Energy Technology Data Exchange (ETDEWEB)

    Shishkina, E.A.; Degteva, M.O.; Shved, V.A. [Urals Research Center for Radiation Medicine, 48-A Vorovsky, Chelyabinsk 454076 (Russian Federation); Fattibene, P.; Onori, S. [Istituto Superiore di Sanita and Istituto Nazionale di Fisica Nucleare (Italy); Wieser, A. [GSF, Forschungszentrum fuer Umwelt und Gesundheit, Ingolstaedter Landstr (Germany); Ivanov, D.V.; Bayankin, S.N. [Institute of Metal Physics, Russian Academy of Sciences (Russian Federation); Knyazev, V.A.; Vasilenko, E.I.; Gorelov, M. [ZAO, Closed Corporation ' Company GEOSPETSECOLOGIA' (Russian Federation)

    2006-07-01

    Method of Electron Paramagnetic Resonance is extensively applied to individual retrospective dosimetry. The background dose is unavoidable component of cumulative absorbed dose in the tooth enamel accumulated during the lifetime of donor. Estimation of incidental radiation dose using tooth enamel needs in extraction of background dose. Moreover, the variation of background doses in the population is a limited factor for reliable detection of additional irradiation especially for low dose level. Therefore the accurate knowledge of the natural background radiation dose is a critical element of EPR studies of exposed populations. In the Urals region the method applies for such two large cohorts as the workers of Mayak (Ozersk citizens) and Techa River riverside inhabitants (rural population). Current study aimed to investigate the Urals radiation background detected by EPR spectrometry. For this aim two group of unexposed Urals residents were separated, viz: citizens of Ozersk and rural inhabitants of Chelyabinsk region. Comparison of two investigated territories has demonstrated that from the point of view of radiation background it is impossible to assume the Urals population as uniform. The reliable difference between the urban and rural residents has been found. The average background doses of Ozersk donors is in average 50 mGy higher than those detected for rural residents. The individual variability of background doses for Osersk has been higher than in the rural results. The difference in background dose levels between two population results in different limits of accidental dose detection and individualization. The doses for 'Mayak' workers (Ozyorsk citizens) can be classed as anthropogenic if the EPR measurements exceed 120 mGy for teeth younger than 40 years, and 240 mGy for teeth older than 70 years. The anthropogenic doses for Techa River residents (rural population) would be higher than 95 mGy for teeth younger than 50 years and 270 mGy for

  2. The possible use of EPR spectroscopy for paint pigment identification

    Energy Technology Data Exchange (ETDEWEB)

    Troup, G.J.; Hutton, D.R. [Monash Univ., Clayton, VIC (Australia). Dept. of Physics; Bacci, M.; Lotti, F.; Casini, A.; Picollo, M. [Istituto di Ricerca sulle Onde Elettromagnetiche, Florence, Italy (Italy)

    1996-12-31

    Full text: Visible and near-infra-red reflectance spectroscopy are now routinely used for the identification of paint pigments in Renaissance painting, thus playing a part in authentication and restoration. Since most of the pigments are minerals, and many minerals either contain traces of paramagnetic ions, or have paramagnetic ions in their main components (e.g., chromic oxide, haematite), it seemed logical to determine whether EPR could distinguish between different pigments. 14 pigments of different colours were tested in a Varian E-12 EPR spectrometer, at a frequency of {approx} 9.1 GHz. Measurements were made at room ({approx} 20 deg C) and liquid N{sub 2} temperatures, in the standard special quartz sample tubes. The active volume is 0. 15 ml, but at most, a volume of sample (powder) one tenth of this was used. The spectra (to be shown) clearly demonstrate that EPR can distinguish between different pigments. The power was 1 milliwatt, the modulation amplitude 4 gauss, the total field sweep 10,000 gauss, centred 5000 gauss and the amplification between 10{sup 2} and 10{sup 4}, as indicated on the charts. The signal to noise ratio is excellent, and sensitivity could be increased (if necessary) by a factor of {approx} 10{sup 3}, thus allowing much smaller samples to be tested. Because the signals are so strong it should be possible to scan at least small painted canvases by the following non-destructive technique, using existing equipment. All that is required is a modified resonant cavity; it must have a high Q, and a slot where the magnetic field is maximum, and the electric field zero. The canvas can thus be placed flush with the waveguide, to interact with the microwave magnetic field emanating from the slot

  3. Photodegradation of petroleum under Na and Hg lamps by EPR

    Energy Technology Data Exchange (ETDEWEB)

    Mauro, Eduardo di; Melo, Fernando Alves de; Turini, Marilene; Campos, Ariana de [Universidade Estadual de Londrina (UEL), PR (Brazil). Dept. of Physics; Guedes, Carmen Luisa Barbosa [Universidade Estadual de Londrina (UEL), PR (Brazil). Dept. of Chemistry; Mangrich, Antonio Salvio [Universidade Federal do Parana (UFPR), PR (Brazil). Dept. of Chemistry

    2002-07-01

    Full text: The environment has become frequent victim of the action of pollutants. This situation has been stimulating several scientific works in the attempt to monitor the self-defence of the environment and minimise the effects caused by these pollutants. The petroleum and its derived, among the several substances that attack the environment, occupy a distinction place in the pollution picture. In the present work, we studied the photodegradation of the Arabian Light and Brazilian (Campos Basin- RJ) oils. Sample of theses oils were irradiated by different time periods in a reactor equipped with Na and Hg vapour lamps, whose emission spectra have different features. The irradiated and non-irradiated samples were subjected to Electron Paramagnetic Resonance (EPR) analysis in a BRUKER (ESP-300) equipment, which operates in the X band (9 GHz) at room temperature. The EPR spectra showed similar features to the two oils. The EPR spectra are composed of a intense signal (one line) with g (spectroscopic factor) about two relative to free radicals and groups of eight lines correspondent to vanadyl porphyrinic compounds (VO{sup 2+}). The parameters of spin Hamiltonian were determined to the two detected paramagnetic species. The two oils irradiated by Na and Hg lamps showed variations in the values of g and {delta}H (linewidth) of the paramagnetic species. The changes in the parameters are the most significant in Brazilian petroleum samples irradiated by Hg lamp. The modifications in the linewidth of free radicals of the Arabian Light petroleum have the same tendency to the two utilised lamps. (author)

  4. Electron paramagnetic resonance of radicals and metal complexes. 2. international conference of the Polish EPR Association. Warsaw 9-13 September 1996

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    The conference of Electron Paramagnetic Resonance of Radicals and Metal Complexes has been held in Warsaw from 9 to 13 September 1996. It was the Second International Conference of the Polish EPR Association. The very extensive group of systems containing paramagnetic species has been studied by means of ESR or other magnetic techniques like ENDOR, Spin Echo etc. By radiation or photochemically generated radicals have been stabilized in low temperatures or being detected by means of very fast pulsed techniques. The chemical reactions, reaction kinetics of radicals as well as spin interaction with matrices have been studied and discussed. Over 100 lectures and posters have been presented.

  5. Quality assessment of automatically extracted data from GPs' EPR.

    Science.gov (United States)

    de Clercq, Etienne; Moreels, Sarah; Van Casteren, Viviane; Bossuyt, Nathalie; Goderis, Geert; Bartholomeeusen, Stefaan

    2012-01-01

    There are many secondary benefits to collecting routine primary care data, but we first need to understand some of the properties of this data. In this paper we describe the method used to assess the PPV and sensitivity of data extracted from Belgian GPs' EPR (diagnoses, drug prescriptions, referrals, and certain parameters), using data collected through an electronic questionnaire as a gold standard. We describe the results of the ResoPrim phase 2 project, which involved 4 software systems and 43 practices (10,307 patients). This method of assessment could also be applied to other research networks.

  6. EPR of Mononuclear Non-Heme Iron Proteins

    OpenAIRE

    Gaffney, Betty J.

    2009-01-01

    Flexible geometry of three- to six-protein side-chain ligands to non-heme iron in proteins is the basis for widely diverse reactivites ranging from iron transport to redox chemistry. The gap between fixed states determined by x-ray analysis can be filled by spectroscopic study of trapped intermediates. EPR is a versatile and relatively quick approach to defining intermediate states in terms of the geometry and electronic structures of iron. A number of examples in which the iron chemistry of ...

  7. EPR spectra of four gadolinium complexes with Schiff bases

    Institute of Scientific and Technical Information of China (English)

    姚克敏; 陈德余; 封子先; 李冬成; 冯亚菲; 何玲

    1995-01-01

    EPR spectra of four new gadolinium complexes with Schiff bases in polycrystalline powder and those of these complexes in three organic solvents were investigated at different temperatures. It has been observed for the first time that their freezing solution spectra are quite different from each other. In THF one peak was observed only, but there were three peaks and typical "U" spectral features appearing in DMF and DMSO at low temperatures. On the basis of spin Hamiltonian of S = 7/2 system, the correlations between crystal field strength in complexes and local symmetry around Gd3+ ions are discussed.

  8. EPR identification of irradiated Monascus purpureus red pigment

    Energy Technology Data Exchange (ETDEWEB)

    Duliu, Octavian G. E-mail: odlu@scut.fizica.unibuc.ro; Ferdes, Mariana; Ferdes, Ovidiu S

    2000-01-01

    Fresh red alimentary pigment extracted from Monascus purpureus fungus exhibits an intense EPR line consisting of a single, narrow line, attributed to a quinone radical. When irradiated with 7 MeV electrons or {sup 60}Co {gamma}-rays, the amplitude of this line increased with the absorbed dose following a saturation exponential dependency up to 10 kGy. During annealing treatment (isothermal heating at 100 deg. C) the irradiation centers decay exponentially with a half-life time of 2.30 min.

  9. EPR identification of irradiated Monascus purpureus red pigment

    Science.gov (United States)

    Duliu, Octavian G.; Ferdes, Mariana; Ferdes, Ovidiu S.

    2000-01-01

    Fresh red alimentary pigment extracted from Monascus purpureus fungus exhibits an intense EPR line consisting of a single, narrow line, attributed to a quinone radical. When irradiated with 7 MeV electrons or 60Co γ-rays, the amplitude of this line increased with the absorbed dose following a saturation exponential dependency up to 10 kGy. During annealing treatment (isothermal heating at 100°C) the irradiation centers decay exponentially with a half-life time of 2.30 min.

  10. Whole-globe biomechanics using high-field MRI.

    Science.gov (United States)

    Voorhees, Andrew P; Ho, Leon C; Jan, Ning-Jiun; Tran, Huong; van der Merwe, Yolandi; Chan, Kevin; Sigal, Ian A

    2017-07-01

    The eye is a complex structure composed of several interconnected tissues acting together, across the whole globe, to resist deformation due to intraocular pressure (IOP). However, most work in the ocular biomechanics field only examines the response to IOP over smaller regions of the eye. We used high-field MRI to measure IOP induced ocular displacements and deformations over the whole globe. Seven sheep eyes were obtained from a local abattoir and imaged within 48 h using MRI at multiple levels of IOP. IOP was controlled with a gravity perfusion system and a cannula inserted into the anterior chamber. T2-weighted imaging was performed to the eyes serially at 0 mmHg, 10 mmHg, 20 mmHg and 40 mmHg of IOP using a 9.4 T MRI scanner. Manual morphometry was conducted using 3D visualization software to quantify IOP-induced effects at the globe scale (e.g. axial length and equatorial diameters) or optic nerve head scale (e.g. canal diameter, peripapillary sclera bowing). Measurement sensitivity analysis was conducted to determine measurement precision. High-field MRI revealed an outward bowing of the posterior sclera and anterior bulging of the cornea due to IOP elevation. Increments in IOP from 10 to 40 mmHg caused measurable increases in axial length in 6 of 7 eyes of 7.9 ± 5.7% (mean ± SD). Changes in equatorial diameter were minimal, 0.4 ± 1.2% between 10 and 40 mmHg, and in all cases less than the measurement sensitivity. The effects were nonlinear, with larger deformations at normal IOPs (10-20 mmHg) than at elevated IOPs (20-40 mmHg). IOP also caused measurable increases in the nasal-temporal scleral canal diameter of 13.4 ± 9.7% between 0 and 20 mmHg, but not in the superior-inferior diameter. This study demonstrates that high-field MRI can be used to visualize and measure simultaneously the effects of IOP over the whole globe, including the effects on axial length and equatorial diameter, posterior sclera displacement and bowing, and even

  11. Role of high-field MR systems in neuroscience

    Energy Technology Data Exchange (ETDEWEB)

    Nakada, Tsutomu [Niigata Univ. (Japan). Brain Research Inst

    1999-07-01

    Nuclear magnetic resonance (NMR) is a remarkably versatile technology applicable to various aspects of medical science. Currently, there are three categories of MR techniques available for probing human brain function in detail. The first category comprises the most widely utilized techniques which make use of the metabolic effects of brain activation, represented by BOLD functional magnetic resonance imaging (fMRI) and EPISTAR cerebral blood flow imaging. The second category of techniques deals with apparent diffusion tensor in probing the cellular aspects of brain function and is represented by magnetic resonance axonography (MRX). The third category of techniques is the oldest and as yet the most underutilized. These techniques which include MR spectroscopy (MRS) and spectroscopic imaging (SI), are based on classical NMR spectroscopy and are capable of providing biochemical information in vivo. In these critically important but highly demanding techniques, high-field systems possess significant advantages over conventional systems. (author)

  12. High-Field Magnetization of Some Mn Alloys(Magnetism)

    OpenAIRE

    Tomiei, Hori; Hiroshi, Shiraishi; Hiroshi, Niida; Hiroaki, Kato; Giyuu, Kido; Yasuo, Yamaguchi; Yasuaki, Nakagawa; Shibaura Institute of Technology; Institute for Materials Research, Tohoku University

    1993-01-01

    We have made high-field magnetization measurements for some Mn alloys : ε-Mn_Ga with δ= -0.30, ε-(Mn_Fe_x)_3Sn with x=0.1 and 0.3, Fe_3Mn_4Ge_ and γ-(Mn_Fe_x)_Ga_y with x=0.44 and y=0.27. The ε-Mn_Ga has the hexagonal D0_ type structure and a distorted triangular antiferromagnetic spin structure. The hexagonal lattice is slightly distorted to an orthorhombic lattice at T_d of about 290 K with large magnetization. Pseudo-binary ε-(Mn_Fe_x)_3Sn has also the D0_ type structure, and the alloys wi...

  13. Spontaneous Radiation Emission from Short, High Field Strength Insertion Devices

    Energy Technology Data Exchange (ETDEWEB)

    Geoffrey Krafft

    2005-09-15

    Since the earliest papers on undulaters were published, it has been known how to calculate the spontaneous emission spectrum from ''short'' undulaters when the magnetic field strength parameter is small compared to unity, or in ''single'' frequency sinusoidal undulaters where the magnetic field strength parameter is comparable to or larger than unity, but where the magnetic field amplitude is constant throughout the undulater. Fewer general results have been obtained in the case where the insertion device is both short, i.e., the magnetic field strength parameter changes appreciably throughout the insertion device, and the magnetic field strength is high enough that ponderomotive effects, radiation retardation, and harmonic generation are important physical phenomena. In this paper a general method is presented for calculating the radiation spectrum for short, high-field insertion devices. It is used to calculate the emission from some insertion device designs of recent interest.

  14. REVIEW OF HIGH FIELD Q SLOPE, CAVITY MEASUREMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Gianluigi Ciovati

    2008-01-23

    One of the most interesting phenomenon occurring in superconducting radio-frequency (SRF) cavities made of bulk niobium is represented by a sharp decrease of the quality factor above peak surface magnetic field of about 90 mT and is referred to as "high field Q-slope" or "Q-drop". This phenomenon was observed first in 1997 and since then some effort was devoted to the understanding of the causes behind it. Still, no clear physical interpretation of the Q-drop has emerged, despite several attempts. In this contribution, I will review the experimental results for various cavities measured in many laboratories and I will try to identify common features and differences related to the Q-drop.

  15. Topical Developments in High-Field Dynamic Nuclear Polarization

    Science.gov (United States)

    Kiesewetter, Matthew K.; Frantz, Derik K.; Walish, Joseph J.; Ravera, Enrico; Luchinat, Claudio; Swager, Timothy M.; Griffin, Robert G.

    2015-01-01

    We report our recent efforts directed at improving high-field DNP experiments. We investigated a series of thiourea nitroxide radicals and the associated DNP enhancements ranging from ε = 25 to 82 that demonstrate the impact of molecular structure on performance. We directly polarized low-gamma nuclei including 13C, 2H, and 17O using trityl via the cross effect. We discuss a variety of sample preparation techniques for DNP with emphasis on the benefit of methods that do not use a glass-forming cryoprotecting matrix. Lastly, we describe a corrugated waveguide for use in a 700 MHz / 460 GHz DNP system that improves microwave delivery and increases enhancements up to 50%. PMID:25977588

  16. Spontaneous radiation emission from short, high field strength magnetic devices

    Directory of Open Access Journals (Sweden)

    G. A. Krafft

    2006-01-01

    Full Text Available Since the earliest papers on undulators were published, it has been known how to calculate the spontaneous emission spectrum from short undulators when the magnetic field strength parameter is small compared to unity, or in “single” frequency sinusoidal undulators where the magnetic field strength parameter is comparable to or larger than unity, but where the magnetic field amplitude is constant throughout the undulator. Fewer general results have been obtained in the case where the magnetic device is both short, i.e., the magnetic field strength parameter changes appreciably throughout the device, and the magnetic field strength is high enough that ponderomotive effects, radiation retardation, and harmonic generation are important physical phenomena. In this paper a general method is presented for calculating the radiation spectrum for short, high-field magnetic devices. It is used to calculate the emission from some designs of recent interest.

  17. Micromagnetic simulation for high field sensors with perpendicular magnetizations

    Institute of Scientific and Technical Information of China (English)

    Jin Wei; Liu Yao-Wen

    2007-01-01

    In this paper, we present a micromagnetic design for high field sensors. The hard layer of the sensors is L10-FePt which is magnetized perpendicularly to film plane and the sense layer is NiFe which is magnetized in the film plane. The magnetization configurations of the hard and sense layers at different external magnetic fields have been simulated. In micromagnetic simulation, the sense field up to one tesla can be reached by using this sensor. We find that whether the sensor has a symmetric or an asymmetric field-sensing window is determined by the coercive field of the hard layer and the demagnetizing field of the sense layer.

  18. EPR of photochromic Mo3+ in SrTiO3

    NARCIS (Netherlands)

    Kool, Th.W.

    2010-01-01

    In single crystals of SrTiO_3, a paramagnetic center, characterized by S = 3/2 and hyperfine interaction with an I = 5/2 nuclear spin has been observed in the temperature range 4.2K-77K by means of EPR. The impurity center is attributed to Mo3+. No additional line splitting in the EPR spectrum due t

  19. Pulse EPR-enabled interpretation of scarce pseudocontact shifts induced by lanthanide binding tags

    Energy Technology Data Exchange (ETDEWEB)

    Abdelkader, Elwy H.; Yao, Xuejun [Australian National University, Research School of Chemistry (Australia); Feintuch, Akiva [Weizmann Institute of Science, Department of Chemical Physics (Israel); Adams, Luke A.; Aurelio, Luigi; Graham, Bim [Monash University, Monash Institute of Pharmaceutical Sciences (Australia); Goldfarb, Daniella [Weizmann Institute of Science, Department of Chemical Physics (Israel); Otting, Gottfried, E-mail: gottfried.otting@anu.edu.au [Australian National University, Research School of Chemistry (Australia)

    2016-01-15

    Pseudocontact shifts (PCS) induced by tags loaded with paramagnetic lanthanide ions provide powerful long-range structure information, provided the location of the metal ion relative to the target protein is known. Usually, the metal position is determined by fitting the magnetic susceptibility anisotropy (Δχ) tensor to the 3D structure of the protein in an 8-parameter fit, which requires a large set of PCSs to be reliable. In an alternative approach, we used multiple Gd{sup 3+}-Gd{sup 3+} distances measured by double electron–electron resonance (DEER) experiments to define the metal position, allowing Δχ-tensor determinations from more robust 5-parameter fits that can be performed with a relatively sparse set of PCSs. Using this approach with the 32 kDa E. coli aspartate/glutamate binding protein (DEBP), we demonstrate a structural transition between substrate-bound and substrate-free DEBP, supported by PCSs generated by C3-Tm{sup 3+} and C3-Tb{sup 3+} tags attached to a genetically encoded p-azidophenylalanine residue. The significance of small PCSs was magnified by considering the difference between the chemical shifts measured with Tb{sup 3+} and Tm{sup 3+} rather than involving a diamagnetic reference. The integrative sparse data approach developed in this work makes poorly soluble proteins of limited stability amenable to structural studies in solution, without having to rely on cysteine mutations for tag attachment.

  20. N-player quantum games in an EPR setting

    CERN Document Server

    Chappell, James M; Abbott, Derek

    2012-01-01

    The $N$-player quantum game is analyzed in the context of an Einstein-Podolsky-Rosen (EPR) experiment. In this setting, a player's strategies are not unitary transformations as in alternate quantum game-theoretic frameworks, but a classical choice between two directions along which spin or polarization measurements are made. The players' strategies thus remain identical to their strategies in the mixed-strategy version of the classical game. In the EPR setting the quantum game reduces itself to the corresponding classical game when the shared quantum state reaches zero entanglement. We find the relations for the probability distribution for $N$-qubit GHZ and W-type states, subject to general measurement directions, from which the expressions for the mixed Nash equilibrium and the payoffs are determined. Players' payoffs are then defined with linear functions so that common two-player games can be easily extended to the $N$-player case and permit analytic expressions for the Nash equilibrium. As a specific exa...

  1. SIMULACIÓN DEL ESPECTRO EPR DEL RADICAL CO2-

    Directory of Open Access Journals (Sweden)

    Eduar Enrique Carvajal Taborda

    2013-09-01

    Full Text Available La  dosimetría EPR se basa en el hecho de que las radiaciones ionizantes interaccionan con el tejido mineralizado, en este caso es esmalte dental y tejido óseo, generan los radicales CO2- estables a temperatura ambiente y de larga vida cuya concentración depende de la dosis recibida. La cuantificación de estos radicales libres se hace por EPR, cuyo espectro característico consta de dos líneas, una muy intensa y otra de menor intensidad. En este trabajo identificamos teóricamente estas dos líneas solucionando el Hamiltoniano de espín electrónico y  simulando el espectro experimental, encontramos que el espectro ERP del radical CO2- es producido por la interacción del espín del electrón desapareado con el campo magnético externo y que el radical CO2- está ubicado en una simetría local axial.

  2. Cd 2+ effect on free radicals in Cladosporium cladosporioides-melanin tested by EPR spectroscopy

    Science.gov (United States)

    Matuszczyk, Magdalena; Buszman, Ewa; Pilawa, Barbara; Witoszyńska, Teresa; Wilczok, Tadeusz

    2004-08-01

    Changes in free radicals system of Cladosporium cladosporioides-melanin and model DOPA-melanin caused by diamagnetic Cd 2+ ions were studied by electron paramagnetic resonance (EPR) spectroscopy. EPR line of eumelanin was mainly found in the spectrum of Cl.cl.-melanin. Cd 2+ ions increased o-semiquinone free radicals concentration in both natural and synthetic melanins. Cd 2+ broadened EPR lines of Cl.cl.-melanin in mycelium and the ions fastened spin-lattice relaxation processes. The narrower EPR lines and slower spin-lattice relaxation were obtained for DOPA-melanin-Cd 2+ complexes than for DOPA-melanin. Pheomelanin additionally existing in Cl.cl. samples was responsible for differences between the EPR data for Cl.cl. melanin and DOPA-melanin.

  3. Alcoholic extraction enables EPR analysis to characterize radiation-induced cellulosic signals in spices.

    Science.gov (United States)

    Ahn, Jae-Jun; Sanyal, Bhaskar; Akram, Kashif; Kwon, Joong-Ho

    2014-11-19

    Different spices such as turmeric, oregano, and cinnamon were γ-irradiated at 1 and 10 kGy. The electron paramagnetic resonance (EPR) spectra of the nonirradiated samples were characterized by a single central signal (g = 2.006), the intensity of which was significantly enhanced upon irradiation. The EPR spectra of the irradiated spice samples were characterized by an additional triplet signal at g = 2.006 with a hyperfine coupling constant of 3 mT, associated with the cellulose radical. EPR analysis on various sample pretreatments in the irradiated spice samples demonstrated that the spectral features of the cellulose radical varied on the basis of the pretreatment protocol. Alcoholic extraction pretreatment produced considerable improvements of the EPR signals of the irradiated spice samples relative to the conventional oven and freeze-drying techniques. The alcoholic extraction process is therefore proposed as the most suitable sample pretreatment for unambiguous detection of irradiated spices by EPR spectroscopy.

  4. Preliminary study for precision dosimetry using electron paramagnetic resonance (EPR) in radiotherapy applications

    Energy Technology Data Exchange (ETDEWEB)

    Shehzadi, N. N.; Kim, I. J.; Yi, C. Y. [Center for Ionizing Radiation, Korea Research for Standards and Science, Daejeon (Korea, Republic of)

    2015-10-15

    EPR (Electron paramagnetic resonance) dosimetry for radiotherapy dose range (1-10 Gy) is still being established.Alanine is an important material for EPR dosimetry because in terms of density and radiation absorption properties, it is water equivalent. High repeatability and high reproducibility of alanine spectrum measurement makes it possible to estimate the irradiation dose accurately. This baseline study has been carried out to establish precision EPR dosimetry in therapeutic photon range. For that purpose, an EPR dosimetry system has been setup and repeatability as well as reproducibility of measurements using alanine dosimeter have been evaluated. Effect of anisotropy of alanine dosimeter in spectrometer cavity has also been observed. EPR dosimetry system is set up at KRISS. It is found that reproducibility of the system at therapeutic photon range is 1.5 % - 6.6 %.

  5. Radiation chemistry of L-Alanine: application to EPR dosimetry (1)

    Energy Technology Data Exchange (ETDEWEB)

    Kim, M. J.; Jeo, Y. H.; Ha, Y. K.; Park, Y. S.; Choi, I. G. [KAERI, Taejon (Korea, Republic of)

    2003-10-01

    High energy ionizing radiation leaves stable radicals to certain organic materials, such as alanine and tartrate. Electron Paramagnetic Resonance (EPR) spectroscopy is a powerful tool for the identification and quantification of these radiation-induced radicals. An EPR method has been applied to study the radical characteristics of L-alanine after gamma radiation dose in the range of {approx}mGy to 60 kGy. The free radicals induced by gamma radiation were fairly stable, and EPR intensity, radical concentration, was proportional to the absorbed dose up to 60 kGy. From the results of our EPR measurements, it can be concluded that an alanine/EPR method is a useful technique for gamma radiation dosimetry from very low to high dose range.

  6. Spectral Fatigue Analysis of Jacket Stuctures in Mumbai High Field

    Directory of Open Access Journals (Sweden)

    S. Nallayarasu

    2010-09-01

    Full Text Available Fatigue analysis of offshore structures is an integral part of design of offshore structures and shall be carried out with suitable method of discretising the seastate. Historically, for most of the fixed offshore structures, deterministic fatigue analysis found to predict the fatigue damage reasonably well and has been in use for several decades. Fixed structures with small topsides, mostly exhibit a static response characteristics and the natural period may be in the order of less than 2 seconds. Offshore platforms with larger production capacity and deeper water depths may require specialised treatment of seastate due to their dynamic characteristics more vulnerable for fatigue damage. A spectral fatigue analysis has been performed for two different platforms in Mumbai high field (MNP and RS14 and a comparison is made with deterministic analysis. The spectral fatigue analysis indicates that the predicted fatigue life is lower than the deterministic analysis since the dynamic amplification of wave loads are treated approximately in deterministic analysis. Hence for large structures, it recommended to use spectral methods to assess the fatigue life of tubular joints.

  7. The design of a large aperture high field dipole

    Energy Technology Data Exchange (ETDEWEB)

    Harfoush, F.; Harrison, M.; Kerby, J.; Koepke, K.; Mantsch, P.; Nicol, T.; Riddiford, A.; Theilacker, J.

    1989-12-01

    The impetus for this design report originated in the Snowmass 88 meeting where the subject of higher energies within the constraints of the existing Tevatron tunnel enclosure was investigated. It was determined that beam transport to the fixed target experimental areas was possible up to an energy of {approximately}1.5 Tev. Collider operation was feasible at somewhat higher energies (1.8 Tev), primarily limited by the ability to design a single turn beam abort system within the constraints of the straight section length. A new accelerator in the existing tunnel would, of necessity, have a similar though not identical lattice and straight section layout to the present Tevatron. Thus when issues arose in the magnet design requiring input from the accelerator standpoint we have assumed a Tevatron like machine. The possibility of using these high field magnets as elements in the existing Tevatron to create new warm space,' for another Interaction Region for example, also emphasizes compatibility with the present machine. 16 refs., 62 figs., 23 tabs.

  8. Towards Integrated Design and Modeling of High Field Accelerator Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Caspi, S.; Ferracin, P.

    2006-06-01

    The next generation of superconducting accelerator magnets will most likely use a brittle conductor (such as Nb{sub 3}Sn), generate fields around 18 T, handle forces that are 3-4 times higher than in the present LHC dipoles, and store energy that starts to make accelerator magnets look like fusion magnets. To meet the challenge and reduce the complexity, magnet design will have to be more innovative and better integrated. The recent design of several high field superconducting magnets have now benefited from the integration between CAD (e.g. ProE), magnetic analysis tools (e.g. TOSCA) and structural analysis tools (e.g. ANSYS). Not only it is now possible to address complex issues such as stress in magnet ends, but the analysis can be better detailed an extended into new areas previously too difficult to address. Integrated thermal, electrical and structural analysis can be followed from assembly and cool-down through excitation and quench propagation. In this paper we report on the integrated design approach, discuss analysis results and point out areas of future interest.

  9. Structure, ligands and substrate coordination of the oxygen-evolving complex of photosystem II in the S2 state: a combined EPR and DFT study.

    Science.gov (United States)

    Lohmiller, Thomas; Krewald, Vera; Navarro, Montserrat Pérez; Retegan, Marius; Rapatskiy, Leonid; Nowaczyk, Marc M; Boussac, Alain; Neese, Frank; Lubitz, Wolfgang; Pantazis, Dimitrios A; Cox, Nicholas

    2014-06-28

    The S2 state of the oxygen-evolving complex of photosystem II, which consists of a Mn4O5Ca cofactor, is EPR-active, typically displaying a multiline signal, which arises from a ground spin state of total spin ST = 1/2. The precise appearance of the signal varies amongst different photosynthetic species, preparation and solvent conditions/compositions. Over the past five years, using the model species Thermosynechococcus elongatus, we have examined modifications that induce changes in the multiline signal, i.e. Ca(2+)/Sr(2+)-substitution and the binding of ammonia, to ascertain how structural perturbations of the cluster are reflected in its magnetic/electronic properties. This refined analysis, which now includes high-field (W-band) data, demonstrates that the electronic structure of the S2 state is essentially invariant to these modifications. This assessment is based on spectroscopies that examine the metal centres themselves (EPR, (55)Mn-ENDOR) and their first coordination sphere ligands ((14)N/(15)N- and (17)O-ESEEM, -HYSCORE and -EDNMR). In addition, extended quantum mechanical models from broken-symmetry DFT now reproduce all EPR, (55)Mn and (14)N experimental magnetic observables, with the inclusion of second coordination sphere ligands being crucial for accurately describing the interaction of NH3 with the Mn tetramer. These results support a mechanism of multiline heterogeneity reported for species differences and the effect of methanol [Biochim. Biophys. Acta, Bioenerg., 2011, 1807, 829], involving small changes in the magnetic connectivity of the solvent accessible outer MnA4 to the cuboidal unit Mn3O3Ca, resulting in predictable changes of the measured effective (55)Mn hyperfine tensors. Sr(2+) and NH3 replacement both affect the observed (17)O-EDNMR signal envelope supporting the assignment of O5 as the exchangeable μ-oxo bridge and it acting as the first site of substrate inclusion.

  10. Medical reference dosimetry using EPR measurements of alanine

    DEFF Research Database (Denmark)

    Helt-Hansen, Jakob; Rosendal, F.; Kofoed, I.M.

    2009-01-01

    Background. Electron spin resonance (EPR) is used to determine the absorbed dose of alanine dosimeters exposed to clinical photon beams in a solid-water phantom. Alanine is potentially suitable for medical reference dosimetry, because of its near water equivalence over a wide energy spectrum, low...... on scaling of known spectra was developed to extract the alanine signal. Results. The dose accuracy, including calibration uncertainty, is less than 2% (k=1) above 4 Gy (n=4). The measurement uncertainty is fairly constant in absolute terms (30 mGy) and the relative uncertainty therefore rises for dose...... measurements below 4 Gy. Typical reproducibility is 1% (k=1) above 10 Gy and 2% between 4 and 10 Gy. Below 4 Gy the uncertainty is higher. A depth dose curve measurement was performed in a solid-water phantom irradiated to a dose of 20 Gy at the maximum dose point (dmax) in 6 and 18 MV photon beams...

  11. DLTS and EPR study of defects in H implanted silicon

    Energy Technology Data Exchange (ETDEWEB)

    Miksic, V.; Pivac, B. E-mail: pivac@rudjer.irb.hr; Rakvin, B.; Zorc, H.; Corni, F.; Tonini, R.; Ottaviani, G

    2002-01-01

    Single crystal CZ Si samples were implanted with hydrogen ions to the dose of 2E16 He ions/cm{sup 2} at room temperature and subsequently annealed in vacuum in the temperature interval from 100 to 900 deg. C. The aim of the experiment was to determine the conditions for bubble formation within the solid film, which may have important technological application. Defects produced in such samples were studied by deep-level transient spectroscopy (DLTS) and electron paramagnetic resonance (EPR) spectroscopy. It is shown that high dose hydrogen implantation produces vacancy-related and silicon selfinterstitial clusters. The latter are thought to be responsible for the formation of the weak displacement field. The annealing at higher temperatures creates multivacancy-related clusters responsible for the strong displacement field formation.

  12. EPR = ER and Scattering Amplitude as Entanglement Entropy Change

    CERN Document Server

    Seki, Shigenori

    2014-01-01

    Alday and Maldacena have found an exact minimal surface of open string world-sheet describing a gluon scattering. We study the causal structure of that minimal surface in AdS of position space, and find a world-sheet wormhole parametrized by Mandelstam variables. If we figure a gluon as an open string in AdS, the ribbon connecting the two strings always pass the world-sheet wormhole, demonstrating the EPR = ER for gluon scattering. Since entanglement is caused by an interaction, one can ask what is the relation between entanglement entropy and the scattering amplitude. We propose an answer by generalizing the holographic entanglement entropy (EE) of Ryu-Takayanagi to the case where two regions are divided in space-time and interpret the result as the change of EE.

  13. Effect of microwave power on EPR spectra of natural and synthetic dental biocompatible materials

    Directory of Open Access Journals (Sweden)

    Adamczyk Jakub

    2015-07-01

    Full Text Available Paramagnetic centers in the two exemplary synthetic and natural dental biocompatible materials applied in implantology were examined by the use of an X-band (9.3 GHz electron paramagnetic resonance (EPR spectroscopy. The EPR spectra were measured in the range of microwave power 2.2–70 mW. The aims of this work were to compare paramagnetic centers concentrations in different dental biocompatible materials and to determine the effect of microwave power on parameters of their EPR spectra. It is the very first and innovatory examination of paramagnetic centers in these materials. It was pointed out that paramagnetic centers existed in both natural (~1018 spin/g and synthetic (~1019 spin/g dental biocompatible materials, but the lower free radical concentration characterized the natural sample. Continuous microwave saturation of EPR spectra indicated that faster spin-lattice relaxation processes existed in synthetic dental biocompatible materials than in natural material. Linewidths (ΔBpp of the EPR spectra of the natural dental material slightly increased for the higher microwave powers. Such effect was not observed for the synthetic material. The broad EPR lines (ΔBpp: 2.4 mT, 3.9 mT, were measured for the natural and synthetic dental materials, respectively. Probably strong dipolar interactions between paramagnetic centers in the studied samples may be responsible for their line broadening. EPR spectroscopy is the useful experimental method in the examination of paramagnetic centers in dental biocompatible materials.

  14. Developments at the High Field Magnet Laboratory in Nijmegen

    Science.gov (United States)

    Perenboom, J. A. A. J.; Maan, J. C.; van Breukelen, M. R.; Wiegers, S. A. J.; den Ouden, A.; Wulffers, C. A.; van der Zande, W. J.; Jongma, R. T.; van der Meer, A. F. G.; Redlich, B.

