Science.gov

Sample records for 48ti 54cr 56fe

  1. The 31- level in 56 Fe

    NASA Astrophysics Data System (ADS)

    Fotiades, N.; Devlin, M.; Nelson, R. O.

    2015-04-01

    The question whether the 3076.2-keV, (3-), or the 4509.6 keV, 3-, is the first 3- level in 56 Fe is important for reaction model calculations. The inclusion in the databases of the 3076.2-keV level will be discussed. A work by using the 56 Fe(n,n' γ) reaction and fast neutrons from a reactor, reported that the 3076.2-keV state does not exist and triggered the present work, where γ- γ coincidence data in 56 Fe, which are more definitive, were recorded with the GEANIE spectrometer comprised of 26 high-purity Ge detectors. The pulsed beam of the Los Alamos Neutron Science Center's WNR facility provided fast neutrons impinging on a 56 Fe target. As we reported in, our experiment supported the assignment of the 4509.6 keV level as the first 3- state, with no observation in the gated spectra of the two transitions that were reported to decay out of the 3076.2-keV level by. A plan to repeat the (p, γ) reaction that reported the observation of these two transitions will be discussed.

  2. 54-Cr Anomalies in the Orgueil Carbonaceous Chondrite

    NASA Astrophysics Data System (ADS)

    Podosek, F. A.; Ott, U.; Brannon, J. C.; Bernatowicz, T. J.; Neal, C. R.

    1995-09-01

    Cr in CI meteorites displays isotopic anomalies in a unique pattern [1-3]. Etching of bulk Orgueil in relatively mild reactants (CH3COOH and dilute HNO3) dissolves most (>80%) of the Cr along with most of other major cations (Mg, Ca, Fe, Ni, Al). The Cr thus dissolved is deficient in 54Cr by about 6 epsilon-units (using 50Cr/52Cr normalization). Much of the remaining Cr is released in further etching in HCl; this Cr has stronger excesses of 54Cr, up to around 100epsilon. Dissolution of the residues in more aggressive reactants yields Cr with smaller excesses of 54Cr. There are no known correlating anomalies in other elements or even in 53Cr. Although no Cr carrier in Orgueil has isotopically normal Cr, mass balance calculations indicate approximately normal Cr in the whole rock. We have previously suggested that these results could be most simply explained by postulating one carrier phase, relatively rich in Cr and bearing strong excess 54Cr, presumably from neutron-rich nuclear statistical equilibrium nucleosynthesis. This phase would have to be soluble in HCl but resistant to parent body aqueous alteration. In this interpretation the 54Cr-deficiency in most of the Cr is understandable in terms of mixing of all the nucleosnthetic sources contributing to solar normal except for that in the postulated carrier phase. Qualitatively similar but more subdued isotopic effects occur in CM meteorites and are very subdued or absent in CV and CO meteorites[1]. If the parent bodies for these classes originally contained the same postulated phase in comparable abundance, the implication is that the 54Cr-enriched carrier phase is also not resistant to the thermal processing experienced by these classes. Interstellar grains bearing Cr from specific nucleosynthetic events would be expected to be much more anomalous than any samples yet observed; we thus lack evidence to determine whether the carrier is itself a type of interstellar grain (in which case all observations to date

  3. Accelerated Hematopoietic Toxicity by High Energy 56Fe Radiation

    PubMed Central

    Datta, Kamal; Suman, Shubhankar; Trani, Daniela; Doiron, Kathryn; Rotolo, Jimmy A.; Kallakury, Bhaskar V. S.; Kolesnick, Richard; Cole, Michael F.; Fornace, Albert J.

    2013-01-01

    Purpose There is little information on the relative toxicity of highly charged (Z) high-energy (HZE) radiation in animal models compared to γ or x-rays, and the general assumption based on in vitro studies has been that acute toxicity is substantially greater. Methods C57BL/6J mice were irradiated with 56Fe ions (1 GeV/nucleon), and acute (within 30 d) toxicity compared to that of γ rays or protons (1 GeV). To assess relative hematopoietic and gastrointestinal toxicity, the effects of 56Fe ions were compared to γ rays using complete blood count (CBC), bone marrow granulocyte-macrophage colony forming unit (GM-CFU), terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay for apoptosis in bone marrow, and intestinal crypt survival. Results Although onset was more rapid, 56Fe ions were only slightly more toxic than γ rays or protons with lethal dose (LD)50/30 (a radiation dose at which 50% lethality occurs at 30-day) values of 5.8, 7.25, and 6.8 Gy respectively with relative biologic effectiveness for 56Fe ions of 1.25 and 1.06 for protons. Conclusions 56Fe radiation caused accelerated and more severe hematopoietic toxicity. Early mortality correlated with more profound leukopenia and subsequent sepsis. Results indicate that there is selective enhanced toxicity to bone marrow progenitor cells, which are typically resistant to γ rays, and bone marrow stem cells, because intestinal crypt cells did not show increased HZE toxicity. PMID:22077279

  4. Cognitive deficits induced by 56Fe radiation exposure

    NASA Technical Reports Server (NTRS)

    Shukitt-Hale, B.; Casadesus, G.; Cantuti-Castelvetri, I.; Rabin, B. M.; Joseph, J. A.

    2003-01-01

    Exposing rats to particles of high energy and charge (e.g., 56Fe) disrupts neuronal systems and the behaviors mediated by them; these adverse behavioral and neuronal effects are similar to those seen in aged animals. Because cognition declines with age, and our previous study showed that radiation disrupted Morris water maze spatial learning and memory performance, the present study used an 8-arm radial maze (RAM) to further test the cognitive behavioral consequences of radiation exposure. Control rats or rats exposed to whole-body irradiation with 1.0 Gy of 1 GeV/n high-energy 56Fe particles (delivered at the alternating gradient synchrotron at Brookhaven National Laboratory) were tested nine months following exposure. Radiation adversely affected RAM performance, and the changes seen parallel those of aging. Irradiated animals entered baited arms during the first 4 choices significantly less than did controls, produced their first error sooner, and also tended to make more errors as measured by re-entries into non-baited arms. These results show that irradiation with high-energy particles produces age-like decrements in cognitive behavior that may impair the ability of astronauts to perform critical tasks during long-term space travel beyond the magnetosphere. Published by Elsevier Science Ltd on behalf of COSPAR.

  5. Cognitive deficits induced by 56Fe radiation exposure

    NASA Astrophysics Data System (ADS)

    Shukitt-Hale, B.; Casadesus, G.; Cantuti-Castelvetri, I.; Rabin, B. M.; Joseph, J. A.

    Exposing rats to particles of high energy and charge (e.g., 56Fe) disrupts neuronal systems and the behaviors mediated by them; these adverse behavioral and neuronal effects are similar to those seen in aged animals. Because cognition declines with age, and our previous study showed that radiation disrupted Morris water maze spatial learning and memory performance, the present study used an 8-arm radial maze (RAM) to further test the cognitive behavioral consequences of radiation exposure. Control rats or rats exposed to whole-body irradiation with 1.0 Gy of 1 GeV/n high-energy 56Fe particles (delivered at the alternating gradient synchrotron at Brookhaven National Laboratory) were tested nine months following exposure. Radiation adversely affected RAM performance, and the changes seen parallel those of aging. Irradiated animals entered baited arms during the first 4 choices significantly less than did controls, produced their first error sooner, and also tended to make more errors as measured by re-entries into non-baited arms. These results show that irradiation with high-energy particles produces age-like decrements in cognitive behavior that may impair the ability of astronauts to perform critical tasks during long-term space travel beyond the magnetosphere.

  6. Cognitive deficits induced by 56Fe radiation exposure.

    PubMed

    Shukitt-Hale, B; Casadesus, G; Cantuti-Castelvetri, I; Rabin, B M; Joseph, J A

    2003-01-01

    Exposing rats to particles of high energy and charge (e.g., 56Fe) disrupts neuronal systems and the behaviors mediated by them; these adverse behavioral and neuronal effects are similar to those seen in aged animals. Because cognition declines with age, and our previous study showed that radiation disrupted Morris water maze spatial learning and memory performance, the present study used an 8-arm radial maze (RAM) to further test the cognitive behavioral consequences of radiation exposure. Control rats or rats exposed to whole-body irradiation with 1.0 Gy of 1 GeV/n high-energy 56Fe particles (delivered at the alternating gradient synchrotron at Brookhaven National Laboratory) were tested nine months following exposure. Radiation adversely affected RAM performance, and the changes seen parallel those of aging. Irradiated animals entered baited arms during the first 4 choices significantly less than did controls, produced their first error sooner, and also tended to make more errors as measured by re-entries into non-baited arms. These results show that irradiation with high-energy particles produces age-like decrements in cognitive behavior that may impair the ability of astronauts to perform critical tasks during long-term space travel beyond the magnetosphere.

  7. Elastic and inelastic scattering of neutrons from 56Fe

    NASA Astrophysics Data System (ADS)

    Ramirez, Anthony Paul; McEllistrem, M. T.; Liu, S. H.; Mukhopadhyay, S.; Peters, E. E.; Yates, S. W.; Vanhoy, J. R.; Harrison, T. D.; Rice, B. G.; Thompson, B. K.; Hicks, S. F.; Howard, T. J.; Jackson, D. T.; Lenzen, P. D.; Nguyen, T. D.; Pecha, R. L.

    2015-10-01

    The differential cross sections for elastic and inelastic scattered neutrons from 56Fe have been measured at the University of Kentucky Accelerator Laboratory (www.pa.uky.edu/accelerator) for incident neutron energies between 2.0 and 8.0 MeV and for the angular range 30° to 150°. Time-of-flight techniques and pulse-shape discrimination were employed for enhancing the neutron energy spectra and for reducing background. An overview of the experimental procedures and data analysis for the conversion of neutron yields to differential cross sections will be presented. These include the determination of the energy-dependent detection efficiencies, the normalization of the measured differential cross sections, and the attenuation and multiple scattering corrections. Our results will also be compared to evaluated cross section databases and reaction model calculations using the TALYS code. This work is supported by grants from the U.S. Department of Energy-Nuclear Energy Universities Program: NU-12-KY-UK-0201-05, and the Donald A. Cowan Physics Institute at the University of Dallas.

  8. Magnesium and 54Cr isotope compositions of carbonaceous chondrite chondrules - Insights into early disk processes

    NASA Astrophysics Data System (ADS)

    Olsen, Mia B.; Wielandt, Daniel; Schiller, Martin; Van Kooten, Elishevah M. M. E.; Bizzarro, Martin

    2016-10-01

    We report on the petrology, magnesium isotopes and mass-independent 54Cr/52Cr compositions (μ54Cr) of 42 chondrules from CV (Vigarano and NWA 3118) and CR (NWA 6043, NWA 801 and LAP 02342) chondrites. All sampled chondrules are classified as type IA or type IAB, have low 27Al/24Mg ratios (0.04-0.27) and display little or no evidence for secondary alteration processes. The CV and CR chondrules show variable 25Mg/24Mg and 26Mg/24Mg values corresponding to a range of mass-dependent fractionation of ∼500 ppm (parts per million) per atomic mass unit. This mass-dependent Mg isotope fractionation is interpreted as reflecting Mg isotope heterogeneity of the chondrule precursors and not the result of secondary alteration or volatility-controlled processes during chondrule formation. The CV and CR chondrule populations studied here are characterized by systematic deficits in the mass-independent component of 26Mg (μ26Mg∗) relative to the solar value defined by CI chondrites, which we interpret as reflecting formation from precursor material with a reduced initial abundance of 26Al compared to the canonical 26Al/27Al of ∼5 × 10-5. Model initial 26Al/27Al values of CV and CR chondrules vary from (1.5 ± 4.0) × 10-6 to (2.2 ± 0.4) × 10-5. The CV chondrules display significant μ54Cr variability, defining a range of compositions that is comparable to that observed for inner Solar System primitive and differentiated meteorites. In contrast, CR chondrites are characterized by a narrower range of μ54Cr values restricted to compositions typically observed for bulk carbonaceous chondrites. Collectively, these observations suggest that the CV chondrules formed from precursors that originated in various regions of the protoplanetary disk and were then transported to the accretion region of the CV parent asteroid whereas CR chondrule predominantly formed from precursor with carbonaceous chondrite-like μ54Cr signatures. The observed μ54Cr variability in chondrules from CV

  9. Magnesium and 54Cr isotope compositions of carbonaceous chondrite chondrules – Insights into early disk processes

    PubMed Central

    Olsen, Mia B.; Wielandt, Daniel; Schiller, Martin; Van Kooten, Elishevah M.M.E.; Bizzarro, Martin

    2016-01-01

    We report on the petrology, magnesium isotopes and mass-independent 54Cr/52Cr compositions (μ54Cr) of 42 chondrules from CV (Vigarano and NWA 3118) and CR (NWA 6043, NWA 801 and LAP 02342) chondrites. All sampled chondrules are classified as type IA or type IAB, have low 27Al/24Mg ratios (0.04–0.27) and display little or no evidence for secondary alteration processes. The CV and CR chondrules show variable 25Mg/24Mg and 26Mg/24Mg values corresponding to a range of mass-dependent fractionation of ~500 ppm (parts per million) per atomic mass unit. This mass-dependent Mg isotope fractionation is interpreted as reflecting Mg isotope heterogeneity of the chondrule precursors and not the result of secondary alteration or volatility-controlled processes during chondrule formation. The CV and CR chondrule populations studied here are characterized by systematic deficits in the mass-independent component of 26Mg (μ26Mg*) relative to the solar value defined by CI chondrites, which we interpret as reflecting formation from precursor material with a reduced initial abundance of 26Al compared to the canonical 26Al/27Al of ~5 × 10−5. Model initial 26Al/27Al values of CV and CR chondrules vary from (1.5 ± 4.0) × 10−6 to (2.2 ± 0.4) × 10−5. The CV chondrules display significant μ54Cr variability, defining a range of compositions that is comparable to that observed for inner Solar System primitive and differentiated meteorites. In contrast, CR chondrites are characterized by a narrower range of μ54Cr values restricted to compositions typically observed for bulk carbonaceous chondrites. Collectively, these observations suggest that the CV chondrules formed from precursors that originated in various regions of the protoplanetary disk and were then transported to the accretion region of the CV parent asteroid whereas CR chondrule predominantly formed from precursor with carbonaceous chondrite-like μ54Cr signatures. The observed μ54Cr variability in chondrules from

  10. Unusual δ56Fe values in Samoan rejuvenated lavas generated in the mantle

    NASA Astrophysics Data System (ADS)

    Konter, Jasper G.; Pietruszka, Aaron J.; Hanan, Barry B.; Finlayson, Valerie A.; Craddock, Paul R.; Jackson, Matthew G.; Dauphas, Nicolas

    2016-09-01

    Several magmatic processes contribute to the Fe isotope composition of igneous rocks. Most basalts fall within a limited range of δ56Fe (+ 0.10 ± 0.05 ‰), although more differentiated lavas trend towards slightly elevated values (up to + 0.3 ‰). New data for basalts and olivine crystals from the Samoan Islands show higher δ56Fe values than have previously been reported for basalts worldwide. Common magmatic processes - from partial melting of average mantle to subsequent differentiation of melts - cannot sufficiently fractionate the Fe isotopes to explain the elevated δ56Fe values (∼ + 0.3 ‰) in rejuvenated Samoan lavas. Instead, a mantle source with an elevated δ56Fe value - in conjunction with effects due to common magmatic processes - is required. The Samoan mantle source is known to be unique in its radiogenic isotope composition and indications that melting of the Samoan mantle source can generate elevated δ56Fe values in lavas comes from: (1) High fO2 values of Samoan lavas and their likely sources affecting Fe isotope fractionation during melting; (2) Metasomatism that caused elevated δ56Fe in the Samoan mantle, as observed in xenoliths; and (3) Involvement of a pyroxenite source lithology, based on the Zn/Fe ratios and TiO2 (and other high field-strength element) abundances of the lavas, that can generate melts with elevated δ56Fe values. Two models are presented to explain the elevated δ56Fe values in Samoan lavas: a metasomatized source (∼ + 0.07 ‰) or the presence of a pyroxenite source component (∼ + 0.12 ‰). Both models subsequently elevate δ56Fe values with both partial melting (∼ + 0.14 ‰) and fractional crystallization (∼ + 0.1 ‰). These processes may be related to an upwelling mantle plume with a pyroxenite component, or melting of previously metasomatized upper mantle.

  11. Evidence for the dipole nature of the low-energy γ enhancement in 56Fe.

    PubMed

    Larsen, A C; Blasi, N; Bracco, A; Camera, F; Eriksen, T K; Görgen, A; Guttormsen, M; Hagen, T W; Leoni, S; Million, B; Nyhus, H T; Renstrøm, T; Rose, S J; Ruud, I E; Siem, S; Tornyi, T; Tveten, G M; Voinov, A V; Wiedeking, M

    2013-12-13

    The γ-ray strength function of 56Fe has been measured from proton-γ coincidences for excitation energies up to ≈11  MeV. The low-energy enhancement in the γ-ray strength function, which was first discovered in the (3He,αγ)56Fe reaction, is confirmed with the (p,p'γ)56Fe experiment reported here. Angular distributions of the γ rays give for the first time evidence that the enhancement is dominated by dipole transitions.

  12. Nuclear Resonance Fluorescence off 54Cr: The Onset of the Pygmy Dipole Resonance

    NASA Astrophysics Data System (ADS)

    Ries, P. C.; Beck, T.; Beller, J.; Krishichayan; Gayer, U.; Isaak, J.; Löher, B.; Mertes, L.; Pai, H.; Pietralla, N.; Romig, C.; Savran, D.; Schilling, M.; Tornow, W.; Werner, V.; Zweidinger, M.

    2016-06-01

    Low-lying electric and magnetic dipole excitations (E1 and M1) below the neutron separation threshold, particularly the Pygmy Dipole Resonance (PDR), have drawn considerable attention in the last years. So far, mostly moderately heavy nuclei in the mass regions around A = 90 and A = 140 were examined with respect to the PDR. In the present work, the systematics of the PDR have been extended by measuring excitation strengths and parity quantum numbers of J = 1 states in lighter nuclei near A = 50 in order to gather information on the onset of the PDR. The nuclei 50,52,54Cr and 48,50Ti were examined via bremsstrahlung produced at the DArmstadt Superconducting electron Linear Accelerator (S-DALINAC) with photon energies up to 9.7 MeV with the method of nuclear resonance fluorescence. Numerous excited states were observed, many of which for the first time. The parity quantum numbers of these states have been determined at the High Intensity Gamma-ray Source (HIγS) of the Triangle Universities Nuclear Laboratory in Durham, NC, USA. Informations to the methods and the experimental setups will be provided and the results on 54Cr achieved will be discussed with respect to the onset of the PDR.

  13. Effects of Proton and Combined Proton and (56)Fe Radiation on the Hippocampus.

    PubMed

    Raber, Jacob; Allen, Antiño R; Sharma, Sourabh; Allen, Barrett; Rosi, Susanna; Olsen, Reid H J; Davis, Matthew J; Eiwaz, Massarra; Fike, John R; Nelson, Gregory A

    2016-01-01

    The space radiation environment contains protons and (56)Fe, which could pose a significant hazard to space flight crews during and after missions. The space environment involves complex radiation exposures, thus, the effects of a dose of protons might be modulated by a dose of heavy-ion radiation. The brain, and particularly the hippocampus, may be susceptible to space radiation-induced changes. In this study, we first determined the dose-response effect of proton radiation (150 MeV) on hippocampus-dependent cognition 1 and 3 months after exposure. Based on those results, we subsequently exposed mice to protons alone (150 MeV, 0.1 Gy), (56)Fe alone (600 MeV/n, 0.5 Gy) or combined proton and (56)Fe radiations (protons first) with the two exposures separated by 24 h. At one month postirradiation, all animal groups showed novel object recognition. However, at three months postirradiation, mice exposed to either protons or combined proton and (56)Fe radiations showed impaired novel object recognition, which was not observed in mice irradiated with (56)Fe alone. The mechanisms in these impairments might involve inflammation. In mice irradiated with protons alone or (56)Fe alone three months earlier, there was a negative correlation between a measure of novel object recognition and the number of newly born activated microglia in the dentate gyrus. Next, cytokine and chemokine levels were assessed in the hippocampus. At one month after exposure the levels of IL-12 were higher in mice exposed to combined radiations compared with sham-irradiated mice, while the levels of IFN-γ were lower in mice exposed to (56)Fe radiation alone or combined radiations. In addition, IL-4 levels were lower in (56)Fe-irradiated mice compared with proton-irradiated mice and TNF-α levels were lower in proton-irradiated mice than in mice receiving combined radiations. At three months after exposure, macrophage-derived chemokine (MDC) and eotaxin levels were lower in mice receiving combined

  14. Effects of Proton and Combined Proton and (56)Fe Radiation on the Hippocampus.

    PubMed

    Raber, Jacob; Allen, Antiño R; Sharma, Sourabh; Allen, Barrett; Rosi, Susanna; Olsen, Reid H J; Davis, Matthew J; Eiwaz, Massarra; Fike, John R; Nelson, Gregory A

    2016-01-01

    The space radiation environment contains protons and (56)Fe, which could pose a significant hazard to space flight crews during and after missions. The space environment involves complex radiation exposures, thus, the effects of a dose of protons might be modulated by a dose of heavy-ion radiation. The brain, and particularly the hippocampus, may be susceptible to space radiation-induced changes. In this study, we first determined the dose-response effect of proton radiation (150 MeV) on hippocampus-dependent cognition 1 and 3 months after exposure. Based on those results, we subsequently exposed mice to protons alone (150 MeV, 0.1 Gy), (56)Fe alone (600 MeV/n, 0.5 Gy) or combined proton and (56)Fe radiations (protons first) with the two exposures separated by 24 h. At one month postirradiation, all animal groups showed novel object recognition. However, at three months postirradiation, mice exposed to either protons or combined proton and (56)Fe radiations showed impaired novel object recognition, which was not observed in mice irradiated with (56)Fe alone. The mechanisms in these impairments might involve inflammation. In mice irradiated with protons alone or (56)Fe alone three months earlier, there was a negative correlation between a measure of novel object recognition and the number of newly born activated microglia in the dentate gyrus. Next, cytokine and chemokine levels were assessed in the hippocampus. At one month after exposure the levels of IL-12 were higher in mice exposed to combined radiations compared with sham-irradiated mice, while the levels of IFN-γ were lower in mice exposed to (56)Fe radiation alone or combined radiations. In addition, IL-4 levels were lower in (56)Fe-irradiated mice compared with proton-irradiated mice and TNF-α levels were lower in proton-irradiated mice than in mice receiving combined radiations. At three months after exposure, macrophage-derived chemokine (MDC) and eotaxin levels were lower in mice receiving combined

  15. Dietary modulation of the effects of exposure to 56Fe particles

    NASA Astrophysics Data System (ADS)

    Rabin, B. M.; Joseph, J. A.; Shukitt-Hale, B.; Carey, A. N.

    On exploratory missions to other planets, astronauts will be exposed to galactic cosmic rays composed of protons and heavy particles, such as 56Fe. Long-term exposure to these particles can cause cancer. However, there are significant uncertainties in the risk estimates for the probability of developing heavy particle-induced cancer, and in the amount of shielding needed to provide an adequate level of radiation protection. The results of this preliminary study, using a ground-based model for exposure to cosmic rays, show reduced tumorigenesis in rats maintained on diets containing blueberry or strawberry extract prior to exposure to 56Fe particles. Because the study was not initially designed to evaluate tumorigenesis following exposure to 56Fe particles, additional research is needed to evaluate the effectiveness of strawberry and blueberry supplementation. However, the preliminary results presented in this study suggest that diets containing antioxidant phytochemicals can provide additional radiation protection on interplanetary voyages.

  16. Neutron cross section covariances in the resonance region: 52Cr, 56Fe, 58Ni

    SciTech Connect

    Oblozinsky, P.; Cho, Y.-S.; Mattoon, C.M.; Mughabghab, S.F.

    2010-08-03

    We evaluated covariances for neutron capture and elastic scattering cross sections on major structural materials, {sup 52}Cr, {sup 56}Fe and {sup 58}Ni, in the resonance region which extends beyond 800 keV for each of them. Use was made of the recently developed covariance formalism based on kernel approximation along with data in the Atlas of Neutron Resonances. The data of most interest for AFCI applications, elastic scattering cross section uncertainties at energies above about few hundred keV, are on the level of about 12% for {sup 52}Cr, 7-8% for {sup 56}Fe and 5-6% for {sup 58}Ni.

  17. Projectile influence on production cross section for ^48Ca-, ^50Ti-, and ^54Cr- induced fusion-evaporation reactions

    NASA Astrophysics Data System (ADS)

    Mayorov, D. A.; Werke, T. A.; Alfonso, M. C.; Bennett, M. E.; Folden, C. M., III

    2013-04-01

    Evaporation residue excitation functions for ^48Ca, ^50Ti + ^159Tb and ^48Ca, ^54Cr + ^162 Dy were measured at Texas A&M University using the vacuum spectrometer MARS. The produced residues are weakly deformed nuclei near the N = 126 shell closure. However, the production cross sections are insensitive to the associated shell stabilization to the fission barrier, an observation previously reported in literature. The ratio of maximum production cross sections between the ^48Ca/^50Ti and ^48Ca/^54Cr reactions is 47 and 7100, respectively. These substantial differences can be reproduced in theoretical calculations by inclusion of collective enhancements during de-excitation of the compound nucleus. The competition between quasifission and complete fusion further contributes to the observed separation in the excitation functions. Model-dependent estimates of the compound nucleus formation probability, PCN, yield ratios of PCN(^48Ca + ^159 Tb) / PCN(^50Ti + ^159 Tb) 2.5 and PCN(^48Ca + ^162Dy) / PCN(^54Cr + ^162Dy) 5. Heavy-ion fusion reactions with ^48Ca, ^50Ti, and ^54Cr projectiles are of interest due to modern-day efforts to synthesize superheavy elements 119 and 120 in warm fusion reactions with projectiles having Z 20.

  18. Exposure to Mission-Relevant Doses of 1 GeV/n (48)Ti Particles Impairs Attentional Set-Shifting Performance in Retired Breeder Rats.

    PubMed

    Hadley, Melissa M; Davis, Leslie K; Jewell, Jessica S; Miller, Vania D; Britten, Richard A

    2016-01-01

    Astronauts on deep space missions will be required to work more autonomously than on previous missions, and thus their ability to perform executive functions could be critical to mission success. In this study we have determined the impact that exposure to 10, 15 and 20 cGy of 1 GeV/n (48)Ti particles has on the long-term (three-months post exposure) ability of male retired breeder Wistar rats to perform attentional set shifting. The ability of the rats to conduct compound discrimination reversal (CDR) was significantly impaired at all doses studied, with compound discrimination (CD) being impaired at 10 and 15 cGy. Impaired CD performance would result in a decreased ability to identify and focus on relevant aspects of a task being conducted, while the functional consequence of an impaired CDR performance would be a reduction in the individual's ability to recognize when that factor changes from a positive to a negative factor for the successful completion of a task. In contrast to our previous study with 1 GeV/n (56)Fe particles, there were no significant impairments in the ability of the (48)Ti-irradiated rats to conduct simple discrimination. This study further supports the notion that "mission-relevant" doses of HZE particles (<20 cGy) can impair certain aspects of attentional set-shifting performance in retired breeder rats, but there may be some ion-specific changes in the specific cognitive domains impaired. PMID:26720801

  19. Local factors modify the dose dependence of 56Fe-induced atherosclerosis.

    NASA Astrophysics Data System (ADS)

    Kucik, Dennis; Gupta, Kiran; Wu, Xing; Yu, Tao; Chang, Polly; Kabarowski, Janusz; Yu, Shaohua

    2012-07-01

    Radiation exposure from a number of terrestrial sources is associated with an increased risk of cardiovascular disease, but evidence establishing whether high-LET radiation has similar effects has been lacking. We recently demonstrated that 600 MeV/n 56Fe induces atherosclerosis as well. Ten-week old male apolipoprotein-E deficient mice, a well-characterized atherosclerosis animal model, were exposed to 0 (control) 2, or 5Gy 56Fe targeted to the chest and neck. In these mice, 56Fe-induced atherosclerosis was similar in character to that induced by X-rays in the same mouse model and to that resulting from therapeutic radiation in cancer patients. Atherosclerosis was exacerbated by 56Fe only in targeted areas, however, suggesting a direct effect of the radiation on the arteries themselves. This is in contrast to some other risk factors, such as high cholesterol or tobacco use, which have systemic effects. The radiation dose required to accelerate development of atherosclerotic plaques, however, differed depending on the vessel that was irradiated and even the location within the vessel. For example, atherosclerosis in the aortic arch was accelerated only by the highest dose (5 Gy), while the carotid arteries and the aortic root showed effects at 2 Gy (a dose four- to eight-fold lower than the dose of X-rays that produces similar effects in this model). Since shear stress is disrupted in the area of the aortic root, it is likely that at least part of the site-specificity is due to additive or synergistic effects of radiation and local hydrodynamics. Other factors, such as local oxidative stress or gene expression may also have been involved. Since the pro-atherogenic effects of 56Fe depend on additional local factors, this suggests that radiation exposure, when unavoidable, might be mitigated by modification of factors unrelated to the radiation itself.

  20. Validation of Geant4 physics models for 56Fe ion beam in various media

    NASA Astrophysics Data System (ADS)

    Jalota, Summit; Kumar, Ashavani

    2012-11-01

    The depth-dose distribution of a 56Fe ion beam has been studied in water, polyethylene, nextel, kevlar and aluminum media. The dose reduction versus areal depth is also calculated for 56Fe ions in carbon, polyethylene and aluminum using the Monte Carlo simulation toolkit Geant4. This study presents the validation of physics models available in Geant4 by comparing the simulated results with the experimental data available in the literature. Simulations are performed using binary cascade (BIC), abrasion-ablation (AA) and quantum molecular dynamics (QMD) models; integrated into Geant4. Deviations from experimental results may be due to the selection of simple geometry. This paper also addresses the differences in the simulated results from various models.

  1. Consistent Data Assimilation of Structural Isotopes: 23Na and 56Fe

    SciTech Connect

    Giuseppe Palmiotti

    2010-09-01

    A new approach is proposed, the consistent data assimilation, that allows to link the integral data experiment results to basic nuclear parameters employed by evaluators to generate ENDF/B point energy files in order to improve them. Practical examples are provided for the structural materials 23Na and 56Fe. The sodium neutron propagation experiments, EURACOS and JANUS-8, are used to improve via modifications of 23Na nuclear parameters (like scattering radius, resonance parameters, Optical model parameters, Statistical Hauser-Feshbach model parameters, and Preequilibrium Exciton model parameters) the agreement of calculation versus experiments for a series of measured reaction rate detectors slopes. For the 56Fe case the EURACOS and ZPR3 assembly 54 are used. Results have shown inconsistencies in the set of nuclear parameters used so that further investigation is needed. Future work involves comparison of results against a more traditional multigroup adjustments, and extension to other isotope of interest in the reactor community.

  2. Analysis of 238Pu and 56Fe Evaluated Data for Use in MYRRHA

    NASA Astrophysics Data System (ADS)

    Díez, C. J.; Cabellos, O.; Martínez, J. S.; Stankovskiy, A.; Van den Eynde, G.; Schillebeeckx, P.; Heyse, J.

    2014-04-01

    A sensitivity analysis on the multiplication factor, keff, to the cross section data has been carried out for the MYRRHA critical configuration in order to show the most relevant reactions. With these results, a further analysis on the 238Pu and 56Fe cross sections has been performed, comparing the evaluations provided in the JEFF-3.1.2 and ENDF/B-VII.1 libraries for these nuclides. Then, the effect in MYRRHA of the differences between evaluations are analysed, presenting the source of the differences. With these results, recommendations for the 56Fe and 238Pu evaluations are suggested. These calculations have been performed with SCALE6.1 and MCNPX-2.7e.

  3. Protective effects of blueberry- and strawberry diets on neuronal stress following exposure to (56)Fe particles.

    PubMed

    Poulose, Shibu M; Bielinski, Donna F; Carrihill-Knoll, Kirsty L; Rabin, Bernard M; Shukitt-Hale, Barbara

    2014-12-17

    Particles of high energy and charge (HZE particles), which are abundant outside the magnetic field of the Earth, have been shown to disrupt the functioning of neuronal communication in critical regions of the brain. Previous studies with HZE particles, have shown that irradiation produces enhanced indices of oxidative stress and inflammation as well as altered neuronal function that are similar to those seen in aging. Feeding animals antioxidant-rich berry diets, specifically blueberries and strawberries, countered the deleterious effects of irradiation by reducing oxidative stress and inflammation, thereby improving neuronal signaling. In the current study, we examined the effects of exposure to (56)Fe particles in critical regions of brain involved in cognitive function, both 36h and 30 days post irradiation. We also studied the effects of antioxidant-rich berry diets, specifically a 2% blueberry or strawberry diet, fed for 8 weeks prior to radiation as well as 30 days post irradiation. (56)Fe exposure caused significant differential, neurochemical changes in critical regions of the brain, such as hippocampus, striatum, frontal cortex, and cerebellum, through increased inflammation, and increased oxidative stress protein markers. (56)Fe exposure altered the autophagy markers, and antioxidant-rich berry diets significantly reduced the accumulation of p62 in hippocampus, a scaffold protein that co-localizes with ubiquitinated protein at the 30 days post irradiation time-point. Exposure to (56)Fe particles increased the accumulation of disease-related proteins such as PHF-tau in the hippocampus of animals fed the control diet, but not in the irradiated animals fed the blueberry diet. These results indicate the potential protective effects of antioxidant-rich berry diets on neuronal functioning following exposure to HZE particles.

  4. Early changes in vascular reactivity in response to 56Fe irradiation in ApoE-/- mice

    NASA Astrophysics Data System (ADS)

    White, C. Roger; Yu, Tao; Gupta, Kiran; Babitz, Stephen K.; Black, Leland L.; Kabarowski, Janusz H.; Kucik, Dennis F.

    2015-03-01

    Epidemiological studies have established that radiation from a number of terrestrial sources increases the risk of atherosclerosis. The accelerated heavy ions in the galacto-cosmic radiation (GCR) that astronauts will encounter on in space, however, interact very differently with tissues than most types of terrestrial radiation, so the health consequences of exposure on deep-space missions are not clear. We demonstrated earlier that 56Fe, an important component of cosmic radiation, accelerates atherosclerotic plaque development. In the present study, we examined an earlier, pro-atherogenic event that might be predictive of later atherosclerotic disease. Decreased endothelium-dependent vasodilation is a prominent manifestation of vascular dysfunction that is thought to predispose humans to the development of structural vascular changes that precede the development of atherosclerotic plaques. To test the effect of heavy-ion radiation on endothelium-dependent vasodilation, we used the same ApoE-/- mouse model in which we previously demonstrated the pro-atherogenic effect of 56Fe on plaque development. Ten week old male ApoE mice (an age at which there is little atherosclerotic plaque in the descending aorta) were exposed to 2.6 Gy 56Fe. The mice were then fed a normal diet and housed under standard conditions. At 4-5 weeks post-irradiation, aortic rings were isolated and endothelial-dependent relaxation was measured. Relaxation in response to acetylcholine was significantly impaired in irradiated mice compared to age-matched, un-irradiated mice. This decrease in vascular reactivity following 56Fe irradiation occurred eight weeks prior to the development of statistically significant exacerbation of aortic plaque formation and may contribute to the formation of later atherosclerotic lesions.

  5. (56)Fe ion irradiation induced apoptosis through Nrf2 pathway in mouse testis.

    PubMed

    Zhao, Qiuyue; Mao, Aihong; Yan, Jiawei; Si, Jing; Zhou, Rong; Gan, Lu; Liu, Yang; Zhang, Hong

    2016-07-15

    The phenomenon has raised the concerns about the safety of an extended manned mission into deep space due to the high potential for exposure to high-LET radiation during space missions. Heavy ions such as (56)Fe are main radiation sources in deep space, which could pose a significant hazard to space flight crews during and after missions. Since the testis is a radiosensitive organ, which may be susceptible to space radiation-induced changes. In this study, we investigated the effect and potential mechanisms of (56)Fe irradiation on mouse testis. Pathological characteristics were measured following whole-body irradiation with 0.5 and 1Gy (56)Fe irradiation. Flow cytometry and terminal dUTP nick end-labeling (TUNEL) were performed to detect apoptotic cells. Western blot was applied to identify potential biomarkers. Immunofluorescence was used to investigate protein localization. We found that pathologic changes and apoptosis cells were significantly higher in 1Gy group than those in 0Gy groups. In addition, protein expression and localization studies confirmed Nrf2 was involved in this acute injury. Nrf2 and its target genes HO-1 and NQO1 were up-regulated in the irradiated testis in a dose-dependent manner. Nrf2 may be useful molecular markers in radiation-induced cellular responses and is important for detecting abnormal spermatogenesis following exposure to space radiation. PMID:27259810

  6. Antimutagenicity of WR-1065 in L5178Y cells exposed to accelerated (56)Fe ions

    NASA Technical Reports Server (NTRS)

    Evans, H. H.; Evans, T. E.; Horng, M. F.

    2002-01-01

    The ability of the aminothiol WR-1065 [N-(2-mercaptoethyl)-1,3-diaminopropane] to protect L5178Y (LY) cells against the cytotoxic and mutagenic effects of exposure to accelerated (56)Fe ions (1.08 GeV/nucleon) was determined. It was found that while WR-1065 reduced the mutagenicity in both cell lines when it was present during the irradiation, the addition of WR-1065 after the exposure had no effect on the mutagenicity of the radiation in either cell line. No marked protection against the cytotoxic effects of exposure to (56)Fe ions was provided by WR-1065 when added either during or after irradiation in either cell line. We reported previously that WR-1065 protected the LY-S1 and LY-SR1 cell lines against both the cytotoxicity and mutagenicity of X radiation when present during exposure, but that its protection when administered after exposure was limited to the mutagenic effects in the radiation-hypersensitive cell line, LY-S1. The results indicate that the mechanisms involved differ in the protection against cytotoxic compared to mutagenic effects and in the protection against damage caused by accelerated (56)Fe ions compared to X radiation.

  7. Cell killing and chromatid damage in primary human bronchial epithelial cells irradiated with accelerated 56Fe ions

    NASA Technical Reports Server (NTRS)

    Suzuki, M.; Piao, C.; Hall, E. J.; Hei, T. K.

    2001-01-01

    We examined cell killing and chromatid damage in primary human bronchial epithelial cells irradiated with high-energy 56Fe ions. Cells were irradiated with graded doses of 56Fe ions (1 GeV/nucleon) accelerated with the Alternating Gradient Synchrotron at Brookhaven National Laboratory. The survival curves for cells plated 1 h after irradiation (immediate plating) showed little or no shoulder. However, the survival curves for cells plated 24 h after irradiation (delayed plating) had a small initial shoulder. The RBE for 56Fe ions compared to 137Cs gamma rays was 1.99 for immediate plating and 2.73 for delayed plating at the D10. The repair ratio (delayed plating/immediate plating) was 1.67 for 137Cs gamma rays and 1.22 for 56Fe ions. The dose-response curves for initially measured and residual chromatid fragments detected by the Calyculin A-mediated premature chromosome condensation technique showed a linear response. The results indicated that the induction frequency for initially measured fragments was the same for 137Cs gamma rays and 56Fe ions. On the other hand, approximately 85% of the fragments induced by 137Cs gamma rays had rejoined after 24 h of postirradiation incubation; the corresponding amount for 56Fe ions was 37%. Furthermore, the frequency of chromatid exchanges induced by gamma rays measured 24 h after irradiation was higher than that induced by 56Fe ions. No difference in the amount of chromatid damage induced by the two types of radiations was detected when assayed 1 h after irradiation. The results suggest that high-energy 56Fe ions induce a higher frequency of complex, unrepairable damage at both the cellular and chromosomal levels than 137Cs gamma rays in the target cells for radiation-induced lung cancers.

  8. Supernova neutrino induced inclusive reactions on {sup 56}Fe in terrestrial detectors

    SciTech Connect

    Athar, M. Sajjad; Ahmad, Shakeb; Singh, S.K.

    2005-04-01

    The calculations for the neutrino absorption cross sections for supernova neutrinos in {sup 56}Fe have been done in the local density approximation (LDA) taking into account Pauli blocking and Fermi motion effects. The renormalization of weak transition strengths in the nuclear medium and the effect of Coulomb distortion of the final lepton are taken into account. The numerical results for the cross sections averaged over the Michel spectrum of neutrinos and various supernova neutrino spectra are presented and compared with other theoretical results.

  9. Hippocampal neurogenesis and neuroinflammation after cranial irradiation with (56)Fe particles.

    PubMed

    Rola, Radoslaw; Fishman, Kelly; Baure, Jennifer; Rosi, Susanna; Lamborn, Kathleen R; Obenaus, Andre; Nelson, Gregory A; Fike, John R

    2008-06-01

    Exposure to heavy-ion radiation is considered a potential health risk in long-term space travel. In the central nervous system (CNS), loss of critical cellular components may lead to performance decrements that could ultimately compromise mission goals and long-term quality of life. Hippocampal-dependent cognitive impairments occur after exposure to ionizing radiation, and while the pathogenesis of this effect is not yet clear, it may involve the production of newly born neurons (neurogenesis) in the hippocampal dentate gyrus. We irradiated mice with 0.5-4 Gy of (56)Fe ions and 2 months later quantified neurogenesis and numbers of activated microglia as a measure of neuroinflammation in the dentate gyrus. Results showed that there were few changes after 0.5 Gy, but that there was a dose-related decrease in hippocampal neurogenesis and a dose-related increase in numbers of newly born activated microglia from 0.5-4.0 Gy. While those findings were similar to what was reported after X irradiation, there were also some differences, particularly in the response of newly born glia. Overall, this study showed that hippocampal neurogenesis was sensitive to relatively low doses of (56)Fe particles, and that those effects were associated with neuroinflammation. Whether these changes will result in functional impairments or if/how they can be managed are topics for further investigation.

  10. Hippocampal Neurogenesis and Neuroinflammation after Cranial Irradiation with 56Fe Particles

    PubMed Central

    Rola, Radoslaw; Fishman, Kelly; Baure, Jennifer; Rosi, Susanna; Lamborn, Kathleen R.; Obenaus, Andre; Nelson, Gregory A.; Fike, John R.

    2008-01-01

    Exposure to heavy-ion radiation is considered a potential health risk in long-term space travel. In the central nervous system (CNS), loss of critical cellular components may lead to performance decrements that could ultimately compromise mission goals and long-term quality of life. Hippocampal-dependent cognitive impairments occur after exposure to ionizing radiation, and while the pathogenesis of this effect is not yet clear, it may involve the production of newly born neurons (neurogenesis) in the hippocampal dentate gyrus. We irradiated mice with 0.5–4 Gy of 56Fe ions and 2 months later quantified neurogenesis and numbers of activated microglia as a measure of neuroinflammation in the dentate gyrus. Results showed that there were few changes after 0.5 Gy, but that there was a dose-related decrease in hippocampal neurogenesis and a dose-related increase in numbers of newly born activated microglia from 0.5–4.0 Gy. While those findings were similar to what was reported after X irradiation, there were also some differences, particularly in the response of newly born glia. Overall, this study showed that hippocampal neurogenesis was sensitive to relatively low doses of 56Fe particles, and that those effects were associated with neuroinflammation. Whether these changes will result in functional impairments or if/how they can be managed are topics for further investigation. PMID:18494546

  11. Beneficial effects of fruit extracts on neuronal function and behavior following 56Fe irradiation

    NASA Astrophysics Data System (ADS)

    Joseph, J. A.; Shukitt-Hale, B.; Carey, A. N.; Jenkins, D.; Rabin, B. M.

    Exposing young rats to particles of high energy and charge HZE particles enhances indices of oxidative stress and inflammation and disrupts the functioning of the dopaminergic system and behaviors mediated by this system in a manner similar to that seen in aged animals Previous research has shown that diets supplemented with 2 blueberry or strawberry extracts have the ability to retard and even reverse age-related deficits in behavior and signal transduction in rats perhaps due to their antioxidant and anti-inflammatory properties This study evaluated the efficacy of these diets on irradiation-induced deficits in these parameters by maintaining rats on these diets or a control diet for 8 weeks prior to being exposed to whole-body irradiation with 1 5 Gy of 1 GeV n high-energy 56 Fe particles Irradiation impaired performance in the Morris water maze and measures of dopamine release one month following radiation these deficits were protected by the antioxidant diets The strawberry diet offered better protection against spatial deficits in the maze because strawberry-fed animals were better able to retain place information a hippocampally-mediated behavior compared to controls The blueberry diet on the other hand seemed to improve reversal learning a behavior more dependent on intact striatal function These data suggest that 56 Fe particle irradiation causes deficits in behavior and signaling in rats which were ameliorated by an antioxidant diet and that the polyphenols in these fruits might be acting in different brain regions

  12. Interaction Between Age and Exposure to 56Fe Particles on Behavior and Neurochemistry

    NASA Astrophysics Data System (ADS)

    Shukitt-Hale, B.; Carey, A. N.; Rabin, B. M.; Joseph, J. A.

    Previous research has shown that exposure to HZE particles and protons which will be encountered on long-term space missions can adversely affect the ability of rats to perform a variety of behavioral tasks This outcome has implications for an astronaut s ability to successfully complete requirements associated with these missions It has also been found that irradiation can lead to increases in oxidative stress similar to that seen in the aging brain Given that astronauts are often middle-aged or older it is important to determine if their age puts them at higher risk for the potentially hazardous effects of exposure to HZE particles Therefore we exposed young and old rats to either 1 or 2Gy of 56 Fe irradiation and evaluated performance in a spatial learning and memory task in addition to examining levels of dopamine DA release from superfused striatal slices Results indicated that exposure to 56 Fe particles can produce alterations in behavior and signaling and that these alterations may be more apparent in older organisms which suggests that the aging brain may be more susceptible to the deleterious effects of irradiation on performance Therefore age may be a factor for consideration in planning long-term missions into space Supported by NASA Grants NAG9-1190 and NAG9-1529

  13. Interaction between age and exposure to 56Fe particles on behavior and neurochemistry

    NASA Astrophysics Data System (ADS)

    Carey, Amanda N.; Shukitt-Hale, Barbara; Rabin, Bernard M.; Joseph, James A.

    Previous research has shown that exposure to HZE particles, which will be encountered on long-term space missions, can adversely affect the ability of rats to perform a variety of behavioral tasks. This outcome has implications for an astronaut’s ability to successfully complete requirements associated with these missions. It has also been found that irradiation can lead to increases in oxidative stress, similar to that seen in the aging brain. Given that astronauts are often middle-aged or older it is important to determine if their age puts them at higher risk for the potentially hazardous effects of exposure to HZE particles. Therefore, we exposed young and old rats to either 1 or 2 Gy of 56Fe irradiation and evaluated performance in a spatial learning and memory task, in addition to examining levels of dopamine (DA) release from superfused striatal slices. Results indicated that exposure to 56Fe particles can produce alterations in behavior and neuronal signaling and that these alterations may be more apparent in older organisms, a finding which suggests that the aging brain may be more susceptible to the deleterious effects of irradiation on performance. Therefore, age may be a factor for consideration in planning long-term missions into space.

  14. (56)Fe Irradiation Alters Spine Density and Dendritic Complexity in the Mouse Hippocampus.

    PubMed

    Allen, Antiño R; Raber, Jacob; Chakraborti, Ayanabha; Sharma, Sourabh; Fike, John R

    2015-12-01

    A unique feature of the space radiation environment is the presence of high-energy charged particles, which can be significantly hazardous to space flight crews who are exposed during a mission. Health risks associated with high-LET radiation exposure include cognitive injury. The pathogenesis of this injury is unknown but may involve modifications to dendritic structure and/or alterations in dendritic spine density and morphology. In this study, 24 two-month-old C57BL6/J male mice were either whole-body irradiated with 0.5 Gy (56)Fe (600 MeV/n; n = 12) or sham irradiated (n = 12). Three months postirradiation animals were tested for locomotor activity and habituation. After behavioral testing, animals were euthanized and the brains were flash frozen. Compared to sham-irradiated mice, irradiated mice moved less when first introduced to the environment, although they did recognize the environment when re-exposed to it one day later. Exposure to (56)Fe radiation significantly compromised the dendritic architecture and reduced spine density throughout the hippocampal tri-synaptic network. To our knowledge, these data represents the first reported evidence that high-LET radiation has deleterious effects on mature neurons associated with hippocampal learning and memory. PMID:26579941

  15. Differential Effects of X-Rays and High-Energy {sup 56}Fe Ions on Human Mesenchymal Stem Cells

    SciTech Connect

    Kurpinski, Kyle; Jang, Deok-Jin; Bhattacharya, Sanchita; Rydberg, Bjorn; Chu, Julia; So, Joanna; Wyrobek, Andy; Li Song; Wang Daojing

    2009-03-01

    Purpose: Stem cells hold great potential for regenerative medicine, but they have also been implicated in cancer and aging. How different kinds of ionizing radiation affect stem cell biology remains unexplored. This study was designed to compare the biological effects of X-rays and of high-linear energy transfer (LET) {sup 56}Fe ions on human mesenchymal stem cells (hMSC). Methods and Materials: A multi-functional comparison was carried out to investigate the differential effects of X-rays and {sup 56}Fe ions on hMSC. The end points included modulation of key markers such as p53, cell cycle progression, osteogenic differentiation, and pathway and networks through transcriptomic profiling and bioinformatics analysis. Results: X-rays and {sup 56}Fe ions differentially inhibited the cell cycle progression of hMSC in a p53-dependent manner without impairing their in vitro osteogenic differentiation process. Pathway and network analyses revealed that cytoskeleton and receptor signaling were uniquely enriched for low-dose (0.1 Gy) X-rays. In contrast, DNA/RNA metabolism and cell cycle regulation were enriched for high-dose (1 Gy) X-rays and {sup 56}Fe ions, with more significant effects from {sup 56}Fe ions. Specifically, DNA replication, DNA strand elongation, and DNA binding/transferase activity were perturbed more severely by 1 Gy {sup 56}Fe ions than by 1 Gy X-rays, consistent with the significant G2/M arrest for the former while not for the latter. Conclusions: {sup 56}Fe ions exert more significant effects on hMSC than X-rays. Since hMSC are the progenitors of osteoblasts in vivo, this study provides new mechanistic understandings of the relative health risks associated with low- and high-dose X-rays and high-LET space radiation.

  16. 56Fe accelerates development of atherosclerosis in apoE -/-mice

    NASA Astrophysics Data System (ADS)

    Kucik, Dennis; Yu, Tao; Parks, Brian; Yu, Shaohua; Srivastava, Roshni; Gupta, Kiran; Wu, Xing; Khaled, Saman; Chang, Polly; Kabarowski, Janusz

    Exposure to radiation from a variety of sources is associated with increased risk of heart disease and stroke. For example, for women with early breast cancer, the benefit of radiotherapy can be nearly offset by the increased risk of mortality from cardiovascular disease. Head and neck cancer patients who undergo radiation treatment are at significantly elevated risk of stroke, even in a relatively young patient population that would not normally be at risk for atheroscle-rosis. Similarly, atomic bomb survivors had an increased incidence of mortality from coronary artery disease and stroke. Even radiation technologists working before 1950 (when occupational exposure was higher) had increased mortality due to circulatory diseases. Although much is known about the cardiovascular consequences these exposures to X-raus and gamma radiation, the response to the type of radiation likely to be encountered in prolonged space flight has not been determined. A key component of this cosmic radiation is 56Fe, which is particularly damaging to tissues. Using collimated beams, we selectively irradiated aortic arches and carotids (only) of the well-established apoE -/-atherosclerosis mouse model to test directly whether 56Fe exposure is a cardiovascular risk factor. Mice were sacrificed at 13 weeks post-irradiation and dissected, and aortas were divided into areas that had been targeted by the ion beam and those that were not. The area that was covered by plaques was then quantified. Plaque area at 13 weeks post-irradiation was significantly greater in targeted areas of mice that had received 5 Gy of 56Fe as compared to age-and sex-matched un-irradiated controls. In the carotid arteries and aortic roots, significantly greater atherosclerosis was apparent for a 2Gy exposure as well (the lowest dose tested). This demonstrates that even a single exposure to heavy ion radiation is capable of triggering events that culminate in cardiovascular disease, even long after the exposure has

  17. Experimental and calculated excitation functions for discrete-line gamma-ray production due to 1-40 MeV neutron interactions with sup 56 Fe

    SciTech Connect

    Dickens, J.K.; Fu, C.Y.; Hetrick, D.M.; Larson, D.C.; Todd, J.H.

    1991-01-01

    Measuring cross sections for gamma-ray production from tertiary reactions is one of the ways to gain experimental information about these reactions. To this end, inelastic and other nonelastic neutron interactions with {sup 56}Fe have been studied for incident neutron energies between 0.8 and 41 MeV. An iron sample isotopically enriched in the mass 56 isotope was used. Gamma rays representing 70 transitions among levels in residual nuclei were identified, and production cross sections were deduced. The reactions studies were {sup 56}Fe(n,n{prime}){sup 56}Fe, {sup 56}Fe(n,p){sup 56}Mn, {sup 56}Fe(n,2n){sup 55}Fe, {sup 56}Fe(n,d + n,np){sup 55}Mn, {sup 56}Fe(n, t + n, nd + n,2np){sup 54}Mn, {sup 56}Fe(n,{alpha}){sup 53}Cr, {sup 56}Fe(n,n{alpha}){sup 52}Cr, and {sup 56}Fe(n,3n){sup 54}Fe. Experimental excitation functions have been compared with cross sections calculated using the nuclear reaction model code TNG, with generally favorable results. 24 refs., 2 figs.

  18. Collective magnetic multipole excitations in open shells: 48Ti

    NASA Astrophysics Data System (ADS)

    Liu, H.; Zamick, L.

    1987-11-01

    The magnetic multipole even-parity transitions are calculated in 48Ti with a mind to finding interesting collective behavior and to study the effects of increasing the model space. The single-j shell signature selection rules are compared to those in the neutron-proton interacting boson model with good F spin. There are similarities but also differences. Some behavior of the single-j shell calculation survives as the model space increases, e.g., low lying collective M1 and M7 modes. Configuration mixing is, however, vital to describe the M3 and M5 modes as well as the spin flip M1 modes. The distribution of strength between lower and higher isospins is discussed. Results are compared with calculated transitions in 42Sc. It appears that allowing one-particle excitations from the single-j shell gives the pattern of the strength distribution; the further addition of two-particle excitations leads to a quenching of the strength distribution.

  19. Level density and mechanism of deuteron-induced reactions on 54,58,56Fe

    NASA Astrophysics Data System (ADS)

    Ramirez, A. P. D.; Voinov, A. V.; Grimes, S. M.; Byun, Y.; Brune, C. R.; Massey, T. N.; Akhtar, S.; Dhakal, S.; Parker, C. E.

    2015-07-01

    Deuteron elastic cross sections, as well as neutron, proton, and α -particle emission spectra, from d + 54,58,56Fe reactions have been measured with deuteron beam energies of 5, 7, and 9 MeV. Optical model parameters have been tested against our experimental data. The fraction of total reaction cross section responsible for the formation of compound nuclei has been deduced from the angular distributions. The degree of discrepancy between calculated and experimental compound cross sections was found to increase with increasing neutron number. The nuclear level densities of the residual nuclei 57Co, 55Co, 57Fe, 55Fe, 52Mn, 54Mn have been deduced from the compound double differential cross sections. The Gilbert-Cameron model with Iljinov parameter systematics [A. S. Iljinov and M. V. Mebel, Nucl. Phys. A 543, 517 (1992)], 10.1016/0375-9474(92)90278-R was found to have a good agreement with our results.

  20. Cognitive differences between male and female rats following exposure to 56Fe particles

    NASA Astrophysics Data System (ADS)

    Rabin, Bernard; Shukitt-Hale, Barbara; Carrihill-Knoll, Kirsty; Luskin, Katharine; Long, Lauren; Joseph, James

    On exploratory class missions astronauts will be exposed to types and doses of radiation (HZE particles) that are not experienced in low earth orbit. While it is likely that the crew will consist of both male and female astronauts, there has been little research on the effects of exposure to HZE particles on cognitive performance in female subjects. While previous research has shown that exposure to HZE particles disrupts cognitive performance in male rats it remains to be established whether or not similar effects will occur with female subjects because estrogen may act as a neuroprotectant. Ovariectomized (OVX) female rats were obtained from Taconic Farms. Thirty mm segments of silastic tubing containing either 180 pg l7-estradiol/mL in sesame oil or vehicle alone were implanted subcutaneously in the neck. Three days following surgery the rats were exposed to 56Fe particles (1000 MeV/n, 0-200 cGy) at the NSRL. Following irradiation the rats were shipped to UMBC for behavioral testing. The results indicated that the pattern of decrements in cognitive performance differed between male and female rats. In addition, for female rats, there were differences in performance as a function of the presence or absence of estradiol. In the vehicle implanted subjects exposure to 56Fe particles did not affect operant responding on an ascending fixed-ratio schedule; whereas irradiation did disrupt responding in OVX animals given estradiol. These results suggest that estrogen may not be protective following exposure to HZE particles. This research was supported by Grant NNX08AM66G from NASA.

  1. A priming dose of protons alters the early cardiac cellular and molecular response to 56Fe irradiation

    NASA Astrophysics Data System (ADS)

    Ramadan, Samy S.; Sridharan, Vijayalakshmi; Koturbash, Igor; Miousse, Isabelle R.; Hauer-Jensen, Martin; Nelson, Gregory A.; Boerma, Marjan

    2016-02-01

    Purpose: Recent evidence suggests that the heart may be injured by ionizing radiation at lower doses than was previously thought. This raises concerns about the cardiovascular risks from exposure to radiation during space travel. Since space travel is associated with exposure to both protons from solar particle events and heavy ions from galactic cosmic rays, we here examined the effects of a "priming" dose of protons on the cardiac cellular and molecular response to a "challenge" dose of 56Fe in a mouse model. Methods: Male C57BL/6 mice at 10 weeks of age were exposed to sham-irradiation, 0.1 Gy of protons (150 MeV), 0.5 Gy of 56Fe (600 MeV/n), or 0.1 Gy of protons 24 hours prior to 0.5 Gy of 56Fe. Hearts were obtained at 7 days post-irradiation and western-blots were used to determine protein markers of cardiac remodeling, inflammatory infiltration, and cell death. Results: Exposure to 56Fe caused an increase in expression of α-smooth muscle cell actin, collagen type III, the inflammatory cell markers mast cell tryptase, CD2 and CD68, the endothelial glycoprotein thrombomodulin, and cleaved caspase 3. Of all proteins investigated, protons at a dose of 0.1 Gy induced a small increase only in cleaved caspase 3 levels. On the other hand, exposure to protons 24 hours before 56Fe prevented all of the responses to 56Fe. Conclusions: This study shows that a low dose of protons may prime the heart to respond differently to a subsequent challenge dose of heavy ions. Further investigation is required to identify responses at additional time points, consequences for cardiac function, threshold dose levels, and mechanisms by which a proton priming dose may alter the response to heavy ions.

  2. Incidence of acute myeloid leukemia and hepatocellular carcinoma in mice irradiated with 1 GeV/nucleon (56)Fe ions.

    PubMed

    Weil, Michael M; Bedford, Joel S; Bielefeldt-Ohmann, Helle; Ray, F Andrew; Genik, Paula C; Ehrhart, Eugene J; Fallgren, Christina M; Hailu, Fitsum; Battaglia, Christine L R; Charles, Brad; Callan, Matthew A; Ullrich, Robert L

    2009-08-01

    Abstract Estimates of cancer risks posed to space-flight crews by exposure to high atomic number, high-energy (HZE) ions are subject to considerable uncertainty because epidemiological data do not exist for human populations exposed to similar radiation qualities. We assessed the leukemogenic efficacy of one such HZE species, 1 GeV (56)Fe ions, a component of space radiation, in a mouse model for radiation-induced acute myeloid leukemia. CBA/CaJ mice were irradiated with 1 GeV/nucleon (56)Fe ions or (137)Cs gamma rays and followed until they were moribund or to 800 days of age. We found that 1 GeV/nucleon (56)Fe ions do not appear to be substantially more effective than gamma rays for the induction of acute myeloid leukemia (AML). However, (56)Fe-ion-irradiated mice had a much higher incidence of hepatocellular carcinoma (HCC) than gamma-irradiated mice, with an estimated RBE of approximately 50. These data suggest a difference in the effects of HZE iron ions on the induction of leukemia compared to solid tumors, suggesting potentially different mechanisms of tumorigenesis. PMID:19630525

  3. Amphetamine-Induced Taste Aversion Learning in Young and Old F-344 Rats Following Exposure to 56Fe Particles

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Exposure to 56Fe particles produces changes in dopaminergic function and in dopamine dependent behaviors, including amphetamine-induced conditioned taste aversion (CTA) learning. Because many of these changes are characteristic of the changes that accompany the aging process, the present study was ...

  4. Effects of exposure to 56Fe particles or protons on fixed-ratio operant responding in rats

    NASA Technical Reports Server (NTRS)

    Rabin, Bernard M.; Buhler, Lynn L.; Joseph, James A.; Shukitt-Hale, Barbara; Jenkins, Daniel G.

    2002-01-01

    On long-duration trips outside of the magnetosphere, astronauts will be exposed to protons and to heavy particles which can affect their performance of required tasks. It is essential to determine the range of behaviors that might be affected by exposure to these types of radiation in order to understand the nature of behavioral deficits and to develop effective countermeasures. The present experiment examined the ability of rats to make an operant response following exposure to protons (250 MeV, 4 Gy) or 56Fe particles (1 GeV/n, 1 or 2 Gy). Following irradiation, rats were trained to press a lever in order to obtain food reinforcement. They were then placed on an ascending fixed-ratio schedule from FR-1 (each lever press rewarded with a food pellet) through FR-35 (35 lever presses required for 1 food pellet). Rats exposed to 4 Gy of protons or 1 Gy of 56Fe particles responded similarly to controls, increasing their rate of responding as the ratio increased. However, rats exposed to 2 Gy of 56Fe particles failed to increase their rate of responding at ratios greater than FR-20, indicating that rats exposed to 2 Gy of 56Fe particles cannot respond appropriately to increasing work requirements.

  5. Evaporation residue excitation function measurements in 50Ti- and 54Cr-induced reactions with lanthanide targets

    NASA Astrophysics Data System (ADS)

    Mayorov, D. A.; Werke, T. A.; Alfonso, M. C.; Tereshatov, E. E.; Bennett, M. E.; Frey, M. M.; Folden, C. M.

    2015-11-01

    Cross sections for the production of shell-stabilized evaporation residues in the 50Ti+Gd160 , 159Tb, 162Dy , and 54Cr+Dy162 reactions are reported. The compound nucleus excitation energy range considered principally covers the 4 n evaporation channel with segments of the 3 n and 5 n channels also measured. The resultant production cross sections are for nuclides with Z =86 -90 . From an analysis based on a statistical model, it is concluded that a larger fission probability than that predicted by the Bohr-Wheeler transition-state theory is needed to describe the data. This outcome is attributed to the influence of collective nuclear excitations. Subsequently, the expected stability enhancement against fission due to the influence of the magic N =126 shell is not evident. The x n excitation functions measured in previous experiments in the reactions 48Ca+Gd154 , 159Tb,Dy162 , and 165Ho are combined with the present data for Z >20 projectiles to illustrate systematic behavior of measured cross sections as a function of the difference in fission barrier and neutron separation energy.

  6. Brain signaling and behavioral responses induced by exposure to (56)Fe-particle radiation

    NASA Technical Reports Server (NTRS)

    Denisova, N. A.; Shukitt-Hale, B.; Rabin, B. M.; Joseph, J. A.

    2002-01-01

    Previous experiments have demonstrated that exposure to 56Fe-particle irradiation (1.5 Gy, 1 GeV) produced aging-like accelerations in neuronal and behavioral deficits. Astronauts on long-term space flights will be exposed to similar heavy-particle radiations that might have similar deleterious effects on neuronal signaling and cognitive behavior. Therefore, the present study evaluated whether radiation-induced spatial learning and memory behavioral deficits are associated with region-specific brain signaling deficits by measuring signaling molecules previously found to be essential for behavior [pre-synaptic vesicle proteins, synaptobrevin and synaptophysin, and protein kinases, calcium-dependent PRKCs (also known as PKCs) and PRKA (PRKA RIIbeta)]. The results demonstrated a significant radiation-induced increase in reference memory errors. The increases in reference memory errors were significantly negatively correlated with striatal synaptobrevin and frontal cortical synaptophysin expression. Both synaptophysin and synaptobrevin are synaptic vesicle proteins that are important in cognition. Striatal PRKA, a memory signaling molecule, was also significantly negatively correlated with reference memory errors. Overall, our findings suggest that radiation-induced pre-synaptic facilitation may contribute to some previously reported radiation-induced decrease in striatal dopamine release and for the disruption of the central dopaminergic system integrity and dopamine-mediated behavior.

  7. Measurements of Materials Shielding Properties with 1 GeV/nuc56Fe

    SciTech Connect

    Zeitlin, Cary; Guetersloh, Stephen B.; Heilbronn, Lawrence H.; Miller, Jack

    2006-05-15

    The design of future spacecraft such as the Crew ExplorationVehicle must take into account the radiation shielding properties of boththe structural components as well as dedicated shielding materials. Sincemodest depths of shielding stop the vast majority of Solar EnergeticParticles (SEP), the greater challenge is posed by the need to shieldcrew from the Galactic Cosmic Rays (GCR), which include highly-chargedand highly-energetic particles. Here, we report on results from testsperformed with beams of 1 GeV/nuc 56Fe at the Brookhaven NationalLaboratory. A wide variety of targets, both elemental and composite, wereplaced in the particle beams, and the spectra of particles emerging fromthe targets were measured using a stack of silicon detectors. Results arepresented primarily in terms of dose reduction per g cm-2 of targetmaterial, and support the conclusions of an earlier calculation by Wilsonet al. showing that performance improves as the shield's mass numberdecreases, with hydrogen being by far the most effective. The data alsoshow that, as depth increases, the incremental benefit of addingshielding decreases, particularlyfor aluminum and other elements withhigher atomic mass numbers.

  8. Alterations in gene expression in rat skin exposed to 56Fe ions and dietary vitamin A acetate.

    PubMed

    Zhang, Ronghe; Burns, Fredric J; Chen, Haobin; Chen, Shuaili; Wu, Feng

    2006-05-01

    The purpose of the present work was to examine gene expression patterns in rat skin exposed to a beam of (56)Fe ions, a surrogate for the high-energy, heavy-ion galactic radiation background, as a basis for obtaining a better understanding of the possible mechanism(s) behind the radioprotective activity of vitamin A. A 2 x 4-cm rectangle of dorsal rat skin was exposed to 1.01 GeV/nucleon (56)Fe ions generated by the Alternating Gradient Synchrotron at Brookhaven National Laboratory. Gene expression patterns were monitored in either the presence or absence of a 250-ppm dietary supplement of vitamin A acetate in powdered lab chow. Although vitamin A and other retinoids show anti-carcinogenic activity in several animal models, the underlying changes in gene expression have not been examined extensively. At either 1 or 7 day after irradiation, a 1-cm square of irradiated and control rat skin was excised and analyzed using the Affymetrix rat microarray (RG_U34A) system. Microarray responses were displayed and processed by GeneSpring 7.0 and GOTree software. At 1 day after 3 Gy of (56)Fe-ion irradiation, the expression of 110 genes was significantly up-regulated (P < = 0.05) in comparison to levels in control rat skin, while no genes were altered by the vitamin A acetate supplement alone. Combined with (56)Fe-ion radiation, the vitamin A acetate supplement blocked the expression of 88 (80%) of the 110 genes and eliminated 16 of 18 gene categories that were significantly altered (all increased) by the (56)Fe-ion radiation. Categories with large numbers of genes eliminated by the retinoid included response to stress, 33 genes; response to biotic stimulus, 38 genes; signal transduction, 35 genes; and regulation of cellular/physiological process, 40 genes. Even for immune response and response to biotic stimulus, the only two categories that remained significantly altered in the presence of the vitamin, the combined number of altered genes was reduced from 74 to 13. No

  9. Changes in Gene Expression in the Hippocampus Following Exposure to 56Fe Particles and Protection by Berry Diets

    NASA Astrophysics Data System (ADS)

    Shukitt-Hale, Barbara; Lau, Francis; Carey, Amanda; Carrihill-Knoll, Kirsty; Rabin, Bernard; Joseph, James

    Exposing young rats to particles of high energy and charge (HZE particles), such as 56 Fe, enhances indices of oxidative stress and inflammation and disrupts the functioning of the dopaminergic system and behaviors mediated by this system in a manner similar to that seen in aged animals. Behaviors affected by radiation include deficits in motor performance, spatial learning and memory behavior, amphetamine-induced conditioned taste aversion learning, conditioned place preference, and operant conditioning. Berry fruit diets are high in antioxidant and antiinflammatory activity, and prevent the occurrence of the neurochemical and behavioral changes that occur in aging and by exposure to 56 Fe particles. In the present study, we examined whether gene expression in the hippocampus, an area of the brain important in memory, is affected by exposure to 56 Fe particles 36 hours post-irradiation. We also evaluated whether the blueberry (BB) and strawberry (SB) diets could ameliorate irradiation-induced deficits in gene expression by maintaining rats on these diets or a control diet for 8 weeks prior to being exposed to radiation. Therefore, to measure gene expression, 4 rats/group were euthanized 36 hours post whole-body irradiation with 1.5 Gy or 2.5 Gy of 1 GeV/n high-energy 56 Fe particles. Alterations in gene expression profile induced by radiation were analyzed by pathway-focused microarrays on the inflammatory cytokines and genes involved in NF-κB signal transduction pathways. For the diet studies, 3 rats/group were irradiated with 2.5 Gy of 56 Fe following 8 weeks supplementation with either the 2% BB or the 2% SB diet. We found that genes that directly or indirectly interact in the regulation of growth and differentiation of neurons were changed following irradiation. Genes that regulate apoptosis were up-regulated whereas genes that modulate cellular proliferation were down-regulated, possibly to eliminate damaged cells and to stop cell proliferation to prevent

  10. Effects of whole body (56)Fe radiation on contextual freezing and Arc-positive cells in the dentate gyrus.

    PubMed

    Raber, Jacob; Allen, Antiño R; Rosi, Susanna; Sharma, Sourabh; Dayger, Catherine; Davis, Matthew J; Fike, John R

    2013-06-01

    The space radiation environment contains high-energy charged particles such as (56)Fe, which could pose a significant hazard to hippocampal function in astronauts during and after the mission(s). The mechanisms underlying impairments in cognition are not clear but might involve alterations in the percentage of neurons in the dentate gyrus expressing the plasticity-related immediate early gene Arc. Previously, we showed effects of cranial (56)Fe irradiation on hippocampus-dependent contextual freezing and on the percentage of Arc-positive cells in the enclosed, but not free, blade. Because it is unclear whether whole body (56)Fe irradiation causes similar effects on these markers of hippocampal function, in the present study we quantified the effects of whole body (56)Fe irradiation (600MeV, 0.5 or 1Gy) on hippocampus-dependent and hippocampus-independent cognitive performance and determined whether these effects were associated with changes in Arc expression in the enclosed and free blades of the dentate gyrus. Whole body (56)Fe irradiation impacted contextual but not cued fear freezing and the percentage of Arc-positive cells in the enclosed and free blades. In mice tested for contextual freezing, there was a correlation between Arc-positive cells in the enclosed and free blades. In addition, in mice irradiated with 0.5Gy, contextual freezing in the absence of aversive stimuli correlated with the percentage of Arc-positive cells in the enclosed blade. In mice tested for cued freezing, there was no correlation between Arc-positive cells in the enclosed and free blades. In contrast, cued freezing in the presence or absence of aversive stimuli correlated with Arc-positive cells in the free blade. In addition, in mice irradiated with 1Gy cued freezing in the absence of aversive stimuli correlated with the percentage of Arc-positive neurons in the free blade. These data indicate that while whole body (56)Fe radiation affects contextual freezing and Arc-positive cells

  11. Effects of exposure to 56Fe particles on the acquisition of a conditioned place preference in rats

    NASA Technical Reports Server (NTRS)

    Rabin, B. M.; Shukitt-Hale, B.; Joseph, J. A.; Denissova, N.

    2001-01-01

    Exposure to low doses of 56Fe particles produces changes in neural function and behavior. The present experiments were designed to examine the effects of irradiation on the acquisition of a dopamine-mediated conditioned place preference (CPP). In the CPP procedure, rats are given an injection of the dopamine agonist amphetamine in one distinctive compartment and a saline injection in a different compartment of a three-compartment apparatus. Control rats develop a preference for the amphetamine-paired compartment. In contrast, rats exposed to 1 Gy of 56Fe particles fail to develop a similar preference. The results of the experiment indicate that exposure to low doses of heavy particles can disrupt the neural mechanisms that mediate the reinforcement of behavior.

  12. Decreased RXRα is Associated with Increased β-Catenin/TCF4 in 56Fe-Induced Intestinal Tumors

    PubMed Central

    Suman, Shubhankar; Kumar, Santosh; Fornace, Albert J.; Datta, Kamal

    2015-01-01

    Although it is known that accumulation of oncogenic β-catenin is critical for intestinal tumorigenesis, the underlying mechanisms have not yet been fully explored. Post-translational β-catenin level is regulated via the adenomatous polyposis coli (APC)-dependent as well as the APC-independent ubiquitin–proteasome pathway (UPP). Employing an APC-mutant mouse model (APCMin/+) the present study aimed to investigate the status of RXRα, an APC-independent factor involved in targeting β-catenin to UPP for degradation, in tumor-bearing and tumor-free areas of intestine after exposure to energetic 56Fe ions. APCMin/+ mice were exposed to energetic 56Fe ions (4 or 1.6 Gy) and intestinal tumor samples and tumor-free normal intestinal samples were collected 100–110 days after exposure. The status of TCF4, β-catenin, cyclin D1, and RXRα was examined using immunohistochemistry and immunoblots. We observed increased accumulation of the transcription factor TCF4 and its co-activator β-catenin as well as their downstream oncogenic target protein cyclin-D1 in 56Fe ion-induced intestinal tumors. Further, decreased expression of RXRα in tumors as well as in adjacent normal epithelium was indicative of perturbations in β-catenin proteasomal-targeting machinery. This indicates that decreased UPP targeting of β-catenin due to downregulation of RXRα can contribute to further accumulation of β-catenin and to 56Fe-induced tumorigenesis. PMID:26500891

  13. Characteristics of genomic instability in clones of TK6 human lymphoblasts surviving exposure to 56Fe ions

    NASA Technical Reports Server (NTRS)

    Evans, Helen H.; Horng, Min-Fen; Ricanati, Marlene; Diaz-Insua, Mireya; Jordan, Robert; Schwartz, Jeffrey L.

    2002-01-01

    Genomic instability in the human lymphoblast cell line TK6 was studied in clones surviving 36 generations after exposure to accelerated 56Fe ions. Clones were assayed for 20 characteristics, including chromosome aberrations, plating efficiency, apoptosis, cell cycle distribution, response to a second irradiation, and mutant frequency at two loci. The primary effect of the 56Fe-ion exposure on the surviving clones was a significant increase in the frequency of unstable chromosome aberrations compared to the very low spontaneous frequency, along with an increase in the phenotypic complexity of the unstable clones. The radiation-induced increase in the frequency of unstable chromosome aberrations was much greater than that observed previously in clones of the related cell line, WTK1, which in comparison to the TK6 cell line expresses an increased radiation resistance, a mutant TP53 protein, and an increased frequency of spontaneous unstable chromosome aberrations. The characteristics of the unstable clones of the two cell lines also differed. Most of the TK6 clones surviving exposure to 56Fe ions showed unstable cytogenetic abnormalities, while the phenotype of the WTK1 clones was more diverse. The results underscore the importance of genotype in the characteristics of instability after radiation exposure.

  14. Effects of lipopolysaccharide on 56Fe-particle radiation-induced impairment of synaptic plasticity in the mouse hippocampus.

    PubMed

    Vlkolinský, Roman; Krucker, Thomas; Smith, Anna L; Lamp, Tyra C; Nelson, Gregory A; Obenaus, Andre

    2007-10-01

    Space radiation, including high-mass, high-Z, high-energy particles (HZE; e.g. (56)Fe), represents a significant health risk for astronauts, and the central nervous system (CNS) may be a vulnerable target. HZE-particle radiation may directly affect neuronal function, or during immunological challenge, it may alter immune system-to-CNS communication. To test these hypotheses, we exposed mice to accelerated iron particles ((56)Fe; 600 MeV/nucleon; 1, 2, 4 Gy; brain only) and 1 month later prepared hippocampal slices to measure the effects of radiation on neurotransmission and synaptic plasticity in CA1 neurons. In a model of immune system-to-CNS communication, these electrophysiological parameters were measured in irradiated mice additionally challenged with the peripheral immunological stressor lipopolysaccharide (LPS) injected intraperitoneally 4 h before the slice preparation. Exposure to (56)Fe particles alone increased dendritic excitability and inhibited plasticity. In control mice (0 Gy), LPS treatment also inhibited synaptic plasticity. Paradoxically, in mice exposed to 2 Gy, the LPS treatment restored synaptic plasticity to levels similar to those found in controls (0 Gy, no LPS). Our results indicate that HZE-particle radiation alters normal electrophysiological properties of the CNS and the hippocampal response to LPS. PMID:17903042

  15. Long-term changes in amphetamine-induced reinforcement and aversion in rats following exposure to 56Fe particle

    NASA Technical Reports Server (NTRS)

    Rabin, B. M.; Joseph, J. A.; Shukitt-Hale, B.

