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Sample records for fe k-shell absorption

  1. Evidence for ultra-fast outflows in radio-quiet AGNs: I - detection and statistical incidence of Fe K-shell absorption lines

    CERN Document Server

    Tombesi, F; Reeves, J N; Palumbo, G G C; Yaqoob, T; Braito, V; Dadina, M

    2010-01-01

    We performed a blind search for narrow absorption features at energies greater than 6.4 keV in a sample of 42 radio-quiet AGNs observed with XMM-Newton. We detect 36 narrow absorption lines on a total of 101 XMM-Newton EPIC pn observations. The number of absorption lines at rest-frame energies E>7 keV is 22. Their global probability to be generated by random fluctuations is very low, less than 3x10^-8, and their detection have been independently confirmed by a spectral analysis of the MOS data, with associated random probability <10^-7. We identify the lines as Fe XXV and Fe XXVI K-shell resonant absorption. They are systematically blue-shifted, with a velocity distribution ranging from zero up to 0.3c, with a peak and mean value at 0.1c. We detect variability of the lines on both EWs and blue-shifted velocities among different observations even on time-scales as short as a few days, possibly suggesting somewhat compact absorbers. Moreover, we find no significant correlation between the cosmological red-sh...

  2. Evidence for Ultra-fast Outflows in Radio-quiet Active Galactic Nuclei. II. Detailed Photoionization Modeling of Fe K-shell Absorption Lines

    Science.gov (United States)

    Tombesi, F.; Cappi, M.; Reeves, J. N.; Palumbo, G. G. C.; Braito, V.; Dadina, M.

    2011-11-01

    X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet active galactic nuclei (AGNs). These have been detected essentially through blueshifted Fe XXV/XXVI K-shell transitions. In the previous paper of this series we defined UFOs as those highly ionized absorbers with an outflow velocity higher than 10,000 km s-1 and assessed the statistical significance of the associated blueshifted absorption lines in a large sample of 42 local radio-quiet AGNs observed with XMM-Newton. The present paper is an extension of that work. First, we report a detailed curve of growth analysis of the main Fe XXV/XXVI transitions in photoionized plasmas. Then, we estimate an average spectral energy distribution for the sample sources and directly model the Fe K absorbers in the XMM-Newton spectra with the detailed Xstar photoionization code. We confirm that the frequency of sources in the radio-quiet sample showing UFOs is >35% and that the majority of the Fe K absorbers are indeed associated with UFOs. The outflow velocity distribution spans from ~10,000 km s-1 (~0.03c) up to ~100,000 km s-1 (~0.3c), with a peak and mean value of ~42,000 km s-1 (~0.14c). The ionization parameter is very high and in the range log ξ ~ 3-6 erg s-1 cm, with a mean value of log ξ ~ 4.2 erg s-1 cm. The associated column densities are also large, in the range N H ~ 1022-1024 cm-2, with a mean value of N H ~ 1023 cm-2. We discuss and estimate how selection effects, such as those related to the limited instrumental sensitivity at energies above 7 keV, may hamper the detection of even higher velocities and higher ionization absorbers. We argue that, overall, these results point to the presence of extremely ionized and possibly almost Compton-thick outflowing material in the innermost regions of AGNs. This also suggests that UFOs may potentially play a significant role in the expected cosmological feedback from AGNs and their study can

  3. Laboratory Studies of the Fe K-shell Emission

    Energy Technology Data Exchange (ETDEWEB)

    Beiersdorfer, P

    2004-12-26

    An overview is given of measurements of the Fe K-shell spectrum from low-density laboratory sources. The measurements include wavelengths, electron-impact collision cross sections, innershell ionization phenomena, dielectronic recombination resonance strengths, charge exchange recombination, electron beam polarization effects, resonance excitation, and radiative cascade contributions. K-shell spectra have now also been obtained with microcalorimeters, including microcalorimeter arrays that are twins of the ASTRO-E and ASTRO-E2 missions, which illustrate typical resolving powers and spectral capabilities.

  4. Evidence for ultra-fast outflows in radio-quiet AGNs: II - detailed photo-ionization modeling of Fe K-shell absorption lines

    CERN Document Server

    Tombesi, F; Reeves, J N; Palumbo, G G C; Braito, V; Dadina, M

    2011-01-01

    X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet AGNs. In the previous paper of this series we defined UFOs as those absorbers with an outflow velocity higher than 10,000km/s and assessed the statistical significance of the associated blueshifted FeK absorption lines in a large sample of 42 local radio-quiet AGNs observed with XMM-Newton. In the present paper we report a detailed curve of growth analysis and directly model the FeK absorbers with the Xstar photo-ionization code. We confirm that the frequency of sources in the radio-quiet sample showing UFOs is >35%. The outflow velocity distribution spans from \\sim10,000km/s (\\sim0.03c) up to \\sim100,000km/s (\\sim0.3c), with a peak and mean value of \\sim42,000km/s (\\sim0.14c). The ionization parameter is very high and in the range log\\xi 3-6erg s^{-1} cm, with a mean value of log\\xi 4.2 erg s^{-1} cm. The associated column densities are also large, in the range N_H\\sim10^{22}-10^{24...

  5. Evidence for ultra-fast outflows in radio-quiet AGNs. I. Detection and statistical incidence of Fe K-shell absorption lines

    Science.gov (United States)

    Tombesi, F.; Cappi, M.; Reeves, J. N.; Palumbo, G. G. C.; Yaqoob, T.; Braito, V.; Dadina, M.

    2010-10-01

    Context. Blue-shifted Fe K absorption lines have been detected in recent years between 7 and 10 keV in the X-ray spectra of several radio-quiet AGNs. The derived blue-shifted velocities of the lines can often reach mildly relativistic values, up to 0.2-0.4c. These findings are important because they suggest the presence of a previously unknown massive and highly ionized absorbing material outflowing from their nuclei, possibly connected with accretion disk winds/outflows. Aims: The scope of the present work is to statistically quantify the parameters and incidence of the blue-shifted Fe K absorption lines through a uniform analysis on a large sample of radio-quiet AGNs. This allows us to assess their global detection significance and to overcome any possible publication bias. Methods: We performed a blind search for narrow absorption features at energies greater than 6.4 keV in a sample of 42 radio-quiet AGNs observed with XMM-Newton. A simple uniform model composed by an absorbed power-law plus Gaussian emission and absorption lines provided a good fit for all the data sets. We derived the absorption lines parameters and calculated their detailed detection significance making use of the classical F-test and extensive Monte Carlo simulations. Results: We detect 36 narrow absorption lines on a total of 101 XMM-Newton EPIC pn observations. The number of absorption lines at rest-frame energies higher than 7 keV is 22. Their global probability to be generated by random fluctuations is very low, less than 3 × 10-8, and their detection have been independently confirmed by a spectral analysis of the MOS data, with associated random probability UFOs) those highly ionized absorbers with outflow velocities higher than 104 km s-1, then the majority of the lines are consistent with being associated to UFOs and the fraction of objects with detected UFOs in the whole sample is at least ~35%. This fraction is similar for type 1 and type 2 sources. The global covering fraction of

  6. Evidence for Ultra-Fast Outflows in Radio-Quiet AGNs. 2; Detailed Photoionization Modeling of Fe K-Shell Absorption Lines

    Science.gov (United States)

    Tombesi, Francesco; Clapp, M.; Reeves, J. N.; Palumbo, G. G. C.; Braito, V.; Dadina, M.

    2011-01-01

    X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet AGNs. In the previous paper of this series we defined UFOs as those absorbers with an outflow velocity higher than 10,000km/s and assessed the statistical significance of the associated blue shifted FeK absorption lines in a large sample of 42 local radio-quiet AGNs observed with XMM-Newton. In the present paper we report a detailed curve of growth analysis and directly model the FeK absorbers with the Xstar photo-ionization code. We confirm that the frequency of sources in the radio-quiet sample showing UFOs is >35%. The outflow velocity distribution spans from \\sim10,000km/s (\\sim0.03c) up to \\siml00,000kmis (\\sim0.3c), with a peak and mean value of\\sim42,000km/s (\\sim0.14c). The ionization parameter is very high and in the range log\\xi 3-6 erg s/cm, with a mean value of log\\xi 4.2 erg s/cm. The associated column densities are also large, in the range N_H\\siml0(exp 22)-10(exp 24)/sq cm, with a mean value of N_H\\siml0(exp23)/sq cm. We discuss and estimate how selection effects, such as those related to the limited instrumental sensitivity at energies above 7keV, may hamper the detection of even higher velocities and higher ionization absorbers. We argue that, overall, these results point to the presence of extremely ionized and possibly almost Compton thick outflowing material in the innermost regions of AGNs. This also suggests that UFOs may potentially play a significant role in the expected cosmological feedback from AGNs and their study can provide important clues on the connection between accretion disks, winds and jets.

  7. Chemical effect on the K shell absorption parameters of some selected cerium compounds

    Science.gov (United States)

    Akman, F.; Kaçal, M. R.; Durak, R.

    2016-08-01

    In this study, the photoelectric cross section values of Ce, CeCl3.7H2O, Ce2(SO4)3, Ce(OH)4 and Ce2O3 samples were measured in the energy range from 31.82 keV up to 51.70 keV by adopting in narrow beam geometry. Using these photoelectric cross sections, the K shell photoelectric cross sections at the K-edge, the K shell absorption jump ratios and jump factors, the Davisson-Kirchner ratios and K shell oscillator strength values were estimated experimentally. The measured parameters were compared with the theoretical calculated values. It is observed that the K shell photoelectric cross section at the K-edge and K shell oscillator strength values of an element are affected by the chemical environment of material while the K shell absorption jump ratio, K shell absorption jump factor and Davisson-Kirchner ratio are not affected by the chemical environment of material for the present samples. To the best of our knowledge, the chemical effects on the Davisson-Kirchner ratio and K shell oscillator strength have not been discussed for any element by now.

  8. Chemical effect on the K shell fluorescence yield of Fe, Mn, Co, Cr and Cu compounds

    Indian Academy of Sciences (India)

    U Turgut

    2004-11-01

    Chemical effects on the K shell fluorescence yields of Fe, Mn, Co, Cr and Cu compounds were investigated. Samples were excited using 59.5 keV energy photons from a 241Am radioisotope source. K X-rays emitted by samples were counted by a Si(Li) detector with a resolution 160 eV at 5.9 keV. Chemical effects on the K shell fluorescence yields (K) for Fe, Mn, Co, Cr and Cu compounds were observed. The values are compared with theoretical, semiempirical fit and experimental ones for the pure elements.

  9. Double K-shell ionization in the electron capture decay of 55Fe

    Science.gov (United States)

    Campbell, J. L.; Maxwell, J. A.; Teesdale, W. J.

    1991-04-01

    The probability per K capture for double K-shell ionization in the electron capture decay of 55Fe was obtained by fitting a model spectrum to the x-ray spectrum recorded to very high statistics in a high-resolution Si(Li) detector. The result, PKK=(1.3+/-0.2)×10-4, confirms the trend wherein experimental data decrease smoothly with Z, and are intermediate between the theoretical predictions of Intemann and of Suzuki and Law. Corrections to some recently published PKK values reconcile them with this trend.

  10. First-Principles Calculation of Principal Hugoniot and K-Shell X-ray Absorption Spectra for Warm Dense KCl

    CERN Document Server

    Zhao, Shijun; Kang, Wei; Li, Zi; Zhang, Ping; He, Xian-Tu

    2015-01-01

    Principal Hugoniot and K-shell X-ray absorption spectra of warm dense KCl are calculated using the first-principles molecular dynamics method. Evolution of electronic structures as well as the influence of the approximate description of ionization on pressure (caused by the underestimation of the energy gap between conduction bands and valence bands) in the first-principles method are illustrated by the calculation. Pressure ionization and thermal smearing are shown as the major factors to prevent the deviation of pressure from global accumulation along the Hugoniot. In addition, cancellation between electronic kinetic pressure and virial pressure further reduces the deviation. The calculation of X-ray absorption spectra shows that the band gap of KCl persists after the pressure ionization of the $3p$ electrons of Cl and K taking place at lower energy, which provides a detailed understanding to the evolution of electronic structures of warm dense matter.

  11. Suzaku Discovery of Fe K-Shell Line from the O-Rich SNR G292.0+1.8

    CERN Document Server

    Kamitsukasa, Fumiyoshi; Tsunemi, Hiroshi; Hayashida, Kiyoshi; Nakajima, Hiroshi; Takahashi, Hiroaki; Ueda, Shutaro; Mori, Koji; Katsuda, Satoru; Uchida, Hiroyuki

    2014-01-01

    We report the Suzaku/XIS results of the Galactic oxygen-rich supernova remnant (SNR), G292.0+1.8, a remnant of a core-collapse supernova. The X-ray spectrum of G292.0+1.8 consists of two type plasmas, one is in collisional ionization equilibrium (CIE) and the other is in non-equilibrium ionization (NEI). The CIE plasma has nearly solar abundances, and hence would be originated from the circumstellar and interstellar mediums. The NEI plasma has super-solar abundances, and the abundance pattern indicates that the plasma originates from the supernova ejecta with a main sequence of 30-35 Msolar. Iron K-shell line at energy of 6.6 keV is detected for the first time in the NEI plasma.

  12. Measurement of the double K-shell vacancy creation probability in the electron-capture decay of 55Fe with active-pixel detectors

    Science.gov (United States)

    Michel, Thilo; Bergmann, Benedikt; Durst, Jürgen; Filipenko, Mykaylo; Gleixner, Thomas; Zuber, Kai

    2014-01-01

    Background: In electron-capture decay, a second K-shell vacancy is eventually created with a small probability. Measurements of the double-vacancy creation probability per K-shell electron capture PKK of various nuclei undergoing electron-capture decays have already been performed, but the statistical accuracy of PKK of several nuclides is still not satisfying. Purpose: The purpose of this experiment was to improve the statistical error of PKK in the decay of 55Fe and to demonstrate the possibility of detecting double-vacancy creation events with position resolving pixel detectors. This enables angle resolved measurements. Method: For the first time, two active-pixel detectors (A,B) were used to detect satellite- and hypersatellite-line photons in coincidence either both in two clusters of triggered pixels in only one detector (A,B) or in both detectors (A∧B). PKK was determined for the two detectors regarded as one single, larger detector (PKK), for each detector separately (single-sided analysis: PKK ,A⊻B), and for both detectors in coincidence (double-sided analysis: PKK ,A∧B). Results: The result of the experiment is PKK=(1.531±0.079)×10-4 with a systematic error of (ΔPKK)syst=±0.023×10-4. This value is in agreement with the value previously measured by Campbell et al. of PKK=(1.3±0.2)×10-4. The discrepancy in literature between PKK of 54Mn to the expected value extrapolated from 55Fe almost vanished with our result. The asymmetry between the result of the single-sided analysis (PKK ,A⊻B) and the double-sided analysis (PKK ,A∧B) is consistent with zero: (PKK ,A⊻B-PKK ,A∧B)/(PKK ,A⊻B+PKK ,A∧B)=-0.003±0.051. This supports the assumption that angular correlations between the two photons are negligible within the achieved level of statistical accuracy for the given angular acceptance of our detectors. Conclusions: One can conclude that hybrid photon counting pixel detectors can be used to measure angular correlations between the directions

  13. 5.9 keV Mn K-shell X-ray luminosity from the decay of 55Fe in Type Ia supernova models

    CERN Document Server

    Seitenzahl, I R; Krauss, F; Sim, S A; Diehl, R; Elsaesser, D; Fink, M; Hillebrandt, W; Kromer, M; Maeda, K; Mannheim, K; Pakmor, R; Roepke, F K; Ruiter, A J; Wilms, J

    2014-01-01

    We show that the X-ray line flux of the Mn Kalpha line at 5.9 keV from the decay of 55Fe is a promising diagnostic to distinguish between Type Ia supernova (SN Ia) explosion models. Using radiation transport calculations, we compute the line flux for two 3D explosion models: a near-Chandrasekhar mass delayed detonation and a violent merger of two white dwarfs. Both models are based on solar metallicity zero-age main sequence progenitors. Due to explosive nuclear burning at higher density, the delayed-detonation model synthesises 3.5 times more radioactive 55Fe than the merger model. As a result, we find that the peak Mn Kalpha line flux of the delayed-detonation model exceeds that of the merger model by a factor of 4.5. Since in both models the 5.9 keV X-ray flux peaks five to six years after the explosion, a single measurement of the X-ray line emission at this time can place a constraint on the explosion physics that is complementary to those derived from earlier phase optical spectra or light curves. We pe...

  14. 5.9-keV Mn K-shell X-ray luminosity from the decay of 55Fe in Type Ia supernova models

    Science.gov (United States)

    Seitenzahl, I. R.; Summa, A.; Krauß, F.; Sim, S. A.; Diehl, R.; Elsässer, D.; Fink, M.; Hillebrandt, W.; Kromer, M.; Maeda, K.; Mannheim, K.; Pakmor, R.; Röpke, F. K.; Ruiter, A. J.; Wilms, J.

    2015-02-01

    We show that the X-ray line flux of the Mn Kα line at 5.9 keV from the decay of 55Fe is a promising diagnostic to distinguish between Type Ia supernova (SN Ia) explosion models. Using radiation transport calculations, we compute the line flux for two three-dimensional explosion models: a near-Chandrasekhar mass delayed detonation and a violent merger of two (1.1 and 0.9 M⊙) white dwarfs. Both models are based on solar metallicity zero-age main-sequence progenitors. Due to explosive nuclear burning at higher density, the delayed-detonation model synthesizes ˜3.5 times more radioactive 55Fe than the merger model. As a result, we find that the peak Mn Kα line flux of the delayed-detonation model exceeds that of the merger model by a factor of ˜4.5. Since in both models the 5.9-keV X-ray flux peaks five to six years after the explosion, a single measurement of the X-ray line emission at this time can place a constraint on the explosion physics that is complementary to those derived from earlier phase optical spectra or light curves. We perform detector simulations of current and future X-ray telescopes to investigate the possibilities of detecting the X-ray line at 5.9 keV. Of the currently existing telescopes, XMM-Newton/pn is the best instrument for close (≲1-2 Mpc), non-background limited SNe Ia because of its large effective area. Due to its low instrumental background, Chandra/ACIS is currently the best choice for SNe Ia at distances above ˜2 Mpc. For the delayed-detonation scenario, a line detection is feasible with Chandra up to ˜3 Mpc for an exposure time of 106 s. We find that it should be possible with currently existing X-ray instruments (with exposure times ≲5 × 105 s) to detect both of our models at sufficiently high S/N to distinguish between them for hypothetical events within the Local Group. The prospects for detection will be better with future missions. For example, the proposed Athena/X-IFU instrument could detect our delayed

  15. K-Shell Photoionization of Nickel Ions Using R-Matrix

    Science.gov (United States)

    Witthoeft, M. C.; Bautista, M. A.; Garcia, J.; Kallman, T. R.; Mendoza, C.; Palmeri, P.; Quinet, P.

    2011-01-01

    We present R-matrix calculations of photoabsorption and photoionization cross sections across the K edge of the Li-like to Ca-like ions stages of Ni. Level-resolved, Breit-Pauli calculations were performed for the Li-like to Na-like stages. Term-resolved calculations, which include the mass-velocity and Darwin relativistic corrections, were performed for the Mg-like to Ca-like ion stages. This data set is extended up to Fe-like Ni using the distorted wave approximation as implemented by AUTOSTRUCTURE. The R-matrix calculations include the effects of radiative and Auger dampings by means of an optical potential. The damping processes affect the absorption resonances converging to the K thresholds causing them to display symmetric profiles of constant width that smear the otherwise sharp edge at the K-shell photoionization threshold. These data are important for the modeling of features found in photoionized plasmas.

  16. Discovery of an ionized Fe-K edge in the z=3.91 Broad Absorption Line Quasar APM 08279+5255 with XMM-Newton

    CERN Document Server

    Hasinger, G; Komossa, S

    2002-01-01

    Recent XMM-Newton observations of the high-redshift, lensed, broad absorption line (BAL) quasi-stellar object APM 08279+5255, one of the most luminous objects in the universe, allowed the detection of a high column density absorber ($N_H \\approx 10^{23}$ cm$^{-2}$) in the form of a K-shell absorption edge of significantly ionized iron (Fe XV - XVIII) and corresponding ionized lower-energy absorption. Our findings confirm a basic prediction of phenomenological geometry models for the BAL outflow and can constrain the size of the absorbing region. The Fe/O abundance of the absorbing material is significantly higher than solar (Fe/O = 2-5), giving interesting constraints on the gas enrichment history in the early Universe.

  17. Production and Decay of Atomic K-Shell Vacancy States

    Science.gov (United States)

    Gorczyca, Tom; Hasoglu, M. F.; Nikolic, D.; McLaughlin, B. M.; Chen, M. H.; Manson, S. T.; Badnell, N. R.

    2008-05-01

    K-shell photoabsorption calculations are important for a variety of astrophysical processes, in particular, determining the elemental abundances of the interstellar medium from observed X-ray absorption spectra. Previously, we performed reliable K-shell photoabsorption calculations for oxygen and neon ions that were used to determine elemental abundances from observed X-ray binary emissions. Here, we have executed detailed R-matrix calculations for carbon ions, where we have included both Auger broadening and relaxation effects by using an optical potential and pseudoorbitals with the necessary pseudoresonance elimination respectively. Also of astrophysical importance, especially for determining the charge-state distribution following K-shell excitation and/or ionization, is the competition between fluorescence (ejection of a photon, no charge change) and Auger decay (ejection of an electron, ionic charge change of +1). Our recent investigations on the accuracy of the existing 1s-vacancy fluorescence and Auger data base have revealed numerous deficiencies in that compilation. Those data were determined from configuration average, non-relativistic, singly-charged atomic physics calculations and were then scaled up through Z=30 for all isoelectronic sequences through the iron peak elements. We demonstrate the significance of including properly such physical effects as correct configuration averaging, semi-relativistic (i.e., spin-orbit) effects, and configuration interaction. Most recently, we have performed calculations that revealed anomalous behavior of the radiative and Auger rates, and the associated fluorescence yields, of the six electron K-shell vacancy isoelectronic sequence, exhibited as non-monotonic behavior as a function of Z. This behavior is explained in terms of an accidental degeneracy, an avoided-crossing of two nearly-degenerate spin-orbit coupled states. Consequently, we have demonstrated that, in general, even interpolation of rates and yields

  18. K-shell ionization by antiprotons

    Energy Technology Data Exchange (ETDEWEB)

    Mehler, G.; Mueller, B.; Greiner, W.; Soff, G.

    1987-08-01

    We present calculations for the impact-parameter dependence of K-shell ionization rates in p-bar-Cu and in p-bar-Ag collisions at various projectile energies. We show that the effect of the attractive Coulomb potential on the Rutherford trajectory and the antibinding effect caused by the negative charge of the antiproton result in a considerable increase of the ionization probability. Total ionization cross sections for proton and antiproton projectiles are compared with each other and with experimental ionization cross sections for protons.

  19. Determination of experimental K-shell fluorescence yield for potassium and calcium compounds

    Indian Academy of Sciences (India)

    E Tiraşoğlu; Ö Söğüt

    2008-03-01

    K-shell fluorescence yields were experimentally determined for potassium and calcium compounds using a Si(Li) X-ray detector system (FWHM=5.96 keV at 160 eV). The samples were excited by 5.96 keV photons produced by a 55Fe radioisotope source. The experimental values are systematically lower than the theoretical values.

  20. Measurement of K Shell Photoelectric Cross Sections at a K Edge--A Laboratory Experiment

    Science.gov (United States)

    Nayak, S. V.; Badiger, N. M.

    2007-01-01

    We describe in this paper a new method for measuring the K shell photoelectric cross sections of high-Z elemental targets at a K absorption edge. In this method the external bremsstrahlung (EB) photons produced in the Ni target foil by beta particles from a weak[superscript 90]Sr-[superscript 90]Y beta source are passed through an elemental target…

  1. Model uncertainties of local-thermodynamic-equilibrium K-shell spectroscopy

    Science.gov (United States)

    Nagayama, T.; Bailey, J. E.; Mancini, R. C.; Iglesias, C. A.; Hansen, S. B.; Blancard, C.; Chung, H. K.; Colgan, J.; Cosse, Ph.; Faussurier, G.; Florido, R.; Fontes, C. J.; Gilleron, F.; Golovkin, I. E.; Kilcrease, D. P.; Loisel, G.; MacFarlane, J. J.; Pain, J.-C.; Rochau, G. A.; Sherrill, M. E.; Lee, R. W.

    2016-09-01

    Local-thermodynamic-equilibrium (LTE) K-shell spectroscopy is a common tool to diagnose electron density, ne, and electron temperature, Te, of high-energy-density (HED) plasmas. Knowing the accuracy of such diagnostics is important to provide quantitative conclusions of many HED-plasma research efforts. For example, Fe opacities were recently measured at multiple conditions at the Sandia National Laboratories Z machine (Bailey et al., 2015), showing significant disagreement with modeled opacities. Since the plasma conditions were measured using K-shell spectroscopy of tracer Mg (Nagayama et al., 2014), one concern is the accuracy of the inferred Fe conditions. In this article, we investigate the K-shell spectroscopy model uncertainties by analyzing the Mg spectra computed with 11 different models at the same conditions. We find that the inferred conditions differ by ±20-30% in ne and ±2-4% in Te depending on the choice of spectral model. Also, we find that half of the Te uncertainty comes from ne uncertainty. To refine the accuracy of the K-shell spectroscopy, it is important to scrutinize and experimentally validate line-shape theory. We investigate the impact of the inferred ne and Te model uncertainty on the Fe opacity measurements. Its impact is small and does not explain the reported discrepancies.

  2. K-shell Photoabsorption of Oxygen Ions

    CERN Document Server

    García, J; Bautista, M A; Gorczyca, T W; Kallman, T R; Palmeri, P

    2004-01-01

    Extensive calculations of the atomic data required for the spectral modelling of the K-shell photoabsorption of oxygen ions have been carried out in a multi-code approach. The present level energies and wavelengths for the highly ionized species (electron occupancies 2 4, lack of measurements, wide experimental scatter, and discrepancies among theoretical values are handicaps in reliable accuracy assessments. The radiative and Auger rates are expected to be accurate to 10% and 20%, respectively, except for transitions involving strongly mixed levels. Radiative and Auger dampings have been taken into account in the calculation of photoabsorption cross sections in the K-threshold region, leading to overlapping lorentzian shaped resonances of constant widths that cause edge smearing. The behavior of the improved opacities in this region has been studied with the XSTAR modelling code using simple constant density slab models, and is displayed for a range of ionization parameters.

  3. Double K-shell ionization probability in 54Mn

    Science.gov (United States)

    Hindi, M.; White, C.; Kozub, R.

    2003-07-01

    We have measured the probability of double K-shell vacancy production in the electron capture decay of 54Mn to the 835-keV level of 54Cr. The probability was deduced from the number of triple coincidences among the Cr hypersatellite and satellite x rays emitted in filling the double vacancy and the 835-keV γ ray. The probability of double K-shell vacancy production per K-shell electron capture (PKK) was found to be (2.3+0.8-0.5)×10-4. Comparisons to previous experimental results and theoretical calculations are discussed.

  4. K-shell ionization in relativistic ion-atom collisions

    Energy Technology Data Exchange (ETDEWEB)

    Mehler, G.; Soff, G.; Rumrich, K.; Greiner, W.

    1989-08-01

    We present calculations of K-shell ionization probabilities in asymmetric ion-atom collisions at relativistic velocities of the projectile. The time-dependent Dirac equation is represented as a system of coupled differential equations. The transition probabilities are determined using the coordinate space method. This necessitates an extension of the angular momentum coupling compared with nonrelativistic collision systems. Effects of the relativistic projectile motion on the coupling matrix elements and their consequences on K-shell ionization are discussed. (orig.).

  5. K-shell ionization in relativistic ion-atom collisions

    Energy Technology Data Exchange (ETDEWEB)

    Mehler, G.; Rumrich, K.; Greiner, W.; Soff, G.

    1989-02-01

    We present calculations of K-shell ionization probabilities in asymmetric ion-atom collisions at relativistic velocities of the projectile. The time-dependent Dirac equation is represented as a system of coupled differential equations. The transition probabilities are determined using the coordinate space method. This necessitates an extension of the angular momentum coupling compared with nonrelativistic collision systems. Effects of the relativistic projectile motion on the coupling matrix elements and their consequences on K-shell ionization are discussed.

  6. New expression for the K-shell ionization

    CERN Document Server

    Santos, J P; Parente, F

    2011-01-01

    A new expression for the total K-shell ionization cross section by electron impact based on the relativistic extension of the binary encounter Bethe (RBEB) model, valid from ionization threshold up to relativistic energies, is proposed. The new MRBEB expression is used to calculate the K-shell ionization cross sections by electron impact for the selenium atom. Comparison with all, to our knowledge, available experimental data shows good agreement.

  7. Fast asynchronous updating algorithms for k-shell indices

    Science.gov (United States)

    Lee, Yan-Li; Zhou, Tao

    2017-09-01

    Identifying influential nodes in networks is a significant and challenging task. Among many centrality indices, the k-shell index performs very well in finding out influential spreaders. However, the traditional method for calculating the k-shell indices of nodes needs the global topological information, which limits its applications in large-scale dynamically growing networks. Recently, Lü et al. [Nature Commun. 7 (2016) 10168] proposed a novel asynchronous algorithm to calculate the k-shell indices, which is suitable to deal with large-scale growing networks. In this paper, we propose two algorithms to select nodes and update their intermediate values towards the k-shell indices, which can help in accelerating the convergence of the calculation of k-shell indices. The former algorithm takes into account the degrees of nodes while the latter algorithm prefers to choose the node whose neighbors' values have been changed recently. We test these two methods on four real networks and four artificial networks. The results suggest that the two algorithms can respectively reduce the convergence time up to 75.4% and 92.9% in average, compared with the original asynchronous updating algorithm.

  8. Electromagnetic absorption properties of graphene/Fe nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yujin, E-mail: chenyujin@hrbeu.edu.cn [Key Laboratory of In-Fiber Integrated Optics, Ministry Education of China, College of Science, Harbin Engineering University, Harbin 150001 (China); Lei, Zhenyu; Wu, Hongyu [Key Laboratory of In-Fiber Integrated Optics, Ministry Education of China, College of Science, Harbin Engineering University, Harbin 150001 (China); Zhu, Chunling [College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Gao, Peng, E-mail: gaopeng@hrbeu.edu.cn [College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Ouyang, Qiuyun; Qi, Li-Hong [Key Laboratory of In-Fiber Integrated Optics, Ministry Education of China, College of Science, Harbin Engineering University, Harbin 150001 (China); Qin, Wei, E-mail: qinwei@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2013-09-01

    Graphical abstract: - Highlights: • Graphene/Fe nanocomposites were prepared by a facile and green method. • 10 nm Fe nanoparticles were uniformly dispersed over the surface of the graphene sheets. • The nanocomposites exhibited strong electromagnetic wave absorption properties. - Abstract: Graphene (G)/Fe nanocomposites with ferromagnetic properties at room temperature were fabricated by a facile and green method. Transmission electron microscope (TEM) and atomic force microscopy (AFM) amylases reveal that the α-Fe nanoparticles with a diameter of only about 10 nm were uniformly dispersed over the surface of the graphene sheets. Compared with other magnetic materials and the graphene, the nanocomposites exhibited significantly enhanced electromagnetic absorption properties. The maximum reflection loss to electromagnetic wave was up to −31.5 dB at a frequency of 14.2 GHz for G/Fe nanocomposites with a thickness of 2.5 mm. Importantly, the addition of the nanocomposites is only about 20 wt.% in the matrix. The enhanced mechanism is discussed and it is related to high surface areas of G/Fe nanocomposites, interfacial polarizations between graphene and iron, synergetic effect and efficient dispersity of magnetic NPs.

  9. Constraining FeLoBAL outflows from absorption line variability

    CERN Document Server

    McGraw, S M; Hamann, F W; Capellupo, D M; Gallagher, S C; Brandt, W N

    2015-01-01

    FeLoBALs are a rare class of quasar outflows with low-ionization broad absorption lines (BALs), large column densities, and potentially large kinetic energies that might be important for `feedback' to galaxy evolution. In order to probe the physical properties of these outflows, we conducted a multiple-epoch, absorption line variability study of 12 FeLoBAL quasars spanning a redshift range between 0.7 and 1.9 over rest frame time-scales of approximately 10 d to 7.6 yr. We detect absorption line variability with greater than 8 sigma confidence in 3 out of the 12 sources in our sample over time-scales of 0.6 to 7.6 yr. Variable wavelength intervals are associated with ground and excited state Fe II multiplets, the Mg II 2796, 2803 doublet, Mg I 2852, and excited state Ni II multiplets. The observed variability along with evidence of saturation in the absorption lines favors transverse motions of gas across the line of sight (LOS) as the preferred scenario, and allows us to constrain the outflow distance from th...

  10. K-shell to K-shell charge transfer in collisions of bare decelerated S ions with Ar

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, M.; Justiniano, E.; Konrad, J.; Schuch, R.; Salin, A.

    1987-05-14

    The impact parameter dependence of the single and double K-shell to K-shell charge transfer probabilities was studied by measuring triple coincidences between two K x-rays and the scattered projectiles for 16 MeV S W -Ar. It was found that the data are internally consistent with independent electron assumptions, but cannot be reproduced by different calculations of single electron transfer probabilities applying the independent electron model. Also a calculation of double K-vacancy transfer including electron correlations which described the HeS -He charge transfer probabilities well, is not in good agreement with the present data. The data allow a more sensitive test of various calculations on K to K charge transfer than recent experimental studies on collision systems with hydrogen-like projectiles.

  11. Measurements of K Shell Emission of Highly Charged Ions with the XRS at EBIT

    Science.gov (United States)

    Porter, F. Scott; Beiersdorfer, P.; Boyce, K.; Brown, G. V.; Chen, H.; Kahn, S.; Kelley, R.; Kilbourne, C. A.

    2004-01-01

    The XRS/EBIT is a 32 channel microcalorimeter spectrometer operating at the electron beam ion trap (EBIT) facility at Lawrence Livermore National Laboratory. The system contains a flight candidate detector array from the XRS instrument for the Astro-E2 mission. The detector array in the XRS/EBIT is functionally identical to the flight array integrated into the XRS instrument and benefits from the enormous amount of calibration data from the XRS program. Since the XRSEBIT was upgraded with the new detector array in October 2003, the system has been used for a number of experiments including a survey of the K shell emission from He-like and H-like O, Ne, Ar, Fe, Ni and Kr as well as for L shell emission to measure the 3C/3D line ratio in Ni. Here we present some basic operational parameters of the instrument as well as direct excitation and simulated maxwellian spectra of He-like and E-like Fe. We show that the XRS instrument can resolve the Lyal and Lya2 lines from each other as well as from the dielectronic recombination satellites in thermal H-like Fe. We also show exactly how well the XRS instrument on Astro-E2 will resolve the thermal He-like triplet in collisionally excited Fe. This work was funded under NASA's Research Opportunities in Space Science program.

  12. NO and O2 absorption in FeII(EDTA) solutions

    NARCIS (Netherlands)

    Gambardella, Francesca

    2005-01-01

    BiodeNOx is an industrial process for the removal of nitrogen monoxide from waste gases. The process consist in a chemical absorption in Fe(EDTA) solutions coupled with a biological regeneration. In order to optimize this process, the absorptions of nitrogen monoxide and oxygen in FeII(EDTA) solutio

  13. [Light Absorption Characteristics of FeS2-Fe1-xS Heterostructures Synthesized under Hydrothermal Conditions].

    Science.gov (United States)

    Liu, Jia; Huang, Fei; Meng, Lin; Yu, Hao-ran; Chen, Ying-hua

    2015-05-01

    Fe-S series, especially FeS2 and Fe1-x S is the main component of crustal rocks as important metal sulphides. Pyrite (FeS2) shows a promising vision in solar cell materials for its high absorption coefficient and suitable band gap. Predecessors have done some researches on the photovoltaic properties of Fe-S series under different conditions. However, little researches have been done on the coexisted sulphide of FeS2 and Fe1-xS. FeS2 and Fe1-xS often appear as symbiotically due to their similar formation conditions. So the study on the optical absorption characteristics of FeS2 and Fe1-xS are of important significance. In order to study the optical absorption characteristics of FeS2-Fe1-xS heterostructures, using the SEM and XRD to characterize the morphology, composition and structure, respectively. The results show that the samples were cubic pyrite with a certain amount of pyrhotite (Fe1-xS). The crystal partical size was between 5 and 10 nm. Measurement of the absorption spectrum was performed using Cary 500 UV-Vis-NIR spectrophotoineter, acquiring the results of 1 860-1 889 nm, and the absorption peak in 1879nm. According to the band gap (eV) formula, the band gap value is calculated to be 0. 657 8 eV. The extreme electrical-to-optical conversion efficiency achieved was about 15%. By the first principles, we analysed the reason of the changing of the band gap value, and then compared the result with previous one. The internal structure of mineral is the important factor affecting the photoelectric conversion. The light absorption characteristics of FeS2-Fel-xS heterostructures synthesized under hydrothermal conditions is better than the characteristics from natural pyrite with defects of Co and Ni. The heterostructures can improve the electrical-to-optical conversion efficiency and provide scientific basis for the absorption characteristics research of Fe-S series materials.

  14. NaFeEDTA Fortified Soy Sauce Showed Higher Iron Absorption Rate in Chinese Females

    Institute of Scientific and Technical Information of China (English)

    JUN-SHENG HUO; XIAO-GUANG YANG; JIAN-HUA PIAO; JUN-QUAN GAO; HONG MIAO; Bo YU; CHENG-QIAN LU; JUN-SHI CHEN

    2007-01-01

    Objective NaFeEDTA was considered as a promising iron fortificant for controlling iron deficiency anemia. Soy sauce is a suitable food carrier for iron fortification and is a popular condiment in China. Iron absorption rates of NaFeEDTA and FeSO4were observed and compared in adult female subjects. Methods The stable isotope tracer method was used in Chinese females consuming a typical Chinese diet. Ten healthy young Chinese women were selected as subjects in the 15-day study. A plant-based diet was used based on the dietary pattern of adult women in the 1992 National Nutrition Survey. Six milligram of54Fe in 54FeSO4 soy sauce and 3 mg 58Fe in Na58FeEDTA soy sauce were given to the same subjects in two days. Food samples and fecal samples were collected and analyzed. Results Iron absorption rates of NaFeEDTA and FeSO4 were 10.51%±2.83and 4.73%±2.15 respectively. The 58Fe (NaFeEDTA) absorption was significantly higher than that of 54Fe (FeSO4) (P<0.01).The iron absorption rate from NaFeEDTA was 1.2 times higher than that from FeSO4 in Chinese adult women consuming a typical Chinese diet. Conclusion The higher absorption rate of NaFeEDTA suggested that NaFeEDTA would be a better iron fortificant used in soy sauce for the controlling of iron deficiency anemia in China.

  15. Experimental K-shell fluorescence yield of silicon

    Science.gov (United States)

    Campbell, J. L.; Cauchon, G.; Lakatos, T.; Lépy, M.-C.; McDonald, L.; Papp, T.; Plagnard, J.; Stemmler, P.; Teesdale, W. J.

    1998-11-01

    The K-shell fluorescence yield of silicon 0953-4075/31/21/009/img11 was determined by evaluating the escape-peak-to-parent-peak intensity ratio for monoenergetic x-rays in the energy range 2-9 keV and for manganese K x-rays from an 0953-4075/31/21/009/img12 radioactive source, using an Si(Li) detector. An order of magnitude improvement in low-energy tailing achieved during the last decade made possible a significant improvement relative to earlier Si(Li) experiments of this type. A detailed analysis of the spectra was performed, including the double-photoionization satellites of the escape peaks. Depending upon the choice of attenuation coefficient, the result of 0953-4075/31/21/009/img13 is 0.050 or 0.052, with approximately 0953-4075/31/21/009/img14 uncertainty in either case. This overall result is close to the semi-empirical fit values both of Krause and of Bambynek, but is significantly higher than the recent fitted values of Hubbell et al.

  16. Unusual continuous dual absorption peaks in Ca-doped BiFeO3 nanostructures for broadened microwave absorption

    Science.gov (United States)

    Li, Zhong-Jun; Hou, Zhi-Ling; Song, Wei-Li; Liu, Xing-Da; Cao, Wen-Qiang; Shao, Xiao-Hong; Cao, Mao-Sheng

    2016-05-01

    Electromagnetic absorption materials have received increasing attention owing to their wide applications in aerospace, communication and the electronics industry, and multiferroic materials with both polarization and magnetic properties are considered promising ceramics for microwave absorption application. However, the insufficient absorption intensity coupled with the narrow effective absorption bandwidth has limited the development of high-performance multiferroic materials for practical microwave absorption. To address such issues, in the present work, we utilize interfacial engineering in BiFeO3 nanoparticles via Ca doping, with the purpose of tailoring the phase boundary. Upon Ca-substitution, the co-existence of both R3c and P4mm phases has been confirmed to massively enhance both dielectric and magnetic properties via manipulating the phase boundary and the destruction of the spiral spin structure. Unlike the commonly reported magnetic/dielectric hybrid microwave absorption composites, Bi0.95Ca0.05FeO3 has been found to deliver unusual continuous dual absorption peaks at a small thickness (1.56 mm), which has remarkably broadened the effective absorption bandwidth (8.7-12.1 GHz). The fundamental mechanisms based on the phase boundary engineering have been discussed, suggesting a novel platform for designing advanced multiferroic materials with wide applications.Electromagnetic absorption materials have received increasing attention owing to their wide applications in aerospace, communication and the electronics industry, and multiferroic materials with both polarization and magnetic properties are considered promising ceramics for microwave absorption application. However, the insufficient absorption intensity coupled with the narrow effective absorption bandwidth has limited the development of high-performance multiferroic materials for practical microwave absorption. To address such issues, in the present work, we utilize interfacial engineering in BiFeO3

  17. Double K-shell vacancy production in the electron capture decay of 139Ce

    Science.gov (United States)

    Hindi, M. M.; Kozub, R. L.

    1991-02-01

    The probability of double K-shell vacancy production in the electron capture decay of 139Ce to the 166-keV level of 139La has been investigated. Triple coincidences between the 166-keV gamma ray, the La satellite Kα x ray, and the La hypersatellite Kα x ray were measured using two intrinsic Ge detectors. We looked for the sum of two of the three radiations in one detector in coincidence with the third radiation in the other detector. The probability of double K-shell vacancy production per K-shell electron capture (PKK) was found to be (2.0+/-1.6)×10-6. From this and the known PKK for 131Cs we estimate a probability for zero K-shell vacancy production (shakedown) per K-shell electron capture of <~2.4×10-5 for 139Ce.

  18. The local structure and optical absorption characteristic investigation on Fe doped TiO2 nanoparticles

    CERN Document Server

    Zhao, Tianxing; Huang, Junheng; He, Jinfu; Liu, Qinghua; Pan, Zhiyun; Wu, Ziyu

    2014-01-01

    The local structures and optical absorption characteristic of Fe doped TiO2 nanoparticles synthesized by the sol-gel method were characterized by X-ray Diffraction (XRD), X-ray absorption fine structure spectroscopy (XAFS) and UV-Vis absorption spectroscopy (UV-Vis). XRD patterns show that all Fe-doped TiO2 samples have the characteristic anatase structure. Accurate Fe and Ti K-edge EXAFS analysis further reveal that all Fe atoms replace Ti atoms in the anatase lattice. The analysis of UV-Vis data shows a red shift to the visible range. According to the above results, we claim that substitutional Fe atoms lead to the formation of structural defects and new intermediate energy levels appear, narrowing the band gap and extending the optical absorption edge towards the visible region.

  19. K-shell auger decay of atomic oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Stolte, W.C.; Lu, Y.; Samson, J.A.R. [Univ. of Nebraska, Lincoln, NE (United States)] [and others

    1997-04-01

    The aim of the present research is to understand the interaction between the ejected photoelectron and Auger electron produced by the Auger decay of a 1s hole in atomic oxygen, and to understand the influence this interaction has on the shape of the ionization cross sections. To accomplish this the authors have measured the relative ion yields (ion/photon) in the vicinity of the oxygen K-shell (525 - 533 eV) for O{sup +} and O{sup 2+}. The measurements were performed at the ALS on beamline, 6.3.2. The atomic oxygen was produced by passing molecular oxygen through a microwave-driven discharge. A Rydberg analysis of the two series leading to the [1s]2s{sup 2}2p{sup 4}({sup 4}P) and [1s]2s{sup 2}2p{sup 4}({sup 2}P) limits were obtained. This analysis shows some differences to the recently published results by Menzel et al. The energy position of the main 1s{sup 1}2s{sup 2}2p{sup 5}({sup 3}P) resonance differs by approximately 1 eV from the authors value, all members of the ({sup 2}P)np series differ by 0.3 eV, but the members of the ({sup 4}P)np series agree. The molecular resonance at 530.5 eV and those between 539 eV and 543 eV, measured with the microwave discharge off show identical results in both experiments.

  20. Unusual continuous dual absorption peaks in Ca-doped BiFeO3 nanostructures for broadened microwave absorption.

    Science.gov (United States)

    Li, Zhong-Jun; Hou, Zhi-Ling; Song, Wei-Li; Liu, Xing-Da; Cao, Wen-Qiang; Shao, Xiao-Hong; Cao, Mao-Sheng

    2016-05-21

    Electromagnetic absorption materials have received increasing attention owing to their wide applications in aerospace, communication and the electronics industry, and multiferroic materials with both polarization and magnetic properties are considered promising ceramics for microwave absorption application. However, the insufficient absorption intensity coupled with the narrow effective absorption bandwidth has limited the development of high-performance multiferroic materials for practical microwave absorption. To address such issues, in the present work, we utilize interfacial engineering in BiFeO3 nanoparticles via Ca doping, with the purpose of tailoring the phase boundary. Upon Ca-substitution, the co-existence of both R3c and P4mm phases has been confirmed to massively enhance both dielectric and magnetic properties via manipulating the phase boundary and the destruction of the spiral spin structure. Unlike the commonly reported magnetic/dielectric hybrid microwave absorption composites, Bi0.95Ca0.05FeO3 has been found to deliver unusual continuous dual absorption peaks at a small thickness (1.56 mm), which has remarkably broadened the effective absorption bandwidth (8.7-12.1 GHz). The fundamental mechanisms based on the phase boundary engineering have been discussed, suggesting a novel platform for designing advanced multiferroic materials with wide applications.

  1. Microwave absorption properties of FeCo-coated carbon fibers with varying morphologies

    Science.gov (United States)

    Wan, Yizao; Xiao, Jian; Li, Chunzhi; Xiong, Guangyao; Guo, Ruisong; Li, Lili; Han, Ming; Luo, Honglin

    2016-02-01

    Hybridizing carbon materials with magnetic metals and oxides has attracted much attention for enhanced microwave absorption. In this study, a magnetic Fe-Co alloy was coated on the surface of carbon fibers (FeCo@CFs) by electrodeposition. For the first time, different Fe-Co coating morphologies (thin plate, irregular particle, and pyramid) were obtained by adjusting the plating temperature. The morphology, structure, magnetic properties, and complex permittivity and permeability of the FeCo@CFs were determined as a function of plating temperature. Results show that the FeCo@CFs with different coating morphologies exhibit different magnetic properties and complex permittivity. The FeCo@CFs with plate-like morphology demonstrate the best absorption performance. It has been shown that the absorption of FeCo@CFs can be controlled by adjusting the morphology of Fe-Co coating, which provides a new and effective way to endow Fe-Co-coated carbon fibers with good microwave absorption properties.

  2. An Empirical Formula of Atomic K-Shell Ionization Cross Sections by Electron Impact

    Institute of Scientific and Technical Information of China (English)

    唐昶环; 安竹; 罗正明; 范晓强

    2001-01-01

    An empirical formula is proposed to describe the K-shell ionization cross sections by electron impact over a wide range of atomic numbers and overvoltages U (the ratio between the electron incident energy and the bindingenergy of the electrons in the K-shell). The study is based on the analysis of existing experimental data of K-shell ionization cross sections. The expression shows the results in good agreement with the data for Z<6 atoms as well as for 6<Z<79.

  3. Double K-shell vacancy production in the electron capture decay of 125I

    Science.gov (United States)

    Hindi, M. M.; Kozub, R. L.

    1992-03-01

    We have measured the probability of double K-shell vacancy production in the electron capture decay of 125I to the 35-keV level of 125Te. The probability was deduced from the number of triple coincidences between the Te hypersatellite and satellite x rays produced in filling the double vacancy, and the subsequent normal x ray accompanying the K internal conversion of the 35-keV level. The probability of double K-shell vacancy production per K-shell electron capture (PKK) was found to be (1.35+/-0.15)×10-5.

  4. K-shell transitions in L-shell ions with the EBIT calorimeter spectrometer

    Science.gov (United States)

    Hell, Natalie; Brown, Greg V.; Wilms, Jörn; Beiersdorfer, Peter; Kelley, Richard L.; Kilbourne, Caroline A.; Porter, F. Scott

    2016-10-01

    With the large improvement in effective area of Astro-H's micro-calorimeter soft X-ray spectrometer (SXS) over grating spectrometers, high-resolution X-ray spectroscopy with good signal to noise will become more commonly available, also for faint and extended sources. This will result in a range of spectral lines being resolved for the first time in celestial sources, especially in the Fe region. However, a large number of X-ray line energies in the atomic databases are known to a lesser accuracy than that expected for Astro-H/SXS, or have no known uncertainty at all. To benchmark the available calculations, we have therefore started to measure reference energies of K-shell transition in L-shell ions for astrophysically relevant elements in the range 11ion trap coupled with the NASA/GSFC EBIT calorimeter spectrometer (ECS). The ECS has a resolution of ~5 e V, i.e., similar to Astro-H/SXS and Chandra/HETG. A comparison to crystal spectra of lower charge states of sulfur with ~0.6 e V resolution shows that the analysis of spectra taken at ECS resolution allows to determine the transition energies of the strongest components.

  5. Molar Absorptivity and Concentration-Dependent Quantum Yield of Fe(II) Photo-Formation for the Aqueous Solutions of Fe(III)-Dicarboxylate Complexes

    Science.gov (United States)

    Hitomi, Y.; Arakaki, T.

    2009-12-01

    Redox cycles of iron in the aquatic environment affect formation of reactive oxygen species such as hydrogen peroxide and hydroxyl radicals, which in turn determines lifetimes of many organic compounds. Although aqueous Fe(III)-dicarboxylate complexes are considered to be important sources of photo-formed Fe(II), molar absorptivity and quantum yield of Fe(II) formation for individual species are not well understood. We initiated a study to characterize Fe(II) photo-formation from Fe(III)-dicarboxylates with the concentration ranges that are relevant to the natural aquatic environment. The Visual MINTEQ computer program was used to calculate the equilibrium concentrations of individual Fe(III)-dicarboxylate species. The molar absorptivity of Fe(III)-dicarboxylate species was obtained by UV-VIS spectrophotometer, and the product of the quantum yield and the molar absorptivity of Fe(III)-dicarboxylate species were obtained from photochemical experiments. These experimental data were combined with the calculated equilibrium Fe(III)-dicarboxylate concentrations to determine individual molar absorptivity and quantum yield of Fe(II) photo-formation for a specific Fe(III)-dicarboxylate species. We used initial concentrations of less than 10 micromolar Fe(III) to study the photochemical formation of Fe(II). Dicarboxylate compounds studied include oxalate, malonate, succinate, malate, and phthalate. We report molar absorptivity and concentration-dependent quantum yields of Fe(II) photo-formation of individual Fe(III)-dicarboxylates.

  6. Erythrocyte incorporation and absorption of 58Fe in premature infants treated with erythropoietin.

    Science.gov (United States)

    Widness, J A; Lombard, K A; Ziegler, E E; Serfass, R E; Carlson, S J; Johnson, K J; Miller, J E

    1997-03-01

    We hypothesized that treatment of very low birth weight premature infants with r-HuEPO would increase erythrocyte incorporation and gastrointestinal absorption of iron. Infants with birth weights absorption of 58Fe was not different between the epo and placebo groups after both early dosing (30 +/- 22% versus 34 +/- 8%) and late dosing (32 +/- 9% versus 31 +/- 6%). Absorption of nonlabeled elemental iron and 58Fe were significantly correlated with one another. The percentage of the absorbed 58Fe dose incorporated into Hb was not different between groups. We conclude that, although erythropoietin treatment stimulates erythrocyte iron incorporation in premature infants, it has no effect on iron absorption at the r-HuEPO dose studied.

  7. Electromagnetic Wave Absorption Property of Graphene with FeO4 Nanoparticles.

    Science.gov (United States)

    Yang, Cheng; Dai, Shenglong; Zhang, Xiaoyan; Zhao, Tianyu; Yan, Shaojiu; Zhao, Xiuying

    2016-02-01

    Nanomaterials consisting of various ratios of Fe3O4 and graphene (defined C-Fe3O4/GR) were pre- pared by an in situ coordination complex hydro-thermal synthesis method. The structure and morphology of the nanomaterials C-Fe3O4/GR obtained were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). It was found that the Fe3O4 nanoparticles distributed on the surfaces of graphene, and had a spinel structure and a uniform chemical phase when the weight ratios of Fe3O4 to graphene oxide (GO) were 9:1 or 9:2. It was suggested that GO had been successfully reduced to graphene and the Fe3O4 nanoparticles were chemically bonded to graphene. The SQUID vibrating sample magnetometer (SQUID-VSM) indicated that the maximum of the saturation magnetization was 83.6 emmicro g(-1) when the mass ratio of Fe3O4 to GO was 9:2. Electromagnetic wave absorption showed that the chemical compound of Fe3O4 and graphene had a better electromagnetic property than the mechanical blend of Fe3O4 and graphene (M-Fe3O4/GR). The C-Fe3O4/GR had a reflection loss larger than -10 dB in the frequency range 12.9-17.0 GHz for an absorber thickness of 3 mm, and a maximum reflection loss of -12.3 dB at 14.8 GHz and a maximum reflection loss of -31.2 dB at 10.5 GHz for an absorber thickness of 10 mm. Theoretical analysis showed that the electromagnetic wave absorption behavior obeyed the quarter-wave principles. These results showed that the C-Fe3O4/GR nanomaterials can meet the requirements for some engineering applications, showing great application potential in electromagnetic wave absorption.

  8. Enhanced and broadband microwave absorption of flake-shaped Fe and FeNi composite with Ba ferrites

    Science.gov (United States)

    Li, Wangchang; Lv, Junjun; Zhou, Xiang; Zheng, Jingwu; Ying, Yao; Qiao, Liang; Yu, Jing; Che, Shenglei

    2017-03-01

    In order to achieve a broad bandwidth absorber at high frequency, the composites of M-type ferrite BaCo1.0Ti1.0Fe10O19 (BaM) with flaked carbonyl iron powders (CIP) and flaked Fe50Ni50 were prepared to optimize the surface impedance in broadband frequency, respectively. The diameter of the flaked carbonyl iron powders (CIP) and Fe50Ni50 is in the range of 5-10 μm and 10-20 μm and the thickness of the CIP and Fe50Ni50 is close to 200 nm and 400 nm, respectively. The complex permeability and permittivity show that the addition of BaM obviously reduces the values of real part of permittivity and imaginary part of the permeability which can enhance the matched-wave-impedance. The absorption bands less than -10 dB of CIP-BaM and FeNi-BaM absorber approach to 5.5 GHz (5.7-11.2 GHz) and 7 GHz (11-18 GHz) at 1.5 mm. However, the bands of CIP and FeNi are only 1.9 GHz (4.7-6.6 GHz) and 2.1 GHz (4.0-6.1 GHz). Hence, the electromagnetic match property is greatly improved by BaM ferrites, and this composite shows a broaden absorption band.

  9. Preparation and electromagnetic wave absorption properties of Sm2O3/α-Fe/Sm2Fe17Nx composites

    Science.gov (United States)

    Ye, Jinwen; Liu, Ying; Zhang, Jiao; Chen, Xianfu; Yao, Mingying

    2013-06-01

    Sm2O3/α-Fe/Sm2Fe17Nx composites were prepared in situ by hydrogenation-disproportionation-oxygen-desorption-recombination and nitrogen process, and their electromagnetic wave absorption properties were measured in the frequency range of 0.5-18 GHz. The result showed that saturation magnetization and coercivity of as-prepared powder with 25.3 wt% Sm2O3, 64.4 wt% α-Fe and 10.3 wt% Sm2Fe17N3 were 134.57 emu/g and 654.5 G, respectively. The dielectric constant of composites was low over the frequency range of 0.5-18 GHz, and their resonance frequencies were at a high frequency range. The resin composite of Sm2O3/α-Fe/Sm2Fe17N3 exhibited effective electromagnetic wave absorption (RL≤20 dB) in a frequency range 3-9 GHz, for absorber thickness ranging from 3 to 8 mm, respectively. A minimum reflection loss of -53 dB from the samples was observed at 7 GHz with an absorber thickness of 3.59 mm.

  10. Laboratory Measurement and Theoretical Modeling of K-shell X-ray Lines from Inner-shell Excited and Ionized Ions of Oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Gu, M; Schmidt, M; Beiersdorfer, P; Chen, H; Thorn, D B; Tr?bert, E; Behar, E; Kahn, S M

    2005-02-05

    We present high resolution laboratory spectra of K-shell X-ray lines from inner-shell excited and ionized ions of oxygen, obtained with a reflection grating spectrometer on the electron beam ion trap (EBIT-I) at the Lawrence Livermore National Laboratory. Only with a multi-ion model including all major atomic collisional and radiative processes, are we able to identify the observed K-shell transitions of oxygen ions from O III to O VI. The wavelengths and associated errors for some of the strongest transitions are given, taking into account both the experimental and modeling uncertainties. The present data should be useful in identifying the absorption features present in astrophysical sources, such as active galactic nuclei and X-ray binaries. They are also useful in providing benchmarks for the testing of theoretical atomic structure calculations.

  11. Preparation, electromagnetic and enhanced microwave absorption properties of Fe nanoparticles encapsulated in carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Xiaosi, E-mail: sci.xsqi@gzu.edu.cn [Physics Department, Guizhou University, Guiyang 550025 (China); Nanjing National Laboratory of Microstructures and Jiangsu Provincial Laboratory for NanoTechnology, Nanjing University, Nanjing 210093 (China); Xu, Jianle; Hu, Q. [Physics Department, Guizhou University, Guiyang 550025 (China); Zhong, Wei, E-mail: wzhong@nju.edu.cn [Nanjing National Laboratory of Microstructures and Jiangsu Provincial Laboratory for NanoTechnology, Nanjing University, Nanjing 210093 (China); Du, Youwei [Nanjing National Laboratory of Microstructures and Jiangsu Provincial Laboratory for NanoTechnology, Nanjing University, Nanjing 210093 (China)

    2015-08-15

    Graphical abstract: In the article, core/shell structured Fe/CNT hybrid have been synthesized over the hollow Fe{sub 2}O{sub 3} nanoparticles. Compared with those representative Fe/CNTs, the obtained Fe/CNT hybrid exhibits enhanced microwave-absorbing ability and can be used as light-weight microwave absorber. - Highlights: • The paper reports the synthesis of Fe/CNT hybrid directly over Fe{sub 2}O{sub 3} particles. • The RL value below −20 dB can be obtained in the 1.0–18 GHz frequency range. • The obtained Fe/CNT hybrid exhibits enhanced microwave absorption property. - Abstract: Using hollow Fe{sub 2}O{sub 3} particles as the catalyst, the core/shell structured Fe/carbon nanotube (CNT) hybrid could be synthesized by a chemical vapor deposition method without the hydrogen reduction process. Based on the obtained results, a possible growth mechanism of the Fe/CNT hybrid was discussed. And the investigations of electromagnetic and microwave absorption performances indicate that a minimum reflection loss (RL) value of the obtained sample is ca. −40.15 dB at 17.15 GHz with a matching thickness of 1.5 mm, and the RL value below −20 dB can be obtained in the whole frequency range (1.0–18 GHz) with the sample thickness varies from 1.3 to 10.0 mm. The results demonstrate that a simple and environment-friendly route has been proposed for the production of core/shell structured carbon nanohybrid. The obtained Fe/CNT hybrid exhibits excellent microwave absorption properties and has potential applications in thin thickness and light-weight microwave absorbers.

  12. Microwave absorption property of aligned MWCNT/Fe{sub 3}O{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Hekmatara, H., E-mail: hd_hekmat@yahoo.com [Department of Physics, Faculty of Science, Guilan University, Postal code 4193833697, Rasht (Iran, Islamic Republic of); Seifi, M., E-mail: m_seifi2000@yahoo.com [Department of Physics, Faculty of Science, Guilan University, Postal code 4193833697, Rasht (Iran, Islamic Republic of); Forooraghi, K., E-mail: kforooraghi@yahoo.com [Faculty of Electrical and Computer Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of)

    2013-11-15

    This study investigated the microwave absorption properties of magnetic modified multiwall carbon nanotubes (MWCNTs) with different alignments to the electric field (E vector) of the incident electromagnetic (EM) waves. MWCNTs were decorated with Fe{sub 3}O{sub 4} nanoparticles using the wet chemical method and the resulting MWCNT/Fe{sub 3}O{sub 4} was then used as a filler in a MWCNT/Fe{sub 3}O{sub 4}/epoxy resin composite at different weight-to-epoxy-resin ratios (2%, 5%, and 8%) with good uniformity and alignment. For each filler concentration, three samples were produced with different alignments of carbon nanotubes using the solution-casting method. For sample one, the nanotube axis (k) was parallel to the E vector of the EM wave, for sample two, k was perpendicular to E, and the third sample contained randomly oriented nanotubes. Magnetic MWCNTs were exposed to a 0.4 T magnetic field in the desired direction to achieve the desired alignment of carbon nanotubes in epoxy resin. Microwave absorption characterization of the considered ranging band (X-band) at all concentrations where the alignment of MWCNT/Fe{sub 3}O{sub 4} was parallel to the incident E vector showed increased absorption. Samples with a perpendicular alignment of MWCNT/Fe{sub 3}O{sub 4} to incident E had the lowest absorption. Samples containing 2 wt% and 8 wt% MWCNT/Fe{sub 3}O{sub 4} aligned parallel to E and had reflection losses exceeding 14.4 dB and 23.6 dB, respectively, over a 10–11 GHz range. The 5 wt% parallel aligned MWCNT/Fe{sub 3}O{sub 4} showed an absorbing peak of 27 dB and a bandwidth broadened to 1.2 GHz. - Highlights: • Multiwall carbon nanotube decorated with Fe{sub 3}O{sub 4} nanoparticles (MWCNT/Fe{sub 3}O{sub 4}) using the wet chemical method. • MWCNT/Fe{sub 3}O{sub 4} aligned in an epoxy resin matrix by being exposed to a weak magnetic field. • Aligned magnetic carbon nanotubes were parallel and perpendicular to the electric field of incident electromagnetic wave.

  13. Hydrogen absorption in Mg-Ni-Fe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lupu, D. (Inst. of Isotopic and Molecular Tech., Cluj-Napoca, Romania); Biris, A.; Indrea, E.; Aldea, N.; Bucur, R.V.; Morariu, M.

    1983-01-01

    The hydrogenation properties of the alloys of overall formula Mg/sub 2/Ni/sub 1-x/Fe/sub x/ (x less than or equal to 0.37) have been studied. In this range of composition multi-phase alloys were obtained containing Mg/sub 2/Ni, Mg and more or less finely dispersed Fe in different coordination as provided by the EXAFS technique and Moessbauer spectroscopy. There is no significant substitution of Ni by Fe atoms in the Mg/sub 2/Ni lattice. Two or three plateau-pressures are observed on the pressure-composition isotherms of the hydrides with the heats of formation in the range -18.4 to 20.4 kcal/mol H/sub 2/ (-77 to -85.4 kJ/mol H/sub 2/). The hydrides of the Fe-containing alloys show higher desorption rates of hydrogen compared to the pure Mg/sub 2/Ni hydride. 17 references, 5 figures, 1 table.

  14. Fe-substituted indium thiospinels: New intermediate band semiconductors with better absorption of solar energy

    Science.gov (United States)

    Chen, Ping; Chen, Haijie; Qin, Mingsheng; Yang, Chongyin; Zhao, Wei; Liu, Yufeng; Zhang, Wenqing; Huang, Fuqiang

    2013-06-01

    The indium thiospinels In2S3 and MgIn2S4 are promising host for the intermediated band (IB) photovoltaic materials due to their ideal band gap value. Here, the optical properties and electronic structure of Fe-doped In2S3 and MgIn2S4 have been investigated. All the Fe-substituted semiconductors exhibit two additional absorption bands at about 0.7 and 1.25 eV, respectively. The results of first-principles calculations revealed that the Fe substituted at the octahedral In site would introduce a partially filled IB into the band gap. Thanks to the formation of IB, the Fe-substituted semiconductors have the ability to absorb the photons with energies below the band gap. With the wide-spectrum absorption of solar energy, these materials possess potential applications in photovoltaic domain.

  15. Vanishing Absorption and Blueshifted Emission in FeLoBAL Quasars

    CERN Document Server

    Rafiee, Alireza; Hall, Patrick B; Galati, Natalee; Rogerson, Jesse; Ameri, Abtin

    2016-01-01

    We study the dramatic decrease in iron absorption strength in the iron low-ionization broad absorption line quasar SDSS J084133.15+200525.8. We report on the continued weakening of absorption in the prototype of this class of variable broad absorption line quasar, FBQS J140806.2+305448. We also report a third example of this class, SDSS J123103.70+392903.6; unlike the other two examples, it has undergone an increase in observed continuum brightness (at 3000~\\AA\\ rest-frame) as well as a decrease in iron absorption strength. These changes could be caused by absorber transverse motion or by ionization variability. We note that the \\mgii\\ and UV \\feii\\ lines in several FeLoBAL quasars are blueshifted by thousands of \\kms\\ relative to the \\Hb\\ emission line peak. We suggest that such emission arises in the outflowing winds normally seen only in absorption.

  16. Fast ranking influential nodes in complex networks using a k-shell iteration factor

    Science.gov (United States)

    Wang, Zhixiao; Zhao, Ya; Xi, Jingke; Du, Changjiang

    2016-11-01

    Identifying the influential nodes of complex networks is important for optimizing the network structure or efficiently disseminating information through networks. The k-shell method is a widely used node ranking method that has inherent advantages in performance and efficiency. However, the iteration information produced in k-shell decomposition has been neglected in node ranking. This paper presents a fast ranking method to evaluate the influence capability of nodes using a k-shell iteration factor. The experimental results with respect to monotonicity, correctness and efficiency have demonstrated that the proposed method can yield excellent performance on artificial and real world networks. It discriminates the influence capability of nodes more accurately and provides a more reasonable ranking list than previous methods.

  17. X-Ray Magnetic Dichroism of Antiferromagnet Fe2O3 : The Orientation of Magnetic Moments Observed by Fe 2p X-Ray Absorption Spectroscopy

    NARCIS (Netherlands)

    Kuiper, Pieter; Searle, Barry G.; Rudolf, Petra; Tjeng, L.H.; Chen, C.T.

    1993-01-01

    We report strong magnetic linear dichroism at the Fe L2,3 edge of the antiferromagnet Fe2O3 (hematite). The relative difference in absorption for light polarized parallel and perpendicular to the magnetic moment is as high as 40% at the Fe L2 edge. The spectra are in excellent agreement with

  18. Microwave absorption property of aligned MWCNT/Fe3O4

    Science.gov (United States)

    Hekmatara, H.; Seifi, M.; Forooraghi, K.

    2013-11-01

    This study investigated the microwave absorption properties of magnetic modified multiwall carbon nanotubes (MWCNTs) with different alignments to the electric field (E vector) of the incident electromagnetic (EM) waves. MWCNTs were decorated with Fe3O4 nanoparticles using the wet chemical method and the resulting MWCNT/Fe3O4 was then used as a filler in a MWCNT/Fe3O4/epoxy resin composite at different weight-to-epoxy-resin ratios (2%, 5%, and 8%) with good uniformity and alignment. For each filler concentration, three samples were produced with different alignments of carbon nanotubes using the solution-casting method. For sample one, the nanotube axis (k) was parallel to the E vector of the EM wave, for sample two, k was perpendicular to E, and the third sample contained randomly oriented nanotubes. Magnetic MWCNTs were exposed to a 0.4 T magnetic field in the desired direction to achieve the desired alignment of carbon nanotubes in epoxy resin. Microwave absorption characterization of the considered ranging band (X-band) at all concentrations where the alignment of MWCNT/Fe3O4 was parallel to the incident E vector showed increased absorption. Samples with a perpendicular alignment of MWCNT/Fe3O4 to incident E had the lowest absorption. Samples containing 2 wt% and 8 wt% MWCNT/Fe3O4 aligned parallel to E and had reflection losses exceeding 14.4 dB and 23.6 dB, respectively, over a 10-11 GHz range. The 5 wt% parallel aligned MWCNT/Fe3O4 showed an absorbing peak of 27 dB and a bandwidth broadened to 1.2 GHz.

  19. Molar Absorptivity and Quantum Yield of Fe(II) Photo-formation for the Aqueous Solutions of Fe(III)-Dicarboxylate Comlexes

    Science.gov (United States)

    Hitomi, Y.; Arakaki, T.

    2009-04-01

    Fe(III)/Fe(II) cycle in the environment affects formation of active oxygen species such as hydrogen peroxide and hydroxyl radicals, which in turn determines lifetimes of many organic compounds. Although aqueous Fe(III)-dicarboxylate complexes are considered to be an important source of photo-chemically formed Fe(II), molar absorptivity and quantum yield of Fe(II) formation for individual species are not well understood. The Visual MINTEQ computer program was used to calculate the equilibrium concentrations of individual Fe(III)-dicarboxylate species in the aqueous solutions of Fe(III)-dicarboxylate complexes. The molar absorptivity and the product of the quantum yield and the molar absorptivity of Fe(III)-dicarboxylate species were obtained by UV-VIS spectrophotometer and photochemical experiments, and these experimental data were combined with the calculated equilibrium Fe(III)-dicarboxylate concentrations to determine individual molar absorptivity and quantum yield of Fe(II) photo-formation for a specific Fe(III)-dicarboxylate species. Dicarboxylate compounds studied were oxalate, malonate, succinate, malate, and phthalate.

  20. Anomalous non-resonant microwave absorption in SmFeAs(O,F) polycrystalline sample

    Energy Technology Data Exchange (ETDEWEB)

    Onyancha, R.B., E-mail: 08muma@gmail.com [Department of Physics, College of Science, Engineering and Technology, University of South Africa, Johannesburg, 1710 (South Africa); Shimoyama, J. [Department of Applied Chemistry, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo (Japan); Singh, S.J. [Leibniz-Institute for Solid State and Materials Research, IFW-Dresden, D-01171 Dresden (Germany); Hayashi, K.; Ogino, H. [Department of Applied Chemistry, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo (Japan); Srinivasu, V.V. [Department of Physics, College of Science, Engineering and Technology, University of South Africa, Johannesburg, 1710 (South Africa)

    2017-02-15

    Highlights: • The non-resonant microwave absorption (NRMA) line shape in evolved with microwave power. • Observed a cross over from ‘normal’ absorption to ‘anomalous’ absorption as a function of microwave power. • The anomalous absorption has been explained in the context of non-hysteretic Josephson junction. - Abstract: Here we present the non-resonant microwave absorption (NRMA) studies on SmFeAsO{sub 0.88}F{sub 0.12} polycrystalline sample measured at 6.06 K with the magnetic field swept from −250 G to +250 G at a frequency of 9.45 GHz. It was observed that the (NRMA) line shape evolves as a function of microwave power. Again, the signal intensity increases from 22.83 µW to 0.710 mW where it reaches a maximum and quite remarkably it changed from ‘normal’ absorption to ‘anomalous’ absorption at 2.247 mW, then the intensity decreases with further increase of microwave power. The crossover from ‘normal’ to ‘anomalous’ NRMA absorption and its dependence on microwave power is a new phenomenon in iron pnictides superconductors and we have attributed this anomaly to come from non-hysteretic Josephson junction.

  1. K -shell ionization during α decay of polonium isotopes and superheavy nuclei

    Science.gov (United States)

    Trzhaskovskaya, M. B.; Nikulin, V. K.

    2016-03-01

    The theory of K -shell ionization during α decay of the 84Po isotopes is considered in detail as a part of our general study of the inner shell ionization probability of heavy and superheavy nuclei. Calculations of K -shell ionization with allowance made for the α -particle tunneling through the atomic Coulomb barrier have been performed in the framework of the fully quantum mechanical treatment developed for the first time by Anholt and Amundsen. Further information is available [Anholt and Amundsen, Phys. Rev. A 25, 169 (1982), 10.1103/PhysRevA.25.169]. As distinct from all previous the K -shell ionization calculations where the Dirac hydrogenlike wave functions have been used, we have found the discrete and continuum electron wave functions in the framework of the relativistic self-consistent Dirac-Fock method. In addition, we have taken into consideration accurately terms associated with the α -particle tunneling. Our exact calculations show that the tunneling contribution to the ionization probability is of great importance while Anholt and Amundsen have asserted that the contribution is small. We have obtained that the K -shell ionization probability during α decay of five isotopes of 84Po correlate better with the available experimental data providing the tunneling is included in calculations. New calculations for K -shell ionization during α decay of superheavy elements Fm249100,No253102,Rg272111, as well as Rn22286 are also presented. The data may be of importance in the combined α ,γ , and conversion-electron spectroscopy used in the superheavy element synthesis analysis.

  2. Incidence of H I 21-cm absorption in strong Fe II systems at 0.5 < z < 1.5

    Science.gov (United States)

    Dutta, R.; Srianand, R.; Gupta, N.; Joshi, R.; Petitjean, P.; Noterdaeme, P.; Ge, J.; Krogager, J.-K.

    2017-03-01

    We present the results from our search for H I 21-cm absorption in a sample of 16 strong Fe II systems [Wr(Mg II λ2796) ≥ 1.0 Å and Wr(Fe II λ2600) or W_{Fe II} ≥ 1 Å] at 0.5 measurements with those in the literature, we find that the detection rate of H I 21-cm absorption increases with W_{Fe II}, being four times higher in systems with W_{Fe II} ≥ 1 Å compared to systems with W_{Fe II} measurements of damped Lyman α systems at this redshift range) and unit covering factor. We find that H I 21-cm absorption arises on an average in systems with stronger metal absorption. We also find that quasars with H I 21-cm absorption detected towards them have systematically higher E(B - V) values than those which do not. Further, by comparing the velocity widths of H I 21-cm absorption lines detected in absorption- and galaxy-selected samples, we find that they show an increasing trend (significant at 3.8σ) with redshift at z < 3.5, which could imply that the absorption originates from more massive galaxy haloes at high z. Increasing the number of H I 21-cm absorption detections at these redshifts is important to confirm various trends noted here with higher statistical significance.

  3. Isothermal section at 773 K and microwave absorption properties of Pr-Fe-Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Shunkang, E-mail: skpan88@163.com [School of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China); Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China); Xiong, Jilei [School of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China); Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China); Yao, Qingrong [School of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China); Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China); School of Materials and Engineering, Central South University, Changsha 410083 (China); Rao, Guanghui, E-mail: rgh@guet.edu.cn [School of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China); Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China); Cheng, Lichun [School of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China); Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China); School of Materials and Engineering, Central South University, Changsha 410083 (China); Zhou, Huaiying [School of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China); Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China)

    2015-10-15

    The isothermal section at 773 K of the phase diagram of Pr-Fe-Ni system was investigated by X-ray powder diffraction and scanning electron microscopy equipped with energy dispersive spectroscopy. The isothermal section consists of 11 single phase regions, 19 two-phase regions and 9 three-phase regions. The maximum solid solubilities of Fe in Ni, PrNi{sub 5}, Pr{sub 2}Ni{sub 7}, PrNi{sub 3}, PrNi{sub 2}, Pr{sub 7}Ni{sub 3} and Pr{sub 3}Ni are about 80.0, 18.2, 15.4, 11.8, 1.9, 1.7 and 4.4 at%, respectively. The maximum solid solubilities of Ni in Fe and Pr{sub 2}Fe{sub 17} are about 5.0 and 1.2 at%, respectively. The solid solubility of Fe in PrNi phase is negligible. The influence of Fe substitution on the microwave absorbing properties of the PrNi{sub 5} alloy was investigated. The frequency corresponding to the minimum absorption peak of Pr{sub 16.67}Ni{sub 83.33-x}Fe{sub x} (x = 0.0–17.5) shifts towards higher frequency region upon the Fe substitution. The Pr{sub 16.67}Ni{sub 68.33}Fe{sub 15.0} alloy exhibits the best microwave absorption properties. The minimum reflection loss of Pr{sub 16.67}Ni{sub 68.33}Fe{sub 15.0} powder is −35.10 dB at 9.76 GHz, and the frequency bandwidth of reflection loss smaller than −10 dB reaches about 1.60 GHz with the best matching thickness of 1.5 mm. - Highlights: • The phase equilibria of Pr-Fe-Ni system at 773 K were determined experimentally. • The isothermal section consists of 11 single phase regions, 19 two-phase regions and 9 three-phase regions. • The solid solubility of each binary compound was determined experimentally. • The microwave absorbing properties of the PrNi{sub 5}-based Pr-Ni-Fe alloys was investigated.

  4. Enhanced microwave absorption of Fe nanoflakes after coating with SiO{sub 2} nanoshell

    Energy Technology Data Exchange (ETDEWEB)

    Yan Longgang; Wang Jianbo; Han Xianghua; Ren Yong; Liu Qingfang; Li Fashen, E-mail: wangjb@lzu.edu.cn [Institute of Applied Magnetics, Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000 (China)

    2010-03-05

    Fe nanoflakes were prepared by the ball-milling technique, and then were coated with 20 nm-thick SiO{sub 2} to prepare Fe/SiO{sub 2} core-shell nanoflakes. Compared with the uncoated Fe nanoflakes, the permittivity of Fe/SiO{sub 2} nanoflakes decreases dramatically, while the permeability decreases slightly. Consequently, reflection losses exceeding - 20 dB of Fe/SiO{sub 2} nanoflakes are obtained in the frequency range of 3.8-7.3 GHz for absorber thicknesses of 2.2-3.6 mm, while the reflection loss of uncoated Fe nanoflakes almost cannot reach - 10 dB in the same thickness range. The enhanced microwave absorption of Fe/SiO{sub 2} nanoflakes can be attributed to the combination of the proper electromagnetic impedance match due to the decrease of permittivity and large magnetic loss due to strong and broadband natural resonance. The key to the combination is the coexistence of the nanoshell microstructure and the nanoflake morphology.

  5. Anomalous non-resonant microwave absorption in SmFeAs(O,F) polycrystalline sample

    Science.gov (United States)

    Onyancha, R. B.; Shimoyama, J.; Singh, S. J.; Hayashi, K.; Ogino, H.; Srinivasu, V. V.