    2013-03-01

    The High Field Magnet Laboratory at the Radboud University Nijmegen is rapidly expanding its capabilities. The developments encompass both organizational changes and new possibilities for research. The organization of the HFML was strengthened as a consequence of stronger participation of the Foundation for Fundamental Research on Matter (FOM), and an increase of the core-funding. This change makes that HFML is now considered on a national level as large research facility that operates at an international scale. At the same time work is underway to build new and powerful magnets, and provide electromagnetic radiation for magneto-spectroscopic studies. Electromagnetic radiation in the infrared and far-infrared spectrum will soon be available in the HFML with wavelengths between 3 μm and 1.5 mm, produced by the `FELIX' facility, comprising the long-wavelength free electron laser `FLARE' that in September 2011 produced its first light and the free electron lasers that have been moved from Rijnhuizen to Nijmegen. In magnet technology great strides are made to make magnets available for the user community with unprecedented performance: late in 2012 we hope to commission a new all-resistive magnet system that will generate a steady magnetic field as high as 38 T, by fully exploiting the maximum power of the installation, i.e. 20 MW, and using all available improvements in the design and construction of `Florida-Bitter' resistive magnets. We are also well underway with the design of a 45 T hybrid magnet system, using Nb3Sn superconductors and wind-and-react Cable-in-Conduit technology.

  15. High field transport properties of a bilayer graphene

    Science.gov (United States)

    Bhargavi, K. S.; Kubakaddi, S. S.

    2014-02-01

    The high electric field transport properties namely, hot electron energy loss rate P, momentum loss rate Q, electron temperature Te and drift velocity Vd are studied theoretically in a bilayer graphene (BLG) by employing the momentum and energy balance technique. P and Q are investigated as a function of Te by considering the electron interaction with the acoustic phonons (APs) and the surface polar phonons (SPPs). In the Bloch-Grüneisen regime P (Q) due to APs is ~Te4 (Te2.5), with a new feature of a kink appearing due to the chiral nature of the electrons. The predicted Te4 is consistent with the recent experimental observation of heat resistance (Yan et al. Nature Nanotechnology 3 (2012) 472 [35]). Hot phonon effect is taken into account for SPPs. A dip has been observed in the hot phonon distribution of SPPs, a new feature, which is not found in conventional two-dimensional electron gas, and this can be attributed to the chiral nature of the electrons. P (Q) due to SPPs is found to be dominant at about Te>150 (180) K for a lattice temperature T=4.2 K. It is observed that the hot phonon effect is found to reduce P and Q due to SPPs significantly. Te and Vd are calculated as a function of the electric field E by taking into account the additional channels for momentum relaxation due to Coulomb impurity (CI) and short-range disorder (SD). Te is found to increase with the increasing electric field and is significantly enhanced by the hot phonon effect. Low field Vd is found to be limited by CI, SD and APs and in the high field region it reaches a near saturation value. The hot phonon effect tends to reduce the value of Vd. The presence of disorders CI and SD reduces Vd significantly and in clean samples larger saturation velocity can be achieved at a relatively smaller E.

  16. Ultra-high field magnets for whole-body MRI

    Science.gov (United States)

    Warner, Rory

    2016-09-01

    For whole-body MRI, an ultra-high field (UHF) magnet is currently defined as a system operating at 7 T or above. Over 70 UHF magnets have been built, all with the same technical approach originally developed by Magnex Scientific Ltd. The preferred coil configuration is a compensated solenoid. In this case, the majority of the field is generated by a simple long solenoid that stretches the entire length of the magnet. Additional coils are wound on a separate former outside the main windings with the purpose of balancing the homogeneity. Most of the magnets currently in operation are passively shielded systems where the magnet is surrounded by a steel box of 200-870 tonnes of carbon steel. More recently actively shielded magnets have been built for operation at 7 T; in this case the stray field is controlled by with reverse turns wound on a separate former outside the primary coils. Protection against quench damage is much more complex with an actively shielded magnet design due to the requirement to prevent the stray field from increasing during a quench. In the case of the 7 T 900 magnet this controlled by combining some of the screening coils into each section of the protection circuit. Correction of the field variations caused by manufacturing tolerances and environmental effects are made with a combination of superconducting shims and passive shims. Modern UHF magnets operate in zero boil-off mode with the use of cryocoolers with cooling capacity at 4.2 K. Although there are no cryogen costs associated with normal operation UHF magnets require a significant volume (10 000-20 000 l) of liquid helium for the cool-down. Liquid helium is expensive therefore new methods of cool-down using high-power cryocoolers are being implemented to reduce the requirement.

  17. High-field Zeeman and Paschen-Back effects at high pressure in oriented ruby

    Science.gov (United States)

    Millot, Marius; Broto, Jean-Marc; Gonzalez, Jesus

    2008-10-01

    High-field Zeeman and Paschen-Back effects have been observed in single crystals of ruby submitted to hydrostatic pressure up to 10 GPa. A specific setup with a miniature diamond-anvil cell has been developed to combine high pressure and pulsed magnetic fields and to perform magnetophotoluminescence measurements. Careful analysis of low-temperature (4.2 and 77 K) photoluminescence spectra with a 56 T magnetic field applied along the c axis allows for the rectification of the assignment of observed emission lines to corresponding Zeeman-split levels. Besides, the intrinsic Zeeman-splitting factors of excited states reveal a linear pressure-induced increase. This enhancement is a signature of an increase in trigonal distortion induced by hydrostatic pressure. Moreover, spectra with magnetic field perpendicular to crystallographic c axis exhibit a Paschen-Back effect reflecting the progressive alignment of Cr3+ ions spin along the applied field. However, no pressure modification is observed in this compound, contrarily to the Heisenberg-to-Ising spin character pressure-induced transition observed in alexandrite.

  18. Spin dynamics of S = 1/2 kagome lattice antiferromagnets observed by high-field ESR

    Energy Technology Data Exchange (ETDEWEB)

    Ohta, Hitoshi [Molecular Photoscience Research Center, Kobe University, Kobe 657-8501 (Japan); Graduate School of Science, Kobe University, Kobe 657-8501 (Japan); Zhang, Wei-min [Graduate School of Science, Kobe University, Kobe 657-8501 (Japan); Okubo, Susumu; Fujisawa, Masashi [Molecular Photoscience Research Center, Kobe University, Kobe 657-8501 (Japan); Sakurai, Takahiro [Center for Supports to Research and Education Activities, Kobe University, Kobe 657-8501 (Japan); Okamoto, Yoshihiko; Yoshida, Hiroyuki; Hiroi, Zenji [Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa, Chiba 277-8581 (Japan)

    2010-03-15

    Due to the existence of strong spin frustration in a system, the spin dynamics of S = 1/2 kagome lattice antiferromagnet at low temperature has attracted much interest. High-field ESR has been measured on its model substances, Cu{sub 3}V{sub 2}O{sub 7}(OH){sub 2} . 2H{sub 2}O (volborthite) and BaCu{sub 3}V{sub 2}O{sub 3}(OH){sub 2} (vesignieite), down to 1.8 K using pulsed magnetic fields up to 16 T. The measurements are performed for 160 and 315 GHz using polycrys-talline samples. Although both samples showed the g-shift and the change of linewidth at low temperature, volborthite showed a small gap excitation of the order of 40 GHz (1.9 K) while vesignieite showed a paramagnetic behavior down to 1.9 K. Observed difference will be discussed in connection with the crystal structure, and the possible spin liquid state in vesignieite will be discussed. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  19. Highly-Efficient Charge Separation and Polaron Delocalization in Polymer-Fullerene Bulk-Heterojunctions: A Comparative Multi-Frequency EPR & DFT Study

    Science.gov (United States)

    Niklas, Jens; Mardis, Kristy L.; Banks, Brian P.; Grooms, Gregory M.; Sperlich, Andreas; Dyakonov, Vladimir; Beaupré, Serge; Leclerc, Mario; Xu, Tao; Yu, Luping; Poluektov, Oleg G.

    2016-01-01

    The ongoing depletion of fossil fuels has led to an intensive search for additional renewable energy sources. Solar-based technologies could provide sufficient energy to satisfy the global economic demands in the near future. Photovoltaic (PV) cells are the most promising man-made devices for direct solar energy utilization. Understanding the charge separation and charge transport in PV materials at a molecular level is crucial for improving the efficiency of the solar cells. Here, we use light-induced EPR spectroscopy combined with DFT calculations to study the electronic structure of charge separated states in blends of polymers (P3HT, PCDTBT, and PTB7) and fullerene derivatives (C60-PCBM and C70-PCBM). Solar cells made with the same composites as active layers show power conversion efficiencies of 3.3% (P3HT), 6.1% (PCDTBT), and 7.3% (PTB7), respectively. Under illumination of these composites, two paramagnetic species are formed due to photo-induced electron transfer between the conjugated polymer and the fullerene. They are the positive, P+, and negative, P-, polarons on the polymer backbone and fullerene cage, respectively, and correspond to radical cations and radical anions. Using the high spectral resolution of high-frequency EPR (130 GHz), the EPR spectra of these species were resolved and principal components of the g-tensors were assigned. Light-induced pulsed ENDOR spectroscopy allowed the determination of 1H hyperfine coupling constants of photogenerated positive and negative polarons. The experimental results obtained for the different polymer-fullerene composites have been compared with DFT calculations, revealing that in all three systems the positive polaron is distributed over distances of 40 - 60 Å on the polymer chain. This corresponds to about 15 thiophene units for P3HT, approximately three units PCDTBT, and about three to four units for PTB7. No spin density delocalization between neighboring fullerene molecules was detected by EPR. Strong

  20. Highly-efficient charge separation and polaron delocalization in polymer-fullerene bulk-heterojunctions: a comparative multi-frequency EPR and DFT study.

    Science.gov (United States)

    Niklas, Jens; Mardis, Kristy L; Banks, Brian P; Grooms, Gregory M; Sperlich, Andreas; Dyakonov, Vladimir; Beaupré, Serge; Leclerc, Mario; Xu, Tao; Yu, Luping; Poluektov, Oleg G

    2013-06-28

    The ongoing depletion of fossil fuels has led to an intensive search for additional renewable energy sources. Solar-based technologies could provide sufficient energy to satisfy the global economic demands in the near future. Photovoltaic (PV) cells are the most promising man-made devices for direct solar energy utilization. Understanding the charge separation and charge transport in PV materials at a molecular level is crucial for improving the efficiency of the solar cells. Here, we use light-induced EPR spectroscopy combined with DFT calculations to study the electronic structure of charge separated states in blends of polymers (P3HT, PCDTBT, and PTB7) and fullerene derivatives (C60-PCBM and C70-PCBM). Solar cells made with the same composites as active layers show power conversion efficiencies of 3.3% (P3HT), 6.1% (PCDTBT), and 7.3% (PTB7), respectively. Upon illumination of these composites, two paramagnetic species are formed due to photo-induced electron transfer between the conjugated polymer and the fullerene. They are the positive, P(+), and negative, P(-), polarons on the polymer backbone and fullerene cage, respectively, and correspond to radical cations and radical anions. Using the high spectral resolution of high-frequency EPR (130 GHz), the EPR spectra of these species were resolved and principal components of the g-tensors were assigned. Light-induced pulsed ENDOR spectroscopy allowed the determination of (1)H hyperfine coupling constants of photogenerated positive and negative polarons. The experimental results obtained for the different polymer-fullerene composites have been compared with DFT calculations, revealing that in all three systems the positive polaron is distributed over distances of 40-60 Å on the polymer chain. This corresponds to about 15 thiophene units for P3HT, approximately three units for PCDTBT, and about three to four units for PTB7. No spin density delocalization between neighboring fullerene molecules was detected by EPR

  1. Taurine-EVA copolymer-paraffin rods dosimeters for EPR high-dose radiation dosimetry

    OpenAIRE

    Maghraby Ahmed M.; Mansour A; Abdel-Fattah A. A.

    2014-01-01

    Taurine/EPR rods (3 × 10 mm) have been prepared by a simple technique in the laboratory where taurine powder was mixed with a molten mixture of paraffin wax and an ethylene vinyl acetate (EVA) copolymer. The binding mixture EVA/Paraffin does not present interference or noise in the EPR signal before or after irradiation. The rods show good mechanical properties for safe and multi-use handling. An EPR investigation of radiation induced radicals in taurine rods revealed that there are two types...

  2. Copper-phthalocyanine encapsulated into zeolite-Y with high Si/Al: An EPR study

    Science.gov (United States)

    Yahiro, Hidenori; Kimoto, Kunihiro; Yamaura, Hiroyuki; Komaguchi, Kenji; Lund, Anders

    2005-10-01

    Copper (II) phthalocyanine (CuPc) molecules encapsulated into zeolite-Y with Si/Al ratios of 2.7 and 410 were prepared by an in situ synthesis and characterized by UV-Vis and electron paramagnetic resonance (EPR) spectroscopies. Resolved Cu-hyperfine and N-superhyperfine structures were observed in the EPR spectrum of CuPc encapsulated into zeolite-Y with a high Si/Al ratio. UV-Vis and EPR studies as well as theoretical calculations suggest that the encapsulated CuPc molecule was distorted in zeolite-Y with keeping of the square-planar symmetry around the center copper (II) ion.

  3. Growth and EPR properties of ErVO4 single crystals

    Directory of Open Access Journals (Sweden)

    Leniec Grzegorz

    2015-07-01

    Full Text Available Single crystals of ErVO4 were grown by the Czochralski method under ambient pressure in a nitrogen atmosphere. Obtained crystals were transparent with strong pink coloring. Electron paramagnetic resonance (EPR spectra were recorded as a function of the applied magnetic field. Temperature and angular dependences of the EPR spectra of the samples in the 3–300 K temperature range were analyzed applying both Lorentzian––Gauss approximation for diluted medium and Dyson for dense magnetic medium. EPR-NMR program was done to find local symmetry and spin Hamiltonian parameters of erbium ions.

  4. EPR statistical mixture of correlated states with fractional brownian process induced by third party interaction

    CERN Document Server

    Tamburini, F; Bianchini, A

    1999-01-01

    A time-correlated EPR pairs protocol is analized, based on detection of fractal correlated signals into a statistical mixture of EPR correlated pairs: an approximated alpha-Fractional Brownian Motion (FBM) is induced on the group of EPR pairs (e.g. by sender-third party eavesdropper-like interactions as in Ekert quantum cryptography), to be detected by the receiver using a non - orthogonal wavelet filter, able to characterize the FBM from a noisy enviroment by formalizing a nonlinear optimization problem for the FBM alpha-characteristic parameter extimation.

  5. EPR investigation of some desiccated Ascomycota and Basidiomycota gamma-irradiated mushrooms

    Energy Technology Data Exchange (ETDEWEB)

    Bercu, V., E-mail: vbercu@gmail.co [University of Bucharest, Department of Atomic and Nuclear Physics, P.O. Box MG-11, 077125 Magurele (Ilfov) (Romania); Negut, C.D., E-mail: dnegut@nipne.r [University of Bucharest, Department of Atomic and Nuclear Physics, P.O. Box MG-11, 077125 Magurele (Ilfov) (Romania); Horia Hulubei National Institute for Physics and Nuclear Engineering, P.O. Box MG-6, 077125 Magurele (Ilfov) (Romania); Duliu, O.G., E-mail: duliu@b.astral.r [University of Bucharest, Department of Atomic and Nuclear Physics, P.O. Box MG-11, 077125 Magurele (Ilfov) (Romania)

    2010-12-15

    The suitability of the EPR spectroscopy for detection of {gamma}-irradiation in five species of dried mushroom, currently used in gastronomy: yellow morel-Morchella esculenta, (L.) Pers. (Phylum Ascomycota), button mushroom-Agaricus bisporus (J.E.Lange), Agaricus haemorrhoidarius Fr., golden chantarelle-Cantharellus cibarius Fr., as well as oyster mushroom-Pleurotus ostreatus (Jacq. ex Fr.) (Phylum Basidiomycota) is presented and discussed. Although after irradiation at doses up to 11 kGy, all specimens presented well defined EPR spectra, only A. bisporus EPR signal was enough stable to make detection possible after 18 months.

  6. EPR investigation of some desiccated Ascomycota and Basidiomycota gamma-irradiated mushrooms

    Science.gov (United States)

    Bercu, V.; Negut, C. D.; Duliu, O. G.

    2010-12-01

    The suitability of the EPR spectroscopy for detection of γ-irradiation in five species of dried mushroom, currently used in gastronomy: yellow morel— Morchella esculenta, (L.) Pers. (Phylum Ascomycota), button mushroom— Agaricus bisporus (J.E.Lange), Agaricus haemorrhoidarius Fr., golden chantarelle— Cantharellus cibarius Fr., as well as oyster mushroom— Pleurotus ostreatus (Jacq. ex Fr.) (Phylum Basidiomycota) is presented and discussed. Although after irradiation at doses up to 11 kGy, all specimens presented well defined EPR spectra, only A. bisporus EPR signal was enough stable to make detection possible after 18 months.

  7. EPR as an analytical tool in assessing the mineral nutrients and irradiated food products-vegetables

    Science.gov (United States)

    Prasuna, C. P. Lakshmi; Chakradhar, R. P. S.; Rao, J. L.; Gopal, N. O.

    2008-12-01

    EPR spectral investigations of some commonly available vegetables in south India, which are of global importance like Daucus carota (carrot), Cyamopsis tetragonoloba (cluster beans), Coccinia indica (little gourd) and Beta vulgaris (beet root) have been carried out. In all the vegetable samples a free radical corresponding to cellulose radical is observed. Almost all the samples under investigation exhibit Mn ions in different oxidation states. The temperature variation EPR studies are done and are discussed in view of the paramagnetic oxidation states. The radiation-induced defects have also been assessed by using the EPR spectra of such irradiated food products.

  8. Pulse Voltammetry.

    Science.gov (United States)

    Osteryoung, Janet

    1983-01-01

    Discusses the nature of pulse voltammetry, indicating that its widespread use arises from good sensitivity and detection limits and from ease of application and low cost. Provides analytical and mechanistic applications of the procedure. (JN)

  9. EPR study of the astaxanthin n-octanoic acid monoester and diester radicals on silica-alumina.

    Science.gov (United States)

    Focsan, A Ligia; Bowman, Michael K; Shamshina, Julia; Krzyaniak, Matthew D; Magyar, Adam; Polyakov, Nikolay E; Kispert, Lowell D

    2012-11-08

    The radical intermediates of the n-octanoic monoester and n-octanoic diester of astaxanthin were detected by pulsed EPR measurements carried out on the UV-produced radicals on silica-alumina artificial matrix and characterized by density functional theory (DFT) calculations. Previous Mims ENDOR for astaxanthin detected the radical cation and neutral radicals formed by proton loss from the C3 (or C3') position and from the methyl groups. Deprotonation of the astaxanthin neutral radical formed at the C3 (or C3') position resulted in a radical anion. DFT calculations for astaxanthin showed that the lowest energy neutral radical forms by proton loss at the C3 (or C3') position of the terminal ring followed by proton loss at the methyl groups of the polyene chain. Contrary to astaxanthin where proton loss can occur at either end of the symmetrical radical, for the diester of astaxanthin, this loss is prevented at the cyclohexene ends and is favored for its methyl groups. The monoester of astaxanthin, however, allows formation of the neutral radical at C3' and prevents its formation at the opposite end where the ester group is attached. At the terminal ring without the ester group attached, migration of proton from hydroxyl group to carbonyl group facilitates resonance stabilization, similarly to already published results for astaxanthin. However, cw EPR shows no evidence of a monoester radical anion formed. This study suggests the different radicals of astaxanthin and its esters that would form in a preferred environment, either hydrophobic or hydrophilic, depending on their structure.

  10. Design and implementation of an FPGA-based timing pulse programmer for pulsed-electron paramagnetic resonance applications.

    Science.gov (United States)

    Sun, Li; Savory, Joshua J; Warncke, Kurt

    2013-08-01

    The design, construction and implementation of a field-programmable gate array (FPGA) -based pulse programmer for pulsed-electron paramagnetic resonance (EPR) experiments is described. The FPGA pulse programmer offers advantages in design flexibility and cost over previous pulse programmers, that are based on commercial digital delay generators, logic pattern generators, and application-specific integrated circuit (ASIC) designs. The FPGA pulse progammer features a novel transition-based algorithm and command protocol, that is optimized for the timing structure required for most pulsed magnetic resonance experiments. The algorithm was implemented by using a Spartan-6 FPGA (Xilinx), which provides an easily accessible and cost effective solution for FPGA interfacing. An auxiliary board was designed for the FPGA-instrument interface, which buffers the FPGA outputs for increased power consumption and capacitive load requirements. Device specifications include: Nanosecond pulse formation (transition edge rise/fall times, ≤3 ns), low jitter (≤150 ps), large number of channels (16 implemented; 48 available), and long pulse duration (no limit). The hardware and software for the device were designed for facile reconfiguration to match user experimental requirements and constraints. Operation of the device is demonstrated and benchmarked by applications to 1-D electron spin echo envelope modulation (ESEEM) and 2-D hyperfine sublevel correlation (HYSCORE) experiments. The FPGA approach is transferrable to applications in nuclear magnetic resonance (NMR; magnetic resonance imaging, MRI), and to pulse perturbation and detection bandwidths in spectroscopies up through the optical range.

  11. EPR spin Hamiltonian parameters of encapsulated spin-labels: impact of the hydrogen bonding topology.

    Science.gov (United States)

    Frecus, Bogdan; Rinkevicius, Zilvinas; Murugan, N Arul; Vahtras, Olav; Kongsted, Jacob; Ågren, Hans

    2013-02-21

    Encapsulation of spin-labels into "host" compounds, like cucurbit[n]urils or cyclodextrins, in solutions has profound effects on the EPR spin Hamiltonian parameters of the spin-labels. In this work we study the microscopic origin of the EPR spin Hamiltonian parameters of spin-labels enclosed in hydrophobic cavities. We focus on the dependence of the EPR properties of encapsulated spin-labels on the hydrogen bonding topologies that occur upon encapsulation, and quantize various contributions to these parameters according to specific hydrogen bonding patterns. The obtained results provide refined insight into the role of the hydrogen bonding induced encapsulation shifts of EPR spin Hamiltonian parameters in solvated "spin-label@host compound" complexes.

  12. Irradiation for dating Brazilian fish fossil by thermoluminescence and EPR technique

    Energy Technology Data Exchange (ETDEWEB)

    Sullasi, H.S.; Andrade, M.B.; Ayta, W.E.F.; Frade, M.; Sastry, M.D.; Watanabe, S

    2004-01-01

    Fish fossil from Ceara State, Brazil has been investigated using thermoluminescence and EPR method. In both cases, additive method has been used by irradiating fossil samples to very high doses (tens of kGy). In the case of thermoluminescence, 360 deg. C peak was used for dating. Since the fish fossil contains relatively high concentration of Mn, the EPR Mn{sup 2+}-lines cover carbonate and sulfate radicals signal (sulfur is also present in large amount), therefore 50 mW microwave power was used for EPR measurements. At this high power region Mn{sup 2+}-lines become very little intense and SO{sub 2}{sup -} and CO{sub 2}{sup -} can be detected. Both TL and EPR dating presented an age around 8 Ma. Correction due to spontaneous decay of 360 deg. C peak at ambient temperature gives rise to about {approx}24 Ma of age.

  13. Wormhole and Entanglement (Non-)Detection in the ER=EPR Correspondence

    CERN Document Server

    Bao, Ning; Remmen, Grant N

    2015-01-01

    The recently proposed ER=EPR correspondence postulates the existence of wormholes (Einstein-Rosen bridges) between entangled states (such as EPR pairs). Entanglement is famously known to be unobservable in quantum mechanics, in that there exists no observable (or, equivalently, projector) that can accurately pick out whether a generic state is entangled. Many features of the geometry of spacetime, however, are observables, so one might worry that the presence or absence of a wormhole could identify an entangled state in ER=EPR, violating quantum mechanics, specifically, the property of state-independence of observables. In this note, we establish that this cannot occur: there is no measurement in general relativity that unambiguously detects the presence of a generic wormhole geometry. This statement is the ER=EPR dual of the undetectability of entanglement.

  14. A view of EPR non-locality problems based on Aron's stochastic foundation of relativity

    Science.gov (United States)

    Scheer, Jens

    1990-12-01

    It is argued that the problem of causal anomalies that still may exist in Vigier's explanation of superluminal EPR type correlations may be removed in the framework of Aron's stochastic foundation of relativity.

  15. USE OF-EPR-DL FIELD TEST EQUIPMENT FOR DETECTION OF SIGMA PHASE

    Directory of Open Access Journals (Sweden)

    Abraão Danilo Gomes Barreto

    2014-06-01

    Full Text Available This work has objective to correlate the intergranular corrosion susceptibility test named EPR-DL (Electrochemical Potentiokinetic Reactivation of Double Loop with the sigma phase formation and other phases. It has been used samples from a UNS S32760 steel pipe for conducting various aging heat treatments. Held isothermal heat treatment at 850°C for 1 min, 10 min, 30 min, 1 h, 1h30min and 10 h. Each heat treated sample and as received were tested using the electrochemical polarization reactivation of double loop technique (EPR-DL. It was possible the detection of deleterious phases with DL-EPR portable cell. The EPR-DL test of some samples showed a second peak of reactivation in which the results showed that this peak might be associated with ferrite or be related to the presence of chi phase

  16. Wormhole and entanglement (non-)detection in the ER=EPR correspondence

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Ning [Institute for Quantum Information and Matter, California Institute of Technology,Pasadena, CA 91125 (United States); Walter Burke Institute for Theoretical Physics, California Institute of Technology,Pasadena, CA 91125 (United States); Pollack, Jason; Remmen, Grant N. [Walter Burke Institute for Theoretical Physics, California Institute of Technology,Pasadena, CA 91125 (United States)

    2015-11-19

    The recently proposed ER=EPR correspondence postulates the existence of wormholes (Einstein-Rosen bridges) between entangled states (such as EPR pairs). Entanglement is famously known to be unobservable in quantum mechanics, in that there exists no observable (or, equivalently, projector) that can accurately pick out whether a generic state is entangled. Many features of the geometry of spacetime, however, are observables, so one might worry that the presence or absence of a wormhole could identify an entangled state in ER=EPR, violating quantum mechanics, specifically, the property of state-independence of observables. In this note, we establish that this cannot occur: there is no measurement in general relativity that unambiguously detects the presence of a generic wormhole geometry. This statement is the ER=EPR dual of the undetectability of entanglement.

  17. EPR spectroscopy of protein microcrystals oriented in a liquid crystalline polymer medium

    Science.gov (United States)

    Caldeira, Jorge; Figueirinhas, João Luis; Santos, Celina; Godinho, Maria Helena

    2004-10-01

    Correlation of the g-tensor of a paramagnetic active center of a protein with its structure provides a unique experimental information on the electronic structure of the metal site. To address this problem, we made solid films containing metalloprotein ( Desulfovibrio gigas cytochrome c3) microcrystals. The microcrystals in a liquid crystalline polymer medium (water/hydroxypropylcellulose) were partially aligned by a shear flow. A strong orientation effect of the metalloprotein was observed by EPR spectroscopy and polarizing optical microscopy. The EPR spectra of partially oriented samples were simulated, allowing for molecular orientation distribution function determination. The observed effect results in enhanced sensitivity and resolution of the EPR spectra and provides a new approach towards the correlation of spectroscopic data, obtained by EPR or some other technique, with the three-dimensional structure of a protein or a model compound.

  18. Study of dose-response and radical decay curves of gamma irradiated norfloxacin using EPR spectroscopy

    Science.gov (United States)

    Sütçü, Kerem; Osmanoǧlu, Yunus Emre

    2017-02-01

    In this study, Electron Paramagnetic Resonance (EPR) spectra of unirradiated and γ-irradiated at doses of 1, 5, 10, 12 and 15 kGy norfloxacin (NOF) were investigated. Before irradiation no EPR signal were observed. After irradiation a weak singlet signal at g = 2.0039 were obtained at room temperature. In order to describe the variation of EPR signal intensity with absorbed radiation dose, several mathematical equations were tried. Increasing irradiation dose up to 15 kGy has increased the signal intensity of the central signal however, no significant changes were observed in g spectroscopic splitting factor. The stability of signal intensity of irradiated NOF was studied over a storage period of 200 days. According to analyses conducted, EPR spectroscopy can be used to distinguish irradiated and unirradiated samples from each other.

  19. Application of electron paramagnetic resonance (EPR) spectroscopy and imaging in drug delivery research - chances and challenges.

    Science.gov (United States)

    Kempe, Sabine; Metz, Hendrik; Mäder, Karsten

    2010-01-01

    Electron Paramagnetic Resonance (EPR) spectroscopy is a powerful technique to study chemical species with unpaired electrons. Since its discovery in 1944, it has been widely used in a number of research fields such as physics, chemistry, biology and material and food science. This review is focused on its application in drug delivery research. EPR permits the direct measurement of microviscosity and micropolarity inside drug delivery systems (DDS), the detection of microacidity, phase transitions and the characterization of colloidal drug carriers. Additional information about the spatial distribution can be obtained by EPR imaging. The chances and also the challenges of in vitro and in vivo EPR spectroscopy and imaging in the field of drug delivery are discussed.

  20. Transport de paires EPR dans des structures mesoscopiques

    Science.gov (United States)

    Dupont, Emilie

    Dans cette these, nous nous sommes particulierement interesses a la propagation de paires EPR1 delocalisees et localisees, et a l'influence d'un supraconducteur sur le transport de ces paires. Apres une introduction de cette etude, ainsi que du cadre scientifique qu'est l'informatique quantique dans lequel elle s'inscrit, nous allons dans le chapitre 1 faire un rappel sur le systeme constitue de deux points quantiques normaux entoures de deux fils supraconducteurs. Cela nous permettra d'introduire une methode de calcul qui sera reutilisee par la suite, et de trouver egalement le courant Josephson produit par ce systeme transforme en SQUID-dc par l'ajout d'une jonction auxiliaire. Le SQUID permet de mesurer l'etat de spin (singulet ou triplet), et peut etre forme a partir d'autres systemes que nous etudierons ensuite. Dans le chapitre 2, nous rappellerons l'etude detaillee d'un intricateur d'Andreev faite par un groupe de Bale. La matrice T, permettant d'obtenir le courant dans les cas ou les electrons sont separes spatialement ou non, sera etudiee en detail afin d'en faire usage au chapitre suivant. Le chapitre 3 est consacre a l'etude de l'influence du bruit sur le fonctionnement de l'intricateur d'Andreev. Ce bruit modifie la forme du courant jusqu'a aboutir a d'autres conditions de fonctionnement de l'intricateur. En effet, le bruit present sur les points quantiques peut perturber le transport des paires EPR par l'intermediaire des degres de liberte. Nous montrerons que, du fait de l'"intrication" entre la charge de la paire et le bruit, la paire est detruite pour des temps longs. Cependant, le resultat le plus important sera que le bruit perturbe plus le transport des paires delocalisees, qui implique une resonance de Breit-Wigner a deux particules. Le transport parasite n'implique pour sa part qu'une resonance de Breit-Wigner a une particule. Dans le chapitre 4, nous reviendrons au systeme constitue de deux points quantiques entoures de deux fils

  1. Evaluation of the original dose in irradiated dried fruit by EPR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    D' Oca, Maria Cristina, E-mail: mcristina.doca@unipa.it [Dipartimento Farmacochimico, Tossicologico e Biologico, Universita di Palermo, via Archirafi 32, 90123 Palermo (Italy); Bartolotta, Antonio [Dipartimento Farmacochimico, Tossicologico e Biologico, Universita di Palermo, via Archirafi 32, 90123 Palermo (Italy)

    2011-09-15

    The electron paramagnetic resonance spectroscopy (EPR) is one of the physical methods, recommended by the European Committee for Standardization, for the identification of irradiated food containing cellulose, such as dried fruit. In this work the applicability of EPR as identification method of irradiated pistachios, hazelnuts, peanuts, chestnuts, pumpkin seeds is evaluated; the time stability of the radiation induced signal is studied and the single aliquot additive dose method is used to evaluate the dose in the product.

  2. EPR Properties of Concentrated NdVO4 Single Crystal System.

    Science.gov (United States)

    Kaczmarek, S M; Fuks, H; Berkowski, M; Głowacki, M; Bojanowski, B

    Single crystals of NdVO4 were grown by the Czochralski method under ambient pressure in a nitrogen atmosphere. Obtained crystals were transparent with strong violet coloring. Temperature and angular dependences of electron paramagnetic resonance (EPR) spectra of the samples in the 3-103 K temperature range were analyzed applying Dyson like lineshape typically used for concentrated magnetic system. EPR-NMR program was used to find local symmetry and spin-Hamiltonian parameters of neodymium ions.

  3. Deterministic quantum key distribution based on Gaussian-modulated EPR correlations

    Institute of Scientific and Technical Information of China (English)

    He Guang-Qiang; Zeng Gui-Hua

    2006-01-01

    This paper proposes a deterministic quantum key distribution scheme based on Gaussian-modulated continuous variable EPR correlations. This scheme can implement fast and efficient key distribution. The security is guaranteed by continuous variable EPR entanglement correlations produced by nondegenerate optical parametric amplifier. For general beam splitter eavesdropping strategy, the secret information rate△I = I(α,β) - I(α,ε) is calculated in view of Shannon information theory. Finally the security analysis is presented.

  4. Preparation and applicability of fresh fruit samples for the identification of radiation treatment by EPR

    Energy Technology Data Exchange (ETDEWEB)

    Yordanov, Nicola D. [Laboratory EPR, Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria)], E-mail: ndyepr@bas.bg; Aleksieva, Katerina [Laboratory EPR, Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria)

    2009-03-15

    The results of electron paramagnetic resonance (EPR) study on fresh fruits (whole pulp of pears, apples, peaches, apricots, avocado, kiwi and mango) before and after gamma-irradiation are reported using two drying procedures before EPR investigation. In order to remove water from non-irradiated and irradiated samples of the first batch, the pulp of fresh fruits is pressed, and the solid residue is washed with alcohol and dried at room temperature. The fruits of the second batch are pressed and dried in a standard laboratory oven at 40 deg. C. The results obtained with both drying procedures are compared. All samples under study show a singlet EPR line with g=2.0048{+-}0.0005 before irradiation. Irradiation gives rise to typical 'cellulose-like' EPR spectrum featuring one intensive line with g=2.0048{+-}0.0005 and two very weak satellite lines situated 3 mT at left and right of the central line. Only mango samples show a singlet line after irradiation. The fading kinetics of radiation-induced EPR signal is studied for a period of 50 days after irradiation. When the irradiated fruit samples are stored in their natural state and dried just before each EPR measurement, the satellite lines are measurable for less than 17 days of storage. Irradiated fruit samples, when stored dried, lose for 50 days ca. 40% of their radiation-induced radicals if treated with alcohol or ca. 70% if dried in an oven. The reported results unambiguously show that the presence of the satellite lines in the EPR spectra could be used for identification of radiation processing of fresh fruits, thus extending the validity of European Protocol EN 1787 (2000). Foodstuffs-Detection of Irradiated Food Containing Cellulose by EPR Spectroscopy. European Committee for Standardisation. Brussels for dry herbs.

  5. EPR Entangled States for Bipartite Kinematics and New Bosonic Representation of SU(2) Algebra

    Institute of Scientific and Technical Information of China (English)

    FANHong-Yi; CHENJun-Hua

    2003-01-01

    We find that the Einstein-Podolsky-Rosen (EPR) entangled state representation descr/bing bipartite kinematics is closely related to a new Bose operator realization of SU(2) Lie algebra. By virtue of the new realization some ttamiltonian eigenfunction equation can be directly converted to the generalized confluent equation in the EPR entangled state representation and its solution is obtainable. This thus provides a new approach for studying dynamics of angular momentum systems.

  6. EPR Entangled States for Bipartite Kinematics and New Bosonic Representation of SU(2) Algebra

    Institute of Scientific and Technical Information of China (English)

    FAN Hong-Yi; CHEN Jun-Hua

    2003-01-01

    We find that the Einstein-Podolsky-Rosen (EPR) entangled state representation describing bipartite kinematics is closely related to a new Bose operator realization of SU(2) Lie algebra. By virtue of the new realization some Hamiltonian eigenfunction equation can be directly converted to the generalized confluent equation in the EPR entangled state representation and its solution is obtainable. This thus provides a new approach for studying dynamics of angular momentum systems.

  7. EPR character of gadolinium complexes with noncyclic polyether Schiff bases and its solvent effects

    Institute of Scientific and Technical Information of China (English)

    姚克敏; 陈德余; 王晓南; 邓宁

    1996-01-01

    EPR characters of three new gadolinium complexes with noncydic polyether Schiff bases in powder or organic solvents, including various oxyethylene chain lengths and different substituting groups in ligands, are investigated respectively. Some regularities are summed up. The difference of EPR character in various solvents, particularly at different temperatures, has been examined. The ’single peak effect’ due to THF solvent at low temperature is observed for the first time. This phenomenon is explicated.