    2003-01-01

    Exposing rats to heavy particles produces alterations in the functioning of dopaminergic neurons and in the behaviors that depend upon the integrity of the dopaminergic system. Two of these dopamine-dependent behaviors include amphetamine-induced reinforcement, measure using the conditioned place preference procedure, and amphetamine-induced reinforcement, measured using the conditioned place preference procedure, and amphetamine-induced aversion, measured using the conditioned taste aversion. Previous research has shown that exposing rats to 1.0 Gy of 1GeV/n 56Fe particles produced a disruption of an amphetamine-induced taste aversion 3 days following exposure, but produced an apparent enhancement of the aversion 112 days following exposure. The present experiments were designed to provide a further evaluation of these results by examining taste aversion learning 154 days following exposure to 1.0 Gy 56Fe particles and to establish the convergent validity of the taste aversion results by looking at the effects of exposure on the establishment of an amphetamine-induced conditioned place preference 3, 7, and 16 weeks following irradiation. The taste aversion results failed to confirm the apparent enhancement of the amphetamine-induced CTA observed in the prior experiment. However, exposure to 56Fe particles prevented the acquisition of amphetamine-induced place preference at all three-time intervals. The results are interpreted as indicating that exposure to heavy particles can produce long-term changes in behavioral functioning. c2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

  16. Long-term changes in amphetamine-induced reinforcement and aversion in rats following exposure to 56Fe particle

    NASA Astrophysics Data System (ADS)

    Rabin, B. M.; Joseph, J. A.; Shukitt-Hale, B.

    Exposing rats to heavy particles produces alterations in the functioning of dopaminergic neurons and in the behaviors that depend upon the integrity of the dopaminergic system. Two of these dopamine-dependent behaviors include amphetamine-induced reinforcement, measure using the conditioned place preference procedure, and amphetamine-induced reinforcement, measured using the conditioned place preference procedure, and amphetamine-induced aversion, measured using the conditioned taste aversion. Previous research has shown that exposing rats to 1.0 Gy of 1GeV/n 56Fe particles produced a disruption of an amphetamine-induced taste aversion 3 days following exposure, but produced an apparent enhancement of the aversion 112 days following exposure. The present experiments were designed to provide a further evaluation of these results by examining taste aversion learning 154 days following exposure to 1.0Gy 56Fe particles and to establish the convergent validity of the taste aversion results by looking at the effects of exposure on the establishment of an amphetamine-induced conditioned place preference 3, 7, and 16 weeks following irradiation. The taste aversion results failed to confirm the apparent enhancement of the amphetamine-induced CTA observed in the prior experiment. However, exposure to 56Fe particles prevented the acquisition of amphetamine-induced place preference at all three-time intervals. The results are interpreted as indicating that exposure to heavy particles can produce long-term changes in behavioral functioning.

  17. Induction of genomic instability after an acute whole-body exposure of mice to 56Fe ions

    NASA Astrophysics Data System (ADS)

    Rithidech, Kanokporn; Supanpaiboon, Wisa; Whorton, Elbert

    Different types of galactic cosmic rays (GCR) are present in space and have large mass and energy (HZE particles). Among these, stripped 56 Fe ions are of major concern. Although HZE particles are approximately 1% of GCR, their contribution to health risk could be significant because of (1) their high linear energy transfer (LET) resulting in a larger amount of energy being deposited in the hit cells, and (2) the lack of information on the effectiveness of these particles in cancer induction. To better protect astronauts in space environments, it is essential that we improve our understanding of the 56 Fe-ion-induced damage associated with the increased risk of late occurring diseases (such as cancer). It has been well established that acute myeloid leukemia (AML) is one of the major malignancies associated with exposure to ionizing radiation in both human beings and in mice. It is therefore one of the most important cancers related to space flights. For these reasons, it is important to investigate 56 Fe ion-induced damage in in vivo systems, especially in those cells that are known to be at risk for health problems associated with radiation, such as hematopoietic cells, the known target cell for radiation-induced leukemia. Since in vivo studies of humans are not possible, animal studies are critically important. It has been widely suggested that elevation of delayed chromosomal damage (normally known as genomic instability) is associated with cancer risk. We therefore determined dose-response relationships for the frequencies of micronuclei (MN) in mouse blood erythrocytes as a measure of both initial radiation damage and the induction of genomic instability. The frequencies of MN were measured in mature normochromatic-erythrocytes (MN-NCEs) and immature polychromatic-erythrocytes (MN-PCEs). These measurements were made as a function of radiation dose, radiation quality, time after irradiation and the genetic background of exposed mice. Blood samples were

  18. Fusion of 48Ti+58Fe and 58Ni+54Fe below the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Stefanini, A. M.; Montagnoli, G.; Corradi, L.; Courtin, S.; Bourgin, D.; Fioretto, E.; Goasduff, A.; Grebosz, J.; Haas, F.; Mazzocco, M.; Mijatović, T.; Montanari, D.; Pagliaroli, M.; Parascandolo, C.; Scarlassara, F.; Strano, E.; Szilner, S.; Toniolo, N.; Torresi, D.

    2015-12-01

    Background: No data on the fusion excitation function of 48Ti+58Fe in the energy region near the Coulomb barrier existed prior to the present work, while fusion of 58Ni+54Fe was investigated in detail some years ago, down to very low energies, and clear evidence of fusion hindrance was noticed at relatively high cross sections. 48Ti and 58Fe are soft and have a low-lying quadrupole excitation lying at ≈800 -900 keV only. Instead, 58Ni and 54Fe have a closed shell (protons and neutrons, respectively) and are rather rigid. Purpose: We aim to investigate (1) the possible influence of the different structures of the involved nuclei on the fusion excitation functions far below the barrier and, in particular, (2) whether hindrance is observed in 48Ti+58Fe , and to compare the results with current coupled-channels models. Methods: 48Ti beams from the XTU Tandem accelerator of INFN-Laboratori Nazionali di Legnaro were used. The experimental setup was based on an electrostatic beam separator, and fusion-evaporation residues (ERs) were detected at very forward angles. Angular distributions of ERs were measured. Results: Fusion cross sections of 48Ti+58Fe have been obtained in a range of nearly six orders of magnitude around the Coulomb barrier, down to σ ≃2 μ b . The sub-barrier cross sections of 48Ti+58Fe are much larger than those of 58Ni+54Fe . Significant differences are also observed in the logarithmic derivatives and astrophysical S factors. No evidence of hindrance is observed, because coupled-channels calculations using a standard Woods-Saxon potential are able to reproduce the data in the whole measured energy range. Analogous calculations for 58Ni+54Fe predict clearly too large cross sections at low energies. The two fusion barrier distributions are wide and display a complex structure that is only qualitatively fit by calculations. Conclusions: It is pointed out that all these different trends originate from the dissimilar low-energy nuclear structures of

  19. Apolipoprotein E Genotype-Dependent Paradoxical Short-Term Effects of {sup 56}Fe Irradiation on the Brain

    SciTech Connect

    Haley, Gwendolen E.; Villasana, Laura; Dayger, Catherine; Davis, Matthew J.; Raber, Jacob

    2012-11-01

    Purpose: In humans, apolipoprotein E (apoE) is encoded by three major alleles ({epsilon}2, {epsilon}3, and {epsilon}4) and, compared to apoE3, apoE4 increases the risk of developing Alzheimer disease and cognitive impairments following various environmental challenges. Exposure to irradiation, including that of {sup 56}Fe, during space missions poses a significant risk to the central nervous system, and apoE isoform might modulate this risk. Methods and Materials: We investigated whether apoE isoform modulates hippocampus-dependent cognitive performance starting 2 weeks after {sup 56}Fe irradiation. Changes in reactive oxygen species (ROS) can affect cognition and are induced by irradiation. Therefore, after cognitive testing, we assessed hippocampal ROS levels in ex vivo brain slices, using the ROS-sensitive fluorescent probe, dihydroethidium (DHE). Brain levels of 3-nitrotyrosine (3-NT), CuZn superoxide dismutase (CuZnSOD), extracellular SOD, and apoE were assessed using Western blotting analysis. Results: In the water maze, spatial memory retention was impaired by irradiation in apoE2 and apoE4 mice but enhanced by irradiation in apoE3 mice. Irradiation reduced DHE-oxidation levels in the enclosed blade of the dentate gyrus and levels of 3-NT and CuZnSOD in apoE2 but not apoE3 or apoE4 mice. Finally, irradiation increased apoE levels in apoE3 but not apoE2 or apoE4 mice. Conclusions: The short-term effects of {sup 56}Fe irradiation on hippocampal ROS levels and hippocampus-dependent spatial memory retention are apoE isoform-dependent.

  20. Beta decay of nuclides 56Fe, 62Ni, 64Ni and 68Ni in the crust of magnetars

    NASA Astrophysics Data System (ADS)

    Liu, Jing-Jing; Kang, Xiao-Ping; Hao, Liang-Huan; Feng, Hao; Liu, Dong-Mei; Li, Chang-Wei; Zeng, Xiang-Ming

    2016-11-01

    By introducing the Dirac δ-function and Pauli exclusion principle in the presence of superstrong magnetic fields (SMFs), we investigate the influence of SMFs on beta decay and the change rates of electron fraction (CREF) of nuclides 56Fe, 62Ni, 64Ni and 68Ni in magnetars, which are powered by magnetic field energy. We find that the magnetic fields have a great influence on the beta decay rates, and the beta decay rates can decrease by more than six orders of magnitude in the presence of SMFs. The CREF also decreases by more than seven orders of magnitude in the presence of SMFs.

  1. Effect of behavioral testing on spine density of basal dendrites in the CA1 region of the hippocampus modulated by (56)Fe irradiation.

    PubMed

    Raber, Jacob; Allen, Antiño R; Weber, Sydney; Chakraborti, Ayanabha; Sharma, Sourabh; Fike, John R

    2016-04-01

    A unique feature of the space radiation environment is the presence of high-energy charged particles, including (56)Fe ions, which can present a significant hazard to space flight crews during and following a mission. (56)Fe irradiation-induced cognitive changes often involve alterations in hippocampal function. These alterations might involve changes in spine morphology and density. In addition to irradiation, performing a cognitive task can also affect spine morphology. Therefore, it is often hard to determine whether changes in spine morphology and density are due to an environmental challenge or group differences in performance on cognitive tests. In this study, we tested the hypothesis that the ability of exploratory behavior to increase specific measures of hippocampal spine morphology and density is affected by (56)Fe irradiation. In sham-irradiated mice, exploratory behavior increased basal spine density in the CA1 region of the hippocampus and the enclosed blade of the dentate gyrus. These effects were not seen in irradiated mice. In addition, following exploratory behavior, there was a trend toward a decrease in the percent stubby spines on apical dendrites in the CA3 region of the hippocampus in (56)Fe-irradiated, but not sham-irradiated, mice. Other hippocampal regions and spine measures affected by (56)Fe irradiation showed comparable radiation effects in behaviorally naïve and cognitively tested mice. Thus, the ability of exploratory behavior to alter spine density and morphology in specific hippocampal regions is affected by (56)Fe irradiation. PMID:26801826

  2. Production of radon and thorium isotopes near N=126 shell closure in 48Ca and 54Cr induced fusion reactions on 162Dy

    NASA Astrophysics Data System (ADS)

    Mayorov, Dmitriy; Werke, Tyler; Alfonso, Marisa; Folden, Charles

    2012-03-01

    Production of spherical evaporation residues (EVRs) near N=126 shell in 48Ca and 54Cr induced reactions on a 162Dy target was investigated at the Texas A&M University Cyclotron Institute using the vacuum separator MARS. For the 54Cr+162Dy reaction, only upper limits for the 4n exit-channel cross section were measured; this can be attributed to a sizably increased fissility of the 216Th compound nucleus relative to 210Rn formed in the 48Ca bombardment. A factor of > 7300 separates the production cross sections of the 4n EVRs from each reaction. A semi-empirical estimate of the lower limit on the fusion probability, PCN, ratio between the two heavy ion projectiles is PCN(48Ca+162Dy)/PCN(54Cr+162Dy) > 1.2. Investigation of spherical nuclei produced by heavy ion fusion reactions is of current interest due to efforts to synthesize superheavy nuclei near Z=120, N=184 nucleon shells. EVRs produced near the N=126 shell closure have previously revealed surprisingly low survival probabilities despite stabilization from shell effects. Similarly, enhancement of the fission channel in the de-excitation cascade of 210Rn and 216Th is observed in this work and this result can be well modeled by the inclusion of collective effects into the statistical decay of excited nuclei calculations. These results suggest that cross sections for production of superheavy nuclei near predicted Z=120, N=184 closed shells may be small regardless of the anticipated strong shell effects.

  3. Possible production of actinide spontaneous fission activities in damped collisions of /sup 209/Bi+/sup 56/Fe

    SciTech Connect

    Viola, V.E. Jr.; Mignerey, A.C.; Breuer, H.; Wolf, K.L.; Glagola, B.G.; Wilcke, W.W.; Schroeder, W.U.; Huizenga, J.R.; Hilscher, D.; Birkelund, J.R.

    1980-07-01

    Results of recent nuclear reaction studies on the /sup 209/Bi+/sup 56/Fe system are analyzed in order to investigate the cross sections for production of spontaneously fissioning species with 90 < or = Z < or = 100. This reaction is nearly identical to those used as the basis for identification of new elements with Z=104 --107, reported to be spontaneous fission emitters. Evidence is presented which indicates that actinide elements are formed with primary yields of the order of millibarns in strongly damped collisions of 464 MeV /sup 56/Fe with /sup 209/Bi. Although strongly depleted by fission competition, final yields of possible spontaneous fission activities /sup 240en-dash244/Am/sup f/, /sup 234en-dash238/Cf, and /sup 242en-dash246/Fm are calculated to be of the order of nanobarns. These results suggest that the spontaneous fission activities observed in similar reactions may be due at least in part to fission decay of actinide elements rather than elements with Z=104 --107.

  4. Embryonic effects transmitted by male mice irradiated with 512 MeV/u {sup 56}Fe nuclei

    SciTech Connect

    Wiley, L.M.; Van Beek, M.E.A.B.; Raabe, O.G.

    1994-06-01

    High-energy, high-charge nuclei may contribute substantially to the yearly equivalent dose in space flight from galactic cosmic radiation (GCR) at solar minimum. The largest single heavy-ion component is {sup 56}Fe. We used the mouse embryo chimera assay to test 512 MeV/u {sup 56}Fe nuclei for effects on the rate of proliferation of embryonic cells transmitted by sperm from irradiated mice. Male CD1 mice were acutely irradiated with 0.01, 0.05, or 0.1 Gy (LET, 184 keV/{mu}m; fluence, 3.5 x 10{sup 4}-3.3 x 10{sup 5} nuclei/cm{sup 2}; average dose rate, 0.02 Gy/min) at the Lawrence Berkeley Laboratory BEVATRON/BEVALAC Facility in Berkeley, CA. Irradiated males were bred weekly for 7 weeks to nonirradiated females and their four-cell embryos were paired with control embryos, forming aggregation chimeras. After 30-35 h of culture, chimeras were dissociated to obtain {open_quotes}proliferation ratios{close_quotes} (number of cells contributed by the embryo from the irradiated male/total number of cells in the chimera). Significant dose-dependent decreases in proliferation ratios were obtained across all three dose groups for postirradiation week 2 (P < 0.05 to P < 0.003). The 0.01- and 0.05-Gy dose groups also produced significant decreases in proliferation ratios for postirradiation week 1 (P < 0.05 to P < 0.01) and the 0.05-Gy dose group produced significant decreases in proliferation ratios for postirradiation week 6 (P < 0.05). Postirradiation weeks 1, 2 and 6 correspond to irradiation of epididymal sperm, testicular spermatids and spermatogonia, respectively. We calculate that only about 5% of sperm in the 0.1-Gy, 2.5% in the 0.05-Gy and 0.5% in the 0.01-Gy dose groups sustained direct hits from {sup 56}Fe nuclei. However, up to 47% of sperm during postirradiation weeks 1 and 2 transmitted proliferation ratios that were at or below one standard deviation from control mean proliferation ratios. 26 refs., 4 figs., 10 tabs.

  5. Dynamic characteristics of 56Fe-particle radiation-induced alterations in the rat brain: magnetic resonance imaging and histological assessments.

    PubMed

    Huang, Lei; Smith, Anna; Badaut, Jerome; Obenaus, Andre

    2010-06-01

    56Fe-particle radiation-induced brain disturbances are a major health concern for astronauts during long-term space travel. The present study investigated temporal modifications within the brain after 56Fe-particle exposure using in vivo magnetic resonance imaging (MRI) correlated to histology. Male Sprague-Dawley rats were exposed to brain-only 56Fe-particle radiation. MRI including T2-weighted, diffusion-weighted, pre/postcontrast enhanced T1-weighted imaging was performed 0.25-18 months after exposure. T2 relaxation times and the apparent diffusion coefficient were quantified within the hippocampus, entorhinal cortex, retrosplenial cortex and thalamus, and correlative histopathology was then performed at each time. In the absence of visible lesions on MR images, the apparent diffusion coefficient and T2 relaxation times revealed 56Fe-particle-induced dynamic changes in all ROIs over the 18-month time course. The patterns of MR changes were spatially similar within the different regions. The temporal alterations in the apparent diffusion coefficient corresponded to the glial cell changes within the brain. Quantitative MRI provides a non-invasive approach to monitor spatio-temporal brain alterations after 56Fe-particle irradiation. The apparent diffusion coefficient appears to be a sensitive metric to reveal ongoing tissue modifications involving multiple cellular components in vivo.

  6. Diverse delayed effects in human lymphoblastoid cells surviving exposure to high-LET (56)Fe particles or low-LET (137)Cs gamma radiation

    NASA Technical Reports Server (NTRS)

    Evans, H. H.; Horng, M. F.; Ricanati, M.; Diaz-Insua, M.; Jordan, R.; Schwartz, J. L.

    2001-01-01

    To obtain information on the origin of radiation-induced genomic instability, we characterized a total of 166 clones that survived exposure to (56)Fe particles or (137)Cs gamma radiation, isolated approximately 36 generations after exposure, along with their respective control clones. Cytogenetic aberrations, growth alterations, responses to a second irradiation, and mutant frequencies at the Na(+)/K(+) ATPase and thymidine kinase loci were determined. A greater percentage of clones that survived exposure to (56)Fe particles exhibited instability (defined as clones showing one or more outlying characteristics) than in the case of those that survived gamma irradiation. The phenotypes of the unstable clones that survived exposure to (56)Fe particles were also qualitatively different from those of the clones that survived gamma irradiation. A greater percentage (20%) of the unstable clones that survived gamma irradiation than those that survived exposure to (56)Fe particles (4%) showed an altered response to the second irradiation, while an increase in the percentage of clones that had an outlying frequency of ouabain-resistant and thymidine kinase mutants was more evident in the clones exposed to (56)Fe particles than in those exposed to gamma rays. Growth alterations and increases in dicentric chromosomes were found only in clones with more than one alteration. These results underscore the complex nature of genomic instability and the likelihood that radiation-induced genomic instability arises from different original events.

  7. Elevated plus-maze performance of Fischer-344 rats as a function of age and of exposure to 56Fe particles

    NASA Astrophysics Data System (ADS)

    Rabin, Bernard M.; Carrihill-Knoll, Kirsty L.; Carey, Amanda N.; Shukitt-Hale, Barbara; Joseph, James A.; Foster, Brian C.

    The aging process is characterized by a series of changes in neurochemical functioning and in motor and cognitive performance. In addition to changes in cognitive/behavioral performance, aged rats also show an increase in baseline anxiety measured using the elevated plus-maze. Exposure to 56Fe particles, a component of cosmic rays, produces neurochemical and behavioral changes in young animals which are characteristic of aged organisms. The present study was designed to determine the relationships between aging and exposure to 56Fe particles on anxiety. Fischer-344 (F-344), which were 2, 7, 12, and 16 months of age at the time of irradiation, were exposed to 56Fe particles (50 200 cGy). Concordant with previous results, the oldest rats spent less time exploring the open arms of the maze. Exposure to 56Fe particles also produced decreased exploration of the open arms of the plus-maze. The dose needed to produce increased levels of anxiety was a function of age at the time of irradiation. The dose of 56Fe particles needed to produce a decrease in open arm exploration was significantly lower in the rats that were irradiated at 7 and 12 months of age than in the rats irradiated at 2 months of age. These results suggest the possibility that exposing middle-aged astronauts to cosmic rays during exploratory class missions outside the magnetosphere, and the resultant effects on exploration-induced anxiety, may affect their ability to successfully complete mission requirements.

  8. Cross sections for production of 70 discrete-energy gamma rays created by neutron interactions with sup 56 Fe for E sub n to 40 MeV: Tabulated data

    SciTech Connect

    Dickens, J.K.; Todd, J.H.; Larson, D.C.

    1990-09-01

    Inelastic and nonelastic neutron interactions with {sup 56}Fe have been studied for incident neutron energies between 0.8 and 41 MeV. An iron sample isotopically enriched in the mass 56 isotope was used. Gamma rays representing 70 transitions among levels in residual nuclei were identified, and production cross sections were deduced. The reactions studied were {sup 56}Fe(n,n{prime}){sup 56}Fe, {sup 56}Fe(n,p){sup 56}Mn, {sup 56}Fe(n,2n){sup 55}Fe, {sup 56}Fe(n,d + n,np){sup 55}Mn, {sup 56}Fe(n,t + n,nd + n,2np){sup 54}Mn, {sup 56}Fe(n,{alpha}){sup 53}Cr, {sup 56}Fe(n,n{alpha}){sup 52}Cr, and {sup 56}Fe(n,3n){sup 54}Fe. Values obtained for production cross sections as functions of incident neutron energy are presented in tabular form. 38 refs., 7 figs., 12 tabs.

  9. Damage to the photoreceptor cells of the rabbit retina from 56Fe ions: effect of age at exposure, 1

    NASA Technical Reports Server (NTRS)

    Williams, G. R.; Lett, J. T.; Chatterjee, A. (Principal Investigator)

    1996-01-01

    Optic and proximate tissues of New Zealand white (NZW) rabbits at ages (approximately 3.5 years) near the middle of their median lifespan (5-7 years) were given 0.5-3.5 Gy of 465 MeV u-1 56Fe ions in the Bragg plateau region of energy deposition at a linear energy transfer (LET infinity) of 220 +/- 31 keV micrometer-1. Dose-dependent losses of retinal photoreceptor cells (rods) occurred until 1-2 years after irradiation, the period of this interim report. Similar cumulative losses of photoreceptor cells were seen during the period 1-2 years post-irradiation for rabbits given comparable exposures when young (6-9 weeks old). Since losses of photoreceptor cells at early times had not been determined previously, the current experiment, which was designed to simulate the responses of mature astronauts, redressed that deficiency.

  10. Damage to the photoreceptor cells of the rabbit retina from 56Fe ions: effect of age at exposure, 1.

    PubMed

    Williams, G R; Lett, J T

    1996-01-01

    Optic and proximate tissues of New Zealand white (NZW) rabbits at ages (approximately 3.5 years) near the middle of their median lifespan (5-7 years) were given 0.5-3.5 Gy of 465 MeV u-1 56Fe ions in the Bragg plateau region of energy deposition at a linear energy transfer (LET infinity) of 220 +/- 31 keV micrometer-1. Dose-dependent losses of retinal photoreceptor cells (rods) occurred until 1-2 years after irradiation, the period of this interim report. Similar cumulative losses of photoreceptor cells were seen during the period 1-2 years post-irradiation for rabbits given comparable exposures when young (6-9 weeks old). Since losses of photoreceptor cells at early times had not been determined previously, the current experiment, which was designed to simulate the responses of mature astronauts, redressed that deficiency. PMID:11538988

  11. Measurement of 56Fe activity produced in inelastic scattering of neutrons created by cosmic muons in an iron shield.

    PubMed

    Krmar, M; Jovančević, N; Nikolić, D

    2012-01-01

    We report on the study of the intensities of several gamma lines emitted after the inelastic scattering of neutrons in (56)Fe. Neutrons were produced via nuclear processes induced by cosmic muons in the 20tons massive iron cube placed at the Earth's surface and used as a passive shield for the HPGe detector. Relative intensities of detected gamma lines are compared with the results collected in the same iron shield by the use of the (252)Cf neutrons. Assessment against the published data from neutron scattering experiments at energies up to 14MeV is also provided. It allowed us to infer the qualitative information about the average energy of muon-created neutrons in the iron shield.

  12. Exposure to 56Fe Particles Produces Deficits in Spatial Learning and Memory in the Radial Arm Water Maze

    NASA Astrophysics Data System (ADS)

    Shukitt-Hale, Barbara; Miller, Marshall; Carrihill-Knoll, Kirsty; Rabin, Bernard; Joseph, James

    Previous research has shown that radiation exposure, particularly to particles of high energy and charge (HZE particles) which will be encountered on long-term space missions, can adversely affect the ability of rats to perform a variety of behavioral tasks. This outcome has implications for an astronaut's ability to successfully complete requirements associated with these missions. Both aged and irradiated rats display cognitive impairment in tests of spatial learning and memory such as the Morris water maze and the radial arm maze. Therefore, in the present study, we used a combination of these two tests, the 8 arm radial water maze (RAWM), to measure spatial learning in rats which were irradiated at the NSRL with 0, 150cGy, or 200cGy of 56Fe radiation. Following irradiation the rats were shipped to the HNRCA and tested in the RAWM (2-3 months later) for 5 days, 3 trials/day. In this version of the RAWM, there were 4 hidden platforms that the rat needed to locate to successfully solve a trial. Once the rat located a platform, it was allowed to remain there for 15 sec before the platform sank, at which point the rat tried to locate the remaining ones. Reference (entering an arm that never contained the platform) and working (re-entering an arm in which the platform had already been found) memory errors were tabulated. Results showed that the irradiated rats had more reference and working memory errors while learning the maze, particularly on Day 3 of testing. Additionally, they utilized non-spatial strategies to solve the RAWM task whereas the control animals used spatial strategies. These results show that irradiation with 56Fe high-energy particles produces age-like decrements in cognitive behavior that may impair the ability of astronauts to perform critical tasks during long-term space travel beyond the magnetosphere. Supported by USDA Intramural and N.A.S.A. Grant NNX08AM66G

  13. Exposure to 56Fe irradiation accelerates normal brain aging and produces deficits in spatial learning and memory

    NASA Astrophysics Data System (ADS)

    Shukitt-Hale, Barbara; Casadesus, Gemma; Carey, Amanda N.; Rabin, Bernard M.; Joseph, James A.

    Previous studies have shown that radiation exposure, particularly to particles of high energy and charge (HZE particles) such as 56Fe, produces deficits in spatial learning and memory. These adverse behavioral effects are similar to those seen in aged animals. It is possible that these shared effects may be produced by the same mechanism. For example, an increased release of reactive oxygen species, and the subsequent oxidative stress and inflammatory damage caused to the central nervous system, is likely responsible for the deficits seen in aging and following irradiation. Therefore, dietary antioxidants, such as those found in fruits and vegetables, could be used as countermeasures to prevent the behavioral changes seen in these conditions. Both aged and irradiated rats display cognitive impairment in tests of spatial learning and memory such as the Morris water maze and the radial arm maze. These rats have decrements in the ability to build spatial representations of the environment, and they utilize non-spatial strategies to solve tasks. Furthermore, they show a lack of spatial preference, due to a decline in the ability to process or retain place (position of a goal with reference to a “map” provided by the configuration of numerous cues in the environment) information. These declines in spatial memory occur in measures dependent on both reference and working memory, and in the flexibility to reset mental images. These results show that irradiation with 56Fe high-energy particles produces age-like decrements in cognitive behavior that may impair the ability of astronauts, particularly middle-aged ones, to perform critical tasks during long-term space travel beyond the magnetosphere.

  14. Combined exposure to protons and 56Fe leads to overexpression of Il13 and reactivation of repetitive elements in the mouse lung

    NASA Astrophysics Data System (ADS)

    Nzabarushimana, Etienne; Prior, Sara; Miousse, Isabelle R.; Pathak, Rupak; Allen, Antiño R.; Latendresse, John; Olsen, Reid H. J.; Raber, Jacob; Hauer-Jensen, Martin; Nelson, Gregory A.; Koturbash, Igor

    2015-11-01

    Interest in deep space exploration underlines the needs to investigate the effects of exposure to combined sources of space radiation. The lung is a target organ for radiation, and exposure to protons and heavy ions as radiation sources may lead to the development of degenerative disease and cancer. In this study, we evaluated the pro-fibrotic and epigenetic effects of exposure to protons (150 MeV/nucleon, 0.1 Gy) and heavy iron ions (56Fe, 600 MeV/nucleon, 0.5 Gy) alone or in combination (protons on Day 1 and 56Fe on Day 2) in C57BL/6 male mice 4 weeks after irradiation. Exposure to 56Fe, proton or in combination, did not result in histopathological changes in the murine lung. At the same time, combined exposure to protons and 56Fe resulted in pronounced molecular alterations in comparison with either source of radiation alone. Specifically, we observed a substantial increase in the expression of cytokine Il13, loss of expression of DNA methyltransferase Dnmt1, and reactivation of LINE-1, SINE B1 retrotransposons, and major and minor satellites. Given the deleterious potential of the observed effects that may lead to development of chronic lung injury, pulmonary fibrosis, and cancer, future studies devoted to the investigation of the long-term effects of combined exposures to proton and heavy ions are clearly needed.

  15. Fibroma induction in rat skin following single or multiple doses of 1.0 GeV/nucleon 56Fe ions from the Brookhaven Alternating Gradient Synchrotron (AGS)

    NASA Technical Reports Server (NTRS)

    Burns, F. J.; Zhao, P.; Xu, G.; Roy, N.; Loomis, C.

    2001-01-01

    Rat skin was exposed to the plateau region of the 1.0 GeV/nucleon 56Fe beam at the Brookhaven AGS. Rats were irradiated or not with single of split doses of 56Fe or argon; some 56Fe-exposed rats were fed 250 ppm retinyl acetate continuously in the lab chow beginning 1 week before irradiation. All lesions were noted, photographed and identified for eventual histological diagnosis. The preponderance of the tumors so far are fibromas. The data show that single doses of 56Fe ions are 2 or 3 fold more effective than argon in producing tumors at 4.5 Gy but are about equally effective at 3.0 Gy and 9.0 Gy. The presence of 250 ppm retinyl acetate in the lab chow reduced the incidence of tumors by about 50-60% in comparison to groups exposed only to the radiation. These are preliminary findings based on only about one-fourth the eventual number of tumors expected.

  16. Fibroma induction in rat skin following single or multiple doses of 1.0 GeV/nucleon 56Fe ions from the Brookhaven Alternating Gradient Synchrotron (AGS).

    PubMed

    Burns, F J; Zhao, P; Xu, G; Roy, N; Loomis, C

    2001-01-01

    Rat skin was exposed to the plateau region of the 1.0 GeV/nucleon 56Fe beam at the Brookhaven AGS. Rats were irradiated or not with single of split doses of 56Fe or argon; some 56Fe-exposed rats were fed 250 ppm retinyl acetate continuously in the lab chow beginning 1 week before irradiation. All lesions were noted, photographed and identified for eventual histological diagnosis. The preponderance of the tumors so far are fibromas. The data show that single doses of 56Fe ions are 2 or 3 fold more effective than argon in producing tumors at 4.5 Gy but are about equally effective at 3.0 Gy and 9.0 Gy. The presence of 250 ppm retinyl acetate in the lab chow reduced the incidence of tumors by about 50-60% in comparison to groups exposed only to the radiation. These are preliminary findings based on only about one-fourth the eventual number of tumors expected.

  17. Induction of genomic instability in TK6 human lymphoblasts exposed to 137Cs gamma radiation: comparison to the induction by exposure to accelerated 56Fe particles

    NASA Technical Reports Server (NTRS)

    Evans, Helen H.; Horng, Min-Fen; Ricanati, Marlene; Diaz-Insua, M.; Jordan, Robert; Schwartz, Jeffrey L.

    2003-01-01

    The induction of genomic instability in TK6 human lymphoblasts by exposure to (137)Cs gamma radiation was investigated by measuring the frequency and characteristics of unstable clones isolated approximately 36 generations after exposure. Clones surviving irradiation and control clones were analyzed for 17 characteristics including chromosomal aberrations, growth defects, alterations in response to a second irradiation, and mutant frequencies at the thymidine kinase and Na(+)/K(+) ATPase loci. Putative unstable clones were defined as those that exhibited a significant alteration in one or more characteristics compared to the controls. The frequency and characteristics of the unstable clones were compared in clones exposed to (137)Cs gamma rays or (56)Fe particles. The majority of the unstable clones isolated after exposure to either gamma rays or (56)Fe particles exhibited chromosomal instability. Alterations in growth characteristics, radiation response and mutant frequencies occurred much less often than cytogenetic alterations in these unstable clones. The frequency and complexity of the unstable clones were greater after exposure to (56)Fe particles than to gamma rays. Unstable clones that survived 36 generations after exposure to gamma rays exhibited increases in the incidence of dicentric chromosomes but not of chromatid breaks, whereas unstable clones that survived 36 generations after exposure to (56)Fe particles exhibited increases in both chromatid and chromosome aberrations.

  18. Interaction of Electron Neutrinos with {sup 56}Fe in the LSD for E{sub {nu}{sub e}} {<=} 50 MeV

    SciTech Connect

    Gaponov, Yu.V.; Ryazhskaya, O.G.; Semenov, S.V.

    2004-11-01

    The neutrino pulses detected by the LSD (Liquid Scintillator Detector) on February 23, 1987, are analyzed on the basis of a two-stage model of supernova explosion. The number of events due to the electron-neutrino interaction with {sup 56}Fe in the LSD is calculated. The obtained number of signals is in agreement with experimental data.

  19. Effects of 28Si Ions, 56Fe Ions, and Protons on the Induction of Murine Acute Myeloid Leukemia and Hepatocellular Carcinoma

    PubMed Central

    Weil, Michael M.; Ray, F. Andrew; Genik, Paula C.; Yu, Yongjia; McCarthy, Maureen; Fallgren, Christina M.; Ullrich, Robert L.

    2014-01-01

    Estimates of cancer risks posed to space-flight crews by exposure to high atomic number, high-energy (HZE) ions are subject to considerable uncertainty because epidemiological data do not exist for human populations exposed to similar radiation qualities. We assessed the carcinogenic effects of 300 MeV/n 28Si or 600 MeV/n 56Fe ions in a mouse model for radiation-induced acute myeloid leukemia and hepatocellular carcinoma. C3H/HeNCrl mice were irradiated with 0.1, 0.2, 0.4, or 1 Gy of 300 MeV/n 28Si ions, 600 MeV/n 56Fe ions or 1 or 2 Gy of protons simulating the 1972 solar particle event (1972SPE) at the NASA Space Radiation Laboratory. Additional mice were irradiated with 137Cs gamma rays at doses of 1, 2, or 3 Gy. All groups were followed until they were moribund or reached 800 days of age. We found that 28Si or 56Fe ions do not appear to be substantially more effective than gamma rays for the induction of acute myeloid leukemia. However, 28Si or 56Fe ion irradiated mice had a much higher incidence of hepatocellular carcinoma than gamma ray irradiated or proton irradiated mice. These data demonstrate a clear difference in the effects of these HZE ions on the induction of leukemia compared to solid tumors, suggesting potentially different mechanisms of tumorigenesis. Also seen in this study was an increase in metastatic hepatocellular carcinoma in the 28Si and 56Fe ion irradiated mice compared with those exposed to gamma rays or 1972SPE protons, a finding with important implications for setting radiation exposure limits for space-flight crew members. PMID:25126721

  20. Exposure to 56Fe-particle radiation accelerates electrophysiological alterations in the hippocampus of APP23 transgenic mice.

    PubMed

    Vlkolinsky, R; Titova, E; Krucker, T; Chi, B B; Staufenbiel, M; Nelson, G A; Obenaus, A

    2010-03-01

    Abstract An unavoidable complication of space travel is exposure to high-charge, high-energy (HZE) particles. In animal studies, exposure of the CNS to HZE-particle radiation leads to neurological alterations similar to those seen in aging or Alzheimer's disease. In this study we examined whether HZE-particle radiation accelerated the age-related neuronal dysfunction that was previously described in transgenic mice overexpressing human amyloid precursor protein (APP). These APP23 transgenic mice exhibit age-related behavioral abnormalities and deficits in synaptic transmission. We exposed 7-week-old APP23 transgenic males to brain-only (56)Fe-particle radiation (600 MeV/nucleon; 1, 2, 4 Gy) and recorded synaptic transmission in hippocampal slices at 2, 6, 9, 14 and 18-24 months. We stimulated Schaeffer collaterals and recorded field excitatory postsynaptic potentials (fEPSP) and population spikes (PS) in CA1 neurons. Radiation accelerated the onset of age-related fEPSP decrements recorded at the PS threshold from 14 months of age to 9 months and reduced synaptic efficacy. At 9 months, radiation also reduced PS amplitudes. At 6 months, we observed a temporary deficit in paired-pulse inhibition of the PS at 2 Gy. Radiation did not significantly affect survival of APP23 transgenic mice. We conclude that irradiation of the brain with HZE particles accelerates Alzheimer's disease-related neurological deficits.

  1. Precision Measurement of 56Fe(n,n γ) Cross Sections Using 14.1 MeV Neutrons

    NASA Astrophysics Data System (ADS)

    Wang, Haoyu; Koltick, David

    2016-03-01

    Integral production cross sections for 846.8 keV and 1238.3 keV prompt gamma rays from 14.1 MeV neutrons interactions on 56Fe are reported. The experimental technique takes advantage of the 1.5 nanosecond coincidence timing resolution between the neutron production time and the gamma ray detection time to reject noise, together with the large 30% solid angle gamma ray coverage. The scattering angle coverage with respect to the neutron beam direction extends from 60 degrees to 120 degrees. The neutron flux is measured using the detected associated alpha-particle from the D-T fusion reaction produced using an associated particle neutron generator. Present cross section measurements using other techniques with limited timing resolution and solid angle coverage are in agreement at neutron energies lower than 6 MeV. At higher neutron energies reported results can disagree by more than 20%. The more accurate technique used in these measurements can distinguish between the differences in the present reported results at higher neutron energies. The author would like to thank TechSource, Inc. and Advanced Physics Technologies, LLC. for their support in this work.

  2. Reaction mechanism coexistence in the 123 MeV {sup 19}F+{sup 56}Fe reaction

    SciTech Connect

    Brondi, A.; Kildir, M.; La Rana, G.; Moro, R.; Vardaci, E.; Pirrone, S.; Porto, F.; Sambataro, S.; Politi, G.; Figuera, P.

    1996-10-01

    Mass and charge identified ejectiles, spanning from {sup 11}B to {sup 22}Ne, have been detected in the 123 MeV {sup 19}F+{sup 56}Fe reaction. The coexistence of deep inelastic collision (DIC) and incomplete fusion (IF) mechanisms has been observed. The shape of the energy spectra and their behavior with angle allowed us to identify two components: The less dissipative one was dominating near the grazing angle. For both components experimental optimum {ital Q} values were derived. Two approaches based on the sum rule (SR) model of Wilczy{acute n}ski were used to calculate DIC and IF contributions to the complex fragment cross sections. Both prescriptions fit reasonably well experimental ejectile cross sections and {ital Q} optimum values. Results of the present investigation support the idea that the DIC can be treated on the same footing as IF in the SR model once the first process is confined in an inner angular momentum window, starting from the maximum fusion angular momentum, with respect to quasielastic processes. {copyright} {ital 1996 The American Physical Society.}

  3. Analysis of chromosomal damage after in vivo exposure to 56Fe ions by means of mFISH and micronucleus methods

    NASA Astrophysics Data System (ADS)

    Rithidech, Kanokporn Noy; Supanpaiboon, Wisa; Honikel, Louise; Whorton, Elbert B.

    In this study, we examined the induction of chromosomal damage at day 7 following whole-body exposure of male CBA/CaJ mice to different doses of 1 GeV/amu 56Fe ions (0, 0.1, 0.5, and 1.0 Gy) or 137Cs γ rays as the reference radiation (0, 0.5, 1.0, and 3.0 Gy, using a GammaCell40). Two cytogenetic assays were used to evaluate dose-response relationships for the induction of chromosomal damage. These include: (1) the whole-genome multi-color fluorescence in situ hybridization (mFISH) technique to examine chromosomal damage in metaphases prepared from bone marrow (BM) cells and (2) the mouse in vivo micronucleus (MN) assay to evaluate chromosomal damage (induced in the bone marrow) in blood erythrocytes. By means of the mFISH method, we detected all types of aberrations from mice exposed to either 56Fe ions or 137Cs γ rays. These were translocations (Robertsonian, reciprocal and incomplete one-way types), dicentrics and breaks (both chromatid- and chromosome-types). Each type of radiation-induced significant dose-dependent increases ( ANOVA, p < 0.01) in the frequencies of chromosomal damage (including the numbers of abnormal cells). Our data indicated that the 56Fe ions were more effective (per unit dose) than 137Cs γ rays in inducing damage: about four times for abnormal cells or breaks (both chromatid- and chromosome-types), and 1.6 times for exchanges (all types). Complex chromosome rearrangements were also found in BM cells of mice exposed to 1.0 Gy of 56Fe ions or 3.0 Gy of 137Cs γ rays, but their frequencies were low. Moreover, the frequencies of complex exchanges found at day 7 after exposure of mice to 1.0 Gy of 56Fe ions or 3.0 Gy of 137Cs γ rays were similar. By means of the blood MN assay, we detected dose-dependent increases in the frequencies of MN in normochromatic erythrocytes (NCE or mature red blood cells) at day 7 following in vivo exposure to 56Fe ions or 137Cs γ rays. In contrast, only a slight increase in the frequency of MN in

  4. 56Fe particle exposure results in a long-lasting increase in a cellular index of genomic instability and transiently suppresses adult hippocampal neurogenesis in vivo

    NASA Astrophysics Data System (ADS)

    DeCarolis, Nathan A.; Rivera, Phillip D.; Ahn, Francisca; Amaral, Wellington Z.; LeBlanc, Junie A.; Malhotra, Shveta; Shih, Hung-Ying; Petrik, David; Melvin, Neal R.; Chen, Benjamin P. C.; Eisch, Amelia J.

    2014-07-01

    The high-LET HZE particles from galactic cosmic radiation pose tremendous health risks to astronauts, as they may incur sub-threshold brain injury or maladaptations that may lead to cognitive impairment. The health effects of HZE particles are difficult to predict and unfeasible to prevent. This underscores the importance of estimating radiation risks to the central nervous system as a whole as well as to specific brain regions like the hippocampus, which is central to learning and memory. Given that neurogenesis in the hippocampus has been linked to learning and memory, we investigated the response and recovery of neurogenesis and neural stem cells in the adult mouse hippocampal dentate gyrus after HZE particle exposure using two nestin transgenic reporter mouse lines to label and track radial glia stem cells (Nestin-GFP and Nestin-CreERT2/R26R:YFP mice, respectively). Mice were subjected to 56Fe particle exposure (0 or 1 Gy, at either 300 or 1000 MeV/n) and brains were harvested at early (24 h), intermediate (7 d), and/or long time points (2-3 mo) post-irradiation. 56Fe particle exposure resulted in a robust increase in 53BP1+ foci at both the intermediate and long time points post-irradiation, suggesting long-term genomic instability in the brain. However, 56Fe particle exposure only produced a transient decrease in immature neuron number at the intermediate time point, with no significant decrease at the long time point post-irradiation. 56Fe particle exposure similarly produced a transient decrease in dividing progenitors, with fewer progenitors labeled at the early time point but equal number labeled at the intermediate time point, suggesting a recovery of neurogenesis. Notably, 56Fe particle exposure did not change the total number of nestin-expressing neural stem cells. These results highlight that despite the persistence of an index of genomic instability, 56Fe particle-induced deficits in adult hippocampal neurogenesis may be transient. These data support

  5. (56)Fe Particle Exposure Results in a Long-Lasting Increase in a Cellular Index of Genomic Instability and Transiently Suppresses Adult Hippocampal Neurogenesis in Vivo.

    PubMed

    DeCarolis, Nathan A; Rivera, Phillip D; Ahn, Francisca; Amaral, Wellington Z; LeBlanc, Junie A; Malhotra, Shveta; Shih, Hung-Ying; Petrik, David; Melvin, Neal; Chen, Benjamin P C; Eisch, Amelia J

    2014-07-01

    The high-LET HZE particles from galactic cosmic radiation pose tremendous health risks to astronauts, as they may incur sub-threshold brain injury or maladaptations that may lead to cognitive impairment. The health effects of HZE particles are difficult to predict and unfeasible to prevent. This underscores the importance of estimating radiation risks to the central nervous system as a whole as well as to specific brain regions like the hippocampus, which is central to learning and memory. Given that neurogenesis in the hippocampus has been linked to learning and memory, we investigated the response and recovery of neurogenesis and neural stem cells in the adult mouse hippocampal dentate gyrus after HZE particle exposure using two nestin transgenic reporter mouse lines to label and track radial glia stem cells (Nestin-GFP and Nestin-CreER(T2)/R26R:YFP mice, respectively). Mice were subjected to (56)Fe particle exposure (0 or 1 Gy, at either 300 or 1000 MeV/n) and brains were harvested at early (24h), intermediate (7d), and/or long time points (2-3mo) post-irradiation. (56)Fe particle exposure resulted in a robust increase in 53BP1+ foci at both the intermediate and long time points post-irradiation, suggesting long-term genomic instability in the brain. However, (56)Fe particle exposure only produced a transient decrease in immature neuron number at the intermediate time point, with no significant decrease at the long time point post-irradiation. (56)Fe particle exposure similarly produced a transient decrease in dividing progenitors, with fewer progenitors labeled at the early time point but equal number labeled at the intermediate time point, suggesting a recovery of neurogenesis. Notably, (56)Fe particle exposure did not change the total number of nestin-expressing neural stem cells. These results highlight that despite the persistence of an index of genomic instability, (56)Fe particle-induced deficits in adult hippocampal neurogenesis may be transient. These

  6. 56Fe Particle Exposure Results in a Long-Lasting Increase in a Cellular Index of Genomic Instability and Transiently Suppresses Adult Hippocampal Neurogenesis in Vivo

    PubMed Central

    DeCarolis, Nathan A.; Rivera, Phillip D.; Ahn, Francisca; Amaral, Wellington Z.; LeBlanc, Junie A.; Malhotra, Shveta; Shih, Hung-Ying; Petrik, David; Melvin, Neal; Chen, Benjamin P.C.; Eisch, Amelia J.

    2014-01-01

    The high-LET HZE particles from galactic cosmic radiation pose tremendous health risks to astronauts, as they may incur sub-threshold brain injury or maladaptations that may lead to cognitive impairment. The health effects of HZE particles are difficult to predict and unfeasible to prevent. This underscores the importance of estimating radiation risks to the central nervous system as a whole as well as to specific brain regions like the hippocampus, which is central to learning and memory. Given that neurogenesis in the hippocampus has been linked to learning and memory, we investigated the response and recovery of neurogenesis and neural stem cells in the adult mouse hippocampal dentate gyrus after HZE particle exposure using two nestin transgenic reporter mouse lines to label and track radial glia stem cells (Nestin-GFP and Nestin-CreERT2/R26R:YFP mice, respectively). Mice were subjected to 56Fe particle exposure (0 or 1 Gy, at either 300 or 1000 MeV/n) and brains were harvested at early (24h), intermediate (7d), and/or long time points (2–3mo) post-irradiation. 56Fe particle exposure resulted in a robust increase in 53BP1+ foci at both the intermediate and long time points post-irradiation, suggesting long-term genomic instability in the brain. However, 56Fe particle exposure only produced a transient decrease in immature neuron number at the intermediate time point, with no significant decrease at the long time point post-irradiation. 56Fe particle exposure similarly produced a transient decrease in dividing progenitors, with fewer progenitors labeled at the early time point but equal number labeled at the intermediate time point, suggesting a recovery of neurogenesis. Notably, 56Fe particle exposure did not change the total number of nestin-expressing neural stem cells. These results highlight that despite the persistence of an index of genomic instability, 56Fe particle-induced deficits in adult hippocampal neurogenesis may be transient. These data support

  7. Trauma-Induced Alterations in Cognition and Arc Expression are Reduced by Previous Exposure to 56Fe Irradiation

    PubMed Central

    Rosi, Susanna; Belarbi, Karim; Ferguson, Ryan A.; Fishman, Kelly; Obenaus, Andre; Raber, Jacob; Fike, John R.

    2013-01-01

    Exposure to ionizing irradiation may affect brain functions directly, but may also change tissue sensitivity to a secondary insult such as trauma, stroke or degenerative disease. To determine if a low dose of particulate irradiation sensitizes the brain to a subsequent injury, C56BL6 mice were exposed to brain only irradiation with 0.5 Gy of 56Fe ions. Two months later, unilateral traumatic brain injury was induced using a controlled cortical impact system. Three weeks after trauma animals received multiple BrdU injections and 30 days later were tested for cognitive performance in the Morris water maze. All animals where able to locate the visible and hidden platform during training; however, treatment effects were seen when spatial memory retention was assessed in the probe trial (no platform). While sham and irradiated animals showed spatial memory retention, mice that received trauma alone did not. When trauma was preceded by irradiation, performance in the water maze was not different from sham-treated animals, suggesting that low dose irradiation had a protective effect in the context of a subsequent traumatic injury. Measures of hippocampal neurogenesis showed that combined injury did not induce any changes greater that those seen after trauma or radiation alone. After trauma there was a significant decrease in the percentage of neurons expressing the behaviorally-induced immediate early gene Arc in both hemispheres, without associated neuronal loss. After combined injury there were no differences relative to sham-treated mice. Our results suggest that combined injury resulted in decreased alterations of our endpoints compared to trauma alone. While the underlying mechanisms are not yet known, these results resemble a preconditioning, adaptive, or inducible-like protective response, where a sublethal or potentially injurious stimulus (i.e. irradiation) induces tolerance to a subsequent and potentially more damaging insult (trauma). PMID:21192069

  8. Effects of 40Ar and 56Fe ions on retinal photoreceptor cells of the rabbit: implications for manned missions to Mars

    NASA Technical Reports Server (NTRS)

    Williams, G. R.; Lett, J. T.

    1994-01-01

    Losses of photoreceptor cells (rods) from the retinas of New Zealand white (NZW) rabbits were detectable within 2 years after localized acute irradiation of optic and proximal tissues with > or = 7 Gy of 530 MeV u-1 40Ar ions or > or = 2 Gy of 465 MeV u-1 56Fe ions in the Bragg plateau region of energy deposition. Those limits were determined only from an analysis of variance of dose groups because the shapes of the dose response curves at early post-irradiation times are not known, a concern being addressed by experiments in progress. Losses of photoreceptor cells for the period 0.5-2.5 years post-irradiation, determined by provisional linear regression analysis, were approximately 1.7% Gy-1 and 2.5% Gy-1 for 40Ar and 56Fe ions, respectively.

  9. Neutrino-induced reactions on {sup 56}Fe and {sup 56}Ni, and production of {sup 55}Mn in population III stars

    SciTech Connect

    Suzuki, Toshio; Honma, Michio; Higashiyama, Koji; Yoshida, Takashi; Umeda, Hideyuki; Kajino, Toshitaka; Otsuka, Takaharu; Nomoto, Ken'ichi

    2009-06-15

    Neutrino-induced reactions on {sup 56}Fe and {sup 56}Ni are investigated based on a new shell-model Hamiltonian for pf shell. The calculated charged current reaction cross section on {sup 56}Fe induced by decay-at-rest (DAR) neutrinos is shown to be consistent with the observation. The Gamow-Teller strength in {sup 56}Ni is found to be more spread compared to previous calculations and result in a considerably large branching ratio for the proton knock-out channel. As a consequence of this, the production yields of heavy elements such as {sup 55}Mn in population III stars are shown to be enhanced for the new Hamiltonian.

  10. Low (60 cGy) doses of (56)Fe HZE-particle radiation lead to a persistent reduction in the glutamatergic readily releasable pool in rat hippocampal synaptosomes.

    PubMed

    Machida, Mayumi; Lonart, György; Britten, Richard A

    2010-11-01

    Exposure to galactic cosmic radiation (GCR) is considered to be a potential health risk in long-term space travel, and it represents a significant risk to the central nervous system (CNS). The most harmful component of GCR is the HZE [high-mass, highly charged (Z), high-energy] particles, e.g. (56)Fe. In ground-based experiments, exposure to HZE-particle radiation induces pronounced deficits in hippocampus-dependent learning and memory in rodents. The mechanisms underlying these impairments are mostly unknown, but some studies suggest that HZE-particle exposure perturbs the regulation of long-term potentiation (LTP) at the CA1 synapse in the hippocampus. In this study, we irradiated rats with 60 cGy of 1 GeV (56)Fe-particle radiation and established its impact on hippocampal glutamatergic neurotransmissions at 3 and 6 months after exposure. Exposure to 60 cGy (56)Fe-particle radiation significantly (P < 0.05) reduced hyperosmotic sucrose evoked [(3)H]-glutamate release from hippocampal synaptosomes, a measure of the readily releasable vesicular pool (RRP). This HZE-particle-induced reduction in the glutamatergic RRP persisted for at least 6 months after exposure. At 90 days postirradiation, there was a significant reduction in the expression of the NR1, NR2A and NR2B subunits of the glutamatergic NMDA receptor. The level of the NR2A protein remained suppressed at 180 days postirradiation, but the level of NR2B and NR1 proteins returned to or exceeded normal levels, respectively. Overall, this study shows that hippocampal glutamatergic transmission is sensitive to relative low doses of (56)Fe particles. Whether the observed HZE-particle-induced change in glutamate transmission, which plays a critical role in learning and memory, is the cause of HZE-particle-induced neurocognitive impairment requires further investigation.

  11. Low (60 cGy) doses of (56)Fe HZE-particle radiation lead to a persistent reduction in the glutamatergic readily releasable pool in rat hippocampal synaptosomes.

    PubMed

    Machida, Mayumi; Lonart, György; Britten, Richard A

    2010-11-01

    Exposure to galactic cosmic radiation (GCR) is considered to be a potential health risk in long-term space travel, and it represents a significant risk to the central nervous system (CNS). The most harmful component of GCR is the HZE [high-mass, highly charged (Z), high-energy] particles, e.g. (56)Fe. In ground-based experiments, exposure to HZE-particle radiation induces pronounced deficits in hippocampus-dependent learning and memory in rodents. The mechanisms underlying these impairments are mostly unknown, but some studies suggest that HZE-particle exposure perturbs the regulation of long-term potentiation (LTP) at the CA1 synapse in the hippocampus. In this study, we irradiated rats with 60 cGy of 1 GeV (56)Fe-particle radiation and established its impact on hippocampal glutamatergic neurotransmissions at 3 and 6 months after exposure. Exposure to 60 cGy (56)Fe-particle radiation significantly (P < 0.05) reduced hyperosmotic sucrose evoked [(3)H]-glutamate release from hippocampal synaptosomes, a measure of the readily releasable vesicular pool (RRP). This HZE-particle-induced reduction in the glutamatergic RRP persisted for at least 6 months after exposure. At 90 days postirradiation, there was a significant reduction in the expression of the NR1, NR2A and NR2B subunits of the glutamatergic NMDA receptor. The level of the NR2A protein remained suppressed at 180 days postirradiation, but the level of NR2B and NR1 proteins returned to or exceeded normal levels, respectively. Overall, this study shows that hippocampal glutamatergic transmission is sensitive to relative low doses of (56)Fe particles. Whether the observed HZE-particle-induced change in glutamate transmission, which plays a critical role in learning and memory, is the cause of HZE-particle-induced neurocognitive impairment requires further investigation. PMID:20726706

  12. Acute and fractionated exposure to high-LET (56)Fe HZE-particle radiation both result in similar long-term deficits in adult hippocampal neurogenesis.

    PubMed

    Rivera, Phillip D; Shih, Hung-Ying; Leblanc, Junie A; Cole, Mara G; Amaral, Wellington Z; Mukherjee, Shibani; Zhang, Shichuan; Lucero, Melanie J; Decarolis, Nathan A; Chen, Benjamin P C; Eisch, Amelia J

    2013-12-01

    Astronauts on multi-year interplanetary missions will be exposed to a low, chronic dose of high-energy, high-charge particles. Studies in rodents show acute, nonfractionated exposure to these particles causes brain changes such as fewer adult-generated hippocampal neurons and stem cells that may be detrimental to cognition and mood regulation and thus compromise mission success. However, the influence of a low, chronic dose of these particles on neurogenesis and stem cells is unknown. To examine the influence of galactic cosmic radiation on neurogenesis, adult-generated stem and progenitor cells in Nestin-CreER(T2)/R26R-YFP transgenic mice were inducibly labeled to allow fate tracking. Mice were then sham exposed or given one acute 100 cGy (56)Fe-particle exposure or five fractionated 20 cGy (56)Fe-particle exposures. Adult-generated hippocampal neurons and stem cells were quantified 24 h or 3 months later. Both acute and fractionated exposure decreased the amount of proliferating cells and immature neurons relative to sham exposure. Unexpectedly, neither acute nor fractionated exposure decreased the number of adult neural stem cells relative to sham expsoure. Our findings show that single and fractionated exposures of (56)Fe-particle irradiation are similarly detrimental to adult-generated neurons. Implications for future missions and ground-based studies in space radiation are discussed. PMID:24320054

  13. Acute and Fractionated Exposure to High-LET 56Fe HZE-Particle Radiation Both Result in Similar Long-Term Deficits in Adult Hippocampal Neurogenesis

    PubMed Central

    Rivera, Phillip D.; Shih, Hung-Ying; LeBlanc, Junie A.; Cole, Mara G.; Amaral, Wellington Z.; Mukherjee, Shibani; Zhang, Shichuan; Lucero, Melanie J.; DeCarolis, Nathan A.; Chen, Benjamin P. C.; Eisch, Amelia J.

    2014-01-01

    Astronauts on multi-year interplanetary missions will be exposed to a low, chronic dose of high-energy, high-charge particles. Studies in rodents show acute, nonfractionated exposure to these particles causes brain changes such as fewer adult-generated hippocampal neurons and stem cells that may be detrimental to cognition and mood regulation and thus compromise mission success. However, the influence of a low, chronic dose of these particles on neurogenesis and stem cells is unknown. To examine the influence of galactic cosmic radiation on neurogenesis, adult-generated stem and progenitor cells in Nestin-CreERT2/R26R-YFP transgenic mice were inducibly labeled to allow fate tracking. Mice were then sham exposed or given one acute 100 cGy 56Fe-particle exposure or five fractionated 20 cGy 56Fe-particle exposures. Adult-generated hippocampal neurons and stem cells were quantified 24 h or 3 months later. Both acute and fractionated exposure decreased the amount of proliferating cells and immature neurons relative to sham exposure. Unexpectedly, neither acute nor fractionated exposure decreased the number of adult neural stem cells relative to sham expsoure. Our findings show that single and fractionated exposures of 56Fe-particle irradiation are similarly detrimental to adult-generated neurons. Implications for future missions and ground-based studies in space radiation are discussed. PMID:24320054

  14. Age/Radiation Parallels in the Effects of 56Fe Particle Irradiation and Protection by Berry Diets

    NASA Astrophysics Data System (ADS)

    Joseph, James; Bielinski, Donna; Carrihill-Knoll, Kirsty; Rabin, Bernard; Shukitt-Hale, Barbara

    Exposing young rats to particles of high-energy and charge (HZE particles) enhances indices of oxidative stress and inflammation and disrupts the functioning of the dopaminergic system and behaviors mediated by this system in a manner similar to that seen in aged animals Previous research has shown that diets supplemented with 2% blueberry or strawberry extracts have the ability to retard and even reverse age-related deficits in behavior and signal transduction in rats, perhaps due to their antioxidant and anti-inflammatory properties. A subsequent study has shown that whole-body irradiation with 1.5 Gy of 1 GeV/n high-energy 56 Fe particles impaired performance in the Morris water maze and measures of dopamine release one month following radiation; these deficits were protected by the antioxidant diets. The strawberry diet offered better protection against spatial deficits in the maze because strawberry-fed animals were better able to retain place information, while the blueberry-supplemented animals showed enhanced learning that was dependent on striatal functioning. Additional experiments in cell models to examine possible mechanisms involved in these beneficial effects have shown that, in addition to the well known free radical scavenging effects of berries, it appears that berry fruit can directly reduce stress signaling and enhance protective signals, suggesting the involvement of multiple mechanisms in the beneficial effects observed. Enhancements of "protective" signals (e.g., extracellular signal regulated kinase, ERK) include those that are involved in neuronal communication, neurogenesis, and learning and memory. Reductions in stress signaling include inhibiting nuclear factor kappa B (NF-κB) and cytokines, among others, induced by oxidative and inflammatory stressors. We have found these changes in both BV2 mouse microglial and hippocampal cells. We believe that the possible addition of colorful fruits such as berry fruits to the diet can possibly

  15. Executive function in rats is impaired by low (20 cGy) doses of 1 GeV/u (56)Fe particles.

    PubMed

    Lonart, György; Parris, Brian; Johnson, Angela M; Miles, Scott; Sanford, Larry D; Singletary, Sylvia J; Britten, Richard A

    2012-10-01

    Exposure to galactic cosmic radiation is a potential health risk in long-term space travel and represents a significant risk to the central nervous system. The most harmful component of galactic cosmic radiation is the HZE [high mass, highly charged (Z), high energy] particles, e.g., (56)Fe particle. In previous ground-based experiments, exposure to doses of HZE-particle radiation that an astronaut will receive on a deep space mission (i.e., ∼20 cGy) resulted in pronounced deficits in hippocampus-dependent learning and memory in rodents. Neurocognitive tasks that are dependent upon other regions of the brain, such as the striatum, are also impaired after exposure to low HZE-particle doses. These data raise the possibility that neurocognitive tasks regulated by the prefrontal cortex could also be impaired after exposure to mission relevant HZE-particle doses, which may prevent astronauts from performing complex executive functions. To assess the effects of mission relevant (20 cGy) doses of 1 GeV/u (56)Fe particles on executive function, male Wistar rats received either sham treatment or were irradiated and tested 3 months later for their ability to perform attentional set shifting. Compared to the controls, rats that received 20 cGy of 1 GeV/u (56)Fe particles showed significant impairments in their ability to complete the attentional set-shifting test, with only 17% of irradiated rats completing all stages as opposed to 78% of the control rats. The majority of failures (60%) occurred at the first reversal stage, and half of the remaining animals failed at the extra-dimensional shift phase of the studies. The irradiated rats that managed to complete the tasks did so with approximately the same ease as did the control rats. These observations suggest that exposure to mission relevant doses of 1 GeV/u (56)Fe particles results in the loss of functionality in several regions of the cortex: medical prefrontal cortex, anterior cingulated cortex, posterior cingulated

  16. Executive function in rats is impaired by low (20 cGy) doses of 1 GeV/u (56)Fe particles.

    PubMed

    Lonart, György; Parris, Brian; Johnson, Angela M; Miles, Scott; Sanford, Larry D; Singletary, Sylvia J; Britten, Richard A

    2012-10-01

    Exposure to galactic cosmic radiation is a potential health risk in long-term space travel and represents a significant risk to the central nervous system. The most harmful component of galactic cosmic radiation is the HZE [high mass, highly charged (Z), high energy] particles, e.g., (56)Fe particle. In previous ground-based experiments, exposure to doses of HZE-particle radiation that an astronaut will receive on a deep space mission (i.e., ∼20 cGy) resulted in pronounced deficits in hippocampus-dependent learning and memory in rodents. Neurocognitive tasks that are dependent upon other regions of the brain, such as the striatum, are also impaired after exposure to low HZE-particle doses. These data raise the possibility that neurocognitive tasks regulated by the prefrontal cortex could also be impaired after exposure to mission relevant HZE-particle doses, which may prevent astronauts from performing complex executive functions. To assess the effects of mission relevant (20 cGy) doses of 1 GeV/u (56)Fe particles on executive function, male Wistar rats received either sham treatment or were irradiated and tested 3 months later for their ability to perform attentional set shifting. Compared to the controls, rats that received 20 cGy of 1 GeV/u (56)Fe particles showed significant impairments in their ability to complete the attentional set-shifting test, with only 17% of irradiated rats completing all stages as opposed to 78% of the control rats. The majority of failures (60%) occurred at the first reversal stage, and half of the remaining animals failed at the extra-dimensional shift phase of the studies. The irradiated rats that managed to complete the tasks did so with approximately the same ease as did the control rats. These observations suggest that exposure to mission relevant doses of 1 GeV/u (56)Fe particles results in the loss of functionality in several regions of the cortex: medical prefrontal cortex, anterior cingulated cortex, posterior cingulated

  17. Exposure to Low-Dose 56Fe-Ion Radiation Induces Long-Term Epigenetic Alterations in Mouse Bone Marrow Hematopoietic Progenitor and Stem Cells

    PubMed Central

    Chang, Jianhui; Feng, Wei; Wang, Yingying; Allen, Antiño R.; Turner, Jennifer; Stewart, Blair; Raber, Jacob; Zhou, Daohong

    2014-01-01

    There is an increasing need to better understand the long-term health effects of high-linear energy transfer (LET) radiation due to exposure during space missions, as well as its increasing use in clinical treatments. Previous studies have indicated that exposure to 56Fe heavy ions increases the incidence of acute myeloid leukemia (AML) in mice but the underlying molecular mechanisms remain elusive. Epigenetic alterations play a role in radiation-induced genomic instability and the initiation and progression of AML. In this study, we assessed the effects of low-dose 56Fe-ion irradiation on epigenetic alterations in bone marrow mononuclear cells (BM-MNCs) and hematopoietic progenitor and stem cells (HPSCs). Exposure to 56Fe ions (600 MeV, 0.1, 0.2 and 0.4 Gy) resulted in significant epigenetic alterations involving methylation of DNA, the DNA methylation machinery and expression of repetitive elements. Four weeks after irradiation, these changes were primarily confined to HPSCs and were exhibited as dose-dependent hypermethylation of LINE1 and SINE B1 repetitive elements [4.2-fold increase in LINE1 (P < 0.001) and 7.6-fold increase in SINE B1 (P < 0.01) after exposure to 0.4 Gy; n = 5]. Epigenetic alterations were persistent and detectable for at least 22 weeks after exposure, when significant loss of global DNA hypomethylation (1.9-fold, P < 0.05), decreased expression of Dnmt1 (1.9-fold, P < 0.01), and increased expression of LINE1 and SINE B1 repetitive elements (2.8-fold, P < 0.001 for LINE1 and 1.9-fold, P < 0.05 for SINE B1; n = 5) were observed after exposure to 0.4 Gy. In contrast, exposure to 56Fe ions did not result in accumulation of increased production of reactive oxygen species (ROS) and DNA damage, exhibited as DNA strand breaks. Furthermore, no significant alterations in cellular senescence and apoptosis were detected in HPSCs after exposure to 56Fe-ion radiation. These findings suggest that epigenetic reprogramming is possibly involved in the

  18. No-Core Shell Model for 48-Ca, 48-Sc and 48-Ti

    SciTech Connect

    Popescu, S; Stoica, S; Vary, J P; Navratil, P

    2004-10-26

    The authors report the first no-core shell model results for {sup 48}Ca, {sup 48}Sc and {sup 48}Ti with derived and modified two-body Hamiltonians. We use an oscillator basis with a limited {bar h}{Omega} range around 40/A{sup 1/3} = 11 MeV and a limited model space up to 1 {bar h}{Omega}. No single-particle energies are used. They find that the charge dependence of the bulk binding energy of eight A = 48 nuclei is reasonably described with an effective Hamiltonian derived from the CD-Bonn interaction while there is an overall underbinding by about 0.4 MeV/nucleon. However, resulting spectra exhibit deficiencies that are anticipated due to: (1) basis space limitations and/or the absence of effective many-body interactions; and, (2) the absence of genuine three-nucleon interactions. They introduce phenomenological modifications to obtain fits to total binding and low-lying spectra. The resulting no-core shell model opens a path for applications to experiments such as the double-beta ({beta}{beta}) decay process.

  19. Exposure to mission relevant doses of 1 GeV/Nucleon (56)Fe particles leads to impairment of attentional set-shifting performance in socially mature rats.

    PubMed

    Britten, Richard A; Davis, Leslie K; Jewell, Jessica S; Miller, Vania D; Hadley, Melissa M; Sanford, Larry D; Machida, Mayumi; Lonart, György

    2014-09-01

    Previous ground-based experiments have shown that cranial irradiation with mission relevant (20 cGy) doses of 1 GeV/nucleon (56)Fe particles leads to a significant impairment in Attentional Set Shifting (ATSET) performance, a measure of executive function, in juvenile Wistar rats. However, the use of head only radiation exposure and the biological age of the rats used in that study may not be pertinent to determine the likelihood that ATSET will be impaired in Astronauts on deep space flights. In this study we have determined the impact that whole-body exposure to 10, 15 and 20 cGy of 1 GeV/nucleon (56)Fe particles had on the ability (at three months post exposure) of socially mature (retired breeder) Wistar rats to conduct the attentional set-shifting paradigm. The current study has established that whole-body exposures to 15 and 20 (but not 10) cGy of 1 GeV/nucleon (56)Fe particles results in the impairment of ATSET in both juvenile and socially mature rats. However, the exact nature of the impaired ATSET performance varied depending upon the age of the rats, whether whole-body versus cranial irradiation was used and the dose of 1 GeV/u (56)Fe received. Exposure of juvenile rats to 20 cGy of 1 GeV/nucleon (56)Fe particles led to a decreased ability to perform intra-dimensional shifting (IDS) irrespective of whether the rats received head only or whole-body exposures. Juvenile rats that received whole-body exposure also had a reduced ability to habituate to the assay and to complete intra-dimensional shifting reversal (IDR), whereas juvenile rats that received head only exposure had a reduced ability to complete compound discrimination reversal (CDR). Socially mature rats that received whole-body exposures to 10 cGy of 1 GeV/nucleon (56)Fe particles exhibited no obvious decline in set-shifting performance; however those exposed to 15 and 20 cGy had a reduced ability to perform simple discrimination (SD) and compound discrimination (CD). Exposure to 20 cGy of 1 Ge

  20. Exposure to Mission Relevant Doses of 1 GeV/Nucleon 56Fe Particles Leads to Impairment of Attentional Set-Shifting Performance in Socially Mature Rats

    PubMed Central

    Britten, Richard A.; Davis, Leslie K.; Jewell, Jessica S.; Miller, Vania D.; Hadley, Melissa M.; Sanford, Larry D.; Machida, Mayumi; Lonart, György

    2014-01-01

    Previous ground-based experiments have shown that cranial irradiation with mission relevant (20 cGy) doses of 1 GeV/nucleon 56Fe particles leads to a significant impairment in Attentional Set Shifting (ATSET) performance, a measure of executive function, in juvenile Wistar rats. However, the use of head only radiation exposure and the biological age of the rats used in that study may not be pertinent to determine the likelihood that ATSET will be impaired in Astronauts on deep space flights. In this study we have determined the impact that whole-body exposure to 10, 15 and 20 cGy of 1 GeV/nucleon 56Fe particles had on the ability (at three months post exposure) of socially mature (retired breeder) Wistar rats to conduct the attentional set-shifting paradigm. The current study has established that whole-body exposures to 15 and 20 (but not 10) cGy of 1 GeV/nucleon 56Fe particles results in the impairment of ATSET in both juvenile and socially mature rats. However, the exact nature of the impaired ATSET performance varied depending upon the age of the rats, whether whole-body versus cranial irradiation was used and the dose of 1 GeV/u 56Fe received. Exposure of juvenile rats to 20 cGy of 1 GeV/nucleon 56Fe particles led to a decreased ability to perform intra-dimensional shifting (IDS) irrespective of whether the rats received head only or whole-body exposures. Juvenile rats that received whole-body exposure also had a reduced ability to habituate to the assay and to complete intra-dimensional shifting reversal (IDR), whereas juvenile rats that received head only exposure had a reduced ability to complete compound discrimination reversal (CDR). Socially mature rats that received whole-body exposures to 10 cGy of 1 GeV/nucleon 56Fe particles exhibited no obvious decline in set-shifting performance; however those exposed to 15 and 20 cGy had a reduced ability to perform simple discrimination (SD) and compound discrimination (CD). Exposure to 20 cGy of 1 GeV/nucleon 56

  1. Impaired Spatial Memory Performance in Adult Wistar Rats Exposed to Low (5-20 cGy) Doses of 1 GeV/n (56)Fe Particles.

    PubMed

    Britten, Richard A; Jewell, Jessica S; Miller, Vania D; Davis, Leslie K; Hadley, Melissa M; Wyrobek, Andrew J

    2016-03-01

    Prolonged deep space missions to planets and asteroids will expose astronauts to galactic cosmic radiation, comprised of low-linear energy transfer (LET) ionizing radiations, high-energy protons and high-Z and energy (HZE) particles, such as (56)Fe nuclei. In prior studies with rodents exposed to HZE particle radiation at doses likely to be encountered during deep space missions (<20 cGy) investigators reported impaired hippocampal-dependent neurocognitive performance and further observed substantial variation among the irradiated animals in neurocognitive impairment, ranging from no observable effects to severe impairment. These findings point to the importance of incorporating quantitative measures of interindividual variations into next generation risk assessment models of radiation risks on neurocognition. In this study, 269 male proven breeder Wistar rats were exposed to 1 GeV/n (56)Fe at doses of 0, 5, 10, 15 and 20 cGy, and tested for spatial memory performance on the Barnes maze at three months after exposure. The radiation response data were compared using changes in mean cohort performance and by the proportion of poor responders using the performance benchmark of two standard deviations below the mean value among the sham-irradiated cohort. Acute exposures to mission-relevant doses of 1 GeV/n (56)Fe reduced the mean spatial memory performance at three months after exposure (P < 0.002) and increased the proportions of poor performers, 2- to 3-fold. However, a substantial fraction of animals in all exposure cohorts showed no detectable change in performance, compared to the distribution of sham-irradiated animals. Our findings suggest that individualized metrics of susceptibility or resistance to radiation-induce changes in neurocognitive performance will be advantageous to the development of probabilistic risk assessment models for HZE-induced neurocognitive impairment.

  2. Long-Term Effects of {sup 56}Fe Irradiation on Spatial Memory of Mice: Role of Sex and Apolipoprotein E Isoform

    SciTech Connect

    Villasana, Laura E.; Benice, Theodore S.; Raber, Jacob

    2011-06-01

    Purpose: To assess whether the effects of cranial {sup 56}Fe irradiation on the spatial memory of mice in the water maze are sex and apolipoprotein E (apoE) isoform dependent and whether radiation-induced changes in spatial memory are associated with changes in the dendritic marker microtubule-associated protein 2 (MAP-2) and the presynaptic marker synaptophysin. Methods and Materials: Two-month-old male and female mice expressing human apoE3 or apoE4 received either a 3-Gy dose of cranial {sup 56}Fe irradiation (600 MeV/amu) or sham irradiation. Mice were tested in a water maze task 13 months later to assess effects of irradiation on spatial memory retention. After behavioral testing, the brain tissues of these mice were analyzed for synaptophysin and MAP-2 immunoreactivity. Results: After irradiation, spatial memory retention of apoE3 female, but not male, mice was impaired. A general genotype deficit in spatial memory was observed in sham-irradiated apoE4 mice. Strikingly, irradiation prevented this genotype deficit in apoE4 male mice. A similar but nonsignificant trend was observed in apoE4 female mice. Although there was no change in MAP-2 immunoreactivity after irradiation, synaptophysin immunoreactivity was increased in irradiated female mice, independent of genotype. Conclusions: The effects of {sup 56}Fe irradiation on the spatial memory retention of mice are critically influenced by sex, and the direction of these effects is influenced by apoE isoform. Although in female mice synaptophysin immunoreactivity provides a sensitive marker for effects of irradiation, it cannot explain the apoE genotype-dependent effects of irradiation on the spatial memory retention of the mice.

  3. Impaired Spatial Memory Performance in Adult Wistar Rats Exposed to Low (5-20 cGy) Doses of 1 GeV/n (56)Fe Particles.

    PubMed

    Britten, Richard A; Jewell, Jessica S; Miller, Vania D; Davis, Leslie K; Hadley, Melissa M; Wyrobek, Andrew J

    2016-03-01

    Prolonged deep space missions to planets and asteroids will expose astronauts to galactic cosmic radiation, comprised of low-linear energy transfer (LET) ionizing radiations, high-energy protons and high-Z and energy (HZE) particles, such as (56)Fe nuclei. In prior studies with rodents exposed to HZE particle radiation at doses likely to be encountered during deep space missions (<20 cGy) investigators reported impaired hippocampal-dependent neurocognitive performance and further observed substantial variation among the irradiated animals in neurocognitive impairment, ranging from no observable effects to severe impairment. These findings point to the importance of incorporating quantitative measures of interindividual variations into next generation risk assessment models of radiation risks on neurocognition. In this study, 269 male proven breeder Wistar rats were exposed to 1 GeV/n (56)Fe at doses of 0, 5, 10, 15 and 20 cGy, and tested for spatial memory performance on the Barnes maze at three months after exposure. The radiation response data were compared using changes in mean cohort performance and by the proportion of poor responders using the performance benchmark of two standard deviations below the mean value among the sham-irradiated cohort. Acute exposures to mission-relevant doses of 1 GeV/n (56)Fe reduced the mean spatial memory performance at three months after exposure (P < 0.002) and increased the proportions of poor performers, 2- to 3-fold. However, a substantial fraction of animals in all exposure cohorts showed no detectable change in performance, compared to the distribution of sham-irradiated animals. Our findings suggest that individualized metrics of susceptibility or resistance to radiation-induce changes in neurocognitive performance will be advantageous to the development of probabilistic risk assessment models for HZE-induced neurocognitive impairment. PMID:26943453

  4. {sup 48}Ti(n,xnpa{gamma}) reaction cross sections using spallation neutrons for E{sub n} = 1 to 20 MeV

    SciTech Connect

    Dashdorj, D; Mitchell, G E; Garrett, P E; Agvaanluvsan, U; Becker, J A; Bernstein, L A; Cooper, J R; Hoffman, R D; Younes, W; Devlin, N; Fotiades, N; Nelson, R O

    2005-01-06

    {gamma}-ray excitation functions have been measured for the interaction of fast neutrons with {sup 48}Ti (neutron energy from 1 MeV to 250 MeV). The Los Alamos National Laboratory spallation neutron source, at the LANSCE/WNR facility, provided a ''white'' neutron beam which is produced by bombarding a natural W target with a pulsed proton beam. The prompt-reaction {gamma} rays were measured with the large-scale Compton-suppressed Ge spectrometer, GEANIE. Neutron energies were determined by the time-of-flight technique. Excitation functions were converted to partial {gamma}-ray cross sections, taking into account the dead-time correction, the target thickness, the detector efficiency, and neutron flux (monitored with an in-line fission chamber). The data analysis is presented here for neutron energies between 1 to 20 MeV. Partial {gamma}-ray cross sections for transitions in {sup 47,48}Ti, {sup 48}Sc, and {sup 45}Ca have been determined. These results are compared to Hauser-Feshbach predictions calculated using the STAPRE code, which includes compound nuclear and pre-equilibrium emission. The partial cross sections for {gamma} rays, whose discrete {gamma}-ray cascade path leads to the ground state in {sup 48}Ti, {sup 47}Ti, {sup 48}Sc, and {sup 45}Ca have been summed to obtain estimates of the lower limits for reaction cross sections. Partial cross sections for unobserved {gamma}-rays are predicted from the STAPRE code. These lower limits are combined with Hauser-Feshbach calculations to deduce {sup 48}Ti(n,n'){sup 48}Ti, {sup 48}Ti(n,2n){sup 47}Ti, {sup 48}Ti(n,p){sup 48}Sc, and {sup 48}Ti(n,{alpha}){sup 45}Ca reaction channel cross sections.

