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Sample records for 63ni electron capture

  1. Neutron capture cross section of unstable 63Ni: implications for stellar nucleosynthesis.

    PubMed

    Lederer, C; Massimi, C; Altstadt, S; Andrzejewski, J; Audouin, L; Barbagallo, M; Bécares, V; Bečvář, F; Belloni, F; Berthoumieux, E; Billowes, J; Boccone, V; Bosnar, D; Brugger, M; Calviani, M; Calviño, F; Cano-Ott, D; Carrapiço, C; Cerutti, F; Chiaveri, E; Chin, M; Colonna, N; Cortés, G; Cortés-Giraldo, M A; Diakaki, M; Domingo-Pardo, C; Duran, I; Dressler, R; Dzysiuk, N; Eleftheriadis, C; Ferrari, A; Fraval, K; Ganesan, S; García, A R; Giubrone, G; Gómez-Hornillos, M B; Gonçalves, I F; González-Romero, E; Griesmayer, E; Guerrero, C; Gunsing, F; Gurusamy, P; Jenkins, D G; Jericha, E; Kadi, Y; Käppeler, F; Karadimos, D; Kivel, N; Koehler, P; Kokkoris, M; Korschinek, G; Krtička, M; Kroll, J; Langer, C; Leeb, H; Leong, L S; Losito, R; Manousos, A; Marganiec, J; Martínez, T; Mastinu, P F; Mastromarco, M; Meaze, M; Mendoza, E; Mengoni, A; Milazzo, P M; Mingrone, F; Mirea, M; Mondelaers, W; Paradela, C; Pavlik, A; Perkowski, J; Pignatari, M; Plompen, A; Praena, J; Quesada, J M; Rauscher, T; Reifarth, R; Riego, A; Roman, F; Rubbia, C; Sarmento, R; Schillebeeckx, P; Schmidt, S; Schumann, D; Tagliente, G; Tain, J L; Tarrío, D; Tassan-Got, L; Tsinganis, A; Valenta, S; Vannini, G; Variale, V; Vaz, P; Ventura, A; Versaci, R; Vermeulen, M J; Vlachoudis, V; Vlastou, R; Wallner, A; Ware, T; Weigand, M; Weiß, C; Wright, T J; Zugec, P

    2013-01-11

    The 63Ni(n,γ) cross section has been measured for the first time at the neutron time-of-flight facility n_TOF at CERN from thermal neutron energies up to 200 keV. In total, capture kernels of 12 (new) resonances were determined. Maxwellian averaged cross sections were calculated for thermal energies from   kT=5-100  keV with uncertainties around 20%. Stellar model calculations for a 25M⊙ star show that the new data have a significant effect on the s-process production of 63Cu, 64Ni, and 64Zn in massive stars, allowing stronger constraints on the Cu yields from explosive nucleosynthesis in the subsequent supernova.

  2. 63Ni (n ,γ ) cross sections measured with DANCE

    NASA Astrophysics Data System (ADS)

    Weigand, M.; Bredeweg, T. A.; Couture, A.; Göbel, K.; Heftrich, T.; Jandel, M.; Käppeler, F.; Lederer, C.; Kivel, N.; Korschinek, G.; Krtička, M.; O'Donnell, J. M.; Ostermöller, J.; Plag, R.; Reifarth, R.; Schumann, D.; Ullmann, J. L.; Wallner, A.

    2015-10-01

    The neutron capture cross section of the s -process branch nucleus 63Ni affects the abundances of other nuclei in its region, especially 63Cu and 64Zn. In order to determine the energy-dependent neutron capture cross section in the astrophysical energy region, an experiment at the Los Alamos National Laboratory has been performed using the calorimetric 4 π BaF2 array DANCE. The (n ,γ ) cross section of 63Ni has been determined relative to the well-known 197Au standard with uncertainties below 15%. Various 63Ni resonances have been identified based on the Q value. Furthermore, the s -process sensitivity of the new values was analyzed with the new network calculation tool NETZ.

  3. Selective laser ionisation of radionuclide 63Ni

    NASA Astrophysics Data System (ADS)

    Tsvetkov, G. O.; D’yachkov, A. B.; Gorkunov, A. A.; Labozin, A. V.; Mironov, S. M.; Firsov, V. A.; Panchenko, V. Ya.

    2017-02-01

    We report a search for a scheme of selective laser stepwise ionisation of radionuclide 63Ni by radiation of a dye laser pumped by a copper vapour laser. A three-stage scheme is found with ionisation through an autoionising state (AIS): 3d 84s2 3F4(E = 0) → 3d 94p 1Fo3(31030.99 cm‑1) → 3d 94d 2[7/2]4(49322.56 cm‑1) → AIS(67707.61 cm‑1) which, by employing saturated radiation intensities provides the ionisation selectivity of above 1200 for 63Ni.

  4. Determination of fluoxetine and norfluoxetine in plasma by gas chromatography with electron-capture detection

    SciTech Connect

    Nash, J.F.; Bopp, R.J.; Carmichael, R.H.; Farid, K.Z.; Lemberger, L.

    1982-10-01

    This gas-chromatographic method for assay of fluoxetine and norfluoxetine in human plasma involves extraction of the drugs and use of a /sup 63/Ni electron-capture detector. The linear range of detection is 25 to 800 micrograms/L for each drug. Overall precision (CV) in the concentration range of 10 to 100 micrograms/L for both drugs was approximately 10%. Accuracy (relative error) in the same concentration range was approximately +10%. None of the commonly prescribed antidepressants or tranquilizers that we tested interfere with the assay.

  5. Modeling of microporous silicon betaelectric converter with 63Ni plating in GEANT4 toolkit*

    NASA Astrophysics Data System (ADS)

    Zelenkov, P. V.; Sidorov, V. G.; Lelekov, E. T.; Khoroshko, A. Y.; Bogdanov, S. V.; Lelekov, A. T.

    2016-04-01

    The model of electron-hole pairs generation rate distribution in semiconductor is needed to optimize the parameters of microporous silicon betaelectric converter, which uses 63Ni isotope radiation. By using Monte-Carlo methods of GEANT4 software with ultra-low energy electron physics models this distribution in silicon was calculated and approximated with exponential function. Optimal pore configuration was estimated.

  6. Orbital electron capture by the nucleus

    NASA Technical Reports Server (NTRS)

    Bambynek, W.; Behrens, H.; Chen, M. H.; Crasemann, B.; Fitzpatrick, M. L.; Ledingham, K. W. D.; Genz, H.; Mutterer, M.; Intemann, R. L.

    1976-01-01

    The theory of nuclear electron capture is reviewed in the light of current understanding of weak interactions. Experimental methods and results regarding capture probabilities, capture ratios, and EC/Beta(+) ratios are summarized. Radiative electron capture is discussed, including both theory and experiment. Atomic wave function overlap and electron exchange effects are covered, as are atomic transitions that accompany nuclear electron capture. Tables are provided to assist the reader in determining quantities of interest for specific cases.

  7. Isotope separation by photoselective dissociative electron capture

    DOEpatents

    Stevens, Charles G. [Pleasanton, CA

    1978-08-29

    A method of separating isotopes based on photoselective electron capture dissociation of molecules having an electron capture cross section dependence on the vibrational state of the molecule. A molecular isotope source material is irradiated to selectively excite those molecules containing a desired isotope to a predetermined vibrational state having associated therewith an electron capture energy region substantially non-overlapping with the electron capture energy ranges associated with the lowest vibration states of the molecules. The isotope source is also subjected to electrons having an energy corresponding to the non-overlapping electron capture region whereby the selectively excited molecules preferentially capture electrons and dissociate into negative ions and neutrals. The desired isotope may be in the negative ion product or in the neutral product depending upon the mechanism of dissociation of the particular isotope source used. The dissociation product enriched in the desired isotope is then separated from the reaction system by conventional means. Specifically, .sup.235 UF.sub.6 is separated from a UF.sub.6 mixture by selective excitation followed by dissociative electron capture into .sup.235 UF.sub.5 - and F.

  8. Isotope separation by photoselective dissociative electron capture

    DOEpatents

    Stevens, C.G.

    1978-08-29

    Disclosed is a method of separating isotopes based on photoselective electron capture dissociation of molecules having an electron capture cross section dependence on the vibrational state of the molecule. A molecular isotope source material is irradiated to selectively excite those molecules containing a desired isotope to a predetermined vibrational state having associated therewith an electron capture energy region substantially non-overlapping with the electron capture energy ranges associated with the lowest vibration states of the molecules. The isotope source is also subjected to electrons having an energy corresponding to the non-overlapping electron capture region whereby the selectively excited molecules preferentially capture electrons and dissociate into negative ions and neutrals. The desired isotope may be in the negative ion product or in the neutral product depending upon the mechanism of dissociation of the particular isotope source used. The dissociation product enriched in the desired isotope is then separated from the reaction system by conventional means. Specifically, [sup 235]UF[sub 6] is separated from a UF[sub 6] mixture by selective excitation followed by dissociative electron capture into [sup 235]UF[sub 5]- and F. 2 figs.

  9. Radiative electron capture by channeled ions

    SciTech Connect

    Pitarke, J.M. . Zientzi Fakultatea); Ritchie, R.H. Tennessee Univ., Knoxville, TN . Dept. of Physics)

    1989-01-01

    Considerable experimental data have been accumulated relative to the emission of photons accompanying electron capture by swift, highly stripped atoms penetrating crystalline matter under channeling conditions. Recent data suggest that the photon energies may be less than that expected from simple considerations of transitions from the valence band of the solid to hydrogenic states on the moving ion. We have studied theoretically the impact parameter dependence of the radiative electron capture (REC) process, the effect of the ion's wake and the effect of capture from inner shells of the solid on the photon emission probability, using a statistical approach. Numerical comparisons of our results with experiment are made. 13 refs., 6 figs.

  10. Electron capture in carbon dwarf supernovae

    NASA Technical Reports Server (NTRS)

    Mazurek, T. J.; Truran, J. W.; Cameron, A. G. W.

    1974-01-01

    The rates of electron capture on heavier elements under the extreme conditions predicted for dwarf star supernovae have been computed, incorporating modifications that seem to be indicated by present experimental results. An estimate of the maximum possible value of such rates is also given. The distribution of nuclei in nuclear statistical equilibrium has been calculated for the range of expected supernovae conditions, including the effects of the temperature dependence of nuclear partition functions. These nuclide abundance distributions are then used to compute nuclear equilibrium thermodynamic properties. The effects of the electron capture on such equilibrium matter are discussed. In the context of the 'carbon detonation' supernova model, the dwarf central density required to ensure core collapse to a neutron star configuration is found to be slightly higher than that obtained by Bruenn (1972) with the electron capture rates of Hansen (1966).-

  11. Electron capture from solids by positrons

    SciTech Connect

    Howell, R.

    1987-08-01

    The capture of electrons in solids is modified from that in gasses by several factors. The most important is the collective interaction of the electrons which results in a density of electron states in the solid in wide bands. Also the high density of electrons in many solids gives a high frequency of interaction as compared to gasses, and quickly destroys any electron-positron states in the metal matrix. Consequently, most positrons implanted in a metal will rapidly thermalize, and unless they reach the surface will annihilate with an electron in an uncorrelated state. Positronium formation from positrons scattered at a metal surface is analogous to ion neutralization however, most of the positronium comes from positrons passing through the surface from the bulk. The dominant motivation for studying positronium formation has been the hope that the distribution of the electrons at the surface would be obtained through the annihilation properties of positrons trapped at the surface or through analysis of the energy and angular distributions of the positronium emitted into the vacuum. These distributions have been measured and are included in this paper. 17 refs.

  12. Measurement of 59Ni and 63Ni by accelerator mass spectrometry at CIAE

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoming; He, Ming; Ruan, Xiangdong; Xu, Yongning; Shen, Hongtao; Du, Liang; Xiao, Caijin; Dong, Kejun; Jiang, Shan; Yang, Xuran; Lan, Xiaoxi; Wu, Shaoyong; Zhao, Qingzhang; Cai, Li; Pang, Fangfang

    2015-10-01

    The long lived isotopes 59Ni and 63Ni can be used in many areas such as radioactive waste management, neutron dosimetry, cosmic radiation study, and so on. Based on the large accelerator and a big Q3D magnetic spectrometer, the measurement method for 59Ni and 63Ni is under development at the AMS facility at China Institute of Atomic Energy (CIAE). By using the ΔE-Q3D technique with the Q3D magnetic spectrometer, the isobaric interferences were greatly reduced in the measurements of 59Ni and 63Ni. A four anode gas ionization chamber was then used to further identify isobars. With these techniques, the abundance sensitivities of 59Ni and 63Ni measurements are determined as 59Ni/Ni = 1 × 10-13 and 63Ni/Ni = 2 × 10-12, respectively.

  13. Consequences of nuclear electron capture in core collapse supernovae.

    PubMed

    Hix, W R; Messer, O E B; Mezzacappa, A; Liebendörfer, M; Sampaio, J; Langanke, K; Dean, D J; Martínez-Pinedo, G

    2003-11-14

    The most important weak nuclear interaction to the dynamics of stellar core collapse is electron capture, primarily on nuclei with masses larger than 60. In prior simulations of core collapse, electron capture on these nuclei has been treated in a highly parametrized fashion, if not ignored. With realistic treatment of electron capture on heavy nuclei come significant changes in the hydrodynamics of core collapse and bounce. We discuss these as well as the ramifications for the postbounce evolution in core collapse supernovae.

  14. Modified Faddeev treatment of electron capture

    SciTech Connect

    Alston, S. |

    1996-09-01

    The Faddeev multiple-scattering formalism in second order is modified to treat lower projectile energies. The electronic part of the amplitude is evaluated using a Hartree-Fock approximation to the helium wave function and a consistent screened target potential for the active electron. Off-energy-shell scattering states appearing in the electronic part of the full amplitude are corrected for loss of normalization. The high velocity Faddeev nuclear-scattering contribution is normalized to the eikonally transformed electronic amplitude at large angles. An application to proton-helium collisions at 293 keV shows good agreement with the experimental data. The effects of the various approximations are studied. {copyright} {ital 1996 The American Physical Society.}

  15. Radiative electron capture in nonequilibrium plasmas

    SciTech Connect

    Milchberg, H.M.; Weisheit, J.C.

    1982-01-19

    Formulae have been obtained for the degree of linear polarization of recombination radiation from a homogeneous plasma having an anisotropic electron velocity distribution, f(v vector), characterized by an axis of symmetry. Polarization measurements are described which utilize these formulae to determine aspects of the anisotropy such as the symmetry axis direction and the lowest order even angular moments of f(v vector). As a special case, if the plasma conforms to a distribution such as a bi-Maxwellian with drift, one can determine the quantities u/sub D//T/sub parallel to/ and (1/T/sub parallel to/ - 1/T/sub perpendicular to/) which involve the electron drift speed, and the perpendicular and parallel electron temperatures. Also, the radiative recombination rate has been calculated for ions whose speeds are comparable to or greater than the electron thermal speed. The change in the rate is small for thermonuclear products in fusion plasmas, but large for cosmic rays in interstellar plasma.

  16. Electron-capture delayed fission properties of 244Es

    SciTech Connect

    Shaughnessy, Dawn A.; Gregorich, Kenneth E.; Adams, Jeb L.; Lane, Michael R.; Laue, Carola A.; Lee, Diana M.; McGrath, Christopher A.; Ninov, Victor; Patin, Joshua B.; Strellis, Dan A.; Sylwester, Eric R.; Wilk, Philip A.; Hoffman, Darleane C.

    2001-03-16

    Electron-capture delayed fission was observed in {sup 244}Es produced via the {sup 237}Np({sup 12}C,5n){sup 244}Es reaction at 81 MeV (on target) with a production cross section of 0.31{+-}0.12 {micro}b. The mass-yield distribution of the fission fragments is highly asymmetric. The average preneutron-emission total kinetic energy of the fragments was measured to be 186{+-}19 MeV. Based on the ratio of the number of fission events to the measured number of {alpha} decays from the electron-capture daughter {sup 244}Cf (100% {alpha} branch), the probability of delayed fission was determined to be (1.2{+-}0.4) x 10{sup -4}. This value for the delayed fission probability fits the experimentally observed trend of increasing delayed fission probability with increasing Q value for electron-capture.

  17. The role of conformation on electron capture dissociation of ubiquitin.

    PubMed

    Robinson, Errol W; Leib, Ryan D; Williams, Evan R

    2006-10-01

    Effects of protein conformation on electron capture dissociation (ECD) were investigated using high-field asymmetric waveform ion mobility spectrometry (FAIMS) and Fourier-transform ion cyclotron resonance mass spectrometry. Under the conditions of these experiments, the electron capture efficiency of ubiquitin 6+ formed from three different solution compositions differs significantly, ranging from 51 +/- 7% for ions formed from an acidified water/methanol solution to 88 +/- 2% for ions formed from a buffered aqueous solution. This result clearly indicates that these protein ions retain a memory of their solution-phase structure and that conformational differences can be probed in an ECD experiment. Multiple conformers for the 7+ and 8+ charge states of ubiquitin were separated using FAIMS. ECD spectra of conformer selected ions of the same charge states differ both in electron capture efficiency and in the fragment ion intensities. Conformers of a given charge state that have smaller collisional cross sections can have either a larger or smaller electron capture efficiency. A greater electron capture efficiency was observed for ubiquitin 6+ that has the same collisional cross section as one ubiquitin 7+ conformer, despite the lower charge state. These results indicate that the shape of the molecule can have a greater effect on electron capture efficiency than either collisional cross section or charge state alone. The cleavage locations of different conformers of a given charge state were the same indicating that the presence of different conformers in the gas phase is not due to difference in where charges are located, but rather reflect conformational differences most likely originating from solution. Small neutral losses observed from the singly- and doubly-reduced ubiquitin 6+ do not show a temperature dependence to their formation, consistent with these ions being formed by nonergodic processes.

  18. Measurement of internal conversion electrons from Gd neutron capture

    NASA Astrophysics Data System (ADS)

    Kandlakunta, P.; Cao, L. R.; Mulligan, P.

    2013-03-01

    Gadolinium (Gd) is a suitable material for neutron conversion because of its superior neutron absorption cross-section. However, the principal secondary particles that generate electron-hole pairs in a semiconductor detector after Gd neutron capture are low-energy internal conversion (IC) electrons. We measured the IC electron spectrum due to Gd neutron capture by using a thermal neutron beam and a digitizer-based multidetector spectroscopy. We also discussed the effective use of the IC electrons in the context of a twin-detector design and the associated gamma-ray rejection issues. Extensive simulations of the spectra of IC electrons and gamma rays agreed well with the experimental results; both types of results support the feasibility of the proposed n-γ separation method.

  19. Electron-capture supernovae exploding within their progenitor wind

    NASA Astrophysics Data System (ADS)

    Moriya, Takashi J.; Tominaga, Nozomu; Langer, Norbert; Nomoto, Ken'ichi; Blinnikov, Sergei I.; Sorokina, Elena I.

    2014-09-01

    The most massive stars on the asymptotic giant branch (AGB), or the so-called super-AGB stars, are thought to produce supernovae triggered by electron captures in their degenerate O+Ne+Mg cores. Super-AGB stars are expected to have slow winds with high mass-loss rates, so their circumstellar density is high. The explosions of super-AGB stars are therefore presumed to occur in this dense circumstellar environment. We provide the first synthetic light curves for such events by exploding realistic electron-capture supernova progenitors within their super-AGB winds. We find that the early light curve - that is, before the recombination wave reaches the bottom of the hydrogen-rich envelope of supernova ejecta (the plateau phase) - is not affected by the dense wind. However, after the luminosity drop following the plateau phase, the luminosity remains much higher when the super-AGB wind is taken into account. We compare our results to the historical light curve of SN 1054, the progenitor of the Crab Nebula, and show that the explosion of an electron-capture supernova within an ordinary super-AGB wind can explain the observed light curve features. We conclude that SN 1054 could have been a Type IIn supernova without any extra extreme mass loss, which was previously suggested to be necessary to account for its early high luminosity. We also show that our light curves match Type IIn supernovae with an early plateau phase or the so-called Type IIn-P supernovae, and suggest that they are electron-capture supernovae within super-AGB winds. Although some electron-capture supernovae can be bright in the optical spectral range due to the large progenitor radius, their X-ray luminosity from the interaction does not necessarily get as bright as other Type IIn supernovae whose optical luminosities are also powered by the interaction. Thus, we suggest that optically bright X-ray-faint Type IIn supernovae can emerge from electron-capture supernovae. Optically faint Type IIn supernovae

  20. Improvement of electron capture efficiency by resonant excitation.

    PubMed

    Mormann, Michael; Peter-Katalinić, Jasna

    2003-01-01

    A novel pulse sequence improving the efficiency for electron capture dissociation (ECD) of an unmodified Fourier transform ion cyclotron resonance (FTICR) mass spectrometer by more than an order of magnitude is presented. Commercially available FTICR instruments are usually equipped with a filament-based electron source producing an electron beam that has a rather small cross section. An ideal overlap between the rotating ion cloud and the electron beam appears to be a prerequisite for a high ECD efficiency. A reduced interception of the ion cloud and the electron beam is probably due to the contribution of the magnetron motion to the trajectory of the ions, resulting in a precession about the z-axis of the instrument. By increasing the kinetic energy and therefore increasing the cyclotron radii of the precursor ions by resonant excitation, the overlap of the rotating ion cloud with the electron beam is improved. By use of this protocol the efficiency of electron capture is substantially increased and consequently the acquisition time of ECD spectra is reduced significantly. The capability of resonant excitation of the precursor ions during the irradiation with electrons is demonstrated for standard peptides. This approach is particularly valuable for analysis and characterization of O-glycosylated peptides. In addition to amino acid sequence information, the attachment site of the labile glycan moiety is determined, and also radical-site-induced fragmentations of the glycosidic bonds are observed.

  1. Electron capture from Ni surface resulting from H+ ion impact

    NASA Astrophysics Data System (ADS)

    Suzuki, Reiko; Suzuki, Reiko; Sato, Hiroshi; Kimura, Mineo

    1998-10-01

    Electron capture from Cu and Co surfaces by H+ and He+ ion bombardment has been investigated theoretically by using the molecular representation. Since an experimental condition was that the incoming particle was introduced on the surface with a large angle, the binary collision would be satisfied. We have obtained electronic states of the colliding pair by the ALCHEMY, and the scattering dynamics was solved by using the semiclassical close coupling treatment. We have included trajectories of compete recoils of the projectile through the coupling of electronic and nuclear motions. The preliminary result obtained shed much light on the understanding of the experimental finding.

  2. Thomas double scattering in electron capture from oriented molecular hydrogen

    SciTech Connect

    Alston, S.; Brennan, T.; Bannon, F.

    1995-11-01

    Electron capture from hydrogen molecules by protons is treated using the second-order Born approximation. Differential cross sections in an adiabatic-nuclei approximation for specific molecular orientations and for an equally weighted averaging over all orientations are presented for incident energies of 2.5 and 10 MeV. A Hartree-Fock molecular wave function and linearized-propagator approximation are employed to evaluate the amplitude. An approximate factoring of the amplitude into double scattering and diffraction (arising from the two target nuclei) components is shown to give a poor description of high-velocity molecular capture.

  3. Electron capture dissociation in a digital ion trap mass spectrometer.

    PubMed

    Ding, Li; Brancia, Francesco L

    2006-03-15

    Electron capture dissociation was implemented in a digital ion trap without using any magnetic field to focus the electrons. Since rectangular waveforms are employed in the DIT for both trapping and dipole excitation, electrons can be injected into the trap when the electric field is constant. Following deceleration, electrons reach the precursor ion cloud. The fragment ions produced by interactions with the electron beam are subsequently analyzed by resonant ejection. [Glu(1)]-Fibrinopeptide B and substance P were used to evaluate the performance of the current design. Fragmentation efficiency of 5.5% was observed for substance P peptide ions. Additionally, analysis of the monophosphorylated peptide FQ[pS]EEQQQTEDELQDK shows that in the resulting c- and z-type ions, the phosphate group is retained on the phophoserine residue, providing information on which amino acid residue the modification is located.

  4. On the stability of (3)H and (63)Ni Ultima Gold liquid scintillation sources.

    PubMed

    Nedjadi, Youcef; Duc, Pierre-François; Bochud, François; Bailat, Claude

    2016-12-01

    The stability of (3)H and (63)Ni samples, made with Ultima Gold and Ultima Gold AB using eight aqueous fractions ranging between 0.1% and 10%, was monitored over a period of 32 weeks. Counting rate losses were measured in all cases, but were found to be particularly severe for samples with low aqueous fractions. Hydrodynamic diameter measurements of the reverse micelles of (3)H and (63)Ni in Ultima Gold and Ultima Gold AB samples were performed with dynamic light scattering. For Ultima Gold, the micelle diameters were measured to be about 2nm and slightly dependent of the aqueous fraction, while for Ultima Gold AB they were found to vary strongly with the aqueous fraction and range between 1 and 4nm. The hypothesis that the counting rate instabilities derive from changes in the sizes of micelles was tested by measuring them four times over the monitoring period. The measurement results do not support this claim.

  5. Can electron capture tell us the mass of the neutrino?

    NASA Astrophysics Data System (ADS)

    Faessler, Amand; Šimkovic, F.

    2016-04-01

    The neutrino masses are one of the most important open problems in particle physics. Presently major efforts are underway to measure the electron antineutrino-mass by the triton beta decay [1] and the effective Majorana neutrino mass by the double beta decay [2]. The best way to determine the neutrino mass by electron capture was assumed to be in {}163{Ho}. The total decay energy of the excited daughter atom has for all excitations the same upper energy limit of the Q-value minus the mass of the electron neutrino. Recently Robertson [3] claimed, that the excitation of the two-hole states makes the determination of the neutrino mass by this method practically impossible. But Faessler and Simkovic [4] showed, that the influence of the two-hole states is less than 1% near the Q-value, the area relevant for the determination of the neutrino mass. Even weaker are the contributions of the three-hole states [5]. The upper end of the calorimetric deexcitation spectrum of Dy is dominated by the highest energy one-hole resonance. With a Lorentzian profile of this resonance one has to fit after including the experimental sensitivity four parameters: (1) the neutrino mass, (2) the Q-value, (3) the width of the resonance and (4) its strength. This contribution discusses the problems of the determination of the neutrino mass by electron capture in {}163{Ho}. The conclusion of this work is, that the determination of the electron neutrino mass by electron capture in {}163{Ho} is difficult, but (probably) not impossible.

  6. Considerations for electron capture dissociation efficiency in FTICR mass spectrometry

    NASA Astrophysics Data System (ADS)

    Gorshkov, Michael V.; Masselon, Christophe D.; Nikolaev, Eugene N.; Udseth, Harold R.; Pasa-Tolic, Ljiljana; Smith, Richard D.

    2004-05-01

    An experimental approach for increasing the efficiency of Electron Capture Dissociation (ECD) with Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) is presented. The approach is based on manipulating the spatial distribution of an ion cloud inside an FTICR trap during electron irradiation, which is realized by using both on-resonance pre-excitation of the ions and sustained off-resonance irradiation (SORI). The achieved fragmentation efficiency is compared with the theoretical prediction. This method may be useful in biological applications of FTICR, such as identification of posttranslational modifications in proteins and de novo sequencing, where the ECD technique is most applicable.

  7. Kinematic Isotope Effects in Low Energy Electron Capture

    SciTech Connect

    Stancil, P.C.; Zygelman, B.

    1995-08-21

    The replacement of hydrogen with its isotope deuterium, in collisions with multiply charged ions, is shown to lead to a suppression of total charge transfer cross sections at collision energies much higher than previously thought. We demonstrate, using a fully quantal calculation of electron capture in collisions of N{sup 4+}(2{ital s}) with H(1{ital s}) and D(1{ital s}), that this isotope effect is significant for capture into the N{sup 3+}(3{ital d}) states at collision energies approaching 10 eV/amu. Estimates of the magnitude of the effect, using the semiclassical Landau-Zener-Stueckelberg model, are made for several multiply charged systems.

  8. Scalable sensing electronics towards a motion capture suit

    NASA Astrophysics Data System (ADS)

    Xu, Daniel; Gisby, Todd A.; Xie, Shane; Anderson, Iain A.

    2013-04-01

    Being able to accurately record body motion allows complex movements to be characterised and studied. This is especially important in the film or sport coaching industry. Unfortunately, the human body has over 600 skeletal muscles, giving rise to multiple degrees of freedom. In order to accurately capture motion such as hand gestures, elbow or knee flexion and extension, vast numbers of sensors are required. Dielectric elastomer (DE) sensors are an emerging class of electroactive polymer (EAP) that is soft, lightweight and compliant. These characteristics are ideal for a motion capture suit. One challenge is to design sensing electronics that can simultaneously measure multiple sensors. This paper describes a scalable capacitive sensing device that can measure up to 8 different sensors with an update rate of 20Hz.

  9. Electron capture by bare ions on water molecules

    NASA Astrophysics Data System (ADS)

    Rivarola, Roberto; Montenegro, Pablo; Monti, Juan; Fojón, Omar

    2016-05-01

    Single electron capture from water molecules by impact of bare ions is theoretically investigated at intermediate and high collision energies. This reaction is of fundamental importance to determine the deposition of energy in biological matter irradiated with ion beams (hadrontherapy), dominating other ionizing processes of the target at low-intermediate impact velocities and giving principal contributions to the energetic region where electronic stopping power maximizes. The dynamics of the interaction between the aggregates is described within the one active-electron continuum distorted wave-eikonal initial state theory. The orbitals of the target in the ground state are represented using the approximate self-consistent complete neglect of differential orbitals (SC-CNDO) model. The contribution of different molecular orbitals on the partial cross sections to selected n-principal quantum number projectile states is discriminated as well as the collaboration of these n-states on total cross sections. The latter ones are dominated by capture to n=1 states at high enough energies decreasing their contribution as n increases.

  10. Decay curve study in a standard electron capture decay

    SciTech Connect

    Nishimura, D.; Fukuda, M.; Kisamori, K.; Kuwada, Y.; Makisaka, K.; Matsumiya, R.; Matsuta, K.; Mihara, M.; Takagi, A.; Yokoyama, R.; Izumikawa, T.; Ohtsubo, T.; Suzuki, T.; Yamaguchi, T.

    2010-05-12

    We have searched for a time-modulated decay in a standard electron capture experiment for {sup 140}Pr, in order to confirm a report from GSI, where an oscillatory decay has been observed for hydrogen-like {sup 140}Pr and {sup 142}Pm ions in the cooler storage ring. {sup 140}Pr has been produced with the {sup 140}Ce(p, n) reaction by a pulsed proton beam accelerated from the Van de Graaff accelerator at Osaka University. Resultant time dependence of the K{sub a}lpha and K{sub b}eta X-ray intensities from the daughter shows no oscillatory behavior.

  11. Electron capture acceleration channel in a slit laser beam

    SciTech Connect

    Wang, P. X.; Scheid, W.; Ho, Y. K.

    2007-03-12

    Using numerical simulations, the authors find that the electrons can be captured and accelerated to high energies (GeV) in a slit laser beam with an intensity of I{lambda}{sup 2}{approx}10{sup 20} W/cm{sup 2} {mu}m{sup 2}, where {lambda} is the laser wavelength in units of {mu}m. The range of the optimum incident energy is very wide, even up to GeV. These results are of interest for experiments because the relatively low intensity can be achieved with present chirped pulse amplification technique and a wide range of incident energies means that a multistage acceleration is possible.

  12. CP-violation reach of an electron capture neutrino beam

    NASA Astrophysics Data System (ADS)

    Orme, Christopher

    2010-07-01

    This article extends the work of Bernabeu and Espinoza by examining the CP-violation reach of a 150Dy electron capture beam through the variation of the two Lorentz boosts, the number of useful electron capture decays, the relative run time of each boost and the number of atmospheric backgrounds. The neutrinos are assumed to be sourced at CERN with an upgraded SPS and are directed towards a 440 kton Water Cerenkov detector located at the Canfranc laboratory. Two large ‘CP-coverage’ choices for the boost pairings are found; a δ-symmetrical coverage for ( γ 1, γ 2) = (280, 160) and an δ-asymmetric coverage for ( γ 1 , γ 2) = (440,150). With a nominal useful decay rate of N ions = 1018 ions per year, the δ-symmetric setup can rule out CP-conservation down to sin2 2 θ 13 = 3•10-4. To reach sin2 2 θ 13 =1•10-3 for both δ < 0 and δ > 0 requires a useful decay rate of N ions = 6•1017 ions per year.

  13. Atomic electron excitation probabilities during orbital electron capture by the nucleus

    NASA Technical Reports Server (NTRS)

    Crasemann, B.; Chen, M. H.; Briand, J. P.; Chevallier, P.; Chetioui, A.; Tavernier, M.

    1979-01-01

    Approximate probabilities of electron excitation (shakeup/shakeoff) from various atomic states during nuclear ns electron capture have been calculated in the sudden approximation, using Hartree-Fock wave functions. Total excitation probabilities are much lower than during inner-shell ionization by photons or electrons, and ns states are more likely to be excited than np states. This latter result is borne out by K-alpha X-ray satellite spectra.

  14. Uncertainties in 63Ni and 55Fe determinations using liquid scintillation counting methods.

    PubMed

    Herranz, M; Idoeta, R; Abelairas, A; Legarda, F

    2012-09-01

    The implementation of (63)Ni and (55)Fe determination methods in an environmental laboratory implies their validation. In this process, the uncertainties related to these methods should be analysed. In this work, the expression of the uncertainty of the results obtained using separation methods followed by liquid scintillation counting is presented. This analysis includes the consideration of uncertainties coming from the different alternatives which these methods use as well as those which are specific to the individual laboratory and the competency of its operators in applying the standard ORISE (Oak Ridge Institute for Science and Education) methods.

  15. Capturing Polyradical Protein Cations after an Electron Capture Event: Evidence for their Stable Distonic Structures in the Gas Phase

    NASA Astrophysics Data System (ADS)

    Baba, Takashi; Campbell, J. Larry

    2015-08-01

    We report on the formation and "capture" of polyradical protein cations after an electron capture event. Performed in a unique electron-capture dissociation (ECD) instrument, these experiments can generate reduced forms of multiply protonated proteins by sequential charge reduction using electrons with ~1 eV. The true structures of these possible polyradicals is considered: Do the introduced unpaired electrons recombine quickly to form a new two-electron bond, or do these unpaired electrons exist as radical sites with appropriate chemical reactivity? Using an established chemical probe—radical quenching with molecular oxygen—we demonstrate that these charge-reduced protein cations are indeed polyradicals that form adducts with up to three molecules of oxygen (i.e., tri-radical protein cations) that are stable for at least 100 ms.

  16. Measurement of {sup 63}Ni and {sup 59}Ni by accelerator mass spectrometry using characteristic projectile x-rays

    SciTech Connect

    McAninch, J.E.; Hainsworth, L.J.; Marchetti, A.A.

    1996-05-01

    The long-lived isotopes of nickel ({sup 59}Ni, {sup 63}Ni) have current and potential use in a number of applications including cosmic radiation studies, biomedical tracing, characterization of low-level radioactive wastes, and neutron dosimetry. Methods are being developed at LLNL for the routine detection of these isotopes by AMS. One intended application is in Hiroshima dosimetry. The reaction {sup 63}Cu(n,p){sup 63}Ni has been identified as one of a small number of reactions which might be used for the direct determination of the fast neutron fluence emitted by the Hiroshima bomb. AMS measurement of {sup 63}Ni(t{sub 1/2} = 100 y) requires the chemical removal of {sup 63}Cu, which is a stable isobar of {sup 63}Ni. Following the electrochemical separation of Ni from gram-sized copper samples, the Cu concentration is further lowered to < 2 x 10{sup -8} (Cu/Ni) using the reaction of Ni with carbon monoxide to form the gas Ni(CO){sub 4}. The Ni(CO){sub 4} is thermally decomposed directly in sample holders for measurement by AMS. After analysis in the AMS spectrometer, the ions are identified using characteristic projectile x-rays, allowing further rejection of remaining {sup 63}Cu. In a demonstration experiment, {sup 63}Ni was measured in Cu wires (2-20 g) which had been exposed to neutrons from a {sup 252}Cf source. We successfully measured {sup 63}Ni at levels necessary for the measurement of Cu samples exposed near the Hiroshima hypocenter. For the demonstration samples, the Cu content was chemically reduced by a factor of 10{sup 12} with quantitative retention of {sup 63}Ni. Detection sensitivity (3{sigma}) was {approximately}20 fg {sup 63}Ni in 1 mg Ni carrier ({sup 63}Ni/Ni {approx} 2 x 10{sup -11}). Significant improvements in sensitivity are expected with planned incremental changes in the methods. Preliminary results indicate that a similar sensitivity is achievable for {sup 59}Ni (t{sub 1/2} = 10{sup 5} y).

  17. Neutron-induced 63Ni activity and microscopic observation of copper samples exposed to the Hiroshima atomic bomb

    NASA Astrophysics Data System (ADS)

    Shizuma, Kiyoshi; Endo, Satoru; Shinozaki, Kenji; Fukushima, Hiroshi

    2013-05-01

    Fast neutron activation data for 63Ni in copper samples exposed to the Hiroshima atomic bomb are important in evaluating neutron doses to the survivors. Up to until now, accelerator mass spectrometry and liquid scintillation counting methods have been applied in 63Ni measurements and data were accumulated within 1500 m from the hypocenter. The slope of the activation curve versus distance shows reasonable agreement with the calculation result, however, data near the hypocenter are scarce. In the present work, two copper samples obtained from the Atomic bomb dome (155 m from the hypocenter) and the Bank of Japan building (392 m) were utilized in 63Ni beta-ray measurement with a Si surface barrier detector. Additionally, microscopic observation of the metal surfaces was performed for the first time. Only upper limit of 63Ni production was obtained for copper sample of the Atomic bomb dome. The result of the 63Ni measurement for Bank of Japan building show reasonable agreement with the AMS measurement and to fast neutron activation calculations based on the Dosimetry System 2002 (DS02) neutrons.

  18. Cross sections of electron capture and electron capture with ionization of argon atoms by fast 3He2+ ions at various impact parameters

    NASA Astrophysics Data System (ADS)

    Afrosimov, V. V.; Basalaev, A. A.; Panov, M. N.

    2017-01-01

    The absolute differential cross sections of scattering of fast particles formed in processes with capture of one or two electrons from Ar atoms have been measured for 6-keV He2+ ions in the interval of scattering angles within 0°-2.5°. The cross sections of electron capture and electron capture with ionization have been determined as functions of the impact parameter. The probabilities of these processes are compared to the distribution of electron density in various shells of target atoms. Applicability of the models of screened Coulomb interaction potentials to description of the scattering of recharged particles is assessed.

  19. Analysis of electron capture process in charge pumping sequence using time domain measurements

    SciTech Connect

    Hori, Masahiro Watanabe, Tokinobu; Ono, Yukinori; Tsuchiya, Toshiaki

    2014-12-29

    A method for analyzing the electron capture process in the charge pumping (CP) sequence is proposed and demonstrated. The method monitors the electron current in the CP sequence in time domain. This time-domain measurements enable us to directly access the process of the electron capture to the interface defects, which are obscured in the conventional CP method. Using the time-domain measurements, the rise time dependence of the capture process is systematically investigated. We formulate the capture process based on the rate equation and derive an analytic form of the current due to the electron capture to the defects. Based on the formula, the experimental data are analyzed and the capture cross section is obtained. In addition, the time-domain data unveil that the electron capture process completes before the electron channel opens, or below the threshold voltage in a low frequency range of the pulse.

  20. ELECTRON-CAPTURE SUPERNOVAE AS ORIGIN OF {sup 48}Ca

    SciTech Connect

    Wanajo, Shinya; Janka, Hans-Thomas; Mueller, Bernhard

    2013-04-20

    We report that electron-capture supernovae (ECSNe), arising from collapsing oxygen-neon-magnesium cores, are a possible source of {sup 48}Ca, whose origin has remained a longstanding puzzle. Our two-dimensional, self-consistent explosion model of an ECSN predicts ejection of neutron-rich matter with electron fractions Y{sub e} Almost-Equal-To 0.40-0.42 and relatively low entropies, s Almost-Equal-To 13-15 k{sub B} per nucleon (k{sub B} is the Boltzmann constant). Post-processing nucleosynthesis calculations result in appreciable production of {sup 48}Ca in such neutron-rich and low-entropy matter during the quasi-nuclear equilibrium and subsequent freezeout phases. The amount of ejected {sup 48}Ca can account for that in the solar inventory when we consider possible uncertainties in the entropies. ECSNe could thus be a site of {sup 48}Ca production in addition to a hypothetical, rare class of high-density Type Ia supernovae.

  1. Bioaccumulation of 51Cr, 63Ni and 14C in Baltic Sea benthos.

    PubMed

    Kumblad, L; Bradshaw, C; Gilek, M

    2005-03-01

    The Baltic Sea is a species-poor, semi-enclosed, brackish sea, whose sediments contain a wide range of contaminants, including sediment-associated metals and radionuclides. In this study, we have examined and compared bioaccumulation kinetics and assimilation efficiencies of sediment-associated (51)Cr, (63)Ni and (14)C in three key benthic invertebrates (the deposit-feeding Monoporeia affinis, the facultative deposit-feeding Macoma baltica, and the omnivorous Halicryptus spinulosus). Our results demonstrate that (i) all radionuclides were accumulated, (ii) the different radionuclides were accumulated to various extents, (iii) small changes in organic carbon concentration can influence the accumulation, and (iv) the degree of accumulation differed only slightly between species. These processes, together with sediment resuspension and bioturbation, may remobilise trace metals from the sediment to the water and to higher trophic levels, and therefore should be taken into account in exposure models and ERAs.

  2. NUCLEOSYNTHESIS IN ELECTRON CAPTURE SUPERNOVAE OF ASYMPTOTIC GIANT BRANCH STARS

    SciTech Connect

    Wanajo, S.; Nomoto, K.; Janka, H.-T.; Kitaura, F. S.; Mueller, B. E-mail: nomoto@astron.s.u-tokyo.ac.jp E-mail: kitaura@mpa-garching.mpg.de

    2009-04-10

    We examine nucleosynthesis in the electron capture supernovae of progenitor asymptotic giant branch stars with an O-Ne-Mg core (with the initial stellar mass of 8.8 M {sub sun}). Thermodynamic trajectories for the first 810 ms after core bounce are taken from a recent state-of-the-art hydrodynamic simulation. The presented nucleosynthesis results are characterized by a number of distinct features that are not shared with those of other supernovae from the collapse of stars with iron core (with initial stellar masses of more than 10 M {sub sun}). First is the small amount of {sup 56}Ni (0.002-0.004 M {sub sun}) in the ejecta, which can be an explanation for the observed properties of faint supernovae such as SNe 2008S and 1997D. In addition, the large Ni/Fe ratio is in reasonable agreement with the spectroscopic result of the Crab nebula (the relic of SN 1054). Second is the large production of {sup 64}Zn, {sup 70}Ge, light p-nuclei ({sup 74}Se, {sup 78}Kr, {sup 84}Sr, and {sup 92}Mo), and in particular, {sup 90}Zr, which originates from the low Y{sub e} (0.46-0.49, the number of electrons per nucleon) ejecta. We find, however, that only a 1%-2% increase of the minimum Y{sub e} moderates the overproduction of {sup 90}Zr. In contrast, the production of {sup 64}Zn is fairly robust against a small variation of Y{sub e} . This provides the upper limit of the occurrence of this type of events to be about 30% of all core-collapse supernovae.

  3. Electron capture dissociation mass spectrometry of tyrosine nitrated peptides.

    PubMed

    Jones, Andrew W; Mikhailov, Victor A; Iniesta, Jesus; Cooper, Helen J

    2010-02-01

    In vivo protein nitration is associated with many disease conditions that involve oxidative stress and inflammatory response. The modification involves addition of a nitro group at the position ortho to the phenol group of tyrosine to give 3-nitrotyrosine. To understand the mechanisms and consequences of protein nitration, it is necessary to develop methods for identification of nitrotyrosine-containing proteins and localization of the sites of modification. Here, we have investigated the electron capture dissociation (ECD) and collision-induced dissociation (CID) behavior of 3-nitrotyrosine-containing peptides. The presence of nitration did not affect the CID behavior of the peptides. For the doubly-charged peptides, addition of nitration severely inhibited the production of ECD sequence fragments. However, ECD of the triply-charged nitrated peptides resulted in some singly-charged sequence fragments. ECD of the nitrated peptides is characterized by multiple losses of small neutral species including hydroxyl radicals, water and ammonia. The origin of the neutral losses has been investigated by use of activated ion (AI) ECD. Loss of ammonia appears to be the result of non-covalent interactions between the nitro group and protonated lysine side-chains.

  4. ELECTRON-CAPTURE SUPERNOVAE AS SOURCES OF {sup 60}Fe

    SciTech Connect

    Wanajo, Shinya; Janka, Hans-Thomas; Mueller, Bernhard

    2013-09-01

    We investigate the nucleosynthesis of the radionuclide {sup 60}Fe in electron-capture supernovae (ECSNe). The nucleosynthetic results are based on a self-consistent, two-dimensional simulation of an ECSN as well as models in which the densities are systematically increased by some factors (low-entropy models). {sup 60}Fe is found to be appreciably made in neutron-rich ejecta during the nuclear quasi-equilibrium phase with greater amounts being produced in the lower-entropy models. Our results, combining them with the yields of core-collapse supernovae in the literature, suggest that ECSNe account for at least 4%-30% of live {sup 60}Fe in the Milky Way. ECSNe co-produce neutron-rich isotopes, {sup 48}Ca, {sup 50}Ti, {sup 54}Cr, some light trans-iron elements, and possibly weak r-process elements including some radionuclides such as {sup 93}Zr, {sup 99}Tc, and {sup 107}Pd, whose association with {sup 60}Fe might have been imprinted in primitive meteorites or in the deep ocean crust on the Earth.

  5. Use of silicon pixel detectors in double electron capture experiments

    NASA Astrophysics Data System (ADS)

    Cermak, P.; Stekl, I.; Shitov, Yu A.; Mamedov, F.; Rukhadze, E. N.; Jose, J. M.; Cermak, J.; Rukhadze, N. I.; Brudanin, V. B.; Loaiza, P.

    2011-01-01

    A novel experimental approach to search for double electron capture (EC/EC) is discussed in this article. R&D for a new generation EC/EC spectrometer based on silicon pixel detectors (SPDs) has been conducted since 2009 for an upgrade of the TGV experiment. SPDs built on Timepix technology with a spectroscopic readout from each individual pixel are an effective tool to detect the 2νEC/EC signature of the two low energy X-rays hitting two separate pixels. The ability of SPDs to indentify α/β/γ particles and localize them precisely leads to effective background discrimination and thus considerable improvement of the signal-to-background ratio (S/B). A multi-SPD system, called a Silicon Pixel Telescope (SPT), is planned based on the experimental approach of the TGV calorimeter which measures thin foils of enriched EC/EC-isotope sandwiched between HPGe detectors working in coincidence mode. The sources of SPD internal background have been identified by measuring SPD radiopurity with a low-background HPGe detector as well as by long-term SPD background runs in the Modane underground laboratory (LSM, France), and results of these studies are presented.

  6. Electron capture processes in ZnS: The role of Al related and other donors

    NASA Astrophysics Data System (ADS)

    Przybylińska, H.; Godlewski, M.

    1986-12-01

    A transient electron spin resonance experiment shows that the Al-related donor in ZnS plays an insignificant role in electron-capture processes, which are dominated by a 35-meV native donor of unknown nature. The methods of determining effective capture cross sections of these donors are discussed.

  7. Absolute differential cross sections for electron capture and loss by kilo-electron-volt hydrogen atoms

    NASA Technical Reports Server (NTRS)

    Smith, G. J.; Johnson, L. K.; Gao, R. S.; Smith, K. A.; Stebbings, R. F.

    1991-01-01

    This paper reports measurements of absolute differential cross sections for electron capture and loss for fast hydrogen atoms incident on H2, N2, O2, Ar, and He. Cross sections have been determined in the 2.0- to 5.0-keV energy range over the laboratory angular range 0.02-2 deg, with an angular, resolution of 0.02 deg. The high angular resolution allows observation of the structure at small angles in some of the cross sections. Comparison of the present results with those of other authors generally shows very good agreement.

  8. Electron capture and single ionization in H+ + Ar collisions: classical calculations

    NASA Astrophysics Data System (ADS)

    Frémont, F.

    2016-03-01

    A classical model is used to study electron capture and single ionization (SI) following H+ + Ar collisions at projectile energies varying from 400 to 40 keV. In the present model, the Ar electrons are treated independently from each other, and only the 3s and 3p electrons are supposed to be captured by the projectile. In addition, a Coulombic potential with an effective charge Z eff = 6.75, derived from Slater rules, is used in the calculations to simulate the screening of the Ar nucleus due to the presence of the core and 2l electrons. Total cross sections for single electron capture and SI are calculated and compared with previous experiments and earlier calculations based on a semiclassical approach. The reasonable agreement we observed allows a preliminary study of double electron capture (DC). The total cross section for DC is found to be much larger than the experimental one. Possible reasons for this disagreement are discussed.

  9. Temperature dependence of an AlInP 63Ni betavoltaic cell

    NASA Astrophysics Data System (ADS)

    Butera, S.; Lioliou, G.; Krysa, A. B.; Barnett, A. M.

    2016-10-01

    In this paper, the performance of an Al0.52In0.48P 63Ni radioisotope cell is reported over the temperature range of -20 °C to 140 °C. A 400 μm diameter p+-i-n+ (2 μm i-layer) Al0.52In0.48P mesa photodiode was used as a conversion device in a novel betavoltaic cell. Dark current measurements on the Al0.52In0.48P detector showed that the saturation current increased increasing the temperature, while the ideality factor decreased. The effects of the temperature on the key cell parameters were studied in detail showing that the open circuit voltage, the maximum output power, and the internal conversion efficiency decreased when the temperature was increased. At -20 °C, an open circuit voltage and a maximum output power of 0.52 V and 0.28 pW, respectively, were measured.

  10. Application of TDCR-Geant4 modeling to standardization of 63Ni.

    PubMed

    Thiam, C; Bobin, C; Chauvenet, B; Bouchard, J

    2012-09-01

    As an alternative to the classical TDCR model applied to liquid scintillation (LS) counting, a stochastic approach based on the Geant4 toolkit is presented for the simulation of light emission inside the dedicated three-photomultiplier detection system. To this end, the Geant4 modeling includes a comprehensive description of optical properties associated with each material constituting the optical chamber. The objective is to simulate the propagation of optical photons from their creation in the LS cocktail to the production of photoelectrons in the photomultipliers. First validated for the case of radionuclide standardization based on Cerenkov emission, the scintillation process has been added to a TDCR-Geant4 modeling using the Birks expression in order to account for the light-emission nonlinearity owing to ionization quenching. The scintillation yield of the commercial Ultima Gold LS cocktail has been determined from double-coincidence detection efficiencies obtained for (60)Co and (54)Mn with the 4π(LS)β-γ coincidence method. In this paper, the stochastic TDCR modeling is applied for the case of the standardization of (63)Ni (pure β(-)-emitter; E(max)=66.98 keV) and the activity concentration is compared with the result given by the classical model.

  11. Determination of 63Ni and 59Ni in spent ion-exchange resin and activated charcoal from the IEA-R1 nuclear research reactor.

    PubMed

    Taddei, M H T; Macacini, J F; Vicente, R; Marumo, J T; Sakata, S K; Terremoto, L A A

    2013-07-01

    A radiochemical method has been adapted to determine (59)Ni and (63)Ni in samples of radioactive wastes from the water cleanup system of the IEA-R1 nuclear research reactor. The process includes extraction chromatographic resin with dimethylglyoxime (DMG) as a functional group. Activity concentrations of (59)Ni and (63)Ni were measured, respectively, by X-ray spectrometry and liquid scintillation counting, whereas the chemical yield was determined by ICP-OES. The average ratio of measured activity concentrations of (63)Ni and (59)Ni agree well with theory.

  12. Recent searches for double-electron capture of nuclei to excited states

    SciTech Connect

    Povinec, P. P.; Frekers, D.; Šimkovic, F.

    2015-10-28

    Double electron capture has been of interest of many theoretical and experimental works as a possible extension of double beta-decay investigations. The neutrinoless double-electron capture, similarly as the neutrinoless double beta-decay may help to clarify if neutrinos are Majorana or Dirac particles. Results obtained in several double electron capture experiments are reviewed and new experiments to be carried out in deep underground laboratories using enriched sources and multidimensional HPGe-HPGe gamma-ray spectrometry with a few years of counting time are proposed, which should be able to improve half-lives limits by at least an order of magnitude.

  13. Limit on the radiative neutrinoless double electron capture of ^{36}Ar from GERDA Phase I

    NASA Astrophysics Data System (ADS)

    Agostini, M.; Allardt, M.; Bakalyarov, A. M.; Balata, M.; Barabanov, I.; Barros, N.; Baudis, L.; Bauer, C.; Bellotti, E.; Belogurov, S.; Belyaev, S. T.; Benato, G.; Bettini, A.; Bezrukov, L.; Bode, T.; Borowicz, D.; Brudanin, V.; Brugnera, R.; Caldwell, A.; Cattadori, C.; Chernogorov, A.; D'Andrea, V.; Demidova, E. V.; di Vacri, A.; Domula, A.; Doroshkevich, E.; Egorov, V.; Falkenstein, R.; Fedorova, O.; Freund, K.; Frodyma, N.; Gangapshev, A.; Garfagnini, A.; Gooch, C.; Grabmayr, P.; Gurentsov, V.; Gusev, K.; Hakenmüller, J.; Hegai, A.; Heisel, M.; Hemmer, S.; Heusser, G.; Hofmann, W.; Hult, M.; Inzhechik, L. V.; Csáthy, J. Janicskó; Jochum, J.; Junker, M.; Kazalov, V.; Kihm, T.; Kirpichnikov, I. V.; Kirsch, A.; Kish, A.; Klimenko, A.; Kneißl, R.; Knöpfle, K. T.; Kochetov, O.; Kornoukhov, V. N.; Kuzminov, V. V.; Laubenstein, M.; Lazzaro, A.; Lebedev, V. I.; Lehnert, B.; Liao, H. Y.; Lindner, M.; Lippi, I.; Lubashevskiy, A.; Lubsandorzhiev, B.; Lutter, G.; Macolino, C.; Majorovits, B.; Maneschg, W.; Medinaceli, E.; Miloradovic, M.; Mingazheva, R.; Misiaszek, M.; Moseev, P.; Nemchenok, I.; Palioselitis, D.; Panas, K.; Pandola, L.; Pelczar, K.; Pullia, A.; Riboldi, S.; Rumyantseva, N.; Sada, C.; Salamida, F.; Salathe, M.; Schmitt, C.; Schneider, B.; Schönert, S.; Schreiner, J.; Schütz, A.-K.; Schulz, O.; Schwingenheuer, B.; Selivanenko, O.; Shirchenko, M.; Simgen, H.; Smolnikov, A.; Stanco, L.; Stepaniuk, M.; Vanhoefer, L.; Vasenko, A. A.; Veresnikova, A.; von Sturm, K.; Wagner, V.; Walter, M.; Wegmann, A.; Wester, T.; Wiesinger, C.; Wilsenach, H.; Wojcik, M.; Yanovich, E.; Zhitnikov, I.; Zhukov, S. V.; Zinatulina, D.; Zuber, K.; Zuzel, G.

    2016-12-01

    Neutrinoless double electron capture is a process that, if detected, would give evidence of lepton number violation and the Majorana nature of neutrinos. A search for neutrinoless double electron capture of ^{36}Ar has been performed with germanium detectors installed in liquid argon using data from Phase I of the GERmanium Detector Array ( Gerda) experiment at the Gran Sasso Laboratory of INFN, Italy. No signal was observed and an experimental lower limit on the half-life of the radiative neutrinoless double electron capture of ^{36}Ar was established: T_{1/2} > 3.6 × 10^{21} years at 90% CI.

  14. A Benign, Low Z Electron Capture Agent for Negative Ion TPCs

    NASA Technical Reports Server (NTRS)

    Martoff, C. J.; Dion, M. P.; Hosack, M.; Barton, D.; Black, J. K.

    2008-01-01

    We have identified nitromethane (CH3NO2) as an effective electron capture agent for negative ion TPCs (NITPCs). We present drift velocity and longitudinal diffusion measurements for negative ion gas mixtures using nitromethane as the capture agent. Not only is nitromethane substantially more benign than the only other identified capture agent, CS2, but its low atomic number will enable the use of the NITPC as a photoelectric X-ray polarimeter in the 1-10 keV band.

  15. Image charge effects on electron capture by dust grains in dusty plasmas.

    PubMed

    Jung, Y D; Tawara, H

    2001-07-01

    Electron-capture processes by negatively charged dust grains from hydrogenic ions in dusty plasmas are investigated in accordance with the classical Bohr-Lindhard model. The attractive interaction between the electron in a hydrogenic ion and its own image charge inside the dust grain is included to obtain the total interaction energy between the electron and the dust grain. The electron-capture radius is determined by the total interaction energy and the kinetic energy of the released electron in the frame of the projectile dust grain. The classical straight-line trajectory approximation is applied to the motion of the ion in order to visualize the electron-capture cross section as a function of the impact parameter, kinetic energy of the projectile ion, and dust charge. It is found that the image charge inside the dust grain plays a significant role in the electron-capture process near the surface of the dust grain. The electron-capture cross section is found to be quite sensitive to the collision energy and dust charge.

  16. Dynamics of O{sup 8+}+H electron capture in Debye plasmas

    SciTech Connect

    Liu, L.; Wang, J. G.; Janev, R. K.

    2009-05-15

    The electron capture in O{sup 8+}-H collisions is studied by the two-center atomic-orbital close-coupling method when the interactions of charged particles are screened and have a Yukawa form. Atomic orbitals and eigenenergies of n{<=}7 states on O{sup 7+} and n{<=}2 states on H are calculated as a function of the interaction screening parameter and used in the atomic-orbital close-coupling dynamics scheme to calculate the electron capture cross sections in the energy range of 0.2-50 keV/u. It is shown that the degree of interaction screening determines the reduction in electron binding energies, the number of open electron capture channels, and the strength of the exchange couplings, thus affecting the entire collision dynamics and the magnitude and energy behavior of state-selective cross sections. The changes in electron binding energies and capture cross sections when the interaction screening varies introduce dramatic changes in the radiation spectrum of O{sup 7+}(nl) capture states with respect to the unscreened interaction case. The state-selective electron capture cross sections in this collision system, as well as the intensities of a number of charge exchange spectral lines, for a number of representative screening parameter values are presented and discussed.

  17. Analytical and computational studies of intramolecular electron transfer pertinent to electron transfer and electron capture dissociation mass spectrometry.

    PubMed

    Neff, Diane; Simons, Jack

    2010-01-28

    Earlier work from this group has suggested that, in electron capture and electron-transfer mass spectrometry experiments on positively charged gas-phase samples of polypeptides, the initial electron attachment event most likely occurs at one of the peptide's positively charged sites (e.g., protonated side chains), although electron attachment can occur at a disulfide or amide site ca. 1-10% of the time. Focusing on the 90-99% dominant channel in which initial electron attachment occurs at a positive site, this paper addresses to what extent and over what distances electron transfer can take place from a positively charged site to a disulfide sigma* or amide pi* orbital, because it is thought that it is through such orbitals that disulfide or N-C(alpha) backbone bond cleavage occurs. Ab initio electronic structure calculations show that, as long as an SS sigma* (or OCN pi*) orbital experiences sufficient Coulomb stabilization from proximal positively charged groups, there are a myriad of excited Rydberg states located on positive sites that are able to induce such intrapeptide electron transfer. Computational data show that the transfer rates decay exponentially with distance for a given Rydberg orbital. An analytical model is developed that allows us to estimate the rates of Rydberg-to-valence and Rydberg-to-Rydberg electron transfers as functions of the Rydberg orbitals' n quantum numbers. This model suggests that transfer can occur over very long distances at rates that are more than competitive with the rates of radiationless relaxation within the manifold of Rydberg states (the latter processes eventually terminate the electron-transfer process an thus the disulfide or N-C(alpha) bond cleavages), and it gives formulas for how these rates depend on n (and thus the radial span of the Rydberg orbitals).

  18. Electron capture by an electric dipole in two dimensions

    SciTech Connect

    Glasser, M. L.; Nieto, L. M.

    2007-06-15

    The question of the existence of a nonzero minimum dipole moment D{sub 0} that can sustain an electron bound state for an electric dipole in two dimensions is examined both classically and quantum mechanically. The results suggest that in the latter case, D{sub 0}{<=}0.209 compared to the Fermi-Teller value 0.904 for three dimensions (in atomic units)

  19. Controlled energy-selected electron capture and release in double quantum dots

    NASA Astrophysics Data System (ADS)

    Pont, Federico M.; Bande, Annika; Cederbaum, Lorenz S.

    2013-12-01

    Highly accurate quantum electron dynamics calculations demonstrate that energy can be efficiently transferred between quantum dots. Specifically, in a double quantum dot an incoming electron is captured by one dot and the excess energy is transferred to the neighboring dot and used to remove an electron from this dot. This process is due to long-range electron correlation and shown to be operative at rather large distances between the dots. The efficiency of the process is greatly enhanced by preparing the double quantum dot such that the incoming electron is initially captured by a two-electron resonance state of the system. In contrast to atoms and molecules in nature, double quantum dots can be manipulated to achieve this enhancement. This mechanism leads to a surprisingly narrow distribution of the energy of the electron removed in the process which is explained by resonance theory. We argue that the process could be exploited in practice.

  20. On the cascade capture of electrons at donors in GaAs quantum wells

    SciTech Connect

    Aleshkin, V. Ya.

    2015-09-15

    The impact parameter for the cascade capture of electrons at a charged donor in a GaAs quantum well is calculated. A simple approximate analytical expression for the impact parameter is suggested. The temperature dependence of the impact parameter for the case of electron scattering by the piezoelectric potential of acoustic phonons is determined.

  1. Level-resolved quantum statistical theory of electron capture into many-electron compound resonances in highly charged ions

    NASA Astrophysics Data System (ADS)

    Berengut, J. C.; Harabati, C.; Dzuba, V. A.; Flambaum, V. V.; Gribakin, G. F.

    2015-12-01

    The strong mixing of many-electron basis states in excited atoms and ions with open f shells results in very large numbers of complex, chaotic eigenstates that cannot be computed to any degree of accuracy. Describing the processes which involve such states requires the use of a statistical theory. Electron capture into these "compound resonances" leads to electron-ion recombination rates that are orders of magnitude greater than those of direct, radiative recombination and cannot be described by standard theories of dielectronic recombination. Previous statistical theories considered this as a two-electron capture process which populates a pair of single-particle orbitals, followed by "spreading" of the two-electron states into chaotically mixed eigenstates. This method is similar to a configuration-average approach because it neglects potentially important effects of spectator electrons and conservation of total angular momentum. In this work we develop a statistical theory which considers electron capture into "doorway" states with definite angular momentum obtained by the configuration interaction method. We apply this approach to electron recombination with W20 +, considering 2 ×106 doorway states. Despite strong effects from the spectator electrons, we find that the results of the earlier theories largely hold. Finally, we extract the fluorescence yield (the probability of photoemission and hence recombination) by comparison with experiment.

  2. Development of Holmium-163 electron-capture spectroscopy with transition-edge sensors

    DOE PAGES

    Croce, Mark Philip; Rabin, Michael W.; Mocko, Veronika; ...

    2016-08-01

    Calorimetric decay energy spectroscopy of electron-capture-decaying isotopes is a promising method to achieve the sensitivity required for electron neutrino mass measurement. The very low total nuclear decay energy (QEC < 3 keV) and short half-life (4570 years) of 163Ho make it attractive for high-precision electron-capture spectroscopy (ECS) near the kinematic endpoint, where the neutrino momentum goes to zero. In the ECS approach, an electron-capture-decaying isotope is embedded inside a microcalorimeter designed to capture and measure the energy of all the decay radiation except that of the escaping neutrino. We have developed a complete process for proton irradiation-based isotope production, isolation,more » and purification of 163Ho. We have developed transition-edge sensors for this measurement and methods for incorporating 163Ho into high-resolution microcalorimeters, and have measured the electron-capture spectrum of 163Ho. Finally, we present our work in these areas and discuss the measured spectrum and its comparison to current theory.« less

  3. Development of Holmium-163 electron-capture spectroscopy with transition-edge sensors

    SciTech Connect

    Croce, Mark Philip; Rabin, Michael W.; Mocko, Veronika; Kunde, Gerd Joachim; Birnbaum, Eva R.; Bond, E. M.; Engle, Jonathan Ward; Hoover, Andrew Scott; Nortier, Francois Meiring; Pollington, Anthony Douglas; Taylor, Wayne Allen; Weisse-Bernstein, Nina R.; Wolfsberg, Laura Evon; Hays-Wehle, James P.; Schmidt, Dan R.; Swetz, D. S.; Ullom, Joel N.; Barnhart, Todd E.; Nickles, Robert J.

    2016-08-01

    Calorimetric decay energy spectroscopy of electron-capture-decaying isotopes is a promising method to achieve the sensitivity required for electron neutrino mass measurement. The very low total nuclear decay energy (QEC < 3 keV) and short half-life (4570 years) of 163Ho make it attractive for high-precision electron-capture spectroscopy (ECS) near the kinematic endpoint, where the neutrino momentum goes to zero. In the ECS approach, an electron-capture-decaying isotope is embedded inside a microcalorimeter designed to capture and measure the energy of all the decay radiation except that of the escaping neutrino. We have developed a complete process for proton irradiation-based isotope production, isolation, and purification of 163Ho. We have developed transition-edge sensors for this measurement and methods for incorporating 163Ho into high-resolution microcalorimeters, and have measured the electron-capture spectrum of 163Ho. Finally, we present our work in these areas and discuss the measured spectrum and its comparison to current theory.

  4. Electron capture in collisions of Al2+ ions with He atoms at intermediate energies

    NASA Astrophysics Data System (ADS)

    Watanabe, A.; Sato, H.; Gu, J. P.; Hirsch, G.; Buenker, R. J.; Kimura, M.

    2001-09-01

    Electron capture resulting from collisions of Al2+ ions with He atoms from 0.15 to 1000 keV/u is investigated using a molecular-orbital representation within a semiclassical frame. Molecular electronic states and corresponding couplings are determined by the ALCHEMY program. Sixteen molecular states all connecting to single-electron-capture processes are included, and hence radial and rotational couplings among these channels are fully considered. The trajectory effect arising from the straight-line, Coulomb, and ground-state potential trajectories for electron-capture and excitation processes is carefully assessed. The electron-capture cross section by ground-state Al2+(2S) ions slowly increases before it reaches a maximum of 1.3×10-16 cm2 at 100 keV/u. Those for metastable Al2+(2P) ions sharply increase with increasing energy, and reach a peak at 1 keV/u with a value of 1.5×10-16 cm2. The earlier experimental data are found to be larger by an order of magnitude although their energy dependence is in good accord with the present result. Excitation cross sections for both the ground and metastable states are found to be much larger by a factor of 2-3 than corresponding capture cross sections above 1 keV/u although they become comparable below this energy.

  5. Development of Holmium-163 Electron-Capture Spectroscopy with Transition-Edge Sensors

    NASA Astrophysics Data System (ADS)

    Croce, M. P.; Rabin, M. W.; Mocko, V.; Kunde, G. J.; Birnbaum, E. R.; Bond, E. M.; Engle, J. W.; Hoover, A. S.; Nortier, F. M.; Pollington, A. D.; Taylor, W. A.; Weisse-Bernstein, N. R.; Wolfsberg, L. E.; Hays-Wehle, J. P.; Schmidt, D. R.; Swetz, D. S.; Ullom, J. N.; Barnhart, T. E.; Nickles, R. J.

    2016-08-01

    Calorimetric decay energy spectroscopy of electron-capture-decaying isotopes is a promising method to achieve the sensitivity required for electron neutrino mass measurement. The very low total nuclear decay energy (Q_EC < 3 keV) and short half-life (4570 years) of ^{163}Ho make it attractive for high-precision electron-capture spectroscopy (ECS) near the kinematic endpoint, where the neutrino momentum goes to zero. In the ECS approach, an electron-capture-decaying isotope is embedded inside a microcalorimeter designed to capture and measure the energy of all the decay radiation except that of the escaping neutrino. We have developed a complete process for proton irradiation-based isotope production, isolation, and purification of ^{163}Ho. We have developed transition-edge sensors for this measurement and methods for incorporating ^{163}Ho into high-resolution microcalorimeters, and have measured the electron-capture spectrum of ^{163}Ho. We present our work in these areas and discuss the measured spectrum and its comparison to current theory.

  6. Electron capture of dopants in two-photonic ionization in a poly(methyl methacrylate) solid

    SciTech Connect

    Tsuchida, Akira; Sakai, Wataru; Nakano, Mitsuru; Yamamoto, Masahide

    1992-10-29

    Behavior of the electron produced by two-photonic excitation of an aromatic donor in a poly(methyl methacrylate) solid was studied by the addition of the electron scavengers to the system. According to the Perrin type analysis for the two-photonically ejected electron, the capture radii (R{sub c}) of the scavengers examined were estimated to be from 8 to 40 {Angstrom}. For the two-photonically ejected electrons, R{sub c} is a capture radius for thermalized electrons. In this case the parent electron donor is not necessarily within this radius. On the other hand, for the fluorescence quenching, the distance between the donor and acceptor is within the static quenching radius (R{sub q}) of the donor. 13 refs., 4 figs., 2 tabs.

  7. Evaluation and optimization of electron capture dissociation efficiency in fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    McFarland, Melinda A; Chalmers, Michael J; Quinn, John P; Hendrickson, Christopher L; Marshall, Alan G

    2005-07-01

    Electron capture dissociation (ECD) efficiency has typically been lower than for other dissociation techniques. Here we characterize experimental factors that limit ECD and seek to improve its efficiency. Efficiency of precursor to product ion conversion was measured for a range of peptide (approximately 15% efficiency) and protein (approximately 33% efficiency) ions of differing sizes and charge states. Conversion of precursor ions to products depends on electron irradiation period and maximizes at approximately 5-30 ms. The optimal irradiation period scales inversely with charge state. We demonstrate that reflection of electrons through the ICR cell is more efficient and robust than a single pass, because electrons can cool to the optimal energy for capture, which allows for a wide range of initial electron energy. Further, efficient ECD with reflected electrons requires only a short (approximately 500 micros) irradiation period followed by an appropriate delay for cooling and interaction. Reflection of the electron beam results in electrons trapped in or near the ICR cell and thus requires a brief (approximately 50 micros) purge for successful mass spectral acquisition. Further electron irradiation of refractory precursor ions did not result in further dissociation. Possibly the ion cloud and electron beam are misaligned radially, or the electron beam diameter may be smaller than that of the ion cloud such that remaining precursor ions do not overlap with the electron beam. Several ion manipulation techniques and use of a large, movable dispenser cathode reduce the possibility that misalignment of the ion and electron beams limits ECD efficiency.

  8. Resonant Enhancement of Neutrinoless Double-Electron Capture in Gd152

    NASA Astrophysics Data System (ADS)

    Eliseev, S.; Roux, C.; Blaum, K.; Block, M.; Droese, C.; Herfurth, F.; Kluge, H.-J.; Krivoruchenko, M. I.; Novikov, Yu. N.; Minaya Ramirez, E.; Schweikhard, L.; Shabaev, V. M.; Šimkovic, F.; Tupitsyn, I. I.; Zuber, K.; Zubova, N. A.