  8. The EPR detection of foods preserved with the use of ionizing radiation

    Science.gov (United States)

    Stachowicz, W.; Burlińska, G.; Michalik, J.; Dziedzic-Gocławska, A.; Ostrowski, K.

    1995-02-01

    Solid constituents extracted from irradiated foods have been examined by the epr (esr) spectroscopy. It has been proved that some epr active species produced by radiation in foods are specific and stable enough to be used for the detection of irradiation treatment. The most promising results have been obtained with bones extracted from frozen raw meat (beef, pork, poultry and fish), with seeds of fruits (dates and figs), with dried mushrooms, gelatin and macaroni.

  9. Preparation and applicability of fresh fruit samples for the identification of radiation treatment by EPR

    Science.gov (United States)

    Yordanov, Nicola D.; Aleksieva, Katerina

    2009-03-01

    The results of electron paramagnetic resonance (EPR) study on fresh fruits (whole pulp of pears, apples, peaches, apricots, avocado, kiwi and mango) before and after gamma-irradiation are reported using two drying procedures before EPR investigation. In order to remove water from non-irradiated and irradiated samples of the first batch, the pulp of fresh fruits is pressed, and the solid residue is washed with alcohol and dried at room temperature. The fruits of the second batch are pressed and dried in a standard laboratory oven at 40 °C. The results obtained with both drying procedures are compared. All samples under study show a singlet EPR line with g=2.0048±0.0005 before irradiation. Irradiation gives rise to typical "cellulose-like" EPR spectrum featuring one intensive line with g=2.0048±0.0005 and two very weak satellite lines situated 3 mT at left and right of the central line. Only mango samples show a singlet line after irradiation. The fading kinetics of radiation-induced EPR signal is studied for a period of 50 days after irradiation. When the irradiated fruit samples are stored in their natural state and dried just before each EPR measurement, the satellite lines are measurable for less than 17 days of storage. Irradiated fruit samples, when stored dried, lose for 50 days ca. 40% of their radiation-induced radicals if treated with alcohol or ca. 70% if dried in an oven. The reported results unambiguously show that the presence of the satellite lines in the EPR spectra could be used for identification of radiation processing of fresh fruits, thus extending the validity of European Protocol EN 1787 (2000). Foodstuffs—Detection of Irradiated Food Containing Cellulose by EPR Spectroscopy. European Committee for Standardisation. Brussels for dry herbs.

  10. EPR safety. Consideration of the internal and external hazards in the safety studies; Surete du reacteur EPR. Prise en compte des agressions internes et externes dans les etudes de surete EPR

    Energy Technology Data Exchange (ETDEWEB)

    Gueguin, H. [Electricite de France (EDF-DIN), Centre National d' Equipement Nucleaire, Service Controle Commande, 92 - Montrouge (France)

    2008-04-15

    The author presents the main points of the Preliminary Safety Report of EDF on the EPR reactor safety. It concerns the considerations of the internal (fire, flood, explosions, pipes failures) and external (earthquakes, airplane falls, explosions, exceptional natural disasters, extreme meteorological conditions) damages. It presents how the safety report takes into account the aggression. (A.L.B.)

  11. EPR and IR spectral investigations on some leafy vegetables of Indian origin

    Science.gov (United States)

    Prasuna, C. P. Lakshmi; Chakradhar, R. P. S.; Rao, J. L.; Gopal, N. O.

    2009-09-01

    EPR spectral investigations have been carried out on four edible leafy vegetables of India, which are used as dietary component in day to day life. In Rumex vesicarius leaf sample, EPR spectral investigations at different temperatures indicate the presence of anti-ferromagnetically coupled Mn(IV)-Mn(IV) complexes. EPR spectra of Trigonella foenum graecum show the presence of Mn ions in multivalent state and Fe 3+ ions in rhombic symmetry. EPR spectra of Basella rubra indicate the presence of Mn(IV)-O-Mn(IV) type complexes. The EPR spectra of Basella rubra have been studied at different temperatures. It is found that the spin population for the resonance signal at g = 2.06 obeys the Boltzmann distribution law. The EPR spectra of Moringa oliefera leaves show the presence of Mn 2+ ions. Radiation induced changes in free radical of this sample have also been studied. The FT-IR spectra of Basella rubra and Moringa oliefera leaves show the evidences for the protein matrix bands and those corresponding to carboxylic C dbnd O bonds.

  12. Using ANN and EPR models to predict carbon monoxide concentrations in urban area of Tabriz

    Directory of Open Access Journals (Sweden)

    Mohammad Shakerkhatibi

    2015-09-01

    Full Text Available Background: Forecasting of air pollutants has become a popular topic of environmental research today. For this purpose, the artificial neural network (AAN technique is widely used as a reliable method for forecasting air pollutants in urban areas. On the other hand, the evolutionary polynomial regression (EPR model has recently been used as a forecasting tool in some environmental issues. In this research, we compared the ability of these models to forecast carbon monoxide (CO concentrations in the urban area of Tabriz city. Methods: The dataset of CO concentrations measured at the fixed stations operated by the East Azerbaijan Environmental Office along with meteorological data obtained from the East Azerbaijan Meteorological Bureau from March 2007 to March 2013, were used as input for the ANN and EPR models. Results: Based on the results, the performance of ANN is more reliable in comparison with EPR. Using the ANN model, the correlation coefficient values at all monitoring stations were calculated above 0.85. Conversely, the R2 values for these stations were obtained <0.41 using the EPR model. Conclusion: The EPR model could not overcome the nonlinearities of input data. However, the ANN model displayed more accurate results compared to the EPR. Hence, the ANN models are robust tools for predicting air pollutant concentrations.

  13. Pulse plating

    CERN Document Server

    Hansal, Wolfgang E G; Green, Todd; Leisner, Peter; Reichenbach, Andreas

    2012-01-01

    The electrodeposition of metals using pulsed current has achieved practical importance in recent years. Although it has long been known that changes in potential, with or without polarity reversal, can significantly affect the deposition process, the practical application of this has been slow to be adopted. This can largely be explained in terms of the complex relationship between the current regime and its effect on the electrodeposition process. In order to harness these effects, an understanding of the anodic and cathodic electrochemical processes is necessary, together with the effects of polarity reversal and the rate of such reversals. In this new monograph, the basics of metal electrodeposition from solution are laid out in great detail in seven distinct chapters. With this knowledge, the reader is able to predict how a given pulse train profile can be adopted to achieve a desired outcome. Equally important is the choice of a suitable rectifier and the ancillary control circuits to enable pulse platin...

  14. Thermoluminescence and EPR studies on natural petalite crystals

    Energy Technology Data Exchange (ETDEWEB)

    Souza, S.O.; Chubaci, J.F.D.; Watanabe, S. [Department of Nuclear Physics, Institute of Physics, University of Sao Paulo, Sao Paulo, SP (Brazil); Christopher Selvin, P. [NGM College, Pollachi, Tamil Nadu (India); Sastry, M.D. [Bhabha Atomic Research Center, Bombay (India)

    2002-07-07

    Thermally stimulated luminescence of natural mineral petalite (LiAlSi{sub 4}O{sub 10}) crystals was investigated and the possible electron/hole traps responsible for thermoluminescence (TL) emission were identified using optical absorption and electron paramagnetic resonance (EPR) measurements. The glow curves for natural samples, obtained with a heating rate of 4C s{sup -1}, show two glow peaks at 160 deg. C and 330 deg. C. Pre-annealed and subsequently irradiated samples give rise to three glow peaks at 175 deg. C, 340 deg. C and 435 deg. C. An isochronal thermal study established correlation between the first glow peak and Ti{sup 3+}-like trap centre and E'{sub 1}-centre and Al-O{sup -}-Al-like recombination centres. The second TL peak at 340 deg. C may be related to the E{sub 1}' centres formed on irradiation. A mechanism for the observed TL is suggested. (author)

  15. Wave Detection Beyond the Standard Quantum Limit via EPR Entanglement

    Science.gov (United States)

    Ma, Yiqiu; Miao, Haixing; Pang, Belinda; Evans, Matthew; Zhao, Chunnong; Harms, Jan; Schnabel, Roman; Chen, Yanbei

    2017-01-01

    The Standard Quantum Limit in continuous monitoring of a system is given by the trade-off of shot noise and back-action noise. In gravitational-wave detectors, such as Advanced LIGO, both contributions can simultaneously be squeezed in a broad frequency band by injecting a spectrum of squeezed vacuum states with a frequency-dependent squeeze angle. This approach requires setting up an additional long base-line, low-loss filter cavity in a vacuum system at the detector's site. Here, we show that the need for such a filter cavity can be eliminated, by exploiting EPR-entangled signal and idler beams. By harnessing their mutual quantum correlations and the difference in the way each beam propagates in the interferometer, we can engineer the input signal beam to have the appropriate frequency dependent conditional squeezing once the out-going idler beam is detected. Our proposal is appropriate for all future gravitational-wave detectors for achieving sensitivities beyond the Standard Quantum Limit.

  16. New Slant on the EPR-Bell Experiment

    CERN Document Server

    Evans, Peter; Wharton, K B

    2010-01-01

    The best case for thinking that quantum mechanics is nonlocal rests on Bell's Theorem, and later results of the same kind. However, the correlations characteristic of EPR-Bell (EPRB) experiments also arise in familiar cases elsewhere in QM, where the two measurements involved are timelike rather than spacelike separated; and in which the correlations are usually assumed to have a local causal explanation, requiring no action-at-a-distance. It is interesting to ask how this is possible, in the light of Bell's Theorem. We investigate this question, and present two options. Either (i) the new cases are nonlocal, too, in which case action-at-a-distance is more widespread in QM than has previously been appreciated (and does not depend on entanglement, as usually construed); or (ii) the means of avoiding action-at-a-distance in the new cases extends in an obvious way to EPRB, removing action-at-a-distance in these cases, too. There is a third option, viz., to argue that the new cases are strongly disanalogous to EP...

  17. Relativistically Self-Channeled Femtosecond Terawatt Lasers for High-Field Physics and X-Ray Generation

    Energy Technology Data Exchange (ETDEWEB)

    Borisov, A.B.; Boyer, K.; Cameron, S.M.; Luk, T.S.; McPherson, A.; Nelson, T.; Rhodes, C.K.

    1999-01-01

    Optical channeling or refractive guiding processes involving the nonlinear interaction of intense femtosecond optical pulses with matter in the self-focussing regime has created exciting opportunities for next-generation laser plasma-based x-ray sources and directed energy applications. This fundamentally new form of extended paraxial electromagnetic propagation in nonlinear dispersive media such as underdense plasma is attributed to the interplay between normal optical diffraction and intensity-dependent nonlinear focussing and refraction contributions in the dielectric response. Superposition of these mechanisms on the intrinsic index profile acts to confine the propagating energy in a dynamic self-guiding longitudinal waveguide structure which is stable for power transmission and robust compression. The laser-driven channels are hypothesized to support a degree of solitonic transport behavior, simultaneously stable in the space and time domains (group velocity dispersion balances self-phase modulation), and are believed to be self-compensating for diffraction and dispersion over many Rayleigh lengths in contrast with the defining characteristics of conventional diffractive imaging and beamforming. By combining concentrated power deposition with well-ordered spatial localization, this phenomena will also create new possibilities for production and regulation of physical interactions, including electron beams, enhanced material coupling, and self-modulated plasma wakefields, over extended gain distances with unprecedented energy densities. Harmonious combination of short-pulse x-ray production with plasma channeling resulting from a relativistic charge displacement nonlinearity mechanism in the terawatt regime (10{sup 18} W/cm{sup 2}) has been shown to generate high-field conditions conducive to efficient multi-kilovolt x-ray amplification and peak spectral brightness. Channeled optical propagation with intense short-pulse lasers is expected to impact several

  18. High-field transport properties of a P-doped BaFe2As2 film on technical substrate

    Science.gov (United States)

    Iida, Kazumasa; Sato, Hikaru; Tarantini, Chiara; Hänisch, Jens; Jaroszynski, Jan; Hiramatsu, Hidenori; Holzapfel, Bernhard; Hosono, Hideo

    2017-01-01

    High temperature (high-Tc) superconductors like cuprates have superior critical current properties in magnetic fields over other superconductors. However, superconducting wires for high-field-magnet applications are still dominated by low-Tc Nb3Sn due probably to cost and processing issues. The recent discovery of a second class of high-Tc materials, Fe-based superconductors, may provide another option for high-field-magnet wires. In particular, AEFe2As2 (AE: Alkali earth elements, AE-122) is one of the best candidates for high-field-magnet applications because of its high upper critical field, Hc2, moderate Hc2 anisotropy, and intermediate Tc. Here we report on in-field transport properties of P-doped BaFe2As2 (Ba-122) thin films grown on technical substrates by pulsed laser deposition. The P-doped Ba-122 coated conductor exceeds a transport Jc of 105 A/cm2 at 15 T for main crystallographic directions of the applied field, which is favourable for practical applications. Our P-doped Ba-122 coated conductors show a superior in-field Jc over MgB2 and NbTi, and a comparable level to Nb3Sn above 20 T. By analysing the E − J curves for determining Jc, a non-Ohmic linear differential signature is observed at low field due to flux flow along the grain boundaries. However, grain boundaries work as flux pinning centres as demonstrated by the pinning force analysis. PMID:28079117

  19. High-field transport properties of a P-doped BaFe2As2 film on technical substrate

    Science.gov (United States)

    Iida, Kazumasa; Sato, Hikaru; Tarantini, Chiara; Hänisch, Jens; Jaroszynski, Jan; Hiramatsu, Hidenori; Holzapfel, Bernhard; Hosono, Hideo

    2017-01-01

    High temperature (high-Tc) superconductors like cuprates have superior critical current properties in magnetic fields over other superconductors. However, superconducting wires for high-field-magnet applications are still dominated by low-Tc Nb3Sn due probably to cost and processing issues. The recent discovery of a second class of high-Tc materials, Fe-based superconductors, may provide another option for high-field-magnet wires. In particular, AEFe2As2 (AE: Alkali earth elements, AE-122) is one of the best candidates for high-field-magnet applications because of its high upper critical field, Hc2, moderate Hc2 anisotropy, and intermediate Tc. Here we report on in-field transport properties of P-doped BaFe2As2 (Ba-122) thin films grown on technical substrates by pulsed laser deposition. The P-doped Ba-122 coated conductor exceeds a transport Jc of 105 A/cm2 at 15 T for main crystallographic directions of the applied field, which is favourable for practical applications. Our P-doped Ba-122 coated conductors show a superior in-field Jc over MgB2 and NbTi, and a comparable level to Nb3Sn above 20 T. By analysing the E ‑ J curves for determining Jc, a non-Ohmic linear differential signature is observed at low field due to flux flow along the grain boundaries. However, grain boundaries work as flux pinning centres as demonstrated by the pinning force analysis.

  20. The structure and function of quinones in biological solar energy transduction: a cyclic voltammetry, EPR, and hyperfine sub-level correlation (HYSCORE) spectroscopy study of model naphthoquinones.

    Science.gov (United States)

    Coates, Christopher S; Ziegler, Jessica; Manz, Katherine; Good, Jacob; Kang, Bernard; Milikisiyants, Sergey; Chatterjee, Ruchira; Hao, Sijie; Golbeck, John H; Lakshmi, K V

    2013-06-20

    Quinones function as electron transport cofactors in photosynthesis and cellular respiration. The versatility and functional diversity of quinones is primarily due to the diverse midpoint potentials that are tuned by the substituent effects and interactions with surrounding amino acid residues in the binding site in the protein. In the present study, a library of substituted 1,4-naphthoquinones are analyzed by cyclic voltammetry in both protic and aprotic solvents to determine effects of substituent groups and hydrogen bonds on the midpoint potential. We use continuous-wave electron paramagnetic resonance (EPR) spectroscopy to determine the influence of substituent groups on the electronic properties of the 1,4-naphthoquinone models in an aprotic solvent. The results establish a correlation between the presence of substituent group(s) and the modification of electronic properties and a corresponding shift in the midpoint potential of the naphthoquinone models. Further, we use pulsed EPR spectroscopy to determine the effect of substituent groups on the strength and planarity of the hydrogen bonds of naphthoquinone models in a protic solvent. This study provides support for the tuning of the electronic properties of quinone cofactors by the influence of substituent groups and hydrogen bonding interactions.

  1. EPR study of deoxygenated high-temperature superconductors

    Indian Academy of Sciences (India)

    R J Singh; P K Sharma; Shakeel Khan

    2002-05-01

    High-c superconductors are EPR silent but on a little deoxygenation of the high-c materials and their constituents, they yield rich but complex spectra. Spectra of (1) CuO, (2) BaCuO2, (3) CaCuO2, (4) Y2Cu2O5, (5) La2CuO4, (6) La2-CuO4 (M = Sr, Ba), (7) Y based-123, (8) Bi based-2201, 2212, 2223, (9) Tl based-2223 and (10) Hg based-1212,1223 have been studied. One thing common to all these materials is the CuO2 plane which gets fragmented on deoxygenation and the inherent antiferromagnetic coupling is partially destroyed which results in the appearance of the spectra. The spectra recorded have been identified to be due to (1) Cu-monomer, (2) Cu-dimer, (3) Cutetramer, (4) Cu-octamer and (5) one signal at very low field which could not be identified because there was no structure in it and may be due to fragments higher than octamers. Very big fragments do not give any spectra because the original AF order probably remains intact in them. It is expected that when the fragments become magnetically isolated from the bulk, they produce EPR spectra. Most of the spectra have been analyzed and their spin-Hamiltonian parameters determined. The spectra of these species vary a little in terms of g-value and fine-structure splitting constant from sample to sample or even in the same sample and this may be attributed to some extra oxygen attachments retained with these species. Most frequently occurring species is the Cu-tetramer, (CuO)4. As (CuO)4 represents the unit cell of the all important two-dimensional CuO2 plane of the high-c materials, its spectra have been argued to provide some clue to the mechanism of high-c superconductivity. The tetramer (CuO)4 is a four one-half spin system and is essentially 16-fold degenerate by Heisenberg isotropic exchange, it is split into 6 components: one pentet, three triplets and two singlets. In superconductors the pentet appears to be the ground state and in the non-superconducting constituents the singlets seem to form the ground

  2. Development of high-strength and high-conductivity conductor materials for pulsed high-field magnets at Dresden

    Science.gov (United States)

    Grünberger, W.; Heilmaier, M.; Schultz, L.

    2001-01-01

    The work at the IFW Dresden is focused on the development of microcomposite Cu-Ag alloys and steel-copper macrocomposites with high-nitrogen steel and pearlitic steel jackets, respectively. In Cu-Ag alloys the investigation of continuously cast rods with different starting diameters suggests that the cooling rate during solidification determining the dendrite arm spacing has a minor influence on the development of the strength compared to the cooling velocity after solidification which determines the extent of the Ag-supersaturation in the Cu solid solution. Maximum strength at minimum drawing strain demands (i) a sufficient volume fraction of eutectic in order to suppress discontinuous precipitation (absence of grain boundaries) and (ii) a sufficiently rapid cooling after solidification in order to prevent pre-precipitation. With a continuously cast starting rod of 12 mm diameter a maximum tensile strength of 1.3 GPa was obtained after a drawing strain of only η=4.3. Steel-copper macrocomposites were fabricated by the ‘rod-in-tube’ technology. The experiments with austenitic high-nitrogen steels were performed with two alloys. With the commercial alloy Nicrofer 3033 a strength level of 1.2 GPa has been achieved with a 52 vol% Cu composite at a drawing strain of η=2.3. A composite with pearlitic C60-steel (0.6 wt% C) and 56 vol% Cu showed a tensile strength of 1.53 GPa after a final patenting at a diameter of 14.7 mm and a drawing strain of η=4.

  3. EPR/alanine dosimetry for two therapeutic proton beams

    Energy Technology Data Exchange (ETDEWEB)

    Marrale, Maurizio, E-mail: maurizio.marrale@unipa.it [Dipartimento di Fisica e Chimica, Università di Palermo, Viale delle Scienze, Edificio 18, 90128 Palermo (Italy); Gruppo V Sezione INFN di Catania, Via Santa Sofia, 64, 95123 Catania (Italy); Carlino, Antonio [Dipartimento di Fisica e Chimica, Università di Palermo, Viale delle Scienze, Edificio 18, 90128 Palermo (Italy); EBG MedAustron GmbH, Marie Curie-Straße 5, A-2700 Wiener Neustadt (Austria); Gallo, Salvatore [Dipartimento di Fisica e Chimica, Università di Palermo, Viale delle Scienze, Edificio 18, 90128 Palermo (Italy); Gruppo V Sezione INFN di Catania, Via Santa Sofia, 64, 95123 Catania (Italy); Laboratorio PH3DRA, Dipartimento di Fisica e Astronomia, Università di Catania, Via Santa Sofia 64, 95123 Catania (Italy); Longo, Anna; Panzeca, Salvatore [Dipartimento di Fisica e Chimica, Università di Palermo, Viale delle Scienze, Edificio 18, 90128 Palermo (Italy); Gruppo V Sezione INFN di Catania, Via Santa Sofia, 64, 95123 Catania (Italy); Bolsi, Alessandra; Hrbacek, Jan; Lomax, Tony [Center for Proton Therapy, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland)

    2016-02-01

    In this work the analysis of the electron paramagnetic resonance (EPR) response of alanine pellets exposed to two different clinical proton beams employed for radiotherapy is performed. One beam is characterized by a passive delivery technique and is dedicated to the eyes treatment (OPTIS2 beam line). Alanine pellets were irradiated with a 70 MeV proton beam corresponding to 35 mm range in eye tissue. We investigated how collimators with different sizes and shape used to conform the dose to the planned target volume influence the delivered dose. For this purpose we performed measurements with varying the collimator size (Output Factor) and the results were compared with those obtained with other dosimetric techniques (such as Markus chamber and diode detector). This analysis showed that the dosimeter response is independent of collimator diameter if this is larger than or equal to 10 mm. The other beam is characterized by an active spot-scanning technique, the Gantry1 beam line (maximum energy 230 MeV), and is used to treat deep-seated tumors. The dose linearity of alanine response in the clinical dose range was tested and the alanine dose response at selected locations in depth was measured and compared with the TPS planned dose in a quasi-clinical scenario. The alanine response was found to be linear in the dose in the clinical explored range (from 10 to 70 Gy). Furthermore, a depth dose profile in a quasi-clinical scenario was measured and compared to the dose computed by the Treatment Planning System PSIPLAN. The comparison of calibrated proton alanine measurements and TPS dose shows a difference under 1% in the SOBP and a “quenching” effect up to 4% in the distal part of SOBP. The positive dosimetric characteristics of the alanine pellets confirm the feasibility to use these detectors for “in vivo” dosimetry in clinical proton beams.

  4. A high-frequency electron paramagnetic resonance spectrometer for multi-dimensional, multi-frequency, and multi-phase pulsed measurements

    Energy Technology Data Exchange (ETDEWEB)

    Cho, F. H. [Department of Physics, University of Southern California, Los Angeles, California 90089 (United States); Stepanov, V. [Department of Chemistry, University of Southern California, Los Angeles, California 90089 (United States); Takahashi, S., E-mail: susumu.takahashi@usc.edu [Department of Chemistry, University of Southern California, Los Angeles, California 90089 (United States); Department of Physics, University of Southern California, Los Angeles, California 90089 (United States)

    2014-07-15

    We describe instrumentation for a high-frequency electron paramagnetic resonance (EPR) and pulsed electron-electron double resonance (PELDOR) spectroscopy. The instrumentation is operated in the frequency range of 107−120 GHz and 215−240 GHz and in the magnetic field range of 0−12.1 T. The spectrometer consisting of a high-frequency high-power solid-state source, a quasioptical system, a phase-sensitive detection system, a cryogenic-free superconducting magnet, and a {sup 4}He cryostat enables multi-frequency continuous-wave EPR spectroscopy as well as pulsed EPR measurements with a few hundred nanosecond pulses. Here we discuss the details of the design and the pulsed EPR sensitivity of the instrumentation. We also present performance of the instrumentation in unique experiments including PELDOR spectroscopy to probe correlations in an insulating electronic spin system and application of dynamical decoupling techniques to extend spin coherence of electron spins in an insulating solid-state system.

  5. Radiation sensitivity and EPR dosimetric potential of gallic acid and its esters

    Science.gov (United States)

    Tuner, Hasan; Oktay Bal, M.; Polat, Mustafa

    2015-02-01

    In the preset work the radiation sensitivities of Gallic Acid anhydrous and monohydrate, Octyl, Lauryl, and Ethyl Gallate (GA, GAm, OG, LG, and EG) were investigated in the intermediate (0.5-20 kGy) and low radiation (<10 Gy) dose range using Electron Paramagnetic Resonance (EPR) spectroscopy. While OG, LG, and EG are presented a singlet EPR spectra, their radiation sensitivity found to be very different in the intermediate dose range. At low radiation dose range (<10 Gy) only LG is found to be present a signal that easily distinguished from the noise signals. The intermediate and low dose range radiation sensitivities are compared using well known EPR dosimeter alanine. The radiation yields (G) of the interested material were found to be 1.34×10-2, 1.48×10-2, 4.14×10-2, and 6.03×10-2, 9.44×10-2 for EG, GA, GAm, OG, and LG, respectively at the intermediate dose range. It is found that the simple EPR spectra and the noticeable EPR signal of LG make it a promising dosimetric material to be used below 10 Gy of radiation dose.

  6. Taurine-EVA copolymer-paraffin rods dosimeters for EPR high-dose radiation dosimetry

    Directory of Open Access Journals (Sweden)

    Maghraby Ahmed M.

    2014-03-01

    Full Text Available Taurine/EPR rods (3 × 10 mm have been prepared by a simple technique in the laboratory where taurine powder was mixed with a molten mixture of paraffin wax and an ethylene vinyl acetate (EVA copolymer. The binding mixture EVA/Paraffin does not present interference or noise in the EPR signal before or after irradiation. The rods show good mechanical properties for safe and multi-use handling. An EPR investigation of radiation induced radicals in taurine rods revealed that there are two types of radicals produced after exposure to gamma radiation (60Co. EPR spectra were recorded and analyzed - also the microwave power saturation and modulation amplitude were studied and optimized. Response of taurine to different radiation doses (1.5-100 kGy was studied and found to follow a linear relationship up to 100 kGy. Radiation induced radicals in taurine persists and showed a noticeable stability over 94 days following irradiation. Uncertainities associated with the evaluation of radiation doses using taurine dosimeters were discussed and tabulated. It was found that taurine possesses good dosimetric properties using EPR spectroscopy in high doses in addition to its simple spectrum.

  7. New developed cylindrical TM010 mode EPR cavity for X-band in vivo tooth dosimetry.

    Directory of Open Access Journals (Sweden)

    Guo Junwang

    Full Text Available EPR tooth in vivo dosimetry is an attractive approach for initial triage after unexpected nuclear events. An X-band cylindrical TM010 mode resonant cavity was developed for in vivo tooth dosimetry and used in EPR applications for the first time. The cavity had a trapezoidal measuring aperture at the exact position of the cavity's cylindrical wall where strong microwave magnetic field H1 concentrated and weak microwave electric field E1 distributed. Theoretical calculations and simulations were used to design and optimize the cavity parameters. The cavity features were evaluated by measuring DPPH sample, intact incisor samples embed in a gum model and the rhesus monkey teeth. The results showed that the cavity worked at designed frequency and had the ability to make EPR spectroscopy in relative high sensitivity. Sufficient modulation amplitude and microwave power could be applied into the aperture. Radiation induced EPR signal could be observed remarkably from 1 Gy irradiated intact incisor within only 30 seconds, which was among the best in scan time and detection limit. The in vivo spectroscopy was also realized by acquiring the radiation induced EPR signal from teeth of rhesus monkey whose teeth was irradiated by dose of 2 Gy. The results suggested that the cavity was sensitive to meet the demand to assess doses of significant level in short time. This cavity provided a very potential option for the development of X-band in vivo dosimetry.

  8. DFT calculations of EPR parameters for copper(II)-exchanged zeolites using cluster models.

    Science.gov (United States)

    Ames, William M; Larsen, Sarah C

    2010-01-14

    The coordination environment of Cu(II) in hydrated copper-exchanged zeolites was explored through the use of density functional theory (DFT) calculations of EPR parameters. Extensive experimental EPR data are available in the literature for hydrated copper-exchanged zeolites. The copper complex in hydrated copper-exchanged zeolites was previously proposed to be [Cu(H(2)O)(5)OH](+) based on empirical trends in tetragonal model complex EPR data. In this study, calculated EPR parameters for the previously proposed copper complex, [Cu(H(2)O)(5)OH](+), were compared to model complexes in which Cu(II) was coordinated to small silicate or aluminosilicate clusters as a first approximation of the impact of the zeolitic environment on the copper complex. Interpretation of the results suggests that Cu(II) is coordinated or closely associated with framework oxygen atoms within the zeolite structure. Additionally, it is proposed that the EPR parameters are dependent on the Si/Al ratio of the parent zeolite.

  9. Harmonization of dosimetric information obtained by different EPR methods: Experience of the Techa river study

    Energy Technology Data Exchange (ETDEWEB)

    Volchkova, A. [Urals Research Center for Radiation Medicine, 68A, Vorovsky Str., 454076 Chelyabinsk (Russian Federation); Shishkina, E.A., E-mail: ElenaA.Shishkina@gmail.com [Urals Research Center for Radiation Medicine, 68A, Vorovsky Str., 454076 Chelyabinsk (Russian Federation); Ivanov, D. [Institute of Metal Physics, Russian Academy of Sciences, 18, S. Kovalevskoy Str., 620041 Yekaterinburg (Russian Federation); Timofeev, Yu. [Urals Research Center for Radiation Medicine, 68A, Vorovsky Str., 454076 Chelyabinsk (Russian Federation); Fattibene, P.; Della Monaca, S. [Istituto Superiore di Sanita and Istituto Nazionale di Fisica Nucleare, Viale Regina Elena 299, 00161 Rome (Italy); Wieser, A. [Helmholtz Zentrum Muenchen, German Research Centre for Environmental Health, D-85764 Neuherberg (Germany); Degteva, M.O. [Urals Research Center for Radiation Medicine, 68A, Vorovsky Str., 454076 Chelyabinsk (Russian Federation)

    2011-09-15

    Between 1949 and 1956 the Techa River (Southern Urals, Russia) was contaminated as a result of releases of radioactive waste by the Mayak Production Association. EPR dosimetry with tooth enamel has been used to estimate the external exposure of Techa riverside residents over the last 17 years. The database 'Tooth' of the Urals Research Center for Radiation Medicine (URCRM) has accumulated about 1000 EPR measurements of tooth enamel from the rural population of the Urals region. The teeth were investigated by laboratories of Russia, USA, Germany and Italy. Most of the enamel samples were measured several times in different laboratories. Each laboratory used different equipment and its own methods for sample preparation and EPR spectra analysis. Even measurements performed at the same laboratory over 10-15 years may not be assumed as uniform: methods change with time, and equipment is subject to aging. These two factors influenced EPR performance. The purpose of this study is, therefore, the harmonization of EPR data accumulated during long-term dosimetric investigations in the Southern Urals for further pooled analysis. The results will be used for external dose evaluation in the Techa River region.

  10. Spin system trajectory analysis under optimal control pulses

    Science.gov (United States)

    Kuprov, Ilya

    2013-08-01

    Several methods are proposed for the analysis, visualization and interpretation of high-dimensional spin system trajectories produced by quantum mechanical simulations. It is noted that expectation values of specific observables in large spin systems often feature fast, complicated and hard-to-interpret time dynamics and suggested that populations of carefully selected subspaces of states are much easier to analyze and interpret. As an illustration of the utility of the proposed methods, it is demonstrated that the apparent "noisy" appearance of many optimal control pulses in NMR and EPR spectroscopy is an illusion - the underlying spin dynamics is shown to be smooth, orderly and very tightly controlled.

  11. Pulsed thermoelectricity

    Science.gov (United States)

    Apostol, M.; Nedelcu, M.

    2010-07-01

    A special mechanism of thermoelectric transport is described, consisting of pulses of charge carriers which "fly" periodically through the external circuit from the hot end of the sample to the cold end, with a determined duration of the "on" and "off" times of the electric contacts, while maintaining continuously the thermal contacts. It is shown that such a "resonant" ideal thermogenerator may work cyclically, with the same efficiency quotient as the ideal efficiency quotient of the thermoelectric devices operated in the usual stationary transport regime but the electric flow and power are increased, as a consequence of the concentration of the charge carriers on pulses of small spatial extent. The process is reversible, in the sense that it can be operated either as a thermoelectric generator or as an electrothermal cooler.

  12. Extraction of pure spectral signatures and corresponding chemical maps from EPR imaging data sets: identifying defects on a CaF2 surface due to a laser beam exposure.

    Science.gov (United States)

    Abou Fadel, Maya; Zhang, Xin; de Juan, Anna; Tauler, Roma; Vezin, Hervé; Duponchel, Ludovic

    2015-04-07

    A calcium fluoride (CaF2) plate was exposed to pulsed laser irradiations inducing surface morphological and ionization changes on its surface. More precisely surface damages mainly correspond to intrinsic defects. Electron paramagnetic resonance (EPR) hyperspectral imaging is a powerful technique able to characterize the defects formed on the CaF2 surface. Indeed, EPR hyperspectral images provide spatial and spectral information about the sample studied. In fact, these images possess a great potential to obtain accurate and reliable knowledge about the chemical composition and the distribution of the component due to the presence of the spatial aspect. However, the complexity of such hyperspectral data sets imposes the use of advanced chemometric tools to extract valuable information on the considered physicochemical system. Therefore, Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) is proposed to identify and locate the different constituents in the images. The originality of this work is that it reports on the application of MCR-ALS, for the first time, on electron paramagnetic resonance (EPR) imaging data sets that will furnish the distribution maps and the spectral signatures of all components present in the sample. The results show the identification of different intrinsic defects on a CaF2 sample from the sole information in the raw image measurements and, therefore, confirm the potential of this methodology and the important role of spatial information contained in the image.

  13. Functionality of veterinary identification microchips following low- (0.5 tesla) and high-field (3 tesla) magnetic resonance imaging.

    Science.gov (United States)

    Piesnack, Susann; Frame, Mairi E; Oechtering, Gerhard; Ludewig, Eberhard

    2013-01-01

    The ability to read patient identification microchips relies on the use of radiofrequency pulses. Since radiofrequency pulses also form an integral part of the magnetic resonance imaging (MRI) process, the possibility of loss of microchip function during MRI scanning is of concern. Previous clinical trials have shown microchip function to be unaffected by MR imaging using a field strength of 1 Tesla and 1.5. As veterinary MRI scanners range widely in field strength, this study was devised to determine whether exposure to lower or higher field strengths than 1 Tesla would affect the function of different types of microchip. In a phantom study, a total of 300 International Standards Organisation (ISO)-approved microchips (100 each of three different types: ISO FDX-B 1.4 × 9 mm, ISO FDX-B 2.12 × 12 mm, ISO HDX 3.8 × 23 mm) were tested in a low field (0.5) and a high field scanner (3.0 Tesla). A total of 50 microchips of each type were tested in each scanner. The phantom was composed of a fluid-filled freezer pack onto which a plastic pillow and a cardboard strip with affixed microchips were positioned. Following an MRI scan protocol simulating a head study, all of the microchips were accurately readable. Neither 0.5 nor 3 Tesla imaging affected microchip function in this study. © 2013 Veterinary Radiology & Ultrasound.

  14. Identification of the sites of chlorophyll triplet quenching in relation to the structure of LHC-II from higher plants. Evidence from EPR spectroscopy.

    Science.gov (United States)

    Di Valentin, Marilena; Biasibetti, Federico; Ceola, Stefano; Carbonera, Donatella

    2009-10-01

    The Chlorophyll a (Chl a) molecules involved in the triplet-triplet energy transfer to the central luteins in trimeric LHC-II are identified by time-resolved and pulse EPR techniques. The concept of spin angular momentum conservation during triplet-triplet energy transfer is exploited for the calculation of the spin polarization of the carotenoid triplet states. The sites with the highest probability of forming triplet states, which are quenched by the central luteins, result to be Chl603 and Chl612. "Unquenched" Chl triplet states are produced by photoexcitation in the LHC-II complex. Putative sites of these triplet states are Chl614, Chl611, Chl604, and Chl613 since they do not contribute to the formation of the observed carotenoid triplet states.