  5. Role of final state interactions in quasielastic [sup 56]Fe([ital e],[ital e][prime]) reactions at large [vert bar][ital [rvec q

    SciTech Connect

    Chinn, C.R. )

    1995-04-01

    A relativistic finite nucleus calculation using a Dirac optical potential is used to investigate the importance of final state interactions (FSI) at large momentum transfers in inclusive quasielastic electronuclear reactions. The optical potential is derived from first-order multiple scattering theory and then is used to calculate the FSI in a nonspectral Green's function doorway approach. At intermediate momentum transfers excellent predictions of the quasielastic [sup 56]Fe([ital e],[ital e][prime]) experimental data for the longitudinal response function are obtained. In comparisons with recent measurements at [vert bar][ital [rvec q

  6. Short-term effects of whole-body exposure to (56)fe ions in combination with musculoskeletal disuse on bone cells.

    PubMed

    Yumoto, Kenji; Globus, Ruth K; Mojarrab, Rose; Arakaki, Joy; Wang, Angela; Searby, Nancy D; Almeida, Eduardo A C; Limoli, Charles L

    2010-04-01

    Space travel and prolonged bed rest cause bone loss due to musculoskeletal disuse. In space, radiation fields may also have detrimental consequences because charged particles traversing the tissues of the body can elicit a wide range of cytotoxic and genotoxic lesions. The effects of heavy-ion radiation exposure in combination with musculoskeletal disuse on bone cells and tissue are not known. To explore this, normally loaded 16-week-old male C57BL/6 mice were exposed to (56)Fe ions (1 GeV/nucleon) at doses of 0 cGy (sham), 10 cGy, 50 cGy or 2 Gy 3 days before tissue harvest. Additional mice were hindlimb unloaded by tail traction continuously for 1 week to simulate weightlessness and exposed to (56)Fe-ion radiation (0 cGy, 50 cGy, 2 Gy) 3 days before tissue harvest. Despite the short duration of this study, low-dose (10, 50 cGy) irradiation of normally loaded mice reduced trabecular volume fraction (BV/TV) in the proximal tibiae by 18% relative to sham-irradiated controls. Hindlimb unloading together with 50 cGy radiation caused a 126% increase in the number of TRAP(+) osteoclasts on cancellous bone surfaces relative to normally loaded, sham-irradiated controls. Together, radiation and hindlimb unloading had a greater effect on suppressing osteoblastogenesis ex vivo than either treatment alone. In sum, low-dose exposure to heavy ions (50 cGy) caused rapid cancellous bone loss in normally loaded mice and increased osteoclast numbers in hindlimb unloaded mice. In vitro irradiation also was more detrimental to osteoblastogenesis in bone marrow cells that were recovered from hindlimb unloaded mice compared to cells from normally loaded mice. Furthermore, irradiation in vitro stimulated osteoclast formation in a macrophage cell line (RAW264.7) in the presence of RANKL (25 ng/ml), showing that heavy-ion radiation can stimulate osteoclast differentiation even in the absence of osteoblasts. Thus heavy-ion radiation can acutely increase osteoclast numbers in cancellous

  7. Radiation leukemogenesis in mice: loss of PU.1 on chromosome 2 in CBA and C57BL/6 mice after irradiation with 1 GeV/nucleon 56Fe ions, X rays or gamma rays. Part I. Experimental observations.

    PubMed

    Peng, Yuanlin; Brown, Natalie; Finnon, Rosemary; Warner, Christy L; Liu, Xianan; Genik, Paula C; Callan, Matthew A; Ray, F Andrew; Borak, Thomas B; Badie, Christophe; Bouffler, Simon D; Ullrich, Robert L; Bedford, Joel S; Weil, Michael M

    2009-04-01

    Since deletion of the PU.1 gene on chromosome 2 is a crucial acute myeloid leukemia (AML) initiating step in the mouse model, we quantified PU.1 deleted cells in the bone marrow of gamma-, X- and 56Fe-ion-irradiated mice at various times postirradiation. Although 56Fe ions were initially some two to three times more effective than X or gamma rays in inducing PU.1 deletions, by 1 month postirradiation, the proportions of cells with PU.1 deletions were similar for the HZE particles and the sparsely ionizing radiations. These results indicate that while 56Fe ions are more effective in inducing PU.1 deletions, they are also more effective in causing collateral damage that removes hit cells from the bone marrow. After X, gamma or 56Fe-ion irradiation, AML-resistant C57BL/6 mice have fewer cells with PU.1 deletions than CBA mice, and those cells do not persist in the bone marrow of the C57B6/6 mice. Our findings suggest that quantification of PU.1 deleted bone marrow cells 1 month postirradiation can be used as surrogate for the incidence of radiation-induced AML measured in large-scale mouse studies. If so, PU.1 loss could be used to systematically assess the potential leukemogenic effects of other ions and energies in the space radiation environment.

  8. Low (20 cGy) doses of 1 GeV/u (56)Fe--particle radiation lead to a persistent reduction in the spatial learning ability of rats.

    PubMed

    Britten, Richard A; Davis, Leslie K; Johnson, Angela M; Keeney, Sonia; Siegel, Andrew; Sanford, Larry D; Singletary, Sylvia J; Lonart, György

    2012-02-01

    Exposure to galactic cosmic radiation (GCR) is considered to be a potential health risk in long-term space travel, and it represents a significant risk to the central nervous system (CNS). The most harmful component of GCR is the HZE [high-mass, highly charged (Z), high-energy] particles, e.g. (56)Fe. In previous ground-based experiments, exposure to high doses of HZE-particle radiation induced pronounced deficits in hippocampus-dependent learning and memory in rodents. Recent data suggest that glutamatergic transmission in hippocampal synaptosomes is impaired after low (60 cGy) doses of 1 GeV/u (56)Fe particles, which could lead to impairment of hippocampus-dependent spatial memory. To assess the effects of mission-relevant (20-60 cGy) doses of 1 GeV/u (56)Fe particles on hippocampus-dependent spatial memory, male Wistar rats either received sham treatment or were irradiated and tested 3 months later in the Barnes maze test. Compared to the controls, rats that received 20, 40 and 60 cGy 1 GeV/u (56)Fe particles showed significant impairments in their ability to locate the escape box in the Barnes maze, which was manifested by progressively increasing escape latency times over the 3 days of testing. However, this increase was not due to a lack of motivation of the rats to escape, because the total number of head pokes (and especially incorrect head pokes) remained constant over the test period. Given that rats exposed to X rays did not exhibit spatial memory impairments until >10 Gy was delivered, the RBE for 1 GeV/u (56)Fe-particle-induced hippocampal spatial memory impairment is ∼50. These data demonstrate that mission-relevant doses of 1 GeV/u (56)Fe particles can result in severe deficits in hippocampus-dependent neurocognitive tasks, and the extreme sensitivity of these processes to 1 GeV/u (56)Fe particles must arise due to the perturbation of multiple processes in addition to killing neuronal cells.

  9. Low (20 cGy) doses of 1 GeV/u (56)Fe--particle radiation lead to a persistent reduction in the spatial learning ability of rats.

    PubMed

    Britten, Richard A; Davis, Leslie K; Johnson, Angela M; Keeney, Sonia; Siegel, Andrew; Sanford, Larry D; Singletary, Sylvia J; Lonart, György

    2012-02-01

    Exposure to galactic cosmic radiation (GCR) is considered to be a potential health risk in long-term space travel, and it represents a significant risk to the central nervous system (CNS). The most harmful component of GCR is the HZE [high-mass, highly charged (Z), high-energy] particles, e.g. (56)Fe. In previous ground-based experiments, exposure to high doses of HZE-particle radiation induced pronounced deficits in hippocampus-dependent learning and memory in rodents. Recent data suggest that glutamatergic transmission in hippocampal synaptosomes is impaired after low (60 cGy) doses of 1 GeV/u (56)Fe particles, which could lead to impairment of hippocampus-dependent spatial memory. To assess the effects of mission-relevant (20-60 cGy) doses of 1 GeV/u (56)Fe particles on hippocampus-dependent spatial memory, male Wistar rats either received sham treatment or were irradiated and tested 3 months later in the Barnes maze test. Compared to the controls, rats that received 20, 40 and 60 cGy 1 GeV/u (56)Fe particles showed significant impairments in their ability to locate the escape box in the Barnes maze, which was manifested by progressively increasing escape latency times over the 3 days of testing. However, this increase was not due to a lack of motivation of the rats to escape, because the total number of head pokes (and especially incorrect head pokes) remained constant over the test period. Given that rats exposed to X rays did not exhibit spatial memory impairments until >10 Gy was delivered, the RBE for 1 GeV/u (56)Fe-particle-induced hippocampal spatial memory impairment is ∼50. These data demonstrate that mission-relevant doses of 1 GeV/u (56)Fe particles can result in severe deficits in hippocampus-dependent neurocognitive tasks, and the extreme sensitivity of these processes to 1 GeV/u (56)Fe particles must arise due to the perturbation of multiple processes in addition to killing neuronal cells. PMID:22077338

  10. Accelerated heavy ions and the lens. IV. Biomicroscopic and cytopathological analyses of the lenses of mice irradiated with 600 MeV/amu sup 56 Fe ions

    SciTech Connect

    Worgul, B.V.; Medvedovsky, C.; Powers-Risius, P.; Alpen, E. )

    1989-11-01

    The lenses of mice exposed to 600 MeV/amu iron ions were evaluated by slit-lamp biomicroscopy and cytopathological analyses. The doses ranged from 0.05 to 1.6 Gy, and the lenses were assessed at several intervals postirradiation. Cataract, the development of which is dependent on both time and dose, is significantly more advanced in all of the exposed mice when compared to the unirradiated controls. The great difference between the severity of the cataracts caused by 0.05 Gy (the lowest dose used) and those that developed spontaneously in the control animals is an indication that 0.05 Gy may far exceed the threshold dose for the production of cataracts by accelerated iron ions. Cytopathologically, a similar dose dependence was observed for a number of end points including micronucleation, interphase death, and meridional row disorganization. In addition the exposure to the 56Fe ions produced a long-term effect on the mitotic population and a pronounced focal loss of epithelial cytoarchitecture. The microscopic changes support the view that the mechanism of heavy-ion-induced cataractogenesis is the same as that for cataracts caused by low-LET radiation.

  11. Reductions of {sup 56}Fe heavy-particle irradiation-induced deficits in striatal muscarinic receptor sensitivity by selective cross-activation/inhibition of second-messenger systems

    SciTech Connect

    Joseph, J.A.; Villalobos-Molina, R.; Rabin, B.M.; Dalton, T.K.; Harris, A.; Kandasamy, S.

    1994-07-01

    Recent experiments have revealed radiation-induced losses of sensitivity of rodent neostriatal muscarinic receptors to stimulation by cholinergic agonists that appears as reduction in oxotremorine enhancement of K{sup +}-evoked dopamine release. These losses were postulated to be the result of radiation-induced alterations early in phosphoinositide-mediated signal transduction. Additional findings indicated that if the ligand-receptor-G protein interface was bypassed no radiation deficits were seen. In the present study, radiation-induced deficits in K{sup +}-evoked dopamine release were examined in perifused striatal tissue obtained from rats exposed to 0,0.1 or 1.0 Gy of {sup 56}Fe particles. Results showed that these deficits could be reduced by co-applying combinations of various pharmacological agents that were known to have differential effects on various second messengers such as 1,4,5-inositoltrisphosphate (IP{sub 3}). Combinations included oxotremorine-carbachol, and either oxotremorine or carbachol with arginine vasopressin or arachidonic acid. These results are discussed in terms of putative radiation-induced changes in receptor-containing membranes which alter receptor-G protein coupling/uncoupling. 49 refs., 4 figs.

  12. [Effect of accelerated heavy ions of carbon 12C, neon 20Ne and iron 56Fe on the chromosomal apparatus of human blood lymphocytes in vitro].

    PubMed

    Repina, L A

    2011-01-01

    Cytogenetic assay of the chromosomal apparatus of human blood lymphocytes was carried out after in vitro irradiation by heavy charged particles with high LET values. Blood plasm samples enriched with lymphocytes were irradiated by accelerated ions of carbon 12C (290 MeV/nucleon and LET = 70 keV/microm), neon 20Ne (400 MeV/nucleon and LET = 70 keV/microm), and iron 56Fe (500 MeV/nucleon and LET = 200 keV/microm) in the dose range from 0.25 to 1 Gy. Rate of chromosome aberrations showed a linear dependence on doses from the densely ionizing radiations with high LET values. Frequency of dicentrics and centric rings in human lymphocytes irradiated by 12C with the energy of 290 MeV/nucleon was maximal at 1 Gy (p < 0.05) relative to the other heavy particles. It was found that relative biological effectiveness of heavy nuclei is several times higher than of 60Co gamma-radiation throughout the range of doses in this investigation. PMID:22312859

  13. [Effect of accelerated heavy ions of carbon 12C, neon 20Ne and iron 56Fe on the chromosomal apparatus of human blood lymphocytes in vitro].

    PubMed

    Repina, L A

    2011-01-01

    Cytogenetic assay of the chromosomal apparatus of human blood lymphocytes was carried out after in vitro irradiation by heavy charged particles with high LET values. Blood plasm samples enriched with lymphocytes were irradiated by accelerated ions of carbon 12C (290 MeV/nucleon and LET = 70 keV/microm), neon 20Ne (400 MeV/nucleon and LET = 70 keV/microm), and iron 56Fe (500 MeV/nucleon and LET = 200 keV/microm) in the dose range from 0.25 to 1 Gy. Rate of chromosome aberrations showed a linear dependence on doses from the densely ionizing radiations with high LET values. Frequency of dicentrics and centric rings in human lymphocytes irradiated by 12C with the energy of 290 MeV/nucleon was maximal at 1 Gy (p < 0.05) relative to the other heavy particles. It was found that relative biological effectiveness of heavy nuclei is several times higher than of 60Co gamma-radiation throughout the range of doses in this investigation.

  14. Induction of Chronic Inflammation and Altered Levels of DNA Hydroxymethylation in Somatic and Germinal Tissues of CBA/CaJ Mice Exposed to (48)Ti Ions.

    PubMed

    Rithidech, Kanokporn Noy; Jangiam, Witawat; Tungjai, Montree; Gordon, Chris; Honikel, Louise; Whorton, Elbert B

    2016-01-01

    Although the lung is one of the target organs at risk for cancer induction from exposure to heavy ions found in space, information is insufficient on cellular/molecular responses linked to increased cancer risk. Knowledge of such events may aid in the development of new preventive measures. Furthermore, although it is known that germinal cells are sensitive to X- or γ-rays, there is little information on the effects of heavy ions on germinal cells. Our goal was to investigate in vivo effects of 1 GeV/n (48)Ti ions (one of the important heavy ions found in the space environment) on somatic (lung) and germinal (testis) tissues collected at various times after a whole body irradiation of CBA/CaJ mice (0, 0.1, 0.25, or 0.5 Gy, delivered at 1 cGy/min). We hypothesized that (48)Ti-ion-exposure induced damage in both tissues. Lung tissue was collected from each mouse from each treatment group at 1 week, 1 month, and 6 months postirradiation. For the testis, we collected samples at 6 months postirradiation. Hence, only late-occurring effects of (48)Ti ions in the testis were studied. There were five mice per treatment group at each harvest time. We investigated inflammatory responses after exposure to (48)Ti ions by measuring the levels of activated nuclear factor kappa B and selected pro-inflammatory cytokines in both tissues of the same mouse. These measurements were coupled with the quantitation of the levels of global 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC). Our data clearly showed the induction of chronic inflammation in both tissues of exposed mice. A dose-dependent reduction in global 5hmC was found in the lung at all time-points and in testes collected at 6 months postirradiation. In contrast, significant increases in global 5mC were found only in lung and testes collected at 6 months postirradiation from mice exposed to 0.5 Gy of 1 GeV/n (48)Ti ions. Overall, our data showed that (48)Ti ions may create health risks in both

  15. Induction of Chronic Inflammation and Altered Levels of DNA Hydroxymethylation in Somatic and Germinal Tissues of CBA/CaJ Mice Exposed to (48)Ti Ions.

    PubMed

    Rithidech, Kanokporn Noy; Jangiam, Witawat; Tungjai, Montree; Gordon, Chris; Honikel, Louise; Whorton, Elbert B

    2016-01-01

    Although the lung is one of the target organs at risk for cancer induction from exposure to heavy ions found in space, information is insufficient on cellular/molecular responses linked to increased cancer risk. Knowledge of such events may aid in the development of new preventive measures. Furthermore, although it is known that germinal cells are sensitive to X- or γ-rays, there is little information on the effects of heavy ions on germinal cells. Our goal was to investigate in vivo effects of 1 GeV/n (48)Ti ions (one of the important heavy ions found in the space environment) on somatic (lung) and germinal (testis) tissues collected at various times after a whole body irradiation of CBA/CaJ mice (0, 0.1, 0.25, or 0.5 Gy, delivered at 1 cGy/min). We hypothesized that (48)Ti-ion-exposure induced damage in both tissues. Lung tissue was collected from each mouse from each treatment group at 1 week, 1 month, and 6 months postirradiation. For the testis, we collected samples at 6 months postirradiation. Hence, only late-occurring effects of (48)Ti ions in the testis were studied. There were five mice per treatment group at each harvest time. We investigated inflammatory responses after exposure to (48)Ti ions by measuring the levels of activated nuclear factor kappa B and selected pro-inflammatory cytokines in both tissues of the same mouse. These measurements were coupled with the quantitation of the levels of global 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC). Our data clearly showed the induction of chronic inflammation in both tissues of exposed mice. A dose-dependent reduction in global 5hmC was found in the lung at all time-points and in testes collected at 6 months postirradiation. In contrast, significant increases in global 5mC were found only in lung and testes collected at 6 months postirradiation from mice exposed to 0.5 Gy of 1 GeV/n (48)Ti ions. Overall, our data showed that (48)Ti ions may create health risks in both

  16. Induction of Chronic Inflammation and Altered Levels of DNA Hydroxymethylation in Somatic and Germinal Tissues of CBA/CaJ Mice Exposed to 48Ti Ions

    PubMed Central

    Rithidech, Kanokporn Noy; Jangiam, Witawat; Tungjai, Montree; Gordon, Chris; Honikel, Louise; Whorton, Elbert B.

    2016-01-01

    Although the lung is one of the target organs at risk for cancer induction from exposure to heavy ions found in space, information is insufficient on cellular/molecular responses linked to increased cancer risk. Knowledge of such events may aid in the development of new preventive measures. Furthermore, although it is known that germinal cells are sensitive to X- or γ-rays, there is little information on the effects of heavy ions on germinal cells. Our goal was to investigate in vivo effects of 1 GeV/n 48Ti ions (one of the important heavy ions found in the space environment) on somatic (lung) and germinal (testis) tissues collected at various times after a whole body irradiation of CBA/CaJ mice (0, 0.1, 0.25, or 0.5 Gy, delivered at 1 cGy/min). We hypothesized that 48Ti-ion-exposure induced damage in both tissues. Lung tissue was collected from each mouse from each treatment group at 1 week, 1 month, and 6 months postirradiation. For the testis, we collected samples at 6 months postirradiation. Hence, only late-occurring effects of 48Ti ions in the testis were studied. There were five mice per treatment group at each harvest time. We investigated inflammatory responses after exposure to 48Ti ions by measuring the levels of activated nuclear factor kappa B and selected pro-inflammatory cytokines in both tissues of the same mouse. These measurements were coupled with the quantitation of the levels of global 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC). Our data clearly showed the induction of chronic inflammation in both tissues of exposed mice. A dose-dependent reduction in global 5hmC was found in the lung at all time-points and in testes collected at 6 months postirradiation. In contrast, significant increases in global 5mC were found only in lung and testes collected at 6 months postirradiation from mice exposed to 0.5 Gy of 1 GeV/n 48Ti ions. Overall, our data showed that 48Ti ions may create health risks in both lung and

  17. The influence of projectile neutron number in the 208Pb(48Ti, n)255Rf and 208Pb(50Ti, n)257Rf reactions

    SciTech Connect

    Dragojevic, Irena; Dragojevic, I.; Gregorich, K.E.; Dullmann, Ch.E.; Garcia, M.A.; Gates, J.M.; Nelson, S.L.; Stavsetra, L.; Sudowe, R.; Nitsche, H.

    2008-07-11

    Four isotopes of rutherfordium,254-257Rf, were produced by the 208Pb(48Ti, xn)256-xRf and 208Pb(50Ti, xn)258-xRf reactions (x = 1, 2) at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. Excitation functions were measured for the 1n and 2n exit channels. A maximum likelihood technique, which correctly accounts for the changing cross section at all energies subtended by the targets, was used to fit the 1n data to allow a more direct comparison between excitation functions obtained under different experimental conditions. The maximum 1n crosssections of the 208Pb(48Ti, n)255Rf and 208Pb(50Ti, n)257Rf reactions obtained from fits to the experimental data are 0.38 +/- 0.07 nb and 40 +/-5 nb, respectively. Excitation functions for the 2n exit channel were also measured, with maximum cross sections of nb for the 48Ti induced reaction, and 15.7 +/- 0.2 nb for the 50Ti induced reaction. The impact of the two neutron difference in the projectile on the 1n cross section is discussed. The results are compared to the Fusion by Diffusion model developed by Swiatecki, Wilczynska, and Wilczynski.

  18. Mass and charge distributions in iron-induced reactions and excitation energy division between the fragments of the 672-MeV [sup 56]Fe + [sup 165]Ho reaction

    SciTech Connect

    Madani, H.

    1993-01-01

    The projectile-like and target-like fragments produced by the 12-MeV/nucleon [sup 56]Fe + [sup 165]Ho reaction were detected in coincidence. The measured parameters were the mass, charge, kinetic energy scattering angle of the projectile-like fragments, and the scattering angle of the target-like fragments. The mass and charge distributions of the projectile-like fragments were generated as a function of energy loss, and characterized by their centroids, variances, and correlation coefficients. The neutron drift of the measured projectile-like products is mostly due to evaporative processes, while the charge drift is a result of a net transfer of protons from the projectile-like fragment to the target-like fragment. The result is a weak drift of the system towards mass asymmetry. The predictions of two nucleon exchange models are compared to the experimental results of the 672-MeV [sup 56]Fe + [sup 165]Ho reaction and other Fe-induced reactions. The fairly good agreement between the experimental and theoretical variances verifies the prevalence of a nucleon exchange mechanism in these reactions. The information from the coincidence measurement and two-body kinematics are used to reconstruct the pre-evaporation masses of the projectile-like and target-like fragments of the reaction. Statistical evaporation calculations are used to translate these masses into excitation energies of the primary fragments. The ratio of excitation energy stored in the projectile-Mm fragment decreases with increasing energy loss, in qualitative agreement with previous measurements; however, higher ratios are observed for the 672-MeV [sup 56]Fe on [sup 165]Ho system.

  19. Mass and charge distributions in iron-induced reactions and excitation energy division between the fragments of the 672-MeV {sup 56}Fe + {sup 165}Ho reaction

    SciTech Connect

    Madani, H.

    1993-05-01

    The projectile-like and target-like fragments produced by the 12-MeV/nucleon {sup 56}Fe + {sup 165}Ho reaction were detected in coincidence. The measured parameters were the mass, charge, kinetic energy scattering angle of the projectile-like fragments, and the scattering angle of the target-like fragments. The mass and charge distributions of the projectile-like fragments were generated as a function of energy loss, and characterized by their centroids, variances, and correlation coefficients. The neutron drift of the measured projectile-like products is mostly due to evaporative processes, while the charge drift is a result of a net transfer of protons from the projectile-like fragment to the target-like fragment. The result is a weak drift of the system towards mass asymmetry. The predictions of two nucleon exchange models are compared to the experimental results of the 672-MeV {sup 56}Fe + {sup 165}Ho reaction and other Fe-induced reactions. The fairly good agreement between the experimental and theoretical variances verifies the prevalence of a nucleon exchange mechanism in these reactions. The information from the coincidence measurement and two-body kinematics are used to reconstruct the pre-evaporation masses of the projectile-like and target-like fragments of the reaction. Statistical evaporation calculations are used to translate these masses into excitation energies of the primary fragments. The ratio of excitation energy stored in the projectile-Mm fragment decreases with increasing energy loss, in qualitative agreement with previous measurements; however, higher ratios are observed for the 672-MeV {sup 56}Fe on {sup 165}Ho system.

  20. Performance in hippocampus- and PFC-dependent cognitive domains are not concomitantly impaired in rats exposed to 20cGy of 1GeV/n (56)Fe particles.

    PubMed

    Britten, Richard A; Miller, Vania D; Hadley, Melissa M; Jewell, Jessica S; Macadat, Evangeline

    2016-08-01

    NASA is currently conducting ground based experiments to determine whether the radiation environment that astronauts will encounter on deep space missions will have an impact on their long-term health and their ability to complete the various tasks during the mission. Emerging data suggest that exposure of rodents to mission-relevant HZE radiation doses does result in the impairment of various neurocognitive processes. An essential part of mission planning is a probabilistic risk assessment process that takes into account the likely incidence and severity of a problem. To date few studies have reported the impact of space radiation in a format that is amenable to PRA, and those that have only reported data for a single cognitive process. This study has established the ability of individual male Wistar rats to conduct a hippocampus-dependent (spatial memory) task and a cortex-dependent (attentional set shifting task) 90 days after exposure to 20cGy 1GeV/n (56)Fe particles. Radiation-induced impairment of performance in one cognitive domain was not consistently associated with impaired performance in the other domain. Thus sole reliance upon a single measure of cognitive performance may substantially under-estimate the risk of cognitive impairment, and ultimately it may be necessary to establish the likelihood that mission-relevant HZE doses will impair performance in the three or four cognitive domains that NASA considers to be most critical for mission success, and build a PRA using the composite data from such studies. PMID:27662783

  1. Performance in hippocampus- and PFC-dependent cognitive domains are not concomitantly impaired in rats exposed to 20 cGy of 1 GeV/n 56Fe particles

    NASA Astrophysics Data System (ADS)

    Britten, Richard A.; Miller, Vania D.; Hadley, Melissa M.; Jewell, Jessica S.; Macadat, Evangeline

    2016-08-01

    NASA is currently conducting ground based experiments to determine whether the radiation environment that astronauts will encounter on deep space missions will have an impact on their long-term health and their ability to complete the various tasks during the mission. Emerging data suggest that exposure of rodents to mission-relevant HZE radiation doses does result in the impairment of various neurocognitive processes. An essential part of mission planning is a probabilistic risk assessment process that takes into account the likely incidence and severity of a problem. To date few studies have reported the impact of space radiation in a format that is amenable to PRA, and those that have only reported data for a single cognitive process. This study has established the ability of individual male Wistar rats to conduct a hippocampus-dependent (spatial memory) task and a cortex-dependent (attentional set shifting task) 90 days after exposure to 20 cGy 1 GeV/n 56Fe particles. Radiation-induced impairment of performance in one cognitive domain was not consistently associated with impaired performance in the other domain. Thus sole reliance upon a single measure of cognitive performance may substantially under-estimate the risk of cognitive impairment, and ultimately it may be necessary to establish the likelihood that mission-relevant HZE doses will impair performance in the three or four cognitive domains that NASA considers to be most critical for mission success, and build a PRA using the composite data from such studies.

  2. Mass asymmetry dependence of scission times in the reactions of 18.5A MeV 136Xe+48Ti

    NASA Astrophysics Data System (ADS)

    Gui, M.; Hagel, K.; Wada, R.; Lou, Y.; Utley, D.; Xiao, B.; Li, J.; Natowitz, J. B.; Enders, G.; Kühn, W.; Metag, V.; Novotny, R.; Schwalb, O.; Charity, R. J.; Freifelder, R.; Gobbi, A.; Henning, W.; Hildenbrand, K. D.; Mayer, R.; Simon, R. S.; Wessels, J. P.; Casini, G.; Olmi, A.; Stefanini, A. A.

    1993-10-01

    The multiplicities of p and α particles detected in coincidence with fragments emitted in fully relaxed collisions in the reactions of 18.5A MeV 136Xe+48Ti have been measured for different exit channel mass asymmetries. A kinematic source analysis of the spectra and angular distributions of the light particles has been used to separate the total multiplicities into prescission and postscission contributions. From these results, the excitation energies at scission are determined using an empirical technique based upon previous measurements of light charged particle multiplicities observed in coincidence with evaporation residues. These excitation energies are found to decrease from ~400 MeV to 110 MeV as the fragment mass asymmetry, AH/AL, varies from 4.8 to 1.0. A corresponding increase of the mean lifetime of the scissioning nucleus from ~5×10-22 s to ~1×10-20 s is derived using calculated statistical model decay widths. The extent to which this variation of lifetime with mass asymmetry may be attributed to completely damped deep inelastic collisions or to dynamic delays in the decay of a compound nucleus is discussed as is the need for inclusion of dynamics in the deexcitation calculations for hot nuclei. Observed three fragment events are also discussed.

  3. Gamow-Teller Strength Distributions in {sup 48}Sc by the {sup 48}Ca(p,n) and {sup 48}Ti(n,p) Reactions and Two-Neutrino Double-beta Decay Nuclear Matrix Elements

    SciTech Connect

    Yako, K.; Sasano, M.; Miki, K.; Sakai, H.; Noji, S.; Dozono, M.; Ihara, E.; Wakasa, T.; Frekers, D.; Greenfield, M. B.; Hatanaka, K.; Kato, M.; Matsubara, H.; Okamura, H.; Sakemi, Y.; Tamii, A.; Kawabata, T.; Sakaguchi, S.; Sasamoto, Y.; Shimizu, Y.

    2009-07-03

    The double-differential cross sections for the {sup 48}Ca(p,n) and {sup 48}Ti(n,p) reactions were measured at 300 MeV. A multipole decomposition technique was applied to the spectra to extract the Gamow-Teller (GT) components. The integrated GT strengths up to an excitation energy of 30 MeV in {sup 48}Sc are 15.3+-2.2 and 2.8+-0.3 in the (p,n) and (n,p) spectra, respectively. In the (n,p) spectra additional GT strengths were found above 8 MeV where shell models within the fp shell-model space predict almost no GT strengths, suggesting that the present shell-model description of the nuclear matrix element of the two-neutrino double-beta decay is incomplete.

  4. Reliable measurement of the Li-like {sub 22}{sup 48}Ti 1s2s2p {sup 4}P{sub 5/2}{sup o} level lifetime by beam-foil and beam-two-foil experiments

    SciTech Connect

    Nandi, T.; Ahmad, Nissar; Wani, A. A.; Marketos, P.

    2006-03-15

    We have determined the lifetime of the Li-like {sub 22}{sup 48}Ti 1s2s2p {sup 4}P{sub 5/2}{sup o} level (210.5{+-}13.5 ps) using data from its x-ray decay channel through beam single- and two-foil experiments, coupled to a multicomponent iterative growth and decay analysis. Theoretical lifetime estimates for this zero-nuclear-spin ion lies within the uncertainty range of our experimental results, indicating that blending contributions to this level from the He-like 1s2p {sup 3}P{sub 2}{sup o} and 1s2s {sup 3}S{sub 1} levels are eliminated within the current approach. A previously reported discrepancy between experimental and theoretical 1s2s2p {sup 4}P{sub 5/2}{sup o} level lifetimes in {sub 23}{sup 51}V may, as a result, be attributed to hyperfine quenching.

  5. Influence of projectile neutron number on cross section in cold fusion reactions

    SciTech Connect

    Dragojevic, Irena; Dragojevic, I.; Gregorich, K.E.; Dullmann, Ch.E.; Folden III, C.M.; Garcia, M.A.; Gates, J.M.; Nelson, S.L.; Sudowe, R.; Nitsche, H.

    2007-09-01

    Elements 107-112 [1,2] have been discovered in reactions between {sup 208}Pb or {sup 209}Bi targets and projectiles ranging from {sup 54}Cr through {sup 70}Zn. In such reactions, the compound nucleus can be formed at excitation energies as low as {approx}12 MeV, thus this type of reaction has been referred to as 'cold fusion'. The study of cold fusion reactions is an indispensable approach to gaining a better understanding of heavy element formation and decay. A theoretical model that successfully predicts not only the magnitudes of cold fusion cross sections, but also the shapes of excitation functions and the cross section ratios between various reaction pairs was recently developed by Swiatecki, Siwek-Wilczynska, and Wilczynski [3,4]. This theoretical model, also referred to as Fusion by Diffusion, has been the guide in all of our cold fusion studies. One particularly interesting aspect of this model is the large predicted difference in cross sections between projectiles differing by two neutrons. The projectile pair where this difference is predicted to be largest is {sup 48}Ti and {sup 50}Ti. To test and extend this model, {sup 208}Pb({sup 48}Ti,n){sup 255}Rf and {sup 208}Pb({sup 50}Ti,n){sup 257}Rf excitation functions were recently measured at the Lawrence Berkeley National Laboratory's (LBNL) 88-Inch Cyclotron utilizing the Berkeley Gas-filled Separator (BGS). The {sup 50}Ti reaction was carried out with thin lead targets ({approx}100 {micro}g/cm{sup 2}), and the {sup 48}Ti reaction with both thin and thick targets ({approx}470 {micro}g/cm{sup 2}). In addition to this reaction pair, reactions with projectile pairs {sup 52}Cr and {sup 54}Cr [5], {sup 56}Fe and {sup 58}Fe [6], and {sup 62}Ni [7] and {sup 64}Ni [8] will be discussed and compared to the Fusion by Diffusion predictions. The model predictions show a very good agreement with the data.

  6. Persistence of chromosome aberrations in mice acutely exposed to 56Fe+26 ions.

    PubMed

    Tucker, James D; Marples, Brian; Ramsey, Marilyn J; Lutze-Mann, Louise H

    2004-06-01

    Space exploration has the potential to yield exciting and significant discoveries, but it also brings with it many risks for flight crews. Among the less well studied of these are health effects from space radiation, which includes the highly charged, energetic particles of elements with high atomic numbers that constitute the galactic cosmic rays. In this study, we demonstrated that 1 Gy iron ions acutely administered to mice in vivo resulted in highly complex chromosome damage. We found that all types of aberrations, including dicentrics as well as translocations, insertions and acentric fragments, disappear rapidly with time after exposure, probably as a result of the death of heavily damaged cells, i.e. cells with multiple and/or complex aberrations. In addition, numerous cells have apparently simple exchanges as their only aberrations, and these cells appear to survive longer than heavily damaged cells. Eight weeks after exposure, the frequency of cells showing cytogenetic damage was reduced to less than 20% of the levels evident at 1 week, with little further decline apparent over an additional 8 weeks. These results indicate that exposure to 1 Gy iron ions produces heavily damaged cells, a small fraction of which appear to be capable of surviving for relatively long periods. The health effects of exposure to high-LET radiation in humans on prolonged space flights should remain a matter of concern.

  7. Acute effects of exposure to 56Fe and 16O particles on learning and memory

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although it has been shown that exposure to HZE particles disrupts cognitive performance when tested 2-4 weeks after irradiation, it has not been determined whether exposure to HZE particles can exert acute effects on cognitive performance; i.e., effects within 4-48 hrs after exposure. The present ...

  8. Persistence of chromosome aberrations in mice acutely exposed to 56Fe+26 ions.

    PubMed

    Tucker, James D; Marples, Brian; Ramsey, Marilyn J; Lutze-Mann, Louise H

    2004-06-01

    Space exploration has the potential to yield exciting and significant discoveries, but it also brings with it many risks for flight crews. Among the less well studied of these are health effects from space radiation, which includes the highly charged, energetic particles of elements with high atomic numbers that constitute the galactic cosmic rays. In this study, we demonstrated that 1 Gy iron ions acutely administered to mice in vivo resulted in highly complex chromosome damage. We found that all types of aberrations, including dicentrics as well as translocations, insertions and acentric fragments, disappear rapidly with time after exposure, probably as a result of the death of heavily damaged cells, i.e. cells with multiple and/or complex aberrations. In addition, numerous cells have apparently simple exchanges as their only aberrations, and these cells appear to survive longer than heavily damaged cells. Eight weeks after exposure, the frequency of cells showing cytogenetic damage was reduced to less than 20% of the levels evident at 1 week, with little further decline apparent over an additional 8 weeks. These results indicate that exposure to 1 Gy iron ions produces heavily damaged cells, a small fraction of which appear to be capable of surviving for relatively long periods. The health effects of exposure to high-LET radiation in humans on prolonged space flights should remain a matter of concern. PMID:15161355

  9. Protective effects of blueberry and strawberry diets on neuronal stress following exposure to 56Fe particles

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Particles of high energy and charge (HZE particles), which are abundant outside the magnetic field of the earth, have been shown to disrupt the functioning of neuronal communication in critical regions of the brain. Previous studies have shown that irradiation produces enhanced indices of oxidative ...

  10. Interaction between age and exposure to 56Fe particles on behavior and neurochemistry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previous research has shown that exposure to HZE particles, which will be encountered on long-term space missions, can adversely affect the ability of rats to perform a variety of behavioral tasks. This outcome has implications for an astronaut's ability to successfully complete requirements associ...

  11. Comparison of the Effects of Exposure to Different Particles or Energies on Behavioral Responding in Rats

    NASA Astrophysics Data System (ADS)

    Rabin, B. M.; Shukitt-Hale, B.; Joseph, J. A.; Carey, A.

    On exploratory class missions, astronauts will be exposed to a variety of heavy particles which differ in terms of quality and energy. Previous research has shown that exposure to 56Fe particles (1 GeV/n) can disrupt performance on taste aversion (CTA) learning and on operant responding using an ascending fixed-ratio schedule of reinforcement. How exposure to different types of particles and different energies will affect performance remains to be established. Rats were exposed to 56Fe (1 GeV/n, 5 GeV/n), 48Ti (1.2 GeV/n)) or 28Si (600 MeV/n) using the AGS or NSRL at Brookhaven National Laboratory. Three days following exposure, the rats were tested for the acquisition of an amphetamine-induced CTA. Compared to 1 GeV/n 56Fe, exposure to 5 GeV/n 56Fe particles required higher doses to disrupt the acquisition of an amphetamine-induced CTA. The dose-response curve for a 48Ti-induced disruption of CTA learning was similar to that produced by exposure to 1 GeV/n 56Fe particles, despite the difference in the LET of the two types of particles. In contrast the rats exposed to 28Si failed to show disruption of amphetamine-induced CTA learning, following exposure to 2.0-4.0 Gy. When tested on a ascending fixed-ratio operant task, the rats exposed to 5 GeV/n 56Fe, in contrast to the rats irradiated with 1 GeV/n 56Fe, did not show poorer performance than the non irradiated controls. These results show that the effects of exposure to heavy particles depend upon the specific particle, its energy, and the endpoint being tested. Supported by NASA Grants NAG9-1190 and NAG9-1529

  12. Neutron production in neutron-induced reactions at 96 MeV on 56Fe and 208Pb

    NASA Astrophysics Data System (ADS)

    Sagrado García, I. C.; Lecolley, J. F.; Lecolley, F. R.; Blideanu, V.; Ban, G.; Fontbonne, J. M.; Itis, G.; Lecouey, J. L.; Lefort, T.; Marie, N.; Steckmeyer, J. C.; Le Brun, C.; Blomgren, J.; Johansson, C.; Klug, J.; Orhn, A.; Mermod, P.; Olsson, N.; Pomp, S.; Osterlund, M.; Tippawan, U.; Prokofiev, A. V.; Nadel-Turonski, P.; Fallot, M.; Foucher, Y.; Guertin, A.; Haddad, F.; Vatre, M.

    2011-10-01

    Double-differential cross sections for neutron production were measured in 96-MeV neutron-induced reactions at The Svedberg Laboratory in Uppsala, Sweden. Measurements for Fe and Pb targets were performed using two independent setups: DECOI-DEMON, time-of-flight telescope dedicated to the detection of emitted neutrons with energies between a few and 50MeV and CLODIA-SCANDAL device devoted to measuring emitted neutrons with energies above 40MeV. Double-differential cross sections were measured for an angular range between 15 and 98 deg and with low-energy thresholds (≈2 MeV). Angular and energy distributions and total neutron emission cross sections have been obtained from those measurements. Results have been compared with predictions given by different models included in several transport codes (MCNPX, GEANT, TALYS, PHITS, and DYWAN) and with other experimental data (the EXFOR database).

  13. Anthocyanin-rich blueberry diets enhance protection of critical brain regions exposed to acute levels of 56Fe cosmic radiation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The protective effects of anthocyanin-rich blueberries on brain health are well documented and are particularly important under conditions of high oxidative stress which can lead to “accelerated aging”. One such scenario is exposure to space radiation, which consists of high-energy and -charge parti...

  14. Effects of 17Beta-estradiol on cognitive performance of ovariectomized female rats exposed to 56Fe particles

    Technology Transfer Automated Retrieval System (TEKTRAN)

    On exploratory class missions to other planets astronauts will be exposed to types and doses of radiation (HZE particles) that are not experienced in low earth orbit. While it is likely that the crew will consist of both male and female astronauts, there has been little research on the effects of ...

  15. The response of a spherical tissue-equivalent proportional counter to 56-Fe particles from 200-1000 MeV/nucleon

    SciTech Connect

    Gersey, Bradford B.; Borak, Thomas B.; Guetersloh, Stephen B.; Zeitlin, Cary J.; Miller, J.; Heilbronn, L.; Murakami, T.; Iwata, Y.

    2001-09-04

    The radiation environment aboard the space shuttle and the International Space Station includes high-Z and high-energy (HZE) particles that are part of the galactic cosmic radiation (GCR) spectrum. Iron-56 is considered to be one of the most biologically important parts of the GCR spectrum. Tissue-equivalent proportional counters (TEPC) are used as active dosimeters on manned space flights. These TEPC's are further used to determine average quality factor for each space mission. A TEPC simulating a 1 micron diameter sphere of tissue was exposed as part of a particle spectrometer to iron-56 at energies from 200-1000 MeV/nucleon. The response of TEPC in terms of frequency-averaged lineal energy, dose-averaged lineal energy, as well as energy deposited at different impact parameters through detector was determined for six different incident energies of iron-56 in this energy range. Calculations determined that charged particle equilibrium was achieved for each of the six experiments. Energy depositions at different impact parameters were calculated using a radial dose distribution model and the results compared to experimental data.

  16. Long term effects of low doses of 56Fe ions on the brain and retina of the mouse: Ultrastructural and behavioral studies

    NASA Astrophysics Data System (ADS)

    Philpott, Delbert E.; Miquel, Jaime

    Eight month old male C57BL6 mice were exposed without anesthesia to wholebody irradiation in circular holders. The mice were tested for behavioral decrements after 0.5 and 50 rads of Fe particle irradiation at 6 and 12 months post irradiation to obtain long term results. A standard maze was used and the animals were timed for completion thereof. A string test also was administered to the mice, testing their ability to grasp and move along a string to safety. The results from animals exposed to 50 rads were significantly different fron control results to p = <.001 in both systems of testing. The hippocampus (believed to be the location of environmental interaction in the brain) and the retina were examined for ultrastructural changes. The ultrastructural changes were similar to those we found in our Cosmos 782, 936 and in our Argon experiments. The mouse data indicate that iron particles were able to induce long term changes in the central nervous system which lead to behavioral impairment.

  17. Long term effects of low doses of 56Fe ions on the brain and retina of the mouse: ultrastructural and behavioral studies

    NASA Technical Reports Server (NTRS)

    Philpott, D. E.; Miquel, J.

    1986-01-01

    Eight month old male C57BL6 mice were exposed without anesthesia to whole-body irradiation in circular holders. The mice were tested for behavioral decrements after 0.5 and 50 rads of Fe particle irradiation at 6 and 12 months post irradiation to obtain long term results. A standard maze was used and the animals were timed for completion thereof. A string test also was administered to the mice, testing their ability to grasp and move along a string to safety. The results from animals exposed to 50 rads were significantly different from [correction of fron] control results to p = < .001 in both systems of testing. The hippocampus (believed to be the location of environmental interaction in the brain) and the retina were examined for ultrastructural changes. The ultrastructural changes were similar to those we found in our Cosmos 782, 936 and in our Argon experiments. The mouse data indicate that iron particles were able to induce long term changes in the central nervous system which lead to behavioral impairment.

  18. Role of triple phonon excitations in large angle quasi-elastic scattering of very heavy mass systems

    NASA Astrophysics Data System (ADS)

    Zamrun, Muhammad Firihu

    2016-07-01

    We study the effect of multi-phonon excitations on large-angle quasi-elastic scattering of massive systems using the full order coupled-channels formalism. We especially investigate the role of triple phonon excitations of the target and projectile nuclei on the quasi-elastic scattering cross-section as well as the barrier distribution for 54Cr, 56Fe, 64Ni and 70Zn + 208Pb systems. It is shown that the calculations taken into account, the triple octupole phonon excitations of the target and triple quadrupole phonon excitations of the projectile for these systems can explain the experimental data of the quasi-elastic cross-section and the quasi-elastic barrier distribution. These results indicate that the coupled-channels formalism is still valid even for the very heavy mass systems.

  19. 2004 Progress Report for Grant No. DE-FG03-03NA00076 Nuclear Level Densities and Gamma-ray Strength Functions: Stewardship Sciences Academic Alliances Program

    SciTech Connect

    G. E. Mitchell

    2004-10-18

    To verify the apparent large enhancement of the radiative strength function in light and medium nuclei, the 56Fe(n,2gamma)57Fe reaction was measured. The two-step cascade intensities with soft primary intensities confirm the enhancement. The combined results have been published in Physical Review Letters and featured in the Physics News Update. Data for the Yb isotopes have been combined to examine the systematics of level densities and strength function in three Yb isotopes. A paper on these results have been accepted for publication in Physical Review C. Analysis of the gamma rays from neutron induced reactions on 48Ti have been measured and analyzed for neturon energies from 1 to 250 MeV.

  20. Nuclear Data Sheets for A = 54

    SciTech Connect

    Dong, Yang; Junde, Huo

    2014-09-15

    The 2005 evaluation for A=54 (2006Hu08) has been updated. Detailed experimental nuclear structure data and decay data for all nuclei with mass chain A=54 are presented in this current evaluation. The new data and information are given in following datasets: {sup 54}Ca: {sup 9}Be({sup 76}Ge, X) and Be({sup 55}Sc, p), ({sup 56}Ti, 2p) {sup 54}Sc: {sup 54}Ca β{sup −} decay and {sup 54}Sc IT decay {sup 54}Ti: {sup 54}Sc β{sup −} decay {sup 54}Cr: {sup 54}Mn ε decay, {sup 56}Fe(μ, nupng), and {sup 238}U({sup 64}Ni, Xγ) {sup 54}Mn: {sup 51}V({sup 20}Ne, Xγ), {sup 55}Mn(p, pn), and {sup 56}Fe(μ, nu2ng) {sup 54}Fe: {sup 58}Ni α decay, {sup 9}Be({sup 55}Co, Xγ), {sup 54}Fe(e, e'), {sup 54}Fe(p, p'), and Coulomb Excitation {sup 54}Co: {sup 54}Ni ε decay, {sup 55}Cu εp decay, {sup 28}Si({sup 32}S, αpnγ), {sup 54}Fe(p,n), and {sup 54}Fe({sup 3}He, t) {sup 54}Ni: {sup 54}Ni IT decay, {sup 55}Zn εp decay, {sup 9}Be({sup 55}Ni, Xγ), and {sup 24}Mg({sup 32}S, Xγ) {sup 54}Zn: Ni({sup 58}Ni, X)

  1. Isotope ratio measurements of iron in blood samples by multi-collector ICP-MS to support nutritional investigations in humans.

    PubMed

    Benkhedda, Karima; Chen, Heidi; Dabeka, Robert; Cockell, Kevin

    2008-05-01

    With the perspective of embarking on a human study using a double iron (Fe) stable isotope tracer protocol to assess iron bioavailability, investigations were conducted on Fe isotope ratios in blood samples using a VG Axiom Multi-collector ICP-MS. The factors affecting the precision and accuracy of Fe isotopic ratios, such as spectral- and matrix-induced interferences and Fe recoveries from sample preparation, have been identified and optimized. Major polyatomic interferences (e.g., Ar-O, Ar-OH, and FeH) were significantly reduced by using an Aridus nebulizer and desolvating system. Isobaric metal (e.g., (54)Cr(+) on (54)Fe(+) and (58)Ni(+) on (58)Fe(+)) interferences and Ca-oxides and hydroxides were quantitatively removed during chemical purification of blood samples and selective isolation of Fe by anion-exchange resin, after mineralization of the blood samples by microwave digestion. Quantitative recoveries of Fe from different steps of sample preparation were verified using whole blood reference material. Fe isotopic compositions of the samples were corrected for instrumental mass bias by the standard-sample bracketing method using the certified reference standard IRMM-014. External precisions on the order of 0.008-0.05 (% RSD), 0.007-0.015 (% RSD), and 0.03-0.09 (% RSD) were obtained for (54)Fe/(56)Fe, (57)Fe/(56)Fe, and (58)Fe/(56)Fe, respectively, in the blood for three replicate measurements. The level of precision obtained in this work enables the detection of low enrichments of Fe in blood, which is highly desired in nutrition tracer studies.

  2. Effect of radiation quality on mutagenic joining of enzymatically-induced DNA double-strand breaks in previously irradiated human cells.

    PubMed

    Li, Zhentian; Wang, Huichen; Wang, Ya; Murnane, John P; Dynan, William S

    2014-11-01

    Previous work has shown that high charge and energy particle irradiation of human cells evokes a mutagenic repair phenotype, defined by increased mutagenic repair of new double-strand breaks that are introduced enzymatically, days or weeks after the initial irradiation. The effect was seen originally with 600 MeV/u (56)Fe particles, which have a linear energy transfer (LET) value of 174 keV/μm, but not with X rays or γ rays (LET ≤ 2 keV/μm). To better define the radiation quality dependence of the phenomenon, we tested two ions with intermediate LET values, 1,000 MeV/u (48)Ti (LET = 108 keV/μm) and 300 MeV/u (28)Si (LET = 69 keV/μm). These experiments used a previously validated assay, where a rare-cutting nuclease introduces double-strand breaks in two reporter transgene cassettes, which are located on different chromosomes. Deletions of a block of sequence in one of the cassettes, or translocations between cassettes, are measured independently using a multicolor fluorescence assay. The results showed that (48)Ti was a potent, but transient, inducer of mutagenic repair, based on increased frequency of nuclease-induced translocations. The (48)Ti ions did not affect the frequency of nuclease-induced deletions. The (28)Si ions had no measurable effect on either endpoint. There was a close correlation between the induction of the mutagenic repair phenomenon and the frequency of micronuclei in the targeted population (R(2) = 0.74), whereas there was no apparent correlation with radiation-induced cell inactivation. Together, these results better define the radiation quality dependence of the mutagenic repair phenomenon and establish its correlation, or lack of correlation, with other endpoints.

  3. Nuclear level densities in {sup 47}V, {sup 48}V, {sup 49}V, {sup 53}Mn, and {sup 54}Mn from neutron evaporation spectra

    SciTech Connect

    Zhuravlev, B. V. Lychagin, A. A.; Titarenko, N. N.; Demenkov, V. G.; Trykova, V. I.

    2011-03-15

    The spectra of neutrons from the (p, n) reactions on {sup 47}Ti, {sup 48}Ti, {sup 49}Ti, {sup 53}Cr, and {sup 54}Cr nuclei were measured in the proton-energy range 7-11 MeV. The measurements were performed with the aid of a fast-neutron spectrometer by the time-of-flight method over the base of the EGP-15 tandem accelerator of the Institute for Physics and Power Engineering (IPPE, Obninsk). Owing to a high resolution and a high stability of the time-of-flight spectrometer used, low-lying discrete levels could be identified reliably along with a continuum section of neutron spectra. An analysis of measured data was performed within the statistical equilibrium and preequilibrium models of nuclear reactions. The relevant calculations were performed by using the exact formalism of Hauser-Feshbach statistical theory supplemented with the generalized model of a superfluid nucleus, the back-shifted Fermi gas model, and the Gilbert-Cameron composite formula for the nuclear level density. The nuclear level densities for {sup 47}V, {sup 48}V, {sup 49}V, {sup 53}Mn, and {sup 54}Mn were determined along with their energy dependences and model parameters. The results are discussed together with available experimental data and recommendations of model systematics.

  4. Nuclear-level densities in the 49V and 57Co nuclei on the basis of evaporated-neutron spectra in ( p, n) and ( d, n) reactions

    NASA Astrophysics Data System (ADS)

    Zhuravlev, B. V.; Titarenko, N. N.

    2016-03-01

    The spectra of neutrons from the reactions 49Ti( p, n)49V and 57Fe ( p, n)57Co were measured in the range of proton energies between 8 and 11 MeV along with their counterparts from the reactions 48Ti( d, n)49V and 56Fe ( d, n)57Co at the deuteron energies of 2.7 and 3.8 MeV. These measurements were conducted with the aid of a time-of-flight fast-neutron spectrometer on the basis of the EGP-15 pulsed tandem accelerator of the Institute for Physics and Power Engineering (IPPE, Obninsk). An analysis of measured data was performed within the statistical equilibrium and preequilibrium models of nuclear reactions. The respective calculations based on the Hauser-Feshbach formalism of statistical theory were carried out with nuclear-level densities given by the generalized superfluid model of the nucleus, the backshifted Fermi-gas model, and the Gilbert-Cameron composite formula. The nuclear-level densities of 49V and 57Co and their energy dependences were determined. The results were discussed together with available experimental data and data recommended by model systematics.

  5. RESULTS FROM THE COMMISSIONING OF THE NSRL BEAM TRANSFER LINE AT BNL.

    SciTech Connect

    TSOUPAS,N.; BELLAVIA,S.; BONATI,R.; ET AL.

    2004-07-05

    The NASA SPACE RADIATION LABORATORY (NSRL) has been constructed and started operations at the Brookhaven National Laboratory in 2003. The NSRL facility will be used by NASA to perform radiation effect studies on materials and biological samples for the space program. The facility utilizes proton and heavy-ion beams of energies from 50 to 3000 MeVln which are accelerated by the AGS Booster synchrotron accelerator. To date, {sup 1}H, {sup 12}C, {sup 56}Fe, {sup 48}Ti, and {sup 197}Au ion beams of various magnetic rigidities have been extracted from the Booster, and transported by the NSRL beam transport line to the sample location which is located 100 m from the extraction point. The NSRL beam transport line has been designed to employ octupole magnetic elements which transform the normal (Gaussian) beam distribution at the location of the sample into a beam with rectangular cross section, and uniformly distributed over the sample. When using the octupole magnetic elements to obtain the uniform beam distribution on the sample, no beam-collimation is applied at any location along the NSRL beam transport line and the beam focusing on the sample is purely magnetic. The main subject of this paper will be the performance of the octupoles (third order optics) in obtaining uniform beam distributions at the target of the NSRL beam transport line.

  6. Maximizing precision of double spiked iron isotopic analyses on a Nu Plasma HR MC-ICPMS

    NASA Astrophysics Data System (ADS)

    Finlayson, V. A.; Konter, J. G.

    2012-12-01

    Non-traditional stable isotope geochemistry is a powerful tool for tracing fractionation processes in a variety of natural systems. Since variations in δ56Fe values of igneous rocks typically range from -0.3‰ to +0.3‰, with the most extreme reported values still below ± 1‰. A high degree of precision is required. We aimed to improve the internal precision and reproducibility of the double spike correction method, developed on the larger Nu Plasma 1700 at San Diego State University and adapted for the Nu Plasma HR ICPMS. We used a double spiked iron standard solution and examined the effects of variables including instrument tuning, signal-to-noise ratios, and employing ion counters to maximize the precision of isotopic measurements. Iron has four naturally occurring isotopes: 56Fe, 54Fe, 57Fe, and 58Fe. Two isobaric interferences, 54Cr and 58Ni, are removed by monitoring signals on 52Cr and 60Ni and assuming a natural ratio. Additional polyatomic argon interferences are partially resolved from the iron peaks in pseudo-high resolution mode and avoided by analyzing the iron signals on the low mass side of the peak flats. Adding to the analyte a double spike composed of an artificial mixture of the two least abundant isotopes of iron, 57Fe and 58Fe, and using an iterative solution, we can determine the "true" 56Fe/54Fe ratio. Modeling the results of the test runs revealed a correlation between variations in the nickel measurements and the corrected 56Fe/54Fe ratio. While typically not a concern for Cr since the signal on 52Cr is sufficiently high enough above the instrumental background for measurement, the 60Ni signal is present only at μV levels, not significantly higher than the electronic noise of the Faraday detectors. This error propagates through the iterative correction, resulting in poor precision during a measurement period and significant variations between measurement blocks. Further tests evaluated background measurements and the precision of the

  7. Statistical properties of excited nuclei in the mass range 47 Less-Than-Or-Slanted-Equal-To A Less-Than-Or-Slanted-Equal-To 59

    SciTech Connect

    Zhuravlev, B. V. Lychagin, A. A. Titarenko, N. N.; Demenkov, V. G.; Trykova, V. I.

    2012-09-15

    Level densities and their energy dependences for nuclei in the mass range of 47 {<=} A {<=} 59 were determined from the results obtained by measuring neutron-evaporation spectra in respective (p, n) reactions. The spectra of neutrons originating from the (p, n) reactions on {sup 47}Ti, {sup 48}Ti, {sup 49}Ti, {sup 53}Cr, {sup 54}Cr, {sup 57}Fe, and {sup 59}Co nuclei were measured in the proton-energy range of 7-11 MeV. These measurements were performed with the aid of a fast-neutron spectrometer by the time-of-flight method over the base of the EGP-15 pulsed tandem accelerator installed at the Institute for Physics and Power Engineering (Obninsk, Russia). A high resolution of the spectrometer and its stability in the time of flight made it possible to identify reliably discrete low-lying levels along with the continuum part of neutron spectra. Our measured data were analyzed within the statistical equilibrium and preequilibrium models of nuclear reactions. The respective calculations were performed with the aid of the Hauser-Feshbach formalismof statistical theory supplemented with the generalized model of a superfluid nucleus, the back-shifted Fermi gas model, and the Gilbert-Cameron composite formula for nuclear level densities. Nuclear level densities for {sup 47}V, {sup 48}V, {sup 49}V, {sup 53}Mn, {sup 54}Mn, {sup 57}Co, and {sup 59}Ni and their energy dependences were determined. The results are discussed and compared with available experimental data and with recommendations of model-based systematics.

  8. Co-culturing with High-Charge and Energy Particle Irradiated Cells Increases Mutagenic Joining of Enzymatically Induced DNA Double-Strand Breaks in Nonirradiated Cells.

    PubMed

    Li, Zhentian; Doho, Gregory; Zheng, Xuan; Jella, Kishore Kumar; Li, Shuyi; Wang, Ya; Dynan, William S

    2015-09-01

    Cell populations that have been exposed to high-charge and energy (HZE) particle radiation, and then challenged by expression of a rare-cutting nuclease, show an increased frequency of deletions and translocations originating at the enzyme cut sites. Here, we examine whether this effect also occurs in nonirradiated cells that have been co-cultured with irradiated cells. Human cells were irradiated with 0.3-1.0 Gy of either 600 MeV/u (56)Fe or 1,000 MeV/u (48)Ti ions or with 0.3-3.0 Gy of 320 kV X rays. These were co-cultured with I-SceI-expressing reporter cells at intervals up to 21 days postirradiation. Co-culture with HZE-irradiated cells led to an increase in the frequency of I-SceI-stimulated translocations and deletions in the nonirradiated cells. The effect size was similar to that seen previously in directly irradiated populations (maximum effect in bystander cells of 1.7- to 4-fold depending on ion and end point). The effect was not observed when X-ray-irradiated cells were co-cultured with nonirradiated cells, but was correlated with an increase in γ-H2AX foci-positive cells in the nonirradiated population, suggesting the presence of genomic stress. Transcriptional profiling of a directly irradiated cell population showed that many genes for cytokines and other secretory proteins were persistently upregulated, but their induction was not well correlated with functional effects on repair in co-cultured cells, suggesting that this transcriptional response alone is not sufficient to evoke the effect. The finding that HZE-irradiated cells influence the DNA double-strand break repair fidelity in their nonirradiated neighbors has implications for risk in the space radiation environment.

  9. Properties of [Pb(Zn1/3Nb2/3)O3]x- [Pb(Zr0.48Ti0.52)O3](1-x) Ceramics With Low Sintering Temperature and Their 1-3 Piezocomposites.

    PubMed

    Mensur-Alkoy, Ebru; Kaya, Mustafa Yunus; Avdan, Duygu; Alkoy, Sedat

    2016-06-01

    In this paper, dense ( x )PZN-( 1-x )PZT ceramics were prepared at sintering temperatures as low as 950 °C with PZN ratios of x=0.4 , 0.5, and 0.6. The 0.4PZN-0.6PZT composition was found to crystallize in the perovskite phase at this sintering temperature without the presence of any other secondary phases. Higher electrical and electromechanical properties were obtained from the 0.4PZN-0.6PZT composition compared with the x=0.5 and x=0.6 counterparts. Dielectric constant, piezoelectric charge coefficient, electromechanical coupling coefficient, and mechanical quality factor of 0.4PZN-0.6PZT were found to be 2608, 477 pC/N, 64.4, and 65, respectively. While the Curie temperature was 140 °C for pure PZN, the Curie temperature was measured as 300 °C for x=0.4 composition. Green PZN-PZT fibers with circular cross section were drawn using alginate gelation method from the 0.4PZN-0.6PZT composition. Dense fibers were obtained after the sintering process, and piezocomposites were prepared with 1-3 connectivity using fibers with an average diameter of 600 [Formula: see text]. Composites with volume fraction of 20 vol% were investigated for passive acoustic sensor applications. Electrical properties of piezocomposites were found to be scalable and compatible with the electrical properties of the bulk composition. The dielectric constant, piezoelectric charge coefficient, and maximum strain value of the PZN-PZT 1-3 piezocomposite were measured as 345, 165 pC/N, and 0.13%, respectively.

  10. Properties of [Pb(Zn1/3Nb2/3)O3]x- [Pb(Zr0.48Ti0.52)O3](1-x) Ceramics With Low Sintering Temperature and Their 1-3 Piezocomposites.

    PubMed

    Mensur-Alkoy, Ebru; Kaya, Mustafa Yunus; Avdan, Duygu; Alkoy, Sedat

    2016-06-01

    In this paper, dense ( x )PZN-( 1-x )PZT ceramics were prepared at sintering temperatures as low as 950 °C with PZN ratios of x=0.4 , 0.5, and 0.6. The 0.4PZN-0.6PZT composition was found to crystallize in the perovskite phase at this sintering temperature without the presence of any other secondary phases. Higher electrical and electromechanical properties were obtained from the 0.4PZN-0.6PZT composition compared with the x=0.5 and x=0.6 counterparts. Dielectric constant, piezoelectric charge coefficient, electromechanical coupling coefficient, and mechanical quality factor of 0.4PZN-0.6PZT were found to be 2608, 477 pC/N, 64.4, and 65, respectively. While the Curie temperature was 140 °C for pure PZN, the Curie temperature was measured as 300 °C for x=0.4 composition. Green PZN-PZT fibers with circular cross section were drawn using alginate gelation method from the 0.4PZN-0.6PZT composition. Dense fibers were obtained after the sintering process, and piezocomposites were prepared with 1-3 connectivity using fibers with an average diameter of 600 [Formula: see text]. Composites with volume fraction of 20 vol% were investigated for passive acoustic sensor applications. Electrical properties of piezocomposites were found to be scalable and compatible with the electrical properties of the bulk composition. The dielectric constant, piezoelectric charge coefficient, and maximum strain value of the PZN-PZT 1-3 piezocomposite were measured as 345, 165 pC/N, and 0.13%, respectively. PMID:27101604

  11. Iron isotope biosignatures.

    PubMed

    Beard, B L; Johnson, C M; Cox, L; Sun, H; Nealson, K H; Aguilar, C

    1999-09-17

    The (56)Fe/(54)Fe of Fe-bearing phases precipitated in sedimentary environments varies by 2.5 per mil (delta(56)Fe values of +0.9 to -1. 6 per mil). In contrast, the (56)Fe/(54)Fe of Fe-bearing phases in igneous rocks from Earth and the moon does not vary measurably (delta(56)Fe = 0.0 +/- 0.3 per mil). Experiments with dissimilatory Fe-reducing bacteria of the genus Shewanella algae grown on a ferrihydrite substrate indicate that the delta(56)Fe of ferrous Fe in solution is isotopically lighter than the ferrihydrite substrate by 1.3 per mil. Therefore, the range in delta(56)Fe values of sedimentary rocks may reflect biogenic fractionation, and the isotopic composition of Fe may be used to trace the distribution of microorganisms in modern and ancient Earth.

  12. Iron isotope biosignatures

    NASA Technical Reports Server (NTRS)

    Beard, B. L.; Johnson, C. M.; Cox, L.; Sun, H.; Nealson, K. H.; Aguilar, C.

    1999-01-01

    The (56)Fe/(54)Fe of Fe-bearing phases precipitated in sedimentary environments varies by 2.5 per mil (delta(56)Fe values of +0.9 to -1. 6 per mil). In contrast, the (56)Fe/(54)Fe of Fe-bearing phases in igneous rocks from Earth and the moon does not vary measurably (delta(56)Fe = 0.0 +/- 0.3 per mil). Experiments with dissimilatory Fe-reducing bacteria of the genus Shewanella algae grown on a ferrihydrite substrate indicate that the delta(56)Fe of ferrous Fe in solution is isotopically lighter than the ferrihydrite substrate by 1.3 per mil. Therefore, the range in delta(56)Fe values of sedimentary rocks may reflect biogenic fractionation, and the isotopic composition of Fe may be used to trace the distribution of microorganisms in modern and ancient Earth.

  13. Exposure to heavy charged particles affects thermoregulation in rats

    SciTech Connect

    Kandasamy, S.B.; Hunt, W.A.; Dalton, T.K.; Joseph, J.A.; Harris, A.H.; Rabin, B.M. |

    1994-09-01

    Rats exposed to 0.1-5 Gy of heavy particles ({sup 56}Fe, {sup 40}Ar, {sup 20}Ne or {sup 4}He) showed dose-dependent changes in body temperature. Lower doses of all particles produced hyperthermia, and higher doses of {sup 20}Ne and {sup 56}Fe produced hypothermia. Of the four HZE particles, {sup 56}Fe particles were the most potent and {sup 4}He particles were the least potent in producing changes in thermoregulation. The {sup 20}Ne and {sup 40}Ar particles produced an intermediate level of change in body temperature. Significantly greater hyperthermia was produced by exposure to 1 Gy of {sup 20}Ne, {sup 40}Ar and {sup 56}Fe particles than by exposure to 1 Gy of {sup 60}Co {gamma} rays. Pretreating rats with the cyclo-oxygenase inhibitor indomethacin attenuated the hyperthermia produced by exposure to 1 Gy of {sup 56}Fe particles, indicating that prostaglandins mediate {sup 56}Fe-particle-induced hyperthermia. The hypothermia produced by exposure to 5 Gy of {sup 56}Fe particles is mediated by histamine and can be attenuated by treatment with the antihistamines mepyramine and cimetidine. 15 refs., 4 figs.

  14. Effect of track structure and radioprotectors on the induction of oncogenic transformation in murine fibroblasts by heavy ions

    NASA Technical Reports Server (NTRS)

    Miller, R. C.; Martin, S. G.; Hanson, W. R.; Marino, S. A.; Hall, E. J.; Wachholz, B. W. (Principal Investigator)

    1998-01-01

    The oncogenic potential of high-energy 56Fe particles (1 GeV/nucleon) accelerated with the Alternating Gradient Synchrotron at the Brookhaven National Laboratory was examined utilizing the mouse C3H 10T1/2 cell model. The dose-averaged LET for high-energy 56Fe is estimated to be 143 keV/micrometer with the exposure conditions used in this study. For 56Fe ions, the maximum relative biological effectiveness (RBEmax) values for cell survival and oncogenic transformation were 7.71 and 16.5 respectively. Compared to 150 keV/micrometer 4He nuclei, high-energy 56Fe nuclei were significantly less effective in cell killing and oncogenic induction. The prostaglandin E1 analog misoprostol, an effective oncoprotector of C3H 10T1/2 cells exposed to X rays, was evaluated for its potential as a radioprotector of oncogenic transformation with high-energy 56Fe. Exposure of cells to misoprostol did not alter 56Fe cytotoxicity or the rate of 56Fe-induced oncogenic transformation.

  15. Evidence for the dipole nature of the low-energy γ enhancement in Fe56

    DOE PAGES

    Larsen, A. C.; Blasi, N.; Bracco, A.; Camera, F.; Eriksen, T. K.; Gorgen, A.; Guttormsen, M.; Hagen, T. W.; Leoni, S.; Million, B.; et al

    2013-12-11

    Here, the γ-ray strength function of 56Fe has been measured from proton-γ coincidences for excitation energies up to ≈11 MeV. The low-energy enhancement in the γ-ray strength function, which was first discovered in the (3He,αγ)56Fe reaction, is confirmed with the (p,p'γ)56Fe experiment reported here. Angular distributions of the γ rays give for the first time evidence that the enhancement is dominated by dipole transitions.

  16. Detection of Remarkably Low Isotopic Ratio of Iron in Anthropogenic Aerosols and Evaluation of its Contribution to the Surface Ocean

    NASA Astrophysics Data System (ADS)

    Kurisu, M.; Iizuka, T.; Sakata, K.; Uematsu, M.; Takahashi, Y.

    2015-12-01

    It has been reported that phytoplankton growth in the High Nutrient-Low Chlorophyll (HNLC) regions is limited by dissolved iron (DFe) concentration (e.g., Martin and Fitzwater, 1988). Aerosol is known as one of the dominant sources of DFe to the ocean and classified into two origins such as anthropogenic and natural. A series of recent studies showed that Fe in anthropogenic aerosols is more soluble than that in natural aerosols (Takahashi et al., 2013) and has lower isotopic ratio (Mead et al., 2013). However, the difference between Fe isotopic ratio (δ56Fe: [(56Fe/54Fe)sample/(56Fe/54Fe)IRMM-14]-1) of two origins reported in Mead et al. (2013) is not so large compared with the standard deviation. Therefore, the aim of this study is to determine Fe species and δ56Fe in anthropogenic aerosols more accurately and to evaluate its contribution to the ocean surface. Iron species were determined by X-ray absorption fine structure (XAFS) analysis, while δ56Fe in size-fractionated aerosols were measured by MC-ICP-MS (NEPTUNE Plus) after chemical separation using anion exchange resin. Dominant Fe species in the samples were, ferrihydrite, hematite, and biotite. It was also revealed that coarse particles contained a larger amount of biotite and that fine particles contained a larger amount of hematite, which suggested that anthropogenic aerosols were emitted during combustion processes. In addition, results of Fe isotopic ratio analysis suggested that δ56Fe of coarse particles were around +0.25‰, whereas that of fine particles were -0.5 ˜ -2‰, which was lower than the δ56Fe in anthropogenic aerosol by Mead et al. (2013). The size-fractionated sampling made it possible to determine the δ56Fe in anthropogenic aerosol. Soluble component in fine particles extracted by simulated rain water also showed much lower δ56Fe56Fe = -3.9±0.12‰), suggesting that anthropogenic Fe has much lower isotopic ratio. The remarkably low δ56Fe may be caused by the

  17. NEUTRON-RICH CHROMIUM ISOTOPE ANOMALIES IN SUPERNOVA NANOPARTICLES

    SciTech Connect

    Dauphas, N.; Remusat, L.; Papanastassiou, D. A.; Guan, Y.; Ma, C.; Eiler, J. M.; Chen, J. H.; Roskosz, M.; Stodolna, J.

    2010-09-10

    Neutron-rich isotopes with masses near that of iron are produced in Type Ia and II supernovae (SNeIa and SNeII). Traces of such nucleosynthesis are found in primitive meteorites in the form of variations in the isotopic abundance of {sup 54}Cr, the most neutron-rich stable isotope of chromium. The hosts of these isotopic anomalies must be presolar grains that condensed in the outflows of SNe, offering the opportunity to study the nucleosynthesis of iron-peak nuclei in ways that complement spectroscopic observations and can inform models of stellar evolution. However, despite almost two decades of extensive search, the carrier of {sup 54}Cr anomalies is still unknown, presumably because it is fine grained and is chemically labile. Here, we identify in the primitive meteorite Orgueil the carrier of {sup 54}Cr anomalies as nanoparticles (<100 nm), most likely spinels that show large enrichments in {sup 54}Cr relative to solar composition ({sup 54}Cr/{sup 52}Cr ratio >3.6 x solar). Such large enrichments in {sup 54}Cr can only be produced in SNe. The mineralogy of the grains supports condensation in the O/Ne-O/C zones of an SNII, although a Type Ia origin cannot be excluded. We suggest that planetary materials incorporated different amounts of these nanoparticles, possibly due to late injection by a nearby SN that also delivered {sup 26}Al and {sup 60}Fe to the solar system. This idea explains why the relative abundance of {sup 54}Cr and other neutron-rich isotopes vary between planets and meteorites. We anticipate that future isotopic studies of the grains identified here will shed new light on the birth of the solar system and the conditions in SNe.

  18. Evaluating the earliest traces of Archean sub-seafloor life by NanoSIMS

    NASA Astrophysics Data System (ADS)

    Mcloughlin, N.; Grosch, E. G.; Kilburn, M.; Wacey, D.

    2012-12-01

    The Paleoarchean sub-seafloor has been proposed as an environment for the emergence of life with titanite microtextures in pillow lavas argued to be the earliest traces of microbial micro-tunneling (Furnes et al. 2004). Here we use a nano-scale ion microprobe (NanoSIMS) to evaluate possible geochemical traces of life in 3.45 Ga pillow lavas of the Barberton Greenstone Belt, South Africa. We investigated both surface and drill core samples from the original "Biomarker" outcrop in the Hooggenoeg Fm. Pillow lava metavolcanic glass contain clusters of segmented microcrystalline titanite filaments, ~4μm across and <200μm in length. Their size, shape and distribution have been directly compared to those found in recent oceanic crust. Thus it has been argued that they are the mineralized remains of tunnels formed by microbes that etched volcanic glass in the Archean sub-seafloor (Furnes et al 2004; Banerjee et al. 2006). Elemental mapping by NanoSIMS was undertaken to investigate reports of enrichments in carbon (possibly also nitrogen) along the margins of the microtextures previously interpreted as decayed cellular remains. We mapped for 12C-, 26CN-, 32S- along with 16O-, 28Si-, 24Mg+,27Al+, 40Ca+, 48Ti+ and 56Fe+ in chlorite and quartz hosted examples. The 12C- or 26CN- linings were not found along the margins of the microtextures in neither the original, nor the drill core samples, despite NanoSIMS being a more sensitive and higher-spatial-resolution technique than earlier microprobe X-ray maps. The absence of organic linings in these samples excludes a key line of evidence previously used to support the biogenicity of the microtextures. Sulfur isotopes 32S and 34S were measured by NanoSIMS on two types of sulfide: i) small sulfides (1-15μm) intimately associated with the microtextures and; ii) larger sulfides (10-60μm) that cross-cut the microtextures and are disseminated near a quartz-carbonate vein. The sulfide inclusions in the microtextures have strongly

  19. Nuclear fragmentation of GCR-like ions: comparisons between data and PHITS

    NASA Astrophysics Data System (ADS)

    Zeitlin, Cary; Guetersloh, Stephen; Heilbronn, Lawrence; Miller, Jack; Sihver, Lembit; Mancusi, Davide; Fukumura, Aki; Iwata, Yoshi; Murakami, Takeshi

    We present a summary of results from recent work in which we have compared nuclear fragmentation cross section data to predictions of the PHITS Monte Carlo simulation. The studies used beams of 12 C, 35 Cl, 40 Ar, 48 Ti, and 56 Fe at energies ranging from 290 MeV/nucleon to 1000 MeV/nucleon. Some of the data were obtained at the Brookhaven National Laboratory, others at the National Institute of Radiological Sciences in Japan. These energies and ion species are representative of the heavy ion component of the Galactic Cosmic Rays (GCR), which contribute significantly to the dose and dose equivalent that will be received by astronauts on deep-space missions. A critical need for NASA is the ability to accurately model the transport of GCR heavy ions through matter, including spacecraft walls, equipment racks, and other shielding materials, as well as through tissue. Nuclear interaction cross sections are of primary importance in the GCR transport problem. These interactions generally cause the incoming ion to break up (fragment) into one or more lighter ions, which continue approximately along the initial trajectory and with approximately the same velocity the incoming ion had prior to the interaction. Since the radiation dose delivered by a particle is proportional to the square of the quantity (charge/velocity), i.e., to (Z/β)2 , fragmentation reduces the dose (and, typically, dose equivalent) delivered by incident ions. The other mechanism by which dose can be reduced is ionization energy loss, which can lead to some particles stopping in the shielding. This is the conventional notion of shielding, but it is not applicable to human spaceflight, since the particles in the GCR tend to be highly energetic and because shielding must be relatively thin in order to keep overall mass as low as possible, keeping launch costs within reason. To support these goals, our group has systematically measured a large number of nuclear cross sections, intended to be used as either

  20. Pathways of coupled arsenic and iron cycling in high arsenic groundwater of the Hetao basin, Inner Mongolia, China: an iron isotope approach

    USGS Publications Warehouse

    Guo, Huaming; Liu, Chen; Lu, Hai; Wanty, Richard B.; Wang, Jun; Zhou, Yinzhu

    2013-01-01

    High As groundwater is widely distributed all over the world, which has posed a significant health impact on millions of people. Iron isotopes have recently been used to characterize Fe cycling in aqueous environments, but there is no information on Fe isotope characteristics in the groundwater. Since groundwater As behavior is closely associated with Fe cycling in the aquifers, Fe isotope signatures may help to characterize geochemical processes controlling As concentrations of shallow groundwaters. This study provides the first observation of Fe isotope fractionation in high As groundwater and evaluation of Fe cycling and As behaviors in shallow aquifers in terms of Fe isotope signatures. Thirty groundwater samples were taken for chemical and isotopic analysis in the Hetao basin, Inner Mongolia. Thirty-two sediments were sampled as well from shallow aquifers for Fe isotope analysis. Results showed that groundwater was normally enriched in isotopically light Fe with δ56Fe values between −3.40‰ and 0.58‰ and median of −1.14‰, while heavier δ56Fe values were observed in the sediments (between −1.10‰ and 0.75‰, median +0.36‰). In reducing conditions, groundwaters generally had higher δ56Fe values, in comparison with oxic conditions. High As groundwaters, generally occurring in reducing conditions, had high δ56Fe values, while low As groundwaters normally had low δ56Fe values. Although sediment δ56Fe values were generally independent of lithological conditions, a large variation in sediment δ56Fe values was observed in the oxidation–reduction transition zone. Three pathways were identified for Fe cycling in shallow groundwater, including dissimilatory reduction of Fe(III) oxides, re-adsorption of Fe(II), and precipitation of pyrite and siderite. Dissimilatory reduction of Fe(III) oxides resulted in light δ56Fe values (around −1.0‰) and high As concentration (>50 μg/L) in groundwater in anoxic conditions. Re-adsorption of isotopically

  1. The Chromium Isotopic Composition of the Ungrouped Carbonaceous Chondrite Tagish Lake

    NASA Astrophysics Data System (ADS)

    Petitat, M.; Birck, J.-L.; Luu, T. H.; Gounelle, M.