    2017-02-01

    Here we present the non-resonant microwave absorption (NRMA) studies on SmFeAsO0.88F0.12 polycrystalline sample measured at 6.06 K with the magnetic field swept from -250 G to +250 G at a frequency of 9.45 GHz. It was observed that the (NRMA) line shape evolves as a function of microwave power. Again, the signal intensity increases from 22.83 μW to 0.710 mW where it reaches a maximum and quite remarkably it changed from 'normal' absorption to 'anomalous' absorption at 2.247 mW, then the intensity decreases with further increase of microwave power. The crossover from 'normal' to 'anomalous' NRMA absorption and its dependence on microwave power is a new phenomenon in iron pnictides superconductors and we have attributed this anomaly to come from non-hysteretic Josephson junction.

  6. Low-field microwave absorption in pulse laser deposited FeSi thin film

    Energy Technology Data Exchange (ETDEWEB)

    Gavi, H. [Department of Physics, SARCHI Chair in Carbon Technology and Materials, Institute of Applied Materials, University of Pretoria, Pretoria 0028 (South Africa); Ngom, B.D. [Groupe d Laboratoires de Physique des Solid et des Materiaux, Faculte deSciences et Techniques, Universite Cheikh Anta de Dakar, BP 25114 Dakar-Fann, Daka 16996 (Senegal); Institut National de la Recherche Scientifique Centre-Energie Materiaux, Telecommunications 1650, Boulevard Lionel Boulet Varennes (Quebec), Canada J3X 1S2 (Canada); Beye, A.C. [Groupe d Laboratoires de Physique des Solid et des Materiaux, Faculte deSciences et Techniques, Universite Cheikh Anta de Dakar, BP 25114 Dakar-Fann, Daka 16996 (Senegal); Strydom, A.M. [Department of Physics, University of Johannesburg, Johannesburg 2006 (South Africa); Srinivasu, V.V., E-mail: vallavs@unisa.ac.za [Department of Physics, University of South Africa, Pretoria 0003 (South Africa); Chaker, M. [Institut National de la Recherche Scientifique Centre-Energie Materiaux, Telecommunications 1650, Boulevard Lionel Boulet Varennes (Quebec), Canada J3X 1S2 (Canada); Manyala, N., E-mail: ncholu.manyala@up.ac.za [Department of Physics, SARCHI Chair in Carbon Technology and Materials, Institute of Applied Materials, University of Pretoria, Pretoria 0028 (South Africa)

    2012-03-15

    Low field microwave absorption (LFMA) measurements at 9.4 GHz (X-band), were carried out on pulse laser deposited (PLD) polycrystalline B20 cubic structure FeSi thin film grown on Si (111) substrate. The LFMA properties of the films were investigated as a function of DC field, temperature, microwave power and the orientation of DC field with respect to the film surface. The LFMA signal is very strong when the DC field is parallel to the film surface and vanishes at higher angles. The LFMA signal strength increases as the microwave power is increased. The LFMA signal disappears around 340 K, which can be attributed to the disappearance of ferromagnetic state well above room temperature in these films. We believe that domain structure evolution in low fields, which in turn modifies the low field permeability as well as the anisotropy, could be the origin of the LFMA observed in these films. The observation of LFMA opens the possibility of the FeSi films to be used as low magnetic field sensors in the microwave and rf frequency regions. - Highlights: Black-Right-Pointing-Pointer B20 crystalline FeSi thin film shows low field microwave absorption. Black-Right-Pointing-Pointer Usual ferromagnic resonance typical of magnetic materials is observed in FeSi film. Black-Right-Pointing-Pointer FeSi film can be used for low magnetic field sensors.

  7. Microwave absorption property of the diatomite coated by Fe-CoNiP films

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Zhenqiang; Cai, Jun; Xu, Yonggang, E-mail: xuyonggang221@163.com; Zhang, Deyuan

    2015-08-15

    Highlights: • The bio-absorbent coated Fe-CoNiP was fabricated by electroless and CVD. • The EM parameters were enlarged as Fe coated on the diatomite. • The coating CIPs play a key role in the enhancement mechanism. • The Fe-CoNiP diatomite had a better absorbing and shielding properties. - Abstract: A bio-absorbent of Fe-CoNiP coated on the diatomite was fabricated by way of electroless plating of CoNiP and subsequent chemical vapor deposition of Fe. The surface morphology and composition of the above-mentioned diatomite particles at different stage were characterized with the scanning electron microscopy and the energy spectrum analysis respectively, and the results showed that the diatomite was successfully coated with CoNoP and Fe (carbony iron). The complex permittivity and permeability of composites filled with the bio-absorbent and paraffin was measured in frequency range of 2–18 GHz, and then the microwave reflection loss (RL) and the shielding effectiveness (SE) were calculated. The results showed that the permittivity and the permeability were both enlarged as Fe films were coated onto the CoNiP-coated diatomite, which was attributed to the excellent electromagnetic property of carbonyl irons. The composites made with the Fe-CoNiP diatomite had a better absorbing property (minimum RL −11.0 dB) as well as the shielding property (maximum SE 5.6 dB) at thickness 2 mm. It indicated the absorption property was mainly due to the attenuation on the microwave, and the Fe-CoNiP diatomite could be an effective absorbent with low-density.

  8. Microwave absorption property of the diatomite coated by Fe-CoNiP films

    Science.gov (United States)

    Yan, Zhenqiang; Cai, Jun; Xu, Yonggang; Zhang, Deyuan

    2015-08-01

    A bio-absorbent of Fe-CoNiP coated on the diatomite was fabricated by way of electroless plating of CoNiP and subsequent chemical vapor deposition of Fe. The surface morphology and composition of the above-mentioned diatomite particles at different stage were characterized with the scanning electron microscopy and the energy spectrum analysis respectively, and the results showed that the diatomite was successfully coated with CoNoP and Fe (carbony iron). The complex permittivity and permeability of composites filled with the bio-absorbent and paraffin was measured in frequency range of 2-18 GHz, and then the microwave reflection loss (RL) and the shielding effectiveness (SE) were calculated. The results showed that the permittivity and the permeability were both enlarged as Fe films were coated onto the CoNiP-coated diatomite, which was attributed to the excellent electromagnetic property of carbonyl irons. The composites made with the Fe-CoNiP diatomite had a better absorbing property (minimum RL -11.0 dB) as well as the shielding property (maximum SE 5.6 dB) at thickness 2 mm. It indicated the absorption property was mainly due to the attenuation on the microwave, and the Fe-CoNiP diatomite could be an effective absorbent with low-density.

  9. High-Resolution Spectroscopy of K-shell Praseodymium with a High-Energy Calorimeter

    Energy Technology Data Exchange (ETDEWEB)

    Thorn, D B; Brown, G V; Clementson, J T; Chen, H; Chen, M H; Beiersdorfer, P; Boyce, K R; Kilbourne, C A; Porter, F S; Kelley, R L

    2007-06-05

    We present a measurement of the K-shell spectrum of He-like through Be-like praseodymium ions trapped in the Livermore SuperEBIT electron beam ion trap using a bismuth absorber pixel on the XRS/EBIT microcalorimeter. This measurement is the first of its kind where the n=2 to n=1 transitions of the various charge states are spectroscopically resolved. The measured transition energies are compared with theoretical calculations from several atomic codes.

  10. K-shell photoionization of O4 + and O5 + ions: experiment and theory

    Science.gov (United States)

    McLaughlin, B. M.; Bizau, J.-M.; Cubaynes, D.; Guilbaud, S.; Douix, S.; Shorman, M. M. Al; Ghazaly, M. O. A. El; Sakho, I.; Gharaibeh, M. F.

    2017-03-01

    Absolute cross-sections for the K-shell photoionization of Be-like (O4 +) and Li-like (O5 +) atomic oxygen ions were measured for the first time (in their respective K-shell regions) by employing the ion-photon merged-beam technique at the SOLEIL synchrotron-radiation facility in Saint-Aubin, France. High-resolution spectroscopy with E/ΔE ≈ 3200 (≈170 meV, full width at half-maximum) was achieved with photon energy from 550 to 670 eV. Rich resonance structure observed in the experimental spectra is analysed using the R-matrix with pseudo-states (RMPS) method. Results are also compared with the screening constant by unit nuclear charge (SCUNC) calculations. We characterize and identify the strong 1s → 2p resonances for both ions and the weaker 1s → np resonances (n ≥ 3) observed in the K-shell spectra of O4 +.

  11. Microwave absorption properties of FeSi flaky particles prepared via a ball-milling process

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chao [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Yuan, Yong [Precision Machinery Research Institute of Shanghai Space Flight Academy, Shanghai 201600 (China); Jiang, Jian-tang [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Gong, Yuan-xun [Aerospace Research Institute of Special Material and Processing Technology, Beijing 100074 (China); Zhen, Liang, E-mail: lzhen@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); MOE Key Laboratory of Micro-system and Micro-structures Manufacturing, Harbin Institute of Technology, Harbin 150080 (China)

    2015-12-01

    Flaky FeSi alloy particles with different aspect ratio were produced via ball-milling and a subsequent annealing. The microstructure and the morphology of the particles were examined by XRD and SEM. The dc resistivity, the static magnetization properties and electromagnetic properties were measured. Particles with high aspect ratio were found possess high permittivity and permeability. On the other hand, the variation of grain size and defects density was found influence the permittivity and permeability. High specific area was believed contribute to the intense dielectric loss and the high shape magnetic anisotropy lead to high permeability in the target band. Increased electromagnetic parameters compel the absorption peak’s shift to lower frequency. Coating using flaky FeSi particles milled for 12 h as fillers presented a reflection loss of −10 dB at 2 GHz and a matching thickness of 1.88 mm. The flaky FeSi alloy particles prepared through ball-milling and annealing can be promising candidates for EMA application at 1–4 GHz band. - Highlights: • Large quantity of flakey FeSi particles were produced through a simple way. • Coatings with as-milled FeSi particles exhibit excellent EMA performance in L-S band. • Shape and size of particles can be controlled via adjusting the ball-milling time. • Shape/size along with the microstructure influence the electromagnetic properties. • Shape/size contribute more to the excellent EMA performance compared to microstructure.

  12. Double K-shell ionization accompanying internal conversion of the 0.662-MeV transition in 137Bam

    Science.gov (United States)

    Nagy, H. J.; Brady, K. E.; Schupp, G.

    1988-12-01

    Double ionization of the atomic K shell accompanying K-shell internal conversion of the 0.662-MeV transition of 137Bam has been studied by recording coincidences between Kα hypersatellite x rays and Kα satellite x rays emitted when the double vacancies are filled. The probability per K-shell internal conversion that a double vacancy is formed, PKK(IC), was found to be (10.0+/-0.9)×10-5 which is in general agreement with less precise earlier experiments, but is a factor of 2.7+/-0.3 larger than the relativistic, one-step theory of Mukoyama and Shimizu.

  13. Flaky FeSiAl alloy-carbon nanotube composite with tunable electromagnetic properties for microwave absorption

    Science.gov (United States)

    Huang, Lina; Liu, Xiaofang; Chuai, Dan; Chen, Yaxin; Yu, Ronghai

    2016-01-01

    Flaky FeSiAl alloy/multi-wall carbon nanotube (FeSiAl/MWCNT) composite was fabricated by facile and scalable ball milling method. The morphology and electromagnetic properties of the FeSiAl alloy can be well tuned by controlling the milling time. It is found that the magnetic loss of the FeSiAl alloy is improved by optimizing the milling time due to the increased anisotropy field. Meanwhile the addition of MWCNTs enhances the dielectric loss of the composite by increasing the interfacial polarizations, dipolar polarizations and conductive paths. Relative to conventional FeSiAl absorbers, the FeSiAl/MWCNT composite exhibits greatly improved microwave absorption performance with advantages of strong absorption and small thickness. The minimum reflection loss of the composite reaches −42.8 dB at 12.3 GHz at a very thin thickness of 1.9 mm. PMID:27762327

  14. [Speciation analysis of trace elements Cu, Fe and Zn in serum by flame atomic absorption spectrophotometry].

    Science.gov (United States)

    Hu, Jun; Chang, Yao-Ming; Gao, Shuang-Bin; Hai, Chun-Xu; Li, Jin-Sheng; Xie, Xiao-Ping

    2008-03-01

    Since biological functions of the elements are generally different, depending on their chemical forms, chemical speciation analysis is really important in metallomics research. Thus, multielement analysis and chemical speciation of the elements in serum were carried out in the present work. A hyphenated technique was developed for high-throughput speciation analysis of the copper, iron and zinc in serum by molecular biology technology and flame atomic absorption spectrophotometry (AAS). Here, Cu, Fe and Zn in serum were classifyied as the forms of combination and non-combination. The serum protein was precipitated by 60% concentration of ethanol under hypothermy. The forms of combination of Cu, Fe and Zn in serum which combined with proteins were in precipitations, and the forms of non-combination of Cu, Fe and Zn in serum, which were free ions, were in supernatant. The total amount of Cu, Fe and Zn in serum and the amount of the forms of non-combination of Cu, Fe and Zn were analyzed by AAS. The amount of the forms of combination of Cu, Fe and Zn was obtained by calculation. The detection limit of Cu in serum by the method is around and 9.84 x 10(-3) microg x mL(-1). For Fe and Zn, the detection limit is about 2.76 x 10(-2) microg x mL(-1) and 1.06 x 10(-3) microg x mL(-1), respectively. The percentage recovery of trace elements Cu, Fe and Zn by the proposed procedure is in the range 95.0%-101.0%, 95.0%-102.0% and 95.0%-103.0%, respectively. The relative standard deviation (RSD) of trace elements Cu, Fe and Zn in the serum is in the range 1.88%-2.26%, 0.56%-1.59% and 0.34%-1.36%, respectively. Speciation of trace elements Cu, Fe and Zn in the serum of SD rat were analyzed by the method.

  15. FeS-Quantum-Dot Sensitized Metal Oxide Photoelectrodes: Photoelectrochemistry and Photoinduced Absorption Spectroscopy

    Directory of Open Access Journals (Sweden)

    Idriss Bedja

    2011-01-01

    Full Text Available TiO2, ZnO nanoparticulate(-np, and ZnO-nanorod(-nr electrodes have been modified with FeS2 (pyrite nanoparticles. Quantum size effect is manifested by a blue shift in both absorption and photocurrent action spectra. PIA (photoinduced absorption spectroscopy, a multipurpose tool in the study of dye-sensitized solar cells, is used to study quantum-dot modified metal oxide (MO nanostructured electrodes. The PIA spectra showed an evidence for long-lived photoinduced charge separation. Time-resolved PIA showed that recombination between electrons and holes occurs on a millisecond timescale. Incident-photon-to-current efficiencies at 400 nm are ranged between 13% and 25%. The better solar cell performance of FeS2 on ZnO-nr over ZnO-np can be ascribed to the faster, unidirectional e-transport channels through the ZnO-nr as well as the longer electron lifetimes. The lower performances of electrodes can be explained by the presence of FeS2 phases other than the photoactive pyrite phase, as evidenced from XRD study.

  16. Low field microwave absorption and magnetization process in CoFeNi electroplated wires

    Institute of Scientific and Technical Information of China (English)

    H.García-Miquel; G.V. Kurlyandskaya

    2008-01-01

    Ferromagnetic resonance (FMR), Ferromagnetic antirresonance (FMAR) and low field magnetoimpedance (MI)are the characteristic features of high frequency losses in applied fields. While some results on FMR and FMAR in CoFeNi eleetroplated wires were reported earlier, here we present mierowave absorption in CuBe wires electroplated by 1 ìm FeCoNi magnetic layer at very low fields. These data are comparatively analysed together with longitudinal hysteresis loops in order to reveal the correlation between power absorption and magnetization processes. Microwave studies are made by using the cavity perturbation method at 9.65 GHz for a DC field parallel to the sample axis, and with microwave magnetic field hrf parallel or perpendicular to the wire axis. Two peaks have been observed in all samples, one is due to FMR, and the other is, at very low fields, related to MI. The MI peaks represent minima in power absorption. By comparing with the hysteresis loop we remark the close correspondence between the MI phenomena in the axial mode and the concomitant magnetization process.

  17. Experimental study on the inhibition of biological reduction of Fe(Ⅲ)EDTA in NOx absorption solution

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Scrubbing of NOx from the gas phase with Fe(Ⅱ)EDTA has been shown to be highly effective. A new biological method can be used to convert NO to N2 and regenerate the chelating agent Fe(Ⅱ)EDTA for continuous NO absorption. The core of this biological regeneration is how to effectively simultaneous reduce Fe(Ⅲ)EDTA and Fe(Ⅱ)EDTA-NO, two mainly products in the ferrous chelate absorption solution. The biological reduction rate of Fe(Ⅲ)EDTA plays a main role for the NOx removal efficiency. In this paper, a bacterial strain identified as Klebsiella Trevisan sp. was used to demonstrate an inhibition of Fe(Ⅲ)EDTA reduction in the presence of Fe(Ⅱ)EDTA-NO. The competitive inhibition experiments indicted that Fe(Ⅱ)EDTA-NO inhibited not only the growth rate of the iron-reduction bacterial strain but also the Fe(Ⅲ)EDTA reduction rate. Cell growth rate and Fe(Ⅲ)EDTA reduction rate decreased with increasing Fe(Ⅱ)EDTA-NO concentration in the solution.

  18. X-ray absorption study of the Fe and Mo valence states in Sr{sub 2}FeMoO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Martins, H.P., E-mail: henrique@fisica.ufpr.br [Departamento de Física, Universidade Federal do Paraná, Caixa Postal 19044, 81531-990 Curitiba, PR (Brazil); Prado, F. [Departamento de Física, Universidad Nacional del Sur, Av. Leandro N. Alem 1253, 8000 Bahía Blanca (Argentina); Caneiro, A. [Centro Atómico Bariloche, Comisión Nacional de Energía Atómica, Av. Ezequiel Bustillo 9500, 8400 Bariloche (Argentina); Vicentin, F.C.; Chaves, D.S. [Laboratório Nacional de Luz Síncrotron, CNPEM, Caixa Postal 6192, 13083-970 Campinas, SP (Brazil); Mossanek, R.J.O.; Abbate, M. [Departamento de Física, Universidade Federal do Paraná, Caixa Postal 19044, 81531-990 Curitiba, PR (Brazil)

    2015-08-15

    Highlights: • Study of the Fe/Mo valence states in Sr{sub 2}FeMoO{sub 6} using X-ray absorption spectroscopy. • The sample was checked to discard disorder and secondary phases. • The sample was stored carefully and measured promptly to avoid aging effects. • The Fe ions present a fairly ionic Fe{sup 3+} (3d{sup 5}) valence. • The Mo ions are in a more covalent Mo{sup 5+} (4d{sup 1}) state. • Fe ions in a 2+ valence state are not present in the Fe-L{sub 2,3} spectrum. • The O-K spectrum is sensitive to the unoccupied electronic states of the metal ions. - Abstract: We studied the Fe and Mo valence states in Sr{sub 2}FeMoO{sub 6} using X-ray absorption spectroscopy. The experimental results were analyzed using atomic multiplet plus crystal field calculations. The analysis indicates that the Fe ions present a fairly ionic Fe{sup 3+} (3d{sup 5}) valence, and that the Mo ions are in a strongly covalent Mo{sup 5+} (4d{sup 1}) state. The presence of Fe ions in a 2+ valence state can be excluded from the Fe-L{sub 2,3} spectrum. These results can be understood taking into account the relative energy of the d-levels, the relative strength of the M d–O p mixing, and the exchange stabilization of the Fe{sup 3+} ion.

  19. Hydrogen absorption of LaFe_(11.5)Si_(1.5) compound under low hydrogen gas pressure

    Institute of Scientific and Technical Information of China (English)

    Fu Bin; Long Yi; Shi Pu-Ji; Ma Tao; Bao Bo; Yan A-Ru; Chen Ren-Jie

    2009-01-01

    Hydrogen absorptions of LaFe_(11.5)Si_(1.5) compound in 1-atm hydrogen gas at different temperatures are investigated. The hydrogen content in the hydrogenated sample does not increase with the increase of temperature of hydrogen absorption but changes complicatedly. The characteristic offirst-order transition in LaFe_(11.5) Si_(1.5) compound is weakened after hydrogen absorption. It leads the peaks of magnetic entropy to become wider and the hysteresis loss to reduce significantly, but relative cooling power(RCP)is not changed considerably.

  20. Hydrogen Absorption and Release Behavior in Hydrogen Decrepitation Process of Nd-Fe-B Alloys

    Institute of Scientific and Technical Information of China (English)

    陈晓东; 姜忠良; 陈秀云; 石大立; 杨昌平; 朱静

    2003-01-01

    The behavior of hydrogen absorption and release in hydrogen decrepitation (HD) process of Nd-Fe-B alloys were investigated. The results reveal that the reactivity and the amount of hydrogen absorption in HD process are related to the surface activity of the alloy so that the fresh and active surface has a higher efficiency. The presence of Nd-rich phase at the grain boundary is an essential factor of the HD activity of the alloy at room temperature. On degassing, hydrogen is released from the HD powder continuously with increasing temperature. And the residual hydrogen is as low as 0.0015% at 1073 K, which shows that the hydrogen is almost exhaused. It is feasible to remove the hydrogen from the HD powder by heating treatment at the temperature of 523~723 K for 1 h prior to the magnetic field forming in order to decrease the harmful effect of hydrogen on the easy axis alignment of HD magnet.

  1. Hydrogen absorption of NdDyFeCoNbCuB sintered magnets

    Institute of Scientific and Technical Information of China (English)

    LUO Jianjun; De Rango P; Fruchart D; MEI Jinna; HU Rui; LI Jinshan; ZHOU Lian

    2009-01-01

    Hydrogen absorption and desorption charactersfics for high coereivity NdDyFeCoNbCuB sintered bulk magnets were studied, by differential scanning calorimetry (DSC) measurement and hydrogenation kinetics measurement. The DSC measurements showed that hy-drogenation of Nd-rich phase occurred in the temperature range of 40-185 ℃, hydrogenation of the tetragonal (φ) phase in the temperature range of 185-220 ℃, as well as the disproportionation of the φ phase that occurred in a broad temperature range from around 500 to 800℃. The hydrogenation kinetics measurements indicated that hydrogen absorption of the bulk magnets at 50 ℃ absorbed more hydrogen than at 150 ℃, although this procedure was slower at 50 ℃ than at 150 ℃. This phenomenon was discussed by means of pres-sure-concentration-temperature (p-c-T) diagrams.

  2. Double K-shell ionization accompanying the internal conversion of the 0.166-MeV transition in 139La

    Science.gov (United States)

    Schupp, G.; Nagy, H. J.; Miles, V. A.

    1987-12-01

    Double ionization of the atomic K shell accompanying the K-shell internal conversion of the 0.166-MeV transition of 139La has been studied by recording triple coincidences between La K x rays, La K satellite x rays, and La Kα hypersatellite x rays emitted when the K-shell vacancies are filled. The probability per K-shell internal conversion that a double vacancy is formed, PKK(IC), was found to be (6.0+/-1.4)×10-5, which is in good agreement with the K-shell electron shakeoff prediction of 5.1×10-5 by Mukoyama and Shimizu.

  3. K-shell X-ray spectroscopy of laser produced aluminum plasma

    Science.gov (United States)

    Kaur, Channprit; Chaurasia, S.; Poswal, A. K.; Munda, D. S.; Rossall, A. K.; Deo, M. N.; Sharma, Surinder M.

    2017-01-01

    Optimization of a laser produced plasma (LPP) X-ray source has been performed by analyzing K-shell emission spectra of Al plasma at a laser intensity of 1013-1014 W/cm2. The effect of varying the laser intensity on the emissivity of the K-shell resonance lines is studied and found to follow a power law, Ix =(IL) α with α=2.2, 2.3, 2.4 for Heβ, Heγ, Heδ respectively. The emission of these resonance lines has been found to be heavily anisotropic. A Python language based code has been developed to generate an intensity profile of K-shell spectral lines from the raw data. In theoretical calculations, the temperature is estimated by taking the ratio of the Li-like satellite (1s22p-1s2p3p) and the Heβ (1s2-1s3p) resonance line and the ratio of the He-like satellite (1s2p-2p2) and the Lyα (1s-2p) resonance line. To determine the plasma density, stark broadening of the Lyβ spectral line is used. Simulation was carried out using the FLYCHK code to generate a synthetic emission spectrum. The results obtained by FLYCHK are Te=160 eV, Th=1 keV, f=0.008, ne=5×1020 cm-3 and the analytical model resulted Te=260-419 eV and ne=3x1020 cm-3.

  4. Voltage-controlled magnetic anisotropy in Fe|MgO tunnel junctions studied by x-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Miwa, Shinji, E-mail: miwa@mp.es.osaka-u.ac.jp; Matsuda, Kensho; Tanaka, Kazuhito; Goto, Minori; Suzuki, Yoshishige [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Kotani, Yoshinori; Nakamura, Tetsuya [Japan Synchrotron Radiation Research Institute/SPring-8, Sayo, Hyogo 679-5198 (Japan)

    2015-10-19

    In this study, voltage-controlled magnetic anisotropy (VCMA) in Fe|MgO tunnel junctions was investigated via the magneto-optical Kerr effect, soft x-ray absorption spectroscopy, and magnetic circular dichroism spectroscopy. The Fe|MgO tunnel junctions showed enhanced perpendicular magnetic anisotropy under external negative voltage, which induced charge depletion at the Fe|MgO interface. Despite the application of voltages of opposite polarity, no trace of chemical reaction such as a redox reaction attributed to O{sup 2−} migration was detected in the x-ray absorption spectra of the Fe. The VCMA reported in the Fe|MgO-based magnetic tunnel junctions must therefore originate from phenomena associated with the purely electric effect, that is, surface electron doping and/or redistribution induced by an external electric field.

  5. Coupled-channel calculations of K-shell ionisation in asymmetric collision systems

    Energy Technology Data Exchange (ETDEWEB)

    Mehler, G.; Greiner, W.; Soff, G.

    1987-06-28

    Theoretical results on K-shell ionisation for a variety of asymmetric collision systems are reported. The calculated ionisation rates are compared with experimental data. The coupled-channel formalism underlying these calculations is presented. It is based on a set of relativistic target centred states, taking a screened potential of Dirac-Fock-Slater type into account. The effects of different matrix elements are discussed, e.g. continuum-continuum couplings. The binding effect is inherently contained in the present approach and described in a dynamical way.

  6. Measurement of vacancy transfer probability from K to L shell using K-shell fluorescence yields

    Indian Academy of Sciences (India)

    Ö Söğüt; E Büyükkasap; A Küçükönder; T Tarakçioğlu

    2009-10-01

    The vacancy transfer probabilities from K to L shell through radiative decay, KL , have been deduced for the elements in the range 19 ≤ ≤ 58 using K-shell fluorescence yields. The targets were irradiated with photons at 59.5 keV from a 75mCi 241Am annular source. The K X-rays from different targets were detected with a high resolution Si(Li) detector. The measurement of vacancy transfer probabilities are least-squared fitted to second-order polynomials to obtain analytical relations that represent these probabilities as a function of atomic number. The obtained results agree with theoretical and fitted values.

  7. Metastable Innershell Molecular State (MIMS) IV: Heteronucleus K-shell MIMS with H+ and He+

    OpenAIRE

    Bae, Young K.

    2014-01-01

    The model of MIMS (Metastable Innershell Molecular State) has been applied to interpreting the Kα X-ray satellite data of target atoms in H+ and He+ ion impact on Al, Ca and Ti targets. The binding energies of the heteronucleus H-K-MIMS (K-shell MIMS formed with H and a target atom) and He-K-MIMS have been obtained. The binding energy trend of the H-K-MIMS shows a Z2 dependency similar to that of the homonucleus K-MIMS, while that of the He-K-MIMS shows a transitional behavior from the former...

  8. Magnetic and microwave absorption properties of La-Nd-Fe alloys

    Science.gov (United States)

    Qiao, Ziqiang; Pan, Shunkang; Xiong, Jilei; Cheng, Lichun; Yao, Qingrong; Lin, Peihao

    2017-02-01

    Through arc smelting and high energy ball milling method to synthesized the powders of LaxNd2-xFe17 (x=0.0, 0.2, 0.4, 0.6). By x-ray diffraction (XRD), scanning electron microscopy (SEM) and laser particle analyzer (LPS) to study the structural, morphology, particle size distribution of the powders, respectively. The electromagnetic parameters and saturation magnetization of the powers were measured by a vector network analyzer (VNA) and vibrating sample magnetometer (VSM), respectively. The saturation magnetization decreases with the La increasing. The minimum absorption peak frequency shifts towards a lower frequency region with an increase of La concentration. The microwave absorbing properties of the composite with different ratios of La0.2Nd1.8Fe17/Ni were studied. The microwave absorbing peaks of the composite shift to higher frequencies, and the microwave absorbing properties improved with the Ni content increase to 20%. The minimum reflection loss is -32.5 dB at 9.8 GHz and the bandwidth less than -10 dB (Microwave absorption rate 90%) reaches 3 GHz with a thickness of 1.8 mm.

  9. Incidence of HI 21-cm absorption in strong FeII systems at $0.5

    CERN Document Server

    Dutta, R; Gupta, N; Joshi, R; Petitjean, P; Noterdaeme, P; Ge, J; Krogager, J -K

    2016-01-01

    We present the results from our search for HI 21-cm absorption in a sample of 16 strong FeII systems ($W_{\\rm r}$(MgII $\\lambda2796$) $\\ge1.0$ \\AA\\ and $W_{\\rm r}$(FeII $\\lambda2600$) or $W_{\\rm FeII}$ $\\ge1$ \\AA) at $0.5absorption detections from our sample, which have increased the known number of detections in strong MgII systems at this redshift range by $\\sim50$%. Combining our measurements with those in the literature, we find that the detection rate of HI 21-cm absorption increases with $W_{\\rm FeII}$, being four times higher in systems with $W_{\\rm FeII}$ $\\ge1$ \\AA\\ compared to systems with $W_{\\rm FeII}$ $<1$ \\AA. The $N$(HI) associated with the HI 21-cm absorbers would be $\\ge 2 \\times 10^{20}$ cm$^{-2}$, assuming a spin temperature of $\\sim500$ K (based on HI 21-cm absorption measurements of damped Lyman-$\\alpha$ systems at this redshift range) and unit covering factor. We find that ...

  10. Prominent role of multielectron processes in K -shell double and triple photodetachment of oxygen anions

    Science.gov (United States)

    Schippers, S.; Beerwerth, R.; Abrok, L.; Bari, S.; Buhr, T.; Martins, M.; Ricz, S.; Viefhaus, J.; Fritzsche, S.; Müller, A.

    2016-10-01

    The photon-ion merged-beam technique was used at a synchrotron light source for measuring the absolute cross sections of the double and triple photodetachment of O- ions. The experimental photon energy range of 524-543 eV comprised the threshold for K -shell ionization. Using resolving powers of up to 13 000, the position, strength, and width of the below-threshold 1 s 2 s22 p6 2S resonance as well as the positions of the 1 s 2 s22 p5 3P and 1 s 2 s22 p5 1P thresholds for K -shell ionization were determined with high precision. In addition, systematically enlarged multiconfiguration Dirac-Fock calculations have been performed for the resonant detachment cross sections. Results from these ab initio computations agree very well with the measurements for the widths and branching fractions for double and triple detachment, if double shakeup (and shakedown) of the valence electrons and the rearrangement of the electron density is taken into account. For the absolute cross sections, however, a previously found discrepancy between measurements and theory is confirmed.

  11. Double K-shell-vacancy production in the decay of 114mIn

    Science.gov (United States)

    van Eijk, C. W. E.; Wijnhorst, J.; Popelier, M. A.

    1981-08-01

    The probability PKK of double K-shell-vacancy production per K-shell internal conversion of the 192-keV E4 transition in the decay of 114mIn has been determined by means of a hypersatellite KαH-x-ray-K-x-ray coincidence experiment using an intrinsic Ge and a NaI(Tl) detector, and by means of a direct measurement of the KαH1- and KαH2-x-ray components with a curved-crystal spectrometer. The results are in good agreement: PKK=(10.8+/-0.9)×10-5 and PKK=(9.6+/-0.8)×10-5, respectively. The average value is PKK=(10.2+/-0.6)×10-5. For the intensity ratio of the KαH1- and KαH2-x-ray components we obtained 1.57+/-0.17, and for the energy shifts of the two components we obtained, respectively, 566.8+/-1.4 and 560.2+/-1.3 eV.

  12. Microwave absorption properties of NiCoFe2O4-graphite embedded poly(o-phenetidine nanocomposites

    Directory of Open Access Journals (Sweden)

    Anil Ohlan

    2011-09-01

    Full Text Available Poly(o-phenetidine nanocomposites (PNG with NiCoFe2O4 and exfoliated graphite have been synthesized via in-situ emulsion polymerization. Systematic investigations reveal that the NiCoFe2O4 nanoparticles (30-40 nm in the poly(o-phenetidine matrix have phenomenal effect in determining the electrical, magnetic, and the microwave absorption properties of the nanocomposites. Shielding effectiveness due to absorption (SEA value of 32 dB (>99.9% has been achieved for PNG composite for its use as broadband microwave absorbing material. The microwave absorption of these composites can be attributed to dielectric loss from graphite and poly(o-phenetidine matrix, and magnetic loss from NiCoFe2O4 nanoparticles.

  13. Microwave absorption capability of microcapsules by coating FeSiAlCr with SiO2

    Science.gov (United States)

    Huang, Weirong; Zhang, Penghua; Yan, Wenjing; Zhou, Liang; Xu, Hui

    2012-10-01

    Electromagnetic wave absorption of microcapsules by coating FeSiAlCr with SiO2 is investigated. The absorption amplitude of the microcapsules is found to increase significantly in the lower frequency of microwave compared with the corpuscles of FeSiAlCr alloy. Reflection loss (RL) exceeding -10 dB can be obtained for all frequencies within 2.6-7.3 GHz, covering half of the S-band, and the whole C-band when the absorber layer thickness is 2 mm. The maximum RL can exceed -18 dB at 4.3 GHz, while the RL is only -4 dB with the corpuscles of FeSiAlCr alloy. The reason is that the microcapsules's conductance is decreased and the absorption of electromagnetic wave in the microcapsule materials is easier.

  14. Understanding Bright 13 keV Kr K-shell X-ray Sources at the NIF

    Science.gov (United States)

    May, M. J.; Colvin, J. D.; Kemp, G. E.; Fournier, K. B.; Scott, H.; Patel, M.; Barrios, Widmann; Widmann, K.

    2015-11-01

    High x-ray conversion efficiency (CE) K-shell Kr sources are being investigated for High Energy Density experiments. These sources are 4.1 mm in diameter 4.4 mm tall hollow epoxy tubes having a 40 μm thick wall holding either 1.2 or 1.5 atm of Kr gas. The CE of K-shell Kr is dependent upon the peak electron temperature in the radiating plasma. In the NIF experiments, the available energy heats the source to Te = 6-7 keV, well below the temperature of Te ~25 keV needed to optimize the Kr CE. The CE is a steep function of the peak electron temperature. A spatially averaged electron temperature can be estimated from measured He(α) and Ly(α) line ratios. Some disagreement has been observed in the simulated and measured line ratios for some of these K-shell sources. Disagreements have been observed between the simulated and measured line ratios for some of these K-shell sources. To help understand this issue, Kr gas pipes have been shot with 3 ω light at ?750 kJ at ~210, ~140 TW and ~120 TW power levels with 3.7, 5.2 and 6.7 ns pulses, respectively. The power and pulse length scaling of the measured CE and K-shell line ratios and their comparison to simulations will be discussed. This work was performed under the auspic

  15. Metastable Innershell Molecular State (MIMS II: K-shell X-ray satellites in heavy ion impact on solids

    Directory of Open Access Journals (Sweden)

    Young K. Bae

    2014-01-01

    Full Text Available Metastable Innershell Molecular State (MIMS, an innershell-bound ultra-high-energy molecule, was previously proposed to explain a ∼40% efficiency of soft-X-ray generation in ∼0.05 keV/amu nanoparticle impact on solids. Here, the MIMS model has been extended and applied to interpreting the experimental K-shell X-ray satellite spectra for more than 40 years in keV-MeV/amu heavy-ion impact on solids. The binding energies of the K-shell MIMS of elements from Al to Ti were determined to be 80–200 eV. The successful extension of the model to the K-shell MIMS confirms that all elements in the periodic table and their combinations are subjected to the MIMS formation.

  16. Metastable Innershell Molecular State (MIMS) II: K-shell X-ray satellites in heavy ion impact on solids

    Science.gov (United States)

    Bae, Young K.

    Metastable Innershell Molecular State (MIMS), an innershell-bound ultra-high-energy molecule, was previously proposed to explain a ∼40% efficiency of soft-X-ray generation in ∼0.05 keV/amu nanoparticle impact on solids. Here, the MIMS model has been extended and applied to interpreting the experimental K-shell X-ray satellite spectra for more than 40 years in keV-MeV/amu heavy-ion impact on solids. The binding energies of the K-shell MIMS of elements from Al to Ti were determined to be 80-200 eV. The successful extension of the model to the K-shell MIMS confirms that all elements in the periodic table and their combinations are subjected to the MIMS formation.

  17. Coulomb explosion imaging of bromobenzene and bromophenol molecules following Br K-shell ionization

    Energy Technology Data Exchange (ETDEWEB)

    Iwayama, H; Nagaya, K; Murakami, H; Ohmasa, Y; Yao, M, E-mail: yao@scphys.kyoto-u.ac.j [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan)

    2010-09-28

    We have performed multiple-ion coincidence momentum imaging measurements for bromobenzene and bromophenol molecules irradiated by hard x-ray photons at Br K-shell edge. Dominant fragment ions were singly charged monatomic ions H{sup +}, C{sup +}, O{sup +} and Br{sup +}. This indicates that parent molecules became highly charged through Auger cascade of Br core shell ionization. From an analysis of momentum vectors of ions, we found that the ejection directions of fragment ions strongly reflected the molecular structure of the neutral state. We can reproduce experimental results well by the trajectory analysis of fragment ions based on a Coulomb explosion model. This result shows that hard x-ray radiation enables us to apply Coulomb explosion imaging even for complex molecules such as benzene molecules.

  18. Double K-shell-vacancy production in the decays of 181W and 165Er

    Science.gov (United States)

    van Eijk, C. W. E.; Wagenaar, J. P.; Bergsma, F.; Lourens, W.

    1982-11-01

    The probabilities PKK of double-K-shell-vacancy production per K-electron-capture decay of 181W and 165Er have been determined by means of Kα x-ray-K x-ray coincidence experiments: PKK=(2.4+/-0.6)×10-6 and PKK=(8.2+/-2.8)×10-6, respectively. The observed energy shifts of the hypersatellite Ta KαH1 x-ray and Ho KαH1 x-ray lines are 1026+/-62 eV and 930+/-70 eV, respectively. In the case of 181W, the theoretical PKK value deviates significantly from the above-mentioned experimental value. In combination with results from other experiments, this strongly suggests that, contrary to what the present theory predicts, PKK shows a considerable dependence on the ratio of transition energy to threshold energy.

  19. Metastable Innershell Molecular State (MIMS IV: Heteronucleus K-shell MIMS with H+ and He+

    Directory of Open Access Journals (Sweden)

    Young K. Bae

    2014-01-01

    Full Text Available The model of MIMS (Metastable Innershell Molecular State has been applied to interpreting the Kα X-ray satellite data of target atoms in H+ and He+ ion impact on Al, Ca and Ti targets. The binding energies of the heteronucleus H-K-MIMS (K-shell MIMS formed with H and a target atom and He-K-MIMS have been obtained. The binding energy trend of the H-K-MIMS shows a Z2 dependency similar to that of the homonucleus K-MIMS, while that of the He-K-MIMS shows a transitional behavior from the former to the latter. These behaviors were interpreted with the Z-expansion theory of heteronucleus molecules.

  20. Metastable Innershell Molecular State (MIMS) IV: Heteronucleus K-shell MIMS with H+ and He+

    Science.gov (United States)

    Bae, Young K.

    The model of MIMS (Metastable Innershell Molecular State) has been applied to interpreting the Kα X-ray satellite data of target atoms in H+ and He+ ion impact on Al, Ca and Ti targets. The binding energies of the heteronucleus H-K-MIMS (K-shell MIMS formed with H and a target atom) and He-K-MIMS have been obtained. The binding energy trend of the H-K-MIMS shows a Z2 dependency similar to that of the homonucleus K-MIMS, while that of the He-K-MIMS shows a transitional behavior from the former to the latter. These behaviors were interpreted with the Z-expansion theory of heteronucleus molecules.

  1. K-shell (e, 3e) double ionization of beryllium by relativistic electrons

    Energy Technology Data Exchange (ETDEWEB)

    Becher, M; Joulakian, B [Universite Paul Verlaine-Metz, Laboratoire de Physique Moleculaire et des Collisions, Member FR CNRS 2843 Jean Barriol 1 Bd Arago, 57078 Metz Cedex 3 (France)

    2009-03-28

    The (e, 3e) process, producing hollow metastable Be{sup 2+}(2s{sup 2}) by very energetic electrons (>100 keV), is studied by using a relativistic procedure based on the application of the first term of the Born series for the determination of the corresponding fully differential cross section. The very fast projectile electron, impinging on the K shell of the neutral beryllium, is described by Dirac plane-wave solutions with the appropriate wave vectors. All atomic electrons and the two final-state-bound electrons are taken into account by non-relativistic Jastrow-type correlated functions. The two slow ejected electrons in the continuum are described by the fully correlated three-Coulomb (3C) function. The comparison of the results with those obtained by our recent non-relativistic approach shows the necessity of the introduction of the relativistic treatment.

  2. Krypton K-shell X-ray spectra recorded by the HENEX spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Seely, J.F. [Naval Research Laboratory, Space Science Division, Washington DC 20375 (United States)]. E-mail: john.seely@nrl.navy.mil; Back, C.A. [Lawrence Livermore National Laboratory, Livermore CA 94550 (United States); Constantin, C. [Lawrence Livermore National Laboratory, Livermore CA 94550 (United States); Lee, R.W. [Lawrence Livermore National Laboratory, Livermore CA 94550 (United States); Chung, H.-K. [Lawrence Livermore National Laboratory, Livermore CA 94550 (United States); Hudson, L.T. [National Institute of Standards and Technology, Gaithersburg MD 20899 (United States); Szabo, C.I. [National Institute of Standards and Technology, Gaithersburg MD 20899 (United States); Henins, A. [National Institute of Standards and Technology, Gaithersburg MD 20899 (United States); Holland, G.E. [SFA Inc., 9315 Largo Drive West Suite 200, Largo MD 20774 (United States); Atkin, R. [Tiger Innovations, L.L.C., 3610 Vacation Lane, Arlington VA 22207 (United States); Marlin, L. [Naval Research Laboratory, Space Science Division, Washington DC 20375 (United States)

    2006-05-15

    High-resolution X-ray spectra were recorded by the High-Energy Electronic X-ray (HENEX) spectrometer from a variety of targets irradiated by the Omega laser at the Laboratory for Laser Energetics. The HENEX spectrometer utilizes four reflection crystals covering the 1-20keV energy range and one quartz(10-11) transmission crystal (Laue geometry) covering the 11-40keV range. The time-integrated spectral images were recorded on five CMOS X-ray detectors. In the spectra recorded from krypton-filled gasbag and hohlraum targets, the helium-like K-shell transitions n=1-2, 1-3, and 1-4 appeared in the 13-17keV energy range. A number of additional spectral features were observed at energies lower than the helium-like n=1-3 and n=1-4 transitions. Based on computational simulations of the spectra using the FLYCHK/FLYSPEC codes, which included opacity effects, these additional features are identified to be inner-shell transitions from the Li-like through N-like krypton charge states. The comparisons of the calculated and observed spectra indicate that these transitions are characteristic of the plasma conditions immediately after the laser pulse when the krypton density is 2x10{sup 18}cm{sup -3} and the electron temperature is in the range 2.8-3.2keV. These spectral features represent a new diagnostic for the charge state distribution, the density and electron temperature, and the plasma opacity. Laboratory experiments indicate that it is feasible to record K-shell spectra from gold and higher Z targets in the >60keV energy range using a Ge(220) transmission crystal.

  3. Photoabsorption and desorption studies on thiophene-based polymers following sulphur K-shell excitation

    Energy Technology Data Exchange (ETDEWEB)

    Santa Rita, J.R.; Arantes, C.; Araujo, G. [Departamento de Fisico-Quimica, Universidade Federal do Rio de Janeiro, 21941-909 Rio de Janeiro, RJ (Brazil); Roman, L.S. [Departamento de Fisica, Universidade Federal do Parana, 81531-990 Curitiba, PR (Brazil); Micaroni, L. [Departamento de Quimica, Universidade Federal do Parana, 81531-990 Curitiba, PR (Brazil); Rocco, M.L.M., E-mail: luiza@iq.ufrj.br [Departamento de Fisico-Quimica, Universidade Federal do Rio de Janeiro, 21941-909 Rio de Janeiro, RJ (Brazil)

    2011-04-15

    Research highlights: {yields} Photon stimulated ion desorption (PSID) measurements at the S K-shell excitation energies were performed on three thiophene-based polymer films, following their NEXAFS spectra. {yields} For poly(thiophene) (PT) and poly(3-methylthiophene) (P3MT) it was found that the S 1s {yields} {pi}*, {sigma}* (S-C) excitation produces S{sup +} desorption efficiently, showing the importance of the resonant Auger process for breaking the C-S bond. {yields} In the case of poly(3-hexylthiophene) (P3HT) S{sup +} desorption seems to be suppressed due to the orientation of 3-hexyl side-chains on the surface. {yields} Desorption ion yield curves for molecular fragments reproduce the photoabsorption spectrum, indicating that the indirect process is here predominant. - Abstract: Photon stimulated ion desorption (PSID) and NEXAFS studies have been performed on thiophene-based polymers at the Brazilian Synchrotron Light Source following sulphur K-shell photoexcitation. For poly(thiophene) (PT) and poly(3-methylthiophene) (P3MT) it was found that the S 1s {yields} {pi}*, {sigma}{sup *} (S-C) excitation produces S{sup +} desorption efficiently. On the other hand, S{sup 2+} desorption is enhanced at higher energy excitations. These results are interpreted in terms of the Auger-stimulated ion desorption mechanism. For poly(3-hexylthiophene) (P3HT) S{sup +} desorption seems to be suppressed, which may be due to the hexyl side-chains. Desorption ion yield curves for molecular fragments reproduce the photoabsorption spectrum, being dominated by the indirect process.

  4. Electromagnetic Wave Absorption Properties of α-Fe /Nd2Fe14B Nanocomposites%纳米复相α-Fe /Nd2Fe14B材料电磁波吸收性能研究

    Institute of Scientific and Technical Information of China (English)

    连利仙; 邓龙江; 冯少东

    2007-01-01

    采用熔体快淬及晶化退火工艺制备了Nd2Fe14B/α-Fe纳米晶双相材料,对该材料在0.5~18 GHz频段的复介电常数、复磁导率进行了测试,其磁谱表现为驰豫型特征.由于磁损耗和介电损耗的共同作用,纳米复相Nd2Fe14B/α-Fe吸波材料在9~17 GHz具有良好的吸波性能,其匹配厚度为1.6~2.5 mm.%The α-Fe/Nd2Fe14B nanocomposites were prepared using a melt-spinning method and subsequent annealing treatment. The complex permittivity, permeability of composites was measured in the 0.5~18 GHz frequency range. The permeability spectra exhibits relaxation type characteristic. The α-Fe/Nd2Fe14B composites shows an excellent microwave absorption property (reflection loss: RL<-20 dB) in 9~17 GHz with thin matching thickness 1.6~2.5 mm due to the cooperate effect of magnetic loss and dielectric loss.

  5. Preparation and radar absorptive properties of BaFe12O19 -coated glass fiber

    Science.gov (United States)

    Jia, F.; Xu, M.; Bao, H. Q.; Cui, K.; Zhang, F.

    2016-07-01

    Traditional passive jamming materials such as chaff and foil showed some limitations in use because they can only reflect the electromagnetic wave. Therefore, to develop a kind of absorptive passive jamming material to make up for deficiencies of traditional passive jamming materials and improve the jamming efficiency is of great significance. In this paper, the BaFe12O19-coated glass fiber, used as a kind of radar absorptive chaff, was prepared by sol-gel dip-coating method. The effects of heat treatment temperature, heat treatment time and coating times on film quality, tensile strength and attenuation efficiency of the samples were discussed. The study shows that an increase of the heat treatment temperature and an extension of the heat treatment time is conducive to the growth of barium ferrite grain, while they would introduce the loss of chaff strength at the same time. In addition, multi-coating process can improve the film quality and attenuation efficiency of the sample. Data show that the 10 times coated samples have a best reflectivity of (15GHz, -6.65dB) and the bandwidth of reflectivity lower than -5dB is11.8 GHz. According to the test results, the prepared material has certain attenuation efficiency in the range of 2GHz-18GHz, having a high practical value.

  6. 1D magnetic materials of Fe₃O₄ and Fe with high performance of microwave absorption fabricated by electrospinning method.

    Science.gov (United States)

    Han, Rui; Li, Wei; Pan, Weiwei; Zhu, Minggang; Zhou, Dong; Li, Fa-shen

    2014-12-16

    Fe3O4 and Fe nanowires are successfully fabricated by electrospinning method and reduction process. Wiry microstructures were achieved with the phase transformation from α-Fe2O3 to Fe3O4 and Fe by partial and full reduction, while still preserving the wire morphology. The diameters of the Fe3O4 and Fe nanowires are approximately 50-60 nm and 30-40 nm, respectively. The investigation of microwave absorption reveals that the Fe3O4 nanowires exhibit excellent microwave absorbing properties. For paraffin-based composite containing 50% weight concentration of Fe3O4 nanowires, the minimum reflection loss reaches -17.2 dB at 6.2 GHz with the matching thickness of 5.5 mm. Furthermore, the calculation shows that the modulus of the ratio between the complex permittivity and permeability |ε/μ| is far away from unity at the minimum reflection loss point, which is quite different from the traditional opinions.

  7. Facile Preparation, Characterization, and Highly Effective Microwave Absorption Performance of CNTs/Fe3O4/PANI Nanocomposites

    Directory of Open Access Journals (Sweden)

    Deqing Zhang

    2013-01-01

    Full Text Available A facile method has been developed to synthesize light-weight CNTs/Fe3O4/PANI nanocomposites. The formation route was proposed as the coprecipitation of Fe2+ and Fe3+ and an additional process of in situ polymerization of aniline monomer. The structure and morphology of CNTs/Fe3O4/PANI were characterized by transmission electron microscopy (TEM, X-ray photoelectron spectroscopy (XPS, and Fourier transform infrared (FTIR spectroscopy. The TEM investigation shows that the CNTs/Fe3O4/PANI nanocomposites exhibit less intertwined structure and that many more Fe3O4 particles are attached homogeneously on the surface of CNTs, indicating that PANI can indeed help CNTs to disperse in isolated form. The wave-absorbing properties were investigated in a frequency of 2–18 GHz. The results show that the CNTs/Fe3O4/PANI nanocomposites exhibit a super absorbing behavior and possess a maximum reflection loss of −48 dB at 12.9 GHz, and the bandwidth below −20 dB is more than 5 GHz. More importantly, the absorption peak frequency ranges of the CNTs/Fe3O4/PANI composites can be tuned easily by changing the wax weight ratio and thickness of CNTs/Fe3O4/PANI paraffin wax matrix.

  8. Complex X-ray Absorption and the Fe K(alpha) Profile in NGC 3516

    Science.gov (United States)

    Turner, T. J.; Kraemer, S. B.; George, I. M.; Reeves, J. N.; Botorff, M. C.

    2004-01-01

    We present data from simultaneous Chandra, XMM-Newton and BeppoSAX observations of the Seyfert 1 galaxy NGC 3516, taken during 2001 April and November. We have investigated the nature of the very flat observed X-ray spectrum. Chandra grating data show the presence of X-ray absorption lines, revealing two distinct components of the absorbing gas, one which is consistent with our previous model of the UV/X-ray absorber while the other, which is outflowing at a velocity of approximately 1100 kilometers per second, has a larger column density and is much more highly ionized. The broad-band spectral characteristics of the X-ray continuum observed with XMM during 2001 April, reveal the presence of a third layer of absorption consisting of a very large column (approximately 2.5 x 10(exp 23) per square centimeter) of highly ionized gas with a covering fraction approximately 50%. This low covering fraction suggests that the absorber lies within a few 1t-days of the X-ray source and/or is filamentary in structure. Interestingly, these absorbers are not in thermal equilibrium with one another. The two new components are too highly ionized to be radiatively accelerated, which we suggest is evidence for a hydromagnetic origin for the outflow. Applying our model to the November dataset, we can account for the spectral variability primarily by a drop in the ionization states of the absorbers, as expected by the change in the continuum flux. When this complex absorption is accounted for we find the underlying continuum to be typical of Seyfert 1 galaxies. The spectral curvature attributed to the high column absorber, in turn, reduces estimates of the flux and extent of any broad Fe emission line from the accretion disk.

  9. Effect of graphene on far-infrared transmission and absorption of FeF2 photonic crystals

    Science.gov (United States)

    Gao, Ying; Zhou, Sheng; Fu, Shufang

    2017-10-01

    The influence of graphene (Gr) on the far-infrared transmission and absorption of FeF2 photonic crystals (PCs) is investigated by the forth-order transfer matrix since Gr is anisotropic when the external field is perpendicular to the surface of PCs. The numerical results show that the transmission and absorption spectra largely depend on the structural symmetry of Gr/FeF2 PCs and the position of Gr layer. The optimal structure and number of dielectric bi-layers (N) are discussed. In addition, the introduction of Gr leads to the disappearance of the defect modes in the band gap. Meanwhile, the line width of absorption around of the resonant frequencies of FeF2 has been extremely broadened, which is compared with the one of FeF2 PCs. Once N is beyond a critical value, the absorber will become the reflector. The effect of Fermi energy and external field on the absorption is also investigated.

  10. SERS active Ag encapsulated Fe@SiO2 nanorods in electromagnetic wave absorption and crystal violet detection.

    Science.gov (United States)

    Senapati, Samarpita; Srivastava, Suneel Kumar; Singh, Shiv Brat; Kulkarni, Ajit R

    2014-11-01

    The present work is focused on the preparation of Fe nanorods by the chemical reduction of FeCl3 (aq) using NaBH4 in the presence of glycerol as template followed by annealing of the product at 500°C in the presence of H2 gas flow. Subsequently, its surface has been modified by silica followed by silver nanoparticles to form silica coated Fe (Fe@SiO2) and Ag encapsulated Fe@SiO2 nanostructure employing the Stöber method and silver mirror reaction respectively. XRD pattern of the products confirmed the formation of bcc phase of iron and fcc phase of silver, though silica remained amorphous. FESEM images established the growth of iron nanorods from the annealed product and also formation of silica and silver coating on its surface. The appearance of the characteristics bands in FTIR confirmed the presence of SiO2 on the Fe surface. Magnetic measurements at room temperature indicated the ferromagnetic behavior of as prepared iron nanorods, Fe@SiO2 and silver encapsulated Fe@SiO2 nanostructures. All the samples exhibited strong microwave absorption property in the high frequency range (10GHz), though it is superior for Ag encapsulated Fe@SiO2 (-14.7dB) compared with Fe@SiO2 (-9.7dB) nanostructures of the same thickness. The synthesized Ag encapsulated Fe@SiO2 nanostructure also exhibited the SERS phenomena, which is useful in the detection of the carcinogenic dye crystal violet (CV) upto the concentration of 10(-10)M. All these findings clearly demonstrate that the Ag encapsulated Fe@SiO2 nanostructure could efficiently be used in the environmental remediation. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Electric field modulation of magnetic anisotropy and microwave absorption properties in Fe50Ni50/Teflon composite films

    Directory of Open Access Journals (Sweden)

    Zhenjun Xia

    2016-05-01

    Full Text Available Fe50Ni50 nanoparticle films with the size about 6 nm were deposited by a high energetic cluster deposition source. An electric field of about 0 - 40 kV was applied on the sample platform when the films were prepared. The field assisted deposition technique can dramatically induce in-plane magnetic anisotropy. To probe the microwave absorption properties, the Fe50Ni50 nanoparticles were deliberately deposited on the dielectric Teflon sheet. Then the laminated Fe50Ni50/Teflon composites were used to do reflection loss scan. The results prove that the application of electric field is an effective avenue to improve the GHz microwave absorption performance of our magnetic nanoparticles films expressed by the movement of reflection loss peak to high GHz region for the composites.

  12. Electric field modulation of magnetic anisotropy and microwave absorption properties in Fe50Ni50/Teflon composite films

    Science.gov (United States)

    Xia, Zhenjun; He, Jun; Ou, Xiulong; Wang, Yu; He, Shuli; Zhao, Dongliang; Yu, Guanghua

    2016-05-01

    Fe50Ni50 nanoparticle films with the size about 6 nm were deposited by a high energetic cluster deposition source. An electric field of about 0 - 40 kV was applied on the sample platform when the films were prepared. The field assisted deposition technique can dramatically induce in-plane magnetic anisotropy. To probe the microwave absorption properties, the Fe50Ni50 nanoparticles were deliberately deposited on the dielectric Teflon sheet. Then the laminated Fe50Ni50/Teflon composites were used to do reflection loss scan. The results prove that the application of electric field is an effective avenue to improve the GHz microwave absorption performance of our magnetic nanoparticles films expressed by the movement of reflection loss peak to high GHz region for the composites.

  13. Measurement and Correction of K-Shell Ionization Cross Sections for Copper and Gallium by Electron Impact

    Institute of Scientific and Technical Information of China (English)

    周长庚; 安竹; 罗正明

    2001-01-01

    The K-shell ionization cross sections of Cu and Ga are measured by electron impact and the data of Ga arereported for the first time. The method of a thin chemical compound target with a thick substrate is formallyused in the experiment. The influence of electrons reflected from the substrate is corrected by means of acalculation of electron transport.

  14. Microwave absorption of sandwich structure based on nanocrystalline SrFe12O19, Ni0.5ZnO.5Fe2O4 and alpha-Fe hollow microfibers.

    Science.gov (United States)

    Yang, Xinchun; Jing, Maoxiang; Shen, Xiangqian; Meng, Xianfeng; Dong, Mingdong; Huang, Daqing; Wang, Yingde

    2014-03-01

    The microwave absorption properties of sandwich structural absorbers based on the nanocrystalline strontium ferrite (SrFe12O19), NiZn ferrite (Ni0.5Zn0.5Fe2O4) and alpha-iron (alpha-Fe) hollow microfibers with diameters of 1-3 microm have been investigated in the frequency range of 2-18 GHz. The sandwich absorbers composed of nanocrystalline ferrite hollow microfibers as the outer or inner layer, and the nanocrystalline alpha-Fe hollow microfibers as the interlayer, have strong microwave absorption with a broad band and thin thickness. Their microwave absorption properties in 2-18 GHz are mainly influenced by the arrangement, each layer thickness and total thickness. It finds that the sandwich absorber with 1.6 mm thick SrFe12O19 microfibers as the outer layer, 0.2 mm thick alpha-Fe microfibers as the interlayer and 0.2 mm thick Ni0.5Zn0.5Fe2O4 microfibers as the inner layer, exhibits an optimal reflection loss (RL) value of -120.1 dB at 13.2 GHz and the bandwidth with RL exceeding -10 dB covers 83% of X-band (8.2-12.4 GHz) and the whole K(u)-band (12.4-18 GHz). This enhancement microwave absorption can be attributed to the unique coupling of the nanocrystalline ferrite and alpha-Fe hollow microfibers arising from the shape anisotropy, interface and small size effects.

  15. High-Pressure Evolution of Fe2O3 Electronic Structure Revealed by X-ray Absorption

    Energy Technology Data Exchange (ETDEWEB)

    Kao, Chi-Chang

    2011-08-12

    We report the first high pressure measurement of the Fe K-edge in hematite (Fe{sub 2}O{sub 3}) by X-ray absorption spectroscopy in partial fluorescence yield geometry. The pressure-induced evolution of the electronic structure as Fe{sub 2}O{sub 3} transforms from a high-spin insulator to a low-spin metal is reflected in the x-ray absorption pre-edge. The crystal field splitting energy was found to increase monotonically with pressure up to 48 GPa, above which a series of phase transitions occur. Atomic multiplet, cluster diagonalization, and density-functional calculations were performed to simulate the pre-edge absorption spectra, showing good qualitative agreement with the measurements. The mechanism for the pressure-induced phase transitions of Fe{sub 2}O{sub 3} is discussed and it is shown that ligand hybridization significantly reduces the critical high-spin/low-spin gap pressure.

  16. Influence of MnO2 decorated Fe nano cauliflowers on microwave absorption and impedance matching of polyvinylbutyral (PVB) matrix

    Science.gov (United States)

    Bora, Pritom J.; Porwal, Mayuri; Vinoy, K. J.; Ramamurthy, Praveen C.; Madras, Giridhar

    2016-09-01

    In this work, a promising, polyvinyl butryl (PVB)-MnO2 decorated Fe composite was synthesised and microwave absorption properties were studied for the most important frequency ranges i.e., X-band (8.2-12.4 GHz) and Ku-band (12.4-18 GHz). The microwave absorption of Fe nano cauliflower structure can be enhanced by MnO2 nanofiber coating. 10 wt% Fe-MnO2 nano cauliflower loaded PVB composite films (2 mm thick) shows an appreciable increase in microwave absorption properties. In X-band, the reflection loss (RL) of this composite decreases almost linearly to -7.5 dB, whereas in the Ku-band the minimum RL was found to be -15.7 dB at 14.7 GHz. Here it was observed that impedance matching is the primarily important factor responsible for enhanced microwave absorption. Further, enhancement of EM attenuation constant (α), dielectrics, scattering attenuation also bolsters the obtained results. This polymer composite can be considered as a novel microwave absorbing coating material.

  17. Excited state assisted three-photon absorption based optical limiting in nanocrystalline Cu2Se and FeSe2

    Science.gov (United States)

    Anand, Benoy; Molli, Muralikrishna; Aditha, Saikiran; Mimani Rattan, Tanu; Siva Sankara Sai, S.; Kamisetti, Venkataramaniah

    2013-09-01

    Transition metal selenides (FeSe2 and Cu2Se) are synthesized by the hydrothermal co-reduction method. XRD results revealed the crystalline nature of their single phase and the elemental compositions are obtained using EDS. TEM images of the as-prepared samples show the formation of nanorods of 10-20 nm diameter in case of iron selenide and nanoparticles of 10-35 nm diameter in case of copper selenide. The energy bandgap values are calculated using tauc plots obtained from UV-Visible absorption spectra. The open aperture Z-scan measurements carried out using 5 ns pulses at 532 nm revealed that the samples showed excellent optical limiting behavior owing to strong nonlinear absorption (NLA). Through numerical simulations, the mechanism of NLA is found to be effective three-photon absorption which has significant contribution from excited state absorption.

  18. Electronic structure and characteristics of Fe 3d valence states of Fe(1.01)Se superconductors under pressure probed by x-ray absorption spectroscopy and resonant x-ray emission spectroscopy.

    Science.gov (United States)

    Chen, J M; Haw, S C; Lee, J M; Chen, S A; Lu, K T; Deng, M J; Chen, S W; Ishii, H; Hiraoka, N; Tsuei, K D

    2012-12-28

    The electronic structure and characteristics of Fe 3d valence states of iron-chalcogenide Fe(1.01)Se superconductors under pressure were probed with x-ray absorption spectroscopy and resonant x-ray emission spectroscopy (RXES). The intensity of the pre-edge peak at ~7112.7 eV of the Fe K-edge x-ray absorption spectrum of Fe(1.01)Se decreases for pressure from 0.5 GPa increased to 6.9 GPa. The satellite line Kβ' was reduced in intensity upon applying pressure and became absent for pressure 52 GPa. Fe(1.01)Se shows a small net magnetic moment of Fe(2+), likely arising from strong Fe-Fe spin fluctuations. The 1s3p-RXES spectra of Fe(1.01)Se at pressures 0.5, 6.9, and 52 GPa recorded at the Fe K-edge reveal that unoccupied Fe 3d states exhibit a delocalized character, stemming from hybridization of Fe 3d and 4p orbitals arising from a local distortion around the Fe atom in a tetrahedral site. Application of pressure causes suppression of this on-site Fe 3d-Fe 4p hybridization, and thereby decreases the intensity of the pre-edge feature in the Fe K-edge absorption spectrum of Fe(1.01)Se. Compression enhances spin fluctuations at Fe sites in Fe(1.01)Se and increases the corresponding T(c), through a competition between nearest-neighbor ferromagnetic and next-nearest-neighbor antiferromagnetic superexchange interactions. This result aids our understanding of the physics underlying iron-based superconductors.

  19. A vortex line for K-shell ionization of a carbon atom by electron impact

    Science.gov (United States)

    Ward, S. J.; Macek, J. H.

    2014-10-01

    We obtained using the Coulomb-Born approximation a deep minimum in the TDCS for K-shell ionization of a carbon atom by electron impact for the electron ejected in the scattering plane. The minimum is obtained for the kinematics of the energy of incident electron Ei = 1801.2 eV, the scattering angle θf = 4°, the energy of the ejected electron Ek = 5 . 5 eV, and the angle for the ejected electron θk = 239°. This minimum is due to a vortex in the velocity field. At the position of the vortex, the nodal lines of Re [ T ] and Im [ T ] intersect. We decomposed the CB1 T-matrix into its multipole components for the kinematics of a vortex, taking the z'-axis parallel to the direction of the momentum transfer vector. The m = +/- 1 dipole components are necessary to obtain a vortex. We also considered the electron to be ejected out of the scattering plane and obtained the positions of the vortex for different values of the y-component of momentum of the ejected electron, ky. We constructed the vortex line for the kinematics of Ei = 1801.2 eV and θf = 4°. S.J.W. and J.H.M. acknowledge support from NSF under Grant No. PHYS- 0968638 and from D.O.E. under Grant Number DE-FG02-02ER15283, respectively.

  20. Laboratory measurements of K-shell transitions in highly charged iron ions

    Science.gov (United States)

    Steinbrügge, René; Rudolph, Jan K.; Bernitt, Sven; Crespo López-Urrutia, José R.

    2016-09-01

    The x-ray spectra of celestial sources show a plethora of features originating from highly charged ions. These can be used to determine the flow, temperatures, and abundances of elements in the star, which are needed to benchmark-stellar evolution models. However, the underlying atomic transition data of the ions are often only known by theoretical calculations, thus testing them in laboratory measurements is crucial. We present our measurements of energies, natural linewidths, radiative and Auger decay rates for K-shell transitions in He-like to F-like iron ions. In this experiments, an electron beam ion trap was used to create a target of highly charged ions, which were resonantly excited by monochromatic light from the PETRA III synchrotron radiation source. Fluorescence was observed while simultaneously detecting photoionization by the change in the ionic charge state. This method, combined with the high resolution of the monochromator used, yields uncertainties on the ppm-level for the excitation energies and below 10% for the linewidths and transition rates, thus providing a valuable benchmark for atomic theory.

  1. Alloying effect on K-shell fluorescence parameters of porous NiTi shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Cengiz, E., E-mail: erhan_cengiz@ktu.edu.tr [Karadeniz Technical University, Science Faculty, Department of Physics, 61080 Trabzon (Turkey); Ozkendir, O.M. [Mersin University, Tarsus Faculty of Technology, Tarsus (Turkey); Kaya, M. [Adiyaman University, Department of Material Science Engineering, 02040 Adiyaman (Turkey); Tirasoglu, E. [Karadeniz Technical University, Science Faculty, Department of Physics, 61080 Trabzon (Turkey); Karahan, I.H. [Mustafa Kemal University, Faculty of Arts and Sciences, Department of Physics, Antakya, Hatay (Turkey); Kimura, S.; Hajiri, T. [UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585 (Japan)

    2014-01-01

    Highlights: • The K{sub α,β} shell production cross-sections and K{sub β}/K{sub α} intensity ratios of porous NiTi SMAs were determined by ED-XRF. • To analyze the changes in the structures due to the preheating and solution heat treatment processes, XRD and XPS measurements were also performed. • The deviations between the experimental and theoretical were interpreted to charge transfer phenomena. - Abstract: The K{sub α,β} shell production cross-sections and K{sub β}/K{sub α} intensity ratios of porous Ni −49 at% Ti shape memory alloys were determined using energy dispersive X-ray fluorescence (EDXRF) technique. Also, the alloying effect on the K shell fluorescence parameters was investigated. The samples were excited by 59.5 keV γ-rays from an {sup 241}Am annular radioactive source. The K X-rays emitted by the samples were counted by an Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV. The structure analyses of the samples were also made using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The deviations between the present results and theoretical values, calculated for pure Ti and Ni, were attributed to charge transfer phenomena and/or rearrangement of valance shell electrons and porosity.

  2. Laboratory study of K-shell photoionization of oxygen and oxygen hydrides ions

    Science.gov (United States)

    Bizau, Jean-Marc

    2016-05-01

    The interpretation of the spectra sent by satellites required the knowledge of many atomic data, including photoionization cross sections or energy and oscillator strength of bound-bound transitions for many ions, over a broad photon energy range going from infra-red to x-rays. These data are mainly provided by theoretical results using state-of-the-art methods like R-matrix. Recently, discrepancies have been observed between the calculated energy of the Kα transitions in atomic oxygen and its ions and those determined from the satellites observations. The results of the experimental studies of K-shell photoionization of oxygen ions performed at the French synchrotron radiation center SOLEIL will be presented. A merged-beam setup installed on the PLEIADES beam line allows for the determination of absolute photoionization cross sections and transitions energy on singly- and multiply-charged ions in the 10-1000 eV photon energy range. The first results obtained with this setup on oxygen hydrides will be also presented.

  3. K-shell spectroscopy in hot plasmas: Stark effect, Breit interaction and QED corrections

    CERN Document Server

    Pain, Jean-Christophe; Comet, Maxime; Gilles, Dominique

    2016-01-01

    The broadening of lines by Stark effect is widely used for inferring electron density and temperature in plasmas. Stark-effect calculations often rely on atomic data (transition rates, energy levels,...) not always exhaustive and/or valid only for isolated atoms. In this work, we first present a recent development in the detailed opacity code SCO-RCG for K-shell spectroscopy. The approach is adapted from the work of Gilles and Peyrusse. Neglecting non-diagonal terms in dipolar and collision operators, the line profile is expressed as a sum of Voigt functions associated to the Stark components. The formalism relies on the use of parabolic coordinates and the relativistic fine-structure of Lyman lines is included by diagonalizing the hamiltonian matrix associated to quantum states having the same principal quantum number n. The SCO-RCG code enables one to investigate plasma environment effects, the impact of the microfield distribution, the decoupling between electron and ion temperatures and the role of satell...

  4. Double K-shell ionization accompanying the internal conversion of the 0.145-MeV transition in 141Pr

    Science.gov (United States)

    Nagy, H. J.; Schupp, G.

    1985-12-01

    Double ionization of the atomic K shell accompanying the K-shell internal conversion of the 0.145-MeV transition of 141Pr has been studied by recording coincidences between Kα satellite x rays and Kα hypersatellite x rays emitted when the double vacancies are filled. The probability per K-shell internal conversion that a double vacancy is formed, PKK(IC), was found to be (3.4+/-0.3)×10-5, which is a factor of (0.79+/-0.07) times the theoretical prediction for K-shell electron shakeoff in K-shell internal conversion of Mukoyama and Shimizu. The Kα1 to Kα2 hyper- satellite ratio was found to be (1.50+/-0.13), a value which is about 6% less than the calculation of Åberg et al.

  5. Field-induced microwave absorption in Fe3O4 nanoparticles and Fe3O4/polyaniline composites synthesized by different methods

    Science.gov (United States)

    Kurlyandskaya, G. V.; Cunanan, Jessica; Bhagat, S. M.; Aphesteguy, J. C.; Jacobo, S. E.

    2007-08-01

    Three kinds of nanoscale powders containing Fe3O4 nanoparticles (NPs) have been studied by ferromagnetic resonance (FMR): (i) Fe3O4 NPs grown and then covered with polyaniline (PANI), (ii) unclad Fe3O4 NPs, and (iii) Fe3O4 NPs grown “in situ” with the PANI. In every case, there is no low field microwave absorption, rather a single FMR line is observed. However, the half-power widths are of order of 1 kOe presumably due to a distribution of internal fields. For type I particles with a low concentration (below 40%) of Fe3O4, the observed resonance fields (Hr) are close to those expected for spheres with negligible magnetocrystalline anisotropy. For all other cases, Hr values are significantly lower. Such shortfalls can be roughly understood by invoking dipolar interactions between the grains, stresses frozen in grains during manufacture (method III), as well as anisotropy fields when the specimens are prepared in an aligning field.

  6. Physical and optical absorption studies of Fe{sup 3+} - ions doped lithium borate glasses containing certain alkaline earths

    Energy Technology Data Exchange (ETDEWEB)

    Bhogi, Ashok [VNR Vignana Jyothi Institute of Engineering and Technology, Hyderabad, Telangana (India); Kumar, R. Vijaya [School of Physics, University of Hyderabad, Hyderabad, Telangana (India); Kistaiah, P., E-mail: pkistaiah@yahoo.com [Department of Physics, Osmania University, Hyderabad, Telangana (India)

    2016-05-23

    Iron ion doped lithium borate glasses with the composition 15RO-25Li{sub 2}O-59B{sub 2}O{sub 3}-1Fe{sub 2}O{sub 3} (where R= Ca, Sr and Ba) have been prepared by the conventional melt quenching technique and characterized to investigate the physical and optical properties using XRD, density, molar volume and UV-Visible spectroscopy. The optical absorption spectra exhibit a band at around 460 nm which is assigned to {sup 6}A{sub 1g}(S) → 4E{sub g} (G) of Fe{sup 3+} ions with distorted octahedral symmetry. From ultraviolet absorption edges, the optical band gap and Urbach energies have been evaluated. The effect of alkaline earths on these properties is discussed.

  7. Physical and optical absorption studies of Fe3+ - ions doped lithium borate glasses containing certain alkaline earths

    Science.gov (United States)

    Bhogi, Ashok; Kumar, R. Vijaya; Kistaiah, P.

    2016-05-01

    Iron ion doped lithium borate glasses with the composition 15RO-25Li2O-59B2O3-1Fe2O3 (where R= Ca, Sr and Ba) have been prepared by the conventional melt quenching technique and characterized to investigate the physical and optical properties using XRD, density, molar volume and UV-Visible spectroscopy. The optical absorption spectra exhibit a band at around 460 nm which is assigned to 6A1g(S) → 4Eg (G) of Fe3+ ions with distorted octahedral symmetry. From ultraviolet absorption edges, the optical band gap and Urbach energies have been evaluated. The effect of alkaline earths on these properties is discussed.

  8. Changes in the electronic structure of highly compressed iron revealed by X-ray fluorescence lines and absorption edges

    Science.gov (United States)

    Hansen, S. B.; Harding, E. C.; Knapp, P. F.; Gomez, M. R.; Nagayama, T.; Bailey, J. E.

    2017-09-01

    We present high-resolution spectroscopic data from iron impurities in beryllium liners driven by Sandia's Z machine to temperatures near 10 eV and electron densities near 2 × 1024 cm-3, conditions independently diagnosed from the transmission depth and shape of the iron K-edge. A 12-eV redshift is observed in the Fe Kβ fluorescence line along with few-eV shifts in the Fe Kα lines and Fe K-shell absorption edge. While the measured edge shift disagrees with several common models of ionization potential depression, both line and edge shifts are in good agreement with the predictions of a self-consistent model based on density functional theory.

  9. Electron-ion recombination measurements motivated by AGN X-ray absorption features: Fe XIV forming Fe XIII

    CERN Document Server

    Schmidt, E W; Müller, A; Lestinsky, M; Sprenger, F; Grieser, M; Repnow, R; Wolf, A; Brandau, C; Lukic, D; Schnell, M; Savin, D W

    2006-01-01

    Recent spectroscopic models of active galactic nuclei (AGN) have indicated that the recommended electron-ion recombination rate coefficients for iron ions with partially filled M-shells are incorrect in the temperature range where these ions form in photoionized plasmas. We have investigated this experimentally for Fe XIV forming Fe XIII. The recombination rate coefficient was measured employing the electron-ion merged beams method at the Heidelberg heavy-ion storage-ring TSR. The measured energy range of 0-260 eV encompassed all dielectronic recombination (DR) 1s2 2s2 2p6 3l 3l' 3l'' nl''' resonances associated with the 3p1/2 -> 3p3/2, 3s -> 3p, 3p -> 3d and 3s -> 3d core excitations within the M-shell of the Fe XIV 1s2 2s2 2p6 3s2 3p parent ion. This range also includes the 1s2 2s2 2p6 3l 3l' 4l'' nl''' resonances associated with 3s -> 4l'' and 3p -> 4l'' core excitations. We find that in the temperature range 2--14 eV, where Fe XIV is expected to form in a photoionized plasma, the Fe XIV recombination rate...

  10. Microwave absorption properties of polyaniline-Fe3O4/ZnO-polyester nanocomposite: Preparation and optimization

    Science.gov (United States)

    Dorraji, M. S. Seyed; Rasoulifard, M. H.; Khodabandeloo, M. H.; Rastgouy-Houjaghan, M.; Zarajabad, H. Karimi

    2016-03-01

    New nanocomposites have been successfully prepared based on polyester resin, including various metal oxides (ZnO nanorod bundles, Fe3O4 nanoparticles, and nano Fe3O4/ZnO) and Polyaniline (PANI) synthesized with different dopants. The microwave absorption properties of nanocomposites were investigated in X-band range. The Taguchi experimental design was used to study the effects of the type of metal oxide and that of PANI (doped with various acids) and the weight percent of metal oxide in PANI and that of filler (metal oxide and PANI) in polyester matrix on the microwave absorption properties with the absorber thickness of only 2 mm. The weight percent of metal oxide in PANI was found to be the most significant parameter, accounting for 45.611% of the total contribution of the four selected parameters. Fe3O4/ZnO as inorganic oxide, PTSA as dopant of PANI, 25 wt.% for inorganic oxide in PANI, and filler in the polyester matrix were selected as optimum conditions by Taguchi method. The sample prepared in optimal conditions had reflection loss of less than -10 dB (absorption >90%) and covering a frequency range of 8.4-11.6 GHz.

  11. X-ray absorption and magnetic circular dichroism studies of Co2FeAl in magnetic tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Ebke, D.; Kugler, Z.; Thomas, P.; Schebaum, O.; Schafers, M.; Nissen, D.; Schmalhorst, J.; Hutten, A.; Arenholz, E.; Thomas, A.

    2010-01-11

    The bulk magnetic moment and the element specific magnetic moment of Co{sub 2}FeAl thin films were examined as a function of annealing temperature by alternating gradient magnetometer (AGM) and X-ray absorption spectroscopy (XAS)/X-ray magnetic circular dichroism (XMCD), respectively. A high magnetic moment can be achieved for all annealing temperatures and the predicted bulk and interface magnetic moment of about 5 {tilde A}{sub B} are reached via heating. We will also present tunnel magnetoresistance (TMR) values of up to 153% at room temperature and 260% at 13 K for MgO based magnetic tunnel junctions (MTJs) with Co{sub 2}FeAl and Co-Fe electrodes.