  15. EPR and optical absorption studies of Cr3+ ions in d-gluconic acid monohydrate.

    Science.gov (United States)

    Kripal, Ram; Singh, Pragya; Govind, Har

    2009-10-01

    EPR studies are carried out on Cr(3+) ions doped in d-gluconic acid monohydrate (C(6)H(12)O(7)*H(2)O) single crystals at 77 K. From the observed EPR spectra, the spin Hamiltonian parameters g, |D| and |E| are measured to be 1.9919, 349 (x 10(-4)) cm(-1) and 113 (x 10(-4)) cm(-1), respectively. The optical absorption of the crystal is also studied at room temperature. From the observed band positions, the cubic crystal field splitting parameter Dq (2052 cm(-1)) and the Racah interelectronic repulsion parameter B (653 cm(-1)) are evaluated. From the correlation of EPR and optical data the nature of bonding of Cr(3+) ion with its ligands is discussed.

  16. On Room-Temperature Inversion of EPR Signals of P1 Centre in Synthetic Diamond

    Institute of Scientific and Technical Information of China (English)

    G. G. Fedoruk; O. N. Poklonskaya

    2009-01-01

    Room-temperature inversion of EPR absorption signals of P1 centre in synthetic diamond is studied by the tran-sient nutation technique. Use of the bichromatic field, consisting of a transverse microwave field and longitudinal radio frequency field, allows to investigate the dynamics of P1 centres in the same field configuration as in cw EPR spectrometers. It is shown that the annealing decreases the P1 centre concentration and, respectively, increases the spin-spin relaxation time. As a result, the periodic inversion (nutation) of the P1 centre absorption signal is observed longer. It is assumed that the P1 centre signal inversion, which was previously observed by cw EPR, might be caused by the Bloch-Siegert effect in the biehromatic field.

  17. In vivo EPR: an effective new tool for studying pathophysiology, physiology and pharmacology

    Energy Technology Data Exchange (ETDEWEB)

    Maeder, K.; Swartz, H.M. [Dartmouth Univ., Hanover, NH (United States). Dept. of Radiology; Gallez, B. [Louvain Univ., Brussels (Belgium). Dept. of Medicinal Chemistry

    1996-11-01

    The development of spectrometers working at lower frequencies with improved resonators now permits the routine use of non-invasive EPR spectroscopy in vivo. The capabilities of EPR spectra to reflect environmental conditions, combined with the use of paramagnetic materials as selective non-toxic labels, has led to increasingly widespread and productive applications of the technique to complex problems involving physiology, pharmacology and pathophysiology. Some of the especially promising applications in which EPR techniques uniquely appear to provide valuable information are illustrated, including the measurement of oxygen and oxygen gradients, monitoring of the metabolism of xenobiotics, monitoring pharmacokinetics of drugs, measurement of perfusion, measurement of pH, recognition and labeling of receptors, and characterization of drug releasing systems. (author).

  18. EPR, UV-Visible, and Near-Infrared Spectroscopic Characterization of Dolomite

    Directory of Open Access Journals (Sweden)

    S. Lakshmi Reddy

    2008-01-01

    Full Text Available Dolomite mineral samples having white and light green colors of Indian origin have been characterized by EPR, optical, and NIR spectroscopy. The optical spectrum exhibits a number of electronic bands due to presence of Fe(III ions in the mineral. From EPR studies, the parameters of g for Fe(III and g,A, and D for Mn(II are evaluated and the data confirm that the ions are in distorted octahedron. Optical absorption studies reveal that Fe(III is in distorted octahedron. The bands in NIR spectra are due to the overtones and combinations of water molecules. Thus EPR and optical absorption spectral studies have proven useful for the study of the solid state chemistry of dolomite.

  19. EPR-Steering measure for two-mode continuous variable states

    CERN Document Server

    Kogias, Ioannis

    2014-01-01

    Steering is a manifestation of quantum correlations that embodies the Einstein-Podolsky-Rosen (EPR) paradox. While there have been recent attempts to quantify steering, continuous variable systems remained elusive. We introduce a steering measure for two-mode continuous variable systems that is valid for arbitrary states. The measure is based on the violation of an optimized variance test for the EPR paradox, and admits a computable and experimentally friendly lower bound only depending on the second moments of the state, which reduces to a recently proposed quantifier of steerability by Gaussian measurements. We further show that Gaussian states are extremal with respect to our measure, minimizing it among all continuous variable states with fixed second moments. As a byproduct of our analysis, we generalize and relate well-known EPR-steering criteria. Finally an operational interpretation is provided, as the proposed measure is shown to quantify the optimal guaranteed key rate in semi-device independent qua...

  20. Strong continuous variable EPR-steering with a detection efficiency above 96%

    CERN Document Server

    Steinlechner, Sebastian; Eberle, Tobias; Schnabel, Roman

    2011-01-01

    In 1935, Einstein, Podolsky, and Rosen reported a gedanken experiment which became famous as the EPR-paradox. In the same year, Schr\\"odinger introduced the terms entanglement and steering in order to describe the underlying effect that a measurement on subsystem A of a certain class of entangled states may apparently allow for a remote steering of the measurement outcome at subsystem B, without the presence of a physical interaction between the subsystems. In this work we report on the observation of unprecedented strong EPR-steering in the gaussian regime, quantified by an EPR co-variance product of about 0.04 < 1, where 1 is the critical value. Together with a high detection efficiency of more than 96%, our result is an important milestone towards applications of gaussian entanglement distribution.

  1. Study on EPR Spectra of Three Gadolinium Complexes With Noncyclic Polyether Schiff Bases

    Institute of Scientific and Technical Information of China (English)

    陈德余; 姚克敏; 封子先; 蔡乐真; 周佩芬; 薛祺

    1994-01-01

    The EPR spectra of three new gadolinium complexes with noncyclic polyether Schiff bases in powder and those of these complexes in organic solvents were investigated at different temperatures. It was observed that EPR spectra of nine and four peaks of Gd(Ⅲ) complexes in polycrystalline powder and freezing samples appeared at low temperature respectively for the first time. The interpretations of these results obtained on the basis of spin Hamiltonian of s = 7/2 system are satisfactory. The correlations of EPR feature between crystal-field strength in complexes and local symmetry around Gd3+ ions were revealed. The crystal-field parameters b20 and the asymmetry parameters λ’ of complexes were estimated. A series of interesting regularity and new results were obtained.

  2. Dosimetric characteristics of different types of saccharides: An EPR and UV spectrometric study

    Energy Technology Data Exchange (ETDEWEB)

    Karakirova, Y., E-mail: daniepr@ic.bas.b [Bulgarian Academy of Sciences, Institute of Catalysis, 1113 Sofia (Bulgaria); Yordanov, N.D. [Bulgarian Academy of Sciences, Institute of Catalysis, 1113 Sofia (Bulgaria); De Cooman, H.; Vrielinck, H.; Callens, F. [Ghent University, Department of Solid State Sciences, B-9000 Gent (Belgium)

    2010-05-15

    The time stability and dose response of the free radicals produced in various types of 'less-studied' mono- and disaccharides by gamma-radiation is studied by EPR (Electron Paramagnetic Resonance) and UV spectrometry. The time evolution of the shape of the EPR spectra of irradiated saccharides is investigated from 5 min to 5 months after irradiation. The intensity of the stable EPR signal is studied as a function of the absorbed gamma-dose in the range 0.5-20 kGy. Aqueous solutions of irradiated solid saccharides exhibit a UV absorption maximum in the range 250-290 nm. A linear dependency is found between the magnitude of the UV absorption maximum and the absorbed gamma-dose. The time stability of the UV absorption maximum is also studied for every saccharide. The results are compared with those obtained for irradiated sucrose.

  3. A reinvestigation of EXAFS and EPR spectroscopic measurements of chromium(VI) reduction by coir pith

    Energy Technology Data Exchange (ETDEWEB)

    Suksabye, Parinda [Department of Environmental Science, Faculty of Science and Technology, Suan Dusit Rajabhat University, 10300 (Thailand); Worasith, Niramon; Thiravetyan, Paitip [Division of Biotechnology, School of Bioresources and Technology King Mongkut' s University of Technology, Thonburi, Bangkhuntien, Bangkok (Thailand); Nakajima, Akira [Division of Chemistry, Department of Medical Science, Faculty of Medicine, University of Miyazaki, Kiyotake, Miyazaki 8891692 (Japan); Goodman, Bernard A., E-mail: bernard_a_goodman@yahoo.com [Health and Environment Department, Unit of Environmental Resources and Technologies, Austrian Institute of Technology, Seibersdorf A-2444 (Austria)

    2010-08-15

    New measurements using extended X-ray absorption fine structure (EXAFS) and electron paramagnetic resonance (EPR) techniques are consistent with Cr in the Cr(III) oxidation state as the main product from the adsorption of Cr(VI) on coir pith. These confirm the previous X-ray measurements, but differ from the results of previous EPR studies, which indicated that Cr(V) was the main form of Cr. The reason for this discrepancy is the presence of a broad signal from Cr(III) in an unsymmetrical environment that was missed previously; the Cr(V) component is in fact only a minor reaction product. As a result of this problem with spectral acquisition and interpretation, some simple recommendations are presented for conducting EPR investigations on natural systems.

  4. A reinvestigation of EXAFS and EPR spectroscopic measurements of chromium(VI) reduction by coir pith.

    Science.gov (United States)

    Suksabye, Parinda; Worasith, Niramon; Thiravetyan, Paitip; Nakajima, Akira; Goodman, Bernard A

    2010-08-15

    New measurements using extended X-ray absorption fine structure (EXAFS) and electron paramagnetic resonance (EPR) techniques are consistent with Cr in the Cr(III) oxidation state as the main product from the adsorption of Cr(VI) on coir pith. These confirm the previous X-ray measurements, but differ from the results of previous EPR studies, which indicated that Cr(V) was the main form of Cr. The reason for this discrepancy is the presence of a broad signal from Cr(III) in an unsymmetrical environment that was missed previously; the Cr(V) component is in fact only a minor reaction product. As a result of this problem with spectral acquisition and interpretation, some simple recommendations are presented for conducting EPR investigations on natural systems.

  5. BCL::MP-Fold: membrane protein structure prediction guided by EPR restraints

    CERN Document Server

    Fischer, Axel Walter; Woetzel, Nils; Karakas, Mert; Weiner, Brian; Meiler, Jens

    2015-01-01

    For many membrane proteins the determination of their topology remains a challenge for methods like X-ray crystallography and nuclear magnetic resonance (NMR) spectroscopy. Electron paramagnetic resonance (EPR) spectroscopy has evolved as an alternative technique to study structure and dynamics of membrane proteins. The present study demonstrates the feasibility of membrane protein topology determination using limited EPR distance and accessibility measurements. The BCL::MP-Fold (BioChemical Library membrane protein fold) algorithm assembles secondary structure elements (SSEs) in the membrane using a Monte Carlo Metropolis (MCM) approach. Sampled models are evaluated using knowledge-based potential functions and agreement with the EPR data and a knowledge-based energy function. Twenty-nine membrane proteins of up to 696 residues are used to test the algorithm. The RMSD100 value of the most accurate model is better than 8{\\AA} for twenty-seven, better than 6{\\AA} for twenty-two and better than 4{\\AA} for fifte...

  6. EPR studies on branched high-spin arylnitrenes.

    Science.gov (United States)

    Chapyshev, Sergei V; Korchagin, Denis V; Budyka, Mikhail F; Gavrishova, Tatiana N; Neuhaus, Patrik; Sander, Wolfram

    2012-08-06

    The UV (λ>305 nm) photolysis of triazide 3 in 2-methyl-tetrahydrofuran glass at 7 K selectively produces triplet mononitrene 4 (g=2.003, D(T)=0.92 cm(-1), E(T)=0 cm(-1)), quintet dinitrene 6 (g=2.003, D(Q)=0.204 cm(-1), E(Q)=0.035 cm(-1)), and septet trinitrene 8 (g=2.003, D(S)=-0.0904 cm(-1), E(S) =-0.0102 cm(-1)). After 45 min of irradiation, the major products are dinitrene 6 and trinitrene 8 in a ratio of ∼1:2, respectively. These nitrenes are formed as mixtures of rotational isomers each of which has slightly different magnetic parameters D and E. The best agreement between the line-shape spectral simulations and the experimental electron paramagnetic resonance (EPR) spectrum is obtained with the line-broadening parameters Γ(E(Q))=180 MHz for dinitrene 6 and Γ(E(S))=330 MHz for trinitrene 8. According to these line-broadening parameters, the variations of the angles Θ in rotational isomers of 6 and 8 are expected to be about ±1 and ±3°, respectively. Theoretical estimations of the magnetic parameters obtained from PBE/DZ(COSMO)//UB3LYP/6-311+G(d,p) calculations overestimate the E and D values by 1 and 8 %, respectively. Despite the large distances between the nitrene units and the extended π systems, the zero field splitting (zfs) parameters D are found to be close to those in quintet dinitrenes and septet trinitrenes, where the nitrene centers are attached to the same aryl ring. The large D values of branched septet nitrenes are due to strong negative one-center spin-spin interactions in combination with weak positive two-center spin-spin interactions, as predicted by theoretical considerations. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Inter-spin distance determination using L-band (1-2 GHz) non-adiabatic rapid sweep electron paramagnetic resonance (NARS EPR)

    Science.gov (United States)

    Kittell, Aaron W.; Hustedt, Eric J.; Hyde, James S.

    2012-08-01

    Site-directed spin-labeling electron paramagnetic resonance (SDSL EPR) provides insight into the local structure and motion of a spin probe strategically attached to a molecule. When a second spin is introduced to the system, macromolecular information can be obtained through measurement of inter-spin distances either by continuous wave (CW) or pulsed electron double resonance (ELDOR) techniques. If both methodologies are considered, inter-spin distances of 8-80 Å can be experimentally determined. However, there exists a region at the upper limit of the conventional X-band (9.5 GHz) CW technique and the lower limit of the four-pulse double electron-electron resonance (DEER) experiment where neither method is particularly reliable. The work presented here utilizes L-band (1.9 GHz) in combination with non-adiabatic rapid sweep (NARS) EPR to address this opportunity by increasing the upper limit of the CW technique. Because L-band linewidths are three to seven times narrower than those at X-band, dipolar broadenings that are small relative to the X-band inhomogeneous linewidth become observable, but the signal loss, due to the frequency dependence of the Boltzmann factor, has made L-band especially challenging. NARS has been shown to increase sensitivity by a factor of five, and overcomes much of this loss, making L-band distance determination more feasible [1]. Two different systems are presented, and distances of 18-30 Å have been experimentally determined at physiologically relevant temperatures. Measurements are in excellent agreement with a helical model and values determined by DEER.

  8. EPR and optical study of Mn{sup 2+} doped monohydrated dipotassium stannic chloride

    Energy Technology Data Exchange (ETDEWEB)

    Kripal, Ram, E-mail: ram_kripal2001@rediffmail.com; Singh, Manju

    2014-11-15

    Highlights: • EPR study of Mn{sup 2+}: DPSC crystal is done at room temperature. • The spin Hamiltonian parameters for two Mn{sup 2+} sites are determined. • The optical absorption study is also done. • The nature of metal–ligand bonding is discussed on the basis of EPR and optical data. • Theoretical zero-field splitting parameters match well with the experimental values. - Abstract: Electron paramagnetic resonance (EPR) study at room temperature (RT) is used to investigate the property of Mn{sup 2+} doped monohydrated dipotassium stannic chloride (K{sub 2}SnCl{sub 4}⋅H{sub 2}O) single crystal. EPR spectra show that there exist two substitutional sites, the spin Hamiltonian parameters for which are determined. The optical absorption study is also done at room temperature in the wavelength range 195–1100 nm. The observed bands are assigned as transitions from {sup 6}A{sub 1g}(S) ground state to various excited states. These bands are fitted with four parameters, namely Racah inter-electronic repulsion parameters B = 792 cm{sup −1}, C = 2278 cm{sup −1}; cubic crystal field splitting parameter Dq = 700 cm{sup −1} and Trees correction α = 76 cm{sup −1}. The nature of metal–ligand bonding is discussed on the basis of EPR and optical data. Superposition model (SPM) is used to find out the crystal field (CF) parameters and the perturbation formulae are used to obtain zero-field splitting (ZFS) parameters. Theoretically calculated ZFS parameters match well with the experimental values obtained from EPR study.

  9. Application of EPR spectroscopy to identify irradiated Indian medicinal plant products.

    Science.gov (United States)

    Sanyal, Bhaskar; Chatterjee, S; Variyar, Prasad S; Sharma, Arun

    2012-06-01

    A study of gamma-irradiated Indian medicinal plant products was carried out using electron paramagnetic resonance (EPR) spectroscopy. Improved approaches like high-power measurement, microwave saturation, and thermal behavior of the radicals were explored for detection of irradiation. Aswagandha (Withania somnifera), vairi (Salacia reticulata), amla (Emblica officinalis), haldi (Curcumin longa), and guduchi (Tinospora cordifolia) exhibited a weak singlet at g = 2.005 before irradiation. Aswagandha, immediately after radiation treatment, revealed a complex EPR spectrum characterized by EPR spectrum simulation technique as superposition of 3 paramagnetic centers. One group of signal with organic origin was carbohydrate and cellulose radical and the other was isotropic signal of inorganic origin (g⟂ =2.0044 and g|| = 1.9980). However, other products did not exhibit any radiation-specific signal after irradiation. Power saturation and thermal behavior techniques were not suitable for these products. However, amongst all the 3 approaches, high-power measurement of EPR spectra emerged as a suitable technique in identification of the irradiated aswagandha. Gamma-irradiation confirms hygienic quality and improves shelf life of food and other products. However, there is a lack of international consensus over considering this as a general application and different regulations are being enforced. EPR is one of the most promising techniques to identify irradiated foodstuffs for regulatory requirements but it has many limitations. Improved approaches based on the EPR technique explained in this study may be useful to identify irradiated products and become beneficial to food regulators and food irradiation enterprises to enhance confidence in irradiation technology. © 2012 Institute of Food Technologists®

  10. EPR dosimetry of teeth in past and future accidents: a prospective look at a retrospective method

    Energy Technology Data Exchange (ETDEWEB)

    Haskell, E.H.; Kenner, G.H.; Hayes, R.B. [Utah Univ., Salt Lake City, UT (United States). Center for Applied Dosimetry; Chumak, V.; Shalom, S. [All-Union Scientific Centre of Radiation Medicine, Kiev (Ukraine)

    1996-01-01

    Electron paramagnetic resonance spectroscopy (EPR) of tooth enamel is a relatively new technique for retrospective dosimetry that in the past two years has seen increasing effort towards its development and evaluation. Efforts have centered on determining the accuracy which may be achieved with current measurement techniques as well as the minimum doses detectable. The study was focused on evaluating some factors which influence the accuracy of EPR dosimetry of enamel. Reported are studies on sample intercomparisions, instrumental considerations, and effects of dental x-rays, environmental sunlight and ultraviolet radiation.

  11. Formates and dithionates: sensitive EPR-dosimeter materials for radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Lund, E. [Department of Medicine and Care, Radiation Physics, Faculty of Health Sciences, University of Linkoeping, S-581 85 Linkoeping (Sweden)]. E-mail: eva.lund@imv.liu.se; Gustafsson, H. [Department of Medicine and Care, Radiation Physics, Faculty of Health Sciences, University of Linkoeping, S-581 85 Linkoeping (Sweden); Danilczuk, M. [Chemical Physics Laboratory, IFM, University of Linkoeping, S-581 83 Linkoeping (Sweden); Sastry, M.D. [Chemical Physics Laboratory, IFM, University of Linkoeping, S-581 83 Linkoeping (Sweden); Lund, A. [Chemical Physics Laboratory, IFM, University of Linkoeping, S-581 83 Linkoeping (Sweden); Vestad, T.A. [Department of Physics, University of Oslo, P.O. Box 1048 Blindern, N-0316 Oslo (Norway); Malinen, E. [Department of Physics, University of Oslo, P.O. Box 1048 Blindern, N-0316 Oslo (Norway); Hole, E.O. [Department of Physics, University of Oslo, P.O. Box 1048 Blindern, N-0316 Oslo (Norway); Sagstuen, E. [Department of Physics, University of Oslo, P.O. Box 1048 Blindern, N-0316 Oslo (Norway)

    2005-02-01

    Polycrystalline formates and dithionates are promising materials for EPR dosimetry, as large yields of radiation induced stable radicals are formed with a linear dose response. Rapid spin relaxation rates were detected in many of the substances, indicating that a high microwave power can be applied during EPR acquisition in order to improve sensitivity. Different techniques used to further improve the sensitivity, such as the replacement of {sup 7}Li with {sup 6}Li or exchange of protons with deuterons in the corresponding crystalline matrices and metal ion doping are discussed. It is concluded that formates and dithionates may be up to 10 times as sensitive as L-{alpha}-alanine.

  12. Theoretical investigation of the optical and EPR parameters for VO 2+ion in some complexes

    Science.gov (United States)

    Kalfaoğlu, Emel; Karabulut, Bünyamin

    2012-04-01

    The molecular orbital coefficients and the EPR parameters of trisodium citrate dihydrate, sodium hydrogen oxalate monohydrate, potassium d-gluconate monohydrate and L-Alanine vanadyl complexes are calculated theoretically. Two d-d transition spectra and EPR parameters for the VO2+ complex are calculated theoretically by using crystal-field theory. The calculated g and A paramaters have indicated that paramagnetic center is axially symmetric. Having the relations of g∥A⊥ for VO2+ ions, it can be concluded that VO2+ ions are located in distorted octahedral sites (C4v) elongated along the z-axis and the ground state of the paramagnetic electron is dxy.

  13. EPR, UV-Visible, and Near-Infrared Spectroscopic Characterization of Dolomite

    OpenAIRE

    S. Lakshmi Reddy; Frost, R. L.; G. Sowjanya; Reddy, N. C. G.; G. Siva Reddy; Reddy, B. J.

    2008-01-01

    Dolomite mineral samples having white and light green colors of Indian origin have been characterized by EPR, optical, and NIR spectroscopy. The optical spectrum exhibits a number of electronic bands due to presence of Fe(III) ions in the mineral. From EPR studies, the parameters of g for Fe(III) and g,A, and D for Mn(II) are evaluated and the data confirm that the ions are in distorted octahedron. Optical absorption studies reveal that Fe(III) is in distorted octahedron. The bands in NIR spe...

  14. EFFECT OF CADMIUM(II) ON FREE RADICALS IN DOPA-MELANIN TESTED BY EPR SPECTROSCOPY.

    Science.gov (United States)

    Zdybel, Magdalena; Pilawa, Barbara; Chodurek, Ewa

    2015-01-01

    Electron paramagnetic resonance (EPR) spectroscopy may be applied to examine interactions of melanin with metal ions and drugs. In this work EPR method was used to examination of changes in free radical system of DOPA-melanin--the model eumelanin after complexing with diamagnetic cadmium(II) ions. Cadmium(II) may affect free radicals in melanin and drugs binding by this polymer, so the knowledge of modification of properties and free radical concentration in melanin is important to pharmacy. The effect of cadmium(II) in different concentrations on free radicals in DOPA-melanin was determined. EPR spectra of DOPA-melanin, and DOPA-melanin complexes with cadmium(II) were measured by an X-band (9.3 GHz) EPR spectrometer produced by Radiopan (Poznań, Poland) and the Rapid Scan Unit from Jagmar (Krak6w, Poland). The DOPA (3,4-dihydroxyphenylalanine) to metal ions molar ratios in the reaction mixtures were 2:1, 1:1, and 1: 2. High concentrations of o-semiquinone (g ~2.0040) free radicals (~10(21)-10(22) spin/g) characterize DOPA-melanin and its complexes with cadmium(II). Formation of melanin complexes with cadmium(II) increase free radical concentration in DOPA-melanin. The highest free radical concentration was obtained for DOPA-melanin-cadmium(II) (1:1) complexes. Broad EPR lines with linewidths: 0.37-0.73 mT, were measured. Linewidths increase after binding of cadmium(II) to melanin. Changes of integral intensities and linewidths with increasing microwave power indicate the homogeneous broadening of EPR lines, independently on the metal ion concentration. Slow spin-lattice relaxation processes existed in all the tested samples, their EPR lines saturated at low microwave powers. Cadmium(II) causes fastening of spin-lattice relaxation processes in DOPA-melanin. The EPR results bring to light the effect of cadmium(II) on free radicals in melanin, and probably as the consequence on drug binding to eumelanin.

  15. High-field studies of quantum oscillations in quasi-two-dimensional organic metals

    Science.gov (United States)

    Sandhu, Pravindrajit

    The organic metals derived from the molecule BEDT-TTF (or ET for short) are important as model systems for the study of low-dimensional phenomena. These materials are molecular crystals with a low Fermi energy (10--100 meV), high mobility (˜104 cm2/Vs) and highly anisotropic Fermi surfaces. We have conducted experimental studies of ( i) the Shubnikov-de Haas (SdH) effect in pulsed fields up to 50 T and (ii) the de Haas-van Alphen (dHvA) effect in steady fields up to 33 T on alpha - (ET)2 MHg(SCN) 4 (where M = K, Tl and NH4) and kappa - (ET)2 Cu (NCS)2. At these high fields, the wave shape as well as the temperature and field-dependence of the oscillations deviate from the behavior predicted by the standard Lifshitz-Kosevich theory. These measurements reveal the limits of the conventional theory of metals and lay the ground-work for extending the theory to low-dimensional systems. We have also performed extended Huckel tight-binding calculations to model the effects of pressure and uniaxial stress on the electronic band structure of kappa - (ET)2 KHg (SCN)4 and kappa - (ET)2 Cu (NCS)2. The calculated changes in the Fermi surface topology are in excellent agreement with the experimental values determined from SdH measurements. We also report predictions of the effects of uniaxial stress in the transverse directions and discuss the behavior of the effective mass and magnetic breakdown probability. Finally, we have investigated the origin of anomalous magnetic breakdown frequencies in the dHvA effect that are forbidden according to semi-classical theories. We construct a tight-binding model based on the realistic band-structure of the system, which is then solved numerically to compute the field-dependence of the magnetization. This model provides a natural description for the phenomenon of magnetic breakdown between co-existing closed and open Fermi surfaces and accounts for the anomalous frequencies that are observed experimentally. The occurrence of these

  16. PULSE COLUMN

    Science.gov (United States)

    Grimmett, E.S.

    1964-01-01

    This patent covers a continuous countercurrent liquidsolids contactor column having a number of contactor states each comprising a perforated plate, a layer of balls, and a downcomer tube; a liquid-pulsing piston; and a solids discharger formed of a conical section at the bottom of the column, and a tubular extension on the lowest downcomer terminating in the conical section. Between the conical section and the downcomer extension is formed a small annular opening, through which solids fall coming through the perforated plate of the lowest contactor stage. This annular opening is small enough that the pressure drop thereacross is greater than the pressure drop upward through the lowest contactor stage. (AEC)

  17. Magnet Science and Technology for Basic Research at the High Field Laboratory for Superconducting Materials

    Institute of Scientific and Technical Information of China (English)

    渡辺和雄

    2007-01-01

    Since the first practical cryocooled superconducting magnet using a GM-cryocooler and high temperature superconducting current leads has been demonstrated successfully at the High Field Laboratory for Superconducting Materials (HFLSM), various kinds of cryocooled superconducting magnets in fields up to 15 T have been used to provide access for new research areas in fields of magneto-science. Recently, the HFLSM has succeeded in demonstrating a cryocooed 18 T high temperature superconducting magnet and a high field cryocooled 27.5 T hybrid magnet. Cryocooled magnet technology and basic research using high field magnets at the HFLSM are introduced.

  18. HF-EPR, Raman, UV/VIS Light Spectroscopic, and DFT Studies of the Ribonucleotide Reductase R2 Tyrosyl Radical from Epstein-Barr Virus

    Science.gov (United States)

    Tomter, Ane B.; Zoppellaro, Giorgio; Schmitzberger, Florian; Andersen, Niels H.; Barra, Anne-Laure; Engman, Henrik; Nordlund, Pär; Andersson, K. Kristoffer

    2011-01-01

    Epstein-Barr virus (EBV) belongs to the gamma subfamily of herpes viruses, among the most common pathogenic viruses in humans worldwide. The viral ribonucleotide reductase small subunit (RNR R2) is involved in the biosynthesis of nucleotides, the DNA precursors necessary for viral replication, and is an important drug target for EBV. RNR R2 generates a stable tyrosyl radical required for enzymatic turnover. Here, the electronic and magnetic properties of the tyrosyl radical in EBV R2 have been determined by X-band and high-field/high-frequency electron paramagnetic resonance (EPR) spectroscopy recorded at cryogenic temperatures. The radical exhibits an unusually low g1-tensor component at 2.0080, indicative of a positive charge in the vicinity of the radical. Consistent with these EPR results a relatively high C-O stretching frequency associated with the phenoxyl radical (at 1508 cm−1) is observed with resonance Raman spectroscopy. In contrast to mouse R2, EBV R2 does not show a deuterium shift in the resonance Raman spectra. Thus, the presence of a water molecule as a hydrogen bond donor moiety could not be identified unequivocally. Theoretical simulations showed that a water molecule placed at a distance of 2.6 Å from the tyrosyl-oxygen does not result in a detectable deuterium shift in the calculated Raman spectra. UV/VIS light spectroscopic studies with metal chelators and tyrosyl radical scavengers are consistent with a more accessible dimetal binding/radical site and a lower affinity for Fe2+ in EBV R2 than in Escherichia coli R2. Comparison with previous studies of RNR R2s from mouse, bacteria, and herpes viruses, demonstrates that finely tuned electronic properties of the radical exist within the same RNR R2 Ia class. PMID:21980375

  19. HF-EPR, Raman, UV/VIS light spectroscopic, and DFT studies of the ribonucleotide reductase R2 tyrosyl radical from Epstein-Barr virus.

    Directory of Open Access Journals (Sweden)

    Ane B Tomter

    Full Text Available Epstein-Barr virus (EBV belongs to the gamma subfamily of herpes viruses, among the most common pathogenic viruses in humans worldwide. The viral ribonucleotide reductase small subunit (RNR R2 is involved in the biosynthesis of nucleotides, the DNA precursors necessary for viral replication, and is an important drug target for EBV. RNR R2 generates a stable tyrosyl radical required for enzymatic turnover. Here, the electronic and magnetic properties of the tyrosyl radical in EBV R2 have been determined by X-band and high-field/high-frequency electron paramagnetic resonance (EPR spectroscopy recorded at cryogenic temperatures. The radical exhibits an unusually low g₁-tensor component at 2.0080, indicative of a positive charge in the vicinity of the radical. Consistent with these EPR results a relatively high C-O stretching frequency associated with the phenoxyl radical (at 1508 cm⁻¹ is observed with resonance Raman spectroscopy. In contrast to mouse R2, EBV R2 does not show a deuterium shift in the resonance Raman spectra. Thus, the presence of a water molecule as a hydrogen bond donor moiety could not be identified unequivocally. Theoretical simulations showed that a water molecule placed at a distance of 2.6 Å from the tyrosyl-oxygen does not result in a detectable deuterium shift in the calculated Raman spectra. UV/VIS light spectroscopic studies with metal chelators and tyrosyl radical scavengers are consistent with a more accessible dimetal binding/radical site and a lower affinity for Fe²⁺ in EBV R2 than in Escherichia coli R2. Comparison with previous studies of RNR R2s from mouse, bacteria, and herpes viruses, demonstrates that finely tuned electronic properties of the radical exist within the same RNR R2 Ia class.

  20. Characteristics and economy of the European reactor of pressurized water (EPR); Caracteristicas y economia del reactor europeo de agua a presion (EPR)

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz V, J.; Ramirez S, J.R.; Palacios H, J.C. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)]. e-mail: jov@nuclear.inin.mx

    2005-07-01

    The high current costs of the fossil fuels, have propitiated that the industries of electric power generation in the world reconsider the nuclear option as medium of generation. In Europe, the more recently contracted nuclear power plant is that of Olkiluoto-III in Finland that waits it enters in operation at the end of 2009. The reactor that will be installed in this power plant will be a prototype of pressurized water reactor of the companies AREVA and EDF. In this work they are described the reactor EPR and the major components of the nuclear power plant as well as the main characteristics of safety and the flexibility of the operation of the EPR. The supposed costs reported in different sources of information are also described and calculated with information provided by the manufacturer company. (Author)

  1. Polypropylene/ethylene-propylene rubber (PP/EPR blends for the automotive industry: Basic correlations between EPR-design and shrinkage

    Directory of Open Access Journals (Sweden)

    G. D. Potter

    2014-04-01

    Full Text Available The influence of the phase morphology on the shrinkage of injection molded plates from reactor based PP/EPR blends was investigated using a model series. The morphology of the dispersed phase – in terms of size and shape of the rubber particles as determined from scanning electron microscopy (SEM – was found to correlate fairly well with the shrinkage determined in the flow and transverse direction of injection molded plates. In this respect it turned out to be elementary to consider the anisotropy of the particles rather than their average size alone. Additionally, the effect of the EPR design on the coefficient of linear thermal expansion (CLTE was evaluated and brought into a relationship with the blend morphology.

  2. Site directed spin labelling and pulsed dipolar electron paramagnetic resonance (double electron-electron resonance) of force activation in muscle

    Energy Technology Data Exchange (ETDEWEB)

    Fajer, Piotr G [Institute of Molecular Biophysics, Department of Biological Science, National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310 (United States)

    2005-05-11

    The recent development of site specific spin labelling and advances in pulsed electron paramagnetic resonance(EPR) have established spin labelling as a viable structural biology technique. Specific protein sites or whole domains can be selectively targeted for spin labelling by cysteine mutagenesis. The secondary structure of the proteins is determined from the trends in EPR signals of labels attached to consecutive residues. Solvent accessibility or label mobility display periodicities along the labelled polypeptide chain that are characteristic of {beta}-strands (periodicity of 2 residues) or {alpha}-helices (3.6 residues). Low-resolution 3D structure of proteins is determined from the distance restraints. Two spin labels placed within 60-70 A of each other create a local dipolar field experienced by the other spin labels. The strength of this field is related to the interspin distance, {proportional_to} r{sup -3}. The dipolar field can be measured by the broadening of the EPR lines for the short distances (8-20 A) or for the longer distances (17-70 A) by the pulsed EPR methods, double electron-electron resonance(DEER) and double quantum coherence (DQC). A brief review of the methodology and its applications to the multisubunit muscle protein troponin is presented below.

  3. EPR spectrum of the Y@C82 metallofullerene isolated in solid argon matrix: hyperfine structure from EPR spectroscopy and relativistic DFT calculations.

    Science.gov (United States)

    Misochko, Eugenii Ya; Akimov, Alexander V; Belov, Vasilii A; Tyurin, Daniil A; Bubnov, Vyacheslav P; Kareev, Ivan E; Yagubskii, Eduard B

    2010-08-21

    The EPR spectrum of the Y@C(82) molecules isolated in solid argon matrix was recorded for the first time at a temperature of 5 K. The isotropic hyperfine coupling constant (hfcc) A(iso) = 0.12 +/- 0.02 mT on the nucleus (89)Y as derived from the EPR spectrum is found in more than two times greater than that obtained in previous EPR measurements in liquid solutions. Comparison of the measured hfcc on a metal atom with that predicted by density-functional theory calculations (PBE/L22) indicate that relativistic method provides good agreement between experiment in solid argon and theory. Analysis of the DFT calculated dipole-dipole hf-interaction tensor and electron spin distribution in the endometallofullerenes with encaged group 3 metal atoms Sc, Y and La has been performed. It shows that spin density on the scandium atom represents the Sc d(yz) orbital lying in the symmetry plane of the C(2v) fullerene isomer and interacting with two carbon atoms located in the para-position on the fullerene hexagon. In contrast, the configuration of electron spin density on the heavier atoms, Y and La, is associated with the hybridized orbital formed by interaction of the metal d(yz) and p(y) electronic orbitals.

  4. Studies on the reliability of high-field intra-operative MRI in brain glioma resection

    Directory of Open Access Journals (Sweden)

    Zhi-jun SONG

    2011-07-01

    Full Text Available Objective To evaluate the reliability of high-field intra-operative magnetic resonance imaging(iMRI in detecting the residual tumors during glioma resection.Method One hundred and thirty-one cases of brain glioma(69 males and 62 females,aged from 7 to 79 years with mean of 39.6 years hospitalized from Nov.2009 to Aug.2010 were involved in present study.All the patients were evaluated using magnetic resonance imaging(MRI before the operation.The tumors were resected under conventional navigation microscope,and the high-field iMRI was used for all the patients when the operators considered the tumor was satisfactorily resected,while the residual tumor was difficult to detect under the microscope,but resected after being revealed by high-field iMRI.Histopathological examination was performed.The patients without residual tumors recieved high-field MRI scan at day 4 or 5 after operation to evaluate the accuracy of high-field iMRI during operation.Results High quality intra-operative images were obtained by using high-field iMRI.Twenty-eight cases were excluded because their residual tumors were not resected due to their location too close to functional area.Combined with the results of intra-operative histopathological examination and post-operative MRI at the early recovery stage,the sensitivity of high-field iMRI in residual tumor diagnosis was 98.0%(49/50,the specificity was 94.3%(50/53,and the accuracy was 96.1%(99/103.Conclusion High-quality intra-operative imaging could be acquired by high-field iMRI,which maybe used as a safe and reliable method in detecting the residual tumors during glioma resection.