    2011-07-01

    Early solar materials bear a variety of isotopic anomalies that reflect compositional differences deriving from distinct stellar nucleosynthetic processes. As shown in previous studies, the stepwise dissolution with increasing acid strengths of bulk rock carbonaceous chondrites liberates Cr with both excesses and deficits in 53Cr and 54Cr relative to the terrestrial standard. The magnitude of the 54Cr variations within a meteorite decreases in the sequence CI1 > CR2 > CM2 > CV3 > CO3 > CK4 and correlates with the degree of metamorphism of each carbonaceous chondrite class. This study shows that the Tagish Lake meteorite presents the highest excesses in 54Cr ever measured in a bulk silicate phase. According to this study, the Tagish Lake meteorite is composed of the least re-equilibrated material known at this time. The magnitude of 54Cr variation decreases now in the following sequence: Tagish Lake (ungrouped CI2) > Orgueil (CI1) > Murchison (CM2) > Allende (CV2). Moreover, this study shows that excesses in 53Cr relative to Earth can be interpreted as representing the extent of aqueous alteration on meteorite parent bodies. Finally, the high 54Cr anomalies measured in this meteorite make Tagish Lake one of the major targets to decipher the host of these anomalies.

  2. THE CHROMIUM ISOTOPIC COMPOSITION OF THE UNGROUPED CARBONACEOUS CHONDRITE TAGISH LAKE

    SciTech Connect

    Petitat, M.; Gounelle, M.; Birck, J.-L.; Luu, T. H.

    2011-07-20

    Early solar materials bear a variety of isotopic anomalies that reflect compositional differences deriving from distinct stellar nucleosynthetic processes. As shown in previous studies, the stepwise dissolution with increasing acid strengths of bulk rock carbonaceous chondrites liberates Cr with both excesses and deficits in {sup 53}Cr and {sup 54}Cr relative to the terrestrial standard. The magnitude of the {sup 54}Cr variations within a meteorite decreases in the sequence CI1 > CR2 > CM2 > CV3 > CO3 > CK4 and correlates with the degree of metamorphism of each carbonaceous chondrite class. This study shows that the Tagish Lake meteorite presents the highest excesses in {sup 54}Cr ever measured in a bulk silicate phase. According to this study, the Tagish Lake meteorite is composed of the least re-equilibrated material known at this time. The magnitude of {sup 54}Cr variation decreases now in the following sequence: Tagish Lake (ungrouped CI2) > Orgueil (CI1) > Murchison (CM2) > Allende (CV2). Moreover, this study shows that excesses in {sup 53}Cr relative to Earth can be interpreted as representing the extent of aqueous alteration on meteorite parent bodies. Finally, the high {sup 54}Cr anomalies measured in this meteorite make Tagish Lake one of the major targets to decipher the host of these anomalies.

  3. Genotoxic effects of high-energy iron particles in human lymphoblasts differing in radiation sensitivity

    NASA Technical Reports Server (NTRS)

    Evans, H. H.; Horng, M. F.; Evans, T. E.; Jordan, R.; Schwartz, J. L.

    2001-01-01

    The effects of (56)Fe particles and (137)Cs gamma radiation were compared in TK6 and WTK1 human lymphoblasts, two related cell lines which differ in TP53 status and in the ability to rejoin DNA double-strand breaks. Both cell lines were more sensitive to the cytotoxic and clastogenic effects of (56)Fe particles than to those of gamma rays. However, the mutagenicity of (56)Fe particles and gamma rays at the TK locus was the same per unit dose and was higher for gamma rays than for (56)Fe particles at isotoxic doses. The respective RBEs for TK6 and WTK1 cells were 1.5 and 1.9 for cytotoxicity and 2.5 and 1.9 for clastogenicity, but only 1 for mutagenicity. The results indicate that complex lesions induced by (56)Fe particles are repaired less efficiently than gamma-ray-induced lesions, leading to fewer colony-forming cells, a slightly higher proportion of aberrant cells at the first division, and a lower frequency of viable mutants at isotoxic doses. WTK1 cells (mutant TP53) were more resistant to the cytotoxic effects of both gamma rays and (56)Fe particles, but showed greater cytogenetic and mutagenic damage than TK6 cells (TP53(+)). A deficiency in the number of damaged TK6 cells (a) reaching the first mitosis after exposure and (b) forming viable mutants can explain these results.

  4. Chromium isotopic systematics of the Sutter's Mill carbonaceous chondrite: Implications for isotopic heterogeneities of the early solar system

    NASA Astrophysics Data System (ADS)

    Yamakawa, Akane; Yin, Qing-Zhu

    2014-11-01

    Recent studies have shown that major meteorite groups possess their own characteristic 54Cr values, demonstrating the utility of Cr isotopes for identifying genetic relationships between the planetary materials in conjunction with other classical tools, such as oxygen isotopes. In this study, we performed Cr isotope analyses for whole rocks and chemically separated phases of the new CM2 chondrite, Sutter's Mill (SM 43 and 51). The two whole rocks of Sutter's Mill show essentially identical ɛ54Cr excesses (SM 43 = +0.95 ± 0.09ɛ, SM 51 = +0.88 ± 0.07ɛ), relative to the Earth. These values are the same within error with that of the CM2-type Murchison (+0.89 ± 0.08ɛ), suggesting that parent bodies of Sutter's Mill and Murchison were formed from the same precursor materials in the solar nebula. Large ɛ54Cr excess of up to 29.40ɛ is observed in the silicate phase of Sutter's Mill, while that of Murchison shows 15.74ɛ. Importantly, the leachate fractions of both Sutter's Mill and Murchison form a steep linear anticorrelation between ɛ54Cr and ɛ53Cr, cross-cutting the positive correlation previously observed in carbonaceous chondrites. The fact that L4 acid leachate fraction contains higher 54Cr excesses than that of L5 step designed to dissolve refractory minerals suggests that spinel is not a major 54Cr carrier. We also note that L5 contains 53Cr anomalies lower than the solar initial value, suggesting it carries a component of nucleosynthetic anomaly unrelated to the 53Mn decay. We have identified five endmember components of nucleosynthetic origin among the early solar system materials.

  5. CHROMIUM ISOTOPE SYSTEMATICS OF ACHONDRITES: CHRONOLOGY AND ISOTOPIC HETEROGENEITY OF THE INNER SOLAR SYSTEM BODIES

    SciTech Connect

    Yamakawa, Akane; Yamashita, Katsuyuki; Makishima, Akio; Nakamura, Eizo

    2010-09-01

    The standard planetary formation models assume that primitive materials, such as carbonaceous chondrites, are the precursor materials of evolved planetesimals. Past chronological studies have revealed that planetesimals of several hundred kilometers in size, such as the Howardite-Eucrite-Diogenite (HED) parent body (Vesta) and angrite parent body, began their differentiation as early as {approx}3 million years of the solar system formation, and continued for at least several million years. However, the timescale of planetesimal formation in distinct regions of the inner solar system, as well as the isotopic characteristics of the reservoirs from which they evolved, remains unclear. Here we present the first report for the precise {sup 53}Mn-{sup 53}Cr ages of monomict ureilites. Chemically separated phases from one monomict ureilite (NWA 766) yielded the Mn-Cr age of 4564.60 {+-} 0.67 Ma, identical within error to the oldest age preserved in other achondrites, such as angrites and eucrites. The {sup 54}Cr isotopic data for this and seven additional bulk ureilites show homogeneous {epsilon}{sup 54}Cr of {approx}-0.9, a value distinct from other achondrites and chondrites. Using the {epsilon}{sup 54}Cr signatures of Earth, Mars, and Vesta (HED), we noticed a linear decrease in the {epsilon}{sup 54}Cr value with the heliocentric distance in the inner region of the solar system. If this trend can be extrapolated into the outer asteroid belt, the {epsilon}{sup 54}Cr signatures of monomict ureilites will place the position of the ureilite parent body at {approx}2.8 AU. These observations imply that the differentiation of achondrite parent bodies began nearly simultaneously at {approx}4565 Ma in different regions of the inner solar system. The distinct {epsilon}{sup 54}Cr value between ureilite and carbonaceous chondrite also implies that a genetic link commonly proposed between the two is unlikely.

  6. Nucleosynthetic strontium isotope anomalies in carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Yokoyama, Tetsuya; Fukami, Yusuke; Okui, Wataru; Ito, Nobuaki; Yamazaki, Hiroshi

    2015-04-01

    Precise Sr isotopic compositions in samples from sequential acid leaching experiments have been determined for three carbonaceous chondrites, Allende, Murchison, and Tagish Lake, together with those in the bulk aliquots of these meteorites. The chondritic acid leachates and residues were characterized by Sr isotope anomalies with variable μ84Sr values (106 relative deviation from a standard material) ranging from +120 to - 4700 ppm, documenting multiple nucleosynthetic sources within a single meteorite. In addition, the μ84Sr patterns across leaching samples for individual chondrites differed from one another. The highest μ84Sr values were observed for leaching Step 3 (HCl+H2O, 75 °C) for Allende and Murchison likely because of the incorporation of calcium and aluminum-rich inclusions (CAIs). In contrast, extremely low μ84Sr values were observed in the later fractions (Steps 6 and 7) for Murchison and Tagish Lake, suggesting the existence of s-process-enriched presolar SiC grains derived from AGB stars. A μ84Sr-ɛ54Cr diagram was prepared with the CAIs and bulk aliquots of carbonaceous chondrites and other meteorites (noncarbonaceous) that were plotted separately; however, they still formed a global positive correlation. CAIs presented the highest μ84Sr and ɛ54Cr values, whereas carbonaceous chondrites and noncarbonaceous meteorites had intermediate and the lowest μ84Sr and ɛ54Cr values, respectively. The positive trend was interpreted as resulting from global thermal processing in which sublimation of high μ84Sr and ɛ54Cr carriers generated the excess μ84Sr and ɛ54Cr signatures in CAIs, while noncarbonaceous planetesimals accreted from materials that underwent significant thermal processing and thus had relatively low μ84Sr and ɛ54Cr values. Apart from the global trend, the carbonaceous chondrites and noncarbonaceous meteorites both exhibited intrinsic variations that highlight an isotopic dichotomy similar to that observed in other isotope

  7. Magnesium activation of GTP hydrolysis or incubation in S-adenosyl-l-methionine reverses iron-56-particle-induced decrements in oxotremorine enhancement of K+-evoked striatal release of dopamine.

    PubMed

    Joseph, J A; Shukitt-Hale, B; McEwen, J; Rabin, B

    1999-12-01

    Previous research has determined that the deficits in motor behavior seen in aged animals irradiated with (56)Fe particles involved alterations in muscarinic receptor sensitivity. In the present experiments, we determined whether increasing either membrane fluidity by exposure of striatal slices from irradiated ((56)Fe particles) animals to S-adenosyl-l-methionine (SAM) or GTP hydrolysis with Mg(2+) would reverse this (56)Fe-particle-induced loss of muscarinic receptor sensitivity, as has been observed in aged animals. Results indicated that, while increasing Mg(2+) concentrations in the incubation medium was effective in reducing the radiation effects, SAM was able to effect some reversal of the radiation effects only at the lower concentration (200 microM). These results suggest that similar mechanisms may be involved in the deficits in signal transduction seen after (56)Fe-particle irradiation to those seen in aging, and that these may include changes in the membrane structure or composition that could alter subsequent responsiveness of transduction pathways. The results further suggest that, as has been reported previously, (56)Fe-particle irradiation may accelerate brain aging, and that since these HZE particles contribute at least 1% of the dose that astronauts would receive from cosmic rays, long-term exposure on extended space flights (e.g. to Mars) may produce similar deficits that could have immediate or delayed effects on behavior. PMID:10581534

  8. Corrosion behaviour of materials at elevated temperatures in an oxidising atmosphere containing sulphur derivatives: influence of the compositon of aggressive phases and of the tested alloys. Final report. [Uranus S; Ni-5. 4Cr-3Al]. Tenue a la corrosion a temperature elevee de materiaux par les milieux oxydants contenant des derives soufres: influence de la composition des phases agressives et des alliages experimentes. rapport final

    SciTech Connect

    Cappelaere, M.; Lechaudel, R.; Turcot, G.

    1984-01-01

    Investigations on the resistance of Alloy 800, Uranus S, and Fe-Cr-Al (5.4% Cr, 3% Al) to sulphur dioxide have been carried out, considering three variables:- (1) duration of tests, (2) pressure of sulphur dioxide, and (3) concentration of bromine (10 and 100 x 10 to the minus 6 power by weight).

  9. Behavioral endpoints for radiation injury

    NASA Astrophysics Data System (ADS)

    Rabin, B. M.; Joseph, J. A.; Hunt, W. A.; Dalton, T. B.; Kandasamy, S. B.; Harris, A. H.; Ludewig, B.

    1994-10-01

    The relative behavioral effectiveness of heavy particles was evaluated. Using the taste aversion paradigm in rats, the behavioral toxicity of most types of radiation (including 20Ne and 40Ar) was similar to that of 60Co photons. Only 56Fe and 93Nb particles and fission neutrons were significantly more effective. Using emesis in ferrets as the behavioral endpoint, 56Fe particles and neutrons were again the most effective; however, 60Co photons were significantly more effective than 18 MeV electrons. These results suggest that LET does not completely predict behavioral effectiveness. Additionally, exposing rats to 10 cGy of 56Fe particles attenuated amphetamine-induced taste aversion learning. This behavior is one of a broad class of behaviors which depends on the integrity of the dopaminergic system and suggests the possibility of alterations in these behaviors following exposure to heavy particles in a space radiation environment.

  10. A model for Cryogenian iron formation

    NASA Astrophysics Data System (ADS)

    Cox, Grant M.; Halverson, Galen P.; Poirier, André; Le Heron, Daniel; Strauss, Justin V.; Stevenson, Ross

    2016-01-01

    The Neoproterozoic Tatonduk (Alaska) and Holowilena (South Australia) iron formations share many characteristics including their broadly coeval (Sturtian) ages, intimate association with glaciogenic sediments, and mineralogy. We show that these shared characteristics extend to their neodymium (εNd) and iron isotope (δ56Fe) systematics. In both regions δ56Fe values display a distinct up-section trend to isotopically heavier values, while εNd values are primitive and similar to non-ferruginous mudstones within these successions. The δ56Fe profiles are consistent with oxidation of ferruginous waters during marine transgression, and the εNd values imply that much of this iron was sourced from the leaching of continental margin sediments largely derived from continental flood basalts. Rare earth element data indicate a secondary hydrothermal source for this iron.

  11. Probing dynamics of fusion reactions through cross-section and spin distribution measurement

    NASA Astrophysics Data System (ADS)

    Kaur, Maninder; Behera, B. R.; Singh, Gulzar; Singh, Varinderjit; Madhavan, N.; Muralithar, S.; Nath, S.; Gehlot, J.; Mohanto, G.; Mukul, Ish; Siwal, D.; Thakur, M.; Kapoor, K.; Sharma, P.; Banerjee, T.; Jhingan, A.; Varughese, T.; Bala, Indu; Nayak, B. K.; Saxena, A.; Chatterjee, M. B.; Stevenson, P. D.

    2016-05-01

    Present work aims to explicate the effect of entrance channel mass asymmetry on fusion dynamics for the Compound Nucleus 80Sr populated through two different channels, 16O+64Zn and 32S+48Ti, using cross-section and spin distribution measurements as probes. The evaporation spectra studies for these systems, reported earlier indicate the presence of dynamical effects for mass symmetric 32S+48Ti system.The CCDEF and TDHF calculations have been performed for both the systems and an attempt has been made to explain the reported deviations in the α-particle spectrum for the mass symmetric system.

  12. The effect of early diagenesis on the Fe isotope compositions of porewaters and authigenic minerals in continental margin sediments

    NASA Astrophysics Data System (ADS)

    Severmann, Silke; Johnson, Clark M.; Beard, Brian L.; McManus, James

    2006-04-01

    Iron isotope compositions in marine pore fluids and sedimentary solid phases were measured at two sites along the California continental margin, where isotope compositions range from δ 56Fe = -3.0‰ to +0.4‰. At one site near Monterey Canyon off central California, organic matter oxidation likely proceeds through a number of diagenetic pathways that include significant dissimilatory iron reduction (DIR) and bacterial sulfate reduction, whereas at our other site in the Santa Barbara basin DIR appears to be comparatively small, and production of sulfides (FeS and pyrite) was extensive. The largest range in Fe isotope compositions is observed for Fe(II) aq in porewaters, which generally have the lowest δ 56Fe values (minimum: -3.0‰) near the sediment surface, and increase with burial depth. δ 56Fe values for FeS inferred from HCl extractions vary between ˜-0.4‰ and +0.4‰, but pyrite is similar at both stations, where an average δ 56Fe value of -0.8 ± 0.2‰ was measured. We interpret variations in dissolved Fe isotope compositions to be best explained by open-system behavior that involves extensive recycling of Feflux. This study is the first to examine Fe isotope variations in modern marine sediments, and the results show that Fe isotopes in the various reactive Fe pools undergo isotopic fractionation during early diagenesis. Importantly, processes dominated by sulfide formation produce high-δ 56Fe values for porewaters, whereas the opposite occurs when Fe(III)-oxides are present and DIR is a major pathway of organic carbon respiration. Because shelf pore fluids may carry a negative δ 56Fe signature it is possible that the Fe isotope composition of ocean water reflects a significant contribution of shelf-derived iron to the open ocean. Such a signature would be an important means for tracing iron sources to the ocean and water mass circulation.

  13. Heavy Ion Radiation Exposure Triggered Higher Intestinal Tumor Frequency and Greater β-Catenin Activation than γ Radiation in APCMin/+ Mice

    PubMed Central

    Datta, Kamal; Suman, Shubhankar; Kallakury, Bhaskar V. S.; Fornace, Albert J.

    2013-01-01

    Risk of colorectal cancer (CRC) after exposure to low linear energy transfer (low-LET) radiation such as γ-ray is highlighted by the studies in atom bomb survivors. On the contrary, CRC risk prediction after exposure to high-LET cosmic heavy ion radiation exposure is hindered due to scarcity of in vivo data. Therefore, intestinal tumor frequency, size, cluster, and grade were studied in APCMin/+ mice (n = 20 per group; 6 to 8 wks old; female) 100 to 110 days after exposure to 1.6 or 4 Gy of heavy ion 56Fe radiation (energy: 1000 MeV/nucleon) and results were compared to γ radiation doses of 2 or 5 Gy, which are equitoxic to 1.6 and 4 Gy 56Fe respectively. Due to relevance of lower doses to radiotherapy treatment fractions and space exploration, we followed 2 Gy γ and equitoxic 1.6 Gy 56Fe for comparative analysis of intestinal epithelial cell (IEC) proliferation, differentiation, and β-catenin signaling pathway alterations between the two radiation types using immunoblot, and immunohistochemistry. Relative to controls and γ-ray, intestinal tumor frequency and grade was significantly higher after 56Fe radiation. Additionally, tumor incidence per unit of radiation (per cGy) was also higher after 56Fe radiation relative to γ radiation. Staining for phospho-histone H3, indicative of IEC proliferation, was more and alcian blue staining, indicative of IEC differentiation, was less in 56Fe than γ irradiated samples. Activation of β-catenin was more in 56Fe-irradiated tumor-free and tumor-bearing areas of the intestinal tissues. When considered along with higher levels of cyclin D1, we infer that relative to γ radiation exposure to 56Fe radiation induced markedly reduced differentiation, and increased proliferative index in IEC resulting in increased intestinal tumors of larger size and grade due to preferentially greater activation of β-catenin and its downstream effectors. PMID:23555653

  14. Interaction of electron neutrino with LSD detector

    NASA Astrophysics Data System (ADS)

    Ryazhskaya, O. G.; Semenov, S. V.

    2016-06-01

    The interaction of electron neutrino flux, originating in the rotational collapse mechanism on the first stage of Supernova burst, with the LSD detector components, such as 56Fe (a large amount of this metal is included in as shielding material) and liquid scintillator barNnH2n+2, is being investigated. Both charged and neutral channels of neutrino reaction with 12barN and 56Fe are considered. Experimental data, giving the possibility to extract information for nuclear matrix elements calculation are used. The number of signals, produced in LSD by the neutrino pulse of Supernova 1987A is determined. The obtained results are in good agreement with experimental data.

  15. Iron isotope compositions and origins of pyrites from the Turee Creek Group, Western Australia: the contribution of high-resolution femtosecond Laser Ablation -MC-ICP-MS

    NASA Astrophysics Data System (ADS)

    d'Abzac, F.; Beard, B. L.; Williford, K. H.; Valley, J. W.; Van Kranendonk, M. J.; Johnson, C.

    2013-12-01

    The Paleoproterozoic Great Oxidation Event (GOE) records a transition from an anoxic environment to a O2-bearing atmosphere, but its timing and duration remain unclear. High-spatial-resolution S isotope analyses by SIMS have shown that pyrite grains in the ~2.4Gy diamictites of the Meteorite Bore Member (MBM; Turee Creek Group, Western Australia), deposited during the GOE, contain evidence for a complex depositional and paragenetic history, including microbial sulfate reduction under low atmospheric O2 yet high seawater sulfate concentrations. The pyrites show various morphologies: euhedral, subhedral, anhedral, rounded, and zoned, where low- δ34S rounded cores may have high-δ34S euhedral/subhedral overgrowths [1]. New in-situ Fe isotope data by femtosecond laser ablation (fs-LA) analysis using Multi Collector ICP-MS on 118 pyrite grains within five rock samples previously analyzed for S isotopes documents δ56Fe values between -2.3‰ and +2.3‰. Transitional cherts at the base of the MBM record the highest δ56Fe values, >0.7‰. Within the upper mudstones/sandstones deposits, anhedral, rounded grains and zoned pyrite cores have a wide range of δ56Fe from -2.3‰ to +1.1‰ whereas euhedral grains and grains overgrowths have mainly positive δ56Fe values, up to +1.34‰, spread over narrower ranges in each sample (<1‰). Non-euhedral grains and rounded grain cores of likely detrital origin have highly scattered δ56Fe values, indicating a range of different sources. Although very low δ56Fe values suggest a source of biologically reduced Fe [2], they can be obtained by precipitation of FeS from low-δ56Fe seawater Fe2+ [3], or might reflect a kinetic signature during pyritization of FeS [4]. High-δ56Fe in pyrite overgrowths and authigenic grains likely reflects precipitation from a hydrothermal fluid (δ56Fe~0.0‰) at T>100°C [5, 6], in agreement with [1]. The δ34S gradient of highly negative to positive values from zoned pyrites cores to rims is well

  16. Hyperfine interactions in the ground states of titanium monoxide and mononitride

    SciTech Connect

    Fletcher, D.A.; Scurlock, C.T.; Jung, K.Y.; Steimle, T.C. )

    1993-09-15

    A comparative study of the hyperfine interactions in the [ital X] [sup 2][Sigma][sup +] state of TiN and the [ital X] [sup 3][Delta] state of TiO has been performed. The [sup 48]Ti[sup 14]N([ital I]=1) hyperfine structure was determined from the analysis of 19 components of the [ital N]=1--0 and [ital N]=2--1 pure rotational transitions recorded using the pump/probe microwave-optical double resonance technique. The [sup 47]Ti([ital I]=5/2) hyperfine structure of [ital X] [sup 2][Sigma][sup +] TiN was determined from an analysis of the high resolution optical spectrum of the (0,0) [ital A] [sup 2][Pi][sub 3/2]--[ital X] [sup 2][Sigma][sup +] band system. The resulting parameters are (in MHz) [ital B]([sup 48]Ti[sup 14]N)=18 589.3513(13), [ital D]([sup 48]Ti[sup 14]N)=0.026 31(18), [gamma]([sup 48]Ti[sup 14]N)=[minus]52.2070(13), [ital b][sub [ital F

  17. Menopause effect on blood Fe and Cu isotope compositions.

    PubMed

    Jaouen, Klervia; Balter, Vincent

    2014-02-01

    Iron (δ(56) Fe) and copper (δ(65) Cu) stable isotope compositions in blood of adult human include a sex effect, which still awaits a biological explanation. Here, we investigate the effect of menopause by measuring blood δ(56) Fe and δ(65) Cu values of aging men and women. The results show that, while the Fe and Cu isotope compositions of blood of men are steady throughout their lifetime, postmenopausal women exhibit blood δ(65) Cu values similar to men, and δ(56) Fe values intermediate between men and premenopausal women. The residence time of Cu and Fe in the body likely explains why the blood δ(65) Cu values, but not the δ(56) Fe values, of postmenopausal women resemble that of men. We suggest that the Cu and Fe isotopic fractionation between blood and liver resides in the redox reaction occurring during hepatic solicitation of Fe stores. This reaction affects the Cu speciation, which explains why blood Cu isotope composition is impacted by the cessation of menstruations. Considering that Fe and Cu sex differences are recorded in bones, we believe this work has important implications for their use as a proxy of sex or age at menopause in past populations.

  18. Bulk Properties of Iron Isotopes

    SciTech Connect

    Algin, E; Schiller, A; Voinov, A; Agvannluvsan, U; Belgya, T; Bernstein, L; Brune, C; Chankova, R; Garrett, P; Grimes, S; Guttormsen, M; Hjorth-Jensen, M; Hornish, M; Johnson, C; Massey, T; Mitchell, G; Rekstad, J; Siem, S; Younes, W

    2006-07-27

    Nuclear level densities and radiative strength functions (RSF) in {sup 56}Fe and {sup 57}Fe were measured using the {sup 57}Fe({sup 3}He,{alpha}{gamma}) and {sup 57}Fe({sup 3}He, {sup 3}He{prime}{gamma}) reactions, respectively, at Oslo Cyclotron Laboratory. A low-energy enhancement in the RSF below 4 MeV energy was observed. This finding cannot be explained by common theoretical models. In a second experiment, two-step cascade intensities with soft primary transitions from the {sup 56}Fe(n,2{gamma}) reaction were measured. The agreement between the two experiments confirms the low-energy enhancement in the RSF. In a third experiment, the neutron evaporation spectrum from the {sup 55}Mn(dn,N){sup 56}Fe reaction was measured at 7-MeV deuteron energy at John Edwards Accelerator Laboratory at Ohio University. Comparison of the level density of {sup 56}Fe obtained from the first and third experiments gives an overall good agreement. Furthermore, observed enhancement for soft {gamma} rays is supported by the last experiment.

  19. Effects of heavy particle irradiation on diet on object recognition memory in rats

    Technology Transfer Automated Retrieval System (TEKTRAN)

    On long duration missions to other planets astronauts will be exposed to types and doses of radiation that are not experienced in low earth orbit. Previous research using a ground-based model for exposure to cosmic rays has shown that exposure to heavy particles, such as 56Fe, disrupts spatial learn...

  20. A new analytical approach to understanding nanoscale lead-iron interactions in drinking water distribution systems.

    PubMed

    Trueman, Benjamin F; Gagnon, Graham A

    2016-07-01

    High levels of iron in distributed drinking water often accompany elevated lead release from lead service lines and other plumbing. Lead-iron interactions in drinking water distribution systems are hypothesized to be the result of adsorption and transport of lead by iron oxide particles. This mechanism was explored using point-of-use drinking water samples characterized by size exclusion chromatography with UV and multi-element (ICP-MS) detection. In separations on two different stationary phases, high apparent molecular weight (>669 kDa) elution profiles for (56)Fe and (208)Pb were strongly correlated (average R(2)=0.96, N=73 samples representing 23 single-unit residences). Moreover, (56)Fe and (208)Pb peak areas exhibited an apparent linear dependence (R(2)=0.82), consistent with mobilization of lead via adsorption to colloidal particles rich in iron. A UV254 absorbance peak, coincident with high molecular weight (56)Fe and (208)Pb, implied that natural organic matter was interacting with the hypothesized colloidal species. High molecular weight UV254 peak areas were correlated with both (56)Fe and (208)Pb peak areas (R(2)=0.87 and 0.58, respectively). On average, 45% (std. dev. 10%) of total lead occurred in the size range 0.05-0.45 μm.

  1. Iron Cycling in Marine Sediments - New Insights from Isotope Analysis on Sequentially Extracted Fe Fractions

    NASA Astrophysics Data System (ADS)

    Henkel, S.; Kasten, S.; Poulton, S.; Hartmann, J.; Staubwasser, M.

    2014-12-01

    Reactive Fe (oxyhydr)oxides preferentially undergo early diagenetic cycling and may cause a diffusive flux of dissolved Fe2+ from sediments towards the sediment-water interface. The partitioning of Fe in sediments has traditionally been studied by applying sequential extractions based on reductive dissolution of Fe minerals. We complemented the sequential leaching method by Poulton and Canfield [1] in order to be able to gain δ56Fe data for specific Fe fractions, as such data are potentially useful to study Fe cycling in marine environments. The specific mineral fractions are Fe-carbonates, ferrihydrite + lepidocrocite, goethite + hematite, and magnetite. Leaching was performed with acetic acid, hydroxylamine-HCl, Na-dithionite and oxalic acid. The processing of leachates for δ56Fe analysis involved boiling the samples in HCl/HNO3/H2O2, Fe precipitation and anion exchange column chromatography. The new method was applied to short sediment cores from the North Sea and a bay of King George Island (South Shetland Islands, Antarctica). Downcore mineral-specific variations in δ56Fe revealed differing contributions of Fe (oxyhydr)oxides to redox cycling. A slight decrease in easily reducible Fe oxides correlating with a slight increase in δ56Fe for this fraction with depth, which is in line with progessive dissimilatory iron reduction [2,3], is visible in the top 10 cm of the North Sea core, but not in the antarctic sediments. Less reactive (dithionite and oxalate leachable) fractions did not reveal isotopic trends. The acetic acid-soluble fraction displayed pronounced δ56Fe trends at both sites that cannot be explained by acid volatile sulfides that are also extracted by acetic acid [1]. We suggest that low δ56Fe values in this fraction relative to the pool of easily reducible Fe oxides result from adsorbed Fe(II) that was open to isotopic exchange with oxide surfaces, affirming the experimental results of Crosby el al. [2]. Hence, δ56Fe analyses on marine

  2. Iron and carbon isotope evidence for ecosystem and environmental diversity in the ˜ 2.7 to 2.5 Ga Hamersley Province, Western Australia

    NASA Astrophysics Data System (ADS)

    Czaja, Andrew D.; Johnson, Clark M.; Beard, Brian L.; Eigenbrode, Jennifer L.; Freeman, Katherine H.; Yamaguchi, Kosei E.

    2010-03-01

    The largest excursion in kerogen δ13C and bulk/mineral δ56Fe values yet measured in the ancient rock record occurs in rocks of ˜ 2.7 to 2.5 Ga age. New Fe isotope data integrated with previously collected C isotope data on the same samples document the metabolic diversity of microbial communities in the Neoarchean Hamersley Province of the Pilbara Craton in Western Australia. Samples of shales, carbonates, and mixed carbonate/shale lithologies were collected from three drill cores; two cores from the depocenter of the province and one from the margin. Shallow-water clastic/carbonate rocks deposited in the center of the province (Tumbiana Formation) record kerogen δ13C values that indicate C cycling by various anaerobic or aerobic methane pathways, but the restricted range in δ56Fe values indicates little or no Fe redox cycling. Deep-water sediments deposited contemporaneously in both parts of the Hamersley Province (Jeerinah Formation) record slightly positive δ56Fe values in the relatively shallower and suboxic margin, but strongly negative δ56Fe values in the deeper euxinic depocenter of the province, a pattern consistent with Fe cycling via a basin Fe shuttle, driven by bacterial dissimilatory iron reduction (DIR). Kerogen δ13C values from these units indicate coupling of microbial Fe cycling to aerobic methanotrophy or anaerobic oxidation of methane. Younger black shales, intercalated with iron formation (Marra Mamba Iron Formation) in the depocenter, record a shift to near-zero δ56Fe values reflecting an Fe budget dominated by hydrothermal and clastic sources. However, time-equivalent, Fe-rich carbonate/shale lithologies deposited on the margin of the province (Carawine Dolomite) have δ56Fe values that steadily decrease from near zero to strongly negative values. These relatively Fe-rich carbonates may reflect a carbonate trap of a DIR-driven Fe shuttle, similar to the sulfidic trap in the euxinic portion of the Jeerinah Formation. In contrast

  3. Modes of planetary-scale Fe isotope fractionation

    NASA Astrophysics Data System (ADS)

    Schoenberg, Ronny; Blanckenburg, Friedhelm von

    2006-12-01

    A comprehensive set of high-precision Fe isotope data for the principle meteorite types and silicate reservoirs of the Earth is used to investigate iron isotope fractionation at inter- and intra-planetary scales. 14 chondrite analyses yield a homogeneous Fe isotope composition with an average δ56Fe/ 54Fe value of - 0.015 ± 0.020‰ (2 SE) relative to the international iron standard IRMM-014. Eight non-cumulate and polymict eucrite meteorites that sample the silicate portion of the HED (howardite-eucrite-diogenite) parent body yield an average δ56Fe/ 54Fe value of - 0.001 ± 0.017‰, indistinguishable to the chondritic Fe isotope composition. Fe isotope ratios that are indistinguishable to the chondritic value have also been published for SNC meteorites. This inner-solar system homogeneity in Fe isotopes suggests that planetary accretion itself did not significantly fractionate iron. Nine mantle xenoliths yield a 2 σ envelope of - 0.13‰ to + 0.09‰ in δ56Fe/ 54Fe. Using this range as proxy for the bulk silicate Earth in a mass balance model places the Fe isotope composition of the outer liquid core that contains ca. 83% of Earth's total iron to within ± 0.020‰ of the chondritic δ56Fe/ 54Fe value. These calculations allow to interprete magmatic iron meteorites ( δ56Fe/ 54Fe = + 0.047 ± 0.016‰; N = 8) to be representative for the Earth's inner metallic core. Eight terrestrial basalt samples yield a homogeneous Fe isotope composition with an average δ56Fe/ 54Fe value of + 0.072 ± 0.016‰. The observation that terrestrial basalts appear to be slightly heavier than mantle xenoliths and that thus partial mantle melting preferentially transfers heavy iron into the melt [S. Weyer, A.D. Anbar, G.P. Brey, C. Munker, K. Mezger and A.B. Woodland, Iron isotope fractionation during planetary differentiation, Earth and Planetary Science Letters 240(2), 251-264, 2005.] is intriguing, but also raises some important questions: first it is questionable whether the

  4. Iron assimilation by the clam Laternula elliptica: Do stable isotopes (δ⁵⁶Fe) help to decipher the sources?

    PubMed

    Poigner, Harald; Wilhelms-Dick, Dorothee; Abele, Doris; Staubwasser, Michael; Henkel, Susann

    2015-09-01

    Iron stable isotope signatures (δ(56)Fe) in hemolymph (bivalve blood) of the Antarctic bivalve Laternula elliptica were analyzed by Multiple Collector-Inductively Coupled Plasma-Mass Spectrometry (MC-ICP-MS) to test whether the isotopic fingerprint can be tracked back to the predominant sources of the assimilated Fe. An earlier investigation of Fe concentrations in L. elliptica hemolymph suggested that an assimilation of reactive and bioavailable Fe (oxyhydr)oxide particles (i.e. ferrihydrite), precipitated from pore water Fe around the benthic boundary, is responsible for the high Fe concentration in L. elliptica (Poigner et al., 2013 b). At two stations in Potter Cove (King George Island, Antarctica) bivalve hemolymph showed mean δ(56)Fe values of -1.19 ± 0.34‰ and -1.04 ± 0.39 ‰, respectively, which is between 0.5‰ and 0.85‰ lighter than the pool of easily reducible Fe (oxyhydr)oxides of the surface sediments (-0.3‰ to -0.6‰). This is in agreement with the enrichment of lighter Fe isotopes at higher trophic levels, resulting from the preferential assimilation of light isotopes from nutrition. Nevertheless, δ(56)Fe hemolymph values from both stations showed a high variability, ranging between -0.21‰ (value close to unaltered/primary Fe(oxyhydr)oxide minerals) and -1.91‰ (typical for pore water Fe or diagenetic Fe precipitates), which we interpret as a "mixed" δ(56)Fe signature caused by Fe assimilation from different sources with varying Fe contents and δ(56)Fe values. Furthermore, mass dependent Fe fractionation related to physiological processes within the bivalve cannot be ruled out. This is the first study addressing the potential of Fe isotopes for tracing back food sources of bivalves.

  5. Induction and repair of HZE induced cytogenetic damage

    NASA Technical Reports Server (NTRS)

    Brooks, A. L.; Bao, S.; Rithidech, K.; Chrisler, W. B.; Couch, L. A.; Braby, L. A.

    2001-01-01

    Wistar rats were exposed to high-mass, high energy (HZE) 56Fe particles (1000 GeV/AMU) using the Alternating Gradient Synchrotron (AGS). The animals were sacrificed at 1-5 hours or after a 30-day recovery period. The frequency of micronuclei in the tracheal and the deep lung epithelial cells were evaluated. The relative effectiveness of 56Fe, for the induction of initial chromosome damage in the form of micronuclei, was compared to damage produced in the same biological system exposed to other types of high and low-LET radiation. It was demonstrated that for animals sacrificed at short times after exposure, the tracheal and lung epithelial cells, the 56Fe particles were 3.3 and 1.3 times as effective as 60Co in production of micronuclei, respectively. The effectiveness was also compared to that for exposure to inhaled radon. With this comparison, the 56Fe exposure of the tracheal epithelial cells and the lung epithelial cells were only 0.18 and 0.20 times as effective as radon in the production of the initial cytogenetic damage. It was suggested that the low relative effectiveness was related to potential for 'wasted energy' from the core of the 56Fe particles. When the animals were sacrificed after 30 days, the slopes of the dose-response relationships, which reflect the remaining level of damage, decreased by a factor of 10 for both the tracheal and lung epithelial cells. In both cases, the slope of the dose-response lines were no longer significantly different from zero, and the r2 values were very high. Lung epithelial cells, isolated from the animals sacrificed hours after exposure, were maintained in culture, and the micronuclei frequency evaluated after 4 and 6 subcultures. These cells were harvested at 24 and 36 days after the exposure. There was no dose-response detected in these cultures and no signs of genomic instability at either sample time.

  6. Microbial production of isotopically light iron(II) in a modern chemically precipitated sediment and implications for isotopic variations in ancient rocks

    USGS Publications Warehouse

    Tangalos, G.E.; Beard, B.L.; Johnson, C.M.; Alpers, C.N.; Shelobolina, E.S.; Xu, H.; Konishi, H.; Roden, E.E.

    2012-01-01

    The inventories and Fe isotope composition of aqueous Fe(II) and solid-phase Fe compounds were quantified in neutral-pH, chemically precipitated sediments downstream of the Iron Mountain acid mine drainage site in northern California, USA. The sediments contain high concentrations of amorphous Fe(III) oxyhydroxides [Fe(III)am] that allow dissimilatory iron reduction (DIR) to predominate over Fe–S interactions in Fe redox transformation, as indicated by the very low abundance of Cr(II)-extractable reduced inorganic sulfur compared with dilute HCl-extractable Fe. δ56Fe values for bulk HCl- and HF-extractable Fe were ≈ 0. These near-zero bulk δ56Fe values, together with the very low abundance of dissolved Fe in the overlying water column, suggest that the pyrite Fe source had near-zero δ56Fe values, and that complete oxidation of Fe(II) took place prior to deposition of the Fe(III) oxide-rich sediment. Sediment core analyses and incubation experiments demonstrated the production of millimolar quantities of isotopically light (δ56Fe ≈ -1.5 to -0.5‰) aqueous Fe(II) coupled to partial reduction of Fe(III)am by DIR. Trends in the Fe isotope composition of solid-associated Fe(II) and residual Fe(III)am are consistent with experiments with synthetic Fe(III) oxides, and collectively suggest an equilibrium Fe isotope fractionation between aqueous Fe(II) and Fe(III)am of approximately -2‰. These Fe(III) oxide-rich sediments provide a model for early diagenetic processes that are likely to have taken place in Archean and Paleoproterozoic marine sediments that served as precursors for banded iron formations. Our results suggest pathways whereby DIR could have led to the formation of large quantities of low-δ56Fe minerals during BIF genesis.

  7. Iron and magnesium isotope fractionation in oceanic lithosphere and sub-arc mantle: Perspectives from ophiolites

    NASA Astrophysics Data System (ADS)

    Su, Ben-Xun; Teng, Fang-Zhen; Hu, Yan; Shi, Ren-Deng; Zhou, Mei-Fu; Zhu, Bin; Liu, Fan; Gong, Xiao-Han; Huang, Qi-Shuai; Xiao, Yan; Chen, Chen; He, Yong-Sheng

    2015-11-01

    We present high-precision Fe and Mg isotopic data for the Purang ophiolite, southwestern Tibet, representing the first combined Fe and Mg isotopic study of the oceanic lithosphere hitherto. The δ56Fe and δ26Mg values of the ophiolitic peridotite, dunite and gabbro vary from -0.209 to 0.187‰ and from -0.28 to - 0.14 ‰, respectively. The average δ56Fe of the peridotites is - 0.030 ± 0.143 ‰ (2SD, n = 17), a value indistinguishable from abyssal peridotites and chondrites, and lower than oceanic basalts. The average δ26Mg value of the peridotites is - 0.20 ± 0.10 ‰, a value slightly higher than both chondrites and oceanic basalts. Correlations between δ56Fe and indices of partial melting indicate fractionation of 0.323‰ in δ56Fe between the oceanic lithospheric mantle and the overlying mafic crust during an early episode of partial melting, presumably beneath a spreading centre. Subsequent metasomatism in a supra-subduction zone caused elevated oxygen fugacity and heavy Fe isotopic compositions in the oceanic lithospheric mantle. The dunite with high Ba/La, a proxy for oxygen fugacity, and high δ56Fe values was likely formed during this process of sub-arc mantle-melt interaction. The negatively coupled Fe-Mg isotopic variations of the Purang ophiolite indicate that Mg isotope fractionation may also occur during high-temperature mantle processes. The observed isotopic variations among different lithologies in the ophiolite may satisfactorily account for the isotopic differences between arc lavas and mantle peridotites with respect to oceanic basalts, thus providing implications for crust-mantle differentiation.

  8. Configuration interaction in symmetry-conserving covariant density functional theory

    NASA Astrophysics Data System (ADS)

    Zhao, P. W.; Ring, P.; Meng, J.

    2016-10-01

    A new method to calculate spectroscopic properties of deformed nuclei is proposed: configuration interaction on top of projected density functional theory (CI-PDFT). The general concept of this approach is discussed in the framework of covariant density functional theory and its validity is illustrated in an application to the yrast band of the nucleus 54Cr. It is found that the experimentally observed excitation energies for the yrast band in 54Cr can be well reproduced. In contrast to conventional shell-model calculations, there is no core and only a relatively small number of configurations is sufficient for a satisfying description. No new parameters are necessary, because the effective interaction is derived from an universal density functional given in the literature.

  9. Manganese chromium isotope systematics of carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Shukolyukov, A.; Lugmair, G. W.

    2006-10-01

    In this article we present the results of Cr isotope investigations of different types of carbonaceous chondrites and of the pallasite Eagle Station. The 53Cr/ 52Cr ratios in the bulk samples of carbonaceous chondrites are correlated with 55Mn/ 52Cr ratios. The slope of the correlation line yields a 53Mn/ 55Mn ratio of (8.5 ± 1.5) × 10 - 6 at the time of Mn/Cr fractionation. Mapping this ratio onto an absolute time scale yields a time for this event of 4568.1 + 0.8/- 1.1 Ma ago. This time is very similar to the formation age of Efremovka CAIs of 4567.2 ± 0.6 Ma [Y. Amelin, A. N. Krot, I. D. Hutcheon, A. A. Ulyanov, Lead isotopic ages of chondrules and calcium-aluminum-rich inclusions, Science 297 (2002) 1678-1683], to a time of the chondrule formation of 4568 ± 1 Ma ago [L.E. Nyquist, D. Lindstrom, D. Mittlefehldt, C.-Y. Shih, H. Wiesmann, S. Wentworth, R. Martinez, Manganese-chromium formation intervals for chondrules from the Bishunpur and Chainpur meteorites, Meteorit. Planet. Sci. 36 (2001) 911-938], which, most likely, constrains early global high-temperature Mn/Cr fractionation in a nebular setting. The bulk samples of carbonaceous chondrites exhibit clear 54Cr excesses ( 54Cr *) that are correlated with the 53Cr excesses ( 53Cr *) and also with Mn/Cr ratios. One possible explanation of this correlation is that 54Cr * is also radiogenic, like 53Cr *, and was formed by the decay of the short-lived parent radionuclide 54Mn. The very short half-life of 54Mn of 312 days would require that both short-lived radionuclides 53Mn and 54Mn were generated locally in spallation reactions during the early period of an active sun. The alternative and possibly more plausible explanation is the heterogeneous addition of presolar material. The presolar component, enriched in 54Cr, is mostly contained in the matrix of carbonaceous chondrites. The relative amount of matrix decreases in the sequence CI > CM > CO,CV. A large proportion of Mn is associated with the matrix while

  10. The Diversity of Anomalous HEDs: Isotopic Constraints on the Connection of EET 92023, GRA 98098, and Dhofar 700 With Vesta

    NASA Technical Reports Server (NTRS)

    Sanborn, M. E.; Yin, Q.-Z.; Mittlefehldt, D. W.

    2016-01-01

    The possibility for multiple parent bodies, instead of a common parent body of Vesta, for eucrites has been suggested based on the variable oxygen isotopic composition observed in some eucrites.. Recently, we added an extra dimension to the discussion based on the (epsilon)54Cr composition of the same eucrites with known (delta)17O to compare with the normal eucrites. The combined (delta)17O and (epsilon)54Cr isotope systematics for Pasamonte, PCA 91007, A-881394, and Ibitira indicate their likely origin from multiple different parent bodies than the normal eucrites. Often the qualifier anomalous is used to identify HEDs with (delta)17O values that deviate significantly (>3(sigma)) from the mean HED (delta)17O. However, variations in eucrites and diogenites also include unique geochemical characteristics such as bulk composition, trace element abundances, or volatile concentrations, in addition to (delta)17O. Here, we investigate three such geochemically anomalous HEDs: Elephant Moraine (EET) 92023, Graves Nunataks (GRA) 98098, and Dhofar 700. In addition, to verify the homogeneity of (epsilon)54Cr observed for normal HEDs thus far, a set of seven eucrites and diogenites considered normal samples were also investigated.

  11. Fe-O stable isotope pairs elucidate a high-temperature origin of Chilean iron oxide-apatite deposits

    NASA Astrophysics Data System (ADS)

    Bilenker, Laura D.; Simon, Adam C.; Reich, Martin; Lundstrom, Craig C.; Gajos, Norbert; Bindeman, Ilya; Barra, Fernando; Munizaga, Rodrigo

    2016-03-01

    Iron oxide-apatite (IOA) ore deposits occur globally and can host millions to billions of tons of Fe in addition to economic reserves of other metals such as rare earth elements, which are critical for the expected growth of technology and renewable energy resources. In this study, we pair the stable Fe and O isotope compositions of magnetite samples from several IOA deposits to constrain the source reservoir of these elements in IOAs. Since magnetite constitutes up to 90 modal% of many IOAs, identifying the source of Fe and O within the magnetite may elucidate high-temperature and/or lower-temperature processes responsible for their formation. Here, we focus on the world-class Los Colorados IOA in the Chilean iron belt (CIB), and present data for magnetite from other Fe oxide deposits in the CIB (El Laco, Mariela). We also report Fe and O isotopic values for other IOA deposits, including Mineville, New York (USA) and the type locale, Kiruna (Sweden). The ranges of Fe isotopic composition (δ56Fe, 56Fe/54Fe relative to IRMM-14) of magnetite from the Chilean deposits are: Los Colorados, δ56Fe (±2σ) = 0.08 ± 0.03‰ to 0.24 ± 0.08‰; El Laco, δ56Fe = 0.20 ± 0.03‰ to 0.53 ± 0.03‰; Mariela, δ56Fe = 0.13 ± 0.03‰. The O isotopic composition (δ18O, 18O/16O relative to VSMOW) of the same Chilean magnetite samples are: Los Colorados, δ18O (±2σ) = 1.92 ± 0.08‰ to 3.17 ± 0.03‰; El Laco, δ18O = 4.00 ± 0.10‰ to 4.34 ± 0.10‰; Mariela, δ18O = (1.48 ± 0.04‰). The δ18O and δ56Fe values for Kiruna magnetite yield an average of 1.76 ± 0.25‰ and 0.16 ± 0.07‰, respectively. The Fe and O isotope data from the Chilean IOAs fit unequivocally within the range of magnetite formed by high-temperature magmatic or magmatic-hydrothermal processes (i.e., δ56Fe 0.06-0.49‰ and δ18O = 1.0-4.5‰), consistent with a high-temperature origin for Chilean IOA deposits. Additionally, minimum formation temperatures calculated by using the measured Δ18O

  12. Chemical leaching methods and measurements of marine labile particulate Fe

    NASA Astrophysics Data System (ADS)

    Revels, B. N.; John, S.

    2012-12-01

    Iron (Fe) is an essential nutrient for life. Yet its low solubility and concentration in the ocean limits marine phytoplankton productivity in many regions of the world. Dissolved phase Fe (<0.4μm) has traditionally been considered the most biologically accessible form, however, the particulate phase (>0.4μm) may contain an important, labile reservoir of Fe that may also be available to phytoplankton. However, concentration data alone cannot elucidate the sources of particulate Fe to the ocean and to what extent particulate iron may support phytoplankton growth. Isotopic analysis of natural particles may help to elucidate the biogeochemical cycling of Fe, though it is important to find a leaching method which accesses bioavailable Fe. Thirty-three different chemical leaches were performed on a marine sediment reference material, MESS-3. The combinations included four different acids (25% acetic acid, 0.01M HCl, 0.5M HCl, 0.1M H2SO4 at pH2), various redox conditions (0.02M hydroxylamine hydrochloride or 0.02M H2O2), three temperatures (25°C, 60°C, 90°C), and three time points (10 minutes, 2 hours, 24 hours). Leached Fe concentrations varied from 1mg/g to 35mg/g, with longer treatment times, stronger acids, and hotter temperatures generally associated with an increase in leached Fe. δ56Fe in these leaches varied from -1.0‰ to +0.2‰. Interestingly, regardless of leaching method used, there was a very similar relationship between the amount of Fe leached from the particles and the δ56Fe of this iron. Isotopically lighter δ56Fe values were associated with smaller amounts of leached Fe whereas isotopically heavier δ56Fe values were associated with larger amounts of leached Fe. Two alternate hypotheses could explain these data. Either, the particles may contain pools of isotopically light Fe that are easily accessed early in dissolution, or isotopically light Fe may be preferentially leached from the particle due to a kinetic isotope effect during dissolution

  13. A new LA-ICP-MS method for Ti-in-Quartz: Implications and application to HP rutile-quartz veins from the Czech Erzgebirge

    NASA Astrophysics Data System (ADS)

    Cruz-Uribe, A. M.; Mertz-Kraus, R.; Zack, T.; Feineman, M. D.; Woods, G.

    2014-12-01

    Experimental determination of the pressure and temperature controls on Ti solubility in quartz provide a calibration of the Ti-in-quartz (TitaniQ) geothermometer applicable to geologic conditions up to ~20 kbar (Thomas et al. (2010) Contrib Mineral Petrol 160, 743-759). One of the greatest limitations to analyzing Ti in metamorphic quartz by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is the lack of a suitable matrix-matched reference material. Typically LA-ICP-MS analyses of Ti in minerals use 49Ti as a normalizing mass because of an isobaric interference from 48Ca, which is present in most well characterized reference glasses, on 48Ti. The benefit of using a matrix-matched reference material to analyze Ti in quartz is the opportunity to use 48Ti (73.8 % abundance) as a normalizing mass, which results in an order of magnitude increase in signal strength compared to the less abundant isotope 49Ti (5.5 % abundance), thereby increasing the analytical precision. Here we characterize Ti-bearing SiO2 glasses from Heraeus Quarzglas and natural quartz grains from the Bishop Tuff by cathodoluminescence (CL) imaging, electron probe microanalysis (EPMA), and LA-ICP-MS, in order to determine their viability as reference materials for Ti in quartz. Titanium contents in low-CL rims in the Bishop Tuff quartz grains were determined to be homogenous by EPMA (41 ± 2 µg/g Ti, 2σ), and are a potential natural reference material. We present a new method for determining 48Ti concentrations in quartz by LA-ICP-MS at the 1 µg/g level, relevant to quartz in HP-LT terranes. We suggest that natural quartz such as the homogeneous low-CL rims of the Bishop Tuff quartz are more suitable than NIST reference glasses as an in-house reference material for low Ti concentrations because matrix effects are limited and Ca isobaric interferences are avoided, thus allowing for the use of 48Ti as a normalizing mass. Titanium concentration from 33 analyses of low

  14. Biological, chemical, electrochemical, and photochemical fractionation of Fe isotopes

    NASA Astrophysics Data System (ADS)

    John, S.; King, A.; Hutchins, D.; Adkins, J. F.; Fu, F.; Wasson, A.; Hodierne, C.

    2012-12-01

    Iron is an important nutrient for life in the ocean, where low Fe concentrations often limit the growth of marine phytoplankton. Fe stable isotope ratios (δ56Fe) are a potentially valuable new tool for studying the marine biological cycling of Fe. In order to effectively use Fe isotopes as a biological tracer, however, it is important to parameterize the isotope effect for biological uptake. We have therefore measured the biological fractionation of Fe isotopes by the marine diatoms Thalassiosira pseudonana, T. oceanica, and Phaeodactylum tricornutum in culture. During biological Fe acquisition, Fe(III) is often first reduced from Fe(III) to Fe(II), either in seawater or at the cell surface. Therefore, we have also measured the isotope effect for Fe(III) reduction by chemical, electrochemical, and photochemical processes. Diatoms were cultured in EDTA or NTA buffered media under varying Fe concentrations from Fe-sufficiency to Fe-limitation. Biological fractionation of Fe isotopes was determined by comparing δ56Fe of phytoplankton to the media. The use of a cell wash allows us to distinguish between isotopic fractionation during extracellular adsorption and intracellular uptake. The biological fractionation of Fe isotopes is highly dependent on culture conditions with Δδ56Fe ranging from +0.6 ‰ to -0.5 ‰ depending on ligand composition, species, and Fe-limitation status. Isotope effects for chemical, electrochemical, and photochemical reduction of Fe(III) to Fe(II) span an even larger range. For example, chemical reduction of Fe(III)-EDTA with hydroxylamine hydrochloride has an isotope effect of Δδ56Fe = -2.8 ‰. By contrast, photochemical reduction of Fe(III)-EDTA has an isotope effect of Δδ56Fe = +0.9 ‰. Isotope effects for electrochemical reduction of Fe(III) using a rotating disc electrode allow for greater control of experimental conditions, such as differentiating between the effects of electric potential (voltage) and mass transport (diffusion

  15. Pyritic event beds and sulfidized Fe (oxyhydr)oxide aggregates in metalliferous black mudstones of the Paleoproterozoic Talvivaara formation, Finland

    NASA Astrophysics Data System (ADS)

    Virtasalo, Joonas J.; Laitala, Jaakko J.; Lahtinen, Raimo; Whitehouse, Martin J.

    2015-12-01

    The Paleoproterozoic, 2.0-1.9 Ga Talvivaara formation of Finland was deposited during the Shunga Event, a worldwide episode of enhanced accumulation of organic-rich sediments in the aftermath of the Lomagundi-Jatuli carbon isotope excursion. Sulfidic carbonaceous mudstones in the Talvivaara formation contain one of the largest known shale-hosted nickel deposits. In order to gain new insight into this Shungian sedimentary environment, sedimentological, petrographical and in situ S and Fe isotopic microanalyses were carried out on samples representing depositional and early-diagenetic conditions. The event-bedded lithology with tidal signatures in the organic-rich mudstones strongly indicates deposition from predominantly river-delivered mud on a highly-productive coastal area, below storm-wave base. The riverine supply of phosphorus, sulfate and iron supported high primary productivity and resulted in strong lateral and vertical chemical gradients in the nearshore waters with a shallow oxic surface layer underlain by euxinic water. The stratigraphic upper part of the Talvivaara formation contains banded intervals of thin alternating pyrite beds and carbonaceous mudstone beds. The pyrite beds were deposited by seaward excursions of the concentrated, acidic Fe-rich river plume subsequent to droughts or dry seasons, which led to intense pyrite precipitation upon mixing with euxinic waters. δ34S and δ56Fe values of the bedded pyrite (median δ34S = - 10.3 ‰ and δ56Fe = - 0.79 ‰) are consistent with the reaction of dissolved Fe(II) with H2S from bacterial sulfate reduction. Organic-rich clayey Fe-monosulfide-bearing granules were transported from the muddy estuary, and enclosed in Fe (oxyhydr)oxide aggregates that were forming by wave and current reworking in nearshore accumulations of river-delivered iron. The isotopic composition of these presently pyrrhotitic inclusions (median δ34S = - 3.3 ‰ and δ56Fe = - 1.6 ‰) indicates microbial iron reduction. The Fe

  16. Mn-Cr systematics in primitive meteorites: Insights from mineral separation and partial dissolution

    NASA Astrophysics Data System (ADS)

    Göpel, Christa; Birck, Jean-Louis; Galy, Albert; Barrat, Jean-Alix; Zanda, Brigitte

    2015-05-01

    Cr isotopic compositions have been measured on carbonaceous chondrites (CC): Tafassasset, Paris, Niger I, NWA 5958, NWA 8157 and Jbilet Winselwan. In bulk samples, the 54Cr/52Cr ratios (expressed as ε54Cr) range from 0.93 to 1.58 ε units. These values are in agreement with values characteristic for distinct petrologic types. Despite this 54Cr heterogeneity, the variability in the 53Cr/52Cr ratios (expressed as ε53Cr) of 0.2 ε units and the Mn/Cr ratios is consistent with the previous finding of an isochron in the Mn-Cr evolution diagram. The Mn/Cr ratio in CC corresponds to variable abundances of high-T condensate formed and separated at the beginning of the solar system, thus the canonical 53Mn/55Mn ratio can be defined. Based on a consistent chronology for U-Pb and Mn-Cr between the earliest objects formed in the solar nebula and the D'Orbigny angrite we define a canonical 53Mn/55Mn ratio and ε53Cri of 6.8 × 10-6 and -0.177, respectively. The internal Mn/Cr systematics in Tafassasset and Paris were studied by two approaches: leaching technique and mineral separation. Despite variable ε54Cr values (up to >30 ε) linear co-variations were found between ε53Cr and Mn/Cr ratio. The mineral separates as well as the leachates of Tafassasset fall on a common isochron indicating that (1) cooling of the Tafassasset's parent body occurred at 4563.5 ± 0.25 Ma, and that (2) 54Cr is decoupled from the other isotopes even though temperatures >900 °C have been reached during metamorphism. In the case of Paris, the leachates form an alignment with a 53Mn/55Mn ratio higher than the canonical value. This alignment is not an isochron but rather a mixing line. Based on leachates from various CM and CI, we propose the occurrence of three distinct Cr reservoirs in meteoritic material: PURE54, HIGH53 and LOW53 characterized by a ε53Cr and ε54Cr of 0 and 25,000, -2.17 and 8, and 0.5 and -151, respectively. PURE54 has already been described and is carried by highly refractory

  17. Strong evidence for quasifission in asymmetric reactions forming {sup 202}Po

    SciTech Connect

    Rafiei, R.; Thomas, R. G.; Hinde, D. J.; Dasgupta, M.; Morton, C. R.; Gasques, L. R.; Brown, M. L.; Rodriguez, M. D.

    2008-02-15

    Fission fragment mass-angle correlations and mass ratio distributions have been measured for the reactions {sup 16}O+{sup 186}Os, {sup 24}Mg+{sup 178}Hf, {sup 34}S+{sup 168}Er, and {sup 48}Ti+{sup 154}Sm, forming the {sup 202}Po composite nucleus, at near barrier energies. Systematic analysis based on the expected dependence of the variance of the mass distribution on the angular momentum and temperature of the compound nucleus indicate that the two lighter systems evolve through true compound nucleus fission. Evidence of quasifission was observed for the two most mass-symmetric reactions, through strong mass-angle correlations for the {sup 48}Ti+{sup 154}Sm reaction and a broadened mass ratio distribution for the {sup 34}S+{sup 168}Er reaction. Furthermore, the increase in mass width at near barrier energies shows the influence of the alignment of statically deformed target nuclei.

  18. Absence of closed shell effect in the fusion reaction 40Ca + 48Ca at 330 MeV

    NASA Astrophysics Data System (ADS)

    Barreto, J.; Tassan-Got, L.; Stephan, C.; Garron, J. P.; Langevin, M.

    1982-03-01

    A direct comparison of the complete fusion cross section of the reaction 40Ar + 48Ti with the double magic 40Ca + 48Ca fusion cross section has been done with 330 MeV projectile energy. The compound nucleus 88Zr was formed with nearly the same excitation energy and identical angular momentum population in both reactions. A ΔE-E telescope placed in the focal plane of a spectrometer, associated with a time of flight allowed a complete identification of the reaction products. Evaporation residues were also detected inside the scattering chamber with a ΔE-E silicon telescope. From both measurements, there was no evidence for a closed shell effect in the complete fusion reaction. NUCLEAR REACTIONS 40Ca + 48Ca, 40Ar + 48Ti, Elab=330 MeV, measured fusion cross sections.

  19. Parity dependence of level densities in sup 49 V

    SciTech Connect

    York, B.W.

    1991-01-01

    In this research, we have studied {sup 48}Ti(p, p{sub 1}) and {sup 48}(p, p{sub 1}{gamma}) in an effort to determine the dependence of level densities on parity in the compound nucleus {sup 49}V. This nuclide was chosen because of the high level density of the {sup 49}V system (leading to good statistical accuracy) and because the target is zero spin (making the assignment of J easier). 5 refs., 3 figs.

  20. Spatially Controlled Fe Isotope Variations at Torres del Paine

    NASA Astrophysics Data System (ADS)

    Gajos, N.; Lundstrom, C.

    2013-12-01

    Recent advances in mass-spectrometry have identified systematic trends of non-traditional stable isotope variation in igneous rocks with differentiation index. We present new Fe isotope data for the Torres del Paine igneous complex in southern Chile. The multi-composition pluton consists of a 1 km vertical exposure of homogenous granite overlying a contemporaneous and possibly cogenetic 0.5 km mafic gabbro suite. Whereas previous isotopic investigations do little to address variations across important magmatic contacts, this study focuses on a first-of-its-kind spatially dependent non-traditional stable isotope investigation of an igneous pluton. Samples were collected at Torres del Paine in spatially significant transects, focusing on major contacts between country rock, granite and mafic units. Results collected by bracketed double spike MC-ICP-MS (2s precision of ×0.03) show an increase in δ56Fe towards the high silica margins of the pluton with values as high as δ56Fe 0.36. Additionally, the data show a decrease in δ56Fe toward the mafic center of the pluton with δ56Fe values ranging from δ56Fe -0.05 to 0.18. Samples collected on the contact between the granite and mafic complex show intermediate values of δ56Fe= 0.18(×) 0.03. Country rock samples in contact with granite show an isotopically light signature of δ56Fe=0.04 (×) 0.03. Analysis of 50 samples in total show a trend of increasing δ56Fe with SiO2 content. The process responsible for Fe isotope variations remains debated but is suggested to reflect four mechanisms: (1) crustal assimilation, (2) fractional crystallization, (3) late stage fluid exsolution [1] and (4) thermal migration [3]. Preliminary results show that mechanisms #1 and #2 would produce isotopic signatures opposite of those seen at Torres del Paine and other plutonic rocks. Isotopically light Torres country rock samples reveal that assimilation of rocks would not produce the isotopically heavy granites seen at Torres. Based on

  1. Application of nuclear resonance scattering for in vivo measurements

    SciTech Connect

    Wielopolski, L.; Vartsky, D.; Cohn, S.H.

    1983-01-01

    Nuclear resonance scattering is applied in our laboratory to measure hepatic and cardiac iron overload. For iron analysis, a gaseous source of 4 mg MnCl/sub 2/ is introduced into an evacuated quartz vial. Following irradiation in a nuclear reactor, /sup 56/Mn decays by beta emission to the 847-keV level of /sup 56/Fe, which subsequently decays to the ground state of /sup 56/Fe with a 7 ps half-life. The principal aim of this work is to evaluate the efficacy of the iron chelation therapy. Serial measurements over a time period of 6 to 12 months of a given patient will enable us to see how the iron is removed from the critical organs.

  2. Ground-based simulations of cosmic ray heavy ion interactions in spacecraft and planetary habitat shielding materials

    NASA Technical Reports Server (NTRS)

    Miller, J.; Zeitlin, C.; Heilbronn, L.; Borak, T.; Carter, T.; Frankel, K. A.; Fukumura, A.; Murakami, T.; Rademacher, S. E.; Schimmerling, W.; Stronach, C.; Chatterjee, A. (Principal Investigator)

    1998-01-01

    This paper surveys some recent accelerator-based measurements of the nuclear fragmentation of high energy nuclei in shielding and tissue-equivalent materials. These data are needed to make accurate predictions of the radiation field produced at depth in spacecraft and planetary habitat shielding materials and in the human body by heavy charged particles in the galactic cosmic radiation. Projectile-target combinations include 1 GeV/nucleon 56Fe incident on aluminum and graphite and 600 MeV/nucleon 56Fe and 290 MeV/nucleon 12C on polyethylene. We present examples of the dependence of fragmentation on material type and thickness, of a comparison between data and a fragmentation model, and of multiple fragments produced along the beam axis.

  3. Elastic scattering of 96 MeV neutrons from iron, yttrium, and lead

    SciTech Connect

    Oehrn, A.; Blomgren, J.; Andersson, P.

    2008-02-15

    Data on elastic scattering of 96 MeV neutrons from {sup 56}Fe, {sup 89}Y, and {sup 208}Pb in the angular interval 10-70 deg. are reported. The previously published data on {sup 208}Pb have been extended, as a new method has been developed to obtain more information from data, namely to increase the number of angular bins at the most forward angles. A study of the deviation of the zero-degree cross section from Wick's limit has been performed. It was shown that the data on {sup 208}Pb are in agreement with Wick's limit while those on the lighter nuclei overshoot the limit significantly. The results are compared with modern optical model predictions, based on phenomenology and microscopic nuclear theory. The data on {sup 56}Fe, {sup 89}Y, and {sup 208}Pb are in general in good agreement with the model predictions.

  4. Effects of exposure to different types of radiation on behaviors mediated by peripheral or central systems

    NASA Technical Reports Server (NTRS)

    Rabin, B. M.; Joseph, J. A.; Erat, S.

    1998-01-01

    The effects of exposure to ionizing radiation on behavior may result from effects on peripheral or on central systems. For behavioral endpoints that are mediated by peripheral systems (e.g., radiation-induced conditioned taste aversion or vomiting), the behavioral effects of exposure to heavy particles (56Fe, 600 MeV/n) are qualitatively similar to the effects of exposure to gamma radiation (60Co) and to fission spectrum neutrons. For these endpoints, the only differences between the different types of radiation are in terms of relative behavioral effectiveness. For behavioral endpoints that are mediated by central systems (e.g., amphetamine-induced taste aversion learning), the effects of exposure to 56Fe particles are not seen following exposure to lower LET gamma rays or fission spectrum neutrons. These results indicate that the effects of exposure to heavy particles on behavioral endpoints cannot necessarily be extrapolated from studies using gamma rays, but require the use of heavy particles.

  5. Determination of the Fe(II)aq-magnetite equilibrium iron isotope fractionation factor using the three-isotope method and a multi-direction approach to equilibrium

    NASA Astrophysics Data System (ADS)

    Frierdich, Andrew J.; Beard, Brian L.; Scherer, Michelle M.; Johnson, Clark M.

    2014-04-01

    Magnetite is ubiquitous in the Earth's crust and its presence in modern marine sediments has been taken as an indicator of biogeochemical Fe cycling. Magnetite is also the most abundant Fe oxide in banded iron formations (BIFs) that have not been subjected to ore-forming alteration. Magnetite is therefore an important target of stable Fe isotope studies, and yet interpretations are currently difficult because of large uncertainties in the equilibrium stable Fe isotope fractionation factors for magnetite relative to fluids and other minerals. In this study, we utilized the three-isotope method (57Fe-56Fe-54Fe) to explore isotopic exchange via an enriched-57Fe tracer, and natural mass-dependent fractionation using 56Fe/54Fe variations, during reaction of aqueous Fe(II) (Fe(II)aq) with magnetite. Importantly, we employed a multi-direction approach to equilibrium by reacting four 57Fe-enriched Fe(II) solutions that had distinct 56Fe/54Fe ratios, which identifies changes in the instantaneous Fe isotope fractionation factor and hence identifies kinetic isotope effects. We find that isotopic exchange can be described by two 56Fe/54Fe fractionations, where an initial rapid exchange (∼66% isotopic mixing within 1 day) involved a relatively small Fe(II)aq-magnetite 56Fe/54Fe fractionation, followed by slower exchange (∼25% isotopic mixing over 50 days) that was associated with a larger Fe(II)aq-magnetite 56Fe/54Fe fractionation; this later fractionation is interpreted to approach isotopic equilibrium between Fe(II)aq and the total magnetite. All four Fe(II) solutions extrapolate to the same final equilibrium 56Fe/54Fe fractionation for Fe(II)aq-magnetite of -1.56±0.20‰ (2σ) at 22 °C. Additional experiments that synthesized magnetite via conversion of ferrihydrite by reaction with aqueous Fe(II) yield final 56Fe/54Fe fractionations that are identical to those of the exchange experiments. Our experimental results agree well with calculated fractionation factors using

  6. Effects of exposure to different types of radiation on behaviors mediated by peripheral or central systems

    NASA Astrophysics Data System (ADS)

    Rabin, B. M.; Joseph, J. A.; Erat, S.

    The effects of exposure to ionizing radiation on behavior may result from effects on peripheral or on central systems. For behavioral endpoints that are mediated by peripheral systems (e.g., radiation-induced conditioned taste aversion or vomiting), the behavioral effects of exposure to heavy particles (^56Fe, 600 MeV/n) are qualitatively similar to the effects of exposure to gamma radiation (^60Co) and to fission spectrum neutrons. For these endpoints, the only differences between the different types of radiation are in terms of relative behavioral effectiveness. For behavioral endpoints that are mediated by central systems (e.g., amphetamine-induced taste aversion learning), the effects of exposure to ^56Fe particles are not seen following exposure to lower LET gamma rays or fission spectrum neutrons. These results indicate that the effects of exposure to heavy particles on behavioral endpoints cannot necessarily be extrapolated from studies using gamma rays, but require the use of heavy particles.

  7. Thermal quasiparticle random-phase approximation with Skyrme interactions and supernova neutral-current neutrino-nucleus reactions

    NASA Astrophysics Data System (ADS)

    Dzhioev, Alan A.; Vdovin, A. I.; Martínez-Pinedo, G.; Wambach, J.; Stoyanov, Ch.

    2016-07-01

    The thermal quasiparticle random-phase approximation is combined with the Skyrme energy density functional method (Skyrme-TQRPA) to study the response of a hot nucleus to an external perturbation. For the sample nuclei 56Fe and 82Ge, the Skyrme-TQRPA is applied to analyze thermal effects on the strength function of charge-neutral Gamow-Teller transitions, which dominate neutrino-nucleus reactions at Eν≲20 MeV. For the relevant supernova temperatures we calculate the cross sections for inelastic neutrino scattering. We also apply the method to examine the rate of neutrino-antineutrino pair emission by hot nuclei. The cross sections and rates are compared with those obtained earlier from the TQRPA calculations based on the phenomenological quasiparticle-phonon model Hamiltonian. For inelastic neutrino scattering on 56Fe we also compare the Skyrme-TQRPA results to those obtained earlier from a hybrid approach that combines shell-model and RPA calculations.

  8. High-temperature fractionation of stable iron isotopes in terrestrial and extra-terrestrial samples determined by ultra-precise measurements with a 57Fe-58Fe double spike and MC-ICPMS

    NASA Astrophysics Data System (ADS)

    Millet, M.; Baker, J.

    2010-12-01

    We have developed techniques for precise stable Fe isotope measurement utilising a 57Fe-58Fe double spike and pseudo-high-resolution MC-ICPMS. Instrumental mass bias is corrected using a 57Fe-58Fe double spike with a spike 58Fe/57Fe ratio of 1.012. Fe isotope analyses are carried out on a Nu Plasma MC-ICPMS with a DSN-100 desolvating nebuliser system. The MC-ICPMS is operated in pseudo-high-resolution mode with a mass resolution of ca. 3000 on all Fe isotopes permitting resolution of Fe isotope peaks from argide interferences. Residual interferences in the form of tails from these Ar-based interferences are corrected for by normalizing data to analyses of bracketing standards of the IRMM-014 standard. Repeated measurement of IRMM-014 yields an external reproducibility of 0.02‰ (2sd, n=26) on δ56Fe. Fe is separated from samples using conventional anion-exchange techniques. Replicate digestions of the JF-2 alkali feldspar standard yield an external reproducibility of 0.025‰ (2sd, n=5). Based on those results, error models predict that precisions of ≤ 0.01‰ (2sd) are attainable for standards and samples by combining multiple measurements of several sample digestions. We will present ultra-precise measurements of an array of international rock standards utilizing these techniques. We have obtained precise stable Fe isotope results on silicate minerals from a range of terrestrial magmatic rocks (basalt to rhyolite) and basaltic meteorites (angrites and eucrites). These results indicate that substantial stable Fe isotope fractionations (δ56Fe = -1.0 to 0.85‰) exist in high-temperature magmatic systems on Earth, which appear to be redox-controlled. Fe2+-dominated minerals like olivine display marked enrichment in light isotopes of Fe (δ56Fe = -0.35 to -0.30‰) compared to the host basaltic melt (δ56Fe = 0.05 to 0.22‰). Conversely, clinopyroxene typically has a stable Fe isotope composition only slightly lower or similar to the host melt. Notably

  9. Evidence for the onset of color transparency in ρ0 electroproduction off nuclei

    DOE PAGES

    Guo, L.; Hanretty, C.; Hicks, K.; Holt, R. J.; Hyde, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jawalker, S. S.; et al

    2012-05-11

    We have measured the nuclear transparency of the incoherent diffractive A(e,e'ρ0) process in 12C and 56Fe targets relative to 2H using a 5 GeV electron beam. The nuclear transparency, the ratio of the produced {rho}{sup 0}'s on a nucleus relative to deuterium, which is sensitive to ρA interaction, was studied as function of the coherence length (Ic), a lifetime of the hadronic fluctuation of the virtual photon, and the four-momentum transfer squared (Q2). Thus, while the transparency for both 12C and 56Fe showed no Ic dependence, a significant Q2 dependence was measured, which is consistent with calculations that included themore » color transparency effects.« less

  10. Neutrino absorption by hot nuclei in supernova environments

    NASA Astrophysics Data System (ADS)

    Dzhioev, Alan A.; Vdovin, A. I.; Wambach, J.