  12. Extended X-ray absorption fine structure studies of Zn2Fe2 hybrid hemoglobins: absence of heme bond length changes in half-ligated species.

    Science.gov (United States)

    Simolo, K; Korszun, Z R; Stucky, G; Moffat, K; McLendon, G; Bunker, G

    1986-07-01

    Metal hybrid hemoglobins, in which Zn(II) replaces Fe(II), have been structurally characterized by extended X-ray absorption structure (EXAFS) studies. Since Zn and Fe have very different K absorption edge energies, the structures of the ligated (Fe) and unligated (Zn) sites could be examined independently within a single molecule that mimics an intermediate ligation state. The observed EXAFS spectra and associated structural parameters are compared among the ligand free (alpha Zn)2(beta Zn)2, half-ligated (alpha FeCO)2(beta Zn)2 and (alpha Zn)2(beta FeCO)2, and fully ligated (alpha FeCO)2(beta FeCO)2 systems.

  13. Synthesis and microwave absorption properties of graphene-oxide(GO)/polyaniline nanocomposite with Fe3O4 particles

    Institute of Scientific and Technical Information of China (English)

    耿欣; 何大伟; 王永生; 赵文; 周亦康; 李树磊

    2015-01-01

    In order to investigate the impedance matching properties of microwave absorbers, the ternary nanocomposites of GO/PANI/Fe3O4 (GPF) are prepared via a two-step method, GO/PANI composites are synthesized by dilute polymerization in the presence of aniline monomer and GO, and GO/PANI/Fe3O4 is prepared via a co-precipitation method. The obtained nanocomposites are characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR), respectively. The microwave absorbability reveals enhanced microwave absorption properties compared with GO, PANI, and GO/PANI. The maximum reflection loss of GO/PANI/Fe3O4 is up to−27 dB at 14 GHz with its thickness being 2 mm, and its absorption bandwidths exceeding−10 dB are more than 11.2 GHz with its thickness values being in a range of 1.5 mm–4 mm. It provides that GO/PANI/Fe3O4 can be used as an attractive candidate for microwave absorbers.

  14. K-shell decomposition reveals hierarchical cortical organization of the human brain

    Science.gov (United States)

    Lahav, Nir; Ksherim, Baruch; Ben-Simon, Eti; Maron-Katz, Adi; Cohen, Reuven; Havlin, Shlomo

    2016-08-01

    In recent years numerous attempts to understand the human brain were undertaken from a network point of view. A network framework takes into account the relationships between the different parts of the system and enables to examine how global and complex functions might emerge from network topology. Previous work revealed that the human brain features ‘small world’ characteristics and that cortical hubs tend to interconnect among themselves. However, in order to fully understand the topological structure of hubs, and how their profile reflect the brain’s global functional organization, one needs to go beyond the properties of a specific hub and examine the various structural layers that make up the network. To address this topic further, we applied an analysis known in statistical physics and network theory as k-shell decomposition analysis. The analysis was applied on a human cortical network, derived from MRI\\DSI data of six participants. Such analysis enables us to portray a detailed account of cortical connectivity focusing on different neighborhoods of inter-connected layers across the cortex. Our findings reveal that the human cortex is highly connected and efficient, and unlike the internet network contains no isolated nodes. The cortical network is comprised of a nucleus alongside shells of increasing connectivity that formed one connected giant component, revealing the human brain’s global functional organization. All these components were further categorized into three hierarchies in accordance with their connectivity profile, with each hierarchy reflecting different functional roles. Such a model may explain an efficient flow of information from the lowest hierarchy to the highest one, with each step enabling increased data integration. At the top, the highest hierarchy (the nucleus) serves as a global interconnected collective and demonstrates high correlation with consciousness related regions, suggesting that the nucleus might serve as a

  15. Formation mechanism of LiFePO 4/C composite powders investigated by X-ray absorption spectroscopy

    Science.gov (United States)

    Hsu, Kuei-Feng; Hu, Shao-Kang; Chen, Chinh-Hsiang; Cheng, Ming-Yao; Tsay, Sun-Yuan; Chou, Tse-Chuan; Sheu, Hwo-Shuenn; Lee, Jyh-Fu; Hwang, Bing-Joe

    The local structure and oxidation states for both the precursors and the LiFePO 4/C composite powders were investigated by X-ray absorption spectroscopy (XAS) to provide a deep insight into their formation mechanism. It was found that the local structure and oxidation states of the precursors and the synthesized LiFePO 4/C powders as well as the electrochemical properties of the synthesized powders were strongly influenced by the R ratio (R: molar ratio of citric acid to total metal ions). The oxidation states of iron ions of the precursors for R = 1 and 0.75 consist mainly of Fe(II) and traces of Fe(III). However, the oxidation state of iron ions of the precursor for R = 0.5 comprises mainly of Fe(III). The oxidation state of iron ions of all the synthesized powders is Fe(II). The structure of the precursors and the synthesized powders for R = 1 and 0.75 is more ordering than that for R = 0.5. It is in good agreement with the observation of the cation mixing obtained from the Riteveld analysis of the XRD data. The better the electrochemical performance is, the more ordering the structure or the less the cation mixing. However, the effect of the R values on the carbon content is also essential for the electrochemical properties of the synthesized LiFePO 4/C composite powders. Increasing the carbon content leads to the increase in the electronic conductivity but impedes the Li + ion diffusion of the composite materials. Consequently, the powders synthesized at the optimal R ratio of 0.75 exhibited the highest initial capacity, about 150 mAh g -1 when cycled at 1/40 C rate at room temperature. The structural scheme of the precursors and the synthesized powders and the formation mechanism of the LiFePO 4/C composite powders are also addressed in this work.

  16. Preliminary Measurement of the K-Shell Ionization Cross Sections of Ti by Positron Impact in the Low Energy Region

    Institute of Scientific and Technical Information of China (English)

    田丽霞; 刘慢天; 朱敬军; 安竹; 王宝义; 秦秀波

    2012-01-01

    Measurements were performed of K-shell ionization cross sections of Ti element by 10~30 keV positron impact using the thick-target method. The effects of multiple scattering of incident positron and from bremsstrahlung photons and annihilation photons with the thick-target method are discussed with the Monte Carlo code PENELOPE. Meanwhile, the Monte Carlo method is also applied to determine the detection efficiencies of X- and γ-ray detectors. Our experimental K-shell ionization cross sections for Ti element are compared with the distorted-wave Born approximation (DWBA) theoretical predictions, and it is found that the agreement of the experimental data and theoretical values is good and this indicates that the experimental method adopted in this study is applicable.

  17. Metastable innershell molecular state (MIMS) III: The universal binding energy and bond length of the homonucleus K-shell MIMS

    Science.gov (United States)

    Bae, Young K.

    2016-03-01

    This paper reports the discovery of a universal Z2-dependency of the binding energy of the homonucleus K-shell MIMS (K-MIMS: Metastable Innershell Molecular State bound by K-shell electrons), which has been established by analyzing extensive existing experimental data over several decades. An intuitive analytical theory on the K-MIMS has been developed for the homologous molecules to the He*2 excimer, which elucidates the universal Z-dependent behavior of the K-MIMS. The theory predicts a 1 / Z-dependency of the K-MIMS bond length, which is in agreement with the quasimolecule sizes estimated from the x-ray generation cross-sections in H-like Bi82+ and U91+ impact on Au solids.

  18. A non-LTE kinetic model for quick analysis of K-shell spectra from Z-pinch plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Li, J., E-mail: s.duan@163.com; Huang, X. B., E-mail: s.duan@163.com; Cai, H. C., E-mail: s.duan@163.com; Yang, L. B., E-mail: s.duan@163.com; Xie, W. P., E-mail: s.duan@163.com; Duan, S. C., E-mail: s.duan@163.com [Key Lab of Pulsed Power, Institute of Fluid Physics, CAEP, P.O. Box 919-108, Mianyang, Sichuan 621999 (China)

    2014-12-15

    Analyzing and modeling K-shell spectra emitted by low-to moderate-atomic number plasma is a useful and effective way to retrieve temperature density of z-pinch plasmas. In this paper, a non-LTE population kinetic model for quick analysis of K-shell spectra was proposed. The model contains ionization stages from bare nucleus to neutral atoms and includes all the important atomic processes. In the present form of the model, the plasma is assumed to be both optically thin and homogeneous with constant temperature and density, and only steady-state situation is considered. According to the detailed calculations for aluminum plasmas, contours of ratios of certain K-shell lines in electron temperature and density plane as well as typical synthesized spectra were presented and discussed. The usefulness of the model is demonstrated by analyzing the spectrum from a neon gas-puff Z-pinch experiment performed on a 1 MA pulsed-power accelerator.

  19. A new method to measure iron absorption from the enrichment of 57Fe and 58Fe in young erythroid cells

    NARCIS (Netherlands)

    Heuvel, E.G.H.M. van den; Muys, T.; Pellegrom, H.; Bruyntjes, J.P.; Dokkum, W. van; Spanhaak, S.; Schaafsma, G.

    1998-01-01

    Iron absorption can be measured by the incorporation of stable iron isotopes into erythrocytes, 14 days after isotope administration. The disadvantage of this method is the high dose of isotopes needed to obtain a sufficient enrichment. Therefore, in this study cell fractions rich in young erythroid

  20. In search of metal hydrides: an X-ray absorption and emission study of [NiFe] hydrogenase model complexes.

    Science.gov (United States)

    Hugenbruch, Stefan; Shafaat, Hannah S; Krämer, Tobias; Delgado-Jaime, Mario Ulises; Weber, Katharina; Neese, Frank; Lubitz, Wolfgang; DeBeer, Serena

    2016-04-28

    Metal hydrides are invoked as important intermediates in both chemical and biological H2 production. In the [NiFe] hydrogenase enzymes, pulsed EPR and high-resolution crystallography have argued that the hydride interacts primarily at the Ni site. In contrast, in [NiFe] hydrogenase model complexes, it is observed that the bridging hydride interacts primarily with the Fe. Herein, we utilize a combination of Ni and Fe X-ray absorption (XAS) and emission (XES) spectroscopies to examine the contribution of the bridging hydride to the observed spectral features in [(dppe)Ni(μ-pdt)(μ-H)Fe(CO)3](+). The corresponding data on (dppe)Ni(μ-pdt)Fe(CO)3 are used as a reference for the changes that occur in the absence of a hydride bridge. For further interpretation of the observed spectral features, all experimental spectra were calculated using a density functional theory (DFT) approach, with excellent agreement between theory and experiment. It is found that the iron valence-to-core (VtC) XES spectra reveal clear signatures for the presence of a Fe-H interaction in the hydride bridged model complex. In contrast, the Ni VtC XES spectrum largely reflects changes in the local Ni geometry and shows little contribution from a Ni-H interaction. A stepwise theoretical analysis of the hydride contribution and the Ni site symmetry provides insights into the factors, which govern the different metal-hydride interactions in both the model complexes and the enzyme. Furthermore, these results establish the utility of two-color XES to reveal important insights into the electronic structure of various metal-hydride species.

  1. Orbital Symmetry of Ba(Fe1-xCox)2As2 Superconductors Probed with X-ray Absorption Spectroscopy

    OpenAIRE

    Cheney, C. Parks; Bondino, F.; Callcott, T. A.; Vilmercati, P.; Ederer, D.; Magnano, E.; Malvestuto, M.; Parmigiani, F.; Sefat, A. S.; McGuire, M. A.; Jin, R; Sales, B. C.; Mandrus, D; Singh, D.J.; Freeland, J. W.

    2010-01-01

    The orbital symmetries of electron doped iron-arsenide superconductors Ba(Fe1-xCox)2As2 have been measured with x-ray absorption spectroscopy. The data reveal signatures of Fe d electron itinerancy, weak electronic correlations, and a high degree of Fe-As hybridization related to the bonding topology of the Fe dxz+yz states, which are found to contribute substantially at the Fermi level. The energies and detailed orbital character of Fe and As derived unoccupied s and d states are found to be...

  2. Highly Ionized Fe-K Absorption Line from Cygnus X-1 in the High/Soft State Observed with Suzaku

    CERN Document Server

    Yamada, S; Mineshige, S; Ueda, Y; Kubota, A; Gandhi, P; Done, C; Noda, H; Yoshikawa, A; Makishima, K

    2013-01-01

    We present observations of a transient He-like Fe K alpha absorption line in Suzaku observations of the black hole binary Cygnus X-1 on 2011 October 5 near superior conjunction during the high/soft state, which enable us to map the full evolution from the start and the end of the episodic accretion phenomena or dips for the first time. We model the X-ray spectra during the event and trace their evolution. The absorption line is rather weak in the first half of the observation, but instantly deepens for ~10 ks, and weakens thereafter. The overall change in equivalent width is a factor of ~3, peaking at an orbital phase of ~0.08. This is evidence that the companion stellar wind feeding the black hole is clumpy. By analyzing the line with a Voigt profile, it is found to be consistent with a slightly redshifted Fe XXV transition, or possibly a mixture of several species less ionized than Fe XXV. The data may be explained by a clump located at a distance of ~10^(10-12) cm with a density of ~10^((-13)-(-11)) g cm^-...

  3. Local structure of Fe-doped In{sub 2}O{sub 3} films investigated by X-ray absorption fine structure spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    An, Yukai; Wang, Shiqi; Feng, Deqiang; Liu, Jiwen [Key Laboratory of Display Materials and Photoelectric Devices, Ministry of Education, Tianjin (China); Tianjin Key Laboratory for Photoelectric Materials and Devices, Tianjin (China); Tianjin University of Technology, School of Material Science and Engineering, Tianjin (China); Wu, Zhonghua [Chinese Academy of Sciences, Beijing Synchrotron Radiation Facility (BSRF), Institute of High Energy Physics, Beijing (China)

    2014-06-15

    (In{sub 1-x}Fe{sub x}){sub 2}O{sub 3} (x = 0.07, 0.09, 0.16, 0.22, 0.31) films were deposited on Si(100) substrates by RF-magnetron sputtering technique. The influence of Fe doping on the local structure of films was investigated by X-ray absorption spectroscopy (XAS) at Fe K-edge and L-edge. For the (In{sub 1-x}Fe{sub x}){sub 2}O{sub 3} films with x = 0.07, 0.09 and 0.16, Fe ions dissolve into In{sub 2}O{sub 3} and substitute for In{sup 3+} sites with a mixed-valence state (Fe{sup 2+}/Fe{sup 3+}) of Fe ions. However, a secondary phase of Fe metal clusters is formed in the (In{sub 1-x}Fe{sub x}){sub 2}O{sub 3} films with x = 0.22 and 0.31. The qualitative analyses of Fe-K edge extended X-ray absorption fine structure (EXAFS) reveal that the Fe-O bond length shortens and the corresponding Debye-Waller factor (α{sup 2}) increases with the increase of Fe concentration, indicating the relaxation of oxygen environment of Fe ions upon substitution. The anomalously large structural disorder and very short Fe-O distance are also observed in the films with high Fe concentration. Linear combination fittings at Fe L-edge further confirm the coexistence of Fe{sup 2+} and Fe{sup 3+} with a ratio of ∝3:2 (Fe{sup 2+}: Fe{sup 3+}) for the (In{sub 1-x}Fe{sub x}){sub 2}O{sub 3} film with x = 0.16. However, a significant fraction (∝40 at%) of the Fe metal clusters is found in the (In{sub 1-x}Fe{sub x}){sub 2}O{sub 3} film with x = 0.31. (orig.)

  4. Correlation of O (1s) and Fe (2p) near edge x-ray absorption fine structure spectra and electrical conductivity of La1-xSrxFe0.75Ni0.25O3-δ

    Science.gov (United States)

    Erat, Selma; Braun, Artur; Ovalle, Alejandro; Piamonteze, Cinthia; Liu, Zhi; Graule, Thomas; Gauckler, Ludwig J.

    2009-10-01

    A-site substitution of La3+ by Sr2+ in polaron conducting ABO3-type perovskite La1-xSrxFe0.75Ni0.25O3-δ causes oxidation of Fe3+ toward Fe4+ and formation of conducting electron holes, as evidenced by Fe (2p) and O (1s) near edge x-ray absorption fine structure spectra. Hole doping is reflected by linear variation of the prepeak ratio eg(↑)/[t2g(↓)+eg(↓)] of oxygen spectra, along with increased conductivity. The significant increase in conductivity due to NiO doping in La1-xSrxFeO3-δ is caused by increased overlap between Fe (3d) and O (2p) and charge transfer from the O (2p) to the Ni (3d) states, as concluded from near edge x-ray absorption fine structure spectra and ligand field multiplet calculations.

  5. Synthesis and microwave absorption enhancement of graphene@Fe3O4@SiO2@NiO nanosheet hierarchical structures.

    Science.gov (United States)

    Wang, Lei; Huang, Ying; Sun, Xu; Huang, Haijian; Liu, Panbo; Zong, Meng; Wang, Yan

    2014-03-21

    Hierarchical structures of graphene@Fe3O4@SiO2@NiO nanosheets were prepared by combining the versatile sol-gel process with a hydrothermal reaction. Graphene@Fe3O4 composites were first synthesized by the reduction reaction between FeCl3 and diethylene glycol (DEG) in the presence of GO. Then, graphene@Fe3O4 was coated with SiO2 to obtain graphene@Fe3O4@SiO2. Finally, NiO nanosheets were grown perpendicularly on the surface of graphene@Fe3O4@SiO2 and graphene@Fe3O4@SiO2@NiO nanosheet hierarchical structures were formed. Moreover, the microwave absorption properties of both graphene@Fe3O4 and graphene@Fe3O4@SiO2@NiO nanosheets were investigated between 2 and 18 GHz microwave frequency bands. The electromagnetic data demonstrate that graphene@Fe3O4@SiO2@NiO nanosheet hierarchical structures exhibit significantly enhanced microwave absorption properties compared with graphene@Fe3O4, which probably originate from the unique hierarchical structure with a large surface area and high porosity.

  6. Fe-heme structure in Cu, Zn superoxide dismutase from Haemophilus ducreyi by X-ray absorption spectroscopy.

    Science.gov (United States)

    D'Angelo, Paola; Zitolo, Andrea; Pacello, Francesca; Mancini, Giordano; Proux, Olivier; Hazemann, Jean Louis; Desideri, Alessandro; Battistoni, Andrea

    2010-06-01

    We have carried out an X-ray Absorption Spectroscopy (XAS) study of ferric, ferrous, CO- and NO-bound Haemophilus ducreyi Cu,ZnSOD (HdSOD) in solution to investigate the structural modifications induced by the binding of small gaseous ligands to heme in this enzyme. The combined analysis of EXAFS and XANES data has allowed us to characterize the local structure around the Fe-heme with 0.02A accuracy, revealing a heterogeneity in the distances between iron and the two histidine ligands which was not evident in the X-ray crystal structure. In addition, we have shown that the metal oxidation state does not influence the Fe-heme coordination environment, whereas the presence of the CO and NO ligands induces local structural rearrangements in the enzyme which are very similar to those already observed in other hexa-coordinated heme proteins, such as neuroglobin.

  7. Correlation between Fe-Zn Interdiffusion Observed by Scanning Capacitance Microscopy and Device Characteristics of Electro-Absorption Modulators

    Science.gov (United States)

    Ogasawara, Matsuyuki; Iga, Ryuzo; Yamanaka, Takayuki; Kondo, Susumu; Kondo, Yasuhiro

    2003-04-01

    The advantages of scanning capacitance microscopy (SCM) in observing Fe-Zn interdiffusion of an electro-absorption (EA) modulator and the relationship between the interdiffusion and device characteristics are discussed. SCM images show that there is a Zn diffusion region, in which the semi-insulating region is converted into p-type due to Zn diffusion, on both sides of the mesa and the Zn diffusion region becomes smaller as the Fe doping concentration is reduced. By comparison, scanning electron microscopy (SEM) images captured after stain etching of EA modulators did not clearly delineate the Zn diffusion front. The influence of a ruthenium (Ru)-doped InP burying layer on the interdiffusion has also been investigated by SCM. These results indicate that in order to improve the performance of EA modulators, it is important to prevent Zn diffusion into the semi-insulating layers.

  8. Electronic and lattice structures in SmFeAsO1-xFx probed by x-ray absorption spectroscopy

    Science.gov (United States)

    Zhang, C. J.; Oyanagi, H.; Sun, Z. H.; Kamihara, Y.; Hosono, H.

    2010-03-01

    Local lattice and electronic structures in the Fe-As layer of SmFeAsO1-xFx superconductors were studied by x-ray absorption spectroscopy, the FeK -edge and the AsK -edge extended x-ray absorption fine-structure, and x-ray absorption near-edge-structure experiments, respectively. Temperature-dependent local lattice distortions were observed in the Fe-As bond mean-square relative displacement of the superconducting samples. A strong coupling of the carrier-induced local lattice distortion (polaron) to the superconducting transition temperature in the oxypnictide superconductors is indicated. The near-edge spectra showed systematic temperature-dependent energy shifts, which indicate an intralayer electron redistribution from Fed states to Asp states due to orbital-selective band filling at low temperatures.

  9. Tuning optical absorption and photoexcited recombination dynamics in La1-xSrxFeO3-δ through A-site substitution and oxygen vacancies

    Science.gov (United States)

    Smolin, Sergey; Scafetta, Mark; Choquette, Amber; Sfeir, Matthew; Baxter, Jason; May, Steven

    We study optical absorption and recombination dynamics in La1-xSrxFeO3-δ thin films, uncovering the effects of tuning nominal Fe valence via A-site substitution and oxygen stoichiometry. Variable angle spectroscopic ellipsometry was used to measure static optical properties, revealing a linear increase in absorption coefficient at 1.25 eV and a red-shifting of the optical absorption edge with increasing Sr fraction. The absorption spectra can be similarly tuned through the introduction of oxygen vacancies, indicating the critical role that nominal Fe valence plays in optical absorption. Dynamic optoelectronic properties were studied with ultrafast transient reflectance spectroscopy, revealing similar nanosecond photoexcited carrier lifetimes for oxygen deficient and stoichiometric films with the same nominal Fe valence. These results demonstrate that while the static optical absorption is strongly dependent on Fe valence tuned through cation or anion stoichiometry, oxygen vacancies do not appear to play a significantly detrimental role in the recombination kinetics. Nsf: ECCS-1201957, MRI DMR-0922929, MRI DMR-1040166. This research used resources of the Center for Functional Nanomaterials, which is a U.S. DOE Office of Science Facility, at Brookhaven National Laboratory under Contract No. DE-SC0012704.

  10. Synthesis, characterization and microwave absorption properties of dendrite-like Fe3O4 embedded within amorphous sugar carbon matrix

    Science.gov (United States)

    Wu, Hao; Wang, Liuding; Wu, Hongjing

    2014-01-01

    Magnetite dendrites/sugar carbon (MDs/SC) nanocomposites, embedding MDs within amorphous SC matrix, were prepared by simple carbonization-reduction method using α-Fe2O3 dendrites (HDs) as precursor of MDs and sucrose as SC source, while still maintain the dendritic shape of the precursor. The morphology, composition, structure and static magnetic properties of the as-prepared MDs/SC nanocomposites were characterized by various techniques thoroughly. Particularly, the electromagnetic and microwave absorption properties of the MDs/SC and MDs paraffin composites (40 wt.%) were compared over 2-14 GHz. The results show that the microwave absorption performance of MDs/SC samples is comparable or even superior to that of MDs case. The absorption band with reflection loss (RL) below -20 dB for one of the MDs/SC samples can cover the whole X-band (8-12 GHz) with thickness of 1.8-2.4 mm when the content of MDs in the MDs/SC nanocomposite is 25.8 wt.%, and the minimum RL can reach -49.9 dB at 12.1 GHz when the layer thickness is only 1.9 mm. The excellent microwave absorption properties of the MDs/SC paraffin composites are attributed to the proper match between the complex permittivity and permeability, and the unique fractal structures of MDs.

  11. Vanadium fine-structure K-shell electron impact ionization cross sections for fast-electron diagnostic in laser–solid experiments

    Energy Technology Data Exchange (ETDEWEB)

    Palmeri, P., E-mail: patrick.palmeri@umons.ac.be [Astrophysique et Spectroscopie, Université de Mons - UMONS, B-7000 Mons (Belgium); Quinet, P., E-mail: pascal.quinet@umons.ac.be [Astrophysique et Spectroscopie, Université de Mons - UMONS, B-7000 Mons (Belgium); IPNAS, Université de Liège, B-4000 Liège (Belgium); Batani, D., E-mail: batani@celia.u-bordeaux1.fr [CELIA, Université de Bordeaux, F-33400 Talence (France)

    2015-09-15

    The K-shell electron impact ionization (EII) cross section, along with the K-shell fluorescence yield, is one of the key atomic parameters for fast-electron diagnostic in laser–solid experiments through the K-shell emission cross section. In addition, in a campaign dedicated to the modeling of the K lines of astrophysical interest (Palmeri et al. (2012)), the K-shell fluorescence yields for the K-vacancy fine-structure atomic levels of all the vanadium isonuclear ions have been calculated. In this study, the K-shell EII cross sections connecting the ground and the metastable levels of the parent vanadium ions to the daughter ions K-vacancy levels considered in Palmeri et al. (2012) have been determined. The relativistic distorted-wave (DW) approximation implemented in the FAC atomic code has been used for the incident electron kinetic energies up to 20 times the K-shell threshold energies. Moreover, the resulting DW cross sections have been extrapolated at higher energies using the asymptotic behavior of the modified relativistic binary encounter Bethe model (MRBEB) of Guerra et al. (2012) with the density-effect correction proposed by Davies et al. (2013)

  12. Electromagnetic and microwave absorption properties of single-walled carbon nanotubes and CoFe{sub 2}O{sub 4} nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Li, Guo; Sheng, Leimei, E-mail: slmss@shu.edu.cn; Yu, Liming; An, Kang; Ren, Wei; Zhao, Xinluo, E-mail: xlzhao@shu.edu.cn

    2015-03-15

    Highlights: • LPA-SWCNTs have been abundantly fabricated by a facile, time-saving, economical and non-hazardous method using DC arc discharge technique in low-pressure air. • The electromagnetic and microwave absorption properties of LPA-SWCNTs, CoFe{sub 2}O{sub 4} nanocrystals and LPA-SWCNT/CoFe{sub 2}O{sub 4} nanocomposites were investigated and the LPA-SWCNT/CoFe{sub 2}O{sub 4} nanocomposites exhibited excellent microwave absorption properties. • The Debye theory and impedance matching were used to analyze the electromagnetic parameters and microwave absorption properties. - Abstract: Single-walled carbon nanotubes were facilely and abundantly synthesized by low-pressure air arc discharge method (LPA-SWCNTs), and CoFe{sub 2}O{sub 4} nanocrystals were synthesized by a nitrate citric acid sol–gel auto-ignition method. The electromagnetic and microwave absorption properties of LPA-SWCNTs, CoFe{sub 2}O{sub 4} nanocrystals and their nanocomposites were investigated. The LPA-SWCNT/CoFe{sub 2}O{sub 4} nanocomposites showed excellent microwave absorption properties. The minimum efficient reflection loss is −30.7 dB at 12.9 GHz for 10 wt% of LPA-SWCNTs in the nanocomposites, and an effective absorption bandwidth with a reflection loss below −10 dB is 7.2 GHz. The Debye equation and impedance matching were introduced to explain the microwave absorption properties. Compared with the single-component materials, the LPA-SWCNT/CoFe{sub 2}O{sub 4} nanocomposites are an excellent candidate for microwave absorbers.

  13. Formation mechanism of LiFePO{sub 4}/C composite powders investigated by X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Kuei-Feng; Hu, Shao-Kang [Department of Chemical Engineering, National Taiwan University of Science and Technology, 43 Keelung Road, Sec. 4, Taipei 106 (China); Department of Chemical Engineering, National Cheng Kung University, No. 1, Ta-Hsueh Road, Tainan 701 (China); Chen, Chinh-Hsiang; Cheng, Ming-Yao [Department of Chemical Engineering, National Taiwan University of Science and Technology, 43 Keelung Road, Sec. 4, Taipei 106 (China); Tsay, Sun-Yuan; Chou, Tse-Chuan [Department of Chemical Engineering, National Cheng Kung University, No. 1, Ta-Hsueh Road, Tainan 701 (China); Sheu, Hwo-Shuenn; Lee, Jyh-Fu [National Synchrotron Radiation Research Center, Hsinchu 300 (China); Hwang, Bing-Joe [Department of Chemical Engineering, National Taiwan University of Science and Technology, 43 Keelung Road, Sec. 4, Taipei 106 (China); National Synchrotron Radiation Research Center, Hsinchu 300 (China)

    2009-07-15

    The local structure and oxidation states for both the precursors and the LiFePO{sub 4}/C composite powders were investigated by X-ray absorption spectroscopy (XAS) to provide a deep insight into their formation mechanism. It was found that the local structure and oxidation states of the precursors and the synthesized LiFePO{sub 4}/C powders as well as the electrochemical properties of the synthesized powders were strongly influenced by the R ratio (R: molar ratio of citric acid to total metal ions). The oxidation states of iron ions of the precursors for R = 1 and 0.75 consist mainly of Fe(II) and traces of Fe(III). However, the oxidation state of iron ions of the precursor for R = 0.5 comprises mainly of Fe(III). The oxidation state of iron ions of all the synthesized powders is Fe(II). The structure of the precursors and the synthesized powders for R = 1 and 0.75 is more ordering than that for R = 0.5. It is in good agreement with the observation of the cation mixing obtained from the Riteveld analysis of the XRD data. The better the electrochemical performance is, the more ordering the structure or the less the cation mixing. However, the effect of the R values on the carbon content is also essential for the electrochemical properties of the synthesized LiFePO{sub 4}/C composite powders. Increasing the carbon content leads to the increase in the electronic conductivity but impedes the Li{sup +} ion diffusion of the composite materials. Consequently, the powders synthesized at the optimal R ratio of 0.75 exhibited the highest initial capacity, about 150 mAh g{sup -1} when cycled at 1/40 C rate at room temperature. The structural scheme of the precursors and the synthesized powders and the formation mechanism of the LiFePO{sub 4}/C composite powders are also addressed in this work. (author)

  14. K. cap alpha. sup(h) hypersatellite spectrum and K shell double photoionization cross-section for Ar

    Energy Technology Data Exchange (ETDEWEB)

    Mikkola, E.; Ahopelto, J. (Helsinki University of Technology, Espoo (Finland). Lab. of Physics)

    1983-04-01

    The K..cap alpha..sup(h) hypersatellite spectrum of gaseous Ar has been measured in photon excitation with a plane crystal Bragg spectrometer. The experimental energy of K..cap alpha../sub 2/sup(h) line is obtained. The result is in good agreement with available theoretical calculations. The K shell double photoionization cross-section is estimated from the measured hypersatellite intensity and it is compared with existing theoretical calculations based on the shake theory and correlated wave functions.

  15. Measurement and Multiple Scattering Correction of K-Shell Ionization Cross Sections of Silver by Electron Impact

    Institute of Scientific and Technical Information of China (English)

    ZHOU Chang-Geng; FU Yu-Chuan; AN Zhu; TANG Chang-Huan; LUO Zheng-Ming

    2001-01-01

    The K-shell ionization cross sections of silver have been measured by electron impact. In order to overcomethe difliculties in. Preparing a self-supporting thin targets, a thin target with a thick substrate was used inour experiments. The influence of electrons reflected from the substrate was corrected by means of a detailed calculation of electron transport. The path of the electrons passing through the silver target of 31.2 μg/cm2 wascalculated by the EGS4 Monte Carlo program. This method of correction for the measurement is reported for the first time.

  16. Erratum: Observation of Tri-photon K-Shell X Rays [Chin. Phys. Lett. 23 (2006)826

    Institute of Scientific and Technical Information of China (English)

    CHENG Yao; XIA Bing

    2006-01-01

    @@ The reported two peaks near 65.1 keV and 66.9 keV are not only the tri-photon coincidence counts but also the single photon of K-shell x-rays. These peaks contain two major decay components, i.e. fast τ0/3 decay and slow 5.8-day decay. The 5.8-day decay corresponds to the 195mPt transition and the τ0/3 decay corresponds to the reported tri-photon effect.

  17. Infrared Optical Absorption in Low-spin Fe2+-doped SrTiO3

    Energy Technology Data Exchange (ETDEWEB)

    Comes, Ryan B.; Kaspar, Tiffany C.; Heald, Steve M.; Bowden, Mark E.; Chambers, Scott A.

    2016-01-06

    Band gap engineering in SrTiO3 and related titanate perovskites has long been explored due to the intriguing properties of the materials for photocatalysis and photovoltaic applications. A popular approach in the materials chemistry community is to substitutionally dope aliovalent transition metal ions onto the B site in the lattice to alter the valence band. However, in such a scheme there is limited control over the dopant valence, and compensating defects often form. Here we demonstrate a novel technique to controllably synthesize Fe2+- and Fe3+-doped SrTiO3 thin films without formation of compensating defects by co-doping with La3+ ions on the A site. We stabilize Fe2+-doped films by doping with two La ions for every Fe dopant, and find that the Fe ions exhibit a low-spin electronic configuration, producing optical transitions in the near infrared regime and degenerate doping. The novel electronic states observed here offer a new avenue for band gap engineering in perovskites for photocatalytic and photovoltaic applications.

  18. Optical absorption red and blue shifts in ZnFe{sub 2}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kislov, N. [Clean Energy Research Center, College of Engineering, University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620 (United States)], E-mail: nikolai@eng.usf.edu; Srinivasan, S.S. [Clean Energy Research Center, College of Engineering, University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620 (United States)], E-mail: sesha@eng.usf.edu; Emirov, Yu. [Nanomaterials and Nanomanufacturing Research Center, College of Engineering, University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620 (United States); Stefanakos, E.K. [Clean Energy Research Center, College of Engineering, University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620 (United States)

    2008-09-25

    Nanoparticles of zinc ferrite (ZnFe{sub 2}O{sub 4}) prepared by both wet- and dry-high-energy ball milling (HEBM), have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM), surface area and pore size distribution (BET) and wavelength-dependent diffuse reflectance and scattering turned into absorption coefficient estimation using the Kubelka-Munk theory. It was found that after 72 h of HEBM, the particle size was decreased from 220 nm for the initial material to 16.5 nm and 9.4 nm for the wet- and dry-milled samples, respectively. The optical absorption analysis revealed that the energy gap is increased (blue shift) for wet-milled and decreased ('anomalous' red shift) for dry-milled samples of ZnFe{sub 2}O{sub 4} as the particle size decreased. The likely origins for the phenomena, namely the blue and red shifts as large as 0.45 eV and 0.14 eV, respectively, are proposed and discussed, and the effects are quantitatively estimated.

  19. Local structure around Fe ions on multiferroic Pb(Fe{sub 1/2}Nb{sub 1/2})O{sub 3} ceramics probed by x-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mesquita, A.; Fraygola, B. M.; Eiras, J. A. [Grupo de Ceramicas Ferroeletricas, Departamento de Fisica, Universidade Federal de Sao Carlos, Sao Carlos, SP (Brazil); Mastelaro, V. R. [Instituto de Fisica de Sao Carlos, Universidade de Sao Paulo, Sao Carlos, SP (Brazil)

    2012-04-23

    Local structure around Fe ions on Pb(Fe{sub 1/2}Nb{sub 1/2})O{sub 3} ceramics was probed by x-ray absorption spectroscopy in order to settle the controversies about its structure. It is observed that the shell structure around Fe atoms exhibits a monoclinic local symmetry at 130 and 230 K, tetragonal local symmetry at room temperature, and cubic local symmetry at 410 K. Independently of the coordination, temperature, or symmetry, Fe-O mean bond-length does not vary significantly.

  20. Local structure studies of Fe2TeO6 using x-ray absorption spectroscopy

    Science.gov (United States)

    Singh, Harishchandra; Yadav, A. K.

    2016-05-01

    In the present study, we have performed EXAFS measurements on powder samples of Fe2TeO6 (FTO) to probe the local structure surrounding at the Fe site. The structural parameters (atomic coordination and lattice parameters) of FTO used for simulation of theoretical EXAFS spectra of the samples have been obtained from Rietveld refined structure on synchrotron X-ray Diffraction (SXRD) data. Quite similar and satisfactory structural parameters have been obtained from both the study, indicating goodness of synchrotron structural analysis over EXAFS analysis. SXRD and EXAFS results shows absence of any secondary phase proves current synthesis superior over reported techniques.

  1. HIGHLY IONIZED Fe-K ABSORPTION LINE FROM CYGNUS X-1 IN THE HIGH/SOFT STATE OBSERVED WITH SUZAKU

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, S.; Yoshikawa, A.; Makishima, K. [Cosmic Radiation Laboratory, Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-0198 (Japan); Torii, S.; Noda, H. [Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Mineshige, S. [Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Ueda, Y. [Department of Physics, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Kubota, A. [Department of Electronic Information Systems, Shibaura Institute of Technology, 307 Fukasaku, Minuma-ku, Saitama-shi, Saitama 337-8570 (Japan); Gandhi, P. [Institute of Space and Astronautical Science, JAXA, 3-1-1 Yoshinodai, Sagamiharas, 229-8510 Kanagawa (Japan); Done, C. [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom)

    2013-04-20

    We present observations of a transient He-like Fe K{alpha} absorption line in Suzaku observations of the black hole binary Cygnus X-1 on 2011 October 5 near superior conjunction during the high/soft state, which enable us to map the full evolution from the start to the end of the episodic accretion phenomena or dips for the first time. We model the X-ray spectra during the event and trace their evolution. The absorption line is rather weak in the first half of the observation, but instantly deepens for {approx}10 ks, and weakens thereafter. The overall change in equivalent width is a factor of {approx}3, peaking at an orbital phase of {approx}0.08. This is evidence that the companion stellar wind feeding the black hole is clumpy. By analyzing the line with a Voigt profile, it is found to be consistent with a slightly redshifted Fe XXV transition, or possibly a mixture of several species less ionized than Fe XXV. The data may be explained by a clump located at a distance of {approx}10{sup 10-12} cm with a density of {approx}10{sup (-13)-(-11)} g cm{sup -3}, which accretes onto and/or transits the line of sight to the black hole, causing an instant decrease in the observed degree of ionization and/or an increase in density of the accreting matter. Continued monitoring for individual events with future X-ray calorimeter missions such as ASTRO-H and AXSIO will allow us to map out the accretion environment in detail and how it changes between the various accretion states.

  2. Prominent role of multi-electron processes in K-shell double and triple photodetachment of oxygen anions

    CERN Document Server

    Schippers, S; Abrok, L; Bari, S; Buhr, T; Martins, M; Ricz, S; Viefhaus, J; Fritzsche, S; Müller, A

    2016-01-01

    The photon-ion merged-beams technique was used at a synchrotron light source for measuring absolute cross sections of double and triple photodetachment of O$^{-}$ ions. The experimental photon energy range of 524-543 eV comprised the threshold for K-shell ionization. Using resolving powers of up to 13,000, the position, strength and width of the below-threshold 1s 2s2 2p6 2S resonance as well as the positions of the 1s 2s2 2p5 3P and 1s 2s2 2p5 1P thresholds for K-shell ionization were determined with high precision. In addition, systematically enlarged multi-configuration Dirac-Fock calculations have been performed for the resonant detachment cross sections. Results from these ab-initio computations agree very well with the measurements for the widths and branching fractions for double and triple detachment, if double shake-up (and -down) of the valence electrons and the rearrangement of the electron density is taken into account. For the absolute cross sections, however, a previously found discrepancy betwe...

  3. L- and M-shell absorption measurements of radiatively heated Fe plasma

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Jiyan; Li Hang; Zhao Yang; Xiong Gang; Yuan Zheng; Zhang Haiying; Yang Guohong; Yang Jiamin; Liu Shenye; Jiang Shaoen; Ding Yongkun; Zhang Baohan; Zheng Zhijian [Research Center of Laser Fusion, P. O. Box 919-986, Mianyang 621900 (China); Xu Yan; Meng Xujun; Yan Jun [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)

    2012-11-15

    Measurements of iron-plasma absorption spectrum over 150-1200 eV photon energy range were reported at temperature T = (72 {+-} 4) eV. The electron temperature was diagnosed with the absorption spectrum of aluminum mixed with iron. The density was not diagnosed directly but obtained from a radiative hydrodynamic simulation with the Multi-1D code. The broad photon energy range enables simultaneous observation of the L-shell and M-shell transitions that dominate the radiation transport at this temperature. The spectrally resolved transmission data were compared to the detailed-configuration-accounting model calculations and reasonable agreement was found.

  4. Microwave absorption properties of polypyrrole-SrFe12O19-TiO2-epoxy resin nanocomposites: Optimization using response surface methodology

    Science.gov (United States)

    Seyed Dorraji, M. S.; Rasoulifard, M. H.; Amani-Ghadim, A. R.; Khodabandeloo, M. H.; Felekari, M.; Khoshrou, M. R.; hajimiri, I.

    2016-10-01

    At a few works are discussed about formation of heterogeneous composites with different distribution of particle shape and size that are used for electromagnetic absorption purposes. In this study a novel heterogeneous nanocpmposites is investigated. The nanocomposite has been successfully prepared based on epoxy resin including various nano-metal oxides (TiO2, SrFe12O19) and polypyrrole (PPy) by sol-gel and the solution chemistry method, respectively. The performance of prepared nanocomposite in absorption of microwave in X-band range was investigated and transmission line method by X-band waveguide straight was used to measure EM parameters of nanocomposites. The Response surface methodology (RSM) with central composite design (CCD) was utilized to study the effects of the wt.% TiO2 in SrFe12O19, wt.% Tio2-SrFe12O19 in PPy and wt.% TiO2-SrFe12O19-PPy in epoxy resin, on the microwave absorption properties with the absorber thickness of only 2 mm. The proposed quadratic model was in accordance with the experimental results with correlation coefficient of 96.5%. The optimum condition for maximum microwave absorption efficiency were wt.% TiO2 in SrFe12O19 of 70, wt.% TiO2-SrFe12O19 in PPy of 10 and wt.% TiO2-SrFe12O19-PPy in epoxy of 25. The sample prepared in optimal conditions indicated reflection loss of -15 dB corresponding to 97% absorption, at the range of 9.2-10.8 GHz.

  5. Facile fabrication of carbon microspheres decorated with B(OH) 3 and α-Fe 2 O 3 nanoparticles: superior microwave absorption

    KAUST Repository

    Zhong, Bo

    2017-06-02

    We demonstrate that novel three-dimensional (3D) B(OH)3 and α-Fe2O3 nanoparticles decorated carbon microspheres (B(OH)3/α-Fe2O3-CMSs) can be fabricated via a facile thermal treatment process. The carbon microspheres with diameter of 1 to 3 μm and decorated B(OH)3 and α-Fe2O3 nanoparticles with diameters of several to tens of nanometers are successfully fabricated. These novel 3D B(OH)3/α-Fe2O3-CMS composites exhibit enhanced microwave absorption with tunable strong absorption wavebands in the frequency range of 2–18 GHz. They have a minimum reflection loss (RL) value of -52.69 dB at a thickness of 3.0 mm, and the effective absorption bandwidth for RL less than -10 dB is as large as 5.64 GHz. The enhanced microwave absorption performance arises from the synergy of the impedance matching caused by the B(OH)3 nanoparticles, dielectric loss as well as the enhancement of multiple reflection among 3D α-Fe2O3 nanocrystals. These results provide a new strategy to tune electromagnetic properties and enhance the capacity of high-efficient microwave absorbers.

  6. Electronic structure of Fe2P(10 1 bar 0) studied by soft X-ray photoelectron spectroscopy and X-ray absorption spectroscopy

    Science.gov (United States)

    Sugizaki, Y.; Motoyama, H.; Edamoto, K.; Ozawa, K.

    2017-10-01

    The electronic structure of Fe2P(10 1 bar 0) has been investigated by photoelectron spectroscopy (PES) and X-ray absorption spectroscopy (XAS). The surface prepared by cycles of Ar+ ion sputtering and annealing at 500-800 °C showed a c(2 × 2) low-energy electron diffraction (LEED) pattern. An Fe 3d-P 3p hybrid band (main band) and a satellite were observed at 0-4 eV and 5-8 eV, respectively, in PES spectra of c(2 × 2) Fe2P(10 1 bar 0). The main band showed a clear cut-off at the Fermi edge, indicating the metallic nature of Fe2P. The satellite intensity showed a resonant maximum around the Fe 3p threshold, suggesting that the satellite is caused through a shake-up process. Three types of surface-shifted components were found in P 2p PES spectra. All the P 2p peaks have symmetric line shapes, while the Fe 2p PES and Fe L-edge XAS spectra have asymmetric line shapes, suggesting that the electronic states around the Fermi level are mostly composed of Fe 3d components. These results suggest that the stabilization of the electronic structure at metal sites through the bonding with P atoms is ineffective on Fe2P(10 1 bar 0), as in the case of Fe2P(0001).

  7. Fe Emission And Ionized Excess Absorption in the Luminous Quasar 3C109 With XMM-Newton

    Energy Technology Data Exchange (ETDEWEB)

    Miniutti, Giovanni; /Cambridge U., Inst. of Astron.; Ballantyne, D.R.; /Arizona U.; Allen, S.W.; /KIPAC, Menlo Park; Fabian, A.C.; /Cambridge U., Inst. of Astron.; Ross,; /Holy Cross Coll.

    2006-06-09

    We report results from an XMM-Newton observation of the broad-line radio galaxy 3C 109 (z=0.3056). Previous ASCA data revealed the presence of a broad iron line from the accretion disc with which the XMM-Newton spectrum is fully consistent. However, although improving the ASCA constraints on the line parameters, the quality of the data is not high enough to distinguish between an untruncated accretion disc extending down to small radii close to the black hole and a scenario in which the innermost 20-30 gravitational radii are missing. For this reason, our results are model-dependent and the hard data can be modeled equally well by considering an absorption scenario in which a large column of neutral gas partially covers the X-ray continuum source. However, the absorber would have to comprise hundreds/thousands very compact clouds close to the X-ray source, which seems rather extreme a requirement. The 2-10 keV intrinsic luminosity of 3C 109 is of the order of 2-3 x 10{sup 45} erg s{sup -1} regardless of the adopted model. A recent black hole mass estimate of {approx} 2 x 10{sup 8} M{sub {circle_dot}} implies that L{sub bol}/L{sub Edd} > 1. If partial covering is excluded, the observed reflection fraction (of the order of unity), steep photon index (1.86), and Fe line equivalent width (about 100 eV) all suggest to exclude that the X-ray continuum is strongly beamed indicating that the large Eddington ratio is associated with a radiatively efficient accretion process and making it unlikely that the innermost accretion disc is replaced by a thick radiatively inefficient medium such as in advection-dominated accretion models. We also confirm previous findings on the detection of low energy absorption in excess of the Galactic value, where we find excellent agreement with previous results obtained in X-rays and at other wavelengths (optical and infrared). The better quality of the XMM-Newton data enables us to attribute the excess absorption to slightly ionized gas in

  8. Quantifying immediate price impact of trades based on the k-shell decomposition of stock trading networks

    Science.gov (United States)

    Xie, Wen-Jie; Li, Ming-Xia; Xu, Hai-Chuan; Chen, Wei; Zhou, Wei-Xing; Stanley, H. Eugene

    2016-10-01

    Traders in a stock market exchange stock shares and form a stock trading network. Trades at different positions of the stock trading network may contain different information. We construct stock trading networks based on the limit order book data and classify traders into k classes using the k-shell decomposition method. We investigate the influences of trading behaviors on the price impact by comparing a closed national market (A-shares) with an international market (B-shares), individuals and institutions, partially filled and filled trades, buyer-initiated and seller-initiated trades, and trades at different positions of a trading network. Institutional traders professionally use some trading strategies to reduce the price impact and individuals at the same positions in the trading network have a higher price impact than institutions. We also find that trades in the core have higher price impacts than those in the peripheral shell.

  9. Demonstration of a 13-keV Kr K-shell x-ray source at the National Ignition Facility.

    Science.gov (United States)

    Fournier, K B; May, M J; Colvin, J D; Barrios, M A; Patterson, J R; Regan, S P

    2013-09-01

    We report 3% conversion efficiency of laser energy into Kr K-shell (≈13 keV) radiation, consistent with theoretical predictions. This is ≈10× greater than previous work. The emission was produced from a 4.1-mm-diameter, 4-mm-tall gas pipe target filled with 1.2 or 1.5 atm of Kr gas. 160 of the National Ignition Facility laser beams deposited ≈700 kJ of 3ω light into the target in an ≈140 TW, 5.0-ns-duration square pulse. The Dante diagnostics measured ≈5 TW into 4π solid angle of ≥12 keV x rays for ≈4 ns, which includes both continuum emission and flux in the Kr He_{α} line at 13 keV.

  10. Dissimilatory reduction of FeIII (EDTA) with microorganisms in the system of nitric oxide removal from the flue gas by metal chelate absorption

    Institute of Scientific and Technical Information of China (English)

    MA Bi-yao; LI Wei; JING Guo-hua; SHI Yao

    2004-01-01

    In the system of nitric oxide removal from the flue gas by metal chelate absorption, it is an obstacle that ferrous absorbents are easily oxidized by oxygen in the flue gas to ferric counterparts, which are not capable of binding NO. By adding iron metal or electrochemical method, FeIII (EDTA) can be reduced to FeII (EDTA). However, there are various drawbacks associated with these techniques. The dissimilatory reduction of FeIII (EDTA) with microorganisms in the system of nitric oxide removal by metal chelate absorption was investigated. Ammonium salt instead of nitrate was used as the nitrogen source, as nitrates inhibited the reduction of FeIII due to the competition between the two electron acceptors. Supplemental glucose and lactate stimulated the formation of FeII more than ethanol as the carbon sources. The microorganisms cultured at 50℃ were not very sensitive to the other experimental temperature, the reduction percentage of FeIII varied little with the temperature range of 30~50℃. Concentrated Na2CO3 solution was added to adjust the solution pH to an optimal pH range of 6~7. The overall results revealed that the dissimilatory ferric reducing microorganisms present in the mix-culture are probably neutrophilic, moderately thermophilic FeIII reducers.

  11. K-shell Analysis Reveals Distinct Functional Parts in an Electron Transfer Network and Its Implications for Extracellular Electron Transfer

    Science.gov (United States)

    Ding, Dewu; Li, Ling; Shu, Chuanjun; Sun, Xiao

    2016-01-01

    Shewanella oneidensis MR-1 is capable of extracellular electron transfer (EET) and hence has attracted considerable attention. The EET pathways mainly consist of c-type cytochromes, along with some other proteins involved in electron transfer processes. By whole genome study and protein interactions inquisition, we constructed a large-scale electron transfer network containing 2276 interactions among 454 electron transfer related proteins in S. oneidensis MR-1. Using the k-shell decomposition method, we identified and analyzed distinct parts of the electron transfer network. We found that there was a negative correlation between the ks (k-shell values) and the average DR_100 (disordered regions per 100 amino acids) in every shell, which suggested that disordered regions of proteins played an important role during the formation and extension of the electron transfer network. Furthermore, proteins in the top three shells of the network are mainly located in the cytoplasm and inner membrane; these proteins can be responsible for transfer of electrons into the quinone pool in a wide variety of environmental conditions. In most of the other shells, proteins are broadly located throughout the five cellular compartments (cytoplasm, inner membrane, periplasm, outer membrane, and extracellular), which ensures the important EET ability of S. oneidensis MR-1. Specifically, the fourth shell was responsible for EET and the c-type cytochromes in the remaining shells of the electron transfer network were involved in aiding EET. Taken together, these results show that there are distinct functional parts in the electron transfer network of S. oneidensis MR-1, and the EET processes could achieve high efficiency through cooperation through such an electron transfer network. PMID:27148219

  12. Complex X-ray Absorption and the Fe Kalpha Profile in NGC 3516

    CERN Document Server

    Turner, T J; George, I M; Reeves, J N; Bottorff, M C

    2004-01-01

    We present data from simultaneous Chandra, XMM-Newton and BeppoSAX observations of the Seyfert 1 galaxy NGC 3516, taken during 2001 April and Nov. We have investigated the nature of the very flat observed X-ray spectrum. Chandra grating data show the presence of X-ray absorption lines, revealing two distinct components of the absorbing gas, one which is consistent with our previous model of the UV/X-ray absorber while the other, which is outflowing at a velocity of ~1100 km/s has a larger column density and is much more highly ionized. The broad-band spectral characteristics of the X-ray continuum observed with XMM during 2001 April, reveal the presence of a third layer of absorption consisting of a very large column (~2.5 x 10E23 cm^-2) of highly ionized gas with a covering fraction ~50%. This low covering fraction suggests that the absorber lies within a few lt-days of the X-ray source and/or is filamentary in structure. Interestingly, these absorbers are not in thermal equilibrium with one another. The two...

  13. Determination of Fe Content of Some Food Items by Flame Atomic Absorption Spectroscopy (FAAS): A Guided-Inquiry Learning Experience in Instrumental Analysis Laboratory

    Science.gov (United States)

    Fakayode, Sayo O.; King, Angela G.; Yakubu, Mamudu; Mohammed, Abdul K.; Pollard, David A.

    2012-01-01

    This article presents a guided-inquiry (GI) hands-on determination of Fe in food samples including plantains, spinach, lima beans, oatmeal, Frosted Flakes cereal (generic), tilapia fish, and chicken using flame atomic absorption spectroscopy (FAAS). The utility of the GI experiment, which is part of an instrumental analysis laboratory course,…

  14. Influence of hybridization in the magnetic circular X-ray dichroism at the Ce-M(4,5) absorption edges of Ce-Fe systems

    NARCIS (Netherlands)

    Finazzi, M; deGroot, FMF; Dias, AM; Kappler, JP; Schulte, O; Felsch, W; Krill, G

    We have performed a Magnetic Circular X-ray Dichroism (XMCD) study at the Ce-M(4,5) absorption edges on some Ce-Fe systems. We find that the dichroism signal in these systems is very sensitive to the degree of hybridization of the 4f electrons with the valence band. XMCD is able to demonstrate that

  15. Influence of hybridization in the Magnetic Circular X-ray Dichroism at the Ce-M4,5 absorption edges of Ce-Fe systems

    NARCIS (Netherlands)

    Finazzi, M.; de Groot, F.M.F.; Dias, A.-M.; Kappler, J.-P.; Schulte, O.; Felsch, W.; Krill, G.

    2013-01-01

    We have performed a Magnetic Circular X-ray Dichroism (XMCD) study at the Ce-M*,s absorption edges on some Ce-Fe systems. We find that the dichroism signal in these systems is very sensitive to the degree of hybridization of the 4f electrons with the valence band. XMCD is able to demonstrate that th

  16. Influence of hybridization in the magnetic circular X-ray dichroism at the Ce-M(4,5) absorption edges of Ce-Fe systems

    NARCIS (Netherlands)

    Finazzi, M; deGroot, FMF; Dias, AM; Kappler, JP; Schulte, O; Felsch, W; Krill, G

    1996-01-01

    We have performed a Magnetic Circular X-ray Dichroism (XMCD) study at the Ce-M(4,5) absorption edges on some Ce-Fe systems. We find that the dichroism signal in these systems is very sensitive to the degree of hybridization of the 4f electrons with the valence band. XMCD is able to demonstrate that

  17. High velocity blue-shifted FeII absorption in the dwarf star-forming galaxy PHL293B: Evidence for a wind driven supershell?

    CERN Document Server

    Terlevich, R; Bosch, G; Diaz, A I; Hagele, G; Cardaci, M; Firpo, V

    2014-01-01

    X-shooter and ISIS WHT spectra of the starforming galaxy PHL 293B also known as A2228-00 and SDSS J223036.79-000636.9 are presented in this paper. We find broad (FWHM = 1000km/s) and very broad (FWZI = 4000km/s) components in the Balmer lines, narrow absorption components in the Balmer series blueshifted by 800km/s, previously undetected FeII multiplet (42) absorptions also blueshifted by 800km/s, IR CaII triplet stellar absorptions consistent with [Fe/H] < -2.0 and no broad components or blushifted absorptions in the HeI lines. Based on historical records, we found no optical variability at the 5 sigma level of 0.02 mag between 2005 and 2013 and no optical variability at the level of 0.1mag for the past 24 years. The lack of variability rules out transient phenomena like luminous blue variables or SN IIn as the origin of the blue shifted absorptions of HI and FeII. The evidence points to either a young and dense expanding supershell or a stationary cooling wind, in both cases driven by the young cluster w...

  18. Local atomic structure investigation of AlFeCuCrMgx (0.5, 1, 1.7) high entropy alloys: X-ray absorption spectroscopy study

    Science.gov (United States)

    Maulik, Ornov; Patra, N.; Bhattacharyya, D.; Jha, S. N.; Kumar, Vinod

    2017-02-01

    The present paper reports local atomic structure investigation of novel AlFeCuCrMgx (x=0.5, 1, 1.7) high entropy alloys (HEAs) produced by mechanical alloying using Fe, Cr and Cu K-edge X-ray absorption near edge spectroscopy (XANES) and extended x-ray absorption fine structure (EXAFS) spectroscopy. XANES spectra measured at Fe and Cr K-edges resemble that of the respective pure metal foils, while the spectrum measured at Cu K-edge manifests the presence of some other phases in the as-milled alloys. The radial distribution functions (RDFs) obtained from Fourier transformation of EXAFS spectra support the formation of disordered BCC structure.

  19. Investigation of electronic and local structural changes during lithium uptake and release of nano-crystalline NiFe2O4 by X-ray absorption spectroscopy

    Science.gov (United States)

    Zhou, Dong; Permien, Stefan; Rana, Jatinkumar; Krengel, Markus; Sun, Fu; Schumacher, Gerhard; Bensch, Wolfgang; Banhart, John

    2017-02-01

    Nano-crystalline NiFe2O4 particles were synthesized and used as active electrode material for a lithium ion battery that showed a high discharge capacity of 1534 mAh g-1 and charge capacity of 1170 mAh g-1 during the 1st cycle. X-ray absorption spectroscopy including XANES and EXAFS were used to investigate electronic and local structural changes of NiFe2O4 during the 1st lithiation and de-lithiation process. As lithium is inserted into the structure, tetrahedral site Fe3+ ions are reduced to Fe2+ and moved from tetrahedral sites to empty octahedral sites, while Ni2+ ions are unaffected. As a consequence, the matrix spinel structure collapses and transforms to an intermediate rock-salt monoxide phase. Meanwhile, the inserted Li is partially consumed by the formation of SEI and other side reactions during the conversion reaction. With further lithiation, the monoxide phase is reduced to highly disordered metallic Fe/Ni nanoparticles with a number of nearest neighbors of 6.0(8) and 8.1(4) for Fe and Ni, respectively. During subsequent de-lithiation, the metal particles are individually re-oxidized to Fe2O3 and NiO phases instead to the original NiFe2O4 spinel phase.

  20. Pathway of FeEDTA transformation and its impact on performance of NOx removal in a chemical absorption-biological reduction integrated process.

    Science.gov (United States)

    Li, Wei; Zhao, Jingkai; Zhang, Lei; Xia, Yinfeng; Liu, Nan; Li, Sujing; Zhang, Shihan

    2016-01-01

    A novel chemical absorption-biological reduction (CABR) integrated process, employing ferrous ethylenediaminetetraacetate (Fe(II)EDTA) as a solvent, is deemed as a potential option for NOx removal from the flue gas. Previous work showed that the Fe(II)EDTA concentration was critical for the NOx removal in the CABR process. In this work, the pathway of FeEDTA (Fe(III)/Fe(II)-EDTA) transformation was investigated to assess its impact on the NOx removal in a biofilter. Experimental results revealed that the FeEDTA transformation involved iron precipitation and EDTA degradation. X-ray photoelectron spectroscopy analysis confirmed the iron was precipitated in the form of Fe(OH)3. The iron mass balance analysis showed 44.2% of the added iron was precipitated. The EDTA degradation facilitated the iron precipitation. Besides chemical oxidation, EDTA biodegradation occurred in the biofilter. The addition of extra EDTA helped recover the iron from the precipitation. The transformation of FeEDTA did not retard the NO removal. In addition, EDTA rather than the iron concentration determined the NO removal efficiency.

  1. Introduction of dielectric phthalocyanine copper into nano-structure Fe{sub 3}O{sub 4} for excellent microwave absorption

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Shihua; Meng, Fanbin; Jia, Kun, E-mail: jiakun@uestc.edu.cn; Liu, Xiaobo, E-mail: liuxb@uestc.edu.cn

    2015-05-15

    Phthalocyanine copper/magnetite (CuPc/Fe{sub 3}O{sub 4}) magnetic nanohybrids were synthesized from CuPc and FeCl{sub 3}·6H{sub 2}O via a facile solvent-thermal route. The nanohybrids were monodispersed solid nanospheres and the diameter can be adjusted by polymerization degree of CuPc. Importantly, the as-prepared CuPc/Fe{sub 3}O{sub 4} nanohybrids showed excellent microwave absorption properties due to the introduction of dielectric CuPc. A reflection loss ≤−5 dB from 10.0 GHz to 18.0 GHz with multi-frequency microwave absorption was exhibited, and the maximum reflection loss reached to −32.96 dB at 14.50 GHz. Furthermore, the microwave absorption property can be tuned easily by varying polymerization degree of CuPc and the layer thickness of the samples, respectively. Thus, these results offered a promising strategy for the fabrication of absorbents for thin-thickness and strong-absorption microwave absorbing materials with working frequencies adjustable over a wide range. - Highlights: • The diameter can be adjusted by varying polymerization degree of CuPc. • CuPc/Fe{sub 3}O{sub 4} exhibits a reflection loss ≤−5 dB from 10.0 to 18.0 GHz. • The nanohybrids exhibit multi-frequency microwave absorption from 10.0 to 18.0 GHz. • The maximum reflection loss reaches to −32.96 dB at 14.50 GHz. • The microwave absorption can be tuned by varying polymerization degree of CuPc.

  2. Interchange core/shell assembly of diluted magnetic semiconductor CeO2 and ferromagnetic ferrite Fe3O4 for microwave absorption

    Directory of Open Access Journals (Sweden)

    Jiaheng Wang

    2017-05-01

    Full Text Available Core/shell-structured CeO2/Fe3O4 and Fe3O4/CeO2 nanocapsules are prepared by interchange assembly of diluted magnetic semiconductor CeO2 and ferromagnetic ferrite Fe3O4 as the core and the shell, and vice versa, using a facile two-step polar solvothermal method in order to utilize the room-temperature ferromagnetism and abundant O-vacancies in CeO2, the large natural resonance in Fe3O4, and the O-vacancy-enhanced interfacial polarization between CeO2 and Fe3O4 for new generation microwave absorbers. Comparing to Fe3O4/CeO2 nanocapsules, the CeO2/Fe3O4 nanocapsules show an improved real permittivity of 3–10% and an enhanced dielectric resonance of 1.5 times at 15.3 GHz due to the increased O-vacancy concentration in the CeO2 cores of larger grains as well as the O-vacancy-induced enhancement in interfacial polarization between the CeO2 cores and the Fe3O4 shells, respectively. Both nanocapsules exhibit relatively high permeability in the low-frequency S and C microwave bands as a result of the bi-magnetic core/shell combination of CeO2 and Fe3O4. The CeO2/Fe3O4 nanocapsules effectively enhance permittivity and permeability in the high-frequency Ku band with interfacial polarization and natural resonance at ∼15 GHz, thereby improving absorption with a large reflection loss of -28.9 dB at 15.3 GHz. Experimental and theoretical comparisons with CeO2 and Fe3O4 nanoparticles are also made.

  3. Optimization of Optical Absorption of Colloids of SiO2@Au and Fe3O4@Au Nanoparticles with Constraints

    Science.gov (United States)

    Xue, Xiaozheng; Sukhotskiy, Viktor; Furlani, Edward P.

    2016-01-01

    We study the optical response of monodisperse colloids of core-shell plasmonic nanoparticles and introduce a computational approach to optimize absorption for photothermal applications that require dilute colloids of non-interacting particles with a prescribed volume fraction. Since the volume fraction is held constant, the particle concentration is size-dependent. Optimization is achieved by comparing the absorption spectra of colloids as a function of particle size and structure. We demonstrate the approach via application to colloids of core-shell SiO2@Au and Fe3O4@Au nanoparticles with particle sizes that range from 5–100 nm and with the incident wavelength varying from 600–1200 nm. The absorption spectra are predicted using Mie theory and the analysis shows that there is a unique mix of parameters (core radius, shell thickness, wavelength) that maximize absorption, independent of the value of volume fraction. We show that lossy Fe3O4 cores produce a much broader absorption peak with much less sensitivity to variations in particle structure and wavelength than lossless SiO2 cores. This approach can be readily adapted to colloids of nanoparticles with arbitrary materials, shapes and structure using appropriate numerical methods to compute the absorption spectra. As such, it is useful for the rational design of colloids and process variables for a broad range of photothermal applications. PMID:27786279

  4. Microwave absorption studies of magnetic sublattices in microwave sintered Cr3+ doped SrFe12O19

    Science.gov (United States)

    Praveena, K.; Sadhana, K.; Liu, Hsiang-Lin; Bououdina, M.

    2017-03-01

    The partial substitution of Fe3+ by Cr3+ in strontium hexaferrite has shown to be an effective method to tailor anisotropy for many novel microwave applications. Some basic studies have revealed that this substitution leads to unusual interactions among the magnetic sublattices of the hexaferrite. In order to investigate these interactions, Cr3+ doped SrCrxFe12-xO19 (x=0.0, 0.1, 0.3, 0.5, 0.7 and 0.9) (m-type) hexaferrites were prepared by microwave-hydrothermal (m-H) method and subsequently sintered at 950 °C/90 min using microwave furnace. The magnetic hysteresis (m-H) loops revealed the ferromagnetic nature of nanoparticles (NPs). The coercive field was increasing from 3291 Oe to 7335 Oe with increasing chromium content. This resulting compacts exhibited high squareness ratio (Mr/Ms-80%). The intrinsic coercivity (Hci) above 1,20,000 Oe and high values of magnetocrystalline anisotropy revealed that all samples are magnetically hard materials. A material with high loss as well as high dielectric constant may be desired in applications such as electromagnetic (EM) wave absorbing coatings. The room temperature complex dielectric and magnetic properties (ε‧, ε‧‧, μ‧ and μ‧‧) of Cr3+ doped SrFe12O19 were measured in X-band region. The frequency dependent dielectric and magnetic losses were increasing to large extent. The reflection coefficient varied from -16 to -33 dB at 10.1 GHz as Cr3+ concentration increased from x=0.0 to x=0.9. Ferromagnetic resonance spectra (FMR) were measured in the X-band (9.4 GHz), linewidth decreases with chromium concentration from 1368 to 752 Oe from x=0.0 to x=0.9, which is quite low compared to commercial samples. We also have detailed origins of the FMR linewidth broadenings in terms of some important theoretical models. These results show that chromium doped strontium hexaferrites are useful for microwave absorption in the X-band frequency and also have potential for use in low frequency self-biased microwave

  5. Photon Absorption Improvement in Reststrahlen Band of Mn1.56Co0.96- x Ni0.48Fe x O4 Series Films

    Science.gov (United States)

    Zhang, Xiaobo; Shi, Qin; Ren, Wei; Zhou, Qing; Lu, Hewei; Bao, Shuai; Wang, Lei; Bian, Liang; Xu, Jinbao; Chang, Aimin

    2017-08-01

    Mn1.56Co0.96- x Ni0.48Fe x O4 series films have been fabricated on SiO2/Si(100) substrates by chemical solution deposition and characterized by scanning electron microscopy, and their structural and mid-infrared (IR) properties investigated. The results indicate slight improvement in the microstructure and density of the films with increasing Fe content. The results of Raman spectroscopy showed variation in the local distortion and cation distribution at octahedral sites with elevated Fe content. The IR optical properties of the films were investigated at room temperature in the wavelength range from 1.5 μm to 25 μm. A strong absorption peak corresponding to Reststrahlen band located at 19.5 μm was observed and its absorption intensity found to improve with increasing Fe content in the films. The maximum absorption coefficient was calculated to be about 18,000 cm-1. The results bear technological significance for the design and fabrication of devices for IR detection applications.

  6. Design of an experimental setup to measure the K-shell photoelectric cross sections and other atomic parameters at K edge

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Alvarez, J.A.; Lopez-Pino, N.; Rizo, O. Diaz; Corrales, Y.; Padilla-Cabal, F.; Perez-Liva, M.; Alessandro, K.D.; Maidana, N.L. [Instituto Superior de Tecnologia y Ciencias Aplicadas (InSTEC), La Habana (Cuba)

    2010-07-01

    Full text: An experimental setup to measure the K shell jump ratio, jump factor and the ratio of total to K-shell photo-electric cross section at K edge was designed with Monte Carlo (MC) simulations, using the MCNPX V 2.6 code. In our arrangement, Bremsstrahlung photons, produced by beta particles from a {sup 90}Sr- {sup 90}Y source (activity - 0.1 mCi) hitting a thin Nickel converter, were used to irradiate the targets. The incident and transmitted spectra were measured with an HPGe detector coupled to conventional electronics. A sharp decrease in intensity at the K-shell binding energy was observed in the transmitted spectra, which, after corrections for photon attenuation, showed the known behavior for the photoelectric cross section as function of photon energy. The photon beam divergence effects were corrected with a calibration curve calculated with MC from simulations of a parallel and a divergent beam. Targets of Dy, Ta, Pt and Au were used to test the setup. The obtained data were processed by fitting either the total cross section to a sigmoidal function or the cross section branches around the K edge to the empirical law {sigma} = (A/E){sup n}. The results obtained using the first method show the influence of detector energy resolution in the data, because the measured jump at the K edge is not so sharp as it should be. Furthermore, additional calculations were done to obtain the anomalous scattering factors and the K-shell oscillator strengths. The values obtained for the K-shell photoelectric cross sections were compared with theoretical and other experimental data. In most cases, relative deviations below 10% were found. (author)

  7. Surface structure of alpha-Fe sub 2 O sub 3 nanocrystal observed by O K-edge X-ray absorption spectroscopy

    CERN Document Server

    Zhang, J; Ibrahim, K; Abbas, M I; Ju, X

    2003-01-01

    X-ray absorption near edge structure (XANES) spectra is used as a probe of surface structure of alpha-Fe sub 2 O sub 3 nanocrystal, prepared by sol-gel method. We present O K-edge XANES of alpha-Fe sub 2 O sub 3 in nanocrystal and bulk by total electron yield at the photoemission station of Beijing Synchrotron Radiation Facility. The spectrum of alpha-Fe sub 2 O sub 3 shows a splitting of the pre-edge structure, which is interpreted as two subsets of Fe 3d t sub 2 sub g and e sub g orbitals in oxygen octahedral (O sub h) crystal field, and is also sensitive to long-range order effects. However, no distinguishable splitting of the pre-edge peak of nanocrystal alpha-Fe sub 2 O sub 3 is observed. This suggests that there exists the distorted octahedral coordination around Fe sites and also the long-range disorder due to the surface as compared with bulk alpha-Fe sub 2 O sub 3.

  8. Microwave Absorption and Shielding, Property of Composites with FeSiA1 and Carbonous Materials as Filler

    Institute of Scientific and Technical Information of China (English)

    Wenqiang Zhang; Yonggang Xu; Liming Yuan; Jun Cai; Deyuan Zhangt

    2012-01-01

    Silicone rubber composites filled with FeSiAI alloys and multi-walled carbon nanotubes (MWCNT)/graphite have been prepared for the first time by a coating process. The complex permittivity and permeability of the composites were measured with a vector network analyzer in a 1-4 GHz frequency range, and the DC electric conductivity was measured by a standard four-point contact method. These parameters were then used to calculate the reflection loss (RL) and shielding effectiveness (SE) of the composites. The results showed that the added MWCNT increased the permittivity and permeability of composites in the L-band, while the added graphite increased only the permittivity. The variation lies in the interactions between two carbonous absorbents. Addition of 1 wt% MWCNT enhanced the RL in the L-band (minimum -5.7 dB at 1 ram, -7.3 dB at 1.5 ram), while the addition of graphite did not. Addition of MWCNT as well as graphite reinforced the shielding property of the composites (maximum SE 13.3 dB at 1 ram, 18.3 dB at 1.5 ram) owing to the increase of conductivity. The addition of these carbonous materials could hold the promise of enforcing the absorption and shielding property of the absorbers.

  9. Ligand-field symmetry effects in Fe(ii) polypyridyl compounds probed by transient X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Hana; Strader, Matthew L.; Hong, Kiryong; Jamula, Lindsey; Gullikson, Eric M.; Kim, Tae Kyu; de Groot, Frank M. F.; McCusker, James K.; Schoenlein, Robert W.; Huse, Nils

    2012-01-01

    Ultrafast excited-state evolution in polypyridyl FeII complexes are of fundamental interest for understanding the origins of the sub-ps spin-state changes that occur upon photoexcitation of this class of compounds as well as for the potential impact such ultrafast dynamics have on incorporation of these compounds in solar energy conversion schemes or switchable optical storage technologies. We have demonstrated that ground-state and, more importantly, ultrafast time-resolved x-ray absorption methods can offer unique insights into the interplay between electronic and geometric structure that underpin the photo-induced dynamics of this class of compounds. The present contribution examines in greater detail how the symmetry of the ligand field surrounding the metal ion can be probed using these x-ray techniques. In particular, we show that steady-state K-edge spectroscopy of the nearest-neighbour nitrogen atoms reveals the characteristic chemical environment of the respective ligands and suggests an interesting target for future charge-transfer femtosecond and attosecond spectroscopy in the x-ray water window.

  10. Preparation and electromagnetic wave absorption properties of Sm{sub 2}O{sub 3}/α-Fe/Sm{sub 2}Fe{sub 17}N{sub x} composites

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Jinwen [School of Materials Science and Engineering, Sichuan University, Chengdu 610065 (China); Liu, Ying, E-mail: liuying5536@163.com [School of Materials Science and Engineering, Sichuan University, Chengdu 610065 (China); Zhang, Jiao; Chen, Xianfu; Yao, Mingying [School of Materials Science and Engineering, Sichuan University, Chengdu 610065 (China)

    2013-06-15

    Sm{sub 2}O{sub 3}/α-Fe/Sm{sub 2}Fe{sub 17}N{sub x} composites were prepared in situ by hydrogenation–disproportionation–oxygen-desorption–recombination and nitrogen process, and their electromagnetic wave absorption properties were measured in the frequency range of 0.5–18 GHz. The result showed that saturation magnetization and coercivity of as-prepared powder with 25.3 wt% Sm{sub 2}O{sub 3}, 64.4 wt% α-Fe and 10.3 wt% Sm{sub 2}Fe{sub 17}N{sub 3} were 134.57 emu/g and 654.5 G, respectively. The dielectric constant of composites was low over the frequency range of 0.5–18 GHz, and their resonance frequencies were at a high frequency range. The resin composite of Sm{sub 2}O{sub 3}/α-Fe/Sm{sub 2}Fe{sub 17}N{sub 3} exhibited effective electromagnetic wave absorption (RL≤20 dB) in a frequency range 3–9 GHz, for absorber thickness ranging from 3 to 8 mm, respectively. A minimum reflection loss of −53 dB from the samples was observed at 7 GHz with an absorber thickness of 3.59 mm. - Highlights: ► Sm{sub 2}O{sub 3}/α-Fe/Sm{sub 2}Fe{sub 17}N{sub x} was firstly prepared in situ by HDDR and nitrogen process. ► Sm{sub 2}O{sub 3}/α-Fe/Sm{sub 2}Fe{sub 17}N{sub x} was used as a new type of EM wave absorber in high frequency. ► Sm{sub 2}O{sub 3}/α-Fe/Sm{sub 2}Fe{sub 17}N{sub x} exhibits a good impedance matching and thickness of absorber.

  11. The enhanced microwave absorption property of CoFe{sub 2}O{sub 4} nanoparticles coated with a Co{sub 3}Fe{sub 7}-Co nanoshell by thermal reduction

    Energy Technology Data Exchange (ETDEWEB)

    Xi Li; Wang Zhen; Zuo Yalu; Shi Xiaoning, E-mail: xili@lzu.edu.cn [Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000 (China)

    2011-01-28

    CoFe{sub 2}O{sub 4} nanoparticles were fabricated by a sol-gel method and then were coated with Co{sub 3}Fe{sub 7}-Co by means of a simple reduction process at different temperatures under 2% H{sub 2} with the protection of argon to generate the dielectric-core/metallic-shell structure. The optimum reflection loss (RL) calculated from permittivity and permeability of the 80 wt% CoFe{sub 2}O{sub 4}/Co{sub 3}Fe{sub 7}-Co and 20 wt% epoxy resin composites reached - 34.4 dB, which was much lower than that of unreduced CoFe{sub 2}O{sub 4} and epoxy resin composites, at 2.4 GHz with a matching thickness of 4.0 mm. Moreover the RL exceeding - 10 dB in the maximum frequency range of 2.2-16 GHz was achieved for a thickness of composites of 1.0-4.5 mm with 600 {sup 0}C thermal reduction process. The improved microwave absorption properties are a consequence of a proper electromagnetic match and the enhanced magnetic loss besides its dielectric loss due to the existence of the core/shell structure in CoFe{sub 2}O{sub 4} composites. Thus, the reductive CoFe{sub 2}O{sub 4} nanoparticles have great potential for being a highly efficient microwave absorber.

  12. Soft-photon emission in extreme-relativistic Compton scattering by K-shell electrons and connection to photoeffect

    CERN Document Server

    Florescu, V

    2000-01-01

    We have recently obtained cross-sections for Compton scattering by K-shell electrons at extreme-relativistic (ER) energies of the incoming photon. Our method is essentially analytical, and only at the end did it require a modest numerical computation. The results are valid for the Compton line of the scattered photon spectrum, but do not cover the infrared divergence at the soft-photon end of the spectrum. This case is treated in the present paper. The method we apply here is an adaptation of the one used for the Compton line. This allows us to make use of many previous results. The quadruply and doubly differential Compton cross-sections can be expressed in analytical forms which allow factorization of the ER photoeffect cross-sections (differential or total, respectively). This result is shown to be a manifestation of the soft-photon theorem connecting the Compton matrix element at low emitted photon frequencies to that of the photoeffect. The computation of ER Compton cross-sections with soft-photon emissi...