  5. Correlating hemodynamic magnetic resonance imaging with high-field intracranial vessel wall imaging in stroke.

    Science.gov (United States)

    Langdon, Weston; Donahue, Manus J; van der Kolk, Anja G; Rane, Swati; Strother, Megan K

    2014-06-01

    Vessel wall magnetic resonance imaging at ultra-high field (7 Tesla) can be used to visualize vascular lesions noninvasively and holds potential for improving stroke-risk assessment in patients with ischemic cerebrovascular disease. We present the first multi-modal comparison of such high-field vessel wall imaging with more conventional (i) 3 Tesla hemodynamic magnetic resonance imaging and (ii) digital subtraction angiography in a 69-year-old male with a left temporal ischemic infarct.

  6. A study of high field quantum electrodynamics in the collision of high energy electrons with a terawatt laser

    Energy Technology Data Exchange (ETDEWEB)

    Horton-Smith, G.A.

    1998-07-01

    An experiment is described which studied quantum electrodynamic interactions under conditions of extremely high fields, along with a review of the relevant theory. The high fields were created by an intense, tightly-focused pulse of laser light at green or infrared wavelengths, into which was sent an ultra-relativistic electron beam of 46.6-GeV energy. The relevant theory is that of an electron in an electromagnetic wave so intense that the electron's mass is effectively shifted by the transverse momentum imparted to it by the wave, and the electron encounters field strengths comparable to the Schwinger critical field strength of 511 kV per Compton wavelength. An electron in the intense wave may radiate a photon and balance 4-momentum by absorbing multiple photons from the laser, which can lead to real photons with energies above the kinematic limit for conventional Compton scattering. All particles have significant probability of scattering multiple times while in the focus of the laser, including the photons radiated by the electrons, which may convert into electron-positron pairs, again with absorption of multiple photons from the laser. This experiment was able to measure the rates and spectra of positrons, electrons, and photons emerging from the interaction region. Results from both experiment and theoretical simulations are presented and compared. The results from the electron and positron measurements are compatible with the accepted theory, within experimental uncertainties due mainly to the laser intensity measurement. The photon spectrum shows the correct shape, but the ratio of rates in the linear and two-absorbed-photon portions of the spectrum does not vary as expected with the laser intensity, suggesting a disagreement with the accepted theory, with a significance of roughly two standard deviations. A follow-up experiment would be in order.

  7. Irradiated bivalve mollusks: Use of EPR spectroscopy for identification and dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Alberti, Angelo, E-mail: aalberti@isof.cnr.it [CNR-ISOF, Area della Ricerca di Bologna, Via P. Gobetti 101, Bologna I-40129 (Italy); Chiaravalle, Eugenio [Istituto Zooprofilattico Sperimentale della Puglia e Basilicata, Via Manfredonia 20, Foggia I-71100 (Italy); Fuochi, Piergiorgio; Macciantelli, Dante [CNR-ISOF, Area della Ricerca di Bologna, Via P. Gobetti 101, Bologna I-40129 (Italy); Mangiacotti, Michele, E-mail: michelemangiacotti@libero.it [Istituto Zooprofilattico Sperimentale della Puglia e Basilicata, Via Manfredonia 20, Foggia I-71100 (Italy); Marchesani, Giuliana [Istituto Zooprofilattico Sperimentale della Puglia e Basilicata, Via Manfredonia 20, Foggia I-71100 (Italy); Plescia, Elena [CNR-ISOF, Area della Ricerca di Bologna, Via P. Gobetti 101, Bologna I-40129 (Italy)

    2011-12-15

    High energy radiation treatment of foodstuff for microbial control and shelf-life extension is being used in many countries. However, for consumer protection and information, the European Union has adopted the Directives 1999/2/EC and 1999/3/EC to harmonize the rules concerning the treatment and trade of irradiated foods in EU countries. Among the validated methods to detect irradiated foods the EU directives also include Electron Paramagnetic Resonance (EPR/ESR) spectroscopy. We describe herein the use of EPR for identification of four species of bivalve mollusks, i.e. brown Venus shells (Callista chione), clams (Tapes semidecussatus), mussels (Mytilus galloprovincialis) and oysters (Ostrea edulis) irradiated with {sup 60}Co {gamma}-rays. EPR could definitely identify irradiated seashells due to the presence of long-lived free radicals, primarily CO{sub 2}{sup -}, CO{sub 3}{sup 3-}, SO{sub 2}{sup -} and SO{sub 3}{sup -} radical anions. The presence of other organic free radicals, believed to originate from conchiolin, a scleroprotein present in the shells, was also ascertained. The use of one of these radicals as a marker for irradiation of brown Venus shells and clams can be envisaged. We also propose a dosimetric protocol for the reconstruction of the administered dose in irradiated oysters. - Highlights: > EPR spectroscopy is confirmed a valuable identification tool for irradiated mollusks. > A conchiolin-derived radical can be used as irradiation marker for some mollusks. > A reliable protocol is outlined for dose reconstruction of irradiated oysters.

  8. Recent results of EPR and Moessbauer investigations on lattice dynamics in ammonium sulphate

    CERN Document Server

    Grecu, M N; Grecu, V V

    2003-01-01

    Recent results of the lattice dynamics investigation on ammonium sulfate are reported based on recent experiments carried out using using the non-destructive experimental technique of EPR and NGR. The main results confirm the presence and the contribution of a soft mode, which accompanied the paraferroelectric phase transition in the investigated crystal. (authors)

  9. Study of Thermal Properties of Mixed (PP/EPR/ABS with Five Model Compatibilizers

    Directory of Open Access Journals (Sweden)

    Pierre Marcel Anicet Noah

    2016-01-01

    Full Text Available The influences of incorporating compatibilizers E-EA-MAH, E-MA-GMA, E-AM, SEBS KRATON G, or PP-g-MAH on the thermal properties of mixed (polypropylene/ethylene propylene rubber/acrylonitrile butadiene styrene (PP/EPR/ABS have been investigated. DSC investigations have revealed that the incorporation of 5% of ABS in the copolymer (PP/EPR does not fundamentally affect the thermal properties of the basic copolymer; additionally, the addition of 1.5% of each of the compatibilizers in the basic mixture does not significantly alter the crystallization temperature values and the melting of the -P- sequences. There is a variation of melting enthalpy values of the -P- sequences of 18.23% using SEBS KRATON G and of 10.38% using E-AM-GMA. When the rate of each of the compatibilizers increases to 5%, overall crystallization enthalpies of -P- sequences are almost kept unchanged, except for the case of using the compatibilizer E-AM-GMA with a variation of 8.42%. There is a minor variation of the melting enthalpy of -P- sequences with higher levels of compatibilizer. The incorporation of 5% ABS copolymer in the PP/EPR does not significantly alter the thermal properties of the basic structure of (PP/EPR/ABS.

  10. Measuring precarious employment in times of crisis: the revised Employment Precariousness Scale (EPRES in Spain

    Directory of Open Access Journals (Sweden)

    Alejandra Vives

    2015-09-01

    Conclusion: The revised version of the EPRES demonstrated good metric properties and improved sensitivity to worker vulnerability and employment instability among permanent workers. Furthermore, it was sensitive to increased levels of precariousness in some dimensions despite decreases in others, demonstrating responsiveness to the context of the economic crisis affecting the Spanish labour market.

  11. BCL::MP-fold: Membrane protein structure prediction guided by EPR restraints.

    Science.gov (United States)

    Fischer, Axel W; Alexander, Nathan S; Woetzel, Nils; Karakas, Mert; Weiner, Brian E; Meiler, Jens

    2015-11-01

    For many membrane proteins, the determination of their topology remains a challenge for methods like X-ray crystallography and nuclear magnetic resonance (NMR) spectroscopy. Electron paramagnetic resonance (EPR) spectroscopy has evolved as an alternative technique to study structure and dynamics of membrane proteins. The present study demonstrates the feasibility of membrane protein topology determination using limited EPR distance and accessibility measurements. The BCL::MP-Fold (BioChemical Library membrane protein fold) algorithm assembles secondary structure elements (SSEs) in the membrane using a Monte Carlo Metropolis (MCM) approach. Sampled models are evaluated using knowledge-based potential functions and agreement with the EPR data and a knowledge-based energy function. Twenty-nine membrane proteins of up to 696 residues are used to test the algorithm. The RMSD100 value of the most accurate model is better than 8 Å for 27, better than 6 Å for 22, and better than 4 Å for 15 of the 29 proteins, demonstrating the algorithms' ability to sample the native topology. The average enrichment could be improved from 1.3 to 2.5, showing the improved discrimination power by using EPR data.

  12. Longitudinal analysis on utilization of medical document management system in a hospital with EPR implementation.

    Science.gov (United States)

    Kuwata, Shigeki; Yamada, Hitomi; Park, Keunsik

    2011-01-01

    Document management systems (DMS) have widespread in major hospitals in Japan as a platform to digitize the paper-based records being out of coverage by EPR. This study aimed to examine longitudinal trends of actual use of DMS in a hospital in which EPR had been in operation, which would be conducive to planning the further information management system in the hospital. Degrees of utilization of electronic documents and templates with DMS were analyzed based on data extracted from a university-affiliated hospital with EPR. As a result, it was found that the number of electronic documents as well as scanned documents circulating at the hospital tended to increase. The result indicated that replacement of paper-based documents with electronic documents did not occur. Therefore it was anticipated that the need for DMS would continue to increase in the hospital. The methods used this study to analyze the trend of DMS utilization would be applicable to other hospitals with with a variety of DMS implementation, such as electronic storage by scanning documents or paper preservation that is compatible with EPR.

  13. Interaction of formin FH2 with skeletal muscle actin. EPR and DSC studies.

    Science.gov (United States)

    Kupi, Tünde; Gróf, Pál; Nyitrai, Miklós; Belágyi, József

    2013-10-01

    Formins are highly conserved proteins that are essential in the formation and regulation of the actin cytoskeleton. The formin homology 2 (FH2) domain is responsible for actin binding and acts as an important nucleating factor in eukaryotic cells. In this work EPR and DSC were used to investigate the properties of the mDia1-FH2 formin fragment and its interaction with actin. MDia1-FH2 was labeled with a maleimide spin probe (MSL). EPR results suggested that the MSL was attached to a single SH group in the FH2. In DSC and temperature-dependent EPR experiments we observed that mDia1-FH2 has a flexible structure and observed a major temperature-induced conformational change at 41 °C. The results also confirmed the previous observation obtained by fluorescence methods that formin binding can destabilize the structure of actin filaments. In the EPR experiments the intermolecular connection between the monomers of formin dimers proved to be flexible. Considering the complex molecular mechanisms underlying the cellular roles of formins this internal flexibility of the dimers is probably important for manifestation of their biological functions.

  14. EPR policies for electronics in developing Asia: an adapted phase-in approach.

    Science.gov (United States)

    Akenji, Lewis; Hotta, Yasuhiko; Bengtsson, Magnus; Hayashi, Shiko

    2011-09-01

    The amount of e-waste is growing rapidly in developing countries, and the health and environmental problems resulting from poor management of this waste have become a concern for policy makers. In response to these challenges, a number of Asian developing countries have been inspired by policy developments in OECD countries, and have drafted legislations based on the principle of extended producer responsibility (EPR). However, the experiences from developed countries show that a successful implementation of EPR policies requires adequate institutions and sufficient administrative capacity. Even advanced countries are thus facing difficulties. This paper concludes from existing literature and from the authors' own observations that there seems to be a mismatch between the typical policy responses to e-waste problems in developing Asia and the capacity for successful implementation of such policies. It also notes that the e-waste situation in developing Asian countries is further complicated by a number of additional factors, such as difficulties in identifying producers, import of used electronic products and e-waste (sometimes illegal), and the existence of a strong informal waste sector. Given these challenges, the authors conclude that comprehensive EPR policy schemes of the kind that have been implemented in some advanced countries are not likely to be effective. The paper therefore proposes an alternative phase-in approach whereby developing Asian countries are able to move gradually towards EPR systems. It argues that this approach would be more feasible, and discusses what could be the key building blocks of each implementation stage.

  15. EPR Spectroscopy of Different Sol Concentration Synthesized Nanocrystalline-ZnO Thin Films

    Directory of Open Access Journals (Sweden)

    Manju Arora

    2015-01-01

    Full Text Available Nanocrystalline zinc oxide (nc-ZnO thin films were grown on p-type silicon substrate through spin coating by sol-gel process using different sol concentrations (10 wt.%, 15 wt.%, and 25 wt.%. These films were characterized by high resolution nondestructive X-ray diffraction (XRD, scanning electron microscopy (SEM with energy dispersive X-ray analysis (EDS attachment, and electron paramagnetic resonance (EPR techniques to understand variations in structural, morphological, and oxygen vacancy with respect to sol concentration. The film surface morphology changes from nanowall to nanorods on increasing sol concentration. EPR spectra revealed the systematic variation from ferromagnetic to paramagnetic nature in these nc-ZnO films. The broad EPR resonance signal arising from the strong dipolar-dipolar interactions among impurity defects present in nc-ZnO film deposited from 10 wt.% sol has been observed and a single strong narrow resonance signal pertaining to oxygen vacancies is obtained in 25 wt.% sol derived nc-ZnO film. The concentrations of impurity defects and oxygen vacancies are evaluated from EPR spectra, necessary for efficient optoelectronic devices development.

  16. EPR and UV spectroscopic study of table sugar as a high-dose dosimeter

    Energy Technology Data Exchange (ETDEWEB)

    Yordanov, N.D. E-mail: ndyepr@bas.bg; Gancheva, V.; Georgieva, E

    2002-10-01

    The possibilities for the estimation of the absorbed dose for high-energy radiation with a new self-calibrated dosimeter containing table sugar as a radiation-sensitive material and Mn{sup 2+}/MgO as an internal standard by the method of electron paramagnetic resonance (EPR) is reported. The dose response of this dosimeter is represented as the ratio between the EPR signal intensities of sugar and Mn{sup 2+} versus absorbed dose. Because the EPR spectra of both substances are simultaneously recorded, the influence of some related instrumental setting parameters were investigated. UV spectral studies on water solutions of irradiated solid sugar were also performed. In all solutions of irradiated sugar samples a band at 267 nm was recorded as linearly increasing intensity with the absorbed dose. The minimum detectable dose using the UV spectrum of water solutions of irradiated sugar is 100 Gy. Combination of EPR and UV spectral data is possible to use for independent internal or international calibration and control of dose estimations.

  17. On the Correlation between EPR and Positron Annihilation Measurements on gamma-Irradiated Acetyl Methionine

    DEFF Research Database (Denmark)

    Eldrup, Morten Mostgaard; Lund-Thomsen, E.; Mogensen, O. E.

    1972-01-01

    The dose dependence of the relative EPR signal intensity and positron lifetime spectrum was measured for γ‐irradiated acetyl methionine in the dose range from 0 to 30 Mrad. Angular correlation measurements were performed for the doses 0 and 30 Mrad. The result of the irradiation was the creation...

  18. Correlated four-component EPR g-tensors for doublet molecules

    DEFF Research Database (Denmark)

    Vad, M.S.; Pedersen, M.N.; Nørager, A.

    2013-01-01

    The first correlated ab initio four-component calculations of electron paramagnetic resonance (EPR) g-tensors for doublet radicals are reported. We have implemented a first-order degenerate perturbation theory approach based on the four-component Dirac-Coulomb Hamiltonian and fully relativistic c...

  19. On the use of Locally Dense Basis Sets in the Calculation of EPR Hyperfine Couplings

    DEFF Research Database (Denmark)

    Hedegård, Erik D.; Sauer, Stephan P. A.; Milhøj, Birgitte O.

    2013-01-01

    The usage of locally dense basis sets in the calculation of Electron Paramagnetic Resonance (EPR) hyperne coupling constants is investigated at the level of Density Functional Theory (DFT) for two model systems of biologically important transition metal complexes: One for the active site in the c...

  20. On the use of locally dense basis sets in the calculation of EPR hyperfine couplings

    DEFF Research Database (Denmark)

    Milhøj, Birgitte Olai; Hedegård, Erik D.; Sauer, Stephan P. A.

    2013-01-01

    The usage of locally dense basis sets in the calculation of Electron Paramagnetic Resonance (EPR) hyperne coupling constants is investigated at the level of Density Functional Theory (DFT) for two model systems of biologically important transition metal complexes: One for the active site in the c...

  1. A 5 tesla superconducting magnet and cryostats for an EPR/FMR spectrometer

    NARCIS (Netherlands)

    Reuvekamp, E.M.C.M.; Gerritsma, G.J.; Kate, ten H.H.J.; Klundert, van de L.J.M.

    1988-01-01

    A description is given of the cryogenic part of an electron paramagnetic resonance (EPR)/ferromagnetic resonance (FMR) spectrometer using Ka-band (26.5-40 GHz) and U-band (40-60 GHz) frequencies for resonance measurements on large magnetic thin-films. The unit has two cryostats; the first has a room

  2. EPR of Sm{sup 3+} in BaFCl single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Falin, M [Department of Physical Chemistry, University of Geneva, Geneva (Switzerland); Bill, H [Department of Physical Chemistry, University of Geneva, Geneva (Switzerland); Lovy, D [Department of Physical Chemistry, University of Geneva, Geneva (Switzerland)

    2004-03-03

    BaFCl single crystals doped with Sm{sup 3+} ions were studied by using the EPR method. Several types of paramagnetic Sm{sup 3+} centres were found. The parameters of the corresponding spin Hamiltonians were determined. Structural models and ground states of the observed centres are proposed.

  3. Model compounds of humic acid and oxovanadium cations. Potentiometric titration and EPR spectroscopy studies

    Directory of Open Access Journals (Sweden)

    Mercê Ana Lucia Ramalho

    1999-01-01

    Full Text Available The stability constants and the isotropic EPR parameters Ao (hyperfine splitting constant and g o (g value were obtained by potentiometric titrations and EPR spectroscopy, respectively, of 85%v/v aqueous solutions of model compounds of humic acids - salicylic acid (SALA - and both nitrohumic acids, a laboratory artifact - nitrosalicylic acids, 3-nitrosalicylic acid (3-NSA, 5-nitrosalicylic acid (5-NSA and 3,5-dinitrosalicylic acid (3,5-DNSA and oxovanadium cations. It was possible to record EPR spectra of those model compounds and the ion VO2+ (V(IV, and the stability constants were obtained from a solution of VO3+ (V(V, the values for the logarithms of the stability constants ranging from 12.77 ± 0.04 to 7.06 ± 0.05 for the species ML, and from 9.90 ±0.04 to 4.06 ± 0.05 for the species ML2 according to the decrease in the acidity of the carboxylic and the hydroxyl groups in the aromatic ring of the model compounds studied as the -NO2 substituents were added. Species distribution diagrams were also obtained for the equilibria studied. The EPR parameters showed that as the logarithm of the overall stability constants increase, g o values also increase, while Ao values show a tendency to decrease.

  4. A New Q-Band EPR Probe for Quantitative Studies of Even Electron Metalloproteins

    Science.gov (United States)

    Petasis, D. T.; Hendrich, M. P.

    1999-02-01

    Existing Q-band (35 GHz) EPR spectrometers employ cylindrical cavities for more intense microwave magnetic fields B1, but are so constructed that only one orientation between the external field B and B1is allowed, namely the B ⊥ B1orientation, thus limiting the use of the spectrometer to measurements on Kramers spin systems (odd electron systems). We have designed and built a Q-band microwave probe to detect EPR signals in even electron systems, which operates in the range 2 K ≤ T ≤ 300 K for studies of metalloprotein samples. The cylindrical microwave cavity operates in the TE011mode with cylindrical wall coupling to the waveguide, thus allowing all orientations of the external magnetic field B relative to the microwave field B1. Such orientations allow observation of EPR transitions in non-Kramers ions (even electron) which are either forbidden or significantly weaker for B ⊥ B1. Rotation of the external magnetic field also permits easy differentiation between spin systems from even and odd electron oxidation states. The cavity consists of a metallic helix and thin metallic end walls mounted on epoxy supports, which allows efficient penetration of the modulation field. The first quantitative EPR measurements from a metalloprotein (Hemerythrin) at 35 GHz with B1‖ B are presented.

  5. VO 2+ ions in zinc lead borate glasses studied by EPR and optical absorption techniques

    Science.gov (United States)

    Prakash, P. Giri; Rao, J. Lakshmana

    2005-09-01

    Electron paramagnetic resonance (EPR) and optical absorption spectra of vanadyl ions in zinc lead borate (ZnO-PbO-B 2O 3) glass system have been studied. EPR spectra of all the glass samples exhibit resonance signals characteristic of VO 2+ ions. The values of spin-Hamiltonian parameters indicate that the VO 2+ ions in zinc lead borate glasses were present in octahedral sites with tetragonal compression and belong to C 4V symmetry. The spin-Hamiltonian parameters g and A are found to be independent of V 2O 5 content and temperature but changing with ZnO content. The decrease in Δ g∥/Δ g⊥ value with increase in ZnO content indicates that the symmetry around VO 2+ ions is more octahedral. The decrease in intensity of EPR signal above 10 mol% of V 2O 5 is attributed to a fall in the ratio of the number of V 4+ ions ( N4) to the number of V 5+ ions ( N5). The number of spins ( N) participating in resonance was calculated as a function of temperature for VO 2+ doped zinc lead borate glass sample and the activation energy was calculated. From the EPR data, the paramagnetic susceptibility was calculated at various temperatures and the Curie constant was evaluated from the 1/ χ- T graph. The optical absorption spectra show single absorption band due to VO 2+ ions in tetragonally distorted octahedral sites.

  6. Synthesis, EPR and Fluorescence Properties of Quaternary Lanthanide Complexes with Chloroacetate and Phenanthroline Ligands

    Institute of Scientific and Technical Information of China (English)

    朱龙观; 肖洪平

    2002-01-01

    A series of novel quaternary mixed anion complexes of lanthanide containing 1,10-phenanthroline (phen) and chloroacetate ligands were synthesized from the water/ethanol solution with slightly acidic solution and characterized by elemental analysis, IR, UV and thermal analysis. The EPR and fluorescence properties also were studied.

  7. Security of EPR-based Quantum Key Distribution using three bases

    CERN Document Server

    Inamori, H

    2000-01-01

    Modifications to a previous proof of the security of EPR-based quantum key distribution are proposed. This modified version applies to a protocol using three conjugate measurement bases rather than two. A higher tolerable error rate is obtained for the three-basis protocol.

  8. Characteristic of paramagnetic centres in burnt clay and pottery by the EPR method

    Energy Technology Data Exchange (ETDEWEB)

    Dobosz, B. [Medical Physics Division, Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznan (Poland)]. E-mail: benia@hoth.amu.edu.pl; Krzyminiewski, R. [Medical Physics Division, Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznan (Poland)

    2007-02-15

    The samples of natural clay and pottery have been investigated by using electron paramagnetic resonance (EPR) method. Because of young age (100-5000 years old) of these materials and the presence of iron compounds the big doses (1-200kGy) of irradiation have been used. The authors investigated whole material without quartz extracting from acid washing. In natural clay the EPR lines were observed which disappear after clay burning and they were also not present in EPR spectrum of pottery. After clay burning at temperatures similar to these at which pottery was burnt the spectra of clay became similar to pottery spectra. These EPR spectra have also similar hyperfine structure for which the g factors are equal g{sub 1}=2.0595, g{sub 2}=2.0079, and g{sub 3}=2.0018 for clay and g{sub 1}=2.0602, g{sub 2}=2.0079 and g{sub 3}=2.0019 for pottery. For these lines the [AlO{sub 4}]{sup 0} centre in quartz was ascribed.

  9. Application of EPR retrospective dosimetry for large-scale accidental situation.

    Science.gov (United States)

    Skvortsov, V G; Ivannikov, A I; Stepanenko, V F; Tsyb, A F; Khamidova, L G; Kondrashov, A E; Tikunov, D D

    2000-05-01

    Above 3000 tooth enamel samples, collected at population of radioactive contaminated territories after Chernobyl accident, the Chernobyl liquidators, the retired military of high radiation risk and the population of control radiation free territories were investigated by EPR spectroscopy method in order to obtain accumulated individual exposure doses. Results of EPR spectra measurements are stored in data bank; enamel samples are also stored in order to provide the possibility to repeat the measurements in future. Statistical analysis of results has allowed to detect the contribution into EPR signal in tooth enamel due to the action of the natural background radiation, and the radioactive contamination of territory. In general, the average doses of external exposure of the population obtained with EPR spectroscopy of teeth enamel are consistent with results based on other methods of direct and retrospective dosimetry. Essential exceeding of the individual doses above the average level within the population groups was observed for some persons. That gave the possibility to detect the individuals with overexposure, which were included into groups for medical monitoring.

  10. EPR Methods for Biological Cu(II): L-Band CW and NARS

    Science.gov (United States)

    Bennett, Brian; Kowalski, Jason

    2016-01-01

    Copper has many roles in biology that involve the change of coordination sphere and/or oxidation state of the copper ion. Consequently, the study of copper in heterogeneous environments is an important area in biophysics. EPR is a primary technique for the investigation of paramagnetic copper, which is usually the isolated Cu(II) ion, but sometimes as Cu(II) in different oxidation states of multi-transition ion clusters. The gross geometry of the coordination environment of Cu(II) can often be determined from a simple inspection of the EPR spectrum, recorded in the traditional X-band frequency range (9 – 10 GHz). Identification and quantitation of the coordinating ligand atoms, however, is not so straightforward. In particular, analysis of the superhyperfine structure on the EPR spectrum, to determine the number of coordinated nitrogen atoms, is fraught with difficulty at X-band, despite the observation that the overwhelming number of EPR studies of Cu(II) in the literature have been carried out at X-band. Greater reliability has been demonstrated at S-band (3 – 4 GHz), using the low-field parallel (gz) features. However, analysis relies on clear identification of the outermost superhyperfine line, which has the lowest intensity of all the spectral features. Computer simulations have subsequently indicated that the much more intense perpendicular region of the spectrum can be reliably interpreted at L-band (2 GHz). The present work describes the development of L-band EPR of Cu(II) into a routine method, that is applicable to biological samples. PMID:26478491

  11. Application of EPR spectroscopy to the examination of pro-oxidant activity of coffee.

    Science.gov (United States)

    Krakowian, Daniel; Skiba, Dominik; Kudelski, Adam; Pilawa, Barbara; Ramos, Paweł; Adamczyk, Jakub; Pawłowska-Góral, Katarzyna

    2014-05-15

    Free radicals present in coffee may be responsible for exerting toxic effects on an organism. The objectives of this work were to compare free radicals properties and concentrations in different commercially available coffees, in solid and liquid states, and to determine the effect of roasting on the formation of free radicals in coffee beans of various origins. The free radicals content of 15 commercially available coffees (solid and liquid) was compared and the impact of processing examined using electron paramagnetic resonance (EPR) spectroscopy at X-band (9.3 GHz). First derivative EPR spectra were measured at microwave power in the range of 0.7-70 mW. The following parameters were calculated for EPR spectra: amplitude (A), integral intensity (I), and line-width (ΔBpp); g-Factor was obtained from resonance condition. Our study showed that free radicals exist in green coffee beans (10(16) spin/g), roasted coffee beans (10(18) spin/g), and in commercially available coffee (10(17)-10(18) spin/g). Free radical concentrations were higher in solid ground coffee than in instant or lyophilised coffee. Continuous microwave saturation indicated homogeneous broadening of EPR lines from solid and liquid commercial coffee samples as well as green and roasted coffee beans. Slow spin-lattice relaxation processes were found to be present in all coffee samples tested, solid and liquid commercial coffees as well as green and roasted coffee beans. Higher free radicals concentrations were obtained for both the green and roasted at 240 °C coffee beans from Peru compared with those originating from Ethiopia, Brazil, India, or Colombia. Moreover, more free radicals occurred in Arabica coffee beans roasted at 240 °C than Robusta. EPR spectroscopy is a useful method of examining free radicals in different types of coffee. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Correlation of the EPR properties of perchlorotriphenylmethyl radicals and their efficiency as DNP polarizers.

    Science.gov (United States)

    Banerjee, Debamalya; Paniagua, Juan Carlos; Mugnaini, Veronica; Veciana, Jaume; Feintuch, Akiva; Pons, Miquel; Goldfarb, Daniella

    2011-11-01

    Water soluble perchlorinated trityl (PTM) radicals were found to be effective 95 GHz DNP (dynamic nuclear polarization) polarizers in ex situ (dissolution) (13)C DNP (Gabellieri et al., Angew Chem., Int. Ed. 2010, 49, 3360). The degree of the nuclear polarization obtained was reported to be dependent on the position of the chlorine substituents on the trityl skeleton. In addition, on the basis of the DNP frequency sweeps it was suggested that the (13)C NMR signal enhancement is mediated by the Cl nuclei. To understand the DNP mechanism of the PTM radicals we have explored the 95 GHz EPR characteristics of these radicals that are relevant to their performance as DNP polarizers. The EPR spectra of the radicals revealed axially symmetric g-tensors. A comparison of the spectra with the (13)C DNP frequency sweeps showed that although the solid effect mechanism is operational the DNP frequency sweeps reveal some extra width suggesting that contributions from EPR forbidden transitions involving (35,37)Cl nuclear flips are likely. This was substantiated experimentally by ELDOR (electron-electron double resonance) detected NMR measurements, which map the EPR forbidden transitions, and ELDOR experiments that follow the depolarization of the electron spin upon irradiation of the forbidden EPR transitions. DFT (density functional theory) calculations helped to assign the observed transitions and provided the relevant spin Hamiltonian parameters. These results show that the (35,37)Cl hyperfine and nuclear quadrupolar interactions cause a considerable nuclear state mixing at 95 GHz thus facilitating the polarization of the Cl nuclei upon microwave irradiation. Overlap of Cl nuclear frequencies and the (13)C Larmor frequency further facilitates the polarization of the (13)C nuclei by spin diffusion. Calculation of the (13)C DNP frequency sweep based on the Cl nuclear polarization showed that it does lead to an increase in the width of the spectra, improving the agreement with the

  13. Detection of free radicals formed by in vitro metabolism of fluoride using EPR spectroscopy.

    Science.gov (United States)

    Pawłowska-Góral, Katarzyna; Pilawa, Barbara

    2011-10-01

    In many parts of the globe, where water contains large amount of fluoride, fluorosis is a serious public health problem. It is accompanied by many changes, not only in the bones, but practically in all organs of the body. Since it was discovered that oxidation stress, together with the peroxidation of lipids which accompanies it, results in many diseases, research has been carried out on this aspect of fluorosis. The findings, however, are incomplete and divergent. The aim of our study was to determine the presence of free radicals in hepatocytes exposed to fluoride in concentrations which do not lead to changes in the concentrations of calcium and magnesium ions. Free radical properties of hepatocytes incubated with fluoride were studied by an X-band electron paramagnetic resonance (EPR) spectroscopy. Hepatocytes are paramagnetic and broad unsymmetrical EPR spectra were obtained for them. Oxygen free radicals with g-factor of 2.0032 exist in hepatocytes. The effect of fluoride concentration and the time of incubation on free radicals amount in cells were examined. The amount of free radicals in hepatocytes increases with the increase of fluoride concentration for all the incubation times (10, 30, and 60 min). The amount of free radicals in hepatocytes decreases with the increase of time of incubation for all the used fluoride concentrations (0.002, 0.082, and 0.164 mmol/l). EPR spectra of the studied cells are homogeneously broadened. Continuous microwave saturation of EPR lines indicates that slow spin-lattice relaxation processes exist in the studied cells. Strong dipolar interactions responsible for the broadening (ΔB(pp): 1.45-1.87 mT) of the EPR spectra exist in the hepatocytes.

  14. Pulse saturation recovery, pulse ELDOR, and free induction decay electron paramagnetic resonance detection using time-locked subsampling

    Science.gov (United States)

    Froncisz, W.; Camenisch, Theodore G.; Ratke, Joseph J.; Hyde, James S.

    2001-03-01

    Time locked subsampling (TLSS) in electron paramagnetic resonance (EPR) involves the steps of (i) translation of the signal from a microwave carrier to an intermediate frequency (IF) carrier where the (IF) offset between the signal oscillator and local oscillator frequencies is synthesized, (ii) sampling the IF carrier four times in an odd number of cycles, say 4 in 3, where the analog-to-digital (A/D) converter is driven by a frequency synthesizer that has the same clock input as the IF synthesizer, (iii) signal averaging as required for adequate signal to noise, (iv) separating the even and odd digitized words into two separate signal channels, which correspond to signals in phase and in quadrature with respect to the IF carrier, i.e., I and Q, and (v) detecting the envelope of I and also of Q by changing the signs of alternate words in each of the two channels. TLSS detection has been demonstrated in three forms of pulse EPR spectroscopy at X band: saturation recovery, pulse electron-electron double resonance, and free induction decay. The IF was 187.5 MHz, the A/D converter frequency was 250 MHz, the overall bandwidth was 125 MHz, and the bandwidths for the separate I and Q channels were each 62.5 MHz. Experiments were conducted on nitroxide radical spin labels. The work was directed towards development of methodology to monitor bimolecular collisions of oxygen with spin labels in a context of site-directed spin labeling.

  15. Excimer Laser Pulse Compress With Pulse Feedback

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>To attain a shorter laser pulse, a compressing technique called pulse feedback was developed from the saturation gain switch applied to the amplification in a discharge pumping excimer laser cavity. It can

  16. Pulsed Optics

    Science.gov (United States)

    Hirlimann, C.

    Optics is the field of physics which comprises knowledge on the interaction between light and matter. When the superposition principle can be applied to electromagnetic waves or when the properties of matter do not depend on the intensity of light, one speaks of linear optics. This situation occurs with regular light sources such as light bulbs, low-intensity light-emitting diodes and the sun. With such low-intensity sources the reaction of matter to light can be characterized by a set of parameters such as the index of refraction, the absorption and reflection coefficients and the orientation of the medium with respect to the polarization of the light. These parameters depend only on the nature of the medium. The situation changed dramatically after the development of lasers in the early sixties, which allowed the generation of light intensities larger than a kilowatt per square centimeter. Actual large-scale short-pulse lasers can generate peak powers in the petawatt regime. In that large-intensity regime the optical parameters of a material become functions of the intensity of the impinging light. In 1818 Fresnel wrote a letter to the French Academy of Sciences in which he noted that the proportionality between the vibration of the light and the subsequent vibration of matter was only true because no high intensities were available. The intensity dependence of the material response is what usually defines nonlinear optics.

  17. Metal-nitroxyl interactions. 28. EPR studies of spin-labeled nickel(II) complexes in fluid solution

    Science.gov (United States)

    Hafid, Slimane; Eaton, Gareth R.; Eaton, Sandra S.

    Three spin-labeled four-coordinate nickel(II) complexes were prepared. In these complexes the nickel(II) was diamagnetic and the EPR spectra in fluid solution were typical nitroxyl spectra. Coordination of pyridine or 2,2'-bipyridyl to the spin-labeled nickel(II) complexes produced high-spin nickel(II) and a disappearance of the nitroxyl EPR signal. Similarly when a spin-labeled bidentate ligang coordinated to a nickel xanthate with diamagnetic ligands, no EPR signal was observed for the six-coordinate complex in fluid solution. The nickel-nitroxyl distances in these complexes were 6 to 10 Å.

  18. A combined EPR and MD simulation study of a nitroxyl spin label with restricted internal mobility sensitive to protein dynamics

    Science.gov (United States)

    Oganesyan, Vasily S.; Chami, Fatima; White, Gaye F.; Thomson, Andrew J.

    2017-01-01

    EPR studies combined with fully atomistic Molecular Dynamics (MD) simulations and an MD-EPR simulation method provide evidence for intrinsic low rotameric mobility of a nitroxyl spin label, Rn, compared to the more widely employed label MTSL (R1). Both experimental and modelling results using two structurally different sites of attachment to Myoglobin show that the EPR spectra of Rn are more sensitive to the local protein environment than that of MTSL. This study reveals the potential of using the Rn spin label as a reporter of protein motions.