    2015-10-01

    Using the thermal quasiparticle random-phase approximation, we study the process of neutrino and antineutrino capture on hot nuclei in supernova environments. For the sample nuclei 56Fe and 82Ge we perform a detailed analysis of thermal effects on the strength distribution of allowed Gamow-Teller (GT) transitions which dominate low-energy charged-current neutrino reactions. The finite-temperature cross sections are calculated taking into account the contributions of both allowed and forbidden transitions. The enhancement of the low-energy cross sections is explained by considering thermal effects on the GT± strength. For 56Fe we compare the calculated finite-temperature cross sections with those obtained from large-scale shell-model calculations.

  11. Correlation of 48Ca, 50Ti, and 138La Heterogeneity in the Allende Refractory Inclusions

    NASA Astrophysics Data System (ADS)

    Chen, Hsin-Wei; Lee, Typhoon; Lee, Der-Chuen; Chen, Jiang-Chang

    2015-06-01

    Precise determinations of 48Ca anomalies in Allende calcium-aluminum-rich inclusions (CAIs) are reported in this work. There are endemic positive 48Ca/44Ca anomalies in all analyzed CAIs after normalization to 42Ca/44Ca, and it is clearly shown that there is no simple correlation between 48Ca/44Ca and 50Ti/48Ti anomalies, in agreement with Jungck et al. Compared to the 48Ca/44Ca versus 50Ti/48Ti correlation line defined by differentiated meteorites, reported by Chen et al., the CAIs plot to elevated 50Ti/48Ti. Assuming the 48Ca/44Ca anomalies of both CAIs and differentiated meteorites came from the same source, excess 50Ti anomalies in CAIs can be calculated by subtracting the part associated with 48Ca/44Ca. These excesses show a linear correlation with 138La anomalies, a neutrino-process nuclide. According to current stellar nucleosynthetic models, we therefore suggest that the solar system 48Ca, 50Ti, and 138La isotopic variations are made of mixtures between grains condensed from ejecta of neutron-rich accretion-induced SNe Ia and the O/Ne-O/C zone of core-collapse SNe II.

  12. 28Silicon Irradiation Impairs Contextual Fear Memory in B6D2F1 Mice.

    PubMed

    Raber, Jacob; Marzulla, Tessa; Stewart, Blair; Kronenberg, Amy; Turker, Mitchell S

    2015-06-01

    The space radiation environment consists of multiple species of charged particles, including (28)Si, (48)Ti and protons that may impact cognition, but their damaging effects have been poorly defined. In mouse studies, C57Bl6/J homozygous wild-type mice and genetic mutant mice on a C57Bl6/J background have typically been used for assessing effects of space radiation on cognition. In contrast, little is known about the radiation response of mice on a heterozygous background. Therefore, in the current study we tested the effects of (28)Si, (48)Ti and proton radiation on hippocampus-dependent contextual fear memory and hippocampus-independent cued fear memory in C57Bl6/J × DBA2/J F1 (B6D2F1) mice three months after irradiation. Contextual fear memory was impaired at a 1.6 Gy dose of (28)Si radiation, but not cued fear memory. (48)Ti or proton irradiation did not affect either type of memory. Based on earlier space radiation cognitive data in C57Bl6/J mice, these data highlight the importance of including different genetic backgrounds in studies aimed at assessing cognitive changes after exposure to space radiation.

  13. The Tamm-Dancoff Approximation as the Contraction Limit of the Richardson-Gaudin Equations

    NASA Astrophysics Data System (ADS)

    de Baerdemacker, S.

    2013-03-01

    A connection is made between the exact eigenstates of the level-independent Bardeen-Cooper-Schrieffer (BCS) Hamiltonian and its Tamm-Dancoff Approximation (TDA). This is done by means of a deformation of the quasi-spin algebra, which connects the Bethe Ansatz states with a unique multi-phonon mode of the TDA. The procedure is illustrated with a model describing neutron superluidity in 56Fe.

  14. Resolving the stellar sources of isotopically rare presolar silicate grains through Mg and Fe isotopic analyses

    SciTech Connect

    Nguyen, Ann N.; Messenger, Scott

    2014-04-01

    We conducted multi-element isotopic analyses of 11 presolar silicate grains from the Acfer 094 meteorite having unusual O isotopic compositions. Eight grains are {sup 18}O-rich, one is {sup 16}O-rich, and two are extremely {sup 17}O-rich. We constrained the grains' stellar sources by measuring their Si and Mg isotopic ratios, and also the {sup 54}Fe/{sup 56}Fe and {sup 57}Fe/{sup 56}Fe ratios for five grains. The Mg and Fe isotopic measurements were conducted after surrounding matrix grains were removed for more accurate ratios. Most of the {sup 18}O-rich silicates had anomalous Mg isotopic ratios, and their combined isotopic constraints are consistent with origins in low-mass Type II supernovae (SNe II) rather than high-metallicity stars. The isotopic ratios of the {sup 16}O-rich silicate are also consistent with an SN origin. Mixing small amounts of interior stellar material with the stellar envelope replicated all measured isotopic ratios except for {sup 29}Si/{sup 28}Si and {sup 54}Fe/{sup 56}Fe in some grains. The {sup 29}Si/{sup 28}Si ratios of all SN-derived grains are matched by doubling the {sup 29}Si yield in the Ne- and Si-burning zones. The {sup 54}Fe/{sup 56}Fe ratios of the grains imply elemental fractionation in the Si/S zone, or introduction of isotopically solar Fe by secondary processing. The two highly {sup 17}O-rich silicates exhibited significant {sup 25}Mg and/or {sup 26}Mg enrichments and their isotopic ratios are best explained by strong dilution of 1.15 M {sub ☉} CO nova matter. We estimate that ∼12% and 1% of presolar silicates have SN and nova origins, respectively, similar to presolar SiC and oxides. This implies that asymptotic giant branch stars are the dominant dust producers in the galaxy.

  15. Use of nuclear resonant scattering of gamma rays for in vivo measurement of iron

    SciTech Connect

    Vartsky, D.; Wielopolski, L.; Ellis, K.J.; Cohn, S.H.

    1981-01-01

    A technique for determination of elements in human body in-vivo, utilizing nuclear resonant scattering of gamma rays has been developed. 847 keV photons emitted from a gaseous /sup 56/MnCl/sub 2/ source are resonantly scattered from /sup 56/Fe present in the body. The detection of these gamma rays is used to estimate the iron content of the liver or heart of patients. Details of the calibration procedure and potential molecular effects are described.

  16. Redox changes induced in hippocampal precursor cells by heavy ion irradiation.

    PubMed

    Limoli, C L; Giedzinski, E; Baure, J; Rola, R; Fike, J R

    2007-06-01

    Hippocampal precursors retain the capacity to proliferate and differentiate throughout life, and their progeny, immature neurons, can undergo neurogenesis, a process believed to be important in maintaining the cognitive health of an organism. A variety of stresses including irradiation have been shown to deplete neural precursor cells, an effect that inhibits neurogenesis and is associated with the onset of cognitive impairments. Our past work has shown that neural precursor cells exposed to X-rays or protons exhibit a prolonged increase in oxidative stress, a factor we hypothesize to be critical in regulating the function of these cells after irradiation and other stresses. Here we report that irradiation of hippocampal precursor cells with high-linear energy transfer (LET) 1 GeV/nucleon 56Fe ions leads to significantly higher levels of oxidative stress when compared to lower LET radiations (X-rays, protons). Irradiation with 1 Gy of 56Fe ions elicits twofold to fivefold higher levels of reactive oxygen species (ROS) compared to unirradiated controls, and at lower doses (56Fe ion irradiation. These results conclusively show that low doses of 56Fe ions can elicit significant levels of oxidative stress in neural precursor cells. Given the prevalence of heavy ions in space and the duration of interplanetary travel, these data suggest that astronauts are at risk for developing cognitive decrements. However, our results also indicate that antioxidants delivered before as radioprotective agents or after as mitigating agents hold promise as effective countermeasures for ameliorating certain adverse effects of heavy ion exposure to the CNS.

  17. The effects of heavy particle irradiation on exploration and response to environmental change

    NASA Astrophysics Data System (ADS)

    Casadesus, G.; Shukitt-Hale, B.; Cantuti-Castelvetri, I.; Rabin, B.; Joseph, J.

    Free radicals produced by exposure to heavy particles have been found to produce motor and behavioral toxicity effects in rats similar to those found during aging. The present research was designed to investigate the effects of exposure to 56Fe particles on the ability to detect novel arrangements in a given environment of male Sprague-Dawley rats. Using a test of spatial memory previously demonstrated to be sensitive to aging, open-field activity and reaction to spatial and non-spatial changes were measured in a group that received a dose of 1.5 Gy (n=10) of 56Fe heavy particle radiation or in non- radiated controls. Animals irradiated with 1.5 Gy of56Fe particles exhibited some age-like effects in animals tested, even though they were for the most part, subtle. Animals took longer to enter, visited less and spent significantly less time in the middle and the center portions of the open-field independently of total frequency and duration of activity of both groups. Likewise, irradiated subjects reacted significantly more to novel objects placed in the open-field than did controls. However, irradiated subjects did not vary from controls in their exploration patterns when objects in the open-field were spatially rearranged. Thus, irradiation with a dose of 1.5 Gy of 56Fe high-energy particle radiation elicited age-like effects in general open-field exploratory behavior, but did not elicit age- like effects during the spatial and non-spatial rearrangement tasks. Supported by N.A.S.A. Grant NAG9-1190.

  18. Interaction between age of irradiation and age of testing in the disruption of operant performance using a ground-based model for exposure to cosmic rays.

    PubMed

    Rabin, Bernard M; Joseph, James A; Shukitt-Hale, Barbara; Carrihill-Knoll, Kirsty L

    2012-02-01

    Previous research has shown a progressive deterioration in cognitive performance in rats exposed to (56)Fe particles as a function of age. The present experiment was designed to evaluate the effects of age of irradiation independently of the age of testing. Male Fischer-344 rats, 2, 7, 12, and 16 months of age, were exposed to 25-200 cGy of (56)Fe particles (1,000 MeV/n). Following irradiation, the rats were trained to make an operant response on an ascending fixed-ratio reinforcement schedule. When performance was evaluated as a function of both age of irradiation and testing, the results showed a significant effect of age on the dose needed to produce a performance decrement, such that older rats exposed to lower doses of (56)Fe particles showed a performance decrement compared to younger rats. When performance was evaluated as a function of age of irradiation with the age of testing held constant, the results indicated that age of irradiation was a significant factor influencing operant responding, such that older rats tested at similar ages and exposed to similar doses of (56)Fe particles showed similar performance decrements. The results are interpreted as indicating that the performance decrement is not a function of age per se, but instead is dependent upon an interaction between the age of irradiation, the age of testing, and exposure to HZE particles. The nature of these effects and how age of irradiation affects cognitive performance after an interval of 15 to 16 months remains to be established.

  19. Search for anomalous fragments produced in collisions with heavy target nuclei and in delta Z = 1 peripheral interactions

    NASA Technical Reports Server (NTRS)

    Drechsel, H.; Brechtmann, C.; Heinrich, W.; Dreute, J.; Benton, E. V.

    1985-01-01

    We exposed a stack of CR39 track detectors containing Ag foils to a 1.7-GeV/nucleon 56Fe beam and investigated the anomalous mean-free-path effect. Neither the whole set of 7517 nor a subset of 2542 interacting fragments produced probably in the Ag target show an effect. By combining the data of this and an earlier experiment we can also exclude an effect for 3219 interacting fragments produced in delta Z = 1 collisions.

  20. The effects of heavy particle irradiation on exploration and response to environmental change

    NASA Technical Reports Server (NTRS)

    Casadesus, G.; Shukitt-Hale, B.; Cantuti-Castelvetri, I.; Rabin, B. M.; Joseph, J. A.

    2004-01-01

    Free radicals produced by exposure to heavy particles have been found to produce motor and cognitive behavioral toxicity effects in rats similar to those found during aging. The present research was designed to investigate the effects of exposure to 56Fe particles on the ability of male Sprague-Dawley rats to detect novel arrangements in a given environment. Using a test of spatial memory previously demonstrated to be sensitive to aging, open field activity and reaction to spatial and non-spatial changes were measured in a group that received a dose of 1.5 Gy (n=10) of 56Fe heavy particle radiation or in non-radiated controls (n=10). Animals irradiated with 1.5 Gy of 56Fe particles exhibited some age-like effects in rats tested, even though they were, for the most part, subtle. Animals took longer to enter, visited less and spent significantly less time in the middle and the center portions of the open field, independently of total frequency and duration of activity of both groups. Likewise, irradiated subjects spend significantly more time exploring novel objects placed in the open field than did controls. However, irradiated subjects did not vary from controls in their exploration patterns when objects in the open field were spatially rearranged. Thus, irradiation with a dose of 1.5 Gy of 56Fe high-energy particle radiation elicited age-like effects in general open field exploratory behavior, but did not elicit age-like effects during the spatial and non-spatial rearrangement tasks. Published by Elsevier Ltd on behalf of COSPAR.

  1. Comet encke: meteor metallic ion identification by mass spectrometer.

    PubMed

    Goldberg, R A; Aikin, A C

    1973-04-20

    Metal ions including 23(+) (Na(+)), 24(+) (Mg(+)) 28(+) (Si(+)), 39(+) (K(+)), 40(+) (Ca(+)), 45(+) (Sc(+)), 52(+) Cr(+)). 56(+) (Fe(+)), and 58(+) (Ni(+)) have been detected in the upper atmosphere during the period of the Beta Taurids meteor shower. The abundances of these ions relative to Si(+) show, agreement in most instances with abundances in chondrites. A notable exception is 45(+), which, if it is Sc(+), is 100 times more abundant than neutral scandium found in chondrites. PMID:17816288

  2. Fe and O isotope composition of meteorite fusion crusts: Possible natural analogues to chondrule formation?

    NASA Astrophysics Data System (ADS)

    Hezel, Dominik C.; Poole, Graeme M.; Hoyes, Jack; Coles, Barry J.; Unsworth, Catherine; Albrecht, Nina; Smith, Caroline; RehkäMper, Mark; Pack, Andreas; Genge, Matthew; Russell, Sara S.

    2015-02-01

    Meteorite fusion crust formation is a brief event in a high-temperature (2000-12,000 K) and high-pressure (2-5 MPa) regime. We studied fusion crusts and bulk samples of 10 ordinary chondrite falls and 10 ordinary chondrite finds. The fusion crusts show a typical layering and most contain vesicles. All fusion crusts are enriched in heavy Fe isotopes, with δ56Fe values up to +0.35‰ relative to the solar system mean. On average, the δ56Fe of fusion crusts from finds is +0.23‰, which is 0.08‰ higher than the average from falls (+0.15‰). Higher δ56Fe in fusion crusts of finds correlate with bulk chondrite enrichments in mobile elements such as Ba and Sr. The δ56Fe signature of meteorite fusion crusts was produced by two processes (1) evaporation during atmospheric entry and (2) terrestrial weathering. Fusion crusts have either the same or higher δ18O (0.9-1.5‰) than their host chondrites, and the same is true for Δ17O. The differences in bulk chondrite and fusion crust oxygen isotope composition are explained by exchange of oxygen between the molten surface of the meteorites with the atmosphere and weathering. Meteorite fusion crust formation is qualitatively similar to conditions of chondrule formation. Therefore, fusion crusts may, at least to some extent, serve as a natural analogue to chondrule formation processes. Meteorite fusion crust and chondrules exhibit a similar extent of Fe isotope fractionation, supporting the idea that the Fe isotope signature of chondrules was established in a high-pressure environment that prevented large isotope fractionations. The exchange of O between a chondrule melt and an 16O-poor nebula as the cause for the observed nonmass dependent O isotope compositions in chondrules is supported by the same process, although to a much lower extent, in meteorite fusion crusts.

  3. Comet encke: meteor metallic ion identification by mass spectrometer.

    PubMed

    Goldberg, R A; Aikin, A C

    1973-04-20

    Metal ions including 23(+) (Na(+)), 24(+) (Mg(+)) 28(+) (Si(+)), 39(+) (K(+)), 40(+) (Ca(+)), 45(+) (Sc(+)), 52(+) Cr(+)). 56(+) (Fe(+)), and 58(+) (Ni(+)) have been detected in the upper atmosphere during the period of the Beta Taurids meteor shower. The abundances of these ions relative to Si(+) show, agreement in most instances with abundances in chondrites. A notable exception is 45(+), which, if it is Sc(+), is 100 times more abundant than neutral scandium found in chondrites.

  4. Iron isotope fractionation in marine invertebrates in near shore environments

    NASA Astrophysics Data System (ADS)

    Emmanuel, S.; Schuessler, J. A.; Vinther, J.; Matthews, A.; von Blanckenburg, F.

    2014-04-01

    Chitons (Mollusca) are marine invertebrates that produce radula (teeth or rasping tongue) containing high concentrations of biomineralized magnetite and other iron bearing minerals. As Fe isotope signatures are influenced by redox processes and biological fractionation, Fe isotopes in chiton radula might be expected to provide an effective tracer of ambient oceanic conditions and biogeochemical cycling. Here, in a pilot study to measure Fe isotopes in marine invertebrates, we examine Fe isotopes in modern marine chiton radula collected from different locations in the Atlantic and Pacific oceans to assess the range of isotopic values, and to test whether or not the isotopic signatures reflect seawater values. Furthermore, by comparing two species that have very different feeding habits but collected from the same location, we infer a possible link between diet and Fe isotopic signatures. Values of δ56Fe (relative to IRMM-014) in chiton teeth range from -1.90 to 0.00‰ (±0.05‰ (2σ) uncertainty in δ56Fe), probably reflecting a combination of geographical control and biological fractionation processes. Comparison with published local surface seawater Fe isotope data shows a consistent negative offset of chiton teeth Fe isotope compositions relative to seawater. Strikingly, two different species from the same locality in the North Pacific (Puget Sound, Washington, USA) have distinct isotopic signatures. Tonicella lineata, which feeds on red algae, has a mean δ56Fe of -0.65 ± 0.26‰ (2σ, 3 specimens), while Mopalia muscosa, which feeds primarily on green algae, shows lighter isotopic values with a mean δ56Fe of -1.47 ± 0.98‰ (2σ, 5 specimens). Although chitons are not simple recorders of the ambient seawater Fe isotopic signature, these preliminary results suggest that Fe isotopes provide information concerning Fe biogeochemical cycling in near shore environments, and might be used to probe sources of Fe in the diets of different organisms.

  5. Fe Isotope Systematics of the Upper and Upper Main Zones of the Bushveld Complex, South Africa

    NASA Astrophysics Data System (ADS)

    Bilenker, L.; VanTongeren, J. A.; Lundstrom, C.; Simon, A. C.

    2014-12-01

    The Rustenberg Layered Suite of the Bushveld Complex, South Africa is the world's largest exposed mafic magma chamber. The uppermost ~2.5 km of the 8-9 km thick intrusion are represented by the Upper and Upper Main Zones (UUMZ) and are thought to denote the final pulse of magma into the chamber. The basaltic-basaltic andesite parent magma to the UUMZ produced orthopyroxenites and gabbronorites at the base of the UUMZ. ~800 m above the base, the rocks contain cumulus magnetite (5-10 modal%), and magnetite layers occur throughout the remaining stratigraphy. Fa-olivine joins the cumulus mineral assemblage ~1300 m above the base, and cumulus apatite joins ~1800 m above the base. Mineral compositions evolve systematically from the base to the roof, making the UUMZ the best place to investigate extreme magmatic fractionation. We report Fe isotope data (δ56Fe) throughout the UUMZ in the eastern Bushveld in order to investigate differentiation processes and geochemical evolution during crystallization. Preliminary measurements of magnetite (δ56Femt = 0.16 to 0.47‰) show two important features: (1) In the lower part of the UUMZ (0 - ~1800 m above the base), δ56Femt decreases with increasing stratigraphic height, such that samples prior to cumulus magnetite saturation show high δ56Fe, and samples above magnetite saturation show lower δ56Fe. (2) In the top 600 m of the UUMZ, however, we observe an increase in δ56Femt that is inconsistent with the fractional crystallization trend below, suggesting this section formed by silicate liquid immiscibility, consistent with the previous conclusions for this interval on the basis of apatite REEs. Our ongoing work on the δ56Fe of whole rock and mineral separates throughout the UUMZ stratigraphy will provide an important benchmark for Fe isotope fractionation during magmatic differentiation.

  6. Oxygenation of Ediacaran Ocean recorded by iron isotopes

    NASA Astrophysics Data System (ADS)

    Fan, Haifeng; Zhu, Xiangkun; Wen, Hanjie; Yan, Bin; Li, Jin; Feng, Lianjun

    2014-09-01

    The increase in atmospheric oxygen during the late Neoproterozoic Era (ca. 800-542 Ma) may have stimulated the oxygenation of the deep oceans and the evolution of macroscopic multicellular organisms. However, the mechanism and magnitude of Neoproterozoic oxygenation remain uncertain. We present Fe isotopes, Fe species and other geochemical data for two sections of the Doushantuo Formation (ca. 635-551 Ma) deposited after the Nantuo glacial episode in the Yangtze Gorge area, South China. It is highlighted that highly positive δ56Fe values reflect a lower oxidation rate of Fe(II)aq under ferruginous conditions, and in turn near zero δ56Fe values indicate oxidizing conditions. Our study suggests that during the deposition of the bottom of Member II of the Doushantuo Formation the shallow seawater was oxic, but the deep water was characterized by ferruginous conditions, which is consistent with a redox chemical stratification model. Subsequent anoxic conditions under shallow seawater, represented by positive δ56Fe and negative δ13Ccarb excursions, should be ascribed to the upwelling of Fe(II)aq and dissolved organic carbon (DOC)-rich anoxic deep seawater. The oxidation of Fe (II)aq and DOC-rich anoxic deep seawater upon mixing with oxic shallow water provides an innovative explanation for the well-known negative δ13Ccarb excursions (ENC2) and positive δ56Fe excursions in the middle of Doushantuo Formation. Meanwhile, the upwelling Fe (II)aq- and DOC-rich anoxic deep seawater could increase photosynthetic activity. The balance between oxygen consumption and production was most important criteria for the oxygenation of Early Ediacaran Ocean and diversity of eukaryotic organisms.

  7. Effects of heavy particle irradiation and diet on amphetamine- and lithium chloride-induced taste avoidance learning in rats

    NASA Technical Reports Server (NTRS)

    Rabin, Bernard M.; Shukitt-Hale, Barbara; Szprengiel, Aleksandra; Joseph, James A.

    2002-01-01

    Rats were maintained on diets containing either 2% blueberry or strawberry extract or a control diet for 8 weeks prior to being exposed to 1.5 Gy of 56Fe particles in the Alternating Gradient Synchrotron at Brookhaven National Laboratory. Three days following irradiation, the rats were tested for the effects of irradiation on the acquisition of an amphetamine- or lithium chloride-induced (LiCl) conditioned taste avoidance (CTA). The rats maintained on the control diet failed to show the acquisition of a CTA following injection of amphetamine. In contrast, the rats maintained on antioxidant diets (strawberry or blueberry extract) continued to show the development of an amphetamine-induced CTA following exposure to 56Fe particles. Neither irradiation nor diet had an effect on the acquisition of a LiCl-induced CTA. The results are interpreted as indicating that oxidative stress following exposure to 56Fe particles may be responsible for the disruption of the dopamine-mediated amphetamine-induced CTA in rats fed control diets; and that a reduction in oxidative stress produced by the antioxidant diets functions to reinstate the dopamine-mediated CTA. The failure of either irradiation or diet to influence LiCl-induced responding suggests that oxidative stress may not be involved in CTA learning following injection of LiCl.

  8. Space radiation exposure persistently increased leptin and IGF1 in serum and activated leptin-IGF1 signaling axis in mouse intestine

    PubMed Central

    Suman, Shubhankar; Kumar, Santosh; Fornace, Albert J.; Datta, Kamal

    2016-01-01

    Travel into outer space is fraught with risk of exposure to energetic heavy ion radiation such as 56Fe ions, which due to its high linear energy transfer (high-LET) characteristics deposits higher energy per unit volume of tissue traversed and thus more damaging to cells relative to low-LET radiation such as γ rays. However, estimates of human health risk from energetic heavy ion exposure are hampered due to lack of tissue specific in vivo molecular data. We investigated long-term effects of 56Fe radiation on adipokines and insulin-like growth factor 1 (IGF1) signaling axis in mouse intestine and colon. Six- to eight-week-old C57BL/6J mice were exposed to 1.6 Gy of 56Fe ions. Serum and tissues were collected up to twelve months post-irradiation. Serum was analyzed for leptin, adiponectin, IGF1, and IGF binding protein 3. Receptor expressions and downstream signaling pathway alterations were studied in tissues. Irradiation increased leptin and IGF1 levels in serum, and IGF1R and leptin receptor expression in tissues. When considered along with upregulated Jak2/Stat3 pathways and cell proliferation, our data supports the notion that space radiation exposure is a risk to endocrine alterations with implications for chronic pathophysiologic changes in gastrointestinal tract. PMID:27558773

  9. High-LET radiation induces inflammation and persistent changes in markers of hippocampal neurogenesis.

    PubMed

    Rola, Radoslaw; Sarkissian, Vahe; Obenaus, Andre; Nelson, Gregory A; Otsuka, Shinji; Limoli, Charles L; Fike, John R

    2005-10-01

    Exposure to heavy-ion radiation is considered a potential health risk in long-term space travel. It may result in the loss of critical cellular components in complex systems like the central nervous system (CNS), which could lead to performance decrements that ultimately could compromise mission goals and long-term quality of life. Specific hippocampal-dependent cognitive impairment occurs after whole-body 56Fe-particle irradiation, and while the pathogenesis of this effect is not yet clear, it may involve damage to neural precursor cells in the hippocampal dentate gyrus. We irradiated mice with 1-3 Gy of 12C or 56Fe ions and 9 months later quantified proliferating cells and immature neurons in the dentate subgranular zone (SGZ). Our results showed that reductions in these cells were dependent on the dose and LET. When compared with data for mice that were studied 3 months after 56Fe-particle irradiation, our current data suggest that these changes are not only persistent but may worsen with time. Loss of precursor cells was also associated with altered neurogenesis and a robust inflammatory response. These results indicate that high-LET radiation has a significant and long-lasting effect on the neurogenic population in the hippocampus that involves cell loss and changes in the microenvironment.

  10. The relative biological effectiveness of densely ionizing heavy-ion radiation for inducing ocular cataracts in wild type versus mice heterozygous for the ATM gene.

    PubMed

    Hall, Eric J; Worgul, Basil V; Smilenov, Lubomir; Elliston, Carl D; Brenner, David J

    2006-07-01

    The accelerated appearance of ocular cataracts at younger ages has been recorded in both astronauts and airline pilots, and is usually attributed to high-energy heavy ions in galactic cosmic ray radiation. We have previously shown that high-LET 1-GeV/nucleon (56)Fe ions are significantly more effective than X-rays in producing cataracts in mice. We have also shown that mice haploinsufficient for ATM develop cataracts earlier than wild-type animals, when exposed to either low-LET X-rays or high-LET (56)Fe ions. In this paper we derive quantitative estimates for the relative biological effectiveness (RBE) of high energy (56)Fe ions compared with X-rays, both for wild type and for mice haploinsufficient for ATM. There is a clear trend toward higher RBE's in haploinsufficient animals, both for low- and high-grade cataracts. Haploinsufficiency for ATM results in an enhanced sensitivity to X-rays compared with the wild type, and this enhancement appears even larger after exposure to high-LET heavy ions. PMID:16799786

  11. Effects of heavy particle irradiation and diet on object recognition memory in rats

    NASA Astrophysics Data System (ADS)

    Rabin, Bernard M.; Carrihill-Knoll, Kirsty; Hinchman, Marie; Shukitt-Hale, Barbara; Joseph, James A.; Foster, Brian C.

    2009-04-01

    On long-duration missions to other planets astronauts will be exposed to types and doses of radiation that are not experienced in low earth orbit. Previous research using a ground-based model for exposure to cosmic rays has shown that exposure to heavy particles, such as 56Fe, disrupts spatial learning and memory measured using the Morris water maze. Maintaining rats on diets containing antioxidant phytochemicals for 2 weeks prior to irradiation ameliorated this deficit. The present experiments were designed to determine: (1) the generality of the particle-induced disruption of memory by examining the effects of exposure to 56Fe particles on object recognition memory; and (2) whether maintaining rats on these antioxidant diets for 2 weeks prior to irradiation would also ameliorate any potential deficit. The results showed that exposure to low doses of 56Fe particles does disrupt recognition memory and that maintaining rats on antioxidant diets containing blueberry and strawberry extract for only 2 weeks was effective in ameliorating the disruptive effects of irradiation. The results are discussed in terms of the mechanisms by which exposure to these particles may produce effects on neurocognitive performance.

  12. Space radiation exposure persistently increased leptin and IGF1 in serum and activated leptin-IGF1 signaling axis in mouse intestine.

    PubMed

    Suman, Shubhankar; Kumar, Santosh; Fornace, Albert J; Datta, Kamal

    2016-01-01

    Travel into outer space is fraught with risk of exposure to energetic heavy ion radiation such as (56)Fe ions, which due to its high linear energy transfer (high-LET) characteristics deposits higher energy per unit volume of tissue traversed and thus more damaging to cells relative to low-LET radiation such as γ rays. However, estimates of human health risk from energetic heavy ion exposure are hampered due to lack of tissue specific in vivo molecular data. We investigated long-term effects of (56)Fe radiation on adipokines and insulin-like growth factor 1 (IGF1) signaling axis in mouse intestine and colon. Six- to eight-week-old C57BL/6J mice were exposed to 1.6 Gy of (56)Fe ions. Serum and tissues were collected up to twelve months post-irradiation. Serum was analyzed for leptin, adiponectin, IGF1, and IGF binding protein 3. Receptor expressions and downstream signaling pathway alterations were studied in tissues. Irradiation increased leptin and IGF1 levels in serum, and IGF1R and leptin receptor expression in tissues. When considered along with upregulated Jak2/Stat3 pathways and cell proliferation, our data supports the notion that space radiation exposure is a risk to endocrine alterations with implications for chronic pathophysiologic changes in gastrointestinal tract. PMID:27558773

  13. Space radiation exposure persistently increased leptin and IGF1 in serum and activated leptin-IGF1 signaling axis in mouse intestine.

    PubMed

    Suman, Shubhankar; Kumar, Santosh; Fornace, Albert J; Datta, Kamal

    2016-08-25

    Travel into outer space is fraught with risk of exposure to energetic heavy ion radiation such as (56)Fe ions, which due to its high linear energy transfer (high-LET) characteristics deposits higher energy per unit volume of tissue traversed and thus more damaging to cells relative to low-LET radiation such as γ rays. However, estimates of human health risk from energetic heavy ion exposure are hampered due to lack of tissue specific in vivo molecular data. We investigated long-term effects of (56)Fe radiation on adipokines and insulin-like growth factor 1 (IGF1) signaling axis in mouse intestine and colon. Six- to eight-week-old C57BL/6J mice were exposed to 1.6 Gy of (56)Fe ions. Serum and tissues were collected up to twelve months post-irradiation. Serum was analyzed for leptin, adiponectin, IGF1, and IGF binding protein 3. Receptor expressions and downstream signaling pathway alterations were studied in tissues. Irradiation increased leptin and IGF1 levels in serum, and IGF1R and leptin receptor expression in tissues. When considered along with upregulated Jak2/Stat3 pathways and cell proliferation, our data supports the notion that space radiation exposure is a risk to endocrine alterations with implications for chronic pathophysiologic changes in gastrointestinal tract.

  14. ApoE isoform modulates effects of cranial ⁵⁶Fe irradiation on spatial learning and memory in the water maze.

    PubMed

    Yeiser, Lauren A; Villasana, Laura E; Raber, Jacob

    2013-01-15

    Apolipoprotein E, which plays an important role in lipid transport and metabolism and neuronal repair, might modulate the CNS risk following (56)Fe irradiation exposure during space missions. In this study, we investigated this risk by behavioral and cognitive testing male E2, E3, and E4 mice 3 months following cranial (56)Fe irradiation. In the open field, mice irradiated with 2 Gy showed higher activity levels than sham-irradiated mice or mice irradiated with 1 Gy. In addition, E2 mice showed higher activity and lower measures of anxiety than E3 and E4 mice in the open field and elevated zero maze. During hidden platform training, sham-irradiated mice showed most robust learning, 1 Gy irradiated mice reduced learning, and 2 Gy irradiated mice no improvement over the four sessions. In the water maze probe trials, sham-irradiated E2, E3, and E4 mice and E2 and E4 mice irradiated with 1 Gy showed spatial memory retention, but E3 mice irradiated with 1 Gy, and E2, E3, and E4 mice irradiated with 2 Gy did not. Thus, cranial (56)Fe irradiation increases activity levels in the open field and impairs spatial learning and memory in the water maze. E3 mice are more susceptible than E2 or E4 mice to impairments in spatial memory retention in the water maze, indicating that apoE isoform modulates the CNS risk following space missions.

  15. Coupled Fe(II)-Fe(III) electron and atom exchange as a mechanism for Fe isotope fractionation during dissimilatory iron oxide reduction.

    PubMed

    Crosby, Heidi A; Johnson, Clark M; Roden, Eric E; Beard, Brian L

    2005-09-01

    Microbial dissimilatory iron reduction (DIR) is an important pathway for carbon oxidation in anoxic sediments, and iron isotopes may distinguish between iron produced by DIR and other sources of aqueous Fe(II). Previous studies have shown that aqueous Fe(II) produced during the earliest stages of DIR has delta56Fe values that are 0.5-2.0%o lowerthan the initial Fe(III) substrate. The new experiments reported here suggest that this fractionation is controlled by coupled electron and Fe atom exchange between Fe(II) and Fe(III) at iron oxide surfaces. In hematite and goethite reduction experiments with Geobacter sulfurreducens, the 56Fe/54Fe isotopic fractionation between aqueous Fe(II) and the outermost layers of Fe(III) on the oxide surface is approximately -3%o and can be explained by equilibrium Fe isotope partitioning between reactive Fe(II) and Fe(III) pools that coexist during DIR. The results indicate that sorption of Fe(II) to Fe(III) substrates cannot account for production of low-delta56Fe values for aqueous Fe(II) during DIR.

  16. Theoretical and experimental tests of a chromosomal fingerprint for densely ionizing radiation based on F ratios calculated from stable and unstable chromosome aberrations

    NASA Technical Reports Server (NTRS)

    Lucas, J. N.; Deng, W.; Oram, S. W.; Hill, F. S.; Durante, M.; George, K.; Wu, H.; Owens, C. L.; Yang, T.

    1999-01-01

    In the present study, F ratios for both stable chromosome aberrations, i.e. ratios of translocations to pericentric inversions, and unstable aberrations, i.e. dicentrics and centric rings, were measured using fluorescence in situ hybridization. F ratios for stable aberrations measured after exposure to low (2.89 Gy 60Co gamma rays) and high-LET (0.25 Gy 56Fe ions; 1.25 Gy 56Fe ions; 3.0 Gy 12C ions) radiation were 6.5 +/- 1.5, 4.7 +/- 1.6, 9.3 +/- 2.5 and 10.4 +/- 3.0, respectively. F ratios for unstable aberrations measured after low (2.89 Gy 60Co gamma rays) and high-LET (0.25 Gy 56Fe ions; 3.0 Gy 12C ions) radiations were 6.5 +/- 1.6, 6.3 +/- 2.3 and 11.1 +/- 3.7, respectively. No significant difference between the F ratios for low- and high-LET radiation was found. Further tests on the models for calculation of the F ratio proposed by Brenner and Sachs (Radiat. Res. 140, 134-142, 1994) showed that the F ratio may not be straightforward as a practical fingerprint for densely ionizing radiation.

  17. Characteristics of Nucleus-Nucleus Interaction with Relativistic Heavy-Ions

    NASA Astrophysics Data System (ADS)

    Das, Gourisankar

    A systematic study of relativistic heavy-ion collisions in nuclear emulsion, initiated by ('40)Ar, ('56)Fe at E = 1.8 GeV/N, ('56)Fe at 0.8 GeV/N, and ('12)C at 400 MeV/N, has been made. Projectile fragmentation reactions, where there is no visual indication of target excitation, are studied in terms of multiplicity and projected angular distributions. The standard deviation widths of the projected angular distributions are compared with the first order theory of Lepore and Riddell. In quasi-central collisions, where a part of both the projectile and target nuclei participate, we have undertaken a study of the space angle distributions of the relativistic alpha particles, emitted in ('40)Ar -emulsion interactions at E = 1.8 GeV/N and ('56)Fe-emulsion interactions at E = 0.8 GeV/N. The large angle alpha particle distributions are fitted with moving relativistic Boltzmann distributions, and compared with distributions obtained by Monte Carlo simulation of (alpha)-p hard scattering process. Mean free path of secondary relativistic projectile fragments, emitted in such collisions, are carefully studied to verify the presence of 'anomalous' mfp component among these fragments. This is followed by a study of the mean free path of secondary alpha particles. Finally, in central collisions, the angular distributions of singly charged particles with (beta) > 0.7 are studied with a view to observe collective phenomena, such as nuclear shock wave in nuclear matter.

  18. Iron isotopic fractionation during continental weathering

    SciTech Connect

    Fantle, Matthew S.; DePaolo, Donald J.

    2003-10-01

    The biological activity on continents and the oxygen content of the atmosphere determine the chemical pathways through which Fe is processed at the Earth's surface. Experiments have shown that the relevant chemical pathways fractionate Fe isotopes. Measurements of soils, streams, and deep-sea clay indicate that the {sup 56}Fe/{sup 54}Fe ratio ({delta}{sup 56}Fe relative to igneous rocks) varies from +1{per_thousand} for weathering residues like soils and clays, to -3{per_thousand} for dissolved Fe in streams. These measurements confirm that weathering processes produce substantial fractionation of Fe isotopes in the modern oxidizing Earth surface environment. The results imply that biologically-mediated processes, which preferentially mobilize light Fe isotopes, are critical to Fe chemistry in weathering environments, and that the {delta}{sup 56}Fe of marine dissolved Fe should be variable and negative. Diagenetic reduction of Fe in marine sediments may also be a significant component of the global Fe isotope cycle. Iron isotopes provide a tracer for the influence of biological activity and oxygen in weathering processes through Earth history. Iron isotopic fractionation during weathering may have been smaller or absent in an oxygen-poor environment such as that of the early Precambrian Earth.

  19. Application of iron and zinc isotopes to track the sources and mechanisms of metal loading in a mountain watershed

    USGS Publications Warehouse

    Borrok, D.M.; Wanty, R.B.; Ian, Ridley W.; Lamothe, P.J.; Kimball, B.A.; Verplanck, P.L.; Runkel, R.L.

    2009-01-01

    Here the hydrogeochemical constraints of a tracer dilution study are combined with Fe and Zn isotopic measurements to pinpoint metal loading sources and attenuation mechanisms in an alpine watershed impacted by acid mine drainage. In the tested mountain catchment, ??56Fe and ??66Zn isotopic signatures of filtered stream water samples varied by ???3.5??? and 0.4???, respectively. The inherent differences in the aqueous geochemistry of Fe and Zn provided complimentary isotopic information. For example, variations in ??56Fe were linked to redox and precipitation reactions occurring in the stream, while changes in ??66Zn were indicative of conservative mixing of different Zn sources. Fen environments contributed distinctively light dissolved Fe (<-2.0???) and isotopically heavy suspended Fe precipitates to the watershed, while Zn from the fen was isotopically heavy (>+0.4???). Acidic drainage from mine wastes contributed heavier dissolved Fe (???+0.5???) and lighter Zn (???+0.2???) isotopes relative to the fen. Upwelling of Fe-rich groundwater near the mouth of the catchment was the major source of Fe (??56Fe ??? 0???) leaving the watershed in surface flow, while runoff from mining wastes was the major source of Zn. The results suggest that given a strong framework for interpretation, Fe and Zn isotopes are useful tools for identifying and tracking metal sources and attenuation mechanisms in mountain watersheds. ?? 2009 Elsevier Ltd.

  20. Modulation of human cell responses to space radiation by gap-junction communication

    NASA Astrophysics Data System (ADS)

    Autsavapromporn, Narongchai; de Toledo, Sonia M.; Buonanno, Manuela; Yang, Zhi; Harris, Andrew; Jay-Gerin, Jean-Paul; Azzam, Edouard

    Understanding the biological effects of space radiation and their underlying mechanism is critical to estimating the health risk associated with human exploration of space. A coordinated interaction of multiple cellular processes is likely involved in the sensing and processing of stressful effects induced by different types of space radiation. Here, we focused on the role of gap-junction intercellular communication (GJIC) in responses of human cells exposed to 1 GeV/n protons or 56 Fe-ions. We compared the results with data obtained in human cells exposed, in parallel, to γ-rays or α-particles. As expected, a higher level of cell killing and DNA damage, per unit dose, was induced in confluent, density-inhibited cells (98% in G0 /G1 ) exposed to α-particles or energetic 56 Fe-ions than γ-rays or protons. Strikingly, greatly attenuated effects occurred when sub-confluent cultures, synchronized in G0 /G1 ,were exposed to 56 Fe-ions. These data suggest that direct intercellular communication is involved in the effects of high linear energy transfer (LET) 56 Fe-ions. To examine the role of gap-junctions in propagating stressful effect, confluent cultures were exposed to 56 Fe-ions or α-particles and incubated for various time periods at 37° C in the presence or absence of the gap-junction inhibitor α-glycyrrhetinic acid (AGA). No repair of potentially lethal radiation damage occurred in cells incubated in the absence of AGA. In contrast, inhibition of functional GJIC significantly enhanced clonogenic survival of irradiated cells. To test the role of junctional channel permeability in the observed effects, we used human adenocarcinoma (HeLa) cells in which specific connexins (Cx) can be expressed in the absence of endogenous connexins. Whereas HeLa cells with selective inducible expression of Cx26 gap-junctions promoted radiation toxic effects, expression of Cx32 junctional channels in HeLa cells promoted pro-survival effects. Experiments are in progress to

  1. Discerning crystal growth from diffusion profiles in zoned olivine by in situ Mg–Fe isotopic analyses

    USGS Publications Warehouse

    Sio, Corliss Kin I.; Dauphas, Nicolas; Teng, Fang-Zhen; Chaussidon, Marc; Helz, Rosalind T.; Roskosz, Mathieu

    2013-01-01

    Mineral zoning is used in diffusion-based geospeedometry to determine magmatic timescales. Progress in this field has been hampered by the challenge to discern mineral zoning produced by diffusion from concentration gradients inherited from crystal growth. A zoned olivine phenocryst from Kilauea Iki lava lake (Hawaii) was selected for this study to evaluate the potential of Mg and Fe isotopes for distinguishing these two processes. Microdrilling of the phenocryst (∼300 μm drill holes) followed by MC-ICPMS analysis of the powders revealed negatively coupled Mg and Fe isotopic fractionations (δ26Mg from +0.1‰ to −0.2‰ and δ56Fe from −1.2‰ to −0.2‰ from core to rim), which can only be explained by Mg–Fe exchange between melt and olivine. The data can be explained with ratios of diffusivities of Mg and Fe isotopes in olivine scaling as D2/D1 = (m1/m2)β with βMg ∼0.16 and βFe ∼0.27. LA-MC-ICPMS and MC-SIMS Fe isotopic measurements are developed and are demonstrated to yield accurate δ56Fe measurements within precisions of ∼0.2‰ (1 SD) at spatial resolutions of ∼50 μm. δ56Fe and δ26Mg stay constant with Fo# in the rim (late-stage overgrowth), whereas in the core (original phenocryst) δ56Fe steeply trends toward lighter compositions and δ26Mg trends toward heavier compositions with higher Fo#. A plot of δ56Fe vs. Fo# immediately distinguishes growth-controlled from diffusion-controlled zoning in these two regions. The results are consistent with the idea that large isotopic fractionation accompanies chemical diffusion in crystals, whereas fractional crystallization induces little or no isotopic fractionation. The cooling timescale inferred from the chemical-isotope zoning profiles is consistent with the documented cooling history of the lava lake. In the absence of geologic context, in situ stable isotopic measurements may now be used to interpret the nature of mineral zoning. Stable isotope measurements by LA-MC-ICPMS and MC

  2. Iron isotope fractionation by microbial iron reduction in modern chemically precipitated sediments

    NASA Astrophysics Data System (ADS)

    Roden, E. E.; Tangalos, G. E.; Beard, B. L.; Johnson, C. M.; Alpers, C. N.; Shelobolina, E. S.; Xu, H.; Konishi, H.

    2008-12-01

    Laboratory experiments have demonstrated that dissimilatory microbial iron oxide reduction (DIR) can produce Fe(II) phases that have low 56Fe/54Fe ratios similar to those found in Neoarchean and Paleoproterozoic banded iron formations (BIFs) and shales. Direct application of these experiments to BIF formation has been hindered by the lack of Fe isotope data from modern environments that are analogous to BIFs. Here we report Fe inventories and isotopic compositions for chemically precipitated sediments in the Spring Creek Arm of Keswick Reservoir (SCAKR) downstream of the Iron Mountain acid mine drainage site in northern California, USA. The high concentration of reactive Fe(III) (ca. 50-100 mmol of amorphous Fe(III) oxyhydroxides per liter of bulk sediment) allows dissimilatory iron-reducing bacteria (DIRB) to predominate over dissimilatory sulfate-reducing bacteria in sediment carbon metabolism, making the SCAKR a better analog for BIFs compared to modern marine environments. DIR has generated millimolar concentrations of aqueous Fe(II) (Fe(II)aq) in SCAKR sediments. The Fe(II)aq has lower 56Fe/54Fe values than bulk HCl-extractable Fe; δ56Fe values for bulk HCl-extractable Fe fall within the range previously defined for mafic- to intermediate-composition terrestrial igneous rocks, modern marine sediments, suspended river sediments, Proterozoic-Phanerozoic shales, loess, aerosols, and soils. After removal of pore fluid, sediment was reacted for 1 hr with 0.1M HCl to isolate solid-phase Fe(II) (Fe(II)s), which was likely a mixture of sorbed Fe(II) and amorphous surface-precipitated Fe(II) hydroxide. Subsequent 24-hr extraction with 0.5M HCl recovered amorphous Fe(III) oxide (Fe(III)am). Sediment incubation experiments with SCAKR sediment produced trends in in Fe isotopic fractionations between Fe(II)aq, Fe(II)s, and Fe(III)am analogous to those observed in situ. Collectively the data suggest an equilibrium 56Fe/54Fe isotope fractionation between Fe(II)aq and Fe

  3. Relative effectiveness of HZE iron-56 particles for the induction of cytogenetic damage in vivo.

    PubMed

    Brooks, A; Bao, S; Rithidech, K; Couch, L A; Braby, L A

    2001-02-01

    One of the risks of prolonged manned space flight is the exposure of astronauts to radiation from galactic cosmic rays, which contain heavy ions such as (56)Fe. To study the effects of such exposures, experiments were conducted at the Brookhaven National Laboratory by exposing Wistar rats to high-mass, high-Z, high-energy (HZE) particles using the Alternating Gradient Synchrotron (AGS). The biological effectiveness of (56)Fe ions (1000 MeV/nucleon) relative to low-LET gamma rays and high-LET alpha particles for the induction of chromosome damage and micronuclei was determined. The mitotic index and the frequency of chromosome aberrations were evaluated in bone marrow cells, and the frequency of micronuclei was measured in cells isolated from the trachea and the deep lung. A marked delay in the entry of cells into mitosis was induced in the bone marrow cells that decreased as a function of time after the exposure. The frequencies of chromatid aberrations and micronuclei increased as linear functions of dose. The frequency of chromosome aberrations induced by HZE particles was about 3.2 times higher than that observed after exposure to (60)Co gamma rays. The frequency of micronuclei in rat lung fibroblasts, lung epithelial cells, and tracheal epithelial cells increased linearly, with slopes of 7 x 10(-4), 12 x 10(-4), and 11 x 10(-4) micronuclei/binucleated cell cGy(-1), respectively. When genetic damage induced by radiation from (56)Fe ions was compared to that from exposure to (60)Co gamma rays, (56)Fe-ion radiation was between 0.9 and 3.3 times more effective than (60)Co gamma rays. However, the HZE-particle exposures were only 10-20% as effective as radon in producing micronuclei in either deep lung or tracheal epithelial cells. Using microdosimetric techniques, we estimated that 32 cells were hit by delta rays for each cell that was traversed by the primary HZE (56)Fe particle. These calculations and the observed low relative effectiveness of the exposure to HZE

  4. Integrated Fe- and S-isotope study of seafloor hydrothermal vents at East Pacific Rise 9-10°N

    USGS Publications Warehouse

    Rouxel, O.; Shanks, Wayne C.; Bach, W.; Edwards, K.J.

    2008-01-01

    In this study, we report on coupled Fe- and S-isotope systematics of hydrothermal fluids and sulfide deposits from the East Pacific Rise at 9–10°N to better constrain processes affecting Fe-isotope fractionation in hydrothermal environments. We aim to address three fundamental questions: (1) Is there significant Fe-isotope fractionation during sulfide precipitation? (2) Is there significant variability of Fe-isotope composition of the hydrothermal fluids reflecting sulfide precipitation in subsurface environments? (3) Are there any systematics between Fe- and S-isotopes in sulfide minerals? The results show that chalcopyrite, precipitating in the interior wall of a hydrothermal chimney displays a limited range of δ56Fe values and δ34S values, between − 0.11 to − 0.33‰ and 2.2 to 2.6‰ respectively. The δ56Fe values are, on average, slightly higher by 0.14‰ relative to coeval vent fluid composition while δ34S values suggest significant S-isotope fractionation (− 0.6 ± 0.2‰) during chalcopyrite precipitation. In contrast, systematically lower δ56Fe and δ34S values relative to hydrothermal fluids, by up to 0.91‰ and 2.0‰ respectively, are observed in pyrite and marcasite precipitating in the interior of active chimneys. These results suggest isotope disequilibrium in both Fe- and S-isotopes due to S-isotopic exchange between hydrothermal H2S and seawater SO42− followed by rapid formation of pyrite from FeS precursors, thus preserving the effects of a strong kinetic Fe-isotope fractionation during FeS precipitation. In contrast, δ56Fe and δ34S values of pyrite from inactive massive sulfides, which show evidence of extensive late-stage reworking, are essentially similar to the hydrothermal fluids. Multiple stages of remineralization of ancient chimney deposits at the seafloor appear to produce minimal Fe-isotope fractionation. Similar affects are indicated during subsurface sulfide precipitation as demonstrated by the lack of systematic

  5. Relative effectiveness of HZE iron-56 particles for the induction of cytogenetic damage in vivo

    NASA Technical Reports Server (NTRS)

    Brooks, A.; Bao, S.; Rithidech, K.; Couch, L. A.; Braby, L. A.

    2001-01-01

    One of the risks of prolonged manned space flight is the exposure of astronauts to radiation from galactic cosmic rays, which contain heavy ions such as (56)Fe. To study the effects of such exposures, experiments were conducted at the Brookhaven National Laboratory by exposing Wistar rats to high-mass, high-Z, high-energy (HZE) particles using the Alternating Gradient Synchrotron (AGS). The biological effectiveness of (56)Fe ions (1000 MeV/nucleon) relative to low-LET gamma rays and high-LET alpha particles for the induction of chromosome damage and micronuclei was determined. The mitotic index and the frequency of chromosome aberrations were evaluated in bone marrow cells, and the frequency of micronuclei was measured in cells isolated from the trachea and the deep lung. A marked delay in the entry of cells into mitosis was induced in the bone marrow cells that decreased as a function of time after the exposure. The frequencies of chromatid aberrations and micronuclei increased as linear functions of dose. The frequency of chromosome aberrations induced by HZE particles was about 3.2 times higher than that observed after exposure to (60)Co gamma rays. The frequency of micronuclei in rat lung fibroblasts, lung epithelial cells, and tracheal epithelial cells increased linearly, with slopes of 7 x 10(-4), 12 x 10(-4), and 11 x 10(-4) micronuclei/binucleated cell cGy(-1), respectively. When genetic damage induced by radiation from (56)Fe ions was compared to that from exposure to (60)Co gamma rays, (56)Fe-ion radiation was between 0.9 and 3.3 times more effective than (60)Co gamma rays. However, the HZE-particle exposures were only 10-20% as effective as radon in producing micronuclei in either deep lung or tracheal epithelial cells. Using microdosimetric techniques, we estimated that 32 cells were hit by delta rays for each cell that was traversed by the primary HZE (56)Fe particle. These calculations and the observed low relative effectiveness of the exposure to HZE

  6. Iron isotopes in an Archean ocean analogue

    NASA Astrophysics Data System (ADS)

    Busigny, Vincent; Planavsky, Noah J.; Jézéquel, Didier; Crowe, Sean; Louvat, Pascale; Moureau, Julien; Viollier, Eric; Lyons, Timothy W.

    2014-05-01

    Iron isotopes have been extensively used to trace the history of microbial metabolisms and the redox evolution of the oceans. Archean sedimentary rocks display greater variability in iron isotope ratios and more markedly negative values than those deposited in the Proterozoic and Phanerozoic. This increased variability has been linked to changes in either water column iron cycling or the extent of benthic microbial iron reduction through time. We tested these contrasting scenarios through a detailed study of anoxic and ferruginous Lac Pavin (France), which can serve as a modern analogue of the Archean ocean. A depth-profile in the water column of Lac Pavin shows a remarkable increase in dissolved Fe concentration (0.1-1200 μM) and δ56Fe values (-2.14‰ to +0.31‰) across the oxic-anoxic boundary to the lake bottom. The largest Fe isotope variability is found at the redox boundary and is related to partial oxidation of dissolved ferrous iron, leaving the residual Fe enriched in light isotopes. The analysis of four sediment cores collected along a lateral profile (one in the oxic layer, one at the redox boundary, one in the anoxic zone, and one at the bottom of the lake) indicates that bulk sediments, porewaters, and reactive Fe mostly have δ56Fe values near 0.0 ± 0.2‰, similar to detrital iron. In contrast, pyrite δ56Fe values in sub-chemocline cores (60, 65, and 92 m) are highly variable and show significant deviations from the detrital iron isotope composition (δ56Fepyrite between -1.51‰ and +0.09‰; average -0.93‰). Importantly, the pyrite δ56Fe values mirror the δ56Fe of dissolved iron at the redox boundary—where near quantitative sulfate and sulfide drawdown occurs—suggesting limited iron isotope fractionation during iron sulfide formation. This finding has important implications for the Archean environment. Specifically, this work suggests that in a ferruginous system, most of the Fe isotope variability observed in sedimentary pyrites can

  7. Iron, zinc, magnesium and uranium isotopic fractionation during continental crust differentiation: The tale from migmatites, granitoids, and pegmatites

    NASA Astrophysics Data System (ADS)

    Telus, Myriam; Dauphas, Nicolas; Moynier, Frédéric; Tissot, François L. H.; Teng, Fang-Zhen; Nabelek, Peter I.; Craddock, Paul R.; Groat, Lee A.

    2012-11-01

    The causes of some stable isotopic variations in felsic rocks are not well understood. In particular, the origin of the heavy Fe isotopic compositions (i.e., high δ56Fe values, deviation in ‰ of the 56Fe/54Fe ratio relative to IRMM-014) of granites with SiO2 > 70 wt.% compared with less silicic rocks is still debated. It has been interpreted to reflect isotopic fractionation during late stage aqueous fluid exsolution, magma differentiation, partial melting, or Soret (thermal) diffusion. The present study addresses this issue by comparing the Fe isotopic compositions of a large range of differentiated crustal rocks (whole rocks of migmatites, granitoids, and pegmatites; mineral separates) with the isotopic compositions of Zn, Mg and U. The samples include granites, migmatites and pegmatites from the Black Hills, South Dakota (USA), as well as I-, S-, and A-type granitoids from Lachlan Fold Belt (Australia). The nature of the protolith (i.e., I- or S-type) does not influence the Fe isotopic composition of granitoids. Leucosomes (partial melts in migmatites) tend to have higher δ56Fe values than melanosomes (melt residues) indicating that partial melting of continental crust material can possibly fractionate Fe isotopes. No clear positive correlation is found between the isotopic compositions of Mg, U and Fe, which rules out the process of Soret diffusion in the systems studied here. Zinc isotopes were measured to trace fluid exsolution because Zn can easily be mobilized by aqueous fluids as chloride complexes. Pegmatites and some granitic rocks with high δ56Fe values also have high δ66Zn values. In addition, high-SiO2 granites show a large dispersion in the Zn/Fe ratio that cannot easily be explained by magma differentiation alone. These results suggest that fluid exsolution is responsible for some of the Fe isotopic fractionation documented in felsic rocks and in particular in pegmatites. However, some granites with high δ56Fe values have unfractionated δ66

  8. Tracing the secular evolution of the UCC using the iron isotope composition of ancient glacial diamictites

    NASA Astrophysics Data System (ADS)

    Liu, X. M.; Gaschnig, R. M.; Rudnick, R. L.; Hazen, R. M.; Shahar, A.

    2015-12-01

    Iron is the fourth most abundant element in the continental crust and influences global climate and biogeochemical cycles in the ocean1. Continental inputs, including river waters, sediments and atmospheric dust are dominant sources (>95%) of iron into the ocean2. Therefore, understanding how continental inputs may have changed through time is important in understanding the secular evolution of the marine Fe cycle. We analysed the Fe isotopic composition of twenty-four glacial diamictite composites, upper continental crust (UCC) proxies, with ages ranging from the Mesoarchean to the Paleozoic eras to characterize the secular evolution of the UCC. The diamictites all have elevated chemical index of alteration (CIA) and other characteristics of weathered regolith (e.g., strong depletion in soluble elements such as Sr), which they inherited from their upper crustal source region3. δ56Fe in the diamictite composites range from -0.59 to +0.23‰, however, most diamictites cluster with an average δ56Fe of 0.11± 0.20 (2s), overlapping juvenile continental material such as island arc basalts (IABs), which show a narrow range in δ56Fe from -0.04 to +0.14 ‰4. There is no obvious correlation between δ56Fe of the glacial diamictites and the CIA, except that the diamictite with the lowest δ56Fe at -0.59 ‰ also has the highest CIA = 89 (the Paleoproterozoic Makganyene Fm.). The data suggest that the Fe isotope compositions in the upper continental crust did not vary throughout Earth history. Interestingly, chemical weathering and sedimentary transport likely play only a minor role in producing Fe isotope variations in the upper continental crust. Anoxic weathering pre-GOE (Great Oxidation Event) does not seem to generate different Fe isotopic signatures from the post-GOE oxidative weathering environment in the upper continental crust. Therefore, large Fe isotopic fractionations observed in various marine sedimentary records are likely due to other processes occurring

  9. Tracing the secular evolution of the UCC using the iron isotope composition of ancient glacial diamictites

    NASA Astrophysics Data System (ADS)

    Liu, X. M.; Gaschnig, R. M.; Rudnick, R. L.; Hazen, R. M.; Shahar, A.

    2014-12-01

    Iron is the fourth most abundant element in the continental crust and influences global climate and biogeochemical cycles in the ocean1. Continental inputs, including river waters, sediments and atmospheric dust are dominant sources (>95%) of iron into the ocean2. Therefore, understanding how continental inputs may have changed through time is important in understanding the secular evolution of the marine Fe cycle. We analysed the Fe isotopic composition of twenty-four glacial diamictite composites, upper continental crust (UCC) proxies, with ages ranging from the Mesoarchean to the Paleozoic eras to characterize the secular evolution of the UCC. The diamictites all have elevated chemical index of alteration (CIA) and other characteristics of weathered regolith (e.g., strong depletion in soluble elements such as Sr), which they inherited from their upper crustal source region3. δ56Fe in the diamictite composites range from -0.59 to +0.23‰, however, most diamictites cluster with an average δ56Fe of 0.11± 0.20 (2s), overlapping juvenile continental material such as island arc basalts (IABs), which show a narrow range in δ56Fe from -0.04 to +0.14 ‰4. There is no obvious correlation between δ56Fe of the glacial diamictites and the CIA, except that the diamictite with the lowest δ56Fe at -0.59 ‰ also has the highest CIA = 89 (the Paleoproterozoic Makganyene Fm.). The data suggest that the Fe isotope compositions in the upper continental crust did not vary throughout Earth history. Interestingly, chemical weathering and sedimentary transport likely play only a minor role in producing Fe isotope variations in the upper continental crust. Anoxic weathering pre-GOE (Great Oxidation Event) does not seem to generate different Fe isotopic signatures from the post-GOE oxidative weathering environment in the upper continental crust. Therefore, large Fe isotopic fractionations observed in various marine sedimentary records are likely due to other processes occurring

  10. Iron and magnesium isotopic constraints on the origin of chemical heterogeneity in podiform chromitite from the Luobusa ophiolite, Tibet

    NASA Astrophysics Data System (ADS)

    Xiao, Yan; Teng, Fang-Zhen; Su, Ben-Xun; Hu, Yan; Zhou, Mei-Fu; Zhu, Bin; Shi, Ren-Deng; Huang, Qi-Shuai; Gong, Xiao-Han; He, Yong-Sheng

    2016-03-01

    We present high-precision measurements of iron (Fe) and magnesium (Mg) isotopic compositions of olivine, orthopyroxene, and chromite separates from harzburgites, dunites, and chromitites in the mantle section of the Luobusa ophiolite, southern Tibet, to investigate the origins of podiform chromitite. Two harzburgites in the Zedong ophiolite, southern Tibet, are also reported for comparison. The olivine and orthopyroxene in the Luobusa and Zedong harzburgites have similar Fe and Mg isotopic compositions, with δ56Fe values ranging from 0‰ to +0.083‰ in olivine, from -0.034‰ to +0.081‰ in orthopyroxene and δ26Mg values ranging from -0.25‰ to -0.20‰ in olivine, from -0.29‰ to -0.26‰ in orthopyroxene, respectively. The olivines of two dunites from the Luobusa display small Fe and Mg isotopic variations, with δ56Fe values of +0.014‰ and +0.116‰ and δ26Mg values of -0.21‰ and -0.29‰. All chromites in the Luobusa chromitites have lighter Fe isotopic compositions than the coexisting olivines, with δ56Fe values ranging from -0.247‰ to +0.043‰ in chromite and from -0.146‰ to +0.215‰ in olivine (Δ56FeChr-Ol = -0.294 to -0.101‰). The chromite δ26Mg values span a significant range from -0.41‰ to +0.14‰. Large disequilibrium Fe and Mg isotope fractionation between chromite and olivine, as well as positive correlation of chromite δ56Fe values with their MgO contents, could be attributed to Fe-Mg exchange between chromite and olivine. In the disseminated chromitites, the higher modal abundances of olivine than chromite would result in a more extensive Fe-Mg exchange, whereas chromite in the massive chromitite where olivine is rare could not be affected by this process.

  11. Isotopic evidence for primordial molecular cloud material in metal-rich carbonaceous chondrites

    PubMed Central

    Van Kooten, Elishevah M. M. E.; Wielandt, Daniel; Schiller, Martin; Nagashima, Kazuhide; Thomen, Aurélien; Olsen, Mia B.; Nordlund, Åke; Krot, Alexander N.; Bizzarro, Martin

    2016-01-01

    The short-lived 26Al radionuclide is thought to have been admixed into the initially 26Al-poor protosolar molecular cloud before or contemporaneously with its collapse. Bulk inner Solar System reservoirs record positively correlated variability in mass-independent 54Cr and 26Mg*, the decay product of 26Al. This correlation is interpreted as reflecting progressive thermal processing of in-falling 26Al-rich molecular cloud material in the inner Solar System. The thermally unprocessed molecular cloud matter reflecting the nucleosynthetic makeup of the molecular cloud before the last addition of stellar-derived 26Al has not been identified yet but may be preserved in planetesimals that accreted in the outer Solar System. We show that metal-rich carbonaceous chondrites and their components have a unique isotopic signature extending from an inner Solar System composition toward a 26Mg*-depleted and 54Cr-enriched component. This composition is consistent with that expected for thermally unprocessed primordial molecular cloud material before its pollution by stellar-derived 26Al. The 26Mg* and 54Cr compositions of bulk metal-rich chondrites require significant amounts (25–50%) of primordial molecular cloud matter in their precursor material. Given that such high fractions of primordial molecular cloud material are expected to survive only in the outer Solar System, we infer that, similarly to cometary bodies, metal-rich carbonaceous chondrites are samples of planetesimals that accreted beyond the orbits of the gas giants. The lack of evidence for this material in other chondrite groups requires isolation from the outer Solar System, possibly by the opening of disk gaps from the early formation of gas giants. PMID:26858438

  12. Isotopic evidence for primordial molecular cloud material in metal-rich carbonaceous chondrites.

    PubMed

    Van Kooten, Elishevah M M E; Wielandt, Daniel; Schiller, Martin; Nagashima, Kazuhide; Thomen, Aurélien; Larsen, Kirsten K; Olsen, Mia B; Nordlund, Åke; Krot, Alexander N; Bizzarro, Martin

    2016-02-23

    The short-lived (26)Al radionuclide is thought to have been admixed into the initially (26)Al-poor protosolar molecular cloud before or contemporaneously with its collapse. Bulk inner Solar System reservoirs record positively correlated variability in mass-independent (54)Cr and (26)Mg*, the decay product of (26)Al. This correlation is interpreted as reflecting progressive thermal processing of in-falling (26)Al-rich molecular cloud material in the inner Solar System. The thermally unprocessed molecular cloud matter reflecting the nucleosynthetic makeup of the molecular cloud before the last addition of stellar-derived (26)Al has not been identified yet but may be preserved in planetesimals that accreted in the outer Solar System. We show that metal-rich carbonaceous chondrites and their components have a unique isotopic signature extending from an inner Solar System composition toward a (26)Mg*-depleted and (54)Cr-enriched component. This composition is consistent with that expected for thermally unprocessed primordial molecular cloud material before its pollution by stellar-derived (26)Al. The (26)Mg* and (54)Cr compositions of bulk metal-rich chondrites require significant amounts (25-50%) of primordial molecular cloud matter in their precursor material. Given that such high fractions of primordial molecular cloud material are expected to survive only in the outer Solar System, we infer that, similarly to cometary bodies, metal-rich carbonaceous chondrites are samples of planetesimals that accreted beyond the orbits of the gas giants. The lack of evidence for this material in other chondrite groups requires isolation from the outer Solar System, possibly by the opening of disk gaps from the early formation of gas giants.

  13. The isotopic signature and distribution of particulate iron in the North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Revels, Brandi N.; Ohnemus, Daniel C.; Lam, Phoebe J.; Conway, Tim M.; John, Seth G.

    2015-06-01

    Iron (Fe) is a key micronutrient for life in the oceans. Particles play an important role in the marine biogeochemical cycling of Fe as a reservoir of marine Fe that may be directly accessible to phytoplankton, and as sources and sinks for seawater dissolved Fe. Here, we report the stable isotopic composition of Fe (δ56Fe) in suspended (0.8-51 μm) particles from the US GEOTRACES GA03 North Atlantic zonal transect, in order to facilitate a better understanding of the marine biogeochemical cycling of Fe. Data are presented both for a total digestion of the particles, and for 'ligand-leachable' phases of Fe using a newly-developed pH 8 oxalate-EDTA leach. For total particle digests, the mean δ56Fe across the whole GA03 section was 0.08±0.09‰ (1 S.D.) which is equivalent to the isotope composition of known lithogenic Fe sources to the ocean. In contrast, ligand-leachable Fe was generally lighter than continental material with a mean δ56Fe of -0.30±0.17‰ (1 S.D.). Our data also provide valuable insight into Fe biogeochemical cycling in several key regions. In the deep ocean, but above the depths where near-sediment nephloid layers are present, ligand-leachable Fe is isotopically lighter in the deep Western Basin compared to the deep Central and Eastern Basins suggesting differences in particle surface chemistry between resuspended seafloor sediments, which may predominate in the west, and Saharan dust that predominates in the center and in the east. Within a nephloid layer above reduced continental margin sediments in the Eastern Basin, below the Mauritanian upwelling region, we report the lowest particulate δ56Fe values for both total and ligand-leachable Fe, suggesting a transfer of isotopically light dissolved porewater Fe2+ to the particulate phase. In contrast, δ56Fe values within a nephloid layer near Bermuda are similar to values higher in the water column. Within a hydrothermal plume sampled at the TAG hydrothermal field on the mid-Atlantic Ridge

  14. Nuclear structure studies in the seaborgium region at SHIP

    NASA Astrophysics Data System (ADS)

    Antalic, S.; Heßberger, F. P.; Andel, B.; Ackermann, D.; Heinz, S.; Hofmann, S.; Kalaninová, Z.; Kindler, B.; Khuyagbaatar, J.; Laatiaoui, M.; Lommel, B.; Piot, J.; Vostinar, M.

    2015-10-01

    New decay data for the isotopes 259Sg and 255Rf were obtained at the velocity filter SHIP using an α-decay spectroscopy measurement. Both isotopes were produced and studied via a one neutron evaporation channel in the compound fusion reaction 54Cr+208Pb. New isomeric states were observed and the single-particle level systematics for isotones with 151 and 153 neutrons were extended. A change of the ground-state configuration for the heaviest N = 151 isotones was observed. Detailed Monte-Carlo simulation for the α decay of 259Sg applying the Geant4 toolkit was performed and compared with experimental data.

  15. Nuclear structure studies in the seaborgium region at SHIP

    SciTech Connect

    Antalic, S. Andel, B.; Heßberger, F. P.; Khuyagbaatar, J.; Ackermann, D.; Heinz, S.; Hofmann, S.; Kindler, B.; Laatiaoui, M.; Lommel, B.; Kalaninová, Z.; Piot, J.; Vostinar, M.

    2015-10-15

    New decay data for the isotopes {sup 259}Sg and {sup 255}Rf were obtained at the velocity filter SHIP using an α-decay spectroscopy measurement. Both isotopes were produced and studied via a one neutron evaporation channel in the compound fusion reaction {sup 54}Cr+{sup 208}Pb. New isomeric states were observed and the single-particle level systematics for isotones with 151 and 153 neutrons were extended. A change of the ground-state configuration for the heaviest N = 151 isotones was observed. Detailed Monte-Carlo simulation for the α decay of {sup 259}Sg applying the GEANT4 toolkit was performed and compared with experimental data.

  16. Precise measurement of chromium isotopes by MC-ICPMS

    PubMed Central

    Schiller, Martin; Van Kooten, Elishevah; Holst, Jesper C.; Olsen, Mia B.; Bizzarro, Martin

    2014-01-01

    We report novel analytical procedures allowing for the concurrent determination of the stable and mass-independent Cr isotopic composition of silicate materials by multiple collector inductively coupled mass spectrometry (MC-ICPMS). In particular, we focus on improved precision of the measurement of the neutron-rich isotope 54Cr. Because nitride and oxide interferences are a major obstacle to precise and accurate 54Cr measurements by MC-ICPMS, our approach is designed to minimize these interferences. Based on repeat measurements of standards, we show that the mass-independent 53Cr and 54Cr compositions can be routinely determined with an external reproducibility better than 2.5 and 5.8 ppm (2 sd), respectively. This represents at least a two-fold improvement compared to previous studies. Although this approach uses significantly more Cr (30–60 μg) than analysis by thermal ionization mass spectrometry (TIMS), our result indicate that it is possible to obtain an external reproducibility of 19 ppm for the μ54Cr when consuming amounts similar to that typically analyzed by TIMS (1 μg). In addition, the amount of time required for analysis by MC-ICPMS is much shorter thereby enabling a higher sample throughput. As a result of the improved analytical precision, we identified small apparent mass-independent differences between different synthetic Cr standards and bulk silicate Earth (BSE) when using the kinetic law for the mass bias correction. These differences are attributed to the Cr loss by equilibrium processes during production of the synthetic standards. The stable isotope data concurrently obtained have a precision of 0.05‰ Da −1, which is comparable to earlier studies. Comparison of the measured isotopic composition of four meteorites with published data indicates that Cr isotope data measured by the technique described here are accurate to stated uncertainties. The stable Cr composition of the Bilanga and NWA 2999 achondrites suggests that the

  17. {sup 53}Mn-{sup 53}Cr CHRONOMETRY OF CB CHONDRITE: EVIDENCE FOR UNIFORM DISTRIBUTION OF {sup 53}Mn IN THE EARLY SOLAR SYSTEM

    SciTech Connect

    Yamashita, Katsuyuki; Yamakawa, Akane; Nakamura, Eizo; Maruyama, Seiji

    2010-11-01

    High-precision Cr isotope ratios for chondrules and metal grain separated from CB chondrite Gujba were determined. The {epsilon}{sup 54}Cr values ({epsilon}{sup i}Cr = [({sup i}Cr/{sup 52}Cr){sub sample}/({sup i}Cr/{sup 52}Cr){sub standard} - 1] x 10{sup 4}) for all samples were identical within the analytical uncertainty, with a mean value of +1.29 {+-} 0.02. Uniform {epsilon}{sup 54}Cr signatures of both chondrules and metal grains imply that the Cr isotope systematics of the meteorite was once completely equilibrated. The {epsilon}{sup 53}Cr values of the chondrules and metal grain, on the other hand, display a strong correlation with the {sup 55}Mn/{sup 52}Cr ratio. The {sup 53}Mn/{sup 55}Mn calculated from the slope of the isochron is (3.18 {+-} 0.52) x 10{sup -6}. This corresponds to absolute ages of 4563.7 {+-} 1.2 Ma and 4563.5 {+-} 1.1 Ma using angrites D'Orbigny and LEW 86010, respectively, as time anchors. These ages are consistent with the ages obtained using other short- and long-lived radio nuclides, supporting the uniform distribution of {sup 53}Mn in the early solar nebula.

  18. Comparison of complementary reactions for the production of {sup 261,262}Bh

    SciTech Connect

    Nelson, S. L.; Folden III, C. M.; Dragojevic, I.; Garcia, M. A.; Gates, J. M.; Nitsche, H.; Gregorich, K. E.; Sudowe, R.; Duellmann, Ch. E.; Eichler, R.

    2008-08-15

    Two heavy-ion induced fusion reactions producing {sup 261,262}Bh were studied using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. An excitation function for the production of {sup 262}Bh via the reaction {sup 209}Bi({sup 54}Cr,n){sup 262}Bh was measured with a maximum cross section from a fit to the data of 430 {+-} 110 pb observed at a compound nucleus excitation energy of 15.7 MeV. New data have been measured for the 1n exit channel of the {sup 208}Pb({sup 55}Mn, n){sup 262}Bh reaction. We present an updated excitation function with an observed maximum cross section of 530{+-}100 pb at a compound nucleus excitation energy of 14.1 MeV. Events corresponding to the 2n exit channel for the {sup 209}Bi({sup 54}Cr,2n){sup 261}Bh and {sup 208}Pb({sup 55}Mn,2n){sup 261}Bh reactions were also observed and are presented as partial excitation functions. The measured decay properties correspond well with existing experimental data. We compare these experimental results to cross section predictions from a model by Swiatecki et al. and discuss entrance channel effects on the magnitude of 1n cross sections.

  19. Transition from quasi-elastic to deep-inelastic reactions

    SciTech Connect

    Rehm, K.E.

    1986-01-01

    Heavy ion induced transfer reactions are usually considered to fall into two categories. Quasi-elastic processes, on one hand, are characterized by small energy transfers, with one-nucleon transfer reactions being a typical example. These processes are dominant for grazing collisions, and are generally described within simple one-step DWBA calculations. Deep inelastic reactions, on the other hand, occur for more central collisions where the interaction time is longer and subsequently more energy and particles can be exchanged. Quasi-elastic collisions dominate transfer reactions induced by light heavy ions (e.g., /sup 16/O) at energies not too high above the barrier, while deep inelastic collisions are observed mainly in reactions induced by heavier projectiles (Kr, Xe). In this contribution, we discuss the transition between these two processes for the system /sup 48/Ti + /sup 208/Pb. /sup 48/Ti is located between light (/sup 16/O) and heavy (Kr) projectiles and should be well suited for a study of the interrelation between quasi- and deep-inelastic reactions. The experiments were performed with a 300 MeV /sup 48/Ti beam obtained from the Argonne National Laboratory superconducting linac. The outgoing particles were momentum analyzed in a split pole magnetic spectrograph and detected in the focal plane by a position sensitive ionization chamber. The specific energy loss, the magnetic rigidity and the total energy of the outgoing particles were measured enabling mass and Z-identification. The energy resolution was about 3 MeV, determined by the thickness of the /sup 208/Pb target, and thus excluded study of transfer reactions to discrete final states. Angular distributions were measured in the range theta/sub lab/ = 20/sup 0/ to 80/sup 0/ in steps of 5/sup 0/. 8 refs.

  20. The cycling of iron, zinc and cadmium in the North East Pacific Ocean - Insights from stable isotopes

    NASA Astrophysics Data System (ADS)

    Conway, Tim M.; John, Seth G.

    2015-09-01

    Dissolved stable isotope ratios of the transition metals provide useful information, both for understanding the cycling of these bioactive trace elements through the oceans, and tracing their marine sources and sinks. Here, we present seawater dissolved Fe, Zn and Cd concentration and stable isotope ratio (δ56Fe, δ66Zn, and δ114Cd) profiles from two stations in the Pacific Ocean, the SAFe Station (30°N 140°W) in the subtropical North East Pacific from the GEOTRACES IC2 cruise, and the marginal San Pedro Basin (33.8°N 118.4°W) within the South California Bight. These data represent, to our knowledge, the first full-water column profiles for δ66Zn and δ56Fe from the open-ocean North Pacific, and the first observations of dissolved δ66Zn and δ114Cd in a low-oxygen marginal basin. At the SAFe station, δ56Fe is isotopically lighter throughout the water column (-0.6 to +0.1‰, relative to IRRM-014) compared to the North Atlantic, suggesting significant differences in Fe sources or Fe cycling between these two ocean basins. A broad minimum in δ56Fe associated with the North Pacific oxygen minimum zone (OMZ; <75 μmol kg-1 dissolved oxygen; ∼550-2000 m depth) is consistent with reductive sediments along the California margin being an important source of dissolved Fe to the North Pacific. Other processes which may influence δ56Fe at SAFe include biological cycling in the upper ocean, and input of Fe from hydrothermal vents and oxic sediments below the OMZ. Zn and Cd concentration profiles at both stations broadly match the distribution of the macronutrients silicate and phosphate, respectively. At SAFe, δ114Cd increases towards the surface, reflecting the biological preference for assimilation of lighter Cd isotopes, while negative Cd∗ (-0.12) associated with low oxygen waters supports the recently proposed hypothesis of water-column CdS precipitation. In contrast to δ114Cd, δ66Zn at SAFe decreases towards the surface ocean, perhaps due to scavenging

  1. Stable iron isotopes - a tool for investigating the fate of organo-mineral associations

    NASA Astrophysics Data System (ADS)

    Fekiacova, Z.; Pichat, S.; Cornu, S.; Balesdent, J.