    2011-02-01

    In the search for the nuclide with the largest probability for neutrinoless double-electron capture, we have determined the Qγγ value between the ground states of Gd152 and Sm152 by Penning-trap mass-ratio measurements. The new Qγγ value of 55.70(18) keV results in a half-life of 1026yr for a 1 eV neutrino mass. With this smallest half-life among known 0νγγ transitions, Gd152 is a promising candidate for the search for neutrinoless double-electron capture.

  9. Electronic data capture platform for clinical research based on mobile phones and near field communication technology.

    PubMed

    Morak, Jürgen; Schwetz, Verena; Hayn, Dieter; Fruhwald, Friedrich; Schreier, Gunter

    2008-01-01

    Electronic data capture systems support data acquisition for clinical research and enable the evaluation of new investigational medical devices. In case of evaluating a device the most challenging part is the user interface i.e. the solution how to acquire the data within a clinical setting and to synchronize them with a web-based data centre. The aim of this paper is to describe the development of an electronic data capture system with a mobile data input solution based on mobile phones and Near Field Communication technology. This system was evaluated within a real clinical setting and demonstrated high usability, security and reliability.

  10. Electron capture in Ar++H2 collisions in the keV energy regime

    NASA Astrophysics Data System (ADS)

    Kimura, M.; Chapman, S.; Lane, N. F.

    1986-03-01

    Electron capture in Ar+( 2P)+H2(X 1Σg) collisions in the keV energy regime has been studied theoretically. The molecular-orbital expansion method was used within a semiclassical formalism and an electron translation factor correction was incorporated to the first order in the magnitude of the relative velocity V. The molecular wave function and eigenenergy were obtained using the diatoms-in-molecules (DIM) method. We have examined the effect of the orientation of the target H2 molecule on the electron-capture mechanism within the sudden adiabatic approximation. Since π symmetry arising from the p orbital of the Ar+ ion is involved in this system, a strong influence on the probability of the molecular orientation was found in all energies studied. As the collision energy increases, the Π-symmetry state in the initial channel becomes more important through the rotational coupling to the electron-capture mechanism, while at lower energies the Σ-symmetry state in the initial channel is the dominant source for the electron capture through strong radial coupling. Agreement of the present theory with measurements is good, but marked disagreement is seen with the atomic-orbital calculation.

  11. Radiative double electron capture in collisions of fully-stripped fluorine ions with thin carbon foils

    NASA Astrophysics Data System (ADS)

    Elkafrawy, Tamer Mohammad Samy

    Radiative double electron capture (RDEC) is a one-step process in ion-atom collisions occurring when two target electrons are captured to a bound state of the projectile simultaneously with the emission of a single photon. The emitted photon has approximately double the energy of the photon emitted due to radiative electron capture (REC), which occurs when a target electron is captured to a projectile bound state with simultaneous emission of a photon. REC and RDEC can be treated as time-reversed photoionization (PI) and double photoionization (DPI), respectively, if loosely-bound target electrons are captured. This concept can be formulated with the principle of detailed balance, in which the processes of our interest can be described in terms of their time-reversed ones. Fully-stripped ions were used as projectiles in the performed RDEC experiments, providing a recipient system free of electron-related Coulomb fields. This allows the target electrons to be transferred without interaction with any of the projectile electrons, enabling accurate investigation of the electron-electron interaction in the vicinity of electromagnetic field. In this dissertation, RDEC was investigated during the collision of fully-stripped fluorine ions with a thin carbon foil and the results are compared with the recent experimental and theoretical studies. In the current work, x rays associated with projectile charge-changing by single and double electron capture and no charge change by F9+ ions were observed and compared with recent work for O8+ ions and with theory. Both the F 9+ and O8+ ions had energies in the ˜MeV/u range. REC, in turn, was investigated as a means to compare with the theoretical predictions of the RDEC/REC cross section ratio. The most significant background processes including various mechanisms of x-ray emission that may interfere with the energy region of interest are addressed in detail. This enables isolation of the contributions of REC and RDEC from the

  12. 2013 R&D 100 Award: Movie-mode electron microscope captures nanoscale

    SciTech Connect

    Lagrange, Thomas; Reed, Bryan

    2014-04-03

    A new instrument developed by LLNL scientists and engineers, the Movie Mode Dynamic Transmission Electron Microscope (MM-DTEM), captures billionth-of-a-meter-scale images with frame rates more than 100,000 times faster than those of conventional techniques. The work was done in collaboration with a Pleasanton-based company, Integrated Dynamic Electron Solutions (IDES) Inc. Using this revolutionary imaging technique, a range of fundamental and technologically important material and biological processes can be captured in action, in complete billionth-of-a-meter detail, for the first time. The primary application of MM-DTEM is the direct observation of fast processes, including microstructural changes, phase transformations and chemical reactions, that shape real-world performance of nanostructured materials and potentially biological entities. The instrument could prove especially valuable in the direct observation of macromolecular interactions, such as protein-protein binding and host-pathogen interactions. While an earlier version of the technology, Single Shot-DTEM, could capture a single snapshot of a rapid process, MM-DTEM captures a multiframe movie that reveals complex sequences of events in detail. It is the only existing technology that can capture multiple electron microscopy images in the span of a single microsecond.

  13. 2013 R&D 100 Award: Movie-mode electron microscope captures nanoscale

    ScienceCinema

    Lagrange, Thomas; Reed, Bryan

    2016-07-12

    A new instrument developed by LLNL scientists and engineers, the Movie Mode Dynamic Transmission Electron Microscope (MM-DTEM), captures billionth-of-a-meter-scale images with frame rates more than 100,000 times faster than those of conventional techniques. The work was done in collaboration with a Pleasanton-based company, Integrated Dynamic Electron Solutions (IDES) Inc. Using this revolutionary imaging technique, a range of fundamental and technologically important material and biological processes can be captured in action, in complete billionth-of-a-meter detail, for the first time. The primary application of MM-DTEM is the direct observation of fast processes, including microstructural changes, phase transformations and chemical reactions, that shape real-world performance of nanostructured materials and potentially biological entities. The instrument could prove especially valuable in the direct observation of macromolecular interactions, such as protein-protein binding and host-pathogen interactions. While an earlier version of the technology, Single Shot-DTEM, could capture a single snapshot of a rapid process, MM-DTEM captures a multiframe movie that reveals complex sequences of events in detail. It is the only existing technology that can capture multiple electron microscopy images in the span of a single microsecond.

  14. The determination of cyclohexylamine in aqueous solutions of sodium cyclamate by electron-capture gas chromatography.

    NASA Technical Reports Server (NTRS)

    Solomon, M. D.; Pereira, W. E.; Duffield, A. M.

    1971-01-01

    A sensitive primary amine assay, capable of detecting 10 to the minus 11th g and utilizing the determination of the amine N-2,4-dinitrophenyl derivative by electron-capture gas chromatography is described. The method is exemplified by the determination of cyclohexylamine in sodium cyclamate.

  15. Transition operators entering neutrinoless double electron capture to excited nuclear states

    NASA Astrophysics Data System (ADS)

    Vergados, J. D.

    2011-10-01

    We construct the effective transition operators relevant for neutrinoless double electron capture leading to final nuclear states different than 0+. From the structure of these operators we see that if such a process is observed experimentally, it will be very helpful in singling out the very important light neutrino mass contribution from the other lepton violating mechanisms.

  16. 77 FR 4059 - Certain Electronic Devices for Capturing and Transmitting Images, and Components Thereof; Receipt...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-26

    ... Images, and Components Thereof, DN 2869; the Commission is soliciting comments on any public interest... COMMISSION Certain Electronic Devices for Capturing and Transmitting Images, and Components Thereof; Receipt of Complaint; Solicitation of Comments Relating to the Public Interest AGENCY: U.S....

  17. Testing the electron-capture supernova scenario using universal relations between neutron star properties

    NASA Astrophysics Data System (ADS)

    Newton, William

    2017-01-01

    8-10 solar mass stars may end their lives in electron-capture supernovae (ECSNe), in which ONeMg cores are destabilized by electron captures onto Neon and Magnesium. Strong circumstantial evidence exists that the Crab pulsar and PSR J0737-3039b were formed in ECSNe. Evidence for the existence of the ECSN mechanism has important implications for the rate of production of Be/X-ray binaries and the rate of binary neutron star mergers.I will discuss how supernova modeling suggests that neutron stars formed via the electron-capture mechanism have a specific gravitational binding energy. Recently, universal relations between neutron star properties including their binding energy, moment of inertia, quadrupole moments and tidal polarizability have been carefully examined. I will show how these relations, coupled with measurements of the post-Newtonian parameters of the PSR J0737-3039 system and of the acceleration of the Crab supernova remnant, can provide evidence for or against the electron-capture supernova formation scenario.

  18. Accelerator mass spectrometry of 63Ni at the Munich Tandem Laboratory for estimating fast neutron fluences from the Hiroshima atomic bomb.

    PubMed

    Rühm, W; Knie, K; Rugel, G; Marchetti, A A; Faestermann, T; Wallner, C; McAninch, J E; Straume, T; Korschinek, G

    2000-10-01

    After the release of the present dosimetry system DS86 in 1987, measurements have shown that DS86 may substantially underestimate thermal neutron fluences at large distances (>1,000 m) from the hypocenter in Hiroshima. This discrepancy casts doubts on the DS86 neutron source term and, consequently, the survivors' estimated neutron doses. However, the doses were caused mainly by fast neutrons. To determine retrospectively fast neutron fluences in Hiroshima, the reaction 63Cu(n, p)63Ni can be used, if adequate copper samples can be found. Measuring 63Ni (half life 100 y) in Hiroshima samples requires a very sensitive technique, such as accelerator mass spectrometry (AMS), because of the relatively small amounts of 63Ni expected (approximately 10(5)-10(6) atoms per gram of copper). Experiments performed at Lawrence Livermore National Laboratory have demonstrated in 1996 that AMS can be used to measure 63Ni in Hiroshima copper samples. Subsequently, a collaboration was established with the Technical University of Munich in view of its potential to perform more sensitive measurements of 63Ni than the Livermore facility and in the interest of interlaboratory validation. This paper presents the progress made at the Munich facility in the measurement of 63Ni by AMS. The Munich accelerator mass spectrometry facility is a combination of a high energy tandem accelerator and a detection system featuring a gas-filled magnet. It is designed for high sensitivity measurements of long-lived radioisotopes. Optimization of the ion source setup has further improved the sensitivity for 63Ni by reducing the background level of the 63Cu isobar interference by about two orders of magnitude. Current background levels correspond to a ratio of 63Ni/Ni<2x10(-14) and suggest that, with adequate copper samples, the assessment of fast neutron fluences in Hiroshima and Nagasaki is possible for ground distances of up to 1500 m, and--under favorable conditions--even beyond. To demonstrate this

  19. Formation and decay of C - 60 following free electron capture by C60

    NASA Astrophysics Data System (ADS)

    Matejčik, Štefan; Märk, Tilmann D.; Španěl, Patrik; Smith, David; Jaffke, Thomas; Illenberger, Eugen

    1995-02-01

    The results of a detailed crossed electron/molecular beam study of electron attachment to C60 molecules and electron detachment from C-60 over the range of electron energies from near zero to about 15 eV are described. It is shown by comparing the experimental data for the attachment cross sections (normalized to the absolute thermal cross sections determined using the flowing afterglow/Langmuir probe apparatus) with quantum calculations that attachment occurs at low energies in the p-wave channel, and in the d- and f-wave channels (and probably higher-order partial waves) at the higher electron energies. At electron energies above 7 eV, thermal detachment of electrons from the hot C-60 negative ions is seen to occur, and the unimolecular rate coefficients for detachment, kd, have been determined as a function of the energy of the attaching electron. Hence, by relating kd to the derived temperature of the hot C-60 ions, the electron detachment energy, Ed, has been determined as 2.6 eV, which is close to the electron affinity of C60 as measured by photodetachment from cold C-60 ions. Additionally, by combining the measured attachment rate coefficients, ka, from the previous flowing afterglow/Langmuir probe study with the kd data determined in this study, equilibrium constants for the detachment/attachment reactions have been obtained which are reconciled with those calculated using total partition functions. An important conclusion to be drawn from all these studies is that C60 very efficiently captures electrons over the wide electron energy range from about 0.2 eV to around 15 eV and retains them if the energy released in the electron capture process can be removed before thermal detachment can occur.

  20. A mobile and asynchronous electronic data capture system for epidemiologic studies.

    PubMed

    Meyer, Jens; Fredrich, Daniel; Piegsa, Jens; Habes, Mohamad; van den Berg, Neeltje; Hoffmann, Wolfgang

    2013-06-01

    A Central Data Management (CDM) system based on electronic data capture (EDC) software and study specific databases is an essential component for assessment and management of large data volumes in epidemiologic studies. Conventional CDM systems using web applications for data capture depend on permanent access to a network. However, in many study settings permanent network access cannot be guaranteed, e.g. when participants/patients are visited in their homes. In such cases a different concept for data capture is needed. The utilized EDC software must be able to ensure data capture as stand-alone instance and to synchronize captured data with the server at a later point in time. This article describes the design of the mobile information capture (MInCa) system an EDC software meeting these requirements. In particular, we focus on client and server design, data synchronization, and data privacy as well as data security measures. The MInCa software has already proven its efficiency in epidemiologic studies revealing strengths and weaknesses concerning both concept and practical application which will be addressed in this article.

  1. Single and double electron capture in p-He and α-He collisions

    NASA Astrophysics Data System (ADS)

    Samaddar, S.; Halder, S.; Mondal, A.; Mandal, C. R.; Purkait, M.; Das, T. K.

    2017-03-01

    The differential and total cross sections for both single and double electron capture in collisions of {{{H}}}+ and He2+ with ground state helium atom have been studied by means of the four-body model of target continuum distorted wave (TCDW-4B) approximation in the energy range from 30 to 1000 keV amu–1. In this model, distortion in the final channel related to the Coulomb continuum states of the active electron(s) in the field of residual target ion are included. The calculations are based on the independent electron model. The present computed results are compared with the available experimental and other theoretical results. Total cross sections are found to be in good agreement with the measurements. We have also analysed differential cross sections (DCS) for both single and double electron capture in the collision of proton and α-particles with helium atoms at different projectile energies. The present DCS data exhibits the typical steeply decreasing dependence on the projectile scattering angles, but neither oscillating structures characteristic of interference effects nor peaks reminiscent of the Thomas peak are observed at different projectile energies. The obtained results for the DCS into the ground state are compared with the experimental data and overall a satisfactory agreement has been found. Finally we have also studied the variation of double to single capture differential cross-section ratios with projectile scattering angles at different impact energies.

  2. Double-electron capture by highly-ionized atoms isolated at very low energy

    NASA Astrophysics Data System (ADS)

    Fogwell Hoogerheide, Shannon; Dreiling, Joan M.; Sahiner, Arda; Tan, Joseph N.

    2016-05-01

    Charge exchange with background gases, also known as electron capture processes, is important in the study of comets, controlled fusion energy, anti-matter atoms, and proposed one-electron ions in Rydberg states. However, there are few experiments in the very low energy regime that could be useful for further theoretical development. At NIST, highly-charged ions extracted from an electron-beam ion trap can be isolated with energy < 10 eV in a compact Penning trap. By controlling the background gas pressure and composition, the charge exchange rates can be studied. Fully stripped neon or other ions are held in the trap for varying lengths of time and allowed to interact with different background gases at multiple pressures. The ions are then pulsed to a time-of-flight detector to count the population of each charge state. Analysis using a system of rate equations yields information about the ion cloud expansion and single-electron capture rates. A substantial amount of double-electron capture is also observed. We present the relative rates and discuss the error budget. SFH and JMD were funded by National Research Council Research Associateship Awards during some of this work.

  3. Proton emission following multiple electron capture in slow N{sup 7+}+HCl collisions

    SciTech Connect

    Fremont, F.; Martina, D.; Kamalou, O.; Sobocinski, P.; Chesnel, J.-Y.; McNab, I.R.; Bennett, F.R.

    2005-04-01

    Collisions between 98-keV N{sup 7+} ions and a HCl target have been investigated experimentally. The kinetic-energy distribution of fragment H{sup +} ions originating from multiple electron capture was detected at angles in the range 20 deg. -160 deg. with respect to the incident beam direction. Proton energies as large as 100 eV were observed, and calculations made in the simple Coulomb explosion model suggest that up to seven target electrons may be involved during the collision. Using the Landau-Zener model, we show that the N{sup 7+} projectile mainly captures outer-shell electrons from HCl. From the experimental data we derived multiple-capture cross sections which we compared with results from a model calculation made using the classical over-barrier model and also with a semiempirical scaling law. For the specific case of double capture, several structures appeared, which were assigned using ab initio calculations to states of HCl{sup 2+}.

  4. Calculations on Electron Capture in Low Energy Ion-Molecule Collisions

    SciTech Connect

    Stancil, P.C.; Zygelman, B.; Kirby, K.

    1997-12-31

    Recent progress on the application of a quantal, molecular-orbital, close-coupling approach to the calculation of electron capture in collisions of multiply charged ions with molecules is discussed. Preliminary results for single electron capture by N{sup 2+} with H{sub 2} are presented. Electron capture by multiply charged ions colliding with H{sub 2} is an important process in laboratory and astrophysical plasmas. It provides a recombination mechanism for multiply charged ions in x-ray ionized astronomical environments which may have sparse electron and atomic hydrogen abundances. In the divertor region of a tokamak fusion device, charge exchange of impurity ions with H{sub 2} plays a role in the ionization balance and the production of radiative energy loss leading to cooling, X-ray and ultraviolet auroral emission from Jupiter is believed to be due to charge exchange of O and S ions with H{sub 2} in the Jovian atmosphere. Solar wind ions interacting with cometary molecules may have produced the x-rays observed from Comet Hyakutake. In order to model and understand the behavior of these environments, it is necessary to obtain total, electronic state-selective (ESS), and vibrational (or rotational) state-selective (VSS) capture cross sections for collision energies as low as 10 meV/amu to as high as 100 keV/amu in some instances. Fortunately, charge transfer with molecular targets has received considerable experimental attention. Numerous measurements have been made with flow tubes, ion traps, and ion beams. Flow tube and ion trap studies generally provide information on rate coefficients for temperatures between 800 K and 20,000 K. In this article, we report on the progress of our group in implementing a quantum-mechanical Molecular Orbital Close Coupling (MOCC) approach to the study of electron capture by multiply charged ions in collisions with molecules. We illustrate this with a preliminary investigation of Single Electron Capture (SEC) by N{sup 2+} with H

  5. 75 FR 8115 - In the Matter of Certain Electronic Devices Having Image Capture or Display Functionality and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-23

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION In the Matter of Certain Electronic Devices Having Image Capture or Display Functionality and... sale within the United States after importation of certain electronic devices having image capture...

  6. Electron capture dissociation in a branched radio-frequency ion trap.

    PubMed

    Baba, Takashi; Campbell, J Larry; Le Blanc, J C Yves; Hager, James W; Thomson, Bruce A

    2015-01-06

    We have developed a high-throughput electron capture dissociation (ECD) device coupled to a quadrupole time-of-flight mass spectrometer using novel branched radio frequency ion trap architecture. With this device, a low-energy electron beam can be injected orthogonally into the analytical ion beam with independent control of both the ion and electron beams. While ions and electrons can interact in a "flow-through" mode, we observed a large enhancement in ECD efficiency by introducing a short ion trapping period at the region of ion and electron beam intersection. This simultaneous trapping mode still provides up to five ECD spectra per second while operating in an information-dependent acquisition workflow. Coupled to liquid chromatography (LC), this LC-ECD workflow provides good sequence coverage for both trypsin and Lys C digests of bovine serum albumin, providing ECD spectra for doubly charged precursor ions with very good efficiency.

  7. Electron capture by the thiyl radical and disulfide bond: ligand effects on the reduction potential.

    PubMed

    Roos, Goedele; De Proft, Frank; Geerlings, Paul

    2013-04-15

    The effect of non-polar and polar ligands and of monovalent cations on the one-electron reduction potential of the thiyl radical and the disulfide bond was evaluated. The reduction potentials E° for the CH3S(.)-nL/CH3S(-)-nL and CH3SSCH3-L/CH3SSCH3(.-)-L redox couples were calculated at the B3LYP, M06-2X and MP2 levels of theory, with n=1, 2 and L=CH4, C2H4, H2O, CH3OH, NH3, CH3COOH, CH3CONH2, NH4(+), Na(+), K(+) and Li(+). Non-polar ligands decrease the E° value of the thiyl radical and disulfide bond, while neutral polar ligands favour electron uptake. Charged polar ligands and cations favour electron capture by the thiyl radical while disfavouring electron uptake by the disulfide bond. Thus, the same type of ligand can have a different effect on E° depending on the redox couple. Therefore, properties of an isolated ligand cannot uniquely determine E°. The ligand effects on E° are discussed in terms of the vertical electron affinity and reorganization energy, as well as molecular orbital theory. For a given redox couple, the ligand type influences the nature of the anion formed upon electron capture and the corresponding reorganization process towards the reduced geometry.

  8. Electron Capture Processes Following Collisions of He^2+ Ions with Molecular Targets

    NASA Astrophysics Data System (ADS)

    Abu-Haija, O.

    2005-05-01

    Energy-gain spectra, absolute state-selective and total cross sections have been measured for single-electron capture processes in collisions of He^2+ ions with O2, H2O, CO2, N2, and NH3 at impact energies between 100 eV and 1600 eV and scattering angles between 0^o and 6^o using the translational energy-gain spectroscopy (TES) technique. As apparent from the translational energy-gain measurements, single-electron capture (SEC) from O2 and H2O proceeds by both dissociative and non-dissociative channels, whereas for N2 and CO2 only dissociative SEC has been observed. However, for NH3 the non-dissociative SEC channel is found to be predominantly populated. Total cross sections have also been compared with available measurements and theoretical calculations based on Landua-Zener model and Demkov model.

  9. Simultaneous collision induced dissociation of the charge reduced parent ion during electron capture dissociation.

    PubMed

    Bushey, Jared M; Baba, Takashi; Glish, Gary L

    2009-08-01

    A method of performing collision induced dissociation (CID) on the charge-reduced parent ion as it is formed during electron capture dissociation (ECD), called ECD+CID, is described. In ECD+CID, the charge-reduced parent ion is selectively activated using resonant excitation and collisions with the helium bath gas inside a linear quadrupole ion trap ECD device (ECD(LIT)). It has been observed that ECD+CID can improve the sequence coverage for beta-endorphin over performing ECD alone (i.e., from 72 to 97%). Perhaps just as important, ECD+CID can be used to reduce the extent of multiple electron capture events observed when performing ECD in the ECD(LIT). Consequently, the abundance of mass-to-charge ratios corresponding to ECD product ions that contain neutralized protons is decreased, simplifying the interpretation of the product ion spectrum.

  10. State-selective electron capture in 30- and 100-keV He++He collisions

    NASA Astrophysics Data System (ADS)

    Guo, D. L.; Ma, X.; Zhang, R. T.; Zhang, S. F.; Zhu, X. L.; Feng, W. T.; Gao, Y.; Hai, B.; Zhang, M.; Wang, H. B.; Huang, Z. K.

    2017-01-01

    A combined experimental and theoretical study on single capture in 30- and 100-keV He+ on He collisions was performed. By using a reaction microscope, we obtained the state selective cross sections and the angular-differential cross sections. It was found that the experimental state-selective cross sections were in good agreement with the dynamic screening classical trajectory Monte Carlo calculation for 100-keV He+ incident. The comparisons with various versions of such calculations reveal the roles played by different electron-electron correlation effects. Moreover, a prominent oscillatory structure was observed in the angular-differential cross sections for both projectile energies. With the single capture probability distribution obtained from the classical trajectory Monte Carlo calculation, the oscillation structures can be well explained by atomic-size Fraunhofer-type diffraction.

  11. Electron emission from single-electron capture with simultaneous single-ionization reactions in 30-keV/u He{sup 2+}-on-argon collisions

    SciTech Connect

    Ma, X.; Zhang, S. F.; Zhu, X. L.; Feng, W. T.; Li, B.; Liu, H. P.; Zhang, R. T.; Guo, D. L.; Yan, S. C.; Zhang, P. J.; Wang, Q.; Li, C. Y.; Wang, J. G.

    2011-05-15

    Electron emission from the single-electron capture with simultaneous single ionization in 30 keV/u He{sup 2+} on argon was investigated using a reaction microscope, providing the electron energy spectra and momentum distributions. Intensive peaks for electrons with near-zero kinetic energies have been observed. It is demonstrated that mechanisms contributing to the electron emission include direct transfer ionization (DTI), double-electron capture with autoionization (DECA), and single-electron capture with autoionization (SECA) of target. Comparison of resonance energies shows that Ar{sup +} ions in SECA decay mainly through the 3s3p{sup 5}3d states by emitting Auger electrons, and He** in DECA decay through the 2l2l' states. The dependence of electron emission on the transverse momentum exchange has been studied. In the transfer ionization channel studied here, the DTI process dominates the electron emission, and no saddle point electron mechanism has been found.

  12. Electron emission from single-electron capture with simultaneous single-ionization reactions in 30-keV/u He2+-on-argon collisions

    NASA Astrophysics Data System (ADS)

    Ma, X.; Zhang, R. T.; Zhang, S. F.; Zhu, X. L.; Feng, W. T.; Guo, D. L.; Li, B.; Liu, H. P.; Li, C. Y.; Wang, J. G.; Yan, S. C.; Zhang, P. J.; Wang, Q.

    2011-05-01

    Electron emission from the single-electron capture with simultaneous single ionization in 30 keV/u He2+ on argon was investigated using a reaction microscope, providing the electron energy spectra and momentum distributions. Intensive peaks for electrons with near-zero kinetic energies have been observed. It is demonstrated that mechanisms contributing to the electron emission include direct transfer ionization (DTI), double-electron capture with autoionization (DECA), and single-electron capture with autoionization (SECA) of target. Comparison of resonance energies shows that Ar+ ions in SECA decay mainly through the 3s3p53d states by emitting Auger electrons, and He** in DECA decay through the 2l2l' states. The dependence of electron emission on the transverse momentum exchange has been studied. In the transfer ionization channel studied here, the DTI process dominates the electron emission, and no saddle point electron mechanism has been found.

  13. Search for double electron capture on 124Xe with the XMASS-I detector

    NASA Astrophysics Data System (ADS)

    Hiraide, Katsuki; XMASS Collaboration

    2016-05-01

    The XMASS project is a multi-purpose experiment using highly-purified liquid xenon scintillator located underground at the Kamioka Observatory in Japan. A search for two-neutrino double electron capture on 124Xe is performed using 165.9 days of data collected with the XMASS-I detector. No significant excess above background was observed and we set a lower limit on the half-life as 4.7 × 1021 years at 90% confidence level.

  14. Neutron-induced 63Ni in copper samples from Hiroshima and Nagasaki: a comprehensive presentation of results obtained at the Munich Maier-Leibnitz Laboratory.

    PubMed

    Rühm, W; Carroll, K L; Egbert, S D; Faestermann, T; Knie, K; Korschinek, G; Martinelli, R E; Marchetti, A A; McAninch, J E; Rugel, G; Straume, T; Wallner, A; Wallner, C; Fujita, S; Hasai, H; Hoshi, M; Shizuma, K

    2007-11-01

    Those inhabitants of Hiroshima and Nagasaki who were affected by the A-bomb explosions, were exposed to a mixed neutron and gamma radiation field. Few years later about 120,000 survivors of both cities were selected, and since then radiation-induced late effects such as leukemia and solid tumors are being investigated in this cohort. When the present study was initiated, the fast neutron fluences that caused the neutron doses of these survivors had never been determined experimentally. In principle, this would have been possible if radioisotopes produced by fast neutrons from the A-bomb explosions had been detected in samples from Hiroshima and Nagasaki at distances where the inhabitants survived. However, no suitable radioisotope had so far been identified. As a contribution to a large international effort to re-evaluate the A-bomb dosimetry, the concentration of the radionuclide (63)Ni (half-life 100.1 years) has been measured in copper samples from Hiroshima and Nagasaki. These measurements were mainly performed at the Maier-Leibnitz-Laboratory in Munich, Germany, by means of accelerator mass spectrometry. Because the (63)Ni had been produced in these samples by fast A-bomb neutrons via the reaction (63)Cu(n,p)(63)Ni, these measurements allow direct experimental validation of calculated neutron doses to the members of the LSS cohort, for the first time. The results of these efforts have already been published in a compact form. A more detailed discussion of the methodical aspects of these measurements and their results are given in the present paper. Eight copper samples that had been significantly exposed to fast neutrons from the Hiroshima A-bomb explosion were investigated. In general, measured (63)Ni concentrations decreased in these samples with increasing distance to the hypocenter, from 4 x 10(6 ) (63)Ni nuclei per gram copper at 391 m, to about 1 x 10(5 ) (63)Ni nuclei per gram copper at about 1,400 m. Additional measurements performed on three large

  15. β+ Gamow-Teller transition strengths from 46Ti and stellar electron-capture rates.

    PubMed

    Noji, S; Zegers, R G T; Austin, Sam M; Baugher, T; Bazin, D; Brown, B A; Campbell, C M; Cole, A L; Doster, H J; Gade, A; Guess, C J; Gupta, S; Hitt, G W; Langer, C; Lipschutz, S; Lunderberg, E; Meharchand, R; Meisel, Z; Perdikakis, G; Pereira, J; Recchia, F; Schatz, H; Scott, M; Stroberg, S R; Sullivan, C; Valdez, L; Walz, C; Weisshaar, D; Williams, S J; Wimmer, K

    2014-06-27

    The Gamow-Teller strength in the β(+) direction to (46)Sc was extracted via the (46)Ti(t,(3)He + γ) reaction at 115  MeV/u. The γ-ray coincidences served to precisely measure the very weak Gamow-Teller transition to a final state at 991 keV. Although this transition is weak, it is crucial for accurately estimating electron-capture rates in astrophysical scenarios with relatively low stellar densities and temperatures, such as presupernova stellar evolution. Shell-model calculations with different effective interactions in the pf shell-model space do not reproduce the experimental Gamow-Teller strengths, which is likely due to sd-shell admixtures. Calculations in the quasiparticle random phase approximation that are often used in astrophysical simulations also fail to reproduce the experimental Gamow-Teller strength distribution, leading to strongly overestimated electron-capture rates. Because reliable theoretical predictions of Gamow-Teller strengths are important for providing astrophysical electron-capture reaction rates for a broad set of nuclei in the lower pf shell, we conclude that further theoretical improvements are required to match astrophysical needs.

  16. Theoretical investigation of the electron capture and loss processes in the collisions of He2+ + Ne.

    PubMed

    Hong, Xuhai; Wang, Feng; Jiao, Yalong; Su, Wenyong; Wang, Jianguo; Gou, Bingcong

    2013-08-28

    Based on the time-dependent density functional theory, a method is developed to study ion-atom collision dynamics, which self-consistently couples the quantum mechanical description of electron dynamics with the classical treatment of the ion motion. Employing real-time and real-space method, the coordinate space translation technique is introduced to allow one to focus on the region of target or projectile depending on the actual concerned process. The benchmark calculations are performed for the collisions of He(2+) + Ne, and the time evolution of electron density distribution is monitored, which provides interesting details of the interaction dynamics between the electrons and ion cores. The cross sections of single and many electron capture and loss have been calculated in the energy range of 1-1000 keV/amu, and the results show a good agreement with the available experiments over a wide range of impact energies.

  17. Proton-induced single electron capture on DNA/RNA bases.

    PubMed

    Champion, C; Weck, P F; Lekadir, H; Galassi, M E; Fojón, O A; Abufager, P; Rivarola, R D; Hanssen, J

    2012-05-21

    In this work, we report total cross sections for the single electron capture process induced on DNA/RNA bases by high-energy protons. The calculations are performed within both the continuum distorted wave and the continuum distorted wave-eikonal initial state approximations. The biological targets are described within the framework of self-consistent methods based on the complete neglect of differential overlap model whose accuracy has first been checked for simpler bio-molecules such as water vapour. Furthermore, the multi-electronic problem investigated here is reduced to a mono-electronic one using a version of the independent electron approximation. Finally, the obtained theoretical predictions are confronted with the scarcely available experimental results.

  18. Synthesis and electrochemical performance of high-capacity 0.34Li{sub 2}MnO{sub 3}·0.66LiMn{sub 0.63}Ni{sub 0.24}Co{sub 0.13}O{sub 2} cathode materials using a Couette–Taylor reactor

    SciTech Connect

    Choi, Mansoo; Kim, Hyun-Soo; Kim, Jik-Soo; Park, Suk-Joon; Lee, Young Moo; Jin, Bong-Soo

    2014-10-15

    Highlights: • The cathode material synthesized by co-precipitation using a Couette–Taylor reactor. • The first and second discharge capacities were measured to be 311 and 307 mA h g{sup −1}. • The material has an excellent rate capability. - Abstract: The 0.34Li{sub 2}MnO{sub 3}·0.66LiMn{sub 0.63}Ni{sub 0.24}Co{sub 0.13}O{sub 2} cathode material for the Li-ion battery is synthesized by co-precipitation using a Couette–Taylor reactor. Particle size analysis (PSA) and a field emission-scanning electron microscopy (FE-SEM) images show that the obtained precursor and cathode material exhibit a narrow particle size distribution and spherical shape. The structure and composition of the 0.34Li{sub 2}MnO{sub 3}·0.66LiMn{sub 0.63}Ni{sub 0.24}Co{sub 0.13}O{sub 2} are confirmed by X-ray diffraction (XRD) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The first and second discharge capacities of 0.34Li{sub 2}MnO{sub 3}·0.66LiMn{sub 0.63}Ni{sub 0.24}Co{sub 0.13}O{sub 2} are measured to be 311 and 307 mA h g{sup −1}, respectively. The material also has an excellent rate capability (250 and 180 mA h g{sup −1} at 1 C and 5 C, respectively). In the rate capability test at 60 °C, 0.34Li{sub 2}MnO{sub 3}·0.66LiMn{sub 0.63}Ni{sub 0.24}Co{sub 0.13}O{sub 2} has a higher capacity of over 210 mA h g{sup −1} in the range 0.1–10 C. In the cyclic performance test, the capacity retention at high temperature is over 85% after 50 cycles, which is similar to that at room temperature. The 0.34Li{sub 2}MnO{sub 3}·0.66LiMn{sub 0.63}Ni{sub 0.24}Co{sub 0.13}O{sub 2} is therefore a high-capacity material with potential for use as an electrode in Li-ion batteries.

  19. Identification and measurement of chlorinated organic pesticides in water by electron-capture gas chromatography

    USGS Publications Warehouse

    Lamar, William L.; Goerlitz, Donald F.; Law, LeRoy M.

    1965-01-01

    Pesticides, in minute quantities, may affect the regimen of streams, and because they may concentrate in sediments, aquatic organisms, and edible aquatic foods, their detection and their measurement in the parts-per-trillion range are considered essential. In 1964 the U.S. Geological Survey at Menlo Park, Calif., began research on methods for monitoring pesticides in water. Two systems were selected--electron-capture gas chromatography and microcoulometric-titration gas chromatography. Studies on these systems are now in progress. This report provides current information on the development and application of an electron-capture gas chromatographic procedure. This method is a convenient and extremely sensitive procedure for the detection and measurement of organic pesticides having high electron affinities, notably the chlorinated organic pesticides. The electron-affinity detector is extremely sensitive to these substances but it is not as sensitive to many other compounds. By this method, the chlorinated organic pesticide may be determined on a sample of convenient size in concentrations as low as the parts-per-trillion range. To insure greater accuracy in the identifications, the pesticides reported were separated and identified by their retention times on two different types of gas chromatographic columns.

  20. Structural studies on protein O-fucosylation by electron capture dissociation

    NASA Astrophysics Data System (ADS)

    Mormann, Michael; Macek, Boris; de Peredo, Anne Gonzalez; Hofsteenge, Jan; Peter-Katalinic, Jasna

    2004-05-01

    The low energy dissociation technique electron capture dissociation has been applied to a series of thrombospondin and properdin derived O-fucosylated glycopeptides. Followed by capture of an electron by multiply protonated precursor ions [M+nH]n+ reduced odd electron radical cations [M+nH](n-1)[radical sign]+ were generated. The latter mainly fragment by cleavage of the N---C[alpha] bonds of the peptide chain without loss of the labile sugar moiety allowing an unambiguous assignment of the glycosylation site. Apart from peptide backbone cleavages, side chain losses of aminocarbonylmethyl and aminocarbonylmethylthiyl radicals from carboxyamidomethylated cysteins are observed. The N---C[alpha] bond cleavage is greatly reduced on both sides of alkylated Cys. However, fragment ions that are formed by secondary fragmentations of z-type radical cations containing N-terminal cystein give rise to even electron z---[radical sign]SCH2CONH2 ions. The potential of the high mass accuracy for the identification of the protein modification topology has been fully explored.

  1. Electron Beam Analysis of Micrometeoroids Captured in Aerogel as Stardust Analogues

    NASA Technical Reports Server (NTRS)

    Graham, G. A.; Sheffield-Parker, J.; Bradley, P.; Kearsley, A. T.; Dai, Z. R.; Mayo, S. C.; Teslich, N.; Snead, C.; Westphal, A. J.; Ishii, H.

    2005-01-01

    In January 2004, NASA s Stardust spacecraft passed through the tail of Comet 81P/Wild-2. The on-board dust flux monitor instrument indicated that numerous micro- and nano-meter sized cometary dust particles were captured by the dedicated silica aerogel capture cell. The collected cometary particles will be returned to Earth in January 2006. Current Stardust analogues are: (i) Light-gas-gun accelerated individual mineral grains and carbonaceous meteoritic material in aerogels at the Stardust encounter velocity ca.approximately 6 kilometers per second. (ii) Aerogels exposed in low-Earth orbit (LEO) containing preserved cosmic dust grains. Studies of these impacts offer insight into the potential state of the captured cometary dust by Stardust and the suitability of various analytical techniques. A number of papers have discussed the application of sophisticated synchrotron analytical techniques to analyze Stardust particles. Yet much of the understanding gained on the composition and mineralogy of interplanetary dust particles (IDPs) has come from electron microscopy studies. Here we discuss the application of scanning electron microscopy (SEM) for Stardust during the preliminary phase of post-return investigations.

  2. High-energy two-electron capture with emission of a single photon

    SciTech Connect

    Drukarev, E. G.; Mikhailov, A. I.; Mikhailov, I. A.; Scheid, W.

    2007-12-15

    We investigate the two-electron capture with emission of a single photon to the ground state in the Coulomb field of a heavy nucleus in its collision with a light atom. Describing electron-electron interactions in the bound state perturbatively, we obtained an analytical formula for the high-energy limit of the cross section. In combination with previous results obtained in the same approach we calculated the cross section in a broad interval of energies of the collision. We show that the amplitude of the process at high energy depends on the behavior of the bound state wave function near the triple coalescence point. We analyze the properties of the approximate wave functions which are necessary for the description of the high-energy limit.

  3. Quantum fluctuations and coherence in high-precision single-electron capture.

    PubMed

    Kashcheyevs, Vyacheslavs; Timoshenko, Janis

    2012-11-21

    The phase of a single quantum state is undefined unless the history of its creation provides a reference point. Thus, quantum interference may seem hardly relevant for the design of deterministic single-electron sources which strive to isolate individual charge carriers quickly and completely. We provide a counterexample by analyzing the nonadiabatic separation of a localized quantum state from a Fermi sea due to a closing tunnel barrier. We identify the relevant energy scales and suggest ways to separate the contributions of quantum nonadiabatic excitation and back tunneling to the rare noncapture events. In the optimal regime of balanced decay and nonadiabaticity, our simple electron trap turns into a single-lead Landau-Zener back tunneling interferometer, revealing the dynamical phase accumulated between the particle capture and leakage. The predicted "quantum beats in back tunneling" may turn the error of a single-electron source into a valuable signal revealing essentially nonadiabatic energy scales of a dynamic quantum dot.

  4. Recoil Momentum Spectroscopy Study of Electron Capture from He by 10 MeV Hydrogenlike Fluorine

    NASA Astrophysics Data System (ADS)

    Saleh, L.; Winecki, S.; Stöckli, M.; Cocke, C. L.; Richard, P.; Ullrich, J.; Moshammer, R.

    1996-05-01

    We have used recoil momentum spectroscopy (COLTRIMS (J. Ullrich, et al., Comm. At. Mol. Phys. \\underline30), 285 (1994).) to determine final state momentum distributions in the single electron capture from He by 10 MeV F^8+ ions. A momentum resolution below 0.15 a.u. was obtained. The longitidunal momentum resolution is sufficient to allow the separation of final state populations of the L, M and higher states, and to identify excitation of the residual He^+ ion. This probability of this excitation is large in the capture process. Transverse momentum distributions were used to extract transverse cross sections (angular distributions) for different final states. Comparison of the data to theoretical expectations will be presented.

  5. N2O analysis in the atmosphere via electron capture-gas chromatography

    NASA Technical Reports Server (NTRS)

    Rasmussen, R. A.; Krasnec, J.; Pierotti, D.

    1976-01-01

    The potential of commercially available pulse-modulated electron capture detector (ECD)-equipped gas chromatographs for direct measurement of ambient levels of N2O is assessed. Since the sensitivity of ECD to N2O is directly proportional to the detector operating temperature and detector standing current, it is necessary to use a 'hot' ECD (250-350 C). The method is shown to be very precise with a standard error not exceeding 1% for automated analysis of ambient air samples. The technology is available to permit highly accurate routine direct analysis of N2O in the troposphere and stratosphere. Both captured air samples or direct real-time measurement from research vessels or airborne platforms are possible.

  6. Activated Ion Electron Capture Dissociation (AI ECD) of proteins: synchronization of infrared and electron irradiation with ion magnetron motion.

    PubMed

    Mikhailov, Victor A; Cooper, Helen J

    2009-05-01

    Here, we show that to perform activated ion electron capture dissociation (AI-ECD) in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer equipped with a CO(2) laser, it is necessary to synchronize both infrared irradiation and electron capture dissociation with ion magnetron motion. This requirement is essential for instruments in which the infrared laser is angled off-axis, such as the Thermo Finnigan LTQ FT. Generally, the electron irradiation time required for proteins is much shorter (ms) than that required for peptides (tens of ms), and the modulation of ECD, AI ECD, and infrared multiphoton dissociation (IRMPD) with ion magnetron motion is more pronounced. We have optimized AI ECD for ubiquitin, cytochrome c, and myoglobin; however the results can be extended to other proteins. We demonstrate that pre-ECD and post-ECD activation are physically different and display different kinetics. We also demonstrate how, by use of appropriate AI ECD time sequences and normalization, the kinetics of protein gas-phase refolding can be deconvoluted from the diffusion of the ion cloud and measured on the time scale longer than the period of ion magnetron motion.

  7. Electronic data capture and DICOM data management in multi-center clinical trials

    NASA Astrophysics Data System (ADS)

    Haak, Daniel; Page, Charles-E.; Deserno, Thomas M.

    2016-03-01

    Providing eligibility, efficacy and security evaluation by quantitative and qualitative disease findings, medical imaging has become increasingly important in clinical trials. Here, subject's data is today captured in electronic case reports forms (eCRFs), which are offered by electronic data capture (EDC) systems. However, integration of subject's medical image data into eCRFs is insufficiently supported. Neither integration of subject's digital imaging and communications in medicine (DICOM) data, nor communication with picture archiving and communication systems (PACS), is possible. This aggravates the workflow of the study personnel, in special regarding studies with distributed data capture in multiple sites. Hence, in this work, a system architecture is presented, which connects an EDC system, a PACS and a DICOM viewer via the web access to DICOM objects (WADO) protocol. The architecture is implemented using the open source tools OpenClinica, DCM4CHEE and Weasis. The eCRF forms the primary endpoint for the study personnel, where subject's image data is stored and retrieved. Background communication with the PACS is completely hidden for the users. Data privacy and consistency is ensured by automatic de-identification and re-labelling of DICOM data with context information (e.g. study and subject identifiers), respectively. The system is exemplarily demonstrated in a clinical trial, where computer tomography (CT) data is de-centrally captured from the subjects and centrally read by a chief radiologists to decide on inclusion of the subjects in the trial. Errors, latency and costs in the EDC workflow are reduced, while, a research database is implicitly built up in the background.

  8. Fine-grid calculations for stellar electron and positron capture rates on Fe isotopes

    SciTech Connect

    Nabi, Jameel-Un; Tawfik, Abdel Nasser

    2013-03-15

    The acquisition of precise and reliable nuclear data is a prerequisite to success for stellar evolution and nucleosynthesis studies. Core-collapse simulators find it challenging to generate an explosion from the collapse of the core of massive stars. It is believed that a better understanding of the microphysics of core-collapse can lead to successful results. The weak interaction processes are able to trigger the collapse and control the lepton-to-baryon ratio (Y{sub e}) of the corematerial. It is suggested that the temporal variation of Y{sub e} within the core of a massive star has a pivotal role to play in the stellar evolution and a fine-tuning of this parameter at various stages of presupernova evolution is the key to generate an explosion. During the presupernova evolution of massive stars, isotopes of iron, mainly {sup 54-56}Fe, are considered to be key players in controlling Y{sub e} ratio via electron capture on these nuclides. Recently an improved microscopic calculation of weak-interaction-mediated rates for iron isotopes was introduced using the proton-neutron quasiparticle random-phase-approximation (pn-QRPA) theory. The pn-QRPA theory allows a microscopic state-by-state calculation of stellar capture rates which greatly increases the reliability of calculated rates. The results were suggestive of some fine-tuning of the Y{sub e} ratio during various phases of stellar evolution. Here we present for the first time the fine-grid calculation of the electron and positron capture rates on {sup 54-56}Fe. The sensitivity of the pn-QRPA calculated capture rates to the deformation parameter is also studied in this work. Core-collapse simulators may find this calculation suitable for interpolation purposes and for necessary incorporation in the stellar evolution codes.

  9. Electron capture into large-l Rydberg states of multiply charged ions escaping from solid surfaces

    NASA Astrophysics Data System (ADS)

    Nedeljković, N.; Nedeljković, Lj.; Mirković, M.

    2003-07-01

    We have investigated the electron capture into large-l Rydberg states of multiply charged ionic projectiles (e.g., the core charges Z=6, 7, and 8) escaping solid surfaces with intermediate velocities (v≈1 a.u.) in the normal emergence geometry. A model of the nonresonant electron capture from the solid conduction band into the moving large angular-momentum Rydberg states of the ions is developed through a generalization of our results obtained previously for the low-l cases (l=0, 1, and 2). The model is based on the two-wave-function dynamics of the Demkov-Ostrovskii type. The electron exchange process is described by a mixed flux through a moving plane (“Firsov plane”), placed between the solid surface and the ionic projectile. Due to low eccentricities of the large-l Rydberg systems, the mixed flux must be evaluated through the whole Firsov plane. It is for this purpose that a suitable asymptotic method is developed. For intermediate ionic velocities and for all relevant values of the principal quantum number n≈Z, the population probability Pnl is obtained as a nonlinear l distribution. The theoretical predictions concerning the ions S VI, Cl VII, and Ar VIII are compared with the available results of the beam-foil experiments.

  10. Fragmentation of peptide negative molecular ions induced by resonance electron capture

    SciTech Connect

    Vasil'ev, Yury V.; Figard, Benjamin J.; Morre, Jeff; Deinzer, Max L.

    2009-07-28

    A simple robust method to study resonance gas-phase reactions between neutral peptides of low volatility and free electrons has been designed and implemented. Resonance electron capture (REC) experiments were performed by several neutral model peptides and two naturally occurring peptides. The assignment of negative ions (NIs) formed in these gas-phase reactions was based on high mass-resolving power experiments. From these accurate mass measurements, it was concluded that fragment NIs formed by low (1-2 eV) energy REC are of the same types as those observed in electron capture/transfer dissociation, where the positive charge is a factor. The main feature resulting from these REC experiments by peptides is the occurrence of z{sub n}-1 ions, which are invariably of the highest abundances in the negative ion mass spectra of larger peptides. [M-H]{sup -} NIs presumably the carboxylate anion structure dominate the REC spectra of smaller peptides. There was no evidence for the occurrence of the complementary reaction, i.e., the formations of c{sub n}+1 ions. Instead, c{sub n} ions arose without hydrogen/proton transfer albeit with lower abundances than that observed for z{sub n}-1 ions. Only the amide forms of small peptides showed more abundant ion peaks for the c{sub n} ions than for the z{sub n}-1 ions. The mechanisms for the N-C{sub {alpha}} bond cleavage are discussed.

  11. Electron capture and emission spectroscopy to study surface and interface magnetism

    NASA Astrophysics Data System (ADS)

    Rau, Carl

    1994-07-01

    Electron capture spectroscopy (ECS) and spin-polarized electron emission spectroscopy (SPEES) are extremely sensitive techniques to probe surface magnetic properties. Ultra-thin bct Fe(100)(1×1)/Pd(100) films exhibit 2D Ising critical behavior. The surface electron spin polarization (ESP) follows precisely the exact solution of the 2D Ising model as given by Yang. The average magnetization of the topmost surface layer is enhanced by 32% compared to that of bulk layers. Pd Auger electrons emitted from the Fe/Pd interface are spin-polarized, and the ESP is oriented parallel to that of emitted Fe Auger electrons. At surfaces of 5nm thick hcp Tb(0001)/W(110) films, strong surface magnetic surface anisotropies are found. The onset of ferromagnetism occurs ≈30 K above the bulk Curie temperature (220K) of Tb. For clean Fe and Fe/Pd surfaces, the ESP of low-energy (≈2 eV) emitted electrons is substantially enhanced by Stoner excitations. The existence of a nonzero ESP at O/Fe surfaces demonstrates the absence of a magnetically dead surface layer.

  12. Neutron Capture and Neutron Total Cross Sections Measurements for {sup 27}Al at the Oak Ridge Electron Linear Accelerator

    SciTech Connect

    Guber, K.H.; Harvey, J.A.; Hill, N.W.; Koehler, P.E.; Leal, L.C.; Sayer, R.O.; Spencer, R.R.; Wright, R.Q.

    1999-08-30

    We have used the Oak Ridge Electron Linear Accelerator (ORELA) to measure neutron total and capture cross sections of {sup 27}Al in the energy range from 100 eV to {approximately}400 keV. We report the resonance parameters as well as the Maxwellian average capture cross sections.

  13. Double electron capture between an α particle and a helium atom in the presence of an intense laser field

    NASA Astrophysics Data System (ADS)

    Li, Shu-Min; Miao, Yan-Gang; Zhou, Zi-Fang; Chen, Ji; Liu, Yao-Yang

    1998-05-01

    In the first Born approximation, the symmetrical double-electron-capture collision between an α particle and a helium atom in the presence of an intense laser field is studied. The capture cross section is promoted considerably and is an increasing function of the ratio of the laser amplitude to frequency. With increasing impact energy, the dressing modification becomes notable.

  14. Electron Capture by a Hydrated Gaseous Peptide: Effects of Water on Fragmentation and Molecular Survival

    PubMed Central

    Prell, James S.; O'Brien, Jeremy T.; Holm, Anne I. S.; Leib, Ryan D.; Donald, William A.; Williams, Evan R.

    2008-01-01

    The effects of water on electron capture dissociation products, molecular survival, and recombination energy are investigated for diprotonated Lys-Tyr-Lys solvated by between zero and 25 water molecules. For peptide ions with between 12 and 25 water molecules attached, electron capture results in a narrow distribution of product ions corresponding to primarily the loss of 10-12 water molecules from the reduced precursor. From these data, the recombination energy (RE) is determined to be equal to the energy that is lost by evaporating on average 10.7 water molecules, or 4.3 eV. Because water stabilizes ions, this value is a lower limit to the RE of the unsolvated ion, but it indicates that the majority of the available RE is deposited into internal modes of the peptide ion. Plotting the fragment ion abundances for ions formed from precursors with fewer than 11 water molecules as a function of hydration extent results in an energy resolved breakdown curve from which the appearance energies of the b2+, y2+, z2+•, c2+, and (KYK + H)+ fragment ions formed from this peptide ion can be obtained; these values are 78, 88, 42, 11, and 9 kcal/mol, respectively. The propensity for H atom loss and ammonia loss from the precursor changes dramatically with the extent of hydration, and this change in reactivity can be directly attributed to a “caging” effect by the water molecules. These are the first experimental measurements of the RE and appearance energies of fragment ions due to electron capture dissociation of a multiply charged peptide. This novel ion nanocalorimetry technique can be applied more generally to other exothermic reactions that are not readily accessible to investigation by more conventional thermochemical methods. PMID:18761457

  15. The Sensitivity of Core-collapse Supernovae to Nuclear Electron Capture

    NASA Astrophysics Data System (ADS)

    Sullivan, Chris; O'Connor, Evan; Zegers, Remco G. T.; Grubb, Thomas; Austin, Sam M.

    2016-01-01

    A weak-rate library aimed at investigating the sensitivity of astrophysical environments to variations of electron-capture rates on medium-heavy nuclei has been developed. With this library, the sensitivity of the core-collapse and early post-bounce phases of core-collapse supernovae to nuclear electron capture is examined. The rates are adjusted by factors consistent with uncertainties indicated by comparing theoretical rates to those deduced from charge-exchange and β-decay measurements. To ensure a model-independent assessment, sensitivity studies across a comprehensive set of progenitors and equations of state are performed. We find a +16/-4% range in the mass of the inner core at shock formation and a ±20% range of peak {ν }e luminosity during the deleptonization burst. These ranges are five times as large as those seen from a separate progenitor study, where we evaluate the sensitivity of these parameters to 32 presupernova models. Additionally, the simulations are found to be more sensitive to a reduction in electron-capture rates than an enhancement, and specifically to the reduction in rates for neutron-rich nuclei near the N = 50 closed neutron shell. As measurements for medium-heavy (A\\gt 65) and neutron-rich nuclei are sparse, and because accurate theoretical models that account for nuclear structure considerations of individual nuclei are not readily available, rates for these nuclei may be overestimated. If more accurate estimates confirm this, results from this study indicate that significant changes to the core-collapse trajectory are expected. For this reason, experimental and theoretical efforts should focus on this region of the nuclear chart.

  16. Neutrino Signal of Electron-Capture Supernovae from Core Collapse to Cooling

    SciTech Connect

    Huedepohl, L.; Mueller, B.; Janka, H.-T.; Marek, A.; Raffelt, G. G.

    2010-06-25

    An 8.8M{sub {center_dot}}electron-capture supernova was simulated in spherical symmetry consistently from collapse through explosion to essentially complete deleptonization of the forming neutron star. The evolution time ({approx}9 s) is short because high-density effects suppress our neutrino opacities. After a short phase of accretion-enhanced luminosities ({approx}200 ms), luminosity equipartition among all species becomes almost perfect and the spectra of {nu}{sub e} and {nu}{sub {mu},{tau}}very similar, ruling out the neutrino-driven wind as r-process site. We also discuss consequences for neutrino flavor oscillations.

  17. Electron-capture Rates for pf-shell Nuclei in Stellar Environments and Nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Suzuki, Toshio; Honma, Michio; Mori, Kanji; Famiano, Michael A.; Kajino, Toshitaka; Hidakai, Jun; Otsuka, Takaharu

    Gamow-Teller strengths in pf-shell nuclei obtained by a new shell-model Hamltonian, GXPF1J, are used to evaluate electron-capture rates in pf-shell nuclei at stellar environments. The nuclear weak rates with GXPF1J, which are generally smaller than previous evaluations for proton-rich nuclei, are applied to nucleosynthesis in type Ia supernova explosions. The updated rates are found to lead to less production of neutron-rich nuclei such as 58Ni and 54Cr, thus toward a solution of the problem of over-production of neutron-rich isotopes of iron-group nuclei compared to the solar abundance.

  18. Neutrino signal of electron-capture supernovae from core collapse to cooling.

    PubMed

    Hüdepohl, L; Müller, B; Janka, H-T; Marek, A; Raffelt, G G

    2010-06-25

    An 8.8M{⊙} electron-capture supernova was simulated in spherical symmetry consistently from collapse through explosion to essentially complete deleptonization of the forming neutron star. The evolution time (∼9  s) is short because high-density effects suppress our neutrino opacities. After a short phase of accretion-enhanced luminosities (∼200  ms), luminosity equipartition among all species becomes almost perfect and the spectra of ν{e} and ν{μ,τ} very similar, ruling out the neutrino-driven wind as r-process site. We also discuss consequences for neutrino flavor oscillations.

  19. Determination of the electron-capture coefficients and the concentration of free electrons in GaN from time-resolved photoluminescence.

    PubMed

    Reshchikov, M A; McNamara, J D; Toporkov, M; Avrutin, V; Morkoç, H; Usikov, A; Helava, H; Makarov, Yu

    2016-11-30

    Point defects in high-purity GaN layers grown by hydride vapor phase epitaxy are studied by steady-state and time-resolved photoluminescence (PL). The electron-capture coefficients for defects responsible for the dominant defect-related PL bands in this material are found. The capture coefficients for all the defects, except for the green luminescence (GL1) band, are independent of temperature. The electron-capture coefficient for the GL1 band significantly changes with temperature because the GL1 band is caused by an internal transition in the related defect, involving an excited state acting as a giant trap for electrons. By using the determined electron-capture coefficients, the concentration of free electrons can be found at different temperatures by a contactless method. A new classification system is suggested for defect-related PL bands in undoped GaN.

  20. Determination of the electron-capture coefficients and the concentration of free electrons in GaN from time-resolved photoluminescence

    PubMed Central

    Reshchikov, M. A.; McNamara, J. D.; Toporkov, M.; Avrutin, V.; Morkoç, H.; Usikov, A.; Helava, H.; Makarov, Yu.

    2016-01-01

    Point defects in high-purity GaN layers grown by hydride vapor phase epitaxy are studied by steady-state and time-resolved photoluminescence (PL). The electron-capture coefficients for defects responsible for the dominant defect-related PL bands in this material are found. The capture coefficients for all the defects, except for the green luminescence (GL1) band, are independent of temperature. The electron-capture coefficient for the GL1 band significantly changes with temperature because the GL1 band is caused by an internal transition in the related defect, involving an excited state acting as a giant trap for electrons. By using the determined electron-capture coefficients, the concentration of free electrons can be found at different temperatures by a contactless method. A new classification system is suggested for defect-related PL bands in undoped GaN. PMID:27901025

  1. Search for two-neutrino double electron capture on 124Xe with the XMASS-I detector

    NASA Astrophysics Data System (ADS)

    Abe, K.; Hiraide, K.; Ichimura, K.; Kishimoto, Y.; Kobayashi, K.; Kobayashi, M.; Moriyama, S.; Nakagawa, K.; Nakahata, M.; Norita, T.; Ogawa, H.; Sekiya, H.; Takachio, O.; Takeda, A.; Yamashita, M.; Yang, B. S.; Kim, N. Y.; Kim, Y. D.; Tasaka, S.; Liu, J.; Martens, K.; Suzuki, Y.; Fujita, R.; Hosokawa, K.; Miuchi, K.; Oka, N.; Onishi, Y.; Takeuchi, Y.; Kim, Y. H.; Lee, J. S.; Lee, K. B.; Lee, M. K.; Fukuda, Y.; Itow, Y.; Kegasa, R.; Kobayashi, K.; Masuda, K.; Takiya, H.; Uchida, H.; Nishijima, K.; Fujii, K.; Murayama, I.; Nakamura, S.

    2016-08-01

    Double electron capture is a rare nuclear decay process in which two orbital electrons are captured simultaneously in the same nucleus. Measurement of its two-neutrino mode would provide a new reference for the calculation of nuclear matrix elements whereas observation of its neutrinoless mode would demonstrate lepton number violation. A search for two-neutrino double electron capture on 124Xe is performed using 165.9 days of data collected with the XMASS-I liquid xenon detector. No significant excess above background was observed and we set a lower limit on the half-life as 4.7 ×1021 years at 90% confidence level. The obtained limit has ruled out parts of some theoretical expectations. We obtain a lower limit on the 126Xe two-neutrino double electron capture half-life of 4.3 ×1021 years at 90% confidence level as well.

  2. Quantitative detection of trace explosive vapors by programmed temperature desorption gas chromatography-electron capture detector.

    PubMed

    Field, Christopher R; Lubrano, Adam; Woytowitz, Morgan; Giordano, Braden C; Rose-Pehrsson, Susan L

    2014-07-25

    The direct liquid deposition of solution standards onto sorbent-filled thermal desorption tubes is used for the quantitative analysis of trace explosive vapor samples. The direct liquid deposition method yields a higher fidelity between the analysis of vapor samples and the analysis of solution standards than using separate injection methods for vapors and solutions, i.e., samples collected on vapor collection tubes and standards prepared in solution vials. Additionally, the method can account for instrumentation losses, which makes it ideal for minimizing variability and quantitative trace chemical detection. Gas chromatography with an electron capture detector is an instrumentation configuration sensitive to nitro-energetics, such as TNT and RDX, due to their relatively high electron affinity. However, vapor quantitation of these compounds is difficult without viable vapor standards. Thus, we eliminate the requirement for vapor standards by combining the sensitivity of the instrumentation with a direct liquid deposition protocol to analyze trace explosive vapor samples.

  3. Stellar electron capture rates on neutron-rich nuclei and their impact on stellar core collapse

    NASA Astrophysics Data System (ADS)

    Raduta, Ad. R.; Gulminelli, F.; Oertel, M.

    2017-02-01

    During the late stages of gravitational core-collapse of massive stars, extreme isospin asymmetries are reached within the core. Due to the lack of microscopic calculations of electron-capture (EC) rates for all relevant nuclei, in general simple analytic parametrizations are employed. We study here several extensions of these parametrizations, allowing for a temperature, electron density, and isospin dependence as well as for odd-even effects. The latter extra degrees of freedom considerably improve the agreement with large-scale microscopic rate calculations. We find, in particular, that the isospin dependence leads to a significant reduction of the global EC rates during core collapse with respect to fiducial results, where rates optimized on calculations of stable f p -shell nuclei are used. Our results indicate that systematic microscopic calculations and experimental measurements in the N ≈50 neutron-rich region are desirable for realistic simulations of the core collapse.

  4. One-electron capture from K shell of atomic targets by proton impact

    NASA Astrophysics Data System (ADS)

    Ghanbari-Adivi, Ebrahim; Ghavaminia, Hoda

    2015-11-01

    A first-order four-body perturbation theory is developed to calculate both the differential and integral cross-sections for K-shell charge exchange from multi-electron atomic targets to the 1s bound state of the fast proton projectiles. The correct boundary conditions are incorporated in the formalism. The model is applied to the single electron capture process from carbon, nitrogen, oxygen, neon and argon atoms for which the experimental data are available. The results are compared with their corresponding experimental values and also with those obtained from three-body version of the theory. A comparison is also made between the present predicted cross-sections and those obtained from other theories. Comparisons show that the suggested approximation is in reasonable agreement with the experimental data and is compatible with the other theories.

  5. Charge-changing collisions of argon ions on argon gas. One-electron capture

    SciTech Connect

    Aubert, J.; Bliman, S.; Geller, R.; Jacquot, B.; Van Houtte, D.

    1980-12-01

    Single-electron-capture cross sections have been measured for argon ions with initial charges 2< or =q< or =12 incident on an argon-gas target. The cross sections show little dependence on the incident ion energy in the range 1q--10q keV. A remarkable oscillating feature is seen for cross sections sigma/sub q/,q-1 when q> or =7. Particularly, sigma/sub 8,7/ is smaller than sigma/sub 7,6/ and sigma/sub 9,8/, the Ar/sup 8 +/ electronic structure being Ne-like. Variation of the cross section is shown as function of the initial charge at constant energy.

  6. Mechanism of 'GSI oscillations' in electron capture by highly charged hydrogen-like atomic ions

    SciTech Connect

    Krainov, V. P.

    2012-07-15

    We suggest a qualitative explanation of oscillations in electron capture decays of hydrogen-like {sup 140}Pr and {sup 142}Pm ions observed recently in an ion experimental storage ring (ESR) of Gesellschaft fuer Schwerionenforschung (GSI) mbH, Darmstadt, Germany. This explanation is based on the electron multiphoton Rabi oscillations between two Zeeman states of the hyperfine ground level with the total angular momentum F = 1/2. The Zeeman splitting is produced by a constant magnetic field in the ESR. Transitions between these states are produced by the second, sufficiently strong alternating magnetic field that approximates realistic fields in the GSI ESR. The Zeeman splitting amounts to only about 10{sup -5} eV. This allows explaining the observed quantum beats with the period 7 s.

  7. Electron Capture from Linear Stark Rydberg States above the Matching Velocity

    NASA Astrophysics Data System (ADS)

    Ciocca, M.; Creasey, C.; MacAdam, K. B.

    1998-05-01

    The relative cross section for electron capture by singly charged ions from linear Stark Rydberg states of Na has been measured, both as a function of the angle of impact and of projectile velocity. The target, the topmost state of the n = 24 Stark manifold, was prepared by two-step laser excitation from the Na ground state, via 3p_3/2, in an electric field F_Stark= 160 V/cm. By means of a device perfected in our laboratory (the "Stark Barrel"), we aligned the target by adiabatically switching the electric field, after excitation, down to a preset low value and a desired direction in the plane determined by the ion and Na beams. Thermionic emission ion sources of Li and Na were operated at accelerating voltages 400-2000 V to allow study of electron capture in the reduced velocity range v = 1.0 - 2.5. This augments an earlier study by Homan footnote D. M. Homan, Ph. D. Dissertation, University of Kentucky 1997, unpublished. at lower velocities.

  8. Breathing-mode lattice relaxation accompanying emission and capture by deep electronic levels in silicon

    SciTech Connect

    Samara, G. A.

    1989-05-15

    The breathing-mode (volume) lattice relaxations associated with carrier emission and capture by a variety of deep electronic levels in silicon are evaluated from high-pressure measurements of the emission rates and capture cross sections. Included are (1) the vacancylike acceptor levels associated with the oxygen-vacancy pair (or /ital A/ center) and the gold, platinum, and palladium impurities, (2) the chalcogenide donors in their singly and doubly charged states, (3) a number of 3/ital d/ transition-metal donors, and (4) the phosphorus-vacancy pair (or /ital E/ center) acceptor. The signs and magnitudes (which range from /similar to/0 to 5 A/sup 3//emitted-carrier) of these relaxations are discussed in terms of models for the impurities and defects responsible for the associated levels. The results on the chalcogenides are compared with recent theoretical results. The experimental method used appears to be the only viable experimental method for determining these relaxations which are a direct manifestation of the effective electron-phonon coupling at deep levels and which are important to the understanding of many of the properties of deep levels.

  9. Procurement of shared data instruments for Research Electronic Data Capture (REDCap).

    PubMed

    Obeid, Jihad S; McGraw, Catherine A; Minor, Brenda L; Conde, José G; Pawluk, Robert; Lin, Michael; Wang, Janey; Banks, Sean R; Hemphill, Sheree A; Taylor, Rob; Harris, Paul A

    2013-04-01

    REDCap (Research Electronic Data Capture) is a web-based software solution and tool set that allows biomedical researchers to create secure online forms for data capture, management and analysis with minimal effort and training. The Shared Data Instrument Library (SDIL) is a relatively new component of REDCap that allows sharing of commonly used data collection instruments for immediate study use by research teams. Objectives of the SDIL project include: (1) facilitating reuse of data dictionaries and reducing duplication of effort; (2) promoting the use of validated data collection instruments, data standards and best practices; and (3) promoting research collaboration and data sharing. Instruments submitted to the library are reviewed by a library oversight committee, with rotating membership from multiple institutions, which ensures quality, relevance and legality of shared instruments. The design allows researchers to download the instruments in a consumable electronic format in the REDCap environment. At the time of this writing, the SDIL contains over 128 data collection instruments. Over 2500 instances of instruments have been downloaded by researchers at multiple institutions. In this paper we describe the library platform, provide detail about experience gained during the first 25months of sharing public domain instruments and provide evidence of impact for the SDIL across the REDCap consortium research community. We postulate that the shared library of instruments reduces the burden of adhering to sound data collection principles while promoting best practices.

  10. Interstellar propagation and electron capture processes of galactic cosmic ray heavy ions in space

    NASA Technical Reports Server (NTRS)

    Miltra, B.; Biswas, S.; Goswami, J. N.

    1995-01-01

    The new information on galactic cosmic rays (GCR) derived from the Spacelab-3 cosmic ray experiment 'Anuradha' shows that at 25-125 MeV/N GCR sub-iron and iron (Z = 21-28) particles consists of a mixture of partially ionized and fully ionized ions. Computation of electron capture and loss cross sections in hydrogen in 1-50 MeV/N energy range are made for Fe, Cr, Ti and Ni. From these it is concluded that: (1) these GCR particles must have captured orbital electrons at energies of about 1-5 MeV/N and (2) these particles are then reaccelerated to 300-500 MeV/N most probably in interstellar medium by collision with SNR shock fronts. Some reacceleration may take place also in heliospheric boundary region. It is suggested that these observations of partially ionized GCR ions of about 100 MeV/N in Spacelab-3 provide a direct evidence of reacceleration of GCR.

  11. Mechanistic Study on Electron Capture Dissociation of the Oligosaccharide-Mg2+ Complex

    PubMed Central

    Huang, Yiqun; Pu, Yi; Yu, Xiang; Costello, Catherine E.; Lin, Cheng

    2014-01-01

    Electron capture dissociation (ECD) has shown great potential in structural characterization of glycans. However, our current understanding of the glycan ECD process is inadequate for accurate interpretation of the complex glycan ECD spectra. Here, we present the first comprehensive theoretical investigation on the ECD fragmentation behavior of metal-adducted glycans, using the cellobiose-Mg2+ complex as the model system. Molecular dynamics simulation was carried out to determine the typical glycan-Mg2+ binding patterns and the lowest-energy conformer identified was used as the initial geometry for density functional theory-based theoretical modeling. It was found that the electron is preferentially captured by Mg2+ and the resultant Mg+• can abstract a hydroxyl group from the glycan moiety to form a carbon radical. Subsequent radical migration and α-cleavage(s) result in the formation of a variety of product ions. The proposed hydroxyl abstraction mechanism correlates well with the major features in the ECD spectrum of the Mg2+-adducted cellohexaose. The mechanism presented here also predicts the presence of secondary, radical-induced fragmentation pathways. These secondary fragment ions could be misinterpreted, leading to erroneous structural determination. The present study highlights an urgent need for continuing investigation of the glycan ECD mechanism, which is imperative for successful development of bioinformatics tools that can take advantage of the rich structural information provided by ECD of metal-adducted glycans. PMID:24845360

  12. Capture and emission of electrons in quantum wells under applied electric field

    NASA Astrophysics Data System (ADS)

    Vinter, B.; Luc, F.; Bois, P.; Thibaudeau, L.; Rosencher, E.

    1994-06-01

    Important characteristics of Quantum Well Infrared Photodetectors are determined almost entirely by the photoionization rate of electrons out of the Quantum Well (QW) and the recapture into the QWs. To elucidate these processes microscopically we have made structures in which the QWs are isolated from one contact by a completely blocking barrier, so that the steady state current vanishes. The transient current induced by photoionization out of the QWs gives a direct measurement of the photoionization cross section and the escape probability of a photoexcited electron. We have found that the variation of the latter with the electric field may be described by a simple barrier lowering model combined with statistical fluctuation of the QW width. The capture process has been studied by impedance spectroscopy in samples containing only one well. The capture velocity thus measured is found to decrease with increasing applied electric field but within experimental uncertainties it does not depend on the width of the well for well widths between 3 and 7.5 nm. Theoretical results on optical phonon mediated transitions in the applied field from barrier to well states show a generally good agreement with experiment at low fields but less dependence on the field.