  19. Alpha Channeling with High-field Launch of Lower Hybrid Waves

    CERN Document Server

    Ochs, Ian E; Fisch, Nathaniel J

    2015-01-01

    Although lower hybrid waves are effective at driving currents in present-day tokamaks, they are expected to interact strongly with high-energy particles in extrapolating to reactors. In the presence of a radial alpha particle birth gradient, this interaction can take the form of wave amplification rather than damping. While it is known that this amplification more easily occurs when launching from the tokamak high-field side, the extent of this amplification has not been made quantitative. Here, by tracing rays launched from the high- field-side of a tokamak, the required radial gradients to achieve amplification are calculated for a temperature and density regime consistent with a hot-ion-mode fusion reactor. These simulations, while valid only in the linear regime of wave amplification, nonetheless illustrate the possibilities for wave amplification using high-field launch of the lower hybrid wave.

  20. Nb3Sn High Field Magnets for the High Luminosity LHC Upgrade Project

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosio, Giorgio

    2015-06-01

    The High Luminosity upgrade of the Large Hadron Collider at CERN requires a new generation of high field superconducting magnets. High field large aperture quadrupoles (MQXF) are needed for the low-beta triplets close to the ATLAS and CMS detectors, and high field two-in-one dipoles (11 T dipoles) are needed to make room for additional collimation. The MQXF quadrupoles, with a field gradient of 140 T/m in 150 mm aperture, have a peak coil field of 12.1 T at nominal current. The 11 T dipoles, with an aperture of 60 mm, have a peak coil field of 11.6 T at nominal current. Both magnets require Nb3Sn conductor and are the first applications of this superconductor to actual accelerator magnets.

  1. Projects of Iberdrola Engineering and Construction on the Flamanville 3 EPR; Proyectos de Iberdrola Ingenieria y construccion en el EPR de Flamanville 3

    Energy Technology Data Exchange (ETDEWEB)

    Zornoza, J.; Dumas, H.; Sesma, J. L.; Cubian, B.; Diaz, J. I.

    2013-06-01

    Iberdrola Engineering and Construction is participating during the last 5 years in 5 projects on the Flamanville 3 EPR, both in the nuclear island and conventional island and the pump house. These projects represent a challenge from the technical point of view due to the high requirements applicable to the project because of the experience feedback of the operator EDF and of compliance with new regulations that have emerged since the completion of the last nuclear power station in France. This paper presents the description of these projects, as well as its current status. (Author)

  2. Areva subcontracts in Japan the noble part of the Finnish EPR; Areva sous-traite au Japon la partie noble de l'EPR finlandais

    Energy Technology Data Exchange (ETDEWEB)

    Jemain, A

    2004-02-01

    Areva, the French energy group, will subcontract the manufacturing of the reactor vessel and cover of the European Pressurized Reactor (EPR) which will be built in Finland. These components will be manufactured in Japan by Mitsubishi and not by Areva's Chalon/Saint-Marcel factory. The reason is the overburden of work and the lack of room and of machining equipment in the French factory. Also, the turbine and alternator are not built by Alstom, but by Siemens (Germany). (J.S.)

  3. Membrane remodeling by amyloidogenic and non-amyloidogenic proteins studied by EPR

    Science.gov (United States)

    Varkey, Jobin; Langen, Ralf

    2017-07-01

    The advancement in site-directed spin labeling of proteins has enabled EPR studies to expand into newer research areas within the umbrella of protein-membrane interactions. Recently, membrane remodeling by amyloidogenic and non-amyloidogenic proteins has gained a substantial interest in relation to driving and controlling vital cellular processes such as endocytosis, exocytosis, shaping of organelles like endoplasmic reticulum, Golgi and mitochondria, intracellular vesicular trafficking, formation of filopedia and multivesicular bodies, mitochondrial fusion and fission, and synaptic vesicle fusion and recycling in neurotransmission. Misregulation in any of these processes due to an aberrant protein (mutation or misfolding) or alteration of lipid metabolism can be detrimental to the cell and cause disease. Dissection of the structural basis of membrane remodeling by proteins is thus quite necessary for an understanding of the underlying mechanisms, but it remains a formidable task due to the difficulties of various common biophysical tools in monitoring the dynamic process of membrane binding and bending by proteins. This is largely since membranes generally complicate protein structure analysis and this problem is amplified for structural analysis in the presence of different types of membrane curvatures. Recent EPR studies on membrane remodeling by proteins show that a significant structural information can be generated to delineate the role of different protein modules, domains and individual amino acids in the generation of membrane curvature. These studies also show how EPR can complement the data obtained by high resolution techniques such as X-ray and NMR. This perspective covers the application of EPR in recent studies for understanding membrane remodeling by amyloidogenic and non-amyloidogenic proteins that is useful for researchers interested in using or complimenting EPR to gain better understanding of membrane remodeling. We also discuss how a single

  4. EPR of ion-implanted, laser-annealed silicon

    Energy Technology Data Exchange (ETDEWEB)

    Brower, K.L.; Peercy, P.S.

    1979-01-01

    Electron paramagnetic resonance and ion backscattering measurements were made on ion-implanted, pulsed laser-annealed silicon. For phosphorus-implanted silicon (3 x 10/sup 13/ 200 keV P/sup +//cm/sup 2/) the electrical activity of the implanted donors is restored after laser annealing with greater than or equal to 1.8 J/cm/sup 2/. Silicon made amorphous with 2 x 10/sup 15/ 200 keV Si/sup +//cm/sup 2/ and implanted with 3 x 10/sup 13/ 200 keV P/sup +//cm/sup 2/ can be restored to crystallinity after laser annealing, but electrical activity of the P was not restored due to residual defects for laser energies less than or equal to 3 J/cm/sup 2/. Electrical activity can be restored, at least in part, for amorphous silicon implanted at lower energies (approx. = 50 keV). We also observed that N/sub 2/ reacts with amorphous silicon surfaces to form silicon-nitride. Under laser annealing the N is redistributed and exists as an N interstitial within the implanted layer.

  5. Electromagnetic and Thermal Aspects of Radiofrequency Field Propagation in Ultra-High Field MRI

    NARCIS (Netherlands)

    van Lier, A.L.H.M.W.

    2012-01-01

    In MRI, a radiofrequency (RF) pulse is used to generate a signal from the spins that are polarized by a strong magnetic field. For higher magnetic field strengths, a higher frequency of the RF pulse is required in order to match the Larmor frequency. A higher frequency, in turn, leads to a shorter w

  6. Proceedings of the sixth Japan--US workshop on high-field superconducting materials and standard procedures for high-field superconducting materials testing

    Energy Technology Data Exchange (ETDEWEB)

    Tachikawa, K. (ed.) (Tokai Univ., Kanagawa (Japan). Faculty of Engineering); Yamafuji, K. (ed.) (Kyushu Univ., Fukuoka (Japan). Dept. of Electronics); Wada, H. (ed.) (National Research Inst. for Metals, Tsukuba, Ibaraki (Japan)); Ekin, J.W. (ed.) (National Inst. of Standards and Technology, Boulder, CO (United States)); Suenaga, M. (ed.) (Brookhaven National Lab., Upton, NY (United States))

    1989-01-01

    High critical current densities and high magnetic fields are needed for most important energy application of both conventional and high-Tc superconductors. This workshop brought together those engaged research on high-field superconductors in Japan and the US to present recent research results on performance of new high-field superconducting materials and to discuss the most promising directions for research, specifically as it relates to the fusion energy needs of both countries. Topics covered included critical currents, irradiation effects, ac losses, magnetization properties, and new fabrication processes for conventional superconductors. An entire session was devoted to presentations on the properties of Nb[sub 3]Al superconductors. Large magnet research programs for energy applications were reviewed, including the tokamak fusion machine at JAERI, the joint US-Japan Nb[sub 3]Sn poloidal-field-coll development program, and the proposed International Thermonuclear Experimental Reactor (ITER) project. Results were also presented on the VAMAS round robin in three areas; J[sub c], stress effects, and ac losses. Finally, some current research results on experimental high-[Tc] superconductors were reviewed, with particular emphasis on new fabrication processes and the factors limiting the critical current in high-current conductors. Separate abstracts have been prepared.

  7. Proceedings of the sixth Japan--US workshop on high-field superconducting materials and standard procedures for high-field superconducting materials testing

    Energy Technology Data Exchange (ETDEWEB)

    Tachikawa, K. [ed.] [Tokai Univ., Kanagawa (Japan). Faculty of Engineering; Yamafuji, K. [ed.] [Kyushu Univ., Fukuoka (Japan). Dept. of Electronics; Wada, H. [ed.] [National Research Inst. for Metals, Tsukuba, Ibaraki (Japan); Ekin, J.W. [ed.] [National Inst. of Standards and Technology, Boulder, CO (United States); Suenaga, M. [ed.] [Brookhaven National Lab., Upton, NY (United States)

    1989-12-31

    High critical current densities and high magnetic fields are needed for most important energy application of both conventional and high-Tc superconductors. This workshop brought together those engaged research on high-field superconductors in Japan and the US to present recent research results on performance of new high-field superconducting materials and to discuss the most promising directions for research, specifically as it relates to the fusion energy needs of both countries. Topics covered included critical currents, irradiation effects, ac losses, magnetization properties, and new fabrication processes for conventional superconductors. An entire session was devoted to presentations on the properties of Nb{sub 3}Al superconductors. Large magnet research programs for energy applications were reviewed, including the tokamak fusion machine at JAERI, the joint US-Japan Nb{sub 3}Sn poloidal-field-coll development program, and the proposed International Thermonuclear Experimental Reactor (ITER) project. Results were also presented on the VAMAS round robin in three areas; J{sub c}, stress effects, and ac losses. Finally, some current research results on experimental high-{Tc} superconductors were reviewed, with particular emphasis on new fabrication processes and the factors limiting the critical current in high-current conductors. Separate abstracts have been prepared.

  8. Decoupling of excitation and receive coils in pulsed magnetic resonance using sinusoidal magnetic field modulation

    Science.gov (United States)

    Tseytlin, Mark; Epel, Boris; Sundramoorthy, Subramanian; Tipikin, Dmitriy; Halpern, Howard J.

    2016-11-01

    In pulsed magnetic resonance, the excitation power is many orders of magnitude larger than that induced by the spin system in the receiving coil or resonator. The receiver must be protected during and immediately after the excitation pulse to allow for the energy stored in the resonator to dissipate to a safe level. The time during which the signal is not detected, the instrumental dead-time, can be shortened by using magnetically decoupled excitation and receive coils. Such coils are oriented, with respect to each other, in a way that minimizes the total magnetic flux produced by one coil in the other. We suggest that magnetically decoupled coils can be isolated to a larger degree by tuning them to separate frequencies. Spins are excited at one frequency, and the echo signal is detected at another. Sinusoidal magnetic field modulation that rapidly changes the Larmor frequency of the spins between the excitation and detection events is used to ensure the resonance conditions for both coils. In this study, the relaxation times of trityl-CD3 were measured in a field-modulated pulsed EPR experiment and compared to results obtained using a standard spin echo method. The excitation and receive coils were tuned to 245 and 256.7 MHz, respectively. Using an available rapid-scan, cross-loop EPR resonator, we demonstrated an isolation improvement of approximately 20-30 dB due to frequency decoupling. Theoretical analysis, numerical simulations, and proof-of-concept experiments demonstrated that substantial excitation-detection decoupling can be achieved. A pulsed L-band system, including a small volume bi-modal resonator equipped with modulation coils, was constructed to demonstrate fivefold dead-time reduction in comparison with the standard EPR experiment. This was achieved by detuning of the excitation and receive coils by 26 MHz and using sinusoidal modulation at 480 kHz.

  9. RosettaTMH: a method for membrane protein structure elucidation combining EPR distance restraints with assembly of transmembrane helices

    Directory of Open Access Journals (Sweden)

    Andrew Leaver-Fay

    2015-12-01

    Full Text Available Membrane proteins make up approximately one third of all proteins, and they play key roles in a plethora of physiological processes. However, membrane proteins make up less than 2% of experimentally determined structures, despite significant advances in structure determination methods, such as X-ray crystallography, nuclear magnetic resonance spectroscopy, and cryo-electron microscopy. One potential alternative means of structure elucidation is to combine computational methods with experimental EPR data. In 2011, Hirst and others introduced RosettaEPR and demonstrated that this approach could be successfully applied to fold soluble proteins. Furthermore, few computational methods for de novo folding of integral membrane proteins have been presented. In this work, we present RosettaTMH, a novel algorithm for structure prediction of helical membrane proteins. A benchmark set of 34 proteins, in which the proteins ranged in size from 91 to 565 residues, was used to compare RosettaTMH to Rosetta’s two existing membrane protein folding protocols: the published RosettaMembrane folding protocol (“MembraneAbinitio” and folding from an extended chain (“ExtendedChain”. When EPR distance restraints are used, RosettaTMH+EPR outperforms ExtendedChain+EPR for 11 proteins, including the largest six proteins tested. RosettaTMH+EPR is capable of achieving native-like folds for 30 of 34 proteins tested, including receptors and transporters. For example, the average RMSD100SSE relative to the crystal structure for rhodopsin was 6.1 ± 0.4 Å and 6.5 ± 0.6 Å for the 449-residue nitric oxide reductase subunit B, where the standard deviation reflects variance in RMSD100SSE values across ten different EPR distance restraint sets. The addition of RosettaTMH and RosettaTMH+EPR to the Rosetta family of de novo folding methods broadens the scope of helical membrane proteins that can be accurately modeled with this software suite.

  10. Programmable pulse generator

    CERN Document Server

    Xue Zhi Hua; Duan Xiao Hui

    2002-01-01

    The author introduces the design of programmable pulse generator that is based on a micro-controller and controlled by RS232 interface of personal computer. The whole system has good stability. The pulse generator can produce TTL pulse and analog pulse. The pulse frequency can be selected by EPLD. The voltage amplitude and pulse width of analog pulse can be adjusted by analog switches and digitally-controlled potentiometers. The software development tools of computer is National Instruments LabView5.1. The front panel of this virtual instrumentation is intuitive and easy-to-use. Parameters can be selected and changed conveniently by knob and slide

  11. EPR study of phenolic radical stabilization by grafting on SiO 2

    Science.gov (United States)

    Panagiota, Stathi; Louloudi, Maria; Deligiannakis, Yiannis

    2009-04-01

    A hybrid [SiO 2-GA] material has been synthesized by grafting Gallic acid (3,4,5-trihydroxybenzoic acid, GA) on SiO 2 via formation of amide bonds between amine groups on aminopropyl-silica and the carboxyl group of GA. The spatial fixation of GA prevents polymerization effects. EPR spectroscopy shows that GA radicals on [SiO 2-GA] show remarkable stability, comparable to that previously observed only for radicals in biological matrices on in soil organic matter. EPR reveals a bundle-like organization of the GA molecules on [SiO 2-GA] material. The relation of these factors to the enhanced radical stability is discussed.

  12. Entanglement Conservation, ER=EPR, and a New Classical Area Theorem for Wormholes

    CERN Document Server

    Remmen, Grant N; Pollack, Jason

    2016-01-01

    We consider the question of entanglement conservation in the context of the ER=EPR correspondence equating quantum entanglement with wormholes. In quantum mechanics, the entanglement between a system and its complement is conserved under unitary operations that act independently on each; ER=EPR suggests that an analogous statement should hold for wormholes. We accordingly prove a new area theorem in general relativity: for a collection of dynamical wormholes and black holes in a spacetime satisfying the null curvature condition, the maximin area for a subset of the horizons (giving the largest area attained by the minimal cross section of the multi-wormhole throat separating the subset from its complement) is invariant under classical time evolution along the outermost apparent horizons. The evolution can be completely general, including horizon mergers and the addition of classical matter satisfying the null energy condition. This theorem is the gravitational dual of entanglement conservation and thus consti...

  13. Investigations in quantum games using EPR-type set-ups

    CERN Document Server

    Iqbal, A

    2006-01-01

    Research in quantum games has flourished during recent years. However, it seems that opinion remains divided about their true quantum character and content. For example, one argument says that quantum games are nothing but 'disguised' classical games and that to quantize a game is equivalent to replacing the original game by a different classical game. The present thesis contributes towards the ongoing debate about quantum nature of quantum games by developing two approaches addressing the related issues. Both approaches take Einstein-Podolsky-Rosen (EPR)-type experiments as the underlying physical set-ups to play two-player quantum games. In the first approach, the players' strategies are unit vectors in their respective planes, with the knowledge of coordinate axes being shared between them. Players perform measurements in an EPR-type setting and their payoffs are defined as functions of the correlations, i.e. without reference to classical or quantum mechanics. Classical bimatrix games are reproduced if th...

  14. EPR-based, quality-related process parameters: a nationwide assessment.

    Science.gov (United States)

    De Clercq, E; Van Casteren, V; Bossuyt, N; Goderis, G; Moreels, S

    2014-01-01

    The aim of the study was to determine whether or not primary care EPR-based data can be used to measure specific process parameters that can then, in turn, be used to assess the quality of care provided to chronic patients. We analysed data from a large research network that collects data from all Belgian GP practices through both manual and automatic extraction procedures. We built a number of quality-related process parameters and observed the concordance of our results with two external databases: a nationwide reimbursement database and a regional EPR-based network. We found that only the automatic data extraction method was suitable for building process parameters. The current research network may lead to an underestimation of the quality of care processes. We suggested ways to improve this network.

  15. Dating sediment deposits on Montalvanian carvings using EPR and TL methods

    Energy Technology Data Exchange (ETDEWEB)

    Sastry, M.D.; Sullasi, Henry S.L. E-mail: hsullasi@dfn.if.usp.br; Camargo, Fabiola; Watanabe, Shigueo; Prous, Andre P.P.; Silva, Martha M.C

    2004-01-01

    About 30 years ago a rock shelter with engravings by early settlers was found at Montalvania, northern end of state of Minas Gerais, Brazil. Lower part of engravings was covered with thin deposit of calcite mixed with quartz grains, due to occasional flood. This mixture of two minerals was dated by thermoluminescence and electron paramagnetic resonance using in both cases, additive method. The accumulated dose D{sub AC}, that is, natural radioactivity and cosmic rays radiation dose that induces TL and EPR signal intensity has been found to be around 50 Gy both by TL and EPR methods. The annual radiation dose rate was estimated to be about 1.027 mGy/a from knowledge of uranium, thorium and potassium content determined by inductively coupled plasma-mass spectrometer system. The age of this calcite plus quartz deposits was estimated to be about 50 ka.

  16. EPR investigation on radiation-induced graft copolymerization of styrene onto polyethylene: Energy transfer effects

    Science.gov (United States)

    Salih, M. A.; Buttafava, A.; Ravasio, U.; Mariani, M.; Faucitano, A.

    2007-08-01

    In this paper, energy transfer phenomena concerning the in-source graft copolymerization of styrene onto LDPE were investigated through the EPR analysis of the radical intermediates. The model solution experiments have shown a substantial deviation of the experimental G (radicals) values with respect to the additivity law, which reflect the negative effect of the styrene monomer concentration on the initiation rate of the graft copolymerization. The EPR measurements performed on polyethylene- co-styrene graft copolymers of various composition following low-temperature vacuum gamma irradiation have confirmed the decrease of the total radical yields with increasing the styrene concentration. The effect was partly attributed to the heterogeneity of the graft copolymer matrix and to the lack of molecular mobility in the solid state at low temperature, which prevents the attainment of the favourable geometrical configurations in intermolecular energy and charge transfer events.

  17. EPR and DNP Properties of Certain Novel Single Electron Contrast Agents Intended for Oximetric Imaging

    DEFF Research Database (Denmark)

    Ardenkjær-Larsen, J. H.; Laursen, I; Leunbach, I.;

    1998-01-01

    Parameters of relevance to oximetry with Overhauser magnetic resonance imaging (OMRI) have been measured for three single electron contrast agents of the triphenylmethyl type. The single electron contrast agents are stable and water soluble. Magnetic resonance properties of the agents have been...... examined with electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), and dynamic nuclear polarization (DNP) at 9.5 mT in water, isotonic saline, plasma, and blood at 23 and 37°C. The relaxivities of the agents are about 0.2–0.4 mM−1s−1and the DNP enhancements extrapolate close...... to the dipolar limit. The agents have a single, narrow EPR line, which is analyzed as a Voigt function. The linewidth is measured as a function of the agent concentration and the oxygen concentration. The concentration broadenings are about 1–3 μT/mM and the Lorentzian linewidths at infinite dilution are less...

  18. Spin Labeling and Characterization of Tau Fibrils Using Electron Paramagnetic Resonance (EPR).

    Science.gov (United States)

    Meyer, Virginia; Margittai, Martin

    2016-01-01

    Template-assisted propagation of Tau fibrils is essential for the spreading of Tau pathology in Alzheimer's disease. In this process, small seeds of fibrils recruit Tau monomers onto their ends. The physical properties of the fibrils play an important role in their propagation. Here, we describe two different electron paramagnetic resonance (EPR) techniques that have provided crucial insights into the structure of Tau fibrils. Both techniques rely on the site-directed introduction of one or two spin labels into the protein monomer. Continuous-wave (CW) EPR provides information on which amino acid residues are contained in the fibril core and how they are stacked along the long fibril axis. Double electron-electron resonance (DEER) determines distances between two spin labels within a single protein and hence provides insights into their spatial arrangement in the fibril cross section. Because of the long distance range accessible to DEER (~2-5 nm) populations of distinct fibril conformers can be differentiated.

  19. The design and integration of retinal CAD-SR to diabetes patient ePR system

    Science.gov (United States)

    Wu, Huiqun; Wei, Yufang; Liu, Brent J.; Shang, Yujuan; Shi, Lili; Jiang, Kui; Dong, Jiancheng

    2017-03-01

    Diabetic retinopathy (DR) is one of the serious complications of diabetes that could lead to blindness. Digital fundus camera is often used to detect retinal changes but the diagnosis relies too much on ophthalmologist's experience. Based on our previously developed algorithms for quantifying retinal vessels and lesions, we developed a computer aided detection-structured report (CAD-SR) template and implemented it into picture archiving and communication system (PACS). Furthermore, we mapped our CAD-SR into HL7 CDA to integrate CAD findings into diabetes patient electronic patient record (ePR) system. Such integration could provide more quantitative features from fundus image into ePR system, which is valuable for further data mining researches.

  20. Retrospective dosimetry with EPR and OSL at McMaster University

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, J.W.; Boreham, D.R.; Rink, W.J.; Mistry, R. [McMaster Univ., Ontario (Canada)

    2010-07-01

    Retrospective dosimetry may be of use following a radiological incident, in order to determine whether individuals may have been exposed. We briefly review the fundamentals of two primary techniques for retrospective biophysical dosimetry: electron paramagnetic resonance (EPR) and optically-stimulated luminescence (OSL). Our facility at McMaster University has the capability to perform both EPR and OSL dosimetry, which provides us with the flexibility to study so-called 'fortuitous' dosimeters with the most appropriate technique. In this paper, we review our research of the past decade, during which we have developed techniques for the measurement of absorbed dose in human, rodent, and canine dental enamel, synthetic quartz oscillators, and gypsum wallboard. (author)

  1. New chemometric approach MCR-ALS to unmix EPR spectroscopic data from complex mixtures

    Science.gov (United States)

    Fadel, Maya Abou; de Juan, Anna; Touati, Nadia; Vezin, Hervé; Duponchel, Ludovic

    2014-11-01

    Electron paramagnetic resonance (EPR) spectra of mixtures are often difficult to interpret due to the superposition of spectral contribution of various species present in the complex materials. It is challenging to accurately identify the number of pure compounds present and to extract their pure spectra. In this study, the powerful chemometric method, multivariate curve resolution-alternating least squares (MCR-ALS), is applied to identify different paramagnetic centers. This method is used to simultaneously extract, with no prior knowledge, the pure spectra and the corresponding concentration profiles of all the compounds in the unknown and unresolved mixtures. The goal of our work is to apply, for the first time, this new chemometrics methodology, MCR-ALS, on EPR spectroscopic data in order to characterize a series of distinct but strongly overlapping spectra of various paramagnetic species.

  2. Structure-activity study of thiazides by magnetic resonance methods (NQR, NMR, EPR) and DFT calculations.

    Science.gov (United States)

    Latosińska, J N

    2005-01-01

    The paper presents a comprehensive analysis of the relationship between the electronic structure of thiazides and their biological activity. The compounds of interest were studied in solid state by the resonance methods nuclear quadrupole resonance (NQR), nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) and quantum chemistry (ab inito and DFT) methods. Detailed parallel analysis of the spectroscopic parameters such as quadrupole coupling constant (QCC) NQR chemical shift (delta), chemical shift anisotropy (CSA), asymmetry parameter (eta), NMR and hyperfine coupling constant (A), EPR was performed and the electronic effects (polarisation and delocalisation) were revealed and compared. Biological activity of thiazides has been found to depend on many factors, but mainly on the physico-chemical properties whose assessment was possible on the basis of electron density determination in the molecules performed by experimental and theoretical methods.

  3. EPR, optical and superposition model study of Mn2+ doped L+ glutamic acid

    Science.gov (United States)

    Kripal, Ram; Singh, Manju

    2015-12-01

    Electron paramagnetic resonance (EPR) study of Mn2+ doped L+ glutamic acid single crystal is done at room temperature. Four interstitial sites are observed and the spin Hamiltonian parameters are calculated with the help of large number of resonant lines for various angular positions of external magnetic field. The optical absorption study is also done at room temperature. The energy values for different orbital levels are calculated, and observed bands are assigned as transitions from 6A1g(s) ground state to various excited states. With the help of these assigned bands, Racah inter-electronic repulsion parameters B = 869 cm-1, C = 2080 cm-1 and cubic crystal field splitting parameter Dq = 730 cm-1 are calculated. Zero field splitting (ZFS) parameters D and E are calculated by the perturbation formulae and crystal field parameters obtained using superposition model. The calculated values of ZFS parameters are in good agreement with the experimental values obtained by EPR.

  4. Crystal Structure and EPR Spectra of cis-Dioxo-molybdenum(Ⅴ) Complex with o-Aminophenol

    Institute of Scientific and Technical Information of China (English)

    LU,Xiao-Ming(鲁晓明); LU,Jing-Fen(卢景芬); MAO,Xi-An(毛希安)

    2002-01-01

    The paramagnetic cis-dioxo-molybdenum(V) complex,[NH2CH2CH2NH3]3[HNC6H4O)2] was obtained by the reaction of tetra-butyl ammonium β-octamolybdate with oaminophenol and ethylenediamine in the mixed solvent of CH3OH and CH3CN, and characterized by IR,NMR,EPR spectroscopy and X-ray diffraction analysis .The determination of single crystal X-ray analysis revealed octahedral coordination withcis-dioxo o-aminophenol.The EPR spectra of both the complex and flavoenzyme show similarly.Thus it suggests that the complex anion[MovO2(HNC6H49)2]3-and flavoenzyme have related structure feature.

  5. EPR and UV-vis studies of biomimetic complexes of molybdoenzyme and tungstoenzyme

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The Mo(Ⅴ) and W(Ⅵ) complexes of (NH3CH2- CH2NH2)3[Mo(Ⅴ)O2(OC6H4O)2] (1), (NH3CH2CH2NH2)2.5 [Mo(Ⅴ) 0.5W(Ⅵ)0.5O2(OC6H4O)2] (2) and (NH3CH2CH2NH2)2- [W(Ⅵ)O2(OC6H4O)2] (3) were synthesized by choosing catechol ligand which shows a good reductive property and taking advantage of EMo > EW. Their EPR and UV-vis spectra were compared with the oxidized UV-vis spectra of xanthine dehydrogenase from chicken liver and xanthine oxidase from milk and the EPR spectrum of flavoenzyme from milk.

  6. Identification and dose assessment of irradiated cardamom and cloves by EPR spectrometry

    Science.gov (United States)

    Beshir, W. B.

    2014-03-01

    The use of electron paramagnetic resonance spectroscopy to accurately distinguish irradiated from unirradiated cardamom and cloves and assesses the absorbed dose to radiation processed cardamom and cloves are examined. The results were successful for identifying both irradiated and unirradiated cardamom and cloves. Additive reirradiation of cardamom and cloves produces reproducible dose-response functions, which can be used to assess the initial dose by back-extrapolation. Third degree polynomial function was used to fit the EPR signal/dose curves. It was found that this 3rd degree polynomial function provides satisfactory results without correction of decay for free radicals. The stability of the radiation induced EPR signal of irradiated cardamom and cloves were studied over a storage period of almost 8 months.

  7. Electron paramagnetic resonance (EPR) investigations of lichens - 1: effects of air pollution

    Science.gov (United States)

    Jezierski, Adam; Bylinska, Ewa; Seaward, Mark R. D.

    Electron paramagnetic resonance (EPR) investigations were carried out on more than 800 samples of lichens from Lower Silesia, southwest Poland. A statistically confirmed correlation between annual average concentration of sulphur dioxide in the atmosphere and concentration of semiquinone radicals in Hypogymnia physodes thalli was found. Similar results were obtained for Umbilicaria species from the Karkonosze Mountains. Distribution of semiquinone radicals in lichen thalli was also investigated. The action of nitrogen dioxide on Umbilicaria species resulted in the synthesis of iminoxy radicals in the thalli. The intensification of the semiquinone free radical production in lichen thalli from atmospherically polluted environments and the degradation of lichen acids to β-diketone compounds would appear to be parallel processes. The properties of the iminoxyls derived from β-diketones in the lichen matrix (anisotropic spectra at room temperature) and in organic solutions after extraction procedure were also examined by EPR.

  8. Analysis of two-player quantum games in an EPR setting using Clifford's geometric algebra.

    Science.gov (United States)

    Chappell, James M; Iqbal, Azhar; Abbott, Derek

    2012-01-01

    The framework for playing quantum games in an Einstein-Podolsky-Rosen (EPR) type setting is investigated using the mathematical formalism of geometric algebra (GA). The main advantage of this framework is that the players' strategy sets remain identical to the ones in the classical mixed-strategy version of the game, and hence the quantum game becomes a proper extension of the classical game, avoiding a criticism of other quantum game frameworks. We produce a general solution for two-player games, and as examples, we analyze the games of Prisoners' Dilemma and Stag Hunt in the EPR setting. The use of GA allows a quantum-mechanical analysis without the use of complex numbers or the Dirac Bra-ket notation, and hence is more accessible to the non-physicist.

  9. Analysis of two-player quantum games in an EPR setting using Clifford's geometric algebra.

    Directory of Open Access Journals (Sweden)

    James M Chappell

    Full Text Available The framework for playing quantum games in an Einstein-Podolsky-Rosen (EPR type setting is investigated using the mathematical formalism of geometric algebra (GA. The main advantage of this framework is that the players' strategy sets remain identical to the ones in the classical mixed-strategy version of the game, and hence the quantum game becomes a proper extension of the classical game, avoiding a criticism of other quantum game frameworks. We produce a general solution for two-player games, and as examples, we analyze the games of Prisoners' Dilemma and Stag Hunt in the EPR setting. The use of GA allows a quantum-mechanical analysis without the use of complex numbers or the Dirac Bra-ket notation, and hence is more accessible to the non-physicist.

  10. High precision EPR dosimetry as a reference tool for validation of other techniques.

    Science.gov (United States)

    Chumak, V V; Sholom, S V; Bakhanova, E V; Pasalskaya, L F; Musijachenko, A V

    2005-02-01

    We present here a particular application area for EPR dosimetry with teeth--use as a source of reference dose values for validation/verification of other retrospective dosimetry techniques and existing dose records. The conditions of application of EPR dosimetry in this role as well as practical design of such studies are shown. Particular attention is given to the requirements to the techniques in terms of precision and throughput, as well as to the issue of availability of samples for analysis and practical solution of this problem. Practical application of this approach is illustrated by several examples of completed validation sub-studies, which were performed in the framework of large-scale post-Chernobyl epidemiological studies.

  11. Isotope separation using high-field asymmetric waveform ion mobility spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Barnett, David A.; Purves, Randy W.; Guevremont, Roger E-mail: roger.guevremont@nrc.ca

    2000-08-01

    A new apparatus for gas-phase separation of stable elemental isotopes at atmospheric pressure is described. A gaseous mixture of chloride isotopes was generated using electrospray ionization and introduced into the analyzer region of a high-field asymmetric waveform ion mobility spectrometer (FAIMS). The ion current exiting the FAIMS was sampled into a quadrupole mass spectrometer for isotope identification.

  12. Powder-in-Tube (PIT) Nb3Sn conductors for high-field magnets

    NARCIS (Netherlands)

    Lindenhovius, J.H.; Hornsveld, E.M.; den Ouden, A.; Wessel, Wilhelm A.J.; ten Kate, Herman H.J.

    2000-01-01

    New Nb3Sn conductors, based on the powder-in-tube (PIT) process, have been developed for application in accelerator magnets and high-field solenoids. For application in accelerator magnets, SMI has developed a binary 504 filament PIT conductor by optimizing the manufacturing process and adjustment o

  13. High-field 3He-F interaction at the surface of fluorocarbon spheres

    DEFF Research Database (Denmark)

    Schuhl, A.; Chapellier, M.; Rasmussen, Finn Berg

    1984-01-01

    High-field experiments on the relaxation betweenF in small Teflon spheres andHe on the surface are reported. WithHe as a monolayer, coupling times are found to be less than 5 sec, in magnetic fields up to 3 T and temperatures down to 50 mK, where electronic centers are completely polarized...

  14. Lumbar Modic Changes - A Comparison Between Findings at Low-and High-field MRI

    DEFF Research Database (Denmark)

    Bendix, Tom; Sorensen, Joan S; Henriksson, Gustaf A C

    2012-01-01

    Study Design. A cross-sectional observational study.Objective. To investigate if there is a difference in findings of lumbar Modic changes in low-field (0.3 Tesla) magnetic resonance imaging (MRI) as compared to high field (1.5 Tesla).Summary of Background Data. It is a challenge to give patients...

  15. A SIMPLE ANALYSIS OF THE PROPAGATING ACOUSTOELECTRIC HIGH-FIELD DOMAIN

    DEFF Research Database (Denmark)

    Mosekilde, Erik

    1968-01-01

    An analytical treatment of the uniformly propagating acoustoelectric high-field domain is presented in the limit of zero diffusion. Expressions for the electron density and the acoustic energy density as functions of the electric field are given. The domain velocity is determined. ©1968 The Ameri...... The American Institute of Physics...

  16. Theoretical Formula and Simulation of Cyclotron Magnet Shimming in High Field Environment

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Dong-sheng; YANG; Jian-jun; LI; Ming

    2015-01-01

    In the computation of cyclotron magnet shimming,trim-rod and magnetic channel,one common process is to calculate the variation of magnet field caused by a small iron piece.Under the circumstance of superconducting cyclotron,high field approximate can be used and we can derive

  17. In-situ high field strength testing using a transportable reverberation chamber

    NARCIS (Netherlands)

    Leferink, Frank Bernardus Johannes

    2008-01-01

    A reverberation chamber can create very high field strength with moderate input power. Existing chambers are making use of a paddle wheel to change the resonant modes in the chamber. In the case of a stepper motor, the field is stable for some time, and this type of reverberation chamber is called

  18. High-field Faraday rotation in II-VI-based semimagnetic semiconductors

    NARCIS (Netherlands)

    Savchuk, AI; Fediv, [No Value; Nikitin, PI; Perrone, A; Tatzenko, OM; Platonov, VV

    1998-01-01

    The effects of d-d exchange interaction have been studied by measuring high-field Faraday rotation in II-VI-based semimagnetic semiconductors. For Cd1-xMnxTe crystals with x = 0.43 and at room temperature a saturation in magnetic field dependence of the Faraday rotation has been observed. In the cas

  19. Powder-in-Tube (PIT) Nb3Sn conductors for high-field magnets

    NARCIS (Netherlands)

    Lindenhovius, J.H.; Hornsveld, E.M.; den Ouden, A.; Wessel, Wilhelm A.J.; ten Kate, Herman H.J.