    2011-12-01

    Organo-mineral associations form one of the most important reservoirs of organic matter in soil [e.g., 1]. They play an important role in major environmental processes such as atmospheric-CO2 control and soil degradation via erosion. They are also the most fragile soil constituents and react rapidly in response to changes in temperature and water content or to modifications induced by human activity. The mineral part of the organo-mineral associations plays a key role in physical protection of organic matter before degradation. In this work we use stable iron isotopes to examine the behavior of iron linked to the organo-mineral associations. Our samples were collected from the surface horizon of soils characterized by distinct climatic histories and different land uses: Ferralsol (Eucalyptus tree plantation), Podzol (Maritime pine forest), Cambisol (Maize crops), Rendzina (Oak forest) and Luvisol (uncultivated prairie). We have performed particle-size fractionation by wet-sieving [2] to separate 200-2000 μm, 50-200 μm and 20-50 μm fractions (further labelled as 200, 50 and 20). For each particle-size fraction, we separated the light-density organic phase from the mineral phase by differential sedimentation in water (labelled V and M, respectively). We have analyzed C and Fe contents and C and Fe isotopic compositions in each fraction. Carbon content in mineral fractions is negligible. Therefore in this study, we focus on the organic-matter enriched V-fractions. For all studied soil types, the coarse particle-size fractions (V200) have higher C and lower Fe content than the fine particle-size fractions (V50, V20). In terms of isotopic compositions, there are differences in δ13C signatures among the different soils, which correspond to the C3 or C4 origin of the existing vegetation. The iron isotopic compositions show an overall variation up to 0.71 % in δ56Fe56Fe = [(56Fe/54Fe)sample/(56Fe/54Fe)std -1] × 103). With one exception showing little overall

  2. Fractionation of iron isotopes during leaching of natural particles by acidic and circumneutral leaches and development of an optimal leach for marine particulate iron isotopes

    NASA Astrophysics Data System (ADS)

    Revels, Brandi N.; Zhang, Ruifeng; Adkins, Jess F.; John, Seth G.

    2015-10-01

    Iron (Fe) is an essential nutrient for life on land and in the oceans. Iron stable isotope ratios (δ56Fe) can be used to study the biogeochemical cycling of Fe between particulate and dissolved phases in terrestrial and marine environments. We have investigated the dissolution of Fe from natural particles both to understand the mechanisms of Fe dissolution, and to choose a leach appropriate for extracting labile Fe phases of marine particles. With a goal of finding leaches which would be appropriate for studying dissolved-particle interactions in an oxic water column, three particle types were chosen including oxic seafloor sediments (MESS-3), terrestrial dust (Arizona Test Dust - A2 Fine), and ocean sediment trap material from the Cariaco basin. Four leaches were tested, including three acidic leaches similar to leaches previously applied to marine particles and sediments (25% acetic acid, 0.01 N HCl, and 0.5 N HCl) and a pH 8 oxalate-EDTA leach meant to mimic the dissolution of particles by organic complexation, as occurs in natural seawater. Each leach was applied for three different times (10 min, 2 h, 24 h) at three different temperatures (25 °C, 60 °C, 90 °C). MESS-3 was also leached under various redox conditions (0.02 M hydroxylamine hydrochloride or 0.02 M hydrogen peroxide). For all three sample types tested, we find a consistent relationship between the amount of Fe leached and leachate δ56Fe for all of the acidic leaches, and a different relationship between the amount of Fe leached and leachate δ56Fe for the oxalate-EDTA leach, suggesting that Fe was released through proton-promoted dissolution for all acidic leaches and by ligand-promoted dissolution for the oxalate-EDTA leach. Fe isotope fractionations of up to 2‰ were observed during acidic leaching of MESS-3 and Cariaco sediment trap material, but not for Arizona Test Dust, suggesting that sample composition influences fractionation, perhaps because Fe isotopes are greatly fractionated

  3. Simulated Space Radiation: Murine Skeletal Responses During Recovery and with Mechanical Stimulation

    NASA Technical Reports Server (NTRS)

    Shirazi-Fard, Yasaman; Zaragoza, Josergio; Schreurs, Ann-Sofie; Truong, Tiffany; Tahimic, Candice; Alwood, Joshua S.; Globus, R. K.

    2016-01-01

    Simulated space radiation at doses similar to those of solar particle events or a round-trip sojourn to Mars (1-2Gy) may cause skeletal tissue degradation and deplete stem/progenitor cell pools throughout the body. We hypothesized that simulated space radiation (SSR) causes late, time-dependent deficits in bone structure and bone cell function reflected by changes in gene expression in response to anabolic stimuli. We used a unique sequential dual ion exposure (proton and iron) for SSR to investigate time-dependence of responses in gene expression, cell function, and microarchitecture with respect to radiation and an anabolic stimulus of axial loading (AL). Male 16-wk C57BL6/J mice (n=120 total) were exposed to 0Gy (Sham, n=10), 56Fe (2Gy, positive control dose, n=10), or sequential ions for SSR (1Gy 1H/56Fe/1H, n=10) by total body irradiation (IR), and the tissues were harvested 2 or 6 mo. later. Further, to assess the response to anabolic stimuli, we subjected additional Sham-AL (n=15) and SSR-AL (n=15) groups to rest-inserted tibial axial loading (AL) starting at 1 and 5 months post-IR (-9N, 60 cycles/day, 3 days/wk, 4 wks). Exposure to 56Fe caused a significant reduction in cancellous bone volume fraction (BV/TV) compared to Sham (-34%) and SSR (-20%) in the proximal tibia metaphysis at 2-months post-IR; however BV/TV for SSR group was not different than Sham. Both 56Fe and SSR caused significant reduction in trabecular number (Tb.N) compared to Sham (-33% and -16%, respectively). Further, Tb.N for 56Fe (2Gy) was significantly lower than SSR (-21%). Ex vivo culture of marrow cells to assess growth and differentiation of osteoblast lineage cells 6 months post-IR showed that both 56Fe and SSR exposures significantly impaired colony formation compared to Sham (-66% and -54%, respectively), as well as nodule mineralization (-90% and -51%, respectively). Two-way analysis of variance showed that both mechanical loading and radiation reduced BV/TV, mechanical loading

  4. Simulated Space Radiation: Murine Skeletal Responses During Recovery and with Mechanical Stimulation

    NASA Technical Reports Server (NTRS)

    Shirazi-Fard, Yasaman; Zaragoza, Josergio; Schreurs, Ann-Sofie; Truong, Tiffany; Tahimic, Candice; Alwood, Joshua S.; Castillo, Alesha B.; Globus, R. K.

    2016-01-01

    Simulated space radiation at doses similar to those of solar particle events or a round-trip sojourn to Mars (1-2Gy) may cause skeletal tissue degradation and deplete stem/progenitor cell pools throughout the body. We hypothesized that simulated space radiation (SSR) causes late, time-dependent deficits in bone structure and bone cell function reflected by changes in gene expression in response to anabolic stimuli. We used a unique sequential dual ion exposure (proton and iron) for SSR to investigate time-dependence of responses in gene expression, cell function, and microarchitecture with respect to radiation and an anabolic stimulus of axial loading (AL). Male 16-wk C57BL6/J mice (n=120 total) were exposed to 0Gy (Sham, n=10), 56Fe (2Gy, positive control dose, n=10), or sequential ions for SSR (1Gy 1H/56Fe/1H, n=10) by total body irradiation (IR), and the tissues were harvested 2 or 6 mo. later. Further, to assess the response to anabolic stimuli, we subjected additional Sham-AL (n=15) and SSR-AL (n=15) groups to rest-inserted tibial axial loading (AL) starting at 1 and 5 months post-IR (-9N, 60 cycles/day, 3 days/wk, 4 wks). Exposure to 56Fe caused a significant reduction in cancellous bone volume fraction (BV/TV) compared to Sham (-34%) and SSR (-20%) in the proximal tibia metaphysis at 2-months post-IR; however BV/TV for SSR group was not different than Sham. Both 56Fe and SSR caused significant reduction in trabecular number (Tb.N) compared to Sham (-33% and -16%, respectively). Further, Tb.N for 56Fe (2Gy) was significantly lower than SSR (-21%). Ex vivo culture of marrow cells to assess growth and differentiation of osteoblast lineage cells 6 months post-IR showed that both 56Fe and SSR exposures significantly impaired colony formation compared to Sham (-66% and -54%, respectively), as well as nodule mineralization (-90% and -51%, respectively). Two-way analysis of variance showed that both mechanical loading and radiation reduced BV/TV, mechanical loading

  5. Damping capacity in shape memory alloy honeycomb structures

    NASA Astrophysics Data System (ADS)

    Boucher, M.-A.; Smith, C. W.; Scarpa, F.; Miller, W.; Hassan, M. R.

    2010-04-01

    SMA honeycombs have been recently developed by several Authors [1, 2] as innovative cellular structures with selfhealing capability following mechanical indentation, unusual deformation (negative Poisson's ratio [3]), and possible enhanced damping capacity due to the natural vibration dissipation characteristics of SMAs under pseudoelastic and superelastic regime. In this work we describe the nonlinear damping effects of novel shape memory alloy honeycomb assemblies subjected to combine mechanical sinusoidal and thermal loading. The SMA honeycomb structures made with Ni48Ti46Cu6 are designed with single and two-phase polymeric components (epoxy), to enhance the damping characteristics of the base SMA for broadband frequency vibration.

  6. Excitation-energy dependence of the giant dipole resonance width

    NASA Astrophysics Data System (ADS)

    Enders, G.; Berg, F. D.; Hagel, K.; Kühn, W.; Metag, V.; Novotny, R.; Pfeiffer, M.; Schwalb, O.; Charity, R. J.; Gobbi, A.; Freifelder, R.; Henning, W.; Hildenbrand, K. D.; Holzmann, R.; Mayer, R. S.; Simon, R. S.; Wessels, J. P.; Casini, G.; Olmi, A.; Stefanini, A. A.

    1992-07-01

    High-energy γ rays have been measured in coincidence with heavy fragents in deeply inelastic reactions of 136Xe+48Ti at 18.5 MeV/nucleon. The giant dipole resonance (GDR) strength function is deduced from an analysis of the photon spectra within the statistical model. The GDR width Γ is studied as a function of the fragment excitation energy E*. A saturation at about Γ=10 MeV is observed for E*/A>=1.0 MeV/nucleon.

  7. Zinc isotope anomalies. [In Allende meteorite

    SciTech Connect

    Volkening, J.; Papanastassiou, D.A. )

    1990-07-01

    The Zn isotope composition in refractory-element-rich inclusions of the Allende meteorite are determined. Typical inclusions contain normal Zn. A unique inclusion of the Allende meteorite shows an excess for Zn-66 of 16.7 + or - 3.7 eu (1 eu = 0.01 percent) and a deficit for Zn-70 of 21 + or - 13 eu. These results indicate the preservation of exotic components even for volatile elements in this inclusion. The observed excess Zn-66 correlates with excesses for the neutron-rich isotopes of Ca-48, Ti-50, Cr-54, and Fe-58 in the same inclusion. 32 refs.

  8. Zinc isotope anomalies. [in Allende meteorite

    NASA Technical Reports Server (NTRS)

    Volkening, J.; Papanastassiou, D. A.

    1990-01-01

    The Zn isotope composition in refractory-element-rich inclusions of the Allende meteorite are determined. Typical inclusions contain normal Zn. A unique inclusion of the Allende meteorite shows an excess for Zn-66 of 16.7 + or - 3.7 eu (1 eu = 0.01 percent) and a deficit for Zn-70 of 21 + or - 13 eu. These results indicate the preservation of exotic components even for volatile elements in this inclusion. The observed excess Zn-66 correlates with excesses for the neutron-rich isotopes of Ca-48, Ti-50, Cr-54, and Fe-58 in the same inclusion.

  9. On the possibility to measure 0{nu}{beta}{beta}-decay nuclear matrix element for {sup 48}Ca

    SciTech Connect

    Rodin, Vadim

    2011-12-16

    As shown in Ref. [2], the Fermi part M{sub F}{sup 0{nu}} of the total 0{nu}{beta}{beta}-decay nuclear matrix element M{sup 0{nu}} can be related to the single Fermi transition matrix element between the isobaric analog state (IAS) of the ground state of the initial nucleus and the ground state of the final nucleus. The latter matrix element could be measured in charge-exchange reactions. Here we discuss a possibility of such a measurement for {sup 48}Ca and estimate the cross-section of the reaction {sup 48}Ti(n,p){sup 48}Sc(IAS).

  10. Elevated Temperature, In Situ Micromechanical Characterization of a High Temperature Ternary Shape Memory Alloy

    NASA Astrophysics Data System (ADS)

    Wheeler, J. M.; Niederberger, C.; Raghavan, R.; Thompson, G.; Weaver, M.; Michler, J.

    2015-12-01

    The microthermomechanical behavior of a precipitation-hardenable Ni-48Ti-25Pd (at.%) shape memory alloy has been investigated as a function of temperature. Micropillars were fabricated within a large <145>-oriented grain and compressed in situ in the SEM at elevated temperatures corresponding to the martensite and austenite phase transformation temperatures. The precipitation-strengthened alloys exhibited stable pseudoelastic behavior with little or no residual strains when near the transformation temperatures. In the plastic regime, slip was observed to occur via pencil glide, circumventing the fine scale precipitates along multiple slip planes.

  11. Low-dose radiation affects cardiac physiology: gene networks and molecular signaling in cardiomyocytes.

    PubMed

    Coleman, Matthew A; Sasi, Sharath P; Onufrak, Jillian; Natarajan, Mohan; Manickam, Krishnan; Schwab, John; Muralidharan, Sujatha; Peterson, Leif E; Alekseyev, Yuriy O; Yan, Xinhua; Goukassian, David A

    2015-12-01

    There are 160,000 cancer patients worldwide treated with particle radiotherapy (RT). With the advent of proton, and high (H) charge (Z) and energy (E) HZE ionizing particle RT, the cardiovascular diseases risk estimates are uncertain. In addition, future deep space exploratory-type missions will expose humans to unknown but low doses of particle irradiation (IR). We examined molecular responses using transcriptome profiling in left ventricular murine cardiomyocytes isolated from mice that were exposed to 90 cGy, 1 GeV proton ((1)H) and 15 cGy, 1 GeV/nucleon iron ((56)Fe) over 28 days after exposure. Unsupervised clustering analysis of gene expression segregated samples according to the IR response and time after exposure, with (56)Fe-IR showing the greatest level of gene modulation. (1)H-IR showed little differential transcript modulation. Network analysis categorized the major differentially expressed genes into cell cycle, oxidative responses, and transcriptional regulation functional groups. Transcriptional networks identified key nodes regulating expression. Validation of the signal transduction network by protein analysis and gel shift assay showed that particle IR clearly regulates a long-lived signaling mechanism for ERK1/2, p38 MAPK signaling and identified NFATc4, GATA4, STAT3, and NF-κB as regulators of the response at specific time points. These data suggest that the molecular responses and gene expression to (56)Fe-IR in cardiomyocytes are unique and long-lasting. Our study may have significant implications for the efforts of National Aeronautics and Space Administration to develop heart disease risk estimates for astronauts and for patients receiving conventional and particle RT via identification of specific HZE-IR molecular markers.

  12. Radiation-induced changes in DNA methylation of repetitive elements in the mouse heart.

    PubMed

    Koturbash, Igor; Miousse, Isabelle R; Sridharan, Vijayalakshmi; Nzabarushimana, Etienne; Skinner, Charles M; Melnyk, Stepan B; Pavliv, Oleksandra; Hauer-Jensen, Martin; Nelson, Gregory A; Boerma, Marjan

    2016-05-01

    DNA methylation is a key epigenetic mechanism, needed for proper control over the expression of genetic information and silencing of repetitive elements. Exposure to ionizing radiation, aside from its strong genotoxic potential, may also affect the methylation of DNA, within the repetitive elements, in particular. In this study, we exposed C57BL/6J male mice to low absorbed mean doses of two types of space radiation-proton (0.1 Gy, 150 MeV, dose rate 0.53 ± 0.08 Gy/min), and heavy iron ions ((56)Fe) (0.5 Gy, 600 MeV/n, dose rate 0.38 ± 0.06 Gy/min). Radiation-induced changes in cardiac DNA methylation associated with repetitive elements were detected. Specifically, modest hypomethylation of retrotransposon LINE-1 was observed at day 7 after irradiation with either protons or (56)Fe. This was followed by LINE-1, and other retrotransposons, ERV2 and SINE B1, as well as major satellite DNA hypermethylation at day 90 after irradiation with (56)Fe. These changes in DNA methylation were accompanied by alterations in the expression of DNA methylation machinery and affected the one-carbon metabolism pathway. Furthermore, loss of transposable elements expression was detected in the cardiac tissue at the 90-day time-point, paralleled by substantial accumulation of mRNA transcripts, associated with major satellites. Given that the one-carbon metabolism pathway can be modulated by dietary modifications, these findings suggest a potential strategy for the mitigation and, possibly, prevention of the negative effects exerted by ionizing radiation on the cardiovascular system. Additionally, we show that the methylation status and expression of repetitive elements may serve as early biomarkers of exposure to space radiation.

  13. An anoxic, Fe(II)-rich, U-poor ocean 3.46 billion years ago

    NASA Astrophysics Data System (ADS)

    Li, Weiqiang; Czaja, Andrew D.; Van Kranendonk, Martin J.; Beard, Brian L.; Roden, Eric E.; Johnson, Clark M.

    2013-11-01

    The oxidation state of the atmosphere and oceans on the early Earth remains controversial. Although it is accepted by many workers that the Archean atmosphere and ocean were anoxic, hematite in the 3.46 billion-year-old (Ga) Marble Bar Chert (MBC) from Pilbara Craton, NW Australia has figured prominently in arguments that the Paleoarchean atmosphere and ocean was fully oxygenated. In this study, we report the Fe isotope compositions and U concentrations of the MBC, and show that the samples have extreme heavy Fe isotope enrichment, where δ56Fe values range between +1.5‰ and +2.6‰, the highest δ56Fe values for bulk samples yet reported. The high δ56Fe values of the MBC require very low levels of oxidation and, in addition, point to a Paleoarchean ocean that had high aqueous Fe(II) contents. A dispersion/reaction model indicates that O2 contents in the photic zone of the ocean were less than 10-3 μM, which suggests that the ocean was essentially anoxic. An independent test of anoxic conditions is provided by U-Th-Pb isotope systematics, which show that U contents in the Paleoarchean ocean were likely below 0.02 ppb, two orders-of-magnitude lower than the modern ocean. Collectively, the Fe and U data indicate a reduced, Fe(II)-rich, U-poor environment in the Archean oceans at 3.46 billion years ago. Given the evidence for photosynthetic communities provided by broadly coeval stromatolites, these results suggests that an important photosynthetic pathway in the Paleoarchean oceans may have been anoxygenic photosynthetic Fe(II) oxidation.

  14. Manganese oxide shuttling in pre-GOE oceans - evidence from molybdenum and iron isotopes

    NASA Astrophysics Data System (ADS)

    Kurzweil, Florian; Wille, Martin; Gantert, Niklas; Beukes, Nicolas J.; Schoenberg, Ronny

    2016-10-01

    The local occurrence of oxygen-rich shallow marine water environments has been suggested to significantly predate atmospheric oxygenation, which occurred during the Great Oxidation Event (GOE) ca. 2.4 billion years ago. However, the potential influence of such 'oxygen oases' on the mobility, distribution and isotopic composition of redox sensitive elements remains poorly understood. Here, we provide new molybdenum and iron isotopic data from shallow marine carbonate and silicate iron formations of the Koegas Subgroup, South Africa, that confirm local ocean redox stratification prior to the GOE. Mn concentrations correlate negatively with both δ98 Mo and δ56 Fe values, which highlights the substantial role of particulate manganese for the cycling of Mo and Fe in the Paleoproterozoic oceans. Based on these trends we propose that pore water molybdate was recharged (1) by the diffusional transport of seawater molybdate with high δ98 Mo and (2) by the re-liberation of adsorbed molybdate with low δ98 Mo during Mn oxide dissolution within the sediment. The relative contribution of isotopically light Mo is highest close to a Mn chemocline, where the flux of Mn oxides is largest, causing the negative correlation of Mn concentrations and δ98 Mo values in the Koegas sediments. The negative correlation between δ56 Fe values and Mn concentrations is likely related to Fe isotope fractionation during Fe(II) oxidation by Mn oxides, resulting in lower δ56 Fe values in the uppermost water column close to a Mn chemocline. We argue that the preservation of these signals within Paleoproterozoic sediments implies the existence of vertically extended chemoclines with a smoother gradient, probably as a result of low atmospheric oxygen concentrations. Furthermore, we suggest that abiotic oxidation of Fe(II) by a Mn oxide particle shuttle might have promoted the deposition of the Koegas iron formations.

  15. Total-body irradiation with high-LET particles: acute and chronic effects on the immune system

    NASA Technical Reports Server (NTRS)

    Gridley, Daila S.; Pecaut, Michael J.; Nelson, Gregory A.

    2002-01-01

    Although the immune system is highly susceptible to radiation-induced damage, consequences of high linear energy transfer (LET) radiation remain unclear. This study evaluated the effects of 0.1 gray (Gy), 0.5 Gy, and 2.0 Gy iron ion (56Fe(26)) radiation on lymphoid cells and organs of C57BL/6 mice on days 4 and 113 after whole body exposure; a group irradiated with 2.0 Gy silicon ions (28Si) was euthanized on day 113. On day 4 after 56Fe irradiation, dose-dependent decreases were noted in spleen and thymus masses and all major leukocyte populations in blood and spleen. The CD19(+) B lymphocytes were most radiosensitive and NK1.1(+) natural killer (NK) cells were most resistant. CD3(+) T cells were moderately radiosensitive and a greater loss of CD3(+)/CD8(+) T(C) cells than CD3(+)/CD4(+) T(H) cells was noted. Basal DNA synthesis was elevated on day 4, but response to mitogens and secretion of interleukin-2 and tumor necrosis factor-alpha were unaffected. Signs of anemia were noted. By day 113, high B cell numbers and low T(C) cell and monocyte percents were found in the 2.0 Gy 56Fe group; the 2.0 Gy 2)Si mice had low NK cells, decreased basal DNA synthesis, and a somewhat increased response to two mitogens. Collectively, the data show that lymphoid cells and tissues are markedly affected by high linear energy transfer (LET) radiation at relatively low doses, that some aberrations persist long after exposure, and that different consequences may be induced by various densely ionizing particles. Thus simultaneous exposure to multiple radiation sources could lead to a broader spectrum of immune dysfunction than currently anticipated.

  16. Ionizing Particle Radiation as a Modulator of Endogenous Bone Marrow Cell Reprogramming: Implications for Hematological Cancers.

    PubMed

    Muralidharan, Sujatha; Sasi, Sharath P; Zuriaga, Maria A; Hirschi, Karen K; Porada, Christopher D; Coleman, Matthew A; Walsh, Kenneth X; Yan, Xinhua; Goukassian, David A

    2015-01-01

    Exposure of individuals to ionizing radiation (IR), as in the case of astronauts exploring space or radiotherapy cancer patients, increases their risk of developing secondary cancers and other health-related problems. Bone marrow (BM), the site in the body where hematopoietic stem cell (HSC) self-renewal and differentiation to mature blood cells occurs, is extremely sensitive to low-dose IR, including irradiation by high-charge and high-energy particles. Low-dose IR induces DNA damage and persistent oxidative stress in the BM hematopoietic cells. Inefficient DNA repair processes in HSC and early hematopoietic progenitors can lead to an accumulation of mutations whereas long-lasting oxidative stress can impair hematopoiesis itself, thereby causing long-term damage to hematopoietic cells in the BM niche. We report here that low-dose (1)H- and (56)Fe-IR significantly decreased the hematopoietic early and late multipotent progenitor (E- and L-MPP, respectively) cell numbers in mouse BM over a period of up to 10 months after exposure. Both (1)H- and (56)Fe-IR increased the expression of pluripotent stem cell markers Sox2, Nanog, and Oct4 in L-MPPs and 10 months post-IR exposure. We postulate that low doses of (1)H- and (56)Fe-IR may induce endogenous cellular reprogramming of BM hematopoietic progenitor cells to assume a more primitive pluripotent phenotype and that IR-induced oxidative DNA damage may lead to mutations in these BM progenitors. This could then be propagated to successive cell lineages. Persistent impairment of BM progenitor cell populations can disrupt hematopoietic homeostasis and lead to hematologic disorders, and these findings warrant further mechanistic studies into the effects of low-dose IR on the functional capacity of BM-derived hematopoietic cells including their self-renewal and pluripotency. PMID:26528440

  17. Particle Radiation-Induced Nontargeted Effects in Bone-Marrow-Derived Endothelial Progenitor Cells.

    PubMed

    Sasi, Sharath P; Park, Daniel; Muralidharan, Sujatha; Wage, Justin; Kiladjian, Albert; Onufrak, Jillian; Enderling, Heiko; Yan, Xinhua; Goukassian, David A

    2015-01-01

    Bone-marrow- (BM-) derived endothelial progenitor cells (EPCs) are critical for endothelial cell maintenance and repair. During future space exploration missions astronauts will be exposed to space irradiation (IR) composed of a spectrum of low-fluence protons ((1)H) and high charge and energy (HZE) nuclei (e.g., iron-(56)Fe) for extended time. How the space-type IR affects BM-EPCs is limited. In media transfer experiments in vitro we studied nontargeted effects induced by (1)H- and (56)Fe-IR conditioned medium (CM), which showed significant increase in the number of p-H2AX foci in nonirradiated EPCs between 2 and 24 h. A 2-15-fold increase in the levels of various cytokines and chemokines was observed in both types of IR-CM at 24 h. Ex vivo analysis of BM-EPCs from single, low-dose, full-body (1)H- and (56)Fe-IR mice demonstrated a cyclical (early 5-24 h and delayed 28 days) increase in apoptosis. This early increase in BM-EPC apoptosis may be the effect of direct IR exposure, whereas late increase in apoptosis could be a result of nontargeted effects (NTE) in the cells that were not traversed by IR directly. Identifying the role of specific cytokines responsible for IR-induced NTE and inhibiting such NTE may prevent long-term and cyclical loss of stem and progenitors cells in the BM milieu. PMID:26074973

  18. (28)Silicon radiation-induced enhancement of synaptic plasticity in the hippocampus of naïve and cognitively tested mice.

    PubMed

    Raber, Jacob; Rudobeck, Emil; Campbell-Beachler, Mary; Allen, Antiño R; Allen, Barrett; Rosi, Susanna; Nelson, Gregory A; Ramachandran, Shaila; Turner, Jennifer; Fike, John R; Vlkolinsky, Roman

    2014-04-01

    The space radiation environment consists of multiple species of high-energy charge particles (HZE), including (56)Fe and (28)Si nuclei, that may impact neuronal cells, but their damaging effects on the central nervous system (CNS) have been poorly defined. Hippocampus-dependent memory functions have been shown to be highly sensitive to (56)Fe HZE particles, which poses a significant risk to the cognitive performance of astronauts during space missions. While low doses of (56)Fe radiation do not induce cell death of mature neurons, they affect synaptic plasticity in the CA1 region, the principal neuronal output of the hippocampal formation involved in memory formation. The effects of (28)Si on the CNS have not been defined. Compared to behaviorally naïve mice, cognitive testing might affect synaptic plasticity and the effects of (28)Si radiation on synaptic plasticity might be modulated by prior cognitive testing. Therefore, in the current study, we quantified the effects of whole-body (28)Si radiation (600 MeV/n, 0.25 and 1 Gy) on hippocampus-dependent contextual freezing and synaptic plasticity in the CA1 region of animals not exposed (behaviorally naïve mice) and animals exposed to the contextual freezing test (cognitively tested mice). In behaviorally naïve mice exposed to 0.25 and 1 Gy of (28)Si radiation, the magnitude of long-term potentiation (LTP) was enhanced. However, in mice irradiated with 0.25 Gy contextual fear conditioning was enhanced and was associated with a further enhancement of the LTP magnitude. Such increase in synaptic plasticity was not seen in cognitively tested mice irradiated with 1 Gy. Thus, low dose (28)Si radiation has effects on synaptic plasticity in the CA1 region of the hippocampus and these effects are modulated by cognitive testing in a contextual fear-conditioning test. PMID:24673255

  19. Low- and high-LET radiation drives clonal expansion of lung progenitor cells in vivo

    PubMed Central

    Farin, Alicia M.; Manzo, Nicholas D.; Kirsch, David G.; Stripp, Barry R.

    2015-01-01

    Abundant populations of epithelial progenitor cells maintain the epithelium along the proximal-to-distal axis of the airway. Exposure of lung tissue to ionizing radiation leads to tissue remodeling and potential cancer initiation or progression. However, little is known about the effects of ionizing radiation on airway epithelial progenitor cells. We hypothesized that ionizing radiation exposure will alter the behavior of airway epithelial progenitor cells in a radiation dose- and quality-dependent manner. To address this hypothesis, we cultured primary airway epithelial cells isolated from mice exposed to various doses of 320 kVp X-ray or 600 MeV/nucleon 56Fe ions in a 3D epithelial-fibroblast co-culture system. Colony-forming efficiency of the airway epithelial progenitor cells was assessed at culture day 14. In vivo clonogenic and proliferative potentials of airway epithelial progenitor cells were measured after exposure to ionizing radiation by lineage tracing and IdU incorporation. Exposure to both X-rays and 56Fe resulted in a dose dependent decrease in the ability of epithelial progenitors to form colonies in vitro. In vivo evidence for increased clonogenic expansion of epithelial progenitors was observed after exposure to both X-rays and 56Fe. Interestingly, we found no significant increase in the epithelial proliferative index, indicating that ionizing radiation does not promote increased turnover of the airway epithelium. Therefore, we propose a model in which radiation induces a dose-dependent decrease in the pool of available progenitor cells, leaving fewer progenitors able to maintain the airway long-term. This work provides novel insights into the effects of ionizing radiation exposure on airway epithelial progenitor cell behavior. PMID:25564721

  20. Iron Isotopic Fractionation in Early Planetary Crusts

    NASA Astrophysics Data System (ADS)

    Wang, K.; Moynier, F.; Dauphas, N.; Barrat, J.; Day, J. M.; Sio, C.; Korotev, R. L.; Zeigler, R. A.

    2012-12-01

    Differentiated meteorites (achondrites) derive from planetary bodies that experienced variable degrees of melting and silicate-metal segregation. The oldest achondrites, such as eucrites, angrites, brachinites and the oligoclase-rich meteorites Graves Nunataks 06128/06129 (GRA 06128/9), were formed ~2-5 Ma after the first Solar System solids. They represent the oldest differentiated silicate samples known in the Solar System and the study of these samples provides insight on the origins and conditions of formation of the first planetary crusts. Here, we present new high-precision data for the Fe isotopic compositions of eucrites, angrites, brachinites and GRA 06128/9 and interpret these results in terms of magmatism during formation of these samples. We find that most eucrites and brachinites are not fractionated compared to undifferentiated chondritic meteorites (δ56Fe = 0.00±0.01, 2se), while the rare Stannern-trend eucrites are slightly enriched in the heavier isotopes of Fe. Angrites are also enriched in the heavier isotopes (δ56Fe = 0.12±0.01, 2se), similar to what is observed for terrestrial basalts, reflecting the relatively high oxidation states of the angrite parent body(ies). Contrastingly to the 'basaltic' achondrites, GRA 06128/9 are enriched in light isotopes of Fe (δ56Fe = -0.08±0.02, 2se). Evidence for light Fe isotope enrichments may be the consequence of the segregation of magma rich in sulphide (usually enriched in light isotopes of Fe compared to silicate and metal in undifferentiated meteorites). If correct, this result not only confirms that GRA 06128/9 represent products from <30% partial melting of an asteroidal body, prior to core formation, but also indicates complementary Fe isotope systematics between GRA 06128/9 and brachinites.

  1. Cardiovascular Risks Associated with Low Dose Ionizing Particle Radiation

    DOE PAGES

    Yan, Xinhua; Sasi, Sharath P.; Gee, Hannah; Lee, JuYong; Yang, Yongyao; Mehrzad, Raman; Onufrak, Jillian; Song, Jin; Enderling, Heiko; Agarwal, Akhil; et al

    2014-10-22

    Previous epidemiologic data demonstrate that cardiovascular (CV) morbidity and mortality may occur decades after ionizing radiation exposure. With increased use of proton and carbon ion radiotherapy and concerns about space radiation exposures to astronauts on future long-duration exploration-type missions, the long-term effects and risks of low-dose charged particle irradiation on the CV system must be better appreciated. Here we report on the long-term effects of whole-body proton (1H; 0.5 Gy, 1 GeV) and iron ion (56Fe; 0.15 Gy, 1GeV/nucleon) irradiation with and without an acute myocardial ischemia (AMI) event in mice. We show that cardiac function of proton-irradiated mice initiallymore » improves at 1 month but declines by 10 months post-irradiation. In AMI-induced mice, prior proton irradiation improved cardiac function restoration and enhanced cardiac remodeling. This was associated with increased pro-survival gene expression in cardiac tissues. In contrast, cardiac function was significantly declined in 56Fe ion-irradiated mice at 1 and 3 months but recovered at 10 months. In addition, 56Fe ion-irradiation led to poorer cardiac function and more adverse remodeling in AMI-induced mice, and was associated with decreased angiogenesis and pro-survival factors in cardiac tissues at any time point examined up to 10 months. This is the first study reporting CV effects following low dose proton and iron ion irradiation during normal aging and post-AMI. Finally, understanding the biological effects of charged particle radiation qualities on the CV system is necessary both for the mitigation of space exploration CV risks and for understanding of long-term CV effects following charged particle radiotherapy.« less

  2. Ionizing Particle Radiation as a Modulator of Endogenous Bone Marrow Cell Reprogramming: Implications for Hematological Cancers

    PubMed Central

    Muralidharan, Sujatha; Sasi, Sharath P.; Zuriaga, Maria A.; Hirschi, Karen K.; Porada, Christopher D.; Coleman, Matthew A.; Walsh, Kenneth X.; Yan, Xinhua; Goukassian, David A.

    2015-01-01

    Exposure of individuals to ionizing radiation (IR), as in the case of astronauts exploring space or radiotherapy cancer patients, increases their risk of developing secondary cancers and other health-related problems. Bone marrow (BM), the site in the body where hematopoietic stem cell (HSC) self-renewal and differentiation to mature blood cells occurs, is extremely sensitive to low-dose IR, including irradiation by high-charge and high-energy particles. Low-dose IR induces DNA damage and persistent oxidative stress in the BM hematopoietic cells. Inefficient DNA repair processes in HSC and early hematopoietic progenitors can lead to an accumulation of mutations whereas long-lasting oxidative stress can impair hematopoiesis itself, thereby causing long-term damage to hematopoietic cells in the BM niche. We report here that low-dose 1H- and 56Fe-IR significantly decreased the hematopoietic early and late multipotent progenitor (E- and L-MPP, respectively) cell numbers in mouse BM over a period of up to 10 months after exposure. Both 1H- and 56Fe-IR increased the expression of pluripotent stem cell markers Sox2, Nanog, and Oct4 in L-MPPs and 10 months post-IR exposure. We postulate that low doses of 1H- and 56Fe-IR may induce endogenous cellular reprogramming of BM hematopoietic progenitor cells to assume a more primitive pluripotent phenotype and that IR-induced oxidative DNA damage may lead to mutations in these BM progenitors. This could then be propagated to successive cell lineages. Persistent impairment of BM progenitor cell populations can disrupt hematopoietic homeostasis and lead to hematologic disorders, and these findings warrant further mechanistic studies into the effects of low-dose IR on the functional capacity of BM-derived hematopoietic cells including their self-renewal and pluripotency. PMID:26528440

  3. Particle Radiation-Induced Nontargeted Effects in Bone-Marrow-Derived Endothelial Progenitor Cells

    PubMed Central

    Sasi, Sharath P.; Park, Daniel; Muralidharan, Sujatha; Wage, Justin; Kiladjian, Albert; Onufrak, Jillian; Enderling, Heiko; Yan, Xinhua; Goukassian, David A.

    2015-01-01

    Bone-marrow- (BM-) derived endothelial progenitor cells (EPCs) are critical for endothelial cell maintenance and repair. During future space exploration missions astronauts will be exposed to space irradiation (IR) composed of a spectrum of low-fluence protons (1H) and high charge and energy (HZE) nuclei (e.g., iron-56Fe) for extended time. How the space-type IR affects BM-EPCs is limited. In media transfer experiments in vitro we studied nontargeted effects induced by 1H- and 56Fe-IR conditioned medium (CM), which showed significant increase in the number of p-H2AX foci in nonirradiated EPCs between 2 and 24 h. A 2–15-fold increase in the levels of various cytokines and chemokines was observed in both types of IR-CM at 24 h. Ex vivo analysis of BM-EPCs from single, low-dose, full-body 1H- and 56Fe-IR mice demonstrated a cyclical (early 5–24 h and delayed 28 days) increase in apoptosis. This early increase in BM-EPC apoptosis may be the effect of direct IR exposure, whereas late increase in apoptosis could be a result of nontargeted effects (NTE) in the cells that were not traversed by IR directly. Identifying the role of specific cytokines responsible for IR-induced NTE and inhibiting such NTE may prevent long-term and cyclical loss of stem and progenitors cells in the BM milieu. PMID:26074973

  4. Long-Term Differential Changes in Mouse Intestinal Metabolomics after γ and Heavy Ion Radiation Exposure

    PubMed Central

    Kaur, Prabhjit; Singh, Rajbir; Fornace, Albert J.; Datta, Kamal

    2014-01-01

    Tissue consequences of radiation exposure are dependent on radiation quality and high linear energy transfer (high-LET) radiation, such as heavy ions in space is known to deposit higher energy in tissues and cause greater damage than low-LET γ radiation. While radiation exposure has been linked to intestinal pathologies, there are very few studies on long-term effects of radiation, fewer involved a therapeutically relevant γ radiation dose, and none explored persistent tissue metabolomic alterations after heavy ion space radiation exposure. Using a metabolomics approach, we report long-term metabolomic markers of radiation injury and perturbation of signaling pathways linked to metabolic alterations in mice after heavy ion or γ radiation exposure. Intestinal tissues (C57BL/6J, female, 6 to 8 wks) were analyzed using ultra performance liquid chromatography coupled with electrospray quadrupole time-of-flight mass spectrometry (UPLC-QToF-MS) two months after 2 Gy γ radiation and results were compared to an equitoxic 56Fe (1.6 Gy) radiation dose. The biological relevance of the metabolites was determined using Ingenuity Pathway Analysis, immunoblots, and immunohistochemistry. Metabolic profile analysis showed radiation-type-dependent spatial separation of the groups. Decreased adenine and guanosine and increased inosine and uridine suggested perturbed nucleotide metabolism. While both the radiation types affected amino acid metabolism, the 56Fe radiation preferentially altered dipeptide metabolism. Furthermore, 56Fe radiation caused upregulation of ‘prostanoid biosynthesis’ and ‘eicosanoid signaling’, which are interlinked events related to cellular inflammation and have implications for nutrient absorption and inflammatory bowel disease during space missions and after radiotherapy. In conclusion, our data showed for the first time that metabolomics can not only be used to distinguish between heavy ion and γ radiation exposures, but also as a radiation

  5. Cardiovascular Risks Associated with Low Dose Ionizing Particle Radiation

    PubMed Central

    Yan, Xinhua; Sasi, Sharath P.; Gee, Hannah; Lee, JuYong; Yang, Yongyao; Mehrzad, Raman; Onufrak, Jillian; Song, Jin; Enderling, Heiko; Agarwal, Akhil; Rahimi, Layla; Morgan, James; Wilson, Paul F.; Carrozza, Joseph; Walsh, Kenneth; Kishore, Raj; Goukassian, David A.

    2014-01-01

    Previous epidemiologic data demonstrate that cardiovascular (CV) morbidity and mortality may occur decades after ionizing radiation exposure. With increased use of proton and carbon ion radiotherapy and concerns about space radiation exposures to astronauts on future long-duration exploration-type missions, the long-term effects and risks of low-dose charged particle irradiation on the CV system must be better appreciated. Here we report on the long-term effects of whole-body proton (1H; 0.5 Gy, 1 GeV) and iron ion (56Fe; 0.15 Gy, 1GeV/nucleon) irradiation with and without an acute myocardial ischemia (AMI) event in mice. We show that cardiac function of proton-irradiated mice initially improves at 1 month but declines by 10 months post-irradiation. In AMI-induced mice, prior proton irradiation improved cardiac function restoration and enhanced cardiac remodeling. This was associated with increased pro-survival gene expression in cardiac tissues. In contrast, cardiac function was significantly declined in 56Fe ion-irradiated mice at 1 and 3 months but recovered at 10 months. In addition, 56Fe ion-irradiation led to poorer cardiac function and more adverse remodeling in AMI-induced mice, and was associated with decreased angiogenesis and pro-survival factors in cardiac tissues at any time point examined up to 10 months. This is the first study reporting CV effects following low dose proton and iron ion irradiation during normal aging and post-AMI. Understanding the biological effects of charged particle radiation qualities on the CV system is necessary both for the mitigation of space exploration CV risks and for understanding of long-term CV effects following charged particle radiotherapy. PMID:25337914

  6. (28)Silicon radiation-induced enhancement of synaptic plasticity in the hippocampus of naïve and cognitively tested mice.

    PubMed

    Raber, Jacob; Rudobeck, Emil; Campbell-Beachler, Mary; Allen, Antiño R; Allen, Barrett; Rosi, Susanna; Nelson, Gregory A; Ramachandran, Shaila; Turner, Jennifer; Fike, John R; Vlkolinsky, Roman

    2014-04-01

    The space radiation environment consists of multiple species of high-energy charge particles (HZE), including (56)Fe and (28)Si nuclei, that may impact neuronal cells, but their damaging effects on the central nervous system (CNS) have been poorly defined. Hippocampus-dependent memory functions have been shown to be highly sensitive to (56)Fe HZE particles, which poses a significant risk to the cognitive performance of astronauts during space missions. While low doses of (56)Fe radiation do not induce cell death of mature neurons, they affect synaptic plasticity in the CA1 region, the principal neuronal output of the hippocampal formation involved in memory formation. The effects of (28)Si on the CNS have not been defined. Compared to behaviorally naïve mice, cognitive testing might affect synaptic plasticity and the effects of (28)Si radiation on synaptic plasticity might be modulated by prior cognitive testing. Therefore, in the current study, we quantified the effects of whole-body (28)Si radiation (600 MeV/n, 0.25 and 1 Gy) on hippocampus-dependent contextual freezing and synaptic plasticity in the CA1 region of animals not exposed (behaviorally naïve mice) and animals exposed to the contextual freezing test (cognitively tested mice). In behaviorally naïve mice exposed to 0.25 and 1 Gy of (28)Si radiation, the magnitude of long-term potentiation (LTP) was enhanced. However, in mice irradiated with 0.25 Gy contextual fear conditioning was enhanced and was associated with a further enhancement of the LTP magnitude. Such increase in synaptic plasticity was not seen in cognitively tested mice irradiated with 1 Gy. Thus, low dose (28)Si radiation has effects on synaptic plasticity in the CA1 region of the hippocampus and these effects are modulated by cognitive testing in a contextual fear-conditioning test.

  7. Characteristics of nucleus-nucleus interaction with relativistic heavy-ions

    SciTech Connect

    Das, G.

    1981-01-01

    A systematic study of relativistic heavy-ion collisions in nuclear emulsion, initiated by /sup 40/Ar, /sup 56/Fe at E = 1.8 GeV/N, /sup 56/Fe at 0.8 GeV/N, and /sup 12/C at 400 MeV/N, has been made. Projectile fragmentation reactions, where there is no visual indication of target excitation, are studied in terms of multiplicity and projected angular distributions. The standard deviation widths of the projected angular distributions are compared with the first order theory of Lepore and Riddell. In quasi-central collisions, where a part of both the projectile and target nuclei participate, we have undertaken a study of the space angle distributions of the relativistic alpha particles, emitted in /sup 40/Ar-emulsion interactions at E = 1.8 GeV/N and /sup 56/Fe-emulsion interactions at E = 0.8 GeV/N. The large angle alpha particle distributions are fitted with moving relativistic Boltzmann distributions, and compared with distributions obtained by Monte Carlo simulation of ..cap alpha..-p hard scattering process. Mean free path of secondary relativistic projectile fragments, emitted in such collisions, are carefully studied to verify the presence of anomalous mfp component among these fragments. This is followed by a study of the mean free path of secondary alpha particles. Finally, in central collisions, the angular distributions of singly charged particles with ..beta.. > 0.7 are studied with a view to observe collective phenomena, such as nuclear shock wave in nuclear matter.

  8. Iron sources and dissolved-particulate interactions in the seawater of the Western Equatorial Pacific, iron isotope perspectives

    NASA Astrophysics Data System (ADS)

    Labatut, M.; Lacan, F.; Pradoux, C.; Chmeleff, J.; Radic, A.; Murray, J. W.; Poitrasson, F.; Johansen, A. M.; Thil, F.

    2014-10-01

    This work presents iron isotope data in the western equatorial Pacific. Marine aerosols and top core margin sediments display a slightly heavy Fe isotopic composition (δ56Fe) of 0.33 ± 0.11‰ (2SD) and 0.14 ± 0.07‰, respectively. Samples reflecting the influence of Papua New Guinea runoff (Sepik River and Rabaul volcano water) are characterized by crustal values. In seawater, Fe is mainly supplied in the particulate form and is found with a δ56Fe between -0.49 and 0.34 ± 0.07‰. The particulate Fe seems to be brought mainly by runoff and transported across continental shelves and slopes. Aerosols are suspected to enrich the surface Vitiaz Strait waters, while hydrothermal activity likely enriched New Ireland waters. Dissolved Fe isotopic ratios are found between -0.03 and 0.53 ± 0.07‰. They are almost systematically heavier than the corresponding particulate Fe, and the difference between the signature of both phases is similar for most samples with Δ56FeDFe - PFe = +0.27 ± 0.25‰ (2SD). This is interpreted as an equilibrium isotopic fractionation revealing exchange fluxes between both phases. The dissolved phase being heavier than the particles suggests that the exchanges result in a net nonreductive release of dissolved Fe. This process seems to be locally significantly more intense than Fe reductive dissolution documented along reducing margins. It may therefore constitute a very significant iron source to the ocean, thereby influencing the actual estimation of the iron residence time and sinks. The underlying processes could also apply to other elements.

  9. Low-dose radiation affects cardiac physiology: gene networks and molecular signaling in cardiomyocytes.

    PubMed

    Coleman, Matthew A; Sasi, Sharath P; Onufrak, Jillian; Natarajan, Mohan; Manickam, Krishnan; Schwab, John; Muralidharan, Sujatha; Peterson, Leif E; Alekseyev, Yuriy O; Yan, Xinhua; Goukassian, David A

    2015-12-01

    There are 160,000 cancer patients worldwide treated with particle radiotherapy (RT). With the advent of proton, and high (H) charge (Z) and energy (E) HZE ionizing particle RT, the cardiovascular diseases risk estimates are uncertain. In addition, future deep space exploratory-type missions will expose humans to unknown but low doses of particle irradiation (IR). We examined molecular responses using transcriptome profiling in left ventricular murine cardiomyocytes isolated from mice that were exposed to 90 cGy, 1 GeV proton ((1)H) and 15 cGy, 1 GeV/nucleon iron ((56)Fe) over 28 days after exposure. Unsupervised clustering analysis of gene expression segregated samples according to the IR response and time after exposure, with (56)Fe-IR showing the greatest level of gene modulation. (1)H-IR showed little differential transcript modulation. Network analysis categorized the major differentially expressed genes into cell cycle, oxidative responses, and transcriptional regulation functional groups. Transcriptional networks identified key nodes regulating expression. Validation of the signal transduction network by protein analysis and gel shift assay showed that particle IR clearly regulates a long-lived signaling mechanism for ERK1/2, p38 MAPK signaling and identified NFATc4, GATA4, STAT3, and NF-κB as regulators of the response at specific time points. These data suggest that the molecular responses and gene expression to (56)Fe-IR in cardiomyocytes are unique and long-lasting. Our study may have significant implications for the efforts of National Aeronautics and Space Administration to develop heart disease risk estimates for astronauts and for patients receiving conventional and particle RT via identification of specific HZE-IR molecular markers. PMID:26408534

  10. Production and decay spectroscopy of 192Po and 194Po

    NASA Astrophysics Data System (ADS)

    Andel, B.

    2015-10-01

    A γ-ray spectroscopy study of the (11-) isomers in 194Po and 192Po was performed at the velocity filter SHIP at GSI (Germany). Nuclei were produced in fusion-evaporation reactions and investigated in the detection set-up at the focal plane after the separator. Several new γ transitions were attributed to the isomers and detailed analysis of the first γ-γ coincidences for both isomers is being prepared. For the reaction 56Fe + 141Pr → 197At*, excitation functions for astatine and polonium isotopes were measured and compared with HIVAP calculations.

  11. In-beam gamma-ray spectrometric measurements of multi-body breakup reactions for E{sub n} between threshold and 40 MeV

    SciTech Connect

    Dickens, J.K.; Larson, D.C.

    1995-04-01

    A system for in-beam gamma-ray spectrometric measurements to study inelastic neutron scattering has been extended to increasing incident neutron energies to study multi-body breakup reactions on light and medium-weight elements. The (n,2n{gamma}) cross sections are generally the largest; however, reactions of the types (n,{alpha}{gamma}), (n,np{gamma}) and (n,3n{gamma}) have been observed. In addition to improved understanding of reaction channels studied by other techniques, this method provides data for some reactions, e.g. {sup 56}Fe(n,3n){sup 54}Fe, which have not been observed previously.

  12. Electron screening effect in (p,n) and (p,γ) reactions

    SciTech Connect

    Cvetinović, Aleksandra; Gajević, Jelena; Lipoglavšek, Matej; Pelicon, Primož; Ortiz, Alberto Sánchez; Likar, Andrej; Petrovič, Toni

    2014-05-09

    To investigate the electron screening effect we compared γ-ray and neutron yields in different metals and insulators (Mn, V and Cd – metals and MnO, VO{sub 2} and CdO – insulators) for the proton induced nuclear reactions {sup 55}Mn(p,n){sup 55}Fe, {sup 55}Mn(p,γ){sup 56}Fe, {sup 113}Cd(p,n){sup 113}In and {sup 51}V(p,γ){sup 52}Cr. We also looked for shifts in resonance energy for metallic compared to insulator targets.

  13. Richardson-Gaudin description of pairing in atomic nuclei

    NASA Astrophysics Data System (ADS)

    De Baerdemacker, Stijn

    2012-05-01

    The present contribution discusses a connection between the exact Bethe Ansatz eigenstates of the reduced Bardeen-Cooper-Schrieffer (BCS) Hamiltonian and the multi-phonon states of the Tamm-Dancoff Approximation (TDA). The connection is made on the algebraic level, by means of a deformed quasi-spin algebra with a bosonic Heisenberg-Weyl algebra in the contraction limit of the deformation parameter. Each exact Bethe Ansatz eigenstate is mapped on a unique TDA multi-phonon state, shedding light on the physics behind the Bethe Ansatz structure of the exact wave function. The procedure is illustrated with a model describing neutron pairing in 56Fe.

  14. Iron isotopes in natural carbonate minerals determined by MC-ICP-MS with a 58Fe- 54Fe double spike

    NASA Astrophysics Data System (ADS)

    Dideriksen, K.; Baker, J. A.; Stipp, S. L. S.

    2006-01-01

    We have developed a method for iron isotope analysis by multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) using a 58Fe- 54Fe double spike. A 20 min analysis produces mass-bias-corrected iron isotope data with an external reproducibility of ±0.05 (2 SD) on δ56Fe, which represents a decrease in analysis time compared to sample-standard bracketing techniques. The estimation of external reproducibility is based on replicate analysis of the ETH hematite in-house standard. The double spike method has two advantages. First, matrix effects during MC-ICP-MS analysis are decreased with tests showing that accurate iron isotope data can, in some cases, be obtained even when matrix levels exceed iron concentration (Na/Fe, Mg/Fe, and Ca/Fe up to 5, 2, and 0.1, respectively). Because chemical separation reduces matrix/Fe to levels more than three orders of magnitude lower than this, measured Fe isotope compositions are unlikely to be compromised by matrix effects. Second, it is possible to spike samples before chemical purification, which enables any isotopic fractionation effect because of incomplete recovery of iron from a sample to be accounted for. This may be important where obtaining quantitative iron yields from samples is difficult, such as the extraction of dissolved iron from water samples. Fe isotope data on a set of standard reference materials (igneous rocks, ferromanganese nodules, sedimentary rocks, and ores) are presented, which are in agreement with previously published data considering analytical uncertainties. Mantle-derived standard rock samples that are the source of iron for surficial, (bio)geochemical cycling yield a mean δ56Fe of 0.041 ± 0.11‰ ( n = 8; 2 SD) with reference to IRMM-14. Hydrothermal and metamorphic calcium carbonate rocks with a relatively low iron content (100-4000 ppm) have δ56Fe = -1.25 to -0.07‰. Structural Fe(II) in hydrothermal calcites has δ56Fe = -1.25 to -0.27‰. The light iron in this range of

  15. Biomarkers in Archaean banded iron formations : examples from Pilbara and Dhawar Craton

    NASA Astrophysics Data System (ADS)

    Orberger, B.; Pinti, D. L.; Cloquet, C.; Hashizume, K.; Soyama, H.; Jayananda, M.; Wirth, R.; Gallien, J. P.; Massault, M.; Rouchon, V.

    The origin of Archeaen banded iron formations (BIF) and the role of biosphere in Fe precipitation is still highly debated. In order to elucidate these processes, detailed mineralogical and textural analyses combined with δ 15 N, δ 56 Fe and δ 13 C data were obtained on Fe-oxide bands from Marble Bar chert Unit (MB, 3.46 Ga, Pilbara craton, W. Australia) and a BIF from the Bababudan Group (BG, 2.7-2.9 Ga, Dhawar Craton, Southern India). Both samples are composed of alternating quartz and Feoxide bands with wavy micro-textures. CI-normalized REE patterns show that MB reflects hydrothermal fluid/basalt interactions, while BG precipitated from a hydrothermal fluid/seawater mixture. In MB, nano-cristalline hematite replaced magnetite, Mgcalcite and Fe-sulfides producing a matlike surface, preserving nanometric N-bearing amorphous carbon nodules. Measured C/N ratios (2.3 to 52) are typical of Precambrian organic matter. The δ 56 Fe of -0.40±0.02% suggests MOR-hydrothermal fluids as a Fe-source, while a δ 15 N of +7.4±0.4% is compatible with nitrification- denitrification processes and δ 13 C of -19.9±0.1% support an organic origin. BG is composed of intergrown magnetite and hematite. Disseminated grunerite and magnetite grew during low T metamorphism. Fe-oxide spherules compose vermicular- filaments that nucleated perpendicular to quartz surfaces. Fe-oxide spherule bunches are perfectly preserved in the silica bands forming micrometric mats, which contain heterogeneously distributed N (˜0.09at.%) and C (0.51 at.%, C/N=5.73). Bulk δ 13 C of -15.35%±0.10 points to an organic origin for C. The ?56 Fe in Fe and Si layers (0.75% to 2.16%) is compatible with a chemical precipitation for BIF. A negative correlation between ?56 Fe and the Th/U ratio suggests that Fe isotopic variations are related to fluid circulation and re-precipitation of Fe-oxides. High ?15 N, on one Feoxide layer, of +21.8±0.7%, corresponds to that observed for Archeaen BIFs and may be related

  16. Iron isotopes in the Seine River (France): Natural versus anthropogenic sources

    NASA Astrophysics Data System (ADS)

    Chen, Jiu-Bin; Busigny, Vincent; Gaillardet, Jérôme; Louvat, Pascale; Wang, Yi-Na

    2014-03-01

    The determination of fluxes and isotope compositions of Fe transported from continents to the ocean is essential for understanding global surface Fe cycle and its effect on oceanic biological productivity. Contrasting to non-polluted rivers, Fe isotope composition in rivers strongly affected by human activities is poorly constrained. In this contribution, we present the first Fe isotope data in suspended particulate matter (SPM) and dissolved load of the human-impacted Seine River (France). Iron concentrations and isotope compositions, together with major and trace element concentrations, were measured for two sample sets: (1) a geographic transect along the river from headwater to estuary, and (2) a temporal series of samples collected in Paris from 2004 to 2007. In the Seine River, Fe is mostly carried by SPM (average 99% of the total Fe) rather than dissolved load. The high Fe enrichment factor (1.40, relative to natural fluvial pre-historical and headwater sediments) and strong correlation between SPM Fe and Zn concentrations (r2 = 0.70, n = 30) demonstrate a strong anthropogenic Fe input. The Fe isotope compositions in SPM show a very small range (δ56Fe from -0.05‰ to 0.09‰) in spite of the large variations of Fe concentrations (from 1.78 to 4.17 wt.%) and are comparable to anthropogenic samples, suggesting that anthropogenic sources have similar Fe isotope composition to that of the natural background. In contrast, larger variations of Fe isotope compositions observed in the dissolved load (from -0.60‰ to 0.06‰) than that of SPM may provide a more promising means for tracing anthropogenic contributions to natural river systems. The δ56Fe and δ66Zn values of the dissolved loads are positively correlated (r2 = 0.62, n = 8), indicating a mixing between anthropogenic and natural end-members, enriched in light and heavy Fe isotopes respectively. Correlation between dissolved δ56Fe and DOC/Fe ratio (i.e. dissolved organic carbon/dissolved Fe

  17. Production and decay spectroscopy of {sup 192}Po and {sup 194}Po

    SciTech Connect

    Andel, B.

    2015-10-15

    A γ-ray spectroscopy study of the (11{sup −}) isomers in {sup 194}Po and {sup 192}Po was performed at the velocity filter SHIP at GSI (Germany). Nuclei were produced in fusion-evaporation reactions and investigated in the detection set-up at the focal plane after the separator. Several new γ transitions were attributed to the isomers and detailed analysis of the first γ-γ coincidences for both isomers is being prepared. For the reaction {sup 56}Fe + {sup 141}Pr → {sup 197}At*, excitation functions for astatine and polonium isotopes were measured and compared with HIVAP calculations.

  18. The storage of hydrogen in the form of metal hydrides: An application to thermal engines

    NASA Technical Reports Server (NTRS)

    Gales, C.; Perroud, P.

    1981-01-01

    The possibility of using LaNi56, FeTiH2, or MgH2 as metal hydride storage sytems for hydrogen fueled automobile engines is discussed. Magnesium copper and magnesium nickel hydrides studies indicate that they provide more stable storage systems than pure magnesium hydrides. Several test engines employing hydrogen fuel have been developed: a single cylinder motor originally designed for use with air gasoline mixture; a four-cylinder engine modified to run on an air hydrogen mixture; and a gas turbine.

  19. Lack of Radiation Dose or Quality Dependence of Epithelial-to-Mesenchymal Transition (EMT) Mediated by Transforming Growth Factor {beta}

    SciTech Connect

    Andarawewa, Kumari L.; Costes, Sylvain V.; Fernandez-Garcia, Ignacio; Chou, William S.; Ravani, Shraddha A.; Park, Howard; Barcellos-Hoff, Mary Helen

    2011-04-01

    Purpose: Epithelial-to-mesenchymal transition (EMT) is a phenotype that alters cell morphology, disrupts morphogenesis, and increases motility. Our prior studies have shown that the progeny of human mammary epithelial cells (HMECs) irradiated with 2 Gy undergoes transforming growth factor {beta} (TGF-{beta})-mediated EMT. In this study we determined whether radiation dose or quality affected TGF-{beta}-mediated EMT. Methods and Materials: HMECs were cultured on tissue culture plastic or in Matrigel (BD Biosciences, San Jose, CA) and exposed to low or high linear energy transfer (LET) and TGF-{beta} (400 pg/mL). Image analysis was used to measure membrane-associated E-cadherin, a marker of functional epithelia, or fibronectin, a product of mesenchymal cells, as a function of radiation dose and quality. Results: E-cadherin was reduced in TGF-{beta}-treated cells irradiated with low-LET radiation doses between 0.03 and 2 Gy compared with untreated, unirradiated cells or TGF-{beta} treatment alone. The radiation quality dependence of TGF-{beta}-mediated EMT was determined by use of 1 GeV/amu (gigaelectron volt / atomic mass unit) {sup 56}Fe ion particles at the National Aeronautics and Space Administration's Space Radiation Laboratory. On the basis of the relative biological effectiveness of 2 for {sup 56}Fe ion particles' clonogenic survival, TGF-{beta}-treated HMECs were irradiated with equitoxic 1-Gy {sup 56}Fe ion or 2-Gy {sup 137}Cs radiation in monolayer. Furthermore, TGF-{beta}-treated HMECs irradiated with either high- or low-LET radiation exhibited similar loss of E-cadherin and gain of fibronectin and resulted in similar large, poorly organized colonies when embedded in Matrigel. Moreover, the progeny of HMECs exposed to different fluences of {sup 56}Fe ion underwent TGF-{beta}-mediated EMT even when only one-third of the cells were directly traversed by the particle. Conclusions: Thus TGF-{beta}-mediated EMT, like other non-targeted radiation effects, is

  20. Processes and time scales of magmatic evolution as revealed by Fe-Mg chemical and isotopic zoning in natural olivines

    NASA Astrophysics Data System (ADS)

    Oeser, Martin; Dohmen, Ralf; Horn, Ingo; Schuth, Stephan; Weyer, Stefan

    2015-04-01

    In this study, we applied high-precision in situ Fe and Mg isotope analyses by femtosecond laser ablation (fs-LA) MC-ICP-MS on chemically zoned olivine xeno- and phenocrysts from intra-plate volcanic regions in order to investigate the magnitude of Fe and Mg isotope fractionation and its suitability to gain information on magma evolution. Our results show that chemical zoning (i.e., Mg#) in magmatic olivines is commonly associated with significant zoning in δ56Fe and δ26Mg (up to 1.7‰ and 0.7‰, respectively). We explored different cases of kinetic fractionation of Fe and Mg isotopes by modeling diffusion in the melt or olivine and simultaneous growth or dissolution. Combining the information of chemical and isotopic zoning in olivine allows to distinguish between various processes that may occur during magma evolution, namely diffusive Fe-Mg exchange between olivine and melt, rapid crystal growth, and Fe-Mg inter-diffusion simultaneous to crystal dissolution or growth. Chemical diffusion in olivine appears to be the dominant process that drives isotope fractionation in magmatic olivine. Simplified modeling of Fe and Mg diffusion is suitable to reproduce both the chemical and the isotopic zoning in most of the investigated olivines and, additionally, provides time information about magmatic processes. For the Massif Central (France), modeling of diffusive re-equilibration of mantle olivines in basanites revealed a short time span (<2 years) between the entrainment of a mantle xenolith in an intra-plate basaltic magma and the eruption of the magma. Furthermore, we determined high cooling rates (on the order of a few tens to hundreds of °C per year) for basanite samples from a single large outcrop in the Massif Central, which probably reflects the cooling of a massive lava flow after eruption. Results from the modeling of Fe and Mg isotope fractionation in olivine point to a systematic difference between βFe and βMg (i.e., βFe/βMg ≈ 2), implying that the

  1. Responses of the central nervous system to high linear energy transfer radiation: NSCOR project highlights

    PubMed Central

    Nelson, Gregory; Fike, John; Limoli, Charles; Obenaus, André; Raber, Jacob; Soltesz, Ivan; Vlkolinský, Roman

    2014-01-01

    Overview: The five-university NSCOR project investigates the responses of the central nervous system to space-like charged particle exposure by evaluating: synaptic function, in vitro and in vivo neurogenesis, behavior and behaviorally induced gene expression, and oxidative stress of the mouse hippocampus and cultured neural precursor cells. To test the role of reactive oxygen species in mediating the effects of radiation exposure, we compare responses in a catalase overexpressing transgenic mouse strain to wild type. We also use computational models of the hippocampus in three dimensions, informed by experimental measurements, to provide insight into network behavior. Radiation exposure protocols include single, acute whole-body exposures to 1H, 28Si and 56Fe ions and mixed field exposures using 1H + 56Fe ions (24 h later). The animal models are 10-week-old C57BL/6J and MCATtg males which are evaluated at 30 and 90 days postirradiation. In vitro models are cultured murine and human neural stem cells irradiated with 1H, 16O, 28Si and 56Fe ions at multiple energies and are evaluated at times from days to weeks. Highlights: Neural stem cells organized into neurospheres were irradiated with several ions at doses as low as 0.75 cGy. Data show that significant oxidative stress occurs that alters survival, proliferation and differentiation. Overall trends indicate that changes in oxidative stress (persisting for weeks) correlate with particle linear energy transfer (LET). 56Fe ions elicited the largest and most persistent changes in stress markers, including antioxidant enzyme expression levels. The hippocampus-dependent contextual fear conditioning (CFC) and novel object recognition (NOR) paradigms were used to assess cognition and showed cognitive deficits after irradiation with the NOR paradigm more sensitive than CFC. Analysis of neurogenesis indicates that overall neurogenesis is inhibited at doses ≥1 Gy, but newly born activated microglia are significantly

  2. A biological switch at the ocean surface as a cause of laminations in a Precambrian iron formation

    NASA Astrophysics Data System (ADS)

    Hashizume, K.; Pinti, D. L.; Orberger, B.; Cloquet, C.; Jayananda, M.; Soyama, H.

    2016-07-01

    Banded iron formations (BIFs) exhibit alternating silica- and iron-rich laminae, potentially reflecting the dynamics of the paleo-environments in which they were formed, although the exact mechanism remains unclear. Here the formation of a 2.7-2.9 Ga BIF from Dharwar Craton, India, is deciphered by analyzing the inter-band variations of the redox-sensitive isotope biomarkers, 15N/14N and 56Fe/54Fe. Organic matter with δ15N values as high as + 12.0 ± 0.8 ‰ appears to be trapped in silica. Iron oxides exhibit systematically positive δ56Fe values, ranging between + 0.80 ± 0.05 ‰ and + 1.67 ± 0.02 ‰. Compared to the iron-rich bands, silica-rich bands, which show higher δ56Fe values, exhibit an order of magnitude higher concentrations of 15N-rich organic nitrogen, normalized by the abundances of its host silica. The presence of 15N-rich organic matter may imply the emergence of a modern-like biological nitrogen cycle that requires the formation of oxidized nitrogen compounds. The higher concentration of 15N-rich organic nitrogen for the silica-rich bands possibly suggests that the photosynthetic activity was higher during the formation periods of these bands. The heavier iron isotope compositions of the silica-rich bands cannot be explained alone by iron oxidation through probable pathways. The relative 56Fe-enrichment in silica-rich bands is explained here by the progressive dissolution of iron oxides to the ocean, through iron reduction by 15N-rich organic matter actively produced at the ocean surface. The formation of iron-rich bands possibly corresponds to periods of reduced biological productivity, when precipitated iron was not effectively dissolved to the ocean. The observed shift in the organic concentration between Fe- and Si-rich bands could be the switch that triggered the BIF laminations. This shift could conceivably represent periodic fluctuations in the oxygen generation, which possibly occurred over periods of millennia, at the dawn of the

  3. Spin Modes, Neutrino-Induced Reactions and Nucleosynthesis in Stars

    SciTech Connect

    Suzuki, Toshio; Otsuka, Takaharu; Honma, Michio; Higashiyama, Koji

    2008-11-11

    Recent advances in shell model calculations of spin modes in nuclei with the use of new shell model Hamiltonians are discussed. Important roles of tensor interaction in shell evolutions toward drip-lines are pointed out. Electromagnetic transitions in exotic carbon isotopes are investigated. Anomalous supressions of transition strengths in the isotopes are found to be rather well explained. Neutrino-induced reactions on {sup 56}Fe and {sup 56}Ni are studied, and implications on production yields of heavy elements in stars are discussed.

  4. Comparison of iron isotope variations in modern and Ordovician siliceous Fe oxyhydroxide deposits

    NASA Astrophysics Data System (ADS)

    Moeller, Kirsten; Schoenberg, Ronny; Grenne, Tor; Thorseth, Ingunn H.; Drost, Kerstin; Pedersen, Rolf B.

    2014-02-01

    Formation pathways of ancient siliceous iron formations and related Fe isotopic fractionation are still not completely understood. Investigating these processes, however, is difficult as good modern analogues to ancient iron formations are scarce. Modern siliceous Fe oxyhydroxide deposits are found at marine hydrothermal vent sites, where they precipitate from diffuse, low temperature fluids along faults and fissures on the seafloor. These deposits exhibit textural and chemical features that are similar to some Phanerozoic iron formations, raising the question as to whether the latter could have precipitated from diffuse hydrothermal fluids rather than from hydrothermal plumes. In this study, we present the first data on modern Fe oxyhydroxide deposits from the Jan Mayen hydrothermal vent fields, Norwegian-Greenland Sea. The samples we investigated exhibited very low δ56Fe values between -2.09‰ and -0.66‰. Due to various degrees of partial oxidation, the Fe oxyhydroxides are with one exception either indistinguishable from low-temperature hydrothermal fluids from which they precipitated (-1.84‰ and -1.53‰ in δ56Fe) or are enriched in the heavy Fe isotopes. In addition, we investigated Fe isotope variations in Ordovician jasper beds from the Løkken ophiolite complex, Norway, which have been interpreted to represent diagenetic products of siliceous ferrihydrite precursors that precipitated in a hydrothermal plume, in order to compare different formation pathways of Fe oxyhydroxide deposits. Iron isotopes in the jasper samples have higher δ56Fe values (-0.38‰ to +0.89‰) relative to modern, high-temperature hydrothermal vent fluids (ca. -0.40‰ on average), supporting the fallout model. However, formation of the Ordovician jaspers by diffuse venting cannot be excluded, due to lithological differences of the subsurface of the two investigated vent systems. Our study shows that reliable interpretation of Fe isotope variations in modern and ancient marine

  5. Coupled Iron and Sulfur Isotope Constraints on the Archean and Paleoproterozoic Ocean Redox State

    NASA Astrophysics Data System (ADS)

    Rouxel, O. J.; Bekker, A.

    2009-05-01

    The rise of atmospheric oxygen level by ca. 2.3 Ga have led to dramatic shifts in the iron and sulfur oceanic cycles. Past studies of non-mass dependent and mass dependent sulfur isotope record in sedimentary sulfides over geological time have placed important constraints on biogeochemical cycle of sulfur and evolution of Precambrian ocean chemistry. Recently, we applied a similar time-record approach to explore potential changes in Fe isotope composition of pyrite in black shales. Although the underlying mechanisms for Fe isotope fractionation in organic-rich sediments are debated, we identified direct link between the rise of atmospheric oxygen and changes in the Fe ocean cycle suggesting that Fe isotopes are useful proxies to the past ocean redox state. Since biogeochemical cycles of Fe and S are closely coupled in marine systems, Fe-limitation and S-limitation for pyrite formation in black shales should leave imprint on the isotopic record of both elements. Coupled Fe and S isotope systematics of Devonian pyrite display a range of 50‰ in δ34S values whereas δ56Fe values vary between - 1.0 and +0.1‰ consistent with Fe isotope variations in modern marine sediments. Similarly, pyrite in the 1.88 Ga Gunflint Formation has δ34S values ranging from - 32‰ to +10‰ and displays a range of δ56Fe values between 0 to - 0.4‰. In contrast, Archean black shales (e.g. Manjeri Fm., Belingwe Belt and Jeerinah Fm., Hamersley Basin) display a smaller range of δ34S values between together with ubiquitous non-mass dependent S-isotope fractionation but a larger range of δ56Fe values from - 3.5 to +0.2‰. A transitional period between ca. 2.3 and ca. 1.8 Ga is marked by a larger spread of δ34S values from - 34 to +28‰, disappearance of MIF and a larger range of δ56Fe values from - 1.7 to +1.1‰. These results confirm that after the rise of atmospheric oxygen by ca. 2.3 Ga, Paleoproterozoic ocean became stratified and gradually affected by an increase of seawater

  6. Molybdenum (Mo) and Iron (Fe) Isotope Evidence of Tepla-Barrandian Black Shales Against Widespread Deep Ocean Oxygenation in the Late Neoproterozoic

    NASA Astrophysics Data System (ADS)

    Kurzweil, F.; Pasava, J.; Drost, K.; Wille, M.; Schoenberg, R.

    2014-12-01

    The late Neoproterozoic was a period of major environmental perturbations including tectonic reorganizations, biologic evolution and environmental oxygenation (Neoproterozoic oxygenation event). Authigenic enrichments in redox-sensitive elements such as Mo, V and U in late Neoproterozoic black shales prior to the appearance of the first metazoan fossils indicate that increasing oxygen levels in the atmosphere-hydrosphere system have facilitated the evolution and diversification of multi-cellular life. The isotopic composition of these elements is another tool to trace (possibly global) changes in the oceanic redox state. For example, significantly higher δ98Mo of seawater and black shales are expected, when the sink of isotopically light Mo in oxic deep marine settings increased. Accordingly, modern anoxic sediments in the Black Sea as well as the well oxygenated seawater show high δ98Mo of 2.3 ‰. However, Mesoproterozoic black shales show relatively low δ98Mo values up to 1.4 ‰. To test if the enrichment of redox-sensitive elements and metazoan evolution temporally correlate with an increase in seawater δ98Mo, we present Mo and Fe isotope data of slightly younger late Neoproterozoic black shales of the Tepla-Barrandian, Czech Republic. We observe a perfect correlation of Fe/Al ratios with δ56Fe that is best explained by mixing of detrital derived Fe with δ56Fe of ~0.1 ‰ and hydrothermal sourced Fe with δ56Fe of ~-0.7 ‰. Hydrothermally dominated samples with low δ56Fe are also enriched in heavy metals such as Ni, Cu and Zn as well as hydrothermally derived Mo (with δ98Mo of ~0.6 ‰). Samples with minor hydrothermal influence show authigenic Mo enrichment from seawater with a maximum δ98Mo of 1.2 ‰. This estimate indicates no significant increase in the seawater δ98Mo during the Neoproterozoic and after the evolution of metazoan life. Thus, our Mo isotope dataset provides no evidence for deep ocean oxygenation during the Neoproterozoic

  7. A preliminary study of iron isotope fractionation in marine invertebrates (chitons, Mollusca) in near-shore environments

    NASA Astrophysics Data System (ADS)

    Emmanuel, S.; Schuessler, J. A.; Vinther, J.; Matthews, A.; von Blanckenburg, F.

    2014-10-01

    Chitons (Mollusca) are marine invertebrates that produce radulae (teeth or rasping tongues) containing high concentrations of biomineralized magnetite and other iron-bearing minerals. As Fe isotope signatures are influenced by redox processes and biological fractionation, Fe isotopes in chiton radulae might be expected to provide an effective tracer of ambient oceanic conditions and biogeochemical cycling. Here, in a pilot study to measure Fe isotopes in marine invertebrates, we examine Fe isotopes in modern marine chiton radulae collected from different locations in the Atlantic and Pacific oceans to assess the range of isotopic values, and to test whether or not the isotopic signatures reflect seawater values. Values of δ56Fe (relative to IRMM-014) in chiton teeth range from -1.90 to 0.00 ‰ (±0.05‰ (2σ) uncertainty in δ56Fe), probably reflecting a combination of geographical control and biological fractionation processes. Comparison with published local surface seawater Fe isotope data shows a consistent negative offset of chiton teeth Fe isotope compositions relative to seawater. Strikingly, two different species from the same locality in the North Pacific (Puget Sound, Washington, USA) have distinct isotopic signatures. Tonicella lineata, which feeds on red algae in the sublittoral zone, has a mean δ56Fe of -0.65 ± 0.26‰ (2σ, 3 specimens), while Mopalia muscosa, which feeds on both green and red algae in the eulittoral zone, shows lighter isotopic values with a mean δ56Fe of -1.47 ± 0.98‰ (2σ, 5 specimens). Three possible pathways are proposed to account for the different isotopic signatures: (i) physiologically controlled processes within the chitons that lead to species-dependent fractionation; (ii) diet-controlled variability due to different Fe isotope fractionation in the red and green algal food sources; and (iii) environmentally controlled fractionation that causes variation in the isotopic signatures of bioavailable Fe in the different

  8. Coupled iron, sulfur and carbon isotope evidences for arsenic enrichment in groundwater

    NASA Astrophysics Data System (ADS)

    Wang, Yanxin; Xie, Xianjun; Johnson, Thomas M.; Lundstrom, Craig C.; Ellis, Andre; Wang, Xiangli; Duan, Mengyu; Li, Junxia

    2014-11-01

    It is generally accepted that microbial processes play a key role in the mobilization and enrichment of arsenic (As) in groundwater. However, the detailed mechanism of the metabolic processes remain poorly understand. We apply isotopic measurements of iron (δ56Fe vs. IRMM-14), sulfur (δ34SSO4 vs. V-CDT) and carbon (δ13CDIC vs. V-PDB) to an experimental field plot in the Datong Basin, northern China. An array of monitoring wells was installed in a ≈1700-m2 plot in which high concentrations of As, ranging from 4.76 to 469.5 μg/L, were detected in the groundwater. The measured range of δ34SSO4 values from 10.0‰ to 24.7‰ indicates the prevalence of microbial sulfate reduction within aquifers. The range of δ56Fe values measured in the groundwater suggests microbial Fe(III) reduction and the occurrence of isotopic exchange between Fe(II)aq and FeS precipitation. The low δ13CDIC values (up to -33.6‰) measured in groundwater are evidences for the microbial oxidation of organic matter, which is interpreted as the light carbon pool within the aquifer sediments. The high As (As > 50 μg/L) groundwater, which has higher δ34SSO4 and δ56Fe values and lower δ13C values, indicates the following: (1) microbial reduction of sulfate causes the mobilization of As through HS- abiotic reduction of Fe(III) minerals and/or formation of As-sulfur components; and (2) direct microbial reduction of Fe(III) oxides, hydroxides and oxyhydroxides cannot increase As concentrations to greater than 50 μg/L. Re-oxidation of Fe-sufide explains how sample C1-2 can have a high As concentration and low δ34SSO4 and high δ56Fe values. The results provide new insight into the mechanism of As enrichment in groundwater.