  13. Atmospheric measurements of carbonyl sulfide, dimethyl sulfide, and carbon disulfide using the electron capture sulfur detector

    NASA Technical Reports Server (NTRS)

    Johnson, James E.; Bates, Timothy S.

    1993-01-01

    Measurements of atmospheric dimethyl sulfide (DMS), carbonyl sulfide (COS), and carbon disulfide (CS2) were conducted over the Atlantic Ocean on board the NASA Electra aircraft during the Chemical Instrumentation Test and Evaluation (CITE 3) project using the electron capture sulfur detector (ECD-S). The system employed cryogenic preconcentration of air samples, gas chromatographic separation, catalytic fluorination, and electron capture detection. Samples collected for DMS analysis were scrubbed of oxidants with NaOH impregnated glass fiber filters to preconcentration. The detection limits (DL) of the system for COS, DMS, and CS2 were 5, 5, and 2 ppt, respectively. COS concentrations ranged from 404 to 603 ppt with a mean of 489 ppt for measurements over the North Atlantic Ocean (31 deg N to 41 deg N), and from 395 to 437 ppt with a mean of 419 ppt for measurements over the Tropical Atlantic Ocean (11 deg S to 2 deg N). DMS concentrations in the lower marine boundary layer, below 600-m altitude, ranged from below DL to 150 ppt from flights over the North Atlantic, and from 9 to 104 ppt over the Tropical Atlantic. CS2 concentrations ranged from below DL to 29 ppt over the North Atlantic. Almost all CS2 measurements over the Tropical Atlantic were below DL.

  14. Measuring the axial form factor of {sup 3}He using weak capture of polarized electrons

    SciTech Connect

    Dutta, D.

    2013-11-07

    A low energy, high intensity polarized electron beam could enable the extraction of the A=3 weak axial form factors F{sub A} using the reaction →e+{sup 3}He→{sup 3}H+ν. These form factors have never been measured before. We discuss the feasibility of such an experiment using a small toroidal magnet and a radial low energy recoil detector to tag the recoil tritons. A moderately high intensity polarized electron beam (>500 μA) with beam energies between 50 - 150 MeV is necessary for the cross section measurement and to provides a free clean measurement of the background. Moreover, in addition to the cross section, by measuring the electron spin and recoil triton correlation coefficient it may be possible to search for second class currents and to extract the ratio of the axial to the vector form factor of the nucleon. Such novel electron scattering based measurements would have a completely different set of systematic uncertainties compared to polarized neutron beta decay, neutrino scattering and muon capture experiments which are typically used to extract the weak form-factors.

  15. Independent-electron analysis of the x-ray spectra from single-electron capture in Ne10 + collisions with He, Ne, and Ar atoms

    NASA Astrophysics Data System (ADS)

    Leung, Anthony C. K.; Kirchner, Tom

    2015-09-01

    We present a theoretical study on the x-ray spectra from single-electron capture in 4.54 keV/amu Ne10 +-He, -Ne, and -Ar collisions. Single-particle capture probabilities were calculated using the two-center basis generator method within the independent electron model. In this framework we investigated the effects of a time-dependent screening potential that models target response on capture cross sections and x-ray spectra. Excellent agreement is shown with the previously measured relative cross sections and x-ray spectra and calculations based on the classical trajectory Monte Carlo method using the no-response single-particle electron capture probabilities in a multinomial single-electron capture analysis. Our results demonstrate the importance of using this consistent statistical analysis of single-electron capture within the independent electron model; a requirement that a previous calculation for the same collision problem using the two-center atomic-orbital close-coupling method may not have considered.

  16. Searching for Experimental Verification of the Oscillation of Electron Capture Decay Probability

    NASA Astrophysics Data System (ADS)

    Vetter, Paul

    2009-05-01

    A group from Gesellschaft f"ur Schwerionenforschung (GSI) last year published an observation of time oscillations of the electron capture decay rate of stored hydrogen-like ions of ^142Pm and ^140Pr.(Phys. Lett. B 664, 162 (2008)). They proposed that the oscillating decay rate was caused by interference between momentum states of the ion caused by neutrino mass and flavor mixing. This hypothesis has been controversial, with several authors arguing either that neutrino mixing can or cannot be responsible. If neutrino mixing is responsible for the decay rate oscillations, then it should be possible to detect these oscillations in a simpler experiment without using stored hydrogenic ions, by observing an electron capture decay rate with an appropriate experiment time structure. If this were possible, it could revolutionize the study of neutrino mixing by allowing much simpler experiments to make precise measurements of mass differences and mixing angles. At LBNL, we performed an experiment to search for oscillations in electron capture rate using ^142Pm produced with a time short compared to the oscillation period, and counting ^142Nd Kα x-rays from the daughter. The decay time spectrum is well-described by a simple exponential, and we observed no statistically significant decay rate oscillations at a level much lower than proposed. A literature search for previous experiments that might have been sensitive to the reported modulation uncovered a candidate in ^142Eu. A reanalysis of that published data shows no decay rate oscillation. A recent experiment at Munich also did not observe decay rate oscillations in decays of ^180Re. Other potential explanations for the GSI decay oscillation data have been proposed, including quantum beats by nearly degenerate initial parent ion states and Thomas precession in the stored ions. I will discuss the status of experimental results, and possibilities for experimental confirmation of the various models. This work was supported by

  17. Electron-capture collisions at keV energies of multiply charged ions of carbon and argon with molecular deuterium

    SciTech Connect

    Bliman, S.; Aubert, J.; Geller, R.; Jacquot, B.; Van Houtte, D.

    1981-04-01

    Single- and double-electron-capture cross sections have been measured for C/sup q/+ with initial charges 2 < or = q < or = 6 and for Ar/sup q/+ with initial charges 2 < or = q < or = 12 incident on molecular deuterium gas targets. The cross sections show little dependence on the incident-ion energy for the range studied 2q to 10q keV. The single-electron-capture cross sections do not vary monotonically with the initial charge, but show an oscillation about a mean curve, reflecting the projectile electronic structure.

  18. Principles of electron capture and transfer dissociation mass spectrometry applied to peptide and protein structure analysis.

    PubMed

    Zhurov, Konstantin O; Fornelli, Luca; Wodrich, Matthew D; Laskay, Ünige A; Tsybin, Yury O

    2013-06-21

    This tutorial review describes the principles and practices of electron capture and transfer dissociation (ECD/ETD or ExD) mass spectrometry (MS) employed for peptide and protein structure analysis. ExD MS relies on interactions between gas phase peptide or protein ions carrying multiple positive charges with either free low-energy (~1 eV) electrons (ECD), or with reagent radical anions possessing an electron available for transfer (ETD). As a result of recent implementation on sensitive, high resolution, high mass accuracy, and liquid chromatography timescale-compatible mass spectrometers, ExD, more specifically, ETD MS has received particular interest in life science research. In addition to describing the fundamental aspects of ExD radical ion chemistry, this tutorial provides practical guidelines for peptide de novo sequencing with ExD MS, as well as reviews some of the current capabilities and limitations of these techniques. The merits of ExD MS are discussed primarily within the context of life science research.

  19. Repeatability and reproducibility of product ion abundances in electron capture dissociation mass spectrometry of peptides.

    PubMed

    Ben Hamidane, Hisham; Vorobyev, Aleksey; Tsybin, Yury O

    2011-01-01

    Site-specific reproducibility and repeatability of electron capture dissociation (ECD) in Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) are of fundamental importance for product ion abundance (PIA)-based peptide and protein structure analysis. However, despite the growing interest in ECD PIA-based applications, these parameters have not yet been investigated in a consistent manner. Here, we first provide a detailed description of the experimental parameters for ECD-based tandem mass spectrometry performed on a hybrid linear ion trap (LTQ) FT-ICR MS. In the following, we describe the evaluation and comparison of ECD and infrared multiphoton dissociation (IRMPD) PIA methodologies upon variation of a number of experimental parameters, for example, cathode potential (electron energy), laser power, electron and photon irradiation periods and pre- irradiation delays, as well as precursor ion number. Ranges of experimental parameters that yielded an average PIA variation below 5% and 15% were determined for ECD and IRMPD, respectively. We report cleavage site-dependent ECD PIA variation below 20% and correlation coefficients between fragmentation patterns superior to 0.95 for experiments performed on three FT-ICR MS instruments. Overall, the encouraging results obtained for ECD PIA reproducibility and repeatability support the use of ECD PIA as a complementary source of information to m/z data in radical-induced dissociation applied for peptide and protein structure analysis.

  20. Effect of piezoelectric field of threading dislocations on electron transport and capture in nitride semiconductors

    NASA Astrophysics Data System (ADS)

    Romanov, Dmitri; Auner, Gregory

    2001-03-01

    In nitride semiconductor structures, stress is known to induce considerable electric fields due to piezoelectric effect. We consider an AlN layer grown on a sapphire substrate and containing a number of threading dislocations. Most them are edge dislocations running in the growth direction. The strain field of such a dislocation results in electric field aligned with the dislocation axis and having alternate directions in the areas of compression and tension. These electric fields make for anisotropic electron diffusion in the layer. They also change the rates of electron capture by impurities, depending on the distance to the dislocation core. We apply these results to photoexcited electrons in a GaN/AlN quantum dot system where the dot nucleation occurred preferably in the tension regions near the dislocations [1]. The biased diffusion leads to photoinduced polarization of the dot-containing layer even in the absence of external electric field. [1] J.L. Rouviere, J. Simon, N. Pelekanos, B. Daudin, and G. Feuillet, Appl. Phys. Lett., 75, 2632-2634 (1999)

  1. Calculations of nuclear excitation by electron capture (NEET) in nonlocal thermodynamic equilibrium plasmas

    SciTech Connect

    Morel, P.; Meot, V.; Gosselin, G.; Faussurier, G.; Blancard, C.

    2010-03-15

    The nuclear excitation by electron capture (NEET) process may occur when the energy differences between two nuclear levels and between two electronic states are nearly equal, provided the quantum selection rules are fulfilled. These resonant conditions drastically limit the number of possible candidates, even though thermodynamic conditions encountered in hot dense plasmas do modify the orbital electronic binding energy and the resonance conditions. {sup 201}Hg, with a low-lying isomeric state located at 1.565 keV, can be excited by NEET process in a laser-created plasma. However, its correct calculation requires nonlocal thermodynamic equilibrium (non-LTE) atomic physics treatment because current laser-created plasmas do not reach high-enough temperature in the area at LTE. In this article, we describe the calculation leading to an estimated excitation rate and discuss the influence of LTE/non-LTE physics with an average-atom model and the use of a Gaussian variance calculation to estimate the broadening around the mean energy mismatch.

  2. Fragmentation of peptide negative molecular ions induced by resonance electron capture

    PubMed Central

    Vasil’ev, Yury V.; Figard, Benjamin J.; Morré, Jeff; Deinzer, Max L.

    2009-01-01

    A simple robust method to study resonance gas-phase reactions between neutral peptides of low volatility and free electrons has been designed and implemented. Resonance electron capture (REC) experiments were performed by several neutral model peptides and two naturally occurring peptides. The assignment of negative ions (NIs) formed in these gas-phase reactions was based on high mass-resolving power experiments. From these accurate mass measurements, it was concluded that fragment NIs formed by low (1–2 eV) energy REC are of the same types as those observed in electron capture∕transfer dissociation, where the positive charge is a factor. The main feature resulting from these REC experiments by peptides is the occurrence of zn−1 ions, which are invariably of the highest abundances in the negative ion mass spectra of larger peptides. [M–H]− NIs presumably the carboxylate anion structure dominate the REC spectra of smaller peptides. There was no evidence for the occurrence of the complementary reaction, i.e., the formations of cn+1 ions. Instead, cn ions arose without hydrogen∕proton transfer albeit with lower abundances than that observed for zn−1 ions. Only the amide forms of small peptides showed more abundant ion peaks for the cn ions than for the zn−1 ions. The mechanisms for the N–Cα bond cleavage are discussed. PMID:19655877

  3. Capturing buried defects in metal interconnections with electron beam inspection system

    NASA Astrophysics Data System (ADS)

    Xiao, Hong; Jiang, Ximan; Trease, David; Van Riet, Mike; Ramprasad, Shishir; Bhatia, Anadi; Lefebvre, Pierre; Bastard, David; Moreau, Olivier; Maher, Chris; MacDonald, Paul; Campochiaro, Cecelia

    2013-04-01

    In this paper we present a novel mode of electron beam inspection (EBI), entitled super wide optics (SWO) mode, which can effectively detect buried defects in tungsten (W) plugs and copper (Cu) wires. These defects are defects of interest (DOI) to integrated circuit (IC) manufacturers because they are not detectable in optical inspection, voltage contrast (VC) mode EBI or physical mode EBI. We used engineering systems to study two samples, a tungsten chemical mechanical polish (CMP) wafer and a copper CMP wafer with a silicon carbon nitride (SiCN) cap layer. EBI with our novel SWO mode was found to capture many dark defects on these two wafers. Furthermore, defect review with all three EBI modes found some of these dark defects were unique to SWO mode. For verification, physical failure analysis was performed on some SWO-unique DOI. The cross-sectional scanning electron microscope (SEM) images and transmission electron microscope (TEM) images confirmed that the unique DOI were buried voids in W-plugs and copper wire thinning caused by either buried particles or buried particle induced metal trench under-etch. These DOI can significantly increase the resistance of metal interconnects of IC chip and affect the chip yield. This new EBI mode can provide an in-line monitoring solution for these DOI, which does not exist before this study.

  4. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe.

    PubMed

    Zhang, C J; Hua, J F; Xu, X L; Li, F; Pai, C-H; Wan, Y; Wu, Y P; Gu, Y Q; Mori, W B; Joshi, C; Lu, W

    2016-07-11

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of the wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. The capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method.

  5. Electron capture by Ne{sup 4+} ions from atomic hydrogen

    SciTech Connect

    Havener, C.C.; Rejoub, R.; Vane, C.R.; Krause, H.F.; Savin, D.W.; Schnell, M.; Wang, J.G.; Stancil, P.C.

    2005-03-01

    Using the Oak Ridge National Laboratory ion-atom merged-beams apparatus, the absolute total electron-capture cross section has been measured for collisions of Ne{sup 4+} with hydrogen and deuterium at relative energies in the center-of-mass frame between 0.10 and 1006 eV/u. Comparison with previous measurements shows large discrepancies between 80 and 600 eV/u. For energies below {approx}1 eV/u, a sharply increasing cross section is attributed to the ion-induced dipole attraction between the reactants. Multichannel Landau-Zener calculations are performed between 0.01 and 5000 eV/u and compare well to the measured total cross sections. Below {approx}5 eV/u, the present total cross section calculations show a significant target isotope effect. At 0.01 eV/u, the H:D total cross section ratio is predicted to be {approx}1.4 where capture is dominated by transitions into the Ne{sup 3+} (2s{sup 2}2p{sup 2}3d) configuration.

  6. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe

    SciTech Connect

    Zhang, C. J.; Hua, J. F.; Xu, X. L.; Li, F.; Pai, C. -H.; Wan, Y.; Wu, Y. P.; Gu, Y. Q.; Mori, W. B.; Joshi, C.; Lu, W.

    2016-07-11

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of the wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. As a result, the capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method.

  7. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe

    DOE PAGES

    Zhang, C. J.; Hua, J. F.; Xu, X. L.; ...

    2016-07-11

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of themore » wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. As a result, the capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method.« less

  8. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe

    PubMed Central

    Zhang, C. J.; Hua, J. F.; Xu, X. L.; Li, F.; Pai, C.-H.; Wan, Y.; Wu, Y. P.; Gu, Y. Q.; Mori, W. B.; Joshi, C.; Lu, W.

    2016-01-01

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of the wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. The capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method. PMID:27403561

  9. Examination of the possible enhancement of neutrinoless double-electron capture in 78Kr

    NASA Astrophysics Data System (ADS)

    Bustabad, S.; Bollen, G.; Brodeur, M.; Lincoln, D. L.; Novario, S. J.; Redshaw, M.; Ringle, R.; Schwarz, S.

    2013-09-01

    Penning-trap mass spectrometry was used at the Low-Energy Beam and Ion Trap (LEBIT) facility at the National Superconducting Cyclotron Laboratory (NSCL) to investigate 78Kr, a candidate for resonantly enhanced neutrinoless double-electron capture (0νECEC). The newly determined Q value of 2847.75 (27) keV is 1.4 keV greater than the value from the most recent atomic mass evaluation [Chin. Phys. C1674-113710.1088/1674-1137/36/12/003 36, 1603 (2012)], a change of two sigma, and the uncertainty has been reduced by a factor of three. The change in the Q value shifts allowed 0νECEC in 78Kr further from resonant enhancement. With the improved determination of the Q value, all known excited states can now be confidently excluded from possible 78Se candidates that could lead to resonantly enhanced 0νECEC.

  10. Pesticide residue analysis of vegetables by gas chromatography with electron-capture detection.

    PubMed

    Fenoll, José; Hellín, Pilar; Martínez, Carmen M; Flores, Pilar

    2007-01-01

    A new and original analytical method was developed for the routine analysis of 28 multiclass pesticide residues in vegetables (green pepper, red pepper, and tomato). The extraction was performed with acetone, and the pesticides were partitioned into ethyl acetate-cyclohexane (1 + 1, v/v). Residue levels in vegetables were determined by gas chromatography (GC) with electron-capture detection. Residue identities were confirmed by GC coupled with mass spectrometry in the selected ion monitoring mode. The average recoveries in pepper and tomato obtained for all analytes studied were 67.3 and 123.1%, respectively, with relative standard deviation between 1.8 and 7.0%. The detection limit for the pesticides studied varied from 0.1 to 2.6 microg/kg. The proposed method was applied to the analysis of these compounds in vegetables grown in experimental greenhouses.

  11. Weak {gamma}-transition intensities in the electron capture decay of {sup 144}Pm

    SciTech Connect

    Robinson, S.J.; Altgilbers, A.S.; Hindi, M.M.; Norman, E.B.; Larimer, R.

    1996-09-01

    We have determined the absolute intensity of weak {gamma} transitions in the level scheme of {sup 144}Nd, observed following the electron capture decay of {sup 144}Pm. The absolute intensity of the 1397-keV {ital E}3 branch from the 2093-keV (5{sub 1}{sup {minus}}) level was determined to be (4.9 {plus_minus} 0.7) {times} 10{sup {minus}4}{percent}. This leads to a revised absolute transition rate of {ital B}({ital E}3;5{sub 1}{sup {minus}}{r_arrow}2{sup +}{sub 1})=26{sub {minus}12}{sup +15} Weisskopf units, which is still consistent with an interpretation of the 5{sub 1}{sup {minus}} level based on quadrupole-octupole coupling. {copyright} {ital 1996 The American Physical Society.}

  12. Low-Energy Electron Capture in Collisions of C3+ with He

    SciTech Connect

    Wu, Y.; Qi, Y. Y.; Yan, J.; Wang, J. G.; Li, Y.; Buenker, R. J.; Kato, D.; Krstic, Predrag S

    2009-01-01

    Charge transfer processes due to collisions of ground-state C{sup 3+}(1s{sup 2}2s {sup 2}S) ions with He atoms are studied using the quantum-mechanical molecular-orbital close-coupling method for energies in the range 10{sup -4}-2 x 10{sup 3} eV/u. The ab initio adiabatic potentials and radial couplings utilized in the calculations are obtained from the multireference single- and double-excitation configuration interaction approach. Total and state-selective single-electron capture cross sections and rate coefficients are calculated and compared with the available experimental and theoretical data. A good agreement is found between the measured cross sections and the present calculations. However, the previous calculations of total rate coefficients using the Landau-Zener model are one to two orders of magnitude smaller than the present results.

  13. Do electron-capture supernovae make neutron stars?. First multidimensional hydrodynamic simulations of the oxygen deflagration

    NASA Astrophysics Data System (ADS)

    Jones, S.; Röpke, F. K.; Pakmor, R.; Seitenzahl, I. R.; Ohlmann, S. T.; Edelmann, P. V. F.

    2016-09-01

    Context. In the classical picture, electron-capture supernovae and the accretion-induced collapse of oxygen-neon white dwarfs undergo an oxygen deflagration phase before gravitational collapse produces a neutron star. These types of core collapse events are postulated to explain several astronomical phenomena. In this work, the oxygen deflagration phase is simulated for the first time using multidimensional hydrodynamics. Aims: By simulating the oxygen deflagration with multidimensional hydrodynamics and a level-set-based flame approach, new insights can be gained into the explosive deaths of 8-10 M⊙ stars and oxygen-neon white dwarfs that accrete material from a binary companion star. The main aim is to determine whether these events are thermonuclear or core-collapse supernova explosions, and hence whether neutron stars are formed by such phenomena. Methods: The oxygen deflagration is simulated in oxygen-neon cores with three different central ignition densities. The intermediate density case is perhaps the most realistic, being based on recent nuclear physics calculations and 1D stellar models. The 3D hydrodynamic simulations presented in this work begin from a centrally confined flame structure using a level-set-based flame approach and are performed in 2563 and 5123 numerical resolutions. Results: In the simulations with intermediate and low ignition density, the cores do not appear to collapse into neutron stars. Instead, almost a solar mass of material becomes unbound from the cores, leaving bound remnants. These simulations represent the case in which semiconvective mixing during the electron-capture phase preceding the deflagration is inefficient. The masses of the bound remnants double when Coulomb corrections are included in the equation of state, however they still do not exceed the effective Chandrasekhar mass and, hence, would not collapse into neutron stars. The simulations with the highest ignition density (log 10ρc = 10.3), representing the case

  14. A review of electron-capture and electron-transfer dissociation tandem mass spectrometry in polymer chemistry.

    PubMed

    Hart-Smith, Gene

    2014-01-15

    Mass spectrometry (MS)-based studies of synthetic polymers often characterise detected polymer components using mass data alone. However when mass-based characterisations are ambiguous, tandem MS (MS/MS) offers a means by which additional analytical information may be collected. This review provides a synopsis of two particularly promising methods of dissociating polymer ions during MS/MS: electron-capture and electron-transfer dissociation (ECD and ETD, respectively). The article opens with a summary of the basic characteristics and operating principles of ECD and ETD, and relates these techniques to other methods of dissociating gas-phase ions, such as collision-induced dissociation (CID). Insights into ECD- and ETD-based MS/MS, gained from studies into proteins and peptides, are then discussed in relation to polymer chemistry. Finally, ECD- and ETD-based studies into various classes of polymer are summarised; for each polymer class, ECD- and ETD-derived data are compared to CID-derived data. These discussions identify ECD and ETD as powerful means by which unique and diagnostically useful polymer ion fragmentation data may be generated, and techniques worthy of increased utilisation by the polymer chemistry community.

  15. Population of n, l States in Electron-Capture Collisions Between Highly Charged, Medium-Velocity Ions and H2

    NASA Astrophysics Data System (ADS)

    Hvelplund, P.; Samsoe, E.; Andersen, L. H.; Haugen, H. K.; Knudsen, H.

    1983-01-01

    The formation of excited states resulting from electron capture by Auq+ ions (q from 12 to 18, v = 2v0) colliding with H2 has been measured by means of optical methods. The capture cross sections into various n, l states are derived from measured emission cross sections by applying a simplified cascade correction. It is found that high l states are preferentially populated and that a large number of n states contributes to the total capture process. The general picture, which emerges from the present study, is in reasonable agreement with theoretical calculations by Olson, by Ryufuku and Watanabe, and by Crothers.

  16. Search for two-neutrino double electron capture of 124Xe with XENON100

    NASA Astrophysics Data System (ADS)

    Aprile, E.; Aalbers, J.; Agostini, F.; Alfonsi, M.; Amaro, F. D.; Anthony, M.; Arneodo, F.; Barrow, P.; Baudis, L.; Bauermeister, B.; Benabderrahmane, M. L.; Berger, T.; Breur, P. A.; Brown, A.; Brown, E.; Bruenner, S.; Bruno, G.; Budnik, R.; Bütikofer, L.; Calvén, J.; Cardoso, J. M. R.; Cervantes, M.; Cichon, D.; Coderre, D.; Colijn, A. P.; Conrad, J.; Cussonneau, J. P.; Decowski, M. P.; de Perio, P.; di Gangi, P.; di Giovanni, A.; Diglio, S.; Duchovni, E.; Fei, J.; Ferella, A. D.; Fieguth, A.; Franco, D.; Fulgione, W.; Gallo Rosso, A.; Galloway, M.; Gao, F.; Garbini, M.; Geis, C.; Goetzke, L. W.; Greene, Z.; Grignon, C.; Hasterok, C.; Hogenbirk, E.; Itay, R.; Kaminsky, B.; Kessler, G.; Kish, A.; Landsman, H.; Lang, R. F.; Lellouch, D.; Levinson, L.; Le Calloch, M.; Levy, C.; Lin, Q.; Lindemann, S.; Lindner, M.; Lopes, J. A. M.; Manfredini, A.; Marrodán Undagoitia, T.; Masbou, J.; Massoli, F. V.; Masson, D.; Mayani, D.; Meng, Y.; Messina, M.; Micheneau, K.; Miguez, B.; Molinario, A.; Murra, M.; Naganoma, J.; Ni, K.; Oberlack, U.; Orrigo, S. E. A.; Pakarha, P.; Pelssers, B.; Persiani, R.; Piastra, F.; Pienaar, J.; Piro, M.-C.; Plante, G.; Priel, N.; Rauch, L.; Reichard, S.; Reuter, C.; Rizzo, A.; Rosendahl, S.; Rupp, N.; Dos Santos, J. M. F.; Sartorelli, G.; Scheibelhut, M.; Schindler, S.; Schreiner, J.; Schumann, M.; Scotto Lavina, L.; Selvi, M.; Shagin, P.; Silva, M.; Simgen, H.; Sivers, M. V.; Stein, A.; Thers, D.; Tiseni, A.; Trinchero, G.; Tunnell, C. D.; Wall, R.; Wang, H.; Weber, M.; Wei, Y.; Weinheimer, C.; Wulf, J.; Zhang, Y.; Xenon Collaboration

    2017-02-01

    Two-neutrino double electron capture is a rare nuclear decay where two electrons are simultaneously captured from the atomic shell. For 124Xe this process has not yet been observed and its detection would provide a new reference for nuclear matrix element calculations. We have conducted a search for two-neutrino double electron capture from the K shell of 124Xe using 7636 kg d of data from the XENON100 dark matter detector. Using a Bayesian analysis we observed no significant excess above background, leading to a lower 90% credibility limit on the half-life T1 /2>6.5 ×1020 yr. We have also evaluated the sensitivity of the XENON1T experiment, which is currently being commissioned, and found a sensitivity of T1 /2>6.1 ×1022 yr after an exposure of 2 t yr .

  17. Electron capture by U(91+) and U(92+) and ionization of U(90+) and U(91+)

    NASA Technical Reports Server (NTRS)

    Gould, H.; Greiner, D.; Lindstrom, P.; Symons, T. J. M.; Crawford, H.

    1984-01-01

    U(92+)/U(91+) and U(91+)/U(90+) electron-capture and ionization cross sections and equilibrium charge-state distributions are measured experimentally in mylar, Cu and Ta of varying thickness. Relativistic U(68+) ions at 437 or 962 MeV/nucleon are produced by a heavy-ion linear accelerator and synchrotron in tandem and passed through the target material into a magnetic specrometer and position-sensitive proportional counter for evaluation of charge states. The results are presented graphically and discussed. At 962 MeV/nucleon, beams containing 85 percent bare U(92+) nuclei are obtained using 150-mg/sq cm Cu or 85-mg/sq cm Ta; at 437 MeV/nucleon, 50 percent bare U(92+) nuclei are obtained with 90-mg/sq cm Cu. The techniques decribed can be applied to produce beams of bare U nuclei for acceleration to ultrarelativistic speeds or beams of few-electron U for atomic-physics experiments on quantum electrodynamics.

  18. Evaluation of electron capture gas chromatographic method for determination of methyl mercury in freezer-case seafoods.

    PubMed

    Alvarez, G H; Hight, S C; Capar, S G

    1984-01-01

    A method was recently adopted by AOAC for determination of methyl-bound mercury in canned and fresh-frozen seafood by electron capture gas chromatography. That method was applied to the analysis of commercially prepared freezer-case seafoods. None of the commercially added ingredients produced electron capture responses that interfered in the analysis for methyl mercury. Recoveries of 95.7-114% were obtained in fortification studies of methyl mercury at 0.2 and 1.0 ppm levels. The applicability of aqueous methyl mercuric chloride solution for fortification studies was demonstrated.

  19. Breathing-mode relaxation associated with electron emission and capture processes of EL 2 in GaAs

    SciTech Connect

    Samara, G.A. ); Vook, D.W.; Gibbons, J.F. )

    1992-03-09

    Analysis of the effects of hydrostatic pressure on the electronic emission and capture properties of the (0/+) and (+/++) deep levels of the {ital EL}2 defect in GaAs leads to the following conclusions: (1) Both levels move higher in the band gap with pressure; (2) relatively large inward (outward) lattice relaxations accompany electron emission (capture) from (by) these levels; and (3) the magnitudes of the relaxations agree quantitatively with theoretical results which identify {ital EL}2 as the As antisite defect. These results which emphasize the antibonding character of the orbitals which describe {ital EL}2 are consistent with this identification.

  20. Determination of phenoxy acid herbicides in water by electron-capture and microcoulometric gas chromatography

    USGS Publications Warehouse

    Goerlitz, D.F.; Lamar, William L.

    1967-01-01

    A sensitive gas chromatographic method using microcoulometric titration and electron-capture detection for the analysis of 2,4-D, silvex, 2,4,5-T, and other phenoxy acid herbicides in water is described. The herbicides are extracted from unfiltered water samples (800-1,000 ml) by use of ethyl ether ; then the herbicides are concentrated and esterilied. To allow the analyst a choice, two esterilication procedures--using either boron trifluoride-methanol or diazomethane--are evaluated. Microcoulometric gas chromatography is specific for the detection of halogenated compounds such as the phenoxy acid herbicides whereas it does not respond to nonhalogenated components. Microcoulometric gas chromatography requires care and patience. It is not convenient for rapid screening of l-liter samples that contain less than 1 microgram of the herbicide. Although electroncapture gas chromatography is less selective and more critically affected by interfering substances, it is, nevertheless, convenient and more sensitive than microcoulometric gas chromatography. Two different liquid phases are used in the gas chromatographic columns--DC-200 silicone in one column and QF-1 silicone in the other. The performance of both columns is improved by the addition of Carbowax 20M. The Gas Chrom Q support is coated with the liquid phases by the 'frontal-analysis' technique. The practical lower limits for measurement of the phenoxy acid herbicides in water primarily depend upon the sample size, interferences present, anal instrumentation used. With l-liter samples of water, the practical lower limits of measurement are 10 ppt (parts per trillion) for 2,4-D and 2 ppt for silvex and 2,4,5-T when electron-capture detection is used, and approximately 20 ppt for each herbicide when analyzed by microcoulometric-titration gas chromatography. Recoveries of the herbicides immediately after addition to unfiltered water samples averaged 92 percent for 2,4-D, 90 percent for silvex, and 98 percent for 2

  1. Cooperativity of dynamics of 18-crown-6 molecule forming one-dimensional chain in Cs2(18-crown-6)3[Ni(dmit)2]2.

    PubMed

    Ikeuchi, Satoaki; Miyazaki, Yuji; Takeda, Sadamu; Akutagawa, Tomoyuki; Nishihara, Sadafumi; Nakamura, Takayoshi; Saito, Kazuya

    2005-07-22

    Heat capacity of Cs2(18-crown-6)3[Ni(dmit)2]2 was measured by adiabatic calorimetry. A broad thermal anomaly was observed around 225 K. The entropy gain (about 52 J K(-1) mol(-1)) is much larger than that expected for twofold disordering of 18-crown-6 assumed in the previous structure analysis. The shape of thermal anomaly was qualitatively explained by a linear Ising model developed for cooperative disordering in polymers. The 18-crown-6 molecules forming a one-dimensional chain in the crystal are orientationally disordered with moderate cooperativity.

  2. Study of photon emission by electron capture during solar nuclei acceleration. 2: Delimitation of conditions for charge transfert establishment

    NASA Technical Reports Server (NTRS)

    Perez-Peraza, J.; Alvarez, M.; Gallegos, A.

    1985-01-01

    The conditions for establishment of charge transfer during acceleration of nuclei up to Fe, for typical conditions of solar flare regions T = 5 x 10 to the 3rd power to 2.5 x 10 to the 8th power degrees K were explored. Results show that such conditions are widely assorted, depending on the acceleration mechanism, the kind of projections and their velocity, the target elements, the source temperature and consequently on the degree of ionization of matter and the local charge state of the accelerated ions. Nevertheless, in spite of that assorted behavior, there are some general tendencies that can be summarized as follows. In atomic H electron capture is systematically established from thermal energies up to high energies, whatever the element and for both acceleration process. For a given element and fixed temperature (T), the probability and energy domain of electron capture and loss with Fermi are higher than with Betatron acceleration. For a given acceleration process the heavier the ion the higher the probability and the wider the energy range for electron capture and loss. For given acceleration mechanism and fixed element the importance and energy domain of capture and loss increase with T: for those reasons, the energy range of charge equilibrium (illustrated with solid lines on the next figs.) is wider with Fermi and increases with temperature and atomic number of projectiles. For the same reasons, electron loss is smaller while the lighter the element, the lower the temperature and the Betatron process, such that there are conditions for which electron loss is not allowed at low energies, but only electron capture is established.

  3. Effect of collective response on electron capture and excitation in collisions of highly charged ions with fullerenes.

    PubMed

    Kadhane, U; Misra, D; Singh, Y P; Tribedi, Lokesh C

    2003-03-07

    Projectile deexcitation Lyman x-ray emission following electron capture and K excitation has been studied in collisions of bare and Li-like sulphur ions (of energy 110 MeV) with fullerenes (C(60)/C(70)) and different gaseous targets. The intensity ratios of different Lyman x-ray lines in collisions with fullerenes are found to be substantially lower than those for the gas targets, both for capture and excitation. This has been explained in terms of a model based on "solidlike" effect, namely, wakefield induced stark mixing of the excited states populated via electron capture or K excitation: a collective phenomenon of plasmon excitation in the fullerenes under the influence of heavy, highly charged ions.

  4. DICOM for Clinical Research: PACS-Integrated Electronic Data Capture in Multi-Center Trials.

    PubMed

    Haak, Daniel; Page, Charles-E; Reinartz, Sebastian; Krüger, Thilo; Deserno, Thomas M

    2015-10-01

    Providing surrogate endpoints in clinical trials, medical imaging has become increasingly important in human-centered research. Nowadays, electronic data capture systems (EDCS) are used but binary image data is integrated insufficiently. There exists no structured way, neither to manage digital imaging and communications in medicine (DICOM) data in EDCS nor to interconnect EDCS with picture archiving and communication systems (PACS). Manual detours in the trial workflow yield errors, delays, and costs. In this paper, requirements for a DICOM-based system interconnection of EDCS and research PACS are analysed. Several workflow architectures are compared. Optimized for multi-center trials, we propose an entirely web-based solution integrating EDCS, PACS, and DICOM viewer, which has been implemented using the open source projects OpenClinica, DCM4CHEE, and Weasis, respectively. The EDCS forms the primary access point. EDCS to PACS interchange is integrated seamlessly on the data and the context levels. DICOM data is viewed directly from the electronic case report form (eCRF), while PACS-based management is hidden from the user. Data privacy is ensured by automatic de-identification and re-labelling with study identifiers. Our concept is evaluated on a variety of 13 DICOM modalities and transfer syntaxes. We have implemented the system in an ongoing investigator-initiated trial (IIT), where five centers have recruited 24 patients so far, performing decentralized computed tomography (CT) screening. Using our system, the chief radiologist is reading DICOM data directly from the eCRF. Errors and workflow processing time are reduced. Furthermore, an imaging database is built that may support future research.

  5. Kuang's Semi-Classical Formalism for Calculating Electron Capture Cross Sections and Sample Application for ENA Modeling

    NASA Technical Reports Server (NTRS)

    Barghouty, A. F.

    2013-01-01

    Accurate estimates of electron-capture cross sections at energies relevant to ENA modeling (approx. few MeV per nucleon) and for multi-electron ions must rely on detailed, but computationally expensive, quantummechanical description of the collision process. Kuang's semi-classical approach is an elegant and efficient way to arrive at these estimates. Motivated by ENA modeling efforts, we shall briefly present this approach along with sample applications and report on current progress.

  6. Strong neutrino cooling by cycles of electron capture and decay in neutron star crusts

    SciTech Connect

    Schatz, Hendrik; Gupta, Sanjib; Moeller, Peter; Beard, Mary; Brown, Edward; Deibel, A. T.; Gasques, Leandro; Hix, William Raphael; Keek, Laurens; Lau, Rita; Steiner, Andrew M; Wiescher, Michael

    2013-01-01

    The temperature in the crust of an accreting neutron star, which comprises its outermost kilometre, is set by heating from nuclear reactions at large densities, neutrino cooling and heat transport from the interior. The heated crust has been thought to affect observable phenomena at shallower depths, such as thermonuclear bursts in the accreted envelope. Here we report that cycles of electron capture and its inverse, decay, involving neutron-rich nuclei at a typical depth of about 150 metres, cool the outer neutron star crust by emitting neutrinos while also thermally decoupling the surface layers from the deeper crust. This Urca mechanism has been studied in the context of white dwarfs13 and type Ia supernovae, but hitherto was not considered in neutron stars, because previous models1, 2 computed the crust reactions using a zero-temperature approximation and assumed that only a single nuclear species was present at any given depth. The thermal decoupling means that X-ray bursts and other surface phenomena are largely independent of the strength of deep crustal heating. The unexpectedly short recurrence times, of the order of years, observed for very energetic thermonuclear superbursts are therefore not an indicator of a hot crust, but may point instead to an unknown local heating mechanism near the neutron star surface.

  7. Determination of toxaphene enantiomers by comprehensive two-dimensional gas chromatography with electron-capture detection.

    PubMed

    Bordajandi, Luisa R; Ramos, Lourdes; González, María José

    2006-09-01

    Comprehensive two-dimensional gas chromatography with micro electron-capture detection (GC x GC-microECD) has been evaluated for the enantioseparation of five chiral toxaphenes typically found in real-life samples (Parlar 26, 32, 40, 44 and 50). From the two enantioselective beta-cyclodextrin-based columns evaluated as first dimension column, BGB-176SE and BGB-172, the latter provided the best results and was further combined with three non-enantioselective columns in the second dimension: HT-8, BPX-50 and Supelcowax-10. The combination BGB-172 x BPX-50 was finally selected because it provided a complete separation among all enantiomers. A satisfactory repeatability and reproducibility of the retention times in both the first and the second dimension were observed for all target compounds (RSDs below 0.8%, n = 4). Linear responses in the tested range of 10-200 pg/microl and limits of detection in the range of 2-6 pg/microl were obtained. The repeatability and reproducibility at a concentration of 100 pg/microl, evaluated as the RSDs calculated for the enantiomeric fraction (EF), was better than 11% (n = 4) in all instances. The feasibility of the method developed for real-life analyses was illustrated by the determination of the enantiomeric ratios and concentration levels of the test compounds in four commercial fish oil samples. These results were compared to those obtained by heart-cut multidimensional gas chromatography using the same enantioselective column.

  8. Rapidly evolving faint transients from stripped-envelope electron-capture supernovae

    NASA Astrophysics Data System (ADS)

    Moriya, Takashi J.; Eldridge, J. J.

    2016-09-01

    We investigate the expected rates and bolometric light-curve properties of stripped-envelope electron-capture supernovae (ECSNe) using stellar models from the Binary Population and Spectral Synthesis code. We find that 0.8 per cent (Z = 0.020) and 1.2 per cent (Z = 0.004) of core-collapse supernovae are stripped-envelope ECSNe. Their typical ejecta masses are estimated to be about 0.3 M⊙(Z = 0.020) and 0.6 M⊙ (Z = 0.004). Assuming ECSN explosion properties from numerical explosion simulations, an explosion energy of 1.5 × 1050 erg and a 56Ni mass of 2.5 × 10-3 M⊙, we find that stripped-envelope ECSNe have a typical rise time of around 7 d (Z = 0.020) or 13 d (Z = 0.004) and peak luminosity of around 1041 ergs-1 (-13.8 mag, Z = 0.020) or 7 × 1040 erg s-1 (-13.4 mag, Z = 0.004). Their typical ejecta velocities are around 7000 km s-1 (Z = 0.020) or 5000 km s-1 (Z = 0.004). Thus, stripped-envelope ECSNe are observed as rapidly evolving faint transients with relatively small velocities. SN 2008ha-like supernovae, which are the faintest kind of SN 2002cx-like (also known as Type Iax) supernovae, may be related to stripped-envelope ECSNe.

  9. Electron capture dissociation mass spectrometric analysis of lysine-phosphorylated peptides.

    PubMed

    Kowalewska, Karolina; Stefanowicz, Piotr; Ruman, Tomasz; Fraczyk, Tomasz; Rode, Wojciech; Szewczuk, Zbigniew

    2010-12-01

    Phosphorylation of proteins is an essential signalling mechanism in eukaryotic and prokaryotic cells. Although N-phosphorylation of basic amino acid is known for its importance in biological systems, it is still poorly explored in terms of products and mechanisms. In the present study, two MS fragmentation methods, ECD (electron-capture dissociation) and CID (collision-induced dissociation), were tested as tools for analysis of N-phosphorylation of three model peptides, RKRSRAE, RKRARKE and PLSRTLSVAAKK. The peptides were phosphorylated by reaction with monopotassium phosphoramidate. The results were confirmed by 1H NMR and 31P NMR studies. The ECD method was found useful for the localization of phosphorylation sites in unstable lysine-phosphorylated peptides. Its main advantage is a significant reduction of the neutral losses related to the phosphoramidate moiety. Moreover, the results indicate that the ECD-MS may be useful for analysis of regioselectivity of the N-phosphorylation reaction. Stabilities of the obtained lysine-phosphorylated peptides under various conditions were also tested.

  10. Electron-capture delayed fission properties of the new isotope [sup 238]Bk

    SciTech Connect

    Kreek, S.A.; Hall, H.L.; Gregorich, K.E.; Henderson, R.A.; Leyba, J.D.; Czerwinski, K.R.; Kadkhodayan, B.; Neu, M.P.; Kacher, C.D.; Hamilton, T.M.; Lane, M.R.; Sylwester, E.R.; Tuerler, A.; Lee, D.M.; Nurmia, M.J.; Hoffman, D.C. )

    1994-04-01

    Electron-capture delayed fission ECDF was studied in the new isotope [sup 238]Bk produced via the [sup 241]Am(75-MeV [alpha], 7[ital n])[sup 238]Bk reaction. The half-life of the fission activity was measured to be 144[plus minus]5 seconds. The mass-yield distribution is predominantly asymmetric and the most probable preneutron emission total kinetic energy of fission is 179[plus minus]7 MeV. The ECDF mode in [sup 238]Bk was verified by an x-ray-fission coincidence experiment which indicated that the [sup 238]Cm fission lifetime is between about 10[sup [minus]15] and 10[sup [minus]9] seconds. The isotope was assigned to [sup 238]Bk through chemical separation and observation of the known 2.4-h [sup 238]Cm daughter activity. No alpha branch was observed in the decay of [sup 238]Bk. The production cross section for [sup 238]Bk is 150[plus minus]20 nb and the delayed fission probability is (4.8[plus minus]2)[times]10[sup [minus]4].

  11. Study of photon emission by electron capture during solar nuclei acceleration. 3: Photon production evaluations

    NASA Technical Reports Server (NTRS)

    Perez-Peraza, J.; Alvarez, M.; Gallegos, A.

    1985-01-01

    Lower limits of photon fluxes were evaluated from electron capture during acceleration in solar flares, because the arbitrary q sub c asterisk assumed in this work evolves very slow with velocity, probably much more slowly than the physical actual situation: in fact, more emission is expected toward the IR region. Nevertheless the authors claim to show that the factibility of sounding acceleration processes, charge evolution processes and physical parameters of the source itself, by the observational analysis of this kind of emissions. For instance, it would be interesting to search observationally, for the predicted flux and energy drift of F sub e ions interacting with the atomic 0 and F sub e of the source matter, or, even more feasible for the X-ray lines at 4.2 keV and 2.624 + 0.003 KeV from Fe and S ions in ionized Fe at T = 10 to the 7th power K respectively, the 418 + or - 2 eV and 20 + or - 4 eV lines of Fe and S in ionized Fe at 5 x 10 to the 6th power K, which are predicted from Fermi acceleration.

  12. Double electron capture of {sup 106}Cd in the TGV-2 experiment

    SciTech Connect

    Rukhadze, N. I.; Egorov, V. G.; Kovalik, A.; Rozov, S. V.; Salamatin, A. V.; Timkin, V. V.; Yakushev, E. A.; Briancon, Ch.; Brudanin, V. B.; Fajt, L.; Hodák, R.; Kouba, P.; Rukhadze, E.; Rychnovský, F.; Štekl, I.; Klimenko, A. A.; Piquemal, F.; Šimkovic, F.; Shitov, Yu. A.

    2015-10-28

    A new experimental run of searching for EC/EC decay of {sup 106}Cd was performed at the Modane underground laboratory (4800 m w.e.) using the TGV-2 spectrometer and ∼23.2 g {sup 106}Cd with enrichment of 99.57%. The limit on 2νEC/EC decay of {sup 106}Cd - T{sub 1/2}(2νEC/EC) > 3.1×10{sup 20} y, at 90% C.L was obtained from the preliminary calculation of experimental data accumulated for 7018 h of measurement. The limits on the resonance neutrino-less double electron capture decay of {sup 106}Cd were obtained from the measurement of ∼23.2 g of {sup 106}Cd with the low-background HPGe spectrometer OBELIX lasted 395 h - T{sub 1/2}(KL, 2741 keV) > 0.9×10{sup 20} y and T{sub 1/2}(KK, 2718 keV) > 1.4×10{sup 20} y at 90% C.L.

  13. Towards a Room-Temperature Spin Quantum Bus in Diamond via Electron Photoionization, Transport, and Capture

    NASA Astrophysics Data System (ADS)

    Doherty, M. W.; Meriles, C. A.; Alkauskas, A.; Fedder, H.; Sellars, M. J.; Manson, N. B.

    2016-10-01

    Diamond is a proven solid-state platform for spin-based quantum technology. The nitrogen-vacancy center in diamond has been used to realize small-scale quantum information processing and quantum sensing under ambient conditions. A major barrier in the development of large-scale quantum information processing in diamond is the connection of nitrogen-vacancy spin registers by a quantum bus at room temperature. Given that diamond is expected to be an ideal spin transport material, the coherent transport of spin directly between the spin registers offers a potential solution. Yet, there has been no demonstration of spin transport in diamond due to difficulties in achieving spin injection and detection via conventional methods. Here, we exploit detailed knowledge of the paramagnetic defects in diamond to identify novel mechanisms to photoionize, transport, and capture spin-polarized electrons in diamond at room temperature. Having identified these mechanisms, we explore how they may be combined to realize an on-chip spin quantum bus.

  14. Comparison of peptide mass mapping and electron capture dissociation as assays for histone posttranslational modifications

    NASA Astrophysics Data System (ADS)

    Zhang, Liwen; Freitas, Michael A.

    2004-05-01

    Posttranslational modifications of core histones play a critical role in the structure of chromatin and the regulation of gene activities. Improved techniques for determining these modification sites may lead to a better understanding of histone regulation at the molecular level. LC-MS peptide mass mapping was performed on pepsin, trypsin and Glu-C digests of bovine thymus H4 using a QqTOF instrument. The well established modification sites of H4 (acetylation of K8, 12, 16 and methylation of K20) were observed in addition to several recently discovered modifications including: methylation of K31, 44, 59 and acetylation of K20, 77, 79. For comparison, electron capture dissociation (ECD) was performed on intact H4 along with several peptides from enzymatic digestion. The results from the ECD experiments of histone H4 indicated the acetylation of K5, 12, 16, 31, 91 and the methylation of K20 and 59 in good agreement with the result from peptide mapping. The work is dedicated to Alan G. Marshall on his 60th birthday. His endeavors in the advancement of FT-ICR facilitated experiments reported herein.

  15. A study of resonance electron capture ionization on a quadrupole tandem mass spectrometer.

    PubMed

    Wei, J; Liu, S; Fedoreyev, S A; Voinov, V G

    2000-01-01

    Procedures that allow the realization of resonance electron capture (REC) mode on a commercial triple-quadrupole mass spectrometer, after some simple modifications, are described. REC mass spectrometry (MS) and tandem mass spectrometry (MS/MS) experiments were performed and spectra for some compounds were recorded. In particular, the charge-remote fragmentation (CRF) spectra of [M - H](-) ions of docosanoic and docosenoic acids under low-energy collisionally activated dissociation (CAD) conditions were obtained, and showed that there were no significant differences for [M - H](-) ions produced at different resonances (i.e. for [M - H](-) ions with different structures). This observation was explained on the basis of results obtained from deuterium-labeled fatty acids, which showed that different CRF ions (but with the same m/z value in the absence of labels) could be produced by different mechanisms, and all of them were obviously realized under CAD conditions that made spectra practically indistinguishable. The other example, which compared the REC-MS/MS spectrum of [M - H](-) ions and EI-MS/MS spectrum of M(+.) ions of daidzein, demonstrated the potential of the REC-MS/MS technique for more complex structure elucidation.

  16. New search for double electron capture in {sup 106}Cd decay with the TGV-2 spectrometer

    SciTech Connect

    Briançon, Ch.; Brudanin, V. B.; Egorov, V. G.; Jose, J. M.; Klimenko, A. A.; Kovalik, A.; Rosov, S. V.; Rukhadze, E. N.; Rukhadze, N. I. Salamatin, A. V.; Timkin, V. V.; Fajt, L.; Hodak, R.; Šimkovic, F.; Shitov, Yu. A.; Špavorova, M.; Štekl, I.; Yakushev, E. A.

    2015-09-15

    A new experiment devoted to searches for double electron capture in {sup 106}Cd decay is being performed at the Modane underground laboratory (4800 mwe) with the 32-detector TGV-2 spectrometer. The limit T{sub 1/2}(2νEC/EC) > 2.0×10{sup 20} yr at a 90%confidence level (C.L.) was obtained from a preliminary analysis of data obtained over 2250 h of measurements with about 23.2 g sample enriched in the isotope {sup 106}Cd to 99.57%. The limits T{sub 1/2}(KL, 2741 keV) > 0.9 × 10{sup 20} yr and T{sub 1/2}(KK, 2718 keV) ≫ 1.4 × 10{sup 20} yr at a 90% C.L. on the neutrinoless decay of {sup 106}Cd were obtained from measurements performed with the Obelix low-background spectrometer from high-purity germanium (HPGe spectrometer) for a sample of mass about 23.2 g enriched in the isotope {sup 106}Cd.

  17. Electron-capture delayed fission properties of neutron-deficient einsteinium nuclei

    SciTech Connect

    Shaughnessy, Dawn A.

    2000-01-01

    Electron-capture delayed fission (ECDF) properties of neutron-deficient einsteinium isotopes were investigated using a combination of chemical separations and on-line radiation detection methods. 242Es was produced via the 233U(14N,5n)242Es reaction at a beam energy of 87 MeV (on target) in the lab system, and was found to decay with a half-life of 11 ± 3 seconds. The ECDF of 242Es showed a highly asymmetric mass distribution with an average pre-neutron emission total kinetic energy (TKE) of 183 ± 18 MeV. The probability of delayed fission (PDF) was measured to be 0.006 ± 0.002. In conjunction with this experiment, the excitation functions of the 233U(14N,xn)247-xEs and 233U(15N,xn)248-xEs reactions were measured for 243Es, 244Es and 245Es at projectile energies between 80 MeV and 100 MeV.

  18. Single-electron capture by low-energy Ar{sup q+} ions from He and Ne

    SciTech Connect

    Akgungor, K.; Kamber, E.Y.; Ferguson, S.M.

    1996-05-01

    State selective differential and total cross sections for single-electron capture processes by low-energy Ar{sup q+} (q = 4 - 8) ions from He and Ne targets have been studied experimentally at impact energies between 30 and 100 qeV, and laboratory scattering angles between 0{degrees} and 5{degrees}, by means of translational energy-gain spectroscopy. The ions were produced in a recoil ion source, pumped by a fast beam from the WMU Van de Graaff accelerator. The dominant processes are found to be single-electron capture (SEC) into the excited states of the projectile products. In additional to SEC, transfer excitation processes are also observed. It is found that the population of the dominant reaction channels is consistent with the predictions of the classical over-barrier model. The multichannel Landau-Zener (MCLZ) model has been used to obtain cross sections for capture into individual states. The MCLZ calculations are shown to be in good agreement with the measured energy-gain spectra. Total cross sections for single-electron capture are compared to the single-crossing Landau-Zener model, classical over-barrier model and available measurements. The general features of the angular distributions are discussed in terms of a semiclassical curve-crossing model.

  19. Determination of deep level capture cross sections in wide band-gap semiconductors by means of an electron beam

    NASA Technical Reports Server (NTRS)

    Von Roos, O.

    1980-01-01

    The paper presents a general theory for the determination of the short circuit current generated by a sinusoidally amplitude-modulated electron beam in the presence of recombination centers with an arbitrary number of charge states. It is shown that a measurement of the coherent phase shift with respect to the incident beam as a function of the modulation frequency of the beam ascertains the magnitudes of electron and hole capture cross sections. The surface exposed to the electron beam must have a negligible surface recombination velocity for the measurements to be unambiguous.

  20. Electron-capture supernovae of super-asymptotic giant branch stars and the Crab supernova 1054

    NASA Astrophysics Data System (ADS)

    Nomoto, Ken'ichi; Tominaga, Nozomu; Blinnikov, Sergei I.

    2014-05-01

    An electron-capture supernova (ECSN) is a core-collapse supernova explosion of a super-asymptotic giant branch (SAGB) star with a main-sequence mass MMs ˜ 7 - 9.5M⊙. The explosion takes place in accordance with core bounce and subsequent neutrino heating and is a unique example successfully produced by first-principle simulations. This allows us to derive a first self-consistent multicolor light curves of a core-collapse supernova. Adopting the explosion properties derived by the first-principle simulation, i.e., the low explosion energy of 1.5 × 1050 erg and the small 56Ni mass of 2.5 × 10-3 M⊙, we perform a multigroup radiation hydrodynamics calculation of ECSNe and present multicolor light curves of ECSNe of SAGB stars with various envelope mass and hydrogen abundance. We demonstrate that a shock breakout has peak luminosity of L ˜ 2 × 1044 erg s-1 and can evaporate circumstellar dust up to R ˜ 1017 cm for a case of carbon dust, that plateau luminosity and plateau duration of ECSNe are L ˜ 1042 erg s-1 and t ˜ 60 - 100 days, respectively, and that a plateau is followed by a tail with a luminosity drop by ˜ 4 mag. The ECSN shows a bright and short plateau that is as bright as typical Type II plateau supernovae, and a faint tail that might be influenced by spin-down luminosity of a newborn pulsar. Furthermore, the theoretical models are compared with ECSN candidates: SN 1054 and SN 2008S. We find that SN 1054 shares the characteristics of the ECSNe. For SN 2008S, we find that its faint plateau requires a ECSN model with a significantly low explosion energy of E ˜ 1048 erg.

  1. Electron-capture supernovae of super-asymptotic giant branch stars and the Crab supernova 1054

    SciTech Connect

    Nomoto, Ken'ichi; Tominaga, Nozomu; Blinnikov, Sergei I.

    2014-05-02

    An electron-capture supernova (ECSN) is a core-collapse supernova explosion of a super-asymptotic giant branch (SAGB) star with a main-sequence mass M{sub Ms} ∼ 7 - 9.5M{sub ⊙}. The explosion takes place in accordance with core bounce and subsequent neutrino heating and is a unique example successfully produced by first-principle simulations. This allows us to derive a first self-consistent multicolor light curves of a core-collapse supernova. Adopting the explosion properties derived by the first-principle simulation, i.e., the low explosion energy of 1.5 × 10{sup 50} erg and the small {sup 56}Ni mass of 2.5 × 10{sup −3} M{sub ⊙}, we perform a multigroup radiation hydrodynamics calculation of ECSNe and present multicolor light curves of ECSNe of SAGB stars with various envelope mass and hydrogen abundance. We demonstrate that a shock breakout has peak luminosity of L ∼ 2 × 10{sup 44} erg s{sup −1} and can evaporate circumstellar dust up to R ∼ 10{sup 17} cm for a case of carbon dust, that plateau luminosity and plateau duration of ECSNe are L ∼ 10{sup 42} erg s{sup −1} and {sup t} ∼ 60 - 100 days, respectively, and that a plateau is followed by a tail with a luminosity drop by ∼ 4 mag. The ECSN shows a bright and short plateau that is as bright as typical Type II plateau supernovae, and a faint tail that might be influenced by spin-down luminosity of a newborn pulsar. Furthermore, the theoretical models are compared with ECSN candidates: SN 1054 and SN 2008S. We find that SN 1054 shares the characteristics of the ECSNe. For SN 2008S, we find that its faint plateau requires a ECSN model with a significantly low explosion energy of E ∼ 10{sup 48} erg.

  2. Double resonant enhancement in the neutrinoless double-electron capture of 190Pt

    NASA Astrophysics Data System (ADS)

    Eibach, M.; Bollen, G.; Gulyuz, K.; Izzo, C.; Redshaw, M.; Ringle, R.; Sandler, R.; Valverde, A. A.

    2016-07-01

    Background: The observation of neutrinoless double-β transitions would indicate physics beyond the standard model as the lepton number conservation is violated. For a complete degeneracy in the energy of the initial and final states, the neutrinoless double-electron capture is resonantly enhanced. This shortens the half-life to similar orders of magnitude as the neutrinoless double-β decay and expands the set of nuclei for the search of neutrinoless double-β transitions as the observation of either process would be equally likely. Purpose: To clearly identify transitions that are resonantly enhanced, among other parameters the total energy of the decay, Qɛ ɛ, needs to be measured very precisely. Of the 12 initially identified candidates, the last remaining decay without a precise Qɛ ɛ was 190Pt(0 ν ɛ ɛ )190Os . Method: The Qɛ ɛ value was determined with the Penning trap mass spectrometer LEBIT by measuring the ratio of the cyclotron frequencies of +190Pt and +190Os in a 9.4-T superconducting magnet. Result: The Qɛ ɛ value was determined to be 1401.57(47) keV with an uncertainty reduction of an order of magnitude compared to its previously known value. The absolute value is shifted by 17.17(623) keV relative to the previously accepted one. Furthermore, the mass value of 190Pt was found to be shifted by more than three standard deviations. In addition we improved the mass values for Os,190186 and 194Pt. Conclusion: Transitions to the two nuclear excited states of 190Os with 1326.9(5) and 1387.00(2) keV energy were identified to be resonantly enhanced within a 1 σ uncertainty. The significantly reduced uncertainty of Qɛ ɛ confirmed the potential for a resonantly enhanced transition.

  3. Atypical behavior in the electron capture induced dissociation of biologically relevant transition metal ion complexes of the peptide hormone oxytocin

    NASA Astrophysics Data System (ADS)

    Kleinnijenhuis, Anne J.; Mihalca, Romulus; Heeren, Ron M. A.; Heck, Albert J. R.

    2006-07-01

    Doubly protonated ions of the disulfide bond containing nonapeptide hormone oxytocin and oxytocin complexes with different transition metal ions, that have biological relevance under physiological conditions, were subjected to electron capture dissociation (ECD) to probe their structural features in the gas phase. Although, all the ECD spectra were strikingly different, typical ECD behavior was observed for complexes of the nonapeptide hormone oxytocin with Ni2+, Co2+ and Zn2+, i.e., abundant c/z' and a'/y backbone cleavages and ECD characteristic S-S and S-C bond cleavages were observed. We propose that, although in the oxytocin-transition metal ion complexes the metal ions serve as the main initial capture site, the captured electron is transferred to other sites in the complex to form a hydrogen radical, which drives the subsequent typical ECD fragmentations. The complex of oxytocin with Cu2+ displayed noticeably different ECD behavior. The fragment ions were similar to fragment ions typically observed with low-energy collision induced dissociation (CID). We propose that the electrons captured by the oxytocin-Cu2+ complex might be favorably involved in reducing the Cu2+ metal ion to Cu+. Subsequent energy redistribution would explain the observed low-energy CID-type fragmentations. Electron capture resulted also in quite different specific cleavage sites for the complexes of oxytocin with Ni2+, Co2+ and Zn2+. This is an indication for structural differences in these complexes possibly linked to their significantly different biological effects on oxytocin-receptor binding, and suggests that ECD may be used to study subtle structural differences in transition metal ion-peptide complexes.

  4. Development of an electronic research permissions management system to enhance informed consents and capture research authorizations data.

    PubMed

    Obeid, Jihad S; Gerken, Katherine; Madathil, Kapil Chalil; Rugg, Daniel; Alstad, Colin E; Fryar, Katrina; Alexander, Randall; Gramopadhye, Anand K; Moskowitz, Jay; Sanderson, Iain C

    2013-01-01

    Informed consents are a critical and essential component of the clinical research process. Currently, most consents and research privacy authorizations are being captured on paper. In this paper we describe a novel method of capturing this information electronically. The objective is to allow easier tracking of research participants' intent for current and future research involvement, enhance consent comprehension and facilitate the research workflow. After multidisciplinary analysis in key hospital registration areas and research participant enrollment, an open source software product was designed to capture this data through a user-friendly touch screen interface. The data may then be fed into a clinical data warehouse for use in cohort discovery or consent tracking. Despite ethical, legal and informatics challenges in clinical and research environments, we propose that this technology opens new avenues for significantly enhancing the consent process and positively impacting recruitment.

  5. Development of an Electronic Research Permissions Management System to Enhance Informed Consents and Capture Research Authorizations Data

    PubMed Central

    Obeid, Jihad S.; Gerken, Katherine; Madathil, Kapil Chalil; Rugg, Daniel; Alstad, Colin E.; Fryar, Katrina; Alexander, Randall; Gramopadhye, Anand K.; Moskowitz, Jay; Sanderson, Iain C.

    Informed consents are a critical and essential component of the clinical research process. Currently, most consents and research privacy authorizations are being captured on paper. In this paper we describe a novel method of capturing this information electronically. The objective is to allow easier tracking of research participants’ intent for current and future research involvement, enhance consent comprehension and facilitate the research workflow. After multidisciplinary analysis in key hospital registration areas and research participant enrollment, an open source software product was designed to capture this data through a user-friendly touch screen interface. The data may then be fed into a clinical data warehouse for use in cohort discovery or consent tracking. Despite ethical, legal and informatics challenges in clinical and research environments, we propose that this technology opens new avenues for significantly enhancing the consent process and positively impacting recruitment. PMID:24303263

  6. Modification of magicity toward the dripline and its impact on electron-capture rates for stellar core collapse

    NASA Astrophysics Data System (ADS)

    Raduta, Ad. R.; Gulminelli, F.; Oertel, M.

    2016-02-01

    The importance of microphysical inputs from laboratory nuclear experiments and theoretical nuclear structure calculations in the understanding of core-collapse dynamics and the subsequent supernova explosion is largely recognized in the recent literature. In this work, we analyze the impact of the masses of very neutron-rich nuclei on the matter composition during collapse and the corresponding electron-capture rate. To this end, we introduce an empirical modification of the popular Duflo-Zuker mass model to account for possible shell quenching far from stability. We study the effect of this quenching on the average electron-capture rate. We show that the pre-eminence of the closed shells with N =50 and N =82 in the collapse dynamics is considerably decreased if the shell gaps are reduced in the region of 78Ni and beyond. As a consequence, local modifications of the overall electron-capture rate of up to 30% can be expected, depending on the strength of magicity quenching. This finding has potentially important consequences on the entropy generation, the neutrino emissivity, and the mass of the core at bounce. Our work underlines the importance of new experimental measurements in this region of the nuclear chart, the most crucial information being the nuclear mass and the Gamow-Teller strength. Reliable microscopic calculations of the associated elementary rate, in a wide range of temperatures and electron densities, optimized on these new empirical information, will be additionally needed to get quantitative predictions of the collapse dynamics.

  7. Comparative analysis of the effects of electron and hole capture on the power characteristics of a semiconductor quantum-well laser

    SciTech Connect

    Sokolova, Z. N. Pikhtin, N. A.; Tarasov, I. S.; Asryan, L. V.

    2015-11-15

    The operating characteristics of a semiconductor quantum-well laser calculated using three models are compared. These models are (i) a model not taking into account differences between the electron and hole parameters and using the electron parameters for both types of charge carriers; (ii) a model, which does not take into account differences between the electron and hole parameters and uses the hole parameters for both types of charge carriers; and (iii) a model taking into account the asymmetry between the electron and hole parameters. It is shown that, at the same velocity of electron and hole capture into an unoccupied quantum well, the laser characteristics, obtained using the three models, differ considerably. These differences are due to a difference between the filling of the electron and hole subbands in a quantum well. The electron subband is more occupied than the hole subband. As a result, at the same velocities of electron and hole capture into an empty quantum well, the effective electron-capture velocity is lower than the effective hole-capture velocity. Specifically, it is shown that for the laser structure studied the hole-capture velocity of 5 × 10{sup 5} cm/s into an empty quantum well and the corresponding electron-capture velocity of 3 × 10{sup 6} cm/s into an empty quantum well describe the rapid capture of these carriers, at which the light–current characteristic of the laser remains virtually linear up to high pump-current densities. However, an electron-capture velocity of 5 × 10{sup 5} cm/s and a corresponding hole-capture velocity of 8.4 × 10{sup 4} cm/s describe the slow capture of these carriers, causing significant sublinearity in the light–current characteristic.

  8. A data capture system for outcomes studies that integrates with electronic health records: development and potential uses.

    PubMed

    Yamamoto, Keiichi; Matsumoto, Shigemi; Tada, Harue; Yanagihara, Kazuhiro; Teramukai, Satoshi; Takemura, Tadamasa; Fukushima, Masanori

    2008-10-01

    In conventional clinical studies, the costs of data management for quality control tend to be high and collecting paper-based case report forms (CRFs) tends to be burdensome, because paper-based CRFs must be developed and filled out for each clinical study protocol. Use of electronic health records for this purpose could result in reductions in cost and improvements in data quality in clinical studies. The purpose of this study was to develop a data capture system for observational cancer clinical studies (i.e. outcomes studies) that would integrate with an electronic health records system, to enable evaluation of patient prognosis, prognostic factors, outcomes and drug safety. At the Outpatient Oncology Unit of Kyoto University Hospital, we developed a data capture system that includes a cancer clinical database system and a data warehouse for outcomes studies. We expect that our new system will reduce the costs of data management and analysis and improve the quality of data in clinical studies.

  9. Lepton-violating β-β-, β+β+ decays, (e -, e +) conversion and double electron capture in gauge theories

    NASA Astrophysics Data System (ADS)

    Vergados, J. D.

    1983-05-01

    The lepton violating processes β-β-, β+β+, (e -, e +) and double electron capture have been investigated in the context of modern gauge theories. Mechanisms involving light or heavy intermediate Majorana neutrinos, with or without right-handed currents, as well as Higgs particles, have been studied. The lepton-violating emission of light bosons, recently proposed by Georgi, Glashow and Nussinov, has also been analyzed. From the analysis of the 48Ca → 48Ti data the following limits emerge: ∣ < m v > ∣ < 80 eV, m N > (2-20) × 10 3GeV, m W R > 400 GeVand g v eoverlinevex 0 < 5 × 10 -3. The above limits are then used to predict the lifetimes for β+β+, (e -, e +) and double electron capture in the A = 58, 92 and 96 systems employing realistic nuclear models.

  10. Cross sections for electron capture in H{sup +}-Li(2p{sigma},{pi}{sup {+-}}) collisions

    SciTech Connect

    Liu, L.; Liu, C. H.; Wang, J. G.; Janev, R. K.

    2011-09-15

    State-selective and total single-electron-capture cross sections in collisions of H{sup +} with the excited Li{sup *}(2p) atom have been investigated by using the full quantum-mechanical molecular orbital close-coupling (QMOCC) method in the energy range 0.001-3 keV/u and by the two-center atomic orbital close-coupling (TC-AOCC) method in the energy range 0.1-100 keV/u. The present results are also compared with data from other sources when available. It is found that the total and partial electron-capture cross sections are sensitive to the initial p-state charge cloud alignment, particularly in the low-energy region.

  11. Excited states in 168Yb from electron-capture decay of 168Lum (T1/2=6.7 min)

    NASA Astrophysics Data System (ADS)

    Barci, V.; Ardisson, G.; Trubert, D.; Hussonnois, M.

    1999-08-01

    The electron-capture decay of the 168Lum (T1/2=6.7 min, Jπ=3+) isomer was studied with high purity sources, obtained by using a new radiochemical method consisting of fast continous on-line separation of reaction products. A complex spectrum composed of about 200 γ rays was observed. From these, 162 transitions were assigned to a level scheme of 39 excited levels of 168Yb, primarily by γ-γ coincidence spectroscopic measurements. About 60 transitions were placed for the first time and >90% of the decay intensity was clearly identified. The structure of the levels directly fed by the electron-capture decay was reviewed as particle-hole excitations of the core.

  12. Scaling of cross sections for K-electron capture by high-energy protons and alpha-particles from the multielectron atoms

    NASA Technical Reports Server (NTRS)

    Omidvar, K.

    1979-01-01

    Electron capture by protons from H, He, and the K shell of Ar, and electron capture by alpha particles from He are considered. Using the experimental data, a function of the capture cross section is formed. It is shown that when this function is plotted versus the inverse of the collision energies, at high energies a straight line is obtained. At lower energies the line is concave up or down, depending on the charge of the projectile and/or the effective charge and the ionization potential of the electron that is being captured. The plot can be used to predict cross sections where experimental data are not available, and as a guide in future experiments. High-energy scaling formulas for K-electron capture by low-charge projectiles are given.

  13. Current oscillations in semi-insulating GaAs associated with field-enhanced capture of electrons by the major deep donor EL2

    NASA Technical Reports Server (NTRS)

    Kaminska, M.; Parsey, J. M.; Lagowski, J.; Gatos, H. C.

    1982-01-01

    Current oscillations thermally activated by the release of electrons from deep levels in undoped semiinsulating GaAs were observed for the first time. They were attributed to electric field-enhanced capture of electrons by the dominant deep donor EL2 (antisite AsGa defect). This enhanced capture is due to the configurational energy barrier of EL2, which is readily penetrated by hot electrons.