  13. Effects of organometallic chelates and inulin in diets for laying hens on Mn and Fe absorption coefficients and their content in egg and tissue

    Directory of Open Access Journals (Sweden)

    Cornescu Gabriela Maria

    2015-01-01

    Full Text Available The aim of this study was to evaluate effects of organic sources of manganese (Mn and iron (Fe and inulin in diets for laying hens on absorption of these minerals and their deposition in egg and tissue. The study was conducted on 90 Lohmann Brown laying hens in the period from 46-52 weeks of age, assigned to 3 groups with 30 hens/group and 3 hens/cage. The hens from the control group (C received a diet based on corn, rice bran and soybean meal with 16% of crude protein, as well as 60 mg Fe/kg and 71.9 mg Mn/kg of diet in form of inorganic salts. The formulation of the experimental diets (E1 and E2 differed from C group diet by the replacement of inorganic Fe and Mn salts by organometallic chelates of these elements, at a level of 25% lower than in the premix for group C. As source of inulin, group E1 diet also included 0.5% of dry Jerusalem artichoke, while group E2 diet included 0.5% of a product based on chicory root extract. At the end of the experiment, 6 hens from each group were slaughtered and blood serum and liver samples were collected and assayed for concentration of Fe and Mn. In the final week of the experiment, 18 eggs/group were collected for determination of Fe and Mn concentration in egg yolk. Concentration of measured blood serum parameters (haemoglobin, haematocrit, Fe and Mn in experimental (E groups were lower than in group C, but no significant differences (P>0.05 were registered. Absorption coefficients of Mn had higher values in E groups than in group C, with significant increase (P0.05 between groups were observed for Mn and Fe concentration in egg yolk.

  14. Respective role of Fe and Mn oxide contents for arsenic sorption in iron and manganese binary oxide: an X-ray absorption spectroscopy investigation.

    Science.gov (United States)

    Zhang, Gaosheng; Liu, Fudong; Liu, Huijuan; Qu, Jiuhui; Liu, Ruiping

    2014-09-02

    In our previous studies, a synthesized Fe-Mn binary oxide was found to be very effective for both As(V) and As(III) removal in aqueous phase, because As(III) could be easily oxidized to As(V). As(III) oxidation and As(V) sorption by the Fe-Mn binary oxide may also play an important role in the natural cycling of As, because of its common occurrence in the environment. In the present study, the respective role of Fe and Mn contents present in the Fe-Mn binary oxide on As(III) removal was investigated via a direct in situ determination of arsenic speciation using X-ray absorption spectroscopy. X-ray absorption near edge structure results indicate that Mn atoms exist in a mixed valence state of +3 and +4 and further confirm that MnOx (1.5 oxidizing As(III) to As(V) through a two-step pathway [reduction of Mn(IV) to Mn(III) and subsequent Mn(III) to Mn(II)] and FeOOH content is dominant for adsorbing the formed As(V). No significant As(III) oxidation by pure FeOOH had been observed during its sorption, when the system was exposed to air. The extended X-ray absorption fine structure results reveal that the As surface complex on both the As(V)- and As(III)-treated sample surfaces is an inner-sphere bidentate binuclear corner-sharing complex with an As-M (M = Fe or Mn) interatomic distance of 3.22-3.24 Å. In addition, the MnOx and FeOOH contents exist only as a mixture, and no solid solution is formed. Because of its high effectiveness, low cost, and environmental friendliness, the Fe-Mn binary oxide would play a beneficial role as both an efficient oxidant of As(III) and a sorbent for As(V) in drinking water treatment and environmental remediation.

  15. Three-dimensional SiO2@Fe3O4 core/shell nanorod array/graphene architecture: synthesis and electromagnetic absorption properties

    Science.gov (United States)

    Ren, Yulan; Zhu, Chunling; Zhang, Shen; Li, Chunyan; Chen, Yujin; Gao, Peng; Yang, Piaoping; Ouyang, Qiuyun

    2013-11-01

    We developed a new strategy, i.e., a seed-assisted method, to fabricate a three-dimensional (3D) SiO2@Fe3O4 core/shell nanorod array/graphene architecture. The fabrication processes involved deposition of β-FeOOH seeds on the graphene surfaces in the ferric nitrate aqueous solution, subsequent growth of β-FeOOH nanorod arrays on the graphene surfaces in the ferric chloride aqueous solution under hydrothermal conditions, deposition of SiO2 coating on the surfaces of β-FeOOH nanorods, and final formation of the 3D architecture by a thermal treatment process. Scanning electron microscopy and transmission electron microscopy measurements showed that the SiO2@Fe3O4 core/shell nanorods with a length and diameter of about 60 and 25 nm, respectively, were almost grown perpendicularly on both side surfaces of graphene sheets. The measured electromagnetic parameters showed that the 3D architecture exhibited excellent electromagnetic wave absorption properties, i.e., more than 99% of electromagnetic wave energy could be attenuated by the 3D architecture with an addition amount of only 20 wt% in the paraffin matrix. In addition, the growth mechanism of the 3D architecture was proposed, and thus, the strategy presented here could be used as a typical method to synthesize other 3D magnetic graphene nanostructures for extending their application areas.We developed a new strategy, i.e., a seed-assisted method, to fabricate a three-dimensional (3D) SiO2@Fe3O4 core/shell nanorod array/graphene architecture. The fabrication processes involved deposition of β-FeOOH seeds on the graphene surfaces in the ferric nitrate aqueous solution, subsequent growth of β-FeOOH nanorod arrays on the graphene surfaces in the ferric chloride aqueous solution under hydrothermal conditions, deposition of SiO2 coating on the surfaces of β-FeOOH nanorods, and final formation of the 3D architecture by a thermal treatment process. Scanning electron microscopy and transmission electron microscopy

  16. Application of x-ray absorption fine structure (XAFS) to local-order analysis in Fe-Cr maghemite-like materials

    Energy Technology Data Exchange (ETDEWEB)

    Montero-Cabrera, M. E., E-mail: elena.montero@cimav.edu.mx; Fuentes-Cobas, L. E.; Macías-Ríos, E. [Centro de Investigación en Materiales Avanzados, Chihuahua, 31136, México (Mexico); Fuentes-Montero, M. E. [Universidad Autónoma de Chihuahua, Chihuahua, 31000, México (Mexico)

    2015-07-23

    The maghemite-like oxide system γ-Fe{sub 2-x}Cr{sub x}O{sub 3} (x=0.75, 1 and 1.25) was studied by X-ray absorption fine structure (XAFS) and by synchrotron radiation X-ray diffraction (XRD). Measurements were performed at the Stanford Synchrotron Radiation Lightsource at room temperature, at beamlines 2-1, 2-3 and 4-3. High-resolution XRD patterns were processed by means of the Rietveld method. In cases of atoms being neighbors in the Periodic Table, the order/disorder degree of the considered solutions is indiscernible by “normal” (absence of “anomalous scattering”) diffraction experiments. Thus, maghemite-like materials were investigated by XAFS in both Fe and Cr K-edges to clarify, via short-range structure characterization, the local ordering of the investigated system. Athena and Artemis graphic user interfaces for IFEFFIT and FEFF8.4 codes were employed for XAFS spectra interpretation. Pre-edge decomposition and theoretical modeling of X-ray absorption near edge structure (XANES) transitions were performed. By analysis of the Cr K-edge XANES, it has been confirmed that Cr is located in an octahedral environment. Fitting of the extended X-ray absorption fine structure (EXAFS) spectra was performed under the consideration that the central atom of Fe is allowed to occupy octa- and tetrahedral positions, while Cr occupies only octahedral ones. Coordination number of neighboring atoms, interatomic distances and their quadratic deviation average were determined for x=1, by fitting simultaneously the EXAFS spectra of both Fe and Cr K-edges. The results of fitting the experimental spectra with theoretical standards showed that the cation vacancies tend to follow a regular pattern within the structure of the iron-chromium maghemite (FeCrO{sub 3})

  17. ESTIMATION OF MEASUREMENT UNCERTAINTY IN THE DETERMINATION OF Fe CONTENT IN POWDERED TONIC FOOD DRINK USING GRAPHITE FURNACE ATOMIC ABSORPTION SPECTROMETRY

    Directory of Open Access Journals (Sweden)

    Harry Budiman

    2010-06-01

    Full Text Available The evaluation of uncertainty measurement in the determination of Fe content in powdered tonic food drink using graphite furnace atomic absorption spectrometry was carried out. The specification of measurand, source of uncertainty, standard uncertainty, combined uncertainty and expanded uncertainty from this measurement were evaluated and accounted. The measurement result showed that the Fe content in powdered tonic food drink sample was 569.32 µg/5g, with the expanded uncertainty measurement ± 178.20 µg/5g (coverage factor, k = 2, at confidende level 95%. The calibration curve gave the major contribution to the uncertainty of the final results.   Keywords: uncertainty, powdered tonic food drink, iron (Fe, graphite furnace AAS

  18. Cation distribution in Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} using X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, A. K., E-mail: akyadav@barc.gov.in; Jha, S. N.; Bhattacharyya, D.; Sahoo, N. K. [Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai - 400094 (India); Jadhav, J.; Biswas, S. [Department of Physics, The LNM Institute of Information Technology, Jaipur-302031 (India)

    2014-04-24

    Spinel ferrite samples of Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} (for x=0.2, 0.4, 0.5, 0.6 and 0.8) nanoparticles prepared by a novel chemical synthesis method have been characterized by X-ray Absorption Spectroscopy (XAS) technique to investigate the distribution of cations in the unit cell. XANES region clearly shows that as Ni concentration increases, the pre-edge feature, which is a characteristic of tetrahedral coordination of Fe, is enhanced. A quantitative determination of the relative occupancy of iron cation in the octahedral and tetrahedral sites of the spinel structure was obtained from EXAFS data analysis. It has been found that as atomic fraction of Ni is increased from 0.2 to 0.8, Fe occupancy at tetrahedral to octahedral sites is increased from 13:87 and to 39:61.

  19. Extended X-ray absorption fine structure studies of Zn/sub 2/Fe/sub 2/ hybrid hemoglobins: absence of heme bond length changes in half-ligated species

    Energy Technology Data Exchange (ETDEWEB)

    Simolo, K.; Korszun, Z.R.; Stucky, G.; Moffat, K.; McLendon, G.

    1986-07-01

    Metal hybrid hemoglobins, in which Zn(II) replaces Fe(II), have been structurally characterized by extended X-ray absorption structure (EAFS) studies. Since Zn and Fe have very different K absorption edge energies, the structures of the ligated (Fe) and unligated (Zn) sites could be examined independently within a single molecule that mimics an intermediate ligation state. The observed EXAFS spectra and associated structural parameters are compared among the ligand free (..cap alpha..Zn)/sub 2/(..beta..Zn)/sub 2/, half-ligated (..cap alpha..FeCO)/sub 2/(..beta..Zn)/sub 2/ and (..cap alpha..Zn)/sub 2/(..beta..FeCO)/sub 2/, and fully ligated (..cap alpha..FeCO)/sub 2/(..beta..FeCO)/sub 2/ systems.

  20. Octahedron Fe3O4 particles supported on 3D MWCNT/graphene foam: In-situ method and application as a comprehensive microwave absorption material

    Science.gov (United States)

    Shi, Luolin; Zhao, Yan; Li, Ye; Han, Xiao; Zhang, Tong

    2017-09-01

    In this work, we used in-situ method to directly prepare a novel structure consisting of well-distributed octahedron Fe3O4 particles, porous graphene foam (GF) and fibrous multiwalled carbon nanotube (MWCNT): started with an intense stir to anchor Fe3+ on the surfaces of graphene oxide and oxided MWCNT, followed by solvothermal reaction to synthesize 3D lightweight Fe3O4/MWCNT/GF hybrids with high performance microwave absorption (MA). The maximum Reflection Loss (RL) value of -35.30 dB and 9.01 GHz bandwidth with RL below -10 dB detected with the thickness of 3.0 mm are achieved by Fe3O4/MWCNT/GF with an ultralow bulk density of 5.0 mg cm-3, of which the Specific Microwave Absorption Performance is much higher than most available MA materials reported. Impedance matching, high loss characteristic, interfacial polarization and polarization relaxation significantly improve MA properties, which serves as a guide for fabricating comprehensive MA materials enjoying numerous advantages of high RL value, broad bandwidth, low density and thin thickness.

  1. On the Fe K absorption - accretion state connection in the Galactic center neutron star X-ray binary AX J1745.6-2901

    CERN Document Server

    Ponti, G; Munoz-Darias, T; DeMarco, B; Dwelly, T; Fender, R P; Nandra, K; Rea, N; Mori, K; Haggard, D; Heinke, C O; Degenaar, N; Aramaki, T; Clavel, M; Goldwurm, A; Hailey, C J; Israel, G L; Morris, M R; Rushton, A; Terrier, R

    2014-01-01

    AX J1745.6-2901 is a high-inclination (eclipsing) neutron star Low Mass X-ray Binary (LMXB) located less than ~1.5 arcmin from Sgr A*. Ongoing monitoring campaigns have targeted Sgr A* frequently and these observations also cover AX J1745.6-2901. We present here an X-ray analysis of AX J1745.6-2901 using a large dataset of 38 XMM-Newton observations, including eleven which caught AX J1745.6-2901 in outburst. Fe K absorption is clearly seen when AX J1745.6-2901 is in the soft state, but disappears during the hard state. The variability of these absorption features does not appear to be due to changes in the ionizing continuum. The small Kalpha/Kbeta ratio of the equivalent widths of the Fe xxv and Fe xxvi lines suggests that the column densities and turbulent velocities of the absorbing ionised plasma are in excess of N_H ~ 10^23 cm^-2 and v_turb >~ 500 km s^-1. These findings strongly support a connection between the wind (Fe K absorber) and the accretion state of the binary. These results reveal strong simil...

  2. Detection of para–antiferromagnetic transition in Bi{sub 2}Fe{sub 4}O{sub 9} powders by means of microwave absorption measurements

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, G., E-mail: memodin@yahoo.com [Escuela Superior de Física y Matemáticas del Instituto Politécnico Nacional, U.P.A.L.M, Edificio 9, Av. Instituto Politécnico Nacional S/N, San Pedro Zacatenco, México DF 07738 (Mexico); Contreras, J. [Facultad de Química de la Universidad Nacional Autónoma de México, Cd. Universitaria, México DF 04510 (Mexico); Conde-Gallardo, A. [Departamento de Física, CINVESTAV-IPN, A.P. 14-740, México DF 07360 (Mexico); Montiel, H., E-mail: herlinda_m@yahoo.com [Centro de Ciencias Aplicadas y Desarrollo Tecnológico de la Universidad Nacional Autónoma de México, Cd. Universitaria, A.P. 70-186, México DF 04510 (Mexico); Zamorano, R. [Escuela Superior de Física y Matemáticas del Instituto Politécnico Nacional, U.P.A.L.M, Edificio 9, Av. Instituto Politécnico Nacional S/N, San Pedro Zacatenco, México DF 07738 (Mexico)

    2013-12-15

    An electron paramagnetic resonance (EPR) study of Bi{sub 2}Fe{sub 4}O{sub 9} powders is carried out in X-band (8.8–9.8 GHz) and the 200–350 K temperature range. For all the temperatures, the EPR spectra show a single broad line attributable to Fe{sup 3+} (S=5/2) ions. The onset of the para–antiferromagnetic transition has been determined from the temperature dependence of the parameters deduced from EPR spectra: the peak-to-peak linewidth (ΔH{sub pp}) and the resonant field (H{sub res}); a weak ferromagnetism is also observed at low temperature and it is attributed to canting of Fe{sup 3+} ion sublattices in the antiferromagnetic matrix. The magnetically modulated microwave absorption spectroscopy (MAMMAS) and the low-field microwave absorption (LFMA) are used to give further information on this material. These techniques give evidence of the magnetic transition, suggesting a weak ferromagnetism at low temperature. - Highlights: • The changes in lineshape of the EPR spectra in Bi{sub 2}Fe{sub 4}O{sub 9} powders are studied. • The onset of the para–antiferromagnetic transition is detected. • A weak ferromagnetism is also observed in this material. • MAMMAS and LFMA techniques are used to give a further knowledge on the bismuth ferrite.

  3. K-shell X-ray production in Silicon (Z2 = 14) by (1 ⩽ Z1 ⩽ 53) slow ions

    Science.gov (United States)

    Lei, Yu; Zhao, Yongtao; Zhou, Xianming; Cheng, Rui; Wang, Xing; Sun, Yuanbo; Liu, Shidong; Ren, Jieru; Wang, Yuyu; Zhang, Xiaoan; Li, Yaozong; Liang, Changhui; Xiao, Guoqing

    2016-03-01

    K-shell X-ray emission of Silicon induced by near-Bohr-velocity ions was systematically investigated in collision systems for which the ratio of projectile-to-target atomic numbers (Z1/Z2) ranged from 0.07 to 3.79. The results show that, in asymmetric collisions, the measured K-shell X-ray production cross sections of Silicon fit very well with the predictions of different direct ionization models depending on the atomic number of projectile. In the case of near-symmetric collisions (Z1/Z2 ∼ 1), an obvious enhancement of the X-ray production cross section was observed, which can be attributed to the vacancy transfer within the framework of quasi-molecular model.

  4. Characterization of a hybrid target multi-keV x-ray source by a multi-parameter statistical analysis of titanium K-shell emission

    Science.gov (United States)

    Primout, M.; Babonneau, D.; Jacquet, L.; Gilleron, F.; Peyrusse, O.; Fournier, K. B.; Marrs, R.; May, M. J.; Heeter, R. F.; Wallace, R. J.

    2016-03-01

    We have studied the titanium K-shell emission spectra from multi-keV x-ray source experiments with hybrid targets on the OMEGA laser facility. Using the collisional-radiative TRANSPEC code, dedicated to K-shell spectroscopy, we reproduced the main features of the detailed spectra measured with the time-resolved MSPEC spectrometer. We have developed a general method to infer the Ne, Te and Ti characteristics of the target plasma from the spectral analysis (ratio of integrated Lyman-α to Helium-α in-band emission and the peak amplitude of individual line ratios) of the multi-keV x-ray emission. These thermodynamic conditions are compared to those calculated independently by the radiation-hydrodynamics transport code FCI2.

  5. Measurement of K-Shell Ionization Cross Sections of Cr, Ni and Cu Atoms by 7.5-25 keV Electron Impact

    Institute of Scientific and Technical Information of China (English)

    安竹; 唐昶环; 罗正明

    2001-01-01

    The K-shell ionization cross sections of Cr, Ni and Cu elements by 7.5-25 keV electron impact have been measured.The experimental data have also been compared with the theoretical predictions of the Hippler and Mayol-Salvat models. In general, it seems that the Mayol-Salvat model can provide a better description to our experimental data.

  6. Photoionisation of Be-like and Li-like atomic oxygen{\\it K}-shell photoionisation of O$^{4+}$ and O$^{5+}$ ions : experiment and theory

    CERN Document Server

    McLaughlin, B M; Cubaynes, D; Guilbaud, S; Douix, S; Shorman, M M Al; Ghazaly, M O A El; Sakho, I; Gharaibeh, M F

    2016-01-01

    Absolute cross sections for the {\\it K}-shell photoionisation of Be-like (O$^{4+}$) and Li-like (O$^{5+}$) atomic oxygen ions were measured for the first time (in their respective {\\it K}-shell regions) by employing the ion-photon merged-beam technique at the SOLEIL synchrotron-radiation facility in Saint-Aubin, France. High-resolution spectroscopy with E/$\\Delta$E $\\approx$ 3200 ($\\approx$ 170 meV, FWHM)was achieved with photon energy from 550 eV up to 670 eV. Rich resonance structure observed in the experimental spectra is analysed using the R-matrix with pseudo-states (RMPS) method. Results are also compared with the screening constant by unit nuclear charge (SCUNC) calculations. We characterise and identify the strong $\\rm 1s \\rightarrow 2p$ resonances for both ions and the weaker $\\rm 1s \\rightarrow np$ resonances ($ n \\ge 3$) observed in the {\\it K}-shell spectra of O$^{4+}$.

  7. Measurement of mass attenuation coefficients in some Cr, Co and Fe compounds around the absorption edge and the validity of the mixture rule

    Indian Academy of Sciences (India)

    U Turgut; O Şimşek; E Büyükkasap

    2007-08-01

    The total mass attenuation coefficients for elements Cr, Co and Fe and compounds CrCl2, CrCl3, Cr2(SO4)32SO4·24H2O, CoO, CoCl2, Co(CH3COO)2, FePO4, FeCl3·6H2O, Fe(SO4)2NH4·12H2O were measured at different energies between 4.508 and 14.142 keV using secondary excitation method. Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr were chosen as secondary exciters. 59.5 keV -rays emitted from a 241Am annular source were used to excite a secondary exciter and K (K-L3, L2) lines emitted by the secondary exciter were counted by a Si(Li) detector with a resolution of 160 eV at 5.9 keV. It was observed that mixture rule method is not a suitable method for determination of the mass attenuation coefficients of compounds, especially at an energy that is near the absorption edge. The obtained values were compared with theoretical values.

  8. Three-dimensional SiO2@Fe3O4 core/shell nanorod array/graphene architecture: synthesis and electromagnetic absorption properties.

    Science.gov (United States)

    Ren, Yulan; Zhu, Chunling; Zhang, Shen; Li, Chunyan; Chen, Yujin; Gao, Peng; Yang, Piaoping; Ouyang, Qiuyun

    2013-12-21

    We developed a new strategy, i.e., a seed-assisted method, to fabricate a three-dimensional (3D) SiO2@Fe3O4 core/shell nanorod array/graphene architecture. The fabrication processes involved deposition of β-FeOOH seeds on the graphene surfaces in the ferric nitrate aqueous solution, subsequent growth of β-FeOOH nanorod arrays on the graphene surfaces in the ferric chloride aqueous solution under hydrothermal conditions, deposition of SiO2 coating on the surfaces of β-FeOOH nanorods, and final formation of the 3D architecture by a thermal treatment process. Scanning electron microscopy and transmission electron microscopy measurements showed that the SiO2@Fe3O4 core/shell nanorods with a length and diameter of about 60 and 25 nm, respectively, were almost grown perpendicularly on both side surfaces of graphene sheets. The measured electromagnetic parameters showed that the 3D architecture exhibited excellent electromagnetic wave absorption properties, i.e., more than 99% of electromagnetic wave energy could be attenuated by the 3D architecture with an addition amount of only 20 wt% in the paraffin matrix. In addition, the growth mechanism of the 3D architecture was proposed, and thus, the strategy presented here could be used as a typical method to synthesize other 3D magnetic graphene nanostructures for extending their application areas.

  9. Bay Functionalized Perylenediimide with Pyridine Positional Isomers: NIR Absorption and Selective Colorimetric/Fluorescent Sensing of Fe(3+) and Al(3+) Ions.

    Science.gov (United States)

    Kundu, Anu; Pitchaimani, Jayaraman; Madhu, Vedichi; Sakthivel, Pachagounder; Ganesamoorthy, Ramasamy; Anthony, Savarimuthu Philip

    2017-03-01

    Bay functionalized perylene diimide substituted with pyridine isomers, (2-pyridine (2HMP-PDI), 3-pyridine (3-HMP-PDI) and 4-pyridine (4-HMP-PDI)) have been synthesized and explored for selective coloro/fluorimetric sensing of heavy transition metal ions. HMP-PDIs showed strong NIR absorption (760-765 nm) in DMF. The absorption and fluorescence of HMP-PDIs have been tuned by make use of pyridine isomers. Reddish-orange color was observed for 2-HMP-PDI (λmax = 437, 551, 765 nm) whereas 4-HMP-PDI exhibited light green (λmax = 432, 522, 765 nm). 3-HMP-PDI showed orange-yellow (λmax = 431, 524, 762 nm). The fluorescence spectra of 2-, 3- and 4-HMP-PDI showed λmax at 585, 538, 546 nm, respectively. Interestingly, HMP-PDI dyes showed selective color change (intense pink color) and fluorescence quenching for Fe(3+) and Al(3+) metal ions in DMF. Absorbance spectra revealed complete disappearance of NIR absorption and intensification/appearance of new peak at lower wavelength. The concentration dependent studies suggest that 4-HMP-PDI can detect up to 36.52 ppb of Fe(3+) and 43.12 ppb of Al(3+) colorimetrically. The interference studies in presence of other metal ions confirmed the good selectivity for Fe(3+) and Al(3+). The mechanistic studies indicate that Lewis acidic character of Fe(3+) and Al(3+) ions were responsible for selective color change and fluorescence quenching.

  10. Scale heights and equivalent widths of the iron K-shell lines in the Galactic diffuse X-ray emission

    CERN Document Server

    Yamauchi, Shigeo; Nobukawa, Masayoshi; Uchiyama, Hideki; Koyama, Katsuji

    2016-01-01

    This paper reports the analysis of the X-ray spectra of the Galactic diffuse X-ray emission (GDXE) in the Suzaku archive. The fluxes of the Fe I K alpha (6.4 keV), Fe XXV,He alpha (6.7 keV) and Fe XXVI Ly alpha (6.97 keV) lines are separately determined. From the latitude distributions, we confirm that the GDXE is decomposed into the Galactic center (GCXE), the Galactic bulge (GBXE) and the Galactic ridge (GRXE) X-ray emissions. The scale heights (SHs) of the Fe XXV He alpha line of the GCXE, GBXE and GRXE are determined to be ~40, ~310 and ~140 pc, while those of the Fe I K alpha line are ~30, ~160 and ~70 pc, respectively. The mean equivalent widths (EWs) of the sum of the Fe XXV He alpha and Fe XXVI Ly alpha lines are ~750 eV, ~600 eV and ~550 eV, while those of the Fe I K alpha line are ~150~eV, ~60~eV and ~100~eV for the GCXE, GBXE and GRXE, respectively. The origin of the GBXE, GRXE and GCXE is separately discussed based on the new results of the SHs and EWs, in comparison with those of the Cataclysmic ...

  11. Anisotropy in the thermal hysteresis of resistivity and charge density wave nature of single crystal SrFeO3-δ: X-ray absorption and photoemission studies.

    Science.gov (United States)

    Hsieh, S H; Solanki, R S; Wang, Y F; Shao, Y C; Lee, S H; Yao, C H; Du, C H; Wang, H T; Chiou, J W; Chin, Y Y; Tsai, H M; Chen, J-L; Pao, C W; Cheng, C-M; Chen, W-C; Lin, H J; Lee, J F; Chou, F C; Pong, W F

    2017-12-01

    The local electronic and atomic structures of the high-quality single crystal of SrFeO3-δ (δ~0.19) were studied using temperature-dependent x-ray absorption and valence-band photoemission spectroscopy (VB-PES) to investigate the origin of anisotropic resistivity in the ab-plane and along the c-axis close to the region of thermal hysteresis (near temperature for susceptibility maximum, Tm~78 K). All experiments herein were conducted during warming and cooling processes. The Fe L 3,2-edge X-ray linear dichroism results show that during cooling from room temperature to below the transition temperature, the unoccupied Fe 3d e g states remain in persistently out-of-plane 3d 3z(2)-r(2) orbitals. In contrast, in the warming process below the transition temperature, they change from 3d 3z(2)-r(2) to in-plane 3d x(2)-y(2) orbitals. The nearest-neighbor (NN) Fe-O bond lengths also exhibit anisotropic behavior in the ab-plane and along the c-axis below Tm. The anisotropic NN Fe-O bond lengths and Debye-Waller factors stabilize the in-plane Fe 3d x(2)-y(2) and out-of-plane 3d 3z(2)-r(2) orbitals during warming and cooling, respectively. Additionally, a VB-PES study further confirms that a relative band gap opens at low temperature in both the ab-plane and along the c-axis, providing the clear evidence of the charge-density-wave nature of SrFeO3-δ (δ~0.19) single crystal.

  12. Preparation, magnetism and microwave absorption performance of ultra-thin Fe{sub 3}O{sub 4}/carbon nanotube sandwich buckypaper

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Shaowei, E-mail: lushaowei_2005@163.com; Xu, Weikai; Xuhai, Xiong; Ma, Keming; Wang, Xiaoqiang

    2014-09-01

    Graphical abstract: Fe{sub 3}O{sub 4}/multi-walled carbon nanotubes (MWCNTs) sandwich buckypapers were fabricated with monodispersion solutions of MWCNTs and Fe{sub 3}O{sub 4} nanoparticles through layer by layer vacuum filtration method. The Fe{sub 3}O{sub 4}/MWCNTs sandwich buckypaper can be co-cured on the surface of fiber reinforce composites and exhibits excellent magnetism and microwave absorbing ability only with a 0.1 mm thickness absorbing layer. - Highlights: • Sandwich buckypapers were fabricated with MWCNTs/Fe{sub 3}O{sub 4} monodispersions through vacuum filtration. • Composite with a 0.1 mm thickness sandwich buckypaper exhibits strong microwave absorbing ability. • The sandwich buckypaper has higher magnetic loss and suitable dielectric loss. • The sandwich buckypaper can fulfil the impedance matching and attenuation characteristics. - Abstract: Fe{sub 3}O{sub 4}/multi-walled carbon nanotubes (MWCNTs) sandwich buckypapers were fabricated with monodisperse solutions of MWCNTs and Fe{sub 3}O{sub 4} nanoparticles through layer by layer vacuum filtration method and can be co-cured with composites for microwave absorbing application. The morphology, element composition and magnetic properties of sandwich buckypapers were characterized by field-emission scanning electron microscope, energy dispersive spectrometer, X-ray diffraction and vibrating sample magnetometer. The complex permittivity and permeability, the reflection loss properties of polymer composites surface coated buckypapers were investigated in the frequency range of 8.2–18 GHz. The results indicate that, due to the electromagnetic matching of magnetic loss and dielectric loss, the microwave absorption properties of the Fe{sub 3}O{sub 4}/MWCNTs sandwich buckypaper attached polymer composites are evidently improved. When the blending Fe{sub 3}O{sub 4} content in sandwich buckypaper is 20 wt%, the composite displays a larger and wider absorption peak (−12.62 dB at 17.72 GHz), and the

  13. X, Ku-band microwave-absorption properties of polyarylene ether nitriles terminated with phthalonitrile/Fe{sub 3}O{sub 4} hybrid submicron spheres

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Lifen, E-mail: 361626614@qq.com; Pu, Zejun; Huang, Xu; Liu, Xiaobo, E-mail: liuxb@uestc.edu.cn

    2014-05-01

    Highlights: • PEN-t-Ph/Fe{sub 3}O{sub 4} hybrid spheres were prepared via one-step solvothermal method. • Polymer compatibility is introduced into inorganic submicron spheres successfully. • PEN-t-Ph/Fe{sub 3}O{sub 4} hybrid submicron spheres possessed good ferrimagnetism. • Control the microwave absorption band of PEN-t-Ph/Fe{sub 3}O{sub 4} hybrid submicron spheres. - Abstract: A novel series of PEN-t-Ph/Fe{sub 3}O{sub 4} hybrid submicron spheres with different additions of PEN-t-Ph have been prepared successfully via solvothermal method, and their structures and morphologies were characterized by X-ray powder diffraction (XRD), energy dispersive spectrometer (EDS), Fourier transform infrared spectrophotometer (FTIR), and scanning electron microscopy (SEM). The results revealed that the crystallinity, dispersity, and size of hybrid submicron spheres can be controlled by altering the addition content of PEN-t-Ph. Magnetization measurement showed that the PEN-t-Ph/Fe{sub 3}O{sub 4} hybrid submicron spheres possessed good ferrimagnetism. The electromagnetic measurement indicated that the resonance peaks of complex permittivity, complex permeability, dielectric loss, and magnetic loss were shifted to the higher frequency as the addition of PEN-t-Ph increased. Moreover, the microwave absorption band was also shifted to higher frequency as the addition of PEN-t-Ph increased. Through this method, the polymer compatibility can be introduced into inorganic submicron spheres, which could provide the inorganic particles with more applications.

  14. Synthesis, characterization, and microwave absorption properties of Fe-40 wt%Ni alloy prepared by mechanical alloying and annealing

    Energy Technology Data Exchange (ETDEWEB)

    Liu Jun [College of Materials Science and Engineering, Nanjing University of Technology, No. 5 Xinmofan Road, Nanjing 210009 (China); Feng Yongbao, E-mail: fengyongbao@163.com [College of Materials Science and Engineering, Nanjing University of Technology, No. 5 Xinmofan Road, Nanjing 210009 (China); Qiu Tai [College of Materials Science and Engineering, Nanjing University of Technology, No. 5 Xinmofan Road, Nanjing 210009 (China)

    2011-12-15

    Fe-40 wt%Ni alloys with granular shape and flake shape were prepared by a mechanical alloying (MA) and annealing method. The phase composition and morphology of the FeNi alloys, electromagnetic parameters, and microwave absorbing properties of the silicone rubber composite absorbers filled with the as-prepared FeNi alloy particles were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM) and vector network analyzer. The XRD results indicate that the crystalline structures of the Fe-40 wt%Ni alloys prepared by both one-step and two-step MA processes are face-centered cubic (fcc) Ni (Fe) solid solutions, and the structures can be retained after annealing at 600 deg. C for 2 h. SEM images show that the FeNi alloy powders for one-step process have a granular shape; however the particles turned into flake form when they were sequentially milled with absolute ethyl alcohol. With the increase in thickness of composite absorber, the reflection loss (RL) decreases, and the peak for minimum reflection loss shifts towards the lower frequency range. Compared to the absorbers filled with the granular FeNi alloy, the absorbers filled with flaky FeNi alloys possess higher complex permittivities and permeabilities and have a lower RL and peak frequency under the same thickness. Microwave absorbing materials with a low reflection loss peak in the range of 1-4 GHz are obtained, and their microwave absorbing properties can be adjustable by changing their thicknesses. - Highlights: > We prepare face-centered cubic (FCC) Ni (Fe) solid solutions by mechanical alloying and annealing. > Shape of FeNi alloy powder changes from granular to flaky after wet-milling. > Absorbers containing flaky FeNi alloys possess higher electromagnetic parameters. > MAMs with low reflection loss peak in the range of 1-4 GHz are obtained. > Microwave absorbing properties can be adjustable by modifying the thickness of the absorbers.

  15. Synthesis of Hierarchical ZnFe2O4@SiO2@RGO Core-Shell Microspheres for Enhanced Electromagnetic Wave Absorption.

    Science.gov (United States)

    Feng, Jiantao; Hou, Yanhui; Wang, Yechen; Li, Liangchao

    2017-04-26

    Hierarchical structured ZnFe2O4@SiO2@RGO core-shell nanocomposites were prepared via a "coating-coating" route, and its structure, composition and electromagnetic properties were characterized. Compared with the binary composites of ZnFe2O4@SiO2, the hierarchical ZnFe2O4@SiO2@RGO ternary composites exhibited enhanced electromagnetic wave (EMW) absorption properties in terms of the effective bandwidth and minimum reflection loss (RL). Furthermore, EMW absorption properties of the prepared samples can be tuned by changing RGO content and thickness of SiO2 layer to reach the best impedance match. The minimum RL of the sample with a thickness of 2.8 mm can reach -43.9 dB at 13.9 GHz, and its effective bandwidth (RL ≤ -10 dB) was up to 6 GHz. Hence, the obtained products can be a new candidate for lightweight EMW absorbing materials.

  16. Electromagnetic and microwave absorption properties of BaMg{sub x}Co{sub 1−x}TiFe{sub 10}O{sub 19}

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jing [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Meng, Pingyuan [Huzhou Innovation Center of Advanced Materials, Shanghai Institute of Ceramics Chinese Academy of Sciences, Huzhou 215100 (China); Wang, Meiling [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Zhou, Guanchen [School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Wang, Xinqing [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Xu, Guangliang, E-mail: xuguangliang@swust.edu.cn [School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China)

    2016-09-15

    To improve the impedance matching and then achieve a better microwave absorption performance in electromagnetic absorber, the Mg{sup 2+} was added to occupy the sites of Co{sup 2+} in hexagonal-type ferrite BaCoTiFe{sub 10}O{sub 19}. BaMg{sub x}Co{sub 1−x}TiFe{sub 10}O{sub 19} were synthesized by a simple sol-gel combustion technique and the phase of BaMg{sub x}Co{sub 1−x}TiFe{sub 10}O{sub 19} was confirmed by X-ray diffraction analysis (XRD). The grain size of BaMg{sub x}Co{sub 1−x}TiFe{sub 10}O{sub 19} was in the range of 100–400 nm and crystal particles were refined with the augment of doped Mg{sup 2+}. Based on the static magnetic measurement, the coercivity (H{sub c}) increased and the saturation magnetization (M{sub s}) decreased as the x increased. Moreover, it was found that BaMg{sub 0.4}Co{sub 0.6}TiFe{sub 10}O{sub 19} possessed a maximum reflection loss of −33.7 dB with a matching thickness of 2.0 mm measured by the vector net-analyzer in the frequency of 0.5–18 GHz, which also had a bandwidth below −20 dB ranging from 11.5 GHz to 17.2 GHz. Meanwhile, the permeability of the prepared ferrites could be adjusted and a proper match was provided between dielectric and magnetic properties by controlling the doped content of Mg{sup 2+}, which would be significant to the application of BaMg{sub x}Co{sub 1−x}TiFe{sub 10}O{sub 19} in the field of the microwave absorbing materials. - Highlights: • The Mg{sup 2+} ions were first employed to occupy the place of Co{sup 2+} ions in BaCoTiFe{sub 10}O{sub 19}. • The grains were refined as Co substitution by Mg in ferrite. • The peaks of complex permeability shift to high frequency with Mg{sup 2+} substituted. • The coercivity increased and saturation magnetization slightly decreased. • Substitution of Mg{sup 2+} enhanced microwave absorption and broadened bandwidth.

  17. Mechanism of selenite removal by a mixed adsorbent based on Fe-Mn hydrous oxides studied using X-ray absorption spectroscopy.

    Science.gov (United States)

    Chubar, Natalia; Gerda, Vasyl; Szlachta, Małgorzata

    2014-11-18

    Selenium cycling in the environment is greatly controlled by various minerals, including Mn and Fe hydrous oxides. At the same time, such hydrous oxides are the main inorganic ion exchangers suitable (on the basis of their chemical nature) to sorb (toxic) anions, separating them from water solutions. The mechanism of selenite adsorption by the new mixed adsorbent composed of a few (amorphous and crystalline) phases [maghemite, MnCO3, and X-ray amorphous Fe(III) and Mn(III) hydrous oxides] was studied by extended X-ray absorption fine structure (EXAFS) spectroscopy [supported by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) data]. The complexity of the porous adsorbent, especially the presence of the amorphous phases of Fe(III) and Mn(III) hydrous oxides, is the main reason for its high selenite removal performance demonstrated by batch and column adsorption studies shown in the previous work. Selenite was bound to the material via inner-sphere complexation (via oxygen) to the adsorption sites of the amorphous Fe(III) and Mn(III) oxides. This anion was attracted via bidentate binuclear corner-sharing coordination between SeO3(2-) trigonal pyramids and both FeO6 and MnO6 octahedra; however, the adsorption sites of Fe(III) hydrous oxides played a leading role in selenite removal. The contribution of the adsorption sites of Mn(III) oxide increased as the pH decreased from 8 to 6. Because most minerals have a complex structure (they are seldom based on individual substances) of various crystallinity, this work is equally relevant to environmental science and environmental technology because it shows how various solid phases control cycling of chemical elements in the environment.

  18. Feasibility of dispersive liquid–liquid microextraction for extraction and preconcentration of Cu and Fe in red and white wine and determination by flame atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Seeger, Tassia S.; Rosa, Francisco C.; Bizzi, Cezar A.; Dressler, Valderi L.; Flores, Erico M.M.; Duarte, Fabio A., E-mail: fabioand@gmail.com

    2015-03-01

    A method for extraction and preconcentration of Cu and Fe in red and white wines using dispersive liquid–liquid microextraction (DLLME) and determination by flame atomic absorption spectrometry (F AAS) was developed. Extraction was performed using sodium diethyldithiocarbamate as chelating agent and a mixture of 40 μL of 1,2-dichlorobenzene (extraction solvent) and 900 μL of methanol (dispersive solvent). Some parameters that influencing the extraction efficiency such as pH (2 to 5), concentration of chelating agent (0 to 2%), effect of salt addition (0 to 10%), number of washing steps (1 to 4) and centrifugation time (0 to 15 min) were studied. Accuracy was evaluated after microwave-assisted digestion in closed vessels and analytes were determined by inductively coupled plasma optical emission spectrometry. Agreement with the proposed method ranged from 91 to 110 and from 89 to 113% for Cu and Fe, respectively. Calibration of F AAS instrument was performed using analyte addition method and limits of detection were 6.3 and 2.4 μg L{sup −1} for Cu and Fe, respectively. The proposed method was applied for the determination of Cu and Fe in five samples of red wine and three samples of white wine, with concentration ranging from 21 to 178 μg L{sup −1} and from 1.38 to 3.74 mg L{sup −1}, respectively. - Highlights: • Determination of Cu and Fe in wine using DLLME and F AAS • High preconcentration factors and low LODs were achieved. • Alternative method for the determination of Cu and Fe in wine for routine analysis.

  19. Reduction of Pu(VI) on Fe surfaces: soft x-ray absorption and resonant inelastic scattering study

    Energy Technology Data Exchange (ETDEWEB)

    Butorin, S.M.; Kvashnina, K.O.; Modin, A.; Nordgren, J. (Dept. of Physics and Materials Science, Uppsala Univ., Uppsala (Sweden)); Guo, J.H. (Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA (United States)); Shuh, D.K. (Chemical Science Div., Lawrence Berkeley National Laboratory, Berkeley, CA (United States)); Werme, L. (Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden))

    2009-03-15

    Based on analysis of spectral shapes, their dependence on the energy of incident photons and comparison with model calculations and experimental data from the reference sample we can conclude that plutonium from the Pu(VI) solution sorbed on Fe surfaces is likely to be reduced and Pu species sorbed on the Fe foils are mainly in the form of Pu (IV). Current results correlate with what was observed for for Np (V) and U (VI) in our previous studies. Furthermore, combined analysis of present data with model atomic multiplet calculations of RIXS and XAS spectra suggests that significant presence of Pu(III) on the Fe foils is unlikely

  20. Monitoring the role of Mn and Fe in the As-removal efficiency of tetravalent manganese feroxyhyte nanoparticles from drinking water: An X-ray absorption spectroscopy study.

    Science.gov (United States)

    Pinakidou, F; Katsikini, M; Paloura, E C; Simeonidis, K; Mitraka, E; Mitrakas, M

    2016-09-01

    The implementation of amorphous tetravalent manganese feroxyhyte (TMFx) nanoparticles, prepared via co-precipitation synthesis, as an efficient As(V)-removal material is investigated using X-ray absorption fine structure (XAFS) spectroscopy at the Fe-, Mn- and As-K-edges. The optimum synthesis conditions and chemical composition of the TMFx adsorbent were determined by the degree of polymerization in the adsorbents' microstructure. Under synthesis into mildly acidic conditions, the change in the polymerization of the metal-oxyhydroxyl chains (metal=Fe, Mn) provides more adsorption sites at edges and corner sites in the bonding environment of Fe and Mn, respectively, thereby enhancing As uptake. After exposure to As-polluted water, similar microstructural changes related to As-bidentate and monodentate geometries are generated: As(V) preferentially occupies the high energy adsorption sites ((2)C complexes) available in the Mn-oxyhydroxyl groups and the low energy edge sites offered by Fe ((2)E complexes). It is revealed that optimum arsenic-removal by TMFx occurs into mildly acidic synthesis pH and for iron to manganese molar ratio equal to 3. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Feasibility of dispersive liquid-liquid microextraction for extraction and preconcentration of Cu and Fe in red and white wine and determination by flame atomic absorption spectrometry

    Science.gov (United States)

    Seeger, Tassia S.; Rosa, Francisco C.; Bizzi, Cezar A.; Dressler, Valderi L.; Flores, Erico M. M.; Duarte, Fabio A.

    2015-03-01

    A method for extraction and preconcentration of Cu and Fe in red and white wines using dispersive liquid-liquid microextraction (DLLME) and determination by flame atomic absorption spectrometry (F AAS) was developed. Extraction was performed using sodium diethyldithiocarbamate as chelating agent and a mixture of 40 μL of 1,2-dichlorobenzene (extraction solvent) and 900 μL of methanol (dispersive solvent). Some parameters that influencing the extraction efficiency such as pH (2 to 5), concentration of chelating agent (0 to 2%), effect of salt addition (0 to 10%), number of washing steps (1 to 4) and centrifugation time (0 to 15 min) were studied. Accuracy was evaluated after microwave-assisted digestion in closed vessels and analytes were determined by inductively coupled plasma optical emission spectrometry. Agreement with the proposed method ranged from 91 to 110 and from 89 to 113% for Cu and Fe, respectively. Calibration of F AAS instrument was performed using analyte addition method and limits of detection were 6.3 and 2.4 μg L- 1 for Cu and Fe, respectively. The proposed method was applied for the determination of Cu and Fe in five samples of red wine and three samples of white wine, with concentration ranging from 21 to 178 μg L- 1 and from 1.38 to 3.74 mg L- 1, respectively.

  2. Dielectronic recombination of Fe 3p^q ions: a key ingredient for describing X-ray absorption in active galactic nuclei

    CERN Document Server

    Badnell, N R

    2006-01-01

    We have carried-out multi-configuration Breit-Pauli AUTOSTRUCTURE calculations for the dielectronic recombination (DR) of Fe^{8+} - Fe^{12+} ions. We obtain total DR rate coefficients for the initial ground-level which are an order of magnitude larger than those corresponding to radiative recombination (RR), at temperatures where Fe 3p^q (q=2-6) ions are abundant in photoionized plasmas. The resultant total (DR+RR) rate coefficients are then an order of magnitude larger than those currently in use by photoionized plasma modeling codes such as CLOUDY, ION and XSTAR. These rate coefficients, together with our previous results for q=0 and 1, are critical for determining the ionization balance of the M-shell Fe ions which give rise to the prominent unresolved-transition-array X-ray absorption feature found in the spectrum of many active galactic nuclei. This feature is poorly described by CLOUDY and ION, necessitating an ad hoc modification to the low-temperature DR rate coefficients. Such modifications are no lo...

  3. Nanometer-resolution depth-resolved measurement of florescence-yield soft x-ray absorption spectroscopy for FeCo thin film

    Science.gov (United States)

    Sakamaki, M.; Amemiya, K.

    2017-08-01

    We develop a fluorescence-yield depth-resolved soft x-ray absorption spectroscopy (XAS) technique, which is based on the principle that the probing depth is changed by the emission angle of the fluorescence soft x rays. Compared with the electron-yield depth-resolved XAS technique, which has been established in this decade, we can observe wider range in-depth XAS distribution up to several tens of nm. Applying this technique to a 30 ML (˜4.3 nm) FeCo thin film, we observe Fe L-edge XAS spectra at the probing depth of 0.3-6 nm and find that the film has 22 ML (˜3.1 nm) surface oxide layer while its inner layer shows metallic state. We thus successfully obtain nanometer-resolution depth-resolved XAS spectra and further expect that operando measurement under the electric and/or magnetic fields is possible.

  4. Effect of Stoichiometry and Absorption on Self-Pumped Two-Beam Coupling Gain and Photovoltaic Fields in LiNbO3:Fe

    Science.gov (United States)

    Banerjee, Hans; Cook, Gary; Banerjee, Partha; Basun, Sergey; Carns, Jennifer; Wechsler, Barry; Scripsick, Michael; Evans, Dean

    2010-03-01

    The variation of self-pumped two-beam coupling gain in LiNbO3:Fe crystals is investigated, using a CW Verdi 532 nm laser, as a function of absorption coefficients, α, and stoichiometry. The 81 crystals tested contain either 0.02% or 0.05% Fe concentrations and are either stoichiometric, intermediate, congruent, or Li deficient. These compositions include a range of α varying between 0.1 and 16 cm-1. Experimental coupling efficiency results exhibit a dependence on both composition and α; these parameters influence the photovoltaic field, which plays a large role in coupling efficiencies. Experimental results are compared with a mathematical model using a focused geometry, and values for the photovoltaic fields as a function of composition are extracted.

  5. Synthesis and Microwave Absorption Property of Flower-like Fe3O4 Sub-microspheres%花状Fe3O4亚微球的制备和吸波性能

    Institute of Scientific and Technical Information of China (English)

    包家兴; 于荣海

    2013-01-01

    The flower-like Fe3O4 sub-microspheres were synthesized by solvothermal method with average particle size about 4 μm, and they were formed by Fe3O4 nano-flakes. The microstructure, magnetic and morphology of the sub-microspheres were investigated by X-ray diffraction(XRD), sample vibrating magnetometry (VSM) and scanning electron microscopy (SEM). The sub-microspheres were mixed with paraffin (1:1 in mass ratio) to form a ring sample for measuring the complex electromagnetic parameters in the frequency range of 2 — 18 GHz. It is found that the flower-like Fe3O4 sub-microspheres exhibits excellent microwave absorption properties in the high frequency range due to the orientational polarization, natural resonance and eddy current loss.%采用溶剂热法制得具有花状结构的Fe3O4亚微米球,该微球直径约4μm,是由Fe3O4纳米片组装而成的.采用X线衍射仪(XRD)、振动样品磁强计(VSM)和扫描电子显微镜(SEM)对产物结构、磁性和形貌进行表征.将样品与石蜡按质量比1:1制成同轴样品,测试其2~18 GHz下的电磁参数并进行分析计算.研究发现,由于偶极子极化、自然共振和涡流损耗,具有花状结构的Fe3O4亚微米球在高频范围内显示出了较为良好的宽频吸收特性.

  6. Magnetic and microwave absorption properties of BaMn{sub x}Co{sub 1−x}TiFe{sub 10}O{sub 19}

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lin [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Yu, Hongtao, E-mail: yuhongtao@swust.edu.cn [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Ren, Xiaohu [Southwest Institute of Applied Magnetics, Mianyang 621010 (China); Xu, Guangliang [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China)

    2014-03-05

    Highlights: • In this work, we firstly used Mn substitution for Co in BaCo{sub 1.0}Ti{sub 1.0}Fe{sub 10}O{sub 19}. • Mn Substitution effectively improved microwave absorber and enlarged bandwidth. • The absorbing peak shift to high microwave frequency with Mn substitution. • The coercivity and remanent magnetization increased with Mn substitution. -- Abstract: For turning the magnetic resonance frequency and bandwidth of the reflection loss, different amounts of manganese (Mn) were incorporated into the BaCoTiFe{sub 10}O{sub 19} for the substitution of cobalt (Co), then the BaMn{sub x}Co{sub 1−x}TiFe{sub 10}O{sub 19} was obtained via the solid-state reaction method. Subsequently, the effect of the doping Mn{sup 2+} on microwave absorption performances was detailedly studied in a frequency range from 2 to 18 GHz. The crystal volume expanded with increasing Mn{sup 2+} substitution as confirmed by X-ray diffraction results. No significant morphology change could be found in the scanning electron microscope images when Co{sup 2+} was partially substituted by Mn{sup 2+}, but the coercivity and remanent magnetization raised as Mn{sup 2+} increased. The complex permittivity and permeability were collected by the vector net-analyzer and the absorbing properties were calculated according to transmission theory. The absorption peak shifted to higher frequencies with the substitution. The maximum loss value of −30.5 dB at 13.4 GHz was observed for the x = 0.6 sample. Based on the magnetic and microwave measurements, BaMn{sub x}Co{sub 1−x}TiFe{sub 10}O{sub 19} may be a good candidate for electromagnetic compatibility and other practical applications at high frequencies.

  7. Blue shift in optical absorption, magnetism and light-induced superparamagnetism in γ-Fe{sub 2}O{sub 3} nanoparticles formed in dendrimer

    Energy Technology Data Exchange (ETDEWEB)

    Domracheva, Natalia E., E-mail: ndomracheva@gmail.com; Vorobeva, Valerya E. [Zavoisky Kazan Physical-Technical Institute (Russian Federation); Gruzdev, Matvey S. [Institute of Solution Chemistry (Russian Federation); Pyataev, Andrew V. [Kazan Federal University (Russian Federation)

    2015-02-15

    We are presenting the investigation of the optical, magnetic, and photoinduced superparamagnetic properties of single-domain γ-Fe{sub 2}O{sub 3} nanoparticles (NPs) with diameters of about 2.5 nm formed in second-generation poly(propylene imine) dendrimer. The optical absorption studies indicated direct allowed transition with the band gap (4.5 eV), which is blue shift with respect to the value of the bulk material. Low-temperature blocking of the NPs magnetic moments at 18 K is determined by SQUID measurements. The influence of pulsed laser irradiation on the superparamagnetic properties of γ-Fe{sub 2}O{sub 3} NPs was studied by EPR spectroscopy. It has been shown that irradiation of the sample held in vacuo and cooled in zero magnetic field to 6.9 K leads to the appearance of a new EPR signal, which decays immediately after the irradiation is stopped. The appearance and disappearance of this new signal can be repeated many times at 6.9 K when we turn on/turn off the laser. We suppose that the generation of conduction band electrons by irradiation into the band gap of the γ-Fe{sub 2}O{sub 3} changes the superparamagnetic properties of NPs. Graphical Abstract: Features of the behavior of single-domain γ-Fe{sub 2}O{sub 3} nanoparticles formed in dendrimer were found by UV-Vis and EPR spectroscopy: “blue” shift in optical absorption, a significant increase in the band gap width and variation of superparamagnetic properties under light irradiation.

  8. Direct and simultaneous determination of Cr and Fe in crude oil using high-resolution continuum source graphite furnace atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Dittert, Ingrid M. [Departamento de Quimica, Universidade Federal de Santa Catarina, Campus Universitario, Trindade, 88040-900, Florianopolis, SC (Brazil); Silva, Jessee S.A. [Centro Federal de Educacao Tecnologica de Santa Catarina, Florianopolis, SC (Brazil); Araujo, Rennan G.O. [Departamento de Quimica, Universidade Federal de Santa Catarina, Campus Universitario, Trindade, 88040-900, Florianopolis, SC (Brazil)], E-mail: rgoa01@terra.com.br; Curtius, Adilson J.; Welz, Bernhard [Departamento de Quimica, Universidade Federal de Santa Catarina, Campus Universitario, Trindade, 88040-900, Florianopolis, SC (Brazil); Becker-Ross, Helmut [ISAS, Institute for Analytical Sciences, Department of Interface Spectroscopy, Albert-Einstein-Str. 9, 12489 Berlin (Germany)

    2009-06-15

    A simple, fast and sensitive direct method for the simultaneous determination of Cr and Fe in crude oil samples is proposed using high-resolution continuum source graphite furnace atomic absorption spectrometry. No sample preparation is used except for a 10-minute homogenization in an ultrasonic bath. Aliquots of 0.1-4 mg of the samples are weighed onto solid sampling platforms and analyzed directly using aqueous standards for calibration. The simultaneous determination was possible because there is a secondary Fe line at 358.120 nm in the vicinity of the most sensitive Cr line at 357.868 nm, and both absorption lines were within the wavelength interval covered by the linear charge-coupled device array detector. It has also been of advantage that the sensitivity ratio between the two analytical lines corresponded roughly to the concentration ratio of the two elements found in crude oil, and that both analytes have very similar volatility, so that no compromises had to be made regarding pyrolysis and atomization temperatures. Two oil reference materials have been analyzed and the results were in agreement with the certified or reported values. Characteristic masses of 3.6 pg and 0.5 ng were obtained for Cr and Fe, respectively. The limits of detection (3{sigma}, n = 10) were 1 {mu}g kg{sup - 1} for Cr and 0.6 mg kg{sup - 1} for Fe, and the precision, expressed as the relative standard deviation, ranged from 4 to 20%, which is often acceptable for a rapid direct analytical procedure. Five crude oils samples were analyzed.

  9. Direct and simultaneous determination of Cr and Fe in crude oil using high-resolution continuum source graphite furnace atomic absorption spectrometry

    Science.gov (United States)

    Dittert, Ingrid M.; Silva, Jessee S. A.; Araujo, Rennan G. O.; Curtius, Adilson J.; Welz, Bernhard; Becker-Ross, Helmut

    2009-06-01

    A simple, fast and sensitive direct method for the simultaneous determination of Cr and Fe in crude oil samples is proposed using high-resolution continuum source graphite furnace atomic absorption spectrometry. No sample preparation is used except for a 10-minute homogenization in an ultrasonic bath. Aliquots of 0.1-4 mg of the samples are weighed onto solid sampling platforms and analyzed directly using aqueous standards for calibration. The simultaneous determination was possible because there is a secondary Fe line at 358.120 nm in the vicinity of the most sensitive Cr line at 357.868 nm, and both absorption lines were within the wavelength interval covered by the linear charge-coupled device array detector. It has also been of advantage that the sensitivity ratio between the two analytical lines corresponded roughly to the concentration ratio of the two elements found in crude oil, and that both analytes have very similar volatility, so that no compromises had to be made regarding pyrolysis and atomization temperatures. Two oil reference materials have been analyzed and the results were in agreement with the certified or reported values. Characteristic masses of 3.6 pg and 0.5 ng were obtained for Cr and Fe, respectively. The limits of detection (3 σ, n = 10) were 1 µg kg - 1 for Cr and 0.6 mg kg - 1 for Fe, and the precision, expressed as the relative standard deviation, ranged from 4 to 20%, which is often acceptable for a rapid direct analytical procedure. Five crude oils samples were analyzed.

  10. Microstructure, hysteresis and microwave absorption analysis of Ba{sub (1-x)}Sr{sub x}Fe{sub 12}O{sub 19} ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Narang, S. Bindra [Department of Electronics Technology, Guru Nanak Dev University, Amritsar, Punjab (India)], E-mail: sukhleen2@yahoo.com; Singh, Charanjeet [Department of Electronics and Communication Engineering, Amritsar College of Engineering and Technology, Mananwala, Amritsar, Punjab (India); Bai Yang [School of Materials Science and Engineering, University of Science and Technology Beijing (China); Hudiara, I.S. [KC College of Engg. and IT, Nawanshahar, Punjab (India)

    2008-10-15

    M-type hexagonal ferrite series, Ba{sub (1-x)}Sr{sub x}Fe{sub 12}O{sub 19} (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0), has been synthesized by conventional ceramic method. Hysteresis parameters have been investigated at an applied field of 10 kOe and absorption has been studied at X-band as a function of thickness, substitution and frequency. Microstructure and X-ray diffraction confirmed hexagonal structure of ferrite. The substitution causes profound increase in absorption, coercivity and magnetization. The magnetic parameters have been characterized by taking into account microstructure and preferential site occupancy. Curie temperature decreases with substitution due to the formation of spin canting structure.

  11. MODELING THE Fe K LINE PROFILES IN TYPE I ACTIVE GALACTIC NUCLEI WITH A COMPTON-THICK DISK WIND

    Energy Technology Data Exchange (ETDEWEB)

    Tatum, M. M.; Turner, T. J. [Department of Physics, University of Maryland, Baltimore County, Baltimore, MD 21250 (United States); Sim, S. A. [Research School of Astronomy and Astrophysics, Mount Stromlo Observatory, Cotter Road, Weston Creek, ACT 2611 (Australia); Miller, L. [Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Reeves, J. N.; Patrick, A. R. [Astrophysics Group, School of Physical and Geographical Sciences, Keele University, Keele, Staffordshire ST5 5BG (United Kingdom); Long, K. S. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2012-06-20

    We have modeled a small sample of Seyfert galaxies that were previously identified as having simple X-ray spectra with little intrinsic absorption. The sources in this sample all contain moderately broad components of Fe K-shell emission and are ideal candidates for testing the applicability of a Compton-thick accretion disk wind model to active galactic nucleus (AGN) emission components. Viewing angles through the wind allow the observer to see the absorption signature of the gas, whereas face-on viewing angles allow the observer to see the scattered light from the wind. We find that the Fe K emission line profiles are well described with a model of a Compton-thick accretion disk wind of solar abundances, arising tens to hundreds of gravitational radii from the central black hole. Further, the fits require a neutral component of Fe K{alpha} emission that is too narrow to arise from the inner part of the wind, and likely comes from a more distant reprocessing region. Our study demonstrates that a Compton-thick wind can have a profound effect on the observed X-ray spectrum of an AGN, even when the system is not viewed through the flow.

  12. X-ray Absorption Measurements on Nickel Cathode of Sodium-beta Alumina batteries: Fe-Ni-CI Chemical Associations

    Energy Technology Data Exchange (ETDEWEB)

    Bowden, Mark E.; Alvine, Kyle J.; Fulton, John L.; Lemmon, John P.; Lu, Xiaochuan; Webb-Robertson, Bobbie-Jo M.; Heald, Steve M.; Balasubramanian, Mahalingam; Mortensen, Devon R.; Seidler, Gerald T.; Hess, Nancy J.

    2014-02-01

    Sections of Na-Al-NiCl2 cathodes from sodium-beta alumina ZEBRA batteries have been characterized with X-ray fluorescence mapping, and XANES measurements to probe the microstructure, elemental correlation, and chemical speciation after voltage cycling. Cycling was performed under identical load conditions at either 240 or 280 °C operating temperature and subsequently quenched in either the charged or discharged state. X-ray fluorescence mapping and XANES measurements were made adjacent to the current collector and β"-Al2O3 solid electrolyte interfaces to detect possible gradients in chemical properties across the cathode. An FeS additive, introduced during battery synthesis, was found to be present as either Fe metal or an Fe(II) chloride in all cathode samples. X-ray fluorescence mapping reveals an operating temperature and charge-state dependent spatial correlation between Fe, Ni, and Cl concentration. XANES measurements indicate that both Ni and Fe are chemically reactive and shift between metallic and chloride phases in the charged and discharged states, respectively. However the percentage of chemically active Ni and Fe is significantly less in the cell operated at lower temperature. Additionally, the cathode appeared chemically homogeneous at the scale of our X-ray measurements.

  13. Coherent Hole-burning, Mollow Absorption Effect, and Four-wave Mixing in Cycling Transition Fe=0(←→)Fg=1 Subject to a Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    古英; 孙庆青; 龚旗煌

    2004-01-01

    @@ We investigate the quantum coherence effects of a cycling transition Fe=0(←→)Fg=1, which is saturated and probed by the circular polarized fields, and is subject to a linearly polarized field and a magnetic field.Saturation field is applied in the case of the maximum coherence between the drive Rabi frequency and magnetic field, corresponding to the electromagnetically induced absorption (EIA) with negative dispersion found by Gu et al.In a small saturation Rabi frequency, the holes are burned in two Autler-Towns peaks outside two symmetric electromagnetically induced transparency (EIT) windows due to the two-photon resonance.When the saturation Rabi frequency is comparable with the drive Rabi frequency, the holes caused by the coherent population oscillation appear in the EIA spectrum.Continuing to increase the saturation Rabi frequency, we observe several emission peaks due to the Mollow absorption effects.Simultaneously, four-wave mixing (FWM) effects in this process are discussed.In the picture of dressed states, we explain the multi-peaks of quantum efficiency of FWM in terms of the multi-photon resonance conditions.We also find a good agreement between the absorption peaks and the FMW peaks.Finally, whenever EIA, EIT, or Mollow absorption happens, the dispersion at the pump-probe detuning center is kept to be negative with increasing the saturation Rabi frequency.It means that this point is suitable to perform the superluminal light propagation experiments.

  14. Thickness and Composition Tailoring of K- and Ka-Band Microwave Absorption of BaCo x Ti x Fe(12-2 x)O19 Ferrites

    Science.gov (United States)

    Narang, Sukhleen Bindra; Pubby, Kunal; Singh, Charanjeet

    2017-02-01

    The goal of this research is to investigate the electromagnetic and microwave absorption properties of M-type barium hexaferrites with chemical formula BaCo x Ti x Fe(12-2 x)O19 ( x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) in K and Ka band. Characterization techniques such as x-ray diffraction analysis and scanning electron microscopy were applied to confirm ferrite formation. The frequency dependence of the complex permittivity and complex permeability was studied for prepared ferrite samples in the frequency range from 18 GHz to 40 GHz. Factors such as the quarter-wavelength condition, impedance matching, high dielectric-magnetic losses, as well as ferromagnetic resonance were investigated to determine their contribution to the absorption characteristics. It was found that the quarter-wavelength ( λ/4) model could be successfully applied to predict and understand the position as well as number of reflection peaks in the microwave absorption spectrum. The origin of the reflection loss peaks is explained and verified based on calculations of input impedance, loss tangent, and ferromagnetic resonance. Reflection loss analysis revealed that all six compositions exhibited reflection loss peaks (absorption >90%) at their matching thicknesses and frequencies. Therefore, these ferrites are potential candidates for use in electromagnetic shielding applications requiring low reflectivity in K and Ka band.

  15. 石墨烯/Fe3O4复合材料的制备及电磁波吸收性能%Synthesis of Graphene/Fe3O4 Composite Materials and Their Electromagnetic Wave Absorption Properties

    Institute of Scientific and Technical Information of China (English)

    李国显; 王涛; 薛海荣; 胡园园; 何建平

    2011-01-01

    For expanding the application field of grahene. Electromagnetic wave absorption performance of the magnetic functionalization graphene has been researched in this paper. Graphene/Fe3O4 nanoparticle composites are prepared by microwave irradiating the suspension of graphite oxide and Fe3O, in the presence of hydrazine hydrate. Transmission electron microscopy and X-ray diffraction are used to characterize the structure and the distribution condition of the composites. Vector network analyzer is used to measure the complex permittivity and complex permeability of the composites in the frequency range of 0.1-18. 0 GHz. The permittivity dispersion behaviors are explained based on the Cole-Cole model. The reflection loss curves are calculated using computer simulation technique. Calculation results from the complex permittivity and permeability show that when the mass ratio of graphene to Fe3O4 is 10:1. Reflection losses exceeding - 20 dB can be obtained in the frequency range of 6.5-8.7 GHz for absorber thicknesses of 2.0-2.5 mm. By changing the relative content of the Fe3 O4 nanoparticles, minimum reflection loss can be obtained at -49.7 dB. Strong absorption properties of the composites indicate its potentially application as electromagnetic wave absorption material.%为扩展石墨烯的应用领域,对磁性功能化石墨烯的电磁波吸收性能进行研究.在氧化石墨与Fe3 O4粒子的悬浮液中添加还原剂水合肼,微波辐照反应制备石墨烯/Fe3 O4复合物.采用X射线衍射、透射电镜等手段对材料的结构和Fe3 O4的分布状态进行了测试表征.采用矢量网络分析仪测定了材料在0.1~18.0 GHz频率范围内的复介电常数和复磁导率.利用Cole-Cole图解释了复合材料的介电特性.利用计算机模拟出不同厚度材料的电磁波衰减性能.结果表明,当石墨烯和Fe3 O4粒子以质量比10∶1复合得到的吸波剂材料的匹配厚度在2.0~2.5 mm变化时,反射损耗小于一20 d

  16. 绿柱石中的Fe2+的d-d跃迁分析%An investigation of absorption spectra of Fe2+ doped in beryl crystal

    Institute of Scientific and Technical Information of China (English)

    王先龙; 杜懋陆; 赵林; 崔江; 文久富; 龙梅

    2010-01-01

    本文引入平均共价因子模型及有效电荷, 计算了绿柱石晶体中的Fe2+离子的d-d跃迁, 并和实验数据进行了详细的比较, 对实验结果中吸收峰进行了识别.结果表明, 实验与理论相符合.

  17. Pengaruh Lama Miling Terhadap Sifat Absorpsi Material Penyimpan Hidrogen MgH2 yang Dikatalisasi Dengan Fe (The Role of Milling Time on the Absorption Behaviour of MgH2 Catalyzed by Fe

    Directory of Open Access Journals (Sweden)

    Mustanir Mustanir

    2009-12-01

    Full Text Available Hidrida logam berbasis MgH2 dengan sisipan 1 wt% katalis Fe telah berhasil disintesis dengan teknik ball milling. Hasil proses miling selama 80 jam menunjukkan bahwa ukuran butir material telah membentuk struktur nanokristal. Hal ini ditunjukkan oleh profil difraksi sinar-X dimana terjadi pelebaran puncakpuncak difraksinya dengan meningkatnya waktu miling. Hasil uji absorpsi secara gravimetrik diketahui bahwa MgH2 berkatalis 1 wt% Fe mampu menyerap hydrogen sebesar 5,5 wt% dalam waktu ~20 menit pada temperatur 300 oC. Hasil ini sekaligus memperlihatkan bahwa sejumlah kecil katalis Fe bekerja secara baik dalam memperbaiki sifat absorpsi material penyimpan hydrogen berbasis Mg.(Metal hydrides are of great interest as hydrogen storage media especially for automotive application. Hydrides of magnesium and magnesium alloys are particularly attractive as they combine potentially high hydrogen storage capacities, 7.6 wt%. But, unfortunately, the sorption properties are poor. For example, conventional hydrogenation of magnesium requires prolonged treatment at temperatures of 300 oC and above. Here, we report the absorption properties of MgH2 catalyzed with a small amount of Fe element (1wt% under argon atmosphere prepared by ball milling in 80 hours. As the results, it showed the influence of milling time on the absortion kinetics of material which could absorp hydrogen in amount 5.5 within 20 minutes at 300 oC. It is obvious that longer milling time and small amount of catalyst could improve the sorption properties of Mg-based hydrides. © 2009 BCREC UNDIP. All rights reserved[Received: 13rd November 2009, Revised: 25th December 2009, Accepted: 31st December 2009][How to Cite: M. Mustanir, Z. Jalil. (2009. Pengaruh Lama Miling Terhadap Sifat Absorpsi Material Penyimpan Hidrogen MgH2 yang Dikatalisasi Dengan Fe (The Role of Milling Time on the Absorption Behaviour of MgH2 Catalyzed by Fe. Bulletin of Chemical Reaction Engineering and Catalysis, 4(2: 69

  18. Pengaruh Lama Miling Terhadap Sifat Absorpsi Material Penyimpan Hidrogen MgH2 yang Dikatalisasi Dengan Fe (The Role of Milling Time on the Absorption Behaviour of MgH2 Catalyzed by Fe

    Directory of Open Access Journals (Sweden)

    Mustanir Mustanir

    2009-12-01

    Full Text Available Hidrida logam berbasis MgH2 dengan sisipan 1 wt% katalis Fe telah berhasil disintesis dengan teknik ball milling. Hasil proses miling selama 80 jam menunjukkan bahwa ukuran butir material telah membentuk struktur nanokristal. Hal ini ditunjukkan oleh profil difraksi sinar-X dimana terjadi pelebaran puncakpuncak difraksinya dengan meningkatnya waktu miling. Hasil uji absorpsi secara gravimetrik diketahui bahwa MgH2 berkatalis 1 wt% Fe mampu menyerap hydrogen sebesar 5,5 wt% dalam waktu ~20 menit pada temperatur 300 oC. Hasil ini sekaligus memperlihatkan bahwa sejumlah kecil katalis Fe bekerja secara baik dalam memperbaiki sifat absorpsi material penyimpan hydrogen berbasis Mg.(Metal hydrides are of great interest as hydrogen storage media especially for automotive application. Hydrides of magnesium and magnesium alloys are particularly attractive as they combine potentially high hydrogen storage capacities, 7.6 wt%. But, unfortunately, the sorption properties are poor. For example, conventional hydrogenation of magnesium requires prolonged treatment at temperatures of 300 oC and above. Here, we report the absorption properties of MgH2 catalyzed with a small amount of Fe element (1wt% under argon atmosphere prepared by ball milling in 80 hours. As the results, it showed the influence of milling time on the absortion kinetics of material which could absorp hydrogen in amount 5.5 within 20 minutes at 300 oC. It is obvious that longer milling time and small amount of catalyst could improve the sorption properties of Mg-based hydrides. © 2009 BCREC UNDIP. All rights reserved[Received: 13rd November 2009, Revised: 25th December 2009, Accepted: 31st December 2009][How to Cite: M. Mustanir, Z. Jalil. (2009. Pengaruh Lama Miling Terhadap Sifat Absorpsi Material Penyimpan Hidrogen MgH2 yang Dikatalisasi Dengan Fe (The Role of Milling Time on the Absorption Behaviour of MgH2 Catalyzed by Fe. Bulletin of Chemical Reaction Engineering and Catalysis, 4(2: 69

  19. xLIPA: Promotion of Electrons from the K-shell to 2 GeV using 10 PW Laser Pulses

    Science.gov (United States)

    2015-08-19

    xLIPA : Promotion of electrons from the K-shell to 2 GeV using 10 PW laser pulses D.F. Gordon, J.P. Palastro, B. Hafizi, D. Kaganovich, L. Johnson...20] N. Kumar, K.Z. Hatsagortsyan, and C.H. Keitel. Radiation-reaction-force-induced nonlinear mixing of Raman sidebands of an ultraintense laser...RESPONSIBLE PERSON 19b. TELEPHONE NUMBER (include area code) b. ABSTRACT c. THIS PAGE 18. NUMBER OF PAGES 17. LIMITATION OF ABSTRACT xLIPA: Promotion of

  20. Computation of triple differential cross-sections with the inclusion of exchange effects in atomic K-shell ionization by relativistic electrons for symmetric geometry

    Indian Academy of Sciences (India)

    S Dhar; M R Alam

    2007-09-01

    The triple differential cross-section for K-shell ionization of silver and copper atoms by relativistic electrons have been computed in the coplanar symmetric geometry with the inclusion of exchange effects following the multiple scattering theory of Das and Seal [1] multiplied by suitable spinors. Present computed results are marginally improved in some cases from the previous computed results [2]. Present results are compared with measured values [3] and with previous computation results [2]. Some other theoretical computational results are also presented here for comparison.

  1. Measurements of the K -Shell Opacity of a Solid-Density Magnesium Plasma Heated by an X-Ray Free-Electron Laser

    Science.gov (United States)

    Preston, T. R.; Vinko, S. M.; Ciricosta, O.; Hollebon, P.; Chung, H.-K.; Dakovski, G. L.; Krzywinski, J.; Minitti, M.; Burian, T.; Chalupský, J.; Hájková, V.; Juha, L.; Vozda, V.; Zastrau, U.; Lee, R. W.; Wark, J. S.

    2017-08-01

    We present measurements of the spectrally resolved x rays emitted from solid-density magnesium targets of varying sub-μ m thicknesses isochorically heated by an x-ray laser. The data exhibit a largely thickness-independent source function, allowing the extraction of a measure of the opacity to K -shell x rays within well-defined regimes of electron density and temperature, extremely close to local thermodynamic equilibrium conditions. The deduced opacities at the peak of the K α transitions of the ions are consistent with those predicted by detailed atomic-kinetics calculations.

  2. Magnetic properties and microwave absorption properties of short carbon fibres coated by Ni–Fe alloy coatings

    Indian Academy of Sciences (India)

    Ying Liu; Chengwen Qiang

    2015-12-01

    Ni–Fe alloy coatings were successfully prepared on carbon fibre (CF) surfaces bymeans of electroplating at 25°C for 560 s. The structures and morphologies of the composite were characterized using X-ray diffraction and scanning electron microscopy. The coercivity () and saturation magnetization () of the Fe0.45Ni0.55/CF composites were 45.19 Oe and 1513.59 emu g−1, respectively. The reflectivity of Fe0.45Ni0.55/CF composites was less than −5 dB over the range of 1.1–5.4 GHz. The reflectivity of Fe0.45Ni0.55/CF composites was less than −10 dB over the range of 1.6–2.1 GHz. The lowest reflectivity of the Fe0.45Ni0.55/CF composites was −14.7 dB at 2.0 GHz and the corresponding thickness was 3.3 mm.

  3. Magnetic properties and microwave absorption properties of carbon fibers coated by Fe{sub 3}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Qiang Chengwen [Key Lab for Magnetism and Magnetic Materials of MOE, Lanzhou University, Lanzhou 730000 (China); Department of Materials Science and Engineering, Lanzhou University, Lanzhou 730000 (China); Xu Jincheng, E-mail: xuhuan@lzu.edu.c [Key Lab for Magnetism and Magnetic Materials of MOE, Lanzhou University, Lanzhou 730000 (China); Department of Materials Science and Engineering, Lanzhou University, Lanzhou 730000 (China); Zhang Zhongquan; Tian Liangliang; Xiao Songtao; Liu Ying; Xu Peng [Key Lab for Magnetism and Magnetic Materials of MOE, Lanzhou University, Lanzhou 730000 (China); Department of Materials Science and Engineering, Lanzhou University, Lanzhou 730000 (China)

    2010-09-10

    Fe{sub 3}O{sub 4} nanoparticles were plated on carbon fibers from nitrate and dimethylamine borane solution at 90 {sup o}C for 1 h. The structures and morphologies of the composite were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The thickness of the Fe{sub 3}O{sub 4} films is about 1 {mu}m. The saturation magnetization of the Fe{sub 3}O{sub 4}/CFs composites reaches 39.5 emu/g and coercivity reaches 166.9 Oe. The reflectivity of Fe{sub 3}O{sub 4} nanoparticles covered carbon fiber (2.90-5.12 mm in thickness) is less than -10 dB over the range of 3.52-10.01 GHz and -20 dB over the range of 5.49-7.75 GHz. The lowest reflectivity of the Fe{sub 3}O{sub 4}/CFs composites is -35 dB at 6.37 GHz for a layer of 4.41 mm in thickness.

  4. Infrared optical absorption in low-spin Fe 2+ -doped SrTiO 3

    Energy Technology Data Exchange (ETDEWEB)

    Comes, Ryan B.; Kaspar, Tiffany C.; Heald, Steve M.; Bowden, Mark E.; Chambers, Scott A.

    2016-01-06

    Band gap engineering in SrTiO3 and related titanate perovskites has long been explored due to the intriguing properties of the materials for photocatalysis and photovoltaic applications. A popular approach in the materials chemistry community is to substitutionally dope aliovalent transition metal ions onto the B site in the lattice to alter the valence band. However, in such a scheme there is limited control over the dopant valence, and compensating defects often form. Here we demonstrate a novel technique to controllably synthesize Fe2+- and Fe3+-doped SrTiO3 thin films without formation of compensating defects by co-doping with La3+ ions on the A site. We stabilize Fe2+-doped films by doping with two La ions for every Fe dopant, and find that the Fe ions exhibit a low-spin electronic configuration, producing optical transitions in the near infrared regime and degenerate doping. The novel electronic states observed here offer a new avenue for band gap engineering in perovskites for photocatalytic and photovoltaic applications.