  9. Fe Isotope Fractionation During Fe(III) Reduction to Fe(II)

    NASA Astrophysics Data System (ADS)

    Baker, E. A.; Greene, S.; Hardin, E. E.; Hodierne, C. E.; Rosenberg, A.; John, S.

    2014-12-01

    The redox chemistry of Fe(III) and Fe(II) is tied to a variety of earth processes, including biological, chemical, or photochemical reduction of Fe(III) to Fe(II). Each process may fractionate Fe isotopes, but the magnitudes of the kinetic isotope effects have not been greatly explored in laboratory conditions. Here, we present the isotopic fractionation of Fe during reduction experiments under a variety of experimental conditions including photochemical reduction of Fe(III) bound to EDTA or glucaric acid, and chemical reduction of Fe-EDTA by sodium dithionite, hydroxylamine hydrochloride, Mn(II), and ascorbic acid. A variety of temperatures and pHs were tested. In all experiments, Fe(III) bound to an organic ligand was reduced in the presence of ferrozine. Ferrozine binds with Fe(II), forming a purple complex which allows us to measure the extent of reaction. The absorbance of the experimental solutions was measured over time to determine the Fe(II)-ferrozine concentration and thus the reduction rate. After about 5% of the Fe(III) was reduced, Fe(III)-EDTA and Fe(II)-ferrozine were separated using a C-18 column to which Fe(II)-ferrozine binds. The Fe(II) was eluted and purified through anion exchange chromatography for analysis of δ56Fe by MC-ICPMS. Preliminary results show that temperature and pH both affect reduction rate. All chemical reductants tested reduce Fe(III) at a greater rate as temperature increases. The photochemical reductant EDTA reduces Fe(III) at a greater rate under more acidic conditions. Comparison of the two photochemical reductants shows that glucaric acid reduces Fe(III) significantly faster than EDTA. For chemical reduction, the magnitude of isotopic fractionation depends on the reductant used. Temperature and pH also affect the isotopic fractionation of Fe. Experiments using chemical reductants show that an increase in temperature at low temperatures produces lighter 56Fe ratios, while at high temperatures some reductants produce heavier

  10. Is the Coulomb sum rule violated in nuclei?

    NASA Astrophysics Data System (ADS)

    Morgenstern, J.; Meziani, Z.-E.

    2001-08-01

    Guided by the experimental confirmation of the validity of the Effective Momentum Approximation (EMA) in quasi-elastic scattering off nuclei, we have re-examined the extraction of the longitudinal and transverse response functions in medium-weight and heavy nuclei. In the EMA we have performed a Rosenbluth separation of the available world data on 40Ca, 48Ca, 56Fe, 197Au, 208Pb and 238U. We find that the longitudinal response function for these nuclei is "quenched" and that the Coulomb sum is not saturated, at odds with claims in the literature.

  11. Determination of Light Water Reactor Fuel Burnup with the Isotope Ratio Method

    SciTech Connect

    Gerlach, David C.; Mitchell, Mark R.; Reid, Bruce D.; Gesh, Christopher J.; Hurley, David E.

    2007-11-01

    For the current project to demonstrate that isotope ratio measurements can be extended to zirconium alloys used in LWR fuel assemblies we report new analyses on irradiated samples obtained from a reactor. Zirconium alloys are used for structural elements of fuel assemblies and for the fuel element cladding. This report covers new measurements done on irradiated and unirradiated zirconium alloys, Unirradiated zircaloy samples serve as reference samples and indicate starting values or natural values for the Ti isotope ratio measured. New measurements of irradiated samples include results for 3 samples provided by AREVA. New results indicate: 1. Titanium isotope ratios were measured again in unirradiated samples to obtain reference or starting values at the same time irradiated samples were analyzed. In particular, 49Ti/48Ti ratios were indistinguishably close to values determined several months earlier and to expected natural values. 2. 49Ti/48Ti ratios were measured in 3 irradiated samples thus far, and demonstrate marked departures from natural or initial ratios, well beyond analytical uncertainty, and the ratios vary with reported fluence values. The irradiated samples appear to have significant surface contamination or radiation damage which required more time for SIMS analyses. 3. Other activated impurity elements still limit the sample size for SIMS analysis of irradiated samples. The sub-samples chosen for SIMS analysis, although smaller than optimal, were still analyzed successfully without violating the conditions of the applicable Radiological Work Permit

  12. Extrinsic Labeling of Staple Food Crops with Isotopic Iron Does Not Consistently Result in Full Equilibration: Revisiting the Methodology.

    PubMed

    Glahn, Raymond P; Cheng, Zhiqiang; Giri, Shree

    2015-11-01

    Extrinsic isotopic labeling of food Fe has been used for over 50 years to measure Fe absorption. This method assumes that complete equilibration occurs between the extrinsic and the intrinsic Fe prior to intestinal absorption. The present study tested this assumption via in vitro digestion of varieties of maize, white beans, black beans, red beans, and lentils. Prior to digestion, foods were extrinsically labeled with (58)Fe at concentrations of 1, 10, 50, and 100% of the intrinsic (56)Fe. Following an established in vitro digestion protocol, the digest was centrifuged and the Fe solubilities of the extrinsic (58)Fe and the intrinsic (56)Fe were compared as a measure of extrinsic/intrinsic equilibration. In the beans, significantly more of the extrinsic Fe (up to 2-3 times, p < 0.001) partitioned into the supernatant. The effect varied depending upon the seed coat color, the harvest, and the concentration of the extrinsic Fe. For lentils and maize the extrinsic Fe tended to partition into the insoluble fraction and also varied depending on variety and harvest. There was no crop that consistently demonstrated full equilibration of the extrinsic Fe with the intrinsic Fe. These observations challenge the accuracy of Fe absorption studies in which isotopic extrinsic Fe was used to evaluate Fe absorption and bioavailability.

  13. Measurement of hair iron concentration as a marker of body iron content

    PubMed Central

    SAHIN, CEM; PALA, CIGDEM; KAYNAR, LEYLAGUL; TORUN, YASEMIN ALTUNER; CETIN, AYSUN; KURNAZ, FATIH; SIVGIN, SERDAR; SAHIN, FATIH SERDAR

    2015-01-01

    The aim of the present study was to define the possible association between blood parameters and hair iron concentration in patient groups showing a difference in body iron content. The study population comprised subjects with iron deficiency anaemia and transfusion-related anaemia with different body iron contents and a healthy control group. All the cases included in the study were examined with respect to hair iron concentration, serum iron, total iron-binding capacity (TIBC), transferrin saturation and erythrocyte markers in the total blood count with ferritin values. Differences in hair iron concentration were evaluated between the groups. Correlation analysis was applied to define the association between the laboratory values used as markers of body iron content and hair iron concentration. A statistically significant difference was determined in hair iron 56Fe and 57Fe concentrations between the group with transfusion-related anaemia, the iron deficiency anaemia group and the healthy control group (P<0.001). In addition, a positive correlation was determined between hair iron 56Fe and 57Fe concentrations and serum iron, ferritin level, transferrin saturation, mean erythrocyte volume and mean erythrocyte haemoglobin values and a negative correlation with TIBC. In conclusion, the results of the present study showed a statistically significant difference in the hair iron concentrations of the patient groups with different body iron content and these values were correlated to the laboratory markers of body iron content. PMID:26137241

  14. Gene amplification and microsatellite instability induced in tumorigenic human bronchial epithelial cells by alpha particles and heavy ions

    NASA Technical Reports Server (NTRS)

    Piao, C. Q.; Hei, T. K.; Hall, E. J. (Principal Investigator)

    2001-01-01

    Gene amplification and microsatellite alteration are useful markers of genomic instability in tumor and transformed cell lines. It has been suggested that genomic instability contributes to the progression of tumorigenesis by accumulating genetic changes. In this study, amplification of the carbamyl-P-synthetase, aspartate transcarbamylase, dihydro-orotase (CAD) gene in transformed and tumorigenic human bronchial epithelial (BEP2D) cells induced by either alpha particles or (56)Fe ions was assessed by measuring resistance to N-(phosphonacetyl)-l-aspartate (PALA). In addition, alterations of microsatellite loci located on chromosomes 3p and 18q were analyzed in a series of primary and secondary tumor cell lines generated in nude mice. The frequency of PALA-resistant colonies was 1-3 x 10(-3) in tumor cell lines, 5-8 x 10(-5) in transformed cells prior to inoculation into nude mice, and less than 10(-7) in control BEP2D cells. Microsatellite alterations were detected in all 11 tumor cell lines examined at the following loci: D18S34, D18S363, D18S877, D3S1038 and D3S1607. No significant difference in either PALA resistance or microsatellite instability was found in tumor cell lines that were induced by alpha particles compared to those induced by (56)Fe ions.

  15. Quantification of dissolved iron sources to the North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Conway, Tim M.; John, Seth G.

    2014-07-01

    Dissolved iron is an essential micronutrient for marine phytoplankton, and its availability controls patterns of primary productivity and carbon cycling throughout the oceans. The relative importance of different sources of iron to the oceans is not well known, however, and flux estimates from atmospheric dust, hydrothermal vents and oceanic sediments vary by orders of magnitude. Here we present a high-resolution transect of dissolved stable iron isotope ratios (δ56Fe) and iron concentrations ([Fe]) along a section of the North Atlantic Ocean. The different iron sources can be identified by their unique δ56Fe signatures, which persist throughout the water column. This allows us to calculate the relative contribution from dust, hydrothermal venting and reductive and non-reductive sedimentary release to the dissolved phase. We find that Saharan dust aerosol is the dominant source of dissolved iron along the section, contributing 71-87 per cent of dissolved iron. Additional sources of iron are non-reductive release from oxygenated sediments on the North American margin (10-19 per cent), reductive sedimentary dissolution on the African margin (1-4 per cent) and hydrothermal venting at the Mid-Atlantic Ridge (2-6 per cent). Our data also indicate that hydrothermal vents in the North Atlantic are a source of isotopically light iron, which travels thousands of kilometres from vent sites, potentially influencing surface productivity. Changes in the relative importance of the different iron sources through time may affect interactions between the carbon cycle and climate.

  16. The response of a spherical tissue-equivalent proportional counter to iron particles from 200-1000 MeV/nucleon

    NASA Technical Reports Server (NTRS)

    Gersey, B. B.; Borak, T. B.; Guetersloh, S. B.; Zeitlin, C.; Miller, J.; Heilbronn, L.; Murakami, T.; Iwata, Y.; Chatterjee, A. (Principal Investigator)

    2002-01-01

    The radiation environment on board the space shuttle and the International Space Station includes high-Z and high-energy (HZE) particles that are part of the galactic cosmic radiation (GCR) spectrum. Iron-56 particles are considered to be one of the most biologically important parts of the GCR spectrum. Tissue-equivalent proportional counters (TEPCs) are used as active dosimeters on manned space flights. These TEPCs are further used to determine the average quality factor for each space mission. A TEPC simulating a 1-microm-diameter sphere of tissue was exposed as part of a particle spectrometer to (56)Fe particles at energies from 200-1000 MeV/nucleon. The response of TEPCs in terms of mean lineal energy, y(F), and dose mean lineal energy, y(D), as well as the energy deposited at different impact parameters through the detector was determined for six different incident energies of (56)Fe particles in this energy range. Calculations determined that charged-particle equilibrium was achieved for each of the six experiments. Energy depositions at different impact parameters were calculated using a radial dose distribution model, and the results were compared to experimental data.

  17. Effects of age and diet on the heavy particle-induced disruption of operant responding produced by a ground-based model for exposure to cosmic rays.

    PubMed

    Rabin, Bernard M; Joseph, James A; Shukitt-Hale, Barbara

    2005-03-01

    On missions to other planets, astronauts will be exposed to galactic cosmic rays which are composed of heavy particles (such as 56Fe) and protons. Exposure to these particles can affect the ability of rats to perform a variety of tasks, indicating that there is the possibility that the performance capabilities of astronauts may be affected. Previous research has shown that diets containing blueberry or strawberry extract can ameliorate the deficits produced by irradiation using a ground-based analog for exposure to cosmic rays. Rats were placed on diets containing 2% blueberry or strawberry extract for 2 months prior to exposure to 1.5 Gy of 1 GeV/n 56Fe particles. There were no effects on performance of any group of animals when tested on an ascending fixed-ratio operant task 6 months following exposure. When tested 12 months after exposure, the performance of the radiated animals given blueberry extract did not differ from the radiated animals fed the control diet. Both groups performed significantly poorer than the non-irradiated controls. There were no differences between the non-irradiated animals fed control diet and the radiated animals fed the strawberry diet and their performance was significantly better than of the radiated rats fed the blueberry or control diets. The results indicate that diets containing strawberry extract may provide a significant level of radiation protection on exploratory class missions.

  18. Genomic instability and tumorigenic induction in immortalized human bronchial epithelial cells by heavy ions

    NASA Astrophysics Data System (ADS)

    Hei, T. K.; Piao, C. Q.; Wu, L. J.; Willey, J. C.; Hall, E. J.

    1998-11-01

    Carcinogenesis is postulated to be a progressive multistage process characterized by an increase in genomic instability and clonal selection with each mutational event endowing a selective growth advantage. Genomic instability as manifested by the amplification of specific gene fragments is common among tumor and transformed cells. In the present study, immortalized human bronchial (BEP2D) cells were irradiated with graded doses of either 1GeV/nucleon 56Fe ions or 150 keV/μm alpha particles. Transformed cells developed through a series of successive steps before becoming tumorigenic in nude mice. Tumorigenic cells showed neither ras mutations nor deletion in the p16 tumor suppressor gene. In contrast, they harbored mutations in the p53 gene and over-expressed cyclin D1. Genomic instability among transformed cells at various stage of the carcinogenic process was examined based on frequencies of PALA resistance. Incidence of genomic instability was highest among established tumor cell lines relative to transformed, non-tumorigenic and control cell lines. Treatment of BEP2D cells with a 4 mM dose of the aminothiol WR-1065 significantly reduced their neoplastic transforming response to 56Fe particles. This model provides an opportunity to study the cellular and molecular mechanisms involved in malignant transformation of human epithelial cells by heavy ions.

  19. Fractionation of Fe isotopes by soil microbes and organic acids

    USGS Publications Warehouse

    Brantley, Susan L.; Liermann, Laura; Bullen, Thomas D.

    2001-01-01

    Small natural variations in Fe isotopes have been attributed to biological cycling. However, without understanding the mechanism of fractionation, it is impossible to interpret such variations. Here we show that the δ56Fe of Fe dissolved from a silicate soil mineral by siderophore-producing bacteria is as much as 0.8% lighter than bulk Fe in the mineral. A smaller isotopic shift is observed for Fe released abiotically by two chelates, and the magnitude of the shift increases with affinity of the ligand for Fe, consistent with a kinetic isotope effect during hydrolysis of Fe at the mineral surface. Fe dissolved abiotically without chelates shows no isotopic shift. The δ56Fe of the exchange fraction on soil grains is also lighter by ~0.6%-1% than Fe from both hornblende and iron oxyhydroxides. The kinetic isotope effect is therefore preserved in open systems such as soils. when recorded in the rock record, Fe isotopic fractionation could document Fe transport by organic molecules or by microbes where such entities were present in the geologic past.

  20. Inelastic neutron scattering from carbon, iron, yttrium and lead

    NASA Astrophysics Data System (ADS)

    Gustavsson, Cecilia; Blomgren, Jan; Hellesen, Carl; Öhrn, Angelica; Pomp, Stephan

    2012-02-01

    Double-differential cross sections and angular distributions of inelastic neutron scattering on 12C, 56Fe, 89Y and 208Pb have been measured at 96 MeV at The Svedberg Laboratory, Uppsala, Sweden. Results on elastic neutron scattering at 96 MeV from these nuclei have been reported previously [1-3]. To obtain the inelastic cross sections, a forward-folding technique has been applied. A physically reasonable trial spectrum has been folded with the response function of the detector system and the output has been compared with the experimental data. To create the trial spectrum, a Gaussian has been used for the elastic part and the PRECO code [4-7] for the inelastic part. Other models were tested for the pre-equilibrium contribution and the method was found to be model independent. The response function of the detector setup has been obtained experimentally at the smallest possible angle, in this case at 9 deg. The resulting preliminary inelastic scattering data cover an excitation energy range up to 45 MeV and the angular intervals 28 to 58 degrees for 12C, 26 to 65 degrees for 56Fe and 26 to 52 degrees for 89Y and 208Pb. The preliminary results are discussed and compared to several model codes as well as existing experimental data for (n,n'x), (n,p'x) and (p,p'x). Possible improvements of the analysis are also discussed.

  1. Elastic Neutron Scattering at 96 MeV

    NASA Astrophysics Data System (ADS)

    Hildebrand, A.; Blomgren, J.; Ataç, A.; Bergenwall, B.; Johansson, C.; Klug, J.; Mermod, P.; Nilsson, L.; Pomp, S.; Österlund, M.; Dangtip, s.; Tippawan, U.; Phansuke, P.; Jonsson, O.; Renberg, P.-U.; Prokofiev, A.; Nadel-Turonski, P.; Elmgren, K.; Olsson, N.; Blideanu, V.; Le Brun, C.; Lecolley, J.-F.; Lecolley, F.-R.; Louvel, M.; Marie-Noury, N.; Schweitzer, C.; Eudes, Ph.; Haddad, F.; Lebrun, C.; Koning, A. J.

    2005-05-01

    A facility for detection of scattered neutrons in the energy interval 50-130 MeV, SCANDAL (SCAttered Nucleon Detection AssembLy), has recently been installed at the 20 - 180-MeV neutron beam line of The Svedberg Laboratory, Uppsala. Elastic neutron scattering from 12C, 16O, 56Fe, 89Y, and 208Pb has been studied at 96 MeV in the 10 - 70° interval. The results from 12C and 208Pb have recently been published,6 while the data from 16O, 56Fe, and 89Y are under analysis. The achieved energy resolution, 3.7 MeV, is about an order of magnitude better than for any previous experiment above 65 MeV incident energy. The present experiment represents the highest neutron energy where the ground state has been resolved from the first excited state in neutron scattering. A novel method for normalization of the absolute scale of the cross section has been used. The estimated normalization uncertainty, 3%, is unprecedented for a neutron-induced differential cross section measurement on a nuclear target. The results are compared with modern optical model predictions, based on phenomenology or microscopic theory. Applications for these measurements are nuclear-waste incineration, single-event upsets in electronics, and fast-neutron therapy.

  2. Biologically recycled continental iron is a major component in banded iron formations.

    PubMed

    Li, Weiqiang; Beard, Brian L; Johnson, Clark M

    2015-07-01

    Banded iron formations (BIFs) record a time of extensive Fe deposition in the Precambrian oceans, but the sources and pathways for metals in BIFs remain controversial. Here, we present Fe- and Nd-isotope data that indicate two sources of Fe for the large BIF units deposited 2.5 billion y ago. High-εNd and -δ(56)Fe signatures in some BIF samples record a hydrothermal component, but correlated decreases in εNd- and δ(56)Fe values reflect contributions from a continental component. The continental Fe source is best explained by Fe mobilization on the continental margin by microbial dissimilatory iron reduction (DIR) and confirms for the first time, to our knowledge, a microbially driven Fe shuttle for the largest BIFs on Earth. Detailed sampling at various scales shows that the proportions of hydrothermal and continental Fe sources were invariant over periods of 10(0)-10(3) y, indicating that there was no seasonal control, although Fe sources varied on longer timescales of 10(5)-10(6) y, suggesting a control by marine basin circulation. These results show that Fe sources and pathways for BIFs reflect the interplay between abiologic (hydrothermal) and biologic processes, where the latter reflects DIR that operated on a basin-wide scale in the Archean.

  3. The effects of proton exposure on neurochemistry and behavior.

    PubMed

    Shukitt-Hale, B; Szprengiel, A; Pluhar, J; Rabin, B M; Joseph, J A

    2004-01-01

    Future space missions will involve long-term travel beyond the magnetic field of the Earth, where astronauts will be exposed to radiation hazards such as those that arise from galactic cosmic rays. Galactic cosmic rays are composed of protons, alpha particles, and particles of high energy and charge (HZE particles). Research by our group has shown that exposure to HZE particles, primarily 600 MeV/n and 1 GeV/n 56Fe, can produce significant alterations in brain neurochemistry and behavior. However, given that protons can make up a significant portion of the radiation spectrum, it is important to study their effects on neural functioning and on related performance. Therefore, these studies examined the effects of exposure to proton irradiation on neurochemical and behavioral endpoints, including dopaminergic functioning, amphetamine-induced conditioned taste aversion learning, and spatial learning and memory as measured by the Morris water maze. Male Sprague-Dawley rats received a dose of 0, 1.5, 3.0 or 4.0 Gy of 250 MeV protons at Loma Linda University and were tested in the different behavioral tests at various times following exposure. Results showed that there was no effect of proton irradiation at any dose on any of the endpoints measured. Therefore, there is a contrast between the insignificant effects of high dose proton exposure and the dramatic effectiveness of low dose (<0.1 Gy) exposures to 56Fe particles on both neurochemical and behavioral endpoints. PMID:15803624

  4. CNS-induced deficits of heavy particle irradiation in space: the aging connection.

    PubMed

    Joseph, J A; Shukitt-Hale, B; McEwen, J; Rabin, B M

    2000-01-01

    Our research over the last several years has suggested that young (3 mo) rats exposed to whole-body 56Fe irradiation show neuronal signal transduction alterations and accompanying motor behavioral changes that are similar to those seen in aged (22-24 mo) rats. Since it has been postulated that 1-2% of the composition of cosmic rays contain 56Fe particles of heavy particle irradiation, there may be significant CNS effects on astronauts on long-term space flights which could produce behavioral changes that could be expressed during the mission or at some time after the return. These, when combined with other effects such as weightlessness and exposure to proton irradiations may even supercede mutagenic effects. It is suggested that by determining mechanistic relationships that might exist between aging and irradiation it may be possible to determine the common factor(s) involved in both perturbations and develop procedures to offset their deleterious effects. For example, one method that has been effective is nutritional modification. PMID:11542857

  5. Effects of age and diet on the heavy particle-induced disruption of operant responding produced by a ground-based model for exposure to cosmic rays.

    PubMed

    Rabin, Bernard M; Joseph, James A; Shukitt-Hale, Barbara

    2005-03-01

    On missions to other planets, astronauts will be exposed to galactic cosmic rays which are composed of heavy particles (such as 56Fe) and protons. Exposure to these particles can affect the ability of rats to perform a variety of tasks, indicating that there is the possibility that the performance capabilities of astronauts may be affected. Previous research has shown that diets containing blueberry or strawberry extract can ameliorate the deficits produced by irradiation using a ground-based analog for exposure to cosmic rays. Rats were placed on diets containing 2% blueberry or strawberry extract for 2 months prior to exposure to 1.5 Gy of 1 GeV/n 56Fe particles. There were no effects on performance of any group of animals when tested on an ascending fixed-ratio operant task 6 months following exposure. When tested 12 months after exposure, the performance of the radiated animals given blueberry extract did not differ from the radiated animals fed the control diet. Both groups performed significantly poorer than the non-irradiated controls. There were no differences between the non-irradiated animals fed control diet and the radiated animals fed the strawberry diet and their performance was significantly better than of the radiated rats fed the blueberry or control diets. The results indicate that diets containing strawberry extract may provide a significant level of radiation protection on exploratory class missions. PMID:15725409

  6. Long-term effects of irradiation with iron-56 particles on the nigrostriatal dopamine system.

    PubMed

    Rice, Onarae V; Grande, Alicia V; Dehktyar, Natasha; Bruneus, Magalie; Robinson, John K; Gatley, Samuel J

    2009-04-01

    Exposure to heavy ions during a Mars mission might damage the brain, thus compromising mission success and the quality of life of returning astronauts. Several workers have suggested that the dopamine system is particularly sensitive to heavy ion radiation, but direct evidence for this notion is lacking. We examined measures of brain dopamine viability at times up to 15 months after acute exposure of rats to (56)Fe (1.2-2.4 Gy). No effects were seen in brain sections stained for tyrosine hydroxylase, the classical marker for dopamine cells and nerve terminals. Locomotion stimulated by cocaine, which directly activates the dopamine system, was reduced at 6 months but not at 12 months. Furthermore, in a visually cued lever-pressing test, reaction times, which are prolonged by dopamine system damage, were identical in irradiated and control animals. However, learning times were increased by irradiation. Our data suggest that the midbrain dopamine system is not especially sensitive to damage by (56)Fe particles at doses much higher than would be associated with travel to and from Mars. PMID:19259693

  7. Iron-ion radiation accelerates atherosclerosis in apolipoprotein E-deficient mice.

    PubMed

    Yu, Tao; Parks, Brian W; Yu, Shaohua; Srivastava, Roshni; Gupta, Kiran; Wu, Xing; Khaled, Saman; Chang, Polly Y; Kabarowski, Janusz H; Kucik, Dennis F

    2011-06-01

    Radiation exposure from a number of terrestrial sources is associated with an increased risk for atherosclerosis. Recently, concern over whether exposure to cosmic radiation might pose a similar risk for astronauts has increased. To address this question, we examined the effect of 2 to 5 Gy iron ions ((56)Fe), a particularly damaging component of cosmic radiation, targeted to specific arterial sites in male apolipoprotein E-deficient (apoE(-/-)) mice. Radiation accelerated the development of atherosclerosis in irradiated portions of the aorta independent of any systemic effects on plasma lipid profiles or circulating leukocytes. Further, radiation exposure resulted in a more rapid progression of advanced aortic root lesions, characterized by larger necrotic cores associated with greater numbers of apoptotic macrophages and reduced lesional collagen compared to sham-treated mice. Intima media thickening of the carotid arteries was also exacerbated. Exposure to (56)Fe ions can therefore accelerate the development of atherosclerotic lesions and promote their progression to an advanced stage characterized by compositional changes indicative of increased thrombogenicity and instability. We conclude that the potential consequences of radiation exposure for astronauts on prolonged deep-space missions are a major concern. Knowledge gained from further studies with animal models should lead to a better understanding of the pathophysiological effects of accelerated ion radiation to better estimate atherogenic risk and develop appropriate countermeasures to mitigate its damaging effects. PMID:21466380

  8. Long-term effects of irradiation with iron-56 particles on the nigrostriatal dopamine system.

    PubMed

    Rice, Onarae V; Grande, Alicia V; Dehktyar, Natasha; Bruneus, Magalie; Robinson, John K; Gatley, Samuel J

    2009-04-01

    Exposure to heavy ions during a Mars mission might damage the brain, thus compromising mission success and the quality of life of returning astronauts. Several workers have suggested that the dopamine system is particularly sensitive to heavy ion radiation, but direct evidence for this notion is lacking. We examined measures of brain dopamine viability at times up to 15 months after acute exposure of rats to (56)Fe (1.2-2.4 Gy). No effects were seen in brain sections stained for tyrosine hydroxylase, the classical marker for dopamine cells and nerve terminals. Locomotion stimulated by cocaine, which directly activates the dopamine system, was reduced at 6 months but not at 12 months. Furthermore, in a visually cued lever-pressing test, reaction times, which are prolonged by dopamine system damage, were identical in irradiated and control animals. However, learning times were increased by irradiation. Our data suggest that the midbrain dopamine system is not especially sensitive to damage by (56)Fe particles at doses much higher than would be associated with travel to and from Mars.

  9. Organotypic culture in three dimensions prevents radiation-induced transformation in human lung epithelial cells

    NASA Astrophysics Data System (ADS)

    El-Ashmawy, Mariam; Coquelin, Melissa; Luitel, Krishna; Batten, Kimberly; Shay, Jerry W.

    2016-08-01

    The effects of radiation in two-dimensional (2D) cell culture conditions may not recapitulate tissue responses as modeled in three-dimensional (3D) organotypic culture. In this study, we determined if the frequency of radiation-induced transformation and cancer progression differed in 3D compared to 2D culture. Telomerase immortalized human bronchial epithelial cells (HBECs) with shTP53 and mutant KRas expression were exposed to various types of radiation (gamma, +H, 56Fe) in either 2D or 3D culture. After irradiation, 3D structures were dissociated and passaged as a monolayer followed by measurement of transformation, cell growth and expression analysis. Cells irradiated in 3D produced significantly fewer and smaller colonies in soft agar than their 2D-irradiated counterparts (gamma P = 0.0004 +H P = 0.049 56Fe P < 0.0001). The cell culture conditions did not affect cell killing, the ability of cells to survive in a colony formation assay, and proliferation rates after radiation—implying there was no selection against cells in or dissociated from 3D conditions. However, DNA damage repair and apoptosis markers were increased in 2D cells compared to 3D cells after radiation. Ideally, expanding the utility of 3D culture will allow for a better understanding of the biological consequences of radiation exposure.

  10. Organotypic culture in three dimensions prevents radiation-induced transformation in human lung epithelial cells

    PubMed Central

    El-Ashmawy, Mariam; Coquelin, Melissa; Luitel, Krishna; Batten, Kimberly; Shay, Jerry W.

    2016-01-01

    The effects of radiation in two-dimensional (2D) cell culture conditions may not recapitulate tissue responses as modeled in three-dimensional (3D) organotypic culture. In this study, we determined if the frequency of radiation-induced transformation and cancer progression differed in 3D compared to 2D culture. Telomerase immortalized human bronchial epithelial cells (HBECs) with shTP53 and mutant KRas expression were exposed to various types of radiation (gamma, +H, 56Fe) in either 2D or 3D culture. After irradiation, 3D structures were dissociated and passaged as a monolayer followed by measurement of transformation, cell growth and expression analysis. Cells irradiated in 3D produced significantly fewer and smaller colonies in soft agar than their 2D-irradiated counterparts (gamma P = 0.0004; +H P = 0.049; 56Fe P < 0.0001). The cell culture conditions did not affect cell killing, the ability of cells to survive in a colony formation assay, and proliferation rates after radiation—implying there was no selection against cells in or dissociated from 3D conditions. However, DNA damage repair and apoptosis markers were increased in 2D cells compared to 3D cells after radiation. Ideally, expanding the utility of 3D culture will allow for a better understanding of the biological consequences of radiation exposure. PMID:27539227

  11. Effects of Exposure to Heavy Particles on a Behavior Mediated by the Dopaminergic System

    NASA Astrophysics Data System (ADS)

    Rabin, B. M.; Joseph, J. A.; Shukitt-Hale, B.; McEwen, J.

    The effects of exposure to heavy particles on behaviors mediated by the central nervous system (CNS) are qualitatively different than the effects produced by exposure to other types of radiation. One behavior mediated by the CNS is the amphetamine-induced taste aversion, which is produced by pairing a novel tasting solution with injection of amphetamine. When the conditioning day is three days following irradiation, exposing rats to low doses of 56Fe particles (600 MeV/n or 1 GeV/n) eliminates the taste aversion produced by injection of amphetamine, which is dependent upon the integrity of the central dopaminergic system, but has no effect on the aversion produced by injection of lithium chloride which is mediated by the gastrointestinal system. In contrast to the effects obtained using heavy particles, exposing rats to 60Co gamma rays or to fission spectrum neutrons has no selective effect upon the acquisition of either amphetamine- or lithium chloride-induced taste aversions. When the conditioning day occurs four months following exposure to 1 GeV/n 56Fe particles, there is an enhancement of the amphetamine-induced taste aversion. The implications of these findings for approaches to risk assessment are considered

  12. The effects of proton exposure on neurochemistry and behavior

    NASA Astrophysics Data System (ADS)

    Shukitt-Hale, B.; Szprengiel, A.; Pluhar, J.; Rabin, B. M.; Joseph, J. A.

    2004-01-01

    Future space missions will involve long-term travel beyond the magnetic field of the Earth, where astronauts will be exposed to radiation hazards such as those that arise from galactic cosmic rays. Galactic cosmic rays are composed of protons, α particles, and particles of high energy and charge (HZE particles). Research by our group has shown that exposure to HZE particles, primarily 600 MeV/n and 1 GeV/n 56Fe, can produce significant alterations in brain neurochemistry and behavior. However, given that protons can make up a significant portion of the radiation spectrum, it is important to study their effects on neural functioning and on related performance. Therefore, these studies examined the effects of exposure to proton irradiation on neurochemical and behavioral endpoints, including dopaminergic functioning, amphetamine-induced conditioned taste aversion learning, and spatial learning and memory as measured by the Morris water maze. Male Sprague-Dawley rats received a dose of 0, 1.5, 3.0 or 4.0 Gy of 250 MeV protons at Loma Linda University and were tested in the different behavioral tests at various times following exposure. Results showed that there was no effect of proton irradiation at any dose on any of the endpoints measured. Therefore, there is a contrast between the insignificant effects of high dose proton exposure and the dramatic effectiveness of low dose (<0.1 Gy) exposures to 56Fe particles on both neurochemical and behavioral endpoints.

  13. A Green's function method for heavy ion beam transport

    NASA Technical Reports Server (NTRS)

    Shinn, J. L.; Wilson, J. W.; Schimmerling, W.; Shavers, M. R.; Miller, J.; Benton, E. V.; Frank, A. L.; Badavi, F. F.

    1995-01-01

    The use of Green's function has played a fundamental role in transport calculations for high-charge high-energy (HZE) ions. Two recent developments have greatly advanced the practical aspects of implementation of these methods. The first was the formulation of a closed-form solution as a multiple fragmentation perturbation series. The second was the effective summation of the closed-form solution through nonperturbative techniques. The nonperturbative methods have been recently extended to an inhomogeneous, two-layer transport media to simulate the lead scattering foil present in the Lawrence Berkeley Laboratories (LBL) biomedical beam line used for cancer therapy. Such inhomogeneous codes are necessary for astronaut shielding in space. The transport codes utilize the Langley Research Center atomic and nuclear database. Transport code and database evaluation are performed by comparison with experiments performed at the LBL Bevalac facility using 670 A MeV 20Ne and 600 A MeV 56Fe ion beams. The comparison with a time-of-flight and delta E detector measurement for the 20Ne beam and the plastic nuclear track detectors for 56Fe show agreement up to 35%-40% in water and aluminium targets, respectively.

  14. Biologically recycled continental iron is a major component in banded iron formations

    PubMed Central

    Li, Weiqiang; Beard, Brian L.; Johnson, Clark M.

    2015-01-01

    Banded iron formations (BIFs) record a time of extensive Fe deposition in the Precambrian oceans, but the sources and pathways for metals in BIFs remain controversial. Here, we present Fe- and Nd-isotope data that indicate two sources of Fe for the large BIF units deposited 2.5 billion y ago. High-εNd and -δ56Fe signatures in some BIF samples record a hydrothermal component, but correlated decreases in εNd- and δ56Fe values reflect contributions from a continental component. The continental Fe source is best explained by Fe mobilization on the continental margin by microbial dissimilatory iron reduction (DIR) and confirms for the first time, to our knowledge, a microbially driven Fe shuttle for the largest BIFs on Earth. Detailed sampling at various scales shows that the proportions of hydrothermal and continental Fe sources were invariant over periods of 100–103 y, indicating that there was no seasonal control, although Fe sources varied on longer timescales of 105–106 y, suggesting a control by marine basin circulation. These results show that Fe sources and pathways for BIFs reflect the interplay between abiologic (hydrothermal) and biologic processes, where the latter reflects DIR that operated on a basin-wide scale in the Archean. PMID:26109570

  15. The effects of proton exposure on neurochemistry and behavior.

    PubMed

    Shukitt-Hale, B; Szprengiel, A; Pluhar, J; Rabin, B M; Joseph, J A

    2004-01-01

    Future space missions will involve long-term travel beyond the magnetic field of the Earth, where astronauts will be exposed to radiation hazards such as those that arise from galactic cosmic rays. Galactic cosmic rays are composed of protons, alpha particles, and particles of high energy and charge (HZE particles). Research by our group has shown that exposure to HZE particles, primarily 600 MeV/n and 1 GeV/n 56Fe, can produce significant alterations in brain neurochemistry and behavior. However, given that protons can make up a significant portion of the radiation spectrum, it is important to study their effects on neural functioning and on related performance. Therefore, these studies examined the effects of exposure to proton irradiation on neurochemical and behavioral endpoints, including dopaminergic functioning, amphetamine-induced conditioned taste aversion learning, and spatial learning and memory as measured by the Morris water maze. Male Sprague-Dawley rats received a dose of 0, 1.5, 3.0 or 4.0 Gy of 250 MeV protons at Loma Linda University and were tested in the different behavioral tests at various times following exposure. Results showed that there was no effect of proton irradiation at any dose on any of the endpoints measured. Therefore, there is a contrast between the insignificant effects of high dose proton exposure and the dramatic effectiveness of low dose (<0.1 Gy) exposures to 56Fe particles on both neurochemical and behavioral endpoints.

  16. A Green's function method for heavy ion beam transport.

    PubMed

    Shinn, J L; Wilson, J W; Schimmerling, W; Shavers, M R; Miller, J; Benton, E V; Frank, A L; Badavi, F F

    1995-08-01

    The use of Green's function has played a fundamental role in transport calculations for high-charge high-energy (HZE) ions. Two recent developments have greatly advanced the practical aspects of implementation of these methods. The first was the formulation of a closed-form solution as a multiple fragmentation perturbation series. The second was the effective summation of the closed-form solution through nonperturbative techniques. The nonperturbative methods have been recently extended to an inhomogeneous, two-layer transport media to simulate the lead scattering foil present in the Lawrence Berkeley Laboratories (LBL) biomedical beam line used for cancer therapy. Such inhomogeneous codes are necessary for astronaut shielding in space. The transport codes utilize the Langley Research Center atomic and nuclear database. Transport code and database evaluation are performed by comparison with experiments performed at the LBL Bevalac facility using 670 A MeV 20Ne and 600 A MeV 56Fe ion beams. The comparison with a time-of-flight and delta E detector measurement for the 20Ne beam and the plastic nuclear track detectors for 56Fe show agreement up to 35%-40% in water and aluminium targets, respectively. PMID:7480630

  17. Extrinsic Labeling of Staple Food Crops with Isotopic Iron Does Not Consistently Result in Full Equilibration: Revisiting the Methodology.

    PubMed

    Glahn, Raymond P; Cheng, Zhiqiang; Giri, Shree

    2015-11-01

    Extrinsic isotopic labeling of food Fe has been used for over 50 years to measure Fe absorption. This method assumes that complete equilibration occurs between the extrinsic and the intrinsic Fe prior to intestinal absorption. The present study tested this assumption via in vitro digestion of varieties of maize, white beans, black beans, red beans, and lentils. Prior to digestion, foods were extrinsically labeled with (58)Fe at concentrations of 1, 10, 50, and 100% of the intrinsic (56)Fe. Following an established in vitro digestion protocol, the digest was centrifuged and the Fe solubilities of the extrinsic (58)Fe and the intrinsic (56)Fe were compared as a measure of extrinsic/intrinsic equilibration. In the beans, significantly more of the extrinsic Fe (up to 2-3 times, p < 0.001) partitioned into the supernatant. The effect varied depending upon the seed coat color, the harvest, and the concentration of the extrinsic Fe. For lentils and maize the extrinsic Fe tended to partition into the insoluble fraction and also varied depending on variety and harvest. There was no crop that consistently demonstrated full equilibration of the extrinsic Fe with the intrinsic Fe. These observations challenge the accuracy of Fe absorption studies in which isotopic extrinsic Fe was used to evaluate Fe absorption and bioavailability. PMID:26456842

  18. Biologically recycled continental iron is a major component in banded iron formations.

    PubMed

    Li, Weiqiang; Beard, Brian L; Johnson, Clark M

    2015-07-01

    Banded iron formations (BIFs) record a time of extensive Fe deposition in the Precambrian oceans, but the sources and pathways for metals in BIFs remain controversial. Here, we present Fe- and Nd-isotope data that indicate two sources of Fe for the large BIF units deposited 2.5 billion y ago. High-εNd and -δ(56)Fe signatures in some BIF samples record a hydrothermal component, but correlated decreases in εNd- and δ(56)Fe values reflect contributions from a continental component. The continental Fe source is best explained by Fe mobilization on the continental margin by microbial dissimilatory iron reduction (DIR) and confirms for the first time, to our knowledge, a microbially driven Fe shuttle for the largest BIFs on Earth. Detailed sampling at various scales shows that the proportions of hydrothermal and continental Fe sources were invariant over periods of 10(0)-10(3) y, indicating that there was no seasonal control, although Fe sources varied on longer timescales of 10(5)-10(6) y, suggesting a control by marine basin circulation. These results show that Fe sources and pathways for BIFs reflect the interplay between abiologic (hydrothermal) and biologic processes, where the latter reflects DIR that operated on a basin-wide scale in the Archean. PMID:26109570

  19. Nuclear structure of odd-odd 82Y

    NASA Astrophysics Data System (ADS)

    Womble, P. C.; Döring, J.; Glasmacher, T.; Holcomb, J. W.; Johns, G. D.; Johnson, T. D.; Petters, T. J.; Riley, M. A.; Wood, V. A.; Tabor, S. L.; Semmes, P.

    1993-06-01

    Excited states in 82Y have been investigated via the 58Ni(28Si,3pn)82Y and 56Fe(29Si,p2n)82Y reactions using beams provided by the Florida State University Tandem-LINAC with energies of 95 to 135 MeV. Particle-γ coincidences with a full-sphere charged-particle detector and an excitation curve were used to assign γ rays to 82Y. The 56Fe(29Si,p2n)82Y reaction at 95 MeV was used to measure γ-γ coincidences with five Compton-suppressed Ge detectors. Lifetimes in the ns and ps ranges were measured using direct timing and the Doppler-shift attenuation method. A level scheme with 39 states was constructed up to tentative spins and parities of (15-) and (21+). In the positive-parity yrast band a phase reversal was observed in the signature splitting at I=10ħ. The B(M1) strengths in this band alternate with signature between about 0.1 and 1.0 μ2N. The B(E2) strengths of about 90 Weisskopf units are in good agreement with those predicted by Hartree-Fock-Bogolyubov calculations. Particle-rotor calculations indicate a prolate or triaxial core shape for the positive-parity band.

  20. On-line experimental results of an argon gas cell-based laser ion source (KEK Isotope Separation System)

    NASA Astrophysics Data System (ADS)

    Hirayama, Y.; Watanabe, Y. X.; Imai, N.; Ishiyama, H.; Jeong, S. C.; Jung, H. S.; Miyatake, H.; Oyaizu, M.; Kimura, S.; Mukai, M.; Kim, Y. H.; Sonoda, T.; Wada, M.; Huyse, M.; Kudryavtsev, Yu.; Van Duppen, P.

    2016-06-01

    KEK Isotope Separation System (KISS) has been developed at RIKEN to produce neutron rich isotopes with N = 126 to study the β -decay properties for application to astrophysics. The KISS is an element-selective mass-separation system which consists of an argon gas cell-based on laser ion source for atomic number selection and an ISOL mass-separation system. The argon gas cell of KISS is a key component to stop and collect the unstable nuclei produced in a multi-nucleon transfer reaction, where the isotopes of interest will be selectively ionized using laser resonance ionization. We have performed off- and on-line experiments to study the basic properties of the gas cell as well as of the KISS. We successfully extracted the laser-ionized stable 56Fe (direct implantation of a 56Fe beam into the gas cell) atoms and 198Pt (emitted from the 198Pt target by elastic scattering with a 136Xe beam) atoms from the KISS during the commissioning on-line experiments. We furthermore extracted laser-ionized unstable 199Pt atoms and confirmed that the measured half-life was in good agreement with the reported value.

  1. Zn, Fe and S isotope fractionation in a large hydrothermal system

    NASA Astrophysics Data System (ADS)

    Gagnevin, D.; Boyce, A. J.; Barrie, C. D.; Menuge, J. F.; Blakeman, R. J.

    2012-07-01

    The genesis of hydrothermal ore deposits is of crucial economic importance. This study investigates the extent, causes and consequences of zinc and iron isotope fractionation in a large hydrothermal system at the world-class Navan Zn-Pb orebody, Ireland. Large variations in Zn, Fe and S isotope compositions have been measured in microdrilled sphalerite (ZnS) at the millimetre scale. δ66Zn and δ56Fe display a well-defined positive correlation and both also correlate with δ34S. These relationships represent the combined effects of kinetic Zn and Fe isotope fractionation during sphalerite precipitation, and S isotope variation through mixing of hot, metal-rich hydrothermal fluids and cool, bacteriogenic sulfide-bearing brines. Combined with S isotope data, δ56Fe and δ66Zn data on mine concentrates confirm that hydrothermal sulfide is a minor component of the overall deposit signature. Our data suggest that incoming pulses of metal-rich hydrothermal fluid triggered sulfide mineralisation, and that rapid precipitation of sphalerite from hydrothermal fluids will lead to strong kinetic fractionation of Zn and Fe isotopes at very short time and length scales, thereby limiting the use of Fe and Zn isotopes as exploration tools within deposits, but revealing the possibility of detecting new deposits from isotopically heavy Zn-Fe geochemical halos.

  2. Some perspectives on cataractogenesis from heavy charged particles

    SciTech Connect

    Lett, J.T.; Cox, A.B.; Lee, A.C.

    1985-01-01

    Two sets of observations on cataractogenesis in the New Zealand white (NZW) rabbit (Oryctolagus cuniculus) following localized exposure of optic and proximate tissues to heavy ions are reported. The experiments involved measurements of lenticular opacification in young (ca. 9 weeks old) rabbits caused by graded doses (0.5-5.0 Gy) of 460 MeV/u (incident energy) 56Fe ions and the effects of animal age (9 +/- 0.3 week, 1 +/- 0.5 year, and 4.5 +/- 1.3 year) on lenticular opacifications caused by 9 Gy of 400 MeV/u (incident energy) 20Ne ions. In substantiation of earlier results from NZW rabbits exposed to other low- and high-LET radiations, there was a dose-dependent onset of cataractogenesis following 56Fe-ion irradiation, with the highest doses causing the earliest appearance of cataracts. The level of stationary cataracts was also dependent on dose, and preliminary estimates of RBE yield values comparable to those found at similar doses (0.5-5.0 Gy) by others with populations of cultured cells. With increasing age at the time of exposure to 20Ne ions, the onset of lenticular opacification was delayed progressively and the level of stationary cataracts was reduced, but the onset and progression of late cataractogenesis was most rapid in the oldest group of animals. A discussion of the use of cataract measurements in risk assessment is included in this article.

  3. THE ELUSIVE {sup 60}Fe IN THE SOLAR NEBULA

    SciTech Connect

    Moynier, Frederic; Wang, Kun; Blichert-Toft, Janne; Albarede, Francis; Herzog, Gregory F. E-mail: kwang@levee.wustl.edu E-mail: albarede@ens-lyon.fr

    2011-11-10

    No {sup 60}Ni or {sup 61}Ni anomalies have been detected in troilite inclusions from Muonionalusta, a 4565.3 {+-} 0.1 Ma old IVA iron meteorite, to the level of the analytical precision of 10 ppm. Because Muonionalusta troilite is very old, has a high Fe/Ni ratio, and is free of {sup 61}Ni anomalies, it is the ideal material in which to search for potential excesses of {sup 60}Ni produced by the decay of {sup 60}Fe (t{sub 1/2} = 2.62 Ma). The {sup 60}Ni/{sup 58}Ni and Fe/Ni ratios (up to 1680) measured here imply an upper limit for the initial {sup 60}Fe/{sup 56}Fe for the Muonionalusta troilite of 3 Multiplication-Sign 10{sup -9}. Assuming that {sup 60}Fe was homogeneously distributed across the nebula, this result suggests that the solar system initial {sup 60}Fe/{sup 56}Fe ratio was less than 5 Multiplication-Sign 10{sup -9}, which is lower than previously measured by at least a factor of 50.

  4. {sup 60}Fe AND {sup 26}Al IN CHONDRULES FROM UNEQUILIBRATED CHONDRITES: IMPLICATIONS FOR EARLY SOLAR SYSTEM PROCESSES

    SciTech Connect

    Mishra, R. K.; Goswami, J. N.; Rudraswami, N. G.; Tachibana, S.; Huss, G. R.

    2010-05-10

    The presence of about a dozen short-lived nuclides in the early solar system, including {sup 60}Fe and {sup 26}Al, has been established from isotopic studies of meteorite samples. An accurate estimation of solar system initial abundance of {sup 60}Fe, a distinct product of stellar nucleosynthesis, is important to infer the stellar source of this nuclide. Previous studies in this regard suffered from the lack of exact knowledge of the time of formation of the analyzed meteorite samples. We present here results obtained from the first combined study of {sup 60}Fe and {sup 26}Al records in early solar system objects to remove this ambiguity. Chondrules from unequilibrated ordinary chondrites belonging to low petrologic grades were analyzed for their Fe-Ni and Al-Mg isotope systematics. The Al-Mg isotope data provide the time of formation of the analyzed chondrules relative to the first solar system solids, the Ca-Al-rich inclusions. The inferred initial {sup 60}Fe/{sup 56}Fe values of four chondrules, combined with their time of formation based on Al-Mg isotope data, yielded a weighted mean value of (6.3 {+-} 2) x 10{sup -7} for solar system initial {sup 60}Fe/{sup 56}Fe. This argues for a high-mass supernova as the source of {sup 60}Fe along with {sup 26}Al and several other short-lived nuclides present in the early solar system.

  5. Biological Fe oxidation controlled deposition of banded iron formation in the ca. 3770 Ma Isua Supracrustal Belt (West Greenland)

    NASA Astrophysics Data System (ADS)

    Czaja, Andrew D.; Johnson, Clark M.; Beard, Brian L.; Roden, Eric E.; Li, Weiqiang; Moorbath, Stephen

    2013-02-01

    The redox balance of the Archean atmosphere-ocean system is among the most significant uncertainties in our understanding of the earliest history of Earth's surface zone. Most workers agree that oxygen did not constitute a significant proportion of the atmosphere until after ca. 2.45 Ga, after the Great Oxidation Event, but there is less agreement on when O2 production began, and how this may have been consumed by reduced species such as Fe(II) in the oceans. The Fe redox cycle through time has been traced using banded iron formations (BIFs), and Fe isotopes are increasingly used to constrain the conditions of Earth's paleoenvironments, including the pathways of formation of BIFs. Iron isotope analyses of BIFs from the 3.7 to 3.8 Ga Isua Supracrustal Belt (ISB), obtained by micro-sampling of magnetite-rich layers and conventional analysis, as well as by in situ femtosecond laser ablation (fs-LA-ICP-MS), indicate a consistently narrow range of non-zero δ56Fe values. Analysis of magnetite by fs-LA-ICP-MS allows for precise and accurate micron-scale analyses without the problems of orientation effects that are associated with secondary ion mass spectrometry (SIMS) analyses. Magnetite δ56Fe values range from +0.4‰ to +1.1‰ among different bands, but within individual layers magnetite grains are mostly homogeneous. Although these BIFs have been metamorphosed to amphibolite-facies, the metamorphism can neither explain the range in Fe isotope compositions across bands, nor that between hand samples. The isotopic compositions therefore reflect “primary”, low-temperature sedimentary values. The positive δ56Fe values measured from the ISB magnetites are best explained by deposition of Fe(III)-oxides produced by partial oxidation of Fe(II)-rich ocean water. A dispersion/reaction model, which accounts for rates of hydrothermal Fe(II)aq input, rates of oxidation, and rates of Fe(OH)3 settling suggests exceptionally low O2 contents, <0.001% of modern O2 contents in

  6. The iron isotope composition of enstatite meteorites: Implications for their origin and the metal/sulfide Fe isotopic fractionation factor

    NASA Astrophysics Data System (ADS)

    Wang, Kun; Savage, Paul S.; Moynier, Frédéric

    2014-10-01

    Despite their unusual chemical composition, it is often proposed that the enstatite chondrites represent a significant component of Earth’s building materials, based on their terrestrial similarity for numerous isotope systems. In order to investigate a possible genetic relationship between the Fe isotope composition of enstatite chondrites and the Earth, we have analyzed 22 samples from different subgroups of the enstatite meteorites, including EH and EL chondrites, aubrites (main group and Shallowater) and the Happy Canyon impact melt. We have also analyzed the Fe isotopic compositions of separated (magnetic and non-magnetic) phases from both enstatite chondrites and achondrites. On average, EH3-5 chondrites (δ56Fe = 0.003 ± 0.042‰; 2 standard deviation; n = 9; including previous literature data) as well as EL3 chondrites (δ56Fe = 0.030 ± 0.038‰; 2 SD; n = 2) have identical and homogeneous Fe isotopic compositions, indistinguishable from those of the carbonaceous chondrites and average terrestrial peridotite. In contrast, EL6 chondrites display a larger range of isotopic compositions (-0.180‰ < δ56Fe < 0.181‰; n = 11), a result of mixing between isotopically distinct mineral phases (metal, sulfide and silicate). The large Fe isotopic heterogeneity of EL6 is best explained by chemical/mineralogical fragmentation and brecciation during the complex impact history of the EL parent body. Enstatite achondrites (aubrites) also exhibit a relatively large range of Fe isotope compositions: all main group aubrites are enriched in the light Fe isotopes (δ56Fe = -0.170 ± 0.189‰; 2 SD; n = 6), while Shallowater is, isotopically, relatively heavy (δ56Fe = 0.045 ± 0.101‰; 2 SD; n = 4; number of chips). We take this variation to suggest that the main group aubrite parent body formed a discreet heavy Fe isotope-enriched core, whilst the Shallowater meteorite is most likely from a different parent body where core and silicate material remixed. This could be

  7. Biogeochemical Cycling of Iron Isotopes at Loihi Seamount

    NASA Astrophysics Data System (ADS)

    Rouxel, O. J.; Edwards, K. J.; Moyer, C. L.; Wheat, G.

    2007-12-01

    It is now well recognized that seafloor hydrothermal systems support diverse and unique biological communities capable of using dissolved chemical species, such as Iron (Fe), as well as mineral substrates as sources of metabolic energy. Deep-sea hydrothermal systems such as the Loihi Seamount hydrothermal field are important examples of environments where both chemical and biological oxidation of Fe can occur simultaneously and provide an ideal system in which to test hypotheses on biotic vs. abiotic origin of iron-oxide formation. Here, we applied Fe isotope systematics of hydrothermal fluids and Fe-oxide precipitates to study biogeochemical cycling of iron and the formation of microbial mats at Loihi seamount. Warm hydrothermal fluids (<60°C) and iron oxide precipitates were recovered using the DSV Jason II during FeMO 2006 cruise. Fe-isotope composition of warm hydrothermal fluids yielded δ56Fe values near 0.1‰ and are indistinguishable from basalt values defined at 0.09‰. Suspended iron oxide particles in the fluids and seafloor iron oxide sediments (microbial mats) recovered in the vicinity of the vents yielded systematically positive δ56Fe values. The enrichment in heavy isotopes between 1.05 to 1.43‰ relative to Fe(II) in vent fluids is slightly higher than those obtained for abiotic Fe oxidation (around 0.9‰) and slightly lower than for bacterial Fe oxidation at circum neutral pH (around 1.5‰). Mass balance considerations also imply that the extent of Fe(II) oxidation is very limited in the vicinity of the vents (<20%) and that most Fe(II) is oxidized later in the water column. These results are consistent with the low oxygen content of seawater (i.e. summit of Loihi is located in the OMZ) and resultant slow kinetics of abiotic Fe oxidation. In contrast, mats supported by very diffuse fluids recovered at the base of the Loihi Seamount (~ 5000m depth) have distinctly negative Fe-isotope values between -0.3 to -1.5‰. These negative values are

  8. Iron Isotope Fractionation in Artic Weathering Environments

    NASA Astrophysics Data System (ADS)

    Rouxel, O. J.; Escoube, R.; Pokrovsky, O. S.; Wisch, M.; Miller, C.

    2008-12-01

    While our current knowledge of Fe isotope systematics in rivers is still limited, Fe isotopes provide a new approach to important questions concerning Fe sources, Fe speciation and its bioavailability in the hydrological cycles. Here, we investigated several Arctic rivers for elemental and Fe-isotopic composition with specific emphasis on silicate weathering and organic C content in order to provide new insights into the delivery of trace nutrients, such as Fe, that are important for the biological productivity of the Arctic Ocean. Without such characterization of the present state of the system, future changes in the response of these river systems to global change cannot be properly evaluated. Our Fe isotope systematics results in Siberian rivers, include (1) a time-series of water samples from large rivers (Ob and Lena) focusing on the peak flow that has not yet been investigated despite its critical importance for annual budgets; (2) the colloidal fractions (1 kDa to 0.45 μm) of rivers and their estuaries in the White Sea, including the Severnaya Dvina River to assess the influence of Fe-rich colloids flocculation on the Fe isotopic composition of the estuarine waters. Dissolved iron fractions (<0.22 μm) in large rivers have restricted δ56Fe values, with the Ob River varying from -0.29 to 0.01‰, averaging -0.11‰ (n= 20) and the Lena River varying from -0.24 to -0.01‰, averaging -0.11‰ (n=15). These values are slightly lower than bulk silicate earth values (defined at 0.09‰ relative to IRMM-14) and do not display any relationships with ice break-up on the rivers. In contrast, dissolved iron fractions in the Severnaya Dvina River and its tributaries yield more positive δ56Fe values, with values ranging from -0.09 to up to 0.64‰, averaging 0.2‰ (n=19). Small swamp rivers from the South White Sea coast reveal an even higher spread of dissolved δ56Fe values, from -1.1 to +0.8‰ with some clear variations among the various colloidal fractions (1 k

  9. Copper and iron isotope fractionation during weathering and pedogenesis: Insights from saprolite profiles

    NASA Astrophysics Data System (ADS)

    Liu, Sheng-Ao; Teng, Fang-Zhen; Li, Shuguang; Wei, Gang-Jian; Ma, Jing-Long; Li, Dandan

    2014-12-01

    Iron and copper isotopes are useful tools to track redox transformation and biogeochemical cycling in natural environment. To study the relationships of stable Fe and Cu isotopic variations with redox regime and biological processes during weathering and pedogenesis, we carried out Fe and Cu isotope analyses for two sets of basalt weathering profiles (South Carolina, USA and Hainan Island, China), which formed under different climatic conditions (subtropical vs. tropical). Unaltered parent rocks from both profiles have uniform δ56Fe and δ65Cu values close to the average of global basalts. In the South Carolina profile, δ56Fe values of saprolites vary from -0.01‰ to 0.92‰ in the lower (reduced) part and positively correlate with Fe3+/ΣFe (R2 = 0.90), whereas δ65Cu values are almost constant. By contrast, δ56Fe values are less variable and negatively correlate with Fe3+/ΣFe (R2 = 0.88) in the upper (oxidized) part, where large (4.85‰) δ65Cu variation is observed with most samples enriched in heavy isotopes. In the Hainan profile formed by extreme weathering under oxidized condition, δ56Fe values vary little (0.05-0.14‰), whereas δ65Cu values successively decrease from 0.32‰ to -0.12‰ with depth below 3 m and increase from -0.17‰ to 0.02‰ with depth above 3 m. Throughout the whole profile, δ65Cu positively correlate with Cu concentration and negatively correlate with the content of total organic carbon (TOC). Overall, the contrasting Fe isotopic patterns under different redox conditions suggest redox states play the key controls on Fe mobility and isotope fractionation. The negative correlation between δ56Fe and Fe3+/ΣFe in the oxidized part of the South Carolina profile may reflect addition of isotopically light Fe. This is demonstrated by leaching experiments, which show that Fe mineral pools extracted by 0.5 N HCl, representing poorly-crystalline Fe (hydr)-oxides, are enriched in light Fe isotopes. The systematic Cu isotopic variation

  10. Fe stable isotope fractionation in modern and ancient hydrothermal Fe-Si deposits

    NASA Astrophysics Data System (ADS)

    Moeller, K.; Schoenberg, R.; Thorseth, I. H.; Øvreås, L.; Pedersen, R.

    2010-12-01

    Modern iron-silica deposits of small yellow to rust coloured mounds and chimney-like structures were found in a low-temperature venting area distal to a white smoker type hydrothermal vent site at the south-western part of the Mohns Ridge, North Atlantic. Individual stratified mm to cm thick laminated layers within these structures are largely composed of branching, twisted filaments resembling encrusted stalks of Fe-oxidising bacteria. DNA analyses have confirmed the presence of both Fe-oxidising (Mariprofundus ferrooxidans and other ζ-Proteobacteria) and Fe-reducing bacteria (Shewanellaceae). Similar morphologic features, such as several mm thick red hematite-rich laminae and micron-scale filamentous structures concentrated in discrete laminae, have also been found in Early Ordovician volcanogenic massive sulphide (VMS) hosted jasper deposits in the Løkken-Høydal area, Norway [1]. These filamentous structures are believed to be formed by Fe-oxidising bacteria similar to Mariprofundus ferrooxidans [2]. Here, we compare the Fe isotope composition of these two different types of Fe-Si deposits with the aim to gain further information about deposition mechanisms and the role of microorganisms in Fe redox cycling of deep-sea hydrothermal systems. Fe isotope compositions of the modern biogenic Fe-Si deposit vary between -2.09 and -0.66 ‰ in δ56Fe values, a range that is comparable to late Archaean to early Proterozoic banded iron formations. The ~490 Ma old Løkken jaspers show a similar variation, but with significantly higher δ56Fe values ranging from -0.39 to +0.89 ‰. The Fe isotopic composition of the Løkken jaspers clearly correlates with morphological features with the lowest δ56Fe values in layered and the highest ones in brecciform jaspers. Our data demonstrate that variations in Fe isotope compositions of the modern Fe-Si deposit cannot be explained by a single process, but rather reflect the full complexity of Fe redox cycling within deep

  11. Manganese-Chromium Isotope Systematics of Ivuna, Kainsaz and Other Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Shukolyukov, A.; Lugmair, G. W.; Bogdanovski, O.

    2003-01-01

    We have shown earlier that the bulk samples of carbonaceous chondrites [CC] reveal excesses in both Cr-53 (Cr-53*) and Cr-54 (Cr-54*) as compared to the terrestrial standard value. The Cr-53/52 ratios in bulk samples of Orgueil (CI), Murray (CM), Allende (CV), and the Bencubbin/CH-like meteorite Hammadah Al Hambra 237 (HH237) are correlated with the respective Mn/Cr ratios. In contrast to CC, HH237 is characterized by a deficit of Cr-53 (-0.15 +/- 0.10(epsilon)) at a low Mn/Cr ratio of 0.07. The HH237 data point, however, falls on the CC line. Here we report new Mn-53 - Cr-53 results for the CC Kainsaz (CO) and Ivuna (CI).

  12. Chromium and Iron Isotopic Composition of Presolar Silicon Carbide Stardust Grains

    NASA Astrophysics Data System (ADS)

    Savina, M.; Levine, J.; Dauphas, N.; Pellin, M.; Willingham, D.; Stephan, T.; Trappitsch, R.; Davis, A. M.

    2011-12-01

    Most presolar SiC stardust grains derive from Asymptotic Giant Branch (AGB) stars, which are the main source of s-process nuclides in the galaxy. s-Process nucleosynthesis is not a major contributor to iron peak nuclides. The most interesting of these isotopes from an AGB nucleosynthetic standpoint are the trace isotopes 54Cr and 58Fe, which are predicted to have deviations from average Solar System ratios of ~100% and >200%, respectively. The other isotopes of Cr and Fe are essentially unchanged by AGB stars, and are representative of the isotopic composition of the protostellar cloud from which the SiC grains formed. They are thus tracers of Galactic Chemical Evolution, and provide a benchmark for the isotopic composition of the galaxy some five to seven billion years ago. SiC grains were isolated from the Murchison meteorite using high purity reagents and techniques specifically designed to prevent contamination with terrestrial Cr and Fe. Grains from the 2-4 μm size fraction were pressed into a high purity gold foil. Chromium and iron isotopic compositions were measured by Resonance Ionization Mass Spectrometry (RIMS) using new techniques specifically developed for high precision isotopic analysis of iron-peak elements. The Cr isotopic compositions of 19 grains form a distinct group. Several grains had resolvable (>2σ) 50Cr and 53Cr deficits ranging as low as -178%. The 54Cr/ 52Cr δ-values were all within 2σ of the Solar System value, though most were slightly higher. The average δ-values for the grains were -45±31% for 50Cr, -37±21% for 53Cr, and +25±26% for 54Cr. Iron results are pending. Given that AGB stars change most Fe and Cr isotope ratios very little, and that these grains' progenitor stars formed from a few hundred million to about three billion years before the Solar System formed (assuming their initial masses were 1.5 - 3 solar masses), and that grain interstellar residence times are likely less than ~100 - 200 million years, the Fe and Cr

  13. How the projectile neutron number influences the evaporation cross section in complete fusion reactions with heavy ions

    SciTech Connect

    Wang Chengbin; Zhang Jinjuan; Ren, Z. Z.; Shen, C. W.

    2010-11-15

    The influence of the projectile neutron number on the evaporation residue cross sections for the reactions {sup 208}Pb({sup 52,54}Cr,n,2n){sup 258-261}Sg and {sup 208}Pb({sup 48,50}Ti,n,2n){sup 254-257}Rf has been studied within the framework of a fusion-fission statistical model. The results obtained with the kewpie2 code are compared with recent experimental data. The excitation functions represent the experimental results well both in the maximum value and the lactation of the peak. The calculations show that the projectile neutron number greatly influences both the capture cross section and the fusion probability.

  14. The Mn-53-Cr-53 System in CAIs: An Update

    NASA Technical Reports Server (NTRS)

    Papanastassiou, D. A.; Wasserburg, G. J.; Bogdanovski, O.

    2005-01-01

    High precision techniques have been developed for the measurement of Cr isotopes on the Triton mass spectrometer, at JPL. It is clear that multiple Faraday cup, simultaneous ion collection may reduce the uncertainty of isotope ratios relative to single Faraday cup ion collection, by the elimination of uncertainties from ion beam instabilities (since ion beam intensities for single cup collection are interpolated in time to calculate isotope ratios), and due to a greatly increased data collection duty cycle, for simultaneous ion collection. Efforts to measure Cr by simultaneous ion collection have not been successful in the past. Determinations on Cr-50-54Cr, by simultaneous ion collection on the Finnigan/ MAT 262 instrument at Caltech, resulted in large variations in extrinsic precision, for normal Cr, of up to 1% in Cr-53/Cr-52 (data corrected for mass fractionation, using Cr-50/Cr-52).

  15. Identification of an 84 Sr-depleted Carrier in Primitive Meteorites and Implications for Thermal Processing in the Solar Protoplanetary Disk

    NASA Astrophysics Data System (ADS)

    Paton, Chad; Schiller, Martin; Bizzarro, Martin

    2013-02-01

    The existence of correlated nucleosynthetic heterogeneities in solar system reservoirs is now well demonstrated for numerous nuclides. However, it has proven difficult to discriminate between the two disparate processes that can explain such correlated variability: incomplete mixing of presolar material or secondary processing of a well-mixed disk. Using stepwise acid-leaching of the Ivuna CI-chondrite, we show that unlike other nuclides such as 54Cr and 50Ti, Sr-isotope variability is the result of a carrier depleted in 84Sr. The carrier is most likely presolar SiC, which is known to have both high Sr-concentrations relative to solar abundances and extremely depleted 84Sr compositions. Thus, variability in 84Sr in meteorites and their components can be attributed to varying contributions from presolar SiC. The observed 84Sr excesses in calcium-aluminum refractory inclusions (CAIs) suggest their formation from an SiC-free gaseous reservoir, whereas the 84Sr depletions present in differentiated meteorites require their formation from material with an increased concentration of SiC relative to CI chondrites. The presence of a positive correlation between 84Sr and 54Cr, despite being hosted in carriers of negative and positive anomalies, respectively, is not compatible with incomplete mixing of presolar material but instead suggests that the solar system's nucleosynthetic heterogeneity reflects selective thermal processing of dust. Based on vaporization experiments of SiC under nebular conditions, the lack of SiC material in the CAI-forming gas inferred from our data requires that the duration of thermal processing of dust resulting in the vaporization of CAI precursors was extremely short-lived, possibly lasting only hours to days.

  16. Isotope Anomalies in the Fe-group Elements in Meteorites and Connections to Nucleosynthesis in AGB Stars

    NASA Astrophysics Data System (ADS)

    Wasserburg, G. J.; Trippella, O.; Busso, M.

    2015-05-01

    We study the effects of neutron captures in AGB stars on “Fe-group” elements, with an emphasis on Cr, Fe, and Ni. These elements show anomalies in 54Cr, 58Fe, and 64Ni in solar system materials, which are commonly attributed to supernovae (SNe). However, as large fractions of the interstellar medium (ISM) were reprocessed in AGB stars, these elements were reprocessed, too. We calculate the effects of such reprocessing on Cr, Fe, and Ni through 1.5 {{M}⊙ } and 3 {{M}⊙ } AGB models, adopting solar and 1/3 solar metallicities. All cases produce excesses of 54Cr, 58Fe, and 64Ni, while the other isotopes are little altered; hence, the observations may be explained by AGB processing. The results are robust and not dependent on the detailed initial isotopic composition. Consequences for other “Fe group” elements are then explored. They include 50Ti excesses and some production of 46,47,49Ti. In many circumstellar condensates, Ti quantitatively reflects these effects of AGB neutron captures. Scatter in the data results from small variations (granularity) in the isotopic composition of the local ISM. For Si, the main effects are instead due to variations in the local ISM from different SN sources. The problem of Ca is discussed, particularly with regard to 48Ca. The measured data are usually represented assuming terrestrial values for 42Ca/44Ca. Materials processed in AGB stars or sources with variable initial 42Ca/44Ca ratios can give apparent 48Ca excesses/deficiencies, attributed to SNe. The broader issue of galactic chemical evolution is also discussed in view of the isotopic granularity in the ISM.

  17. IDENTIFICATION OF AN {sup 84}Sr-DEPLETED CARRIER IN PRIMITIVE METEORITES AND IMPLICATIONS FOR THERMAL PROCESSING IN THE SOLAR PROTOPLANETARY DISK

    SciTech Connect

    Paton, Chad; Schiller, Martin; Bizzarro, Martin E-mail: schiller@snm.ku.dk

    2013-02-01

    The existence of correlated nucleosynthetic heterogeneities in solar system reservoirs is now well demonstrated for numerous nuclides. However, it has proven difficult to discriminate between the two disparate processes that can explain such correlated variability: incomplete mixing of presolar material or secondary processing of a well-mixed disk. Using stepwise acid-leaching of the Ivuna CI-chondrite, we show that unlike other nuclides such as {sup 54}Cr and {sup 50}Ti, Sr-isotope variability is the result of a carrier depleted in {sup 84}Sr. The carrier is most likely presolar SiC, which is known to have both high Sr-concentrations relative to solar abundances and extremely depleted {sup 84}Sr compositions. Thus, variability in {sup 84}Sr in meteorites and their components can be attributed to varying contributions from presolar SiC. The observed {sup 84}Sr excesses in calcium-aluminum refractory inclusions (CAIs) suggest their formation from an SiC-free gaseous reservoir, whereas the {sup 84}Sr depletions present in differentiated meteorites require their formation from material with an increased concentration of SiC relative to CI chondrites. The presence of a positive correlation between {sup 84}Sr and {sup 54}Cr, despite being hosted in carriers of negative and positive anomalies, respectively, is not compatible with incomplete mixing of presolar material but instead suggests that the solar system's nucleosynthetic heterogeneity reflects selective thermal processing of dust. Based on vaporization experiments of SiC under nebular conditions, the lack of SiC material in the CAI-forming gas inferred from our data requires that the duration of thermal processing of dust resulting in the vaporization of CAI precursors was extremely short-lived, possibly lasting only hours to days.

  18. High precision titanium isotope measurements on geological samples by high resolution MC-ICPMS

    NASA Astrophysics Data System (ADS)

    Leya, Ingo; Schönbächler, Maria; Wiechert, Uwe; Krähenbühl, Urs; Halliday, Alex N.

    2007-05-01

    A method has been developed for the precise and reproducible measurement of Ti isotopes in natural materials using high resolution MC-ICPMS. Instrumental mass fractionation is internally corrected using 49Ti/47Ti. Replicate measurements of synthetic standard solutions, terrestrial rocks, and the carbonaceous chondrite Allende yield a long-term reproducibility (2[sigma]) of 0.28[var epsilon], 0.34[var epsilon], and 0.28[var epsilon] for 50Ti/47Ti, 48Ti/47Ti, and 46Ti/47Ti, respectively. Isobaric interferences from 46,48Ca+, 50V+, 50Cr+, and doubly charged Zr can be corrected for reliably in separated Ti solutions with Ca/Ti < 5, V/Ti < 0.3, Cr/Ti < 0.2, and Zr/Ti < 1, respectively. Such elemental ratios are achieved easily in most samples using the anion-exchange procedure presented. Single and double charged polyatomic ions can either be resolved, e.g., 14N36Ar+, or do not compromise the measurements. The method has been successfully applied to terrestrial rocks, meteorites, and various mineral separates. Terrestrial samples and standards agree within analytical uncertainties but are consistently different from the recommended values of Niederer et al. [F.R. Niederer, D.A. Papanastassiou, G.J. Wasserburg, Geochim. Cosmochim. Acta 45 (1981) 1017] with the largest effect on 50Ti/47Ti. The new results provide evidence that the recommended terrestrial 50Ti/47Ti is not well constrained; our data are higher by ~13[var epsilon] than the recommended value. Better agreement is found with the values recommended by Heydegger et al. [H.R. Heydegger, J.J. Foster, W. Compston, Earth Planet. Sci. Lett. 58 (1982) 406]. Our best estimate for the isotopic composition of terrestrial Ti (relative to 49Ti/47Ti = 0.749766) is: 50Ti/47Ti = 0.73010, 48Ti/47Ti = 10.06884, and 46Ti/47Ti = 1.09325. This corresponds to an atomic weight of 47.877, significantly different from the value of 47.867 recommended by IUPAC. A 50Ti/47Ti anomaly for bulk Allende of 3.37 ± 0.51[var epsilon] is found

  19. Identification of biologically recycled continental materials in banded iron formations

    NASA Astrophysics Data System (ADS)

    Li, W.; Beard, B. L.; Johnson, C.

    2015-12-01

    The controversy on the origin of banded iron formations (BIFs) has lasted for many decades. Studies prior to the 1970s suggested that Fe in BIFs was supplied from continental riverine inputs[1], but discovery of midocean ridge hydrothermal systems in the 1970s and identification of positive Eu anomaly in BIF samples led to an alternative model where hydrothermal vents provided Fe in BIFs[2]. Although the latter model has became widely accepted, it should be noted that interpretations of Fe sources for BIFs using the abundance and isotopic composition of rare earth elements (REEs) are based on an assumption that transport and deposition of REEs and Fe were coupled. We address the question of Fe sources and pathways for BIFs by combining stable Fe isotopes with radiogenic Nd isotopes as well as REE measurements to test proposals that Fe in BIFs was hydrothermally sourced. The samples investigated are from a type section of the Dales Gorge member of the 2.5 Ga Brockman Iron Formation, the world's most extensive Superior-type BIF that represents the climax of BIF deposition in the geologic record. Large variations were observed in both Fe and Nd isotope compositions of the BIF samples, and there is a positive correlation between the bulk rock ɛNd and δ56Fe values. In addition, there is a negative corelation between ɛNd and Sm/Nd ratios. In order to explain the observed correlations in those isotopic and elemental data, a two-component model, where mixing between a high ɛNd, low Sm/Nd hydrothermal endmember and a low ɛNd, low δ56Fe, but high Sm/Nd continental endmember occurred prior to deposition of the BIF, is required. The low-δ56Fe, high-Sm/Nd endmember is best explained by microbial dissimilatory iron reduction (DIR) in the coastal sediments, which fractionated Fe isotopes and REEs and released these components back to water column that were ultimately precipitated in BIFs. The range and distribution of ɛNdvalues in the BIF samples suggest that the amount

  20. Stable isotopes as a tool to apportion atmospheric iron.

    PubMed

    Majestic, Brian J; Anbar, Ariel D; Herckes, Pierre

    2009-06-15

    Identification of atmospheric iron is a key parameter to understanding the source of iron in urban and remote areas. Atmospheric deposition of desert dust, which also can include an anthropogenic component, is a primary nutrient source for most of the open ocean. To better assess particulate matter (PM) sources specific to iron, we measured the iron isotopic composition of aerosols in two size fractions: PM with aerodynamic diameters less than 2.5 microm and less than 10 microm (PM2.5 and PM10, respectively). Using colocated samplers, atmospheric aerosol samples were collected in the U.S. desert Southwest at a mixed suburban/agricultural site near Phoenix, AZ. The measurements are presented as delta56Fe relative to the IRMM-014 (Institute for Reference Materials and Measurements) standard. Using multiple collector inductively coupled plasma mass spectrometry, we found differences in iron isotopic composition within the PM10 aerosol. Half of the PM10 samples had an iron isotopic signature similar to crustal material (+0.03 per thousand), which implicates wind-blown soil-dust as the primary source. The other PM10 samples showed a lighter iron isotopic composition, centered at -0.18 per thousand. Further analysis showed thatthe lighter iron was associated with winds originating from the southwest. This strongly suggests that there is a different PM10 source in this direction, with a distinct iron isotopic composition. The iron in the PM2.5 samples was usually substantially lighter than the corresponding PM10 samples, which is consistent with coarse and fine particles having different sources, again with distinctively different isotopic compositions. The magnitude of the iron isotopic difference between the PM10 and the PM2.5 size fractions (delta56Fe(PM10) - delta56Fe(PM2.5)) correlated with the PM2.5 concentrations of elements known to be emitted from industrial sources (Pb, Cd, As, V, and Cr). This observation implies that the isotopically light iron is created or

  1. HZE Radiation Leukemogenesis in Mice

    NASA Astrophysics Data System (ADS)

    Peng, Yuanlin

    Radiation exposure is a risk factor for acute myeloid leukemia (AML). The Leukemogenesis NSCOR was developed to compare this risk for low LET vs HZE radiations as a means to better assess the leukemia risk to astronauts posed by space radiation. Individual projects within the NSCOR explore HZE radiation leukemogenesis in murine model systems and extend the findings to AML in humans. AML sensitive CBA/CaJ mice have been irradiated with 1 GeV 56 Fe particles at NSRL and with 137 Cs gamma-rays at Colorado State University and followed to 800 days of age for the development of AML. Molecular and cytogenetic analyses of HZE- and gamma-induced AML, including assays for chromosomal aberrations, PU.1 deletion, gene expression, array CGH and microsatellite instability are ongoing. Preliminary data indicate that 56 Fe particles are no more effective in inducing AML or shortening lifespan than gamma-rays. Studies designed to address the individual molecular steps in leukemogenesis and determine the effects of radiation and genetic background on each step have been initiated using knockout mice. Deletion of the PU.1 gene on mouse chromosome 2 is a critical step in this murine model of radiation leukemogenesis. Two of the three HZE-induced AMLs that could be assayed and thirteen of fourteen γ-induced AMLs had PU.1 loss as determined by Fluorescence in Situ Hybridization (FISH). We have found that AML sensitive CBA/CaJ mice have a higher incidence of Chr. 2 deletion in bone marrow cells following 56 Fe irradiation than AML resistant C57BL/6 mice. This study is being extended to proton irradiated mice. Our preliminary results indicate that microsatellite instability may be common in HZE irradiated progenitor cells. To determine if these cytogenetic changes can be induced in human myeloid progenitor cells by gamma, proton or HZE irradiation we are generating NOD/SCID mice that have been "humanized" by being transplanted with human hematopoietic stem cells. We are currently

  2. A non-traditional isotope study of plagiogranite and rhyo-dacite suites: insights into mid ocean ridge magma chamber processes (Invited)

    NASA Astrophysics Data System (ADS)

    Lundstrom, C.; Huggett, N.; Perfit, M. R.; Zambardi, T.