    2000-01-01

    New Nb3Sn conductors, based on the powder-in-tube (PIT) process, have been developed for application in accelerator magnets and high-field solenoids. For application in accelerator magnets, SMI has developed a binary 504 filament PIT conductor by optimizing the manufacturing process and adjustment

  20. First observation of trapped high-field seeking ultracold neutron spin states

    Energy Technology Data Exchange (ETDEWEB)

    Daum, M., E-mail: manfred.daum@psi.ch [PSI, Paul-Scherrer-Institut, CH-5232 Villigen PSI (Switzerland); TUM, Physik-Department Technische Universitaet Muenchen, Excellence Cluster Universe, Munich (Germany); Department of Physics, University of Virginia, Charlottesville, VA 22904-4714 (United States); Fierlinger, P. [TUM, Physik-Department Technische Universitaet Muenchen, Excellence Cluster Universe, Munich (Germany); Franke, B. [PSI, Paul-Scherrer-Institut, CH-5232 Villigen PSI (Switzerland); TUM, Physik-Department Technische Universitaet Muenchen, Excellence Cluster Universe, Munich (Germany); Geltenbort, P. [ILL, Institut Laue-Langevin, Grenoble (France); Goeltl, L. [PSI, Paul-Scherrer-Institut, CH-5232 Villigen PSI (Switzerland); Gutsmiedl, E. [TUM, Physik-Department Technische Universitaet Muenchen, Excellence Cluster Universe, Munich (Germany); Karch, J. [Institut fuer Physik, Johannes-Gutenberg-Universitaet, Mainz (Germany); Kessler, G. [TUM, Physik-Department Technische Universitaet Muenchen, Excellence Cluster Universe, Munich (Germany); Kirch, K. [PSI, Paul-Scherrer-Institut, CH-5232 Villigen PSI (Switzerland); IPP, Institut f. Teilchenphysik, ETH Zuerich, CH-8093 Zuerich (Switzerland); Koch, H.-C.; Kraft, A.; Lauer, T. [Institut fuer Physik, Johannes-Gutenberg-Universitaet, Mainz (Germany); Lauss, B. [PSI, Paul-Scherrer-Institut, CH-5232 Villigen PSI (Switzerland); Pierre, E. [LPC, Laboratoire de Physique Corpusculaire, ENSICAEN-CNRS/IN2P3, Caen (France); Pignol, G. [LPSC, Laboratoire de Physique Subatomique et de Cosmologie, UJF-CNRS/IN2P3-INPG, Grenoble (France); Reggiani, D.; Schmidt-Wellenburg, P. [PSI, Paul-Scherrer-Institut, CH-5232 Villigen PSI (Switzerland); Sobolev, Yu.; Zechlau, T. [Institut fuer Physik, Johannes-Gutenberg-Universitaet, Mainz (Germany); Zsigmond, G. [PSI, Paul-Scherrer-Institut, CH-5232 Villigen PSI (Switzerland)

    2011-10-25

    Ultracold neutrons were stored in a volume, using a magnetic dipole field shutter. Radial confinement was provided by material walls. Low-field seeking neutrons were axially confined above the magnetic field. High-field seeking neutrons are trapped inside the magnetic field. They can systematically shift the measured neutron lifetime to lower values in experiments with magnetic confinement.

  1. A.S.N. regulation of Flamanville 3 EPR construction; L'inspection du reacteur Flamanville 3 de type EPR

    Energy Technology Data Exchange (ETDEWEB)

    Limousin, S. [Autorite de Surete Nucleaire, 75 - Paris (France)

    2009-02-15

    The EPR authorization decree for Flamanville 3 was issued by the French government (decree no. 2007-534) on the 10 April 2007. The construction activities are going on in the manufacturer workshops and at Flamanville site. The decree published in November 2007, and related to the so called TSN law (the nuclear transparency and safety nuclear law published in 2006), specifies that the commissioning licence (the agreement for first fuel load) has to be granted by an ASN decision on the basis of the assessment of the demonstration of the plant safety. In this aim, one part of ASN's work is to review, with its technical sup-port organisation (IRSN), the reactor construction in order to appreciate the safety level of the construction activities. This paper describes ASN's strategy for the regulation of Flamanville 3 EPR construction activities, endorsed by ASN commission at the end of November 2007, and the main events which have occurred on Flamanville site since the beginning of the construction. The article presents the main ASN conclusions of this regulation at this time. (author)

  2. The value of high-field MRI (3 T) in the assessment of sellar lesions

    Energy Technology Data Exchange (ETDEWEB)

    Pinker, K. [Department of Diagnostic Radiology, Medical University Vienna, Waehringer Guertel 18-20, 1090 Vienna (Austria); Ba-Ssalamah, A. [Department of Diagnostic Radiology, Medical University Vienna, Waehringer Guertel 18-20, 1090 Vienna (Austria); Wolfsberger, S. [Department of Neurosurgery, Medical University Vienna (Austria); Mlynarik, V. [Department of Diagnostic Radiology, Medical University Vienna, Waehringer Guertel 18-20, 1090 Vienna (Austria); Knosp, E. [Department of Neurosurgery, Medical University Vienna (Austria); Trattnig, S. [Department of Diagnostic Radiology, Medical University Vienna, Waehringer Guertel 18-20, 1090 Vienna (Austria)]. E-mail: siegfried.trattnig@univie.ac.at

    2005-06-01

    The aim of this study was the evaluation of the normal sellar anatomy in vitro and in vivo with high-field MRI and its application in the diagnosis of sellar pathologies in comparison to standard MRI. All high-field MR images were obtained using a 3 T Bruker Medspec 30/80 Scanner with a head birdcage transmit/receive coil and an actively shielded gradient system with a maximum gradient strength of 45 mT/m. Firstly an in vitro study of the sella turcica was performed to depict normal pituitary and sellar anatomy at high field. After a pilot-study this sequence-protocol was established: A RARE sequence (TR/TE = 7790/19 ms; matrix size, 512 x 512; RARE factor = 8, FOV, 200 mm) was used for T2-weighted coronal, axial and sagittal images. A 3D gradient echo sequence with magnetization-preparation (MP-RAGE, TR/TE/TI 33.5/7.6/800 ms, matrix size, 512 x 512; FOV, 200 mm, effective slice thickness, 1.88 mm; 3 averages) was used for acquisition of T1-weighted pre- and post-contrast images. Between January 2002 and March 200458 patients were enrolled in this study. Seven patients were examined for suspected microadenoma and in 51 patients 3T MRI was used to obtain additional information about the sellar lesion already known to be present from standard MRI. In 21 cases the accuracy of the imaging findings was assessed afterwards by comparison with intraoperative findings. The infiltration of the medial cavernous sinus wall was suspected on standard MRI on 15 sides (47%), on high-field MRI on 9 sides (28%) and could be verified by intraoperative findings on 6 sides (19%). Accordingly, sensitivity to infiltration was 83% for 3 T and 67% for standard MRI. Specificity was 84% for 3 T and 58% for standard MRI. Moreover, high-field MRI revealed microadenomas in 7 patients with a median diameter of 4 mm (range 2-9 mm). The segments of the cranial nerves were seen as mean 4 hypointense spots (range 2-5 spots) on high-field MRI in contrast to 3 spots (range 0-4 spots) on standard MRI

  3. NMR and EPR Studies of Free-Radical Intermediates from Experiments Mimicking the Winds on Mars

    DEFF Research Database (Denmark)

    Jakobsen, Hans J.; Song, Likai; Gan, Zhehong

    2016-01-01

    A new kind of solid gas chemical reactions has been investigated using solid-state powder H-2, C-13, and Si-29 NMR and EPR spectroscopies. These studies involve reactions between a silicate-created Si free-radical intermediate and a few ordinary gases such as isotopically H-2-, C-13-, and O-17......)-C-13, (encapsulation of the gas) and the indication of a congested methyl group in the product from reaction with methane....

  4. Emergency Preservation and Resuscitation for Cardiac Arrest from Trauma (EPR CAT)

    Science.gov (United States)

    2016-12-01

    Award Number: W81XWH-07-1-0682 TITLE: Emergency Preservation and Resuscitation for Cardiac Arrest from Trauma (EPR-CAT) PRINCIPAL INVESTIGATOR...Arrest 5a. CONTRACT NUMBER From Trauma 5b. GRANT NUMBER W81XWH-07-1-0682 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Patrick...for the trauma surgeons involved in the project has been completed. The Shock Trauma Center of the University of Maryland Medical Center is now open

  5. Multi-Partite EPR Entangled State Representation for Continuous Variables and Its Application in Squeezing Theory

    Institute of Scientific and Technical Information of China (English)

    JIANG Nian-Quan

    2005-01-01

    @@ By extending the Einstein-Podolsky-Rosen (EPR) bipartite entanglement to an n-partite case, we construct the common eigenstate of the n-partite total coordinate and relative momenta for the continuous variables. The entanglement property of the state is shown. The classical dilation transform of variables in such a state induces a new n-mode squeezing operator related to an n-mode bosonic operator realization of SU(1,1) Lie algebra.

  6. Ionizable Nitroxides for Studying Local Electrostatic Properties of Lipid Bilayers and Protein Systems by EPR

    Science.gov (United States)

    Voinov, Maxim A.; Smirnov, Alex I.

    2016-01-01

    Electrostatic interactions are known to play one of the major roles in the myriad of biochemical and biophysical processes. In this Chapter we describe biophysical methods to probe local electrostatic potentials of proteins and lipid bilayer systems that is based on an observation of reversible protonation of nitroxides by EPR. Two types of the electrostatic probes are discussed. The first one includes methanethiosulfonate derivatives of protonatable nitroxides that could be used for highly specific covalent modification of the cysteine’s sulfhydryl groups. Such spin labels are very similar in magnetic parameters and chemical properties to conventional MTSL making them suitable for studying local electrostatic properties of protein-lipid interfaces. The second type of EPR probes is designed as spin-labeled phospholipids having a protonatable nitroxide tethered to the polar head group. The probes of both types report on their ionization state through changes in magnetic parameters and a degree of rotational averaging, thus, allowing one to determine the electrostatic contribution to the interfacial pKa of the nitroxide, and, therefore, determining the local electrostatic potential. Due to their small molecular volume these probes cause a minimal perturbation to the protein or lipid system while covalent attachment secure the position of the reporter nitroxides. Experimental procedures to characterize and calibrate these probes by EPR and also the methods to analyze the EPR spectra by least-squares simulations are also outlined. The ionizable nitroxide labels and the nitroxide-labeled phospholipids described so far cover an exceptionally wide pH range from ca. 2.5 to 7.0 pH units making them suitable to study a broad range of biophysical phenomena especially at the negatively charged lipid bilayer surfaces. The rationale for selecting proper electrostatically neutral interface for calibrating such probes and example of studying surface potential of lipid bilayer is

  7. Large EPR g-shifts for S= {1}/{2} molecules doped into the nickelocene lattice

    Science.gov (United States)

    Hulliger, J.; Baltzer, P.

    1986-10-01

    Large anisotropic g-shifts for bis-(benzene)-vanadium or cyclopentadienyl-cycloheptatrienyl-vanadium (both S= {1}/{2}) doped into nickelocene ( S=1) have been observed by X-band EPR at 3 K. It is shown by a molecular field analysis that nickelocene is a weakly ferromagnetically coupled Van Vleck paramagnet. Estimated ferro- and antiferromagnetic doublet-triplet molecular field sums are of the order of wavenumbers.

  8. [Role of rapid movement of spin labels in interpreting EPR spectra for spin-labelled macromolecules].

    Science.gov (United States)

    Nikol'skiĭ, D O; Timofeev, V P

    2003-01-01

    The method of spin labeling was used to monitor quick movements of side residues in protein monocrystals. The EPR spectra of monocrystals of spin-labeled lysozyme at different orientations of the tetrahonal crystal relative to the direction of the magnetic field were interpreted using the molecular dynamics method. A simple model was proposed, which enables one to calculate the trajectory of movements of the spin label by the molecular dynamic method over a relatively short period of time. The entire "frozen" protein molecule and a "defrozen" spin-labeled amino acid residue were considered in the framework of the model. To calculate the trajectories in vacuum, a model of spin-labeled lysozyme was constructed, and the parameters of force potentials for the atoms of the protein molecule and the spin label were specified. It follows from the calculations that the protein environment sterically hinders the range of eventual angular reorientations of the reporter NO-group of nitroxyl incorporated into the spin label, thereby affecting the shape of the EPR spectrum. However, the scatter in the positions of the reporter group in the angular space turned out to correspond to the Gauss distribution. Using the atomic coordinates of the spin label, obtained in a chosen time interval by the method of molecular dynamics, and taking into account the distribution of the states of the spin label in the ensemble of spin-labeled macromolecules in the crystal, we simulated the EPR spectra of monocrystals of spin-labeled lysozyme. The theoretical EPR spectra coincide well with the experimental.

  9. Spectra processing at tooth enamel dosimetry: Analytical description of EPR spectrum at different microwave power

    Energy Technology Data Exchange (ETDEWEB)

    Tieliewuhan, E. [Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8553 (Japan); Ivannikov, A. [Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8553 (Japan) and Medical Radiological Research Center of RAMS, Korolyov str., 4, Obninsk 249036 (Russian Federation)]. E-mail: ivann@mail.ru; Zhumadilov, K. [Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8553 (Japan); Nalapko, M. [Medical Radiological Research Center of RAMS, Korolyov str., 4, Obninsk 249036 (Russian Federation); Tikunov, D. [Medical Radiological Research Center of RAMS, Korolyov str., 4, Obninsk 249036 (Russian Federation); Skvortsov, V. [Medical Radiological Research Center of RAMS, Korolyov str., 4, Obninsk 249036 (Russian Federation); Stepanenko, V. [Medical Radiological Research Center of RAMS, Korolyov str., 4, Obninsk 249036 (Russian Federation); Toyoda, S. [Department of Applied Physics, Okayama University of Science, 1-1 Ridai, Okayama 700-0005 (Japan); Tanaka, K. [Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8553 (Japan); Endo, S. [Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8553 (Japan); Hoshi, M. [Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8553 (Japan)

    2006-04-15

    Variation of the electron paramagnetic resonance (EPR) spectrum of the human tooth enamel recorded at different microwave power is investigated. The analytical models describing the native and the radiation-induced signals in the enamel are proposed, which fit the experimental spectra in wide range of microwave power. These models are designed to use for processing the spectra of irradiated enamel at determination of the absorbed dose from the intensity of the radiation-induced signal.

  10. Free Radical Scavenging Activity of Drops and Spray Containing Propolis—An EPR Examination

    OpenAIRE

    Pawel Olczyk; Katarzyna Komosinska-Vassev; Pawel Ramos; Lukasz Mencner; Krystyna Olczyk; Barbara Pilawa

    2017-01-01

    The influence of heating at a temperature of 50 °C and UV-irradiation of propolis drops and spray on their free radical scavenging activity was determined. The kinetics of interactions of the propolis samples with DPPH free radicals was analyzed. Interactions of propolis drops and propolis spray with free radicals were examined by electron paramagnetic resonance spectroscopy. A spectrometer generating microwaves of 9.3 GHz frequency was used. The EPR spectra of the model DPPH free radicals we...

  11. UV/Vis, MCD and EPR Spectra of Mononuclear Manganese and Molybdenum Complexes

    OpenAIRE

    Westphal, Anne

    2012-01-01

    This PhD thesis deals with the spectroscopic characterization of the electronic structures of mononuclear manganese and molybdenum complexes. At this, in addition to UV/Vis absorption spectroscopy, electron paramagnetic resonance (EPR) and magnetic circular dichroism (MCD) spectroscopy were applied in this work. Additionally, new procedures for the general analysis of MCD C-term intensities were developed within the scope of this thesis. It is divided into four parts. Following a general p...

  12. Effect of absorbed dose and storage length on electron paramagnetic resonance (EPR) signal strength in irradiated alfalfa seeds

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A kind of alfalfa seeds was irradiated by 1, 2, 3, 4 and 5 kGy at a dose rate of 6.288 kGy. h-1 in a self-shielded irradiator of 137Cs gamma rays. The EPR spectra, which were measured subsequently between 0.3401and 0.3501 T, showed that there was a direct proportional relationship between the EPR signal strength of free radicals produced by gamma irradiation in the alfalfa seeds and absorbed dose. The first derivative EPR spectra of the alfalfa seeds were very clear and easy to identify. However, the EPR signal strength of the peak-to-peak amplitude decreased rapidly and most of them decayed beyond 50% within 3 days after the seeds were irradiated. It tended to stabilize after half a month since the seeds were irradiated. The differences of the EPR signal strength between the irradiated and unirradiated alfalfa seeds still remained. All seeds were stored at ambient temperature for more than 3months. Therefore, using EPR spectrometry technique to measure free radicals in alfalfa seeds as a means to determine whether the seeds have been irradiated or not is feasible, relatively fast and simple.

  13. Shock waves associated with electric pulses affect cell electro-permeabilization.

    Science.gov (United States)

    Wasungu, Luc; Pillet, Flavien; Bellard, Elizabeth; Rols, Marie-Pierre; Teissié, Justin

    2014-12-01

    New features of cell electro-permeabilization are obtained by using high field (several tens of kV/cm) with short (sub-microsecond, nanosecond) pulse duration. Arcing appears as a main safety problem when air gaps are present between electrodes. A new applicator design was chosen to obtain a closed chamber where high field pulses could be delivered in a safe way with very short pulse duration. The safety issue of the system was validated under millisecond, microsecond and nanosecond pulses. The closed chamber applicator was then checked for its use under classical electro-mediated permeabilization and electro-gene transfer (EGT). A 20 times decrease in gene expression was observed compared with classical open chambers. It was experimentally observed that shock waves were present under the closed chamber configuration of the applicator. This was not the case with an open chamber design. Electropulsation chamber design plays a role on pulsing conditions and in the efficiency of gene electro transfer.

  14. EPR study of the formation of radicals in PP with antioxidants irradiated with gamma rays

    Energy Technology Data Exchange (ETDEWEB)

    Silva, P. [Instituto Venezolano de Investigaciones Cientificas, Centro de Fisica, Carretera Panamericana Km. 11, Caracas 1020-A (Venezuela)], E-mail: silva@ivic.ve; Albano, C. [Instituto Venezolano de Investigaciones Cientificas, Centro de Quimica, Universidad Central de Venezuela, Facultad de Ingenieria (Venezuela); Perera, R. [Departamento de Mecanica, Universidad Simon Bolivar (Venezuela)

    2007-12-15

    The behavior of different compounds of polypropylene (PP) with stabilizers such as buthyl-hydroxy-toluene (BHT), Chimassorb 944 (Hals) (CHIM), and a copolymer of styrene-butadiene-styrene (SBS) was studied using electron paramagnetic resonance (EPR). A characteristic spectra for pure PP irradiated in air was obtained for all the samples just after being irradiated [M. Dole, The Radiation Chemistry of Macromolecules, Vol. 2, Academic Press, 1973]. A change in the lineshape of the spectra from a pure PP's EPR signal to that of nitroxyl radical as a function of time was observed. The total free radical concentration (TFRC) decayed until approximately 800 h in the PP-HALS and until around 2000 h in all other cases, when the TFRC began to increase in all the cases, except in that of PP-BHT. In this last case, the EPR signal was not detectable after 4000 h. The BHT and the SBS diluted the free radical concentrations, being them smaller when they are present. The behavior observed in all the samples is consistent with the formation of nitroxyl radicals by gamma rays.

  15. Extruded dielectric sample tubes of complex cross section for EPR signal enhancement of aqueous samples

    Science.gov (United States)

    Sidabras, Jason W.; Mett, Richard R.; Hyde, James S.

    2017-04-01

    This paper builds on the work of Mett and Hyde (2003) and Sidabras et al. (2005) where multiple flat aqueous sample cells placed perpendicular to electric fields in microwave cavities were used to reduce the RF losses and increase the EPR signal. In this work, we present three novel sample holders for loop-gap resonators (LGRs) and cylindrical cavity geometries. Two sample holders have been commissioned and built by polytetrafluoroethylene (PTFE) extrusion techniques: a 1 mm O.D. capillary with a septum down the middle, named DoubleDee, and a 3.5 mm O.D. star shaped sample holder, named AquaStar. Simulations and experimental results at X-band show that the EPR signal intensity increases by factors of 1.43 and 3.87 in the DoubleDee and AquaStar respectively, over the current TPX 0.9 mm O.D. sample tube in a two-loop-one-gap LGR. Finally, combining the insight gained from the constructed sample holders and finite-element solutions, a third multi-lumen sample holder for a cylindrical TE011 cavity is optimized, named AquaSun, where simulations show an EPR signal intensity increase by a factor of 8.2 over a standard 1 mm capillary.

  16. EPR and optical absorption studies of vanadyl ions in potassium oxalate monohydrate

    Energy Technology Data Exchange (ETDEWEB)

    Kripal, Ram [Department of Physics, University of Allahabad, Allahabad 211002 (India)]. E-mail: ram_kripal2001@rediffmail.com; Maurya, Manju [Department of Physics, University of Allahabad, Allahabad 211002 (India)]. E-mail: mmanju8@yahoo.co.in; Govind, Har [Department of Electronics, Ewing Christian College, Allahabad 211003 (India)

    2007-04-15

    Electron paramagnetic resonance (EPR) studies are reported on vanadyl (VO{sup 2+}) ions in potassium oxalate monohydrate (POM) single crystals at room temperature. The results indicate that the paramagnetic impurity takes up an interstitial site in the lattice. The angular variation of EPR spectra in three mutually perpendicular planes are used to determine the spin Hamiltonian parameters and the values obtained are: g{sub x} =2.0153{+-}0.0002, g{sub y} =1.9489{+-}0.0002, g{sub z} =1.9155{+-}0.0002 and A{sub x} =(63{+-}2)x10{sup -4} cm{sup -1}, A{sub y} =(92{+-}2)x10{sup -4} cm{sup -1}, A{sub z} =(193{+-}2)x10{sup -4} cm{sup -1}. The optical absorption spectrum of VO{sup 2+} ions in the crystal lattice is also studied at room temperature. The characteristic spectrum of the VO{sup 2+} ions has four absorption bands. The band positions are calculated using the energy expressions and compared with the observed values to confirm the transitions. The analysis of the spectrum indicates that the first three bands correspond to d-d transitions and the last band is probably charge transfer band. Crystal field parameter (Dq) and tetragonal parameters (Ds and Dt) are also evaluated. From optical and EPR data various bonding parameters are obtained and nature of bonding in the crystal is discussed.

  17. In situ EPR and UV-vis spectroelectrochemistry of hole-transporting organic substrates

    Science.gov (United States)

    Rapta, Peter; Fáber, René; Dunsch, Lothar; Neudeck, Andreas; Nuyken, Oskar

    2000-02-01

    A newly developed in situ electron paramagnetic resonance (EPR)/ultraviolet-visible (UV-vis) spectroelectrochemical cell equipped with a laminated indium-tin oxide (ITO) working electrode was used in the investigation of various organic substrates which are potential hole-transporting materials. The experiment demonstrated the possibility of using such a technique for examining redox behavior of conducting polymers (polypyrrole, PPy), oligomers (thiophene dimmer and quarterthiophene) and bis-anilines (N,N,N',N'-tetraphenylbenzidine, TPB). All investigated structures formed stable paramagnetic intermediates in the first oxidation step characterised with UV-vis spectra in the region 400-600 nm. In the second oxidation step EPR-silent di-cationic structures are formed with broad vis bands in the region 600-1000 nm. The measurement of the reference UV-vis spectra direct in the EPR cavity was possible using a specially-constructed non-contacted ITO plate in the spectroelectrochemical cell in the case of polypyrrole.

  18. Entanglement conservation, ER=EPR, and a new classical area theorem for wormholes

    Science.gov (United States)

    Remmen, Grant N.; Bao, Ning; Pollack, Jason

    2016-07-01

    We consider the question of entanglement conservation in the context of the ER=EPR correspondence equating quantum entanglement with wormholes. In quantum mechanics, the entanglement between a system and its complement is conserved under unitary operations that act independently on each; ER=EPR suggests that an analogous statement should hold for wormholes. We accordingly prove a new area theorem in general relativity: for a collection of dynamical wormholes and black holes in a spacetime satisfying the null curvature condition, the maximin area for a subset of the horizons (giving the largest area attained by the minimal cross section of the multi-wormhole throat separating the subset from its complement) is invariant under classical time evolution along the outermost apparent horizons. The evolution can be completely general, including horizon mergers and the addition of classical matter satisfying the null energy condition. This theorem is the gravitational dual of entanglement conservation and thus constitutes an explicit characterization of the ER=EPR duality in the classical limit.

  19. EPR Distance Measurements in Native Proteins with Genetically Encoded Spin Labels.

    Science.gov (United States)

    Schmidt, Moritz J; Fedoseev, Artem; Bücker, Dennis; Borbas, Julia; Peter, Christine; Drescher, Malte; Summerer, Daniel

    2015-12-18

    The genetic encoding of nitroxide amino acids in combination with electron paramagnetic resonance (EPR) distance measurements enables precise structural studies of native proteins, i.e. without the need for mutations to create unique reactive sites for chemical labeling and thus with minimal structural perturbation. We here report on in vitro DEER measurements in native E. coli thioredoxin (TRX) that establish the nitroxide amino acid SLK-1 as a spectroscopic probe that reports distances and conformational flexibilities in the enzyme with nonmutated catalytic centers that are not accessible by the use of the traditional methanethiosulfonate spin label (MTSSL). We generated a rotamer library for SLK-1 that in combination with molecular dynamics (MD) simulation enables predictions of distance distributions between two SLK-1 labels incorporated into a target protein. Toward a routine use of SLK-1 for EPR distance measurements in proteins and the advancement of the approach to intracellular environments, we study the stability of SLK-1 in E. coli cultures and lysates and establish guidelines for protein expression and purification that offer maximal nitroxide stability. These advancements and insights provide new perspectives for facile structural studies of native, endogenous proteins by EPR distance measurements.

  20. Structural Characterization of Polymer-Clay Nanocomposites Prepared by Co-Precipitation Using EPR Techniques

    Directory of Open Access Journals (Sweden)

    Udo Kielmann

    2014-02-01

    Full Text Available Polymer-clay nanocomposites (PCNCs containing either a rubber or an acrylate polymer were prepared by drying or co-precipitating polymer latex and nanolayered clay (synthetic and natural suspensions. The interface between the polymer and the clay nanoparticles was studied by electron paramagnetic resonance (EPR techniques by selectively addressing spin probes either to the surfactant layer (labeled stearic acid or the clay surface (labeled catamine. Continuous-wave (CW EPR studies of the surfactant dynamics allow to define a transition temperature T* which was tentatively assigned to the order-disorder transition of the surfactant layer. CW EPR studies of PCNC showed that completely exfoliated nanoparticles coexist with agglomerates. HYSCORE spectroscopy in PCNCs showed couplings within the probe −assigned with DFT computations− and couplings with nuclei of the environment, 1H and 23Na for the surfactant layer probe, and 29Si, 7Li, 19F and 23Na for the clay surface probe. Analysis of these couplings indicates that the integrity of the surfactant layer is conserved and that there are sizeable ionic regions containing sodium ions directly beyond the surfactant layer. Simulations of the very weak couplings demonstrated that the HYSCORE spectra are sensitive to the composition of the clay and whether or not clay platelets stack.

  1. EPR investigation of gamma irradiated single crystal guaifenesin: A combined experimental and computational study

    Science.gov (United States)

    Tasdemir, Halil Ugur; Sayin, Ulku; Türkkan, Ercan; Ozmen, Ayhan

    2016-04-01

    Gamma irradiated single crystal of Guaifenesin (Glyceryl Guaiacolate), an important expectorant drug, were investigated with Electron Paramagnetic Resonance (EPR) spectroscopy between 123 and 333 K temperature at different orientations in the magnetic field. Considering the chemical structure and the experimental spectra of the gamma irradiated single crystal of guaifenesin sample, we assumed that alkoxy or alkyl-type paramagnetic species may be produced by irradiation. Depending on this assumption, eight possible alkoxy and alkyl-type radicals were modeled and EPR parameters of these modeled radicals were calculated using the B3LYP/6-311++G(d,p)-level of density functional theory (DFT). Theoretically calculated values of alkyl-type modeled radical(R3) are in good agreement with experimentally determined EPR parameters of single crystal. Furthermore, simulation spectra which are obtained by using the theoretical initial values are well matched with the experimental spectra. It was determined that a stable Cα •H2αCβHβCγH2γ (R3) alkyl radical was produced in the host crystal as a result of gamma irradiation.

  2. An EPR spin probe study of liposomes from sunflower and soybean phospholipids.

    Science.gov (United States)

    Melnyk, Andrii K; Sukhoveev, Olexandr V; Kononets, Lyudmyla A; Khilchevsky, Olexandr M; Shulga, Serhiy M; Kukhar, Valery P; Vovk, Andriy I

    2016-01-01

    Comparative properties of lecithin-based liposomes prepared from the mixed phospholipids of sunflower seeds, soybean and egg yolk were investigated by electron paramagnetic resonance (EPR) spectroscopy. For these investigations, stable nitroxide radicals, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 5,7-dimethyladamantane-1-carboxylate (DMAC-TEMPO), 5-doxylstearic acid (5-DSA) and 16-doxylstearic acid (16-DSA) were used as spin probes. Binding of the spin probes to the liposome membranes resulted in a substantial increase of the apparent rotational diffusion correlation times. The EPR spectra of the incorporated nitroxides underwent temperature-dependent changes. For every spin probe, values of apparent enthalpy and entropy of activation were calculated from the temperature dependence of rotational diffusion correlation times via Arrhenius equation. In case of DMAC-TEMPO, the data point to differences between the phospholipid bilayer of liposomes derived from sunflower and soy lecithin, and some similarity between the sunflower and egg yolk liposomes. Anisotropic hyperfine interaction constants of DMAC-TEMPO and 16-DSA included in the liposomes have been analyzed and attributed to different micropolarity of the surroundings of the spin probes. The kinetics of EPR signal decay of DMAC-TEMPO in the presence of 2,2'-azobis(2-amidinopropane) suggest the better stability of the sunflower liposomes to lipid peroxidation as compared to the liposomes prepared from soy lecithin.

  3. X-ray absorption spectroscopy and EPR studies of oriented spinach thylakoid preparations

    Energy Technology Data Exchange (ETDEWEB)

    Andrews, J.C. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley Lab., CA (United States). Structural Biology Div.

    1995-08-01

    In this study, oriented Photosystem II (PS II) particles from spinach chloroplasts are studied with electron paramagnetic resonance (EPR) and x-ray absorption spectroscopy (XAS) to determine more details of the structure of the oxygen evolving complex (OEC). The nature of halide binding to Mn is also studied with Cl K-edge and Mn EXAFS (extended x-ray absorption fine structure) of Mn-Cl model compounds, and with Mn EXAFS of oriented PS II in which Br has replaced Cl. Attention is focused on the following: photosynthesis and the oxygen evolving complex; determination of mosaic spread in oriented photosystem II particles from signal II EPR measurement; oriented EXAFS--studies of PS II in the S{sub 2} state; structural changes in PS II as a result of treatment with ammonia: EPR and XAS studies; studies of halide binding to Mn: Cl K-edge and Mn EXAFS of Mn-Cl model compounds and Mn EXAFS of oriented Br-treated photosystem II.

  4. Radiation-induced defects in strontium carbonate rod for EPR dosimetry applications

    Science.gov (United States)

    Rushdi, M. A. H.; Abdel-Fattah, A. A.; Soliman, Y. S.

    2017-02-01

    The radiation-induced defects in strontium carbonate (SrCO3) rod dosimeter in the dose range of 2.5 Gy-25 kGy was investigated using electron paramagnetic resonance (EPR) technique. The EPR spectra of γ-irradiated strontium carbonate (SC) rods exhibit a strong EPR signal with the spectroscopic splitting g-factor 2.008 and a weak signal at g-factor 2.003. This signal increases with increasing irradiation dose. The dose-response function has a good linearity in the low dose range of 2.5-500 Gy and slight sub-linearity in the high dose range of 0.5-25 kGy. The dosimeter is nearly humidity independent in the level of 33-77% relative humidity during irradiation. The temperature coefficient of the dose-response function is 0.22% per °C in the temperature range of 20-40 °C. The rod dosimeter exhibits a maximum deviation from water equivalency by 7% in the energy range of 0.3-5 MeV. The overall uncertainty of dose determination using SC dosimeter is 5.2% and 4.54% (2σ) for low and high dose range, respectively.

  5. An EPR Study on VO2+ and Mn2+ Ions in Some Zeolites

    Science.gov (United States)

    Ucun, F.; Köksal, F.

    1996-02-01

    The electron paramagnetic resonance (EPR) of hydrated VOSO4 ·3H2O and MnCl2 · 2H2O, adsorbed on the synthetic zeolites 3A, 4A, 5A and 13X of pore diameters 0.3, 0.4, 0.5, and 1.0 nm, respectively, and the natural zeolites heulandite and clinoptilolite was investigated. The spectra indicated that the coordination structures are VO(H2O)52+ and Mn(H2O)62+ , and that their EPR line widths vary with the pore diameters and the surface areas of the zeolites. The spectra of VO(H2O)52+ in natural zeolites at room temperature display an isotropic behavior and therefore indicate that the water ligands are mobile. The EPR spin Hamiltonian parameters, the molecule orbital constant ß2*2 , and the Fermi contact term Keff were determined and are discussed. The spectra of Mn(H2O)62+ for narrow-pore zeolites indicate the existence of mobile and immobile water, whereas for wide-pore and natural zeolites they indicated the existence of only mobile water. The obtained Mn(H2O)62+ spectra are discussed.

  6. On the zigzagging causility model of EPR correlations and on the interpretation of quantum mechanics

    Science.gov (United States)

    de Beauregard, O. Costa

    1988-09-01

    Being formalized inside the S-matrix scheme, the zigzagging causility model of EPR correlations has full Lorentz and CPT invariance. EPR correlations, proper or reversed, and Wheeler's smoky dragon metaphor are respectively pictured in spacetime or in the momentum-energy space, as V-shaped, A-shaped, or C-shaped ABC zigzags, with a summation at B over virtual states |B> = *. The formal parrallelism breaks down at the level of interpretation because (A|C) = ||2. CPT invariance implies the Fock and Watanabe principle that, in quantum mechanics, retarded (advanced) waves are used for prediction (retrodiction), an expression of which is = = , with |Φ> denoting a preparation, |Ψ> a measurement, and U the evolution operator. The transformation |Ψ> = |UΦ> or |Φ> = |U-1Ψ> exchanges the “preparation representation” and the “measurement representation” of a system and is ancillary in the formalization of the quantum chance game by the “wavelike algebra” of conditional amplitude. In 1935 EPR overlooked that a conditional amplitude = Σ between the two distant measurements is at stake, and that only measurements actually performed do make sense. The reversibility = * implies that causality is CPT-invariant, or arrowless, at the microlevel. Arrowed causality is a macroscopic emergence, corollary to wave retardation and probability increase. Factlike irreversibility states repression, not suppression, of “blind statistical retrodiction”—that is, of “final cause.”

  7. Entanglement conservation, ER=EPR, and a new classical area theorem for wormholes

    Energy Technology Data Exchange (ETDEWEB)

    Remmen, Grant N. [Walter Burke Institute for Theoretical PhysicsCalifornia Institute of Technology, Pasadena, CA 91125 (United States); Bao, Ning [Walter Burke Institute for Theoretical PhysicsCalifornia Institute of Technology, Pasadena, CA 91125 (United States); Institute for Quantum Information and Matter,California Institute of Technology, Pasadena, CA 91125 (United States); Pollack, Jason [Walter Burke Institute for Theoretical PhysicsCalifornia Institute of Technology, Pasadena, CA 91125 (United States)

    2016-07-11

    We consider the question of entanglement conservation in the context of the ER=EPR correspondence equating quantum entanglement with wormholes. In quantum mechanics, the entanglement between a system and its complement is conserved under unitary operations that act independently on each; ER=EPR suggests that an analogous statement should hold for wormholes. We accordingly prove a new area theorem in general relativity: for a collection of dynamical wormholes and black holes in a spacetime satisfying the null curvature condition, the maximin area for a subset of the horizons (giving the largest area attained by the minimal cross section of the multi-wormhole throat separating the subset from its complement) is invariant under classical time evolution along the outermost apparent horizons. The evolution can be completely general, including horizon mergers and the addition of classical matter satisfying the null energy condition. This theorem is the gravitational dual of entanglement conservation and thus constitutes an explicit characterization of the ER=EPR duality in the classical limit.

  8. Pd+ ions in NaCl single crystal: EPR and optical studies

    Science.gov (United States)

    Badalyan, A. G.; Polak, K.; Rosa, J.

    2003-01-01

    EPR and optical absorption of Pd centres in as grown NaCl single crystal are reported. The EPR spectra show that palladium forms the Pd+ centre with d(x2-y2) wave function in the ground state. This centre formation and the accompanying distortion give rise to a superhyperfine interaction of the Pd+ ion with the nuclei of the four Cl- ligands in the plane perpendicular to the C-4 Symmetry axis. The results of the fitting of axial spin Hamiltonian parameters to the experimentally observed spectra give the following values at 12 K: g(parallel to) =2.85, g(perpendicular to) congruent to 2.15, A(parallel to) 29.8 x 10(-4)cm(-1), A(perpendicular to) = 5.9 x 10(-4)cm(-1). When the temperature increases, lines are getting broader, their amplitude decreases and a single line with g-value of g = 2.38 at g = 1/3(g(parallel to)+ 2g(perpendicular to)) appears, which demonstrates the known Jahn-Teller behaviour of d(9) ions EPR spectra.