  14. Complete voltage recovery in quantum dot solar cells due to suppression of electron capture.

    PubMed

    Varghese, A; Yakimov, M; Tokranov, V; Mitin, V; Sablon, K; Sergeev, A; Oktyabrsky, S

    2016-04-07

    Extensive investigations in recent years have shown that addition of quantum dots (QDs) to a single-junction solar cell decreases the open circuit voltage, VOC, with respect to the reference cell without QDs. Despite numerous efforts, the complete voltage recovery in QD cells has been demonstrated only at low temperatures. To minimize the VOC reduction, we propose and investigate a new approach that combines nanoscale engineering of the band structure and the potential profile. Our studies of GaAs solar cells with various InAs QD media demonstrate that the main cause of the VOC reduction is the fast capture of photoelectrons from the GaAs conduction band (CB) to the localized states in QDs. As the photoelectron capture into QDs is mainly realized via the wetting layers (WLs), we substantially reduced the WLs using two monolayer AlAs capping of QDs. In the structures with reduced WLs, the direct CB-to-QD capture is further suppressed due to charging of QDs via doping of the interdot space. The QD devices with suppressed photoelectron capture show the same VOC as the GaAs reference cell together with some improvements in the short circuit current.

  15. Capturing enveloped viruses on affinity grids for downstream cryo-electron microscopy applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Electron microscopy cryo-electron microscopy and cryo-electron tomography are essential techniques used for characterizing basic virus morphology and determining the three-dimensional structure of viruses. Enveloped viruses, which contain an outer lipoprotein coat, constitute the largest group of pa...

  16. Theoretical studies on the electron capture properties of the H2SO4...HOO˙ complex and its implications as an alternative source of HOOH.

    PubMed

    Li, Ping; Ma, Zhiying; Wang, Weihua; Song, Rui; Zhai, Yazhou; Bi, Siwei; Sun, Haitao; Bu, Yuxiang

    2011-04-07

    To better understand the potential role of sulfuric acid aerosols in the atmosphere, the electron capture properties of the H(2)SO(4)...HOO˙ complex have been systematically investigated by employing the MP2 and B3LYP methods in combination with the atoms in molecules (AIM) theory, energy decomposition analysis (EDA), and ab initio molecular dynamics. It was found that the electron capture process is a favorable reaction thermodynamically and kinetically. The excess electron can be captured by the HOO˙ fragment initially, and then the proton of the H(2)SO(4) fragment associated with the intermolecular H-bonds is transferred to the HOO˙ fragment without any activation barriers, resulting in the formation of the HOOH species directly. Therefore, the electron capture process of the H(2)SO(4)...HOO˙ complex provides an alternative source of HOOH in the atmosphere. The nature of the coupling interactions in the electron capture products are clarified, and the most stable anionic complex is also determined. Additionally, the influences of the adjacent water molecules on the electron capture properties are investigated, as well as the distinct IR features of the most stable electron capture product.

  17. Electron capture and excitation in collisions of O+ ( 4S , 2D , 2P ) with H2 molecules

    NASA Astrophysics Data System (ADS)

    Pichl, Lukáš; Li, Yan; Liebermann, Heinz-Peter; Buenker, Robert J.; Kimura, Mineo

    2004-06-01

    Using an electronic-state close-coupling method, we treated the electron capture and excitation processes of O+ ions both in ground state O+ ( 4S ) and metastable states O+* ( 2D ) and O+* ( 2P ) in collisions with the H2 molecule. In the ground-state projectile energy region considered (from 50 eV/amu to 10 keV/amu ), the experimental data vary by orders of magnitude: our results smoothly connect to the data by FleschNg, J. Chem. Phys.9419912372 and Xuet al., J. Phys. B2319901235 at low energy and agree with Phaneufet al., Phys. Rev. A171978534 in the high-energy region. The present values differ from Sieglaffet al., Phys. Rev. A5919993538 and Nuttet al., J. Phys. B121979L157, especially in the energy region below 1 keV/amu . We provide the first calculated state-resolved cross sections of electron capture and target-projectile electronic excitations for the O+ ( 4S , 2D , 2P )- H2 collision system.

  18. The feasibility of using 'bring your own device' (BYOD) technology for electronic data capture in multicentre medical audit and research.

    PubMed

    Faulds, M C; Bauchmuller, K; Miller, D; Rosser, J H; Shuker, K; Wrench, I; Wilson, P; Mills, G H

    2016-01-01

    Large-scale audit and research projects demand robust, efficient systems for accurate data collection, handling and analysis. We utilised a multiplatform 'bring your own device' (BYOD) electronic data collection app to capture observational audit data on theatre efficiency across seven hospital Trusts in South Yorkshire in June-August 2013. None of the participating hospitals had a dedicated information governance policy for bring your own device. Data were collected by 17 investigators for 392 individual theatre lists, capturing 14,148 individual data points, 12, 852 (91%) of which were transmitted to a central database on the day of collection without any loss of data. BYOD technology enabled accurate collection of a large volume of secure data across multiple NHS organisations over a short period of time. Bring your own device technology provides a method for collecting real-time audit, research and quality improvement data within healthcare systems without compromising patient data protection.

  19. State-selective electron capture in {sup 3}He{sup 2+} + He collisions at intermediate impact energies

    SciTech Connect

    Alessi, M.; Otranto, S.; Focke, P.

    2011-01-15

    In this work we have measured single-electron capture in collisions of {sup 3}He{sup 2+} projectiles incident on a helium target for energies of 13.3-100 keV/amu with the cold-target recoil-ion momentum spectroscopy setup implemented at the Centro Atomico Bariloche. State-selective single-capture cross sections were measured as a function of the impact energy. They were found to agree with previous existing data from the Frankfurt group, starting at the impact energy of 60 keV/amu; as well as with recent data, at 7.5 keV/amu, from the Lanzhou group. The present experimental results are also contrasted to the classical trajectory Monte Carlo method with dynamical screening.

  20. Breathing mode lattice relaxation associated with carrier emission and capture by deep electronic levels in silicon

    SciTech Connect

    Samara, G.A.

    1987-01-01

    The breathing mode (volume) lattice relaxations associated with carrier emission and capture are evaluated for a variety of deep levels in silicon using a recently proposed method based on high pressure measurement of the emission rates and capture cross sections. Included are (1) the vacancy-like acceptor levels associated with the oxygen-vacancy pair (or A-center) and the gold, platinum and palladium impurities, (2) the chalcogenide donors in their singly- and doubly-charged states and (3) a number of 3d transition metal donors. The signs and magnitudes (which range from approx.0 to 5A/sup 3//emitted carrier) of these relaxations are discussed in terms of models for the impurities and defects responsible for the associated levels. The results on the chalcogenides are compared with recent theoretical calculations. 8 refs., 1 tab.

  1. Experimental investigations of electron capture from atomic hydrogen and deuterium by alpha particles

    SciTech Connect

    Not Available

    1990-01-01

    We have undertaken a program at the University of Missouri-Rolla to experimentally determine cross sections for ion-atom collisions of interest in fusion reactor development. During the last grant period, we have made measurements of total and singly-differential cross sections for the alpha double-capture reaction. He{sup ++} + He(ls{sup 2}) {yields} He({Sigma}n,{ell}) + He{sup ++}. Collisions of this type have been discussed as a basis for diagnostics in which alphas are neutralized in a single collisions either by a HeI beam or by the ablative cloud from mechanically introduced impurity pellets. We are now finishing measurements of cross sections for the alpha single capture reaction He{sup ++} + He(1s{sup 2}) {yields} He{sup +}(n) + He{sup +}(1s), and propose to study He{sup ++} + H(1s) {yields} He{sup +}(n) + H{sup +} during next year. Accurate knowledge of these cross sections is fundamental for modeling of neutral-hydrogen beam penetration in fusion plasmas as well as for spectroscopic diagnostics of alpha densities and velocity distributions, especially for the case of capture into the n = 4 state of the projectile He{sup +}. Our measurements are made using a unique collision spectrometer discussed in this paper.

  2. Examination of the calorimetric spectrum to determine the neutrino mass in low-energy electron capture decay

    NASA Astrophysics Data System (ADS)

    Robertson, R. G. H.

    2015-03-01

    Background: The standard kinematic method for determining neutrino mass from the β decay of tritium or other isotope is to measure the shape of the electron spectrum near the endpoint. A similar distortion of the "visible energy" remaining after electron capture is caused by neutrino mass. There has been a resurgence of interest in using this method with 163Ho, driven by technological advances in microcalorimetry. Recent theoretical analyses offer reassurance that there are no significant theoretical uncertainties. Purpose: The theoretical analyses consider only single vacancy states in the daughter 163Dy atom. It is necessary to consider configurations with more than one vacancy that can be populated owing to the change in nuclear charge. Method: The shakeup and shake-off theory of Carlson and Nestor is used as a basis for estimating the population of double-vacancy states. Results: A spectrum of satellites associated with each primary vacancy created by electron capture is presented. Conclusions: The theory of the calorimetric spectrum is more complicated than has been described heretofore. There are numerous shakeup and shake-off satellites present across the spectrum, and some may be very near the endpoint. The spectrum shape is presently not understood well enough to permit a sensitive determination of the neutrino mass in this way.

  3. Capturing Structural Dynamics in Crystalline Silicon Using Chirped Electrons from a Laser Wakefield Accelerator.

    PubMed

    He, Z-H; Beaurepaire, B; Nees, J A; Gallé, G; Scott, S A; Pérez, J R Sánchez; Lagally, M G; Krushelnick, K; Thomas, A G R; Faure, J

    2016-11-08

    Recent progress in laser wakefield acceleration has led to the emergence of a new generation of electron and X-ray sources that may have enormous benefits for ultrafast science. These novel sources promise to become indispensable tools for the investigation of structural dynamics on the femtosecond time scale, with spatial resolution on the atomic scale. Here, we demonstrate the use of laser-wakefield-accelerated electron bunches for time-resolved electron diffraction measurements of the structural dynamics of single-crystal silicon nano-membranes pumped by an ultrafast laser pulse. In our proof-of-concept study, we resolve the silicon lattice dynamics on a picosecond time scale by deflecting the momentum-time correlated electrons in the diffraction peaks with a static magnetic field to obtain the time-dependent diffraction efficiency. Further improvements may lead to femtosecond temporal resolution, with negligible pump-probe jitter being possible with future laser-wakefield-accelerator ultrafast-electron-diffraction schemes.

  4. Capturing Structural Dynamics in Crystalline Silicon Using Chirped Electrons from a Laser Wakefield Accelerator

    NASA Astrophysics Data System (ADS)

    He, Z.-H.; Beaurepaire, B.; Nees, J. A.; Gallé, G.; Scott, S. A.; Pérez, J. R. Sánchez; Lagally, M. G.; Krushelnick, K.; Thomas, A. G. R.; Faure, J.

    2016-11-01

    Recent progress in laser wakefield acceleration has led to the emergence of a new generation of electron and X-ray sources that may have enormous benefits for ultrafast science. These novel sources promise to become indispensable tools for the investigation of structural dynamics on the femtosecond time scale, with spatial resolution on the atomic scale. Here, we demonstrate the use of laser-wakefield-accelerated electron bunches for time-resolved electron diffraction measurements of the structural dynamics of single-crystal silicon nano-membranes pumped by an ultrafast laser pulse. In our proof-of-concept study, we resolve the silicon lattice dynamics on a picosecond time scale by deflecting the momentum-time correlated electrons in the diffraction peaks with a static magnetic field to obtain the time-dependent diffraction efficiency. Further improvements may lead to femtosecond temporal resolution, with negligible pump-probe jitter being possible with future laser-wakefield-accelerator ultrafast-electron-diffraction schemes.

  5. The Use of Research Electronic Data Capture (REDCap) Software to Create a Database of Librarian-Mediated Literature Searches

    PubMed Central

    LYON, JENNIFER A.; GARCIA-MILIAN, ROLANDO; NORTON, HANNAH F.; TENNANT, MICHELE R.

    2015-01-01

    Expert-mediated literature searching, a keystone service in biomedical librarianship, would benefit significantly from regular methodical review. This paper describes the novel use of Research Electronic Data Capture (REDCap) software to create a database of literature searches conducted at a large academic health sciences library. An archive of paper search requests was entered into REDCap, and librarians now prospectively enter records for current searches. Having search data readily available allows librarians to reuse search strategies and track their workload. In aggregate, this data can help guide practice and determine priorities by identifying users’ needs, tracking librarian effort, and focusing librarians’ continuing education. PMID:25023012

  6. Characterization of the iron-binding properties of pyoverdine using electron-capture dissociation-tandem mass spectrometry.

    PubMed

    Qi, Yulin; Hayen, Heiko; Volmer, Dietrich A

    2016-02-01

    Pyoverdines (PVD) are a group of siderophores produced by fluorescent Pseudomonads. Identification of PVD variants mostly relies on liquid chromatography-tandem mass spectrometry (LC-MS/MS) using collision-induced dissociation (CID). Here, both CID and the novel dissociation technique electron-capture dissociation (ECD) were applied to characterize PVD succinamide and its Fe(III)-chelated complex. The results clearly showed that ECD produced diagnostic side chain fragmentation of the PVD peptide chain and preserved the labile Fe(III) binding to the chromophore in contrast to CID. The ECD technique is therefore expected to support the understanding of strain-specific Fe(III) transport processes of PVDs.

  7. Determination of chloramphenicol residue in fish and shrimp tissues by gas chromatography with a microcell electron capture detector.

    PubMed

    Ding, Shuangyang; Shen, Jianzhong; Zhang, Suxia; Jiang, Haiyang; Sun, Zhiwen

    2005-01-01

    A gas chromatography method with microcell electron capture detection was developed for the determination of chloramphenicol residue in fish and shrimp muscle tissues. The tissue samples were extracted with ethyl acetate, defatted with hexane, and derivatized with Sylon BFT [N,O-bis (trimethylsilyl) trifluoroacetamide-trimethylchlorosilane (99 + 1)]. The limit of detection was 0.04 ng/g and the limit of quantitation 0.1 ng/g. Average recoveries were 70.8-90.8% for fish and 69.9-86.3% for shrimp, respectively. The method was validated for the determination of practical samples.

  8. Electron-capture branch of {sup 100}Tc and tests of nuclear wave functions for double-{beta} decays.

    SciTech Connect

    Sjue, S. K. L.; Melconian, D.; Garcia, A.; Ahmad, I.; Algora, A.; Aysto, J.; Elomaa, V.-V.; Eronen, T.; Hakala, J.; Hoedl, S.; Kankainen, A.; Kessler, T.; Moore, I. D.; Naabe, F.; Penttila, H.; Rahaman, S.; Saastamoinen, A.; Swanson, H. E.; Weber, C.; Triambak, S.; Deryckx, K.; Physics; Univ. of Washington; Texas A&M Univ.; Univ. of Valencia; Hungarian Academy of Sciences; Univ. of Jyvaskyla; Univ. of Michigan

    2008-12-30

    We present a measurement of the electron-capture branch of {sup 100}Tc. Our value, B(EC) = (2.6 {+-} 0.4) x 10{sup -5}, implies that the {sup 100}Mo neutrino absorption cross section to the ground state of {sup 100}Tc is roughly 50% larger than previously thought. Disagreement between the experimental value and QRPA calculations relevant to double-{beta} decay matrix elements persists. We find agreement with previous measurements of the 539.5- and 590.8-keV {gamma}-ray intensities.

  9. Detection of trace levels of triclopyr using capillary gas chromatography-electron-capture negative-ion chemical ionization mass spectrometry.

    PubMed

    Begley, P; Foulger, B E

    1988-04-01

    Triclopyr, after esterification, is shown to be a suitable candidate for detection by gas chromatography-electron-capture negative-ion chemical ionization mass spectrometry forming a characteristic carboxylate anion which offers a high detection sensitivity. A detection limit of 70 fg reaching the ionizer is indicated. Low backgrounds and an absence of chemical interferences are shown for vegetation extracts, using a simple method of extraction and derivatisation. A similar behaviour is demonstrated for 2,4-D and 2,4,5-T.

  10. Measurement of the {beta}{sup +} and Orbital Electron-Capture Decay Rates in Fully Ionized, Hydrogenlike, and Heliumlike {sup 140}Pr Ions

    SciTech Connect

    Litvinov, Yu. A.; Geissel, H.; Winckler, N.; Knoebel, R.; Litvinov, S. A.; Scheidenberger, C.; Bosch, F.; Beckert, K.; Brandau, C.; Dimopoulou, C.; Hess, S.; Kozhuharov, C.; Mazzocco, M.; Nociforo, C.; Nolden, F.; Prochazka, A.; Reuschl, R.; Steck, M.; Stoehlker, T.; Trassinelli, M.

    2007-12-31

    We report on the first measurement of the {beta}{sup +} and orbital electron-capture decay rates of {sup 140}Pr nuclei with the simplest electron configurations: bare nuclei, hydrogenlike, and heliumlike ions. The measured electron-capture decay constant of hydrogenlike {sup 140}Pr{sup 58+} ions is about 50% larger than that of heliumlike {sup 140}Pr{sup 57+} ions. Moreover, {sup 140}Pr ions with one bound electron decay faster than neutral {sup 140}Pr{sup 0+} atoms with 59 electrons. To explain this peculiar observation one has to take into account the conservation of the total angular momentum, since only particular spin orientations of the nucleus and of the captured electron can contribute to the allowed decay.

  11. Bond cleavage reactions in the tripeptide trialanine upon free electron capture

    NASA Astrophysics Data System (ADS)

    Puschnigg, Benjamin; Huber, Stefan E.; Scheier, Paul; Probst, Michael; Denifl, Stephan

    2014-05-01

    In the present study we performed dissociative electron attachment (DEA) measurements with the tripeptide trialanine, C9H17N3O4, utilizing a crossed electron-molecular beam experiment with high electron energy resolution (~100 meV). Anion efficiency yields as a function of the incident electron energy are obtained for the most abundant anions up to electron energies of ~4 eV. Quantum chemical calculations are performed to determine the thermochemical thresholds for the anions observed in the measurements. There is no evidence of a molecular anion with lifetime of mass spectrometric timescales. The dehydrogenated closed shell anion (M-H)- is one of the fragment anions observed for which the calculations show that H-loss is energetically possible from carboxyl, as well as amide groups. In contrast to the dipeptide dialanine and monomer alanine the cleavage of the N-Cα bond in the peptide chain is already possible by attachment of electrons at ~0 eV. Contribution to the Topical Issue "Nano-scale Insights into Ion-beam Cancer Therapy", edited by Andrey V. Solov'yov, Nigel Mason, Paulo Limão-Vieira and Malgorzata Smialek-Telega.

  12. Electron capture decay of 58-min U-229(92) and levels in Pa-229(91)

    SciTech Connect

    Ahmad, I.; Chasman, R. R.; Greene, J. P.; Kondev, F. G.; Zhu, S.

    2015-08-17

    Electron capture decay of U-229 is investigated by measuring the gamma-ray and conversion electron spectra of mass-separated and unseparated U-229 sources with high-resolution germanium and silicon detectors, respectively. Gamma-gamma coincidence measurements are also performed using germanium detectors. These studies provide level energies and level ordering in Pa-229. Single-particle assignments are given to these levels which are in agreement with the systematics in this region and also with theory. In a previous study, we report the observation of a 5/2(+/-) parity doublet in the Pa-229 ground state, which is a signature of octupole deformation. The present analysis of the data still shows a splitting of 60 +/- 50 eV, but with this large uncertainty the existence of the doublet is not certain.

  13. Capturing Structural Dynamics in Crystalline Silicon Using Chirped Electrons from a Laser Wakefield Accelerator

    PubMed Central

    He, Z.-H.; Beaurepaire, B.; Nees, J. A.; Gallé, G.; Scott, S. A.; Pérez, J. R. Sánchez; Lagally, M. G.; Krushelnick, K.; Thomas, A. G. R.; Faure, J.

    2016-01-01

    Recent progress in laser wakefield acceleration has led to the emergence of a new generation of electron and X-ray sources that may have enormous benefits for ultrafast science. These novel sources promise to become indispensable tools for the investigation of structural dynamics on the femtosecond time scale, with spatial resolution on the atomic scale. Here, we demonstrate the use of laser-wakefield-accelerated electron bunches for time-resolved electron diffraction measurements of the structural dynamics of single-crystal silicon nano-membranes pumped by an ultrafast laser pulse. In our proof-of-concept study, we resolve the silicon lattice dynamics on a picosecond time scale by deflecting the momentum-time correlated electrons in the diffraction peaks with a static magnetic field to obtain the time-dependent diffraction efficiency. Further improvements may lead to femtosecond temporal resolution, with negligible pump-probe jitter being possible with future laser-wakefield-accelerator ultrafast-electron-diffraction schemes. PMID:27824086

  14. An antibiotic linked to peptides and proteins is released by electron capture dissociation fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Fagerquist, Clifton K; Hudgins, Robert R; Emmett, Mark R; Håkansson, Kristina; Marshall, Alan G

    2003-04-01

    Desfuroylceftiofur (DFC) is a bioactive beta-lactam antibiotic metabolite that has a free thiol group. Previous experiments have shown release of DFC from plasma extracts after addition of a disulfide reducing agent, suggesting that DFC may be bound to plasma and tissue proteins through disulfide bonds. We have reacted DFC with [Arg(8)]-vasopressin (which has one disulfide bond) and bovine insulin (which has three disulfide bonds) and analyzed the reaction products by use of electron capture dissociation Fourier transform ion cyclotron resonance mass spectrometry (ECD FT-ICR MS), which has previously shown preferential cleavage of disulfide bonds. We observe cleavage of DFC from vasopressin and insulin during ECD, suggesting that DFC is indeed bound to peptides and proteins through disulfide bonds. Specifically, we observed dissociative loss of one, as well as two, DFC species during ECD of [vasopressin + 2(DFC-H) + 2H](2+) from a single electron capture event. Loss of two DFCs could arise from either consecutive or simultaneous loss, but in any case implies a gas phase disulfide exchange step. ECD of [insulin + DFC + 4H](4+) shows preferential dissociative loss of DFC. Combined with HPLC, ECD FT-ICR-MS may be an efficient screening method for detection of drug-biomolecule binding.

  15. On the Significance of the Contribution of Multiple-Electron Capture Processes to Cometary X-Ray Emission

    SciTech Connect

    Ali, R; Neill, P A; Beiersdorfer, P; Harris, C L; Rakovi?, M J; Wang, J G; Schultz, D R; Stancil, P C

    2005-05-12

    We report laboratory studies of the role played by multiple-electron capture (MEC) in solar wind induced cometary X-ray emission. Collisions of Ne{sup 10+} with He, Ne, Ar, CO, and CO{sub 2} have been investigated by means of the traditional singles X-ray spectroscopy in addition to the triple-coincidence measurements of X-rays, scattered projectile, and target recoil ions for the atomic targets. The coincidence measurements enable the reduction of the singles X-ray spectra into partial spectra originating in single-electron capture (SEC) and MEC collisions. The measurements provide unequivocal evidence for a significant role played by MEC, and strongly suggest that models based solely on SEC are bound to yield erroneous conclusions on the solar wind composition and velocities and on cometary atmospheres. The experimental relative importance of MEC collisions is compared with molecular classical-over-the-barrier model (MCBM), classical trajectory Monte Carlo (CTMC), and multi-channel Landau-Zener (MCLZ), calculations which can qualitatively reproduce the experimental trends.

  16. Capillary atmospheric pressure electron capture ionization (cAPECI): a highly efficient ionization method for nitroaromatic compounds.

    PubMed

    Derpmann, Valerie; Mueller, David; Bejan, Iustinian; Sonderfeld, Hannah; Wilberscheid, Sonja; Koppmann, Ralf; Brockmann, Klaus J; Benter, Thorsten

    2014-03-01

    We report on a novel method for atmospheric pressure ionization of compounds with elevated electron affinity (e.g., nitroaromatic compounds) or gas phase acidity (e.g., phenols), respectively. The method is based on the generation of thermal electrons by the photo-electric effect, followed by electron capture of oxygen when air is the gas matrix yielding O2(-) or of the analyte directly with nitrogen as matrix. Charge transfer or proton abstraction by O2(-) leads to the ionization of the analytes. The interaction of UV-light with metals is a clean method for the generation of thermal electrons at atmospheric pressure. Furthermore, only negative ions are generated and neutral radical formation is minimized, in contrast to discharge- or dopant assisted methods. Ionization takes place inside the transfer capillary of the mass spectrometer leading to comparably short transfer times of ions to the high vacuum region of the mass spectrometer. This strongly reduces ion transformation processes, resulting in mass spectra that more closely relate to the neutral analyte distribution. cAPECI is thus a soft and selective ionization method with detection limits in the pptV range. In comparison to standard ionization methods (e.g., PTR), cAPECI is superior with respect to both selectivity and achievable detection limits. cAPECI demonstrates to be a promising ionization method for applications in relevant fields as, for example, explosives detection and atmospheric chemistry.

  17. Investigation of the Mechanism of Electron Capture and Electron Transfer Dissociation of Peptides with a Covalently Attached Free Radical Hydrogen Atom Scavenger.

    PubMed

    Sohn, Chang Ho; Yin, Sheng; Peng, Ivory; Loo, Joseph A; Beauchamp, J L

    2015-11-15

    The mechanisms of electron capture and electron transfer dissociation (ECD and ETD) are investigated by covalently attaching a free-radical hydrogen atom scavenger to a peptide. The 2,2,6,6-tetramethylpiperidin-l-oxyl (TEMPO) radical was chosen as the scavenger due to its high hydrogen atom affinity (ca. 280 kJ/mol) and low electron affinity (ca. 0.45 ev), and was derivatized to the model peptide, FQX(TEMPO)EEQQQTEDELQDK. The X(TEMPO) residue represents a cysteinyl residue derivatized with an acetamido-TEMPO group. The acetamide group without TEMPO was also examined as a control. The gas phase proton affinity (882 kJ/mol) of TEMPO is similar to backbone amide carbonyls (889 kJ/mol), minimizing perturbation to internal solvation and sites of protonation of the derivatized peptides. Collision induced dissociation (CID) of the TEMPO tagged peptide dication generated stable odd-electron b and y type ions without indication of any TEMPO radical induced fragmentation initiated by hydrogen abstraction. The type and abundance of fragment ions observed in the CID spectra of the TEMPO and acetamide tagged peptides are very similar. However, ECD of the TEMPO labeled peptide dication yielded no backbone cleavage. We propose that a labile hydrogen atom in the charge reduced radical ions is scavenged by the TEMPO radical moiety, resulting in inhibition of N-Cα backbone cleavage processes. Supplemental activation after electron attachment (ETcaD) and CID of the charge-reduced precursor ion generated by electron transfer of the TEMPO tagged peptide dication produced a series of b + H (b(H)) and y + H (y(H)) ions along with some c ions having suppressed intensities, consistent with stable O-H bond formation at the TEMPO group. In summary, the results indicate that ECD and ETD backbone cleavage processes are inhibited by scavenging of a labile hydrogen atom by the localized TEMPO radical moiety. This observation supports the conjecture that ECD and ETD processes involve long

  18. Structural determination of zinc dithiophosphates in lubricating oils by gas chromatography-mass spectrometry with electron impact and electron-capture negative ion chemical ionization.

    PubMed

    Becchi, M; Perret, F; Carraze, B; Beziau, J F; Michel, J P

    2001-01-05

    Pentafluorobenzyl ester derivatives were used to identify zinc dialkyldithiophosphates and diaryldithiophosphates antiwear engine oil additives by GC-electron impact ionization (EI) MS and GC-electron-capture negative ion chemical ionization (ECNCI) MS analysis. GC-EI-MS of the dialkyldithiophosphate-pentafluorobenzyl derivatives afforded characteristic fragment ions corresponding to the cleavage of one and two alkyl radicals. In most cases, information was only obtained on one alkyl chain. Additional and complete information was obtained with retention time indices using synthetic derivatives and with GC-ECNCI-MS analysis. ECNCI afforded characteristic dithiophosphate anions which allowed the determination of the total number of carbon atoms in the alkyl radicals. The diastereoisomer mixtures of 2-hydroxy-sec.-alkyl radicals were completely separated on GC analysis.

  19. Dynamics of O{sup 6+} + H electron capture in Debye plasmas and properties of resulting O{sup 5+}(nl) emission spectra

    SciTech Connect

    Zhao, Y. Q.; Xue, P.; Liu, L.; Wang, J. G.; Janev, R. K.

    2010-08-15

    The electron capture in O{sup 6+}-H collisions is studied by the two-center atomic orbital close-coupling (TC-AOCC) method when the interactions of charged particles are screened and have a Yukawa form. Atomic orbitals and eigenenergies of n {<=} 6 states on O{sup 5+} and n {<=} 2 states on H are calculated as a function of the interaction screening parameter and used in the AOCC dynamics scheme to calculate the electron capture cross sections in the energy range 1-200 keV/u. It is shown that the degree of interaction screening reduces the electron binding energies, the number of open electron capture channels, and the strength of exchange couplings, thus affecting the entire collision dynamics and the magnitude and energy behavior of electron capture cross sections. The state-selective electron capture cross sections in this collision system, as well as the intensities of a number of charge exchange spectral lines, for a number of representative interaction screening strengths are presented and discussed.

  20. The effects of ultra-strong magnetic fields on electron capture rates for iron group nuclei in the outer crust of magnetars

    NASA Astrophysics Data System (ADS)

    Du, Jun; Luo, Zhi-Quan; Zhang, Jie

    2014-06-01

    Based on the work of Wang et al. (Chin. Phys. Lett. 29:049701, 2012), we re-investigated electron capture on iron group nuclei in the outer crust of magnetars and studied magnetar evolution. Effects of ultra-strong magnetic field on electron capture rates for 57Co have been analyzed in the nuclear shell model and under the Landau-level-quantization approximation, and the electron capture rates and the neutrino energy loss rates on iron group nuclei in the outer crust of magnetar have been calculated. The results show that electron capture rates on 57Co are increase greatly in the ultra-strong magnetic field, and above 3 orders of magnitude generally; and the neutrino energy loss rates by electron capture on iron group nuclei increase above 3 orders of magnitude in the range from B=4.414×1013 G to B=4.414×1015 G. These conclusions play an important role in future studying the evolution of magnetar. Furthermore, we modify the expressions of the electron chemical potential (Fermi energy) and phase space factor by introducing Dirac δ-function, and select appropriate parameters of temperature T, magnetic field B and matter density ρ in the our crust, thus our results will be reliable than those of Wang et al.

  1. The internal architecture of leukocyte lipid body organelles captured by three-dimensional electron microscopy tomography.

    PubMed

    Melo, Rossana C N; Paganoti, Guillherme F; Dvorak, Ann M; Weller, Peter F

    2013-01-01

    Lipid bodies (LBs), also known as lipid droplets, are complex organelles of all eukaryotic cells linked to a variety of biological functions as well as to the development of human diseases. In cells from the immune system, such as eosinophils, neutrophils and macrophages, LBs are rapidly formed in the cytoplasm in response to inflammatory and infectious diseases and are sites of synthesis of eicosanoid lipid mediators. However, little is known about the structural organization of these organelles. It is unclear whether leukocyte LBs contain a hydrophobic core of neutral lipids as found in lipid droplets from adipocytes and how diverse proteins, including enzymes involved in eicosanoid formation, incorporate into LBs. Here, leukocyte LB ultrastructure was studied in detail by conventional transmission electron microscopy (TEM), immunogold EM and electron tomography. By careful analysis of the two-dimensional ultrastructure of LBs from human blood eosinophils under different conditions, we identified membranous structures within LBs in both resting and activated cells. Cyclooxygenase, a membrane inserted protein that catalyzes the first step in prostaglandin synthesis, was localized throughout the internum of LBs. We used fully automated dual-axis electron tomography to study the three-dimensional architecture of LBs in high resolution. By tracking 4 nm-thick serial digital sections we found that leukocyte LBs enclose an intricate system of membranes within their "cores". After computational reconstruction, we showed that these membranes are organized as a network of tubules which resemble the endoplasmic reticulum (ER). Our findings explain how membrane-bound proteins interact and are spatially arranged within LB "cores" and support a model for LB formation by incorporating cytoplasmic membranes of the ER, instead of the conventional view that LBs emerge from the ER leaflets. This is important to understand the functional capabilities of leukocyte LBs in health and

  2. Detailed microscopic calculation of stellar electron and positron capture rates on 24Mg for O+Ne+Mg core simulations

    NASA Astrophysics Data System (ADS)

    Nabi, Jameel-Un

    2008-09-01

    A few white dwarfs, located in binary systems, may acquire sufficiently high mass-accretion rates resulting in the burning of carbon and oxygen under nondegenerate conditions forming an O+Ne+Mg core. These O+Ne+Mg cores are gravitationally less bound than more massive progenitor stars and can release more energy due to the nuclear burning. They are also amongst the probable candidates for low entropy r-process sites. Recent observations of subluminous Type II-P supernovae (e.g. 2005cs, 2003gd, 1999br and 1997D) were able to rekindle the interest in 8-10 Modot which develop O+Ne+Mg cores. Microscopic calculations of capture rates on 24Mg, which may contribute significantly to the collapse of O+Ne+Mg cores, using the shell model and the proton-neutron quasiparticle random-phase approximation (pn-QRPA) theory, were performed earlier and comparisons made. Simulators, however, may require these capture rates on a fine scale. For the first time, a detailed microscopic calculation of the electron and positron capture rates on 24Mg on an extensive temperature-density scale is presented here. This type of scale is more appropriate for interpolation purposes and of greater utility for simulation codes. The calculations are done using the pn-QRPA theory using a separable interaction. The deformation parameter, believed to be a key parameter in QRPA calculations, is adopted from experimental data to increase the reliability of the QRPA results further. The resulting calculated rates are up to a factor of 14 or more enhanced as compared to shell model rates and may lead to some interesting scenarios for core collapse simulators.

  3. Kuang's Semi-Classical Formalism for Calculating Electron Capture Cross Sections: A Space- Physics Application

    NASA Technical Reports Server (NTRS)

    Barghouty, A. F.

    2014-01-01

    Accurate estimates of electroncapture cross sections at energies relevant to the modeling of the transport, acceleration, and interaction of energetic neutral atoms (ENA) in space (approximately few MeV per nucleon) and especially for multi-electron ions must rely on detailed, but computationally expensive, quantum-mechanical description of the collision process. Kuang's semi-classical approach is an elegant and efficient way to arrive at these estimates. Motivated by ENA modeling efforts for apace applications, we shall briefly present this approach along with sample applications and report on current progress.

  4. Natural Language Processing–Enabled and Conventional Data Capture Methods for Input to Electronic Health Records: A Comparative Usability Study

    PubMed Central

    Sheehan, Barbara; Stetson, Peter; Bhatt, Ashish R; Field, Adele I; Patel, Chirag; Maisel, James Mark

    2016-01-01

    Background The process of documentation in electronic health records (EHRs) is known to be time consuming, inefficient, and cumbersome. The use of dictation coupled with manual transcription has become an increasingly common practice. In recent years, natural language processing (NLP)–enabled data capture has become a viable alternative for data entry. It enables the clinician to maintain control of the process and potentially reduce the documentation burden. The question remains how this NLP-enabled workflow will impact EHR usability and whether it can meet the structured data and other EHR requirements while enhancing the user’s experience. Objective The objective of this study is evaluate the comparative effectiveness of an NLP-enabled data capture method using dictation and data extraction from transcribed documents (NLP Entry) in terms of documentation time, documentation quality, and usability versus standard EHR keyboard-and-mouse data entry. Methods This formative study investigated the results of using 4 combinations of NLP Entry and Standard Entry methods (“protocols”) of EHR data capture. We compared a novel dictation-based protocol using MediSapien NLP (NLP-NLP) for structured data capture against a standard structured data capture protocol (Standard-Standard) as well as 2 novel hybrid protocols (NLP-Standard and Standard-NLP). The 31 participants included neurologists, cardiologists, and nephrologists. Participants generated 4 consultation or admission notes using 4 documentation protocols. We recorded the time on task, documentation quality (using the Physician Documentation Quality Instrument, PDQI-9), and usability of the documentation processes. Results A total of 118 notes were documented across the 3 subject areas. The NLP-NLP protocol required a median of 5.2 minutes per cardiology note, 7.3 minutes per nephrology note, and 8.5 minutes per neurology note compared with 16.9, 20.7, and 21.2 minutes, respectively, using the Standard

  5. Radioactive decay speedup at T=5 K: electron-capture decay rate of (7)Be encapsulated in C(60).

    PubMed

    Ohtsuki, T; Ohno, K; Morisato, T; Mitsugashira, T; Hirose, K; Yuki, H; Kasagi, J

    2007-06-22

    The electron-capture (EC) decay rate of (7)Be in C(60) at the temperature of liquid helium (T=5 K) was measured and compared with the rate in Be metal at T=293 K. We found that the half-life of (7)Be in endohedral C(60) ((7)Be@C(60)) at a temperature close to T=5 K is 52.47+/-0.04 d, a value that is 0.34% faster than that at T=293 K. In this environment, the half-life of (7)Be is nearly 1.5% faster than that inside Be metal at room temperature (T=293 K). We then interpreted our observations in terms of calculations of the electron density at the (7)Be nucleus position inside the C(60); further, we estimate theoretically the temperature dependence (at T=0 K and 293 K) of the electron density at the Be nucleus position in the stable center inside C(60). The theoretical estimates were almost in agreement with the experimental observations.

  6. Electron Capture by B^5+ from H2 At E < 1.0 keV/amu

    NASA Astrophysics Data System (ADS)

    Joseph, Dwayne C.; Saha, Bidhan C.

    2007-06-01

    The capture of electrons from molecular targets has considerable influence on the charge state balance of astrophysical as well as magnetically confined fusion plasmas. Molecular targets are in general more complicated than their atomic counterparts. A suitable method by freezing the molecular details of the targets is applied with a core potential [1] that represents the ionic core of the target. The molecular orbital method, including the electron translation factor [2], in the impact parameter formalism [3] is employed to evaluate the state selective cross sections. The motion of the nuclei is treated classically and that due to electron is considered quantum mechanically [4]. Details will be presented at the conference. [1] J. N. Bradsley, Case Stud. At. Phys. 4, 299 (1974). [2] M. Kimura and N. F. Lane, Adv. At. Mol. Opt. Phys. 26, 79 (1990). [3] B. C. Saha and A. Kumar, J. Mol. Struct. THEOCHEM, 487, 11 (1999). [4] A. Kumar and B. C. Saha, Phys. Rev. A 59, 1273 (1999).

  7. Selective uptake, distribution, and redistribution of (109)Cd, (57)Co, (65)Zn, (63)Ni, and (134)Cs via xylem and phloem in the heavy metal hyperaccumulator Solanum nigrum L.

    PubMed

    Wei, Shuhe; Anders, Iwona; Feller, Urs

    2014-06-01

    The focus of this article was to explore the translocation of (109)Cd, (57)Co, (65)Zn, (63)Ni, and (134)Cs via xylem and phloem in the newly found hyperaccumulator Solanum nigrum L. Two experiments with the uptake via the roots and transport of (109)Cd, (57)Co, and (65)Zn labeled by roots, and the redistribution of (109)Cd, (65)Zn, (57)Co, (63)Ni, and (134)Cs using flap label in S. nigrum in a hydroponic culture with a standard nutrient solution were conducted. The results showed that (109)Cd added for 24 h to the nutrient medium of young plants was rapidly taken up, transferred to the shoot, and accumulated in the cotyledons and the oldest leaves but was not efficiently redistributed within the shoot afterward leading to a rather low content in the fruits. In contrast, (57)Co was more slowly taken up and released to the shoot, but afterward, this element was redistributed from older leaves to younger leaves and maturing fruits. (65)Zn was rapidly taken up and transferred to the shoot (mainly to the youngest leaves and not to the cotyledons). Afterward, this radionuclide was redistributed within the shoot to the youngest organs and finally accumulated in the maturing fruits. After flap labeling, all five heavy metals tested ((109)Cd, (57)Co, (65)Zn, (63)Ni, (134)Cs) were exported from the labeled leaf and redistributed within the plant. The accumulation in the fruits was most pronounced for (63)Ni and (65)Zn, while a relatively high percentage of (57)Co was finally found in the roots. (134)Cs was roughly in the middle of them. The transport of (109)Cd differed from that previously reported for wheat or lupin and might be important for the potential of S. nigrum to hyperaccumulate cadmium.

  8. Electron capture gas chromatography study of the acid and alcohol products of Clostridium septicum and Clostridium chauvoei.

    PubMed

    Brooks, J B; Selin, M J; Alley, C C

    1976-02-01

    The metabolic products produced by several strains of Clostridium septicum obtained from patients and animals, along with strains of Clostridium chauvoei, were studied in chopped meat glucose medium by electron capture gas-liquid chromatography (EC-GLC). The strains of C. septicum and C. chauvoei were shown to comprise five different metabolic groups. Both the EC-GLC study and the O and H antigenic study performed previously showed that strains of C. septicum comprise a heterogeneous group. One type of metabolic profile was found only in strains of C. chauvoei. The O antigen types and EC-GLC metabolic types of C. septicum correlated fairly well in isolates from cancer patients but not in stock culture and animal isolates.

  9. Towards saturation of the electron-capture delayed fission probability: The new isotopes 240Es and 236Bk

    NASA Astrophysics Data System (ADS)

    Konki, J.; Khuyagbaatar, J.; Uusitalo, J.; Greenlees, P. T.; Auranen, K.; Badran, H.; Block, M.; Briselet, R.; Cox, D. M.; Dasgupta, M.; Di Nitto, A.; Düllmann, Ch. E.; Grahn, T.; Hauschild, K.; Herzán, A.; Herzberg, R.-D.; Heßberger, F. P.; Hinde, D. J.; Julin, R.; Juutinen, S.; Jäger, E.; Kindler, B.; Krier, J.; Leino, M.; Lommel, B.; Lopez-Martens, A.; Luong, D. H.; Mallaburn, M.; Nishio, K.; Pakarinen, J.; Papadakis, P.; Partanen, J.; Peura, P.; Rahkila, P.; Rezynkina, K.; Ruotsalainen, P.; Sandzelius, M.; Sarén, J.; Scholey, C.; Sorri, J.; Stolze, S.; Sulignano, B.; Theisen, Ch.; Ward, A.; Yakushev, A.; Yakusheva, V.

    2017-01-01

    The new neutron-deficient nuclei 240Es and 236Bk were synthesised at the gas-filled recoil separator RITU. They were identified by their radioactive decay chains starting from 240Es produced in the fusion-evaporation reaction 209Bi(34S,3n)240Es. Half-lives of 6 (2)s and 22-6+13s were obtained for 240Es and 236Bk, respectively. Two groups of α particles with energies Eα = 8.19 (3)MeV and 8.09 (3)MeV were unambiguously assigned to 240Es. Electron-capture delayed fission branches with probabilities of 0.16 (6) and 0.04 (2) were measured for 240Es and 236Bk, respectively. These new data show a continuation of the exponential increase of ECDF probabilities in more neutron-deficient isotopes.

  10. Determination of hexachloro-1,3-butadiene in spinach, eggs, fish, and milk by electron capture gas-liquid chromatography.

    PubMed

    Yurawecz, M P; Dreifuss, P A; Kamps, L R

    1976-05-01

    Hexachloro-1,3-butadiene (HCBD), a waste product formed in the manufacture of perchloroethylene and trichloroethylene, has been found in fish from the lower Mississippi River basin. The AOAC official method for organochlorine pesticide residues in fatty and nonfatty foods has been modified for the determination of HCBD residues in selected food commodities. Acetonitrile extracts of nonfatty foods, or the combined acetonitrile extracts obtained in acetonitrile-petroleum ether partitioning of fat isolated from fatty foods, are diluted with water and extracted with petroleum ether. The petroleum ether extracts are chromatographed on Florisil and HCBD is eluted with petroleum ether. The elute is analyzed by gas-liquid chromatography with an electron capture detector. Average recoveries of HCBD from fortified samples of fatty and nonfatty foods were greater than 90% in the interlaboratory trials of the method.

  11. Ambient air analyses using nonspecific flame ionization and electron capture detection compared to specific detection by mass spectroscopy

    SciTech Connect

    Pleil, J.D.; Oliver, K.D.; McClenny, W.A.

    1988-08-01

    Ambient air samples from various studies were analyzed for a specific set of trace-level volatile organic compounds by using a gas chromatograph (GC) equipped with a flame ionization detector (FID) in parallel with an electron capture detector (ECD). The samples were then reanalyzed on a second GC system equipped with a mass selective detector (MSD). GC-FID/ECD data were compared to the nominally correct GC-MSD data to determine the accuracy of the nonspecific detectors, which often do not differentiate the targeted compound from interfering compounds. Qualitative accuracy (capability for correctly identifying compounds on the basis of retention time only) and quantitative accuracy (capability for correctly measuring the concentration of an identified compound on the basis of peak area) were evaluated. Data are presented on a per-compound basis to provide the combined typical results from air samples collected in three geographic regions: Kanawha Valley, WV; Los Angeles, CA, area; and Houston, TX.

  12. A Novel Feature Extraction Approach Using Window Function Capturing and QPSO-SVM for Enhancing Electronic Nose Performance

    PubMed Central

    Guo, Xiuzhen; Peng, Chao; Zhang, Songlin; Yan, Jia; Duan, Shukai; Wang, Lidan; Jia, Pengfei; Tian, Fengchun

    2015-01-01

    In this paper, a novel feature extraction approach which can be referred to as moving window function capturing (MWFC) has been proposed to analyze signals of an electronic nose (E-nose) used for detecting types of infectious pathogens in rat wounds. Meanwhile, a quantum-behaved particle swarm optimization (QPSO) algorithm is implemented in conjunction with support vector machine (SVM) for realizing a synchronization optimization of the sensor array and SVM model parameters. The results prove the efficacy of the proposed method for E-nose feature extraction, which can lead to a higher classification accuracy rate compared to other established techniques. Meanwhile it is interesting to note that different classification results can be obtained by changing the types, widths or positions of windows. By selecting the optimum window function for the sensor response, the performance of an E-nose can be enhanced. PMID:26131672

  13. A Novel Feature Extraction Approach Using Window Function Capturing and QPSO-SVM for Enhancing Electronic Nose Performance.

    PubMed

    Guo, Xiuzhen; Peng, Chao; Zhang, Songlin; Yan, Jia; Duan, Shukai; Wang, Lidan; Jia, Pengfei; Tian, Fengchun

    2015-06-29

    In this paper, a novel feature extraction approach which can be referred to as moving window function capturing (MWFC) has been proposed to analyze signals of an electronic nose (E-nose) used for detecting types of infectious pathogens in rat wounds. Meanwhile, a quantum-behaved particle swarm optimization (QPSO) algorithm is implemented in conjunction with support vector machine (SVM) for realizing a synchronization optimization of the sensor array and SVM model parameters. The results prove the efficacy of the proposed method for E-nose feature extraction, which can lead to a higher classification accuracy rate compared to other established techniques. Meanwhile it is interesting to note that different classification results can be obtained by changing the types, widths or positions of windows. By selecting the optimum window function for the sensor response, the performance of an E-nose can be enhanced.

  14. Determining the Binding Sites of β-Cyclodextrin and Peptides by Electron-Capture Dissociation High Resolution Tandem Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Qi, Yulin; Geib, Timon; Volmer, Dietrich A.

    2015-07-01

    Cyclodextrins (CDs) are a group of cyclic oligosaccharides, which readily form inclusion complexes with hydrophobic compounds to increase bioavailability, thus making CDs ideal drug excipients. Recent studies have also shown that CDs exhibit a wide range of protective effects, preventing proteins from aggregation, degradation, and folding. These effects strongly depend on the binding sites on the protein surface. CDs only exhibit weak interactions with amino acids, however; conventional analytical techniques therefore usually fail to reveal the exact location of the binding sites. Moreover, some studies even suggest that CD inclusion complexes are merely electrostatic adducts. Here, electron capture dissociation (ECD) was applied in this proof-of-concept study to examine the exact nature of the CD/peptide complexes, and CD binding sites were unambiguously located for the first time via Fourier-transform ion cyclotron resonance (FTICR) tandem mass spectrometry.

  15. Longitudinal assessment of pain outcomes in the clinical setting: development of the "APOLO" electronic data capture system.

    PubMed

    Hassett, Afton L; Wasserman, Ronald; Goesling, Jenna; Rakovitis, Kevin; Shi, Baorong; Brummett, Chad M

    2012-01-01

    Data to fully evaluate the effectiveness of many commonly used interventions in the clinical pain management setting are inadequate. Clinical data collected for patient management often are not based on validated instruments, and this impedes the ability to conduct longitudinal research. To address these needs, modified patient intake and return visit forms were established and the Assessment of Pain Outcomes Longitudinal Electronic Data Capture system was developed. Data collection has been underway since November 22, 2010. As of December 7, 2011, 951 New Patient and 688 Return Visit forms had been entered. The forms have been well received, with less than 6.5% failing to complete at least 90% of the data requested. Accuracy of data entry is excellent, with an error rate of 1 in 11,250 potential data points. Data output converts easily to standard statistical programs. The creation of a pain outcomes database using validated measures and clinically relevant data is feasible.

  16. Determination of malathion, coumaphos, and fluvalinate residues in honey by gas chromatography with nitrogen-phosphorus or electron capture detectors.

    PubMed

    Menkissoglu-Spiroudi, U; Diamantidis, G C; Georgiou, V E; Thrasyvoulou, A T

    2000-01-01

    A rapid, reliable, and inexpensive extraction method was developed to determine acaricide residues in honey by gas chromatography (GC) with nitrogen-phosphorus (NP) or electron capture (EC) detectors. Because of the high selectivity of the NP detector, no interfering peaks were present and no cleanup was necessary. A simple cleanup step is proposed for the GC-ECD analysis. Recoveries from spiked honey samples ranged from 79 to 94.4%, with coefficients of variation of 0.3-18.5%. The quantitation limit obtained was 0.015 mg/kg for malathion, 0.020 mg/kg for coumaphos, and 0.005 mg/kg for fluvalinate. The method was used to determine the disappearance of malathion and coumaphos residues from honey samples collected from beehives treated with these acaricides. The disappearance of both acaricides was rapid and followed a first-order model for the duration of the experiment.

  17. Probing the Electron Capture Dissociation Mass Spectrometry of Phosphopeptides with Traveling Wave Ion Mobility Spectrometry and Molecular Dynamics Simulations

    NASA Astrophysics Data System (ADS)

    Kim, Doyong; Pai, Pei-Jing; Creese, Andrew J.; Jones, Andrew W.; Russell, David H.; Cooper, Helen J.

    2015-06-01

    Electron capture dissociation mass spectrometry offers several advantages for the analysis of peptides, most notably that backbone c and z fragments typically retain labile modifications such as phosphorylation. We have shown previously that, in some cases, the presence of phosphorylation has a deleterious effect on peptide sequence coverage, and hypothesized that intramolecular interactions involving the phosphate group were preventing separation of backbone fragments. In the present work, we seek to rationalize the observed ECD behavior through a combination of ECD of model peptides, traveling wave ion mobility mass spectrometry and molecular dynamics simulations. The results suggest that for doubly protonated ions of phosphopeptide APLpSFRGSLPKSYVK a salt-bridge structure is favored, whereas for the doubly-protonated ions of APLSFRGSLPKpSYVK ionic hydrogen bonds predominate.

  18. The origin of the Crab Nebula and the electron capture supernova in 8-10 M solar mass stars

    NASA Technical Reports Server (NTRS)

    Nomoto, K.

    1981-01-01

    The chemical composition of the Crab Nebula is compared with several presupernova models. The small carbon and oxygen abundances in the helium-rich nebula are consistent with only the presupernova model of the star whose main sequence mass was MMS approximately 8-9.5 M. More massive stars contain too much carbon in the helium layer and smaller mass stars do not leave neutron stars. The progenitor star of the Crab Nebula lost appreciable part of the hydrogen-rich envelope before the hydrogen-rich and helium layers were mixed by convection. Finally it exploded as the electron capture supernova; the O+Ne+Mg core collapsed to form a neutron star and only the extended helium-rich envelope was ejected by the weak shock wave.

  19. Determining the Binding Sites of β-Cyclodextrin and Peptides by Electron-Capture Dissociation High Resolution Tandem Mass Spectrometry.

    PubMed

    Qi, Yulin; Geib, Timon; Volmer, Dietrich A

    2015-07-01

    Cyclodextrins (CDs) are a group of cyclic oligosaccharides, which readily form inclusion complexes with hydrophobic compounds to increase bioavailability, thus making CDs ideal drug excipients. Recent studies have also shown that CDs exhibit a wide range of protective effects, preventing proteins from aggregation, degradation, and folding. These effects strongly depend on the binding sites on the protein surface. CDs only exhibit weak interactions with amino acids, however; conventional analytical techniques therefore usually fail to reveal the exact location of the binding sites. Moreover, some studies even suggest that CD inclusion complexes are merely electrostatic adducts. Here, electron capture dissociation (ECD) was applied in this proof-of-concept study to examine the exact nature of the CD/peptide complexes, and CD binding sites were unambiguously located for the first time via Fourier-transform ion cyclotron resonance (FTICR) tandem mass spectrometry.

  20. Determination of naloxone and naltrexone as perfluoroalkyl ester derivatives by electron-capture gas-liquid chromatography.

    PubMed

    Sams, R A; Malspeis, L

    1976-10-13

    An electron-capture gas chromatographic method is described for the determination of naloxone and naltrexone as the perfluoroalkyl esters. Each compound serves as internal standard for determination of the other. The method permits quantitation of 2-100 ng of either compound. Conditions for derivatization with heptafluorobutyric anhydride (HFBA), pentafluoropropionic anhydride (PFPA), and trifluoroacetic anhydride (TFAA) have been investigated. When catalyzed with pyridine, derivatization with HFBA and PFPA at 70 degrees gives naloxone and naltrexone triesters. Evidence for triester formation was obtained from gas chromatography-methane chemical ionization mass spectrometry and infrared spectral analysis. It was found that both the HFB and PFP triesters are suitable for quantitation of the narcotic antagonists, the HFB derivatives having greater stability than the PFP derivatives. The TFA derivatives are substantially less stable.

  1. Fragmentation dynamics of CO(2)(3+) investigated by multiple electron capture in collisions with slow highly charged ions.

    PubMed

    Neumann, N; Hant, D; Schmidt, L Ph H; Titze, J; Jahnke, T; Czasch, A; Schöffler, M S; Kreidi, K; Jagutzki, O; Schmidt-Böcking, H; Dörner, R

    2010-03-12

    Fragmentation of highly charged molecular ions or clusters consisting of more than two atoms can proceed in a one step synchronous manner where all bonds break simultaneously or sequentially by emitting one ion after the other. We separated these decay channels for the fragmentation of CO(2)(3+) ions by measuring the momenta of the ionic fragments. We show that the total energy deposited in the molecular ion is a control parameter which switches between three distinct fragmentation pathways: the sequential fragmentation in which the emission of an O(+) ion leaves a rotating CO(2+) ion behind that fragments after a time delay, the Coulomb explosion and an in-between fragmentation--the asynchronous dissociation. These mechanisms are directly distinguishable in Dalitz plots and Newton diagrams of the fragment momenta. The CO(2)(3+) ions are produced by multiple electron capture in collisions with 3.2 keV/u Ar(8+) ions.

  2. Electron capture decay of cosmic rays: A model of the inhomogeneous interstellar medium

    NASA Technical Reports Server (NTRS)

    Letaw, J. R.; Silberberg, R.; Tsao, C. H.

    1985-01-01

    Traditional analyses of cosmic ray composition seek to identify the sources through a determination of a the isotopic abundances of these nuclei prior to acceleration. At the same time, it is both necessary and interesting to understand the nature of the medium through which cosmic rays pass before arriving at detectors. In fact, only within a model of the interstellar medium (ISM) sampled by cosmic rays can a refined estimate of source composition be made. An elaboration of the traditional model of the ISM used in studying cosmic ray propagation is explored. Inhomogeneity of the ISM is accomodated in this model. Within this model it is found that the abundances of some electron apture isotopes, are very sensitive to density inhomogeneities which might be expected in the ISM. These nuclei therefore measure the penetration of heavy cosmic rays into interstellar clouds.

  3. Transmission electron microscopic observations of nanobubbles and their capture of impurities in wastewater

    PubMed Central

    2011-01-01

    Unique properties of micro- and nanobubbles (MNBs), such as a high adsorption of impurities on their surface, are difficult to verify because MNBs are too small to observe directly. We thus used a transmission electron microscope (TEM) with the freeze-fractured replica method to observe oxygen (O2) MNBs in solutions. MNBs in pure water and in 1% NaCl solutions were spherical or oval. Their size distribution estimated from TEM images close to that of the original solution is measured by light-scattered methods. When we applied this technique to the observation of O2 MNBs formed in the wastewater of a sewage plant, we found the characteristic features of spherical MNBs that adsorbed surrounding impurity particles on their surface. PACS: 68.03.-g, 81.07.-b, 92.40.qc PMID:21711798

  4. Electronic Capture of Written Handoff Information: What Are the Next Steps?

    PubMed

    Nabors, Christopher; Khera, Sahil; Forman, Leanne; Kolte, Dhaval; Mittal, Varun; Marballi, Abhishek; Agrawal, Sahil; Pawar, Rahul; OʼConnell, Daniel; Afanador, Sara M; Kolandaivel, Krishna; Chugh, Savneek; Peterson, Stephen J

    2016-01-01

    Communication lapses during patient care transitions are reported to be frequent and may result in patient harm. The primary objective of our study was to assess the completeness, accuracy, and usefulness of our electronic handoff system to guide future software changes and educational interventions. We randomly selected and reviewed 707 of 2840 available handoff records generated on the medicine service of an academic medical center between August 1, 2012 and December 31, 2012. We used both quantitative and qualitative analytical techniques to characterize sign-outs in the following dimensions: completeness, usefulness and accuracy of information content, handoff task category, logic, internal consistency and appropriateness of assigned tasks, and composition and complexity of assigned tasks. The degree of completeness of information varied considerably across domains. Completeness was highest for entry of assigned tasks (99.9%), nearly as high for hospital course/presenting illness (95%), and relatively high (87%-98%) for entry of provider name and contact information, principal diagnosis, allergies, current clinical condition, mental status, and code status. Eighty-eight percent written handoffs described clinical condition and hospital course and whether there were tasks to complete. In 58% of suitable records, all problems listed in the electronic health record (EHR) were also present in the history of present illness. The accuracy of entered information also displayed wide variation. Only 80% of cardiovascular medications matched the contemporaneous EHR pharmacy record. Birth dates and allergies were identical in the handoff system and EHR in 95% and 86% of respective records. Of assigned tasks, 8% contained at least 1 unnecessary component or illogical/internally inconsistent element. Use of a handoff system, which organizes information entry through a standard template, promotes completeness of written handoff information. Inaccuracies in handoff data are

  5. The translation elongation cycle-capturing multiple states by cryo-electron microscopy.

    PubMed

    Frank, Joachim

    2017-03-19

    During the work cycle of elongation, the ribosome, a molecular machine of vast complexity, exists in a large number of states distinguished by constellation of its subunits, its subunit domains and binding partners. Single-particle cryogenic electron microscopy (cryo-EM), developed over the past 40 years, is uniquely suited to determine the structure of molecular machines in their native states. With the emergence, 10 years ago, of unsupervised clustering techniques in the analysis of single-particle data, it has been possible to determine multiple structures from a sample containing ribosomes equilibrating in different thermally accessible states. In addition, recent advances in detector technology have made it possible to reach near-atomic resolution for some of these states. With these capabilities, single-particle cryo-EM has been at the forefront of exploring ribosome dynamics during its functional cycle, along with single-molecule fluorescence resonance energy transfer and molecular dynamics computations, offering insights into molecular architecture uniquely honed by evolution to capitalize on thermal energy in the ambient environment.This article is part of the themed issue 'Perspectives on the ribosome'.

  6. Capturing district nursing through a knowledge-based electronic caseload analysis tool (eCAT).

    PubMed

    Kane, Kay

    2014-03-01

    The Electronic Caseload Analysis Tool (eCAT) is a knowledge-based software tool to assist the caseload analysis process. The tool provides a wide range of graphical reports, along with an integrated clinical advisor, to assist district nurses, team leaders, operational and strategic managers with caseload analysis by describing, comparing and benchmarking district nursing practice in the context of population need, staff resources, and service structure. District nurses and clinical lead nurses in Northern Ireland developed the tool, along with academic colleagues from the University of Ulster, working in partnership with a leading software company. The aim was to use the eCAT tool to identify the nursing need of local populations, along with the variances in district nursing practice, and match the workforce accordingly. This article reviews the literature, describes the eCAT solution and discusses the impact of eCAT on nursing practice, staff allocation, service delivery and workforce planning, using fictitious exemplars and a post-implementation evaluation from the trusts.

  7. Venous thromboembolism capture on electronic systems in obstetrics patients at St Thomas' Hospital

    PubMed Central

    Ahmad, Aminah Noor; Byrne, Megan Leyla; Imambaccus, Nazia; Hubert, Dawid; Gateley, Anna; Abdullahi Idle, Salwa; Lloyd, Jilly

    2016-01-01

    Venous thromboembolism (VTE) is one of the leading causes of maternal mortality in the UK. Therefore, timely VTE risk assessment is essential in all obstetrics patients. The Commissioning for Quality and Innovation (CQUIN) payment framework set a target for trusts to complete a VTE risk assessment within 24 hours of admission for 95% of patients. A combination of factors, including lack of integration between multiple IT systems, means that this CQUIN target is currently not being met for obstetric patients in the Hospital Birth Centre at Guys and St Thomas' NHS Trust. This project aims to increase staff awareness of this issue and educate them regarding the correct procedure for VTE assessment. Trialled methods included reminders at staff handovers, use of magnets on the patient whiteboard, posters and stickers displayed around the unit and a loyalty card scheme as incentive to complete assessments. Initial average completion rate was 20.7%, which increased to 67.5% after the first plan, do, study, act (PDSA) cycle with a slight drop to 65.7% after the second cycle. Completion rates increased to 92.3% on the last day of the third PDSA cycle. Although we did not reach the 95% target, we have raised awareness of the importance of recording VTE assessment on electronic systems, and hope we have created sustainable change. PMID:27933149

  8. Scaling of cross sections for K-electron capture by high-energy protons and alpha-particles from the multielectron atoms

    NASA Technical Reports Server (NTRS)

    Omidvar, K.

    1976-01-01

    Electron capture by protons from H, He, and the K-shell of Ar, and alpha particles from He are considered. It is shown that when a certain function of the experimental cross sections is plotted versus the inverse of the collision energy, at high energies the function falls on a straight line. At lower energies the function concaves up or down, depending on the charge of the projectile, the effective charge and the ionization potential of the electron that is being captured. The plot can be used to predict cross sections where experimental data are not available, and as a guide in future experiments. High energy scaling formulas for K-electron capture by low-charge projectiles are given.

  9. X-ray emission following K-L double ionization by electron impact and K capture: Vacancy-production probabilities and structure of the Kα satellite spectra

    NASA Astrophysics Data System (ADS)

    Li-Scholz, Angela; Leiberich, A.; Scholz, W.

    1982-12-01

    Kα x-ray satellites following K-electron capture in 55Fe and electron impact on Mn have been measured with a high-resolution spectrometer. Ratios of double- to single-vacancy-production probability are found to be PKL=(2.5+/-0.5)×10-3 and (9.5+/-0.9)×10-3 for capture and impact, respectively. An evaluation of vacancy rearrangement in the L shell before satellite emission has been carried out with the use of published level widths. It is found that in electron impact, as distinct from K capture, essentially only satellites associated with a 2p spectator vacancy are observed. This observation is at variance with certain commonly used satellite assignments. Energies and intensities of the satellite transitions have been calculated in intermediate coupling and coordinations are proposed for the stronger lines.

  10. Simplifying electronic data capture in clinical trials: workflow embedded image and biosignal file integration and analysis via web services.

    PubMed

    Haak, Daniel; Samsel, Christian; Gehlen, Johan; Jonas, Stephan; Deserno, Thomas M

    2014-10-01

    To improve data quality and save cost, clinical trials are nowadays performed using electronic data capture systems (EDCS) providing electronic case report forms (eCRF) instead of paper-based CRFs. However, such EDCS are insufficiently integrated into the medical workflow and lack in interfacing with other study-related systems. In addition, most EDCS are unable to handle image and biosignal data, although electrocardiography (EGC, as example for one-dimensional (1D) data), ultrasound (2D data), or magnetic resonance imaging (3D data) have been established as surrogate endpoints in clinical trials. In this paper, an integrated workflow based on OpenClinica, one of the world's largest EDCS, is presented. Our approach consists of three components for (i) sharing of study metadata, (ii) integration of large volume data into eCRFs, and (iii) automatic image and biosignal analysis. In all components, metadata is transferred between systems using web services and JavaScript, and binary large objects (BLOBs) are sent via the secure file transfer protocol and hypertext transfer protocol. We applied the close-looped workflow in a multicenter study, where long term (7 days/24 h) Holter ECG monitoring is acquired on subjects with diabetes. Study metadata is automatically transferred into OpenClinica, the 4 GB BLOBs are seamlessly integrated into the eCRF, automatically processed, and the results of signal analysis are written back into the eCRF immediately.

  11. Time Modulation of the K-Shell Electron Capture Decay Rates of H-like Heavy Ions at GSI Experiments

    SciTech Connect

    Ivanov, A. N.; Kienle, P.

    2009-08-07

    According to experimental data at GSI, the rates of the number of daughter ions, produced by the nuclear K shell electron capture decays of the H-like heavy ions with one electron in the K shell, such as {sup 140}Pr{sup 58+}, {sup 142}Pm{sup 60+}, and {sup 122}I{sup 52+}, are modulated in time with periods T{sub EC} of the order of a few seconds, obeying an A scaling T{sub EC}=A/20 s, where A is the mass number of the mother nuclei, and with amplitudes a{sub d}{sup EC}approx0.21. We show that these data can be explained in terms of the interference of two massive neutrino mass eigenstates. The appearance of the interference term is due to overlap of massive neutrino mass eigenstate energies and of the wave functions of the daughter ions in two-body decay channels, caused by the energy and momentum uncertainties introduced by time differential detection of the daughter ions in GSI experiments.

  12. An experiment to verify that the weak interactions satisfy the strong equivalence principle. [electron capture and gravitational potential

    NASA Technical Reports Server (NTRS)

    Eby, P. B.

    1978-01-01

    The construction of a clock based on the beta decay process is proposed to test for any violations by the weak interaction of the strong equivalence principle bu determining whether the weak interaction coupling constant beta is spatially constant or whether it is a function of gravitational potential (U). The clock can be constructed by simply counting the beta disintegrations of some suitable source. The total number of counts are to be taken a measure of elapsed time. The accuracy of the clock is limited by the statistical fluctuations in the number of counts, N, which is equal to the square root of N. Increasing N gives a corresponding increase in accuracy. A source based on the electron capture process can be used so as to avoid low energy electron discrimination problems. Solid state and gaseous detectors are being considered. While the accuracy of this type of beta decay clock is much less than clocks based on the electromagnetic interaction, there is a corresponding lack of knowledge of the behavior of beta as a function of gravitational potential. No predictions from nonmetric theories as to variations in beta are available as yet, but they may occur at the U/sg C level.

  13. Single electron ionization and electron capture cross sections for (C6+, H2O) interaction within the Classical Trajectory Monte Carlo (CTMC) approach

    NASA Astrophysics Data System (ADS)

    Tran, H. N.; Dao, D. D.; Incerti, S.; Bernal, M. A.; Karamitros, M.; Nhan Hao, T. V.; Dang, T. M.; Francis, Z.

    2016-01-01

    In this work, we present a derivation of cross sections for single ionization and electron capture processes within the Classical Trajectory Monte Carlo (CTMC) approach. Specifically, we have used a potential stemming from an ab initio calculation in Green et al.'s framework to describe the dynamics of the water molecule system. Proposing a modified version of the Classical Over-Barrier (COB) potential, we have found that a cut-off of roughly 28 a.u. on the initial distance of the projectile produced a reasonable accuracy. A global agreement has been obtained in our calculations compared to experimental and other theoretical results for C6+ ion energies ranging from 10 keV/u to 10 MeV/u.

  14. Kuang's Semi-Classical Formalism for Electron Capture Cross-Sections in Ion-Ion Collisions at Approximately to MeV/amu: Application to ENA Modeling

    NASA Technical Reports Server (NTRS)

    Barghouty, A. F.

    2012-01-01

    Recent discovery by STEREO A/B of energetic neutral hydrogen is spurring an interest and need for reliable estimates of electron capture cross sections at few MeVs per nucleon as well as for multi-electron ions. Required accuracy in such estimates necessitates detailed and involved quantum-mechanical calculations or expensive numerical simulations. For ENA modeling and similar purposes, a semi-classical approach offers a middle-ground approach. Kuang's semiclassical formalism to calculate electron-capture cross sections for single and multi-electron ions is an elegant and efficient method, but has so far been applied to limited and specific laboratory measurements and at somewhat lower energies. Our goals are to test and extend Kuang s method to all ion-atom and ion-ion collisions relevant to ENA modeling, including multi-electron ions and for K-shell to K-shell transitions.

  15. Mobile Device–Based Electronic Data Capture System Used in a Clinical Randomized Controlled Trial: Advantages and Challenges

    PubMed Central

    Liu, Yu; Wang, Hongyi; Sun, Ningling

    2017-01-01

    Background Electronic data capture (EDC) systems have been widely used in clinical research, but mobile device–based electronic data capture (mEDC) system has not been well evaluated. Objective The aim of our study was to evaluate the feasibility, advantages, and challenges of mEDC in data collection, project management, and telemonitoring in a randomized controlled trial (RCT). Methods We developed an mEDC to support an RCT called “Telmisartan and Hydrochlorothiazide Antihypertensive Treatment (THAT)” study, which was a multicenter, double-blinded, RCT, with the purpose of comparing the efficacy of telmisartan and hydrochlorothiazide (HCTZ) monotherapy in high-sodium-intake patients with mild to moderate hypertension during a 60 days follow-up. Semistructured interviews were conducted during and after the trial to evaluate the feasibility, advantage, and challenge of mEDC. Nvivo version 9.0 (QSR International) was used to analyze records of interviews, and a thematic framework method was used to obtain outcomes. Results The mEDC was successfully used to support the data collection and project management in all the 14 study hospitals. A total of 1333 patients were recruited with support of mEDC, of whom 1037 successfully completed all 4 visits. Across all visits, the average time needed for 141 questions per patient was 53 min, which were acceptable to both doctors and patients. All the interviewees, including 24 doctors, 53 patients, 1 clinical research associate (CRA), 1 project manager (PM), and 1 data manager (DM), expressed their satisfaction to nearly all the functions of the innovative mEDC in randomization, data collection, project management, quality control, and remote monitoring in real time. The average satisfaction score was 9.2 (scale, 0-10). The biggest challenge came from the stability of the mobile or Wi-Fi signal although it was not a problem in THAT study. Conclusions The innovative mEDC has many merits and is well acceptable in supporting

  16. Valence parity to distinguish c' and z• ions from electron capture dissociation/electron transfer dissociation of peptides: effects of isomers, isobars, and proteolysis specificity.

    PubMed

    Mao, Yuan; Tipton, Jeremiah D; Blakney, Greg T; Hendrickson, Christopher L; Marshall, Alan G

    2011-10-15

    Valence parity provides a way to distinguish between N-terminal and C-terminal electron capture dissociation/electron transfer dissociation (ECD/ETD) product ions based on their number of hydrogen plus nitrogen atoms determined by accurate mass measurement and forms a basis for de novo peptide sequencing. The effect of mass accuracy (0.1-1 ppm error) on c'/z(•) overlap and unique elemental composition overlap is evaluated for a database of c'/z(•) product ions each based on all possible amino acid combinations and four subset databases containing the same c' ions but with z(•) ions determined by in silico digestion with trypsin, Glu-C, Lys-C, or chymotrypsin. High mass accuracy reduces both c'/z(•) overlap and unique elemental composition overlap. Of the four proteases, trypsin offers slightly better discrimination between N- and C-terminal ECD/ETD peptides. Interestingly, unique elemental composition overlap curves for c'/c' and z(•)/z(•) peptide ions exhibit discontinuities at certain nominal masses for 0.1-1.0 ppm mass error. Also, as noted in the companion article (Polfer et al. Anal. Chem.2011, DOI: 10.1021/ac201624t), the number of ECD/ETD product ion amino acid compositions as a function of nominal mass increases exponentially with mass but with a superimposed modulation due to higher prevalence of certain elemental compositions.