  5. 尖锥八面体Fe3O4的水热合成及微波吸收性能%Hydrothermal synthesis and microwave absorption of sharp octahedral Fe3O4 crystals

    Institute of Scientific and Technical Information of China (English)

    周克省; 卢玉娥; 尹荔松; 秦宪明; 邓联文; 翟志彩; 夏辉

    2012-01-01

    With mixed solution of PEG-6000 and water as a reaction medium, Fe3O4 crystal particles were synthesized by hydrothermal method from Fe(OH)2 precursor oxidized by Na2S2O3 in alkaline conditions. The crystal structure and surface morphology of the products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The complex dielectric constant and complex permeability of Fe3O4 samples were measured by microwave vector network analyzer in the frequency range from 2 to 18 GHz. The microwave reflection coefficients of the samples were calculated according to measurements and the microwave absorbing mechanism was discussed. The results show that monodisperse spinel-type Fe3O4 crystal particles with regular sharp octahedral shape and flat surface are obtained by hydrothermal reaction in a certain time, and the microwave reflection coefficient peak of the sample with 2.8 mm thickness is -35 dB at 7.1 GHz frequency and the absorption bandwidth less than -10 dB is 7.9 GHz after hydrothermal growth of 12 h. The microwave absorption is caused by magnetic loss mainly and dielectric loss secondly in the low-frequency range of 2-13 GHz, while dielectric loss mainly but magnetic loss weakly in the high-frequency range of 13-18 GHz. So, the sharp micro-octahedral Fe3O4 is an excellent microwave absorption material with low reflectivity and broadband.%采用水热法,在碱性条件下,以PEG-6000与水的混合溶液为反应介质,以硫代硫酸钠氧化前驱体氢氧化亚铁制备Fe3O4晶粉.采用X线衍射仪(XRD)和扫描电子显微镜(SEM)对产物结构和形貌进行表征.用微波矢量网络分析仪测试了样品在2~18 GHz微波频率范围内的复介电常数和复磁导率,计算微波反射系数,探讨材料的微波损耗机制.研究结果表明:在水热反应一定时间后,得到单分散的尖晶石型Fe3O4晶粒,颗粒呈规则的尖锥八面体形貌且表面平整;对反应为12h、厚度为2.8 mm

  6. An Fe XXIV Absorption Line in the Persistent Spectrum of the Dipping Low-Mass X-Ray Binary 1A 1744-361

    Science.gov (United States)

    Gavriil, Fotis P.; Strohmayer, Tod E.; Bhattacharyya, Sudip

    2012-01-01

    We report on Chandra X-ray Observatory (Chandra) High Energy Transmission Grating spectra of the dipping low-mass X-ray binary 1A 1744-361 during its 2008 July outburst. We find that its persistent emission is well modeled by a blackbody (kT approx. 1.0 keV) plus power law (Gamma approx. 1.7) with an absorption edge. In the residuals of the combined spectrum, we find a significant absorption line at 6.961 +/- 0.002 keV, consistent with the Fe xxvi (hydrogen-like Fe) 2-1 transition.We place an upper limit on the velocity of a redshifted flow of nu 103.6 erg cm/s. We discuss what implications the feature has on the system and its geometry. We also present Rossi X-ray Timing Explorer data accumulated during this latest outburst and, via an updated color-color diagram, clearly show that 1A 1744-361 is an "atoll" source

  7. Strongly Variable z=1.48 MgII and FeII Absorption in the Spectra of z=4.05 GRB 060206

    CERN Document Server

    Hao, H; Dobrzycki, A; Matheson, T; Bentz, M C; Kuraszkiewicz, J; Garnavich, P M; Howk, J C; Calkins, M L; Worthey, G; Modjaz, M; Serven, J

    2006-01-01

    We report on the discovery of strongly variable MgII and FeII absorption lines seen at z=1.48 in the spectra of the z=4.05 GRB 060206 obtained between 4.13 to 7.63 hours after the burst. In particular, the FeII line equivalent width (EW) decayed rapidly from 1.72+-0.25 AA to 0.28+-0.21 AA, only to increase to 0.96+-0.21 AA in a later date spectrum. The MgII doublet shows even more complicated evolution: the weaker line of the doublet drops from 2.05+-0.25 AA to 0.92+-0.32 AA, but then more than doubles to 2.47+-0.41 AA in later data. The ratio of the EWs for the MgII doublet is also variable, being closer to 1:1 (saturated regime) when the lines are stronger and becoming closer to 2:1 (unsaturated regime) when the lines are weaker, consistent with expectations based on atomic physics. We have investigated and rejected the possibility of any instrumental or atmospheric effects causing the observed strong variations. The possibility of variable intervening absorption in GRB spectra was recently predicted by Fra...

  8. Ultraviolet photochemical reaction of [Fe(III)(C2O4)3](3-) in aqueous solutions studied by femtosecond time-resolved X-ray absorption spectroscopy using an X-ray free electron laser.

    Science.gov (United States)

    Ogi, Y; Obara, Y; Katayama, T; Suzuki, Y-I; Liu, S Y; Bartlett, N C-M; Kurahashi, N; Karashima, S; Togashi, T; Inubushi, Y; Ogawa, K; Owada, S; Rubešová, M; Yabashi, M; Misawa, K; Slavíček, P; Suzuki, T

    2015-05-01

    Time-resolved X-ray absorption spectroscopy was performed for aqueous ammonium iron(III) oxalate trihydrate solutions using an X-ray free electron laser and a synchronized ultraviolet laser. The spectral and time resolutions of the experiment were 1.3 eV and 200 fs, respectively. A femtosecond 268 nm pulse was employed to excite [Fe(III)(C2O4)3](3-) in solution from the high-spin ground electronic state to ligand-to-metal charge transfer state(s), and the subsequent dynamics were studied by observing the time-evolution of the X-ray absorption spectrum near the Fe K-edge. Upon 268 nm photoexcitation, the Fe K-edge underwent a red-shift by more than 4 eV within 140 fs; however, the magnitude of the redshift subsequently diminished within 3 ps. The Fe K-edge of the photoproduct remained lower in energy than that of [Fe(III)(C2O4)3](3-). The observed red-shift of the Fe K-edge and the spectral feature of the product indicate that Fe(III) is upon excitation immediately photoreduced to Fe(II), followed by ligand dissociation from Fe(II). Based on a comparison of the X-ray absorption spectra with density functional theory calculations, we propose that the dissociation proceeds in two steps, forming first [(CO2 (•))Fe(II)(C2O4)2](3-) and subsequently [Fe(II)(C2O4)2](2-).

  9. Ultraviolet photochemical reaction of [Fe(III(C2O43]3− in aqueous solutions studied by femtosecond time-resolved X-ray absorption spectroscopy using an X-ray free electron laser

    Directory of Open Access Journals (Sweden)

    Y. Ogi

    2015-05-01

    Full Text Available Time-resolved X-ray absorption spectroscopy was performed for aqueous ammonium iron(III oxalate trihydrate solutions using an X-ray free electron laser and a synchronized ultraviolet laser. The spectral and time resolutions of the experiment were 1.3 eV and 200 fs, respectively. A femtosecond 268 nm pulse was employed to excite [Fe(III(C2O43]3− in solution from the high-spin ground electronic state to ligand-to-metal charge transfer state(s, and the subsequent dynamics were studied by observing the time-evolution of the X-ray absorption spectrum near the Fe K-edge. Upon 268 nm photoexcitation, the Fe K-edge underwent a red-shift by more than 4 eV within 140 fs; however, the magnitude of the redshift subsequently diminished within 3 ps. The Fe K-edge of the photoproduct remained lower in energy than that of [Fe(III(C2O43]3−. The observed red-shift of the Fe K-edge and the spectral feature of the product indicate that Fe(III is upon excitation immediately photoreduced to Fe(II, followed by ligand dissociation from Fe(II. Based on a comparison of the X-ray absorption spectra with density functional theory calculations, we propose that the dissociation proceeds in two steps, forming first [(CO2•Fe(II(C2O42]3− and subsequently [Fe(II(C2O42]2−.

  10. Only Ku-band microwave absorption by Fe{sub 3}O{sub 4}/ferrocenyl-CuPc hybrid nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Wei Junji; Zhao Rui [Research Branch of Functional Materials, Institute of Microelectronic and Solid State Electronic, High-Temperature Resistant Polymers and Composites Key Laboratory of Sichuan Province, University of Electronic Science and Technology of China, Chengdu 610054 (China); Liu Xiaobo, E-mail: liuxb@uestc.edu.cn [Research Branch of Functional Materials, Institute of Microelectronic and Solid State Electronic, High-Temperature Resistant Polymers and Composites Key Laboratory of Sichuan Province, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2012-10-15

    A novel kind of hybrid nanospheres made of Fe{sub 3}O{sub 4} and ferrocenyl-CuPc (FCP) was prepared via effective solvothermal method and performed microwave absorptivity only in Ku-band with minimum reflection loss of -25 dB at 16.0 GHz corresponding to absorbing about 99.7% content of microwave. Scanning electron microscopy images indicated that the nanospheres with uniform particle size distribution have the average diameter of 135 nm. Due to the synergistic reaction between magnetic ferrocenyl-CuPc and Fe{sub 3}O{sub 4}, the hybrid nanospheres showed novel electromagnetic properties. The real part of complex permittivity of hybrid nanospheres remains stable in the range of 0.5-12.0 GHz and has a large fluctuation at 16.5 GHz. Moreover, the dielectric loss of hybrid nanospheres also appeared a sharp peak at 16.3 GHz with the value of 2.7. The specific gravity of hybrid nanospheres is about 2.08. On the basis of these results, the novel hybrids are believed to have potential applications in the microwave absorbing area in Ku-band. - Highlights: Black-Right-Pointing-Pointer A novel kind of ferrocenyl-CuPc/Fe{sub 3}O{sub 4} hybrid nanospheres was prepared. Black-Right-Pointing-Pointer The hybrids performed microwave absorptivity only in Ku-band. Black-Right-Pointing-Pointer The minimum absorbtion of hybrid nanospheres achieved -25 dB. Black-Right-Pointing-Pointer The material is believed to have broad application in notch filter in Ku-band.

  11. Nano-engineering of p-n CuFeO2-ZnO heterojunction photoanode with improved light absorption and charge collection for photoelectrochemical water oxidation

    Science.gov (United States)

    Karmakar, Keshab; Sarkar, Ayan; Mandal, Kalyan; Gopal Khan, Gobinda

    2017-08-01

    The effective utilization of abundant visible solar light for photoelectrochemical water splitting is a green approach for energy harvesting, to reduce the enormous rise of carbon content in the atmosphere. Here, a novel efficient design strategy for p-n type nano-heterojunction photoanodes is demonstrated, with the goal of improving water splitting efficiency by growing low band gap p-CuFeO2 nanolayers on n-ZnO nanorods by an easy and scalable electrochemical route. The photoconversion efficiency of p-n CuFeO2/ZnO photoanodes is found to be ˜450% higher than that of pristine ZnO nanorod electrodes under visible solar light illumination (λ > 420 nm, intensity 10 mW cm-2). The p-n CuFeO2/ZnO nano-engineering not only boosts the visible light absorption but also resolves limitations regarding effective charge carrier separation and transportation due to interfacial band alignment. This photoanode also shows remarkably enhanced stability, where the formation of p-n nano-heterojunction enhances the easy migration of holes to the electrode/electrolyte interface, and of electrons to the counter electrode (Pt) for hydrogen generation. Therefore, this work demonstrates that p-n nano-engineering is a potential strategy to design light-harvesting electrodes for water splitting and clean energy generation.

  12. Determination of Iron (Fe and Calcium (Ca in NIST SRM 1566b (Oyster tissue using Flame Atomic Absorption Spectrometry (F-AAS by Standard Addition Method

    Directory of Open Access Journals (Sweden)

    Fitri Dara

    2017-03-01

    Full Text Available NIST Standard Reference Material (SRM 1566b was employed for the determination of Iron (Fe andCalcium (Ca as nutrients in food matrix using Flame Atomic Absorption Spectrometry (F-AAS. Thecertified value of SRM 1566b for Fe and Ca are 205.8 ± 6.8 mg/kg and 0.0838 ± 0.0020 (% or 838 ±20 mg/kg, respectively. This certified values are based on results obtained by single primary method(Isotope Dilution Inductively Couple Plasma Mass Spectrometry at NIST with confirmation by othermethods at National Metrology Institute of P.R. China. This paper proposed a method fordetermination of Fe and Ca in food matrix as recommended by AOAC official with a littlemodification. The method was commenced from the destruction of all organic matter by dry oxidationbefore analysis by standard addition. Under optimum condition, the results of the determination of Feand Ca in SRM 1566b were agreed well with the certificate value. This method would be useful forroutine analysis in food testing laboratories.

  13. Controlled synthesis of alpha-Fe2O3 nanorods and its size-dependent optical absorption, electrochemical, and magnetic properties.

    Science.gov (United States)

    Zeng, Suyuan; Tang, Kaibin; Li, Tanwei

    2007-08-15

    Uniform alpha-Fe(2)O(3) nanorods with diameter of about 30 nm and length up to 500 nm were synthesized by a template-free hydrothermal method and a following calcination of the intermediate product in the air at 500 degrees C for 2 h. By carefully tuning the concentration of the reactants, a series of alpha-Fe(2)O(3) nanorods with gradient in aspect ratios can be obtained. The effect of the solvent was also evaluated. Based on the experimental facts, the formation mechanism of this one-dimensional structure was proposed. The size-dependent properties of the as-obtained alpha-Fe(2)O(3) nanorods were investigated. The optical absorption properties of the samples showed that the band gaps of the samples decreased in the sequence in which the size increased. The electrochemical performance of the samples showed that the discharge capacity decreased as the size of the sample increased, which may result from the high surface area and small size. The magnetic hysteresis measurements taken at 5 K showed that the coercivities of the samples were related to the aspect ratios of the samples, which may result from the larger shape anisotropy. However, the temperature-dependent field cooling magnetization showed that there was no Morin transition in the as-prepared samples, which may result from the surface effect.

  14. A time-resolved iron-specific X-ray absorption experiment yields no evidence for an Fe2+ --> Fe3+ transition during QA- --> QB electron transfer in the photosynthetic reaction center.

    Science.gov (United States)

    Hermes, Sabine; Bremm, Oliver; Garczarek, Florian; Derrien, Valerie; Liebisch, Peter; Loja, Paola; Sebban, Pierre; Gerwert, Klaus; Haumann, Michael

    2006-01-17

    Previous time-resolved FTIR measurements suggested the involvement of an intermediary component in the electron transfer step Q(A)- --> Q(B) in the photosynthetic reaction center (RC) from Rhodobacter sphaeroides [Remy and Gerwert (2003) Nat. Struct. Biol. 10, 637]. By a kinetic X-ray absorption experiment at the Fe K-edge we investigated whether oxidation occurs at the ferric non-heme iron located between the two quinones. In isolated reaction centers with a high content of functional Q(B), at a time resolution of 30 micros and at room temperature, no evidence for transient oxidation of Fe was obtained. However, small X-ray transients occurred, in a similar micro- to millisecond time range as in the IR experiments, which may point to changes in the Fe ligand environment due to the charges on Q(A)- and Q(B)-. In addition, VIS measurements agree with the IR data and do not exclude an intermediate in the Q(A)- --> Q(B) transition.

  15. K-shell excitation studied for H- and He-like bismuth ions in collisions with low-z target atoms

    Energy Technology Data Exchange (ETDEWEB)

    Stoehlker, T. [Frankfurt Univ. (Germany). Inst. fuer Kernphysik; Ionescu, D.C. [Hahn-Meitner-Institut Berlin GmbH (Germany). Bereich Theoretische Physik; Rymuza, P. [Institute for Nuclear Studies, Swierk (Poland); Bosch, F.; Geissel, H.; Kozhuharov, C.; Ludziejewski, T.; Mokler, P.H.; Scheidenberger, C. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Stachura, Z. [Henryk Niewodniczanski Inst. of Nuclear Physics, Cracow (Poland); Warczak, A. [Krakow Univ. (Poland). Inst. of Physics; Dunford, R.W. [Argonne National Lab., IL (United States)

    1997-09-01

    The formation of excited projectile states via Coulomb excitation is investigated for hydrogen- and helium-like bismuth projectiles (Z=83) in relativistic ion-atom collisions. The excitation process was unambiguously identified by observing the radiative decay of the excited levels to the vacant 1s shell in coincidence with ions that did not undergo charge exchange in the reaction target. In particular, owing to the large fine structure splitting of Bi, the excitation cross-sections to the various L-shell sublevels are determined separately. The results are compared with detailed relativistic calculations, showing that both the relativistic character of the bound-state wave-functions and the magnetic interaction are of considerable importance for the K-shell excitation process in high-Z ions like Bi. The experimental data confirm the result of the complete relativistic calculations, namely that the magnetic part of the Lienard-Wiechert interaction leads to a significant reduction of the K-shell excitation cross-section. (orig.) 27 refs.

  16. Non-dipole effects in the angular distribution of photoelectrons from the K-shell of N{sub 2} molecule

    Energy Technology Data Exchange (ETDEWEB)

    Hosaka, K [Department of Chemistry, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Adachi, J [Department of Chemistry, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Photon Factory, Institute of Materials Structure Science, Tsukuba-shi, Ibaraki 305-0801 (Japan); Golovin, A V [Photon Factory, Institute of Materials Structure Science, Tsukuba-shi, Ibaraki 305-0801 (Japan); Institute of Physics, St Petersburg State University, 198504 St Petersburg (Russian Federation); Takahashi, M [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577 (Japan); Teramoto, T [Department of Chemistry, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Watanabe, N [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577 (Japan); Yagishita, A [Department of Chemistry, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Photon Factory, Institute of Materials Structure Science, Tsukuba-shi, Ibaraki 305-0801 (Japan); Semenov, S K [State University of Aerospace Instrumentation, 190000 St Petersburg (Russian Federation); Cherepkov, N A [State University of Aerospace Instrumentation, 190000 St Petersburg (Russian Federation)

    2006-01-28

    Measurements and calculations of the contribution of the non-dipole terms in the angular distribution of photoelectrons from the K-shell of randomly oriented N{sub 2} molecules are reported. The angular distributions have been measured in the plane containing the photon polarization and the photon momentum vectors of linearly polarized radiation. Calculations have been performed in the relaxed core Hartree-Fock approximation with a fractional charge, and many-electron correlations were taken into account in the random phase approximation. Both theory and experiment show that the non-dipole effects are rather small in the photon energy region from the ionization threshold of the K-shell up to about 70 eV above it. From the theory, it follows that the non-dipole terms for the individual 1{sigma}{sub g} and 1{sigma}{sub u} shells are considerably large; therefore measurements resolving the contributions of the 1{sigma}{sub g} and 1{sigma}{sub u} shells are desirable. (letter to the editor)

  17. Selective detection of Fe and Mn species at mineral surfaces in weathered granite by conversion electron yield X-ray absorption fine structure

    Energy Technology Data Exchange (ETDEWEB)

    Itai, Takaaki [Department of Earth and Planetary Systems Science, Hiroshima University, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan)], E-mail: itai-epss@hiroshima-u.ac.jp; Takahashi, Yoshio [Department of Earth and Planetary Systems Science, Hiroshima University, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Uruga, Tomoya; Tanida, Hajime [Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Iida, Atsuo [Photon Factory, National Laboratory for High Energy Physics, O-ho, Tsukuba, Ibaraki 305 (Japan)

    2008-09-15

    A new method for the speciation of Fe and Mn at mineral surfaces is proposed using X-ray absorption fine structure in conversion electron yield mode (CEY-XAFS). This method generally reflects information on the species at the sub-{mu}m scale from the particle surface due to the limited escape depth of the inelastic Auger electron. The surface sensitivity of this method was assessed by experiments on two samples of granite showing different degrees of weathering. The XANES spectra of the Fe-K and Mn-K edge clearly gave different information for CEY and fluorescence (FL) modes. These XANES spectra of Fe and Mn show a good fit upon application of least-squares fitting using ferrihydrite/MnO{sub 2} and biotite as the end members. The XANES spectra collected by CEY mode provided more selective information on the secondary phases which are probably present at the mineral surfaces. In particular, CEY-XANES spectra of Mn indicated the presence of Mn oxide in unweathered granite despite a very small contribution of Mn oxide being indicated by FL-XANES and selective chemical-extraction analyses. Manganese oxide could not be detected by micro-beam XANES (beam size: 5 x 5 {mu}m{sup 2}) in unweathered granite, suggesting that Mn oxide thinly and ubiquitously coats mineral surface at a sub-{mu}m scale. This information is important, since Mn oxide can be the host for various trace elements. CEY-XAFS can prove to be a powerful tool as a highly sensitive surface speciation method. Combination of CEY and FL-XAFS will help identify minor phases that form at mineral surfaces, but identification of Fe and Mn oxides at mineral surfaces is critical to understand the migration of trace elements in water-rock interaction.

  18. High-Resolution X-ray Spectroscopy of the Interstellar Medium II: Neon and Iron Absorption Edges

    CERN Document Server

    Juett, A M; Chakraborty, D; Gorczyca, T W; Juett, Adrienne M.; Schulz, Norbert S.; Chakrabarty, Deepto; Gorczyca, Thomas W.

    2006-01-01

    We present high-resolution spectroscopy of the neon K-shell and iron L-shell interstellar absorption edges in nine X-ray binaries using the High Energy Transmission Grating Spectrometer (HETGS) onboard the Chandra X-ray Observatory. We found that the iron absorption is well fit by an experimental determination of the cross-section for metallic iron, although with a slight wavelength shift of ~20 mA. The neon edge region is best fit by a model that includes the neutral neon edge and three Gaussian absorption lines. We identify these lines as due to the 1s-2p transitions from Ne II, Ne III, and Ne IX. As we found in our oxygen edge study, the theoretical predictions for neutral and low-ionization lines all require shifts of ~20 mA to match our data. Combined with our earlier oxygen edge study, we find that a best fit O/Ne ratio of 5.4+/-1.6, consistent with standard interstellar abundances. Our best fit Fe/Ne ratio of 0.20+/-0.03 is significantly lower than the interstellar value. We attribute this difference t...

  19. Fe K Emission and Absorption in the XMM-EPIC Spectrum of the Seyfert Galaxy IC 4329a

    CERN Document Server

    Markowitz, A; Reeves, J

    2006-01-01

    We present a detailed analysis of the XMM-Newton long-look of the Seyfert galaxy IC 4329a. The Fe K bandpass is dominated by two resolved peaks at 6.4 keV and 7.0 keV, consistent with neutral or near-neutral Fe K alpha and K beta emission. There is a prominent redward asymmetry in the 6.4 keV line, which could indicate emission from a Compton shoulder. Alternatively, models using dual relativistic disklines are found to describe the emission profile well. A low-inclination, moderately-relativistic dual-diskline model is possible if the contribution from narrow components, due to distant material, is small or absent. A high-inclination, moderately relativistic profile for each peak is possible if there are roughly equal contributions from both the broad and narrow components. Combining the XMM-Newton data with RXTE monitoring data, we explore the time-resolved spectral behavior on time scales from hours to 2 years. We find no strong evidence for variability of the Fe K line flux on any time scale, likely due t...

  20. Integrating giant microwave absorption with magnetic refrigeration in one multifunctional intermetallic compound of LaFe(11.6)Si(1.4)C(0.2)H(1.7).

    Science.gov (United States)

    Song, Ning-Ning; Ke, Ya-Jiao; Yang, Hai-Tao; Zhang, Hu; Zhang, Xiang-Qun; Shen, Bao-Gen; Cheng, Zhao-Hua

    2013-01-01

    Both microwave absorption and magnetocaloric effect (MCE) are two essential performances of magnetic materials. We observe that LaFe(11.6)Si(1.4)C(0.2)H(1.7) intermetallic compound exhibits the advantages of both giant microwave absorption exceeding -42 dB and magnetic entropy change of -20 Jkg(-1)K(-1). The excellent electromagnetic wave absorption results from the large magnetic loss and dielectric loss as well as the efficient complementarity between relative permittivity and permeability. The giant MCE effect in this material provides an ideal technique for cooling the MAMs to avoid temperature increase and infrared radiation during microwave absorption. Our finding suggests that we can integrate the giant microwave absorption with magnetic refrigeration in one multifunctional material. This integration not only advances our understanding of the correlation between microwave absorption and MCE, but also can open a new avenue to exploit microwave devices and electromagnetic stealth.

  1. K-Shell absorpsion spectroscopy of direct drive, shock compressed aluminum targets at the Omega laser facility

    Science.gov (United States)

    Shepherd, Ronnie; Boehley, Thomas; Bradley, David; Ng, Andrew; Iglesias, Carlos; Moon, Steve; Food, Mark; Collins, Gilbert; Rogers, Forrest; Heeter, Robert; Springer, Paul

    2003-10-01

    We have performed experiments to study plasma effects on bound states. The experiments were performed at the Laboratory for Laser Energetics Omega laser facility. The targets consisted of 25 μ m Be, 15 μ m Si, and 10 μ m of Al with an additional 15 μ m step. The targets were shock compressed using direct drive to form dense, strongly coupled plasmas. The plasma conditions were inferred from equation of state models in conjunction with shock breakout time measurements from VISAR. Time resolved absorption spectroscopy was also performed to study the degree of ionization. Data and simulations will be presented.

  2. Reduced Graphene Oxide-Cu0.5Ni0.5Fe2O4-Polyaniline Nanocomposite: Preparation, Characterization and Microwave Absorption Properties

    Science.gov (United States)

    Dat, Tran Quang; Ha, Nguyen Tran; Hung, Do Quoc

    2017-02-01

    Reduced graphene oxide-Cu0.5Ni0.5Fe2O4-polyaniline nanocomposite (RGO-CNF-PANI) was synthesized by a three-step method. The morphology, structure and magnetic properties of composite samples were characterized by scanning electron microscopy, x-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy (RAMAN) and vibrating sample magnetometer. It was found that reduced graphene oxide was exfoliated and decorated homogeneously with ferrite nanoparticles having diameters between 11 nm and 21 nm. The polyaniline was coated by an in situ chemical oxidation polymerization. The measurement of magnetic properties found the remanence (Mr) and coercive field (Hc) were near zero, indicating that the obtained material was superparamagnetic. The microwave measurements found that the nanocomposite exhibited a good absorption property with the optimum matching thickness of 3 mm in the frequency of 8-12 GHz. The value of the maximum RL was -40.7 dB at 9.8 GHz.

  3. High-frequency millimeter wave absorption of indium-substituted ε-Fe{sub 2}O{sub 3} spherical nanoparticles (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Yoshikiyo, Marie; Namai, Asuka [Department of Chemistry, School of Science, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Nakajima, Makoto [Department of Physics, Chiba University 1-33 Yayoicho, Inage Ward, Chiba-shi, Chiba 263-8522 (Japan); Yamaguchi, Keita; Suemoto, Tohru [Institute for Solid State Physics, The University of Tokyo 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Ohkoshi, Shin-ichi, E-mail: ohkoshi@chem.s.u-tokyo.ac.jp [Department of Chemistry, School of Science, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); CREST, JST, K' s Gobancho, 7 Gobancho, Chiyoda-ku, Tokyo 102-0076 (Japan)

    2014-05-07

    In this work, we prepared indium-substituted ε-iron oxide (ε-In{sub x}Fe{sub 2−x}O{sub 3}) spherical nanoparticles by a combination method of reverse-micelle and sol-gel techniques. The powder X-ray diffraction pattern with Rietveld analysis shows that ε-In{sub x}Fe{sub 2−x}O{sub 3} has an orthorhombic crystal structure (space group: Pna2{sub 1}), and the In{sup 3+} ions mainly replace the Fe{sup 3+} ions at B site among the four nonequivalent Fe{sup 3+} sites (A–D sites). The magnetic measurements show that the coercive field (H{sub c}) at 300 K decreases with increasing x, i.e., H{sub c} = 21.9 kOe (x = 0), 12.2 kOe (x = 0.04), 11.6 kOe (x = 0.09), 7.8 kOe (x = 0.13), and 5.9 kOe (x = 0.18). Millimeter wave absorption was measured by terahertz time-domain spectroscopy, and the decrease of resonance frequency (f{sub r}) is observed, i.e., f{sub r} = 182 GHz (x = 0), 160 GHz (x = 0.04), 143 GHz (x = 0.09), 123 GHz (x = 0.13), and 110 GHz (x = 0.18). This decrease in the f{sub r} value is understood by the decrease of magnetic anisotropy, which is caused by the replacement of Fe{sup 3+} (S = 5/2) with nonmagnetic In{sup 3+} (S = 0) at B site contributing to the magnetic anisotropy.

  4. Local structures and electronic band states of α−Fe2O3 polycrystalline particles in the glazes of the HIZEN celadons produced in the Edo period of Japan, by means of X-ray absorption spectra (II)

    OpenAIRE

    Hidaka, M; Ohashi, K.; R. P. Wijesundera; L. S. R. Kumara; Sugihara, S.; Momoshima,N.; Kubuki,S.; Sung,N. E.

    2011-01-01

    HIZEN celadon glazes produced in 1630's to 1790's (Edo period, Japan) have been investigated by means of X-ray absorption spectra (XAS) near a Fe-K edge by using synchrotron radiation and a Mössbauer spectrum. The XAS suggest that the local structure around Fe2O3 fine powders is slightly different between the Izumiyama ceramics of mainly the Quartz-SiO2 and Ohkawachi ceramics of mainly the feldspar of (K,Na)Si3O8 (Sanidine), and that the glazes of the HIZEN celadons include the Fe2O3 fine pow...

  5. Synthesis of core-shell iron nanoparticles from decomposition of Fe-Sn nanocomposite and studies on their microwave absorption properties

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Vatsana; Patra, Manoj K.; Shukla, Anuj; Saini, Lokesh; Songara, Sandhya; Jani, Rajkumar; Vadera, Sampat R.; Kumar, Narendra, E-mail: nkjainjd@yahoo.com [Defence Laboratory (India)

    2012-12-15

    Core-shell iron nanoparticles have been synthesized by pyrolysis of nanocomposite of oxides of iron-tin (Fe-Sn). The core-shell nanoparticles of phase pure iron in carbonaceous shell are formed only at very low concentration of tin (0.0011 mol) in the nanocomposite sample. From different studies viz. X-ray diffraction, high-resolution transmission electron microscopy, atomic force microscopy, and Raman spectroscopy, it has been established that core-shell nanostructures have been formed with Fe as core and amorphous carbon as the shell. The heating of nanocomposite at different temperatures up to 900 Degree-Sign C revealed very interesting dynamics of formation of core-shell structure wherein above 650 Degree-Sign C the iron carbide phase decomposes and carbon atoms move out to form an amorphous shell around iron nanoparticles. This process of formation of core-shell structures is quite different from conventional way wherein synthesis of core material precedes formation of shell in two different steps. The microwave absorption properties of core-shell nanoparticles have been studied by making their composites in nitrile butadiene rubber. Reflection loss simulation studies show high values in the X and Ku bands of microwave region. The frequency of maximum return loss can be tuned through variation of composition and thickness of composite layer.

  6. Soft magnetic property and enhanced microwave absorption of nanoparticles of Co0.5Zn0.5Fe2O4 incorporated in MWCNT

    Science.gov (United States)

    Mallick, A.; Mahapatra, A. S.; Mitra, A.; Chakrabarti, P. K.

    2016-10-01

    Nanoparticles of Co0.5Zn0.5Fe2O4 (CZFO) are prepared by coprecipitation method where CoCl2·H2O, ZnCl2·6H2O and FeCl3 are used as precursor materials. To enhance the microwave absorption, nanoparticles of CZFO are incorporated in the matrix of multiwall carbon nanotubes (MWCNT). X-ray diffractogram (XRD) and its analysis confirmed the formation of the desired crystallographic phase of the sample. The average crystallite size is evaluated by using the Debye-Scherrer formula. Micrographs observed in high resolution transmission electron microscope confirm the successful incorporation of CZFO in the matrix of MWCNT. Results obtained from the high resolution lattice fringe and selected area electron diffraction patterns are in good agreement with the findings extracted from the XRD analysis. Analysis of Raman spectra confirms the presence of CZFO and MWCNT in the nanocomposite sample. Magnetic properties recorded in SQUID magnetometer confirm the presence of mixed state of superparamagnetic and ferrimagnetic nanoparticles. Reflection losses in X (8-12 GHz) and Ku (12-18 GHz) bands of microwave region are significantly high (~-38.2 dB at 16.9 GHz). High magnetization (~36.5 emu/g at 300 K), low coercive field (~30.1 Oe at 300 K) and high reflection loss of CZFO-MWCNT would be suitable for application in microwave devices.

  7. Multiple response optimization for Cu, Fe and Pb determination in naphtha by graphite furnace atomic absorption spectrometry with sample injection as detergent emulsion

    Science.gov (United States)

    Brum, Daniel M.; Lima, Claudio F.; Robaina, Nicolle F.; Fonseca, Teresa Cristina O.; Cassella, Ricardo J.

    2011-05-01

    The present paper reports the optimization for Cu, Fe and Pb determination in naphtha by graphite furnace atomic absorption spectrometry (GF AAS) employing a strategy based on the injection of the samples as detergent emulsions. The method was optimized in relation to the experimental conditions for the emulsion formation and taking into account that the three analytes (Cu, Fe and Pb) should be measured in the same emulsion. The optimization was performed in a multivariate way by employing a three-variable Doehlert design and a multiple response strategy. For this purpose, the individual responses of the three analytes were combined, yielding a global response that was employed as a dependent variable. The three factors related to the optimization process were: the concentration of HNO 3, the concentration of the emulsifier agent (Triton X-100 or Triton X-114) in aqueous solution used to emulsify the sample and the volume of solution. At optimum conditions, it was possible to obtain satisfactory results with an emulsion formed by mixing 4 mL of the samples with 1 mL of a 4.7% w/v Triton X-100 solution prepared in 10% v/v HNO 3 medium. The resulting emulsion was stable for 250 min, at least, and provided enough sensitivity to determine the three analytes in the five samples tested. A recovery test was performed to evaluate the accuracy of the optimized procedure and recovery rates, in the range of 88-105%; 94-118% and 95-120%, were verified for Cu, Fe and Pb, respectively.

  8. Multiple response optimization for Cu, Fe and Pb determination in naphtha by graphite furnace atomic absorption spectrometry with sample injection as detergent emulsion

    Energy Technology Data Exchange (ETDEWEB)

    Brum, Daniel M.; Lima, Claudio F. [Departamento de Quimica, Universidade Federal de Vicosa, A. Peter Henry Rolfs s/n, Vicosa/MG, 36570-000 (Brazil); Robaina, Nicolle F. [Departamento de Quimica Analitica, Universidade Federal Fluminense, Outeiro de S.J. Batista s/n, Centro, Niteroi/RJ, 24020-141 (Brazil); Fonseca, Teresa Cristina O. [Petrobras, Cenpes/PDEDS/QM, Av. Horacio Macedo 950, Ilha do Fundao, Rio de Janeiro/RJ, 21941-915 (Brazil); Cassella, Ricardo J., E-mail: cassella@vm.uff.br [Departamento de Quimica Analitica, Universidade Federal Fluminense, Outeiro de S.J. Batista s/n, Centro, Niteroi/RJ, 24020-141 (Brazil)

    2011-05-15

    The present paper reports the optimization for Cu, Fe and Pb determination in naphtha by graphite furnace atomic absorption spectrometry (GF AAS) employing a strategy based on the injection of the samples as detergent emulsions. The method was optimized in relation to the experimental conditions for the emulsion formation and taking into account that the three analytes (Cu, Fe and Pb) should be measured in the same emulsion. The optimization was performed in a multivariate way by employing a three-variable Doehlert design and a multiple response strategy. For this purpose, the individual responses of the three analytes were combined, yielding a global response that was employed as a dependent variable. The three factors related to the optimization process were: the concentration of HNO{sub 3}, the concentration of the emulsifier agent (Triton X-100 or Triton X-114) in aqueous solution used to emulsify the sample and the volume of solution. At optimum conditions, it was possible to obtain satisfactory results with an emulsion formed by mixing 4 mL of the samples with 1 mL of a 4.7% w/v Triton X-100 solution prepared in 10% v/v HNO{sub 3} medium. The resulting emulsion was stable for 250 min, at least, and provided enough sensitivity to determine the three analytes in the five samples tested. A recovery test was performed to evaluate the accuracy of the optimized procedure and recovery rates, in the range of 88-105%; 94-118% and 95-120%, were verified for Cu, Fe and Pb, respectively.

  9. Spectral analysis of K-shell X-ray emission of magnesium plasma produced by ultrashort high-intensity laser pulse irradiation

    Indian Academy of Sciences (India)

    V Arora; U Chakravarty; Manoranjan P Singh; J A Chakera; P A Naik; P D Gupta

    2014-02-01

    Spectral analysis of K-shell X-ray emission of magnesium plasma, produced by laser pulses of 45 fs duration, focussed up to an intensity of ∼1018 W cm-2, is carried out. The plasma conditions prevalent during the emission of X-ray spectrum were identified by comparing the experimental spectra with the synthetic spectra generated using the spectroscopic code Prism-SPECT. It is observed that He-like resonance line emission occurs from the plasma region having sub-critical density, whereas K- emission arises from the bulk solid heated to a temperature of 10 eV by the impact of hot electrons. K- line from Be-like ions was used to estimate the hot electron temperature. A power law fit to the electron temperature showed a scaling of 0.47 with laser intensity.

  10. K-shell X-ray production cross sections of Ni induced by protons, alpha-particles, and He{sup +}

    Energy Technology Data Exchange (ETDEWEB)

    Bertol, A.P.L. [Programa de Pós-graduação em Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil); Hinrichs, R. [Programa de Pós-graduação em Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil); Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil); Vasconcellos, M.A.Z., E-mail: marcos@if.ufrgs.br [Programa de Pós-graduação em Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil); Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil)

    2015-11-15

    The proton, alpha-particle, and He{sup +} induced X-ray emissions of Ni were measured on mono-elemental thin films in order to obtain the K-shell X-ray production cross section in the energy range of 0.7–2.0 MeV for protons, 4.0–6.5 MeV for alpha-particles, and 3.0–4.0 MeV for He{sup +}. The proton-induced X-ray production cross section for Ni agreed well with the theoretical values, endorsing the quality of the measurements. The X-ray production cross section induced with alpha-particles is in good agreement with ECPSSR theory in the complete range of energies, while for He{sup +} that quantity is systematically below. K{sub β}/K{sub α} ratios were evaluated and compared with experimental and theoretical values.

  11. Ag K-shell ionization by electron impact: New cross-section measurements between 50 and 100 keV and review of previous experimental data

    Science.gov (United States)

    Vanin, V. R.; Manso Guevara, M. V.; Maidana, N. L.; Martins, M. N.; Fernández-Varea, J. M.

    2016-02-01

    We report the measurement of Ag K-shell ionization cross-section by electron impact in the range 50-100 keV and review the experimental data found in the literature. The sample consisted in a thin film of Ag evaporated on a thin C backing. The x-ray spectra generated by electron bombardment in the São Paulo Microtron were observed with a planar HPGe detector. The ratios between characteristic and bremsstrahlung x-ray yields were transformed to ionization cross sections with the help of theoretical atomic-field bremsstrahlung cross sections. The measured cross sections are compared with existing experimental values and calculations based on the semi-relativistic distorted-wave Born approximation. According to our experiment, the ratio of Ag Kβ to Kα x-ray intensities is 0.2018(24).

  12. Single and double K-shell resonant photoionization and Auger decay of 1s → 2p excited states of O+-O4+

    Science.gov (United States)

    Zeng, Jiaolong; Li, Yongjun; Liu, Pengfei; Gao, Cheng; Yuan, Jianmin

    2017-09-01

    In this work, single and double photoionization cross sections in the vicinity of 1s → 2p resonances are investigated theoretically for quantum states belonging to the ground and first excited configurations of O+-O4+. R-matrix method has been employed to obtain the single ionization cross section, whereas the double ionization cross sections are obtained by the branching ratios of the direct double Auger decay to the total Auger decay. By analyzing possible double ionization pathways, we conclude that the double photoionization originates predominately from the direct double Auger decay of the K-shell resonant states. Our theoretical work diagnosed the population fraction of the quantum state prepared in a recent experiment and successfully interpreted the experimental observations on both single and double photoionization cross sections.

  13. Optical signature of sub-gap absorption in the superconducting state of Ba(Fe1-x Cox)2 As 2

    Science.gov (United States)

    Nagel, Urmas; Rõõm, T.; Lobo, R. P. S. M.; Dai, Y. M.; Carbotte, J.; Timusk, T.; Colson, D.

    2011-03-01

    The optical conductivity of Ba(Fe 0.92 Co 0.08)2 As 2 shows a clear signature of the superconducting gap, but a simple s -wave description fails in accounting for the low frequency response. This task is achieved by introducing an extra Drude peak in the superconducting state representing sub-gap absorption, other than thermally broken pairs. This extra peak and the coexisting s -wave response respect the total sum rule indicating a common origin for the carriers. We discuss the possible origins for this absorption as (i) quasiparticles due to pair-breaking from interband impurity scattering in a two band s+/- gap symmetry model, which includes (ii) the possible existence of impurity levels within an isotropic gap model; or (iii) an indication that one of the bands in is highly anisotropic. The results are published in Phys. Rev B vol 82, 100506(R) (2010). Work in Tallinn was supported by the Estonian Ministry of Education and Research (SF0690029s09) and Estonian Science Foundation (ETF7011, ETF8170).

  14. Electromagnetic wave absorption properties of Fe{sub 73}Si{sub 16}B{sub 7}Nb{sub 3}Cu{sub 1}-based composites mixed with fine charcoal powder

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sun-I; Kim, Mi Rae; Sohn, Keun Yong; Park, Won-Wook, E-mail: wwpark@inje.ac.k [Department of Nano-Systems Engineering, Inje University, 607 Obang-dong, Gimhae, Gyeongnam 621-749 (Korea, Republic of)

    2010-05-01

    Fe{sub 73}Si{sub 16}B{sub 7}Nb{sub 3}Cu{sub 1} soft magnetic powder was crystallized to obtain a nano grain structure and mixed with a fine charcoal powder. The mixtures were tape-cast with polymer-based organic binders to form a sheet-type electromagnetic (EM) wave absorption composite. The EM wave absorption properties of the sheets were investigated using a network analyzer. The results showed that addition of charcoal powder improved the EM-absorbing properties of the composite. The power loss of the EM wave was directly related to the imaginary part of the permeability and permittivity, and it was reviewed in detail. Excellent absorption properties were achieved by adding 5 wt % charcoal powder (-500 mesh) to the Fe-based sheets.

  15. X-ray Absorption Spectroscopy and Density Functional Theory Studies of [(H3buea)FeIII-X]n1 (X= S2-, O2-,OH-): Comparison of Bonding and Hydrogen Bonding in Oxo and Sulfido Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Dey, Abhishek; Hocking, Rosalie K.; /Stanford U., Chem. Dept.; Larsen, Peter; Borovik, Andrew S.; /Kansas U.; Hodgson, Keith O.; Hedman, Britt; Solomon, Edward I.; /SLAC,

    2006-09-27

    Iron L-edge, iron K-edge, and sulfur K-edge X-ray absorption spectroscopy was performed on a series of compounds [Fe{sup III}H{sub 3}buea(X)]{sup n-} (X = S{sup 2-}, O{sup 2-}, OH{sup -}). The experimentally determined electronic structures were used to correlate to density functional theory calculations. Calculations supported by the data were then used to compare the metal-ligand bonding and to evaluate the effects of H-bonding in Fe{sup III}-O vs Fe{sup III-}S complexes. It was found that the Fe{sup III-}O bond, while less covalent, is stronger than the FeIII-S bond. This dominantly reflects the larger ionic contribution to the Fe{sup III-}O bond. The H-bonding energy (for three H-bonds) was estimated to be -25 kcal/mol for the oxo as compared to -12 kcal/mol for the sulfide ligand. This difference is attributed to the larger charge density on the oxo ligand resulting from the lower covalency of the Fe-O bond. These results were extended to consider an Fe{sup IV-}O complex with the same ligand environment. It was found that hydrogen bonding to Fe{sup IV-}O is less energetically favorable than that to Fe{sup III-}O, which reflects the highly covalent nature of the Fe{sup IV-}O bond.

  16. Local structure study of (In{sub 0.95−x}Fe{sub x}Cu{sub 0.05}){sub 2}O{sub 3} thin films using x-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Yuan; Xing, Yaya; Ma, Guanxiong; Wang, Shiqi; An, Yukai, E-mail: ykan@tjut.edu.cn; Liu, Jiwen, E-mail: jwliu@tjut.edu.cn [Tianjin Key Laboratory for Photoelectric Materials and Devices, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384 (China); Zhao, Xingliang [Beijing Aerospace Institute for Metrology and Measurement Technology, Beijing 100076 (China)

    2015-07-15

    The (In{sub 0.95−x}Fe{sub x}Cu{sub 0.05}){sub 2}O{sub 3} (x = 0.06, 0.08, 0.15, and 0.20) films prepared by RF-magnetron sputtering were investigated by the combination of x-ray absorption spectroscopy (XAS) at Fe, Cu, and O K-edge. Although the Fe and O K-edge XAS spectra show that the Fe atoms substitute for the In sites of In{sub 2}O{sub 3} lattice for all the films, the Cu K-edge XAS spectra reveal that the codoped Cu atoms are separated to form the Cu metal clusters. After being annealed in air, the Fe atoms are still substitutionally incorporated into the In{sub 2}O{sub 3} lattice, while the Cu atoms form the CuO secondary phases. With the increase of Fe concentration, the bond length R{sub Fe-O} shortens and the Debye–Waller factor σ{sup 2}{sub Fe-O} increases in the first coordination shell of Fe, which are attributed to the relaxation of oxygen environment around the substitutional Fe ions. The forming of Cu relating secondary phases in the films is due to high ionization energy of Cu atoms, leading that the Cu atoms are energetically much harder to be oxidized to substitute for the In sites of In{sub 2}O{sub 3} lattice than Fe atoms. These results provide new experimental guidance in the preparation of the codoped In{sub 2}O{sub 3} based dilute magnetic oxides.

  17. Iron absorption from intrinsically-labeled lentils

    Science.gov (United States)

    Low iron (Fe) absorption from important staple foods may contribute to Fe deficiency in developing countries. To date, there are few studies examining the Fe bioavailability of pulse crops as commonly prepared and consumed by humans. The objectives of this study were to characterize the Fe absorpt...

  18. Direct K-shell ionization probabilities in 30-MeV/u Ne- and 8.3-MeV/u C-induced reactions near zero impact parameter

    NARCIS (Netherlands)

    Kravchuk, VL; Wilschut, HW; van den Berg, AM; Davids, B; Fleurot, F; Hunyadi, M; de Huu, MA; Lohner, H; van der Woude, A

    2003-01-01

    Direct K-shell ionization probabilities were measured in coincidence with elastically scattered particles in 30-MeV/u Ne+Sn, Tb, Pb, Th and 8.3-MeV/u C+Zr, Ag, Sn, Sm, Au, Pb, Th reactions. Experimental data were compared with calculations in the semiclassical approximation. The transitional behavio

  19. Microwave absorption properties of lightweight absorber based on Fe{sub 50}Ni{sub 50}-coated poly(acrylonitrile) microspheres and reduced graphene oxide composites

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Bin [School of Material Science And Engineering, Wuhan University of Technology, Wuhan 430070 (China); Wang, Jun, E-mail: wgdfrp@whut.edu.cn [School of Material Science And Engineering, Wuhan University of Technology, Wuhan 430070 (China); Wang, Junpeng; Huo, Siqi [School of Material Science And Engineering, Wuhan University of Technology, Wuhan 430070 (China); Zhang, Bin [School of Science, Wuhan University of Technology, Wuhan 430070 (China); Tang, Yushan [School of Material Science And Engineering, Wuhan University of Technology, Wuhan 430070 (China)

    2016-09-01

    In this paper, we proposed a facile method to obtain the lightweight composites consisting of surface modified Fe{sub 50}Ni{sub 50}-coated poly(acrylonitrile) microspheres (PANS@SMF), reduced graphene oxide (RGO) and epoxy resin. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry (VSM) and vector network analyzer (VNA). Impedance matching condition and electromagnetic wave attenuation characteristic were used for the reflection loss (RL) performance of the composites. Compared with pure PANS@SMF and RGO composites, the −10 dB absorption bandwidth and the minimum RL of the hybrid composites were enhanced. The bandwidth less than −10 dB was almost 4.5 GHz in the range of 10 GHz to 14.5 GHz, with a matching thickness of 2.5 mm. The density of the hybrid composites was in the range of 0.25–0.34 g/cm{sup 3}. Therefore, the hybrid composite can be considered as a potential lightweight microwave absorber. - Highlights: • PANS@SMF – RGO epoxy composite was fabricated by a facile method. • The absorption bandwidth less than −10 dB can reach up to 4.5 GHz with layer thickness of 2.5 mm. • The density of the composites is in the range of 0.25–0.34 g/cm{sup 3} and can be considered as a lightweight microwave absorber.

  20. Local vibrational dynamics of hematite (α-Fe{sub 2}O{sub 3}) studied by extended x-ray absorption fine structure and molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Sanson, A., E-mail: andrea.sanson@unipd.it [Dipartimento di Fisica e Astronomia - Università di Padova, Padova (Italy); Mathon, O.; Pascarelli, S. [ESRF - European Synchrotron Radiation Facility, Grenoble (France)

    2014-06-14

    The local vibrational dynamics of hematite (α-Fe{sub 2}O{sub 3}) has been investigated by temperature-dependent extended x-ray absorption fine structure spectroscopy and molecular dynamics simulations. The local dynamics of both the short and long nearest-neighbor Fe–O distances has been singled out, i.e., their local thermal expansion and the parallel and perpendicular mean-square relative atomic displacements have been determined, obtaining a partial agreement with molecular dynamics. No evidence of the Morin transition has been observed. More importantly, the strong anisotropy of relative thermal vibrations found for the short Fe–O distance has been related to its negative thermal expansion. The differences between the local dynamics of short and long Fe–O distances are discussed in terms of projection and correlation of atomic motion. As a result, we can conclude that the short Fe–O bond is stiffer to stretching and softer to bending than the long Fe–O bond.

  1. Single impurity Anderson model versus density functional theory for describing Ce L3 x-ray absorption spectra of CeFe2: resolution of a recent controversy.

    Science.gov (United States)

    Kotani, A; Kvashnina, K O; Glatzel, P; Parlebas, J C; Schmerber, G

    2012-01-20

    We resolved a recent controversy on the structure of the Ce L(3) x-ray absorption spectra (XAS) of CeFe(2); i.e., which of the single impurity Anderson model (SIAM) and the first-principles band calculations based on the density-functional theory (DFT) describes more appropriately the Ce 4f states and their contribution to the Ce L(3) XAS? For this purpose, we examined the core-hole effect in Ce L(3) XAS as an application of our new method taking advantage of resonant x-ray emission spectroscopy. Our result clearly shows that the Ce L(3) XAS structure is caused by the mixed valence 4f character revealed by the core-hole potential effect as indicated by SIAM, but denies the possibility that the L(3) XAS structure is caused by the 5d band structure with a very small core-hole effect as predicted by band calculations based on DFT. © 2012 American Physical Society

  2. Ultratrace determination of arsenic in water samples by electrothermal atomic absorption spectrometry after pre-concentration with Mg-Al-Fe ternary layered double hydroxide nano-sorbent.

    Science.gov (United States)

    Abdolmohammad-Zadeh, Hossein; Jouyban, Abolghasem; Amini, Roghayeh

    2013-11-15

    A selective solid phase extraction method, based on nano-structured Mg-Al-Fe(NO3(-)) ternary layered double hydroxide as a sorbent, is developed for the pre-concentration of ultra-trace levels of arsenic (As) prior to determination by electrothermal atomic absorption spectrometry. It is found that both As(III) and As(V) could be quantitatively retained on the sorbent within a wide pH range of 4-12. Accordingly, the presented method is applied to determination of total inorganic As in aqueous solutions. Maximum analytical signal of As is achieved when the pyrolysis and atomization temperatures are close to 900 °C and 2300 °C, respectively. Several variables affecting the extraction efficiency including pH, sample flow rate, amount of nano-sorbent, elution conditions and sample volume are optimized. Under the optimized conditions, the limit of detection (3Sb/m) and the relative standard deviation are 4.6 pg mL(-1) and 3.9%, respectively. The calibration graph is linear in the range of 15.0-650 pg mL(-1) with a correlation coefficient of 0.9979, sorption capacity and pre-concentration factor are 8.68 mg g(-1) and 300, respectively. The developed method is validated by the analysis of a standard reference material (SRM 1643e) and is successfully applied to the determination of ultra-trace amounts of As in different water samples.

  3. Microwave absorption properties of lightweight absorber based on Fe50Ni50-coated poly(acrylonitrile) microspheres and reduced graphene oxide composites

    Science.gov (United States)

    Zhang, Bin; Wang, Jun; Wang, Junpeng; Huo, Siqi; Zhang, Bin; Tang, Yushan

    2016-09-01

    In this paper, we proposed a facile method to obtain the lightweight composites consisting of surface modified Fe50Ni50-coated poly(acrylonitrile) microspheres (PANS@SMF), reduced graphene oxide (RGO) and epoxy resin. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry (VSM) and vector network analyzer (VNA). Impedance matching condition and electromagnetic wave attenuation characteristic were used for the reflection loss (RL) performance of the composites. Compared with pure PANS@SMF and RGO composites, the -10 dB absorption bandwidth and the minimum RL of the hybrid composites were enhanced. The bandwidth less than -10 dB was almost 4.5 GHz in the range of 10 GHz to 14.5 GHz, with a matching thickness of 2.5 mm. The density of the hybrid composites was in the range of 0.25-0.34 g/cm3. Therefore, the hybrid composite can be considered as a potential lightweight microwave absorber.

  4. 微波消解-原子吸收测定柠檬中的 Cu、Zn、Fe 的含量%Microwave Digestion-Detection of Cu,Zn and Fe through Atomic Absorption

    Institute of Scientific and Technical Information of China (English)

    李兴华

    2015-01-01

    This experiment aims to ,using flame atomic absorption spectrometry ,determine through specific ab-sorption procedure the contents of copper , zinc, iron in different parts of lemons when the best atomic absorp-tion spectrometer works.The findings suggest that contents of Cu ,Zn and Fe are respectively 0.709μg/kg,1. 244μg/kg and 14.312μg/kg in lemon juice,0.787μg/kg,2.430μg/kg and 12.971μg/kg in lemon peel,and 3.384μg/kg,5.948μg/kg and 29.773μg/kg in lemon seeds.The experiment provides reference for the safety control of lemon as one of our advantageous fruit resources .%实验对柠檬果实不同部位按照特定的消解程序进行消解,铜、锌、铁三种元素在最佳原子吸收光谱仪工作条件下,采用火焰原子吸收光谱法对其含量进行测定。柠檬果实中,不同部位中铜、锌、铁含量分别为柠檬果汁:0.709μg/kg,1.244μg/kg,14.312μg/kg;柠檬果皮:0.787μg/kg,2.430μg/kg、12.971μg/kg;柠檬籽:3.384μg/kg,5.948μg/kg,29.773μg/kg。实验所建立的柠檬重金属含量测定方法可为四川省优势资源果蔬柠檬的质量安全奠定基础。

  5. Surface atomic structures of Fe2O3 nanoparticles coated with cetyltrimethyl ammonium bromide and sodium dodecyl benzene sulphonate:an extended x-ray absorption fine-structure study

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Fe2O3 nanoparticles coated with sodium dodecyl benzene sulphonate(DBS)or cetyltrimethyl ammonium bromide(CTAB) were prepared by using a microemulsion method in the system water/toluene.The nanoparticles were characterized by means of transmission electron microscopy and average particle sizes of 5.0nm and 6.0nm were found for DBS-modified and CTAB-modified nanoparticles respectively.The local atomic structures of these iron(Ⅲ) oxide nanoparticles were probed by using the extended x-ray absorption fine-structure technique.Fe K absorption spectra were collected at beam line 4W1B of Beijing Synchrotron Radiation Facility.A structureal model was proposed for describing their atomic structures.The Fe-O bond length at the surface of DBS-coated Fe2O3 nanoparticles was found to be similar to that in bulk Fe2O3.but there was about 0.04A expansion for the CTAB-coated Fe2O3 nanoparticles.On the basis of the model proposed in this paper,the thicknesses of the surface layers were estimated to be 0.5nm and 0.7nm.respectively,for the DBS-coated and CTAB-coated Fe2O3 nanoparticles.The anharmonicity of the atomic vibration and the asymmetry of atom-pair distribution were found to be larger at the surface of the nanoparticles than in the bulk material,while the Debye-Waller factors are almost the same for the surface and the core parts of the nanoparticles.It can be concluded that the atomic structure of the nanoparticle surface is ordered.but the atom-pari distribution is asymmetric.

  6. Local structures of mechanically alloyed Fe100—xCux solid soulutions studied by X—ray absorption fine structure

    Institute of Scientific and Technical Information of China (English)

    WenshengYan; YuzhiLi; 等

    2001-01-01

    The local structures of the immiscible Fe100-xCux alloys(x=0,10,20,40,60,80and100)produced by mechanical alloying have been investigated by XAFS.For the Fe100-xCux(x≥40) solid solutions,the local structures around Fe atoms change from bcc structure to fcc one and the Cu atoms maintain the original coordination geometry after milling for 160 hours.On the contrary,the local structures around Cu atoms in both of Fe80Cu20 and Fe90 Cu10 alloys appear a transition from fcc to bcc structure.We found that the Debye-waller factor σof fcc Fe-Cu phase is larger than that of bcc F-Cu phase,and the σ(0.099A°)around Fe atoms is larger than that (0.089A°) of Cu in the Fe100-xCux(x≥40)solid solutions,This suggests that the mechanically alloyed Fe100-xCux supersaturated solid solution is not a homogeneous alloy,and consists of Fe-rich and Cu-rich regions for various compositions.A possible mechanism for bcc-to-fcc and fcc-to-bcc changes in Fe100-xCux solid solutions is discussed in relation to the interdiffusion and transition induced by the ball milling.

  7. Yafet-Kittel-type magnetic ordering in Ni{sub 0.35}Zn{sub 0.65}Fe{sub 2}O{sub 4} ferrite detected by magnetosensitive microwave absorption measurements

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, G., E-mail: memodin@yahoo.co [Departamento de Materiales Metalicos y Ceramicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-360, Coyoacan, DF 04510 Mexico (Mexico); Montiel, H.; Barron, J.F. [Departamento de Tecnociencias, Centro de Ciencias Aplicadas y Desarrollo Tecnologico de la Universidad Nacional Autonoma de Mexico, Mexico, DF 04510 (Mexico); Gutierrez, M.P. [Universidad Anahuac, Mexico Norte, Mexico DF (Mexico); Zamorano, R. [Departamento de Fisica, ESFM-IPN, U. P. Adolfo Lopez Mateos Edificio 9, Av. Instituto Politecnico Nacional S/N, Col. San Pedro Zacatenco, 07738 DF (Mexico)

    2010-02-15

    Magnetosensitive microwave absorption measurements of polycrystalline ferrite Ni{sub 0.35}Zn{sub 0.65}Fe{sub 2}O{sub 4} was carried out at 9.4 GHz (X-band) as a function of temperature. Temperature dependence of the total linewidth (DELTAH{sub pp}) deduced from the resonance spectra showed the passage through the Curie point (T{sub c}approx430 K). Additionally, the plot DELTAH{sub pp} vs. T also indicated the existence of another magnetic phase transition at approx240 K, which can be associated with a Yafet-Kittel-type canting of the magnetic moments. Low-field microwave absorption (LFMA) and the magnetically modulated microwave absorption spectroscopy (MAMMAS) were used to give a further knowledge on this material. For low temperature, these techniques give evidence of a Yafet-Kittel-type canting of the magnetic moments.

  8. The effect of hydrogen absorption on the structural, electronic and magnetic properties of the C15 Friauf-Laves phase compounds CeFe{sub 2}, CeRu{sub 2} and LaRu{sub 2} : an x-ray absorption spectroscopy (XAS) study

    Energy Technology Data Exchange (ETDEWEB)

    Chaboy, J.; Garcia, J. [CSIC-Univ., Zaragoza (Spain). Inst. de Ciencia de Materiales de Aragon ICMA; Marcelli, A. [INFN, Laboratori Nazionali di Frascati, Rome (Italy)

    1995-08-01

    An x-ray absorption spectroscopy (XAS) investigation of the structural changes occurred upon hydriding in the Friauf-Laves phase compounds CeFe{sub 2}, CeRu{sub 2}and LaRu{sub 2} compounds is presented. The analysis of the extended x-ray absorption spectroscopy (EXAFS) spectra at the L-edges of the rare-earth and at the Fe K-edge indicates that the hydrogenation process leads to the suppression of the long-range crystalline order in all the hydride derivates investigated, as well as the different influence of H{sub 2} in both the rare earth and transition metal sublattices. The correlation between the structural and magnetic changes induced by the hydrogen in the lost matrix is discussed in terms of the modification of the electronic properties, i.e., intermediate-valence of Ce, and of the hybridization between the transition metal and rare-earth.

  9. Optical Absorption and Spectral Photoconductivity in α-(Fe1-xCrx)2O3 Solid-Solution Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Chamberlin, Sara E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wang, Yong [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lopata, Kenneth A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kaspar, Tiffany C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Cohn, Alicia [Univ. of Washington, Seattle, WA (United States); Gamelin, Daniel R. [Univ. of Washington, Seattle, WA (United States); Govind, Niranjan [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sushko, Peter V. [Univ. College London (United Kingdom); Chambers, Scott A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2013-09-04

    Hematite, α-Fe2O3, is an attractive narrow gap oxide for consideration as an efficient visible light photocatalyst, with significant potential for band gap engineering via doping. We examine optical absorption in α (Fe1-xCrx)2O3 epitaxial films and explain the observed excitations, and the nature of the band gap dependence on x, through first principles calculations. The calculated and measured optical band gap becomes smaller than that of the bulk α-Fe2O3 and reaches a minimum as the Cr mole fraction increases to 50%. The lowest energy transitions in the mixed-metal alloys involve electron excitation from occupied Cr 3d orbitals to unoccupied Fe 3d orbitals, and they result in a measureable photocurrent. The onset of α-Fe2O3 photoconductivity can be reduced by nearly ~0.5 eV through addition of Cr.

  10. Optical Absorption and Band Gap Reduction in (Fe 1–x Cr x ) 2 O 3 Solid Solutions: A First-Principles Study

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yong; Lopata, Kenneth; Chambers, Scott A.; Govind, Niranjan; Sushko, Peter V.

    2013-12-05

    We provide a detailed theoretical analysis of the character of optical transitions and band gap reduction in (Fe1-xCrx)2O3 solid solutions using extensive periodic model and embedded cluster calculations. Optical absorption bands for x = 0.0, 0.5, and 1.0 are assigned on the basis of timedependent density functional theory (TDDFT) calculations. A band-gap reduction of as much as 0.7 eV with respect to that of pure α-Fe2O3 is found. This result can be attributed to predominantly two effects: (i) the higher valence band edge for x ≈ 0.5, as compared to those in pure α-Fe2O3 and α-Cr2O3, and, (ii) the appearance of Cr α Fe d–d transitions in the solid solutions. Broadening of the valence band due to hybridization of the O 2p states with Fe and Cr 3d states also contributes to band gap reduction.

  11. Relativistic Iron K Emission and absorption in the Seyfert 1.9 galaxy MCG-5-23-16

    CERN Document Server

    Braito, V; Dewangan, G C; George, I; Griffiths, R E; Markowitz, A; Nandra, K; Porquet, D; Ptak, A; Turner, T J; Yaqoob, T; Weaver, K

    2007-01-01

    We present the results of the simultaneous deep XMM and Chandra observations of the bright Seyfert 1.9 galaxy MCG-5-23-16, which is thought to have one of the best known examples of a relativistically broadened iron K-alpha line. The time averaged spectral analysis shows that the iron K-shell complex is best modeled with an unresolved narrow emission component (FWHM < 5000 km/s, EW ~ 60 eV) plus a broad component. This latter component has FWHM ~ 44000 km/s and EW ~ 50 eV. Its profile is well described by an emission line originating from an accretion disk viewed with an inclination angle ~ 40^\\circ and with the emission arising from within a few tens of gravitational radii of the central black hole. The time-resolved spectral analysis of the XMM EPIC-pn spectrum shows that both the narrow and broad components of the Fe K emission line appear to be constant in time within the errors. We detected a narrow sporadic absorption line at 7.7 keV which appears to be variable on a time-scale of 20 ksec. If associa...

  12. Fe(Ⅱ)EDTA吸收-微生物还原体系处理烟气中NO试验%Evaluation of Fe( Ⅱ )EDTA absorption-biological reduction integrated process on removal of NO from flue gas in lab-scale

    Institute of Scientific and Technical Information of China (English)

    刘楠; 吴成志; 刘芸; 蔡灵琳; 李伟

    2011-01-01

    针对目前烟气脱硝技术的缺陷,采用络合吸收结合生物还原的方法处理烟气中NO,在该过程中,NO与Fe(Ⅱ)EDTA络合,进而由微生物将NO还原为N2;其中烟气中的O2能够迅速氧化吸收NO的活性成分Fe(Ⅱ)EDTA为Fe(Ⅲ)EDTA,而它可被微生物再生为Fe(Ⅱ)EDTA,使络合吸收剂得到有效再生,用以循环利用.在稳态运行条件下,该过程的NO去除率可达90%,而直接生物法仅为29%的去除率,单纯的络合吸收法在相同条件下经过5h的运行,吸收液已无法对NO进行有效的吸收.另外,分离出了能够将Fe(Ⅱ)EDTA-NO中的NO还原为N2的脱氮菌Pseudomonas sp.,以及将Fe(Ⅲ)EDTA还原为Fe(Ⅱ)EDTA的铁还原菌Escherichia coli,并研究了它们对Fe(Ⅱ)EDTA-NO或Fe(Ⅲ)EDTA的还原情况,结果表明其还原率均可达到90%以上.%For the current shortcomings of flue gas denitrification technologies, a chemical absorption-biological reduction integrated approach was developed to achieve the NO^ removal from the flue gas. In this integrated process, NO is chelated by Fe( II )EDTA in scrubbing liquid and subsequently reduced to N2 by denitrification bacteria. Fe(III)EDTA formed via oxidation by oxygen in flue gas is simultaneously and biologically reduced back to Fe ( II )EDTA by dedicated iron-reducing bacteria. Thus the absorbent complex can be regenerated effectively for recycling. The possibilities of this process for NO removal were studied. The comparison with NO removal in different ways was investigated in a glass column. The scrubbing and biological regeneration were simultaneously carried out after adapting the microorganisms to the packed tower. And the experiments of Fe( TJ )EDTA-NO and Fe( U ) EDTA reduction by bacterium were also studied in 100 ml. Glass serum vials under anaerobic conditions, which were filled with sterile medium and inoculated with dedicated bacterium strain. During the steady state operation, the integrated approach for the NO

  13. Fe:Mg:LiNbO3晶体电子结构和吸收光谱的第一性原理研究∗%First-principles study of the electronic structures and absorption sp ectrum of Fe:Mg:LiNbO3 crystals

    Institute of Scientific and Technical Information of China (English)

    赵佰强; 张耘; 邱晓燕; 王学维

    2015-01-01

    In this paper, the electronic structures and absorption spectra of LiNbO3 (LN) and Fe:Mg:LiNbO3 crystals are studied by the first-principles under the generalized gradient approximation. The supercell structures of the LN crystal are established with 60 atoms, including four models: pure LN crystal, Fe:LiNbO3 crystal (Fe:LN), Fe:Mg:LiNbO3 crystal with Mg of 2 mol%–3 mol% (Fe:Mg(L):LN), and Fe:Mg:LiNbO3 crystal with Mg of 5.0 mol% (Fe:Mg(E):LN). The electronic structures show that the extrinsic defect levels (within forbidden band) of Fe:LN are contributed by Fe 3d orbital and O 2p orbital, and the band gap of Fe:LN (about 2.85 eV) is narrower than that of LN. For Fe:Mg:LN crystals, the band gap changes to 2.90 eV and 2.81 eV respectively for the Mg ion concentration less than and equal to the threshold (∼5.0 mol%). The two absorption peaks at 2.3 eV and 2.6 eV are attributed to the Fe ions in crystal. Moreover, the intensities of these peaks vary with the concentration of Mg ion. It is revealed that the concentration of Mg ion influences the concentrations and the sites of Fe2+ and Fe3+ ions in crystal. From the absorption spectrum, the values of ratio Fe2+/Fe3+in Fe:Mg(E):LN and Fe:Mg(L):LN can be obtained, and the ratio of first sample is smaller than that of the second one. With the one-center model, one can distinctly deduce that the photoconductivity of Fe:Mg(E):LN is relatively weak compared with that of Fe:Mg(L):LN, but this is inconsistent with many experimental results. One notices the contribution of O 2p orbital to extrinsic defect level in electronic structure. Therefore, it is reasonable to presume that the one-center model is not suitable enough for this condition. Based on the research work, we find that the formations of photoelectrons are related to orbital electron states of iron ions and oxygen atoms at extrinsic defect levels in Fe:LN and Fe:Mg:LN crystals.

  14. Microwave absorption performance of the absorber based on epsilon-Fe{sub 3}N/epoxy and carbonyl iron/epoxy composites

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shu-Yuan, E-mail: ZSY07058079@163.com; Cao, Quan-Xi; Xue, Yi-Rong; Zhou, Yue-Xin

    2015-01-15

    The hexagonal structure epsilon-Fe{sub 3}N powders were fabricated by the molten salt method. It is found that epsilon-Fe{sub 3}N exhibited much better electromagnetic attenuation performance, but its impedance match characteristic was worse than that of carbonyl iron based on the database of electromagnetic parameters. Reflection loss of the monolayer absorber for epsilon-Fe{sub 3}N/epoxy composite obtained by theoretical calculation was in good consistent with that by experiment measurement. The maximum reflection loss of epsilon-Fe{sub 3}N/epoxy composite was −7.6 dB at 7.28 GHz with a thickness of 2 mm, and the −6 dB absorbing bandwidth was 3.7 GHz. Furthermore, microwave absorbing properties of the double-layer absorber with epsilon-Fe{sub 3}N/epoxy as the absorbing layer and carbonyl iron/epoxy as the matching layer were investigated. The double-layer absorber had much better microwave absorbing performance. The maximum reflection loss was −49.8 dB at 12.62 GHz, and the bandwidth bellow −6 dB was as much as 14 GHz with a total thickness of 1.4 mm. - Highlights: • The hexagonal epsilon-Fe{sub 3}N powders were fabricated by the molten salt method. • Epsilon-Fe{sub 3}N had good dissipation property in comparison with that of CI. • CI had better impedance matching characteristic than that of epsilon-Fe{sub 3}N. • The calculated reflectivity of epsilon-Fe{sub 3}N was consistent with the measured value. • The reflectivity of double layer absorber based on epsilon-Fe{sub 3}N and CI was studied.

  15. Characterization of atmospheric aerosols using Synchroton radiation total reflection X-ray fluorescence and Fe K-edge total reflection X-ray fluorescence-X-ray absorption near-edge structure

    Energy Technology Data Exchange (ETDEWEB)

    Fittschen, U.E.A. [Department of Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany)], E-mail: ursula.fittschen@chemie.uni-hamburg.de; Meirer, F. [Atominstitut, Vienna University of Technology, Stadionallee 2, 1020 Wien (Austria)], E-mail: fmeirer@ati.ac.at; Streli, C. [Atominstitut, Vienna University of Technology, Stadionallee 2, 1020 Wien (Austria)], E-mail: streli@ati.ac.at; Wobrauschek, P. [Atominstitut, Vienna University of Technology, Stadionallee 2, 1020 Wien (Austria)], E-mail: wobi@ati.ac.at; Thiele, J. [Department of Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany)], E-mail: Julian.Thiele@gmx.de; Falkenberg, G. [Hamburger Synchrotronstrahlungslabor at Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22603 Hamburg (Germany)], E-mail: falkenbe@mail.desy.de; Pepponi, G. [ITC-irst, Via Sommarive 18, 38050 Povo (Trento) (Italy)], E-mail: pepponi@itc.it

    2008-12-15

    In this study a new procedure using Synchrotron total reflection X-ray fluorescence (SR-TXRF) to characterize elemental amounts in atmospheric aerosols down to particle sizes of 0.015 um is presented. The procedure was thoroughly evaluated regarding bounce off effects and blank values. Additionally the potential of total reflection X-ray fluorescence-X-ray absorption near edge structure (SR-TXRF-XANES) for speciation of FeII/III down to amounts of 34 pg in aerosols which were collected for 1 h is shown. The aerosols were collected in the city of Hamburg with a low pressure Berner impactor on Si carriers covered with silicone over time periods of 60 and 20 min each. The particles were collected in four and ten size fractions of 10.0-8.0 {mu}m, 8.0-2.0 {mu}m, 2.0-0.13 {mu}m 0.13-0.015 {mu}m (aerodynamic particle size) and 15-30 nm, 30-60 nm, 60-130 nm, 130-250 nm, 250-500 nm, 0.5-1 {mu}m, 1-2 {mu}m, 2-4 {mu}m, 4-8 {mu}m, 8-16 {mu}m. Prior to the sampling 'bounce off' effects on Silicone and Vaseline coated Si carriers were studied with total reflection X-ray fluorescence. According to the results silicone coated carriers were chosen for the analysis. Additionally, blank levels originating from the sampling device and the calibration procedure were studied. Blank levels of Fe corresponded to 1-10% of Fe in the aerosol samples. Blank levels stemming from the internal standard were found to be negligible. The results from the Synchroton radiation total reflection X-ray fluorescence analysis of the aerosols showed that 20 min of sampling time gave still enough sample material for elemental determination of most elements. For the determination of the oxidation state of Fe in the aerosols different Fe salts were prepared as a reference from suspensions in isopropanol. The results from the Fe K-edge Synchroton radiation total reflection X-ray fluorescence-X-ray absorption near-edge structure analysis of the aerosol samples showed that mainly Fe(III) was present in

  16. Li deinsertion mechanism and Jahn–Teller distortion in LiFe0.75Mn0.25PO4: an operando x-ray absorption spectroscopy investigation

    Science.gov (United States)

    Iadecola, Antonella; Perea, Alexis; Aldon, Laurent; Aquilanti, Giuliana; Stievano, Lorenzo

    2017-04-01

    The electrochemical lithiation of the mixed metal olivine LiFe0.75Mn0.25PO4 was followed by operando x-ray absorption spectroscopy (XAS) at both Fe and Mn K edges. XAS data were interpreted using an innovating chemometric approach, allowing the detailed reconstruction of the rather complicated reaction mechanism involving two different metal centres. In this way it was possible to precisely describe the Jahn–Teller effect occurring upon oxidation of the manganese centres. The thorough comprehension of the electrochemical mechanism is of high interest for studying the effect of lithium extraction in the olivine structure in the presence of Mn, which is known to partially hamper the complete lithiation of such mixed metal systems.

  17. Existence of orbital order and its fluctuation in superconducting Ba(Fe(1-x)Co(x))2As2 single crystals revealed by x-ray absorption spectroscopy.

    Science.gov (United States)

    Kim, Y K; Jung, W S; Han, G R; Choi, K-Y; Chen, C-C; Devereaux, T P; Chainani, A; Miyawaki, J; Takata, Y; Tanaka, Y; Oura, M; Shin, S; Singh, A P; Lee, H G; Kim, J-Y; Kim, C

    2013-11-22

    We performed temperature dependent x-ray linear dichroism (XLD) experiments on an iron pnictide system, Ba(Fe(1-x)Co(x))2As2 with x=0.00, 0.05, 0.08, and 0.10 to experimentally verify the existence of orbital ordering (OO). Substantial XLD was observed in polarization dependent x-ray absorption spectra of Fe L edges. By exploiting the difference in the temperature dependent behaviors, OO, and structure contributions to XLD could be clearly separated. The observed OO signal indicates different occupation numbers for d(yz) and d(zx) orbitals and supports the existence of ferro-OO. The results are also consistent with the theoretical prediction. Moreover, we find substantial OO signal well above the structural and magnetic transition temperatures, which suggests the existence of strong OO fluctuations up to high temperatures.

  18. High orbital angular momentum quantum numbers in the electronic ground states of Fe$_2^+$ and Co$_2^+$ as determined by x-ray absorption and x-ray magnetic circular dichroism spectroscopy

    CERN Document Server

    Zamudio-Bayer, V; Langenberg, A; Lawicki, A; Terasaki, A; Issendorff, B v; Lau, J T

    2015-01-01

    The $^6\\Delta$ electronic ground state of the Co$_2^+$ diatomic molecular cation has been assigned experimentally by x-ray absorption and x-ray magnetic circular dichroism spectroscopy in a cryogenic ion trap. Three candidates, $^6\\Phi$, $^6\\Gamma$, and $^8\\Gamma$, for the electronic ground state of Fe$_2^+$ have been identified. These states carry sizable ground-state orbital angular momenta that disagree with theoretical predictions from multireference configuration interaction and density functional theory. Our results show that the ground states of neutral and cationic diatomic molecules of $3d$ elements cannot be assumed to be connected by a one-electron process.

  19. Order-disorder in olivine minerals by synchrotron X-ray absorption near-edge structure (Xane) spectroscopy at the Mg, Fe and Ca K edges

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Z.; Marcelli, A.; Cibin, G. [Istituto Nazionale di Fisica Nucleare, Frascati, RM (Italy). Laboratori Nazionali di Frascati; Mottana, A. [Istituto Nazionale di Fisica Nucleare, Frascati, RM (Italy). Laboratori Nazionali di Frascati; Rome Univ. Roma Tre, Rome (Italy). Dipt. di Scienze Geologiche; Paris, E.; Giuli, G [INFM, Camerino Univ., Camerino, MC (Italy). Dipt. di Scienze della Terra

    1999-07-01

    In this paper, are presented new, high-resolution experimental spectra at the Mg and Fe K edges for the two Fe-Mg end members F o and F a, and for three other olivines. Two are the Ca end members of the family, namely monticellite (Mtc: CaMgSiO4) and kirschsteinite (Krs: CaFeSiO4). The main purpose of this work is to investigate the effects of Mg, Fe, and Ca partition in the Pbnm (or {alpha}) olivine structure on the electronic properties, as well as the relationships that exist between chemical substitutions and features occurring in Xanes spectra. One wants to explore the relationships that intervene between LRO, as determined by XRD, and SRO, as determined by Xanes, on the endmembers and on a well-known intermediate member as well, and deduce from it a model for the behavior of the entire olivine solid-solution system.

  20. Controlled synthesis and microwave absorption properties of Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4}/PANI composite via an in-situ polymerization process

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Min [Department of Applied Chemistry, College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 211100 (China); Ji, Guangbin, E-mail: gbji@nuaa.edu.cn [Department of Applied Chemistry, College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 211100 (China); Zhang, Baoshan, E-mail: bszhang@nju.edu.cn [School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Tang, Dongming; Yang, Yi [School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Du, Youwei [Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China)

    2015-03-01

    The binary composites of conducting polyaniline (PANI) and nickle zinc ferrite were synthesized by an in-situ polymerization process, and the electromagnetic absorption properties of the composites were also investigated. The FT-IR spectra present the peaks of PANI (1562, 1481, 1301, 1109, and 799 cm{sup −1}) and the bonds of NiZn ferrite (579 and 390 cm{sup −1}), indicating the existence of both NiZn ferrite particles and PANI in the composites. With the increasing ratio of nickle zinc ferrite, the composites distributes in irregular compared with pure PANI and Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4}. The TG curves of the pure PANI and PANI/Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4} composites with different molar ratios clearly show the increase percentage of the ferrite in the composites. Furthermore, we found that the excellent electromagnetic absorption properties and wide absorption bandwidth can be achieved by adjusting proper molar ratios Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4} to PANI. The maximum reflection loss of Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4}/PANI can reach to −41 dB at 12.8 GHz and the bandwidth exceeding −10 dB can reach to 5 GHz with the absorber thickness of 2.6 mm at the molar ratio of 1:2. This can be attributed to the enhancing magnetic loss and the better impedance matching. Therefore, Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4}/PANI ferrite composites can become a new kind of candidate in the field of the microwave absorbing. - Highlights: • Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4}/PANI possesses the enhanced dielectric properties when compared with pure Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4}. • The absorbing bandwidth of Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4}/PANI is wider than pure Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4}. • The maximum R{sub L} can reach −41 dB at 12.8 GHz and the bandwidth exceeding −10 dB was 5 GHz with the absorber thickness of 2.6 mm.