  9. Irradiated bivalve mollusks: Use of EPR spectroscopy for identification and dosimetry

    Science.gov (United States)

    Alberti, Angelo; Chiaravalle, Eugenio; Fuochi, Piergiorgio; Macciantelli, Dante; Mangiacotti, Michele; Marchesani, Giuliana; Plescia, Elena

    2011-12-01

    High energy radiation treatment of foodstuff for microbial control and shelf-life extension is being used in many countries. However, for consumer protection and information, the European Union has adopted the Directives 1999/2/EC and 1999/3/EC to harmonize the rules concerning the treatment and trade of irradiated foods in EU countries. Among the validated methods to detect irradiated foods the EU directives also include Electron Paramagnetic Resonance (EPR/ESR) spectroscopy.We describe herein the use of EPR for identification of four species of bivalve mollusks, i.e. brown Venus shells (Callista chione), clams (Tapes semidecussatus), mussels (Mytilus galloprovincialis) and oysters (Ostrea edulis) irradiated with 60Co γ-rays. EPR could definitely identify irradiated seashells due to the presence of long-lived free radicals, primarily CO2-, CO33-, SO2- and SO3- radical anions. The presence of other organic free radicals, believed to originate from conchiolin, a scleroprotein present in the shells, was also ascertained. The use of one of these radicals as a marker for irradiation of brown Venus shells and clams can be envisaged. We also propose a dosimetric protocol for the reconstruction of the administered dose in irradiated oysters.

  10. An EPR investigation of SiO{sub x} films with columnar structure

    Energy Technology Data Exchange (ETDEWEB)

    Bratus' , V., E-mail: v_bratus@isp.kiev.ua [V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, Kyiv 03680 (Ukraine); Indutnyi, I.; Shepeliavyi, P. [V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, Kyiv 03680 (Ukraine); Torchynska, T. [ESFM-Instituto Politécnico Nacional, México D.F. 07738 (Mexico)

    2014-11-15

    The results of electron paramagnetic resonance (EPR) study of obliquely deposited porous SiO{sub x} films before and after thermal annealing in vacuum at 950 °C are presented. The low intensity slightly asymmetrical and featureless EPR line with a g-value of 2.0044 and a linewidth of 0.77 mT has been detected in as-sputtered films and attributed to dangling bonds of silicon atoms in amorphous SiO{sub x} domains with x=0.8. Successive annealing results in decreasing this line and the appearance of an intense EPR line with g=2.0025, linewidth of 0.11 mT and a hyperfine doublet with 1.6 mT splitting. According to the parameters this spectrum has been attributed to the EX center, a hole delocalized over four non-bridging oxygen atoms grouped around a Si vacancy in SiO{sub 2}. The impact of chemical treatment before annealing and duration of anneals on the defect system is discussed.

  11. Free Radical Scavenging Activity of Drops and Spray Containing Propolis-An EPR Examination.

    Science.gov (United States)

    Olczyk, Pawel; Komosinska-Vassev, Katarzyna; Ramos, Pawel; Mencner, Lukasz; Olczyk, Krystyna; Pilawa, Barbara

    2017-01-13

    The influence of heating at a temperature of 50 °C and UV-irradiation of propolis drops and spray on their free radical scavenging activity was determined. The kinetics of interactions of the propolis samples with DPPH free radicals was analyzed. Interactions of propolis drops and propolis spray with free radicals were examined by electron paramagnetic resonance spectroscopy. A spectrometer generating microwaves of 9.3 GHz frequency was used. The EPR spectra of the model DPPH free radicals were compared with the EPR spectra of DPPH in contact with the tested propolis samples. The antioxidative activity of propolis drops and propolis spray decreased after heating at the temperature of 50 °C. A UV-irradiated sample of propolis drops more weakly scavenged free radicals than an untreated sample. The antioxidative activity of propolis spray increased after UV-irradiation. The sample of propolis drops heated at the temperature of 50 °C quenched free radicals faster than the unheated sample. UV-irradiation weakly changed the kinetics of propolis drops or spray interactions with free radicals. EPR analysis indicated that propolis drops and spray should not be stored at a temperature of 50 °C. Propolis drops should not be exposed to UV-irradiation.

  12. Temperature dependent electron paramagnetic resonance (EPR) of SrZrO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Santosh K., E-mail: santufrnd@gmail.com [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai (India); Pathak, Nimai [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai (India); Ghosh, P.S. [Materials Science Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Rajeshwari, B. [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai (India); Materials Science Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Natarajan, V. [Materials Science Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Kadam, R.M. [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai (India)

    2015-10-01

    SrZrO{sub 3} (SZO), a distorted perovskite was synthesized using gel-combustion route employing citric acid as a fuel and ammonium nitrate as oxidizer followed by characterization using X-ray diffraction (XRD) and electron paramagnetic resonance (EPR). Purity of the sample is confirmed by inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis. Broadening and shift of the resonance field position in EPR spectrum to the lower field was observed as the temperature is lowered; which is the characteristic of ferromagnetic resonance spectra. The value of Curie–Weiss temperature obtained for SZO particles is 8.7 K. The positive sign of the Curie–Weiss temperature indicates that some of the spins are ferromagnetically coupled in this sample. Theoretical investigation using density functional theory (DFT) calculation revealed that Vacancy at zirconium site contribute maximum to the magnetic moment. - Highlights: • Gel-combustion synthesis of SrZrO{sub 3} perovskite at relatively low temperature. • EPR evidence for ferromagnetic resonance. • Positive sign of the Curie–Weiss temperature ~8.7 K. • Defect induced magnetism- Zirconium vacancy induces maximum magnetic moment.

  13. A high-field magnetic resonance imaging spectrometer using an oven-controlled crystal oscillator as the local oscillator of its radio frequency transceiver.

    Science.gov (United States)

    Liang, Xiao; Tang, Xin; Tang, Weinan; Gao, Jia-Hong

    2014-09-01

    A home-made high-field magnetic resonance imaging (MRI) spectrometer with multiple receiving channels is described. The radio frequency (RF) transceiver of the spectrometer consists of digital intermediate frequency (IF) circuits and corresponding mixing circuits. A direct digital synthesis device is employed to generate the IF pulse; the IF signal from a down-conversion circuit is sampled and followed by digital quadrature detection. Both the IF generation and the IF sampling use a 50 MHz clock. An oven-controlled crystal oscillator, which has outstanding spectral purity and a compact circuit, is used as the local oscillator of the RF transceiver. A digital signal processor works as the pulse programmer of the spectrometer, as a result, 32 control lines can be generated simultaneously while an event is triggered. Field programmable gate array devices are utilized as the auxiliary controllers of the IF generation, IF receiving, and gradient control. High performance, including 1 μs time resolution of the soft pulse, 1 MHz receiving bandwidth, and 1 μs time resolution of the gradient waveform, is achieved. High-quality images on a 1.5 T MRI system using the spectrometer are obtained.

  14. Widespread inflammation in CLIPPERS syndrome indicated by autopsy and ultra-high-field 7T MRI

    DEFF Research Database (Denmark)

    Blaabjerg, Morten; Ruprecht, Klemens; Sinnecker, Tim

    2016-01-01

    OBJECTIVE: To examine if there is widespread inflammation in the brain of patients with chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS) syndrome by using histology and ultra-high-field MRI at 7.0T. METHODS: We performed a detailed neuropath......OBJECTIVE: To examine if there is widespread inflammation in the brain of patients with chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS) syndrome by using histology and ultra-high-field MRI at 7.0T. METHODS: We performed a detailed...... in the brainstem, which were not seen on 3.0T MRI. This corresponded to neuropathologic detection of axonal injury in the autopsy case. CONCLUSION: Our findings suggest more widespread perivascular inflammation and postinflammatory axonal injury in patients with CLIPPERS....

  15. Zero-field nuclear magnetic resonance in high field by modulated rf sequences.

    Science.gov (United States)

    Nishiyama, Yusuke; Yamazaki, Toshio

    2007-04-07

    The authors propose a novel approach to design and evaluate sequences for zero-field NMR spectra in high field (ZFHF) by using amplitude and phase modulated rf sequences. ZFHF provide sharp peaks for the dipolar interaction between two nuclear spins even if the orientation of the molecules is distributed. The internuclear distance r can be directly obtained from the peak position which is proportional to r-3. Numerous ZFHF sequences are obtained. A sequence is selected from them by the systematic evaluation of the sequences. The new ZFHF sequence is less affected by chemical shift anisotropy (CSA) than the previous sequences; the sequence can be used for systems with large CSA such as a dipolar coupled 13C-pair system under realistically high field. 13C ZFHF spectra of 13C2 diammonium succinate and 13C2 diammonium oxalate were observed under the 9.4 T field.

  16. Direct imaging of rf waveguide modes via ultra-high field NMR

    CERN Document Server

    Tonyushkin, A; Van de Moortele, P -F; Adriany, G; Kiruluta, A

    2016-01-01

    We demonstrate an experimental method for direct 2D and 3D imaging of magnetic rf field distribution in metal waveguides based on traveling wave (TW) nuclear-magnetic resonance (NMR) imaging at ultra-high field (>7T). The typical apparatus would include an ultra-high field whole body or small bore NMR scanner, waveguide elements filled with NMR active dielectrics with predefined electric and magnetic properties, and TW rf transmit-receive probes. We validated the technique by obtaining TW magnetic-resonance (MR) images of the magnetic field distribution of the rf modes of circular waveguide filled with deionized water in a 16.4 T small-bore NMR scanner and compared the MR images with numerical simulations. Our NMR technique opens up a practical way of imaging of previously inaccessible rf field distribution of modes inside of various shapes metal waveguides with inserted dielectric objects, including waveguide mode converters and transformers.

  17. Open Science CBS Neuroimaging Repository: Sharing ultra-high-field MR images of the brain.

    Science.gov (United States)

    Tardif, Christine Lucas; Schäfer, Andreas; Trampel, Robert; Villringer, Arno; Turner, Robert; Bazin, Pierre-Louis

    2016-01-01

    Magnetic resonance imaging at ultra high field opens the door to quantitative brain imaging at sub-millimeter isotropic resolutions. However, novel image processing tools to analyze these new rich datasets are lacking. In this article, we introduce the Open Science CBS Neuroimaging Repository: a unique repository of high-resolution and quantitative images acquired at 7 T. The motivation for this project is to increase interest for high-resolution and quantitative imaging and stimulate the development of image processing tools developed specifically for high-field data. Our growing repository currently includes datasets from MP2RAGE and multi-echo FLASH sequences from 28 and 20 healthy subjects respectively. These datasets represent the current state-of-the-art in in-vivo relaxometry at 7 T, and are now fully available to the entire neuroimaging community. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Double degenerate mergers as progenitors of high-field magnetic white dwarfs

    CERN Document Server

    García--Berro, E; Aznar--Siguán, G; Torres, S; Camacho, J; Althaus, L G; Córsico, A H; Külebi, B; Isern, J

    2012-01-01

    High-field magnetic white dwarfs have been long suspected to be the result of stellar mergers. However, the nature of the coalescing stars and the precise mechanism that produces the magnetic field are still unknown. Here we show that the hot, convective, differentially rotating corona present in the outer layers of the remnant of the merger of two degenerate cores is able to produce magnetic fields of the required strength that do not decay for long timescales. We also show, using an state-of-the-art Monte Carlo simulator, that the expected number of high-field magnetic white dwarfs produced in this way is consistent with that found in the Solar neighborhood.

  19. High-field magnetization process of granular Co-Cu alloys prepared by melt spinning

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    High solid-solubility Co15Cu35 alloys have been prepared by melt spinning and submitted to isothermal and anisothermal annealing to obtain granular alloys.The X-ray diffraction(XRD) patterns were measured to invesugate the decomposition of supersaturated solid solution induced by annealing.The atomic diffusion and structural evolution during the heat treatment were investigated.In view of the problems limiting their appllcation.the high-field magneazation curves were measured.By a fit to the high-field magnetization curves,the granuiar alloys are found hard to be magnetically saturated at the early stage of nucleation and growth.The magnetization behavior was correlaced to the annealed-induced structureal evolution and also to the magnetoresistance effect.

  20. Nonlinear Optimization of CLIC DRS New Design with Variable Bends and High Field Wigglers

    CERN Document Server

    Ghasem, H.; Alabau-Gonzalvo, J.; Papadopoulou, S.; Papaphilippou, Y.

    2016-01-01

    The new design of CLIC damping rings is based on longitudinal variable bends and high field superconducting wiggler magnets. It provides an ultra-low horizontal normalised emittance of 412 nm-rad at 2.86 GeV. In this paper, nonlinear beam dynamics of the new design of the damping ring (DR) with trapezium field profile bending magnets have been investigated in detail. Effects of the misalignment errors have been studied in the closed orbit and dynamic aperture.

  1. High-field magnetization of NpRhGa{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Sugiyama, K. [Graduate School of Sciences, Osaka University, Toyonaka, Osaka 560-0043 (Japan)]. E-mail: sugiyama@phys.sci.osaka-u.ac.jp; Honda, D. [Graduate School of Sciences, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Nakashima, H. [Graduate School of Sciences, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Aoki, D. [IMR, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Yamamoto, E. [Advanced Science Research Center, JAERI, Tokai, Ibaraki 319-1195 (Japan); Nakamura, A. [Advanced Science Research Center, JAERI, Tokai, Ibaraki 319-1195 (Japan); Honma, K. [IMR, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Shiokawa, Y. [IMR, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Kindo, K. [ISSP, The University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba 277-8581 (Japan); Hagiwara, M. [KYOKUGEN, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Onuki, Y. [Graduate School of Sciences, Osaka University, Toyonaka, Osaka 560-0043 (Japan)

    2006-05-01

    We have measured the high-field magnetization of NpRhGa{sub 5} with the tetragonal structure and found the sharp metamagnetic transition with a sharp step at 26T in the field along the [100] direction at 4.2K. The magnetization saturates above 38T, with 0.43{mu}{sub B}/Np. The H-T phase diagram was determined by the magnetization curves at various temperatures.

  2. High field transport properties of MBE processed Fe-based superconducting thin films

    Energy Technology Data Exchange (ETDEWEB)

    Iida, Kazumasa [Nagoya University (Japan); IFW Dresden (Germany)

    2015-07-01

    It has been reported that Fe-based superconductors show high upper critical fields with low anisotropies at low temperatures. Hence these materials may offer a unique possibility for high field magnet applications. However, only a few reports on high-field transport properties of Co-doped Ba-122 and Fe(Se,Te) have been published and the only one for SmFeAs(O,F) thin films to date. In order to use this material class for applications, the knowledge of in-field and its orientation dependence of transport properties in a wide range of external fields need to be clarified. In this talk, I will report on high-field (up to dc 45 T) transport properties of P-doped Ba-122, SmFeAs(O,F) and NdFeAs(O,F) thin films prepared by MBE. Although P-doped Ba-122 has the lowest T{sub c}, self-field J{sub c} of over 6 MA/cm{sup 2} at 4.2 K is recorded, which is the highest value ever reported in Fe-based superconductors. Additionally, in-field performance of P-doped Ba-122 shows comparable to those of NdFeAs(O,F) and SmFeAs(O,F) for Hc. On the other hand, both NdFeAs(O,F) and SmFeAs(O,F) exhibited higher J{sub c} for H parallel ab due to the intrinsic pinning. These results indicate that P-doped Ba-122 is the most promising candidates for high-field magnet applications.

  3. Large field-of-view transmission line resonator for high field MRI

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Johannesson, Kristjan Sundgaard; Boer, Vincent

    2016-01-01

    Transmission line resonators is often a preferable choice for coils in high field magnetic resonance imaging (MRI), because they provide a number of advantages over traditional loop coils. The size of such resonators, however, is limited to shorter than half a wavelength due to high standing wave....... Achieved magnetic field distribution is compared to the conventional transmission line resonator. Imaging experiments are performed using 7 Tesla MRI system. The developed resonator is useful for building coils with large field-of-view....

  4. Large field-of-view transmission line resonator for high field MRI

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Johannesson, Kristjan Sundgaard; Boer, Vincent;

    2016-01-01

    Transmission line resonators is often a preferable choice for coils in high field magnetic resonance imaging (MRI), because they provide a number of advantages over traditional loop coils. The size of such resonators, however, is limited to shorter than half a wavelength due to high standing wave....... Achieved magnetic field distribution is compared to the conventional transmission line resonator. Imaging experiments are performed using 7 Tesla MRI system. The developed resonator is useful for building coils with large field-of-view....

  5. Utilization of a Buffered Dielectric to Achieve High Field-Effect Carrier Mobility in Graphene Transistors

    OpenAIRE

    Farmer, Damon B.; Chiu, Hsin-Ying; Lin, Yu-Ming; Jenkins, Keith A.; Xia, Fengnian; Avouris, Phaedon

    2009-01-01

    We utilize an organic polymer buffer layer between graphene and conventional gate dielectrics in top-gated graphene transistors. Unlike other insulators, this dielectric stack does not significantly degrade carrier mobility, allowing for high field-effect mobilities to be retained in top-gate operation. This is demonstrated in both two-point and four-point analysis, and in the high-frequency operation of a graphene transistor. Temperature dependence of the carrier mobility suggests that phono...

  6. Examination by EPR spectroscopy of free radicals in melanins isolated from A-375 cells exposed on valproic acid and cisplatin.

    Science.gov (United States)

    Chodurek, Ewa; Zdybel, Magdalena; Pilawa, Barbara; Dzierzewicz, Zofia

    2012-01-01

    Drug binding by melanin biopolymers influence the effectiveness of the chemotherapy, radiotherapy and photodynamic therapy. Free radicals of melanins take part in formation of their complex with drugs. The aim of this work was to determine the effect of the two compounds: valproic acid (VPA) and cisplatin (CPT) on free radicals properties of melanin isolated from A-375 melanoma cells. Free radicals were examined by an X-band (9.3 GHz) electron paramagnetic resonance (EPR) spectroscopy. EPR spectra were measured for the model synthetic eumelanin - DOPA-melanin, the melanin isolated from the control A-375 cells and these cells treated by VPA, CPT and both VPA and CPT. For all the examined samples broad EPR lines (deltaBpp: 0.48-0.68 mT) with g-factors of 2.0045-2.0060 characteristic for o-semiquinone free radicals were observed. Free radicals concentrations (N) in the tested samples, g-factors, amplitudes (A), integral intensities (I) and linewidths (deltaBpp) of the EPR spectra, were analyzed. The EPR lines were homogeneously broadened. Continuous microwave saturation of the EPR spectra indicated that slow spin-lattice relaxation processes existed in all the tested melanin samples. The relatively slowest spin-lattice relaxation processes characterized melanin isolated from A-375 cells treated with both VPA and CPT. The changes of the EPR spectra with increasing microwave power in the range of 2.2-70 mW were evaluated. Free radicals concentrations in the melanin from A-375 cells were higher than in the synthetic DOPA-melanin. The strong increase of free radicals concentration in the melanin from A-375 cells was observed after their treating by VPA. CPT also caused the increase of free radicals concentrations in the examined natural melanin. The free radicals concentration in melanin isolated from A-375 cells treated with both VPA and CPT was slightly higher than those in melanin from the control cells.

  7. Quantification of local geometric distortion in structural magnetic resonance images: Application to ultra-high fields.

    Science.gov (United States)

    Lau, Jonathan C; Khan, Ali R; Zeng, Tony Y; MacDougall, Keith W; Parrent, Andrew G; Peters, Terry M

    2017-01-06

    Ultra-high field magnetic resonance imaging (MRI) provides superior visualization of brain structures compared to lower fields, but images may be prone to severe geometric inhomogeneity. We propose to quantify local geometric distortion at ultra-high fields in in vivo datasets of human subjects scanned at both ultra-high field and lower fields. By using the displacement field derived from nonlinear image registration between images of the same subject, focal areas of spatial uncertainty are quantified. Through group and subject-specific analysis, we were able to identify regions systematically affected by geometric distortion at air-tissue interfaces prone to magnetic susceptibility, where the gradient coil non-linearity occurs in the occipital and suboccipital regions, as well as with distance from image isocenter. The derived displacement maps, quantified in millimeters, can be used to prospectively evaluate subject-specific local spatial uncertainty that should be taken into account in neuroimaging studies, and also for clinical applications like stereotactic neurosurgery where accuracy is critical. Validation with manual fiducial displacement demonstrated excellent correlation and agreement. Our results point to the need for site-specific calibration of geometric inhomogeneity. Our methodology provides a framework to permit prospective evaluation of the effect of MRI sequences, distortion correction techniques, and scanner hardware/software upgrades on geometric distortion. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Nb$_3$Sn High Field Magnets for the High Luminosity LHC Upgrade Project

    CERN Document Server

    AUTHOR|(CDS)2075881

    2015-01-01

    The high luminosity upgrade of the Large Hadron Collider at CERN requires a new generation of high field superconducting magnets. High field large aperture quadrupoles (MQXF) are needed for the low-beta triplets close to the ATLAS and CMS detectors, and high field two-in-one dipoles (11-T dipoles) are needed to make room for additional collimation. The MQXF quadrupoles, with a field gradient of 140 T/m in 150 mm aperture, have a peak coil field of 12.1 T at nominal current. The 11-T dipoles, with an aperture of 60 mm, have a peak coil field of 11.6 T at nominal current. Both magnets require Nb3Sn conductor and are the first applications of this superconductor to actual accelerator magnets. Collaboration between the US LARP (LHC Accelerator Research Program) and CERN is developing the MQXF magnets, whereas the 11-T dipole magnets are being developed by CERN and Fermilab. This paper reviews the status of Nb3Sn technology for accelerator magnets, discusses its main challenges, and discusses how the MQXF and 11-T...

  9. EPR Studies of DOPA–Melanin Complexes with Netilmicin and Cu(II) at Temperatures in the Range of 105–300 K

    OpenAIRE

    Zdybel, Magdalena; Pilawa, Barbara; Buszman, Ewa; Wrześniok, Dorota; Krzyminiewski, Ryszard; Kruczyński, Zdzisław

    2012-01-01

    The application of electron paramagnetic resonance (EPR) spectroscopy in pharmacy of melanin complexes with netilmicin and Cu(II) was presented. The continuous microwave saturation of EPR spectra of DOPA–melanin and the complexes was performed. EPR spectra were measured on an X-band (9.3 GHz) spectrometer at temperatures in the range of 105–300 K. Paramagnetic copper ions decrease the intensity of the EPR lines of melanin’s free radicals. It was found that fast spin–lattice relaxation charact...

  10. Radial pulse (image)

    Science.gov (United States)

    ... heart. The arteries are the vessels with the "pulse", a rhythmic pushing of the blood in the ... a refilling of the heart chamber. To determine heart rate, one feels the beats at a pulse point ...

  11. Wrist pulse (image)

    Science.gov (United States)

    To measure the pulse at the wrist, place the index and middle finger over the underside of the opposite wrist, below the base ... firmly with flat fingers until you feel the pulse in the radial artery.

  12. Determination of the intersublattice exchange interactions in GdCo12-xFexB6 (x = 0-3) intermetallic compounds by high field magnetization measurements

    Science.gov (United States)

    Diop, L. V. B.; Isnard, O.; Skourski, Y.; Ballon, G.

    2013-05-01

    High field magnetization measurements up to 60 T on free powder samples from GdCo12-xFexB6 (x = 0-3) compounds are reported. The data were used to evaluate the microscopic exchange interaction integral, JGd-3d, between Gd and 3d (Co,Fe) spins. The systems are ferrimagnets; they order magnetically between TC = 95 K for x = 3 and TC = 165 K for x = 0. The low temperature magnetization curves as well as the temperature dependence of intrinsic magnetic parameters are determined by magnetic measurements in pulsed magnetic field. The average magnetic moment ⟨μCo+Fe⟩ per mean transition metal atom (Co + Fe) is small and increases with increasing Fe concentration from 0.44 μΒ for x = 0 to 0.51 μΒ for x = 3 at T = 4 K. From high field magnetization curves, a value of JGd-3d/kB = -4.65 K is derived for x = 0, whereas mean field approximation yields a much larger 3d-3d exchange integral of JCo-Co/kB = 105 K. The obtained results reveal an increase of -JGd-3d/kB with Fe concentration. For x = 0.5, the intersublattice coefficient nGd-3d is found to keep an almost constant value of 5.87 ± 0.13 T*f.u.*μB-1 whatever the temperature in the 2 to 60 K range.

  13. Stress management as an enabling technology for high-field superconducting dipole magnets

    Science.gov (United States)

    Holik, Eddie Frank, III

    This dissertation examines stress management and other construction techniques as means to meet future accelerator requirement demands by planning, fabricating, and analyzing a high-field, Nb3Sn dipole. In order to enable future fundamental research and discovery in high energy accelerator physics, bending magnets must access the highest fields possible. Stress management is a novel, propitious path to attain higher fields and preserve the maximum current capacity of advanced superconductors by managing the Lorentz stress so that strain induced current degradation is mitigated. Stress management is accomplished through several innovative design features. A block-coil geometry enables an Inconel pier and beam matrix to be incorporated in the windings for Lorentz Stress support and reduced AC loss. A laminar spring between windings and mica paper surrounding each winding inhibit any stress transferral through the support structure and has been simulated with ALGORRTM. Wood's metal filled, stainless steel bladders apply isostatic, surface-conforming preload to the pier and beam support structure. Sufficient preload along with mica paper sheer release reduces magnet training by inhibiting stick-slip motion. The effectiveness of stress management is tested with high-precision capacitive stress transducers and strain gauges. In addition to stress management, there are several technologies developed to assist in the successful construction of a high-field dipole. Quench protection has been designed and simulated along with full 3D magnetic simulation with OPERARTM. Rutherford cable was constructed, and cable thermal expansion data was analysed after heat treatment. Pre-impregnation analysis techniques were developed due to elemental tin leakage in varying quantities during heat treatment from each coil. Robust splicing techniques were developed with measured resistivites consistent with nO joints. Stress management has not been incorporated by any other high field dipole

  14. Pulse-Width Jitter Measurement for Laser Diode Pulses

    Institute of Scientific and Technical Information of China (English)

    TANG Jun-Hua; WANG Yun-Cai

    2006-01-01

    @@ Theoretical analysis and experimental measurement of pulse-width jitter of diode laser pulses are presented. The expression of pulse power spectra with all amplitude jitter, timing jitter and pulse-width jitter is deduced.

  15. SU-C-BRD-05: Non-Invasive in Vivo Biodosimetry in Radiotherapy Patients Using Electron Paramagnetic Resonance (EPR) Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bahar, N; Roberts, K; Stabile, F; Mongillo, N; Decker, RD; Wilson, LD; Husain, Z; Contessa, J; Carlson, DJ [Yale University School of Medicine, New Haven, Connecticut (United States); Williams, BB; Flood, AB; Swartz, HM [Geisel Medical School at Dartmouth University, Hanover, New Hampshire (United States)

    2015-06-15

    Purpose: Medical intervention following a major, unplanned radiation event can elevate the human whole body exposure LD50 from 3 to 7 Gy. On a large scale, intervention cannot be achieved effectively without accurate and efficient triage. Current methods of retrospective biodosimetry are restricted in capability and applicability; published human data is limited. We aim to further develop, validate, and optimize an automated field-deployable in vivo electron paramagnetic resonance (EPR) instrument that can fill this need. Methods: Ionizing radiation creates highly-stable, carbonate-based free radicals within tooth enamel. Using a process similar to nuclear magnetic resonance, EPR directly measures the presence of radiation-induced free radicals. We performed baseline EPR measurements on one of the upper central incisors of total body irradiation (TBI) and head and neck (H&N) radiotherapy patients before their first treatment. Additional measurements were performed between subsequent fractions to examine the EPR response with increasing radiation dose. Independent dosimetry measurements were performed with optically-stimulated luminescent dosimeters (OSLDs) and diodes to more accurately establish the relationship between EPR signal and delivered radiation dose. Results: 36 EPR measurements were performed over the course of four months on two TBI and four H & N radiotherapy patients. We observe a linear increase in EPR signal with increasing dose across the entirety of the tested range. A linear least squares-weighted fit of delivered dose versus measured signal amplitude yields an adjusted R-square of 0.966. The standard error of inverse prediction (SEIP) is 1.77 Gy. For doses up to 7 Gy, the range most relevant to triage, we calculate an SEIP of 1.29 Gy. Conclusion: EPR spectroscopy provides a promising method of retrospective, non-invasive, in vivo biodosimetry. Our preliminary data show an excellent correlation between predicted signal amplitude and delivered

  16. Development of a new dosimeter of EPR based on lactose; Desarrollo de un nuevo dosimetro de RPE basado en lactosa

    Energy Technology Data Exchange (ETDEWEB)

    Cruz C, L.; Torijano C, E.; Azorin N, J.; Aguirre G, F. [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 Mexico D. F. (Mexico); Cruz Z, E., E-mail: eftc@xanum.uam.mx [UNAM, Instituto de Ciencias Nucleares, Circuito Exterior, Ciudad Universitaria, 04510 Mexico D. F. (Mexico)

    2014-08-15

    50 years have passed since was proposed using the amino acid alanine as dosimeter advantage the phenomenon of electron paramagnetic resonance (EPR); this dosimetric method has reached a highly competitive level regarding others dosimetry classic methods, for example the thermoluminescence or the use of Fricke dosimeters, to measure high dose of radiation. In this type of materials, the free radicals induced by the radiation are stable and their concentration is proportional to the absorbed dose may be determined by the amplitude pick to pick of the first derived of the EPR absorption spectrum. The obtained results studying the EPR response of lactose tablets elaborated in the Universidad Autonoma Metropolitana, Unidad Iztapalapa are presented. The tablets were irradiated with gamma radiation of {sup 60}Co in the irradiator Gamma beam 651-Pt of the Instituto de Ciencias Nucleares de la Universidad Nacional Autonoma de Mexico to a dose rate of 8 kGy-h{sup -1} and their EPR response in a EPR spectrometer e-scan Bruker. The obtained response in function of the dose was lineal in the interval of 1 at 10 kGy. The lactose sensibility was compared with the l-alanine, used as reference, and the result was consistently 0.25 of this. Due to the linearity shown in the interval of used dose and their low production cost, we conclude that the lactose is a promissory option for the dosimetry of high dose of radiation. (author)

  17. EPR and optical studies of VO2+ doped potassium succinate-succinic acid single crystal - Substitutional incorporation

    Science.gov (United States)

    Juliet sheela, K.; Radha Krishnan, S.; Shanmugam, V. M.; Subramanian, P.

    2017-03-01

    EPR and optical absorption studies of VO2+ doped potassium succinate-succinic acid (KSSA) single crystal has been examined at room temperature. EPR spectrum shows that well resolved hyperfine lines. The angular variation of the EPR spectra has shown that two different VO2+ complexes are located in different chemical environments. Among the number of sites, two sites have been followed and reported here. From the EPR analysis, spin Hamiltonian parameters g and A tensors and their directional cosines are evaluated. Both the sites experience rhombic crystal field symmetry around the impurity ion. The VO2+ ion entering the site location of potassium ion has coordination of eight oxygen atoms in a distorted dodecahedral arrangement. The Optical absorption spectrum studied at room temperature shows bands corresponding to C4v symmetry. The crystal field parameter and tetragonal field parameters are calculated. From the Optical and EPR data various molecular orbital coefficients are evaluated and the nature of bonding in the crystal is discussed.

  18. Tooth enamel EPR dosimetry of neutrons: Enhancement of the apparent sensitivity at irradiation in the human head phantom

    Energy Technology Data Exchange (ETDEWEB)

    Khailov, A.M. [Medical Radiological Research Center, Korolyov str., 4, Obninsk 249032 (Russian Federation); Ivannikov, A.I. [Medical Radiological Research Center, Korolyov str., 4, Obninsk 249032 (Russian Federation)], E-mail: ivannikov@mrrc.obninsk.ru; Tikunov, D.D.; Skvortsov, V.G.; Stepanenko, V.F. [Medical Radiological Research Center, Korolyov str., 4, Obninsk 249032 (Russian Federation); Zhumadilov, K.; Tanaka, K.; Endo, S.; Hoshi, M. [Research Institute for Radiation Biology and Medicine, Hiroshima University, Kasumi 1-2-3, Minami-ku, Hiroshima 734-8553 (Japan)

    2007-07-15

    Induction of the EPR signal in tooth enamel at irradiation by the neutrons produced by a generator with maximal energy of 0.8 MeV in the air and in the human head phantom was investigated. Neutron and photon tissue absorbed doses in the mixed radiation field were determined experimentally and calculated using the Monte-Carlo method. It is shown that the EPR signal response of enamel to neutrons relative to the tissue dose is (2{+-}2)% of the appropriate value for {sup 60}Co gamma radiation. At irradiation in the human head phantom, the EPR signal response relatively to the input neutron tissue dose near the surface of the phantom (apparent EPR sensitivity to neutrons) increases to (14{+-}1)%. The observed EPR signal enhancement is caused by absorption in enamel of the secondary photons produced at H(n,{gamma})H{sup 2}, E{sub {gamma}}=2.23MeV reaction in the material of the phantom.

  19. EPR studies of free radicals decay and survival in gamma irradiated aminoglycoside antibiotics: sisomicin, tobramycin and paromomycin.

    Science.gov (United States)

    Wilczyński, Sławomir; Pilawa, Barbara; Koprowski, Robert; Wróbel, Zygmunt; Ptaszkiewicz, Marta; Swakoń, Jan; Olko, Paweł

    2012-02-14

    Radiation sterilization technology is more actively used now that any time because of its many advantages. Gamma radiation has high penetrating power, relatively low chemical reactivity and causes small temperature rise. But on the other hand radiosterilization can lead to radiolytic products appearing, in example free radicals. Free radicals in radiative sterilized sisomicin, tobramycin and paromomycin were studied by electron paramagnetic resonance (EPR) spectroscopy. Dose of gamma irradiation of 25kGy was used. Concentrations and properties of free radicals in irradiated antibiotics were studied. EPR spectra were recorded for samples stored in air and argon. For gamma irradiated antibiotics strong EPR lines were recorded. One- and two-exponential functions were fitted to experimental points during testing and researching of time influence of the antibiotics storage to studied parameters of EPR lines. Our study of free radicals in radiosterilized antibiotics indicates the need for characterization of medicinal substances prior to sterilization process using EPR values. We propose the concentration of free radicals and other spectroscopic parameters as useful factors to select the optimal type of sterilization for the individual drug. The important parameters are i.a. the τ time constants and K constants of exponential functions. Time constants τ give us information about the speed of free radicals concentration decrease in radiated medicinal substances. The constant K(0) shows the free radicals concentration in irradiated medicament after long time of storage.

  20. EPR and optical absorption studies of vanadyl impurity in zinc potassium phosphate hexahydrate single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Kripal, Ram, E-mail: ram_kripal2001@rediffmail.co [Department of Physics, University of Allahabad, Allahabad 211002 (India); Maurya, Manju, E-mail: mmanju8@yahoo.co.i [Department of Physics, University of Allahabad, Allahabad 211002 (India); Bajpai, Manisha [Department of Physics, University of Allahabad, Allahabad 211002 (India); Govind, Har [Department of Electronics, Ewing Christian College, Allahabad 211003 (India)

    2009-11-01

    Electron paramagnetic resonance (EPR) study of VO{sup 2+} doped zinc potassium phosphate hexahydrate single crystal is carried out. The angular variation of the spectra is studied in the three crystallographic planes. The principal value of spin Hamiltonian parameters g and A and the direction cosines which principal axes make with the crystallographic axes are determined. The observed values are site I: g{sub ||} =1.9664+-0.0002, g{sub perpendicular} =1.9973+-0.0002, A{sub ||} =150+-2x10{sup -4}, A{sub perpendicular} =60+-2x10{sup -4} cm{sup -1}; site II: g{sub ||} =1.9276+-0.0002, g{sub perpendicular} =1.9921+-0.0002, A{sub ||} =155+-2x10{sup -4} and A{sub perpendicular} =62+-2x10{sup -4} cm{sup -1}. By comparison of direction cosines of g from EPR with the direction cosines of different bonds obtained from crystal structure data it is ascertained that the VO{sup 2+} ion occupies Zn{sup 2+} substitutional sites. The optical absorption study of the crystal at room temperature is also carried out. The bands observed in the optical absorption spectrum are attributed to d-d transitions. The EPR results together with the optical data are employed to estimate the molecular orbital (MO) coefficients. These MO coefficients (also called bonding coefficients) are further used to discuss the nature of bonding of VO{sup 2+} ion with different ligands in the crystal.