  17. Evidence for field enhanced electron capture by EL2 centers in semi-insulating GaAs and the effect on GaAs radiation detectors

    SciTech Connect

    McGregor, D.S.; Rojeski, R.A.; Knoll, G.F. ); Terry, F.L. Jr.; East, J. ); Eisen, Y. )

    1994-06-15

    The performance of Schottky contact semiconductor radiation detectors fabricated from semi-insulating GaAs is highly sensitive to charged impurities and defects in the material. The observed behavior of semi-insulating GaAs Schottky barrier alpha particle detectors does not match well with models that treat the semi-insulating material as either perfectly intrinsic or as material with deep donors (EL2) of constant capture cross section compensated with shallow acceptors. We propose an explanation for the discrepancy based on enhanced capture of electrons by EL2 centers at high electric fields and the resulting formation of a quasineutral region in the GaAs. Presented is a simple model including field enhanced electron capture which shows good agreement with experimental alpha particle pulse height measurements.

  18. Detection and characterization of methionine oxidation in peptides by collision-induced dissociation and electron capture dissociation.

    PubMed

    Guan, Ziqiang; Yates, Nathan A; Bakhtiar, Ray

    2003-06-01

    Electron capture dissociation (ECD) and collision-induced dissociation (CID), the two complementary fragmentation techniques, are demonstrated to be effective in the detection and localization of the methionine sulfoxide [Met(O)] residues in peptides using Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. The presence of Met(O) can be easily recognized in the low-energy CID spectrum showing the characteristic loss of methanesulfenic acid (CH(3)SOH, 64 Da) from the side chain of Met(O). The position of Met(O) can then be localized by ECD which is capable of providing extensive peptide backbone fragmentation without detaching the labile Met(O) side chain. We studied CID and ECD of several Met(O)-containing peptides that included the 44-residue human growth hormone-releasing factor (GRF) and the human atrial natriuretic peptide (ANP). The distinction and complementarity of the two fragmentation techniques were particularly remarkable in their effects on ANP, a disulfide bond-containing peptide. While the predominant fragmentation pathway in CID of ANP was the loss of CH(3)SOH (64 Da) from the molecular ion, ECD of ANP resulted in many sequence-informative products, including those from cleavages within the disulfide-bonded cyclic structure, to allow for the direct localization of Met(O) without the typical procedures for disulfide bond reduction followed by [bond]SH alkylation.

  19. Electron Capture Dissociation of Sodium-Adducted Peptides on a Modified Quadrupole/Time-of-Flight Mass Spectrometer.

    PubMed

    Voinov, Valery G; Hoffman, Peter D; Bennett, Samuel E; Beckman, Joseph S; Barofsky, Douglas F

    2015-12-01

    Electron capture dissociation (ECD), which generally preserves the position of labile post-translational modifications, can be a powerful method for de novo sequencing of proteins and peptides. In this report, ECD product-ion mass spectra of singly and doubly sodiated, nonphosphorylated, and phosphorylated peptides are presented and compared with the ECD mass spectra of their protonated counterparts. ECD of doubly charged, singly sodiated peptides yielded essentially the same sequence information as was produced by the corresponding doubly protonated peptides. The presence of several sodium binding sites on the polypeptide backbone, however, resulted in more complicated spectra. This situation is aggravated by the zwitterionic equilibrium of the free acid peptide precursors. The product-ion spectra of doubly and triply charged peptides possessing two sodium ions were further complicated by the existence of isomers created by the differential distribution of sodium binding sites. Triply charged, phosphorylated precursors containing one sodium, wherein the sodium is attached exclusively to the PO4 group, were found to be as useful for sequence analysis as the fully protonated species. Although sodium adducts are generally minimized during sample preparation, it appears that they can nonetheless provide useful sequence information. Additionally, they enable straightforward identification of a peptide's charge state, even on low-resolution instruments. The experiments were carried out using a radio frequency-free electromagnetostatic cell retrofitted into the collision-induced dissociation (CID) section of a hybrid quadrupole/time-of-flight tandem mass spectrometer. Graphical Abstract ᅟ.

  20. On decay constants and orbital distance to the Sun—part III: beta plus and electron capture decay

    NASA Astrophysics Data System (ADS)

    Pommé, S.; Stroh, H.; Paepen, J.; Van Ammel, R.; Marouli, M.; Altzitzoglou, T.; Hult, M.; Kossert, K.; Nähle, O.; Schrader, H.; Juget, F.; Bailat, C.; Nedjadi, Y.; Bochud, F.; Buchillier, T.; Michotte, C.; Courte, S.; van Rooy, M. W.; van Staden, M. J.; Lubbe, J.; Simpson, B. R. S.; Fazio, A.; De Felice, P.; Jackson, T. W.; Van Wyngaardt, W. M.; Reinhard, M. I.; Golya, J.; Bourke, S.; Roy, T.; Galea, R.; Keightley, J. D.; Ferreira, K. M.; Collins, S. M.; Ceccatelli, A.; Verheyen, L.; Bruggeman, M.; Vodenik, B.; Korun, M.; Chisté, V.; Amiot, M.-N.

    2017-02-01

    The hypothesis that seasonal changes in proximity to the Sun cause variation of decay constants at permille level has been tested for radionuclides disintegrating through electron capture and beta plus decay. Activity measurements of 22Na, 54Mn, 55Fe, 57Co, 65Zn, 82+85Sr, 90Sr, 109Cd, 124Sb, 133Ba, 152Eu, and 207Bi sources were repeated over periods from 200 d up to more than four decades at 14 laboratories across the globe. Residuals from the exponential nuclear decay curves were inspected for annual oscillations. Systematic deviations from a purely exponential decay curve differ from one data set to another and appear attributable to instabilities in the instrumentation and measurement conditions. Oscillations in phase with Earth’s orbital distance to the sun could not be observed within 10-4-10-5 range precision. The most stable activity measurements of β + and EC decaying sources set an upper limit of 0.006% or less to the amplitude of annual oscillations in the decay rate. There are no apparent indications for systematic oscillations at a level of weeks or months.

  1. Hollow-fiber solvent bar microextraction with gas chromatography and electron capture detection determination of disinfection byproducts in water samples.

    PubMed

    Correa, Liliana; Fiscal, Jhon Alex; Ceballos, Sandra; de la Ossa, Alberto; Taborda, Gonzalo; Nerin, Cristina; Rosero-Moreano, Milton

    2015-09-10

    A liquid-phase microextraction method that uses a hollow-fiber solvent bar microextraction technique was developed by combining gas chromatography with electron capture detection for the analysis of four trihalomethanes (chloroform, dichlorobromomethane, chlorodibromomethane, and bromoform) in drinking water. In the microextraction process, 1-octanol was used as the solvent. The technique operates in a two-phase mode with a 5 min extraction time, a 700 rpm stirring speed, a 30°C extraction temperature, and NaCl concentration of 20%. After microextraction, one edge of the membrane was cut, and 1 μL of solvent was collected from the membrane using a 10 μL syringe. The solvent sample was directly injected into the gas chromatograph. The analytical characteristics of the developed method were as follows: detection limits, 0.017-0.037 ng mL(-1) ; linear working range, 10-900 ng mL(-1) ; recovery, 74 ± 9-91 ± 2; relative standard deviation, 5.7-10.3; and enrichment factor, 330-455. A simple, fast, economic, selective, and efficient method with big possibilities for automation was developed with a potential use to apply with other matrices and analytes.

  2. Determination of pyrimidine dimers in DNA by high-performance liquid chromatography/gas chromatography and electron capture detection

    SciTech Connect

    Ramsey, R.S.; Ho, C. )

    1989-11-01

    Exposure of DNA to uv radiation results in the formation of a number of photoproducts including the cyclobutyl pyrimidine dimers. At low uv fluences the concentrations of these dimeric compounds are only a small fraction of the corresponding DNA pyrimidine concentration (e.g., as low as 0.02% or less of the total thymine content). Sensitive methods of analysis are therefore required for accurate determinations. Analytical methodology based upon HPLC fractionation and electrophore labeling followed by GC/electron capture detection (ECD) has been developed to quantitate these species. Separation of thymine-thymine, thymine-uracil, and uracil-uracil from the monomeric bases and from other constituents present in acid-hydrolyzed DNA is achieved by reversed-phase HPLC. Isolation of the dimeric fractions is followed by off-line derivatization to form pentafluorobenzyl products for analysis by GC/ECD. All active hydrogens are alkylated, yielding products with high response factors and detection limits in the low femtomole range. The overall analytical scheme for the determination of pyrimidine dimers in DNA is presented.

  3. Electron Capture Dissociation of Divalent Metal-adducted Sulfated N-Glycans Released from Bovine Thyroid Stimulating Hormone

    NASA Astrophysics Data System (ADS)

    Zhou, Wen; Håkansson, Kristina

    2013-11-01

    Sulfated N-glycans released from bovine thyroid stimulating hormone (bTSH) were ionized with the divalent metal cations Ca2+, Mg2+, and Co by electrospray ionization (ESI). These metal-adducted species were subjected to infrared multiphoton dissociation (IRMPD) and electron capture dissociation (ECD) and the corresponding fragmentation patterns were compared. IRMPD generated extensive glycosidic and cross-ring cleavages, but most product ions suffered from sulfonate loss. Internal fragments were also observed, which complicated the spectra. ECD provided complementary structural information compared with IRMPD, and all observed product ions retained the sulfonate group, allowing sulfonate localization. To our knowledge, this work represents the first application of ECD towards metal-adducted sulfated N-glycans released from a glycoprotein. Due to the ability of IRMPD and ECD to provide complementary structural information, the combination of the two strategies is a promising and valuable tool for glycan structural characterization. The influence of different metal ions was also examined. Calcium adducts appeared to be the most promising species because of high sensitivity and ability to provide extensive structural information.

  4. Mapping a Noncovalent Protein-Peptide Interface by Top-Down FTICR Mass Spectrometry Using Electron Capture Dissociation

    NASA Astrophysics Data System (ADS)

    Clarke, David J.; Murray, Euan; Hupp, Ted; Mackay, C. Logan; Langridge-Smith, Pat R. R.

    2011-08-01

    Noncovalent protein-ligand and protein-protein complexes are readily detected using electrospray ionization mass spectrometry (ESI MS). Furthermore, recent reports have demonstrated that careful use of electron capture dissociation (ECD) fragmentation allows covalent backbone bonds of protein complexes to be dissociated without disruption of noncovalent protein-ligand interactions. In this way the site of protein-ligand interfaces can be identified. To date, protein-ligand complexes, which have proven tractable to this technique, have been mediated by ionic electrostatic interactions, i.e., ion pair interactions or salt bridging. Here we extend this methodology by applying ECD to study a protein-peptide complex that contains no electrostatics interactions. We analyzed the complex between the 21 kDa p53-inhibitor protein anterior gradient-2 and its hexapeptide binding ligand (PTTIYY). ECD fragmentation of the 1:1 complex occurs with retention of protein-peptide binding and analysis of the resulting fragments allows the binding interface to be localized to a C-terminal region between residues 109 and 175. These finding are supported by a solution-phase competition assay, which implicates the region between residues 108 and 122 within AGR2 as the PTTIYY binding interface. Our study expands previous findings by demonstrating that top-down ECD mass spectrometry can be used to determine directly the sites of peptide-protein interfaces. This highlights the growing potential of using ECD and related top-down fragmentation techniques for interrogation of protein-protein interfaces.

  5. Resonance conditions for Mom93 isomer depletion via nuclear excitation by electron capture in a beam-based scenario

    NASA Astrophysics Data System (ADS)

    Polasik, M.; Słabkowska, K.; Carroll, J. J.; Chiara, C. J.; Syrocki, Ł.; WÈ©der, E.; Rzadkiewicz, J.

    2017-03-01

    We present here a comprehensive analysis to understand the optimal atomic conditions for the first experimental observation of nuclear excitation by electron capture (NEEC) for the 6.85 h Mom93 isomer with spin parity 21 /2+ . The NEEC process would provide an excitation from the long-lived isomer to a depletion level with spin parity 17 /2+ , which lies only 4.85 keV higher in energy, and is itself a shorter-lived isomer that subsequently decays, releasing a substantial amount of stored energy (2429.8 keV). The depletion level decays to a 13 /2+ state through a 267.9-keV transition that offers the opportunity for identification of NEEC because it does not occur in the natural decay of the long-lived isomer. It has been shown that, for the proposed approach, high-precision atomic predictions are essential to understanding the proper physical conditions under which the experimental observation of the NEEC process will be possible using a beam-based scenario.

  6. Low-Energy Nuclear Reactions Resulting as Picometer Interactions with Similarity to K-Shell Electron Capture

    NASA Astrophysics Data System (ADS)

    Hora, H.; Miley, G. H.; Li, X. Z.; Kelly, J. C.; Osman, F.

    2006-02-01

    Since the appeal by Brian Josephson at the meeting of the Nobel Laureates July 2004, it seems to be indicated to summarize the following serious, reproducible and confirmed observations on reactions of protons or deuterons incorporated in host metals such as palladium. Some reflections to Rutherford's discovery of nuclear physics, the Cockroft-Oliphant discovery of anomalous low-energy fusion reactions and the chemist Hahn's discovery of fission had to be included. Using gaseous atmosphere or discharges between palladium targets, rather significant results were seen e.g. from the "life after death" heat production of such high values per host atom that only nuclear reactions can be involved. This supports the earlier evaluation of neutron generation in fully reversible experiments with gas discharges hinting that a reasonable screening effect - preferably in the swimming electron layer - may lead to reactions at nuclear distances d of picometers with reaction probability times U of about megaseconds similar to the K-shell capture radioactivity. Further electrolytic experiments led to low-energy nuclear reactions (LENR) where the involvement of pollution could be excluded from the appearance of very seldom rare earth elements. A basically new theory for DD cross-sections is used to confirm the picometer-megasecond reactions of cold fusion. Other theoretical aspects are given from measured heavy element distributions similar to the standard abundance distribution, SAD, in the Universe with consequences on endothermic heavy nuclei generation, magic numbers and to quark-gluon plasmas.

  7. Electron Capture Dissociation of Sodium-Adducted Peptides on a Modified Quadrupole/Time-of-Flight Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Voinov, Valery G.; Hoffman, Peter D.; Bennett, Samuel E.; Beckman, Joseph S.; Barofsky, Douglas F.

    2015-12-01

    Electron capture dissociation (ECD), which generally preserves the position of labile post-translational modifications, can be a powerful method for de novo sequencing of proteins and peptides. In this report, ECD product-ion mass spectra of singly and doubly sodiated, nonphosphorylated, and phosphorylated peptides are presented and compared with the ECD mass spectra of their protonated counterparts. ECD of doubly charged, singly sodiated peptides yielded essentially the same sequence information as was produced by the corresponding doubly protonated peptides. The presence of several sodium binding sites on the polypeptide backbone, however, resulted in more complicated spectra. This situation is aggravated by the zwitterionic equilibrium of the free acid peptide precursors. The product-ion spectra of doubly and triply charged peptides possessing two sodium ions were further complicated by the existence of isomers created by the differential distribution of sodium binding sites. Triply charged, phosphorylated precursors containing one sodium, wherein the sodium is attached exclusively to the PO4 group, were found to be as useful for sequence analysis as the fully protonated species. Although sodium adducts are generally minimized during sample preparation, it appears that they can nonetheless provide useful sequence information. Additionally, they enable straightforward identification of a peptide's charge state, even on low-resolution instruments. The experiments were carried out using a radio frequency-free electromagnetostatic cell retrofitted into the collision-induced dissociation (CID) section of a hybrid quadrupole/time-of-flight tandem mass spectrometer.

  8. Probing the Gaseous Structure of a β-Hairpin Peptide with H/D Exchange and Electron Capture Dissociation

    NASA Astrophysics Data System (ADS)

    Straus, Rita N.; Jockusch, Rebecca A.

    2017-02-01

    An improved understanding of the extent to which native protein structure is retained upon transfer to the gas phase promises to enhance biological mass spectrometry, potentially streamlining workflows and providing fundamental insights into hydration effects. Here, we investigate the gaseous conformation of a model β-hairpin peptide using gas-phase hydrogen-deuterium (H/D) exchange with subsequent electron capture dissociation (ECD). Global gas-phase H/D exchange levels, and residue-specific exchange levels derived from ECD data, are compared among the wild type 16-residue peptide GB1p and several variants. High protection from H/D exchange observed for GB1p, but not for a truncated version, is consistent with the retention of secondary structure of GB1p in the gas phase or its refolding into some other compact structure. Four alanine mutants that destabilize the hairpin in solution show levels of protection similar to that of GB1p, suggesting collapse or (re)folding of these peptides upon transfer to the gas phase. These results offer a starting point from which to understand how a key secondary structural element, the β-hairpin, is affected by transfer to the gas phase. This work also demonstrates the utility of a much-needed addition to the tool set that is currently available for the investigation of the gaseous conformation of biomolecules, which can be employed in the future to better characterize gaseous proteins and protein complexes.

  9. Finite Forward Acceptance Angles for Single Electron Capture by ^3He^2+ Ions in He and H_2

    NASA Astrophysics Data System (ADS)

    Mawhorter, Rj; Greenwood, J.; Smith; Chutjian, A.

    2004-05-01

    Perhaps surprisingly, electron capture scattering angles of a few degrees or more are observed for slow ions impacting light targets. Gas cells must be designed with this in mind. Indeed the difference between small acceptance angle results(W.L. Nutt, et al., J. Phys. B 8), 1457 (1978) and the larger acceptance-angle studies of both Kusakabe, et al.(T. Kusakabe, et al., J. Phys. Soc. Japan 59), 1218 (1990) and our group at JPL (presented here; energy range 0.33-4.67 keV/amu) for ^3He^2+ in H2 can be ascribed to this effect. Olson and Kimura(R. E. Olson and M. Kimura, J. Phys. B 15), 4231 (1982) have modeled the problem theoretically. We use existing differential cross section data(D. Bordenave-Montesquieu and R. Dagnac, J. Phys. B 27), 543 1994) for both H_2/ D2 and ^4He targets to calculate realistic acceptance angles. The resulting small total cross section corrections provide reliable absolute results for these benchmark systems. This work was carried out at JPL/Caltech, and was supported through agreement with NASA.

  10. EVALUATION OF N-METHYL-N-TERT-BUTYLDIMETHYLSILYLTRIFLUOROACETAMIDE FOR ENVIRONMENTAL ANALYSIS UNDER BOTH EIMS AND ELECTRON CAPTURE NICIMS CONDITIONS AND COMPARISON TO TRIMETHYLSILYL REAGENTS UNDER EIMS

    EPA Science Inventory

    Sewage effluent was analyzed for 3,5,6-trichloropyridinol (TCP) by extracting one liter of water using liquid-liquid extraction and determined by GC/MS operated in the negative ion chemical ionization (electron capture) mode, TCP is the major metabolite of the commonly used insec...

  11. The Use of Electronic Data Capture Tools in Clinical Trials: Web-Survey of 259 Canadian Trials

    PubMed Central

    Jonker, Elizabeth; Sampson, Margaret; Krleža-Jerić, Karmela; Neisa, Angelica

    2009-01-01

    Background Electronic data capture (EDC) tools provide automated support for data collection, reporting, query resolution, randomization, and validation, among other features, for clinical trials. There is a trend toward greater adoption of EDC tools in clinical trials, but there is also uncertainty about how many trials are actually using this technology in practice. A systematic review of EDC adoption surveys conducted up to 2007 concluded that only 20% of trials are using EDC systems, but previous surveys had weaknesses. Objectives Our primary objective was to estimate the proportion of phase II/III/IV Canadian clinical trials that used an EDC system in 2006 and 2007. The secondary objectives were to investigate the factors that can have an impact on adoption and to develop a scale to assess the extent of sophistication of EDC systems. Methods We conducted a Web survey to estimate the proportion of trials that were using an EDC system. The survey was sent to the Canadian site coordinators for 331 trials. We also developed and validated a scale using Guttman scaling to assess the extent of sophistication of EDC systems. Trials using EDC were compared by the level of sophistication of their systems. Results We had a 78.2% response rate (259/331) for the survey. It is estimated that 41% (95% CI 37.5%-44%) of clinical trials were using an EDC system. Trials funded by academic institutions, government, and foundations were less likely to use an EDC system compared to those sponsored by industry. Also, larger trials tended to be more likely to adopt EDC. The EDC sophistication scale had six levels and a coefficient of reproducibility of 0.901 (P< .001) and a coefficient of scalability of 0.79. There was no difference in sophistication based on the funding source, but pediatric trials were likely to use a more sophisticated EDC system. Conclusion The adoption of EDC systems in clinical trials in Canada is higher than the literature indicated: a large proportion of

  12. Analytical Method for the Detection of Ozone Depleting Chemicals (ODC) in Commercial Products Using a Gas Chromatograph with an Electron Capture Detector (GC-ECD)

    SciTech Connect

    Lee, Richard N.; Dockendorff, Brian P.; Wright, Bob W.

    2008-08-01

    This document describes an analytical procedure that was developed for the trace level detection of residual ozone depleting chemicals (ODC) associated with the manufacture of selected commercial products. To ensure the United States meets it obligation under the Montreal Protocol, Congress enacted legislation in 1989 to impose an excise tax on electronic goods imported into the United States that were produced with banned chemicals. This procedure was developed to technically determine if residual ODC chemicals could be detected on electronic circuit boards. The analytical method utilizes a “purge and trap” technique followed by gas chromatography with electron capture detection to capture and analyze the volatile chemicals associated with the matrix. The method describes the procedure, the hardware, operating conditions, calibration, and quality control measures in sufficient detail to allow the capability to be replicated. This document corresponds to internal Standard Operating Procedure (SOP) EFL-130A, Rev 4.

  13. ELECTRON-CAPTURE AND β-DECAY RATES FOR sd-SHELL NUCLEI IN STELLAR ENVIRONMENTS RELEVANT TO HIGH-DENSITY O–NE–MG CORES

    SciTech Connect

    Suzuki, Toshio; Toki, Hiroshi; Nomoto, Ken’ichi

    2016-02-01

    Electron-capture and β-decay rates for nuclear pairs in the sd-shell are evaluated at high densities and high temperatures relevant to the final evolution of electron-degenerate O–Ne–Mg cores of stars with initial masses of 8–10 M{sub ⊙}. Electron capture induces a rapid contraction of the electron-degenerate O–Ne–Mg core. The outcome of rapid contraction depends on the evolutionary changes in the central density and temperature, which are determined by the competing processes of contraction, cooling, and heating. The fate of the stars is determined by these competitions, whether they end up with electron-capture supernovae or Fe core-collapse supernovae. Since the competing processes are induced by electron capture and β-decay, the accurate weak rates are crucially important. The rates are obtained for pairs with A = 20, 23, 24, 25, and 27 by shell-model calculations in the sd-shell with the USDB Hamiltonian. Effects of Coulomb corrections on the rates are evaluated. The rates for pairs with A = 23 and 25 are important for nuclear Urca processes that determine the cooling rate of the O–Ne–Mg core, while those for pairs with A = 20 and 24 are important for the core contraction and heat generation rates in the core. We provide these nuclear rates at stellar environments in tables with fine enough meshes at various densities and temperatures for studies of astrophysical processes sensitive to the rates. In particular, the accurate rate tables are crucially important for the final fates of not only O–Ne–Mg cores but also a wider range of stars, such as C–O cores of lower-mass stars.

  14. Trace analysis of multi-class pesticide residues in Chinese medicinal health wines using gas chromatography with electron capture detection

    PubMed Central

    Kong, Wei-Jun; Liu, Qiu-Tao; Kong, Dan-Dan; Liu, Qian-Zhen; Ma, Xin-Ping; Yang, Mei-Hua

    2016-01-01

    A method is described for multi-residue, high-throughput determination of trace levels of 22 organochlorine pesticides (OCPs) and 5 pyrethroid pesticides (PYPs) in Chinese medicinal (CM) health wines using a QuEChERS (quick, easy, cheap, effective, rugged, and safe) based extraction method and gas chromatography-electron capture detection (GC-ECD). Several parameters were optimized to improve preparation and separation time while still maintaining high sensitivity. Validation tests of spiked samples showed good linearities for 27 pesticides (R = 0.9909–0.9996) over wide concentration ranges. Limits of detection (LODs) and quantification (LOQs) were measured at ng/L levels, 0.06–2 ng/L and 0.2–6 ng/L for OCPs and 0.02–3 ng/L and 0.06–7 ng/L for PYPs, respectively. Inter- and intra-day precision tests showed variations of 0.65–9.89% for OCPs and 0.98–13.99% for PYPs, respectively. Average recoveries were in the range of 47.74–120.31%, with relative standard deviations below 20%. The developed method was then applied to analyze 80 CM wine samples. Beta-BHC (Benzene hexachloride) was the most frequently detected pesticide at concentration levels of 5.67–31.55 mg/L, followed by delta-BHC, trans-chlordane, gamma-BHC, and alpha-BHC. The validated method is simple and economical, with adequate sensitivity for trace levels of multi-class pesticides. It could be adopted by laboratories for this and other types of complex matrices analysis. PMID:26883080

  15. Supernova Explosions of Super-asymptotic Giant Branch Stars: Multicolor Light Curves of Electron-capture Supernovae

    NASA Astrophysics Data System (ADS)

    Tominaga, Nozomu; Blinnikov, Sergei I.; Nomoto, Ken'ichi

    2013-07-01

    An electron-capture supernova (ECSN) is a core-collapse supernova (CCSN) explosion of a super-asymptotic giant branch (SAGB) star with a main-sequence mass M MS ~ 7-9.5 M ⊙. The explosion takes place in accordance with core bounce and subsequent neutrino heating and is a unique example successfully produced by first-principle simulations. This allows us to derive a first self-consistent multicolor light curve of a CCSN. Adopting the explosion properties derived by the first-principle simulation, i.e., the low explosion energy of 1.5 × 1050 erg and the small 56Ni mass of 2.5 × 10-3 M ⊙, we perform a multi-group radiation hydrodynamics calculation of ECSNe and present multicolor light curves of ECSNe of SAGB stars with various envelope masses and hydrogen abundances. We demonstrate that a shock breakout has a peak luminosity of L ~ 2 × 1044 erg s-1 and can evaporate circumstellar dust up to R ~ 1017 cm for the case of carbon dust, that the plateau luminosity and plateau duration of ECSNe are L ~ 1042 erg s-1 and t ~ 60-100 days, respectively, and that a plateau is followed by a tail with a luminosity drop by ~4 mag. The ECSN shows a bright and short plateau that is as bright as typical Type II plateau supernovae, and a faint tail that might be influenced by the spin-down luminosity of a newborn pulsar. Furthermore, the theoretical models are compared with ECSN candidates: SN 1054 and SN 2008S. We find that SN 1054 shares the characteristics of the ECSNe. For SN 2008S, we find that its faint plateau requires an ECSN model with a significantly low explosion energy of E ~ 1048 erg.

  16. Trace analysis of multi-class pesticide residues in Chinese medicinal health wines using gas chromatography with electron capture detection

    NASA Astrophysics Data System (ADS)

    Kong, Wei-Jun; Liu, Qiu-Tao; Kong, Dan-Dan; Liu, Qian-Zhen; Ma, Xin-Ping; Yang, Mei-Hua

    2016-02-01

    A method is described for multi-residue, high-throughput determination of trace levels of 22 organochlorine pesticides (OCPs) and 5 pyrethroid pesticides (PYPs) in Chinese medicinal (CM) health wines using a QuEChERS (quick, easy, cheap, effective, rugged, and safe) based extraction method and gas chromatography-electron capture detection (GC-ECD). Several parameters were optimized to improve preparation and separation time while still maintaining high sensitivity. Validation tests of spiked samples showed good linearities for 27 pesticides (R = 0.9909–0.9996) over wide concentration ranges. Limits of detection (LODs) and quantification (LOQs) were measured at ng/L levels, 0.06–2 ng/L and 0.2–6 ng/L for OCPs and 0.02–3 ng/L and 0.06–7 ng/L for PYPs, respectively. Inter- and intra-day precision tests showed variations of 0.65–9.89% for OCPs and 0.98–13.99% for PYPs, respectively. Average recoveries were in the range of 47.74–120.31%, with relative standard deviations below 20%. The developed method was then applied to analyze 80 CM wine samples. Beta-BHC (Benzene hexachloride) was the most frequently detected pesticide at concentration levels of 5.67–31.55 mg/L, followed by delta-BHC, trans-chlordane, gamma-BHC, and alpha-BHC. The validated method is simple and economical, with adequate sensitivity for trace levels of multi-class pesticides. It could be adopted by laboratories for this and other types of complex matrices analysis.

  17. Anatomical mercury speciation in bay scallops by thio-bearing chelating resin concentration and GC-electron capture detector determination.

    PubMed

    Zhang, Qihua; Yang, Guipeng

    2014-01-01

    The highly toxic methyl-, ethyl- and phenylmercury species that may exist in the three main anatomical parts - the adductor muscle, the mantle and the visceral mass - of bay scallops (Argopecten irradias) were quantitatively released by cupric chloride, zinc acetate, sodium chloride and hydrochloric acid (HCl) under ultrasonic extraction. After centrifugation, the mercury species in the supernatant were concentrated by thio (SH)-bearing chelating resins, eluted with HClO4 and HCl and extracted with toluene. Separation was achieved by capillary GC equipped with programmed temperatures, a constant nitrogen flow and detected by a micro-electron capture detector (μECD). Under optimised conditions, the LODs for methyl-, ethyl- and phenylmercury in bay scallop samples were 1.1, 0.65 and 0.80 ng g(-1), respectively. The maximum RSD for three replicate determinations of methyl-, ethyl- and phenylmercury in bay scallop samples were 13.7%, 14.0% and 11.2%, respectively. In the concentration range of 4-200 ng g(-1) in bay scallop samples, the calibration graphs were linear with correlation coefficients not less than 0.997. Recoveries for spiked samples were in the range of 92.7-103.5% (methylmercury), 87.5-108.3% (ethylmercury) and 91.6-106.0% (phenylmercury), respectively. The method was verified by the determination of methylmercury in a CRM GBW10029 (Total Mercury and Methyl Mercury in Fish Tissue), with results in good agreement with the certified values. Methylmercury - the only existing species in bay scallops - was successfully determined by the method.

  18. Determination of volatile chlorinated hydrocarbons in water samples by static headspace gas chromatography with electron capture detection.

    PubMed

    Li, Tiejun; Guo, Yuanming; Hu, Hongmei; Zhang, Xiaoning; Jin, Yanjian; Zhang, Xiaojun; Zhang, Yurong

    2016-01-01

    A simple, efficient, solvent-free, and commercial readily available approach for determination of five volatile chlorinated hydrocarbons in water samples using the static headspace sampling and gas chromatography with electron capture detection has been described. The proposed static headspace sampling method was initially optimized and the optimum experimental conditions found were 10 mL water sample containing 20% w/v sodium chloride placed in a 20 mL vial and stirred at 50ºC for 20 min. The linearity of the method was in the range of 1.2-240 μg/L for dichloromethane, 0.2-40 μg/L for trichloromethane, 0.005-1 μg/L for perchloromethane, 0.025-5 μg/L for trichloroethylene, and 0.01-2 μg/L for perchloroethylene, with coefficients of determination ranging between 0.9979 and 0.9990. The limits of detection were in the low μg/L level, ranging between 0.001 and 0.3 μg/L. The relative recoveries of spiked five volatile chlorinated hydrocarbons with external calibration method at different concentration levels in pure, tap, sea water of Jiaojiang Estuary, and sea water of waters of Xiaomendao were in the range of 91-116, 96-105, 86-112, and 80-111%, respectively, and with relative standard deviations of 1.9-3.6, 2.3-3.5, 1.5-2.7, and 2.3-3.7% (n = 5), respectively. The performance of the proposed method was compared with traditional liquid-liquid extraction on the real water samples (i.e., pure, tap, and sea water, etc.) and comparable efficiencies were obtained. It is concluded that this method can be successfully applied for the determination of volatile chlorinated hydrocarbons in different water samples.

  19. Determination of chlorobenzenes in pure, tap, and sea water by static headspace gas chromatography-electron capture detection.

    PubMed

    Hu, Hongmei; Sun, Xiumei; Zhong, Zhi; Chen, Xuechang; Zhang, Xiaoning; Guo, Yuanming

    2012-11-01

    A simple, efficient, solvent-free, and commercial readily available approach for determination of 11 chlorobenzenes (CBs) in water samples using the static headspace (HS) sampling and gas chromatography-electron capture detector has been described. The proposed static HS sampling method was initially optimized and the optimum experimental conditions found were 10 mL water sample containing 20% (w/v) sodium chloride placed in a 20 mL vial and stirred at 70°C for 30 min. The linearity of the method ranged from 0.16 to 8.0 μg/L for dichlorobenzene isomers, 0.0176~0.88 μg/L for trichlorobenzene isomers, 0.004~0.2 μg/L for tetrachlorobenzene isomers, and from 0.001 to 0.05 μg/L for pentachlorobenzene and hexachlorobenzene, with correlation coefficients ranging between 0.9992 and 0.9999. The limits of detection were in the low μg/L level, ranging between 0.0002 and 0.04 μg/L. The relative recoveries of spiked CBs with external calibration or standard addition method at different concentration levels in pure, tap, and sea water samples were 83~116%, 89~108%, and 93~112%, respectively, and with relative standard deviations of 1.9~6.3%, 1.6~5.4%, and 2.5~5.7% (n = 5), respectively. It is concluded that this method can be successfully applied for the determination of CBs in pure, tap, and sea water samples.

  20. Single and double electron capture from He by Ar{sup 16+} studied using cold-target recoil-ion momentum spectroscopy

    SciTech Connect

    Abdallah, M.A.; Wolff, W.; Wolf, H.E.; Kamber, E.Y.; Stoeckli, M.; Cocke, C.L.

    1998-10-01

    Single and double electron capture from He targets by Ar{sup 16+} ions have been studied at projectile velocities from 0.3 to 1.5 a.u. Cold-target recoil-ion momentum spectroscopy was used to record the energy gain and scattering angle simultaneously. For single capture, the reaction window is found to spread in width approximately as the square root of the projectile velocity and to shift slightly toward smaller energy-gain values as the velocity increases. The angular distributions center at the half Coulomb angle over most of the velocity range covered, but differ in shape from multichannel Landau-Zener model results. For double capture, transfer ionization dominates and feeds primarily n-symmetric states, where {ital n} is the principal quantum number. True double capture feeds mainly n-asymmetric states. The angular distributions for double capture lie outside the half Coulomb angle, indicating the importance of two-step processes in populating doubly excited states. {copyright} {ital 1998} {ital The American Physical Society}

  1. Rapid differentiation of the major causative agents of bacterial meningitis by use of frequency-pulsed electron capture gas-liquid chromatograph: analysis of acids.

    PubMed

    Brooks, J B; Kellogg, D S; Shepherd, M E; Alley, C C

    1980-01-01

    The major causative agents of bacterial meningitis, Haemophilus influenzae serogroup B, Neisseria meningitidis serogroups B and C, Klebsiella pneumoniae, Streptococcus pneumoniae, and two types of Escherichia coli, were cultured in a modified chemically defined Catlin medium and in a commercial version of the unmodified Catlin medium. The spent media were extracted under acidic conditions, and electron-capturing derivatives were prepared by derivatization with trichloroethanol or haptafluorobutyric anhydride. The derivatives were analyzed on a gas chromatograph equipped with a frequency-pulsed electron capture detector and a PEP-2 computer. The data obtained from the study show that these organisms can be easily distinguished from each other on the basis of metabolic products detected in either type of medium. Three different metabolic groups were detected within two serogroups of N. meningitidis. The methods are practical, and the new technique should offer clinical laboratories and hospitals a better method for rapid identification of this important group of pathogens.

  2. Excited states in the doubly odd 168Lu nucleus fed by electron-capture decay of 168Hf (T1/2=25.95 min)

    NASA Astrophysics Data System (ADS)

    Barci, V.; Ardisson, G.; Trubert, D.; Hussonnois, M.

    1997-05-01

    The low-spin levels of the odd-odd nucleus 168Lu from 168Hf (T1/2=25.95 min) electron-capture decay were investigated by direct γ and γ-γ coincidence measurements. The sources of 168Hf were produced with the 156Gd(16O,4n) reaction and radiochemically separated using chromatographic methods. A level scheme of 39 new levels in the 168Lu nucleus was proposed, accounting for 107 of 119 observed γ transitions assigned to 168Hf electron-capture decay. Transition multipolarities, level-spins, and parities were deduced or proposed. A tentative decay scheme was proposed. Level structure was discussed in the framework of the particle-rotor and Nilsson models.

  3. Validation of a new hand-held electronic data capture method for continuous monitoring of subjective appetite sensations

    PubMed Central

    2011-01-01

    Background When large scale trials are investigating the effects of interventions on appetite, it is paramount to efficiently monitor large amounts of human data. The original hand-held Electronic Appetite Ratings System (EARS) was designed to facilitate the administering and data management of visual analogue scales (VAS) of subjective appetite sensations. The purpose of this study was to validate a novel hand-held method (EARS II (HP® iPAQ)) against the standard Pen and Paper (P&P) method and the previously validated EARS. Methods Twelve participants (5 male, 7 female, aged 18-40) were involved in a fully repeated measures design. Participants were randomly assigned in a crossover design, to either high fat (>48% fat) or low fat (<28% fat) meal days, one week apart and completed ratings using the three data capture methods ordered according to Latin Square. The first set of appetite sensations was completed in a fasted state, immediately before a fixed breakfast. Thereafter, appetite sensations were completed every thirty minutes for 4h. An ad libitum lunch was provided immediately before completing a final set of appetite sensations. Results Repeated measures ANOVAs were conducted for ratings of hunger, fullness and desire to eat. There were no significant differences between P&P compared with either EARS or EARS II (p > 0.05). Correlation coefficients between P&P and EARS II, controlling for age and gender, were performed on Area Under the Curve ratings. R2 for Hunger (0.89), Fullness (0.96) and Desire to Eat (0.95) were statistically significant (p < 0.05). Conclusions EARS II was sensitive to the impact of a meal and recovery of appetite during the postprandial period and is therefore an effective device for monitoring appetite sensations. This study provides evidence and support for further validation of the novel EARS II method for monitoring appetite sensations during large scale studies. The added versatility means that future uses of the system provides

  4. Excitation, ionization, and electron capture cross sections for collisions of Li{sup 3+} with ground state and excited hydrogen atoms

    SciTech Connect

    Murakami, I. Yan, J.; Sato, H.; Kimura, M.; Janev, R.K.; Kato, T.

    2008-03-15

    Using the available experimental and theoretical data, as well as the established cross section scaling relationships, a comprehensive cross section database for excitation, ionization and electron capture in collisions of Li{sup 3+} ions with ground state and excited hydrogen atoms has been generated. The critically assessed cross sections are represented by analytic fit functions that have the correct asymptotic behavior both at low and high collision energies. The derived cross sections are also presented in graphical form.

  5. Gamow-Teller transitions from Mg24 and their impact on the electron capture rates in the O+Ne+Mg cores of stars

    NASA Astrophysics Data System (ADS)

    Nabi, Jameel-Un; Rahman, Muneeb-Ur

    2007-03-01

    Electron captures on nuclei play an important role in the collapse of stellar core in the stages leading to a type-II supernova. Recent observations of subluminous Type II-P supernovae (e.g., 2005cs, 2003gd, 1999br) were able to rekindle the interest in 8 10 M⊙ which develop O+Ne+Mg cores. We used the proton-neutron quasiparticle random phase approximation (pn-QRPA) theory to calculate the B(GT) strength for Mg24 →Na24 and its associated electron capture rates for incorporation in simulation calculations. The calculated rates, in this article, have differences with the earlier reported shell model and Fuller, Fowler, and Newman (hereafter FN2) rates. We compared Gamow-Teller (GT) strength distribution functions and found fairly good agreement with experiment and shell model. However, the GT centroid and the total GT strength, which are useful in the calculation of electron capture rates in the core of massive presupernova stars, lead to the enhancement of our rate up to a factor of 4 compared to the shell model rates at high temperatures and densities.

  6. Kuang's Semi-Classical Formalism for Electron Capture Cross-Sections in Ion-Ion Collisions at few MeV's/nucleon: Application to ENA Modeling

    NASA Technical Reports Server (NTRS)

    Barghouty, A. F.

    2012-01-01

    Accurate estimates of electron-capture cross sections at energies relevant to energetic neutral atom (ENA) modeling (approx few MeV per nucleon) and for multi-electron ions must rely on first-principles approaches and/or detailed quantum-mechanical simulation of the collision process. Kuang's semi-classical approach offers a middle-ground, elegant and efficient way to arrive at these estimates. We shall present a sample application and current progress in applying and extending Kuang's formalism to ENA modeling.

  7. Cross sections for electron capture and excitation in collisions of Li{sup q+} (q=1, 2, 3) with atomic hydrogen

    SciTech Connect

    Liu, L.; Wang, J. G.; Li, X. Y.; Janev, R. K.

    2014-06-15

    The two-center atomic orbital close-coupling method is employed to study electron capture and excitation reactions in collisions of Li{sup q+} (q = 1-3) ions with ground state atomic hydrogen in the ion energy range from 0.1 keV/u to 300 keV/u, where u is the atomic mass unit. The interaction of the active electron with the projectile ions (Li{sup +}, Li{sup 2+}) is represented by a model potential. Total and state-selective cross sections for charge transfer and excitation processes are calculated and compared with data from other sources when available.

  8. Fe{sup 15+} dielectronic recombination and the effects of configuration interaction between resonances with different captured electron principal quantum numbers

    SciTech Connect

    Kwon, Duck-Hee; Savin, Daniel Wolf

    2011-01-15

    Dielectronic recombination (DR) of Na-like Fe{sup 15+} forming Mg-like Fe{sup 14+} via excitation of a 2l core electron has been investigated. We find that configuration interaction (CI) between DR resonances with different captured electron principal quantum numbers n can lead to a significant reduction in resonance strengths for n{>=}5. Previous theoretical work for this system has not considered this form of CI. Including it accounts for most of the discrepancy between previous theoretical and experimental results.

  9. Boundary-corrected four-body continuum-intermediate-state method: Single-electron capture from heliumlike atomic systems by fast nuclei

    NASA Astrophysics Data System (ADS)

    Mančev, Ivan; Milojević, Nenad; Belkić, Dževad

    2015-06-01

    Single charge exchange in collisions between bare projectiles and heliumlike atomic systems at intermediate and high incident energies is examined by using the four-body formalism of the first- and second-order theories. The main purpose of the present study is to investigate the relative importance of the intermediate ionization continua of the captured electron compared to the usual direct path of the single electron transfer from a target to a projectile. In order to achieve this goal, comprehensive comparisons are made between the four-body boundary-corrected continuum-intermediate-states (BCIS-4B) method and the four-body boundary-corrected first Born (CB1-4B) method. The perturbation potential is the same in the CB1-4B and BCIS-4B methods. Both methods satisfy the correct boundary conditions in the entrance and exit channels. However, unlike the CB1-4B method, the second-order BCIS-4B method takes into account the electronic Coulomb continuum-intermediate states in either the entrance or the exit channel depending on whether the post or the prior version of the transition amplitude is used. Hence, by comparing the results from these two theories, the relative importance of the intermediate ionization electronic continua can be assessed within the four-body formalism of scattering theory. The BCIS-4B method predicts the usual second-order effect through double scattering of the captured electron on two nuclei as a quantum-mechanical counterpart of the Thomas classical two-step, billiard-type collision. The physical mechanism for this effect in the BCIS-4B method is also comprised of two steps such that ionization occurs first. This is followed by capture of the electron by the projectile with both processes taking place on the energy shell. Moreover, the role of the second, noncaptured electron in a heliumlike target is revisited. To this end, the BCIS-4B method describes the effect of capture of one electron by the interaction of the projectile nucleus with

  10. Electronic capture of patient-reported and clinician-reported outcome measures in an elective orthopaedic setting: a retrospective cohort analysis

    PubMed Central

    Malhotra, Karan; Buraimoh, Olatunbosun; Thornton, James; Cullen, Nicholas; Singh, Dishan; Goldberg, Andrew J

    2016-01-01

    Objectives To determine whether an entirely electronic system can be used to capture both patient-reported outcomes (electronic Patient-Reported Outcome Measures, ePROMs) as well as clinician-validated diagnostic and complexity data in an elective surgical orthopaedic outpatient setting. To examine patients' experience of this system and factors impacting their experience. Design Retrospective analysis of prospectively collected data. Setting Single centre series. Outpatient clinics at an elective foot and ankle unit in the UK. Participants All new adult patients attending elective orthopaedic outpatient clinics over a 32-month period. Interventions All patients were invited to complete ePROMs prior to attending their outpatient appointment. At their appointment, those patients who had not completed ePROMs were offered the opportunity to complete it on a tablet device with technical support. Matched diagnostic and complexity data were captured by the treating consultant during the appointment. Outcome measures Capture rates of patient-reported and clinician-reported data. All information and technology (IT) failures, language and disability barriers were captured. Patients were asked to rate their experience of using ePROMs. The scoring systems used included EQ-5D-5L, the Manchester-Oxford Foot Questionnaire (MOxFQ) and the Visual Analogue Scale (VAS) pain score. Results Out of 2534 new patients, 2176 (85.9%) completed ePROMs, of whom 1090 (50.09%) completed ePROMs at home/work prior to their appointment. 31.5% used a mobile (smartphone/tablet) device. Clinician-reported data were captured on 2491 patients (98.3%). The mean patient experience score of using Patient-Reported Outcome Measures (PROMs) was 8.55±1.85 out of 10 and 666 patients (30.61%) left comments. Of patients leaving comments, 214 (32.13%) felt ePROMs did not adequately capture their symptoms and these patients had significantly lower patient experience scores (p<0.001). Conclusions This study

  11. Electron capture and excitation in collisions of O{sup +}({sup 4}S,{sup 2}D,{sup 2}P) with H{sub 2} molecules

    SciTech Connect

    Pichl, Lukas; Li Yan; Liebermann, Heinz-Peter; Buenker, Robert J.; Kimura, Mineo

    2004-06-01

    Using an electronic-state close-coupling method, we treated the electron capture and excitation processes of O{sup +} ions both in ground state O{sup +}({sup 4}S) and metastable states O{sup +*}({sup 2}D) and O{sup +*}({sup 2}P) in collisions with the H{sub 2} molecule. In the ground-state projectile energy region considered (from 50 eV/amu to 10 keV/amu), the experimental data vary by orders of magnitude: our results smoothly connect to the data by Flesch and Ng [J. Chem. Phys. 94, 2372 (1991)] and Xu et al. [J. Phys. B 23, 1235 (1990)] at low energy and agree with Phaneuf et al. [Phys. Rev. A 17, 534 (1978)] in the high-energy region. The present values differ from Sieglaff et al. [Phys. Rev. A 59, 3538 (1999)] and Nutt et al. [J. Phys. B 12, L157 (1979)], especially in the energy region below 1 keV/amu. We provide the first calculated state-resolved cross sections of electron capture and target-projectile electronic excitations for the O{sup +}({sup 4}S,{sup 2}D,{sup 2}P)-H{sub 2} collision system.

  12. Elastic and electron-capture processes in H{sup +}+C{sub 2}H{sub 4} collisions below the 10-keV regime

    SciTech Connect

    Suzuki, Reiko; Rai, Sachchida N.; Liebermann, Heinz-Peter; Buenker, Robert J.; Pichl, Lukas; Kimura, Mineo

    2005-03-01

    Electron capture and direct elastic scattering in collisions of H{sup +} ions with C{sub 2}H{sub 4} molecules are studied by using a molecular representation within a semiclassical as well as a fully quantum-mechanical approaches below 10 keV. Calculations are carried out at three different molecular configurations, in which H{sup +} approaches (i) parallel and (ii) perpendicular to the C=C axis in the molecular plane, and (iii) perpendicular to this plane. We find that electron capture in the (iii) configuration takes place preferentially over that in the (i) and (ii) configurations at scattering angles above 15 deg., while the results for (i) and (ii) are comparable in magnitude below 10 deg., although (ii) dominates slightly at still smaller angles. Total capture cross sections for the (iii) and (ii) configurations differ by a factor of 4 above 500 eV, while those for (i) lie between these values. Below 500 eV, the results for (i) and (iii) are similar in magnitude, while that for the (ii) configuration sharply decreases.

  13. X-ray emission cross sections following Ar{sup 18+} charge-exchange collisions on neutral argon: The role of the multiple electron capture

    SciTech Connect

    Otranto, S.; Olson, R. E.

    2011-03-15

    X-ray emission originating in charge-exchange collisions between Ar{sup 18+} and neutral argon is studied at impact energies of 5-4000 eV/amu by means of the classical trajectory Monte Carlo method (CTMC). Line emission and charge-exchange cross sections obtained from different CTMC versions based on the one-active electron approximation are contrasted among themselves and against the results obtained by means of a three-active electron code that lets us infer the role of multiple electron capture. The present results are compared to the recent experimental data available from the EBIT groups operating at Livermore, NIST, and Berlin. We were not able to reconcile the major difference in x-ray emission cross sections obtained from in situ measurements made in EBIT, versus those made in an exterior, field-free collision chamber using ions extracted from the EBIT. Our calculations support the extracted beam results.

  14. The Final Fate of Stars that Ignite Neon and Oxygen Off-center: Electron Capture or Iron Core-collapse Supernova?

    NASA Astrophysics Data System (ADS)

    Jones, Samuel; Hirschi, Raphael; Nomoto, Ken'ichi

    2014-12-01

    In the ONeMg cores of 8.8-9.5 M ⊙ stars, neon and oxygen burning is ignited off-center. Whether or not the neon-oxygen flame propagates to the center is critical for determining whether these stars undergo Fe core collapse or electron-capture-induced ONeMg core collapse. We present more details of stars that ignite neon and oxygen burning off-center. The neon flame is established in a manner similar to the carbon flame of super-AGB stars, albeit with a narrower flame width. The criteria for establishing a flame can be met if the strict Schwarzschild criterion for convective instability is adopted. Mixing across the interface of the convective shell disrupts the conditions for the propagation of the burning front, and instead the shell burns as a series of inward-moving flashes. While this may not directly affect whether or not the burning will reach the center (as in super-AGB stars), the core is allowed to contract between each shell flash. Reduction of the electron fraction in the shell reduces the Chandrasekhar mass and the center reaches the threshold density for the URCA process to activate and steer the remaining evolution of the core. This highlights the importance of a more accurate treatment of mixing in the stellar interior for yet another important question in stellar astrophysics—determining the properties of stellar evolution and supernova progenitors at the boundary between electron capture supernova and iron core-collapse supernova.

  15. Improved description of one- and two-hole excitations after electron capture in 163Ho and the determination of the neutrino mass

    NASA Astrophysics Data System (ADS)

    Faessler, Amand; Šimkovic, F.

    2015-04-01

    The atomic pair 163Ho and 163Dy , because of its small Q value of about 2.5 keV, seems to be the best pair to use to determine the neutrino mass by electron capture. The bolometer spectrum measures the full deexcitation energy of dysprosium (by x rays and Auger electrons plus the recoil of holmium, which can be neglected). The spectrum has an upper limit given by the Q value minus the neutrino mass. Till now this spectrum has been calculated in dysprosium allowing excitations with 3 s1 /2 , 3 p1 /2 , 4 s1 /2 , 4 p1 /2 , 5 s1 /2 , and 5 p1 /2 (and 6 s1 /2 ) holes only. Robertson [R. G. H. Robertson, arXiv:1411.2906v1] also recently calculated the spectrum with two-electron-hole excitations in Dy. He took the probability for the excitation for the second electron hole from the work of Carlson and Nestor [T. A. Carlson, C. W. Nestor, T. C. Tucker, and F. B. Malik, Phys. Rev. 169, 27 (1968), 10.1103/PhysRev.169.27; T. A. Carlson and C. W. Nestor, Phys. Rev. A 8, 2887 (1973) 10.1103/PhysRevA.8.2887] for Z =54 xenon. The neutrino mass must finally be obtained by a simultaneous fit of the Q value, together with the properties of the relevant resonances, and the neutrino mass to the the upper end of the spectrum. Under the assumption that only one resonance (independent of its nature: one-hole, two-hole, multihole, or of other origin) near the Q value determines the upper end of the spectrum and that the profile of this leading state is Lorentzian, one has to fit simultaneously four parameters (neutrino mass, strength, distance of the leading resonance to the Q value, and width). If more than one resonance is of comparable importance for the upper end of the spectrum, it might be difficult or even impossible to extract the neutrino mass reliably. Compared to the work of Robertson this work includes the following improvements. (i) The two-hole probabilities are calculated in the Dirac-Hartree-Fock (DHF) approach for holmium and dysprosium but not for xenon. (ii) In

  16. EPA Method 551.1: Determination of Chlorination Disinfection Byproducts, Chlorinated Solvents, and Halogenated Pesticides/Herbicides in Drinking Water by Liquid-Liquid Extraction and Gas Chromatography With Electron-Capture Detection

    EPA Pesticide Factsheets

    SAM lists this method as a gas chromatography with electron capture detection applicable to the determination of halogenated analytes in finished drinking water, drinking water during intermediate stages of treatment and raw source water.

  17. Electron capture and positron decay of /sup 206/Fr and /sup 208/Fr and the energy levels of /sup 206/Rn and /sup 208/Rn

    SciTech Connect

    Ritchie, B.G.; Avignone, F.T. III; Carter, H.K.; Mlekodaj, R.L.; Spejewski, E.H.

    1981-04-01

    The isotopes /sup 206/Fr and /sup 208/Fr were produced by the reactions Ir(/sup 20/Ne,xn)/sup 206,208/Fr and mass separated on-line. The electron-capture and positron decays to /sup 206/Rn and /sup 208/Rn were studied by collecting ..gamma.. ray and internal conversion electron singles spectra as a function of decay time as well as ..gamma..-..gamma.., ..gamma..-e/sup -/, and ..gamma..-x ray coincidence spectra. The energies and many of the spins were determined for 18 excited, even parity states in /sup 208/Rn and for 10 excited, even parity states in /sup 206/Rn. These nuclei appear to be excellent candidates for interpretation in terms of a weak coupling shell model. The energy levels were also compared to the predictions of the interacting boson approximation model.

  18. Semiclassical analysis of angular differential cross sections for single-electron capture in 250-eV H++H collisions

    NASA Astrophysics Data System (ADS)

    Frémont, F.

    2015-05-01

    A classical model based on the resolution of Hamilton equations of motion is used to determine the angular distribution of H projectiles following single-electron capture in H++H collisions at an incident projectile energy of 250 eV. At such low energies, the experimental charge-exchange probability and angular differential cross sections exhibit oscillatory structures that are classically related to the number of swaps the electron experiences between the target and the projectile during the collision. These oscillations are well reproduced by models based on quantum mechanics. In the present paper, the angular distribution of H projectiles is determined classically, at angles varying from 0.1° up to 7°. The variation in intensity due to interferences caused by the indiscernibility between different trajectories is calculated, and the role of these interferences is discussed.

  19. State-Selective Single-Electron Capture by Ne^q+ (q = 3 -- 6) Ions from H2 O and CO2

    NASA Astrophysics Data System (ADS)

    Abu-Haija, O.; Sacks, R.; Ferguson, S. M.; Kamber, E. Y.

    2005-05-01

    Using translational energy-gain spectroscopy technique, we have measured the energy-gain spectra and absolute total cross sections for single-electron capture in collisions of Ne^q+ recoil ions with H2O and CO2 at laboratory impact energies between 15 and 200 qeV (q = 3 - 6, where q is the projectile charge state) and scattering angles between 0 and 5 . The translational energy-gain spectra show that only a few final states were selectively populated depending on the charge state of the projectile. In all collision systems studied here, the dominant reaction channels are due to non-dissociative single-electron capture into excited states of the projectile product. The final state populations will be discussed on the basis of the reaction windows, which are calculated using the single-crossing Landau-Zener model and the extended version of the classical over-the-barrier model. Additional measurements of differential cross sections compared with available theoretical calculations will also be presented.

  20. Rapid differentiation of the major causative agents of bacterial meningitis by use of frequency-pulsed electron capture gas-liquid chromatography: analysis of amines.

    PubMed

    Brooks, J B; Kellogg, D S; Shepherd, M E; Alley, C C

    1980-01-01

    The major causative agents of bacterial meningitis (Haemophilus influenzae serogroup B, Neisseria meningitidis serogroups B and C, Klebsiella pneumoniae, Steptococcus pneumoniae, and two types of Escherichia coli) were cultured in a chemically defined medium, and selected strains were further studied in Todd-Hewitt medium. After acidic extraction of the spent media with chloroform, a basic extraction was made with chloroform to obtain amines. A third extraction was performed on re-acidified Todd-Hewitt medium with ethyl ether to obtain hydroxyacids. The extracts were derivatized with heptafluorobutyric anhydride-ethanol to form electron-capturing derivatives, and the derivatives were analyzed on a frequency-pulsed electron capture gas-liquid chromatograph (FPEC-GLC) equipped with a PEP-2 computer. The data obtained from the study showed that amines were produced by these organisms that formed characteristic patterns. Different serotypes of K. pneumoniae and the two serogroups of N. meningitidis produced different types of FPEC-GLC profiles within serotypes. E. coli produced several hydroxy acids on Todd-Hewitt medium that made it unique among the organisms studied. The methods used are practical and the techniques have potential for use in clinical laboratories and hospitals as a valuable aid for the rapid identification of the major causative agents of bacterial meningitis.

  1. Detection and quantitation of fatty acid acyl conjugates of triamcinolone acetonide via gas chromatography-electron-capture negative-ion mass spectrometry.

    PubMed

    Hubbard, Walter C; Blum, Andrew E; Bickel, Carol A; Heller, Nicola M; Schleimer, Robert P

    2003-11-15

    The inherent electron-capture properties of triamcinolone acetonide (TAA) fatty acid conjugates were exploited for development of a GC-MS technique for quantitation of C21 long-chain fatty esters of TAA synthesized in BEAS-2B cells, an immortalized airway epithelium cell line. TAA esters extracted from BEAS-2B cells were purified and detected via selected ion monitoring of the molecular anions generated from the TAA esters under electron-capture negative-ion mass spectrometric conditions. Standard curves were linear over a range of 0.0 to >4.5 ng/mg protein with r(2) values = 1. Levels of TAA conjugates extracted from BEAS-2B treated with 10(-5)M TAA for 24h ranged from 0.024 to 0.301 ng/mg protein. Further evidence for confirmation of the identity of TAA fatty esters formed in BEAS-2B cells was obtained via selected reaction monitoring. The transition monitored was formation of the carboxy anion generated from each of the respective molecular anions of the TAA esters during collision-induced decomposition. These findings indicate that the GC-MS analysis is suitable for studies of the kinetics of the TAA fatty acid conjugates formation in vitro and may be directly applicable to determination of the kinetics of TAA fatty acid conjugation in vivo.

  2. Measurement of low picomolar levels of triamcinolone acetonide in human bronchoalveolar lavage fluid by gas chromatography-electron-capture negative-ion mass spectrometry.

    PubMed

    Hubbard, W C; Liu, M C; Bickel, C; Argenti, D; Heald, D; Schleimer, R P

    2001-03-01

    The intense inherent electron-capture properties of the C21 acetate derivative of triamcinolone acetonide (TAA) under methane chemical ionization mass spectrometric conditions were exploited for the development of a highly sensitive and selective gas chromatography-mass spectrometric (GC-MS) technique for measurement of levels of TAA in human bronchoalveolar lavage (BAL) fluid. After the addition of 3.0 ng of a heptadeuterated analog of TAA and varying concentrations of TAA to 2-ml aliquots of BAL fluid, the deuterium and protium forms of the steroid were extracted with diethyl ether, converted to the C21 acetate derivative, and purified via adsorptive chromatography prior to GC-MS analysis. Standard curves obtained from 2-ml aliquots of BAL fluid were linear over a wide range of concentrations of TAA from 0.0 to 24,600 pg/2-ml aliquots of BAL fluid. Levels as low as 6.0 pg/ml (13.8 pmol x L(-1)) in BAL fluid can be reliably determined in 2-ml aliquots of the biological fluid with <10% error. These findings suggest that the assay method exploiting the intense electron-capture properties of TAA is highly suitable for determination of the deposition pattern and in vivo kinetics of TAA in human airways following inhalation of the steroid.

  3. THE FINAL FATE OF STARS THAT IGNITE NEON AND OXYGEN OFF-CENTER: ELECTRON CAPTURE OR IRON CORE-COLLAPSE SUPERNOVA?

    SciTech Connect

    Jones, Samuel; Hirschi, Raphael; Nomoto, Ken'ichi

    2014-12-20

    In the ONeMg cores of 8.8-9.5 M {sub ☉} stars, neon and oxygen burning is ignited off-center. Whether or not the neon-oxygen flame propagates to the center is critical for determining whether these stars undergo Fe core collapse or electron-capture-induced ONeMg core collapse. We present more details of stars that ignite neon and oxygen burning off-center. The neon flame is established in a manner similar to the carbon flame of super-AGB stars, albeit with a narrower flame width. The criteria for establishing a flame can be met if the strict Schwarzschild criterion for convective instability is adopted. Mixing across the interface of the convective shell disrupts the conditions for the propagation of the burning front, and instead the shell burns as a series of inward-moving flashes. While this may not directly affect whether or not the burning will reach the center (as in super-AGB stars), the core is allowed to contract between each shell flash. Reduction of the electron fraction in the shell reduces the Chandrasekhar mass and the center reaches the threshold density for the URCA process to activate and steer the remaining evolution of the core. This highlights the importance of a more accurate treatment of mixing in the stellar interior for yet another important question in stellar astrophysics—determining the properties of stellar evolution and supernova progenitors at the boundary between electron capture supernova and iron core-collapse supernova.

  4. Nuclear motion captured by the slow electron velocity imaging technique in the tunnelling predissociation of the S1 methylamine.

    PubMed

    Ahn, Doo-Sik; Lee, Jeongmook; Park, Young Choon; Lee, Yoon Sup; Kim, Sang Kyu

    2012-01-14

    Predissociation dynamics of methylamines (CH(3)NH(2) and CH(3)ND(2)) on the first electronically excited states are studied using the slow-electron velocity imaging method to unravel the multi-dimensional nature of the N-H(D) chemical bond dissociation reaction which occurs via tunnelling. The nearly free internal rotation around the C-N bond axis is found to be strongly coupled to the reaction pathway, revealing nuclear motions actively involved in the tunnelling process on the S(1) potential energy surfaces. The vibrational state-resolved energy and angular distributions of photoelectron, ejected from the ionization mediated by the metastable intermediate S(1) state provide a unique way for mapping the predissociative potential energy surfaces.

  5. An inadvertent capture cell for orbital debris and micrometeorites - The main electronics box thermal blanket of the solar maximum satellite

    NASA Technical Reports Server (NTRS)

    Rietmeijer, F. J. M.; Schramm, L. S.; Barrett, R. A.; Mckay, D. S.; Zook, H. A.

    1986-01-01

    The physical properties of impact features in the Solar Max main electronics box thermal blanket are consistent with hypervelocity impacts of particles in the near-earth space environment. The majority of particles are orbital debris and include spacecraft paints and bismuth-rich particles. At least 30 percent of all impact features are caused by micrometeorites, which include silicates and sulfides. Some micrometeorites survive impact with only minor shock-metamorphic effects or chemical fractionation. Currently calibration experiments are under way to relate flux to particle diameter (or mass).

  6. Difference of Electron Capture and Transfer Dissociation Mass Spectrometry on Ni2+-, Cu2+-, and Zn2+-Polyhistidine Complexes in the Absence of Remote Protons

    NASA Astrophysics Data System (ADS)

    Asakawa, Daiki; De Pauw, Edwin

    2016-07-01

    Electron capture dissociation (ECD) and electron transfer dissociation (ETD) in metal-peptide complexes are dependent on the metal cation in the complex. The divalent transition metals Ni2+, Cu2+, and Zn2+ were used as charge carriers to produce metal-polyhistidine complexes in the absence of remote protons, since these metal cations strongly bind to neutral histidine residues in peptides. In the case of the ECD and ETD of Cu2+-polyhistidine complexes, the metal cation in the complex was reduced and the recombination energy was redistributed throughout the peptide to lead a zwitterionic peptide form having a protonated histidine residue and a deprotonated amide nitrogen. The zwitterion then underwent peptide bond cleavage, producing a and b fragment ions. In contrast, ECD and ETD induced different fragmentation processes in Zn2+-polyhistidine complexes. Although the N-Cα bond in the Zn2+-polyhistidine complex was cleaved by ETD, ECD of Zn2+-polyhistidine induced peptide bond cleavage accompanied with hydrogen atom release. The different fragmentation modes by ECD and ETD originated from the different electronic states of the charge-reduced complexes resulting from these processes. The details of the fragmentation processes were investigated by density functional theory.

  7. Effect of structural parameters on the electron capture dissociation and collision-induced dissociation pathways of copper(II)-peptide complexes.

    PubMed

    Chen, Xiangfeng; Wang, Ze; Li, Wan; Wong, Y L Elaine; Chan, T-W Dominic

    2015-01-01

    The gas-phase dissociation pathways of proteins/peptides are usually affected by the nature of the charge carrier and the sequence of amino acid residues. The effects of peptide structural parameters, including peptide composition, chain length and amide hydrogen, on the gas-phase dissociation of Cu(II)-model peptide complexes were explored in this study. Polyglycine peptides with flexible frames were used as probes to reduce the complexity of the system and illustrate the mechanism. Results revealed that the types of fragment ions generated in the electron capture dissociation (ECD) of Cu(II)-adducted peptides changed according to the basic amino acid residue composition. Charged or neutral tryptophan side-chain losses were observed in the collision-induced dissociation (CID) of Cu(II)-peptide complexes. Internal electron transfer between tryptophan and metal ion within the complex occurred during the CID reaction, leaving the charge-reduced Cu(+) as a closed d-shell stable electron configuration. The choice of the reaction channel was then determined by the gas-phase basicity of the peptide. Amide hydrogen was critical in the formation of metalated b-/y-ions in the ECD process as determined through mutation of the backbone amide group. Increasing the chain length suppressed the ECD of Cu-metalated peptide species. Our results indicate that the structural parameters of peptides play important roles in the gas-phase dissociation processes of Cu-peptide complexes.

  8. Neutrino energy spectrum and electron capture of Nuclides 56Fe, 56Co, 56Ni, 56Mn, 56Cr and 56V in stellar interiors

    NASA Astrophysics Data System (ADS)

    Liu, Jing-Jing

    2014-08-01

    Based on the shell-model Monte Carlo method and random phase approximation theory, the neutrino energy spectrum (NES) and the electron capture (EC) of 56Fe 56Co 56Ni, 56Mn, 56Cr and 56V are investigated in presupernova surroundings. The results show that the EC rates are affected greatly at different densities and temperatures. The rates increase greatly and even exceed six orders of magnitude at lower temperature. On the other hand, the NES is very sensitive to stellar temperature and electron energy. The higher the temperature and the lower the electron energy, the larger the influence on NES is. For example, the maxima of NES in the ground state are 9.02, 160, 80, 24.01, 0.44, 1.42 me c2 for 56Fe, 56Co, 56Ni, 56Mn, 56Cr and 56V respectively at ρ7 = 10.7, Ye = 0.45 and T9 = 15. Furthermore, the influence on NES due to EC for different nuclei has some otherness because of different Q0-values. For example, the spectrum of 56Co shows a double bump structure.

  9. Simultaneous determination of florfenicol and florfenicol amine in fish, shrimp, and swine muscle by gas chromatography with a microcell electron capture detector.

    PubMed

    Zhang, Suxia; Sun, Fengyun; Li, Jiancheng; Cheng, Linli; Shen, Jianzhong

    2006-01-01

    A rapid and sensitive gas chromatography method was developed for the simultaneous determination of florfenicol (FF) and its metabolite florfenicol amine (FFA) in fish, shrimp, and swine muscle. The extracted samples were defatted with hexane and cleaned up by solid-phase extraction using Oasis MCX cartridges. The eluate was evaporated to dryness, and residues were derivatized and determined by gas chromatography with a microcell electron capture detector. Overall average recoveries ranged from 81.7 to 109.7% for fish, 94.1 to 103.4% for shrimp, and 71.5 to 91.4% for swine muscle. The detection limit was 0.5 ng/g for FF and 1 ng/g for FFA, respectively. The method was validated for the determination of incurred swine muscle samples in an actual residue study.

  10. Analysis of nitroaromatic compounds in complex samples using solid-phase microextraction and isotope dilution quantification gas chromatography-electron-capture negative ionisation mass spectrometry.

    PubMed

    Jönsson, S; Gustavsson, L; van Bavel, B

    2007-09-14

    A solid-phase microextraction (SPME) method using gas chromatography-electron-capture negative ionisation mass spectrometry (GC-ECNI-MS) and isotope dilution quantification for the analysis of nitroaromatic compounds in complex, water based samples has been optimised. For ionisation, ECNI was the most sensitive and selective method. SPME was compared to solid-phase extraction (SPE) and found to be more sensitive for these small volume samples. LODs were in the range 0.02-38ngL(-1) for SPME and 6-184ngL(-1) for SPE, respectively. The SPME method was applied on samples in the ngL(-1) level from artificial reed beds treated with sludge containing residues from explosives and pharmaceuticals.

  11. Simultaneous determination of chlorinated organic compounds from environmental samples using gas chromatography coupled with a micro electron capture detector and micro-plasma atomic emission detector

    NASA Astrophysics Data System (ADS)

    Quan, Xie; Chen, Shuo; Platzer, Bernhard; Chen, Jingwen; Gfrerer, Marion

    2002-01-01

    Water and sediment samples were screened simultaneously for the presence of polychlorinated organic compounds using gas chromatography (GC) coupled with an micro electron capture detector (μ-ECD) and a newly developed helium plasma based on a micro-atomic emission detector (μ-AED). The GC column effluent was split 15:85 between two detectors. In this way, two chromatograms, one obtained by μ-ECD and another by μ-AED, were recorded simultaneously. α-, β-hexachlorocyclohexane and p, p'-DDE were detected. RSDs of the monitoring results from the two detection methods were <20% for the three compounds. A detection limit of 8.5 pg and at least 3 orders of magnitude of linear range for μ-AED was observed.

  12. Automated fast extraction of nitrated polycyclic aromatic hydrocarbons from soil by focused microwave-assisted Soxhlet extraction prior to gas chromatography--electron-capture detection.