  1. Preparation and Optical Absorption of Fe Implanted Composite Titania Thin Films%Fe离子注入二氧化钛复合薄膜制备及光吸收性能研究

    Institute of Scientific and Technical Information of China (English)

    周艳军; 何芳; 王玉林; 黄远; 万怡灶

    2011-01-01

    By uainS the sol-Sel method, TiO2 thin films were fabricated onto quartz aubatrates, and then modified by Fe introduced with ion implantation method to promote the ahsorption shift to visible region and enhance optical absorption of TiO2 thin films.XRD,XPS and UV-via were used to characterize the phase structure, the atomic chemical states and optical absorption of these composite TiO2 thin films in different implantation dose.The XRD results indicated that TiO2 films obtained by sol-gel method were anatase.Fe implantation reaulted in the disappearance of anatase and the occurrence of rutile.Since Fe3+ substituted Ti4+ in unit cell, so there was a solid solution of iron in TiO2 matrix.As a result, oxygen vacancies facilitated the transformation of TiO2 from anatase to rutile.XPS results revealed that Fe existed as elemental Fe and Fe3O4 in the films, indicating that the Ti in the lattice of TiO2 was aubatituted by Fe ion.However, No diffraction peaka of Fe and its oxidea were observed, ahowing their non-crystalline structures.The UV-VIS reaults of Fe-implanted TiO2 films with various Fe doae exhibited that the absorption edge shifted to a longer wavelengh due to the exiatence of Fe3O4.Furthermore , this red ahift increased with a higher implanted Fe doae and the optimal Fe implantation dose 1 × 1017 cm -2 was detennined accordingly.%采用溶胶凝胶法在石英基体上制备了纯TiO2薄膜,并通过离子注入方法对TiO2薄膜进行Fe掺杂改性以促进TiO2薄膜光吸收边红移,提高其光吸收性能.利用XRD,XPS及UV-vis对不同注入剂量的Fe掺杂TiO2复合薄膜的晶相结构、原子化学态以及光吸收性能进行了表征.XRD侧试结果表明,溶胶凝胶法制得的TiO2薄膜为锐钛矿相,经Fe离子注入后,复合TiO2薄膜经退火后锐钛矿相消失,金红石相出现,因为Fe3+离子进入晶胞代替Ti4+,在TiO2基体形成铁的固溶体,结果氧空缺形成促进了TiO2从锐钛矿向金红石的转变;XPS测试结果

  2. Electromagnetically induced absorption due to transfer of coherence and coherence population oscillation for the Fg = 3 →Fe = 4 transition in 85Rb atoms

    Science.gov (United States)

    Rehman, Hafeez Ur; Mohsin, Muhammad Qureshi; Noh, Heung-Ryoul; Kim, Jin-Tae

    2016-12-01

    Lineshapes for the electromagnetically induced absorption (EIA) of thermal 85Rb atoms in a degenerate two-level system have been investigated using matching (σ∥σ , π∥π) and orthogonal (σ ⊥ σ , π ⊥ π) polarization configurations of coupling and probe beams. EIA signals, which result from coherence population oscillation and transfer of coherence of the excited state, are obtained in detail theoretically and experimentally. The observed EIA linewidths, which are limited due to the decoherence rate between the magnetic sublevels in the ground state from transit-time relaxation, match well with the calculated ones. Decompositions of the absorption signals analyzed with respect to magnetic sublevels of the ground state show that enhanced or decreased absorption signals for each component of magnetic sublevels in the ground state depend on several factors. These factors include the decay rates and transition strengths, which determine the overall absorption spectral profile.

  3. Microwave absorption measurements in the complex perovskite Pb(Fe{sub 0.5}Ta{sub 0.5})O{sub 3}: Detection of short-range orderly regions

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, G., E-mail: memodin@yahoo.com [Seccion de Estudios de Posgrado e Investigacion, ESFM-IPN, U.P. Adolfo Lopez Mateos Edificio 9, Av. Instituto Politecnico Nacional S/N, San Pedro Zacatenco, Mexico DF 07738 (Mexico); Montiel, H. [Departamento de Tecnociencias, Centro de Ciencias Aplicadas y Desarrollo Tecnologico de la Universidad Nacional Autonoma de Mexico, Apartado Postal 70-360, Mexico DF 04510 (Mexico); Castellanos, M.A. [Facultad de Quimica, Universidad Nacional Autonoma de Mexico, Cd. Universitaria, Mexico DF 04510 (Mexico); Heiras, J. [Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autonoma de Mexico, Km. 107, Carretera Tijuana Ensenada, Ensenada, Baja California 22860 (Mexico); Zamorano, R. [Seccion de Estudios de Posgrado e Investigacion, ESFM-IPN, U.P. Adolfo Lopez Mateos Edificio 9, Av. Instituto Politecnico Nacional S/N, San Pedro Zacatenco, Mexico DF 07738 (Mexico)

    2011-10-17

    Highlights: {yields} LFMA spectra showed straight lines with positive slope and non-hysteretic traces. {yields} The spectral changes for the plot of the slope vs. temperature give evidence of the formation of iron clusters. {yields} These small orderly regions of iron ions generate short-range magnetic correlations, and that they produce changes in dynamics of microwave absorption. - Abstract: An electron paramagnetic resonance (EPR) study of the complex perovskite Pb(Fe{sub 0.5}Ta{sub 0.5})O{sub 3} (PFT) at X-band (8.8-9.8 GHz) is presented. The EPR spectra show a single broad line in the 300-480 K temperature range, attributable to Fe{sup 3+} (S = 5/2) ions. The temperature dependence of the EPR parameters: the peak-to-peak linewidth ({Delta}H{sub pp}), the resonance field (H{sub res}) and the integrated intensity (I{sub EPR}), suggests the existence of short-range magnetic correlations; which are associated with the presence of small orderly regions of iron ions in B-sites of the perovskites-type structure, and that they give origin to formation of iron clusters. Low-field microwave absorption (LFMA) is used to give further knowledge on this material; where this technique also gives evidence of these short-range orderly regions.

  4. Effect of Fe3+ Dopen of Titanium Dioxide Film on Absorption Spectra and Photo Catalysis%Fe3+离子对二氧化钛光电化学催化性能的影响

    Institute of Scientific and Technical Information of China (English)

    肖美群; 沈嘉年; 李谋成; 武朋飞; 刘冬; 张玉娟

    2004-01-01

    应用电化学阳极氧化法制备Ti上多孔状纳米晶TiO2薄膜,以及不同Fe3+离子掺杂量的二氧化钛薄膜.研究了Fe3+离子掺杂对二氧化钛薄膜吸收光谱和光催化活性的影响,发现Fe3+的掺杂使薄膜的吸收带边发生红移,在可见光照射下其光催化活性也有一定的提高.

  5. Preparation of Modified Magnetic Nano-Fe3O4 Chitosan/ Graphene Oxide for the Preconcentration and Determination of Copper (П Ions in Biological and Environmental Water Samples Prior to Flame Atomic Absorption Spectrometry.

    Directory of Open Access Journals (Sweden)

    Mohammd Yari

    2016-06-01

    Full Text Available A simple, highly sensitive, accurate and selective method for determination of trace amounts of Cu2+in water samples .In this paper, chitosan grafted with graphene oxide sheets showed an increased surface area was used to encapsulate nano-Fe3O4 and produce a nano-Fe3O4-encapsulated-chitosan/graphene oxide sorbent based new sorbent was prepared. Flame atomic absorption spectrometer was utilized for determination of Cu2+.Some of the important parameters on the preconcentration and complex formation were selected and optimized. Under the optimized conditions the limit of detection (LOD and limit of quantification (LOQwere 0.30,0.750 and the proposed method has a good reproducibility 0.90% (RSD %.The enrichment factor was 200 and the percentage of recovery was in the range of 95-100% .The method was successfully applied to the recovery of Cu2+in different type of water samples. Graphene oxide and its derivates such as magnetic nano-Fe3O4-encapsulated-chitosan/graphene oxide in this study is full of potential to use as an excellent adsorbent in the extraction method like solid phase extraction(SPE and solid phase micro extraction(SPME. In the present study, we report the application of pre concentration techniques still continues increasingly for trace metal determinations by flame atomic absorption spectrometry (FAAS for quantification of Cu2+ in Formalin-fixed paraffin-embedded (FFPE tissues from Liver loggerhead turtles. This method exhibits the superiority in compared to the other adsorption reagents because of the fact that there is no necessity of any complexing reagent and optimum pH of solution presents in acidic media.

  6. Structural Analysis of the Mn(IV)/Fe(III) Cofactor of Chlamydia Trachomatis Ribonucleotide Reductase By Extended X-Ray Absorption Fine Structure Spectroscopy And Density Functional Theory Calculations

    Energy Technology Data Exchange (ETDEWEB)

    Younker, J.M.; Krest, C.M.; Jiang, W.; Krebs, C.; Bollinger, J.M.Jr.; Green, M.T.

    2009-05-28

    The class Ic ribonucleotide reductase from Chlamydia trachomatis (C{bar A}) uses a stable Mn(lV)/ Fe(lll) cofactor to initiate nucleotide reduction by a free-radical mechanism. Extended X-ray absorption fine structure (EXAFS) spectroscopy and density functional theory (DFT) calculations are used to postulate a structure for this cofactor. Fe and Mn K-edge EXAFS data yield an intermetallic distance of -2.92 {angstrom}. The Mn data also suggest the presence of a short 1.74 {angstrom} Mn-O bond. These metrics are compared to the results of DFT calculations on 12 cofactor models derived from the crystal structure of the inactive Fe2(lll/ III) form of the protein. Models are differentiated by the protonation states of their bridging and terminal OH{sub x} ligands as well as the location of the Mn(lV) ion (site 1 or 2). The models that agree best with experimental observation feature a{mu}-1, 3-carboxylate bridge (E120), terminal solvent (H{sub 2}O/OH) to site 1, one {mu}-O bridge, and one {mu}-OH bridge. The site-placement of the metal ions cannot be discerned from the available data.

  7. The Redshifted Hydrogen Balmer and Metastable He I Absorption Line System in Mini-FeLoBAL Quasar SDSS J112526.12+002901.3: A Parsec Scale Accretion Inflow?

    CERN Document Server

    Shi, Xi-Heng; Wang, Hui-Yuan; Zhang, Shao-Hua; Ji, Tuo; Liu, Wen-Juan; Zhou, Hong-Yan

    2016-01-01

    The accretion of interstellar medium onto the central super massive black holes is widely accepted as the source of the gigantic energy released by the active galactic nuclei. But few pieces of observational evidence have been confirmed directly demonstrating the existence of the inflows. The absorption line system in the spectra of quasar SDSS J112526.12+002901.3 presents an interesting example, in which the rarely detected hydrogen Balmer and metastable He I absorption lines are found redshifted to the quasar's rest frame along with the low-ionization metal absorption lines Mg II, Fe II, etc. The repeated SDSS spectroscopic observations suggest a transverse velocity smaller than the radial velocity. The motion of the absorbing medium is thus dominated by infall. The He I* lines present a powerful probe to the strength of ionizing flux, while the Balmer lines imply a dense environment. With the help of photoionization simulations, we find the absorbing medium is exposed to the radiation with ionization param...

  8. 利用K—shell分析合著网络中的作者传播影响力%Influential Spreaders in Co -author Network Based on K- shell

    Institute of Scientific and Technical Information of China (English)

    张金柱

    2012-01-01

    以情报学领域的12种期刊在2000—2009年间的7389位作者形成的合著网络为例,分别基于度和K—shell,介数和K—shell对作者传播影响力进行比较分析。结果表明,K—shell值较度、介数能更好地表征作者的传播影响力。这种方法可以推广到基于科技文献数据的其他网络中,如识别文献共被引网络、文献耦合网络中最具传播影响力的关键文献。%Based on the data comes from 12 journals between 2000 -2009 which contains 7 389 different authors, this paper computes the degree, betweenness centrality and K - shell and makes a comparative analysis. The results show that K - shell does better in identification of influential spreaders in co - author network. This method can be also used in co - citation network and coupling network for identification of influential spreaders.

  9. Studies on different iron source absorption by in situ ligated intestinal loops of broilers.

    Science.gov (United States)

    Jia, Y F; Jiang, M M; Sun, J; Shi, R B; Liu, D S

    2015-02-01

    The objective of this study was to investigate the iron source absorption in the small intestine of broiler. In situ ligated intestinal loops of 70 birds were poured into one of seven solutions, including inorganic iron (FeSO4, Fe2(SO4)3), organic Fe glycine chelate (Fe-Gly(II), Fe-Gly(III)), the mixtures (FeSO4 with glycine (Fe+Gly(II)), Fe2(SO4)3 with glycine (Fe+Gly(III)), and no Fe source (control). The total volume of 3-mL solution (containing 1 mg of elemental Fe) was injected into intestinal loops, and then 120-min incubation was performed. Compared with inorganic iron groups, in which higher FeSO4 absorption than Fe2(SO4)3 was observed, supplementation with organic Fe glycine chelate significantly increased the Fe concentration in the duodenum and jejunum (P small intestine. Those results indicated that the absorption of organic Fe glycine chelate was more effective than that of inorganic Fe, and the orders of iron absorption in the small intestine were: Fe-Gly(II), Fe-Gly(III) > FeSO4, Fe+Gly(II) > Fe2(SO4)3, Fe+Gly(III). Additionally, the simple mixture of inorganic iron and glycine could not increase Fe absorption, and the duodenum was the main site of Fe absorption in the intestines of broilers and the ileum absorbed iron rarely.

  10. Concentrations of As, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, Pb, and Zn in uruguayan rice determined by atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Mario E. Rivero Huguet

    2011-04-01

    Full Text Available The United Nations General Assembly declared the year 2004 the International Year of Rice and the concept "Rice is life". The largest nutritional problems occurring globally are protein-energy malnutrition, and Ca, Fe, I, Zn, and vitamin A deficiency. In this report, 49 rice samples (Oryza sativa L. were digested by dry ashing in order to determine As, Cd, Cr, and Pb by ETA-AAS; while Ca, Co, Cu, Fe, K, Mg, Mo, Mn, Na, Ni, and Zn were determined by FAAS; and Hg by CV-AAS using microwave-assisted decomposition. The following concentration ranges were obtained for Ca (9.1-15 mg/100 g, Cd (2.30-4.12 µg/kg, Co (41-60 µg/kg, Cu (1.33-180 mg/kg, Fe (4.41-7.15 mg/kg, K (167-217 mg/100 g, Mg (45-121 mg/100 g, Mo (0.52-0.97 mg/kg, Mn (5.45-25.4 mg/kg, Na (0.95-2.50 mg/100g, Ni (0.53-0.72 mg/kg, and Zn (5.86-12.6 mg/kg. Mean recoveries of elements from fortified rice were: 87±12% for As, 95.3±8.9% for Ca, 106.2±7.7% for Cd, 103.3±6.5% for Co, 89.4±8.1% for Cr, 99.3±4.6% for Cu, 103±10% for Fe, 96.3±9.3% for Hg, 95.4±12% for K, 98.3±8.0% for Mg, 93.4±7.8% for Mo, 95.3±9.9% for Mn, 89±12% for Na, 90.3±9.7% for Ni, 91.2±5.5% for Pb and 92.0±9.4% for Zn. The concentrations of the minerals and microelements studied fall within the typical range of rice grown around the world. Potassium was the most abundant mineral, followed by Mg and Ca; among microelements, the concentrations of Cu, Fe, Mo, Mn, Na, and Zn in rice were outstanding. It was also found that the milling process highly affects the K, Mg, Mn, Na, and Zn concentrations, while it has little influence on Ca, Co, Cu, and Fe. On the other hand, there is a loss of Ca, Fe, and Mn during the parboiling process. Recent studies have shown the potential to exploit the genetic variation of rice seeds with regard to the concentration of some minerals (Ca, Fe, Zn, etc. without affecting yield or adding new traits. All rice samples tested showed lower levels of As, Cd, Hg, and Pb in comparison

  11. Self-Propagating Combustion Triggered Synthesis of 3D Lamellar Graphene/BaFe12O19 Composite and Its Electromagnetic Wave Absorption Properties

    Science.gov (United States)

    Zhao, Tingkai; Ji, Xianglin; Jin, Wenbo; Yang, Wenbo; Peng, Xiarong; Duan, Shichang; Dang, Alei; Li, Hao; Li, Tiehu

    2017-01-01

    The synthesis of 3D lamellar graphene/BaFe12O19 composites was performed by oxidizing graphite and sequentially self-propagating combustion triggered process. The 3D lamellar graphene structures were formed due to the synergistic effect of the tremendous heat induced gasification as well as huge volume expansion. The 3D lamellar graphene/BaFe12O19 composites bearing 30 wt % graphene present the reflection loss peak at −27.23 dB as well as the frequency bandwidth at 2.28 GHz (graphene structures could consume the incident waves through multiple reflection and scattering within the layered structures, prolonging the propagation path of electromagnetic waves in the absorbers. PMID:28336889

  12. 在绿柱石晶体中掺入Fe3+的吸收光谱研究%An investigation of absorption spectra of Fe3+ doped in beryl crystal

    Institute of Scientific and Technical Information of China (English)

    王先龙; 杜懋陆; 赵林; 文久富

    2009-01-01

    绿柱石是一种结构较复杂的硅酸盐矿物, 其晶体结构中Al3+可以被Fe2+,Fe3+等取代, 对这种晶体的吸收光谱的研究有助于认识绿柱石晶体的结构, 从而更好的使这种晶体得到应用. 本文引入平均共价因子 , 在立方晶场下考虑电子静电相互作用, 通过完全对角化的方法对掺入Fe3+的绿柱石晶体的吸收光谱进行理论计算, 并对实验结果中吸收峰进行了识别. 结果表明, 实验与理论符合的比较好.

  13. Determination of Fe(II) and Fe(III) in small samples by microbore ion chromatography and photometric, atomic absorption spectrometry and total-reflection X-ray fluorescence detection

    Science.gov (United States)

    Sinner, T.; Hoffmann, P.; Ortner, H. M.

    1993-02-01

    Iron(II) and iron(III) are determined after separation on an ion Chromatographie column by various detection systems. "On-line" detection was achieved by the use of a photometer with a flow cell of 0.8 μl; for "off-line" detection, graphite furnace atomic absorption spectrometry or total-reflection X-ray fluorescence were used. The applicability of the methods is shown for standard solutions and atmospheric samples. As a typical result, 50 μg/l of iron can be determined in a 10 μl sample with a nucrobore ion chromatograph-photometer and atomic absorption system and 40 μg/l of iron in a microbore ion chromatograph-total-reflection X-ray fluorescence combination.

  14. Application of the extraction induced by emulsion breaking for the determination of Cu, Fe and Mn in used lubricating oils by flame atomic absorption spectrometry.

    Science.gov (United States)

    Caldas, Luiz Fernando S; Brum, Daniel M; de Paula, Carlos Eduardo R; Cassella, Ricardo J

    2013-06-15

    A novel approach is proposed for the sample preparation of used lubricating oils to determine Cu, Fe and Mn by FAAS. The method is based on the extraction induced by emulsion breaking, in which the elements of interest are transferred to an aqueous phase before the measurement by FAAS. In the method, each sample of used lubricating oil was diluted with toluene (20% v/v) and the resulting solution was emulsified with a Triton X-114 solution containing HNO3. Further, the water-in-oil emulsion was broken by centrifugation for 30 min at 3500 rpm, originating a system with two well-separated phases: (i) the upper phase, containing the used lubricating oil diluted in toluene and (ii) the lower aqueous phase, containing the analytes that were extracted from oil. The lower phase was collected, diluted with water and the analytes were determined by FAAS. The optimization of the methodology was performed by studying the influence of different parameters that could affect the extraction efficiency such as the nature and concentration of the solvent used for sample dilution, the concentrations of HNO3 and Triton X-114 in the solution employed for emulsification and the operational conditions for extraction (extraction, centrifugation and sampling times). The limits of quantification for Cu, Fe and Mn were 2.9, 77 and 8.2 ng g(-1), respectively. The accuracy of the method was evaluated by comparison with the reference method based on the total digestion of the samples in a closed-vessel microwave oven. There were no statistical differences between the results obtained with the proposed method and the reference one, except for Fe in the cases where its concentration was higher than 80 µg g(-1).

  15. Characterization of selective binding of alkali cations with carboxylate by x-ray absorption spectroscopy of liquid microjets

    Energy Technology Data Exchange (ETDEWEB)

    Saykally, Richard J; Uejio, Janel S.; Schwartz, Craig P.; Duffin, Andrew M.; Drisdell, Walter S.; Cohen, Ronald C.; Saykally, Richard J.

    2008-01-08

    We describe an approach for characterizing selective binding between oppositely charged ionic functional groups under biologically relevant conditions. Relative shifts in K-shell x-ray absorption spectra of aqueous cations and carboxylate anions indicate the corresponding binding strengths via perturbations of carbonyl antibonding orbitals. XAS spectra measured for aqueous formate and acetate solutions containing lithium, sodium, and potassium cations reveal monotonically stronger binding of the lighter metals, supporting recent results from simulations and other experiments. The carbon K-edge spectra of the acetate carbonyl feature centered near 290 eV clearly indicate a preferential interaction of sodium versus potassium, which was less apparent with formate. These results are in accord with the Law of Matching Water Affinities, relating relative hydration strengths of ions to their respective tendencies to form contact ion pairs. Density functional theory calculations of K-shell spectra support the experimental findings.

  16. Detection of the magnetic and electric transitions by electron paramagnetic resonance and low-field microwave absorption in the magnetoelectric Pb(Fe{sub 0.5}Ta{sub 0.5})O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, G., E-mail: memodin@yahoo.co [Departamento de Fisica, ESFM-IPN, U.P. Adolfo Lopez Mateos Edificio 9, Av. Instituto Politecnico Nacional S/N, San Pedro Zacatenco, Mexico DF 07738 (Mexico); Montiel, H. [Departamento de Tecnociencias, Centro de Ciencias Aplicadas y Desarrollo Tecnologico de la Universidad Nacional Autonoma de Mexico, Apartado Postal 70-360, Mexico DF 04510 (Mexico); Pena, J.A.; Castellanos, M.A. [Facultad de Quimica, Universidad Nacional Autonoma de Mexico, Cd. Universitaria, Mexico DF 04510 (Mexico); Zamorano, R. [Departamento de Fisica, ESFM-IPN, U.P. Adolfo Lopez Mateos Edificio 9, Av. Instituto Politecnico Nacional S/N, San Pedro Zacatenco, Mexico DF 07738 (Mexico)

    2010-10-22

    Graphical abstract: Display Omitted Research highlights: {yields} LFMA spectra showed straight lines with positive slope and non-hysteretic traces. {yields} The spectral changes for the plot of the slope vs. temperature give evidence of magnetic and electric orderings, with a very high detection sensibility. - Abstract: An electron paramagnetic resonance (EPR) study of Pb(Fe{sub 0.5}Ta{sub 0.5})O{sub 3} powder samples in perovskite-type structure at X-band (8.8-9.8 GHz), in the 120-300 K temperature range, is presented. For all the temperatures, the EPR spectra show a single broad line attributable to Fe{sup 3+} ions. The onset of the ferro-paraelectric and antiferro-paramagnetic transitions has been determined from the temperature dependence of parameters deduced from the EPR spectra: the peak-to-peak linewidth ({Delta}H{sub pp}), the resonance field (H{sub res}) and the integrated intensity (I{sub EPR}). Low-field microwave absorption (LFMA) is used to give further knowledge on this material; where this technique also gives evidence of the magnetic and electric orders.

  17. Magnetic and microwave absorption properties of BaFe{sub 12-} {sub x} (Mn{sub 0.5}Cu{sub 0.5}Zr) {sub x} {sub /2}O{sub 19} synthesized by sol-gel processing

    Energy Technology Data Exchange (ETDEWEB)

    Ghasemi, Ali [Materials Engineering Department, Malek Ashtar University of Technology, Shahen Shahr (Iran, Islamic Republic of) and Electroceramics Research Center, Malek Ashtar University of Technology, Shahin Shahr (Iran, Islamic Republic of)]. E-mail: ali13912001@yahoo.com; Liu, Xiaoxi [Department of Information Engineering, Shinshu University, Nagano (Japan); Morisako, Akimitsu [Department of Information Engineering, Shinshu University, Nagano (Japan)

    2007-09-15

    BaFe{sub 12-} {sub x} (Mn{sub 0.5}Cu{sub 0.5}Zr) {sub x} {sub /2}O{sub 19} hexaferrites with x=1, 2 and 3 were prepared by sol-gel process. The ferrite powders possess hexagonal shape and are well separated from one another. The powders of these ferrites were mixed with polyvinylchloride (PVC) plasticizer to be converted into a microwave absorbing composite ferrite with a thickness of 1.8 mm. X-ray diffractometer (XRD), scanning electron microscope (SEM), ac susceptometer, vibrating sample magnetometer and vector network analyzer were used to analyze its structure, electromagnetic and microwave absorption properties. The results showed that magnetoplumbite structures for all samples were formed. The sample with higher magnetic susceptibility and coercivity exhibits a larger microwave absorbing ability. Also the present investigation demonstrates that a microwave absorber using BaFe{sub 12-} {sub x} (Mn{sub 0.5}Cu{sub 0.5}Zr) {sub x} {sub /2}O{sub 19} (x=2 and 3)/PVC with a matching thickness of 1.8 mm can be fabricated for applications over 15 GHz, with reflection loss more than -25 dB for specific frequencies, by controlling the molar ratio of the substituted ions.

  18. Microwave absorption properties of planar-anisotropy Ce2Fe17N3-δ powders/Silicone composite in X-band

    Science.gov (United States)

    Gu, Xisheng; Tan, Guoguo; Chen, Shuwen; Man, Qikui; Chang, Chuntao; Wang, Xinmin; Li, Run-Wei; Che, Shenglei; Jiang, Liqiang

    2017-02-01

    The soft-magnetic properties of planar-anisotropy Ce2Fe17N3-δ powders were reported, and reflection loss (RL) of the powders/Silicone composites with various volume concentrations have been studied in 0.1-18 GHz frequency range. It was found that the optimal RL of this composite absorber with a thickness of 1.72 mm is -60.5 dB at 9.97 GHz and the RL is less than -10 dB in the whole X-band (8-12 GHz). The bandwidth with RL exceeding -10 dB and -20 dB are 5.24 GHz and 1.32 GHz, respectively. Furthermore, all the optimal RL value of the composite with the thickness less than 2.13 mm can reach -20 dB in the range of 8-17 GHz, which indicates that the Ce2Fe17N3-δ/Silicone composite absorber will be a promising candidate in higher gigahertz frequency especially in X-band.

  19. The Fe-heme structure of met-indoleamine 2,3-dioxygenase-2 determined by X-ray absorption fine structure

    Energy Technology Data Exchange (ETDEWEB)

    Aitken, Jade B. [School of Chemistry, The University of Sydney, NSW 2006 (Australia); Australian Synchrotron, Clayton, Victoria 3168 (Australia); Institute of Materials Structure Science, KEK, Tsukuba, Ibaraki 305-0801 (Japan); Austin, Christopher J.D. [School of Chemistry, The University of Sydney, NSW 2006 (Australia); Department of Pathology and Bosch Institute, The University of Sydney, Camperdown, NSW 2006 (Australia); Hunt, Nicholas H.; Ball, Helen J. [Department of Pathology and Bosch Institute, The University of Sydney, Camperdown, NSW 2006 (Australia); Lay, Peter A., E-mail: peter.lay@sydney.edu.au [School of Chemistry, The University of Sydney, NSW 2006 (Australia)

    2014-07-18

    Highlights: • IDO2 is a newly discovered tryptophan metabolising enzyme with a role in immunity. • IDO2’s active site contains a heme moiety for tryptophan binding and catabolism. • EXAFS/XANES analysis provides the first data of an IDO2 Fe-heme environment. • IDO2 Fe-heme exists as a low spin bis(His) form at 10 K; mixed spin-state at RT. - Abstract: Multiple-scattering (MS) analysis of EXAFS data on met-indoleamine 2,3-dioxygenase-2 (IDO2) and analysis of XANES have provided the first direct structural information about the axial donor ligands of the iron center for this recently discovered protein. At 10 K, it exists in a low-spin bis(His) form with Fe–N{sub p}(av) = 1.97 Å, the Fe–N{sub Im} bond lengths of 2.11 Å and 2.05 Å, which is in equilibrium with a high-spin form at room temperature. The bond distances in the low-spin form are consistent with other low-spin hemeproteins, as is the XANES spectrum, which is closer to that of the low-spin met-Lb than that of the high-spin met-Mb. The potential physiological role of this spin equilibrium is discussed.

  20. 原子吸收法测定Fe-Co-V合金中锰、镍、铜%Determination of manganess, nickel and copper in Fe-Cr-V alloy by atomic absorption specroscopy(AAS)

    Institute of Scientific and Technical Information of China (English)

    黄中越; 李燕群; 李柏杰

    2000-01-01

    介绍用火焰原子吸收光谱法同时测定Fe-Co-V合金中锰、镍、铜的含量, 研究了实验条件及影响因素, 建立了有效的分析方法. 结果表明, 锰、镍、铜含量在0.5~5.0 mg·L-1范围的回收率为97%~103%, RSD<3.0% (n=10), 具有良好的准确性和重现性.

  1. Hepcidin and 1,25(OH)2D3 effectively restore Ca2+ transport in β-thalassemic mice: reciprocal phenomenon of Fe2+ and Ca2+ absorption.

    Science.gov (United States)

    Kraidith, Kamonshanok; Svasti, Saovaros; Teerapornpuntakit, Jarinthorn; Vadolas, Jim; Chaimana, Rattana; Lapmanee, Sarawut; Suntornsaratoon, Panan; Krishnamra, Nateetip; Fucharoen, Suthat; Charoenphandhu, Narattaphol

    2016-07-01

    Previously, β-thalassemia, an inherited anemic disorder with iron overload caused by loss-of-function mutation of β-globin gene, has been reported to induce osteopenia and impaired whole body calcium metabolism, but the pathogenesis of aberrant calcium homeostasis remains elusive. Herein, we investigated how β-thalassemia impaired intestinal calcium absorption and whether it could be restored by administration of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] or hepcidin, the latter of which was the liver-derived antagonist of intestinal iron absorption. The results showed that, in hemizygous β-globin knockout (BKO) mice, the duodenal calcium transport was lower than that in wild-type littermates, and severity was especially pronounced in female mice. Both active and passive duodenal calcium fluxes in BKO mice were found to be less than those in normal mice. This impaired calcium transport could be restored by 7-day 1,25(OH)2D3 treatment. The 1,25(OH)2D3-induced calcium transport was diminished by inhibitors of calcium transporters, e.g., L-type calcium channel, NCX1, and PMCA1b, as well as vesicular transport inhibitors. Interestingly, the duodenal calcium transport exhibited an inverse correlation with transepithelial iron transport, which was markedly enhanced in thalassemic mice. Thus, 3-day subcutaneous hepcidin injection and acute direct hepcidin exposure in the Ussing chamber were capable of restoring the thalassemia-associated impairment of calcium transport; however, the positive effect of hepcidin on calcium transport was completely blocked by proteasome inhibitors MG132 and bortezomib. In conclusion, both 1,25(OH)2D3 and hepcidin could be used to alleviate the β-thalassemia-associated impairment of calcium absorption. Therefore, our study has shed light on the development of a treatment strategy to rescue calcium dysregulation in β-thalassemia.

  2. Soft magnetic property and enhanced microwave absorption of nanoparticles of Co{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} incorporated in MWCNT

    Energy Technology Data Exchange (ETDEWEB)

    Mallick, A.; Mahapatra, A.S.; Mitra, A.; Chakrabarti, P.K., E-mail: pabitra_c@hotmail.com

    2016-10-15

    Nanoparticles of Co{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} (CZFO) are prepared by coprecipitation method where CoCl{sub 2}·H{sub 2}O, ZnCl{sub 2}·6H{sub 2}O and FeCl{sub 3} are used as precursor materials. To enhance the microwave absorption, nanoparticles of CZFO are incorporated in the matrix of multiwall carbon nanotubes (MWCNT). X-ray diffractogram (XRD) and its analysis confirmed the formation of the desired crystallographic phase of the sample. The average crystallite size is evaluated by using the Debye-Scherrer formula. Micrographs observed in high resolution transmission electron microscope confirm the successful incorporation of CZFO in the matrix of MWCNT. Results obtained from the high resolution lattice fringe and selected area electron diffraction patterns are in good agreement with the findings extracted from the XRD analysis. Analysis of Raman spectra confirms the presence of CZFO and MWCNT in the nanocomposite sample. Magnetic properties recorded in SQUID magnetometer confirm the presence of mixed state of superparamagnetic and ferrimagnetic nanoparticles. Reflection losses in X (8–12 GHz) and K{sub u} (12–18 GHz) bands of microwave region are significantly high (~−38.2 dB at 16.9 GHz). High magnetization (~36.5 emu/g at 300 K), low coercive field (~30.1 Oe at 300 K) and high reflection loss of CZFO-MWCNT would be suitable for application in microwave devices. - Highlights: • Nanoparticles of Co{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} are incorporated in the matrix of MWCNT. • Crystallographic phase and microstructure analysis are carried out. • Magnetic properties are measured and analyzed. • Microwave reflection losses are significantly high due to incorporation in MWCNT.

  3. A cold metal poor cloud traced by a weak MgII absorption at z~0.45. First detection of SiI, CaI and FeI in a QSO absorber

    CERN Document Server

    D'Odorico, Valentina

    2007-01-01

    We present the observations of a weak MgII absorption system detected at z~0.452 in the UVES high resolution spectrum of the QSO HE0001-2340. The weakest of the two MgII components forming the system shows associated absorptions due to SiI, CaI and FeI observed for the first time in a QSO spectrum. We investigate the nature of this absorber by comparing its properties with those of different classes of absorbers (weak MgII, Damped Ly-alpha systems and local interstellar clouds) and reproducing its ionization conditions with photoionization models. The observed absorber belongs to the class of weak MgII systems on the basis of its equivalent width, however the relative strength of commonly observed transitions deviates significantly from those of the above mentioned absorbers. A rough estimate of the probability to cross such a system with a QSO line of sight is P~0.03. The presence of rare neutral transitions suggests that the cloud is shielded by a large amount of neutral Hydrogen. A detailed comparison of t...

  4. Proton induced K-shell ionization cross sections for a wide range of elements (4 ≤ Z ≤ 92 within ECPSSR theory and updated experimental data

    Directory of Open Access Journals (Sweden)

    B. Deghfel

    2014-10-01

    Full Text Available Within the individual treatment of the elements from beryllium (4Be to uranium (92U, the experimental databases are normalized to their corresponding values of the ECPSSR model to deduce the semi-empirical cross sections. These databases rely on the different compilations available in the literature and on the other data extracted from papers published from 1953 till 2010. In the present paper, a fourth order polynomial was used to fit very well the existing normalized database of K-shell ionization cross sections by proton. These procedures generate a new set of parameters for the sake of the quick calculation of the semi-empirical cross sections. A comparison is made between the deduced results and those obtained by using the ECPSSR model where a remarkable discrepancy is observed at low-proton velocity regime especially for the lightest elements.

  5. Inflammation neither increases hepatic hepcidin nor affects intestinal (59)Fe-absorption in two murine models of bowel inflammation, hemizygous TNF(ΔARE/+) and homozygous IL-10(-/-) mice.

    Science.gov (United States)

    Buffler, M; Becker, C; Windisch, W; Schümann, K

    2015-10-01

    Hepcidin-synthesis was reported to be stimulated by inflammation. In contrast, hepcidin synthesis was inhibited by TNFα and serum hepcidin was low. To elucidate these contradictions, we compare data on hepcidin expression, on iron absorption and homoeostasis and markers of inflammation between two murine models of intestinal inflammation and corresponding wild-types as determined by standard methods. In TNF(ΔARE/+) and IL-10(-/-)-mice hepatic hepcidin expression and protein content was significantly lower than in corresponding wild-types. However, (59)Fe whole-body retention showed no difference between knock-outs and corresponding wild-types 7d after gavage, in neither strain. Compared to wild-types, body weight, hepatic non-haem iron content, hemoglobin and hematocrit were significantly decreased in TNF(ΔARE/+) mice, while erythropoiesis increased. These differences were not seen in IL-10(-/-) mice. Duodenal IL-6 and TNFα content increased significantly in TNF(ΔARE/+) mice, while ferritin-H decreased along with hepatic hepcidin expression, ferritin L, and non-haem iron. In IL-10(-/-) mice, these changes were less marked or missing for non-haem iron. Duodenal ferritin-L and ferroportin increased significantly, while HFE decreased. Our results corroborate the conflicting combination of low hepcidin with inflammation and without increased intestinal iron absorption. Speculating on underlying mechanism, decreased hepcidin may result from stimulated erythropoiesis. Unaltered intestinal iron-absorption may compromise between the stimulation by increased erythropoiesis and inhibition by local and systemic inflammation. The findings suggest intense interaction between counterproductive mechanisms and ask for further research.

  6. A simple and fast ultrasound-assisted extraction procedure for Fe and Zn determination in milk-based infant formulas using flame atomic absorption spectrometry (FAAS).

    Science.gov (United States)

    Machado, Ignacio; Bergmann, Gabriela; Pistón, Mariela

    2016-03-01

    A simple and fast ultrasound-assisted procedure for the determination of iron and zinc in infant formulas is presented. The analytical determinations were carried out by flame atomic absorption spectrometry. Multivariate experiments were performed for optimization; in addition, a comparative study was carried out using two ultrasonic devices. A method using an ultrasonic bath was selected because several samples can be prepared simultaneously, and there is less contamination risk. Analytical precision (sr(%)) was 3.3% and 4.1% for iron and zinc, respectively. Trueness was assessed using a reference material and by comparison of the results obtained analyzing commercial samples using a reference method. The results were statistically equivalent to the certified values and in good agreement with those obtained using the reference method. The proposed method can be easily implemented in laboratories for routine analysis with the advantage of being rapid and in agreement with green chemistry.

  7. RE L(3) x-ray absorption study of REO(1-x)F(x)FeAs (RE = La, Pr, Nd, Sm) oxypnictides.

    Science.gov (United States)

    Joseph, B; Iadecola, A; Fratini, M; Bianconi, A; Marcelli, A; Saini, N L

    2009-10-28

    Rare earth L(3)-edge x-ray absorption near-edge structure (XANES) spectroscopy has been used to study REOFeAs (RE = La, Pr, Nd, Sm) oxypnictides. The Nd L(3) XANES due to the [Formula: see text] transition shows a substantial change in both white line (WL) spectral weight and the higher energy multiple scattering resonances with the partial substitution of O by F. A systematic change in the XANES features is seen due to varying lattice parameters with ionic radius of the rare earth. On the other hand, we hardly see any change across the structural phase transition. The results provide timely information on the local atomic correlations showing the importance of the local structural chemistry of the REO spacer layer and interlayer coupling in the competing superconductivity and itinerant striped magnetic phase of the oxypnictides.

  8. Element-specific characterization of transient electronic structure of solvated Fe(II) complexes with time-resolved soft X-ray absorption spectroscopy.

    Science.gov (United States)

    Hong, Kiryong; Cho, Hana; Schoenlein, Robert W; Kim, Tae Kyu; Huse, Nils

    2015-11-17

    Polypyridyl transition-metal complexes are an intriguing class of compounds due to the relatively facile chemical designs and variations in ligand-field strengths that allow for spin-state changes and hence electronic configurations in response to external perturbations such as pressure and light. Light-activated spin-conversion complexes have possible applications in a variety of molecular-based devices, and ultrafast excited-state evolution in these complexes is of fundamental interest for understanding of the origins of spin-state conversion in metal complexes. Knowledge of the interplay of structure and valence charge distributions is important to understand which degrees of freedom drive spin-conversion and which respond in a favorable (or unfavorable) manner. To track the response of the constituent components, various types of time-resolved X-ray probe methods have been utilized for a broad range of chemical and biological systems relevant to catalysis, solar energy conversions, and functional molecular devices. In particular, transient soft X-ray spectroscopy of solvated molecules can offer complementary information on the detailed electronic structures and valence charge distributions of photoinduced intermediate species: First-row transition-metal L-edges consist of 2p-3d transitions, which directly probe the unoccupied valence density of states and feature lifetime broadening in the range of 100 meV, making them sensitive spectral probes of metal-ligand interactions. In this Account, we present some of our recent progress in employing picosecond and femtosecond soft X-ray pulses from synchrotron sources to investigate element specific valence charge distributions and spin-state evolutions in Fe(II) polypyridyl complexes via core-level transitions. Our results on transient L-edge spectroscopy of Fe(II) complexes clearly show that the reduction in σ-donation is compensated by significant attenuation of π-backbonding upon spin-crossover. This underscores

  9. Simulation study of 3–5 keV x-ray conversion efficiency from Ar K-shell vs. Ag L-shell targets on the National Ignition Facility laser

    Energy Technology Data Exchange (ETDEWEB)

    Kemp, G. E., E-mail: kemp10@llnl.gov; Colvin, J. D.; Fournier, K. B.; May, M. J.; Barrios, M. A.; Patel, M. V.; Scott, H. A.; Marinak, M. M. [Lawrence Livermore National Laboratory, Livermore, California 94550-9698 (United States)

    2015-05-15

    Tailored, high-flux, multi-keV x-ray sources are desirable for studying x-ray interactions with matter for various civilian, space and military applications. For this study, we focus on designing an efficient laser-driven non-local thermodynamic equilibrium 3–5 keV x-ray source from photon-energy-matched Ar K-shell and Ag L-shell targets at sub-critical densities (∼n{sub c}/10) to ensure supersonic, volumetric laser heating with minimal losses to kinetic energy, thermal x rays and laser-plasma instabilities. Using HYDRA, a multi-dimensional, arbitrary Lagrangian-Eulerian, radiation-hydrodynamics code, we performed a parameter study by varying initial target density and laser parameters for each material using conditions readily achievable on the National Ignition Facility (NIF) laser. We employ a model, benchmarked against Kr data collected on the NIF, that uses flux-limited Lee-More thermal conductivity and multi-group implicit Monte-Carlo photonics with non-local thermodynamic equilibrium, detailed super-configuration accounting opacities from CRETIN, an atomic-kinetics code. While the highest power laser configurations produced the largest x-ray yields, we report that the peak simulated laser to 3–5 keV x-ray conversion efficiencies of 17.7% and 36.4% for Ar and Ag, respectively, occurred at lower powers between ∼100–150 TW. For identical initial target densities and laser illumination, the Ag L-shell is observed to have ≳10× higher emissivity per ion per deposited laser energy than the Ar K-shell. Although such low-density Ag targets have not yet been demonstrated, simulations of targets fabricated using atomic layer deposition of Ag on silica aerogels (∼20% by atomic fraction) suggest similar performance to atomically pure metal foams and that either fabrication technique may be worth pursuing for an efficient 3–5 keV x-ray source on NIF.

  10. Mathematical model of zinc absorption: effects of dietary calcium, protein and iron on zinc absorption.

    Science.gov (United States)

    Miller, Leland V; Krebs, Nancy F; Hambidge, K Michael

    2013-02-28

    A previously described mathematical model of Zn absorption as a function of total daily dietary Zn and phytate was fitted to data from studies in which dietary Ca, Fe and protein were also measured. An analysis of regression residuals indicated statistically significant positive relationships between the residuals and Ca, Fe and protein, suggesting that the presence of any of these dietary components enhances Zn absorption. Based on the hypotheses that (1) Ca and Fe both promote Zn absorption by binding with phytate and thereby making it unavailable for binding Zn and (2) protein enhances the availability of Zn for transporter binding, the model was modified to incorporate these effects. The new model of Zn absorption as a function of dietary Zn, phytate, Ca, Fe and protein was then fitted to the data. The proportion of variation in absorbed Zn explained by the new model was 0·88, an increase from 0·82 with the original model. A reduced version of the model without Fe produced an equally good fit to the data and an improved value for the model selection criterion, demonstrating that when dietary Ca and protein are controlled for, there is no evidence that dietary Fe influences Zn absorption. Regression residuals and testing with additional data supported the validity of the new model. It was concluded that dietary Ca and protein modestly enhanced Zn absorption and Fe had no statistically discernable effect. Furthermore, the model provides a meaningful foundation for efforts to model nutrient interactions in mineral absorption.

  11. Diagram X-ray emission spectra of a hollow atom: the Kh alpha1,2 and Kh beta1,3 hypersatellites of Fe.

    Science.gov (United States)

    Diamant, R; Huotari, S; Hämäläinen, K; Sharon, R; Kao, C C; Deutsch, M

    2003-11-07

    High-resolution Fe K(h) beta(1,3) and K(h) alpha(1,2) hypersatellite spectra were measured, using monochromatized synchrotron radiation photoexcitation. The lines' energies, splitting, excitation thresholds, and the K(h) alpha(1)/K(h) alpha(2) intensity ratio were derived with high accuracy. Having both spectra, not hitherto available for any atom with high resolution, allows separating out the energy shifts of the outer levels caused by a K shell spectator vacancy. Comparison with ab initio relativistic multiconfigurational Dirac-Fock calculations reveals that while the influence of relativity and QED effects is mostly accounted for, discrepancies remain in the lines' intensity ratio, which sensitively measures the intermediacy of the coupling. Similar discrepancies, of unknown origin, are found in the energy shifts of the outer levels due to the final-state K shell spectator vacancy.

  12. Fractionation of Fe isotopes during Fe(II) oxidation by a marine photoferrotroph is controlled by the formation of organic Fe-complexes and colloidal Fe fractions

    Science.gov (United States)

    Swanner, Elizabeth D.; Wu, Wenfang; Schoenberg, Ronny; Byrne, James; Michel, F. Marc; Pan, Yongxin; Kappler, Andreas

    2015-09-01

    Much interest exists in finding mineralogical, organic, morphological, or isotopic biosignatures for Fe(II)-oxidizing bacteria (FeOB) that are retained in Fe-rich sediments, which could indicate the activity of these organisms in Fe-rich seawater, more common in the Precambrian Era. To date, the effort to establish a clear Fe isotopic signature in Fe minerals produced by Fe(II)-oxidizing metabolisms has been thwarted by the large kinetic fractionation incurred as freshly oxidized aqueous Fe(III) rapidly precipitates as Fe(III) (oxyhydr)oxide minerals at near neutral pH. The Fe(III) (oxyhydr)oxide minerals resulting from abiotic Fe(II) oxidation are isotopically heavy compared to the Fe(II) precursor and are not clearly distinguishable from minerals formed by FeOB isotopically. However, in marine hydrothermal systems and Fe(II)-rich springs the minerals formed are often isotopically lighter than expected considering the fraction of Fe(II) that has been oxidized and experimentally-determined fractionation factors. We measured the Fe isotopic composition of aqueous Fe (Feaq) and the final Fe mineral (Feppt) produced in batch experiment using the marine Fe(II)-oxidizing phototroph Rhodovulum iodosum. The δ56Feaq data are best described by a kinetic fractionation model, while the evolution of δ56Feppt appears to be controlled by a separate fractionation process. We propose that soluble Fe(III), and Fe(II) and Fe(III) extracted from the Feppt may act as intermediates between Fe(II) oxidation and Fe(III) precipitation. Based on 57Fe Mössbauer spectroscopy, extended X-ray absorption fine structure (EXAFS) spectroscopy, and X-ray total scattering, we suggests these Fe phases, collectively Fe(II/III)interm, may consist of organic-ligand bound, sorbed, and/or colloidal Fe(II) and Fe(III) mineral phases that are isotopically lighter than the final Fe(III) mineral product. Similar intermediate phases, formed in response to organic carbon produced by FeOB and inorganic

  13. Determination of Fe and Zn in Infant Formula Milk Power by Flame Atomic Absorption Spectrometry%火焰原子吸收光谱法测定婴幼儿奶粉中铁、锌元素含量

    Institute of Scientific and Technical Information of China (English)

    宋龙波; 赵龙刚; 赵延伟; 陈海华

    2012-01-01

    [目的]鉴于婴幼儿食品的特殊性和重要性,对婴幼儿配方奶粉中的铁、锌元素含量进行测定.[方法]采用干法灰化法处理6种婴幼儿配方奶粉,探究适合奶粉灰化的温度,并且用火焰原子吸收光谱法测定奶粉中铁、锌元素的含量.[结果]试验表明,测定铁、锌元素含量时奶粉的灰化温度为450 ~ 500℃;同一厂家生产的同一品牌不同成长阶段的婴幼儿配方奶粉,铁含量存在一定的差异,锌含量存在显著性差异,同一厂家生产的不同品牌的婴儿(较大婴儿)配方奶粉,铁、锌含量均不存在显著性差异,不同品牌幼儿配方奶粉的铁、锌含量存在显著性差异;6种奶粉的铁、锌元素含量均符合国家标准GB/T5413.21-1997.[结论]科学全面地评价婴幼儿配方奶粉中铁和锌元素的含量,对评价奶粉的品质以及正确引导消费者消费具有积极的现实意义.%[Objective] To determine contents of Fe and Zn in infant formula milk power. [ Method ] Amounts of iron and zinc in 6 brands of infant milk powder were determined by flame atomic absorption spectrometry. The samples were treated by ashing and ashing temperature was determined. [Result] The results showed that ashing temperature of 450 -500 twas suitable for determining iron and zinc in infant formula; for various growth stages of infant formula milk powder with same brand for the same manufacturer, iron content exhibited some difference and zinc content showed significant difference; for various brands of baby formula, iron and zinc content had no significant difference; but for children infant formula, amounts of iron and zinc exhibited significant difference. The values determined in 6 brands of infant milk powder were in agreement with the requirements of national standard GB/T5413.21-1997, [Conclusion] Scientifically and comprehensively evaluating Fe, Zn content in infant formula milk power has positive significance on quality assessment

  14. Effects of Fe-deficient conditions on Fe uptake and utilization in P-efficient soybean.

    Science.gov (United States)

    Qiu, Wei; Dai, Jing; Wang, Nanqi; Guo, Xiaotong; Zhang, Xiaoli; Zuo, Yuanmei

    2017-03-01

    Phosphorus (P)-efficient soybean (Glycine max) plants absorb and utilize P with high efficiency. To investigate the effects of iron (Fe)-deficient conditions on the absorption and utilization of Fe in P-efficient soybean plants, two soybean cultivars with different P efficiency, the 03-3 (P-efficient variety) and Bd-2 (P-inefficient variety), were used in this study. The two soybean cultivars were grown in nutrient solution containing Fe concentrations of 0 (Fe0), 20 (Fe20), 40 (Fe40), or 80 (Fe80) μM for 7 days. The Fe reductase activity of roots was higher in 03-3 plants grown under the Fe0, Fe20, and Fe40 treatments than in Bd-2 plants and the total Fe uptake was greater in 03-3 plants under the Fe40 treatment. GmFRD3a was much more highly expressed in the stem of 03-3 than in that of Bd-2, and significantly more iron was transported to 03-3 plant shoots during Fe0 treatment. Chlorosis in young leaves caused by Fe deficiency under the Fe0 and Fe20 treatments was alleviated by increased Fe concentration in shoots. Increased levels of active Fe in young 03-3 leaves under Fe-deprivation conditions (Fe0) and maintenance of stable Fe concentrations in 03-3 shoots subjected to Fe20, Fe40, and Fe80 treatments suggested that the P-efficient 03-3 cultivar is also Fe-efficient. It is suggested that 03-3 soybean cultivar should be a good resource for application to farm field.

  15. [Effect of altitude on iron absorption].

    Science.gov (United States)

    Pizarro, F; Zavaleta, N; Hertrampf, E; Berlanga, R; Camborda, L; Olivares, M

    1998-03-01

    Iron bioavailability was evaluated in people living in high altitudes. Absorption was estimated from a reference dose of ferrous ascorbate and from a standard diet of wheat flour, using extrinsic tag radioisotope technique of 55Fe and 59Fe. Twenty four volunteers, healthy women, with ages ranging from 28 to 45 years, participated. Of those, eleven lived at 3450 meters above sea level (m.a.s.l.) in Huancayo city-Peru (study group), and 13 lived in Santiago de Chile at 630 m.a.s.l. (control group). Iron absorption from reference dose of ferrous ascorbate was 32.0% and 31.1% in the study and control groups respectively. The geometric mean of iron absorption from the standard diet, corrected to 40% of absorption of reference dose, was 9.0% and 6.9% in the study and control groups respectively (NS). The results suggest that altitude does not produce a high iron absorption in highlander residents.

  16. Time- and space-resolved X-ray absorption spectroscopy of aluminum irradiated by a subpicosecond high-power laser

    Science.gov (United States)

    Tzortzakis, S.; Audebert, P.; Renaudin, P.; Bastiani-Ceccotti, S.; Geindre, J. P.; Chenais-Popovics, C.; Nagels, V.; Gary, S.; Shepherd, R.; Girard, F.; Matsushima, I.; Peyrusse, O.; Gauthier, J.-C.

    2006-05-01

    The ionization and recombination dynamics of transient aluminum plasmas was measured using point projection K-shell absorption spectroscopy. An aluminum plasma was produced with a subpicosecond beam of the 100-TW laser at the LULI facility and probed at different times with a picosecond X-ray backlighter created with a synchronized subpicosecond laser beam. Fourier-Domain-Interferometry (FDI) was used to measure the electron temperature at the peak of the heating laser pulse. Absorption X-ray spectra at early times are characteristic of a dense and rather homogeneous plasma, with limited longitudinal gradients as shown by hydrodynamic simulations. The shift of the Al K-edge was measured in the cold dense plasma located at the edge of the heated plasma. From the 1s 2p absorption spectra, the average ionization was measured as a function of time and was also modeled with a collisional-radiative atomic physics code coupled with hydrodynamic simulations.

  17. Photochemical Formation of Fe(II) in the Aqueous Solutions of Fe(III)- Dicarboxylates

    Science.gov (United States)

    Okada, K.; Arakaki, T.

    2007-12-01

    Although there have been many studies reporting the photochemical formation of Fe(II) in various aqueous-phase such as rain, cloud waters, seawater and aerosols, the detailed formation mechanisms are not well understood. To better understand the mechanisms of Fe(II) formation, we attempted to determine the molar absorptivity and the quantum yield of Fe(II) photoformation for individual Fe(III)-dicarboxylate species. The concentrations of Fe(II) and total dissolved Fe were measured by a Ferrozine-HPLC method. The Visual MINTEQ computer program was used to calculate the equilibrium concentrations of chemical species in the solutions of Fe(III)-dicarboxylate complexes. The molar absorptivity and the product of the quantum yield and the molar absorptivity of Fe(III)- dicarboxylate complex can be analysed by UV-VIS spectrophotometer and photochemical experiments, and these experimental data were combined with the calculated equilibrium Fe(III) speciation to determine individual molar absorptivity and quantum yield of Fe(II) photoformation for a specific Fe(III)-dicarboxylate complex. Preliminary results, using an oxalate whose quantum yield has been previously reported, indicate that this approach gives lower quantum yield values in air saturated solutions than previously reported.

  18. Measurement of the ionization state and electron temperature of plasma during the ablation stage of a wire-array Z pinch using absorption spectroscopy.

    Science.gov (United States)

    Ivanov, V V; Hakel, P; Mancini, R C; Chittenden, J P; Anderson, A; Durmaz, T; Wiewior, P; Papp, D; Altemara, S D; Astanovitskiy, A L; Chalyy, O

    2011-06-03

    Wire-array plasmas were investigated in the nonradiative ablation stage via x-ray absorption spectroscopy. A laser-produced Sm plasma was used to backlight Al wire arrays. The Sm spectrum was simultaneously observed by two spectrometers: one recorded the unattenuated spectrum and the other the transmission spectrum with 1.45-1.55 keV K-shell absorption lines. Analysis of absorption spectra revealed electron temperature in the range of 10-30 eV and the presence of F-, O-, N- and C-like Al ions in the absorbing plasma. A comparison of this electron temperature with the postprocessed absorption spectra of a 2D MHD simulation yields results in general agreement with the data analysis.

  19. Preparation of magnetic recoverable nanosize Cu-Fe2O3/Fe photocatalysts.

    Science.gov (United States)

    Kang, Hsu-Ya; Wang, H Paul

    2013-07-02

    Iron based catalysts generally have the advantage of the easily operated magnetically recovery from application sites. In the present work, paramagnetic iron and copper core-shell nanoparticles having the iron fractions (X(Fe) = Fe/(Cu+Fe)) of 0.33-1.0 were prepared and characterized by in situ synchrotron X-ray absorption and scattering spectroscopy. During the temperature-programmed carbonization (TPC) of Cu(2+)- and Fe(3+)-β-cyclodextrin (CD) complexes, a rapid reduction of Cu(II) occurs at about 453 K together with a growth of the metallic copper (Cu). Iron proceeds in the distinct growth path. At 453-513 K, the Fe(III) → Fe(II) → Fe consecutive reduction is observed. The unreduced Fe(III) (7-13%) is coated on the surfaces of the Fe nanoparticles (as Fe2O3/Fe). Growth of the Fe nanoparticle is inhibited by the surface Fe2O3, while the steady growth in Cu is observed. The Cu has a size range of 14-18 nm in diameter, compared to the small Fe2O3/Fe ones (3-6 nm). Under the UV-visible light irradiation for four hours, methylene blue can be photocatalytically degraded (>90%) by the (Cu-Fe2O3/Fe)@C. The (Cu-Fe2O3/Fe)@C photocatalysts can effectively oxidize dye molecules, providing a promising alternative for dye degradation using solar energy. Recovery of the (Cu-Fe2O3/Fe)@C photocatalysts can be attained by applying external magnetic field to trap the ferromagnetic Cu-Fe2O3/Fe nanoparticles, which suggests an economically attractive process, especially applied in photocatalytic degradation of dye-contaminated wastewater.

  20. The Effect of Plant Proteins Derived from Cereals and Legumes on Heme Iron Absorption

    Directory of Open Access Journals (Sweden)

    Valerie Weinborn

    2015-10-01

    Full Text Available The aim of this study is to determine the effect of proteins from cereals and legumes on heme iron (Fe absorption. The absorption of heme Fe without its native globin was measured. Thirty adult females participated in two experimental studies (15 per study. Study I focused on the effects of cereal proteins (zein, gliadin and glutelin and study II on the effects of legume proteins (soy, pea and lentil on heme Fe absorption. When heme was given alone (as a control, study I and II yielded 6.2% and 11.0% heme absorption (p > 0.05. In study I, heme Fe absorption was 7.2%, 7.5% and 5.9% when zein, gliadin and glutelin were added, respectively. From this, it was concluded that cereal proteins did not affect heme Fe absorption. In study II, heme Fe absorption was 7.3%, 8.1% and 9.1% with the addition of soy, pea and lentil proteins, respectively. Only soy proteins decreased heme Fe absorption (p < 0.05. These results suggest that with the exception of soy proteins, which decreased absorption, proteins derived from cereals and legumes do not affect heme Fe absorption.

  1. Study on absorption performance of new wave-absorbering material nano-compound-α-Fe%新型吸波剂纳米复合α-Fe的吸波性能研究

    Institute of Scientific and Technical Information of China (English)

    廖晓莲; 谭新常; 李正南

    2014-01-01

    探讨了利用天然马脾铁蛋白制备的核壳型纳米复合粉末的成分及组织结构、纳米复合α-Fe含量对电磁参数及电磁损耗的影响,以及以纳米复合α-Fe作为吸波剂的吸收性能。结果表明:利用天然马脾铁蛋白可以制备粒径均一的核壳型纳米复合α-Fe ,一次粒径小于12 nm ;随着复合α-Fe含量的增加,介电常数ε′和ε″基本上单调增加,同时有助于磁导率μ′和μ″的提高;电磁损耗单调增加,损耗中以电损耗为主,磁损耗次之。用纳米复合α-Fe作为吸波剂,可以在厘米波范围内取得较理想的吸收效果,是一种新型的、耐腐蚀性能好的纳米吸波材料。%The composition and structure of the core shell structured nano-composites are analyzed by using natural horse spleen ferritin as materials . The impact of nano-composition α-Fe on the electromagnetic parameters and the electromagnetic loss ,the absorbability of nano-composites-α-Fe as wave-absorber is studied as well .The results show that using natural horse spleen ferritin can prepare the core shell structured nano-composites-α-Fe with equidimensional particle-size and the linear particle-size is less than 12 nm .Theε′andε″raise monotonously and at the same time contribute to the rise of μ′and μ″with the increase of compound-α-Fe . The electromagnetic loss is also raised monotonously with the increase of compound-α-Fe ,with the electric loss as the main loss and the magnetic loss as the second loss .Utilization of the nano-composites-α-Fe as wave-absorber can obtain an ideal absorbent effect within the range of centimeter wave .From all these results ,it is concluded that the nano-composites-α-Fe is a new nano-absorbing material having good performances with good corrosion resistance .

  2. 低分子有机酸对暗棕壤P、Fe、K有效性及林木吸收的影响%Effects of Low Molecular-weight Organic Acids on P,Fe and K Availability of Dark Brown Forest Soils and Absorption of Forest Seedlings

    Institute of Scientific and Technical Information of China (English)

    宋金凤; 崔晓阳; 王政权

    2011-01-01

    模拟东北林区森林凋落物淋洗液中低分子有机酸浓度范围,研究了不同浓度外源草酸、柠檬酸溶液对暗棕壤中P、Fe、K等养分元素有效性、以及落叶松和水曲柳幼苗吸收P、Fe、K的影响.结果表明,合适浓度的草酸和柠檬酸促进暗棕壤中磷的活化,并促进落叶松和水曲柳苗木根系对磷的吸收,但较高浓度时(50.0 mmol/L)水曲柳叶片含磷量却降低;合适浓度草酸和柠檬酸促进暗棕壤中Fe、K等金属元素的活化释放,并促进落叶松和水曲柳幼苗对Fe、K的吸收和运输;在有机酸活化土壤P、Fe、K养分、促进林木吸收的过程中,柠檬酸的作用效果强于同浓度草酸,这主要与柠檬酸较强的络合能力及较大的解离常数有关.%By simulating low molecular-weight organic acids concentrations in forest litter leachates,a series of batch experiments were conducted to study the effects of oxalic and citric solutions on P,Fe, K availability in dark brown forest soils and nutrient absorption of Larix olgensis and Fraxinus mandshurica seedlings. The results showed that, oxalic and citric solutions of appropriate concentrations stimulated soil P release from dark brown forest soils supporting Fraxinus mandshurica and Larix olgensis seedings, and were helpful to P absorption by two kinds of seedings. However, oxalic and citric solutions of higher concentrations (50.0 mmol/L) inhibited P transportation to Fraxinus mandshurica leaves. Oxalic and citric solutions of appropriate concentrations also stimulated Fe and K release from dark brown forest soils, and were helpful in the course of Fe and K absorptions and transportation by Fraxinus mandshurica and Larix olgensis seeding s. In the processes of nutrient mobilization and absorption, citric had higher release capacity than oxalic, and it was related to higher dissociation constants and organic ligand-metal stabilities of citric.

  3. Pressure-induced magnetic switching and linkage isomerism in K0.4Fe4[Cr(CN)6]2.8 •16H2O: x-ray absorption and magnetic circular dichroism studies

    NARCIS (Netherlands)

    Coronado, E.; Giménez-López, M.C.; Korzeniak, T.; Levchenko, G.; Romero, F.M.; Segura, A.; García-Baonza, V.; Cezar, J.C.; de Groot, F.M.F.; Milner, A.; Paz-Pasternak, M.

    2008-01-01

    The effect of applied pressure on the magnetic properties of the Prussian blue analogue K0.4Fe4[Cr(CN)6]2.8 ·16H2O (1) has been analyzed by dc and ac magnetic susceptibility measurements. Under ambient conditions, 1 orders ferromagnetically at a critical temperature (TC) of 18.5 K. Under application

  4. Interstellar dust grain composition from high-resolution X-ray absorption edge structure

    Science.gov (United States)

    Corrales, Lia

    2016-06-01

    X-ray light is sufficient to excite electrons from n=1 (K-shell) and n=2 (L-shell) energy levels of neutral interstellar metals, causing a sharp increase in the absorption cross-section. Near the ionization energy, the shape of the photoelectric absorption edge depends strongly on whether the atom is isolated or bound in molecules or minerals (dust). With high resolution X-ray spectroscopy, we can directly measure the state of metals and the mineral composition of dust in the interstellar medium. In addition, the scattering contribution to the X-ray extinction cross-section can be used to gauge grain size, shape, and filling factor. In order to fully take advantage of major advances in high resolution X-ray spectroscopy, lab measurements of X-ray absorption fine structure (XAFS) from suspected interstellar minerals are required. Optical constants derived from the absorption measurements can be used with Mie scattering or anomalous diffraction theory in order to model the full extinction cross-sections from the interstellar medium. Much like quasar spectra are used to probe other intergalactic gas, absorption spectroscopy of Galactic X-ray binaries and bright stars will yield key insights to the mineralogy and evolution of dust grains in the Milky Way.

  5. Structural analysis of sulfur in natural rubber using X-ray absorption near-edge spectroscopy.

    Science.gov (United States)

    Pattanasiriwisawa, Wanwisa; Siritapetawee, Jaruwan; Patarapaiboolchai, Orasa; Klysubun, Wantana

    2008-09-01

    X-ray absorption near-edge spectroscopy (XANES) has been applied to natural rubber in order to study the local environment of sulfur atoms in sulfur crosslinking structures introduced in the vulcanization process. Different types of chemical accelerators in conventional, semi-efficient and efficient vulcanization systems were investigated. The experimental results show the good sensitivity and reproducibility of XANES to characterize the local geometry and electronic environment of the sulfur K-shell under various conditions of vulcanization and non-vulcanization of natural rubber. Several applications of XANES in this study demonstrate an alternative way of identifying sulfur crosslinks in treated natural rubber based on differences in their spectra and oxidation states.

  6. The Effect of Plant Proteins Derived from Cereals and Legumes on Heme Iron Absorption.

    Science.gov (United States)

    Weinborn, Valerie; Pizarro, Fernando; Olivares, Manuel; Brito, Alex; Arredondo, Miguel; Flores, Sebastián; Valenzuela, Carolina

    2015-10-30

    The aim of this study is to determine the effect of proteins from cereals and legumes on heme iron (Fe) absorption. The absorption of heme Fe without its native globin was measured. Thirty adult females participated in two experimental studies (15 per study). Study I focused on the effects of cereal proteins (zein, gliadin and glutelin) and study II on the effects of legume proteins (soy, pea and lentil) on heme Fe absorption. When heme was given alone (as a control), study I and II yielded 6.2% and 11.0% heme absorption (p > 0.05). In study I, heme Fe absorption was 7.2%, 7.5% and 5.9% when zein, gliadin and glutelin were added, respectively. From this, it was concluded that cereal proteins did not affect heme Fe absorption. In study II, heme Fe absorption was 7.3%, 8.1% and 9.1% with the addition of soy, pea and lentil proteins, respectively. Only soy proteins decreased heme Fe absorption (p legumes do not affect heme Fe absorption.

  7. Solid-phase extraction of Fe(III), Pb(II) and Cr(III) in environmental samples on amberlite XAD-7 and their determinations by flame atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Divrikli, Umit [Pamukkale University, Faculty of Arts and Science, Department of Chemistry, Denizli 20020 (Turkey)], E-mail: udivrikli@pamukkale.edu.tr; Akdogan, Abdullah [Pamukkale University, Faculty of Arts and Science, Department of Chemistry, Denizli 20020 (Turkey); Soylak, Mustafa [Erciyes University, Faculty of Arts and Science, Department of Chemistry, Kayseri 38039 (Turkey); Elci, Latif [Pamukkale University, Faculty of Arts and Science, Department of Chemistry, Denizli 20020 (Turkey)

    2007-10-22

    This paper describes a simple and accurate procedure for preconcentration of trace amounts of Fe(III), Pb(II) and Cr(III) ions. The preconcentration procedure is based on retention of p-xylenol blue chelates on Amberlite XAD-7. The analytes retained were eluted from Amberlite XAD-7 by using 1 mol L{sup -1} HCl. The influences of the analytical parameters including amounts of reagents, pH and type of eluent were also investigated. The detection limits of Fe, Pb and Cr were found to be 3.07, 18.6 and 3.27 {mu}g L{sup -1}, respectively. The accuracy of the procedure was checked by the analysis of an electrolytic copper wire sample. The relative error was less than 5%. The presented method was applied to the determination of Fe(III), Pb(II) and Cr(III) in water samples from Denizli, Turkey with good results such as recoveries more than 95%, relative standard deviations below 10%.

  8. Solid-phase extraction of Fe(III), Pb(II) and Cr(III) in environmental samples on amberlite XAD-7 and their determinations by flame atomic absorption spectrometry.

    Science.gov (United States)

    Divrikli, Umit; Akdogan, Abdullah; Soylak, Mustafa; Elci, Latif

    2007-10-22

    This paper describes a simple and accurate procedure for preconcentration of trace amounts of Fe(III), Pb(II) and Cr(III) ions. The preconcentration procedure is based on retention of p-xylenol blue chelates on Amberlite XAD-7. The analytes retained were eluted from Amberlite XAD-7 by using 1 mol L(-1) HCl. The influences of the analytical parameters including amounts of reagents, pH and type of eluent were also investigated. The detection limits of Fe, Pb and Cr were found to be 3.07, 18.6 and 3.27 microg L(-1), respectively. The accuracy of the procedure was checked by the analysis of an electrolytic copper wire sample. The relative error was less than 5%. The presented method was applied to the determination of Fe(III), Pb(II) and Cr(III) in water samples from Denizli, Turkey with good results such as recoveries more than 95%, relative standard deviations below 10%.

  9. Synthesis Method and Absorption Application of Nanocrystalline Alloy Flakes

    Institute of Scientific and Technical Information of China (English)

    Pei-Heng Zhou; Long-Jiang Deng

    2007-01-01

    The soft magnetic FeSiB nanocrystalline/amorphous flakes were fabricated by ball milling from the elemental powders and annealing the amorphous precursor, respectively. The microstructure, magnetic and microwave properties were evaluated by different synthesis methods. By computation, ballmilled Fe78Si13B9 flakes demonstrated potential application in absorption.

  10. Acute Copper and Ascorbic Acid Supplementation Inhibits Non-heme Iron Absorption in Humans.

    Science.gov (United States)

    Olivares, Manuel; Figueroa, Constanza; Pizarro, Fernando

    2016-08-01

    The objective of the study is to determine the effect of copper (Cu) plus the reducing agent ascorbic acid (AA) on the absorption of non-heme iron (Fe). Experimental study with block design in which each subject was his own control. After signing an informed consent, 14 adult women using an effective method of contraception and negative pregnancy test received 0.5 mg Fe, as ferrous sulfate, alone or with Cu, as copper sulfate, plus ascorbic acid (AA/Cu 2/1 molar ratio) at 4/1; 6/1 and 8/1 Cu/Fe molar ratios as an aqueous solution on days 1, 2, 14, and 15 of the study. Fe absorption was assessed by erythrocyte incorporation of iron radioisotopes (55)Fe and (59)Fe. Geometric mean (range ± SD) absorption of Fe at 4/1 and 6/1 Cu/Fe molar ratios (and AA/Cu 2/1 molar ratio) and Fe alone was 57.4 % (35.7-92.1 %), 64.2 % (45.8-89.9 %), and 38.8 % (20.4-73.8 %), respectively (ANOVA for repeated measures p absorption; however, Fe absorption at Cu/Fe 8/1 molar ratio was 47.3 % (27.7-80.8) (p = NS compared with Fe alone). It was expected that Fe absorption would have been equal or greater than at 4/1 and 6/1 molar ratios. Copper in the presence of ascorbic acid inhibits non-heme Fe absorption at Cu/Fe 8/1 molar ratio.

  11. Investigation of microwave absorption property of the core–shell structured Li{sub 0.4}Mg{sub 0.6}Fe{sub 2}O{sub 4}/TiO{sub 2} nanocomposite in X-band region

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, Pallab; Hatui, Goutam; Mandal, Avinandan [Materials Science Centre, Indian Institute of Technology, Kharagpur 721302, West Bengal (India); Das, Chapal Kumar, E-mail: chapal12@yahoo.co.in [Materials Science Centre, Indian Institute of Technology, Kharagpur 721302, West Bengal (India); Kumar, Rudresh; Shami, T.C. [Defence Materials and Stores Research and Development Establishment, Kanpur 208013, Uttar Pradesh (India)

    2014-03-25

    Highlights: • Li{sub 0.4}Mg{sub 0.6}Fe{sub 2}O{sub 4} is a new spinel ferrite. • The synthetic procedure is simple and cost effective. • The composite shows core–shell morphology. • The composite shows good magnetic, optical and microwave absorbing properties. • The material shows the maximum reflection loss of −41.6 dB. The thickness of the absorber is only 2.5 mm. -- Abstract: Initially, we have synthesized a magnetic spinel-type ferrite, Li{sub 0.4}Mg{sub 0.6}Fe{sub 2}O{sub 4} (LMF) by a simple chemical coprecipitation method. The LMF particles of different sizes were formed, and the most populated size range is 45–75 nm. Further, the LMF was coated by titanium di-oxide (TiO{sub 2}) via the sol–gel process, and examined the microwave absorption property of TiO{sub 2} coated LMF (Ti@LMF) in the X-band region. The formation of both LMF and Ti@LMF was supported by analysing the materials through different analytical techniques such as X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), and fourier transform infrared (FTIR) spectroscopy. The core–shell morphology of Ti@LMF was confirmed by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analysis. The result indicates that the average shell thickness is around 40–50 nm. The optical and magnetic property was studied by UV–VIS spectroscopy and SQUID analysis. Ti@LMF showed excellent microwave absorption property under the thermoplastic polyurethane (TPU) matrix. The maximum reflection loss (−41.6 dB) was measured with the help of Vector Network Analyzer, and the mechanism of absorption was explained by considering the relative complex permittivity and permeability of the prepared materials. The matching of both the dielectric loss (initiated by TiO{sub 2}) and magnetic loss (initiated by LMF) is the main reason for remarkable microwave absorption property of Ti@LMF.

  12. GASTROINTESTINAL TRACT AND IRON ABSORPTION: A REVIEW

    Directory of Open Access Journals (Sweden)

    Gladys O. LATUNDE-DADA

    2009-07-01

    Full Text Available

    Iron is an important element in many metabolic processes. The bioavailability of iron is a function of solubilization and reduction of Fe3+ in the stomach, hydrolysis, neutralization, ligand complexes and transport through the mucus layer of the intestine. The bioavailibility of non-heme Fe is determined by enhancers of iron absorption such as meat, amino acids, organic acids, antagonized by the inhibitors as bran, phytate and fibre. Haem Fe is absorbed directly as an intact metalloprotein porphyrin complex. The pathways of inorganic Fe into the mucosa cell Include endocytosis, electrogenic fatty acid mediated transcellular pathway, nonspecific paracellular permeation ar probably facilitated transcellular diffusion. The redox model proposes the reduction of Fe3+ by a transplasma membrane ferric reductase in lhe duodenal mucosa and the translocation of the Fe2+ across the cell probably by the nonesterified fatty acid. The mucin-mobilferrin-integrin pathway on the other hand involves the delivery of Fe-mucin complex in the lumen to the integrins of mucosa surface for translocation lo mobllferrin in the cytosol. The transfer of absorbed Fe iron from the mucosa into the blood is dependent on a number of regulatory intracellular and systemic factors

  13. Local structures and electronic band states of α−Fe2O3 polycrystalline particles in the glazes of the HIZEN celadons produced in the Edo period of Japan, by means of X-ray absorption spectra (II Estruturas locais e estados de banda de partículas policristalinas nos esmaltes de celadons Hizen produzidos no período Edo do Japão, por meio de espectros de absorção de raios X (II

    Directory of Open Access Journals (Sweden)

    M. Hidaka

    2011-06-01

    Full Text Available HIZEN celadon glazes produced in 1630's to 1790's (Edo period, Japan have been investigated by means of X-ray absorption spectra (XAS near a Fe-K edge by using synchrotron radiation and a Mössbauer spectrum. The XAS suggest that the local structure around Fe2O3 fine powders is slightly different between the Izumiyama ceramics of mainly the Quartz-SiO2 and Ohkawachi ceramics of mainly the feldspar of (K,NaSi3O8 (Sanidine, and that the glazes of the HIZEN celadons include the Fe2O3 fine powders in the glassy state, though the X-ray diffraction patterns of the glassy celadon glazes do not show any peaks of the Fe2O3 structure. The Mössbauer spectrum suggests that the celadon glaze of Seiji (m includes only Fe3+ ions, but not Fe2+ ions. This indicates the existence of Fe2O3 in the celadon glaze. It is interpreted that the colored brightness of the HIZEN celadons is induced by the structural properties of the used raw celadon ceramics and the other transition-metal ions of Cr, Cu, Zn in the celadon glazes, but not by the chemical reaction from Fe2O3 to FeO under the deoxidizing thermal treatment at higher temperature in a kiln.Esmaltes de celadon Hizen produzidos dos anos 1630 a 1790 (período Edo, Japão foram investigados por meio de espectros de absorção de raios X (XAS próximos da linha Fe-K usando radiação síncrotron e espectro Mossbaues. Os resultados de XAS sugerem que a estrutura local em pós finos de Fe2O3 é levemente diferente entre as cerâmicas Izumiyama principalmente o quartzo e cerâmicas Ohkawachi principalmente do feldspato (K,NaSi3O8 (Sanidine, e que os esmaltes dos celadons Hizen incluem finos pós de Fe2O3 no estado vítreo, embora os difratogramas de raios X dos esmaltes celadon não mostrem picos da estrutura do Fe2O3. O espectro Mossbauer sugere que os esmaltes celadon de Seiji (m incluem somente íons Fe3+, mas não Fe2+. Isto indica a existência de Fe2O3 no esmalte celadon. É feita a interpretação que o brilho

  14. Phytases for Improved Iron Absorption

    DEFF Research Database (Denmark)

    Nielsen, Anne Veller Friis; Nyffenegger, Christian; Meyer, Anne S.

    2014-01-01

    Microbial phytases (EC 3.1.3.8) catalyse dephosphorylation of phytic acid, which is the primary storage compound for phosphorous in cereal kernels. The negatively charged phosphates in phytic acid chelate iron (Fe3+) and thus retards iron bioavailability in humans 1. Supplementation of microbial...... phytase can improve iron absorption from cereal-based diets 2. In order for phytase to catalyse iron release in vivo the phytase must be robust to low pH and proteolysis in the gastric ventricle. Our work has compared the robustness of five different microbial phytases, evaluating thermal stability...

  15. Absorption of some powder materials to YAG laser

    Institute of Scientific and Technical Information of China (English)

    SHAOT.M.; LINX.C.; ZHOUM.

    2001-01-01

    Laser powder alloying is widely used for tribological applications. As one of the key pa-rameters , absorptivity of powder materials to laser plays an important role in the processing. Themeasurement of laser absorptivity is essential for absorptivity research. In present work, lumpedmethod based on heat transfer is established for laser absorptivity measurement. The absorptivityof some powder materials as Cu, Fe, Al, NiO, Al2O3, ZrO2, SiC, to YAG laser, are investigated.The results show that the absorptivity of powder materials to YAG laser is generally larger thanthat of bulk materials.

  16. Bioavailability of iron in geophagic earths and clay minerals, and their effect on dietary iron absorption using an in vitro digestion/Caco-2 cell model

    Science.gov (United States)

    Geophagy, the deliberate consumption of earth, is strongly associated with iron (Fe) deficiency. It has been proposed that geophagy may be practiced as a means to improve Fe status by increasing Fe intakes and, conversely, that geophagy may cause Fe deficiency by inhibiting Fe absorption. We tested ...

  17. XAFS和XRD研究高能球磨对Fe70Cu30合金结构的影响%X-ray absorption fine structure and x-ray diffraction studies on structures of Fe70 Cu30 alloys affected by mechanical alloying

    Institute of Scientific and Technical Information of China (English)

    范江玮; 卞清; 殷士龙; 闫文盛; 刘文汉; 韦世强

    2004-01-01

    利用XRD和XAFS方法研究机械合金化Fe70Cu30二元金属合金随球磨时间的结构变化.XRD结果表明,球磨2 h后,部分金属Fe与Cu生成Fe-Cu合金;球磨20h后,金属Fe与Cu已完全合金化生成Fe-Cu合金,并只在2θ=44°处出现一个宽化的弱衍射峰,认为是在球磨20h后的Fe70Cu30合金中共存着fcc和bcc结构的Fe-Cu合金相.XAFS结果进一步表明,在球磨的初始阶段(2h),fcc结构的Cu颗粒的晶格产生较大的畸变,其无序度σ(σ=σT+σS)为0.0190nm.球磨5h后,部分fcc结构的Cu原子进入了无序度相对较小的bcc结构的α-Fe相,导致Cu原子的平均无序度σ降为0.0108 nm.球磨10h后,样品中很大比例的Fe原子处于fcc结构的Fe-Cu合金相,其无序度为σ=0.0119 nm;而大部分Cu原子依然保持fcc结构,无序度为σ=0.0110 nm.这是由于扩散到bcc结构α-Fe相的Cu原子超过某一浓度后(约30%-40%),Cu原子能诱导其产生fcc结构相变所致.球磨时间增加到20h,样品中Cu原子和Fe原子在fcc和bcc相的比例与球磨10h基本相同,生成的Fe-Cu合金混合相的组成和结构分别近似于bcc结构的Fe80Cu20和fcc结构的Fe60Cu40.

  18. First-principles calculations of X-ray absorption spectra for warm dense methane

    Science.gov (United States)

    Li, Zi; Wang, Cong; Li, Dafang; Kang, Wei; Zhang, Ping

    2017-09-01

    X-ray absorption spectrum is a powerful tool for atomic structure detection on materials under extreme conditions. Here, we perform first-principles molecular dynamics and X-ray absorption spectrum calculations for warm dense methane under thermodynamical conditions along a Hugoniot curve. From the molecular dynamics trajectories, the detailed atomic structures are examined for each condition. The carbon K-shell X-ray absorption spectrum is calculated, and its change with temperature and pressure is discussed. The methane systems under extreme conditions may contain radicals CHx (x = 1,2,3), molecules CH4, and carbon chains CmHn (m,n >1). These various products show quite different contributions to the total X-ray spectrum due to the different atomic and electronic structures. The change of the total X-ray spectrum along the Hugoniot curve is then attributed to the change of the products induced by the temperature and pressure. Some clear signatures on the X-ray absorption spectrum under different thermodynamical conditions are proposed, which provide useful information for future X-ray experiments.

  19. Evidence for weak electronic correlations in Fe-pnictides

    Energy Technology Data Exchange (ETDEWEB)

    Yang, W.L.

    2010-04-29

    Using x-ray absorption and resonant inelastic x-ray scattering, charge dynamics at and near the Fe L edges is investigated in Fe pnictide materials, and contrasted to that measured in other Fe compounds. It is shown that the XAS and RIXS spectra for 122 and 1111 Fe pnictides are each qualitatively similar to Fe metal. Cluster diagonalization, multiplet, and density-functional calculations show that Coulomb correlations are much smaller than in the cuprates, highlighting the role of Fe metallicity and strong covalency in these materials. Best agreement with experiment is obtained using Hubbard parameters U {approx}< 2eV and J {approx} 0.8eV.

  20. Evidence for weak electronic correlations in Fe-Pnictides

    Energy Technology Data Exchange (ETDEWEB)

    Yang, W. L.; Sorini, A. P.; Chen, C-C.; Moritz, B.; Lee, W.-S.; Vernay, F.; Olalde-Velasco, P.; Denlinger, J. D.; Delley, B.; Chu, J.-H.; Analytis, J.G.; Fisher, I. R.; Ren, Z. A.; Yang, J.; Lu, W.; Zhao, Z. X.; van den Brink, J.; Hussain, Z.; Shen, Z.-X.; Devereaux, T. P.

    2009-06-11

    Using x-ray absorption and resonant inelastic x-ray scattering, charge dynamics at and near the Fe L edges is investigated in Fe pnictide materials, and contrasted tothat measured in other Fe compounds. It is shown that the XAS and RIXS spectra for 122 and 1111 Fe pnictides are each qualitatively similar to Fe metal. Cluster diagonalization, multiplet, and density-functional calculations show that Coulomb correlations are much smaller than in the cuprates, highlighting the role of Fe metallicity and strong covalency in these materials. Best agreement with experiment is obtained using Hubbard parameters U<~;; 2eV and J ~;; 0.8eV.

  1. Determination of Fe,Mn,Cu and Zn Elements in Oatmeal by Flame Atomic Absorption Spectrometry%火焰原子吸收分光光谱法测定燕麦片中铁、锰、铜、锌含量

    Institute of Scientific and Technical Information of China (English)

    杨葵华; 黎国兰; 谢丽; 邓文文

    2011-01-01

    采用HNO3-HClO4(4+1)湿法消解样品,用火焰原子吸收光谱法测定燕麦片中铁、锰、铜、锌的含量。测得铁、锰、铜、锌的回收率分别在98%~100%、99%~101%9、8%~99%9、6%~101%之间。平均回收率为96%~101%,RSD为0.3%~0.9%,表明该方法准确可靠。%To preprocess samples of oatmeal with HNO3-HClO4(4+1) wet digestion,the contents of Fe,Mn,Cu,Zn in oatmeal can be determined by flame atomic absorption spectrometry,obtaining the recovery rate of 98%~100% for Fe,99%~101% for Mn,98%~99% for Cu,96%~101% for Zn.,and the average rate is 96%~101%,RSD is 0.3%~0.9%.The result of this experiment shows that the method is reliable and accurate for the test.

  2. Determination of Cd,Cu,Pb,Fe,Zn in Bottled Drinking Water through Atomic Absorption Spectrometry Method%原子吸收光谱法对瓶装饮用水中Cd、Cu、Pb、Fe、Zn的分析

    Institute of Scientific and Technical Information of China (English)

    李帅; 沈祥森; 李勇

    2011-01-01

    10 different brands of commercial bottled drinking water for the experimental materials,using graphite furnace atomic absorption and flame atomic absorption spectrometry,the bottled water Cd、Cu、Pb、Fe、Zn five heavy metals were determined to understand the different brand bottled drinking water content of the five heavy metals.The results showed that:The whole bottled water content of the five heavy metals Cd、Cu、Pb、Fe、Zn are up to national standard requirements.%以10种不同品牌的市售瓶装饮用水为研究对象,运用石墨炉原子吸收法和火焰原子吸收法对其Cd、Cu、Pb、Fe、Zn5种重金属元素的含量进行分析,以了解不同品牌的瓶装饮用水中重金属元素的含量情况。研究结果表明:10种市售瓶装饮用水中的Cd、Cu、Pb、Fe、Zn 5种重金属含量均达到国标要求。

  3. Structural and microwave absorption properties of Ni{sub (1-x)}Co{sub (x)}Fe{sub 2}O{sub 4} (0.0 {<=} x {<=} 0.5) nanoferrites synthesized via co-precipitation route

    Energy Technology Data Exchange (ETDEWEB)

    Maqsood, Asghari, E-mail: tpl.qau@usa.net [Thermal Transport Laboratory, School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), H-12 Islamabad (Pakistan); Khan, Kishwar, E-mail: kishwar.nust@gmail.com [Thermal Transport Laboratory, School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), H-12 Islamabad (Pakistan)

    2011-02-17

    Research highlights: > Nanocrystalline Ni-Co was prepared by co-precipitation method. > The structural morphology was carried out using scanning electron microscope. > The complex relative permittivity ({epsilon}{sub r}) and complex relative permeability ({mu}{sub r}) were measured in the frequency range of 1 MHz to 3 GHz. > The variation of complex relative permittivity ({epsilon}{sub r}) as a function of frequency is explained in accordance with Maxwell-Wagner model and Koop's phenomenological theory. > Effect of frequency and cobalt concentration on permeability are reported. > The reflectivity (R) of nanoferrites is also calculated. > Results indicated that Ni{sub 1-x}Co{sub x}Fe{sub 2}O{sub 4} nanoparticles have excellent microwave absorbing properties, magneto-dielectric properties and have a great potential for military use. - Abstract: Ni-Co nanoferrites show excellent magneto-dielectric properties and these materials can be used to miniaturize the size of the high frequency devices which is the order of the day. Nanocrystalline Ni-Co ferrites having general formula Ni{sub 1-x}Co{sub x}Fe{sub 2}O{sub 4} (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) were prepared by co-precipitation method. The structural morphology of the prepared samples was carried out using scanning electron microscopy. The results showed the spherical shaped nanoparticles varying in the range of 16-40 nm. The complex relative permittivity ({epsilon}{sub r}) and complex relative permeability ({mu}{sub r}) were measured using vector network analyzer for all the samples in the frequency range of 1 MHz to 3 GHz. The variation of complex relative permittivity ({epsilon}{sub r}) as a function of frequency is explained in accordance with Maxwell-Wagner model and Koop's phenomenological theory. The effect of frequency and cobalt concentration on permeability are reported. The reflectivity (R) of nanoferrites is also calculated. The value of minimum reflection loss (RL) is about -18 dB at 2

  4. The importance of dietary composition for efficacy of iron absorption measured in a whole diet that includes rye bread fortified with ferrous fumerate: A radioisotope study in young women

    DEFF Research Database (Denmark)

    Tetens, Inge; Larsen, T.M.; Kristensen, M.B.

    2005-01-01

    Fe absorption is affected by many dietary factors. The objective of the present study was to measure the effects of high v. low content of vitamin C, meat and phytic acid in whole diets with Fe-fortified bread on the efficacy of Fe absorption. Thirty-two healthy women with low Fe stores were rand...

  5. 原子吸收法连续测定铋及氧化铋中铜铅铁镉镍%Sequential Determination of Cu, Pb, Fe, Cd and Ni in Bismuth and Bismuth Oxide by Atomic Absorption Spectrometry

    Institute of Scientific and Technical Information of China (English)

    张耀春

    2003-01-01

    HNO3分解样品后,直接用火焰原子吸收法测定铋及氧化铋中铜、铅、铁、镉、镍.方法的检出限分别为Cu 0.22 μg/g, Pb 1.5 μg/g, Fe 0.39 μg/g, Cd 0.11 μg/g , Ni 0.34 μg/g.与国标方法进行比较,分析结果基本一致,精密度试验,各元素的RSD(n=6)≤5.2% .

  6. Application of Triton X-100 coated poly vinyl chloride as new solid phase for preconcentration of Fe3+, Cu2+ and Zn2+ ions and their flame atomic absorption spectrometric determinations

    Directory of Open Access Journals (Sweden)

    Mehrorang Ghaedi

    2010-04-01

    Full Text Available A selective, sensitive and efficient method for preconcentration of trace amounts of Cu(II, Fe(II and Zn(II ions based on the uptake of their complexes with 3-((indolin-3-yl(phenylmethylindoline (IYPMI loaded on Triton X-100 coated poly vinyl chloride has been reported. The influences of the analytical parameters including pH, ligand amount, surfactant type and concentration, eluting condition and sample volume on metal ions recovery were investigated. The method has been successfully applied for the extraction of these ions content in some real samples of soil and plants. The extraction efficiency was > 97% with low relative standard deviation (RSD < 2.4% and the preconcentration factor of 90 (5 mL elution volume for a 450 mL of sample volume.

  7. Hydrogenation of nanocrystalline Zr-Fe-H powder

    Energy Technology Data Exchange (ETDEWEB)

    Roupcova, P. [Institute of Materials Engineering, Brno University of Technology, Technicka 2, 616 69 Brno (Czech Republic) and Institute of Physics of Materials, AS CR, Zizkova 22, 616 62 Brno (Czech Republic)]. E-mail: roupcova@ipm.cz; Schneeweiss, O. [Institute of Physics of Materials, AS CR, Zizkova 22, 616 62 Brno (Czech Republic); Zhu, M. [Department of Mechano-Electrical Engineering, South China University of Technology, Guangzhou, 510640 Guangdong (China)

    2005-12-08

    Changes in the phase composition of nanocrystalline Zr-Fe powders prepared by spark synthesis were investigated in dependence of the heat treatment in vacuum and hydrogen atmosphere. Mossbauer spectroscopy, X-ray diffraction and magnetic measurements were applied for phase analysis. {alpha}-Fe, Fe embedded in ZrO{sub 2}, ZrO{sub 2}, and iron oxides were found in the as-prepared powder. After annealing in hydrogen, {alpha}-Fe and ZrO{sub 2} dominate and minor Fe atoms embedded in ZrO{sub 2} and Fe{sub 2}Zr were detected. Zr-Fe phases were transformed gradually into the {alpha}-Fe and ZrO{sub 2} during the repeated annealing in vacuum and hydrogen. The ability of hydrogen absorption is decreasing with the annealing steps and is connected with the decrease of the Fe{sub 2}Zr phase content.

  8. RE L{sub 3} x-ray absorption study of REO{sub 1-x}F{sub x}FeAs (RE = La, Pr, Nd, Sm) oxypnictides

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, B; Iadecola, A; Bianconi, A; Saini, N L [Dipartimento di Fisica, Universita di Roma ' La Sapienza' , Piazza le Aldo Moro 2, 00185 Roma (Italy); Fratini, M [Istituto di Fotonica e Nanotecnologie, CNR Roma (Italy); Marcelli, A [Laboratori Nazionali di Frascati, INFN, 00044 Frascati (Italy)

    2009-10-28

    Rare earth L{sub 3}-edge x-ray absorption near-edge structure (XANES) spectroscopy has been used to study REOFeAs (RE = La, Pr, Nd, Sm) oxypnictides. The Nd L{sub 3} XANES due to the 2p{sub 3/2}->5epsilond transition shows a substantial change in both white line (WL) spectral weight and the higher energy multiple scattering resonances with the partial substitution of O by F. A systematic change in the XANES features is seen due to varying lattice parameters with ionic radius of the rare earth. On the other hand, we hardly see any change across the structural phase transition. The results provide timely information on the local atomic correlations showing the importance of the local structural chemistry of the REO spacer layer and interlayer coupling in the competing superconductivity and itinerant striped magnetic phase of the oxypnictides. (fast track communication)

  9. Online spectrophotometric determination of Fe(II) and Fe(III) by flow injection combined with low pressure ion chromatography

    Science.gov (United States)

    Chen, Shujuan; Li, Nan; Zhang, Xinshen; Yang, Dongjing; Jiang, Heimei

    2015-03-01

    A simple and new low pressure ion chromatography combined with flow injection spectrophotometric procedure for determining Fe(II) and Fe(III) was established. It is based on the selective adsorption of low pressure ion chromatography column to Fe(II) and Fe(III), the online reduction reaction of Fe(III) and the reaction of Fe(II) in sodium acetate with phenanthroline, resulting in an intense orange complex with a suitable absorption at 515 nm. Various chemical (such as the concentration of colour reagent, eluant and reductive agent) and instrumental parameters (reaction coil length, reductive coil length and wavelength) were studied and were optimized. Under the optimum conditions calibration graph of Fe(II)/Fe(III) was linear in the Fe(II)/Fe(III) range of 0.040-1.0 mg/L. The detection limit of Fe(III) and Fe(II) was respectively 3.09 and 1.55 μg/L, the relative standard deviation (n = 10) of Fe(II) and Fe(III) 1.89% and 1.90% for 0.5 mg/L of Fe(II) and Fe(III) respectively. About 2.5 samples in 1 h can be analyzed. The interfering effects of various chemical species were studied. The method was successfully applied in the determination of water samples.

  10. Production of nearly monodisperse Fe3O4 and Fe@Fe3O4 nanoparticles in aqueous medium and their surface modification for biomedical applications

    Science.gov (United States)

    Tegafaw, Tirusew; Xu, Wenlong; Lee, Sang Hyup; Chae, Kwon Seok; Chang, Yongmin; Lee, Gang Ho

    2017-02-01

    Iron (Fe)-based nanoparticles are extremely valuable in biomedical applications owing to their low toxicity and high magnetization values at room temperature. In this study, we synthesized nearly monodisperse iron oxide (Fe3O4) and Fe@Fe3O4 (core: Fe, shell: Fe3O4) nanoparticles in aqueous medium under argon flow and then, coated them with various biocompatible ligands and silica. In this study, eight types of surface-modified nanoparticles were investigated, namely, Fe3O4@PAA (PAA = polyacrylic acid; Mw of PAA = 5100 amu and 15,000 amu), Fe3O4@PAA-FA (FA = folic acid; Mw of PAA = 5100 amu and 15,000 amu), Fe3O4@PEI-fluorescein (PEI = polyethylenimine; Mw of PEI = 1300 amu), Fe@Fe3O4@PEI (Mw of PEI = 10,000 amu), Fe3O4@SiO2 and Fe@Fe3O4@SiO2 nanoparticles. We characterized the prepared surface-modified nanoparticles using high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) absorption spectroscopy, a superconducting quantum interference device (SQUID), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy and confocal microscopy. Finally, we measured the cytotoxicity of the samples. The results indicate that the surface-modified nanoparticles are biocompatible and are potential candidates for various biomedical applications.

  11. Transient absorption and laser output of YAG : Nd

    Science.gov (United States)

    Kvapil, Jiří; Kvapil, Jos; Kubelka, J.; Kubeček, V.

    1981-06-01

    YAG : Nd grown under 98% Ar 2% H2 protective atmosphere free of nitrogen or hydrocarbons showed after UV irradiation broad absorption peaked at ˜1·9×104 cm-1 which disappeared relatively slowly at room temperature. It was more intensive in oxygen treated samples than in those annealed in hydrogsn. Transient absorption suppresses laser output by the increase of absorption at 0·94×104 cm-1 (1064 nm) and, particularly in CW mode, by the anomalous rod deformation. YAG : Nd containing Fe ions (≲2·10-4 wt%) showed no transient absorption.

  12. Hard molecule-based magnet of Fe

    Science.gov (United States)

    Vaz, M. G. F.; Ardisson, J. D.; Stumpf, H. O.; Macedo, W. A. A.

    2001-05-01

    A new molecule-based magnet containing Fe 2+, Fe 3+, Cu(opba) 2- and Bu 4N +, with opba=ortho-phenylenebis(oxamato) and Bu 4N +=tetra-n-butylammonium, was synthesized. The samples were characterized by infrared spectroscopy, elemental analysis, atomic absorption, vibrating sample magnetometry and 57Fe Mössbauer spectroscopy. The magnetic measurements show that the compound presents a magnetic transition around 25 K and a high coercivity, around 1.3 T. Above the transition temperature, the Mössbauer spectrum is dominated by a broad doublet characteristic of Fe 2+. At 20 K, the spectrum shows clear magnetic splitting and at least two non-equivalent Fe sites can be identified. To the best of our knowledge, this compound presents the highest coercive field observed for an iron-based molecular magnetic system.

  13. Hard molecule-based magnet of Fe

    Energy Technology Data Exchange (ETDEWEB)

    Vaz, M.G.F. E-mail: vaz@urano.cdtn.br; Ardisson, J.D.; Stumpf, H.O.; Macedo, W.A.A

    2001-05-01

    A new molecule-based magnet containing Fe{sup 2+}, Fe{sup 3+}, Cu(opba){sup 2-} and Bu{sub 4}N{sup +}, with opba=ortho-phenylenebis(oxamato) and Bu{sub 4}N{sup +}=tetra-n-butylammonium, was synthesized. The samples were characterized by infrared spectroscopy, elemental analysis, atomic absorption, vibrating sample magnetometry and {sup 57}Fe Moessbauer spectroscopy. The magnetic measurements show that the compound presents a magnetic transition around 25 K and a high coercivity, around 1.3 T. Above the transition temperature, the Moessbauer spectrum is dominated by a broad doublet characteristic of Fe{sup 2+}. At 20 K, the spectrum shows clear magnetic splitting and at least two non-equivalent Fe sites can be identified. To the best of our knowledge, this compound presents the highest coercive field observed for an iron-based molecular magnetic system.

  14. D-xylose absorption

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003606.htm D-xylose absorption To use the sharing features on this page, please enable JavaScript. D-xylose absorption is a laboratory test to determine ...

  15. Accumulation of Fe oxyhydroxides in the Peruvian oxygen deficient zone implies non-oxygen dependent Fe oxidation

    Science.gov (United States)

    Heller, Maija I.; Lam, Phoebe J.; Moffett, James W.; Till, Claire P.; Lee, Jong-Mi; Toner, Brandy M.; Marcus, Matthew A.

    2017-08-01

    Oxygen minimum zones (OMZs) have been proposed to be an important source of dissolved iron (Fe) into the interior ocean. However, previous studies in OMZs have shown a sharp decrease in total dissolved Fe (dFe) and/or dissolved Fe(II) (dFe(II)) concentrations at the shelf-break, despite constant temperature, salinity and continued lack of oxygen across the shelf-break. The loss of both total dFe and dFe(II) suggests a conversion of the dFe to particulate form, but studies that have coupled the reduction-oxidation (redox) speciation of both dissolved and particulate phases have not previously been done. Here we have measured the redox speciation and concentrations of both dissolved and particulate forms of Fe in samples collected during the U.S. GEOTRACES Eastern tropical Pacific Zonal Transect (EPZT) cruise in 2013 (GP16). This complete data set allows us to assess possible mechanisms for loss of dFe. We observed an offshore loss of dFe(II) within the oxygen deficient zone (ODZ), where dissolved oxygen is undetectable, accompanied by an increase in total particulate Fe (pFe). Total pFe concentrations were highest in the upper ODZ. X-ray absorption spectroscopy revealed that the pFe maximum was primarily in the Fe(III) form as Fe(III) oxyhydroxides. The remarkable similarity in the distributions of total particulate iron and nitrite suggests a role for nitrite in the oxidation of dFe(II) to pFe(III). We present a conceptual model for the rapid redox cycling of Fe that occurs in ODZs, despite the absence of oxygen.

  16. Electronic structure of Fe- vs. Ru-based dye molecules

    DEFF Research Database (Denmark)

    Johnson, Phillip S.; Cook, Peter L.; Zegkinoglou, Ioannis;

    2013-01-01

    In order to explore whether Ru can be replaced by inexpensive Fe in dye molecules for solar cells, the differences in the electronic structure of Fe- and Ru-based dyes are investigated by X-ray absorption spectroscopy and first-principles calculations. Molecules with the metal in a sixfold...

  17. A lactic acid-fermented oat gruel increases non-haem iron absorption from a phytate-rich meal in healthy women of childbearing age

    DEFF Research Database (Denmark)

    Bering, S.; Suchdev, S.; Sjoltov, L.

    2006-01-01

    Lactic acid-fermented foods have been shown to increase Fe absorption in human subjects, possibly by lowering pH, activation of phytases, and formation of soluble complexes of Fe and organic acids. We tested the effect of an oat gruel fermented with Lactobacillus plantarum 299v on non-haem Fe....... The fermented gruel with live L. plantarum 299v increased Fe absorption significantly (P lactic acid concentration in the fermented gruel was 19 % higher than in the pasteurised gruel, but the Fe absorption was increased by 50...... %. In the gruel with organic acids, the lactic acid concentration was 52 % lower than in the pasteurised gruel, with no difference in Fe absorption. The fermented gruel increased non-haem Fe absorption from a phytate-rich meal in young women, indicating a specific effect of live L. plantarum 299v and not only...

  18. The effects of fruit juices and fruits on the absorption of iron from a rice meal.

    Science.gov (United States)

    Ballot, D; Baynes, R D; Bothwell, T H; Gillooly, M; MacFarlane, B J; MacPhail, A P; Lyons, G; Derman, D P; Bezwoda, W R; Torrance, J D

    1987-05-01

    The effects of the chemical composition of fruit juices and fruit on the absorption of iron from a rice (Oryza sativa) meal were measured in 234 parous Indian women, using the erythrocyte utilization of radioactive Fe method. The corrected geometric mean Fe absorptions with different juices varied between 0.040 and 0.129, with the variation correlating closely with the ascorbic acid contents of the juices (rs 0.838, P less than 0.01). Ascorbic acid was not the only organic acid responsible for the promoting effects of citrus fruit juices on Fe absorption. Fe absorption from laboratory 'orange juice' (100 ml water, 33 mg ascorbic acid and 750 mg citric acid) was significantly better than that from 100 ml water and 33 mg ascorbic acid alone (0.097 and 0.059 respectively), while Fe absorption from 100 ml orange juice (28 mg ascorbic acid) was better than that from 100 ml water containing the same amount of ascorbic acid (0.139 and 0.098 respectively). Finally, Fe absorption from laboratory 'lemon juice' (100 ml orange juice and 4 g citric acid) was significantly better than that from 100 ml orange juice (0.226 and 0.166 respectively). The corrected geometric mean Fe absorption from the rice meal was 0.025. Several fruits had little or no effect on Fe absorption from the meal (0.013-0.024). These included grape (Vitis vinifera), peach (Prunus persica), apple (Malus sylvestris) and avocado pear (Persea americana). Fruit with a mild to moderate enhancing effect on Fe absorption (0.031-0.088) included strawberry (Fragaria sp.) (uncorrected values), plum (Prunus domestica), rhubarb (Rheum rhaponticum), banana (Musa cavendishii), mango (Mangifera indica), pear (Pyrus communis), cantaloup (Cucumis melo) and pineapple (Ananas comosus) (uncorrected values). Guava (Psidium guajava) and pawpaw (Carica papaya) markedly increased Fe absorption (0.126-0.293). There was a close correlation between Fe absorption and the ascorbic acid content of the fruits tested (rs 0.738, P less

  19. X-ray absorption spectroscopy of soybean lipoxygenase-1 : Influence of lipid hydroperoxide activation and lyophilization on the structure of the non-heme iron active site

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Heijdt, L.M. van der; Feiters, M.C.; Navaratnam, S.; Nolting, H.-F.; Hermes, C.; Veldink, G.A.

    1992-01-01

    X-ray absorption spectra at the Fe K-edge of the non-heme iron site in Fe(II) as well as Fe(III) soybean lipoxygenase-1, in frozen solution or lyophilized, are presented; the latter spectra were obtained by incubation of the Fe(II) enzyme with its product hydroperoxide. An edge shift of about 23 eV

  20. Ionization and excitation of lithium atoms by fast charged particle impact: identification of mechanisms for double K-shell vacancy production as a function of the projectile charge and velocity; Ionisation et excitation de l'atome de lithium par impact de particules chargees rapides: Identification des mecanismes de creation de deux lacunes en couche K du lithium en fonction de la charge et de la vitesse du projectile

    Energy Technology Data Exchange (ETDEWEB)

    Rangama, J

    2002-11-01

    Ionization and excitation of lithium atoms by fast charged particle impact: identification of mechanisms for double K-shell vacancy production as a function of projectile charge and velocity. Auger electron spectroscopy is used for an experimental investigation of ionization and excitation of lithium atoms by ions (Kr34{sup +} and Ar18{sup +}) and electrons at high impact velocities (from 6 to 60 a.u.). In particular, relative contributions of the mechanisms responsible for lithium K-shell ionization-excitation are determined for various projectile charges Zp and velocities vp. A large range of perturbation parameters |Zp|/vp is explored (|Zp|/vp = 0,05 - 0,7 a.u.). From single K-shell excitation results, it appears that the projectile-electron interaction gives mainly rise to a dipole-like transition 1s -> np Concerning K-shell ionization-excitation, the separation of the TS2 (two independent projectile-electron interactions) and TS1 (one projectile-electron interaction) mechanisms responsible for the formation of the 2snp 1,3P and 2sns 1,3S lithium states is performed. In TS1 process, the projectile-electron interaction can be followed by an electron-electron interaction (dielectronic process) or by an internal rearrangement of the residual target after a sudden potential change (shake process). From Born theory, ab initio calculations are performed. The good agreement between theoretical and experimental results confirms the mechanism identification. For the production of P states, TS1 is found to be strongly dominant for small |Zp|/vp values and TS2 is found to be most important for large |Zp|/vp values. Since P states cannot be formed significantly via a shake process, the TS1 and TS2 separation provides a direct signature of the dielectronic process. On the other hand, the TS1 process is shown to be the unique process for producing the S states. At the moment, only the shake aspect of the TS1 process can explain the fact that the 2s3s configuration is

  1. 硅烷偶联剂表面处理后FeSiAl微米片的电磁和微波吸收特性研究%Electromagnetic and microwave absorption properties of surface modified FeSiAl micron-flakes with silane coupling agent

    Institute of Scientific and Technical Information of China (English)

    张永搏; 唐丽云; 徐飞; 位建强; 乔亮; 王涛

    2014-01-01

    FeSiAl 不规则颗粒在酒精溶剂中球磨,制备得到直径为10μm左右厚度为1μm左右的FeSiAl微米片,然后用硅烷偶联剂对微米片表面进行包裹处理。用电子显微镜和 X 射线光谱仪对包裹和未包裹样品做形貌观测和元素分析,并将样品制备成45%(体积分数)的石蜡复合材料,通过矢量网络分析仪测试其在0.1~18 GHz范围内的电磁参数,发现包裹和未包裹样品的复数磁导率曲线基本重合,但包裹后样品的复数介电常数有很明显的下降。微波传输理论计算表明,包裹后样品在L-S波段具有更优越吸波性能。%The irregular FeSiAl particle was used as a raw material for ball milling with alcohol solvent to pro-duce micron-flakes of the diameter and thickness was about 10 μm and 1 μm,and then used silane coupling agent to package the flakes surface.The morphology and the element content of the packaged sample were in-vestigated with SEM and XPS.The frequency-dependent complex permeability of paraffin composites with 45%volume concentration of flakes was measured using the coaxial line method in 0.1-18 GHz frequency range.Af-ter surface modification the complex permittivity of the packaged composite decreased dramatically in the 0.1-5 GHz frequency range,but the permeability wasn’t found obvious change.The calculated microwave re-flectivities indicated that packaged sample had better absorbing performance than unpackaged sample in L-S fre-quency band.

  2. Flooding impairs Fe uptake and distribution in Citrus due to the strong down-regulation of genes involved in Strategy I responses to Fe deficiency in roots.

    Directory of Open Access Journals (Sweden)

    Mary-Rus Martínez-Cuenca

    Full Text Available This work determines the ffects of long-term anoxia conditions--21 days--on Strategy I responses to iron (Fe deficiency in Citrus and its impact on Fe uptake and distribution. The study was carried out in Citrus aurantium L. seedlings grown under flooding conditions (S and in both the presence (+Fe and absence of Fe (-Fe in nutritive solution. The results revealed a strong down-regulation (more than 65% of genes HA1 and FRO2 coding for enzymes proton-ATPase and Ferric-Chelate Reductase (FC-R, respectively, in -FeS plants when compared with -Fe ones. H+-extrusion and FC-R activity analyses confirmed the genetic results, indicating that flooding stress markedly repressed acidification and reduction responses to Fe deficiency (3.1- and 2.0-fold, respectively. Waterlogging reduced by half Fe concentration in +FeS roots, which led to 30% up-regulation of Fe transporter IRT1, although this effect was unable to improve Fe absorption. Consequently, flooding inhibited 57Fe uptake in +Fe and -Fe seedlings (29.8 and 66.2%, respectively and 57Fe distribution to aerial part (30.6 and 72.3%, respectively. This evidences that the synergistic action of both enzymes H+-ATPase and FC-R is the preferential regulator of the Fe acquisition system under flooding conditions and, hence, their inactivation implies a limiting factor of citrus in their Fe-deficiency tolerance in waterlogged soils.

  3. Determination of Fe, Ca, Mg, Zn and Pb in Cinder and Activated Carbon by Flame Atomic Absorption Method%火焰原子吸收法测定煤渣和煤质活性炭中铁、钙、镁、锌、铅

    Institute of Scientific and Technical Information of China (English)

    薛慧; 董宾

    2014-01-01

    A method for measurement of metal microelements in cinders and activated carbon,such as Fe, Ca, Mg, Zn and Pb by flame atomic absorption method was established. Pretreatment procedure was studied. Cinders was treated with dry ashing and then digested,activated carbon was treated with acid extraction method. Metal microelements such as Fe,Ca and Mg in cinder were measured using standard curve method,while microelements such as Fe,Zn and Pb in activated carbon from coal were measured based on standard addition method,in order to reduce the interference of the basic. Results detected by the method were in accordance with existed references. Microelements contents were higher in cinders,especially after burning. In comparison,microelements dropped dramatically in activated carbon, due to the complex processing procedure. Recoveries of each element ranged from 88.5% to 105.5%, and the relative standard deviation was less than 2% (n=7). The detecting limits of the six elements were 0.010,0.015,0.005,0.012,0.013, 0.110 mg/L respectively, in two kinds of the specimen. It can be concluded that the flame atomic absorption method is accurate,convenient, it is suitable for the measurement of metal microelements in cinders and activated carbon.%建立了火焰原子吸收法测定煤渣和煤质活性炭中微量金属元素铁、钙、镁、锌、铅含量的方法。煤渣样品采用干灰化后消解,煤质活性炭样品采用稀酸提取进行处理。煤渣中铁、钙、镁元素用标准曲线法定量,活性炭中铁、锌、铅则采用标准加入法定量以减少基体干扰的影响。样品测定结果与文献报道相一致,煤渣尤其是燃烧处理后的煤渣中微量元素含量较高,而煤质活性炭通过复杂工艺处理后,微量元素大大减少。样品中被测元素的加标回收率在88.5%~105.5%之间,测定结果的相对标准偏差小于2%(n=7),两类样品中6种元素的检出限分别为0.010,0.015,0.005,0.012

  4. Microwave Power Absorption in Materials for Ferrous Metallurgy

    Science.gov (United States)

    Peng, Zhiwei; Li, Zhizhong; Lin, Xiaolong; Yang, Mengshen; Hwang, Jiann-Yang; Zhang, Yuanbo; Li, Guanghui; Jiang, Tao

    2016-11-01

    The characteristics of microwave power absorption in materials for ferrous metallurgy, including iron oxides (Fe2O3, Fe3O4 and Fe0.925O) and bitumite, were explored by evaluating their dielectric loss (Q E) and/or magnetic loss (Q H) distributions in the 0.05-m-thick slabs of the corresponding materials exposed to 1.2-kW and 2.45-GHz microwave radiation at temperatures below 1100°C. It is revealed that the dielectric loss contributes primarily to the power absorption in Fe2O3, Fe0.925O and the bitumite at all of the examined temperatures. Their Q E values at room temperature and slab surface are 9.1311 × 103 W m-3, 23.7025 × 103 W m-3, and 49.5999 × 103 W m-3, respectively, showing that the materials have the following heating rate initially under microwave irradiation: bitumite > Fe0.925O > Fe2O3. Compared with the other materials, Fe3O4 has much stronger power absorption, primarily originated from its magnetic loss (e.g., Q H = 1.0615 × 106 W m-3, Q H/Q E = 2.4185 at 24°C and slab surface), below its Curie point, above which the magnetic susceptibility approaches to zero, thereby causing a very small Q H value at even the surface (Q H = 1.0416 × 105 W m-3 at 880°C). It is also demonstrated that inhomogeneous power distributions occur in all the slabs and become more pronounced with increasing temperature mainly due to rapid increase in permittivity. Characterizing power absorption in the oxides and the coal is expected to offer a strategic guide for improving use of microwave energy in ferrous metallurgy.

  5. Variability in Low Ionization Broad Absorption Line Outflows

    CERN Document Server

    Vivek, M; Petitjean, P; Mohan, V; Mahabal, A; Samui, S

    2014-01-01

    We present results of our time variability studies of Mg II and Al III absorption lines in a sample of 22 Low Ionization Broad Absorption Line QSOs (LoBAL QSOs) at 0.2 = 1 year) absorption line variability is seen in 8 cases (36% systems) while only 4 of them (i.e 18% systems) show variability over short time-scales (i.e < 1 year). We notice a tendency of highly variable LoBAL QSOs to have high ejection velocity, low equivalent width and low redshift. The detection rate of variability in LoBAL QSOs showing Fe fine-structure lines (FeLoBAL QSOs) is less than that seen in non-Fe LoBAL QSOs. Absorption line variability is more frequently detected in QSOs having continuum dominated by Fe emission lines compared to rest of the QSOs. Confirming these trends with a bigger sample will give vital clues for understanding the physical distinction between different BAL QSO sub-classes. We correlate the absorption line variability with various parameters derived from continuum light curves and find no clear correlation...

  6. [Effect of polyphenols of coffee pulp on iron absorption].

    Science.gov (United States)

    de Rozo, M P; Vélez, J; García, L A

    1985-06-01

    The effect of the polyphenols of coffee pulp on iron absorption was studied using the method of ligated segments in rats. Optimal conditions to measure iron absorption, were determined using as criteria the concentration of Fe59 and the time that produced the highest value of blood radioactivity. A concentration of 0.4 uCi/dose of Fe59 and a 3-hr period were chosen to measure iron absorption. Experimental groups were formed assigning six rats randomly to each group. Each group was injected with a solution of 59Fe and either with the standard polyphenol solution or with the coffee pulp extract, except the control group which was injected with the Fe59 solution only. The effect of two polyphenol concentrations was also studied. Iron uptake from the duodenum was found to be the best indicator of iron absorption when compared to the sum of iron uptake by the tissues (blood, liver, spleen, kidneys, heart and carcass). Therefore, this indicator was used to interpret the results obtained. Catechin, tannic acid and the coffee pulp extract decreased significantly iron absorption when compared with the control group. The level of polyphenols used in these experiments is similar to the amounts consumed by animals fed coffee pulp at a 10% level. Therefore, we can conclude that the antinutritional effect of coffee pulp polyphenols may be partially due to their capacity to bind iron.

  7. Fighting Fe deficiency malnutrition in West Africa : an interdisciplinary programme on a food chain approach

    NARCIS (Netherlands)

    Slingerland, M.A.; Traore, K.; Kayodé, A.P.P.; Mitchikpe, C.E.S.

    2006-01-01

    About 2 billion people, mainly women and young children, suffer from iron deficiency. The supply of iron (Fe) falls short when consumed foods have a low Fe content or when absorption of Fe is inhibited by the presence of phytic acid and polyphenols in the diet. Current interventions are dietary

  8. Fighting Fe deficiency malnutrition in West Africa : an interdisciplinary programme on a food chain approach

    NARCIS (Netherlands)

    Slingerland, M.A.; Traore, K.; Kayodé, A.P.P.; Mitchikpe, C.E.S.

    2006-01-01

    About 2 billion people, mainly women and young children, suffer from iron deficiency. The supply of iron (Fe) falls short when consumed foods have a low Fe content or when absorption of Fe is inhibited by the presence of phytic acid and polyphenols in the diet. Current interventions are dietary dive

  9. [Study on lead absorption in pumpkin by atomic absorption spectrophotometry].

    Science.gov (United States)

    Li, Zhen-Xia; Sun, Yong-Dong; Chen, Bi-Hua; Li, Xin-Zheng

    2008-07-01

    A study was carried out on the characteristic of lead absorption in pumpkin via atomic absorption spectrophotometer. The results showed that lead absorption amount in pumpkin increased with time, but the absorption rate decreased with time; And the lead absorption amount reached the peak in pH 7. Lead and cadmium have similar characteristic of absorption in pumpkin.

  10. Calcium and iron absorption--mechanisms and public health relevance.

    Science.gov (United States)

    Lönnerdal, Bo

    2010-10-01

    Studies on human subjects have shown that calcium (Ca) can inhibit iron (Fe) absorption, regardless of whether it is given as Ca salts or in dairy products. This has caused concern as increased Ca intake commonly is recommended for children and women, the same populations that are at risk of Fe deficiency. However, a thorough review of studies on humans in which Ca intake was substantially increased for long periods shows no changes in hematological measures or indicators of iron status. Thus, the inhibitory effect may be of short duration and there also may be compensatory mechanisms. The interaction between Ca and Fe may be a lumenal event, affecting Fe uptake through DMT1 (divalent metal transporter 1) at the apical membrane. However, it is also possible that inhibition occurs during Fe transfer into circulation, suggesting roles for the serosal exporter ferroportin (FPN) and hephaestin. We explored these possibilities in human intestinal Caco-2 cells cultured in monolayers. Iron transport ((59)Fe) and expression of DMT1, FPN, and hephaestin were assessed after 1.5 and 4 hours with 0 or 100 µM CaCl(2.) Although Ca did not affect Fe uptake or DMT1 expression at 1.5 hours, FPN abundance at the basolateral membrane decreased, resulting in increased cellular Fe retention and decreased Fe efflux. After 4 hours, DMT1 and FPN expression increased and there was increased FPN at the membrane, suggesting a rebound effect. Thus, the effect of Ca on Fe absorption may be of short duration and adaptation may occur with time. This may explain why studies on long-term Ca supplementation of different groups fail to show any adverse effects on Fe status.

  11. Experimental Validation of Modeled Fe Opacities at Conditions Approaching the Base of the Solar Convection Zone

    Science.gov (United States)

    Nagayama, Taisuke

    2013-10-01

    Knowledge of the Sun is a foundation for other stars. However, after the solar abundance revision in 2005, standard solar models disagree with helioseismic measurements particularly at the solar convection zone base (CZB, r ~ 0 . 7 ×RSun) [Basu, et al., Physics Reports 457, 217 (2008)]. One possible explanation is an underestimate in the Fe opacity at the CZB [Bailey et al., Phys. Plasmas 16, 058101 (2009)]. Modeled opacities are important physics inputs for plasma simulations (e.g. standard solar models). However, modeled opacities are not experimentally validated at high temperatures because of three challenging criteria required for reliable opacity measurements: 1) smooth and strong backlighter, 2) plasma condition uniformity, and 3) simultaneous measurements of plasma condition and transmission. Fe opacity experiments are performed at the Sandia National Laboratories (SNL) Z-machine aiming at conditions close to those at the CZB (i.e. Te = 190 eV, ne = 1 ×1023 cm-3). To verify the quality of the experiments, it is critical to investigate how well the three requirements are satisfied. The smooth and strong backlighter is provided by the SNL Z-pinch dynamic hohlraum. Fe plasma condition is measured by mixing Mg into the Fe sample and employing Mg K-shell line transmission spectroscopy. Also, an experiment is designed and performed to measure the level of non-uniformity in the Fe plasma by mixing Al and Mg dopants on the opposite side of the Fe sample and analyzing their spectra. We will present quantitative results on these investigations as well as the comparison of the measured opacity to modeled opacities. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL85000.

  12. Magnetic Properties and Microstructure of FeOx/Fe/FePt and FeOx/FePt Films

    Directory of Open Access Journals (Sweden)

    Jai-Lin Tsai

    2013-01-01

    Full Text Available The Fe(6 nm/FePt film with perpendicular magnetization was deposited on the glass substrate. To study the oxygen diffusion effect on the coupling of Fe/FePt bilayer, the plasma oxidation with 0.5~7% oxygen flow ratio was performed during sputtered part of Fe layer and formed the FeOx(3 nm/Fe(3 nm/FePt trilayer. Two-step magnetic hysteresis loops were found in trilayer with oxygen flow ratio above 1%. The magnetization in FeOx and Fe/FePt layers was decoupled. The moments in FeOx layer were first reversed and followed by coupled Fe/FePt bilayer. The trilayer was annealed again at 500°C and 800°C for 3 minutes. When the FeOx(3 nm/Fe(3 nm/FePt trilayer was annealed at 500°C, the layers structure was changed to FeOx(6 nm/FePt bilayer due to oxygen diffusion. The hard-magnetic FeOx(6 nm/FePt film was coupled with single switching field. The FeOx/(disordered FePt layer structure was observed with further annealing at 800°C and presented soft-magnetic loop. In summary, the coupling between soft-magnetic Fe, FeOx layer, and hard-magnetic L10 FePt layer can be controlled by the oxygen diffusion behavior, and the oxidation of Fe layer was tuned by the annealing temperature. The ordered L10 FePt layer was deteriorated by oxygen and became disordered FePt when the annealed temperature was up to 800°C.

  13. Fe(III)EDTA and Fe(II)EDTA-NO reduction by a sulfate reducing bacterium in NO and SO₂ scrubbing liquor.

    Science.gov (United States)

    Chen, Mingxiang; Zhou, Jiti; Zhang, Yu; Wang, Xiaojun; Shi, Zhuang; Wang, Xiaowei

    2015-03-01

    A viable process concept, based on NO and SO2 absorption into an alkaline Fe(II)EDTA (EDTA: ethylenediaminetetraacetic acid) solution in a scrubber combined with biological reduction of the absorbed SO2 utilizing sulfate reducing bacteria (SRB) and regeneration of the scrubbing liquor in a single bioreactor, was developed. The SRB, Desulfovibrio sp. CMX, was used and its sulfate reduction performances in FeEDTA solutions and Fe(II)EDTA-NO had been investigated. In this study, the detailed regeneration process of Fe(II)EDTA solution, which contained Fe(III)EDTA and Fe(II)EDTA-NO reduction processes in presence of D. sp. CMX and sulfate, was evaluated. Fe(III)EDTA and Fe(II)EDTA-NO reduction processes were primarily biological, even if Fe(III)EDTA and Fe(II)EDTA-NO could also be chemically convert to Fe(II)EDTA by biogenic sulfide. Regardless presence or absence of sulfate, more than 87 % Fe(III)EDTA and 98 % Fe(II)EDTA-NO were reduced in 46 h, respectively. Sulfate and Fe(III)EDTA had no affection on Fe(II)EDTA-NO reduction. Sulfate enhanced final Fe(III)EDTA reduction. Effect of Fe(III)EDTA on Fe(II)EDTA-NO reduction rate was more obvious than effect of sulfate on Fe(II)EDTA-NO reduction rate before 8 h. To overcome toxicity of Fe(II)EDTA-NO on SRB, Fe(II)EDTA-NO was reduced first and the reduction of Fe(III)EDTA and sulfate occurred after 2 h. First-order Fe(II)EDTA-NO reduction rate and zero-order Fe(III)EDTA reduction rate were detected respectively before 8 h.

  14. The effects of FeCl₃ and Fe-EDTA on the development of psoriasis.

    Science.gov (United States)

    Shi, Qiang; Yang, Xiao-qian; Cui, Xi

    2011-04-01

    The effects of FeCl₃ and Fe-EDTA on the development of psoriasis were studied in the mouse model of vaginal epithelium and tail epidermis. The mitoses of vaginal epithelial cell in female mice of their estrogenic stage and the formation of granular cell layers in male mouse tail scale were observed. Mice were randomly divided into eight groups and treated with normal saline, methotrexate, and different doses of two iron forms, FeCl₃ and Fe-EDTA, respectively, for 10 days. To explore the influence of FeCl₃ and Fe-EDTA on the excretion of Cu, Fe, Zn, Ca, Mg, Mn, and Se, the concentration of those elements in liver and kidney was analyzed by atomic absorption spectrometry. The different doses of FeCl₃ or Fe-EDTA could obviously inhibit the mitoses of vaginal epithelial cell (pEDTA, and between experimental groups and methotrexate group acted as the positive control (p>0.05). Compared with the negative group, the concentrations of Cu, Fe, Zn, Ca, Mg, Mn, and Se in liver and kidney of experimental groups and positive control group were not significantly changed (p > 0.05). FeCl₃ and Fe-EDTA are as effective as methotrexate on inhibiting hyperplasia of epidermal cells and increasing the formation of granular cell layers, and the concentrations of Cu, Fe, Zn, Ca, Mg, Mn, and Se in liver and kidney of experimental groups and positive control group were not significantly changed compared with the negative group, possibly retarding the development of psoriasis.

  15. Correlation of cation distribution with the hyperfine and magnetic behaviour of Ni0.3Zn0.4Co0.2Cu0.1Fe2O4 nanoparticles and their microwave absorption properties when encapsulated in multi-walled carbon nanotubes

    Science.gov (United States)

    Dalal, Madhumita; Mallick, Ayan; Greneche, Jean-Marc; Das, Dipankar; Chakrabarti, Pabitra K.

    2017-03-01

    Nanocrystalline samples of Ni0.3Zn0.4Co0.2Cu0.1Fe2O4 (NZCCF) are prepared by a simple co-precipitation method. To obtain nanoparticles of different sizes, the as prepared sample is annealed at 400, 600, 800 and 1000 °C. Nanoparticles of the sample annealed at 600 °C are encapsulated in multi-walled carbon nanotubes (MWCNT). To confirm the crystallographic phase, x-ray diffraction (XRD) patterns are analyzed by the Rietveld method and cation distribution in A- and B-sites is estimated from the analysis. Occupancy of Zn2+ ions in A-site and that of Fe3+ ions in B-site increase with the increase of annealing temperature (T A) and lattice parameters lie within 8.365-8.398 Å. Morphology of the encapsulated sample is examined by taking micrographs in high resolution transmission electron microscope (HRTEM). Hyperfine behaviour of the prepared samples is studied by analyzing Mössbauer spectra recorded at room temperature (RT) and 77 K. Average values of isomer shift (IS) are found to decrease with the increase of crystallite size. Static and dynamic magnetic hysteresis loops are recorded to analyze the magnetic properties of the sample. Maximum saturation magnetization of ~75 emu g-1 is obtained for the sample of NZCCF annealed at 800 °C with crystallite size of ~48 nm. Microwave absorption capability of the encapsulated sample is measured by recording the reflection loss in X and K u bands of microwave region of frequency. Maximum value of reflection loss is  -25.71 dB observed at 15.24 GHz for a sample layer thickness of 1 mm. Moreover, the reflection loss is less than  -10 dB for the entire range of observation (8-18 GHz) which shows that MWCNT encapsulated NZCCF could be considered as a potential candidate for applications in microwave devices.

  16. Iron K Features in the Quasar E 1821+643: Evidence for Gravitationally Redshifted Absorption?

    Science.gov (United States)

    Yaqoob, Tahir; Serlemitsos, Peter

    2005-01-01

    We report a Chandra high-energy grating detection of a narrow, redshifted absorption line superimposed on the red wing of a broad Fe K line in the z = 0.297 quasar E 1821+643. The absorption line is detected at a confidence level, estimated by two different methods, in the range approx. 2 - 3 sigma. Although the detection significance is not high enough to exclude a non-astrophysical origin, accounting for the absorption feature when modeling the X-ray spectrum implies that the Fe-K emission line is broad, and consistent with an origin in a relativistic accretion disk. Ignoring the apparent absorption feature leads to the conclusion that the Fe-K emission line is narrower, and also affects the inferred peak energy of the line (and hence the inferred ionization state of Fe). If the absorption line (at approx. 6.2 keV in the quasar frame) is real, we argue that it could be due to gravitationally redshifted Fe XXV or Fe XXVI resonance absorption within approx. 10 - 20 gravitational radii of the putative central black hole. The absorption line is not detected in earlier ASCA and Chandra low-energy grating observations, but the absorption line is not unequivocally ruled out by these data. The Chandra high-energy grating Fe-K emission line is consistent with an origin predominantly in Fe I-XVII or so. In an ASCA observation eight years earlier, the Fe-K line peaked at approx. 6.6 keV, closer to the energies of He-like Fe triplet lines. Further, in a Chandra low-energy grating observation the Fe-K line profile was double-peaked, one peak corresponding to Fe I-XVII or so, the other peak to Fe XXVI Ly alpha. Such a wide range in ionization state of Fe is not ruled out by the HEG and ASCA data either, and is suggestive of a complex structure for the line-emitter.

  17. Optical Properties of Mg, Fe, Co-Doped Near-Stoichiometric LiTaO3 Single Crystals

    Directory of Open Access Journals (Sweden)

    Chung Wen Lan

    2012-01-01

    Full Text Available Mg, Fe co-doped near-stoichiometric lithium tantalite (SLT single crystals were grown by employing the zone-leveling Czochralski (ZLCz technique. The optical properties, holographic parameters, as well as the composition of the grown crystals were measured. It was found that the Li/Ta ratio decreased with the doping of Mg and Fe ions. A red shift was observed in absorption spectrum for the Mg, Fe co-doped crystals compared to the undoped and Mg-doped ones. The effect of the iron ions (Fe2+ and Fe3+ was further discussed based on the specified absorption bands. Moreover, the occupation mechanism for the defects was discussed by using the IR absorption spectrum, which was attributed to the FeTa3− defects in the highly Fe-doped crystal. In addition, the holographic parameters were also found to be improved with a higher Fe/Ta ratio in the crystals.

  18. The HI absorption "Zoo"

    NARCIS (Netherlands)

    Geréb, K.; Maccagni, F. M.; Morganti, R.; Oosterloo, T. A.

    2015-01-01

    We present an analysis of the H I 21 cm absorption in a sample of 101 flux-selected radio AGN (S1.4 GHz> 50 mJy) observed with the Westerbork Synthesis Radio Telescope (WSRT). We detect H I absorption in 32 objects (30% of the sample). In a previous paper, we performed a spectral stacking analysis o

  19. Bioacoustic Absorption Spectroscopy

    Science.gov (United States)

    2016-06-07

    frequencies (Ching and Weston, 1971). RESULTS Measured resonance frequencies of absorption lines, which were attributed to adult (~ 1.3 khz) and juvenile ...of adult and juvenile sardines. These results suggest that bioacoustic absorption spectroscopy measurements permit isolation of juvenile from adult...from broadband tomographic transmission loss measurements over large areas . 2. Depths of sardines and contours of phytoplankton concentrations vs. time

  20. Nutrition and magnesium absorption.

    NARCIS (Netherlands)

    Brink, E.J.

    1992-01-01

    The influence of various nutrients present in dairy products and soybean-based products on absorption of magnesium has been investigated. The studies demonstrate that soybean protein versus casein lowers apparent magnesium absorption in rats through its phytate component. However, true magnesium abs

  1. Iron absorption from experimental infant formulas based on pea (Pisum sativum)-protein isolate: the effect of phytic acid and ascorbic acid.

    Science.gov (United States)

    Davidsson, L; Dimitriou, T; Walczyk, T; Hurrell, R F

    2001-01-01

    Infant formula based on pea (Pisum sativum)-protein isolate has been suggested as an alternative to soybean formula in countries where soybean is not a native crop, or when soybean protein cannot be used due to allergic reactions or intolerances. In the present study, Fe absorption from experimental infant formulas based on pea-protein isolate was measured in healthy non-anaemic young women. The influence of phytic acid and ascorbic acid on Fe absorption was evaluated, using a stable-isotope technique based on incorporation of Fe stable-isotope labels into erythrocytes 14 d after administration. Geometric mean Fe absorption increased from 20.7 (+1 SD 41.6, -1 SD 10.3) % to 33.1 (+1 SD 58.6, -1 SD 18.7) %; (P phytic acid. Doubling the molar ratio Fe:ascorbic acid from 1:2.1 to 1:4.2 in the infant formula with native phytic acid content also increased Fe absorption significantly (P phytic acid and ascorbic acid respectively on Fe absorption, but also indicate relatively high fractional Fe absorption from the pea-protein-based formulas. After adjusting for differences in Fe status, our data indicate that Fe absorption from dephytinised pea protein might be less inhibitory than dephytinised soybean protein as measured in a previous study (Hurrell et al. 1998).

  2. Iron analysis in atmospheric water samples by atomic absorption spectroscopy (AAS) in water-methanol.

    Science.gov (United States)

    Sofikitis, A M; Colin, J L; Desboeufs, K V; Losno, R

    2004-01-01

    To distinguish between Fe(II) and Fe(III) species in atmospheric water samples, we have adapted an analytical procedure based on the formation of a specific complex between Fe(II) and ferrozine (FZ) on a chromatographic column. After elution of Fe(III), the Fe(II) complex is recovered with water-methanol (4:1). The possibility of trace iron measurements in this complex medium by graphite-furnace atomic-absorption spectrometry has been investigated. A simplex optimization routine was required to complete the development of the analytical method.

  3. Fe~Ⅱ(EDTA)络合协同RDB去除NO废气效能及过程分析%Investigation of Effect and Process of Nitric Oxide Removal in Rotating Drum Biofilter Coupled with Absorption by Fe~Ⅱ(EDTA)

    Institute of Scientific and Technical Information of China (English)

    陈浚; 杨宣; 於建明; 蒋轶锋; 陈建孟

    2012-01-01

    为进一步提高一氧化氮(NO)的去除效率,在新型生物转鼓反应器(rotating drum biofilter,RDB)中,以FeⅡ(EDTA)络合协同RDB生物转鼓的耦合技术强化难水溶性NO的气液传质速率,提高生物还原效能为目标进行了研究.结果表明,适量FeⅡ(EDTA)被添加到RDB底部营养液后,能迅速吸收气相中的NO并生成FeⅡ(EDTA)-NO络合物,进而可通过反硝化实现同步脱氮和络合剂再生.在转速0.5 r.min-1、空床停留时间(EBRT)57.7 s、温度30℃、pH 7~8的实验条件下,RDB的净化效能随络合剂的投加而显著改善;FeⅡ(EDTA)质量浓度从0增至500 mg.L-1后,NO去除率从61.1%提高到97.6%,去除负荷从16.2 g.(m3.h)-1上升到26.7 g.(m3.h)-1.分析了FeⅡ(EDTA)络合协同净化NO的反应过程,建立了NO净化效率与FeⅡ(EDTA)添加浓度的关联方程,可较好地拟合实验数据.%In order to accelerate the NO removal efficiency,a novel and effective system was developed for the complete treatment of NO from flue gases.The system features NO absorption by FeⅡ(EDTA) and biological denitrification in a rotating drum biofilter(RDB) so as to promote biological reduction.The experimental results show that a moderate amount of FeⅡ(EDTA) was added to the nutrient solution to improve the mass transfer efficiency of NO from gas to liquid,with the concomitant formation of nitrosyl complex FeⅡ(EDTA)-NO.Under the experimental conditions of rotational speed was at 0.5 r·min-1,EBRT of 57.7 s,temperature was at 30℃,pH was 7-8,with the increasing concentration of FeⅡ(EDTA) was from 0 mg·L-1 to 500 mg·L-1,the NO removal efficiency was improved from 61.1% to 97.6%,and the elimination capacity was from 16.2 g·(m3·h)-1 to 26.7 g·(m3·h)-1.In order to simulate the denitrifying process of waste gas containing NO by using RDB coupled with FeⅡ(EDTA) absorption,a tie-in equation of NO removal and the

  4. [Study on cadmium absorption in pumpkin by atomic absorption spectrophotometry].

    Science.gov (United States)

    Li, Zhen-Xia; Jing, Rui-Jun; Dong, Wei-Hua; Li, Xin-Zheng; Liu, Hong

    2006-08-01

    A study was carried out on the characteristic of cadmium absorption in pumpkin by atomic absorption spectrophotometer. The results show that the cadmium absorption amount in pumpkin increased with the increase in cadmium concentration. Meanwhile the cadmium absorption amount in pumpkin increased with time. Eight hours after being cultured in the liquid, the cadmium absorption amount became saturated. The cadmium absorption rate reached the peak after 2 hours, then the absorption rate gradually reduced. The cadmium absorption amount in pumpkin is less in acid or alkali compared with neutral condition. And the absorption amount became minimum in pH 3, while maximum in pH 7.

  5. Proton induced K X-ray production cross sections of the elements Al, Si, Ti, Fe, and Ni in the 0.7–2.0 MeV energy range

    Energy Technology Data Exchange (ETDEWEB)

    Bertol, Ana Paula Lamberti [Programa de Pós Graduação em Física, PPGFis, Universidade Federal do Rio Grande do Sul, UFRGS, Porto Alegre, RS (Brazil); Hinrichs, Ruth [PPGFis and Instituto de Geociências, UFRGS (Brazil); Vasconcellos, Marcos A.Z. [PPGFis and Instituto de Física, UFRGS (Brazil)

    2015-12-15

    Proton induced K-shell ionization cross sections were obtained for the elements Al, Si, Ti, Fe, and Ni in the 0.7–2.0 MeV energy range. The accuracy of these fundamental parameters is essential for PIXE analysis and the data in the literature present a considerable spread, mainly for Al and Si. The values obtained for Ti, Fe and Ni are compatible with the current theories and the experimental results reported in the literature. However, Al and Si cross sections present important differences from theoretical and experimental data. We propose values for the fluorescent yields of Al and Si that are compatible with recent results and can be incorporated in the computations of K X-ray production cross sections.

  6. Protein Hydrolysates as Promoters of Non-Haem Iron Absorption

    Directory of Open Access Journals (Sweden)

    Yanan Li

    2017-06-01

    Full Text Available Iron (Fe is an essential micronutrient for human growth and health. Organic iron is an excellent iron supplement due to its bioavailability. Both amino acids and peptides improve iron bioavailability and absorption and are therefore valuable components of iron supplements. This review focuses on protein hydrolysates as potential promoters of iron absorption. The ability of protein hydrolysates to chelate iron is thought to be a key attribute for the promotion of iron absorption. Iron-chelatable protein hydrolysates are categorized by their absorption forms: amino acids, di- and tri-peptides and polypeptides. Their structural characteristics, including their size and amino acid sequence, as well as the presence of special amino acids, influence their iron chelation abilities and bioavailabilities. Protein hydrolysates promote iron absorption by keeping iron soluble, reducing ferric iron to ferrous iron, and promoting transport across cell membranes into the gut. We also discuss the use and relative merits of protein hydrolysates as iron supplements.

  7. Dietary inulin supplementation does not promote colonic iron absorption in a porcine model

    Science.gov (United States)

    Prebiotics may enhance iron bioavailability by increasing iron absorption in the colon. Anemic pigs fitted with cecal cannulas were fed a low-iron diet with or without 4% inulin. Over 7 days, pigs were administered 1 mg 54 Fe in the morning feed followed by cannula infusion of 0.5 mg 58 Fe to measu...

  8. Quasar Absorption Studies

    Science.gov (United States)

    Mushotzky, Richard (Technical Monitor); Elvis, Martin

    2004-01-01

    The aim of the proposal is to investigate the absorption properties of a sample of inter-mediate redshift quasars. The main goals of the project are: Measure the redshift and the column density of the X-ray absorbers; test the correlation between absorption and redshift suggested by ROSAT and ASCA data; constrain the absorber ionization status and metallicity; constrain the absorber dust content and composition through the comparison between the amount of X-ray absorption and optical dust extinction. Unanticipated low energy cut-offs where discovered in ROSAT spectra of quasars and confirmed by ASCA, BeppoSAX and Chandra. In most cases it was not possible to constrain adequately the redshift of the absorber from the X-ray data alone. Two possibilities remain open: a) absorption at the quasar redshift; and b) intervening absorption. The evidences in favour of intrinsic absorption are all indirect. Sensitive XMM observations can discriminate between these different scenarios. If the absorption is at the quasar redshift we can study whether the quasar environment evolves with the Cosmic time.

  9. Seasonal changes in Fe species and soluble Fe concentration in the atmosphere in the Northwest Pacific region based on the analysis of aerosols collected in Tsukuba, Japan

    Directory of Open Access Journals (Sweden)

    Y. Takahashi

    2013-08-01

    Full Text Available Atmospheric iron (Fe can be a significant source of nutrition for phytoplankton inhabiting remote oceans, which in turn has a large influence on the Earth's climate. The bioavailability of Fe in aerosols depends mainly on the fraction of soluble Fe (= [FeSol]/[FeTotal], where [FeSol] and [FeTotal] are the atmospheric concentrations of soluble and total Fe, respectively. However, the numerous factors affecting the soluble Fe fraction have not been fully understood. In this study, the Fe species, chemical composition, and soluble Fe concentrations in aerosols collected in Tsukuba, Japan were investigated over a year (nine samples from December 2002 to October 2003 to identify the factors affecting the amount of soluble Fe supplied into the ocean. The soluble Fe concentration in aerosols is correlated with those of sulfate and oxalate originated from anthropogenic sources, suggesting that soluble Fe is mainly derived from anthropogenic sources. Moreover, the soluble Fe concentration is also correlated with the enrichment factors of vanadium and nickel emitted by fossil fuel combustion. These results suggest that the degree of Fe dissolution is influenced by the magnitude of anthropogenic activity, such as fossil fuel combustion. X-ray absorption fine structure (XAFS spectroscopy was performed in order to identify the Fe species in aerosols. Fitting of XAFS spectra coupled with micro X-ray fluorescence analysis (μ-XRF showed the main Fe species in aerosols in Tsukuba to be illite, ferrihydrite, hornblende, and Fe(III sulfate. Moreover, the soluble Fe fraction in each sample measured by leaching experiments is closely correlated with the Fe(III sulfate fraction determined by the XAFS spectrum fitting, suggesting that Fe(III sulfate is the main soluble Fe in the ocean. Another possible factor that can control the amount of soluble Fe supplied into the ocean is the total Fe(III concentration in the atmosphere, which was high in spring due to the high

  10. Seasonal changes in Fe species and soluble Fe concentration in the atmosphere in the Northwest Pacific region based on the analysis of aerosols collected in Tsukuba, Japan

    Directory of Open Access Journals (Sweden)

    Y. Takahashi

    2013-03-01

    Full Text Available Atmospheric iron (Fe can be a significant source of nutrition for phytoplankton inhabiting remote oceans, which in turn has a large influence on the Earth's climate. The bioavailability of Fe in aerosols depends mainly on the fraction of soluble Fe (= [FeSol]/[FeTotal], where [FeSol] and [FeTotal] are the atmospheric concentrations of soluble and total Fe, respectively. However, the numerous factors affecting the soluble Fe fraction have not been fully understood. In this study, the Fe species, chemical composition, and soluble Fe concentrations in aerosols collected in Tsukuba, Japan were investigated over a year (nine samples from December 2002 to October 2003 to identify the factors affecting the amount of soluble Fe supplied into the ocean. The soluble Fe concentration in aerosols is correlated with those of sulfate and oxalate originated from anthropogenic sources, suggesting that soluble Fe is mainly derived from anthropogenic sources. Moreover, the soluble Fe concentration is also correlated with the enrichment factors of vanadium and nickel emitted by fossil fuel combustion. These results suggest that the degree of Fe dissolution is influenced by the magnitude of anthropogenic activity, such as fossil fuel combustion. X-ray absorption fine structure (XAFS spectroscopy was performed in this study to identify the Fe species in aerosols. The fitting of XAFS spectra coupled with micro X-ray fluorescence analysis (XRF determined the main Fe species in aerosols in Tsukuba to be illite, ferrihydrite, hornblende, and Fe(III sulfate. Moreover, the soluble Fe fraction in each sample measured by leaching experiments is closely correlated with the Fe(III sulfate fraction determined by the XAFS spectrum fitting, suggesting that Fe(III sulfate is the main soluble Fe in the ocean. Another possible factor that can control the amount of soluble Fe supplied into the ocean is the total Fe(III concentration in the atmosphere, which was high in spring due to

  11. Absorption and emission spectroscopy in natural and synthetic corundum

    Science.gov (United States)

    Spinolo, G.; Palanza, V.; Ledonne, A.; Paleari, A.

    2009-04-01

    In the frame of an extensive project on the optical characterization of the many varieties of corundum (see:www.gemdata.mater.unimib.it ) we reconsidered the current interpretation of the absorption spectra with particular attention to the bands attributed to the IVCT mechanism Fe2+→ Fe3+ and Fe2+→Ti4+. A detailed study was devoted to natural metamorphic and Verneuil synthetic pale blue sapphires . In that paper (I.Fontana et al 2008) we gave experimental evidence that the band at 17500 cm-1 often attributed to Fe2+→Ti4+ IVCT transitions is in reality due to the 4T2 crystal field transition of Cr3+ partially overlapped by the 2E of Ti3+. The results of radio and photoluminescence excitation experiments obtained there, led us to propose that the color of these sapphires is mainly due to Cr in its two valence states ; Ti 3+ and Fe3+ have a minor role. After those encouraging results, we decided to apply the same approach to the study of deep blue and yellow sapphires of magmatic origin. Evaluation of impurity ion concentration by EDXRF revealed that in all these samples the concentration of Fe is quite high (around 1%) while Cr and Ti are barely detectable. Characteristic of the absorption spectra of deep blue samples is the dominant presence of the 5E spin allowed transition of Fe2+; Fe3+ has a minor role due to the fact that all d5 transitions are spin forbidden and ,consequently, very weak. In yellow sapphires Fe is totally in its 3+ valence state. In these cases, the color from yellow to blue, sometimes even within the same sample, depends. on oxidizing or reducing growth conditions. Even if the concentrations of Cr and Ti are very low, their characteristic emissions are the only ones observable down to 10000 cm-1 in radio and photoluminescence spectra. This piece of evidence suggested us to propose for the absorption bands present in the 14000 to 21000 cm-1 range, often attributed to IVCT, the same attribution given to the analogous bands in metamorphic

  12. In Haitian women and preschool children, iron absorption from wheat flour-based meals fortified with sodium iron EDTA is higher than that from meals fortified with ferrous fumarate, and is not affected by Helicobacter pylori infection in children.

    Science.gov (United States)

    Herter-Aeberli, Isabelle; Eliancy, Kerline; Rathon, Yanick; Loechl, Cornelia U; Marhône Pierre, Joseline; Zimmermann, Michael B

    2017-08-01

    Fe fortification of wheat flour was proposed in Haiti to combat Fe deficiency, but Fe bioavailability from fortificants has never been investigated in Haitian women or preschool children, two key target groups. We aimed to investigate the bioavailability of ferrous fumarate (FeFum), NaFeEDTA and their combination from fortified wheat flour. We recruited twenty-two healthy mother-child pairs in Port au Prince, Haiti, for an Fe-absorption study. We administered stable Fe isotopes as FeFum or NaFeEDTA individually in low-extraction wheat flour bread rolls consumed by all participants in a randomised, cross-over design. In a final, identical meal, consumed only by the women, FeFum+NaFeEDTA was administered. We measured Fe absorption by using erythrocyte incorporation of stable isotopes 14 d after consumption of each meal, and determined Fe status, inflammatory markers and Helicobacter pylori infection. Fe absorption (geometric mean was 9·24 (95 % CI 6·35, 13·44) and 9·26 (95 % CI 7·00, 12·31) from FeFum and 13·06 (95 % CI 9·23, 19·10) and 12·99 (95 % CI 9·18, 18·39) from NaFeEDTA in mothers and children, respectively (P<0·05 between compounds). Fe absorption from FeFum+NaFeEDTA was 11·09 (95 % CI 7·45, 17·34) and did not differ from the other two meals. H. pylori infection did not influence Fe absorption in children. In conclusion, in Haitian women and children, Fe absorption from NaFeEDTA was 40 % higher than from FeFum, and the combination FeFum+NaFeEDTA did not significantly increase Fe absorption compared with FeFum alone. In the context of Haiti, where the high costs of NaFeEDTA may not be affordable, the use of FeFum at 60 mg Fe/kg flour may be a preferable, cost-effective fortification strategy.

  13. Predicted profiles of ultraviolet interstellar absorption lines

    Energy Technology Data Exchange (ETDEWEB)

    Welty, D.E.; Hobbs, L.M.; York, D.G. (Chicago, University, IL (USA))

    1991-02-01

    In this paper, values of the column density, line width parameter, and velocity are determined for as many components derived from optical interstellar absorption-line profiles of Na I and K I as needed to reproduce the observed high-resolution optical profiles of the D lines of Na I toward eight lightly reddened stars and of the 7698 A line of K I toward six moderately reddened stars. The derived component structures are then used to predict UV absorption-line profiles due to C I, Mg I, S I, Si I, and Fe I along the same lines of sight. Comparison of the predicted profiles with existing lower resolution line profiles and equivalent width data suggests that this simple scaling procedure can in many cases fairly reliably predict the UV profiles from the observed optical ones. 64 refs.

  14. First-principles Study on Infrared Absorptions of Transition Metal-doped ZnO with Oxygen Vacancy

    Institute of Scientific and Technical Information of China (English)

    Yinhua YAO; Quanxi CAO

    2013-01-01

    Using first-principle theory,the infrared absorptions of transition metal (Mn,Fe,Co,Ni)-doped ZnO were investigated.The results indicate that the absorptions of Mn-and Co-incorporated ZnO without oxygen vacancy are reduced,while those of Fe-and Ni-doped ZnO are raised.This is consistent with the previous experimental results.The effects of oxygen vacancy on the absorptions of the doped systems were predicted.When a neutral oxygen vacancy is introduced,all doping elements decrease the absorptions.On the contrary,the absorptions of the doped systems are enhanced if the vacancies are charged.Degraded absorptions can be obtained by increasing the permeability.However,the appearance of anti-bonding states may cause enhanced absorptions.In the current study,Mn-doped ZnO is the most suitable for use as low infrared absorption materials.

  15. Soliton absorption spectroscopy

    CERN Document Server

    Kalashnikov, V L

    2010-01-01

    We analyze optical soliton propagation in the presence of weak absorption lines with much narrower linewidths as compared to the soliton spectrum width using the novel perturbation analysis technique based on an integral representation in the spectral domain. The stable soliton acquires spectral modulation that follows the associated index of refraction of the absorber. The model can be applied to ordinary soliton propagation and to an absorber inside a passively modelocked laser. In the latter case, a comparison with water vapor absorption in a femtosecond Cr:ZnSe laser yields a very good agreement with experiment. Compared to the conventional absorption measurement in a cell of the same length, the signal is increased by an order of magnitude. The obtained analytical expressions allow further improving of the sensitivity and spectroscopic accuracy making the soliton absorption spectroscopy a promising novel measurement technique.

  16. Absorption heat pump system

    Science.gov (United States)

    Grossman, G.

    1982-06-16

    The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

  17. Zeeman atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Hadeishi, T.; McLaughlin, R.

    1978-08-01

    The design and development of a Zeeman atomic absorption spectrometer for trace element analysis are described. An instruction manual is included which details the operation, adjustment, and maintenance. Specifications and circuit diagrams are given. (WHK)

  18. Temperature dependence of microwave absorption phenomena in single and biphase soft magnetic microwires

    Energy Technology Data Exchange (ETDEWEB)

    El Kammouni, Rhimou, E-mail: elkammounirhimou@gmail.com [Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid (Spain); Vázquez, Manuel [Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid (Spain); Lezama, Luis [Depto. Química Inorgánica, Universidad País Vasco, UPV/EHU, Bilbao (Spain); Kurlyandskaya, Galina [Depto. Electricidad y Electrónica, Universidad País Vasco, UPV/EHU, Bilbao (Spain); Dept. Magnetism and Magnetic Nanomaterials, Ural Federal University, Ekaterinburg (Russian Federation); Kraus, Ludek [Institute of Physics, Academy of Sciences of the Czech Republic, Prague (Czech Republic)

    2014-11-15

    The microwave absorption phenomena of single and biphase magnetic microwires with soft magnetic behavior have been investigated as a function of DC applied magnetic field using two alternative techniques: (i) absorption measurements in the temperature range of 4–300 K using a spectrometer operating at X-band frequency, at 9.5 GHz, and (ii) room-temperature, RT, ferromagnetic resonance measurements in a network analyzer in the frequency range up to 20 GHz. Complementary low-frequency magnetic characterization was performed in a Vibrating Sample Magnetometer. Studies have been performed for 8 μm diameter small-magnetostriction amorphous CoFeSiB single-phase microwire, coated by micrometric Pyrex layer, and after electroplating an external shell, 2 µm or 4 µm thick, of FeNi alloys. For single phase CoFeSiB microwire, a single absorption is observed, whose DC field dependence of resonance frequency at RT fits to a Kittel-law behavior for in-plane magnetized thin film. The temperature dependence behavior shows a monotonic increase in the resonance field, H{sub r}, with temperature. A parallel reduction of the circular anisotropy field, H{sub K}, is deduced from the temperature dependence of hysteresis loops. For biphase, CoFeSiB/FeNi, microwires, the absorption phenomena at RT also follow the Kittel condition. The observed opposite evolution with temperature of resonance field, H{sub r}, in 2 and 4 µm thick FeNi samples is interpreted considering the opposite sign of magnetostriction of the respective FeNi layers. The stress-induced magnetic anisotropy field, H{sub K}, in the FeNi shell is deduced to change sign at around 130 K. - Highlights: • A single absorption phenomenon is observed for single phase CoFeSiB. • The T dependence of the microwave behavior shows a monotonic increase of H{sub r} with T. • The absorption at RT follows the Kittel condition for biphase CoFe/FeNi microwires. • The T dependence of resonant field of CoFe/FeNi is interpreted to be

  19. Revisiting Absorptive Capacity

    DEFF Research Database (Denmark)

    de Araújo, Ana Luiza Lara; Ulhøi, John Parm; Lettl, Christopher

    Absorptive capacity has mostly been perceived as a 'passive' outcome of R&D investments. Recently, however, a growing interest into its 'proactive' potentials has emerged. This paper taps into this development and proposes a dynamic model for conceptualizing the determinants of the complementary...... learning processes of absorptive capacity, which comprise combinative and adaptive capabilities. Drawing on survey data (n=169), the study concludes that combinative capabilities primarily enhance transformative and exploratory learning processes, while adaptive capabilities strengthen all three learning...

  20. Revisiting Absorptive Capacity

    DEFF Research Database (Denmark)

    de Araújo, Ana Luiza Lara; Ulhøi, John Parm; Lettl, Christopher

    Absorptive capacity has mostly been perceived as a 'passive' outcome of R&D investments. Recently, however, a growing interest into its 'proactive' potentials has emerged. This paper taps into this development and proposes a dynamic model for conceptualizing the determinants of the complementary...... learning processes of absorptive capacity, which comprise combinative and adaptive capabilities. Drawing on survey data (n=169), the study concludes that combinative capabilities primarily enhance transformative and exploratory learning processes, while adaptive capabilities strengthen all three learning...

  1. Electronic Properties of LiFePO4 and Li doped LiFePO4

    Energy Technology Data Exchange (ETDEWEB)

    Allen, J.L.; Zhuang, G.V.; Ross, P.N.; Guo, J.-H.; Jow, T.R.