    PubMed

    Priego-Capote, F; Luque-García, J L; Luque de Castro, M D

    2003-04-25

    An approach for the automated fast extraction of nitrated polycyclic aromatic hydrocarbons (nitroPAHs) from soil, using a focused microwave-assisted Soxhlet extractor, is proposed. The main factors affecting the extraction efficiency (namely: irradiation power, irradiation time, number of cycles and extractant volume) were optimised by using experimental design methodology. The reduction of the nitro-PAHs to amino-PAHs and the derivatisation of the reduced analytes with heptafluorobutyric anhydride was mandatory prior to the separation-determination step by gas chromatography--electron-capture detection. The proposed approach has allowed the extraction of these pollutants from spiked and "real" contaminated soils with extraction efficiencies similar to those provided by the US Environmental Protection Agency methods 3540-8091, but with a drastic reduction in both the extraction time and sample handling, and using less organic solvent, as 75-85% of it was recycled.

  13. Moulting of insect tracheae captured by light and electron-microscopy in the metathoracic femur of a third instar locust Locusta migratoria.

    PubMed

    Snelling, Edward P; Seymour, Roger S; Runciman, Sue

    2011-09-01

    The insect tracheal system is an air-filled branching network of internal tubing that functions to exchange respiratory gases between the tissues and the environment. The light and electron-micrographs presented in this study show tracheae in the process of moulting, captured from the metathoracic hopping femur of a juvenile third instar locust (Locusta migratoria). The images provide evidence for the detachment of the cuticular intima from the tracheal epithelial cells, the presence of moulting fluid between the new and old cuticle layers, and the withdrawal of the shed cuticular lining through larger upstream regions of the tracheal system during moulting. The micrographs also reveal that the cuticular intima of the fine terminal branches of the tracheal system is cast at ecdysis. Therefore, the hypothesis that tracheoles retain their cuticle lining at each moult may not apply to all insect species or developmental stages.

  14. Simultaneous quantification of insecticides including carbaryl in drinking water by gas chromatography using dual electron-capture and nitrogen-phosphorus detection.

    PubMed

    Oh-Shin, Y S; Ko, M; Shin, H S

    1997-05-09

    A rapid and simple gas chromatographic method for the simultaneous determination of malathion, parathion, fenitrothion, diazinon and carbaryl in drinking water is presented. A fused-silica SE-54 column was used for the separation of the insecticides and was split into two specific detectors; electron-capture and nitrogen-phosphorus detectors by using column switching. A water sample was extracted with methylene chloride. The organic phase was evaporated and the residue was derivatized with pentafluoropropionic acid anhydride. The detection limit was below 0.1 ng/ml and the calibration curves showed good linearity with r = 0.998 approximately 1.000. The method was sensitive, reproducible and simple enough to permit the reliable routine analysis of the pesticides in drinking water.

  15. Trenbolone acetate and trenbolone: trace analysis in animal chow, wastewater and human urine by high pressure liquid chromatography and electron capture gas chromatography.

    PubMed

    Holder, C L; Blakemore, W M; Bowman, M C

    1979-02-01

    Analytical methodology is described for determining residues of the synthetic anabolic steroid trenbolone acetate (TBA) and its hydrolysis product trenbolone (TBOH) in admixture in animal chow, human urine, and wastewater. Benzene extracts of the substrates are subjected to liquid-liquid partitioning, further cleanup on a column of silica gel, and direct analysis by high pressure liquid chromotography or derivatization with pentafluoropropionic anhydride and analysis by electron capture gas chromatography. Satisfactory recoveries were obtained with both compounds from all three substrates. Residue levels of TBA and TBOH as low as 0.32 and 0.04 ppm, respectively, could be detected in chow; about 0.6 ppb of each compound could be detected in urine and wastewater. Thin layer chromatographic behavior of the two compounds in 7 solvent systems and other ancillary analytical data are also presented.

  16. Measurement of polychlorinated biphenyls in solid waste such as transformer insulation paper by supercritical fluid extraction and gas chromatography electron capture detection.

    PubMed

    Chikushi, Hiroaki; Fujii, Yuka; Toda, Kei

    2012-09-21

    In this work, a method for measuring polychlorinated biphenyls (PCBs) in contaminated solid waste was investigated. This waste includes paper that is used in electric transformers to insulate electric components. The PCBs in paper sample were extracted by supercritical fluid extraction and analyzed by gas chromatography-electron capture detection. The recoveries with this method (84-101%) were much higher than those with conventional water extraction (0.08-14%), and were comparable to those with conventional organic solvent extraction. Limit of detection was 0.0074 mg kg(-1) and measurable up to 2.5 mg kg(-1) for 0.5 g of paper sample. Data for real insulation paper by the proposed method agreed well with those by the conventional organic solvent extraction. Extraction from wood and concrete was also investigated and good performance was obtained as well as for paper samples. The supercritical fluid extraction is simpler, faster, and greener than conventional organic solvent extraction.

  17. Large Scale Discovery and De Novo-Assisted Sequencing of Cationic Antimicrobial Peptides (CAMPs) by Microparticle Capture and Electron-Transfer Dissociation (ETD) Mass Spectrometry.

    PubMed

    Juba, Melanie L; Russo, Paul S; Devine, Megan; Barksdale, Stephanie; Rodriguez, Carlos; Vliet, Kent A; Schnur, Joel M; van Hoek, Monique L; Bishop, Barney M

    2015-10-02

    The identification and sequencing of novel cationic antimicrobial peptides (CAMPs) have proven challenging due to the limitations associated with traditional proteomics methods and difficulties sequencing peptides present in complex biomolecular mixtures. We present here a process for large-scale identification and de novo-assisted sequencing of newly discovered CAMPs using microparticle capture followed by tandem mass spectrometry equipped with electron-transfer dissociation (ETD). This process was initially evaluated and verified using known CAMPs with varying physicochemical properties. The effective parameters were then applied in the analysis of a complex mixture of peptides harvested from American alligator plasma using custom-made (Bioprospector) functionalized hydrogel particles. Here, we report the successful sequencing process for CAMPs that has led to the identification of 340 unique peptides and the discovery of five novel CAMPs from American alligator plasma.

  18. Amide-I relaxation-induced hydrogen bond distortion: An intermediate in electron capture dissociation mass spectrometry of alpha-helical peptides?

    PubMed

    Pouthier, Vincent; Tsybin, Yury O

    2008-09-07

    Electron capture dissociation (ECD) of peptides and proteins in the gas phase is a powerful tool in tandem mass spectrometry whose current description is not sufficient to explain many experimental observations. Here, we attempt to bridge the current understanding of the vibrational dynamics in alpha-helices with the recent experimental results on ECD of alpha-helical peptides through consideration of amide-I relaxation-induced hydrogen bond distortion. Based on a single spine of H-bonded peptide units, we assume that charge neutralization upon electron capture by a charged alpha-helix excites a nearby amide-I mode, which relaxes over a few picoseconds due to Fermi resonances with intramolecular normal modes. The amide-I population plays the role of an external force, which drives the displacements of each peptide unit. It induces a large immobile contraction of the H bonds surrounding the excited site whose lifetime is about the amide-I lifetime. In addition, it creates two lattice deformations describing H bond stretchings, which propagate from the excited region toward both termini of the alpha-helix, get reflected at the termini and yield H bond contractions which move back to the excited region. Consequently, we show that H bonds experience rather large contractions whose amplitude depends on general features such as the position of the amide-I mode, the peptide length and the H bond force constants. When an H bond contraction is sufficiently large, it may promote a hydrogen atom transfer between two neighboring peptide units leading to the formation of a radical at charge site remote carbonyl carbon which is known to be a precursor to the rupture of the corresponding N[Single Bond]C(alpha) bond. The introduced here way of excitation energy generation and transfer may significantly advance ECD understanding and complement existing ECD mechanisms.

  19. Determination of fungicides in natural waters using solid-phase microextraction and gas chromatography coupled with electron-capture and mass spectrometric detection.

    PubMed

    Lambropoulou, D A; Konstantinou, I K; Albanis, T A

    2000-09-29

    This study develops a method for the analysis of seven fungicides in environmental waters, using solid-phase microextraction (SPME). The analyzed compounds--dicloran, chlorothalonil, vinclozolin, dichlofluanid, captan, folpet and captafol--belong to different classes of chemical compound (chloroanilines, sulphamides, phthalimides and oxazolidines) and are used mainly in agriculture and as antifouling paints. Their determination was carried out by gas chromatography with electron-capture and mass spectrometric detection. To perform SPME, four types of fibre have been assayed and compared: polyacrylate (85 microm), polydimethylsiloxane (100 and 30 microm), carbowax-divinylbenzene (CW-DVB 65 microm) and polydimethylsiloxane-divinylbenzene (65 microm). The main parameters affecting the SPME process such as pH, salt additives, methanol content, memory effect, stirring rate and adsorption-time profile were studied. The method was developed using spiked natural waters such as ground water, sea water, river water and lake water in a concentration range of 0.1-10 microg/l. Limits of detection of studied compounds were determined in the range of 1-60 ng/l, by using electron-capture and mass spectrometric detectors. The recoveries of all fungicides were in relatively high levels (70.0-124.4%) and the average R2 values of the calibration curves were above 0.990 for all the analytes. The SPME conditions were finally optimized in order to obtain the maximum sensitivity. The potential of the proposed method was realized by applying it to the trace-level screening determination of fungicides and antifouling compounds in sea water samples originating from various Greek marinas.

  20. Comparative study of Gamow-Teller strength distributions in the odd-odd nucleus V50 and its impact on electron capture rates in astrophysical environments

    NASA Astrophysics Data System (ADS)

    Nabi, Jameel-Un; Sajjad, Muhammad

    2007-11-01

    Gamow-Teller (GT) strength transitions are an ideal probe for testing nuclear structure models. In addition to nuclear structure, GT transitions in nuclei directly affect the early phases of Type Ia and Type-II supernovae core collapse since the electron capture rates are partly determined by these GT transitions. In astrophysics, GT transitions provide an important input for model calculations and element formation during the explosive phase of a massive star at the end of its life-time. Recent nucleosynthesis calculations show that odd-odd and odd-A nuclei cause the largest contribution in the rate of change of lepton-to-baryon ratio. In the present manuscript, we have calculated the GT strength distributions and electron capture rates for odd-odd nucleus V50 by using the pn-QRPA theory. At present V50 is the first experimentally available odd-odd nucleus in fp-shell nuclei. We also compare our GT strength distribution with the recently measured results of a V50(d, He2)Ti50 experiment, with the earlier work of Fuller, Fowler, and Newman (referred to as FFN) and subsequently with the large-scale shell model calculations. One curious finding of the paper is that the Brink's hypothesis, usually employed in large-scale shell model calculations, is not a good approximation to use at least in the case of V50. SNe Ia model calculations performed using FFN rates result in overproduction of Ti50, and were brought to a much acceptable value by employing shell model results. It might be interesting to study how the composition of the ejecta using presently reported QRPA rates compare with the observed abundances.

  1. Gas-phase doubly charged complexes of cyclic peptides with copper in +1, +2 and +3 formal oxidation states: formation, structures and electron capture dissociation.

    PubMed

    Afonso, Carlos; Tabet, Jean-Claude; Giorgi, Gianluca; Tureček, František

    2012-02-01

    Copper complexes with a cyclic D-His-β-Ala-L-His-L-Lys and all-L-His-β-Ala-His-Lys peptides were generated by electrospray which were doubly charged ions that had different formal oxidation states of Cu(I), Cu(II) and Cu(III) and different protonation states of the peptide ligands. Electron capture dissociation showed no substantial differences between the D-His and L-His complexes. All complexes underwent peptide cross-ring cleavages upon electron capture. The modes of ring cleavage depended on the formal oxidation state of the Cu ion and peptide protonation. Density functional theory (DFT) calculations, using the B3LYP with an effective core potential at Cu and M06-2X functionals, identified several precursor ion structures in which the Cu ion was threecoordinated to pentacoordinated by the His and Lys side-chain groups and the peptide amide or enolimine groups. The electronic structure of the formally Cu(III) complexes pointed to an effective Cu(I) oxidation state with the other charge residing in the peptide ligand. The relative energies of isomeric complexes of the [Cu(c-HAHK + H)](2+) and [Cu(c-HAHK - H)](2+) type with closed electronic shells followed similar orders when treated by the B3LYP and M06-2X functionals. Large differences between relative energies calculated by these methods were obtained for open-shell complexes of the [Cu(c-HAHK)](2+) type. Charge reduction resulted in lowering the coordination numbers for some Cu complexes that depended on the singlet or triplet spin state being formed. For [Cu(c-HAHK - H)](2+) complexes, solution H/D exchange involved only the N-H protons, resulting in the exchange of up to seven protons, as established by ultra-high mass resolution measurements. Contrasting the experiments, DFT calculations found the lowest energy structures for the gas-phase ions that were deprotonated at the peptide C(α) positions.

  2. How we developed eForms: an electronic form and data capture tool to support assessment in mobile medical education.

    PubMed

    Mooney, Jane S; Cappelli, Tim; Byrne-Davis, Lucie; Lumsden, Colin J

    2014-12-01

    Mobile learning technologies are being introduced and adopted by an increasing number of medical schools. Following the implementation of these devices, institutions are tasked with the challenge of their integration into curriculum delivery and presented with the opportunity to facilitate data collection from large student cohorts. Since 2011, Manchester Medical School (MMS) has undertaken the largest deployment of iPads within UK Higher Education. Working towards the more efficient collation of students' compulsory workplace-based assessment data led us to evaluate how existing information management software could replace previously paper-based systems. Following an evaluation of six, and a trial of one, commercially available packages, the existing software solutions were found to be inflexible and unfit for purpose. This resulted in the development of a new digital solution that addressed the limitations of the previous system. "University of Manchester (UoM) eForms" consists of an app and a web-based administration system that respectively permit high volume data collection and management. UoM eForms has now replaced the preceding paper-based and electronic systems within MMS for workplace-based assessment administration, due to the improved usability and dynamicity built into its interface and infrastructure. This new system has found many further useful applications, including research data collection, feedback, placement evaluations, quality assurance and interview marking.

  3. Can odors of TCM be captured by electronic nose? The novel quality control method for musk by electronic nose coupled with chemometrics.

    PubMed

    Ye, Tao; Jin, Cheng; Zhou, Jian; Li, Xingfeng; Wang, Haitao; Deng, Pingye; Yang, Ying; Wu, Yanwen; Xiao, Xiaohe

    2011-07-15

    Musk is a precious and wide applied material in traditional Chinese medicine, also, an important material for the perfume industry all over the world. To establish a rapid, cost-effective and relatively objective assessment for the quality of musk, different musk samples, including authentic, fake and adulterate, were collected. A oxide sensor based electronic nose (E-nose) was employed to measure the musk samples, the E-nose generated data were analyzed by principal component analysis (PCA), the responses of 18 sensors of E-nose were evaluated by loading analysis. Results showed that a rapid evaluation of complex response of the samples could be obtained, in combination with PCA and the perception level of the E-nose was given better results in the recognition values of the musk aroma. The authentic, fake and adulterate musk could be distinguished by E-nose coupled with PCA, sensor 2, 3, 5, 12, 15 and 17 were found to be able to better discriminate between musk samples, confirming the potential application of an electronic instrument coupled with chemometrics for a rapid and on-line quality control for the traditional medicines.

  4. Comment on 'Time modulation of K-shell electron capture decay rates of H-like heavy ions at GSI experiments.'

    SciTech Connect

    Lipkin, H. J.; Physics; Weizmann Inst. of Science; Tel Aviv Univ.

    2010-04-16

    A Comment on the Letter by A.N. Ivanov and P. Kienle, Physical Review Letters volume 103, Issue 6, 062502 (2009). The authors of the Letter offer a Reply to experimental data at GSI, the rates of the number of daughter ions, produced by the nuclear K shell electron capture decays of the H-like heavy ions with one electron in the K shell, such as {sup 140}Pr{sup 58+}, {sup 142}Pm{sup 60+}, and {sup 122}I{sup 52+}, are modulated in time with periods T{sub EC} of the order of a few seconds, obeying an A scaling T{sub EX}=A/20 s, where A is the mass number of the mother nuclei, and with amplitudes a{sub d {sup EC}}{approx}0.21. We show that these data can be explained in terms of the interference of two massive neutrino mass eigenstates. The appearance of the interference term is due to overlap of massive neutrino mass eigenstate energies and of the wave functions of the daughter ions in two-body decay channels, caused by the energy and momentum uncertainties introduced by time differential detection of the daughter ions in GSI experiments.

  5. The Neutrino Energy Loss of Nuclides by K-shell Continuum State Electron Capture at the Late Stage of Stellar Evolution

    NASA Astrophysics Data System (ADS)

    Liu, J. J.; Lin, Y.

    2013-01-01

    Based on the Weinberg-Salam theory and taken into consideration of the Coulomb effect on electron gas, the neutrino energy loss rates by K-shell continuum state electron capture are discussed for ^{12}C, ^{16}O, ^{20}Ne, ^{24}Mg, ^{28}Si and ^{56}Fe under the condition of complete ionization and at the late stage of stellar evolution. Our results are compared with those of Beaudet, Petrosian and Salpeter (BPS). It is shown that at relatively high temperatures (e.g., {T_9 = 0.1} and {T_9 = 1}, T_9 represents the temperature in units of 10^9 K), our results agree well with BPS's. However, at relatively low temperatures (e.g., {T_9 = 0.01} and {T_9 = 0.001}), the neutrino energy loss rates of BPS for ^{16}O, ^{20}Ne, ^{24}Mg and ^{28}Si are higher than our results by 10˜ 70 times, and even by 2 orders of magnitude for nuclide ^{12}C. Our results may be of great importance in the research of late stellar evolution, especially for the cooling mechanism of white dwarf, during which the nucleus collapsed to the stage with a relatively low temperature and intermediate density.

  6. Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of chlorinated pesticides in aquatic tissue by capillary-column gas chromatography with electron-capture detection

    USGS Publications Warehouse

    Leiker, Thomas J.; Madsen, J.E.; Deacon, J.R.; Foreman, W.T.

    1995-01-01

    A method for the determination of chlorinated organic compounds in aquatic tissue by dual capillary-column gas chromatography with electron-capture detection is described. Whole-body-fish or corbicula tissue is homogenized, Soxhlet extracted, lipid removed by gel permeation chromatography, and fractionated using alumina/silica adsorption chromatography. The extracts are analyzed by dissimilar capillary-column gas chromatography with electron-capture detection. The method reporting limits are 5 micrograms per kilogram (μg/kg) for chlorinated compounds, 50 μg/kg for polychlorinated biphenyls, and 200 μg/kg for toxaphene.

  7. Validation of a multi-residue method to determine deltamethrin and alpha-cypermethrin in mosquito nets by gas chromatography with electron capture detection (GC-μECD)

    PubMed Central

    2013-01-01

    Background Nowadays long-lasting insecticidal mosquito nets (LNs) are frequently used around the world to protect people against malaria vectors. As they contain insecticide, laboratory control is needed to check whether the content of the active ingredient follows the conditions of the manufacturer and also if the active ingredient is still present after some time of use. For this purpose, an analytical method had to be developed. The fact that LNs include a range of polymers for the yarn and use coated or incorporated technologies for the active ingredient, it is a challenge to find only one analytical method determining the active ingredient in LNs, which takes into account both impregnation technologies. Some methods are provided by international organizations but are limited by the determination of only one pesticide per method. The aim of this study was to optimize a short time extraction method for deltamethrin and alpha-cypermethrin from coated and incorporated mosquito nets and also to detect both insecticides in one analytical run, using gas chromatography with electron capture detection (GC-μECD). Methods Based on the literature, the most suitable solvent and the adequate extraction process for the insecticides used for net making were identified and adapted for the new multi-residue method. Results The validation data of the multi-residue method to determine deltamethrin and alpha-cypermethrin in mosquito nets by GC-μECD are given. Depending on the concentration of the active ingredient spiked on the nets, the mean recovery for alpha-cypermethrin ranged between 86% and 107% with a relative standard deviation below 3.5%. For deltamethrin it ranged between 90% and 108% with a relative standard deviation also below 3.5%. The limit of detection is 0.009 g.a.i/kg of net (0.3 mg a.i./m2 of net) both for alpha-cypermethrin and deltamethrin. Conclusions Data obtained are excellent. A 30 minutes reflux extraction method with xylene was developed to determine

  8. New multiresidue method using solid-phase extraction and gas chromatography-micro-electron-capture detection for pesticide residues analysis in royal jelly.

    PubMed

    Karazafiris, Emmanouel; Menkissoglu-Spiroudi, Urania; Thrasyvoulou, Andreas

    2008-10-31

    Royal jelly, one of the most important bee products, can be contaminated with pesticide and/or antibiotic residues resulting from treatments applied either inside beehives or in the agricultural environment. A new multiresidue method was developed and validated for analysis of nine pesticides in royal jelly. Solid-phase extraction RP-C(18) cartridges were used for sample purification and isolation of analytes. Final solution was analyzed with GC and micro-electron-capture detection. Four synthetic acaricides used by beekeepers (bromopropylate, coumaphos, malathion and tau-fluvalinate), and moreover one pyrethroid, two organochlorine, and two organophosphate insecticides were tested. Linearity is demonstrated for the range of 0.0025-1mgkg(-1), with correlation coefficients ranging from 0.99991 to 0.99846, depending on the analyte. Overall recovery rates from royal jelly blank samples spiked at five fortification levels ranged from 80.8% (lindane) to 91.3% (ethion), well above the range defined by the SANCO/10232/2006 and EC/675/2002 documents. The limit of quantification was <0.003-0.005 mg kg(-1) depending on the analyte, and the reporting level of the method, defined as the lowest recovery level, was 0.005 mg kg(-1).

  9. Sample pretreatment optimization for the analysis of short chain chlorinated paraffins in soil with gas chromatography-electron capture negative ion-mass spectrometry.

    PubMed

    Chen, Laiguo; Huang, Yumei; Han, Shuang; Feng, Yongbin; Jiang, Guo; Tang, Caiming; Ye, Zhixiang; Zhan, Wei; Liu, Ming; Zhang, Sukun

    2013-01-25

    Accurately quantifying short chain chlorinated paraffins (SCCPs) in soil samples with gas chromatograph coupled with electron capture negative ionization mass spectrometry (GC-ECNI-MS) is difficult because many other polychlorinated pollutants are present in the sample matrices. These pollutants (e.g., polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and toxaphene) can cause serious interferences during SCCPs analysis with GC-MS. Four main columns packed with different adsorbents, including silica gel, Florisil and alumina, were investigated in this study to determine their performance for separating interfering pollutants from SCCPs. These experimental results suggest that the optimum cleanup procedure uses a silica gel column and a multilayer silica gel-Florisil composite column. This procedure completely separated 22 PCB congeners, 23 OCPs and three toxaphene congeners from SCCPs. However, p,p'-DDD, cis-nonachlor and o,p'-DDD were not completely removed and only 53% of the total toxaphene was removed. This optimized method was successfully and effectively applied for removing interfering pollutants from real soil samples. SCCPs in 17 soil samples from different land use areas within a suburban region were analyzed with the established method. The concentrations of SCCPs in these samples were between 7 and 541 ng g(-1) (mean: 84 ng g(-1)). Similar homologue SCCPs patterns were observed between the soil samples collected from different land use areas. In addition, lower chlorinated (Cl(6/7)) C(10)- and C(11)- SCCPs were the dominant congeners.

  10. Detection of metabolites by frequency-pulsed electron capture gas-liquid chromatography in serum and cerebrospinal fluid of a patient with Nocardia infection.

    PubMed

    Brooks, J B; Kasin, J V; Fast, D M; Daneshvar, M I

    1987-02-01

    Serum (SR) and cerebrospinal fluid (CSF) from a patient suspected of having tuberculous meningitis were submitted to our laboratory for analysis by frequency-pulsed electron capture gas-liquid chromatography (FPEC GLC). The samples were tested for the presence of carboxylic acids, alcohols, hydroxy acids, and amines by methods described previously (C. C. Alley, J. B. Brooks, and D. S. Kellogg, Jr., J. Clin. Microbiol. 9:97-102, 1977; J. B. Brooks, C. C. Alley, and J. A. Liddle, Anal. Chem. 46:1930-1934, 1974; J. B. Brooks, D. S. Kellogg, Jr., M. E. Shepherd, and C. C. Alley, J. Clin. Microbiol. 11:45-51, 1980; J. B. Brooks, D. S. Kellogg, Jr., M. E. Shepherd, and C. C. Alley, J. Clin. Microbiol. 11:52-58, 1980). The results were different from previous FPEC GLC profiles of SR and CSF from patients with known tuberculous meningitis. Both the SR and CSF contained several unidentified compounds that were not previously detected in tuberculous meningitis or any of our other studies of body fluids. Nocardia brasiliensis was later isolated from the patient. Detection of these metabolites by FPEC GLC could prove to be useful for rapid diagnosis of Nocardia disease, and their identification will provide a better understanding of metabolites produced by Nocardia sp. in vivo.

  11. Multiresidue determination of pyrethroid pesticide residues in pepper through a modified QuEChERS method and gas chromatography with electron capture detection.

    PubMed

    Zhang, Yuping; Hu, Deyu; Zeng, Song; Lu, Ping; Zhang, Kankan; Chen, Lingzhu; Song, Baoan

    2016-02-01

    This study developed and used a modified quick, easy, cheap, efficient, rugged and safe (QuEChERS) method coupled with gas chromatography with electron capture detection to determine eight pyrethroid pesticide residues in green, red and dehydrated red peppers. Pyrethroids were extracted with acetonitrile, partitioned with sodium chloride and purified with primary secondary amino and graphitized carbon black in hexane. The QuEChERS extraction conditions were optimized, and the matrix effects that might influence recoveries were evaluated and minimized using matrix-matched calibration curves. Under the optimized conditions, the calibration curves for pyrethroid pesticides showed good linearities in the concentration range of 0.05-20 µg/mL with determination coefficients (R(2) ) >0.997. The limits of quantification of eight pyrethroids were 0.004-0.04 mg/kg for green and red pepper and 0.04-0.5 mg/kg for dehydrated red pepper. These values are below the suggested regulatory maximum residue limits. The mean recoveries ranged between 79.0 and 104%, and the relative standard deviations were <11%. The developed method was successfully applied to commercial samples. Some samples were found to contain pyrethroid pesticides with levels below the legal limits.

  12. Use of green coating (cork) in solid-phase microextraction for the determination of organochlorine pesticides in water by gas chromatography-electron capture detection.

    PubMed

    Dias, Adriana Neves; Simão, Vanessa; Merib, Josias; Carasek, Eduardo

    2015-03-01

    A novel method for the determination of organochlorine pesticides in water samples with extraction using cork fiber and analysis by gas chromatography with electron capture detector was developed. Also, the procedure to extract these pesticides with DVB/Car/PDMS fiber was optimized. The optimization of the variables involved in the extraction of organochlorine pesticides using the aforementioned fibers was carried out by multivariate design. The optimum extraction conditions were sample temperature 75 °C, extraction time 60 min and sodium chloride concentration 10% for the cork fiber and sample temperature 50 °C and extraction time 60 min (without salt) for the DVB/Car/PDMS fiber. The quantification limits for the two fibers varied between 1.0 and 10.0 ng L(-1). The linear correlation coefficients were >0.98 for both fibers. The method applied with the use of the cork fiber provided recovery values between 60.3 and 112.7 and RSD≤25.5 (n=3). The extraction efficiency values for the cork and DVB/Car/PDMS fibers were similar. The results show that cork is a promising alternative as a coating for SPME.

  13. Determination of pentachlorophenol residue in meat and fish by gas chromatography-electron capture detection and gas chromatography-mass spectrometry with accelerated solvent extraction.

    PubMed

    Zhao, Dongmei

    2014-01-01

    A novel analytical method, using gas chromatography-electron capture detection (GC-ECD) and GC-mass spectrometry detection (MS), was developed for the qualitative and quantitative measurement of pentachlorophenol in meat and fish. The analyte was extracted by methanol-2% trichloroacetic acid (3/1, v/v) with accelerated solvent extraction (ASE). The eluted fraction was evaporated and derivatized with acetic anhydride-pyridine (1/1, v/v) for GC-ECD analysis and GC-MS confirmation. The parameters for extraction pressure, temperature and cycle of ASE, cleanup, derivatization and analysis procedure were optimized. The averaged decision limits and detection capability of the method were in the ranges of 0.25-0.41 and 0.49-1.01 µg/kg in the muscle and liver of swine and bovine and in the muscle of carp and finless eel, respectively. Spiked recoveries from levels of 0.5-2.0 µg/kg were found to be more than 71.1%, with relative standard deviation less than 14.7% in GC-ECD and GC-MS. This rapid and reliable method can be used for the characterization and quantification of residues of pentachlorophenol in animal and fish tissues.

  14. Solid phase extraction with silicon dioxide microsphere adsorbents in combination with gas chromatography-electron capture detection for the determination of DDT and its metabolites in water samples.

    PubMed

    Zhou, Qingxiang; Wu, Wei; Xie, Guohong

    2013-01-01

    The goal of the present study was to investigate the feasibility of silicon dioxide (SiO(2)) microspheres without special modification to enrich dichlorodiphenyltrichloroethane (DDT) and its main metabolites, p,p'-dichlorodiphenyl-2,2-dichloroethylene (p,p'-DDD) and p,p'-dichlorodiphenyldichloroethylene (DDE) in combination with gas chromatography-electron-capture detection. The experimental results indicated that an excellent linear relationship between the recoveries and the concentrations of DDT and its main metabolites was obtained in the range of 0.2-30 ng mL(-1) and the correlation coefficients were in the range of 99.96-99.99%. The detection limits based on the ratio of signal to the baseline noise (S/N = 3) were 2.2, 2.9, 3.8 and 4.1 ng L(-1) for p,p'-DDD, p,p'-DDT, o,p'-DDT, and p,p'-DDE, respectively. The precisions of the proposed method were all below 10% (n = 6). Four real water samples were utilized for validation of the proposed method, and satisfactory spiked recoveries in the range of 72.4-112.9% were achieved. These results demonstrated that the developed method was a simple, sensitive, and robust analytical method for the monitoring of pollutants in the environment.

  15. Determination of 2,4,6-trichloroanisole in wines by headspace solid-phase microextraction and gas chromatography-electron-capture detection.

    PubMed

    Riu, M; Mestres, M; Busto, O; Guasch, J

    2002-11-15

    One of the most important problems in the wine world, today, is cork taint, which often has been chemically identified as 2,4,6-trichloroanisole (TCA). The perception limit of this compound is very low (close to 10 and 40 ng/l for white and red wines, respectively), so, even at such low concentrations, its presence becomes a problem in wine quality. A method for the analysis of TCA in white and red wines has been developed in our laboratory, using headspace solid-phase microextraction and gas chromatography with electron-capture detection. The method, which has been optimized using an experimental design, involves the use of fibres coated with polydimethylsiloxane (PDMS) and allows the analysis of TCA at very low concentrations (under 500 ng/l) with good accuracy (RSD < or = 10%). The limits of quantification of the method are 5 and 8 ng/l for white and red wines, respectively, while the limit of detection is 1 ng/l for both types of wine.

  16. Determination of acetanilide herbicides in cereal crops using accelerated solvent extraction, solid-phase extraction and gas chromatography-electron capture detector.

    PubMed

    Zhang, Yaping; Yang, Jun; Shi, Ronghua; Su, Qingde; Yao, Li; Li, Panpan

    2011-07-01

    A method was developed to determine eight acetanilide herbicides from cereal crops based on accelerated solvent extraction (ASE) and solid-phase extraction (SPE) followed by gas chromatography-electron capture detector (GC-ECD) analysis. During the ASE process, the effect of four parameters (temperature, static time, static cycles and solvent) on the extraction efficiency was considered and compared with shake-flask extraction method. After extraction with ASE, four SPE tubes (graphitic carbon black/primary secondary amine (GCB/PSA), GCB, Florisil and alumina-N) were assayed for comparison to obtain the best clean-up efficiency. The results show that GCB/PSA cartridge gave the best recoveries and cleanest chromatograms. The analytical process was validated by the analysis of spiked blank samples. Performance characteristics such as linearity, limit of detection (LOD), limit of quantitation (LOQ), precision and recovery were studied. At 0.05 mg/kg spiked level, recoveries and precision values for rice, wheat and maize were 82.3-115.8 and 1.1-13.6%, respectively. For all the herbicides, LOD and LOQ ranged from 0.8 to 1.7 μg/kg and from 2.4 to 5.3 μg/kg, respectively. The proposed analytical methodology was applied for the analysis of the targets in samples; only three herbicides, propyzamid, metolachlor and diflufenican, were detected in two samples.

  17. Searches for massive neutrino emission in 14C beta and 55Fe electron-capture decays

    SciTech Connect

    Wietfeldt, Fred Eberhardt

    1994-05-01

    In 1985 Simpson reported evidence for the emission of a 17 keV mass neutrino in a small fraction of tritium beta decays. An experimental controversy ensued in which a number of both positive and negative results were reported. The beta spectrum of 14C was collected in a unique 14C-doped planar germanium detector and a distortion was observed that initially confirmed Simpson`s result. Further tests linked this distortion to a splitting of the collected charge between the central detector and the surrounding guard ring in a fraction of the events. A second 14C measurement showed no evidence for emission of a 17 keV mass neutrino. In a related experiment, a high statistics electron-capture internal-bremsstrahlung photon spectrum of 55Fe was collected with a coaxial germanium detector. A local search for departures from a smooth shape near the endpoint was performed, using a second-derivative technique. An upper limit of 0.65% (95% C.L.) for the mixing Of a neutrino in the mass range 5--25 keV was established. The upper limit on the mixing of a 17 keV mass neutrino was 0.14% (95% C.L.).

  18. 20-150-keV proton-impact-induced ionization of uracil: Fragmentation ratios and branching ratios for electron capture and direct ionization

    SciTech Connect

    Tabet, J.; Eden, S.; Feil, S.; Abdoul-Carime, H.; Farizon, B.; Farizon, M.; Ouaskit, S.; Maerk, T. D.

    2010-01-15

    Fragmentation ratios and branching ratios are measured for ionization and dissociative ionization for 20-150 keV (0.9-2.4v{sub 0}) proton collisions with gas-phase uracil molecules. Through event-by-event determination of the postcollision projectile charge, it is possible for such a key biomolecule to distinguish between electron capture (EC) by the incident proton and direct ionization (DI) without projectile neutralization. While the same fragment ion groups are observed in the mass spectra for both processes, EC induces dissociation with greater efficiency than DI in the impact energy range of 35-150 keV (1.2-2.4v{sub 0}). In this range EC is also less abundant than DI with a branching ratio for EC/total ionization of <50%. Moreover, whereas fragmentation ratios do not change with energy in the case of EC, DI mass spectra show a tendency for increased fragmentation at lower impact energies.

  19. Rapid analysis of pyrethroid insecticides in aquaculture seawater samples via membrane-assisted solvent extraction coupled with gas chromatography-electron capture detection.

    PubMed

    Shi, X Z; Song, S Q; Sun, A L; Liu, J H; Li, D X; Chen, J

    2012-01-21

    A simple, efficient, and environmentally friendly membrane-assisted solvent extraction (MASE) method for the extraction and preconcentration of six pyrethroid insecticides from aquaculture seawater samples followed by gas chromatography-electron capture detection (GC-ECD) was successfully proposed. The operating conditions for MASE, such as the extraction solvent, solvent volume, NaCl concentration, stirring rate, extraction time, and temperature, were optimized. Compared to conventional Florisil-solid phase extraction (SPE), higher extraction recoveries (85.9% to 105.9%) of three spiked levels of the six pyrethroid pesticides in aquaculture seawater were obtained using MASE, and the RSD values were lower than 7.9%. The limits of detection (LOD, signal-to-noise ratio (S/N)=3) and quantification (LOQ, S/N = 10) were in the range of 0.037-0.166 and 0.12-0.55 μg L(-1), respectively. The results demonstrate the excellent applicability of the MASE method in analyzing the six pyrethroid pesticides in aqueous samples. The proposed method exhibited a high potential for routine monitoring analysis of pyrethroid insecticides in seawater samples.

  20. Ultrasound-assisted extraction and solid-phase extraction for the simultaneous determination of five amide herbicides in fish samples by gas chromatography with electron capture detection.

    PubMed

    Qu, Zhipeng; Bai, Xiuzhi; Zhang, Ting; Yang, Zhaoguang

    2017-03-01

    An efficient sample extraction and clean-up method was developed for simultaneous determination of five amide herbicides (alachlor, acetochlor, propisochlor, metazachlor, and butachlor) in fish samples. The protocol consisted of ultrasound-assisted solvent extraction and solid-phase extraction clean-up. In detail, aliquots of homogenized fish flesh were thoroughly mixed with 20 mL of n-hexane and then extracted with ultrasonication for 40 min. Each sample was centrifuged and the supernatant was collected for the subsequent clean-up. For the sample preparation, the above supernatant was processed with a C18 column with 3 mL of dichloromethane/n-hexane (1:1, v/v) as the eluant. Then the samples were analyzed by gas chromatography with electron capture detection. The correlation coefficients of the five calibration curves were 0.9976-0.9998 (n = 3). The limits of detection (S/N = 3, n = 11) and limits of quantification (S/N = 10, n = 11) were 0.19-0.42 and 0.63-1.39 μg/kg, respectively. The recoveries of this method were 71.2-92.6% with good precision (<4.7% relative standard deviations, n = 6). The developed method was successfully applied to monitor the five amide herbicides in fish samples collected from different cities.

  1. Comparative study of different clean-up techniques for the determination of λ-cyhalothrin and cypermethrin in palm oil matrices by gas chromatography with electron capture detection.

    PubMed

    Muhamad, Halimah; Zainudin, Badrul Hisyam; Abu Bakar, Nor Kartini

    2012-10-15

    Solid phase extraction (SPE) and dispersive solid-phase extraction (d-SPE) were compared and evaluated for the determination of λ-cyhalothrin and cypermethrin in palm oil matrices by gas chromatography with an electron capture detector (GC-ECD). Several SPE sorbents such as graphitised carbon black (GCB), primary secondary amine (PSA), C(18), silica, and florisil were tested in order to minimise fat residues. The results show that mixed sorbents using GCB and PSA obtained cleaner extracts than a single GCB and PSA sorbents. The average recoveries obtained for each pesticide ranged between 81% and 114% at five fortification levels with the relative standard deviation of less than 7% in all cases. The limits of detection for these pesticides were ranged between 0.025 and 0.05 μg/g. The proposed method was applied successfully for the residue determination of both λ-cyhalothrin and cypermethrin in crude palm oil samples obtained from local mills throughout Malaysia.

  2. A new approach to measuring protein backbone protection with high spatial resolution using H/D exchange and electron capture dissociation

    PubMed Central

    Abzalimov, Rinat R.; Bobst, Cedric E.; Kaltashov, Igor A.

    2013-01-01

    Inadequate spatial resolution remains one of the most serious limitations of hydrogen/deuterium exchange mass spectrometry (HDX MS), especially when applied to larger proteins (over 30 kDa). Supplementing proteolytic fragmentation of the protein in solution with ion dissociation in the gas phase has been used successfully by several groups to obtain near-residue level resolution. However, the restrictions imposed by the LC/MS/MS mode of operation on the data acquisition time frame makes it difficult in many cases to obtain signal-to-noise ratio adequate for reliable assignment of the backbone amide protection levels at individual residues. This restriction is lifted in the present work by eliminating the LC separation step from the workflow and taking advantage of the high resolving power and dynamic range of a Fourier transform ion cyclotron resonance mass spectrometer (FT ICR MS). A residue-level resolution is demonstrated for a peptic fragment of a 37 kDa recombinant protein (N-lobe of human serum transferrin) using electron-capture dissociation as an ion fragmentation tool. The absence of hydrogen scrambling in the gas phase prior to ion dissociation is verified using redundant HDX MS data generated by FT ICR MS. The backbone protection pattern generated by direct HDX MS/MS is in excellent agreement with the known crystal structure of the protein, but also provides information on conformational dynamics, which is not available from the static X-ray structure. PMID:23978257

  3. Phenyl-functionalized silica-coated magnetic nanoparticles for the extraction of chlorobenzenes, and their determination by GC-electron capture detection.

    PubMed

    Saraji, Mohammad; Khaje, Nasrin

    2013-03-01

    We have prepared a solid phase for the extraction of chlorobenzenes (CBs) by coating magnetic (Fe3 O4 ) nanoparticles with silica via a sol-gel process using a mixture of tetraethoxysilane and triethoxyphenylsilane. The nanoparticles were characterized by SEM, energy-dispersive spectroscopy, and X-ray diffractometry. The nanoparticles were used for the extraction of 1,4-dichlorobenzene (1,4-DCB), 1,2,3-trichlorobenzene (1,2,3-TCB), 1,2,4-trichlorobenzene (1,2,4-TCB), and 1,2,3,4-tetrachlorobenzene (1,2,3,4-TeCB) from water, followed by their determination by GC-electron capture detection. Under optimal conditions, enrichment factors ranging from 220 to 360 were obtained. All determination coefficients (r(2)) are >0.99, and linear response is found in range 0.025-1.5 μg/L (at the lower end), and 6-120 μg/L (at the higher end). Detection limits are 6, 10, 11, and 500 ng/L for 1,2,3,4-TeCB, 1,2,4-TCB, 1,2,3-TCB, and 1,4-DCB, respectively. All RSDs are <6% (for n = 5). The method was successfully applied to the determination of CBs in environmental water samples.

  4. Suitability of magnetic particle immunoassay for the analysis of PBDEs in Hawaiian freshwater fish and crabs in comparison with gas chromatography/electron capture detection-ion trap mass spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A gas chromatograph/electron capture detector-ion trap mass spectrometer (GC/ECD-ITMS) was used for the determination of polybrominated diphenyl ethers (PBDEs) in freshwater fish and crabs. The samples were also analyzed with an enzyme-linked immunosorbent assay (ELISA). GC/ECD-ITMS results showed...

  5. Density functional theory study of the structural, electronic, lattice dynamical, and thermodynamic properties of Li4SiO4 and its capability for CO2 capture

    SciTech Connect

    Duan, Yuhua; Parlinski, K.

    2011-01-01

    The structural, electronic, lattice dynamical, optical, thermodynamic, and CO{sub 2} capture properties of monoclinic and triclinic phases of Li{sub 4}SiO{sub 4} are investigated by combining density functional theory with phonon lattice dynamics calculations. We found that these two phases have some similarities in their bulk and thermodynamic properties. The calculated bulk modulus and the cohesive energies of these two phases are close to each other. Although both of them are insulators, the monoclinic phase of Li{sub 4}SiO{sub 4} has a direct band gap of 5.24 eV while the triclinic Li{sub 4}SiO{sub 4} phase has an indirect band gap of 4.98 eV. In both phases of Li{sub 4}SiO{sub 4}, the s orbital of O mainly contributes to the lower-energy second valence band (VB{sub 2}) and the p orbitals contribute to the fist valence band (VB{sub 1}) and the conduction bands (CBs). The s orbital of Si mainly contributes to the lower portions of the VB1 and VB{sub 2}, and Si p orbitals mainly contribute to the higher portions of the VB{sub 1} and VB{sub 2}. The s and p orbitals of Li contribute to both VBs and to CBs, and Li p orbitals have a higher contribution than the Li s orbital. There is possibly a phonon soft mode existing in triclinic {gamma}-Li{sub 4}SiO{sub 4}; in the monoclinic Li{sub 4}SiO{sub 4}, there are three phonon soft modes, which correspond to the one type of Li disordered over a few sites. Their LO-TO splitting indicates that both phases of Li{sub 4}SiO{sub 4} are polar anisotropic materials. The calculated infrared absorption spectra for LO and TO modes are different for these two phases of Li{sub 4}SiO{sub 4}. The calculated relationships of the chemical potential versus temperature and CO{sub 2} pressure for reaction of Li{sub 4}SiO{sub 4} with CO{sub 2} shows that Li{sub 4}SiO{sub 4} could be a good candidate for a high-temperature CO{sub 2} sorbent while used for postcombustion capture technology.

  6. Density functional theory studies of the structural, electronic, and phonon properties of Li2O and Li2CO3 : Application to CO2 capture reaction

    NASA Astrophysics Data System (ADS)

    Duan, Yuhua; Sorescu, Dan C.

    2009-01-01

    The structural, electronic, and phonon properties of Li2O and Li2CO3 solids are investigated using density functional theory (DFT) and their thermodynamic properties for CO2 absorption and desorption reactions are analyzed. The calculated bulk properties for both the ambient- and the high-pressure phases of Li2O and Li2CO3 are in good agreement with available experimental measurements. The calculated band gap of the high-pressure phase of Li2O (8.37 eV, indirect) is about 3 eV larger than the one corresponding to the ambient Li2O phase (5.39 eV, direct), whereas the calculated band gap for the high-pressure phase of Li2CO3 (3.55 eV, indirect) is about 1.6 eV smaller than that for the ambient phase of Li2CO3 (5.10 eV, direct). The oxygen atoms in the ambient phase of the Li2CO3 crystal are not equivalent as reflected by two different sets of C-O bond lengths (1.28 and 1.31Å ) and they form two different groups. When Li2CO3 dissociates, one group of O forms Li2O , while the other group of O forms CO2 . The calculated phonon dispersion and density of states for the ambient phases of Li2O and Li2CO3 are in good agreement with experimental measurements and other available theoretical results. Li2O(s)+CO2(g)↔Li2CO3(s) is the key reaction of lithium salt sorbents (such as lithium silicates and lithium zircornates) for CO2 capture. The energy change and the chemical potential of this reaction have been calculated by combining DFT with lattice dynamics. Our results indicate that although pure Li2O can absorb CO2 efficiently, it is not a good solid sorbent for CO2 capture because the reverse reaction, corresponding to Li2CO3 releasing CO2 , can only occur at very low CO2 pressure and/or at very high temperature when Li2CO3 is in liquid phase.

  7. In matrix derivatization of trichloroethylene metabolites in human plasma with methyl chloroformate and their determination by solid-phase microextraction-gas chromatography-electron capture detector.

    PubMed

    Mudiam, Mohana Krishna Reddy; Jain, Rajeev; Varshney, Meenu; Ch, Ratnasekhar; Chauhan, Abhishek; Goyal, Sudhir Kumar; Khan, Haider A; Murthy, R C

    2013-04-15

    Trichloroethylene (TCE) is a common industrial chemical that has been widely used as metal degreaser and for many industrial purposes. In humans, TCE is metabolized into dichloroacetic acid (DCA), trichloroacetic acid (TCA) and trichloroethanol (TCOH). A simple and rapid method has been developed for the quantitative determination of TCE metabolites. The procedure involves the in situ derivatization of TCE metabolites with methyl chloroformate (MCF) directly in diluted plasma samples followed by extraction and analysis with solid-phase microextraction (SPME) coupled to gas chromatography-electron capture detector (GC-ECD). Factors which can influence the efficiency of derivatization such as amount of MCF and pyridine (PYR), ratio of water/methanol were optimized. The factors which can affect the extraction efficiencies of SPME were screened using 2(7-4) Placket-Burman Design (PBD). A central composite design (CCD) was then applied to further optimize the most significant factors for optimum SPME extraction. The optimum factors for the SPME extraction were found to be 562.5mg of NaCl, pH at 1 and an extraction time of 22 min. Recoveries and detection limits of all three analytes in plasma were found to be in the range of 92.69-97.55% and 0.036-0.068 μg mL(-1) of plasma, respectively. The correlation coefficients were found to be in the range of 0.990-0.995. The intra- and inter-day precisions for TCE metabolites were found to be in the range of 2.37-4.81% and 5.13-7.61%, respectively. The major advantage of this method is that MCF derivatization allows conversion of TCE metabolites into their methyl esters in very short time (≤30 s) at room temperature directly in the plasma samples, thus makes it a solventless analysis. The method developed was successfully applied to the plasma samples of humans exposed to TCE.

  8. Capturing Patient-Reported Outcome (PRO) Data Electronically: The Past, Present, and Promise of ePRO Measurement in Clinical Trials.

    PubMed

    Coons, Stephen Joel; Eremenco, Sonya; Lundy, J Jason; O'Donohoe, Paul; O'Gorman, Hannah; Malizia, William

    2015-08-01

    Patient-reported outcomes (PROs) are an important means of evaluating the treatment benefit of new medical products. It is recognized that PRO measures should be used when assessing concepts best known by the patient or best measured from the patient's perspective. As a result, there is growing emphasis on well defined and reliable PRO measures. In addition, advances in technology have significantly increased electronic PRO (ePRO) data collection capabilities and options in clinical trials. The movement from paper-based to ePRO data capture has enhanced the integrity and accuracy of clinical trial data and is encouraged by regulators. A primary distinction in the types of ePRO platforms is between telephone-based interactive voice response systems and screen-based systems. Handheld touchscreen-based devices have become the mainstay for remote (i.e., off-site, unsupervised) PRO data collection in clinical trials. The conventional approach is to provide study subjects with a handheld device with a device-based proprietary software program. However, an emerging alternative for clinical trials is called bring your own device (BYOD). Leveraging study subjects' own Internet-enabled mobile devices for remote PRO data collection (via a downloadable app or a Web-based data collection portal) has become possible due to the widespread use of personal smartphones and tablets. However, there are a number of scientific and operational issues that must be addressed before BYOD can be routinely considered as a practical alternative to conventional ePRO data collection methods. Nevertheless, the future for ePRO data collection is bright and the promise of BYOD opens a new chapter in its evolution.

  9. Separation and screening of short-chain chlorinated paraffins in environmental samples using comprehensive two-dimensional gas chromatography with micro electron capture detection.

    PubMed

    Xia, Dan; Gao, Lirong; Zhu, Shuai; Zheng, Minghui

    2014-11-01

    Short-chain chlorinated paraffins (SCCPs) are highly complex technical mixtures with thousands of isomers and numerous homologs. They are classified as priority candidate persistent organic pollutants under the Stockholm Convention for their persistence, bioaccumulation, and toxicity. Analyzing SCCPs is challenging because of the complexity of the mixtures. Chromatograms of SCCPs acquired using one-dimensional (1D) gas chromatography (GC) contain a large characteristic "peak" with a broad and unresolved profile. Comprehensive two-dimensional GC (GC×GC) shows excellent potential for separating complex mixtures. In this study, GC×GC coupled with micro electron capture detection (μECD) was used to separate and screen SCCPs. The chromatographic parameters, including the GC column types, oven temperature program, and modulation period, were systematically optimized. The SCCP congeners were separated into groups using a DM-1 column connected to a BPX-50 column. The SCCP congeners in technical mixtures were separated according to the number of chlorine substituents for a given carbon chain length and according to the number of carbon atoms plus chlorine atoms for different carbon chain lengths. A fish tissue sample was analyzed to illustrate the feasibility of the GC×GC-μECD method in analyzing biological samples. Over 1,500 compounds were identified in the fish extract, significantly more than were identified using 1D GC. The detection limits for five selected SCCP congeners were between 1 and 5 pg/L using the GC×GC method, and these were significantly lower than those achieved using 1D GC. This method is a good choice for analysis of SCCPs in environmental samples, exhibiting good separation and good sensitivity.

  10. Electron capture gas-liquid chromatographic study of metabolites produced by some arthritic transudate-associated organisms in vitro and in vivo in rabbit models.

    PubMed

    Brooks, J B; Melton, A R

    1978-10-01

    Computerized, frequency-pulsed, modulated electron capture gas-liquid chromatography was used to study the acid metabolites produced in vitro in fetal calf serum and in vivo in an animal chamber model. Several strains of Diplostreptococcus agalactiae, Propionibacterium acnes, Staphylococcus aureus, and Streptococcus serogroups A, B, and G were studied. All of these organisms have been reported to be associated with arthritic transudates in humans. Metabolites were detected by this method from derivatized extracts of both spent fetal calf serum and chamber fluids. Since there was little host response to the organisms cultured in the chambers, it is highly probable that the products detected represent metabolites produced in an in vivo type of environment. The metabolic patterns were reproducible and exhibited many similarities in vitro and in vivo. Production of the acids detected was reproducible, and these acids were useful identification markers. The data support published reports (J. B. Brooks, C. C. Alley, and J. A. Liddle, Anal. Chem. 46: 1930-1934, 1974; J. B. Brooks, G. Choudhary, R. B. Craven, D. Edman, C. C. Alley, and J. A. Liddle, J. Clin. Microbiol. 5:625-628, 1977; J. B. Brooks, R. B. Craven, A. R. Melton, and C. C. Alley, in H. H. Johnson and W. B. Newson, ed., Second International Symposium on Rapid Methods and Automation on Microbiology, 1976; J. B. Brooks, R. B. Craven, D. Schlossberg, C. C. Alley, and F. M. Pitts, J. Clin. Microbiol. 8:203-208, 1978; J. B. Brooks, D. S. Kellogg, C. C. Alley, H. B. Short, and H. H. Handsfield, J. Infect. Dis. 129:660-668, 1974) that bacterial metabolites might be detectable in diseased body fluids. The growth characteristics of the organisms in the animal model and fetal calf serum are discussed, and a moderately priced computer for performing data manipulations is evaluated.

  11. Dispersive liquid-liquid microextraction for the determination of organochlorine pesticides residues in honey by gas chromatography-electron capture and ion trap mass spectrometric detection.

    PubMed

    Zacharis, Constantinos K; Rotsias, Ilias; Zachariadis, Petros G; Zotos, Anastasios

    2012-10-01

    A simple dispersive liquid-liquid microextraction (DLLME) protocol for the determination of 15 organochlorine pesticides residues in honey is proposed. The selected pesticides were separated using gas chromatography and detected by electron capture (ECD) or ion trap mass spectrometry (GC-IT/MS). Several parameters affecting the extraction efficiency namely type and volume of organic extraction solvent, type and volume of disperser solvent, sample pH, ionic strength, extraction time and centrifugation speed were systematically investigated. The final DLLME protocol involved the addition of 750 μL acetonitrile (disperser) and 50 μL chloroform (extraction solvent) into a 5 mL aqueous honey solution followed by centrifugation. The sedimented organic phase (chloroform) were analysed directly by GC-IT/MS or evaporated and reconstituted in acetonitrile prior to the GC-ECD analysis. The analytical performance of the GC-ECD and GC-IT/MS methods was compared and discussed. Under the selected experimental conditions, the enrichment factors varied between of 36 and 114. The limits of detection (LOD) were in the range of 0.02-0.15 μg L(-1) (0.4-3 ng g(-1)) for GC-ECD and 0.01-0.2 μg L(-1) (0.2-4 ng g(-1)) for GC-IT/MS which is adequate to verify compliance of products to legal tolerances. The proposed method was applied to the analysis of the selected organochlorine pesticides residues in various honey samples obtained from Greek region. Mean recoveries were ranged from 75% to 119% while the precision was better than 20% in both methodologies.

  12. Use of solid-phase microextraction/gas chromatography-electron capture detection for the determination of energetic chemicals in marine samples.

    PubMed

    Monteil-Rivera, Fanny; Beaulieu, Chantale; Hawari, Jalal

    2005-02-25

    Gas chromatography with electron capture detection (GC-ECD) is a highly explosive-sensitive analytical technique. However, its application to the analysis of sediment extracts is hampered by the presence of numerous endogenous interferences. In the present study, solid-phase microextraction (SPME) was used both as a purification technique for sediment extracts and as an extraction technique for water samples prior to analysis by GC-ECD. SPME/GC-ECD coupling was optimized and applied to the trace analysis of nine explosives including nitroaromatics and RDX in real seawater and marine sediment samples. Addition of a high concentration of salt (30%, w/v) in the aqueous medium and use of a carbowax/divinylbenzene (CW/DVB) coating led to optimal extraction efficiencies. Method detection limits (MDLs) ranged from 0.05 to 0.81 microg/L in water and from 1 to 9 microg/kg in dry sediment. Except for RDX, spike recoveries in seawater were satisfactory (89-147%) when samples were fortified at 2 microg/L of each analyte. Spike recoveries from dry sediment fortified at 10 microg/kg of each analyte gave lower recoveries but these could also be due to degradation in the matrix. With a smaller volume of aqueous sample required compared to solid-phase extraction (SPE), SPME is an attractive method for the analysis of limited volumes of sediment pore-water. Moreover, the use of SPME eliminated interferences present in sediment extracts thus allowing the detection of the target analytes that were otherwise difficult to detect by direct injection.

  13. Determination of the enantiomer fraction of PBB 149 by gas chromatography/electron capture negative ionization tandem mass spectrometry in the selected reaction monitoring mode.

    PubMed

    von der Recke, Roland; Mariussen, Espen; Berger, Urs; Götsch, Arntraut; Herzke, Dorte; Vetter, Walter

    2005-01-01

    Enantioselective determination of the atropisomers of 2,2',3,4',5',6-hexabromobiphenyl (PBB 149) in a purified sample from a bird egg was attempted in this work. By application of the classic method for PBB determination, i.e. gas chromatography coupled to electron capture negative ionization mass spectrometry (GC/ECNI-MS) using the bromide ions, the enantiomers interfered with another brominated compound. Subsequent measurements clarified that this interference did not occur in the mass chromatogram of the molecular ion of PBB 149. Therefore, a GC/ECNI tandem mass spectrometry (MS/MS) method was developed, based on the fragmentation of [M]-. A suitable precursor-product ion transition was found for m/z 627.5 --> 80 +/- 1.5, representing the most abundant ion trace of the molecular ion and the bromide ions. Optimization of the ion source temperature, the methane gas pressure, and the collision voltages resulted in a robust method that could solve the problem. Subsequent injections of a technical PBB product (Firemaster BP-6) resulted in the anticipated racemic proportion (enantiomer fraction (EF) = 0.50 +/- 0.02 (n = 8)). By contrast, the EF in the purified extract of a bird egg was found to be 0.42 +/- 0.02 (n = 10), indicative of a significant enantioenrichment of the second eluting atropisomer. Additional measurements were performed on a non-chiral column. These measurements allowed for the detection of 16 hexabromobiphenyls (hexa-BBs) in Firemaster BP-6. These comparisons verified that PBB 149 enantiomers did not interfere with an isomer that could falsify the enantiomer fraction in the sample. The novel method using GC/ECNI-MS/MS in the selected reaction monitoring (SRM) mode was eight times more sensitive than application of conventional GC/ECNI-MS selected ion monitoring (SIM) analysis of the molecular ion.

  14. Gas-Phase Structure of Amyloid-β (12 - 28) Peptide Investigated by Infrared Spectroscopy, Electron Capture Dissociation and Ion Mobility Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Le, Thi Nga; Poully, Jean Christophe; Lecomte, Frédéric; Nieuwjaer, Nicolas; Manil, Bruno; Desfrançois, Charles; Chirot, Fabien; Lemoine, Jerome; Dugourd, Philippe; van der Rest, Guillaume; Grégoire, Gilles

    2013-12-01

    The gas-phase structures of doubly and triply protonated Amyloid-β12-28 peptides have been investigated through the combination of ion mobility (IM), electron capture dissociation (ECD) mass spectrometry, and infrared multi-photon dissociation (IRMPD) spectroscopy together with theoretical modeling. Replica-exchange molecular dynamics simulations were conducted to explore the conformational space of these protonated peptides, from which several classes of structures were found. Among the low-lying conformers, those with predicted diffusion cross-sections consistent with the ion mobility experiment were further selected and their IR spectra simulated using a hybrid quantum mechanical/semiempirical method at the ONIOM DFT/B3LYP/6-31 g(d)/AM1 level. In ECD mass spectrometry, the c/z product ion abundance (PIA) has been analyzed for the two charge states and revealed drastic differences. For the doubly protonated species, N - Cα bond cleavage occurs only on the N and C terminal parts, while a periodic distribution of PIA is clearly observed for the triply charged peptides. These PIA distributions have been rationalized by comparison with the inverse of the distances from the protonated sites to the carbonyl oxygens for the conformations suggested from IR and IM experiments. Structural assignment for the amyloid peptide is then made possible by the combination of these three experimental techniques that provide complementary information on the possible secondary structure adopted by peptides. Although globular conformations are favored for the doubly protonated peptide, incrementing the charge state leads to a conformational transition towards extended structures with 310- and α-helix motifs.

  15. Dispersive liquid-liquid microextraction method based on solidification of floating organic drop combined with gas chromatography with electron-capture or mass spectrometry detection.

    PubMed

    Leong, Mei-I; Huang, Shang-Da

    2008-11-21

    A simple dispersive liquid-liquid microextraction (DLLME) method based on solidification of a floating organic drop (DLLME-SFO) technique combined with gas chromatography/electron-capture detection (GC/ECD) or gas chromatography/mass spectrometry (GC/MS) has been developed. The proposed method is simple, low in cost, and of high precision. It overcomes the most important problem in DLLME, the high-toxic solvent used. Halogenated organic compounds (HOCs) in water samples were determined as the model compounds. The parameters optimized for the DLLME-SFO technique were as follows: A mixture of 0.5 mL acetone, containing 10 microL 2-dodecanol (2-DD-OH), was rapidly injected by syringe into the 5 mL water sample. After centrifugation, the fine 2-DD-OH droplets (8+/-0.5 microL) were floated at the top of the screwcap test tube. The test tube was then cooled in an ice bath. After 5 min the 2-DD-OH solvent had solidified and was then transferred into a conical vial; it melted quickly at room temperature and 3 microL (for GC/ECD) or 2 microL (for GC/MS) of it was injected into a gas chromatograph for analysis. The limit of detection (LOD) for this technique was 0.005-0.05microgL(-1) for GC/ECD and was 0.005-0.047 microgL(-1) for GC/MS, respectively. The linear range of the calibration curve of DLLME-SFO was from 0.01 to 500 microgL(-1) with a coefficient of estimation (r2)>0.996 for GC/ECD and was from 0.02 to 500 microgL(-1) with a coefficient of estimation (r2)>0.996 for GC/MS.

  16. Determination of chlorinated insecticides in bottom sediment using an electron-capture gas chromatography screening method, Austin, Texas, 1991 and 1992

    USGS Publications Warehouse

    Brock, Robert D.; Murtagh, Lucinda K.

    1994-01-01

    Twenty-two bottom-sediment samples were collected from Town Lake in Austin, Texas, in 1991 and 1992 and analyzed for chlorinated insecticides by a reconnaissance-quality, electron-capture gas chromatography screening method developed by the U.S. Geological Survey (USGS). Four different chlorinated insecticides (aldrin, chlordane, dieldrin, and p,p'-DDT) and two degradation products of p,p'-DDT (p,p'-DDD and p,p'-DDE) were detected in these samples. The most significant insecticides detected were chlordane, which was detected in 20 of the 22 samples at concentrations that ranged from 26 to 140 micrograms per kilogram, and p,p'-DDT, which was detected in all 22 samples at concen- trations that ranged from 5 to 40 micrograms per kilogram. Degradation products of p,p'-DDT were detected in all 22 samples. Concentrations of p,p'-DDD ranged from not detected to 117 micrograms per kilogram and for p,p'-DDE from 9 to 97 micrograms per kilogram. Of the 22 samples collected, 15 also were analyzed by the standard USGS laboratory analytical method for chlorinated insecticides to determine the comparability of the two methods. Correlation coefficients were calculated for chlordane (0.8662), p,p'-DDT (0.6393), p,p'-DDD (0.9401), p,p'-DDE (0.8595), and dieldrin (0.3819). A paired sign test at the 95 percent confidence level showed no significant difference between the screening method and laboratory analytical method for all detected insecticides except aldrin. P-values were calculated from the data for chlordane (l.0000), p,p'-DDT (0.1796), p,p'-DDD (l,0000), p,p'-DDE (0.1796), and dieldrin (0.2891).

  17. Gas chromatographic method using electron-capture detection for the determination of musk xylene in human blood samples. Biological monitoring of the general population.

    PubMed

    Angerer, J; Käfferlein, H U

    1997-05-23

    Musk xylene (2,4,6-trinitro-1,3-dimethyl-5-tert.-butylbenzene, MX), a synthetic musk often used in different fragrances and soaps to substitute the natural musk, is a potential contaminant of humans. In this publication, a specific and sensitive detection method for the determination of musk xylene in human blood samples is described. The clean-up of the blood samples includes an extraction step followed by a solid-phase adsorption to separate MX from other plasma components. Separation and detection was carried out by capillary gas chromatography and an electron capture detector (GC-ECD). The results were verified using qualitative capillary gas chromatography and a mass selective detector with electron impact ionisation (GC-EI-MS). epsilon-Hexachlorocyclohexane (epsilon-HCH) is used as internal standard. The reliability of the GC-ECD method has been proved. The relative standard deviations of the within-series imprecision were 12.7% for samples with a concentration of 0.5 microg/l and 2.1% for samples with a concentration of 5.0 microg/l, whereas the relative standard deviations for the between-day imprecision were 14.9% (0.5 microg/l samples) and 3.4% (5.0 microg/l samples). The losses during sample treatment were between 10.1% and 17.8%. No interfering peaks were observed. The absolute detection limit was 0.1 microg/l plasma. A total of 72 human blood samples were analysed to determine the MX concentrations within the general population. In 66 of the 72 human blood samples, the MX concentrations ranged from 0.10 to 1.12 microg/l plasma for the described method. In six samples no MX was detected. The median concentration was 0.24+/-0.23 microg MX/l plasma. The 95 percentile was 0.79 microg/l. No correlation could be found between MX concentrations and smoking habit, broca index, age, sex as well as fish consumption habits. Nevertheless, the results demonstrate the exposure of the general population to MX.

  18. The AtChem On-line model and Electronic Laboratory Notebook (ELN): A free community modelling tool with provenance capture

    NASA Astrophysics Data System (ADS)

    Young, J. C.; Boronska, K.; Martin, C. J.; Rickard, A. R.; Vázquez Moreno, M.; Pilling, M. J.; Haji, M. H.; Dew, P. M.; Lau, L. M.; Jimack, P. K.

    2010-12-01

    AtChem On-line1 is a simple to use zero-dimensional box modelling toolkit, developed for use by laboratory, field and chamber scientists. Any set of chemical reactions can be simulated, in particular the whole Master Chemical Mechanism (MCM2) or any subset of it. Parameters and initial data can be provided through a self-explanatory web form and the resulting model is compiled and run on a dedicated server. The core part of the toolkit, providing a robust solver for thousands of chemical reactions, is written in Fortran and uses SUNDIALS3 CVODE libraries. Chemical systems can be constrained at multiple, user-determined timescales; this enabled studies of radical chemistry at one minute timescales. AtChem On-line is free to use and requires no installation - a web browser, text editor and any compressing software is all the user needs. CPU and storage are provided by the server (input and output data are saved indefinitely). An off-line version is also being developed, which will provide batch processing, an advanced graphical user interface and post-processing tools, for example, Rate of Production Analysis (ROPA) and chainlength analysis. The source code is freely available for advanced users wishing to adapt and run the program locally. Data management, dissemination and archiving are essential in all areas of science. In order to do this in an efficient and transparent way, there is a critical need to capture high quality metadata/provenance for modelling activities. An Electronic Laboratory Notebook (ELN) has been developed in parallel with AtChem Online as part of the EC EUROCHAMP24 project. In order to use controlled chamber experiments to evaluate the MCM, we need to be able to archive, track and search information on all associated chamber model runs, so that they can be used in subsequent mechanism development. Therefore it would be extremely useful if experiment and model metadata/provenance could be easily and automatically stored electronically

  19. Continuum capture in the three-body problem

    SciTech Connect

    Sellin, I A

    1980-01-01

    The three-body problem, especially the problem of electron capture to the continuum in heavy particle collisions is reviewed. Major topics covered include: second born-induced asymmetry in electron capture to the continuum; historical context, links to other tests of atomic scattering theory; experiments characterizing the velocity distribution of ECC electrons; other atomic physics tests of high velocity Born expansions; atom capture; capture by positrons; and pion capture to the continuum. (GHT)

  20. The Crab nebula and the class of Type IIn-P supernovae caused by sub-energetic electron-capture explosions

    NASA Astrophysics Data System (ADS)

    Smith, Nathan

    2013-09-01

    What sort of supernova (SN) gave rise to the Crab nebula? While there are several indications that the Crab arose from a sub-energetic explosion of an 8-10 M⊙ progenitor star, this would appear to conflict with the high luminosity indicated by historical observations. This paper shows that several well-known observed properties of the Crab and SN 1054 are well matched by a particular breed of Type IIn SN. The Crab's properties are best suited to the Type IIn-P subclass (Type IIn spectra with plateau light curves), exemplified by SNe 1994W, 2009kn and 2011ht. These events probably arise from relatively low energy (1050 erg) explosions with low 56Ni yield that may result from electron-capture SN (ecSN) explosions, but their high visual-wavelength luminosity and Type IIn spectra are dominated by shock interaction with dense circumstellar material (CSM) rather than the usual recombination photosphere. In this interaction, a large fraction of the 1050 erg of the total kinetic energy can be converted to visual-wavelength luminosity. After about 120 d, nearly all of the mass outside the neutron star in the CSM and ejecta ends up in a slowly expanding (1000-1500 km s-1) thin dense shell, which is then accelerated and fragmented by the growing pulsar wind nebula in the subsequent 1000 yr, producing the complex network of filaments seen today. There is no need to invoke the extended, invisible fast SN envelope hypothesized to reside outside the Crab. As differentiated from a normal SN II-P, SNe IIn-P provide a much better explanation for several observed features of the Crab: (1) no blast wave outside the Crab nebula filaments, (2) no rapidly expanding SN envelope outside the filaments, (3) a total mass of ˜5 M⊙ swept up in a thin slow shell, (4) a low kinetic energy of the Crab at least an order of magnitude below a normal core-collapse SN, (5) a high peak luminosity (-18 mag) despite the low kinetic energy, (6) chemical abundances consistent with an 8-10 M⊙ star and

  1. Simultaneous analysis of polychlorinated biphenyls and organochlorine pesticides in seawater samples by membrane-assisted solvent extraction combined with gas chromatography-electron capture detector and gas chromatography-tandem mass spectrometry.

    PubMed

    Shi, Xizhi; Tang, Zigang; Sun, Aili; Zhou, Lei; Zhao, Jian; Li, Dexiang; Chen, Jiong; Pan, Daodong

    2014-12-01

    A highly efficient and environment-friendly membrane-assisted solvent extraction system combined with gas chromatography-electron capture detector was applied in the simultaneous determination of 17 polychlorinated biphenyls and organochlorine pesticides in seawater samples. Variables affecting extraction efficiency, including extraction solvent used, stirring rate, extraction time, and temperature, were optimized extensively. Under optimal extraction conditions, recoveries between 76.9% and 104.6% in seawater samples were achieved, and relative standard deviation values below 10% were obtained. The limit of detection (signal-to-noise ratio=3) and limit of quantification (signal-to-noise ratio=10) of 17 polychlorinated biphenyls and organochlorine pesticides in seawater ranged from 0.14ngL(-1) to 0.36ngL(-1) and 0.46ngL(-1) to 1.19ngL(-1), respectively. Matrix effects on extraction efficiency were evaluated by comparing with the results obtained using tap water. The extraction effect of developed membrane-assisted solvent extraction method was further demonstrated by gas chromatography-tandem mass spectrometry which can provide structural information of the analytes for more accurate identification, and results identical to those produced by gas chromatography-electron capture detector were obtained. These findings demonstrate the applicability of the developed membrane-assisted solvent extraction determination method for coupling to gas chromatography-electron capture detector or tandem mass spectrometry for determining polychlorinated biphenyls and organochlorine pesticides in seawater samples.

  2. Evidence from Voyager and ISEE-3 spacecraft. Data for the decay of secondary K-electron capture isotopes during the propagation of cosmic rays in the Galaxy

    NASA Astrophysics Data System (ADS)

    Soutoul, A.; Legrain, R.; Lukasiak, A.; McDonald, F. B.; Webber, W. R.