    2006-05-31

    LiFePO{sub 4} has several potential advantages in comparison to the transition metal oxide cathode materials used in commercial lithium-ion batteries. However, its low intrinsic electronic conductivity ({approx} 10{sup -9} S/cm) is problematic. We report here a study by soft x-ray absorption/emission spectroscopy of the electronic properties of undoped LiFePO{sub 4} and Li-doped LiFePO{sub 4} in which Li{sup +} ions are substituted for Fe{sup 2+} ions in an attempt to increase the intrinsic electronic conductivity. The conductivities of the Li{sub 1+x}Fe{sub 1-x}PO{sub 4} samples were, however, essentially unchanged from that of the undoped LiFePO{sub 4}. Nonetheless, evidence for changing the electronic properties of LiFePO{sub 4} by doping with excess Li+ was observed by the XAS/XES spectroscopy. New pre-edge features the O-1s XAS spectrum of Li{sub 1.05}Fe{sub 0.95}PO4 is a direct indication that the charge compensation for substitution of Fe{sup 2+} by Li{sup +} resides in the unoccupied O-2p orbitals. A charge transfer (CT) excitation was also observed in the doped material implying that the unoccupied O-2p orbitals created by doping are strongly hybridized with unoccupied Fe-3d orbitals of neighboring sites. However, the strong covalent bonding within the (PO{sub 4}){sup 3-} anions and the large separation of the Fe cations means that the charge created by doping is not delocalized in the manner of electrons or holes in a semiconductor.

  2. ELECTROMAGNETIC MICROWAVE PROPERTIES OF Fe82B17Cu1 BALL MILLED ALLOY

    Science.gov (United States)

    Tian, N.; Fan, X. D.; Wang, J. W.; You, C. Y.; Lu, Z. X.; Ge, L. L.

    2013-07-01

    High saturation magnetization and magnetic anisotropy are helpful for getting a high frequency electromagnetic microwave absorption performance. The α-Fe possesses a high saturation magnetization. Fe-B phases exhibit a relatively higher magnetic anisotropy and higher resistivity than α-Fe simultaneously. In this work, we made nanocrystalline powders of Fe82B17Cu1, mainly consisting of α-Fe and Fe2B phases, by ball milling and post-annealing. Electromagnetic microwave characterization shows that Fe82B17Cu1 powders possess a relative high permeability and considerable permittivity. Due to a good electromagnetic impedance matching, a good electromagnetic microwave absorption property (RL < -35 dB) has been achieved at 3.6 GHz. The experimental frequency and the matching thickness are coincident with the quarter wavelength matching condition.

  3. Duodenal Absorption and Tissue Utilization of Dietary Heme and Nonheme Iron Differ in Rats123

    Science.gov (United States)

    Cao, Chang; Thomas, Carrie E.; Insogna, Karl L.; O'Brien, Kimberly O.

    2014-01-01

    Background: Dietary heme contributes to iron intake, yet regulation of heme absorption and tissue utilization of absorbed heme remains undefined. Objectives: In a rat model of iron overload, we used stable iron isotopes to examine heme- and nonheme-iron absorption in relation to liver hepcidin and to compare relative utilization of absorbed heme and nonheme iron by erythroid (RBC) and iron storage tissues (liver and spleen). Methods: Twelve male Sprague-Dawley rats were randomly assigned to groups for injections of either saline or iron dextran (16 or 48 mg Fe over 2 wk). After iron loading, rats were administered oral stable iron in the forms of 57Fe-ferrous sulfate and 58Fe-labeled hemoglobin. Expression of liver hepcidin and duodenal iron transporters and tissue stable iron enrichment was determined 10 d postdosing. Results: High iron loading increased hepatic hepcidin by 3-fold and reduced duodenal expression of divalent metal transporter 1 (DMT1) by 76%. Nonheme-iron absorption was 2.5 times higher than heme-iron absorption (P = 0.0008). Absorption of both forms of iron was inversely correlated with hepatic hepcidin expression (heme-iron absorption: r = −0.77, P = 0.003; nonheme-iron absorption: r = −0.80, P = 0.002), but hepcidin had a stronger impact on nonheme-iron absorption (P = 0.04). Significantly more 57Fe was recovered in RBCs (P = 0.02), and more 58Fe was recovered in the spleen (P = 0.01). Conclusions: Elevated hepcidin significantly decreased heme- and nonheme-iron absorption but had a greater impact on nonheme-iron absorption. Differential tissue utilization of heme vs. nonheme iron was evident between erythroid and iron storage tissues, suggesting that some heme may be exported into the circulation in a form different from that of nonheme iron. PMID:25332470

  4. Conflicting Role of Water in the Activation of H2O2 and the Formation and Reactivity of Non-Heme Fe-III-OOH and Fe-III-O-Fe-III Complexes at Room Temperature

    NARCIS (Netherlands)

    Padamati, Sandeep K.; Draksharapu, Apparao; Unjaroen, Duenpen; Browne, Wesley R.

    2016-01-01

    The formation of an Fe-III-OOH species by reaction of complex 1 ([(MeN3Py)Fe-II(CH3CN)(2)](2+)) with H2O2 at room temperature is reported and is studied by a combination of UV/vis absorption, EPR, and resonance Raman spectroscopies. The formation of the Fe-III-OOH species, and its subsequent

  5. Central cooling: absorptive chillers

    Energy Technology Data Exchange (ETDEWEB)

    Christian, J.E.

    1977-08-01

    This technology evaluation covers commercially available single-effect, lithium-bromide absorption chillers ranging in nominal cooling capacities of 3 to 1,660 tons and double-effect lithium-bromide chillers from 385 to 1,060 tons. The nominal COP measured at operating conditions of 12 psig input steam for the single-effect machine, 85/sup 0/ entering condenser water, and 44/sup 0/F exiting chilled-water, ranges from 0.6 to 0.65. The nominal COP for the double-effect machine varies from 1.0 to 1.15 with 144 psig entering steam. Data are provided to estimate absorption-chiller performance at off-nominal operating conditions. The part-load performance curves along with cost estimating functions help the system design engineer select absorption equipment for a particular application based on life-cycle costs. Several suggestions are offered which may be useful for interfacing an absorption chiller with the remaining Integrated Community Energy System. The ammonia-water absorption chillers are not considered to be readily available technology for ICES application; therefore, performance and cost data on them are not included in this evaluation.

  6. Fe2+-Ti4+ vs. Fe2+-Fe3+ charge-transfer and short-range order in single chains of face-sharing octahedra: ellenbergerite and dumortierite

    Science.gov (United States)

    Chopin, C.; Langer, K.; Khomenko, V.

    2009-04-01

    In zoned pyrope megacrysts from the Dora-Maira UHP terrane, new, dark-violet colour varieties of the hexagonal, high-pressure silicate ellenbergerite extend the range of known Fe contents for this mineral from 0-0.1 to 0-0.4 atom pfu, for Ti contents commonly in the range 0.2-0.4 pfu. The new varieties show an extremely intense pleochroism, colourless for E perpendicular to c to deep Prussian blue for E//c, as compared to colourless to lilac or reddish purple for classical Fe-poor ellenbergerite. These features were the incentive for an electronic absorption spectroscopic study and a reappraisal of the interpretation of the charge transfers (CT), colour and ordering schemes in this group and the structurally related borosilicate dumortierite. Both structures are characterized by the presence of infinite single chains of face-sharing, partly vacant octahedra along the 6-fold screw axis and pseudo-hexad axis, respectively, in which the Fe and Ti atoms are partitioned. In the spectra of Fe-poor ellenbergerite, the presence of a single Fe2+-Ti4+ CT band near 19000 cm˘1 was taken as evidence for complete short-range ordering of Mg(Fe), Ti and vacancies in the octahedral single chain [1]. The E//c spectra of Fe-rich ellenbergerite show the same absorption band near 19000 cm˘1 but consistently flanked by another CT band near 14000 cm˘1 , the intensity of which increases with total Fe content. The latter is similar to the 12400 cm˘1 CT band observed as the single feature in E//c spectra of the isotructural (Ti-free and Fe-bearing) phosphoellenbergerite, and clearly assigned to Fe2+-Fe3+ CT in the octahedral single chain [1]. The same colour pattern occurs in the dumortierite group, with red Fe-poor, Ti-rich crystals showing a single CT band near 20000 cm˘1, blue Ti-poor crystals showing a single CT band near 16500 cm˘1, and violet Fe- and Ti-rich crystals showing a combination of the two bands [2]. In the light of the new data, we reinterpret the dumortierite colour

  7. A lactic acid-fermented oat gruel increases non-haem iron absorption from a phytate-rich meal in healthy women of childbearing age

    DEFF Research Database (Denmark)

    Bering, S.; Suchdev, S.; Sjoltov, L.;

    2006-01-01

    Lactic acid-fermented foods have been shown to increase Fe absorption in human subjects, possibly by lowering pH, activation of phytases, and formation of soluble complexes of Fe and organic acids. We tested the effect of an oat gruel fermented with Lactobacillus plantarum 299v on non-haem Fe abs...

  8. Exploring electrosorption at iron electrode with in situ surface-enhanced infrared absorption spectroscopy.

    Science.gov (United States)

    Huo, Sheng-Juan; Wang, Jin-Yi; Yao, Jian-Lin; Cai, Wen-Bin

    2010-06-15

    Surface-enhanced infrared absorption spectroscopy (SEIRAS) in attenuated total reflection (ATR) configuration has been extended to the Fe electrode/electrolyte interface in neutral and weakly acidic solutions for the first time. The SEIRA-active Fe film electrode was obtained through a potentiostatic electrodeposition of a virtually pinhole-free 40 nm-thick Fe overfilm onto a 60 nm-thick Au underfilm chemically predeposited on the reflecting plane of an ATR Si prism. The infrared absorption for CO adlayer at the Fe film electrode measured with ATR-SEIRAS was enhanced by a factor of larger than 34, as compared to that at a Fe bulk electrode with external infrared absorption spectroscopy in the literature. More importantly, the unipolar band shape enabled the reliable determination of the Stark tuning rates of CO adlayer at Fe electrode. In situ ATR-SEIRAS was also applied to study the electrosorption of a typical corrosion inhibitor benzotriazole (BTAH) on Fe electrode as a function of potential, providing additional spectral information at positive potentials in support of the formation of a polymer-like surface complex Fe(II)(m)(BTA)(n) as the corrosion-resistant layer.

  9. Anormalous Optical Absorption in Porous Al_2O3 Host Matrix---Nano-Oxide Particle Nanocomposites

    Science.gov (United States)

    Zhang, Lide; Zhang, Biao; Mo, Chimei

    1996-03-01

    Porous Al_2O3 host matrix---nano-γ-Fe_2O3 particle composites (porous nanocomposite) were prepared by pyrolysis of Fe(NO_3)_39H_2O in porous nano- Al_2O3 matrix at 250^0C. Comparing with simple nanocomposites formed by mixing nano-γ-Fe_2O3 and compacting at room temperature, followed by annealing at 250^0C, the following anomalous optical behaviors were observed: for porous nanocomposite containing 5% Fe_2O_3, the aborption edge shifts obviously from 827nm to 543nm, and with increasing dopping amount of Fe_2O3 from 5% to 70%, blue shift phenomina decreases. Namely, the absorption edge moves from 543nm to 710nm. The mechanism of shift of the absorption edge is discussed.

  10. Neutron absorption constraints on the composition of 4 Vesta

    Science.gov (United States)

    Prettyman, Thomas H.; Mittlefehldt, David W.; Yamashita, Naoyuki; Beck, Andrew W.; Feldman, William C.; Hendricks, John S.; Lawrence, David J.; McCoy, Timothy J.; McSween, Harry Y.; Paplowski, Patrick N.; Reedy, Robert C.; Toplis, Michael J.; Le Corre, Lucille; Mizzon, Hugau; Reddy, Vishnu; Titus, Timothy N.; Raymond, Carol A.; Russell, Christopher T.

    2013-01-01

    Global maps of the macroscopic thermal neutron absorption cross section of Vesta's regolith by the Gamma Ray and Neutron Detector (GRaND) on board the NASA Dawn spacecraft provide constraints on the abundance and distribution of Fe, Ca, Al, Mg, and other rock-forming elements. From a circular, polar low-altitude mapping orbit, GRaND sampled the regolith to decimeter depths with a spatial resolution of about 300 km. At this spatial scale, the variation in neutron absorption is about seven times lower than that of the Moon. The observed variation is consistent with the range of absorption for howardite whole-rock compositions, which further supports the connection between Vesta and the howardite, eucrite, and diogenite meteorites. We find a strong correlation between neutron absorption and the percentage of eucritic materials in howardites and polymict breccias, which enables petrologic mapping of Vesta's surface. The distribution of basaltic eucrite and diogenite determined from neutron absorption measurements is qualitatively similar to that indicated by visible and near infrared spectroscopy. The Rheasilvia basin and ejecta blanket has relatively low absorption, consistent with Mg-rich orthopyroxene. Based on a combination of Fe and neutron absorption measurements, olivine-rich lithologies are not detected on the spatial scales sampled by GRaND. The sensitivity of GRaND to the presence of mantle material is described and implications for the absence of an olivine signature are discussed. High absorption values found in Vesta's “dark” hemisphere, where exogenic hydrogen has accumulated, indicate that this region is richer in basaltic eucrite, representative of Vesta's ancient upper crust.

  11. Neutron absorption constraints on the composition of 4 Vesta

    Science.gov (United States)

    Prettyman, Thomas H.; Mittlefehldt, David W.; Yamashita, Naoyuki; Beck, Andrew W.; Feldman, William C.; Hendricks, John S.; Lawrence, David J.; McCoy, Timothy J.; McSween, Harry Y.; Peplowski, Patrick N.; Reedy, Robert C.; Toplis, Michael J.; Corre, Lucille; Mizzon, Hugau; Reddy, Vishnu; Titus, Timothy N.; Raymond, Carol A.; Russell, Christopher T.

    2013-11-01

    Global maps of the macroscopic thermal neutron absorption cross section of Vesta's regolith by the Gamma Ray and Neutron Detector (GRaND) on board the NASA Dawn spacecraft provide constraints on the abundance and distribution of Fe, Ca, Al, Mg, and other rock-forming elements. From a circular, polar low-altitude mapping orbit, GRaND sampled the regolith to decimeter depths with a spatial resolution of about 300 km. At this spatial scale, the variation in neutron absorption is about seven times lower than that of the Moon. The observed variation is consistent with the range of absorption for howardite whole-rock compositions, which further supports the connection between Vesta and the howardite, eucrite, and diogenite meteorites. We find a strong correlation between neutron absorption and the percentage of eucritic materials in howardites and polymict breccias, which enables petrologic mapping of Vesta's surface. The distribution of basaltic eucrite and diogenite determined from neutron absorption measurements is qualitatively similar to that indicated by visible and near infrared spectroscopy. The Rheasilvia basin and ejecta blanket has relatively low absorption, consistent with Mg-rich orthopyroxene. Based on a combination of Fe and neutron absorption measurements, olivine-rich lithologies are not detected on the spatial scales sampled by GRaND. The sensitivity of GRaND to the presence of mantle material is described and implications for the absence of an olivine signature are discussed. High absorption values found in Vesta's "dark" hemisphere, where exogenic hydrogen has accumulated, indicate that this region is richer in basaltic eucrite, representative of Vesta's ancient upper crust.

  12. An Extreme, Blueshifted Iron-Line Profile in the Narrow-Line Seyfert 1 PG 1402+261: An Edge-on Accretion Disk or Highly Ionized Absorption?

    Science.gov (United States)

    Reeves, J. N.; Porquet, D.; Turner, T. J.

    2004-11-01

    We report on a short XMM-Newton observation of the radio-quiet narrow-line Seyfert 1 galaxy PG 1402+261. The EPIC X-ray spectrum of PG 1402+261 shows a strong excess of counts between 6 and 9 keV in the rest frame. This feature can be modeled by an unusually strong (equivalent width 2 keV) and very broad (FWHM velocity of 110,000 km s-1) iron K-shell emission line. The line centroid energy at 7.3 keV appears blueshifted with respect to the iron Kα emission band between 6.4 and 6.97 keV, while the blue wing of the line extends to 9 keV in the quasar rest frame. The line profile can be fitted by reflection from the inner accretion disk, but an inclination angle of >60° is required to model the extreme blue wing of the line. Furthermore, the extreme strength of the line requires a geometry whereby the hard X-ray emission from PG 1402+261 above 2 keV is dominated by the pure-reflection component from the disk, while little or none of the direct hard power law is observed. Alternatively, the spectrum above 2 keV may be explained by an ionized absorber, if the column density is sufficiently high (NH>3×1023 cm-2) and if the matter is ionized enough to produce a deep (τ~1) iron K-shell absorption edge at 9 keV. This absorber could originate in a large column density, high-velocity outflow, perhaps similar to those that appear to be observed in several other high accretion rate active galactic nuclei. Further observations, especially at higher spectral resolution, are required to distinguish between the accretion disk reflection and outflow scenarios.

  13. Chemical Absorption Materials

    DEFF Research Database (Denmark)

    Thomsen, Kaj

    2011-01-01

    Chemical absorption materials that potentially can be used for post combustion carbon dioxide capture are discussed. They fall into five groups, alkanolamines, alkali carbonates, ammonia, amino acid salts, and ionic liquids. The chemistry of the materials is discussed and advantages and drawbacks...... are mentioned. References to review papers, papers with experimental data, and papers describing the thermodynamic modelling of the systems are given....

  14. Inhibition of iron absorption from human milk by baby food.

    Science.gov (United States)

    Oski, F A; Landaw, S A

    1980-05-01

    We measured the effect of a common baby food, strained pears, on the absorption of iron from human milk. Five adult subjects were initially fed 1 dL of human milk that contained added ferrous citrate Fe 59; the same subjects were later fed human milk and one jar of baby food. Incorporation of 59Fe into RBCs averaged approximately one quarter of the administered iron from the human milk. When the milk was combined with the baby food, incorporation was significantly decreased. The addition of a supplemental food to the diet of the breast-fed infant impairs the bioavailability of the iron from human milk.

  15. Peptide-based FeS4 complexes: the zinc ribbon fold is unsurpassed to stabilize both the FeII and FeIII states.

    Science.gov (United States)

    Jacques, Aurélie; Latour, Jean-Marc; Sénèque, Olivier

    2014-03-14

    Whereas Zn(Cys)4 zinc fingers exist with different protein folds, only the zinc ribbon fold is found in rubredoxin Fe(Cys)4 sites. To assess the significance of this observation, we have investigated the binding and stability of Fe(2+) and Fe(3+) ions by a set of four peptides designed to model Zn(Cys)4 zinc fingers with various folds, i.e. zinc ribbon, treble clef and a loosened zinc ribbon fold. All peptides were shown by means of UV-Vis and CD spectroscopies to form stable 1 : 1 Fe(II)/peptide complexes with binding constants higher than 10(7) M(-1) at pH 7. Their oxidation into Fe(III) complexes and the stability of the latter were compared. The UV-Vis absorption and CD spectroscopic properties of the Fe(II) and Fe(III) complexes were analysed with respect to the structures of the zinc analogues in order to get insight into the local arrangement of the Fe(Cys)4 core around the metal ion. The chemical stability of these complexes was rationalized according to the shielding from the solvent provided by the various peptide folds to the FeS4 core. In addition, we showed that whereas UV-visible spectra inform only on the FeS4, the information derived from the corresponding CD spectra extend to the Cβ orientation and the peptide fold. The results presented here demonstrate that while the zinc ribbon fold is not strictly required to obtain a Fe(Cys)4 site, it affords a drastically superior protection of the site toward external redox agents. This finding brings new clues to engineer stable and redox-active Fe(Cys)4 sites in de novo proteins.

  16. Superconductivity and Properties of FeTeOx Films

    Energy Technology Data Exchange (ETDEWEB)

    D Telesca; j Budnick; B Sinkovic; R Ramprasad; B Wells

    2011-12-31

    Films of the parent compound FeTe can be made superconducting via the addition of interstitial oxygen. The process is reversible. We have characterized the new superconductors with a variety of experiments. X-ray diffraction shows that the superconductor has the same overall structure but a small lattice constant change compared to pure FeTe. X-ray absorption shows that superconducting FeTeO{sub x} has a nominal valence of 3+. DFT calculations show the most likely position for interstitial oxygen and confirm that such oxygen incorporation does not produce a large change in structure.

  17. Controllable synthesis and enhanced microwave absorbing properties of Fe3O4/NiFe2O4/Ni heterostructure porous rods

    Science.gov (United States)

    Li, Yana; Wu, Tong; Jin, Keying; Qian, Yao; Qian, Naxin; Jiang, Kedan; Wu, Wenhua; Tong, Guoxiu

    2016-11-01

    We developed a coordinated self-assembly/precipitate transfer/sintering method that allows the controllable synthesis of Fe3O4/NiFe2O4/Ni heterostructure porous rods (HPRs). A series of characterizations confirms that changing [Ni2+] can effectively control the crystal size, internal strain, composition, textural characteristics, and properties of HPRs. Molar percentages of Ni and NiFe2O4 in HPRs increase with [Ni2+] in various Boltzmann function modes. Saturation magnetization Ms and coercivity Hc show U-shaped change trends because of crystal size, composition, and interface magnetic coupling. High magnetic loss is maintained after decorating NiFe2O4 and Ni on the surface of Fe3O4 PRs. Controlling the NiFe2O4 interface layers and Ni content can improve impedance matching and dielectric losses, thereby leading to lighter weight, stronger absorption, and broader absorption band of Fe3O4/NiFe2O4/Ni HPRs than Fe3O4 PRs. An optimum EM wave absorbing property was exhibited by Fe3O4/NiFe2O4/Ni HPRs formed at [Ni2+] = 0.05 M. The maximum reflection loss (RL) reaches -58.4 dB at 13.68 GHz, which corresponds to a 2.1 mm matching thickness. The absorbing bandwidth (RL ≤ -20 dB) reaches 14.4 GHz with the sample thickness at 1.6-2.4 and 2.8-10.0 mm. These excellent properties verify that Fe3O4/NiFe2O4/Ni HPRs are promising candidates for new and effective absorptive materials.

  18. Effect of thermal treatment in vacuum on Fe-doped SnO{sub 2} powders

    Energy Technology Data Exchange (ETDEWEB)

    Bilovol, V. [Laboratorio de Solidos Amorfos, INTECIN, Facultad de Ingenieria, Universidad de Buenos Aires, Paseo Colon 850, C1063ACV Buenos Aires (Argentina); Mudarra Navarro, A.M.; Rodriguez Torres, C.E. [Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, IFLP-CCT La Plata, CONICET (Argentina); Cabrera, A.F., E-mail: cabrera@fisica.unlp.edu.ar [Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, IFLP-CCT La Plata, CONICET (Argentina)

    2012-08-15

    A sample of 10 at% Fe-doped SnO{sub 2} powder was prepared by mechanical alloying and then thermally treated at 773 K in vacuum. The fit of the diffraction patterns and X-ray absorption spectroscopy measurements revealed that the as milled sample was pure doped rutile. Fe dissolved into SnO{sub 2} was found in Fe{sup 2+}/Fe{sup 3+} ionic valence with mainly paramagnetic behavior. After the thermal treatment all techniques indicate the formation of the ternary Sn{sub 0.36}Fe{sub 2.64}O{sub 4} spinel phase, which is responsible for the observed ferromagnetism.

  19. Redox interactions between Fe and cysteine: Spectroscopic studies and multiplet calculations

    Science.gov (United States)

    Bhattacharyya, Amrita; Stavitski, Eli; Dvorak, Joseph; Martínez, Carmen Enid

    2013-12-01

    The biogeochemical cycle of Fe is intricately linked with that of organic matter. Cysteine represents an organic molecule with functionalities (O, S, N functional groups) and a C backbone that may mimic the functional groups present in organic matter from terrestrial and aquatic environments. In the present study we explore the redox speciation and coordination environment of Fe and the roles of the various ligand atoms of cysteine (C, N, S) in iron-organic redox coupling and transformations. The changes in oxidation state of Fe, C, N, and S in laboratory-synthesized Fe(II)-cysteine (synthesized from ferrous sulfate) and Fe(III)-cysteine (synthesized from ferric nitrate) complexes are monitored as a function of time using synchrotron X-ray absorption spectroscopy (Fe L2,3-edge XANES; C, N and S K-edge XANES; Fe K-edge EXAFS) and theoretical multiplet calculations using the program CTM4XAS (Charge Transfer Multiplet for X-ray Absorption Spectroscopy). CTM4XAS calculations show that 80% of the total Fe in both the Fe(II)-cysteine and the Fe(III)-cysteine complexes is present as Fe2+ initially (t = 0), thus indicating preservation of Fe(II) in Fe(II)-cysteine and reduction of Fe(III) in Fe(III)-cysteine at initial conditions, the latter caused by an internal electron transfer reaction from S of -SH on the cysteine molecule. After 12 months, however, ∼60% of the total Fe is present as Fe3+ in the Fe(II)-cysteine complex whereas ∼67% of the total Fe is present as Fe2+ in the Fe(III)-cysteine complex. The fact that a larger proportion of the Fe in the Fe(III)-cysteine complex remained reduced after 12 months than that in the Fe(II)-cysteine complex suggests that the reduced Fe in Fe(III)-cysteine after 12 months is further stabilized via preferential binding with the donor atoms of cysteine. Stabilization via preferential binding is supported by a coordination environment that changed from tetrahedral Fe2+ binding to S at a distance of 2.3 Å at t = 0 for both Fe

  20. Enhanced microwave absorption properties and mechanism of core/shell structured magnetic nanoparticles/carbon-based nanohybrids

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Xiaosi, E-mail: sci.xsqi@gzu.edu.cn [Physics Department, Guizhou University, Guiyang 550025 (China); Nanjing National Laboratory of Microstructures and Jiangsu Provincial Laboratory for NanoTechnology, Nanjing University, Nanjing 210093 (China); Hu, Qi; Xu, Jianle; Xie, Ren; Bai, Zhongchen; Jiang, Yang; Qin, Shuijie [Physics Department, Guizhou University, Guiyang 550025 (China); Zhong, Wei, E-mail: wzhong@nju.edu.cn [Nanjing National Laboratory of Microstructures and Jiangsu Provincial Laboratory for NanoTechnology, Nanjing University, Nanjing 210093 (China); Du, Youwei [Nanjing National Laboratory of Microstructures and Jiangsu Provincial Laboratory for NanoTechnology, Nanjing University, Nanjing 210093 (China)

    2016-09-15

    Graphical abstract: In the article, core/shell Fe{sub 3}O{sub 4}/C, Fe/helical carbon nanotubes were synthesized selectively. The results indicated that the optimum reflection loss (RL) could reach −47.1 dB at 17.39 GHz with a matching thickness of 1.39 mm. The absorption bandwidth with the RL below −20 dB was up to 11.59 GHz. Moreover, based on the obtained results, the possibly enhanced microwave absorption mechanisms were also discussed in detail. - Highlights: • An efficient scheme was designed to synthesize core/shell magnetic nanoparticles/carbon-based hybrids. • By controlling the temperature, different categories of core/shell nanohybrids were synthesized. • The obtained Fe/CNT hybrid exhibits enhanced microwave absorption property. • Enhanced microwave absorbing mechanism was discussed in detail. - Abstract: An efficient scheme was designed to selectively synthesize different categories of core/shell structured magnetic nanoparticles/carbon-based nanohybrids such as Fe{sub 3}O{sub 4}/C and Fe/helical carbon nanotubes (HCNTs) through the decomposition of acetylene directly over Fe{sub 2}O{sub 3} nanotubes by controlling the pyrolysis temperature. The measured electromagnetic parameters indicated that the Fe/HCNT nanohybrids exhibited enhanced microwave absorption properties, which may be related to their special structures. The optimum reflection loss (RL) could reach −47.1 dB at 17.39 GHz with a matching thickness of 1.39 mm. The absorption bandwidth with the RL values below −20 dB was up to 11.59 GHz. Moreover, based on the obtained results, the possible enhanced EM absorption mechanisms were also discussed in detail. The results show excellent microwave absorption materials that are lightweight, have strong absorption and a wide absorption frequency band may be realized in these nanohybrids.

  1. In situ measurement of ferric iron in lunar glass beads using Fe-XAS

    Science.gov (United States)

    McCanta, Molly C.; Dyar, M. Darby; Rutherford, Malcolm J.; Lanzirotti, Antonio; Sutton, Stephen R.; Thomson, Bradley J.

    2017-03-01

    Through use of a new X-ray Absorption Spectroscopy (XAS) calibration for Fe3+ analysis in silicate glasses, the first direct measurements of ferric iron in natural lunar picritic glasses are presented. Lunar glass beads from the Apollo sample collection contain up to 60.0% Fe3+. No correlation with melt chemical properties, such as Mg# or weight % TiO2, or physical properties, such as bead diameter, was observed. Fe3+/ΣFe is negatively correlated with NBO/T. These elevated Fe3+/ΣFe values reflect eruption and post-eruption oxidation due to magmatic degassing of H or OH. Glass beads observed to be zoned to lower Fe3+/ΣFe rims may represent a subsequent reduction in the lunar vacuum prior to cooling through the glass transition temperature.

  2. In situ measurement of ferric iron in lunar glass beads using Fe-XAS

    Energy Technology Data Exchange (ETDEWEB)

    McCanta, Molly C.; Dyar, M. Darby; Rutherford, Malcolm J.; Lanzirotti, Antonio; Sutton, Stephen R.; Thomson, Bradley J.

    2017-03-01

    Through use of a new X-ray Absorption Spectroscopy (XAS) calibration for Fe3+ analysis in silicate glasses, the first direct measurements of ferric iron in natural lunar picritic glasses are presented. Lunar glass beads from the Apollo sample collection contain up to 60.0% Fe3+. No correlation with melt chemical properties, such as Mg# or weight % TiO2, or physical properties, such as bead diameter, was observed. Fe3+Fe is negatively correlated with NBO/T. These elevated Fe3+Fe values reflect eruption and post-eruption oxidation due to magmatic degassing of H or OH. Glass beads observed to be zoned to lower Fe3+Fe rims may represent a subsequent reduction in the lunar vacuum prior to cooling through the glass transition temperature.

  3. Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages.

    Science.gov (United States)

    Hurrell, R F; Reddy, M; Cook, J D

    1999-04-01

    The effects of different polyphenol-containing beverages on Fe absorption from a bread meal were estimated in adult human subjects from the erythrocyte incorporation of radio-Fe. The test beverages contained different polyphenol structures and were rich in either phenolic acids (chlorogenic acid in coffee), monomeric flavonoids (herb teas, camomile (Matricaria recutita L.), vervain (Verbena officinalis L.), lime flower (Tilia cordata Mill.), pennyroyal (Mentha pulegium L.) and peppermint (Mentha piperita L.), or complex polyphenol polymerization products (black tea and cocoa). All beverages were potent inhibitors of Fe absorption and reduced absorption in a dose-dependent fashion depending on the content of total polyphenols. Compared with a water control meal, beverages containing 20-50 mg total polyphenols/serving reduced Fe absorption from the bread meal by 50-70%, whereas beverages containing 100-400 mg total polyphenols/serving reduced Fe absorption by 60-90%. Inhibition by black tea was 79-94%, peppermint tea 84%, pennyroyal 73%, cocoa 71%, vervain 59%, lime flower 52% and camomile 47%. At an identical concentration of total polyphenols, black tea was more inhibitory than cocoa, and more inhibitory than herb teas camomile, vervain, lime flower and pennyroyal, but was of equal inhibition to peppermint tea. Adding milk to coffee and tea had little or no influence on their inhibitory nature. Our findings demonstrate that herb teas, as well as black tea, coffee and coca can be potent inhibitors of Fe absorption. This property should be considered when giving dietary advice in relation to Fe nutrition.

  4. Iron and Nickel Line Diagnostics for the Galactic Center Diffuse Emission

    CERN Document Server

    Koyama, K; Inui, T; Nakajima, H; Matsumoto, H; Tsuru, T G; Takahashi, T; Maeda, Y; Yamazaki, N; Murakami, H; Yamauchi, S; Tsuboi, Y; Senda, A; Kataoka, J; Takahashi, H; Holt, S S; Brown, G V; Koyama, Katsuji; Hyodo, Yoshiaki; Inui, Tatsuya; Nakajima, Hiroshi; Matsumoto, Hironori; Tsuru, Takeshi Go; Takahashi, Tadayuki; Maeda, Yoshitomo; Yamazaki, Noriko; Murakami, Hiroshi; Yamauchi, Shigeo; Tsuboi, Yohko; Senda, Atsushi; Kataoka, Jun; Takahashi, Hiromitsu; Holt, Stephen S; Brown, Gregory V

    2006-01-01

    We have observed the diffuse X-ray emission from the Galactic center (GC) using the X-ray Imaging Spectrometer (XIS) on Suzaku. The high-energy resolution and the low-background orbit provide excellent spectra of the GC diffuse X-rays (GCDX). The XIS found many emission lines in the GCDX near the energy of K-shell transitions of iron and nickel. The most pronounced features are FeI K alpha at 6.4 keV and K-shell absorption edge at 7.1 keV, which are from neutral and/or low ionization states of iron, and the K-shell lines at 6.7 keV and 6.9 keV from He-like (FeXXV K alpha) and hydrogenic (FeXXVI Ly alpha) ions of iron. In addition, K alpha lines from neutral or low ionization nickel (NiI K alpha) and He-like nickel (NiXXVII K alpha), and FeI K beta, FeXXV K beta, FeXXVI Ly beta, FeXXV K gamma and FeXXVI Ly gamma are detected for the first time. The line center energies and widths of FeXXV K alpha and FeXXVI Ly alpha favor a collisional excitation (CE) plasma for the origin of the GCDX. The electron temperature...

  5. Preparation and photo-catalytic activities of FeOOH/ZnO/MMT composite

    Science.gov (United States)

    Zhou, Yao; Liu, Fusheng; Yu, Shitao

    2015-11-01

    Montmorillonite (MMT) was used as the carrier for synthesis of FeOOH and FeOOH/ZnO nano-material. FeOOH and FeOOH/ZnO were synthesized by the aqueous solutions of Fe(NO3)3-HNO3 and Zn(NO3)2-NaOH/Fe(NO3)3-HNO3 with the carrier of montmorillonite respectively. Transmission electron-microscopy (TEM) and X-ray diffraction (XRD) were used to study the morphology form and structure of the nano-materials. TEM was also used to demonstrate that FeOOH/ZnO can be formed with the appropriate interface. According to UV-vis absorption spectra, FeOOH/ZnO has a better response to visible light than FeOOH and ZnO, which indicates there is some coupling effect between FeOOH and ZnO. Pentachlorophenol (PCP) was used as a representative organic pollutant to evaluate the photo-catalytic efficiency of the FeOOH/ZnO and FeOOH catalysts in visible light (λ > 400 nm). The photo-catalytic efficiency of FeOOH/ZnO/MMT is better than FeOOH/MMT. According to FTIR, changes of pH and TOC, the degradation mechanism was also discussed. PCP was degraded to aromatic ketone and chloro-hydrocarbon compounds and then to H2O, CO2 and HCl.

  6. Lead adsorption study on combustion derived -Fe2O3 surface

    Indian Academy of Sciences (India)

    Arunkumar Lagashetty; H Vijayanand; S Basavaraja; N N Mallikarjuna; A Venkataraman

    2010-02-01

    New combustion synthetic route for the synthesis of nanosized -Fe2O3 by microwave-assisted route is reported. X-ray density, tap density and powder density of prepared -Fe2O3 are calculated. Adsorption study of Pb2+ on combustion derived nanosized -Fe2O3 is studied by dynamic method. The -Fe2O3 structure and lead adsorbed -Fe2O3 (Pb--Fe2O3) are studied by X-ray diffraction (XRD). Additional lead peaks in Pb--Fe2O3 sample pattern confirm the lead adsorption. Morphology of as prepared -Fe2O3 and Pb--Fe2O3 is studied by scanning electron micrograph (SEM) technique. Varied morphology for Pb--Fe2O3 compared to its -Fe2O3 is observed. Variation of bonding in Pb--Fe2O3 sample due to lead adsorption is viewed by infrared spectroscopic (IR) technique. Energy dispersive X-ray microanalysis (EDX) is scanned for the lead adsorbed -Fe2O3 to know the presence of lead on -Fe2O3 surface. The eluent lead solution is characterized by atomic absorption spectroscopy (AAS) and solution conductivity (SC). Reduction in the concentration and increase in conductance of eluent lead solution is observed. The potential use of solid adsorbents for the adsorption of heavy metal pollutants is envisaged in the present work.

  7. Acoustic absorption by sunspots

    Science.gov (United States)

    Braun, D. C.; Labonte, B. J.; Duvall, T. L., Jr.

    1987-01-01

    The paper presents the initial results of a series of observations designed to probe the nature of sunspots by detecting their influence on high-degree p-mode oscillations in the surrounding photosphere. The analysis decomposes the observed oscillations into radially propagating waves described by Hankel functions in a cylindrical coordinate system centered on the sunspot. From measurements of the differences in power between waves traveling outward and inward, it is demonstrated that sunspots appear to absorb as much as 50 percent of the incoming acoustic waves. It is found that for all three sunspots observed, the amount of absorption increases linearly with horizontal wavenumber. The effect is present in p-mode oscillations with wavelengths both significantly larger and smaller than the diameter of the sunspot umbrae. Actual absorption of acoustic energy of the magnitude observed may produce measurable decreases in the power and lifetimes of high-degree p-mode oscillations during periods of high solar activity.

  8. Chaotic systems with absorption

    CERN Document Server

    Altmann, Eduardo G; Tél, Tamás

    2013-01-01

    Motivated by applications in optics and acoustics we develop a dynamical-system approach to describe absorption in chaotic systems. We introduce an operator formalism from which we obtain (i) a general formula for the escape rate $\\kappa$ in terms of the natural conditionally-invariant measure of the system; (ii) an increased multifractality when compared to the spectrum of dimensions $D_q$ obtained without taking absorption and return times into account; and (iii) a generalization of the Kantz-Grassberger formula that expresses $D_1$ in terms of $\\kappa$, the positive Lyapunov exponent, the average return time, and a new quantity, the reflection rate. Simulations in the cardioid billiard confirm these results.

  9. Galactic Outflows in Absorption and Emission: Near-UV Spectroscopy of Galaxies at 1

    CERN Document Server

    Erb, Dawn K; Henry, Alaina L; Martin, Crystal L

    2012-01-01

    We study large-scale outflows in a sample of 96 star-forming galaxies at 1FeII and MgII absorption and emission. The average blueshift of the FeII interstellar absorption lines with respect to the systemic velocity is -85+/-10 km/s at z~1.5, with standard deviation 87 km/s; this is a decrease of a factor of two from the average blueshift measured for far-UV interstellar absorption lines in similarly selected galaxies at z~2. The profiles of the MgII 2796, 2803 lines show much more variety than the FeII profiles, which are always seen in absorption; MgII ranges from strong emission to pure absorption, with emission more common in galaxies with blue UV slopes and at lower stellar masses. Outflow velocities, as traced by the centroids and maximum extent of the absorption lines, increase with increasing stellar mass with 2-3sigma significance, in agreement with previous results. We study fine structure emission from FeII*, finding several lines of evidence in support of t...

  10. Spin and orbital magnetic moments of Fe in the n-type ferromagnetic semiconductor (In,Fe)As

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, M., E-mail: masakik@post.kek.jp; Oshima, M. [Department of Applied Chemistry, School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Synchrotron Radiation Research Organization, University of Tokyo, 1-490-2 Kouto, Sayo-cho, Tatsuno, Hyogo 679-5165 (Japan); Anh, L. D.; Hai, P. N.; Tanaka, M. [Department of Electrical Engineering and Information Systems, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Takeda, Y.; Okane, T.; Saitoh, Y.; Yamagami, H. [Synchrotron Radiation Research Unit, Japan Atomic Energy Agency, Sayo-gun, Hyogo 679-5148 (Japan); Sakamoto, S.; Kadono, T.; Fujimori, A. [Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Harada, Y. [Synchrotron Radiation Research Organization, University of Tokyo, 1-490-2 Kouto, Sayo-cho, Tatsuno, Hyogo 679-5165 (Japan); Institute for Solid State Physics, The University of Tokyo, 1-1-1 Koto, Sayo, Hyogo 679-5198 (Japan)

    2014-07-21

    The electronic and magnetic properties of Fe atoms in the ferromagnetic semiconductor (In,Fe)As codoped with Be have been studied by x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) at the Fe L{sub 2,3} edge. The XAS and XMCD spectra showed simple spectral line shapes similar to Fe metal, but the ratio of the orbital and spin magnetic moments (M{sub orb}/M{sub spin}) estimated using the XMCD sum rules was significantly larger than that of Fe metal, indicating a significant orbital moment of Fe 3d electrons in (In,Fe)As:Be. The positive value of M{sub orb}/M{sub spin} implies that the Fe 3d shell is more than half-filled, which arises from the hybridization of the Fe{sup 3+} (d{sup 5}) state with the charge-transfer d{sup 6}L{sub ¯} states, where L{sub ¯} is a ligand hole in the host valence band. The XMCD intensity as a function of magnetic field indicated hysteretic behavior of the superparamagnetic-like component due to discrete ferromagnetic domains.

  11. Nano-structure analysis of Fe implanted SnO2 films by 57Fe and 119Sn CEMS

    Science.gov (United States)

    Nomura, Kiyoshi; Reuther, Helfried

    2009-06-01

    SnO2 films were implanted with 57Fe at substrate temperatures of room temperature and 300°C. The chemical states of Fe and Sn were characterized by 57Fe CEMS and 119Sn CEMS, respectively. The implanted Fe species exist as Fe(II) and Fe(III) in SnO2 films, which also are reduced into Sn(II)on the implanted surface. The as prepared and post annealed at 500°C samples did not show Kerr effect, but the sample implanted with 1 × 1017 Fe ions/cm2 at 300°C showed Kerr effect although magnetic sextets were not clearly observed in the 57Fe CEM spectra. The Kerr effect disappeared after annealing. It suggests that the number of magnetic defects decreases by absorption of oxygen. Magnetic relaxation appeared in the case of low implantation of 5 × 1016 Fe ions/cm2, which is considered to be due to anti-ferromagnetism or paramagnetic relaxation.

  12. Photoinduced absorption of polyalkylthienylenevinylenes

    Energy Technology Data Exchange (ETDEWEB)

    Botta, C. (Ist. di Chimica delle Macromolecole (CNR), Milano (Italy)); Bradley, D.D.C. (Cambridge Univ. (United Kingdom). Cavendish Lab.); Friend, R.H. (Cambridge Univ. (United Kingdom). Cavendish Lab.); Musco, A. (Ist. di Scienze Chimiche, Univ. di Urbino (Italy))

    1993-03-15

    We present a photoinduced absorption study of alkyl substituted poly(2,5-thienylenevinylene)s. Three photoinduced states are detected in both the solid state and in solution. The two low-energy bands are assigned to bipolarons, while a third band peaked near the band edge has a different origin. In solution photoexcitated states are very long-lived and we propose that photoexcitation recombine via a solvent-assisted photo-doping mechanism. (orig.)

  13. Hydrogen Absorption by Niobium.

    Science.gov (United States)

    1982-04-13

    incorporate an independent means for ascertaining surface cleanliness (e.g. AES). The form of the absorption curve in Fig. 7 appears to agree with that...very interesting study and is well within the capabilities of the systen designed, if the surface cleanliness can be assured. Wire specimens have a...assessing surface cleanliness would be an important supporting technique for understanding the results of these measurements. The simple kinetic

  14. Fe(II) sorption on pyrophyllite: Effect of structural Fe(III) (impurity) in pyrophyllite on nature of layered double hydroxide (LDH) secondary mineral formation

    Energy Technology Data Exchange (ETDEWEB)

    Starcher, Autumn N.; Li, Wei; Kukkadapu, Ravi K.; Elzinga, Evert J.; Sparks, Donald L.

    2016-11-01

    Fe(II)-Al(III)-LDH (layered double hydroxide) phases have been shown to form from reactions of aqueous Fe(II) with Fe-free Al-bearing minerals (phyllosilicate/clays and Al-oxides). To our knowledge, the effect of small amounts of structural Fe(III) impurities in “neutral” clays on such reactions, however, were not studied. In this study to understand the role of structural Fe(III) impurity in clays, laboratory batch studies with pyrophyllite (10 g/L), an Al-bearing phyllosilicate, containing small amounts of structural Fe(III) impurities and 0.8 mM and 3 mM Fe(II) (both natural and enriched in 57Fe) were carried out at pH 7.5 under anaerobic conditions (4% H2 – 96% N2 atmosphere). Samples were taken up to 4 weeks for analysis by Fe-X-ray absorption spectroscopy and 57Fe Mössbauer spectroscopy. In addition to the precipitation of Fe(II)-Al(III)-LDH phases as observed in earlier studies with pure minerals (no Fe(III) impurities in the minerals), the analyses indicated formation of small amounts of Fe(III) containing solid(s), most probably hybrid a Fe(II)-Al(III)/Fe(III)-LDH phase. The mechanism of Fe(II) oxidation was not apparent but most likely was due to interfacial electron transfer from the sorbed Fe(II) to the structural Fe(III) and/or surface-sorption-induced electron-transfer from the sorbed Fe(II) to the clay lattice. Increase in the Fe(II)/Al ratio of the LDH with reaction time further indicated the complex nature of the samples. This research provides evidence for the formation of both Fe(II)-Al(III)-LDH and Fe(II)-Fe(III)/Al(III)-LDH-like phases during reactions of Fe(II) in systems that mimic the natural environments. Better understanding Fe phase formation in complex laboratory studies will improve models of natural redox systems.

  15. Preparation of Fe-Doped TiO2 Nanotubes and Their Photocatalytic Activities under Visible Light

    OpenAIRE

    Honghui Teng; Shukun Xu; Dandan Sun; Ying Zhang

    2013-01-01

    Fe-doped TiO2 nanotubes (Fe-TNTs) have been prepared by ultrasonic-assisted hydrothermal method. The structure and composition of the as-prepared TiO2 nanotubes were characterized by transmission electron microscopy, X-ray diffraction, and UV-Visible absorption spectroscopy. Their photocatalytic activities were evaluated by the degradation of MO under visible light. The UV-visible absorption spectra of the Fe-TNT showed a red shift and an enhancement of the absorption in the visible region co...

  16. Exogenous EBR mediated the plant growth and absorption and accumulation of Cu, Fe and Zn in tomato seedlings under Cu stress%外源油菜素内酯介导Cu胁迫下番茄生长及Cu、Fe、Zn的吸收与分配

    Institute of Scientific and Technical Information of China (English)

    尹博; 梁国鹏; 贾文; 崔秀敏

    2014-01-01

    As an essential element and a heavy metal, copper (Cu) occurs in various vital movements and metabolic processes of plant. In previous industrial and agricultural production, excess Cu2+or Cu compounds were frequently intentionally or unintentio-nally discharged into the environment. In some polluted soils, Cu content exceeded ten times the original content of the soil. This led to fatal damages to plant growth and food security, and thus developing new phytoremediation pathways were imperative. Our early studies showed that exogenous 2,4-epibrassinolide (EBR) alleviated Cu stress and increased Cu accumulation in tomato seedlings.‘Gailiang Maofen 802F1’ was used as the plant material to explore the alleviation mechanism of EBR on tomato seedlings under Cu stress. Through nutrient solution cultivation in greenhouse conditions, we investigated the effects of EBR on tomato growth and mineral elements contents under Cu stress. The results showed that exogenous EBR effectively alleviated growth strains induced by Cu stress. 50 µmol·L-1 of CuCl2 obviously restrained tomato growth and increased Cu content in tomato seedlings. Compared with seedlings exposed to Cu stress, 0.1 mg·L-1 of exogenous EBR effectively increased leaf chlorophyll content and plant biomass respectively by 39.6%and 20.0%. Under Cu stress, exogenous EBR observably reduced Cu absorption and transport, simultaneously increasing contents of iron (Fe) and zinc (Zn) in roots. EBR efficiently regulated different chemical forms and Cu, Fe, Zn distributions among subcellular organelles and reduced Cu biotoxicity in cells. This was helpful to the normal growth of tomato and ensured regular physiological and biochemical metabolism of roots and leaves. Cu stress increased contents of different chemical species of Cu in tomato leaves and root. Addition of EBR under Cu stress increased contents of all forms of Cu except NaCl extracted Cu in leaf, compared with Cu stress. Proportion of movable Cu increased

  17. Charge redistribution and a shortening of the Fe--As bond at the quantum critical point of SmO1-xFxFeAs.

    Science.gov (United States)

    Cheng, Jie; Dong, Peng; Xu, Wei; Liu, Shengli; Chu, Wangsheng; Chen, Xianhui; Wu, Ziyu

    2015-07-01

    Many researchers have pointed out that there is a quantum critical point (QCP) in the F-doped SmOFeAs system. In this paper, the electronic structure and local structure of the superconductive FeAs layer in SmO(1-x)FxFeAs as a function of the F-doping concentration have been investigated using Fe and As K-edge X-ray absorption spectroscopy. Experiments performed on the X-ray absorption near-edge structure showed that in the vicinity of the QCP the intensity of the pre-edge feature at the Fe-edge decreases continuously, while there is a striking rise of the shoulder-peak at the As edge, suggesting the occurrence of charge redistribution near the QCP. Further analysis on the As K-edge extended X-ray absorption fine structure demonstrated that the charge redistribution originates mostly from a shortening of the Fe-As bond at the QCP. An evident relationship between the mysterious QCP and the fundamental Fe-As bond was established, providing new insights on the interplay between QCP, charge dynamics and the local structural Fe-As bond in Fe-based superconductors.

  18. Corrosion Problems in Absorption Chillers

    Science.gov (United States)

    Stetson, Bruce

    1978-01-01

    Absorption chillers use a lithium bromide solution as the medium of absorption and water as the refrigerant. Discussed are corrosion and related problems, tests and remedies, and cleaning procedures. (Author/MLF)

  19. Converting Sabine absorption coefficients to random incidence absorption coefficients

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2013-01-01

    Absorption coefficients measured by the chamber method are referred to as Sabine absorption coefficients, which sometimes exceed unity due to the finite size of a sample and non-uniform intensity in the reverberation chambers under test. In this study, conversion methods from Sabine absorption...... coefficients to random incidence absorption coefficients are proposed. The overestimations of the Sabine absorption coefficient are investigated theoretically based on Miki's model for porous absorbers backed by a rigid wall or an air cavity, resulting in conversion factors. Additionally, three optimizations...

  20. Acoustic Absorption Characteristics of People.

    Science.gov (United States)

    Kingsbury, H. F.; Wallace, W. J.

    1968-01-01

    The acoustic absorption characteristics of informally dressed college students in typical classroom seating are shown to differ substantially from data for formally dressed audiences in upholstered seating. Absorption data, expressed as sabins per person or absorption coefficient per square foot, shows that there is considerable variation between…

  1. BONDLENGTH ALTERNATION OF NANOPARTICLES Fe2O3 COATED WITH ORGANIC SURFACTANTS PROBED BY EXAFS

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The nanoparticles γ-Fe2O3 coated with surfactants.DBS,ST and CTAB.repsectively.were synthesized by microemulsion method.The coated ferric oxides.which show enhanced nonlinear optical properties compared with their bulk counterpart.were probed by EXAFS in solution forms.The x=-ray absorption spectra for Fe K edge were measured at room temperature by help of synchrotron radiation light source.Extended x-ray absorption fine structure analysis shows that the coating layers of organic molecules interact with surface atoms of nanopartices,the Fe-O bond length was extended.

  2. Acceleration of the Fe(III)EDTA(-) reduction rate in BioDeNO(x) reactors by dosing electron mediating compounds

    NARCIS (Netherlands)

    Maas, van der P.M.F.; Brink, van den P.; Klapwijk, A.; Lens, P.N.L.

    2009-01-01

    BioDeNO(x), a novel technique to remove NOx from industrial flue gases, is based on absorption of gaseous nitric oxide into an aqueous Fe(II)EDTA(2-) solution, followed by the biological reduction of Fe(II)EDTA(2-) complexed NO to N-2. Besides NO reduction, high rate biological Fe(III)EDTA(-) reduct

  3. Acceleration of the Fe(III)EDTA(-) reduction rate in BioDeNO(x) reactors by dosing electron mediating compounds

    NARCIS (Netherlands)

    Maas, van der P.M.F.; Brink, van den P.; Klapwijk, A.; Lens, P.N.L.

    2009-01-01

    BioDeNO(x), a novel technique to remove NOx from industrial flue gases, is based on absorption of gaseous nitric oxide into an aqueous Fe(II)EDTA(2-) solution, followed by the biological reduction of Fe(II)EDTA(2-) complexed NO to N-2. Besides NO reduction, high rate biological Fe(III)EDTA(-)

  4. Absorption in dielectric models

    CERN Document Server

    Churchill, R J

    2015-01-01

    We develop a classical microscopic model of a dielectric. The model features nonlinear interaction terms between polarizable dipoles and lattice vibrations. The lattice vibrations are found to act as a pseudo-reservoir, giving broadband absorption of electromagnetic radiation without the addition of damping terms in the dynamics. The effective permittivity is calculated using a perturbative iteration method and is found to have the form associated with real dielectrics. Spatial dispersion is naturally included in the model and we also calculate the wavevector dependence of the permittivity.

  5. Geospatial Absorption and Regional Effects

    Directory of Open Access Journals (Sweden)

    IOAN MAC

    2009-01-01

    Full Text Available The geospatial absorptions are characterized by a specific complexity both in content and in their phenomenological and spatial manifestation fields. Such processes are differentiated according to their specificity to pre-absorption, absorption or post-absorption. The mechanisms that contribute to absorption are extremely numerous: aggregation, extension, diffusion, substitution, resistivity (resilience, stratification, borrowings, etc. Between these mechanisms frequent relations are established determining an amplification of the process and of its regional effects. The installation of the geographic osmosis phenomenon in a given territory (a place for example leads to a homogenization of the geospatial state and to the installation of the regional homogeneity.

  6. Absorption Spectra of Astaxanthin Aggregates

    CERN Document Server

    Olsina, Jan; Minofar, Babak; Polivka, Tomas; Mancal, Tomas

    2012-01-01

    Carotenoids in hydrated polar solvents form aggregates characterized by dramatic changes in their absorption spectra with respect to monomers. Here we analyze absorption spectra of aggregates of the carotenoid astaxanthin in hydrated dimethylsulfoxide. Depending on water content, two types of aggregates were produced: H-aggregates with absorption maximum around 390 nm, and J-aggregates with red-shifted absorption band peaking at wavelengths >550 nm. The large shifts with respect to absorption maximum of monomeric astaxanthin (470-495 nm depending on solvent) are caused by excitonic interaction between aggregated molecules. We applied molecular dynamics simulations to elucidate structure of astaxanthin dimer in water, and the resulting structure was used as a basis for calculations of absorption spectra. Absorption spectra of astaxanthin aggregates in hydrated dimethylsulfoxide were calculated using molecular exciton model with the resonance interaction energy between astaxanthin monomers constrained by semi-e...

  7. The HI absorption 'Zoo'

    CERN Document Server

    Gereb, K; Morganti, R; Oosterloo, T A

    2014-01-01

    We present an analysis of the HI absorption in a sample of 101 flux-selected radio AGN (S_1.4 GHz > 50 mJy) observed with the Westerbork Synthesis Radio Telescope (WSRT). HI absorption is detected in 32 galaxies, showing a broad variety of widths, shapes and kinematical properties. We characterize the HI spectra of the individual detections using the busy function (Westmeier et al. 2014). With the goal of identifying different morphological structures of HI, we study the kinematical and radio source properties of the detections as function of their width. Narrow lines (FWHM = 500 km/s). These detections are good candidates for being HI outflows. The detection rate of HI outflows is 5 percent in the total radio AGN sample. This fraction represents a lower limit, however it could suggests that, if outflows are a characteristic phenomenon of all radio sources, they would have a short depletion timescale compared to the lifetime of the AGN. Blueshifted and broad/asymmetric lines are more often present among young...

  8. Speciative Determination of Dissolved Inorganic Fe(II, Fe(III and Total Fe in Natural Waters by Coupling Cloud Point Extraction with FAAS

    Directory of Open Access Journals (Sweden)

    Ramazan GÜRKAN

    2013-12-01

    Full Text Available A new cloud point extraction (CPE method for the preconcentration of trace iron speciation in natural waters prior to determination by flame atomic absorption spectrometry (FAAS was developed in the present study. In this method, Fe(II sensitively and selectively reacts with Calcon carboxylic acid (CCA in presence of cetylpyridinium chloride (CPC yielding a hydrophobic complex at pH 10.5, which is then entrapped in surfactant-rich phase. Total Fe was accurately and reliably determined after the reduction of Fe(III to Fe(II with sulfite. The amount of Fe(III in samples was determined from the difference between total Fe and Fe(II. CPC was used not only as an auxiliary ligand in CPE, but also as sensitivity enhancement agent in FAAS. The nonionic surfactant, polyethylene glycol tert-octylphenyl ether (Triton X-114 was used as an extracting agent. The analytical variables affecting CPE efficiency were investigated in detail. The preconcentration/enhancement factors of 50 and 82 respectively, were obtained for the preconcentration of Fe(II with 50 mL solution. Under the optimized conditions, the detection limit of Fe(II in linear range of 0.2-60 μg L-1 was 0.06 μg L-1. The relative standard deviation was 2.7 % (20 μg L-1, N: 5, recoveries for Fe(II were in range of 99.0-102.0% for all water samples including certified reference materials (CRMs. In order to verify its accuracy, two CRMs were analyzed and the results obtained were statistically in good agreement with the certified values.

  9. Absorption of Arsenite on Several Iron (Hydro-)Oxides and Impact from Pre-processing Methods

    Institute of Scientific and Technical Information of China (English)

    YE Ying; JI Shanshan; WU Daidai; LI Jun; ZHANG Weirui

    2006-01-01

    The absorption reactions of arsenite on Fe (hydro-)oxides are studied. The three absorbent types are Fe(OH)3 gel and two Fe (hydro-)oxides, in which the Fe(OH)3 gel was dried in a microwave oven under vacuum at 80℃. It is found that pH changes from 9.71 to 10.36 in 6 minutes after the Fe (OH)3 gel was mixed with NaAsO2 solution, as the arsenite replaces the OH- in goethite and Fe(OH)3.At the 40th minute after the start of the reaction, pH decreases, which is most probably because that the monodentate surface complex of absorbed arsenite has changed into mononuclear-bidentate complex and released proton. The decline in pH values indicates not the end of the absorption but a change in the reaction type. Temperature and dissolved gas has little effect on these two types of reactions. The total absorption of arsenite increases after the absorbent is irradiated with ultrasound, which also lead to difficulty in separating the solids from solution. The absorption capacity for arsenite of Fe(OH)3 gel dried in a microwave oven under vacuum is 53.18% and 17.22% respectively better than that of Fe (OH)3 gel and gel dried at 80℃. The possible reasons are that the water molecules in the gel vibrates with high frequency under the effect of microwave irradiation, thereby producing higher porosity and improved surface activity.

  10. Bioavailability of iron in geophagic earths and clay minerals, and their effect on dietary iron absorption using an in vitro digestion/Caco-2 cell model.

    Science.gov (United States)

    Seim, Gretchen L; Ahn, Cedric I; Bodis, Mary S; Luwedde, Flavia; Miller, Dennis D; Hillier, Stephen; Tako, Elad; Glahn, Raymond P; Young, Sera L

    2013-08-01

    Geophagy, the deliberate consumption of earth, is strongly associated with iron (Fe) deficiency. It has been proposed that geophagy may be practiced as a means to improve Fe status by increasing Fe intakes and, conversely, that geophagy may cause Fe deficiency by inhibiting Fe absorption. We tested these hypotheses by measuring Fe concentration and relative bioavailable Fe content of 12 samples of geophagic earth and 4 samples of pure clay minerals. Further, we assessed the impact of these samples on the bioavailability of Fe from an Fe-rich test meal (cooked white beans, WB). Fe concentrations were measured with inductively coupled plasma atomic emission spectroscopy. Fe bioavailability was determined using an in vitro digestion/Caco-2 cell model in which ferritin formation was used as an index of Fe bioavailability. Geophagic earth and clay mineral samples were evaluated with this model, both alone and in combination with WB (1 : 16 ratio, sample : WB). Median Fe concentration of the geophagic earth was 3485 (IQR 2462, 14 ,571) μg g⁻¹ and mean Fe concentration in the clay minerals was 2791 (±1782) μg g⁻¹. All specimens had Fe concentrations significantly higher (p ≤ 0.005) than the Fe concentration of WB (77 μg g⁻¹). Ferritin formation (i.e. Fe uptake) in cells exposed to geophagic earths and clay minerals was significantly lower than in cells exposed to WB (p ≤ 0.05) and Fe uptake responses of 11 of the 16 samples were not significantly different from the blank, indicating no bioavailable Fe. When samples were combined with WB, 5 of 16 had mean ferritin levels that were significantly lower (p ≤ 0.05, one tail) than the WB alone, indicating that the samples inhibited Fe uptake from the WB. None of the ferritin responses of cells exposed to both WB and earth/clay were significantly higher than WB alone. Thus, although geophagic earths and mineral clays are high in total Fe, very little of this Fe is bioavailable. Further, some

  11. Speciation of iron (II) and (III) by using solvent extraction and flame atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Yaman, Mehmet [Department of Chemistry, Science and Arts Faculty, Firat University, Elazig (Turkey)]. E-mail: myaman@firat.edu.tr; Kaya, Gokce [Department of Chemistry, Science and Arts Faculty, Firat University, Elazig (Turkey)

    2005-05-17

    A method for speciation, preconcentration and separation of Fe{sup 2+} and Fe{sup 3+} in different matrices was developed using solvent extraction and flame atomic absorption spectrometry. PAN as complexing reagent for Fe{sup 2+} and chloroform as organic solvent were used. The complex of Fe{sup 2+}-PAN was extracted into chloroform phase in the pH range of 0.75-4.0 and Fe{sup 3+} remains in water phase in the pH range 0.75-1.25. The optimum conditions for maximum recovery of Fe{sup 2+} and minimum recovery of Fe{sup 3+} were determined as pH = 1, the stirring time of 20 min, the PAN amount of 0.5 mg and chloroform volume of 8 mL. The developed method was applied to the determination of Fe{sup 2+} and Fe{sup 3+} in tea infusion, fruit juice, cola and pekmez. It is seen that there is high bioavailable iron (Fe{sup 2+}) in pekmez. The developed method is sensitive, simple and need the shorter time in comparison with other similar studies.

  12. Zinc absorption from micronutrient powder is low but is not affected by iron in Kenyan infants.

    Science.gov (United States)

    Esamai, Fabian; Liechty, Edward; Ikemeri, Justus; Westcott, Jamie; Kemp, Jennifer; Culbertson, Diana; Miller, Leland V; Hambidge, K Michael; Krebs, Nancy F

    2014-12-01

    Interference with zinc absorption is a proposed explanation for adverse effects of supplemental iron in iron-replete children in malaria endemic settings. We examined the effects of iron in micronutrient powder (MNP) on zinc absorption after three months of home fortification with MNP in maize-based diets in rural Kenyan infants. In a double blind design, six-month-old, non-anemic infants were randomized to MNP containing 5 mg zinc, with or without 12.5 mg of iron (MNP + Fe and MNP − Fe, respectively); a control (C) group received placebo powder. After three months, duplicate diet collections and zinc stable isotopes were used to measure intake from MNP + non-breast milk foods and fractional absorption of zinc (FAZ) by dual isotope ratio method; total absorbed zinc (TAZ, mg/day) was calculated from intake × FAZ. Mean (SEM) TAZ was not different between MNP + Fe (n = 10) and MNP - Fe (n = 9) groups: 0.85 (0.22) and 0.72 (0.19), respectively, but both were higher than C (n = 9): 0.24 (0.03) (p = 0.04). Iron in MNP did not significantly alter zinc absorption, but despite intakes over double estimated dietary requirement, both MNP groups' mean TAZ barely approximated the physiologic requirement for age. Impaired zinc absorption may dictate need for higher zinc doses in vulnerable populations.

  13. Zinc Absorption from Micronutrient Powder Is Low but Is not Affected by Iron in Kenyan Infants

    Directory of Open Access Journals (Sweden)

    Fabian Esamai

    2014-12-01

    Full Text Available Interference with zinc absorption is a proposed explanation for adverse effects of supplemental iron in iron-replete children in malaria endemic settings. We examined the effects of iron in micronutrient powder (MNP on zinc absorption after three months of home fortification with MNP in maize-based diets in rural Kenyan infants. In a double blind design, six-month-old, non-anemic infants were randomized to MNP containing 5 mg zinc, with or without 12.5 mg of iron (MNP + Fe and MNP − Fe, respectively; a control (C group received placebo powder. After three months, duplicate diet collections and zinc stable isotopes were used to measure intake from MNP + non-breast milk foods and fractional absorption of zinc (FAZ by dual isotope ratio method; total absorbed zinc (TAZ, mg/day was calculated from intake × FAZ. Mean (SEM TAZ was not different between MNP + Fe (n = 10 and MNP − Fe (n = 9 groups: 0.85 (0.22 and 0.72 (0.19, respectively, but both were higher than C (n = 9: 0.24 (0.03 (p = 0.04. Iron in MNP did not significantly alter zinc absorption, but despite intakes over double estimated dietary requirement, both MNP groups’ mean TAZ barely approximated the physiologic requirement for age. Impaired zinc absorption may dictate need for higher zinc doses in vulnerable populations.

  14. Zinc Absorption from Micronutrient Powder Is Low but Is not Affected by Iron in Kenyan Infants

    Science.gov (United States)

    Esamai, Fabian; Liechty, Edward; Ikemeri, Justus; Westcott, Jamie; Kemp, Jennifer; Culbertson, Diana; Miller, Leland V.; Hambidge, K. Michael; Krebs, Nancy F.

    2014-01-01

    Interference with zinc absorption is a proposed explanation for adverse effects of supplemental iron in iron-replete children in malaria endemic settings. We examined the effects of iron in micronutrient powder (MNP) on zinc absorption after three months of home fortification with MNP in maize-based diets in rural Kenyan infants. In a double blind design, six-month-old, non-anemic infants were randomized to MNP containing 5 mg zinc, with or without 12.5 mg of iron (MNP + Fe and MNP − Fe, respectively); a control (C) group received placebo powder. After three months, duplicate diet collections and zinc stable isotopes were used to measure intake from MNP + non-breast milk foods and fractional absorption of zinc (FAZ) by dual isotope ratio method; total absorbed zinc (TAZ, mg/day) was calculated from intake × FAZ. Mean (SEM) TAZ was not different between MNP + Fe (n = 10) and MNP − Fe (n = 9) groups: 0.85 (0.22) and 0.72 (0.19), respectively, but both were higher than C (n = 9): 0.24 (0.03) (p = 0.04). Iron in MNP did not significantly alter zinc absorption, but despite intakes over double estimated dietary requirement, both MNP groups’ mean TAZ barely approximated the physiologic requirement for age. Impaired zinc absorption may dictate need for higher zinc doses in vulnerable populations. PMID:25493942

  15. Magnetite-Bridged Carbon Nanotubes/Graphene Sheets Three-Dimensional Network with Excellent Microwave Absorption

    Science.gov (United States)

    Wei, Renbo; Wang, Jialing; Wang, Zicheng; Tong, Lifen; Liu, Xiaobo

    2017-04-01

    A series of three-dimensional carbon nanotubes/graphene sheets network bridged by magnetite (Fe3O4-CNT/GS) is fabricated by solvothermal reaction and used as microwave absorption materials. Phthalonitrile-functionalized CNT (CNT-CN) and graphene oxide (GO-CN) are prepared by reacting acidulated CNT and GO with isophorone diisocyanate and 3-aminophenoxyphthalonitrile. The Fe3O4-CNT/GS is then obtained by the solvothermal reaction from CNT-CN and GO-CN with FeCl3·6H2O. Fe3O4-CNT/GS is characterized by x-ray photoelectron spectroscopic, x-ray diffraction and vibrating sample magnetometer, and its three-dimensional structure is confirmed by scanning electron microscope observation. Due to the formation of three-dimensional nano-architecture and the proper ratio of CNT and GS, the obtained Fe3O4-CNT/GS shows excellent microwave absorption with the minimum reflection loss as high as -45.3 dB at a thickness of 2.5 mm and a bandwidth below -10 dB of 3.8 GHz at a thickness of 1.5 mm. This Fe3O4-CNT/GS material will be a potential candidate as a microwave absorption material.

  16. Fe + N Noncompensated Codoping TiO2 Nanowires: The Enhanced Visible Light Photocatalytic Properties

    Directory of Open Access Journals (Sweden)

    Zhongpo Zhou

    2014-01-01

    Full Text Available The Fe + N codoped nanowire samples are prepared by hydro-thermal method and annealed in NH3 atmosphere. The XRD (X-ray diffraction, SEM (Scanning electron microscope, UV-vis absorption spectroscopy, and BET (Brunauer, Emmett, and Teller results indicate that the samples are pure anatase nanowires. The Fe + N codoped samples have the highest specific surface area, the largest red-shift, and the largest absorption enhancement in the visible light range compared with Fe doped, N doped, and undoped nanowires. The measurements of XPS (X-ray photoelectron spectroscopy show that N content of Fe + N codoped TiO2 is about two times as large as that of the N doped TiO2. It is assumed that nitrogen doping plays a very important role for the photocatalytic activity increase and hence the Fe + N codoped nanowire TiO2 shows the most effective photocatalytic activity under the visible light irradiation.

  17. Photocatalytic Degradation of Nox Under Visible Light Irradiation Using Fe-Doped Titanium Dioxide

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In order to utilize visible light in photocatalytic conversion of NOx, Fe atoms were doped in commercially available photocatalytic TiO2 powders by impregnating method.The crystal phase of TiO2 was not changed after calcination process. Analysis by both X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) indicated that Fe atoms were incorporated in TiO2 as Ti-O-Fe linkages. One significant shift of the absorption edge to a Iower energy and a higher absorption in the visible light region were observed. The Fe-doped TiO2 powder exhibited photocatalytic activity for the degradation of NOx under visible light irradiation. The sample mixed with 0.2 at% Fe3+ and calcined at 600 ℃ showed the best photocatalytic activity.

  18. Room-temperature ferromagnetism in Fe-doped In2O3 nanoparticles

    Science.gov (United States)

    Wongsaprom, Kwanruthai; Sonsupap, Somchai; Maensiri, Santi; Kidkhunthod, Pinit

    2015-10-01

    Nanoparticles of Fe-doped In2O3 [(In1- x Fe x )2O3, 0 ≤ x ≤ 0.10] are prepared by a simple polymerized complex method using indium (III) nitrate hydrate, iron (III) nitrate nonahydrate and polyvinyl pyrrolidone as the starting materials. The XRD, Raman and electron diffraction analysis results indicated that the calcined samples have the cubic structure of In2O3. An X-ray absorption spectroscopy including X-ray absorption near-edge spectroscopy is used in order to address both qualitative and quantitative of doped Fe valence states. The undoped sample exhibits a diamagnetic behavior, whereas all the Fe-doped samples are ferromagnetic having the magnetizations of ~0.0019-0.2959 emu/g at 10 kOe. Our results indicate that room-temperature ferromagnetism of Fe-doped In2O3 system is intrinsic and is not a result of any ferromagnetic impurity phases.

  19. Absorption of manganese and iron in a mouse model of hemochromatosis.

    Directory of Open Access Journals (Sweden)

    Jonghan Kim

    Full Text Available Hereditary hemochromatosis, an iron overload disease associated with excessive intestinal iron absorption, is commonly caused by loss of HFE gene function. Both iron and manganese absorption are regulated by iron status, but the relationships between the transport pathways of these metals and how they are affected by HFE-associated hemochromatosis remain poorly understood. Loss of HFE function is known to alter the intestinal expression of DMT1 (divalent metal transporter-1 and Fpn (ferroportin, transporters that have been implicated in absorption of both iron and manganese. Although the influence of HFE deficiency on dietary iron absorption has been characterized, potential effects on manganese metabolism have yet to be explored. To investigate the role of HFE in manganese absorption, we characterized the uptake and distribution of the metal in Hfe (-/- knockout mice after intravenous, intragastric, and intranasal administration of (54Mn. These values were compared to intravenous and intragastric administration of (59Fe. Intestinal absorption of (59Fe was increased and clearance of injected (59Fe was also increased in Hfe(-/- mice compared to controls. Hfe (-/- mice displayed greater intestinal absorption of (54Mn compared to wild-type Hfe(+/+ control mice. After intravenous injection, the distribution of (59Fe to heart and liver was greater in Hfe (-/- mice but no remarkable differences were observed for (54Mn. Although olfactory absorption of (54Mn into blood was unchanged in Hfe (-/- mice, higher levels of intranasally-instilled (54Mn were associated with Hfe(-/- brain compared to controls. These results show that manganese transport and metabolism can be modified by HFE deficiency.

  20. Modeling thermodynamics of Fe-N phases; characterisation of e-Fe2N1-z

    DEFF Research Database (Denmark)

    Pekelharing, M.I.; Böttger, A.; Somers, Marcel A.J.

    1999-01-01

    In order to arrive at modeling the thermodynamics of Fe-N phases, including long-range (LRO) and short-range ordering (SRO) of the N atoms, it is important to understand the role of N interstitially dissolved in an Fe-host lattice. The crystal structure of -Fe2N1-z consists of an h.c.p. iron...... sublattice and a hexagonal nitrogen sublattice formed by octahedral interstices of the Fe sublattice [1]. Two ground-state structures have been proposed for the ordered arrangement of the N atoms on their own sublattice [1], which were shown to be thermodynamically favourable [2]: configuration A for Fe2N1...... investigated with X-ray diffraction (XRD) and Mössbauer spectroscopy. A thermodynamic model accounting for the two configurations of LRO of the N atoms [2,3] was fitted to the N-absorption isotherm at 723 K and resulted in the occupancies of the sites of the nitrogen sublattice. A miscibility gap between...

  1. Sabine absorption coefficients to random incidence absorption coefficients

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2014-01-01

    Absorption coefficients measured by the chamber method are referred to as Sabine absorption coefficients, which sometimes exceed unity due to the finite size of a specimen and non-uniform intensity in the test chamber. In this study, several methods that convert Sabine absorption coefficients...... into random incidence absorption coefficients for porous absorbers are investigated. Two optimization-based conversion methods are suggested: the surface impedance estimation for locally reacting absorbers and the flow resistivity estimation for extendedly reacting absorbers. The suggested conversion methods...

  2. Charge density study of two FeS2 polymorphs

    DEFF Research Database (Denmark)

    Schmøkel, Mette Stokkebro; Jørgensen, Mads Ry Vogel; Bjerg, Lasse

    Experimental charge density studies of inorganic solids have proven to be a difficult task due to systematic errors related to data collection such as absorption and extinction; however, the use of synchrotron radiation has the potential to minimize these problems. [1] One of the pioneering...... experimental electron density studies of an inorganic solid containing a transition metal was presented by Stevens et al. [2] who investigated the effect of crystal-field splitting of the partially filled iron d-orbitals in the pyrite structure of FeS2. Other studies of various FeS2 structures, including...... pyrite, has been performed by Gibbs et al. [3], however, these are all based on theoretical calculations rather than experiment. In the current study we revisit FeS2 through an experimental charge density study of the two low-spin iron FeS2 structures, pyrite and marcasite. High-quality, low...

  3. Standardization of (55)Fe by tracing method.

    Science.gov (United States)

    Koskinas, M F; Pires, C A; Yamazaki, I M; Silva, E A; Dias, M S

    2008-01-01

    This work describes the procedure followed by the Laboratório de Metrologia Nuclear (LMN) for the standardization of (55)Fe by the tracing method. This technique was applied using two radionuclides, which decay by the electron capture process followed by a prompt gamma-ray, namely (51)Cr and (54)Mn, as tracers. The calibration was performed in a 4pibeta-gamma coincidence system. The efficiency was obtained by selecting a gamma-ray window set at the 320keV total absorption peak for (51)Cr and at 834keV for (54)Mn.

  4. Diffuse interstellar absorption bands

    Institute of Scientific and Technical Information of China (English)

    XIANG FuYuan; LIANG ShunLin; LI AiGen

    2009-01-01

    The diffuse interstellar bands (DIBs) are a large number of absorption bands that are superposed on the interstellar extinction curve and are of interstellar origin. Since the discovery of the first two DIBs in the 1920s, the exact nature of DIBs still remains unclear. This article reviews the history of the detec-tions of DIBs in the Milky Way and external galaxies, the major observational characteristics of DIBs, the correlations or anti-correlations among DIBs or between DIBs and other interstellar features (e.g. the prominent 2175 Angstrom extinction bump and the far-ultraviolet extinction rise), and the proposed candidate carriers. Whether they are also present in circumstellar environments is also discussed.

  5. Diffuse interstellar absorption bands

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The diffuse interstellar bands(DIBs) are a large number of absorption bands that are superposed on the interstellar extinction curve and are of interstellar origin. Since the discovery of the first two DIBs in the 1920s,the exact nature of DIBs still remains unclear. This article reviews the history of the detections of DIBs in the Milky Way and external galaxies,the major observational characteristics of DIBs,the correlations or anti-correlations among DIBs or between DIBs and other interstellar features(e.g. the prominent 2175 Angstrom extinction bump and the far-ultraviolet extinction rise),and the proposed candidate carriers. Whether they are also present in circumstellar environments is also discussed.

  6. The HI absorption "Zoo"

    Science.gov (United States)

    Geréb, K.; Maccagni, F. M.; Morganti, R.; Oosterloo, T. A.

    2015-03-01

    We present an analysis of the H I 21 cm absorption in a sample of 101 flux-selected radio AGN (S1.4 GHz> 50 mJy) observed with the Westerbork Synthesis Radio Telescope (WSRT). We detect H I absorption in 32 objects (30% of the sample). In a previous paper, we performed a spectral stacking analysis on the radio sources, while here we characterize the absorption spectra of the individual detections using the recently presented busy function. The H I absorption spectra show a broad variety of widths, shapes, and kinematical properties. The full width half maximum (FWHM) of the busy function fits of the detected H I lines lies in the range 32 km s-1 200 km s-1). We study the kinematical and radio source properties of each group, with the goal of identifying different morphological structures of H I. Narrow lines mostly lie at the systemic velocity and are likely produced by regularly rotating H I disks or gas clouds. More H I disks can be present among galaxies with lines of intermediate widths; however, the H I in these sources is more unsettled. We study the asymmetry parameter and blueshift/redshift distribution of the lines as a function of their width. We find a trend for which narrow profiles are also symmetric, while broad lines are the most asymmetric. Among the broadest lines, more lines appear blueshifted than redshifted, similarly to what was found by previous studies. Interestingly, symmetric broad lines are absent from the sample. We argue that if a profile is broad, it is also asymmetric and shifted relative to the systemic velocity because it is tracing unsettled H I gas. In particular, besides three of the broadest (up to FW20 = 825 km s-1) detections, which are associated with gas-rich mergers, we find three new cases of profiles with blueshifted broad wings (with FW20 ≳ 500 km s-1) in high radio power AGN. These detections are good candidates for being HI outflows. Together with the known cases of outflows already included in the sample (3C 293 and

  7. Preparation of Fe-Doped TiO2 Nanotubes and Their Photocatalytic Activities under Visible Light

    Directory of Open Access Journals (Sweden)

    Honghui Teng

    2013-01-01

    Full Text Available Fe-doped