    1998-08-01

    New data from the cosmic ray experiment on the Voyager spacecraft confirms and extends earlier data from a similar experiment on the ISEE-3 spacecraft which indicates the possibility of the decay of certain K-capture isotopes during the interstellar propagation of galactic cosmic rays. These cosmic ray measurements, along with the cross section measurements, indicate that ~ 25% of the K-capture isotopes (51Cr and (49V produced as secondaries have decayed at interstellar energy of ~ 400 MeV/nuc. This suggests a possible interstellar energy gain ~ 100 MeV/nuc out of the current interstellar energy ~ 500 MeV/nuc. This measurement suggests that the study of the K-capture isotopes may now have reached a level that will soon provide definitive information on the amount of re-acceleration that may occur during cosmic-ray propagation after an initial acceleration in the cosmic ray sources.

  3. Capturing Callisto

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The New Horizons Long Range Reconnaissance Imager (LORRI) captured these two images of Jupiter's outermost large moon, Callisto, as the spacecraft flew past Jupiter in late February. New Horizons' closest approach distance to Jupiter was 2.3 million kilometers (1.4 million miles), not far outside Callisto's orbit, which has a radius of 1.9 million kilometers (1.2 million miles). However, Callisto happened to be on the opposite side of Jupiter during the spacecraft's pass through the Jupiter system, so these images, taken from 4.7 million kilometers (3.0 million miles) and 4.2 million kilometers (2.6 million miles) away, are the closest of Callisto that New Horizons obtained.

    Callisto's ancient, crater-scarred surface makes it very different from its three more active sibling satellites, Io, Europa and Ganymede. Callisto, 4,800 kilometers (3000 miles) in diameter, displays no large-scale geological features other than impact craters, and every bright spot in these images is a crater. The largest impact feature on Callisto, the huge basin Valhalla, is visible as a bright patch at the 10 o'clock position. The craters are bright because they have excavated material relatively rich in water ice from beneath the dark, dusty material that coats most of the surface.

    The two images show essentially the same side of Callisto -- the side that faces Jupiter -- under different illumination conditions. The images accompanied scans of Callisto's infrared spectrum with New Horizons' Linear Etalon Imaging Spectral Array (LEISA). The New Horizons science team designed these scans to study how the infrared spectrum of Callisto's water ice changes as lighting and viewing conditions change, and as the ice cools through Callisto's late afternoon. The infrared spectrum of water ice depends slightly on its temperature, and a goal of New Horizons when it reaches the Pluto system (in 2015) is to use the water ice features in the spectrum of Pluto's moon Charon, and

  4. Single-electron capture processes in slow collisions of He{sup 2+} ions with O{sub 2}, NH{sub 3}, N{sub 2}, and CO{sub 2}

    SciTech Connect

    Abu-Haija, O.; Kamber, E.Y.; Ferguson, S.M.; Stolterfoht, N.

    2005-10-15

    Using the translational energy-gain spectroscopy technique, we have measured the energy-gain spectra and absolute total cross sections for single-electron capture (SEC) in collisions of He{sup 2+} ions with O{sub 2}, NH{sub 3}, N{sub 2}, and CO{sub 2} at laboratory impact energies between 25 and 400 eV/amu. The measured spectra for the He{sup 2+}-N{sub 2} and CO{sub 2} collision systems show that the dominant reaction channel is due to dissociative transfer ionization (i.e., SEC accompanied by ionization of the molecular target ion). In the case of the He{sup 2+}-NH{sub 3} collision system, nondissociative single-electron capture into n=2 states of He{sup +} with production of NH{sub 3}{sup +} in the ground state is predominantly populated. These processes are observed to be the dominant reaction channels over the entire impact energy region studied and at laboratory scattering angles between 0 deg. and 8 deg. The energy dependence of total cross sections for SEC are also measured and found to slowly increase with increasing impact energies. The measured cross sections are also compared with the available measurements and theoretical results based on the Demkov and Landau-Zener models.

  5. The Use of Integrated Electronic Data Capture and Analysis for Accelerator Construction and Commissioning: Pansophy from the SNS Towards the ILC

    SciTech Connect

    J. P. Ozelis; V. Bookwalter; B. Madre; C. E. Reece

    2005-05-01

    Jefferson Lab has extensively used a proprietary web-based system (Pansophy) that integrates commercial database, data analysis, document archiving and retrieval, and user interface software, as a coherent knowledge management product during the construction of the cryomodules for the SNS Superconducting Linac, providing elements of process and procedure control, data capture and review, and data mining and analysis. With near real-time and potentially global access to production data, process monitoring and performance analyses could be pursued in a timely manner, providing crucial feedback. The extensibility, portability, and accessibility of Pansophy via universally available software components provide the essential features needed in any information and project management system capable of meeting the needs of future accelerator construction efforts, requiring an unprecedented level of regional and international coordination and collaboration, to which Pansophy is well suited.

  6. A study of Channeling, Volume Reflection and Volume Capture of 3.35 - 14.0 GeV Electrons in a bent Silicon Crystal

    SciTech Connect

    Wistisen, T. N.; Uggerhoj, U. I.; Wienands, U.; Markiewicz, T. W.; Noble, R. J.; Benson, B. L.; Smith, T.; Bagli, E.; Bandiera, L.; Germogli, G.; Guidi, V.; Mazzolari, A.; Holtzapple, R.; Tucker, S.

    2015-12-03

    We present the experimental data and analysis of experiments conducted at SLAC National Accelerator Laboratory investigating the processes of channeling, volume-reflection and volume-capture along the (111) plane in a strongly bent quasi-mosaic silicon crystal. Additionally, these phenomena were investigated at 5 energies: 3.35, 4.2, 6.3, 10.5 and 14.0 GeV with a crystal with bending radius of 0.15m, corresponding to curvatures of 0.070, 0.088, 0.13, 0.22 and 0.29 times the critical curvature respectively. We have extracted important parameters describing the channeling process such as the dechanneling length, the angle of volume reflection, the surface transmission and the widths of the distribution of channeled particles parallel and orthogonal to the plane.

  7. The Bells' Capture note TH-3054-CERN

    SciTech Connect

    Hartouni, Ed P.

    2014-01-29

    This document revisits the paper by M. Bell and J. S. Bell “Capture of Cooling Electrons by Cool Protons” TH-3054-CERN (March 30, 1981). I expand the treatment to include e+e- capture.

  8. STUDENT AWARD FINALIST: Projectile Coherence Effects in Single and Dissociative Electron Capture in Collision of Protons with H2 and He

    NASA Astrophysics Data System (ADS)

    Sharma, Sachin; Hasan, Ahmad; Egodapitiya, Kisra; Arthanayaka, Thusitha; Sakhelashvili, Giorgi; Schulz, Michael

    2012-10-01

    Recently, we have observed that interference effects, similar to optical Young double-slit interference, in the projectile scattering angle dependent ionization cross sections of H2 by 75 keV proton impact are present or not depending on the projectile coherence. This suggests that atomic scattering cross sections in general are sensitive to the projectile coherence, an aspect which has been overlooked for decades. To investigate this effect further, we have measured differential cross sections for single and dissociative capture for 75 and 25 keV protons colliding with H2 and He. A significant sensitivity of the cross sections to the projectile coherence was confirmed. For 25 keV we found that interference due to different impact parameters leading to the same scattering angle dominates over molecular two-center interference. This important observation sets the stage for resolving heatedly debated discrepancies between theory and experiment for ionization of He by 100 MeV/amu C^6+ impact.

  9. An investigation of used electronics return flows: a data-driven approach to capture and predict consumers storage and utilization behavior.

    PubMed

    Sabbaghi, Mostafa; Esmaeilian, Behzad; Raihanian Mashhadi, Ardeshir; Behdad, Sara; Cade, Willie

    2015-02-01

    Consumers often have a tendency to store their used, old or un-functional electronics for a period of time before they discard them and return them back to the waste stream. This behavior increases the obsolescence rate of used still-functional products leading to lower profitability that could be resulted out of End-of-Use (EOU) treatments such as reuse, upgrade, and refurbishment. These types of behaviors are influenced by several product and consumer-related factors such as consumers' traits and lifestyles, technology evolution, product design features, product market value, and pro-environmental stimuli. Better understanding of different groups of consumers, their utilization and storage behavior and the connection of these behaviors with product design features helps Original Equipment Manufacturers (OEMs) and recycling and recovery industry to better overcome the challenges resulting from the undesirable storage of used products. This paper aims at providing insightful statistical analysis of Electronic Waste (e-waste) dynamic nature by studying the effects of design characteristics, brand and consumer type on the electronics usage time and end of use time-in-storage. A database consisting of 10,063 Hard Disk Drives (HDD) of used personal computers returned back to a remanufacturing facility located in Chicago, IL, USA during 2011-2013 has been selected as the base for this study. The results show that commercial consumers have stored computers more than household consumers regardless of brand and capacity factors. Moreover, a heterogeneous storage behavior is observed for different brands of HDDs regardless of capacity and consumer type factors. Finally, the storage behavior trends are projected for short-time forecasting and the storage times are precisely predicted by applying machine learning methods.

  10. Liquid chromatography electron capture dissociation tandem mass spectrometry (LC-ECD-MS/MS) versus liquid chromatography collision-induced dissociation tandem mass spectrometry (LC-CID-MS/MS) for the identification of proteins.

    PubMed

    Creese, Andrew J; Cooper, Helen J

    2007-05-01

    Electron capture dissociation (ECD) offers many advantages over the more traditional fragmentation techniques for the analysis of peptides and proteins, although the question remains: How suitable is ECD for incorporation within proteomic strategies for the identification of proteins? Here, we compare LC-ECD-MS/MS and LC-CID-MS/MS as techniques for the identification of proteins. Experiments were performed on a hybrid linear ion trap-Fourier transform ion cyclotron resonance mass spectrometer. Replicate analyses of a six-protein (bovine serum albumin, apo-transferrin, lysozyme, cytochrome c, alcohol dehydrogenase, and beta-galactosidase) tryptic digest were performed and the results analyzed on the basis of overall protein sequence coverage and sequence tag lengths within individual peptides. The results show that although protein coverage was lower for LC-ECD-MS/MS than for LC-CID-MS/MS, LC-ECD-MS/MS resulted in longer peptide sequence tags, providing greater confidence in protein assignment.

  11. Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of organochlorine pesticides and polychlorinated biphenyls in bottom sediment by dual capillary-column gas chromatography with electron-capture detection

    USGS Publications Warehouse

    Foreman, William T.; Connor, Brooke F.; Furlong, Edward T.; Vaught, Deborah G.; Merten, Leslie M.

    1995-01-01

    A method for the determination of 30 individual organochlorine pesticides, total toxaphene, and total polychlorinated biphenyls (PCBs) in bottom sediment is described. The method isolates the pesticides and PCBs by solvent extraction with dichlorobenzene, removes inorganic sulfur, large naturally occurring molecules, and other unwanted interferences by gel permeation chromatography, and further cleans up and class fractionates the extract using adsorption chromatography. The com- pounds then are instrumentally determined using dual capillary-column gas chromatography with electron-capture detection. Reporting limits range from 1 to 5 micrograms per kilogram for 30 individual pesticides, 50 micrograms per kilogram for total PCBs, and 200 micrograms per kilogram for total toxaphene. The method also is designed to allow the simultaneous isolation of 79 other semivolatile organic compounds from the sediment, which are separately quantified using gas chromatography with mass spectrometric detection. The method was developed in support of the U.S. Geological Survey's National Water-Quality Assessment program.

  12. Methyl sulfonyl polychlorinated biphenyls and 2,2-bis(4-chlorophenyl)-1,1-dichlorethene in gray seal tissues determined by gas chromatography with electron capture detection and atomic emission detection

    SciTech Connect

    Janak, K.; Becker, G.; Colmisjoe, A.; Oestman, C.; Athanasiadou, M.; Valters, K.; Bergman, A.

    1998-06-01

    The presence of 24 methyl sulfonyl polychlorinated biphenyl (PCB) congeners (MeSO{sub 2}-CBs) and 3-methyl sulfonyl 2,2-bis(4-chlorophenyl)-1,1-dichlorethene (DDE) (MeSO{sub 2}-DDE), metabolites of PCB and DDE, in blubber, lung, and liver of gray seals has been determined by using atomic emission detection (AED) and electron capture detection (ECD). Selective accumulation of aryl methyl sulfones in blubber, liver, and lung tissue was also investigated. For the liver samples, a substantial and highly specific retention of PCB methyl sulfones was observed. The atomic emission technique significantly improved the determination of measured solutes compared with ECD. Atomic emission detection was also valuable for the monitoring of the prefractionation and to decrease the requirements of sample clean-up. Comparing both detection techniques showed a good correlation between the results of the AED sulfur-selective line and ECD.

  13. Automated determination of pesticide residues in olive oil by on-line reversed-phase liquid chromatography-gas chromatography using the through oven transfer adsorption desorption interface with electron-capture and nitrogen-phosphorus detectors operating simultaneously.

    PubMed

    Díaz-Plaza, Eva M; Cortés, Jose M; Vázquez, Ana; Villén, Jesús

    2007-12-07

    A rapid method for the multiresidue analysis of pesticides in olive oil is presented. Pesticides are analyzed by on-line coupling reversed-phase liquid chromatography-gas chromatography using the through oven transfer adsorption desorption (TOTAD) interface with subsequent simultaneous electron-capture and nitrogen-phosphorus detection by post-column splitter. An autosampler is employed and the olive oil is simply filtered before the chromatographic analysis. Organophosphorus, organochlorine and triazine pesticides are determined in one run. The limits of detection are below the required maximum residue levels and calibration curves are linear in the range tested. Repeatabilities (intra-day and inter-days) are good. The method was satisfactory applied to the routine analysis of numerous olive oil samples.

  14. An investigation of used electronics return flows: A data-driven approach to capture and predict consumers storage and utilization behavior

    SciTech Connect

    Sabbaghi, Mostafa; Esmaeilian, Behzad; Raihanian Mashhadi, Ardeshir; Behdad, Sara; Cade, Willie

    2015-02-15

    Highlights: • We analyzed a data set of HDDs returned back to an e-waste collection site. • We studied factors that affect the storage behavior. • Consumer type, brand and size are among factors which affect the storage behavior. • Commercial consumers have stored computers more than household consumers. • Machine learning models were used to predict the storage behavior. - Abstract: Consumers often have a tendency to store their used, old or un-functional electronics for a period of time before they discard them and return them back to the waste stream. This behavior increases the obsolescence rate of used still-functional products leading to lower profitability that could be resulted out of End-of-Use (EOU) treatments such as reuse, upgrade, and refurbishment. These types of behaviors are influenced by several product and consumer-related factors such as consumers’ traits and lifestyles, technology evolution, product design features, product market value, and pro-environmental stimuli. Better understanding of different groups of consumers, their utilization and storage behavior and the connection of these behaviors with product design features helps Original Equipment Manufacturers (OEMs) and recycling and recovery industry to better overcome the challenges resulting from the undesirable storage of used products. This paper aims at providing insightful statistical analysis of Electronic Waste (e-waste) dynamic nature by studying the effects of design characteristics, brand and consumer type on the electronics usage time and end of use time-in-storage. A database consisting of 10,063 Hard Disk Drives (HDD) of used personal computers returned back to a remanufacturing facility located in Chicago, IL, USA during 2011–2013 has been selected as the base for this study. The results show that commercial consumers have stored computers more than household consumers regardless of brand and capacity factors. Moreover, a heterogeneous storage behavior is

  15. Video Screen Capture Basics

    ERIC Educational Resources Information Center

    Dunbar, Laura

    2014-01-01

    This article is an introduction to video screen capture. Basic information of two software programs, QuickTime for Mac and BlueBerry Flashback Express for PC, are also discussed. Practical applications for video screen capture are given.

  16. On capturing the grain-scale elastic and plastic anisotropy of alpha-Ti with spherical nanoindentation and electron back-scattered diffraction

    DOE PAGES

    Weaver, Jordan S.; Priddy, Matthew W.; McDowell, David L.; ...

    2016-09-01

    Here, spherical nanoindentation combined with electron back-scattered diffraction has been employed to characterize the grain-scale elastic and plastic anisotropy of single crystal alpha-Ti of two different compositions (in two different titanium alloys). Data analyses protocols needed to reliably extract the desired properties of interest are extended and demonstrated in this paper. Specifically, the grain-scale mechanical response is extracted in the form of indentation stress-strain curves for commercially pure (CP-Ti) alpha-Ti and alloyed (Ti-64) titanium from measurements on polycrystalline samples. The results are compared with responses of single crystals and nanoindentation tests (hardness and modulus) from the literature, and the measuredmore » indentation moduli are validated using crystal-elastic finite element simulations. The results obtained in this study show that (i) it is possible to characterize reliably the elastic and plastic anisotropy of alpha-Ti (hcp) of varying alloying contents with spherical nanoindentation stress-strain curves, (ii) the indentation modulus of alpha-Ti-64 is 5–10% less than CP-Ti, and (iii) the indentation yield strength of alpha-Ti-64 is 50–80% higher than CP-Ti.« less

  17. On capturing the grain-scale elastic and plastic anisotropy of alpha-Ti with spherical nanoindentation and electron back-scattered diffraction

    SciTech Connect

    Weaver, Jordan S.; Priddy, Matthew W.; McDowell, David L.; Kalidindi, Surya R.

    2016-09-01

    Here, spherical nanoindentation combined with electron back-scattered diffraction has been employed to characterize the grain-scale elastic and plastic anisotropy of single crystal alpha-Ti of two different compositions (in two different titanium alloys). Data analyses protocols needed to reliably extract the desired properties of interest are extended and demonstrated in this paper. Specifically, the grain-scale mechanical response is extracted in the form of indentation stress-strain curves for commercially pure (CP-Ti) alpha-Ti and alloyed (Ti-64) titanium from measurements on polycrystalline samples. The results are compared with responses of single crystals and nanoindentation tests (hardness and modulus) from the literature, and the measured indentation moduli are validated using crystal-elastic finite element simulations. The results obtained in this study show that (i) it is possible to characterize reliably the elastic and plastic anisotropy of alpha-Ti (hcp) of varying alloying contents with spherical nanoindentation stress-strain curves, (ii) the indentation modulus of alpha-Ti-64 is 5–10% less than CP-Ti, and (iii) the indentation yield strength of alpha-Ti-64 is 50–80% higher than CP-Ti.

  18. Study of photon emission by electron capture during solar nuclei acceleration, 1: Temperature-dependent cross section for charge changing processes

    NASA Technical Reports Server (NTRS)

    Perez-Peraza, J.; Alvarez, M.; Laville, A.; Gallegos, A.

    1985-01-01

    The study of charge changing cross sections of fast ions colliding with matter provides the fundamental basis for the analysis of the charge states produced in such interactions. Given the high degree of complexity of the phenomena, there is no theoretical treatment able to give a comprehensive description. In fact, the involved processes are very dependent on the basic parameters of the projectile, such as velocity charge state, and atomic number, and on the target parameters, the physical state (molecular, atomic or ionized matter) and density. The target velocity, may have also incidence on the process, through the temperature of the traversed medium. In addition, multiple electron transfer in single collisions intrincates more the phenomena. Though, in simplified cases, such as protons moving through atomic hydrogen, considerable agreement has been obtained between theory and experiments However, in general the available theoretical approaches have only limited validity in restricted regions of the basic parameters. Since most measurements of charge changing cross sections are performed in atomic matter at ambient temperature, models are commonly based on the assumption of targets at rest, however at Astrophysical scales, temperature displays a wide range in atomic and ionized matter. Therefore, due to the lack of experimental data , an attempt is made here to quantify temperature dependent cross sections on basis to somewhat arbitrary, but physically reasonable assumptions.

  19. Capture Their Attention: Capturing Lessons Using Screen Capture Software

    ERIC Educational Resources Information Center

    Drumheller, Kristina; Lawler, Gregg

    2011-01-01

    When students miss classes for university activities such as athletic and academic events, they inevitably miss important class material. Students can get notes from their peers or visit professors to find out what they missed, but when students miss new and challenging material these steps are sometimes not enough. Screen capture and recording…

  20. Cryogenic Carbon Capture

    SciTech Connect

    2010-07-15

    IMPACCT Project: SES is developing a process to capture CO2 from the exhaust gas of coal-fired power plants by desublimation - the conversion of a gas to a solid. Capturing CO2 as a solid and delivering it as a liquid avoids the large energy cost of CO2 gas compression. SES’ capture technology facilitates the prudent use of available energy resources. Coal is our most abundant energy resource and is an excellent fuel for baseline power production. SES capture technology can capture 99% of the CO2 emissions in addition to a wide range of other pollutants more efficiently and at lower costs than existing capture technologies. SES’ capture technology can be readily added to our existing energy infrastructure.

  1. High-power electron beam tests of a liquid-lithium target and characterization study of (7)Li(p,n) near-threshold neutrons for accelerator-based boron neutron capture therapy.

    PubMed

    Halfon, S; Paul, M; Arenshtam, A; Berkovits, D; Cohen, D; Eliyahu, I; Kijel, D; Mardor, I; Silverman, I

    2014-06-01

    A compact Liquid-Lithium Target (LiLiT) was built and tested with a high-power electron gun at Soreq Nuclear Research Center (SNRC). The target is intended to demonstrate liquid-lithium target capabilities to constitute an accelerator-based intense neutron source for Boron Neutron Capture Therapy (BNCT) in hospitals. The lithium target will produce neutrons through the (7)Li(p,n)(7)Be reaction and it will overcome the major problem of removing the thermal power >5kW generated by high-intensity proton beams, necessary for sufficient therapeutic neutron flux. In preliminary experiments liquid lithium was flown through the target loop and generated a stable jet on the concave supporting wall. Electron beam irradiation demonstrated that the liquid-lithium target can dissipate electron power densities of more than 4kW/cm(2) and volumetric power density around 2MW/cm(3) at a lithium flow of ~4m/s, while maintaining stable temperature and vacuum conditions. These power densities correspond to a narrow (σ=~2mm) 1.91MeV, 3mA proton beam. A high-intensity proton beam irradiation (1.91-2.5MeV, 2mA) is being commissioned at the SARAF (Soreq Applied Research Accelerator Facility) superconducting linear accelerator. In order to determine the conditions of LiLiT proton irradiation for BNCT and to tailor the neutron energy spectrum, a characterization of near threshold (~1.91MeV) (7)Li(p,n) neutrons is in progress based on Monte-Carlo (MCNP and Geant4) simulation and on low-intensity experiments with solid LiF targets. In-phantom dosimetry measurements are performed using special designed dosimeters based on CR-39 track detectors.

  2. A first-principles density functional theory study of the electronic structural and thermodynamic properties of M2ZrO3 and M2CO3 (M=Na, K) and their capabilities for CO2 capture

    SciTech Connect

    Yuhua Duan

    2012-01-01

    Alkali metal zirconates could be used as solid sorbents for CO{sub 2} capture. The structural, electronic, and phonon properties of Na{sub 2}ZrO{sub 3}, K{sub 2}ZrO{sub 3}, Na{sub 2}CO{sub 3}, and K{sub 2}CO{sub 3} are investigated by combining the density functional theory with lattice phonon dynamics. The thermodynamics of CO{sub 2} absorption/desorption reactions of these two zirconates are analyzed. The calculated results show that their optimized structures are in a good agreement with experimental measurements. The calculated band gaps are 4.339 eV (indirect), 3.641 eV (direct), 3.935 eV (indirect), and 3.697 eV (direct) for Na{sub 2}ZrO{sub 3}, K{sub 2}ZrO{sub 3}, Na{sub 2}CO{sub 3}, and K{sub 2}CO{sub 3}, respectively.The calculated phonon dispersions and phonon density of states for M{sub 2}ZrO{sub 3} and M{sub 2}CO{sub 3} (M = K, Na, Li) revealed that from K to Na to Li, their frequency peaks are shifted to high frequencies due to the molecular weight decreased from K to Li. From the calculated reaction heats and relationships of free energy change versus temperatures and CO{sub 2} pressures of the M{sub 2}ZrO{sub 3} (M = K, Na, Li) reacting with CO{sub 2}, we found that the performance of Na{sub 2}ZrO{sub 3} capturing CO{sub 2} is similar to that of Li{sub 2}ZrO{sub 3} and is better than that of K{sub 2}ZrO{sub 3}. Therefore, Na{sub 2}ZrO{sub 3} and Li{sub 2}ZrO{sub 3} are good candidates of high temperature CO{sub 2} sorbents and could be used for post combustion CO{sub 2} capture technologies.

  3. Testing the Capture Magnet

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image of a model capture magnet was taken after an experiment in a Mars simulation chamber at the University of Aarhus, Denmark. It has some dust on it, but not as much as that on the Mars Exploration Rover Spirit's capture magnet. The capture and filter magnets on both Mars Exploration Rovers were delivered by the magnetic properties team at the Center for Planetary Science, Copenhagen, Denmark.

  4. Spatial capture-recapture

    USGS Publications Warehouse

    Royle, J. Andrew; Chandler, Richard B.; Sollmann, Rahel; Gardner, Beth

    2013-01-01

    Spatial Capture-Recapture provides a revolutionary extension of traditional capture-recapture methods for studying animal populations using data from live trapping, camera trapping, DNA sampling, acoustic sampling, and related field methods. This book is a conceptual and methodological synthesis of spatial capture-recapture modeling. As a comprehensive how-to manual, this reference contains detailed examples of a wide range of relevant spatial capture-recapture models for inference about population size and spatial and temporal variation in demographic parameters. Practicing field biologists studying animal populations will find this book to be a useful resource, as will graduate students and professionals in ecology, conservation biology, and fisheries and wildlife management.

  5. Electron capture and excitation in collisions of O[sup +]([sup 4][ital S],[sup 2][ital D],[sup 2][ital P]) ions with He atoms and He[sup +] ions with O atoms at energies below 10 keV

    SciTech Connect

    Kimura, M. Department of Physics, Rice University, Houston, Texas 77251 ); Gu, J.P.; Liebermann, H.P.; Li, Y.; Hirsch, G.; Buenker, R.J. ); Dalgarno, A. )

    1994-12-01

    Electron capture and excitation in O[sup +]([sup 4][ital S],[sup 2][ital D],[sup 2][ital P])+He collisions above 100 eV are studied theoretically by using a semiclassical molecular representation and electron capture in He[sup +]+O([sup 3][ital P]) collisions; excitation and deexcitation in O[sup +]([sup 4][ital S])+He[leftrightarrow]O[sup +]([sup 2][ital D])+He collisions at lower energies are studied by using a fully-quantum-mechanical molecular representation. At higher energies, nonadiabatic couplings are the driving forces that cause transitions. At collision energies below 10 eV, transitions are driven by spin-orbit couplings. At kilo-electron-volt energies, the contribution from metastable O[sup +]([sup 2][ital D],[sup 2][ital P]) ions to electron capture is much larger than that from the ground O[sup +]([sup 4][ital S]) ions. At energies below 1 eV, the cross section for electron capture in He[sup +]+O collisions is very small, with a magnitude of less than 10[sup [minus]20] cm[sup 2]. The cross sections for the excitation-deexcitation of metastable O[sup +] ions are larger, with values near 10[sup [minus]18] cm[sup 2].

  6. Jupiter: its captured satellites.

    PubMed

    Bailey, J M

    1971-08-27

    Because of the small size and irregular orbits of the seven outer satellites of Jupiter, it is often assumed that they were derived by capture. The conditions whereby Jupiter can capture satellites have therefore been examined. Relationships derived on the basis of the three-body problem for planets in elliptical orbits enable the dimensions of the capture orbits around Jupiter to be calculated. It is found that Jupiter may capture satellites through the inner Lagrangian point when at perihelion or at aphelion. Captures at perihelion should give rise to satellites in direct orbits of 11.48 x 10(6) kilometers and capture at aphelion to retrograde orbits of 21.7 x 10(6) kilometers. The correspondence with the seven outer satellites suggests that Jupiter VI, VIl, and X in direct orbits at 11.47, 11.74, and 11.85 x 10(6) kilometers were captured at Jupiter perihelion, whereas Jupiter VIII, IX, XI, and XII in retrograde orbits of 23.5, 23.7, 22.5, and 21.2 x 10(6) kilometers were captured when Jupiter was at aphelion. Examination of the precapture orbits indicates that the seven outer satellites were derived from the asteroid belt.

  7. Demonstrating carbon capture

    SciTech Connect

    Qader, A.; Hooper, B.; Stevens, G.

    2009-11-15

    Australia is at the forefront of advancing CCS technology. The CO2CRC's H3 (Post-combustion) and Mulgrave (pre-combustion) capture projects are outlined. The capture technologies for these 2 demonstration projects are described. 1 map., 2 photos.

  8. Precision Measurement of Nuclear Electron Capture Decay

    NASA Astrophysics Data System (ADS)

    Koltick, David; Liu, Shih-Chieh; Wang, Haoyu; Heim, Jordan; Nistor, Jonathan

    2017-01-01

    The method of accurately measuring the radioactive decay constant of a isotope by measuring the decay rate as a function of time requires that both the detector and environment be stable over time periods comparable to the life-time of the isotope. In addition statistical accuracy requires initial counting rates be high but limited by the dead time capability of the data collection system and the detectors double-event resolving time. A High Purity Germanium (HPGe) spectrometer, sensitive to radiation from 3-KeV to over 3-MeV, has been built to measure radioactive decay constants to a level of 10-5 10-6 at a location only 6 meters from the core of the High Flux Isotope Reactor located at Oak Ridge National Laboratory. Such accuracy requires understanding of, background, signal-processing algorithms, and both the double and triple event pile-up in the observed spectrum. The approach taken is to fit the collected energy spectrum with invariant shapes, independent of event rate. By fixing the source-detector geometry and environmental conditions, the invariant shapes are (1) ideal energy spectrum without pile-up and background, (2) the ideal double event pile-up spectrum, (3) the ideal triple event pile-up spectrum, and (4) the stable background spectrum. A method is presented that finds these ideal shapes using the collected data in situ. Taking this approach the HPGe detector photopeak shape in the absence of background and pile-up is presented showing associated structure over a range of 7 orders of magnitude.

  9. Application of single-drop microextraction and comparison with solid-phase microextraction and solid-phase extraction for the determination of alpha- and beta-endosulfan in water samples by gas chromatography-electron-capture detection.

    PubMed

    López-Blanco, M C; Blanco-Cid, S; Cancho-Grande, B; Simal-Gándara, J

    2003-01-17

    Water contamination due to the wide variety of pesticides used in agriculture practices is a global environmental pollution problem. The 98/83 European Directive requires the measurement of pesticides residues at a target concentration of 1.0 microg/l in surface water and 0.1 microg/l in drinking water. In order to reach the level of detection required, efficient extraction techniques are necessary. The application of a new extraction technique: single-drop microextraction (SDME), followed by gas chromatography with electron-capture detection, was assessed for determining alpha-endosulfan and beta-endosulfan in water samples. Experimental parameters which control the performance of SDME, such as selection of microextraction solvent and internal standard, optimization of organic drop volume, effects of sample stirring, temperature and salt addition, and sorption time profiles were studied. Once SDME was optimized, analytical parameters such as linearity, precision, detection and quantitation limits, plus matrix effects were evaluated. The SDME method was compared with solid-phase microextraction and solid-phase extraction with the aim of selecting the most appropriate method for a certain application.

  10. Analysis of pesticide residues in fresh peppermint, Mentha piperita L., using the quick easy cheap effective rugged and safe method (QuEChERS) followed by gas chromatography with electron capture and nitrogen phosphorus detection.

    PubMed

    Słowik-Borowiec, Magdalena; Szpyrka, Ewa; Walorczyk, Stanisław

    2012-09-01

    A new analytical method for the determination of 14 pesticide residues in fresh peppermint was developed based on the QuEChERS sample preparation technique followed by gas chromatography coupled to electron capture and nitrogen phosphorus detectors (GC/ECD/NPD). The validation study clearly demonstrated suitability of the method for its intended application. The overall recoveries of the pesticides from peppermint, at the three spiking levels of 0.01, 0.1 and 1.0 mg kg(-1), were 100% ± 10% with relative standard deviations of 6% ± 5% on average. The limit of quantification was 0.01 mg kg(-1) for all the pesticides. The expanded uncertainties were in the range between 7% and 30% (14% on average), which was distinctively less than a maximum default value of ±50%. Compared with our previous method, that entailed dichloromethane/acetone extraction and florisil column cleanup with collection of four fractions, the new method was more straightforward, less time and labour intensive as well as more sensitive, selective and accurate, simultaneously.

  11. [Determination of short-chain chlorinated paraffins in ambient air using high-volume sampling combined with high resolutimi gas chromatography-electron capture negative ion-low resolution mass spectrometry].

    PubMed

    Shi, Loimeng; Gao, Yuan; Hou, Xiaohong; Zhang, Haijun; Zhang, Yichi; Chen, Jiping

    2016-02-01

    An analytical method for quantifying short-chain chlorinated paraffins (SCCPs) in ambient air using high-volume sampling combined with high resolution gas chromatography-electron capture negative ion-low resolution mass spectrometry ( HRGC-ECNI-LRMS) was developed. An acidified silica gel column and a basic alumina column were used to optimize the cleanup procedures. The results showed a good linearity (R2>0. 99) between the total response factors and the degree of chlorination of SCCPs in the content range of 58. 1%-63. 3%. The limits of detection (S/N ≥3) and the limits of quantification (S/N ≥ 10) were 4. 2 and 12 µg, respectively. The method detection limit (MDL) for SCCPs was 0. 34 ng/m3 (n = 7). The recoveries of SCCPs in air samples were in the range of 81. 9% to 94. 2%. It is demonstrated that the method is suitable for the quantitative analysis of SCCPs in air samples.

  12. Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory : determination of organochlorine pesticides and polychlorinated biphenyls in bottom and suspended sediment by gas chromatography with electron-capture detection

    USGS Publications Warehouse

    Noriega, Mary C.; Wydoski, Duane S.; Foreman, William T.

    2004-01-01

    A method applicable for the determination of 19 organochlorine (OC) pesticides, including total toxaphene as a complex mixture, and 3 polychlorinated biphenyl (PCB) mixtures as Aroclor equivalents--Aroclor 1016/1242, 1254, and 1260--in soil, aquatic bottom sediment, and suspended sediment is described. Method performance data are presented. The solvent system is designed to extract simultaneously selected OC pesticides and PCBs from the same sample matrix. The compounds are extracted by conventional Soxhlet extraction with dichloromethane, followed by partial isolation using gel permeation chromatography (GPC) to remove inorganic sulfur and large naturally present molecules from the sediment extract. The aliquot of extract collected from the GPC for OCs (OC pesticides and PCBs) is split into two sample fractions by alumina/silica combined-column chromatography, followed by Florisil adsorption chromatography to remove interfering compounds in the second fraction. The OC fractions are analyzed by dual capillary-column gas chromatography with electron-capture detection (GC/ECD). This report is limited to the determination of selected OC pesticides and PCBs by GC/ECD using this method. Interim reporting levels (IRLs) have been set at 0.400 to 3.12 micrograms per kilogram for 18 individual OC pesticides, 200 micrograms per kilogram for toxaphene, and 4.04 to 4.68 micrograms per kilogram for the PCBs, based on a sample size of 25-gram equivalent dry weight. These reporting levels may change following additional determinations of method detection limits.

  13. Validation of QuEChERS method for the determination of 36 pesticide residues in fruits and vegetables from Ghana, using gas chromatography with electron capture and pulsed flame photometric detectors.

    PubMed

    Donkor, Augustine; Osei-Fosu, Paul; Nyarko, Stephen; Kingsford-Adaboh, Robert; Dubey, Brajesh; Asante, Isaac

    2015-01-01

    In this study, "Quick, Easy, Cheap, Effective, Rugged and Safe" 'QuEChERS' method was modified for the determination of 36 pesticides fortified at (0.01-1.0) mg kg(-1) in three vegetables and a fruit (lettuce, carrot, tomatoes and pineapples respectively) from Ghana. The method involved extraction with acetonitrile, phase separation with primary secondary amine and magnesium sulfate; the final injection solution was reconstituted in ethyl acetate. Organochlorine and synthetic pyrethroids residues were detected with electron capture detector whereas organophosphorus, pulsed flame photometric detector was used. The recoveries at different concentration levels (0.01, 0.1 and 1.0 mg kg(-1)) were in the range of 83% and 93% with relative standard deviation ranging from 2% to 10% (n = 5) and the coefficient of determination (R(2)) was greater than 0.99 for all the 36 pesticides. The method was successfully tested on 120 real samples from Accra markets and this proved to be useful for monitoring purposes particularly in laboratories that have no gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry.

  14. Determination of pesticide residues in coconut water by liquid-liquid extraction and gas chromatography with electron-capture plus thermionic specific detection and solid-phase extraction and high-performance liquid chromatography with ultraviolet detection.

    PubMed

    Brito, N M; Navickiene, S; Polese, L; Jardim, E F G; Abakerli, R B; Ribeiro, M L

    2002-05-31

    Two simple methods were developed to determine 11 pesticides in coconut water, a natural isotonic drink rich in salts, sugars and vitamins consumed by the people and athletes. The first procedure involves solid-phase extraction using Sep-Pak Vac C18 disposable cartridges with methanol for elution. Isocratic analysis was carried out by means of high-performance liquid chromatography with ultraviolet detection at 254 nm to analyse captan, chlorothalonil, carbendazim, lufenuron and diafenthiuron. The other procedure is based on liquid-liquid extraction with hexane-dichloromethane (1:1, v/v), followed by gas chromatographic analysis with effluent splitting to electron-capture detection for determination of endosulfan, captan, tetradifon and trichlorfon and thermionic specific detection for determination of malathion, parathion-methyl and monocrotophos. The methods were validated with fortified samples at different concentration levels (0.01-12.0 mg/kg). Average recoveries ranged from 75 to 104% with relative standard deviations between 1.4 and 11.5%. Each recovery analysis was repeated at least five times. Limits of detection ranged from 0.002 to 2.0 mg/kg. The analytical procedures were applied to 15 samples and no detectable amounts of the pesticides were found in any samples under the conditions described.

  15. Determination of chlorinated paraffins in sediments from the Firth of Clyde by gas chromatography with electron capture negative ionisation mass spectrometry and carbon skeleton analysis by gas chromatography with flame ionisation detection.

    PubMed

    Hussy, Ines; Webster, Lynda; Russell, Marie; Moffat, Colin

    2012-07-01

    Short chain chlorinated paraffins (SCCPs) are a group of persistent organic pollutants (POPs) of increasing concern, but are to date not widely investigated in the environment, largely due to the challenges involved in their quantification. Here, SCCPs were quantified in marine sediments from the Firth of Clyde, Scotland, by gas chromatography with electron capture negative ionisation mass spectrometry (GC-ECNIMS) and through carbon skeleton analysis by gas chromatography with flame ionisation detection (GC-FID), and the analytical challenges encountered are discussed. Concentrations in the sediments ranged from 0.4 to 69 μg kg(-1) when determined by GC-ECNIMS, and from 5.6 to 379 μg kg(-1) when determined by GC-FID. For 8 out of 11 samples, analysis by GC-FID gave higher results than analysis by GC-ECNIMS. Unexpected aspects of the analysis, such as the presence of high concentrations of longer chain chlorinated paraffins in the samples, are also presented.

  16. Rapid and simple determination of acrylamide in conventional cereal-based foods and potato chips through conversion to 3-[bis(trifluoroethanoyl)amino]-3-oxopropyl trifluoroacetate by gas chromatography coupled with electron capture and ion trap mass spectrometry detectors.

    PubMed

    Russo, Mario Vincenzo; Avino, Pasquale; Centola, Angela; Notardonato, Ivan; Cinelli, Giuseppe

    2014-03-01

    A new, simple, rapid and fully validated method based on gas chromatography coupled with Electron capture and ion trap mass spectrometry detectors (GC-ECD and GC-IT/MS) is presented for quantitative analysis of acrylamide contaminant in conventional cereal-based foods and potato chips. Before analysis acrylamide was efficiently derivatized with trifluoroacetic anhydride, the effects of temperature, reaction time and catalyst on the acylation reaction were evaluated. Chromatographic analysis was performed on SE-54 capillary column; good retention and peak response of the acrylamide derivative achieved under the optimal conditions. The analytical method has been fully validated by assessment of the following parameters: LODs and LOQs (1 and 25ngg(-1) by GC-ECD and 2 and 36ngg(-1) by GC-IT/MS, with a Relative Standard Deviations <4 and <6, respectively), linearity (R(2) above 0.981 in the range 0.005-50μgg(-1)) and extraction recovery (ranging between 91% and 99%, RSD below 4.0, for acrylamide spiked at levels of 1, 20, 50 and 100ngg(-1)). Furthermore, the method proposed requires no clean-up step of the acrylamide derivative to be performed prior to injection. The developed method has been successfully applied to determine acrylamide in different commercial cereal-based foods (including French fries and potato chips).

  17. Toward the understanding of chemical absorption processes for post-combustion capture of carbon dioxide: electronic and steric considerations from the kinetics of reactions of CO2(aq) with sterically hindered amines.

    PubMed

    Conway, William; Wang, Xiaoguang; Fernandes, Debra; Burns, Robert; Lawrance, Geoffrey; Puxty, Graeme; Maeder, Marcel

    2013-01-15

    The present study reports (a) the determination of both the kinetic rate constants and equilibrium constants for the reaction of CO(2)(aq) with sterically hindered amines and (b) an attempt to elucidate a fundamental chemical understanding of the relationship between the amine structure and chemical properties of the amine that are relevant for postcombustion capture of CO(2) (PCC) applications. The reactions of CO(2)(aq) with a series of linear and methyl substituted primary amines and alkanolamines have been investigated using stopped-flow spectrophotometry and (1)H NMR measurements at 25.0 °C. The specific mechanism of absorption for each of the amines, that is CO(2) hydration and/or carbamate formation, is examined and, based on the mechanism, the kinetic and equilibrium constants for the formation of carbamic acid/carbamates, including protonation constants of the carbamate, are reported for amines that follow this pathway. A Brønsted correlation relating the kinetic rate constants and equilibrium constants for the formation of carbamic acid/carbamates with the protonation constant of the amine is reported. Such a relationship facilitates an understanding of the effects of steric and electronic properties of the amine toward its reactivity with CO(2). Further, such relationships can be used to guide the design of new amines with improved properties relevant to PCC applications.

  18. Dynamic hollow fiber protected liquid phase microextraction and quantification using gas chromatography combined with electron capture detection of organochlorine pesticides in green tea leaves and ready-to-drink tea.

    PubMed

    Huang, Shih-Pin; Huang, Shang-Da

    2006-11-24

    The dynamic hollow fiber protected liquid phase microextraction (DHFP-LPME) technique was evaluated for the extraction of organochlorine pesticides (OCPs) in green tea leaves and ready-to-drink tea prior to gas chromatography combined-electron capture detection (GC-ECD) analysis. A conventional microsyringe with a 1.5 cm length of hollow fiber attached to its needle was connected to a syringe pump to perform the extraction. The microsyringe was used as both the microextraction device and the sample introduction device for GC-ECD analysis. In this work, the organochlorine pesticides were extracted and condensed to a volume of 3 microl of organic extracting solvent (1-octanol) confined within a 1.5 cm length of hollow fiber. The effects of extraction solvent, extraction time, sample agitation, plunger speed, and extraction temperature and salt concentration content on the extraction performance were also investigated. Good enrichments were achieved (34-297-fold) with this method, and good repeatabilities of extraction were obtained, with full name (RSDs) below 12.57%. Detection limits were much below 1 microg l(-1) for ready-to-drink tea and much below 1 microg g(-1) for green tea leaves.

  19. Validation of high-throughput measurement system with microwave-assisted extraction, fully automated sample preparation device, and gas chromatography-electron capture detector for determination of polychlorinated biphenyls in whale blubber.

    PubMed

    Fujita, Hiroyuki; Honda, Katsuhisa; Hamada, Noriaki; Yasunaga, Genta; Fujise, Yoshihiro

    2009-02-01

    Validation of a high-throughput measurement system with microwave-assisted extraction (MAE), fully automated sample preparation device (SPD), and gas chromatography-electron capture detector (GC-ECD) for the determination of polychlorinated biphenyls (PCBs) in minke whale blubber was performed. PCB congeners accounting for > 95% of the total PCBs burden in blubber were efficiently extracted with a small volume (20 mL) of n-hexane using MAE due to simultaneous saponification and extraction. Further, the crude extract obtained by MAE was rapidly purified and automatically substituted to a small volume (1 mL) of toluene using SPD without using concentrators. Furthermore, the concentration of PCBs in the purified and concentrated solution was accurately determined by GC-ECD. Moreover, the result of accuracy test using a certified material (SRM 1588b; Cod liver oil) showed good agreement with the NIST certified concentration values. In addition, the method quantification limit of total-PCB in whale blubbers was 41 ng g(-1). This new measurement system for PCBs takes only four hours. Consequently, it indicated this method is the most suitable for the monitoring and screening of PCBs in the conservation of the marine ecosystem and safe distribution of foods.

  20. IMPACCT: Carbon Capture Technology

    SciTech Connect

    2012-01-01

    IMPACCT Project: IMPACCT’s 15 projects seek to develop technologies for existing coal-fired power plants that will lower the cost of carbon capture. Short for “Innovative Materials and Processes for Advanced Carbon Capture Technologies,” the IMPACCT Project is geared toward minimizing the cost of removing carbon dioxide (CO2) from coal-fired power plant exhaust by developing materials and processes that have never before been considered for this application. Retrofitting coal-fired power plants to capture the CO2 they produce would enable greenhouse gas reductions without forcing these plants to close, shifting away from the inexpensive and abundant U.S. coal supply.

  1. Characterization of 4-hydroxy-2-nonenal-modified peptides by liquid chromatography-tandem mass spectrometry using data-dependent acquisition: neutral loss-driven MS3 versus neutral loss-driven electron capture dissociation.

    PubMed

    Rauniyar, Navin; Stevens, Stanley M; Prokai-Tatrai, Katalin; Prokai, Laszlo

    2009-01-15

    Reactive oxygen species generated during oxidative stress can lead to unfavorable cellular consequences, predominantly due to formation of 4-hydroxy-2-nonenal (HNE) during lipid peroxidation. Data-dependent and neutral loss (NL)-driven MS(3) acquisition have been reported for the identification of HNE adducts by mass spectrometry-based proteomics. However, the limitation associated with this method is the ambiguity in correct assignment of the HNE modification site when more than one candidate site is present as MS(3) is triggered on the neutral loss ion. We introduce NL-triggered electron capture dissociation tandem mass spectrometry (NL-ECD-MS/MS) for the characterization of HNE-modification sites in peptides. With this method performed using a hybrid linear ion trap-Fourier transform ion cyclotron resonance (FTICR) mass spectrometer, ECD in the FTICR unit of the instrument is initiated on precursor ions of peptides showing the neutral loss of 156 Da corresponding to an HNE molecule in the prescan acquired via collision-induced dissociation tandem mass spectrometry in the linear ion trap. In addition to manifold advantages associated with the ECD method of backbone fragmentation, including extensive sequence fragments, ECD tends to retain the HNE group during MS/MS of the precursor ion, facilitating the correct localization of the modification site. The results also suggest that predisposition of a peptide molecular ion to lose HNE during collision-induced dissociation-based fragmentation is independent of its charge state (2+ or 3+). In addition, we have demonstrated that coupling of solid-phase enrichment of HNE-modified peptides facilitates the detection of this posttranslational modification by NL-driven strategies for low-abundance proteins that are susceptible to substoichiometric carbonylation during oxidative stress.

  2. Hollow fiber liquid-liquid-liquid microextraction followed by solid-phase microextraction and in situ derivatization for the determination of chlorophenols by gas chromatography-electron capture detection.

    PubMed

    Saraji, Mohammad; Ghani, Milad

    2015-10-30

    A method based on the combination of hollow fiber liquid-liquid-liquid microextraction and solid-phase microextraction (SPME) followed by gas chromatography-electron capture detection was developed for the determination of chlorophenols in water and wastewater samples. Silica microstructures fabricated on the surface of a stainless steel wire were coated by an organic solvent and used as a SPME fiber. The analytes were extracted through a hollow fiber membrane containing n-decane from sample solution to an alkaline aqueous acceptor phase. They were then extracted and in situ derivatized on the SPME fiber using acetic anhydride. Experimental parameters such as the type of extraction solvent, acceptor phase NaOH concentration, donor phase HCl concentration, the amount of derivatizing reagent, salt concentration, stirring rate and extraction time were investigated and optimized. The precision of the method for the analytes at 0.02-30μgL(-1) concentration level ranged from 7.1 to 10.2% (as intra-day relative standard deviation) and 6.4 to 9.8% (as inter-day relative standard deviation). The linear dynamic ranges were in the interval of 5-500μgL(-1), 0.05-5μgL(-1), 0.02-1μgL(-1) and 0.001-0.5μgL(-1) for 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol, respectively. The enrichment factors were between 432 and 785. The limits of detection were in the range of 0.0004-1.2μgL(-1). Tap water, well water and wastewater samples were also analyzed to evaluate the method capability for real sample analysis.

  3. Quantification of multi-residue levels in peach juices, pulps and peels using dispersive liquid-liquid microextraction based on floating organic droplet coupled with gas chromatography-electron capture detection.

    PubMed

    Matsadiq, Guzalnur; Hu, Hai-Li; Ren, Hai-Bo; Zhou, Yi-Wen; Liu, Lu; Cheng, Jing

    2011-07-15

    In this paper, polychlorinated biphenyl (PCB), organochlorine pesticide (OCP) and pyrethroid pesticides in peach was investigated by comparing their residual level in peach juice, pulps and peels using dispersive liquid-liquid microextraction based on solidification of floating organic droplet (DLLME-SFO) combined with gas chromatography-electron capture detection (GC-ECD). Extraction conditions such as the type of extractant, volume of extractant and dispersant, salt effect and extraction time were optimized. For juice samples, the linearity of the method was obtained in the range of 10-2000 ng L(-1),with determination coefficients>0.99. The limits of detection (LOD) of the method were ranged between 2.8 and 18.5 ng L(-1). For pulp and peel samples, the developed method is linear over the range assayed, 1-20 μg kg(-1),with coefficients also >0.99. The relative recoveries of compounds analyzed from juice, pulp and peel samples were in the range of 73-106% with a relative standard deviation between 2.6 and 11.8%. The proposed method was applied to the simultaneous analysis of residues in real peach juice, pulp and peel samples. As a result, there were no target analytes found in peach juices and pulps while 3.3 μg kg(-1) cyhalothrin and 3.5 μg kg(-1) fenvalerate were found in peels. The experiment results revealed that the pyrethroid residues just deposited on the peels of the fruits, but did not move into pulps and juices.

  4. Simultaneous analysis of organochlorine pesticides and polychlorinated biphenyls in air samples by using accelerated solvent extraction (ASE) and solid-phase micro-extraction (SPME) coupled to gas chromatography dual electron capture detection.

    PubMed

    Mokbel, Haifaa; Al Dine, Enaam Jamal; Elmoll, Ahmad; Liaud, Céline; Millet, Maurice

    2016-04-01

    An analytical method associating accelerated solvent extraction (ASE) and solid-phase micro-extraction (SPME) in immersion mode combined with gas chromatography dual electrons capture detectors (SPME-GC-2ECD) has been developed and studied for the simultaneous determination of 19 organochlorine pesticides (OCPs) and 22 polychlorinated biphenyls (PCBs) in air samples (active and XAD-2 passive samplers). Samples were extracted with ASE with acetonitrile using the following conditions: temperature, 150 °C; pressure, 1500 psi; static, 15 min; cycles, 3; purge, 300 s; flush, 100 %. Extracts were reduced to 1 mL, and 500 μL of this extract, filled with deionised water, was subject to SPME extraction. Experimental results indicated that the proposed method attained the best extraction efficiency under the optimised conditions: extraction of PCB-OCP mixture using 100-μm PDMS fibre at 80 °C for 40 min with no addition of salt. The performance of the proposed ASE-SPME-GC-2ECD methodology with respect to linearity, limit of quantification and detection was evaluated by spiking of XAD-2 resin with target compounds. The regression coefficient (R (2)) of most compounds was found to be high of 0.99. limits of detection (LODs) are between 0.02 and 4.90 ng m(-3), and limits of quantification (LOQs) are between 0.05 and 9.12 ng m(-3) and between 0.2 and 49 ng/sampler and 0.52 and 91 ng/sampler, respectively, for XAD-2 passive samplers. Finally, a developed procedure was applied to determine selected PCBs and OCPs in the atmosphere.

  5. Low density solvent based dispersive liquid-liquid microextraction with gas chromatography-electron capture detection for the determination of cypermethrin in tissues and blood of cypermethrin treated rats.

    PubMed

    Mudiam, Mohana Krishna Reddy; Jain, Rajeev; Maurya, Shailendra Kumar; Khan, Haider A; Bandyopadhyay, Sanghamitra; Murthy, R C

    2012-05-01

    A simple and rapid method to determine the cypermethrin (CYP) insecticide in rat tissues (kidney, liver and brain) and blood has been developed for the first time using low density solvent-dispersive liquid-liquid microextraction (LDS-DLLME) followed by gas chromatography-electron capture detector (GC-ECD) analysis. Initially, tissue samples containing CYP were homoginized in acetone. Subsequently, homogenate was mixed with n-hexane (extraction solvent) and the mixture was rapidly injected into water. The upper n-hexane layer was collected in a separate microtube and injected into GC-ECD for analysis. Blood samples were diluted with ultrapure water and subjected to DLLME through similar procedure. Parameters such as type and volume of disperser and extraction solvent, salting out effect and extraction time, which can affect the extraction efficiency of DLLME, were optimized. Method was validated by investigating linearity, precision, recovery, limit of detection (LOD) and quantification (LOQ). LODs in tissue were in the range of 0.043-0.314 ng mg(-1) and for blood it was 8.6 ng mL(-1) with a signal to noise ratio of 3:1. LOQs in tissue were in the range of 0.143-1.03 ng mg(-1) and for blood it was 28.3 ng mL(-1) with a signal to noise ratio of 10:1. Mean recoveries of CYP at three different concentation levels in all the matrices were found to be in the range of 81.6-103.67%. The results show that, LDS-DLLME coupled with GC-ECD offers a simple, rapid and efficient technique for extraction and determination of CYP in rat tissues and blood samples, which in turn would be useful for toxicological studies of CYP.

  6. Muon capture in deuterium

    NASA Astrophysics Data System (ADS)

    Ricci, P.; Truhlík, E.; Mosconi, B.; Smejkal, J.

    2010-06-01

    Model dependence of the capture rates of the negative muon capture in deuterium is studied starting from potential models and the weak two-body meson exchange currents constructed in the tree approximation and also from an effective field theory. The tree one-boson exchange currents are derived from the hard pion chiral Lagrangians of the NΔπρωa system. If constructed in conjunction with the one-boson exchange potentials, the capture rates can be calculated consistently. On the other hand, the effective field theory currents, constructed within the heavy baryon chiral perturbation theory, contain a low energy constant d that cannot be extracted from data at the one-particle level nor determined from the first principles. Comparative analysis of the results for the doublet transition rate allows us to extract the constant d.

  7. Contingent Attentional Capture

    NASA Technical Reports Server (NTRS)

    Remington, Roger; Folk, Charles L.

    1994-01-01

    Four experiments address the degree of top-down selectivity in attention capture by feature singletons through manipulations of the spatial relationship and featural similarity of target and distractor singletons in a modified spatial cuing paradigm. Contrary to previous studies, all four experiments show that when searching for a singleton target, an irrelevant featural singleton captures attention only when defined by the same feature value as the target. Experiments 2, 3, and 4 provide a potential explanation for this empirical discrepancy by showing that irrelevant singletons can produce distraction effects that are independent of shifts of spatial attention. The results further support the notion that attentional capture is contingent on top-down attention control settings but indicates that such settings can be instantiated at the level of feature values.

  8. US Spacesuit Knowledge Capture

    NASA Technical Reports Server (NTRS)

    Chullen, Cinda; Thomas, Ken; McMann, Joe; Dolan, Kristi; Bitterly, Rose; Lewis, Cathleen

    2011-01-01

    The ability to learn from both the mistakes and successes of the past is vital to assuring success in the future. Due to the close physical interaction between spacesuit systems and human beings as users, spacesuit technology and usage lends itself rather uniquely to the benefits realized from the skillful organization of historical information; its dissemination; the collection and identification of artifacts; and the education of those in the field. The National Aeronautics and Space Administration (NASA), other organizations and individuals have been performing United States (U.S.) Spacesuit Knowledge Capture since the beginning of space exploration. Avenues used to capture the knowledge have included publication of reports; conference presentations; specialized seminars; and classes usually given by veterans in the field. More recently the effort has been more concentrated and formalized whereby a new avenue of spacesuit knowledge capture has been added to the archives in which videotaping occurs engaging both current and retired specialists in the field presenting technical scope specifically for education and preservation of knowledge. With video archiving, all these avenues of learning can now be brought to life with the real experts presenting their wealth of knowledge on screen for future learners to enjoy. Scope and topics of U.S. spacesuit knowledge capture have included lessons learned in spacesuit technology, experience from the Gemini, Apollo, Skylab and Shuttle programs, hardware certification, design, development and other program components, spacesuit evolution and experience, failure analysis and resolution, and aspects of program management. Concurrently, U.S. spacesuit knowledge capture activities have progressed to a level where NASA, the National Air and Space Museum (NASM), Hamilton Sundstrand (HS) and the spacesuit community are now working together to provide a comprehensive closed-looped spacesuit knowledge capture system which includes

  9. Adiabatic capture and debunching

    SciTech Connect

    Ng, K.Y.; /Fermilab

    2012-03-01

    In the study of beam preparation for the g-2 experiment, adiabatic debunching and adiabatic capture are revisited. The voltage programs for these adiabbatic processes are derived and their properties discussed. Comparison is made with some other form of adiabatic capture program. The muon g-2 experiment at Fermilab calls for intense proton bunches for the creation of muons. A booster batch of 84 bunches is injected into the Recycler Ring, where it is debunched and captured into 4 intense bunches with the 2.5-MHz rf. The experiment requires short bunches with total width less than 100 ns. The transport line from the Recycler to the muon-production target has a low momentum aperture of {approx} {+-}22 MeV. Thus each of the 4 intense proton bunches required to have an emittance less than {approx} 3.46 eVs. The incoming booster bunches have total emittance {approx} 8.4 eVs, or each one with an emittance {approx} 0.1 eVs. However, there is always emittance increase when the 84 booster bunches are debunched. There will be even larger emittance increase during adiabatic capture into the buckets of the 2.5-MHz rf. In addition, the incoming booster bunches may have emittances larger than 0.1 eVs. In this article, we will concentrate on the analysis of the adiabatic capture process with the intention of preserving the beam emittance as much as possible. At this moment, beam preparation experiment is being performed at the Main Injector. Since the Main Injector and the Recycler Ring have roughly the same lattice properties, we are referring to adiabatic capture in the Main Injector instead in our discussions.

  10. Neutron capture therapies

    SciTech Connect

    Yanch, Jacquelyn C.; Shefer, Ruth E.; Klinkowstein, Robert E.

    1999-01-01

    In one embodiment there is provided an application of the .sup.10 B(n,.alpha.).sup.7 Li nuclear reaction or other neutron capture reactions for the treatment of rheumatoid arthritis. This application, called Boron Neutron Capture Synovectomy (BNCS), requires substantially altered demands on neutron beam design than for instance treatment of deep seated tumors. Considerations for neutron beam design for the treatment of arthritic joints via BNCS are provided for, and comparisons with the design requirements for Boron Neutron Capture Therapy (BNCT) of tumors are made. In addition, exemplary moderator/reflector assemblies are provided which produce intense, high-quality neutron beams based on (p,n) accelerator-based reactions. In another embodiment there is provided the use of deuteron-based charged particle reactions to be used as sources for epithermal or thermal neutron beams for neutron capture therapies. Many d,n reactions (e.g. using deuterium, tritium or beryllium targets) are very prolific at relatively low deuteron energies.

  11. Neutron capture therapies

    SciTech Connect

    Yanch, J.C.; Shefer, R.E.; Klinkowstein, R.E.

    1999-11-02

    In one embodiment there is provided an application of the {sup 10}B(n,{alpha}){sup 7}Li nuclear reaction or other neutron capture reactions for the treatment of rheumatoid arthritis. This application, called Boron Neutron Capture Synovectomy (BNCS), requires substantially altered demands on neutron beam design than for instance treatment of deep seated tumors. Considerations for neutron beam design for the treatment of arthritic joints via BNCS are provided for, and comparisons with the design requirements for Boron Neutron Capture Therapy (BNCT) of tumors are made. In addition, exemplary moderator/reflector assemblies are provided which produce intense, high-quality neutron beams based on (p,n) accelerator-based reactions. In another embodiment there is provided the use of deuteron-based charged particle reactions to be used as sources for epithermal or thermal neutron beams for neutron capture therapies. Many d,n reactions (e.g. using deuterium, tritium or beryllium targets) are very prolific at relatively low deuteron energies.

  12. Attention Capture by Faces

    ERIC Educational Resources Information Center

    Langton, Stephen R. H.; Law, Anna S.; Burton, A. Mike; Schweinberger, Stefan R.

    2008-01-01

    We report three experiments that investigate whether faces are capable of capturing attention when in competition with other non-face objects. In Experiment 1a participants took longer to decide that an array of objects contained a butterfly target when a face appeared as one of the distracting items than when the face did not appear in the array.…

  13. Carbon Smackdown: Carbon Capture

    SciTech Connect

    Jeffrey Long

    2010-07-12

    In this July 9, 2010 Berkeley Lab summer lecture, Lab scientists Jeff Long of the Materials Sciences and Nancy Brown of the Environmental Energy Technologies Division discuss their efforts to fight climate change by capturing carbon from the flue gas of power plants, as well as directly from the air

  14. Capturing the Market

    ERIC Educational Resources Information Center

    Ramaswami, Rama

    2009-01-01

    Digital lecture capture and broadcast solutions have been around for only about 10 years, but are poised for healthy growth. Frost & Sullivan research analysts estimate that the market (which amounts to $25 million currently) will quadruple by 2013. It's still dominated by a few key players, however: Sonic Foundry holds a hefty 40 percent-plus…

  15. Carbon Smackdown: Carbon Capture

    ScienceCinema

    Jeffrey Long

    2016-07-12

    In this July 9, 2010 Berkeley Lab summer lecture, Lab scientists Jeff Long of the Materials Sciences and Nancy Brown of the Environmental Energy Technologies Division discuss their efforts to fight climate change by capturing carbon from the flue gas of power plants, as well as directly from the air

  16. Effectiveness of intact capture media

    SciTech Connect

    Tsou, P.; Aubert, J.; Brownlee, D.; Hrubesh, L.; Williams, J.; Albee, A.

    1989-01-01

    The possibility of capturing cosmic dust at hypervelocity has been demonstrated in the laboratory and in the unintended Solar Max spacecraft. This technology will enable a comet coma sample return mission and be important for the earth orbital cosmic dust collection mission, i.e., the Space Station Cosmic Dust Collection Facility. Since the only controllable factor in an intact capture of cosmic dust is the capturing medium, characterizing the effectiveness and properties of available capture media would be very important in the development of the technique for capturing hypervelocity cosmic dust intact. We have evaluated various capture underdense media for the relative effectiveness for intact capture. 2 refs., 2 figs.

  17. Advanced Telemetry Data Capturing

    SciTech Connect

    Paschke, G.A.

    2000-05-16

    This project developed a new generation or advanced data capturing process specifically designed for use in future telemetry test systems at the Kansas City Plant (KCP). Although similar data capturing processes are performed both commercially and at other DOE weapon facilities, the equipment used is not specifically designed to perform acceptance testing requirements unique to the KCP. Commercially available equipment, despite very high cost (up to $125,000), is deficient in reliability and long-term maintainability necessary in test systems at this facility. There are no commercial sources for some requirements, specifically Terminal Data Analyzer (TDA) data processing. Although other custom processes have been developed to satisfy these test requirements, these designs have become difficult to maintain and upgrade.

  18. Capturing the Future: Direct and Indirect Probes of Neutron Capture

    SciTech Connect

    Couture, Aaron Joseph

    2016-08-31

    This report documents aspects of direct and indirect neutron capture. The importance of neutron capture rates and methods to determine them are presented. The following conclusions are drawn: direct neutron capture measurements remain a backbone of experimental study; work is being done to take increased advantage of indirect methods for neutron capture; both instrumentation and facilities are making new measurements possible; more work is needed on the nuclear theory side to understand what is needed furthest from stability.

  19. Laser Capture Microdissection

    NASA Astrophysics Data System (ADS)

    Emmert-Buck, Michael R.; Bonner, Robert F.; Smith, Paul D.; Chuaqui, Rodrigo F.; Zhuang, Zhengping; Goldstein, Seth R.; Weiss, Rhonda A.; Liotta, Lance A.

    1996-11-01

    Laser capture microdissection (LCM) under direct microscopic visualization permits rapid one-step procurement of selected human cell populations from a section of complex, heterogeneous tissue. In this technique, a transparent thermoplastic film (ethylene vinyl acetate polymer) is applied to the surface of the tissue section on a standard glass histopathology slide; a carbon dioxide laser pulse then specifically activates the film above the cells of interest. Strong focal adhesion allows selective procurement of the targeted cells. Multiple examples of LCM transfer and tissue analysis, including polymerase chain reaction amplification of DNA and RNA, and enzyme recovery from transferred tissue are demonstrated.

  20. Capturing the Daylight Dividend

    SciTech Connect

    Peter Boyce; Claudia Hunter; Owen Howlett

    2006-04-30

    Capturing the Daylight Dividend conducted activities to build market demand for daylight as a means of improving indoor environmental quality, overcoming technological barriers to effective daylighting, and informing and assisting state and regional market transformation and resource acquisition program implementation efforts. The program clarified the benefits of daylight by examining whole building systems energy interactions between windows, lighting, heating, and air conditioning in daylit buildings, and daylighting's effect on the human circadian system and productivity. The project undertook work to advance photosensors, dimming systems, and ballasts, and provided technical training in specifying and operating daylighting controls in buildings. Future daylighting work is recommended in metric development, technology development, testing, training, education, and outreach.

  1. Multiple ionization and capture in relativistic heavy-ion atom collisions

    SciTech Connect

    Meyerhof, W.E.; Anholt, R.; Xu, Xiang-Yuan; Gould, H.; Feinberg, B.; McDonald, R.J.; Wegner, H.E.; Thieberger, P.

    1987-02-01

    We show that in relativistic heavy-ion collisions the independent electron model can be used to predict cross sections for multiple inner-shell ionization and capture in a single collision. Charge distributions of 82- to 200-MeV/amu Xe and 105- to 955-MeV/amu U ion beams emerging from thin solid targets were used to obtain single- and multiple-electron stripping and capture cross sections. The probabilities of stripping electrons from the K, L, or M shells were calculated using the semiclassical approximation and Dirac hydrogenic wavefunctions. For capture, a simplified model for electron capture was uded. The data generally agree with theory.

  2. Theory of inelastic multiphonon scattering and carrier capture by defects in semiconductors: Application to capture cross sections

    NASA Astrophysics Data System (ADS)

    Barmparis, Georgios D.; Puzyrev, Yevgeniy S.; Zhang, X.-G.; Pantelides, Sokrates T.

    2015-12-01

    Inelastic scattering and carrier capture by defects in semiconductors are the primary causes of hot-electron-mediated degradation of power devices, which holds up their commercial development. At the same time, carrier capture is a major issue in the performance of solar cells and light-emitting diodes. A theory of nonradiative (multiphonon) inelastic scattering by defects, however, is nonexistent, while the theory for carrier capture by defects has had a long and arduous history. Here we report the construction of a comprehensive theory of inelastic scattering by defects, with carrier capture being a special case. We distinguish between capture under thermal equilibrium conditions and capture under nonequilibrium conditions, e.g., in the presence of an electrical current or hot carriers where carriers undergo scattering by defects and are described by a mean free path. In the thermal-equilibrium case, capture is mediated by a nonadiabatic perturbation Hamiltonian, originally identified by Huang and Rhys and by Kubo, which is equal to linear electron-phonon coupling to first order. In the nonequilibrium case, we demonstrate that the primary capture mechanism is within the Born-Oppenheimer approximation (adiabatic transitions), with coupling to the defect potential inducing Franck-Condon electronic transitions, followed by multiphonon dissipation of the transition energy, while the nonadiabatic terms are of secondary importance (they scale with the inverse of the mass of typical atoms in the defect complex). We report first-principles density-functional-theory calculations of the capture cross section for a prototype defect using the projector-augmented wave, which allows us to employ all-electron wave functions. We adopt a Monte Carlo scheme to sample multiphonon configurations and obtain converged results. The theory and the results represent a foundation upon which to build engineering-level models for hot-electron degradation of power devices and the performance

  3. Asteroid capture using lunar flyby

    NASA Astrophysics Data System (ADS)

    Gong, Shengping; Li, Junfeng

    2015-09-01

    This paper focuses on the approach which enables us to capture an asteroid using the lunar flyby. Assume that the asteroid is able to enter the Earth-Moon system. The orbits of the asteroid before and after lunar flybys are investigated for different Jacobi constants in the restricted three body problem. The capture will happen when the post-flyby Jacobi constant reaches certain value due to the flyby. The capture regions of different pre-flyby initial Jacobi constants are numerically explored in the diagram that is represented by two defined angles. To give an intuitive description of the capture region, it is represented by the orbital elements of the asteroid. Based on this capture region, the asteroids that can be captured through lunar flybys are chosen from the asteroid database. Finally, the capture processes of selected asteroids are validated through the ephemerides model.

  4. Particle capture device

    DOEpatents

    Jayne, John T.; Worsnop, Douglas R.

    2016-02-23

    In example embodiments, particle collection efficiency in aerosol analyzers and other particle measuring instruments is improved by a particle capture device that employs multiple collisions to decrease momentum of particles until the particles are collected (e.g., vaporized or come to rest). The particle collection device includes an aperture through which a focused particle beam enters. A collection enclosure is coupled to the aperture and has one or more internal surfaces against which particles of the focused beam collide. One or more features are employed in the collection enclosure to promote particles to collide multiple times within the enclosure, and thereby be vaporized or come to rest, rather than escape through the aperture.

  5. Robust automated knowledge capture.

    SciTech Connect

    Stevens-Adams, Susan Marie; Abbott, Robert G.; Forsythe, James Chris; Trumbo, Michael Christopher Stefan; Haass, Michael Joseph; Hendrickson, Stacey M. Langfitt

    2011-10-01

    This report summarizes research conducted through the Sandia National Laboratories Robust Automated Knowledge Capture Laboratory Directed Research and Development project. The objective of this project was to advance scientific understanding of the influence of individual cognitive attributes on decision making. The project has developed a quantitative model known as RumRunner that has proven effective in predicting the propensity of an individual to shift strategies on the basis of task and experience related parameters. Three separate studies are described which have validated the basic RumRunner model. This work provides a basis for better understanding human decision making in high consequent national security applications, and in particular, the individual characteristics that underlie adaptive thinking.

  6. Capture-ejector satellites

    NASA Technical Reports Server (NTRS)

    Macconochie, I. O.; Eldred, C. H.; Martin, J. A.

    1983-01-01

    A satellite in the form of a large rotating rim which can be used to boost spacecraft from low-Earth orbit to higher orbits is described. The rim rotates in the plane of its orbit such that the lower portion of the rim is traveling at suborbital velocity, while the upper portion is travelling at greater than orbital velocity. Ascending spacecraft or payloads arrive at the lowest portion of the rim at suborbital velocities, where the payloads are released on a trajectory for higher orbits; descending payloads employ the reverse procedure. Electric thrusters placed on the rim maintain rim rotational speed and altitude. From the standpoint of currently known materials, the capture-ejector concept may be useful for relatively small velocity increments.

  7. Boron neutron capture therapy for cancer

    SciTech Connect

    Barth, R.E.; Soloway, A.H. ); Fairchild, R.G. State Univ. of New York, Stony Brook )

    1990-10-01

    Boron neutron capture therapy (BNCT) bring together two components that when kept separate have only minor effects on normal cells. The first component is a stable isotope of boron (boron 10) that can be concentrated in tumor cells. The second is a beam of low-energy neutrons that produces short-range radiation when absorbed, or captured, by the boron. The combination of these two conditions at the site of a tumor releases intense radiation that can destroy malignant tissues. BNCT is based on the nuclear reaction that occurs when boron 10 is irradiated with an absorbs neutrons. The neutrons that it takes up are called thermal, or slow, neutrons. They are of such low energy that they cause little tissue damage as compared with other forms of radiation such as protons, gamma rays and fast neutrons. When an atom of boron 10 captures a neutron, an unstable isotope, boron 11, forms. The boron 11 instantly fissions, yielding lithium 7 nuclei and energetic alpha particles. These heavy particles, which carry 2.79 million electron volts of energy, are a highly lethal form of radiation. If the treatment proceeds as intended, the destructive effects of the capture reaction would occur primarily in those cancer cells that have accumulated boron 10. Normal cells with low concentrations of boron would be spared.

  8. Lunar Sulfur Capture System

    NASA Technical Reports Server (NTRS)

    Berggren, Mark; Zubrin, Robert; Bostwick-White, Emily

    2013-01-01

    The Lunar Sulfur Capture System (LSCS) protects in situ resource utilization (ISRU) hardware from corrosion, and reduces contaminant levels in water condensed for electrolysis. The LSCS uses a lunar soil sorbent to trap over 98 percent of sulfur gases and about two-thirds of halide gases evolved during hydrogen reduction of lunar soils. LSCS soil sorbent is based on lunar minerals containing iron and calcium compounds that trap sulfur and halide gas contaminants in a fixed-bed reactor held at temperatures between 250 and 400 C, allowing moisture produced during reduction to pass through in vapor phase. Small amounts of Earth-based polishing sorbents consisting of zinc oxide and sodium aluminate are used to reduce contaminant concentrations to one ppm or less. The preferred LSCS configuration employs lunar soil beneficiation to boost concentrations of reactive sorbent minerals. Lunar soils contain sulfur in concentrations of about 0.1 percent, and halogen compounds including chlorine and fluorine in concentrations of about 0.01 percent. These contaminants are released as gases such as H2S, COS, CS2,HCl, and HF during thermal ISRU processing with hydrogen or other reducing gases. Removal of contaminant gases is required during ISRU processing to prevent hardware corrosion, electrolyzer damage, and catalyst poisoning. The use of Earth-supplied, single-use consumables to entirely remove contaminants at the levels existing in lunar soils would make many ISRU processes unattractive due to the large mass of consumables relative to the mass of oxygen produced. The LSCS concept of using a primary sorbent prepared from lunar soil was identified as a method by which the majority of contaminants could be removed from process gas streams, thereby substantially reducing the required mass of Earth-supplied consumables. The LSCS takes advantage of minerals containing iron and calcium compounds that are present in lunar soil to trap sulfur and halide gases in a fixedbed reactor

  9. Intact capture of hypervelocity projectiles

    NASA Technical Reports Server (NTRS)

    Tsou, P.

    1990-01-01

    The ability to capture projectiles intact at hypervelocities opens new applications in science and technology that would either not be possible or would be very costly by other means. This capability has been demonstrated in the laboratory for aluminum projectiles of 1.6 mm diameter, captured at 6 km/s, in one unmelted piece, and retaining up to 95% of the original mass. Furthermore, capture was accomplished passively using microcellular underdense polymer foam. Another advantage of capturing projectiles in an underdense medium is the ability of such a medium to preserve a record of the projectile's original velocity components of speed and direction. A survey of these experimental results is described in terms of a dozen parameters which characterize the amount of capture and the effect on the projectile due to different capture media.

  10. Intact capture of hypervelocity projectiles.

    PubMed

    Tsou, P

    1990-01-01

    The ability to capture projectiles intact at hypervelocities opens new applications in science and technology that would either not be possible or would be very costly by other means. This capability has been demonstrated in the laboratory for aluminum projectiles of 1.6 mm diameter, captured at 6 km/s, in one unmelted piece, and retaining up to 95% of the original mass. Furthermore, capture was accomplished passively using microcellular underdense polymer foam. Another advantage of capturing projectiles in an underdense medium is the ability of such a medium to preserve a record of the projectile's original velocity components of speed and direction. A survey of these experimental results is described in terms of a dozen parameters which characterize the amount of capture and the effect on the projectile due to different capture media.

  11. The Generic Data Capture Facility

    NASA Technical Reports Server (NTRS)

    Connell, Edward B.; Barnes, William P.; Stallings, William H.

    1987-01-01

    The Generic Data Capture Facility, which can provide data capture support for a variety of different types of spacecraft while enabling operations costs to be carefully controlled, is discussed. The data capture functions, data protection, isolation of users from data acquisition problems, data reconstruction, and quality and accounting are addressed. The TDM and packet data formats utilized by the system are described, and the development of generic facilities is considered.

  12. Inland capture fisheries

    PubMed Central

    Welcomme, Robin L.; Cowx, Ian G.; Coates, David; Béné, Christophe; Funge-Smith, Simon; Halls, Ashley; Lorenzen, Kai

    2010-01-01

    The reported annual yield from inland capture fisheries in 2008 was over 10 million tonnes, although real catches are probably considerably higher than this. Inland fisheries are extremely complex, and in many cases poorly understood. The numerous water bodies and small rivers are inhabited by a wide range of species and several types of fisher community with diversified livelihood strategies for whom inland fisheries are extremely important. Many drivers affect the fisheries, including internal fisheries management practices. There are also many drivers from outside the fishery that influence the state and functioning of the environment as well as the social and economic framework within which the fishery is pursued. The drivers affecting the various types of inland water, rivers, lakes, reservoirs and wetlands may differ, particularly with regard to ecosystem function. Many of these depend on land-use practices and demand for water which conflict with the sustainability of the fishery. Climate change is also exacerbating many of these factors. The future of inland fisheries varies between continents. In Asia and Africa the resources are very intensely exploited and there is probably little room for expansion; it is here that resources are most at risk. Inland fisheries are less heavily exploited in South and Central America, and in the North and South temperate zones inland fisheries are mostly oriented to recreation rather than food production. PMID:20713391

  13. Inland capture fisheries.

    PubMed

    Welcomme, Robin L; Cowx, Ian G; Coates, David; Béné, Christophe; Funge-Smith, Simon; Halls, Ashley; Lorenzen, Kai

    2010-09-27

    The reported annual yield from inland capture fisheries in 2008 was over 10 million tonnes, although real catches are probably considerably higher than this. Inland fisheries are extremely complex, and in many cases poorly understood. The numerous water bodies and small rivers are inhabited by a wide range of species and several types of fisher community with diversified livelihood strategies for whom inland fisheries are extremely important. Many drivers affect the fisheries, including internal fisheries management practices. There are also many drivers from outside the fishery that influence the state and functioning of the environment as well as the social and economic framework within which the fishery is pursued. The drivers affecting the various types of inland water, rivers, lakes, reservoirs and wetlands may differ, particularly with regard to ecosystem function. Many of these depend on land-use practices and demand for water which conflict with the sustainability of the fishery. Climate change is also exacerbating many of these factors. The future of inland fisheries varies between continents. In Asia and Africa the resources are very intensely exploited and there is probably little room for expansion; it is here that resources are most at risk. Inland fisheries are less heavily exploited in South and Central America, and in the North and South temperate zones inland fisheries are mostly oriented to recreation rather than food production.

  14. Captured by Aliens

    NASA Astrophysics Data System (ADS)

    Achenbach, Joel

    2000-03-01

    Captured by Aliens is a long and twisted voyage from science to the supernatural and back again. I hung out in Roswell, N.M., spent time with the Mars Society, met a guy who was figuring out the best way to build a spaceship to go to Alpha Centauri. I visited the set of the X-Files and talked to Mulder and Scully. One day over breakfast I was told by NASA administrator Dan Goldin, We live in a fog, man! He wants the big answers to the big questions. I spent a night in the base of a huge radio telescope in the boondocks of West Virginia, awaiting the signal from the aliens. I was hypnotized in a hotel room by someone who suspected that I'd been abducted by aliens and that this had triggered my interest in the topic. In the last months of his life, I talked to Carl Sagan, who believed that the galaxy riots with intelligent civilizations. He's my hero, for his steadfast adherence to the scientific method. What I found in all this is that the big question that needs immediate attention is not what's out THERE, but what's going on HERE, on Earth, and why we think the way we do, and how we came to be here in the first place.

  15. Capture-recapture methodology

    USGS Publications Warehouse

    Gould, William R.; Kendall, William L.

    2013-01-01

    Capture-recapture methods were initially developed to estimate human population abundance, but since that time have seen widespread use for fish and wildlife populations to estimate and model various parameters of population, metapopulation, and disease dynamics. Repeated sampling of marked animals provides information for estimating abundance and tracking the fate of individuals in the face of imperfect detection. Mark types have evolved from clipping or tagging to use of noninvasive methods such as photography of natural markings and DNA collection from feces. Survival estimation has been emphasized more recently as have transition probabilities between life history states and/or geographical locations, even where some states are unobservable or uncertain. Sophisticated software has been developed to handle highly parameterized models, including environmental and individual covariates, to conduct model selection, and to employ various estimation approaches such as maximum likelihood and Bayesian approaches. With these user-friendly tools, complex statistical models for studying population dynamics have been made available to ecologists. The future will include a continuing trend toward integrating data types, both for tagged and untagged individuals, to produce more precise and robust population models.

  16. Vehicle capture system

    NASA Astrophysics Data System (ADS)

    Tacke, Kenneth L.

    1998-12-01

    Primex Aerospace Company, under contract with the U.S. Army Armament Research Development & Engineering Center (ARDEC), has developed a portable vehicle capture system for use at vehicle checkpoints. Currently when a vehicle does not stop at a checkpoint, there are three possible reactions: let the vehicle go unchallenged, pursue the vehicle or stop the vehicle with lethal force. This system provides a non-lethal alternative that will stop and contain the vehicle. The system is completely portable with the heaviest component weighing less than 120 pounds. It can be installed with no external electrical power or permanent anchors required. In its standby mode, the system does not impede normal traffic, but on command erects a barrier in less than 1.5 seconds. System tests have been conducted using 5,100 and 8.400 pound vehicles, traveling at speeds up to 45 mph. The system is designed to minimize vehicle damage and occupant injury, typically resulting in deceleration forces of less than 2.5 gs on the vehicle. According to the drivers involved in tests at 45 mph, the stopping forces feel similar to a panic stop with the vehicle brakes locked. The system is completely reusable and be rapidly reset.

  17. The physics of intact capture

    NASA Technical Reports Server (NTRS)

    Tsou, Peter; Griffiths, D. J.; Albee, A. L.

    1994-01-01

    The ability to capture projectiles intact at hypervelocities in underdense media open a new area of study in physics. Underdense material behaves markedly different than solid, liquid, or gas upon hypervelocity impact. This new phenomenon enables applications in science that would either not be possible or would be very costly by other means. This phenomenon has been fully demonstrated in the laboratory and validated in space. Even more interesting is the fact that this hypervelocity intact capture was accomplished passively. A better understanding of the physics of intact capture will lead to improvements in intact capture. A collection of physical observations of this phenomenon is presented here.

  18. Resource capture by single leaves

    SciTech Connect

    Long, S.P.

    1992-05-01

    Leaves show a variety of strategies for maximizing CO{sub 2} and light capture. These are more meaningfully explained if they are considered in the context of maximizing capture relative to the utilization of water, nutrients and carbohydrates reserves. There is considerable variation between crops in their efficiency of CO{sub 2} and light capture at the leaf level. Understanding of these mechanisms indicate some ways in which efficiency of resource capture could be level cannot be meaningfully considered without simultaneous understanding of implications at the canopy level. 36 refs., 5 figs., 1 tab.

  19. Control of DNA Capture by Nanofluidic Transistors

    PubMed Central

    Paik, Kee-Hyun; Liu, Yang; Tabard-Cossa, Vincent; Waugh, Matthew J.; Huber, David E.; Provine, J; Howe, Roger T.; Dutton, Robert W.; Davis, Ronald W.

    2012-01-01

    We report the use of an array of electrically gated ~200 nm solid-state pores as nanofluidic transistors to manipulate the capture and passage of DNA. The devices are capable of reversibly altering the rate of DNA capture by over three orders of magnitude using sub-1V biasing of a gate electrode. This efficient gating originates from the counter-balance of electrophoresis and electroosmosis, as revealed by quantitative numerical simulations. Such a reversible electronically-tuneable biomolecular switch may be used to manipulate nucleic acid delivery in a fluidic circuit, and its development is an important first step towards active control of DNA motion through solid-state nanopores for sensing applications. PMID:22762282

  20. Embracing Electronic Publishing.

    ERIC Educational Resources Information Center

    Wills, Gordon

    1996-01-01

    Electronic publishing is the grandest revolution in the capture and dissemination of academic and professional knowledge since Caxton developed the printing press. This article examines electronic publishing, describes different electronic publishing scenarios (authors' cooperative, consolidator/retailer/agent oligopsony, publisher oligopoly), and…

  1. The solar neutrino capture cross section for 81Br

    NASA Astrophysics Data System (ADS)

    Haxton, W. C.

    1981-09-01

    The solar neutrino capture rate for the reaction 81Br + νe --> 81Kr + e- is calculated for the standard solar and weak interaction models. The results show that the capture cross section is dominated by the lowest Gamow-Teller transition to the metastable 1/2- (0.190 MeV) state in 81Kr. As the inverse electron capture rate for this transition has been measured recently, one can then argue that the cross section is well determined experimentally. Thus uncertainties in nuclear physics should not be an obstacle to the recently proposed 81Br radiochemical measurement of the 7Be solar neutrino flux. Present address.

  2. Capture probabilities for secondary resonances

    NASA Technical Reports Server (NTRS)

    Malhotra, Renu

    1990-01-01

    A perturbed pendulum model is used to analyze secondary resonances, and it is shown that a self-similarity between secondary and primary resonances exists. Henrard's (1982) theory is used to obtain formulas for the capture probability into secondary resonances. The tidal evolution of Miranda and Umbriel is considered as an example, and significant probabilities of capture into secondary resonances are found.

  3. Carbon Capture: A Technology Assessment

    DTIC Science & Technology

    2013-10-21

    monoethanolamine (MEA) and ammonia ; pre- combustion capture (also via chemical solvents) from the synthesis gas produced in an integrated coal gasification...71 D. Heaven et al., “ Synthesis Gas Purification in Gasification to Ammonia /Urea Plants,” Gasification Technologies...32 Ammonia -Based Capture Processes

  4. Intact capture of cosmic dust

    NASA Technical Reports Server (NTRS)

    Tsou, P.

    1991-01-01

    The focus of this development effort is to capture dust particles at hypervelocities intact and unmelted in order to preserve volatile organics. At the same time, the capture process must minimize any organic elemental or compound contamination to prevent any compromise of exobiological analyses. Inorganic silicate aerogel has been developed as a successful capture medium to satisfy both requirements of intact capture and minimal organic contamination. Up to 6 km/s, silicate projectiles from a few microns up to 100 microns have been captured intact without any melting and with minimal loss of mass. Carbon in silicate aerogel can be reduced to less than 1 part in 1000 and hydrogen 3 parts in 1000 when baked in air. Under controlled inert gas environments, additional hydrocarbon reduction can be achieved.

  5. Iodine neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Ahmed, Kazi Fariduddin

    A new technique, Iodine Neutron Capture Therapy (INCT) is proposed to treat hyperthyroidism in people. Present thyroid therapies, surgical removal and 131I treatment, result in hypothyroidism and, for 131I, involve protracted treatment times and excessive whole-body radiation doses. The new technique involves using a low energy neutron beam to convert a fraction of the natural iodine stored in the thyroid to radioactive 128I, which has a 24-minute half-life and decays by emitting 2.12-MeV beta particles. The beta particles are absorbed in and damage some thyroid tissue cells and consequently reduce the production and release of thyroid hormones to the blood stream. Treatment times and whole-body radiation doses are thus reduced substantially. This dissertation addresses the first of the several steps needed to obtain medical profession acceptance and regulatory approval to implement this therapy. As with other such programs, initial feasibility is established by performing experiments on suitable small mammals. Laboratory rats were used and their thyroids were exposed to the beta particles coming from small encapsulated amounts of 128I. Masses of 89.0 mg reagent-grade elemental iodine crystals have been activated in the ISU AGN-201 reactor to provide 0.033 mBq of 128I. This activity delivers 0.2 Gy to the thyroid gland of 300-g male rats having fresh thyroid tissue masses of ˜20 mg. Larger iodine masses are used to provide greater doses. The activated iodine is encapsulated to form a thin (0.16 cm 2/mg) patch that is then applied directly to the surgically exposed thyroid of an anesthetized rat. Direct neutron irradiation of a rat's thyroid was not possible due to its small size. Direct in-vivo exposure of the thyroid of the rat to the emitted radiation from 128I is allowed to continue for 2.5 hours (6 half-lives). Pre- and post-exposure blood samples are taken to quantify thyroid hormone levels. The serum T4 concentration is measured by radioimmunoassay at

  6. Carbon Capture and Storage

    SciTech Connect

    Friedmann, S

    2007-10-03

    Carbon capture and sequestration (CCS) is the long-term isolation of carbon dioxide from the atmosphere through physical, chemical, biological, or engineered processes. This includes a range of approaches including soil carbon sequestration (e.g., through no-till farming), terrestrial biomass sequestration (e.g., through planting forests), direct ocean injection of CO{sub 2} either onto the deep seafloor or into the intermediate depths, injection into deep geological formations, or even direct conversion of CO{sub 2} to carbonate minerals. Some of these approaches are considered geoengineering (see the appropriate chapter herein). All are considered in the 2005 special report by the Intergovernmental Panel on Climate Change (IPCC 2005). Of the range of options available, geological carbon sequestration (GCS) appears to be the most actionable and economic option for major greenhouse gas reduction in the next 10-30 years. The basis for this interest includes several factors: (1) The potential capacities are large based on initial estimates. Formal estimates for global storage potential vary substantially, but are likely to be between 800 and 3300 Gt of C (3000 and 10,000 Gt of CO{sub 2}), with significant capacity located reasonably near large point sources of the CO{sub 2}. (2) GCS can begin operations with demonstrated technology. Carbon dioxide has been separated from large point sources for nearly 100 years, and has been injected underground for over 30 years (below). (3) Testing of GCS at intermediate scale is feasible. In the US, Canada, and many industrial countries, large CO{sub 2} sources like power plants and refineries lie near prospective storage sites. These plants could be retrofit today and injection begun (while bearing in mind scientific uncertainties and unknowns). Indeed, some have, and three projects described here provide a great deal of information on the operational needs and field implementation of CCS. Part of this interest comes from several

  7. River Capture in Disequilibrium Landscapes

    NASA Astrophysics Data System (ADS)

    McCoy, S. W.; Perron, J.; Willett, S.; Goren, L.

    2013-12-01

    The process of river piracy or river capture has long drawn interest as a potential mechanism by which drainage basins large and small evolve towards an equilibrium state. River capture transfers both drainage area and drainage lines from one river basin to another, which can cause large, abrupt shifts in network topology, drainage divide positions, and river incision rates. Despite numerous case studies in which river capture has been proposed to have occurred, there is no general, mechanistic framework for understanding the controls on river capture, nor are there quantitative criteria for determining if capture has occurred. Here we use new metrics of landscape disequilibrium to first identify landscapes in which drainage reorganization is occurring. These metrics are based on a balance between an integral of the contributing drainage area and elevation. In an analysis of rivers in the Eastern United States we find that many rivers are in a state of disequilibrium and are experiencing recent or ongoing area exchange between basins. In these disequilibrium basins we find widespread evidence for network rearrangement via river capture at multiple scales. We then conduct numerical experiments with a 2-D landscape evolution model to explore the conditions in which area exchange among drainage basins is likely to occur as discrete capture events as opposed to continuous divide migration. These experiments indicate that: (1) capture activity increases with the degree of disequilibrium induced by persistent spatial gradients in tectonic forcing or by temporal changes in climate or tectonic forcing; (2) capture activity is strongly controlled by the initial planform drainage network geometry; and (3) capture activity scales with the fluvial incision rate constant in the river power erosion law.

  8. Neutron capture reactions at DANCE

    NASA Astrophysics Data System (ADS)

    Bredeweg, T. A.

    2008-05-01

    The Detector for Advanced Neutron Capture Experiments (DANCE) is a 4π BaF2 array consisting of 160 active detector elements. The primary purpose of the array is to perform neutron capture cross section measurements on small (>~100 μg) and/or radioactive (<~100 mCi) species. The measurements made possible with this array will be useful in answering outstanding questions in the areas of national security, threat reduction, nuclear astrophysics, advanced reactor design and accelerator transmutation of waste. Since the commissioning of DANCE we have performed neutron capture cross section measurements on a wide array of medium to heavy mass nuclides. Measurements to date include neutron capture cross sections on 241,243Am, neutron capture and neutron-induced fission cross sections and capture-to-fission ratio (α = σγ/σf) for 235U using a new fission-tagging detector as well as neutron capture cross sections for several astrophysics branch-point nuclei. Results from several of these measurements will be presented along with a discussion of additional physics information that can be extracted from the DANCE data.

  9. Capture zones for simple aquifers

    USGS Publications Warehouse

    McElwee, Carl D.

    1991-01-01

    Capture zones showing the area influenced by a well within a certain time are useful for both aquifer protection and cleanup. If hydrodynamic dispersion is neglected, a deterministic curve defines the capture zone. Analytical expressions for the capture zones can be derived for simple aquifers. However, the capture zone equations are transcendental and cannot be explicitly solved for the coordinates of the capture zone boundary. Fortunately, an iterative scheme allows the solution to proceed quickly and efficiently even on a modest personal computer. Three forms of the analytical solution must be used in an iterative scheme to cover the entire region of interest, after the extreme values of the x coordinate are determined by an iterative solution. The resulting solution is a discrete one, and usually 100-1000 intervals along the x-axis are necessary for a smooth definition of the capture zone. The presented program is written in FORTRAN and has been used in a variety of computing environments. No graphics capability is included with the program; it is assumed the user has access to a commercial package. The superposition of capture zones for multiple wells is expected to be satisfactory if the spacing is not too close. Because this program deals with simple aquifers, the results rarely will be the final word in a real application.

  10. Neutron capture reactions at DANCE

    SciTech Connect

    Bredeweg, T. A.

    2008-05-12

    The Detector for Advanced Neutron Capture Experiments (DANCE) is a 4{pi} BaF{sub 2} array consisting of 160 active detector elements. The primary purpose of the array is to perform neutron capture cross section measurements on small (> or approx.100 {mu}g) and/or radioactive (< or approx. 100 mCi) species. The measurements made possible with this array will be useful in answering outstanding questions in the areas of national security, threat reduction, nuclear astrophysics, advanced reactor design and accelerator transmutation of waste. Since the commissioning of DANCE we have performed neutron capture cross section measurements on a wide array of medium to heavy mass nuclides. Measurements to date include neutron capture cross sections on {sup 241,243}Am, neutron capture and neutron-induced fission cross sections and capture-to-fission ratio ({alpha} = {sigma}{sub {gamma}}/{sigma}{sub f}) for {sup 235}U using a new fission-tagging detector as well as neutron capture cross sections for several astrophysics branch-point nuclei. Results from several of these measurements will be presented along with a discussion of additional physics information that can be extracted from the DANCE data.

  11. Intact capture of hypervelocity particles

    NASA Technical Reports Server (NTRS)

    Tsou, P.; Brownlee, D. E.; Albee, A. L.

    1986-01-01

    Knowledge of the phase, structure, and crystallography of cosmic particles, as well as their elemental and isotopic compositions, would be very valuable information toward understanding the nature of our solar system. This information can be obtained from the intact capture of large mineral grains of cosmic particles from hypervelocity impacts. Hypervelocity experiments of intact capture in underdense media have indicated realistic potential in this endeaver. The recovery of the thermal blankets and louvers from the Solar Max spacecraft have independently verified this potential in the unintended capture of cosmic materials from hypervelocity impacts. Passive underdense media will permit relatively simple and inexpensive missions to capture cosmic particles intact, either by going to a planetary body or by waiting for the particles to come to the Shuttle or the Space Station. Experiments to explore the potential of using various underdense media for an intact comet sample capture up to 6.7 km/s were performed at NASA Ames Research Center Vertical Gun Range. Explorative hypervelocity experiments up to 7.9 km/s were also made at the Ernst Mach Institute. These experiments have proven that capturing intact particles at hypervelocity impacts is definitely possible. Further research is being conducted to achieve higher capture ratios at even higher hypervelocities for even smaller projectiles.

  12. Intact capture of hypervelocity particles

    NASA Astrophysics Data System (ADS)

    Tsou, P.; Brownlee, D. E.; Albee, A. L.

    Knowledge of the phase, structure, and crystallography of cosmic particles, as well as their elemental and isotopic compositions, would be very valuable information toward understanding the nature of our solar system. This information can be obtained from the intact capture of large mineral grains of cosmic particles from hypervelocity impacts. Hypervelocity experiments of intact capture in underdense media have indicated realistic potential in this endeaver. The recovery of the thermal blankets and louvers from the Solar Max spacecraft have independently verified this potential in the unintended capture of cosmic materials from hypervelocity impacts. Passive underdense media will permit relatively simple and inexpensive missions to capture cosmic particles intact, either by going to a planetary body or by waiting for the particles to come to the Shuttle or the Space Station. Experiments to explore the potential of using various underdense media for an intact comet sample capture up to 6.7 km/s were performed at NASA Ames Research Center Vertical Gun Range. Explorative hypervelocity experiments up to 7.9 km/s were also made at the Ernst Mach Institute. These experiments have proven that capturing intact particles at hypervelocity impacts is definitely possible. Further research is being conducted to achieve higher capture ratios at even higher hypervelocities for even smaller projectiles.

  13. Capture methods for Musk Ducks

    USGS Publications Warehouse

    McCracken, K.G.; Hemmings, J.; Paton, D.C.; Afton, A.D.

    2003-01-01

    Musk Ducks Biziura lobata are endemic to wetlands, river systems and coastal oceanic waters of temperate Australia. Individuals of this species are difficult to capture because of their excellent swimming and diving abilities and frequent use of deep-water habitats. Night-lighting, baited clover-leaf traps and walk-in-nest-traps were used to capture Musk Ducks at Murray Lagoon, Cape Gantheaume Conservation Park, Kangaroo Island, South Australia. These techniques should be useful for capturing Musk Ducks at other locations in Australia.

  14. Provenance Datasets Highlighting Capture Disparities

    DTIC Science & Technology

    2014-01-01

    the Web pages of the universities and institutes.1 Notes are made and links pasted in a variety of formats. Files are saved on a shared drive. When...institutions/ 3. Capture Methods There are several capture methods that are available for use [4]: • Manual capture. • Scraping of logs or...the high-level user desktop. Save links App: Word, SharePoint User: Alice Web Data Web Data Web Data Web Data Web Data Web Data Notes.txt Create

  15. ISS Update: Capturing a Dragon

    NASA Video Gallery

    NASA Public Affairs Officer Josh Byerly talks with space station training instructors Jeff Tuxhorn and Graeme Newman, who trained the space station crews on how to capture SpaceX’s Dragon spacecr...

  16. Radiative capture reactions in astrophysics

    DOE PAGES

    Brune, Carl R.; Davids, Barry

    2015-08-07

    Here, the radiative capture reactions of greatest importance in nuclear astrophysics are identified and placed in their stellar contexts. Recent experimental efforts to estimate their thermally averaged rates are surveyed.

  17. ISS Update: Capturing a Dragon

    NASA Video Gallery

    NASA Public Affairs Officer Josh Byerly talks with Melanie Miller, Robotics Officer, about the capture of the SpaceX Dragon commercial cargo craft by the Expedition 33 crew of the International Spa...

  18. Muon Capture on ^3H

    NASA Astrophysics Data System (ADS)

    Golak, Jacek; Skibiński, Roman; Witała, Henryk; Topolnicki, Kacper; Kamada, Hiroyuki; Nogga, Andreas; Marcucci, Laura E.

    2017-01-01

    The μ ^- + ^3H → ν _μ + n + n + n capture reaction is studied under full inclusion of final-state interactions with the AV18 nucleon-nucleon potential and the Urbana IX three-nucleon force. We employ the single nucleon weak current operator comprising the dominant relativistic corrections to obtain first estimates of the total capture rates based on realistic forces. Our results are compared with older theoretical predictions.

  19. Toward transformational carbon capture systems

    SciTech Connect

    Miller, David C.; Litynski, John T.; Brickett, Lynn A.; Morreale, Bryan D.

    2015-10-28

    This paper will briefly review the history and current state of Carbon Capture and Storage (CCS) research and development and describe the technical barriers to carbon capture. it will argue forcefully for a new approach to R&D, which leverages both simulation and physical systems at the laboratory and pilot scales to more rapidly move the best technoogies forward, prune less advantageous approaches, and simultaneously develop materials and processes.

  20. Gold nanoparticle capture within protein crystal scaffolds

    NASA Astrophysics Data System (ADS)

    Kowalski, Ann E.; Huber, Thaddaus R.; Ni, Thomas W.; Hartje, Luke F.; Appel, Karina L.; Yost, Jarad W.; Ackerson, Christopher J.; Snow, Christopher D.

    2016-06-01

    DNA assemblies have been used to organize inorganic nanoparticles into 3D arrays, with emergent properties arising as a result of nanoparticle spacing and geometry. We report here the use of engineered protein crystals as an alternative approach to biologically mediated assembly of inorganic nanoparticles. The protein crystal's 13 nm diameter pores result in an 80% solvent content and display hexahistidine sequences on their interior. The hexahistidine sequence captures Au25(glutathione)~17 (nitrilotriacetic acid)~1 nanoclusters throughout a chemically crosslinked crystal via the coordination of Ni(ii) to both the cluster and the protein. Nanoparticle loading was validated by confocal microscopy and elemental analysis. The nanoparticles may be released from the crystal by exposure to EDTA, which chelates the Ni(ii) and breaks the specific protein/nanoparticle interaction. The integrity of the protein crystals after crosslinking and nanoparticle capture was confirmed by single crystal X-ray crystallography.DNA assemblies have been used to organize inorganic nanoparticles into 3D arrays, with emergent properties arising as a result of nanoparticle spacing and geometry. We report here the use of engineered protein crystals as an alternative approach to biologically mediated assembly of inorganic nanoparticles. The protein crystal's 13 nm diameter pores result in an 80% solvent content and display hexahistidine sequences on their interior. The hexahistidine sequence captures Au25(glutathione)~17 (nitrilotriacetic acid)~1 nanoclusters throughout a chemically crosslinked crystal via the coordination of Ni(ii) to both the cluster and the protein. Nanoparticle loading was validated by confocal microscopy and elemental analysis. The nanoparticles may be released from the crystal by exposure to EDTA, which chelates the Ni(ii) and breaks the specific protein/nanoparticle interaction. The integrity of the protein crystals after crosslinking and nanoparticle capture was

  1. Shutterless ion mobility spectrometer with fast pulsed electron source

    NASA Astrophysics Data System (ADS)

    Bunert, E.; Heptner, A.; Reinecke, T.; Kirk, A. T.; Zimmermann, S.

    2017-02-01

    Ion mobility spectrometers (IMS) are devices for fast and very sensitive trace gas analysis. The measuring principle is based on an initial ionization process of the target analyte. Most IMS employ radioactive electron sources, such as 63Ni or 3H. These radioactive materials have the disadvantage of legal restrictions and the electron emission has a predetermined intensity and cannot be controlled or disabled. In this work, we replaced the 3H source of our IMS with 100 mm drift tube length with our nonradioactive electron source, which generates comparable spectra to the 3H source. An advantage of our emission current controlled nonradioactive electron source is that it can operate in a fast pulsed mode with high electron intensities. By optimizing the geometric parameters and developing fast control electronics, we can achieve very short electron emission pulses for ionization with high intensities and an adjustable pulse width of down to a few nanoseconds. This results in small ion packets at simultaneously high ion densities, which are subsequently separated in the drift tube. Normally, the required small ion packet is generated by a complex ion shutter mechanism. By omitting the additional reaction chamber, the ion packet can be generated directly at the beginning of the drift tube by our pulsed nonradioactive electron source with only slight reduction in resolving power. Thus, the complex and costly shutter mechanism and its electronics can also be omitted, which leads to a simple low-cost IMS-system with a pulsed nonradioactive electron source and a resolving power of 90.

  2. The Capture of Jupiter Trojans

    NASA Astrophysics Data System (ADS)

    Morbidelli, A.; Nesvorny, D.; Vokrouhlicky, D.

    2013-09-01

    The origin of Jupiter Trojans remained mysterious for decades. Particularly, it was difficult to explain the excitation of the inclinations of the Trojan population [1]. In 2005, Morbidelli et al. [2] proposed a scenario of capture from the trans-Neptunian disk, in the framework of the so-called "Nice model" [3,4]. This scenario explained in a natural way the observed orbital distribution of Trojans. The Nice model, however, evolved in the years, in order to satisfy an increasingly large number of constraints. It now appears that the dynamical evolution of the giant planets was different from that envisioned in [2]. Here, we assess again the process of capture of Trojans within this new evolution. We show that (6-8)×10 - 7 of the original trans-Neptunian planetesimals are captured in the Trojan region, with an orbital distribution consistent with the one observed. Relative to [2], the new capture mechanism has the potential of explaining the asymmetry between the L4 and L5 populations. Moreover, the resulting population of Trojans is consistent with that of the Irregular Satellites of Jupiter, which are captured in the same process; a few bodies from the main asteroid belt could also be captured in the Trojan cloud.

  3. Capture by colour: evidence for dimension-specific singleton capture.

    PubMed

    Harris, Anthony M; Becker, Stefanie I; Remington, Roger W

    2015-10-01

    Previous work on attentional capture has shown the attentional system to be quite flexible in the stimulus properties it can be set to respond to. Several different attentional "modes" have been identified. Feature search mode allows attention to be set for specific features of a target (e.g., red). Singleton detection mode sets attention to respond to any discrepant item ("singleton") in the display. Relational search sets attention for the relative properties of the target in relation to the distractors (e.g., redder, larger). Recently, a new attentional mode was proposed that sets attention to respond to any singleton within a particular feature dimension (e.g., colour; Folk & Anderson, 2010). We tested this proposal against the predictions of previously established attentional modes. In a spatial cueing paradigm, participants searched for a colour target that was randomly either red or green. The nature of the attentional control setting was probed by presenting an irrelevant singleton cue prior to the target display and assessing whether it attracted attention. In all experiments, the cues were red, green, blue, or a white stimulus rapidly rotated (motion cue). The results of three experiments support the existence of a "colour singleton set," finding that all colour cues captured attention strongly, while motion cues captured attention only weakly or not at all. Notably, we also found that capture by motion cues in search for colour targets was moderated by their frequency; rare motion cues captured attention (weakly), while frequent motion cues did not.

  4. CHAOTIC CAPTURE OF NEPTUNE TROJANS

    SciTech Connect

    Nesvorny, David; Vokrouhlicky, David

    2009-06-15

    Neptune Trojans (NTs) are swarms of outer solar system objects that lead/trail planet Neptune during its revolutions around the Sun. Observations indicate that NTs form a thick cloud of objects with a population perhaps {approx}10 times more numerous than that of Jupiter Trojans and orbital inclinations reaching {approx}25 deg. The high inclinations of NTs are indicative of capture instead of in situ formation. Here we study a model in which NTs were captured by Neptune during planetary migration when secondary resonances associated with the mean-motion commensurabilities between Uranus and Neptune swept over Neptune's Lagrangian points. This process, known as chaotic capture, is similar to that previously proposed to explain the origin of Jupiter's Trojans. We show that chaotic capture of planetesimals from an {approx}35 Earth-mass planetesimal disk can produce a population of NTs that is at least comparable in number to that inferred from current observations. The large orbital inclinations of NTs are a natural outcome of chaotic capture. To obtain the {approx}4:1 ratio between high- and low-inclination populations suggested by observations, planetary migration into a dynamically excited planetesimal disk may be required. The required stirring could have been induced by Pluto-sized and larger objects that have formed in the disk.

  5. IODIDE AEROSOL SORBENTS FOR MERCURY CAPTURE IN COMBUSTION EXHAUSTS

    EPA Science Inventory

    Several sorbent processes are being studied for their feasibility for mercury capture. Mercury is different from the other heavy metals as it is not as chemically reactive (due to a filled outer electronic shell), thus making it difficult for sorbents to chemically trap it (a). ...

  6. A Brief Introduction to Web-Based Note Capture

    ERIC Educational Resources Information Center

    Ovadia, Steven

    2012-01-01

    While physical notebooks and locally saved electronic files are certainly helpful, there are a number of web-based solutions that might be useful to someone conducting research online, or looking to hold their notes in a web-based environment. The main advantage of a web-based note capture tool is that one is able to access it from just about…

  7. Stability and capture of asteroids

    NASA Technical Reports Server (NTRS)

    Szebehely, V.

    1983-01-01

    The problem of stability of asteroids is treated from the point of view of Hill's stability-concept and using Lyapunov's Characteristic Numbers. The quantitative measure of stability (S) introduced earlier is evaluated for over 300 asteroids and a surprisingly simple relation is established between the semi-major axes of some of the asteroids' orbits and S. A detailed analysis is presented of the Lyapunov Characteristic Numbers for two minor planets and the time-variation of these numbers is discussed. The technology of capture of asteroids is vitally dependent on their orbital stability, therefore, these two problems, i.e., capture and stability, are closely related. In fact, some predictable instabilities may be properly utilized to capture and/or change asteroidal orbits to accomplish collisions with the Earth.

  8. Adaptive capture of expert behavior

    SciTech Connect

    Jones, R.D.; Barrett, C.L.; Hand, U.; Gordon, R.C.

    1994-08-01

    The authors smoothed and captured a set of expert rules with adaptive networks. The motivation for doing this is discussed. (1) Smoothing leads to stabler control actions. (2) For some sets of rules, the evaluation of the rules can be sped up. This is important in large-scale simulations where many intelligent elements are present. (3) Variability of the intelligent elements can be achieved by adjusting the weights in an adaptive network. (4) After capture has occurred, the weights can be adjusted based on performance criteria. The authors thus have the capability of learning a new set of rules that lead to better performance. The set of rules the authors chose to capture were based on a set of threat determining rules for tank commanders. The approach in this paper: (1) They smoothed the rules. The rule set was converted into a simple set of arithmetic statements. Continuous, non-binary inputs, are now permitted. (2) An operational measure of capturability was developed. (3) They chose four candidate networks for the rule set capture: (a) multi-linear network, (b) adaptive partial least squares, (c) connectionist normalized local spline (CNLS) network, and (d) CNLS net with a PLS preprocessor. These networks were able to capture the rule set to within a few percent. For the simple tank rule set, the multi-linear network performed the best. When the rules were modified to include more nonlinear behavior, CNLS net performed better than the other three nets which made linear assumptions. (4) The networks were tested for robustness to input noise. Noise levels of plus or minus 10% had no real effect on the network performance. Noise levels in the plus or minus 30% range degraded performance by a factor of two. Some performance enhancement occurred when the networks were trained with noisy data. (5) The scaling of the evaluation time was calculated. (6) Human variation can be mimicked in all the networks by perturbing the weights.

  9. EDOS Data Capture for ALOS

    NASA Technical Reports Server (NTRS)

    McLemore, Bruce; Cordier, Guy R.; Wood, Terri; Gamst, Harek

    2012-01-01

    In 2008, NASA's Earth Sciences Missions Operations (ESMO) at Goddard Space Flight Center (GSFC) directed the Earth Observing System Data Operations System (EDOS) project to provide a prototype system to assess the feasibility of high rate data capture for the Japan Aerospace Exploration Agency's (JAXA) Advanced Land Observing Satellite (ALOS) spacecraft via NASA's Tracking and Data Relay Satellite System (TDRSS). The key objective of this collaborative effort between NASA and JAXA was to share science data collected over North and South America previously unavailable due to limitations in ALOS downlink capacity. EDOS provided a single system proof-of-concept in 4 months at White Sands TDRS Ground Terminal The system captured 6 ALOS events error-free at 277 Mbps and delivered the data to the Alaska Satellite Facility (ASF) within 3 hours (May/June '08). This paper describes the successful rapid prototyping approach which led to a successful demonstration and agreement between NASA and JAXA for operational support. The design of the operational system will be discussed with emphasis on concurrent high-rate data capture, Level-O processing, real-time display and high-rate delivery with stringent latency requirements. A similar solution was successfully deployed at Svalbard, Norway to support the Suomi NPP launch (October 2011) and capture all X-band data and provide a 30-day backup archive.

  10. Penetration of multiple thin films in micrometeorite capture cells

    NASA Technical Reports Server (NTRS)

    Simon, Charles G.

    1994-01-01

    As part of a continuing effort to develop cosmic dust detectors/collectors for use in space, we performed a series of hypervelocity impact experiments on combined sensor/capture-cell assemblies using 10-200-micron-diameter glass projectiles and olivine crystals at velocities of 0.9-14.4 km/s. The design objective of the space-flight instrument is to measure the trajectories of individual particles with sufficient accuracy to permit identification of their parent bodies and to capture enough impactor material to allow chemical and isotopic analyses of samples returned to Earth. Three different multiple-film small-particle capture cell designs (0.1-100-micron-thick Al foils with approx. 10, 100, and 1800 micron spacing) were evaluated for their ability to capture impactor fragments and residue. Their performances were compared to two other types of capture cells, foil covered Ge crystals, and 0.50 and 0.120 g/cu cm aerogels. All capture cells were tested behind multifilm (1.4-6.0-micron-thick) polyvinylidene fluoride (PVDF) velocity/trajectory sensor devices. Several tests were also done without the PVDF sensors for comparison. The results of this study were reported by Simon in a comprehensive report in which the morphology of impacts and impactor residues in various types of capture cells after passage through two PVDF sensor films is discussed. Impactor fragments in selected capture cells from impacts at velocities up to 6.4 km/s were identified using scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS).

  11. The use of computer imaging technology to facilitate the capture of feedlot necropsy information.

    PubMed Central

    Wildman, B K; Schunicht, O C; Jim, G K; Guichon, P T; Booker, C W; Tollens, R A

    2000-01-01

    The collection of necropsy information is an integral component of veterinary feedlot consulting. Computer imaging technology can be employed to facilitate the capture of feedlot necropsy data. A digital camera is used to capture necropsy images. Subsequently, the images are electronically transferred to a central site for veterinary interpretation and diagnosis. Images Figure 1. PMID:10723598

  12. Natural materials for carbon capture.

    SciTech Connect

    Myshakin, Evgeniy M.; Romanov, Vyacheslav N.; Cygan, Randall Timothy

    2010-11-01

    Naturally occurring clay minerals provide a distinctive material for carbon capture and carbon dioxide sequestration. Swelling clay minerals, such as the smectite variety, possess an aluminosilicate structure that is controlled by low-charge layers that readily expand to accommodate water molecules and, potentially, carbon dioxide. Recent experimental studies have demonstrated the efficacy of intercalating carbon dioxide in the interlayer of layered clays but little is known about the molecular mechanisms of the process and the extent of carbon capture as a function of clay charge and structure. A series of molecular dynamics simulations and vibrational analyses have been completed to assess the molecular interactions associated with incorporation of CO2 in the interlayer of montmorillonite clay and to help validate the models with experimental observation.

  13. Proton Capture on 12C

    NASA Astrophysics Data System (ADS)

    Goerres, Joachim; Kettner, Karl-Ulrich; Becker, Hans-Werner; Deboer, Richard J.; Uberseder, Ethan; Wiescher, Michael C.

    2014-09-01

    During explosive Hydrogen burning the 12C(p, γ)13N reaction is the entry point which injects 12C, newly produced by the triple α-process, into the hot CNO cycle. At solar temperatures this reaction is one of the two sources for neutrinos within the CNO cycle whose observation would provide a test for the SSM. The capture cross section is determined by 2 resonances, the direct capture to the ground state as well as interferences between these components. To investigate uncertainties found in the literature for the 1.7 MeV resonance we have measured this reaction in the energy of 1.2 to 2.5 MeV. Detailed excitation functions were measured at 0° and 55° and complemented by angular distributions measured in 100 keV steps. The results of this experiment will be reported together with R-matrix fits over the entire energy range of astrophysical interest. During explosive Hydrogen burning the 12C(p, γ)13N reaction is the entry point which injects 12C, newly produced by the triple α-process, into the hot CNO cycle. At solar temperatures this reaction is one of the two sources for neutrinos within the CNO cycle whose observation would provide a test for the SSM. The capture cross section is determined by 2 resonances, the direct capture to the ground state as well as interferences between these components. To investigate uncertainties found in the literature for the 1.7 MeV resonance we have measured this reaction in the energy of 1.2 to 2.5 MeV. Detailed excitation functions were measured at 0° and 55° and complemented by angular distributions measured in 100 keV steps. The results of this experiment will be reported together with R-matrix fits over the entire energy range of astrophysical interest. Supported by the Nation Science Foundation.

  14. Spacecraft capture and docking system

    NASA Technical Reports Server (NTRS)

    Kong, Kinyuen (Inventor); Rafeek, Shaheed (Inventor); Myrick, Thomas (Inventor)

    2001-01-01

    A system for capturing and docking an active craft to a passive craft has a first docking assembly on the active craft with a first contact member and a spike projecting outwardly, a second docking assembly on the passive craft having a second contact member and a flexible net deployed over a target area with an open mesh for capturing the end of the spike of the active craft, and a motorized net drive for reeling in the net and active craft to mate with the passive craft's docking assembly. The spike has extendable tabs to allow it to become engaged with the net. The net's center is coupled to a net spool for reeling in. An alignment funnel has inclined walls to guide the net and captured spike towards the net spool. The passive craft's docking assembly includes circumferentially spaced preload wedges which are driven to lock the wedges against the contact member of the active craft. The active craft's docking assembly includes a rotary table and drive for rotating it to a predetermined angular alignment position, and mating connectors are then engaged with each other. The system may be used for docking spacecraft in zero or low-gravity environments, as well as for docking underwater vehicles, docking of ancillary craft to a mother craft in subsonic flight, in-flight refueling systems, etc.

  15. Block Copolymer Membranes for Efficient Capture of a Chemotherapy Drug

    PubMed Central

    2016-01-01

    We introduce the use of block copolymer membranes for an emerging application, “drug capture”. The polymer is incorporated in a new class of biomedical devices, referred to as ChemoFilter, which is an image-guided temporarily deployable endovascular device designed to increase the efficacy of chemotherapy-based cancer treatment. We show that block copolymer membranes consisting of functional sulfonated polystyrene end blocks and a structural polyethylene middle block (S-SES) are capable of capturing doxorubicin, a chemotherapy drug. We focus on the relationship between morphology of the membrane in the ChemoFilter device and efficacy of doxorubicin capture measured in vitro. Using small-angle X-ray scattering and cryogenic scanning transmission electron microscopy, we discovered that rapid doxorubicin capture is associated with the presence of water-rich channels in the lamellar-forming S-SES membranes in aqueous environment. PMID:27547493

  16. A low energy ion source for electron capture spectroscopy.

    PubMed

    Tusche, C; Kirschner, J

    2014-06-01

    We report on the design of an ion source for the production of single and double charged Helium ions with kinetic energies in the range from 300 eV down to 5 eV. The construction is based on a commercial sputter ion gun equipped with a Wien-filter for mass/charge separation. Retardation of the ions from the ionizer potential (2 keV) takes place completely within the lens system of the sputter gun, without modification of original parts. For 15 eV He(+) ions, the design allows for beam currents up to 30 nA, limited by the space charge repulsion in the beam. For He(2 +) operation, we obtain a beam current of 320 pA at 30 eV, and 46 pA at 5 eV beam energy, respectively. In addition, operating parameters can be optimized for a significant contribution of metastable He*(+) (2s) ions.

  17. Electron capture in collisions of S with H{sup +}

    SciTech Connect

    Zhao, L.B.; Stancil, P.C.; Gu, J.-P.; Liebermann, H.-P.; Funke, P.; Buenker, R.J.; Kimura, M.

    2005-06-15

    Within the framework of a fully quantum-mechanical molecular-orbital close-coupling (QMOCC) theory, charge transfer has been studied for collisions of S with H{sup +}. The multireference single- and double-excitation configuration-interaction method was utilized to evaluate the adiabatic potentials and nonadiabatic coupling matrix elements for the SH{sup +} system. Cross sections and rate coefficients are presented for S({sup 3}P,{sup 1}D)+H{sup +}{yields}S{sup +}({sup 4}S{sup 0},{sup 2}D{sup 0},{sup 2}P{sup 0})+H with relative collision energies between 0.1 meV/u and 10 keV/u and temperatures between 10 K and 2.0x10{sup 6} K. The investigation shows that the charge-transfer process is dominated by S({sup 3}P)+H{sup +}{yields}S{sup +}({sup 2}P{sup 0})+H and that the cross sections and rate coefficients vary by orders of magnitude over the energy and temperature range considered. The current rate coefficients are in disagreement with the often adopted value of 1.30x10{sup -9} cm{sup 3}/s at low temperatures, and two orders of magnitude smaller than a previous estimate at T=10{sup 4} K, for the process S({sup 3}P)+H{sup +}{yields}S{sup +}({sup 2}D{sup 0},{sup 2}P{sup 0})+H. We also performed semiclassical close-coupling calculations, which give cross sections in excellent agreement agreement with the QMOCC results for energies above 30 eV/u. Application of the results to astrophysical environments is briefly discussed.

  18. COMBUSTION-ASSISTED CO2 CAPTURE USING MECC MEMBRANES

    SciTech Connect

    Brinkman, K.; Gray, J.

    2012-03-30

    Mixed Electron and Carbonate ion Conductor (MECC) membranes have been proposed as a means to separate CO{sub 2} from power plant flue gas. Here a modified MECC CO{sub 2} capture process is analyzed that supplements retentate pressurization and permeate evacuation as a means to create a CO{sub 2} driving force with a process assisted by the catalytic combustion of syngas on the permeate side of the membrane. The combustion reactions consume transported oxygen, making it unavailable for the backwards transport reaction. With this change, the MECC capture system becomes exothermic, and steam for electricity production may be generated from the waste heat. Greater than 90% of the CO{sub 2} in the flue gas may be captured, and a compressed CO{sub 2} product stream is produced. A fossil-fueled power plant using this process would consume 14% more fuel per unit electricity produced than a power plant with no CO{sub 2} capture system, and has the potential to meet U.S. DOE's goal that deployment of a CO{sub 2} capture system at a fossil-fueled power plant should not increase the cost of electricity from the combined facility by more than 30%.

  19. Realistic costs of carbon capture

    SciTech Connect

    Al Juaied, Mohammed . Belfer Center for Science and International Affiaris); Whitmore, Adam )

    2009-07-01

    There is a growing interest in carbon capture and storage (CCS) as a means of reducing carbon dioxide (CO2) emissions. However there are substantial uncertainties about the costs of CCS. Costs for pre-combustion capture with compression (i.e. excluding costs of transport and storage and any revenue from EOR associated with storage) are examined in this discussion paper for First-of-a-Kind (FOAK) plant and for more mature technologies, or Nth-of-a-Kind plant (NOAK). For FOAK plant using solid fuels the levelised cost of electricity on a 2008 basis is approximately 10 cents/kWh higher with capture than for conventional plants (with a range of 8-12 cents/kWh). Costs of abatement are found typically to be approximately US$150/tCO2 avoided (with a range of US$120-180/tCO2 avoided). For NOAK plants the additional cost of electricity with capture is approximately 2-5 cents/kWh, with costs of the range of US$35-70/tCO2 avoided. Costs of abatement with carbon capture for other fuels and technologies are also estimated for NOAK plants. The costs of abatement are calculated with reference to conventional SCPC plant for both emissions and costs of electricity. Estimates for both FOAK and NOAK are mainly based on cost data from 2008, which was at the end of a period of sustained escalation in the costs of power generation plant and other large capital projects. There are now indications of costs falling from these levels. This may reduce the costs of abatement and costs presented here may be 'peak of the market' estimates. If general cost levels return, for example, to those prevailing in 2005 to 2006 (by which time significant cost escalation had already occurred from previous levels), then costs of capture and compression for FOAK plants are expected to be US$110/tCO2 avoided (with a range of US$90-135/tCO2 avoided). For NOAK plants costs are expected to be US$25-50/tCO2. Based on these considerations a likely representative range of costs of abatement from CCS excluding

  20. Algal Energy Conversion and Capture

    NASA Astrophysics Data System (ADS)

    Hazendonk, P.

    2015-12-01

    We address the potential for energy conversions and capture for: energy generation; reduction in energy use; reduction in greenhouse gas emissions; remediation of water and air pollution; protection and enhancement of soil fertility. These processes have the potential to sequester carbon at scales that may have global impact. Energy conversion and capture strategies evaluate energy use and production from agriculture, urban areas and industries, and apply existing and emerging technologies to reduce and recapture energy embedded in waste products. The basis of biocrude production from Micro-algal feedstocks: 1) The nutrients from the liquid fraction of waste streams are concentrated and fed into photo bioreactors (essentially large vessels in which microalgae are grown) along with CO2 from flue gasses from down stream processes. 2) The algae are processed to remove high value products such as proteins and beta-carotenes. The advantage of algae feedstocks is the high biomass productivity is 30-50 times that of land based crops and the remaining biomass contains minimal components that are difficult to convert to biocrude. 3) The remaining biomass undergoes hydrothermal liquefaction to produces biocrude and biochar. The flue gasses of this process can be used to produce electricity (fuel cell) and subsequently fed back into the photobioreactor. The thermal energy required for this process is small, hence readily obtained from solar-thermal sources, and furthermore no drying or preprocessing is required keeping the energy overhead extremely small. 4) The biocrude can be upgraded and refined as conventional crude oil, creating a range of liquid fuels. In principle this process can be applied on the farm scale to the municipal scale. Overall, our primary food production is too dependent on fossil fuels. Energy conversion and capture can make food production sustainable.

  1. Carbon Capture and Storage, 2008

    ScienceCinema

    None

    2016-07-12

    The U.S. Department of Energy is researching the safe implementation of a technology called carbon sequestration, also known as carbon capture and storage, or CCS. Based on an oilfield practice, this approach stores carbon dioxide, or CO2 generated from human activities for millennia as a means to mitigate global climate change. In 2003, the Department of Energys National Energy Technology Laboratory formed seven Regional Carbon Sequestration Partnerships to assess geologic formations suitable for storage and to determine the best approaches to implement carbon sequestration in each region. This video describes the work of these partnerships.

  2. Carbon Capture and Storage, 2008

    SciTech Connect

    2009-03-19

    The U.S. Department of Energy is researching the safe implementation of a technology called carbon sequestration, also known as carbon capture and storage, or CCS. Based on an oilfield practice, this approach stores carbon dioxide, or CO2 generated from human activities for millennia as a means to mitigate global climate change. In 2003, the Department of Energys National Energy Technology Laboratory formed seven Regional Carbon Sequestration Partnerships to assess geologic formations suitable for storage and to determine the best approaches to implement carbon sequestration in each region. This video describes the work of these partnerships.

  3. Chromosome Conformation Capture in Drosophila.

    PubMed

    Li, Hua-Bing

    2016-01-01

    Linear chromatin fiber is packed inside the nuclei as a complex three-dimensional structure, and the organization of the chromatin has important roles in the appropriate spatial and temporal regulation of gene expression. To understand how chromatin organizes inside nuclei, and how regulatory proteins physically interact with genes, chromosome conformation capture (3C) technique provides a powerful and sensitive tool to detect both short- and long-range DNA-DNA interaction. Here I describe the 3C technique to detect the DNA-DNA interactions mediated by insulator proteins that are closely related to PcG in Drosophila, which is also broadly applicable to other systems.

  4. Astronauts Capture Moon Illusion Photo

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Many odd looking moon photos have been captured over the years by astronauts aboard the International Space Station. Even so, this photograph, taken by the crew over Russia on May 11, 2003, must have come as a surprise. The moon which is really a quarter of a million miles away, appears to be floating inside the Earth's atmosphere. The picture is tricky because of its uneven lighting. With the sun's elevation angle at only 6 degrees, night is falling on the left side of the image while it is still broad daylight on the right side. This gradient of sunlight is the key to the illusion.

  5. Non-Statistical Effects in Neutron Capture

    NASA Astrophysics Data System (ADS)

    Koehler, P. E.; Bredeweg, T. A.; Guber, K. H.; Harvey, J. A.; O'Donnell, J. M.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wiarda, D.; Wouters, J. M.

    2009-01-01

    There have been many reports of non-statistical effects in neutron-capture measurements. However, reports of deviations of reduced-neutron-width (Γn0) distributions from the expected Porter-Thomas (PT) shape largely have been ignored. Most of these deviations have been reported for odd-A nuclides. Because reliable spin (J) assignments have been absent for most resonances for such nuclides, it is possible that reported deviations from PT might be due to incorrect J assignments. We recently developed a new method for measuring spins of neutron resonances by using the DANCE detector at the Los Alamos Neutron Science Center (LANSCE). Measurements made with a 147Sm sample allowed us to determine spins of almost all known resonances below 1 keV. Furthermore, analysis of these data revealed that the Γn0 distribution was in good agreement with PT for resonances below 350 eV, but in disagreement with PT for resonances between 350 and 700 eV. Our previous (n,α) measurements had revealed that the α strength function also changes abruptly at this energy. There currently is no known explanation for these two non-statistical effects. Recently, we have developed another new method for determining the spins of neutron resonances. To implement this technique required a small change (to record pulse-height information for coincidence events) to a much simpler apparatus: A pair of C6D6 γ-ray detectors which we have employed for many years to measure neutron-capture cross sections at the Oak Ridge Electron Linear Accelerator (ORELA). Measurements with a 95Mo sample revealed that not only does the method work very well for determining spins, but it also makes possible parity assignments. Taken together, these new techniques at LANSCE and ORELA could be very useful for further elucidation of non-statistical effects.

  6. Advanced Docking System With Magnetic Initial Capture

    NASA Technical Reports Server (NTRS)

    Lewis, James L.; Carroll, Monty B.; Morales, Ray; Le, Thang

    2004-01-01

    An advanced docking system is undergoing development to enable softer, safer docking than was possible when using prior docking systems. This system is intended for original use in docking of visiting spacecraft and berthing the Crew Return Vehicle at the International Space Station (ISS). The system could also be adapted to a variety of other uses in outer space and on Earth, including mating submersible vehicles, assembling structures, and robotic berthing/handling of payloads and cargo. Heretofore, two large spacecraft have been docked by causing the spacecraft to approach each other at a speed sufficient to activate capture latches - a procedure that results in large docking loads and is made more difficult because of the speed. The basic design and mode of operation of the present advanced docking system would eliminate the need to rely on speed of approach to activate capture latches, thereby making it possible to reduce approach speed and thus docking loads substantially. The system would comprise an active subsystem on one spacecraft and a passive subsystem on another spacecraft with which the active subsystem will be docked. The passive subsystem would include an extensible ring containing magnetic striker plates and guide petals. The active subsystem would include mating guide petals and electromagnets containing limit switches and would be arranged to mate with the magnetic striker plates and guide petals of the passive assembly. The electromagnets would be carried on (but not rigidly attached to) a structural ring that would be instrumented with load sensors. The outputs of the sensors would be sent, along with position information, as feedback to an electronic control subsystem. The system would also include electromechanical actuators that would extend or retract the ring upon command by the control subsystem.

  7. Non-Statistical Effects in Neutron Capture

    SciTech Connect

    Koehler, P. E.; Guber, K. H.; Harvey, J. A.; Wiarda, D.; Bredeweg, T. A.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wouters, J. M.; Reifarth, R.

    2009-01-28

    There have been many reports of non-statistical effects in neutron-capture measurements. However, reports of deviations of reduced-neutron-width ({gamma}{sub n}{sup 0}) distributions from the expected Porter-Thomas (PT) shape largely have been ignored. Most of these deviations have been reported for odd-A nuclides. Because reliable spin (J) assignments have been absent for most resonances for such nuclides, it is possible that reported deviations from PT might be due to incorrect J assignments. We recently developed a new method for measuring spins of neutron resonances by using the DANCE detector at the Los Alamos Neutron Science Center (LANSCE). Measurements made with a {sup 147}Sm sample allowed us to determine spins of almost all known resonances below 1 keV. Furthermore, analysis of these data revealed that the {gamma}{sub n}{sup 0} distribution was in good agreement with PT for resonances below 350 eV, but in disagreement with PT for resonances between 350 and 700 eV. Our previous (n,{alpha}) measurements had revealed that the {alpha} strength function also changes abruptly at this energy. There currently is no known explanation for these two non-statistical effects. Recently, we have developed another new method for determining the spins of neutron resonances. To implement this technique required a small change (to record pulse-height information for coincidence events) to a much simpler apparatus: A pair of C{sub 6}D{sub 6}{gamma}-ray detectors which we have employed for many years to measure neutron-capture cross sections at the Oak Ridge Electron Linear Accelerator (ORELA). Measurements with a {sup 95}Mo sample revealed that not only does the method work very well for determining spins, but it also makes possible parity assignments. Taken together, these new techniques at LANSCE and ORELA could be very useful for further elucidation of non-statistical effects.

  8. Non-Statistical Effects in Neutron Capture

    SciTech Connect

    Koehler, Paul Edward; Bredeweg, t a; Guber, Klaus H; Harvey, John A; O'Donnell, J. M.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wiarda, Dorothea; Wouters, J. M.

    2009-01-01

    There have been many reports of non-statistical effects in neutron-capture measurements. However, reports of deviations of reduced-neutron-width ({Gamma}n{sup 0}) distributions from the expected Porter-Thomas (PT) shape largely have been ignored. Most of these deviations have been reported for odd-A nuclides. Because reliable spin (J) assignments have been absent for most resonances for such nuclides, it is possible that reported deviations from PT might be due to incorrect J assignments. We recently developed a new method for measuring spins of neutron resonances by using the DANCE detector at the Los Alamos Neutron Science Center (LANSCE). Measurements made with a 147Sm sample allowed us to determine spins of almost all known resonances below 1 keV. Furthermore, analysis of these data revealed that the {Gamma}n{sup 0} distribution was in good agreement with PT for resonances below 350 eV, but in disagreement with PT for resonances between 350 and 700 eV. Our previous (n,{alpha}) measurements had revealed that the {alpha} strength function also changes abruptly at this energy. There currently is no known explanation for these two non-statistical effects. Recently, we have developed another new method for determining the spins of neutron resonances. To implement this technique required a small change (to record pulse-height information for coincidence events) to a much simpler apparatus: A pair of C6D6 ?-ray detectors which we have employed for many years to measure neutron-capture cross sections at the Oak Ridge Electron Linear Accelerator (ORELA). Measurements with a 95Mo sample revealed that not only does the method work very well for determining spins, but it also makes possible parity assignments. Taken together, these new techniques at LANSCE and ORELA could be very useful for further elucidation of non-statistical effects.

  9. 49 CFR 563.9 - Data capture.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 6 2014-10-01 2014-10-01 false Data capture. 563.9 Section 563.9 Transportation..., DEPARTMENT OF TRANSPORTATION EVENT DATA RECORDERS § 563.9 Data capture. The EDR must capture and record the data elements for events in accordance with the following conditions and circumstances: (a) In...

  10. 49 CFR 563.9 - Data capture.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 6 2012-10-01 2012-10-01 false Data capture. 563.9 Section 563.9 Transportation..., DEPARTMENT OF TRANSPORTATION EVENT DATA RECORDERS § 563.9 Data capture. The EDR must capture and record the data elements for events in accordance with the following conditions and circumstances: (a) In...

  11. 49 CFR 563.9 - Data capture.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 6 2013-10-01 2013-10-01 false Data capture. 563.9 Section 563.9 Transportation..., DEPARTMENT OF TRANSPORTATION EVENT DATA RECORDERS § 563.9 Data capture. The EDR must capture and record the data elements for events in accordance with the following conditions and circumstances: (a) In...

  12. 49 CFR 563.9 - Data capture.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 6 2011-10-01 2011-10-01 false Data capture. 563.9 Section 563.9 Transportation..., DEPARTMENT OF TRANSPORTATION EVENT DATA RECORDERS § 563.9 Data capture. Link to an amendment published at 76 FR 47489, Aug. 5, 2011. The EDR must capture and record the data elements for events in...

  13. The Effectiveness of Classroom Capture Technology

    ERIC Educational Resources Information Center

    Ford, Maire B.; Burns, Colleen E.; Mitch, Nathan; Gomez, Melissa M.

    2012-01-01

    The use of classroom capture systems (systems that capture audio and video footage of a lecture and attempt to replicate a classroom experience) is becoming increasingly popular at the university level. However, research on the effectiveness of classroom capture systems in the university classroom has been limited due to the recent development and…

  14. The elements of design knowledge capture

    NASA Technical Reports Server (NTRS)

    Freeman, Michael S.

    1988-01-01

    This paper will present the basic constituents of a design knowledge capture effort. This will include a discussion of the types of knowledge to be captured in such an effort and the difference between design knowledge capture and more traditional knowledge base construction. These differences include both knowledge base structure and knowledge acquisition approach. The motivation for establishing a design knowledge capture effort as an integral part of major NASA programs will be outlined, along with the current NASA position on that subject. Finally the approach taken in design knowledge capture for Space Station will be contrasted with that used in the HSTDEK project.

  15. Bad data packet capture device

    DOEpatents

    Chen, Dong; Gara, Alan; Heidelberger, Philip; Vranas, Pavlos

    2010-04-20

    An apparatus and method for capturing data packets for analysis on a network computing system includes a sending node and a receiving node connected by a bi-directional communication link. The sending node sends a data transmission to the receiving node on the bi-directional communication link, and the receiving node receives the data transmission and verifies the data transmission to determine valid data and invalid data and verify retransmissions of invalid data as corresponding valid data. A memory device communicates with the receiving node for storing the invalid data and the corresponding valid data. A computing node communicates with the memory device and receives and performs an analysis of the invalid data and the corresponding valid data received from the memory device.

  16. Neutron capture therapy for melanoma

    SciTech Connect

    Coderre, J.A.; Glass, J.D.; Micca, P.; Fairchild, R.G.

    1988-01-01

    The development of boron-containing compounds which localize selectively in tumor may require a tumor-by-tumor type of approach that exploits any metabolic pathways unique to the particular type of tumor. Melanin-producing melanomas actively transport and metabolize aromatic amino acids for use as precursors in the synthesis of the pigment melanin. It has been shown that the boron-containing amino acid analog p-borono-phenylalanine (BPA) is selectively accumulated in melanoma tissue, producing boron concentrations in tumor that are within the range estimated to be necessary for successful boron neutron capture therapy (BNCT). We report here the results of therapy experiments carried out at the Brookhaven Medical Research Reactor (BMRR). 21 refs., 5 figs., 3 tabs.

  17. Workshop on neutron capture therapy

    SciTech Connect

    Fairchild, R.G.; Bond, V.P.

    1986-01-01

    Potentially optimal conditions for Neutron Capture Therapy (NCT) may soon be in hand due to the anticipated development of band-pass filtered beams relatively free of fast neutron contaminations, and of broadly applicable biomolecules for boron transport such as porphyrins and monoclonal antibodies. Consequently, a number of groups in the US are now devoting their efforts to exploring NCT for clinical application. The purpose of this Workshop was to bring these groups together to exchange views on significant problems of mutual interest, and to assure a unified and effective approach to the solutions. Several areas of preclinical investigation were deemed to be necessary before it would be possible to initiate clinical studies. As neither the monomer nor the dimer of sulfhydryl boron hydride is unequivocally preferable at this time, studies on both compounds should be continued until one is proven superior.

  18. Subsurface capture of carbon dioxide

    SciTech Connect

    Blount, Gerald; Siddal, Alvin A.; Falta, Ronald W.

    2014-07-22

    A process and apparatus of separating CO.sub.2 gas from industrial off-gas source in which the CO.sub.2 containing off-gas is introduced deep within an injection well. The CO.sub.2 gases are dissolved in the, liquid within the injection well while non-CO.sub.2 gases, typically being insoluble in water or brine, are returned to the surface. Once the CO.sub.2 saturated liquid is present within the injection well, the injection well may be used for long-term geologic storage of CO.sub.2 or the CO.sub.2 saturated liquid can be returned to the surface for capturing a purified CO.sub.2 gas.

  19. Radiative capture versus Coulomb dissociation.

    SciTech Connect

    Esbensen, H.; Physics

    2006-01-01

    Measurements of the Coulomb dissociation of {sup 8}B have been used to infer the rate of the inverse radiative proton capture on {sup 7}Be. The analysis is usually based on the assumptions that the two processes are related by detailed balance and described by E1 transitions. However, there are corrections to this relation. The Coulomb form factors for the two processes, for example, are not identical. There are also E2 transitions and higher-order effects in the Coulomb dissociation, and the nuclear induced breakup cannot always be ignored. While adding first-order E2 transitions enhances the decay energy spectrum, the other mechanisms cause a suppression at low relative energies. The net result may accidentally be close to the conventional first-order E1 calculation, but there are differences which cannot be ignored if accuracies of 10% or better are needed.

  20. Small Particles Intact Capture Experiment (SPICE)

    NASA Technical Reports Server (NTRS)

    Nishioka, Ken-Ji; Carle, G. C.; Bunch, T. E.; Mendez, David J.; Ryder, J. T.

    1994-01-01

    The Small Particles Intact Capture Experiment (SPICE) will develop technologies and engineering techniques necessary to capture nearly intact, uncontaminated cosmic and interplanetary dust particles (IDP's). Successful capture of such particles will benefit the exobiology and planetary science communities by providing particulate samples that may have survived unaltered since the formation of the solar system. Characterization of these particles may contribute fundamental data to our knowledge of how these particles could have formed into our planet Earth and, perhaps, contributed to the beginnings of life. The term 'uncontaminated' means that captured cosmic and IDP particles are free of organic contamination from the capture process and the term 'nearly intact capture' means that their chemical and elemental components are not materially altered during capture. The key to capturing cosmic and IDP particles that are organic-contamination free and nearly intact is the capture medium. Initial screening of capture media included organic foams, multiple thin foil layers, and aerogel (a silica gel); but, with the exception of aerogel, the requirements of no contamination or nearly intact capture were not met. To ensure no contamination of particles in the capture process, high-purity aerogel was chosen. High-purity aerogel results in high clarity (visual clearness), a useful quality in detection and recovery of embedded captured particles from the aerogel. P. Tsou at the Jet Propulsion Laboratory (JPL) originally described the use of aerogel for this purpose and reported laboratory test results. He has flown aerogel as a 'GAS-can Lid' payload on STS-47 and is evaluating the results. The Timeband Capture Cell Experiment (TICCE), a Eureca 1 experiment, is also flying aerogel and is scheduled for recovery in late April.