    2013-12-01

    The eruption of silicic volcanic rocks in the mid-ocean ridge environment, although rare, provides an important observation for understanding MOR magma chamber processes. Although axially erupted MORB are quite homogeneous geochemically, this likely reflects mixing and reaction from the magma lens axis at only slightly variable temperature. Differentiation occurs along the colder 'wings' of the magma lens and rhyo-dacite suites show mixing trends with normal MORB. Both plagiogranites in ophiolites and erupted rhyodacites provide evidence of extensive magma evolution at MORs. Yet, whether silicic eruptives in MOR environments are equivalent to plagiogranites is unknown. Here we compare the non-traditional isotope ratios of Fe and Si in a plagiogranite suite from Troodos (Cyprus) with rhyo-dacite suites from the Galapagos Spreading Center, the Juan de Fuca-Blanco ridge-transform intersection [RTI], and the 9°N EPR overlapping spreading center [OSC]) to shed light on the origin of oceanic silicic rocks. Within the eastern Troodos Ophiolite we collected 14 samples from a 700m transect from gabbros through to plagiogranites (which immediately transition to sheeted dikes). Indeed, Troodos geologic maps show plagiogranites ubiquitously occur at the upper gabbro-sheeted dike contact. Silica content ranges from ~45 wt. % in the gabbros to 75 wt. % in the most evolved plagiogranites. Notably, iron ratios increase (become heavier) with increasing, up-section distance from the gabbros (d56Fe ranges from -0.05 to 0.40). This spatial pattern is consistent with the prediction of thermal diffusion occurring within a temperature gradient in a MOR magma lens although other explanations are possible. Because there is a spatial progression in SiO2 from gabbro to plagiogranite, these isotope ratios also increase with SiO2. Notably, within the 3 silicic MOR systems, d56Fe and d30Si exhibit the same relationship becoming isotopically heavier with increasing silica content (d30Si ranges

  3. Coupled sulfur, iron and molybdenum isotope data from black shales of the Teplá-Barrandian unit argue against deep ocean oxygenation during the Ediacaran

    NASA Astrophysics Data System (ADS)

    Kurzweil, Florian; Drost, Kerstin; Pašava, Jan; Wille, Martin; Taubald, Heinrich; Schoeckle, Daniel; Schoenberg, Ronny

    2015-12-01

    The Earth's atmosphere and hydrosphere changed from an Archean anoxic to a modern oxygenated world in two major steps, the Paleoproterozoic Great Oxidation Event (2.4-2.3 billion years ago) and the Neoproterozoic Oxidation Event (0.8-0.5 billion years ago). Both events had a strong influence on the availability of redox sensitive and bio-essential metals within the ocean and are, thus, strongly linked to fundamental biological innovations and diversification. Biological diversification during the Precambrian-Cambrian transition between 555 and 540 million years ago may have been driven by ocean-atmosphere oxygenation. The exact timing and the extent of (deep) ocean oxygenation within this time period remains unresolved though. Here we present major and trace element compositions as well as Mo, S and Fe isotopic data of organic-rich black shales from the Teplá-Barrandian unit, Czech Republic. New in situ zircon U-Pb ages provide a maximum depositional age of 559.8 ± 3.8 million years. Black shales with strong metal enrichment show low δ56Fe values due to the dominance of authigenic pyrite-Fe with δ56Fe values around -0.6‰ over detrital Fe with δ56Fe values around 0.1‰. Samples with lower authigenic metal enrichment show relatively low Mo/TOC ratios and increasing δ34S values, which is interpreted to reflect basinal restriction and longer seawater renewal times. In analogy to the modern Black Sea, the accompanied depletion of basinal Moaq due to near quantitative Mo removal might have led to the preservation of the seawater δ98Mo in the respective black shales. Our best estimate for this seawater Mo isotopic composition <560 million years ago is +1.2‰ in δ98Mo, which is nearly identical to seawater δ98Mo values inferred from Mid-Proterozoic black shales. The lack of higher δ98Mo values in black shales (and seawater) argues against contemporaneous Mn oxide formation in well oxygenated deep sea settings, which would preferentially adsorb isotopically

  4. Iron isotope fractionation during sulfide-rich felsic partial melting in early planetesimals

    NASA Astrophysics Data System (ADS)

    Wang, Kun; Day, James M. D.; Korotev, Randy L.; Zeigler, Ryan A.; Moynier, Frédéric

    2014-04-01

    New Fe isotope data of feldspar-rich meteorites Graves Nunataks 06128 and 06129 (GRA 06128/9) reveal that they are the only known examples of crustal materials with isotopically light Fe isotope compositions (δFe56=-0.08±0.06‰; δ56Fe is defined as the per mille deviation of a sample's 56Fe/54Fe ratio from the IRMM-014 standard) in the Solar System. In contrast, associated brachinites, as well as brachinite-like achondrites, have Fe isotope compositions (δFe56=+0.01±0.02‰) that are isotopically similar to carbonaceous chondrites and the bulk terrestrial mantle. In order to understand the cause of Fe isotope variations in the GRA 06128/9 and brachinite parent body, we also report the Fe isotope compositions of metal, silicate and sulfide fractions from three ordinary chondrites (Semarkona, Kernouve, Saint-Séverin). Metals from ordinary chondrites are enriched in the heavier isotopes of Fe (average δFe56=0.15‰), sulfide fractions are enriched in the lighter isotopes of Fe (average δFe56=-0.14‰), and the δ56Fe values of the silicates are coincident with that of the bulk rock (average δFe56=0.03‰). The enrichment of light isotopes of Fe isotopes in GRA 06128/9 is consistent with preferential melting of sulfides in precursor chondritic source materials leading to the formation of Fe-S-rich felsic melts. Conceptual models show that melt generation to form a GRA 06128/9 parental melt occurred prior to the onset of higher-temperature basaltic melting (<1200 °C) in a volatile-rich precursor and led to the generation of buoyant felsic melt with a strong Fe-S signature. These models not only reveal the origin of enrichment in light isotopes of Fe for GRA 06128/9, but are also consistent with petrological and geochemical observations, experimental studies for the origin of Fe-S-rich felsic melts, and for the cessation of early melting on some asteroidal parent bodies because of the effective removal of the major radioactive heat-source, 26Al. The mode of

  5. Evidence for high-temperature fractionation of lithium isotopes during differentiation of the Moon

    NASA Astrophysics Data System (ADS)

    Day, James M. D.; Qiu, Lin; Ash, Richard D.; McDonough, William F.; Teng, Fang-Zhen; Rudnick, Roberta L.; Taylor, Lawrence A.

    2016-06-01

    Lithium isotope and abundance data are reported for Apollo 15 and 17 mare basalts and the LaPaz low-Ti mare basalt meteorites, along with lithium isotope data for carbonaceous, ordinary, and enstatite chondrites, and chondrules from the Allende CV3 meteorite. Apollo 15 low-Ti mare basalts have lower Li contents and lower δ7Li (3.8 ± 1.2‰; all uncertainties are 2 standard deviations) than Apollo 17 high-Ti mare basalts (δ7Li = 5.2 ± 1.2‰), with evolved LaPaz mare basalts having high Li contents, but similar low δ7Li (3.7 ± 0.5‰) to Apollo 15 mare basalts. In low-Ti mare basalt 15555, the highest concentrations of Li occur in late-stage tridymite (>20 ppm) and plagioclase (11 ± 3 ppm), with olivine (6.1 ± 3.8 ppm), pyroxene (4.2 ± 1.6 ppm), and ilmenite (0.8 ± 0.7 ppm) having lower Li concentrations. Values of δ7Li in low- and high-Ti mare basalt sources broadly correlate negatively with 18O/16O and positively with 56Fe/54Fe (low-Ti: δ7Li ≤4‰; δ56Fe ≤0.04‰; δ18O ≥5.7‰; high-Ti: δ7Li >6‰ δ56Fe >0.18‰ δ18O <5.4‰). Lithium does not appear to have acted as a volatile element during planetary formation, with subequal Li contents in mare basalts compared with terrestrial, martian, or vestan basaltic rocks. Observed Li isotopic fractionations in mare basalts can potentially be explained through large-degree, high-temperature igneous differentiation of their source regions. Progressive magma ocean crystallization led to enrichment in Li and δ7Li in late-stage liquids, probably as a consequence of preferential retention of 7Li and Li in the melt relative to crystallizing solids. Lithium isotopic fractionation has not been observed during extensive differentiation in terrestrial magmatic systems and may only be recognizable during extensive planetary magmatic differentiation under volatile-poor conditions, as expected for the lunar magma ocean. Our new analyses of chondrites show that they have δ7Li ranging between -2.5‰ and 4

  6. Two- and three-dimensional models for risk assessment of radiation-enhanced colorectal tumorigenesis.

    PubMed

    Roig, Andres I; Hight, Suzie K; Shay, Jerry W

    2009-01-01

    Astronauts may be at an increased risk for developing colorectal cancer after a prolonged interplanetary mission given the potential for greater carcinogenic effects of radiation to the colon. In addition, with an increase in age, there is a greater incidence of premalignant colon adenomas with age. In the present study, we have compared the effects of radiation on human colon epithelial cells in two-dimensional (2D) monolayer culture, in three-dimensional (3D) culture, and in intact human colon tissue biopsies. Immortalized colon epithelial cells were irradiated at the NASA Space Radiation Laboratory (NSRL) with either 1 Gy 1 GeV/nucleon (56)Fe particles or 1 Gy 1 GeV/nucleon protons and were stained at various times to assess DNA damage and repair responses. The results show more persisting damage at 24 h with iron-particle radiation compared to protons. Similar results were seen in 3D colon epithelial cell cultures in which (56)Fe-particle-irradiated specimens show more persisting damage at 24 h than those irradiated with low-LET gamma rays. We compared these results to those obtained from human colon tissue biopsies irradiated with 1 Gy gamma rays or 1 Gy 1 GeV (56)Fe particles. Observations of radiation-induced DNA damage and repair in gamma-irradiated specimens revealed more pronounced early DNA damage responses in the epithelial cell compartment compared to the stromal cell compartment. After low-LET irradiation, the damage foci mostly disappeared at 24 h. Antibodies to more than one type of DNA repair factor display this pattern of DNA damage, and staining of nonirradiated cells with nonphosphorylated DNA-PKcs shows a predominance of epithelial staining over stromal cells. Biopsy specimens irradiated with high-LET radiations also show a pattern of predominance of the DNA damage response in the highly proliferative epithelial cell compartment. Persistent unrepaired DNA damage in colon epithelial cells and the differing repair responses between the epithelial

  7. Energy dissipation in heavy systems: the transition from quasi-elastic to deep-inelastic scattering

    SciTech Connect

    Rehm, K.E.; van den Berg, A.; Kolata, J.J.; Kovar, D.G.; Kutschera, W.; Rosner, G.; Stephans, G.S.F.; Yntema, J.L.; Lee, L.L.

    1984-01-01

    The interaction of medium mass projectiles (A = 28 - 64) with /sup 208/Pb has been studied using a split-pole spectrograph which allows single mass and charge identification. The reaction process in all systems studied so far is dominated by quasi-elastic neutron transfer reactions, especially at incident energies in the vicinity of the Coulomb barrier. In addition to the quasi-elastic component deep inelastic contributions are present in all reaction channels. The good mass and charge separation allows to generate Wilczynski plots for individual channels; for the system /sup 48/Ti + /sup 208/Pb we observe that the transition between the quasi-elastic and deep-inelastic reactions occurs around Q = -(30 to 35) MeV.

  8. Atomic mass and double-β-decay Q value of 48Ca

    NASA Astrophysics Data System (ADS)

    Redshaw, Matthew; Bollen, Georg; Brodeur, Maxime; Bustabad, Scott; Lincoln, David L.; Novario, Samuel J.; Ringle, Ryan; Schwarz, Stefan

    2012-10-01

    The possibility of detecting neutrinoless double-β-decay (0νββ-decay) in experiments that are currently in operation or under development provides the exciting opportunity to determine the Dirac or Majorana nature of the neutrino and its absolute mass scale. An important datum for interpreting 0νββ-decay experimental results is the Q value of the decay. Using Penning trap mass spectrometry we have measured the atomic mass of 48Ca to be M[48Ca] = 47.952 522 76(21) u which, combined with the mass of 48Ti evaluated by Audi [Nucl. Phys. ANUPABL0375-947410.1016/j.nuclphysa.2003.11.003 729, 337 (2003)], provides a new determination of the 48Ca ββ-decay Q value: Qββ = 4262.96(84) keV.

  9. Type II Supernova Matter in a Silicon Carbide Grain from the Murchison Meteorite

    PubMed

    Hoppe; Strebel; Eberhardt; Amari; Lewis

    1996-05-31

    The circumstellar silicon carbide (SiC) grain X57 from the Murchison meteorite contains large amounts of radiogenic calcium-44 (20 times its solar system abundance) and has an anomalous silicon isotopic composition, different from other circumstellar SiC grains. Its inferred initial 44Ti/Si and 44Ti/48Ti ratios are 1.6 x 10(-4) and 0.37. In addition, it contains radiogenic magnesium-26; the inferred initial 26Al/27Al ratio is 0.11. The isotopic and elemental data of X57 can be explained by selective mixing of matter from different zones of a typical type II supernova of 25 solar masses during its explosion. The high 44Ti/Si ratio requires contributions from the innermost nickel zone of the supernova to the SiC condensation site, as similarly suggested by astronomical observations.

  10. Band gap states of Ti, V, and Cr in 4H-silicon carbide

    NASA Astrophysics Data System (ADS)

    Achtziger, Norbert; Witthuhn, Wolfgang

    1997-07-01

    Band gap states of Ti, V, and Cr in n-type 4H-SiC were investigated by radiotracer deep level transient spectroscopy (DLTS). Doping with the radioactive isotopes 48V and 51Cr was done by recoil implantation followed by annealing (1600 K). Repeated DLTS measurements during the elemental transmutation of these isotopes to 48Ti and 51V, respectively, reveal the corresponding concentration changes of band gap states. Thus, six levels are identified in the band gap: Cr levels at 0.15, 0.18, and 0.74 eV, one V level at 0.97 eV, and two Ti levels at 0.13 and 0.17 eV below the conduction band edge.

  11. Band gap states of V and Cr in 6H-silicon carbide

    NASA Astrophysics Data System (ADS)

    Achtziger, N.; Grillenberger, J.; Witthuhn, W.

    Band gap states of Ti, V and Cr in n-type 6H-SiC were investigated by radiotracer deep level transient spectroscopy (DLTS). Doping with the radioactive isotopes 48V and 51Cr was done by recoil implantation followed by annealing (1600 K). Repeated DLTS measurements during the elemental transmutation of these isotopes to 48Ti and 51V respectively revealed the corresponding concentration changes of band gap states. Thus, three levels were identified in the band gap: a Cr level at 0.54 eV and two V levels at 0.71 and 0.75 eV below the conduction band edge. There are no deep levels of Ti in the upper part of the band gap.

  12. Giant Dipole Resonance decay of hot rotating 88Mo

    NASA Astrophysics Data System (ADS)

    Ciemała, M.; Kmiecik, M.; Maj, A.; Kravchuk, V. L.; Gramegna, F.; Barlini, S.; Casini, G.; Camera, F.

    2014-03-01

    An experiment focusing on study of the properties of hot rotating compound nucleus of 88Mo was performed in LNL Legnaro using 48Ti beam at energies of 300 and 600 MeV on 40Ca target. The compound nucleus was produced at the temperatures of 3 and 4.5 MeV, with angular momentum distribution with lmax > 60 ħ (i.e. exceeding the crtical angular momentum for fission). High-energy gamma rays, measured in coincidence with evaporation residues and alpha particles, were analyzed with the statistical model. The GDR parameters were obtained from the best fit to the data, which allowed investigating an evolution of the GDR width up to high temperatures.

  13. Giant dipole resonance in 88Mo from phonon damping model strength functions averaged over temperature and angular momentum distributions

    NASA Astrophysics Data System (ADS)

    Dinh Dang, N.; Ciemala, M.; Kmiecik, M.; Maj, A.

    2013-05-01

    The line shapes of giant dipole resonance (GDR) in the decay of the compound nucleus 88Mo, which is formed after the fusion-evaporation reaction 48Ti + 40Ca at various excitation energies E* from 58 to 308 MeV, are generated by averaging the GDR strength functions predicted within the phonon damping model (PDM) using the empirical probabilities for temperature and angular momentum. The average strength functions are compared with the PDM strength functions calculated at the mean temperature and mean angular momentum, which are obtained by averaging the values of temperature and angular momentum using the same temperature and angular momentum probability distributions, respectively. It is seen that these two ways of generating the GDR linear line shape yield very similar results. It is also shown that the GDR width approaches a saturation at angular momentum J≥ 50 ℏ at T=4 MeV and at J≥ 70 ℏ at any T.

  14. Domain switching of fatigued ferroelectric thin films

    SciTech Connect

    Tak Lim, Yun; Yeog Son, Jong E-mail: hoponpop@ulsan.ac.kr; Shin, Young-Han E-mail: hoponpop@ulsan.ac.kr

    2014-05-12

    We investigate the domain wall speed of a ferroelectric PbZr{sub 0.48}Ti{sub 0.52}O{sub 3} (PZT) thin film using an atomic force microscope incorporated with a mercury-probe system to control the degree of electrical fatigue. The depolarization field in the PZT thin film decreases with increasing the degree of electrical fatigue. We find that the wide-range activation field previously reported in ferroelectric domains result from the change of the depolarization field caused by the electrical fatigue. Domain wall speed exhibits universal behavior to the effective electric field (defined by an applied electric field minus the depolarization field), regardless of the degree of the electrical fatigue.

  15. Pauli-blocking effects in neutron-alpha reactions

    SciTech Connect

    Avrigeanu, M. |; Avrigeanu, V.; Antonov, A.N.; Chadwick, M.B.; Hodgson, P.E.; Stoitsov, M.V.

    1994-06-01

    We present a knockout model for direct (n,{alpha}) reactions in which the residual nucleus is left in a continuum excited state. The interaction of the neutron with a preformed alpha particle inside the nucleus is related to the free neutron-alpha scattering cross-section, with modifications to account for nuclear medium effects, including Fermi motion, Pauli-blocking, and barrier penetration. Phase space restrictions for the four nucleons of the alpha-particle after the knockout are imposed by a Pauli-blocking function. We apply this model, along with evaporation contributions, to analyze excitation functions of (n,{alpha} reactions on {sup 48}Ti, {sup 51}V, {sup 52}Cr, {sup 54}Fe, {sup 55}Mn, and {sup 59}Co. Good agreement is obtained between our calculations and experimental measurements. Values for the local Fermi energy in the region from where knockout occurs indicate a surface reaction.

  16. Centrifugal stretching along the ground state band of {sup 168}Hf

    SciTech Connect

    Costin, A.; Pietralla, N.; Reese, M.; Moeller, O.; Ai, H.; Casten, R. F.; Heinz, A.; McCutchan, E. A.; Meyer, D. A.; Qian, J.; Werner, V.; Dusling, K.; Fitzpatrick, C. R.; Guerdal, G.; Petkov, P.; Rainovski, G.

    2009-02-15

    The lifetimes of the J{sup {pi}}=4{sup +}, 6{sup +}, 8{sup +}, and 10{sup +} levels along the ground state band in {sup 168}Hf were measured by means of the recoil distance Doppler shift (RDDS) method using the New Yale Plunger Device (NYPD) and the SPEEDY detection array at Wright Nuclear Structure Laboratory of Yale University. Excited states in {sup 168}Hf were populated using the {sup 124}Sn({sup 48}Ti,4n) fusion evaporation reaction. The new lifetime values are sufficiently precise to clearly prove the increase of quadrupole deformation as a function of angular momentum in the deformed nucleus {sup 168}Hf. The data agree with the predictions from the geometrical confined {beta}-soft (CBS) rotor model that involves centrifugal stretching in a soft potential.

  17. OMC studies for the matrix elements in ββ decay

    SciTech Connect

    Zinatulina, D.; Brudanin, V.; Egorov, V.; Shirchenko, M.; Vasiliev, R.; Yyutlandov, I.; Briançon, Ch.; Petitjean, C.

    2013-12-30

    Energy and time spectra of gamma-rays following μ-capture in natural Kr, Se, Cd and Sm, as well as isotopic enriched {sup 82}Kr, {sup 76}Se, {sup 106}Cd and {sup 150}Sm, have been measured. Total life-times of muons in different isotopes, as well as partial μ-capture rates to the excited states of {sup 48}Sc, {sup 76}As and {sup 106}Ag, were extracted. These results are discussed in the context of the double-beta decay matrix elements. The data are also compared with data from theoretical calculations and with data from charge-exchange reactions on {sup 48}Ti. It is the first time that μ-capture and charge-exchange reaction data are being compared in the context of ββ decay.

  18. ISOCHRONS IN PRESOLAR GRAPHITE GRAINS FROM ORGUEIL

    SciTech Connect

    Zinner, Ernst; Jadhav, Manavi

    2013-05-10

    Primitive meteorites contain tiny dust grains that condensed in stellar outflows and explosions. These stardust grains can be extracted from their host meteorites and studied in detail in the laboratory. We investigated depth profiles of the Al-Mg, Ca-K, and Ti-Ca isotopic systems obtained during NanoSIMS isotopic analysis of presolar graphite grains from the CI carbonaceous meteorite Orgueil. Large {sup 26}Al/{sup 27}Al, {sup 41}Ca/{sup 40}Ca, and {sup 44}Ti/{sup 48}Ti ratios, inferred from {sup 26}Mg, {sup 41}K, and {sup 44}Ca excesses from the decay of the short-lived radioisotopes {sup 26}Al, {sup 41}Ca, and {sup 44}Ti, indicate a supernova (SN) origin. From the depth distribution of the radiogenic isotopes and the stable isotopes of their parent elements we constructed isochron-type correlation plots. The plots indicate quantitative retention of radiogenic {sup 26}Mg, {sup 41}K, and {sup 44}Ca in most grains. Deviations from straight lines in the Al-Mg and Ca-K plots can be explained by contamination with {sup 27}Al and isotopically normal Ca, respectively. For the Ti-Ca system in some grains, the lack of parent-daughter correlation indicates either redistribution of radiogenic {sup 44}Ca or heterogeneity in the initial {sup 44}Ti/{sup 48}Ti ratio. We also obtained Si isotopic depth profiles in three graphite grains with large {sup 29}Si and {sup 30}Si excesses, for which a SN origin has been proposed. In two grains no Si-rich subgrains are observed; in the third grain with an apparent Si-rich subgrain the anomalous Si isotopic ratios in the subgrain are the same as in the rest of the graphite host. Our studies show that by measuring depth profiles, information on presolar grains can be obtained that cannot be obtained by whole-grain analysis.

  19. New Titanium Isotope Data for Allende and Efremovka CAIs

    NASA Astrophysics Data System (ADS)

    Leya, Ingo; Schönbächler, Maria; Krähenbühl, Urs; Halliday, Alex N.

    2009-09-01

    We measured the titanium (Ti) isotope composition, i.e., 50Ti/47Ti, 48Ti/47Ti, and 46Ti/47Ti, in five calcium-rich-aluminum-rich refractory inclusions (CAIs) from the oxidized CV3 chondrite Allende and in two CAIs from the reduced CV3 chondrite Efremovka. Our data indicate that CAIs are enriched in 50Ti/47Ti and 46Ti/47Ti and are slightly depleted in 48Ti/47Ti compared to normal Ti defined by ordinary chondrites, eucrites, ureilites, mesosiderites, Earth, Moon, and Mars. Some CAIs have an additional 50Ti excess of ~8ɛ relative to bulk carbonaceous chondrites, which are enriched in 50Ti by ~2ɛ relative to terrestrial values, leading to a total excess of ~10ɛ. This additional 50Ti excess is correlated with nucleosynthetic anomalies found in 62Ni and 96Zr, all indicating an origin from a neutron-rich stellar source. Bulk carbonaceous chondrites show a similar trend, however, the extent of the anomalies is either less than or similar to the smallest anomalies seen in CAIs. Mass balance calculations suggest that bulk Allende Ti possibly consists of a mixture of at least two Ti components, anomalous Ti located in CAIs and a normal component possibly for matrix and chondrules. This argues for a heterogeneous distribution of Ti isotopes in the solar system. The finding that anomalous Ti is concentrated in CAIs suggests that CAIs formed in a specific region of the solar system and were, after their formation, not homogeneously redistributed within the solar system. Combining the CAI data with improved model predictions for early solar system irradiation effects indicates that a local production scenario for the relatively short lived radionuclides can be excluded, because the production of, e.g., 10Be, 26Al, and 41Ca, would result in a significant collateral shift in Ti isotopes, which is not seen in the measured data.

  20. New method for calculation of nuclear cluster structure of nuclei

    NASA Astrophysics Data System (ADS)

    Ibishi, A. I.

    2005-05-01

    In the calculations of the many-nucleon bound states, using the realistic nucleon-nucleon potential, and a three- and four-nucleon potential, the Exact Many-Body Nuclear Cluster Model (EMBNCM) was found to give accurate results, that converege much more rapidly, than those obtained by the Faddeev equation calculations. With the use of realistic nucleon-nucleon potentials, and many-nucleon potentials, containing strong tensor, Majorana, and repulsive core components, the many-body cluster structure of 16O, 27Al, 44Ti, and 48Ti is discussed. In 27Al(p,x)Na reactions we assume that two different nuclear cluster structures of 27Al, gives us two different isotopes of Na: 22Na and 24Na. But the most important result is the existence of two different permutations symmetries of 27Al. Using new method for calculation of nuclear cluster structure of 27Al, we have found two different nuclear cluster structures of 27Al: 24Na+3He and 25Na+d. The internal nuclear cluster wave functions of different nuclear cluster models (nuclear cluster isomers) of the same isotope are not equivalent, if we take into account Many-Body Nuclear Forces, such as 3BF and 4BF. The core clusters of 16O, 27Al, 44Ti, and 48Ti nuclei have a trigonal-pyramide Td, D2d, and C3v symmetry, while exterior clusters in 16O and 27Al[(24Na +3 He)model] nuclei have a trigonal symmetry C2v, and D3h. We have developed a new system of Jacobi coordinates for our EMBNCM model with the symmetry above. The new computer code for determination of direct nuclear cluster reactions has been written in Mathematica 5 programming language. We have found a high level of dependence of the nuclear cluster wave functions from the center of mass and cluster effects.

  1. New method for calculation of nuclear cluster structure of nuclei

    SciTech Connect

    Ibishi, A.I.

    2005-05-06

    In the calculations of the many-nucleon bound states, using the realistic nucleon-nucleon potential, and a three- and four-nucleon potential, the Exact Many-Body Nuclear Cluster Model (EMBNCM) was found to give accurate results, that converege much more rapidly, than those obtained by the Faddeev equation calculations. With the use of realistic nucleon-nucleon potentials, and many-nucleon potentials, containing strong tensor, Majorana, and repulsive core components, the many-body cluster structure of 16O, 27Al, 44Ti, and 48Ti is discussed. In 27Al(p,x)Na reactions we assume that two different nuclear cluster structures of 27Al, gives us two different isotopes of Na: 22Na and 24Na. But the most important result is the existence of two different permutations symmetries of 27Al. Using new method for calculation of nuclear cluster structure of 27Al, we have found two different nuclear cluster structures of 27Al: 24Na+3He and 25Na+d. The internal nuclear cluster wave functions of different nuclear cluster models (nuclear cluster isomers) of the same isotope are not equivalent, if we take into account Many-Body Nuclear Forces, such as 3BF and 4BF. The core clusters of 16O, 27Al, 44Ti, and 48Ti nuclei have a trigonal-pyramide Td, D2d, and C3v symmetry, while exterior clusters in 16O and 27Al[(24Na +3 He)model] nuclei have a trigonal symmetry C2v, and D3h. We have developed a new system of Jacobi coordinates for our EMBNCM model with the symmetry above. The new computer code for determination of direct nuclear cluster reactions has been written in Mathematica 5 programming language. We have found a high level of dependence of the nuclear cluster wave functions from the center of mass and cluster effects.

  2. Phosphorus in the young supernova remnant Cassiopeia A.

    PubMed

    Koo, Bon-Chul; Lee, Yong-Hyun; Moon, Dae-Sik; Yoon, Sung-Chul; Raymond, John C

    2013-12-13

    Phosphorus ((31)P), which is essential for life, is thought to be synthesized in massive stars and dispersed into interstellar space when these stars explode as supernovae (SNe). Here, we report on near-infrared spectroscopic observations of the young SN remnant Cassiopeia A, which show that the abundance ratio of phosphorus to the major nucleosynthetic product iron ((56)Fe) in SN material is up to 100 times the average ratio of the Milky Way, confirming that phosphorus is produced in SNe. The observed range is compatible with predictions from SN nucleosynthetic models but not with the scenario in which the chemical elements in the inner SN layers are completely mixed by hydrodynamic instabilities during the explosion.

  3. Nuclear physics. Momentum sharing in imbalanced Fermi systems.

    PubMed

    Hen, O; Sargsian, M; Weinstein, L B; Piasetzky, E; Hakobyan, H; Higinbotham, D W; Braverman, M; Brooks, W K; Gilad, S; Adhikari, K P; Arrington, J; Asryan, G; Avakian, H; Ball, J; Baltzell, N A; Battaglieri, M; Beck, A; May-Tal Beck, S; Bedlinskiy, I; Bertozzi, W; Biselli, A; Burkert, V D; Cao, T; Carman, D S; Celentano, A; Chandavar, S; Colaneri, L; Cole, P L; Crede, V; D'Angelo, A; De Vita, R; Deur, A; Djalali, C; Doughty, D; Dugger, M; Dupre, R; Egiyan, H; El Alaoui, A; El Fassi, L; Elouadrhiri, L; Fedotov, G; Fegan, S; Forest, T; Garillon, B; Garcon, M; Gevorgyan, N; Ghandilyan, Y; Gilfoyle, G P; Girod, F X; Goetz, J T; Gothe, R W; Griffioen, K A; Guidal, M; Guo, L; Hafidi, K; Hanretty, C; Hattawy, M; Hicks, K; Holtrop, M; Hyde, C E; Ilieva, Y; Ireland, D G; Ishkanov, B I; Isupov, E L; Jiang, H; Jo, H S; Joo, K; Keller, D; Khandaker, M; Kim, A; Kim, W; Klein, F J; Koirala, S; Korover, I; Kuhn, S E; Kubarovsky, V; Lenisa, P; Levine, W I; Livingston, K; Lowry, M; Lu, H Y; MacGregor, I J D; Markov, N; Mayer, M; McKinnon, B; Mineeva, T; Mokeev, V; Movsisyan, A; Munoz Camacho, C; Mustapha, B; Nadel-Turonski, P; Niccolai, S; Niculescu, G; Niculescu, I; Osipenko, M; Pappalardo, L L; Paremuzyan, R; Park, K; Pasyuk, E; Phelps, W; Pisano, S; Pogorelko, O; Price, J W; Procureur, S; Prok, Y; Protopopescu, D; Puckett, A J R; Rimal, D; Ripani, M; Ritchie, B G; Rizzo, A; Rosner, G; Roy, P; Rossi, P; Sabatié, F; Schott, D; Schumacher, R A; Sharabian, Y G; Smith, G D; Shneor, R; Sokhan, D; Stepanyan, S S; Stepanyan, S; Stoler, P; Strauch, S; Sytnik, V; Taiuti, M; Tkachenko, S; Ungaro, M; Vlassov, A V; Voutier, E; Walford, N K; Wei, X; Wood, M H; Wood, S A; Zachariou, N; Zana, L; Zhao, Z W; Zheng, X; Zonta, I

    2014-10-31

    The atomic nucleus is composed of two different kinds of fermions: protons and neutrons. If the protons and neutrons did not interact, the Pauli exclusion principle would force the majority of fermions (usually neutrons) to have a higher average momentum. Our high-energy electron-scattering measurements using (12)C, (27)Al, (56)Fe, and (208)Pb targets show that even in heavy, neutron-rich nuclei, short-range interactions between the fermions form correlated high-momentum neutron-proton pairs. Thus, in neutron-rich nuclei, protons have a greater probability than neutrons to have momentum greater than the Fermi momentum. This finding has implications ranging from nuclear few-body systems to neutron stars and may also be observable experimentally in two-spin-state, ultracold atomic gas systems. PMID:25323697

  4. The straggling Green's function method for ion transport

    NASA Astrophysics Data System (ADS)

    Walker, Steven Andrew

    For many years work has been conducted on developing a concise theory and method for HZE ion transport capable of being validated in the laboratory. Previous attempts have ignored dispersion and energy downshift associated with nuclear fragmentation and energy and range straggling. Here we present a Green's function approach to ion transport that incorporates these missing elements. This work forms the basis for a new version of GRNTRN, a Green's function transport code. Comparisons of GRNTRN predictions and laboratory results for an 56Fe ion beam with average energy at the target of one GeV/amu or more are presented for various targets. Quantities compared are the energy deposited spectra for an Aluminum target and Graphite-Epoxy mix target, the fraction of primary beam surviving and track average LET for these and various other targets.

  5. New Isotope 263Hs

    SciTech Connect

    Dragojevic, I.; Gregorich, K.E.; Dullmann, Ch.E.; Dvorak, J.; Ellison, P.A.; Gates, J.M.; Nelson, S.L.; Stavsetra, L.; Nitsche, H.

    2010-03-16

    A new isotope of Hs was produced in the reaction 208Pb(56Fe, n)263Hs at the 88-Inch Cyclotron of the Lawrence Berkeley National Laboratory. Six genetically correlated nuclear decay chains have been observed and assigned to the new isotope 263Hs. The measured cross section was 21+13-8.4 pb at 276.4 MeV lab-frame center-of-target beam energy. 263Hs decays with a half-life of 0.74 ms by alpha-decay and the measured alpha-particle energies are 10.57 +- 0.06, 10.72 +- 0.06, and 10.89 +- 0.06 MeV. The experimental cross section is compared to a theoretical prediction based on the Fusion by Diffusion model [W. J. Swiatecki et al., Phys. Rev. C 71, 014602 (2005)].

  6. The bubble-like interior of the core-collapse supernova remnant Cassiopeia A

    NASA Astrophysics Data System (ADS)

    Milisavljevic, Dan; Fesen, Robert A.

    2015-01-01

    The death of massive stars is believed to involve aspheric explosions initiated by the collapse of an iron core. The specifics of these catastrophic explosions remain uncertain, due partly to limited observational constraints on asymmetries deep inside the star. Here we present near-infrared observations of the young supernova remnant Cassiopeia A, descendant of a type IIb core-collapse explosion, and a three-dimensional map of its interior unshocked ejecta. The remnant’s interior has a bubble-like morphology that smoothly connects to and helps explain the multiringed structures seen in the remnant's bright reverse-shocked main shell of expanding debris. This internal structure may originate from turbulent mixing processes that encouraged outwardly expanding plumes of radioactive 56Ni-rich ejecta. If this is true, substantial amounts of its decay product, 56Fe, may still reside in these interior cavities.

  7. Plasma spectroscopy of metal ions for hyper-electron cyclotron resonance ion source.

    PubMed

    Muto, Hideshi; Ohshiro, Yukimitsu; Yamaka, Shoichi; Watanabe, Shin-ichi; Oyaizu, Michihiro; Kubono, Shigeru; Yamaguchi, Hidetoshi; Kase, Masayuki; Hattori, Toshiyuki; Shimoura, Susumu

    2014-02-01

    In this research, the optical line spectra of metal ions from ECR plasma were observed using a grating monochromator with a photomultiplier. The light intensity of line spectrum from the ECR plasma had a strong correlation with ion beam intensity measured by a magnetic mass analyzer. This correlation is a significant information for the beam tuning process, because it allows to conduct the extraction of the desired metal ion species from the ECR plasma. Separation of ion species of the same charge to mass ratio with an electromagnetic mass analyzer is known to be an exceptionally complex process, but this research provides a new approach for its simplification. In this paper the grating monochromator method for metal ion beam tuning such as (40)Ca(12+), (56)Fe(15+), and (85)Rb(20+) of hyper-ECR ion source as an injector for RIKEN Azimuthal Varying Field cyclotron is described.

  8. Mass-dependent and -independent signature of Fe isotopes in magnetotactic bacteria

    NASA Astrophysics Data System (ADS)

    Amor, Matthieu; Busigny, Vincent; Louvat, Pascale; Gélabert, Alexandre; Cartigny, Pierre; Durand-Dubief, Mickaël; Ona-Nguema, Georges; Alphandéry, Edouard; Chebbi, Imène; Guyot, François

    2016-05-01

    Magnetotactic bacteria perform biomineralization of intracellular magnetite (Fe3O4) nanoparticles. Although they may be among the earliest microorganisms capable of biomineralization on Earth, identifying their activity in ancient sedimentary rocks remains challenging because of the lack of a reliable biosignature. We determined Fe isotope fractionations by the magnetotactic bacterium Magnetospirillum magneticum AMB-1. The AMB-1 strain produced magnetite strongly depleted in heavy Fe isotopes, by 1.5 to 2.5 per mil relative to the initial growth medium. Moreover, we observed mass-independent isotope fractionations in 57Fe during magnetite biomineralization but not in even Fe isotopes (54Fe, 56Fe, and 58Fe), highlighting a magnetic isotope effect. This Fe isotope anomaly provides a potential biosignature for the identification of magnetite produced by magnetotactic bacteria in the geological record.

  9. Application of Fe Isotopes to the Search for Life and Habitable Planets

    NASA Technical Reports Server (NTRS)

    Johnson, Clark M.; Beard, Brian L.; Nealson, Kenneth L.

    2001-01-01

    The relatively new field of Fe isotope geochemistry can make important contributions to tracing the geochemical cycling of Fe, which bears on issues such as metabolic processing of Fe, surface redox conditions, and development of planetary atmospheres and biospheres. It appears that Fe isotope fractionation in nature and the lab spans about 4 per mil (%) in Fe-56/Fe-54, and although this range is small, our new analytical methods produce a precision of +/- 0.05% on sample sizes as small as 100 ng (10(exp -7) g); this now provides us with a sufficient "signal-to-noise" ratio to make this isotope system useful. We review our work in three areas: 1) the terrestrial and lunar rock record, 2) experiments on inorganic fractionation, and 3) experiments involving biological processing of Fe. Additional information is contained in the original extended abstract.

  10. Observation of the ⁶⁰Fe nucleosynthesis-clock isotope in galactic cosmic rays.

    PubMed

    Binns, W R; Israel, M H; Christian, E R; Cummings, A C; de Nolfo, G A; Lave, K A; Leske, R A; Mewaldt, R A; Stone, E C; von Rosenvinge, T T; Wiedenbeck, M E

    2016-05-01

    Iron-60 ((60)Fe) is a radioactive isotope in cosmic rays that serves as a clock to infer an upper limit on the time between nucleosynthesis and acceleration. We have used the ACE-CRIS instrument to collect 3.55 × 10(5) iron nuclei, with energies ~195 to ~500 mega-electron volts per nucleon, of which we identify 15 (60)Fe nuclei. The (60)Fe/(56)Fe source ratio is (7.5 ± 2.9) × 10(-5) The detection of supernova-produced (60)Fe in cosmic rays implies that the time required for acceleration and transport to Earth does not greatly exceed the (60)Fe half-life of 2.6 million years and that the (60)Fe source distance does not greatly exceed the distance cosmic rays can diffuse over this time, ⪍1 kiloparsec. A natural place for (60)Fe origin is in nearby clusters of massive stars.

  11. Iron isotope fractionation between aqueous Fe(II) and goethite revisited: New insights based on a multi-direction approach to equilibrium and isotopic exchange rate modification

    NASA Astrophysics Data System (ADS)

    Frierdich, Andrew J.; Beard, Brian L.; Reddy, Thiruchelvi R.; Scherer, Michelle M.; Johnson, Clark M.

    2014-08-01

    The Fe isotope compositions of naturally occurring Fe oxide minerals provide insights into biogeochemical processes that occur in modern and ancient environments. Key to understanding isotopic variations in such minerals is knowledge of the equilibrium Fe isotope fractionation factors between common minerals and aqueous Fe species. Because experimental measurements of isotopic fractionation may reflect a combination of kinetic and equilibrium fractionations during rapid dissolution and precipitation, even in experiments that employ the three-isotope method, assessment of the attainment of equilibrium is often difficult. Here, we re-examine Fe isotope exchange, via a 57Fe tracer, and natural mass-dependent fractionation, through changes in initial 56Fe/54Fe ratios, between aqueous Fe(II) (Fe(II)aq) and goethite. This approach uses the three-isotope method, but is distinct in its evaluation of kinetic isotope fractionation and the attainment of equilibrium by: (i) employing a multi-direction approach to equilibrium at 22 °C via reaction of three Fe(II)aq solutions that had different initial 56Fe/54Fe ratios, (ii) conducting isotopic exchange experiments at elevated temperature (50 °C), and (iii) modifying the rate of isotopic exchange through a combination of trace-element substitutions and particle coarsening to evaluate corresponding temporal changes in fractionation trajectories that may reflect changing instantaneous fractionation factors. We find that rapid isotopic exchange produces kinetic isotope effects between Fe(II)aq and goethite, which shifts the 56Fe/54Fe ratios of Fe(II)aq early in reactions toward that of goethite, indicating that the instantaneous Fe(II)aq-goethite fractionation factor under kinetic conditions is small. Importantly, however, this kinetic fractionation is “erased” with continued reaction, and this is evident by the congruence for multiple-exchange trajectories of distinct initial Fe(II)aq solutions toward the same final value

  12. USE OF COVARIANCE MATRICES IN A CONSISTENT (MULTISCALE) DATA ASSIMILATION FOR IMPROVEMENT OF BASIC NUCLEAR PARAMETERS IN NUCLEAR REACTOR APPLICATIONS: FROM METERS TO FEMTOMETERS

    SciTech Connect

    G. Palmiotti; M. Salvatores; H. Hiruta; M. Herman; P. Oblozinsky; M. Pigni

    2010-04-01

    A new approach is proposed, the consistent data assimilation, that allows to link the integral data experiment results to basic nuclear parameters employed by evaluators to generate ENDF/B point energy files in order to improve them. A practical example is provided where the sodium neutron propagation experiments, EURACOS and JANUS-8, are used to improve via modifications of 23Na nuclear parameters (like scattering radius, resonance parameters, Optical model parameters, Statistical Hauser-Feshbach model parameters, and Preequilibrium Exciton model parameters) the agreement of calculation versus experiments for a series of measured reaction rate detectors slopes. Future work involves comparison of results against a more traditional multigroup adjustments, and extension to other isotope of interest in the reactor community as 56Fe, actinides, and fission products.

  13. Use of Covariance Matrices in a Consistent (Multiscale) Data Assimilation for Improvement of Basic Nuclear Parameters in Nuclear Reactor Applications: from Meters to Femtometers

    SciTech Connect

    Palmiotti, G.; Herman, M.; Palmiotti,G.; Hiruta,H.; Salvatores,M.; Herman,M.; Oblozinsky,P.; Pigni,M.T.

    2011-08-01

    A new approach is proposed, the consistent data assimilation, that allows to link the integral data experiment results to basic nuclear parameters employed by evaluators to generate ENDF/B point energy files in order to improve them. A practical example is provided where the sodium neutron propagation experiments, EURACOS and JANUS-8, are used to improve via modifications of {sup 23}Na nuclear parameters (like scattering radius, resonance parameters, Optical model parameters, Statistical Hauser-Feshbach model parameters, and Preequilibrium Exciton model parameters) the agreement of calculation versus experiments for a series of measured reaction rate detectors slopes. Future work involves comparison of results against a more traditional multigroup adjustments, and extension to other isotope of interest in the reactor community as {sup 56}Fe, actinides, and fission products.

  14. Iron isotope fractionation during microbially stimulated Fe(II) oxidation and Fe(III) precipitation

    USGS Publications Warehouse

    Balci, N.; Bullen, T.D.; Witte-Lien, K.; Shanks, Wayne C.; Motelica, M.; Mandernack, K.W.

    2006-01-01

    Interpretation of the origins of iron-bearing minerals preserved in modern and ancient rocks based on measured iron isotope ratios depends on our ability to distinguish between biological and non-biological iron isotope fractionation processes. In this study, we compared 56Fe/54Fe ratios of coexisting aqueous iron (Fe(II)aq, Fe(III)aq) and iron oxyhydroxide precipitates (Fe(III)ppt) resulting from the oxidation of ferrous iron under experimental conditions at low pH (<3). Experiments were carried out using both pure cultures of Acidothiobacillus ferrooxidans and sterile controls to assess possible biological overprinting of non-biological fractionation, and both SO42- and Cl- salts as Fe(II) sources to determine possible ionic/speciation effects that may be associated with oxidation/precipitation reactions. In addition, a series of ferric iron precipitation experiments were performed at pH ranging from 1.9 to 3.5 to determine if different precipitation rates cause differences in the isotopic composition of the iron oxyhydroxides. During microbially stimulated Fe(II) oxidation in both the sulfate and chloride systems, 56Fe/54Fe ratios of residual Fe(II)aq sampled in a time series evolved along an apparent Rayleigh trend characterized by a fractionation factor ??Fe(III)aq-Fe(II)aq???1.0022. This fractionation factor was significantly less than that measured in our sterile control experiments (???1.0034) and that predicted for isotopic equilibrium between Fe(II)aq and Fe(III)aq (???1.0029), and thus might be interpreted to reflect a biological isotope effect. However, in our biological experiments the measured difference in 56Fe/54Fe ratios between Fe(III)aq, isolated as a solid by the addition of NaOH to the final solution at each time point under N2-atmosphere, and Fe(II)aq was in most cases and on average close to 2.9??? (??Fe(III)aq-Fe(II)aq ???1.0029), consistent with isotopic equilibrium between Fe(II)aq and Fe(III)aq. The ferric iron precipitation experiments

  15. Experimental differential cross sections, level densities, and spin cutoffs as a testing ground for nuclear reaction codes

    NASA Astrophysics Data System (ADS)

    Voinov, A. V.; Grimes, S. M.; Brune, C. R.; Bürger, A.; Görgen, A.; Guttormsen, M.; Larsen, A. C.; Massey, T. N.; Siem, S.

    2013-11-01

    Proton double-differential cross sections from 59Co(α,p)62Ni, 57Fe(α,p)60Co, 56Fe(7Li,p)62Ni, and 55Mn(6Li,p)60Co reactions have been measured with 21-MeV α and 15-MeV lithium beams. Cross sections have been compared against calculations with the empire reaction code. Different input level density models have been tested. It was found that the Gilbert and Cameron [A. Gilbert and A. G. W. Cameron, Can. J. Phys.0008-420410.1139/p65-139 43, 1446 (1965)] level density model is best to reproduce experimental data. Level densities and spin cutoff parameters for 62Ni and 60Co above the excitation energy range of discrete levels (in continuum) have been obtained with a Monte Carlo technique. Excitation energy dependencies were found to be inconsistent with the Fermi-gas model.

  16. Supernovae. The bubble-like interior of the core-collapse supernova remnant Cassiopeia A.

    PubMed

    Milisavljevic, Dan; Fesen, Robert A

    2015-01-30

    The death of massive stars is believed to involve aspheric explosions initiated by the collapse of an iron core. The specifics of these catastrophic explosions remain uncertain, due partly to limited observational constraints on asymmetries deep inside the star. Here we present near-infrared observations of the young supernova remnant Cassiopeia A, descendant of a type IIb core-collapse explosion, and a three-dimensional map of its interior unshocked ejecta. The remnant's interior has a bubble-like morphology that smoothly connects to and helps explain the multiringed structures seen in the remnant's bright reverse-shocked main shell of expanding debris. This internal structure may originate from turbulent mixing processes that encouraged outwardly expanding plumes of radioactive (56)Ni-rich ejecta. If this is true, substantial amounts of its decay product, (56)Fe, may still reside in these interior cavities.

  17. AFRRI reports, second quarter 1992. Rept. for Apr-Jul 92

    SciTech Connect

    Not Available

    1992-07-01

    This report includes the following topics: Short and long courses of ofloxacin therapy of Klebsiella pneumoniae sepsis following irradiation, Possible 'accelerated striatal aging' induced by 56Fe heavy-particle irradiation: Implications for manned space flights, Modulation of mortality by tissue trauma and sepsis in mice after radiation injury, Cytokine therapy in canine and primate models of radiation-induced marrow aplasia, Comparison of behavioral and radioprotective effects of WR-2721 and WR-3689, Energy transfer mechanisms in DNA: Relationship to energy deposition in sub-microscopic volumes, Role of interleukin 6 (IL-6) in protection from lethal irradiation and in endocrine responses to IL-1 and tumor necrosis factor, Effects on enhancing hemopoietic reconstitution and increasing survival following exposure to ionizing radiation, and Radioprotection of hematopoietic tissues in mice by lipoic acid.

  18. The (n, α) Reaction in the s-process Branching Point {sup 59}Ni

    SciTech Connect

    Weiß, C.; Guerrero, C.; Griesmayer, E.; Andrzejewski, J.; Badurek, G.; Chiaveri, E.; Dressler, R.; Ganesan, S.; Jericha, E.; Käppeler, F.; Koehler, P.; Lederer, C.; Leeb, H.; Marganiec, J.; Pavlik, A.; Perkowski, J.; Rauscher, T.; and others

    2014-06-15

    The (n, α) reaction in the radioactive {sup 59}Ni is of relevance in nuclear astrophysics as {sup 59}Ni can be considered as the first branching point in the astrophysical s-process. Its relevance in nuclear technology is especially related to material embrittlement in stainless steel. However, there is a discrepancy between available experimental data and the evaluated nuclear data files for this reaction. At the n{sub T}OF facility at CERN, a dedicated system based on sCVD diamond diodes was set up to measure the {sup 59}Ni(n, α){sup 56}Fe cross section. The results of this measurement, with special emphasis on the dominant resonance at 203 eV, are presented here.

  19. Investigation of pion-nucleus interactions. Progress report, April 1, 1990--March 31, 1991

    SciTech Connect

    Moore, C.F.

    1991-09-01

    The double isovector giant state has been observed in the ({pi}{sup {minus}}, {pi}{sup +}) {Delta}T{sub z} = +2 double-charge-exchange reaction on {sup 13}C, {sup 27}Al, {sup 40}Ca, {sup 56}Fe, {sup 59}Co, and {sup 93}Nb. The resonances observed in the ({pi}{sup {minus}}, {pi}{sup +}) reaction are closely related via Coulomb displacement energy and isospin symmetry to the resonances measured in the inverse ({pi}{sup +}, {pi}{sup {minus}}) reaction on the same nuclei. The new observations provide a direct determination of the upper isospin component of the double giant dipole state, which is generally very weak in the ({pi}{sup +}, {pi}{sup {minus}}) reaction. The comparison between the double dipole in the two double-charge-exchange modes gives valuable information on the isospin splitting and the Pauli-blocking effects for isotensor transitions.

  20. Investigation of pion-nucleus interactions

    SciTech Connect

    Moore, C.F.

    1991-09-01

    The double isovector giant state has been observed in the ({pi}{sup {minus}}, {pi}{sup +}) {Delta}T{sub z} = +2 double-charge-exchange reaction on {sup 13}C, {sup 27}Al, {sup 40}Ca, {sup 56}Fe, {sup 59}Co, and {sup 93}Nb. The resonances observed in the ({pi}{sup {minus}}, {pi}{sup +}) reaction are closely related via Coulomb displacement energy and isospin symmetry to the resonances measured in the inverse ({pi}{sup +}, {pi}{sup {minus}}) reaction on the same nuclei. The new observations provide a direct determination of the upper isospin component of the double giant dipole state, which is generally very weak in the ({pi}{sup +}, {pi}{sup {minus}}) reaction. The comparison between the double dipole in the two double-charge-exchange modes gives valuable information on the isospin splitting and the Pauli-blocking effects for isotensor transitions.

  1. Contrasting behavior of oxygen and iron isotopes in banded iron formation revealed by in situ analysis

    NASA Astrophysics Data System (ADS)

    Beard, B.; Li, W.; Kita, N.; Valley, J. W.; Johnson, C.

    2012-12-01

    Banded iron formations (BIFs) record a period of dramatic secular change in Earth's geologic history, when abundant aqueous Fe(II) was removed from Archean and Proterozoic oceans by oxidation. BIFs are characterized by co-existing of quartz and iron minerals, including oxides and carbonates, and alternating iron-rich and iron-poor layers range from m to 56Fe, respectively. Analysis of δ18O in iron oxides by SIMS employed special tuning with a 3kV primary beam to minimize orientation effects (Huberty et al. 2010 ). For hematite, δ18O values range from -7.1 ‰ to -0.6 ‰, with the majority of data clustering around -4.5 ‰, and δ56Fe values range from -0.50 ‰ to +1.53‰. Magnetite has a δ18O range of -5.6 ‰ to +5.6 ‰ and a δ56Fe range of -0.76 ‰ to +1.33 ‰. Notably, magnetite shows significant O isotope heterogeneity at a mineral grain scale, and the highest δ18O values were commonly measured from Si-rich (1-3 wt% SiO2) magnetite overgrowths or magnetite grains that have a recrystallization texture. In contrast, lowest δ18O values were measured from magnetite that contains less than 1 wt% SiO2. Individual magnetite grains can have up to 6 ‰ variation in δ18O values between low-Si core and Si-rich overgrowth. Iron

  2. On relative supernova rates and nucleosynthesis roles

    NASA Technical Reports Server (NTRS)

    Arnett, W. David; Schramm, David N.; Truran, James W.

    1989-01-01

    It is shown that the Ni-56-Fe-56 observed in SN 1987A argues that core collapse supernovae may be responsible for more than 50 percent of the iron in the galaxy. Furthermore it is argued that the time averaged rate of thermonuclear driven Type I supernovae may be at least an order of magnitude lower than the average rate of core collapse supernovae. The present low rate of Type II supernovae (below their time averaged rate of approx. 1/10 yr) is either because the past rate was much higher because many core collapse supernovae are dim like SN 1987A. However, even in this latter case they are only an order of magnitude dimmer that normal Type II's due to the contribution of Ni-56 decay to the light curve.

  3. On relative supernova rates and nucleosynthesis roles

    NASA Technical Reports Server (NTRS)

    Arnett, W. David; Schramm, David N.; Truran, James W.

    1988-01-01

    It is shown that the Ni-56-Fe-56 observed in SN 1987A argues that core collapse supernovae may be responsible for more that 50 percent of the iron in the galaxy. Furthermore it is argued that the time averaged rate of thermonuclear driven Type I supernovae may be at least an order of magnitude lower than the average rate of core collapse supernovae. The present low rate of Type II supernovae (below their time averaged rate of approx. 1/10 yr) is either because the past rate was much higher because many core collapse supernovae are dim like SN 1987A. However, even in this latter case they are only an order of magnitude dimmer that normal Type II's due to the contribution of Ni-56 decay to the light curve.

  4. Nuclear interactions in high energy heavy ions and applications in astrophysics. [Dept. of Physics and Astronomy, Louisiana State Univ. , Baton Rouge

    SciTech Connect

    Wefel, J.P.; Guzik, T.G.

    1993-01-11

    The overall objective is to study the mechanisms and the energy dependence of heavy ion fragmentation by studying the reactions of heavy ion projectiles (e.g. [sup 4]He, [sup 16]O, [sup 20]Ne, [sup 28]Si, [sup 56]Fe) in a variety of targets (H, He, C, Si, Cu, Pb) and at a number of beam energies exceeding 0.1 GeV/nucleon. The results have application to questions in high-energy nuclear astrophysics. Most of the discussion is on low-energy [sup 16]O,[sup 28]Si data analysis. The description includes analysis procedures and techniques, detector calibrations, data selections and normalizations. Cross section results for the analysis are also presented. 83 figs., 6 tabs., 73 refs.

  5. Nuclear interactions in high energy heavy ions and applications in astrophysics. Technical progress report, 1 April 1992--31 March 1993

    SciTech Connect

    Wefel, J.P.; Guzik, T.G.

    1993-01-11

    The overall objective is to study the mechanisms and the energy dependence of heavy ion fragmentation by studying the reactions of heavy ion projectiles (e.g. {sup 4}He, {sup 16}O, {sup 20}Ne, {sup 28}Si, {sup 56}Fe) in a variety of targets (H, He, C, Si, Cu, Pb) and at a number of beam energies exceeding 0.1 GeV/nucleon. The results have application to questions in high-energy nuclear astrophysics. Most of the discussion is on low-energy {sup 16}O,{sup 28}Si data analysis. The description includes analysis procedures and techniques, detector calibrations, data selections and normalizations. Cross section results for the analysis are also presented. 83 figs., 6 tabs., 73 refs.

  6. Study of wear and galling in aircraft fuel pump drive shafts and gears using the surface layer activation technique

    NASA Astrophysics Data System (ADS)

    Gallmann, A.; Natter, B.; Molinari, M. A.

    1988-10-01

    The surface layer activation technique (SLA) has been applied to study galling and wear in moving parts of Boeing 747 engines. Radioactive 56Co was formed by the reaction 56Fe(p, n) 56Co in fuel pump drive shafts and gears, and their residual activities in these activated parts were measured in situ during routine inspections over more than one year. The study of the wear was done on shafts made of a new alloy and on gears having a new tooth geometry. Wear determined by SLA was corroborated by a profile measurement made when one of the pumps was disassembled. The study of the galling (with release of metallic fragments) of a drive shaft consisted in checking the condition of the critical zone of the splines with the SLA technique. The main originality of the present work is that for the first time such measurements were performed on engines in revenue service.

  7. Nuclear physics. Momentum sharing in imbalanced Fermi systems.

    PubMed

    Hen, O; Sargsian, M; Weinstein, L B; Piasetzky, E; Hakobyan, H; Higinbotham, D W; Braverman, M; Brooks, W K; Gilad, S; Adhikari, K P; Arrington, J; Asryan, G; Avakian, H; Ball, J; Baltzell, N A; Battaglieri, M; Beck, A; May-Tal Beck, S; Bedlinskiy, I; Bertozzi, W; Biselli, A; Burkert, V D; Cao, T; Carman, D S; Celentano, A; Chandavar, S; Colaneri, L; Cole, P L; Crede, V; D'Angelo, A; De Vita, R; Deur, A; Djalali, C; Doughty, D; Dugger, M; Dupre, R; Egiyan, H; El Alaoui, A; El Fassi, L; Elouadrhiri, L; Fedotov, G; Fegan, S; Forest, T; Garillon, B; Garcon, M; Gevorgyan, N; Ghandilyan, Y; Gilfoyle, G P; Girod, F X; Goetz, J T; Gothe, R W; Griffioen, K A; Guidal, M; Guo, L; Hafidi, K; Hanretty, C; Hattawy, M; Hicks, K; Holtrop, M; Hyde, C E; Ilieva, Y; Ireland, D G; Ishkanov, B I; Isupov, E L; Jiang, H; Jo, H S; Joo, K; Keller, D; Khandaker, M; Kim, A; Kim, W; Klein, F J; Koirala, S; Korover, I; Kuhn, S E; Kubarovsky, V; Lenisa, P; Levine, W I; Livingston, K; Lowry, M; Lu, H Y; MacGregor, I J D; Markov, N; Mayer, M; McKinnon, B; Mineeva, T; Mokeev, V; Movsisyan, A; Munoz Camacho, C; Mustapha, B; Nadel-Turonski, P; Niccolai, S; Niculescu, G; Niculescu, I; Osipenko, M; Pappalardo, L L; Paremuzyan, R; Park, K; Pasyuk, E; Phelps, W; Pisano, S; Pogorelko, O; Price, J W; Procureur, S; Prok, Y; Protopopescu, D; Puckett, A J R; Rimal, D; Ripani, M; Ritchie, B G; Rizzo, A; Rosner, G; Roy, P; Rossi, P; Sabatié, F; Schott, D; Schumacher, R A; Sharabian, Y G; Smith, G D; Shneor, R; Sokhan, D; Stepanyan, S S; Stepanyan, S; Stoler, P; Strauch, S; Sytnik, V; Taiuti, M; Tkachenko, S; Ungaro, M; Vlassov, A V; Voutier, E; Walford, N K; Wei, X; Wood, M H; Wood, S A; Zachariou, N; Zana, L; Zhao, Z W; Zheng, X; Zonta, I

    2014-10-31

    The atomic nucleus is composed of two different kinds of fermions: protons and neutrons. If the protons and neutrons did not interact, the Pauli exclusion principle would force the majority of fermions (usually neutrons) to have a higher average momentum. Our high-energy electron-scattering measurements using (12)C, (27)Al, (56)Fe, and (208)Pb targets show that even in heavy, neutron-rich nuclei, short-range interactions between the fermions form correlated high-momentum neutron-proton pairs. Thus, in neutron-rich nuclei, protons have a greater probability than neutrons to have momentum greater than the Fermi momentum. This finding has implications ranging from nuclear few-body systems to neutron stars and may also be observable experimentally in two-spin-state, ultracold atomic gas systems.

  8. Identification of new astatine isotopes using the gas-filled magnetic separator, SASSY

    SciTech Connect

    Yashita, S.

    1984-02-01

    A He-filled on-line mass separator system was built at the SuperHILAC and used to study the fusion products in the reaction /sup 56/Fe + /sup 141/Pr. The new neutron-deficient isotopes /sup 194/At and /sup 195/At were produced in this bombardment as three- and two- neutron-out products, respectively, and were identified by the ..cap alpha..-..cap alpha.. time-correlation technique. The measured ..cap alpha.. energies and half lives are 7.20 +- 0.02 MeV and 180 +- 80 msec for /sup 194/At, and 7.12 +- 0.02 MeV and 200 +- 100 msec for /sup 195/At. 66 references.

  9. Identification of new astatine isotopes using the gas-filled magnetic separator, Sassy

    SciTech Connect

    Yashita, S.

    1983-01-01

    A He-filled on-line separator system was built at the SuperHILAC and used to study the fusion products in the reaction /sup 56/Fe + /sup 141/Pr. The new neutron-deficient isotopes /sup 194/At and /sup 195/At were produced in this bombardment as three- and two-neutron-out products, respectively, and were identified by the ..cap alpha..-..cap alpha.. time-correlation technique. The measured ..cap alpha.. energies and half lives are 7.20 +/- 0.02 MeV and 180 +/- 80 msec for /sup 194/At, and 7.12 +/- 0.02 MeV and 200 +/- 100 msec for /sup 195/At.

  10. Observation of the ⁶⁰Fe nucleosynthesis-clock isotope in galactic cosmic rays.

    PubMed

    Binns, W R; Israel, M H; Christian, E R; Cummings, A C; de Nolfo, G A; Lave, K A; Leske, R A; Mewaldt, R A; Stone, E C; von Rosenvinge, T T; Wiedenbeck, M E

    2016-05-01

    Iron-60 ((60)Fe) is a radioactive isotope in cosmic rays that serves as a clock to infer an upper limit on the time between nucleosynthesis and acceleration. We have used the ACE-CRIS instrument to collect 3.55 × 10(5) iron nuclei, with energies ~195 to ~500 mega-electron volts per nucleon, of which we identify 15 (60)Fe nuclei. The (60)Fe/(56)Fe source ratio is (7.5 ± 2.9) × 10(-5) The detection of supernova-produced (60)Fe in cosmic rays implies that the time required for acceleration and transport to Earth does not greatly exceed the (60)Fe half-life of 2.6 million years and that the (60)Fe source distance does not greatly exceed the distance cosmic rays can diffuse over this time, ⪍1 kiloparsec. A natural place for (60)Fe origin is in nearby clusters of massive stars. PMID:27103666

  11. Momentum sharing in imbalanced Fermi systems

    DOE PAGES

    Hen, O.; Sargsian, M.; Weinstein, L. B.; Piasetzky, E.

    2014-10-16

    The atomic nucleus is composed of two different kinds of fermions, protons and neutrons. If the protons and neutrons did not interact, the Pauli exclusion principle would force the majority fermions (usually neutrons) to have a higher average momentum. Our high-energy electron scattering measurements using 12C, 27Al, 56Fe and 208Pb targets show that, even in heavy neutron-rich nuclei, short-range interactions between the fermions form correlated high-momentum neutron-proton pairs. Thus, in neutron-rich nuclei, protons have a greater probability than neutrons to have momentum greater than the Fermi momentum. This finding has implications ranging from nuclear few body systems to neutron starsmore » and may also be observable experimentally in two-spin state, ultra-cold atomic gas systems.« less

  12. Total Monte Carlo evaluation for dose calculations.

    PubMed

    Sjöstrand, H; Alhassan, E; Conroy, S; Duan, J; Hellesen, C; Pomp, S; Österlund, M; Koning, A; Rochman, D

    2014-10-01

    Total Monte Carlo (TMC) is a method to propagate nuclear data (ND) uncertainties in transport codes, by using a large set of ND files, which covers the ND uncertainty. The transport code is run multiple times, each time with a unique ND file, and the result is a distribution of the investigated parameter, e.g. dose, where the width of the distribution is interpreted as the uncertainty due to ND. Until recently, this was computer intensive, but with a new development, fast TMC, more applications are accessible. The aim of this work is to test the fast TMC methodology on a dosimetry application and to propagate the (56)Fe uncertainties on the predictions of the dose outside a proposed 14-MeV neutron facility. The uncertainty was found to be 4.2 %. This can be considered small; however, this cannot be generalised to all dosimetry applications and so ND uncertainties should routinely be included in most dosimetry modelling.

  13. Mass-dependent and -independent signature of Fe isotopes in magnetotactic bacteria.

    PubMed

    Amor, Matthieu; Busigny, Vincent; Louvat, Pascale; Gélabert, Alexandre; Cartigny, Pierre; Durand-Dubief, Mickaël; Ona-Nguema, Georges; Alphandéry, Edouard; Chebbi, Imène; Guyot, François

    2016-05-01

    Magnetotactic bacteria perform biomineralization of intracellular magnetite (Fe3O4) nanoparticles. Although they may be among the earliest microorganisms capable of biomineralization on Earth, identifying their activity in ancient sedimentary rocks remains challenging because of the lack of a reliable biosignature. We determined Fe isotope fractionations by the magnetotactic bacterium Magnetospirillum magneticum AMB-1. The AMB-1 strain produced magnetite strongly depleted in heavy Fe isotopes, by 1.5 to 2.5 per mil relative to the initial growth medium. Moreover, we observed mass-independent isotope fractionations in (57)Fe during magnetite biomineralization but not in even Fe isotopes ((54)Fe, (56)Fe, and (58)Fe), highlighting a magnetic isotope effect. This Fe isotope anomaly provides a potential biosignature for the identification of magnetite produced by magnetotactic bacteria in the geological record. PMID:27151868

  14. Measurement of Two- and Three-Nucleon Short-Range Correlation Probabilities in Nuclei

    SciTech Connect

    K. S. Egiyan; N. B. Dashyan; M. M. Sargsian; M. I. Strikman; L. B. Weinstein; G. Adams; P. Ambrozewicz; M. Anghinolfi; B. Asavapibhop; G. Asryan; H. Avakian; H. Baghdasaryan; N. Baillie; J. P. Ball; N. A. Baltzell; V. Batourine; M. Battaglieri; I. Bedlinskiy; M. Bektasoglu; M. Bellis; N. Benmouna; A. S. Biselli; B. E. Bonner; S. Bouchigny; S. Boiarinov; R. Bradford; D. Branford; W. K. Brooks; S. Bültmann; V. D. Burkert; C. Bultuceanu; J. R. Calarco; S. L. Careccia; D. S. Carman; B. Carnahan; S. Chen; P. L. Cole; P. Coltharp; P. Corvisiero; D. Crabb; H. Crannell; J. P. Cummings; E. De Sanctis; R. DeVita; P. V. Degtyarenko; H. Denizli; L. Dennis; K. V. Dharmawardane; C. Djalali; G. E. Dodge; J. Donnelly; D. Doughty; P. Dragovitsch; M. Dugger; S. Dytman; O. P. Dzyubak; H. Egiyan; L. Elouadrhiri; A. Empl; P. Eugenio; R. Fatemi; G. Fedotov; R. J. Feuerbach; T. A. Forest; H. Funsten; G. Gavalian; N. G. Gevorgyan; G. P. Gilfoyle; K. L. Giovanetti; F. X. Girod; J. T. Goetz; E. Golovatch; R. W. Gothe; K. A. Griffioen; M. Guidal; M. Guillo; N. Guler; L. Guo; V. Gyurjyan; C. Hadjidakis; J. Hardie; F. W. Hersman; K. Hicks; I. Hleiqawi; M. Holtrop; J. Hu; M. Huertas; C. E. Hyde-Wright; Y. Ilieva; D. G. Ireland; B. S. Ishkhanov; M. M. Ito; D. Jenkins; H. S. Jo; K. Joo; H. G. Juengst; J. D. Kellie; M. Khandaker; K. Y. Kim; K. Kim; W. Kim; A. Klein; F. J. Klein; A. Klimenko; M. Klusman; L. H. Kramer; V. Kubarovsky; J. Kuhn; S. E. Kuhn; S. Kuleshov; J. Lachniet; J. M. Laget; J. Langheinrich; D. Lawrence; T. Lee; K. Livingston; L. C. Maximon; S. McAleer; B. McKinnon; J. W. C. McNabb; B. A. Mecking; M. D. Mestayer; C. A. Meyer; T. Mibe; K. Mikhailov; R. Minehart; M. Mirazita; R. Miskimen; V. Mokeev; S. A. Morrow; J. Mueller; G. S. Mutchler; P. Nadel-Turonski; J. Napolitano; R. Nasseripour; S. Niccolai; G. Niculescu; I. Niculescu; B. B. Niczyporuk; R. A. Niyazov; G. V. O'Rielly; M. Osipenko; A. I. Ostrovidov; K. Park; E. Pasyuk; C. Peterson; J. Pierce; N. Pivnyuk; D. Pocanic; O. Pogorelko; E. Polli; S. Pozdniakov; B. M. Preedom; J. W. Price; Y. Prok; D. Protopopescu; L. M. Qin; B. A. Raue; G. Riccardi; G. Ricco; M. Ripani; B. G. Ritchie; F. Ronchetti; G. Rosner; P. Rossi; D. Rowntree; P. D. Rubin; F. Sabatié; C. Salgado; J. P. Santoro; V. Sapunenko; R. A. Schumacher; V. S. Serov; Y. G. Sharabian; J. Shaw; E. S. Smith; L. C. Smith; D. I. Sober; A. Stavinsky; S. Stepanyan; B. E. Stokes; P. Stoler; S. Strauch; R. Suleiman; M. Taiuti; S. Taylor; D. J. Tedeschi; R. Thompson; A. Tkabladze; S. Tkachenko; L. Todor; C. Tur; M. Ungaro; M. F. Vineyard; A. V. Vlassov; D. P. Weygand; M. Williams; E. Wolin; M. H. Wood; A. Yegneswaran; J. Yun; L. Zana; and J. Zhang

    2006-03-01

    The ratios of inclusive electron scattering cross sections of 4He, 12C, and 56Fe to 3He have been measured at 11.4 GeV2, the ratios exhibit two separate plateaus, at 1.52.25. This pattern is predicted by models that include 2- and 3-nucleon short-range correlations (SRC). Relative to A=3, the per-nucleon probabilities of 3-nucleon SRC are 2.3, 3.1, and 4.4 times larger for A=4, 12, and 56. This is the first measurement of 3-nucleon SRC probabilities in nuclei.

  15. Mass-dependent and -independent signature of Fe isotopes in magnetotactic bacteria.

    PubMed

    Amor, Matthieu; Busigny, Vincent; Louvat, Pascale; Gélabert, Alexandre; Cartigny, Pierre; Durand-Dubief, Mickaël; Ona-Nguema, Georges; Alphandéry, Edouard; Chebbi, Imène; Guyot, François

    2016-05-01

    Magnetotactic bacteria perform biomineralization of intracellular magnetite (Fe3O4) nanoparticles. Although they may be among the earliest microorganisms capable of biomineralization on Earth, identifying their activity in ancient sedimentary rocks remains challenging because of the lack of a reliable biosignature. We determined Fe isotope fractionations by the magnetotactic bacterium Magnetospirillum magneticum AMB-1. The AMB-1 strain produced magnetite strongly depleted in heavy Fe isotopes, by 1.5 to 2.5 per mil relative to the initial growth medium. Moreover, we observed mass-independent isotope fractionations in (57)Fe during magnetite biomineralization but not in even Fe isotopes ((54)Fe, (56)Fe, and (58)Fe), highlighting a magnetic isotope effect. This Fe isotope anomaly provides a potential biosignature for the identification of magnetite produced by magnetotactic bacteria in the geological record.

  16. Responses of a direct ion storage dosimeter (DIS-1) to heavy charged particles.

    PubMed

    Yasuda, H

    2001-12-01

    The responses of a direct ion storage dosimeter (DIS-1) to energetic heavy charged particles were examined using (4)He, (12)C, (40)Ar and (56)Fe ion beams at the HIMAC at the National Institute of Radiological Sciences. The efficiency of the DIS-1 on the basis of absorbed dose was almost unity for the helium and carbon ions and was slightly decreased for the argon and iron ions. The linearity in the dose response and the angular independence for these heavy ions were fairly good. Although further studies are necessary, these results suggest that the DIS-1 would be a suitable passive dosimeter for measurements of absorbed dose in a field dominated by heavy charged particles such as the space environment. PMID:11741505

  17. The (n, α) Reaction in the s-process Branching Point 59Ni

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    The (n, α) reaction in the radioactive 59Ni is of relevance in nuclear astrophysics as 59Ni can be considered as the first branching point in the astrophysical s-process. Its relevance in nuclear technology is especially related to material embrittlement in stainless steel. However, there is a discrepancy between available experimental data and the evaluated nuclear data files for this reaction. At the n_TOF facility at CERN, a dedicated system based on sCVD diamond diodes was set up to measure the 59Ni(n, α)56Fe cross section. The results of this measurement, with special emphasis on the dominant resonance at 203 eV, are presented here.

  18. Oxygen and iron isotope constraints on near-surface fractionation effects and the composition of lunar mare basalt source regions

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Spicuzza, Michael J.; Craddock, Paul R.; Day, James M. D.; Valley, John W.; Dauphas, Nicolas; Taylor, Lawrence A.

    2010-11-01

    Oxygen and iron isotope analyses of low-Ti and high-Ti mare basalts are presented to constrain their petrogenesis and to assess stable isotope variations within lunar mantle sources. An internally-consistent dataset of oxygen isotope compositions of mare basalts encompasses five types of low-Ti basalts from the Apollo 12 and 15 missions and eight types of high-Ti basalts from the Apollo 11 and 17 missions. High-precision whole-rock δ 18O values (referenced to VSMOW) of low-Ti and high-Ti basalts correlate with major-element compositions (Mg#, TiO 2, Al 2O 3). The observed oxygen isotope variations within low-Ti and high-Ti basalts are consistent with crystal fractionation and match the results of mass-balance models assuming equilibrium crystallization. Whole-rock δ 56Fe values (referenced to IRMM-014) of high-Ti and low-Ti basalts range from 0.134‰ to 0.217‰ and 0.038‰ to 0.104‰, respectively. Iron isotope compositions of both low-Ti and high-Ti basalts do not correlate with indices of crystal fractionation, possibly owing to small mineral-melt iron fractionation factors anticipated under lunar reducing conditions. The δ 18O and δ 56Fe values of low-Ti and the least differentiated high-Ti mare basalts are negatively correlated, which reflects their different mantle source characteristics (e.g., the presence or absence of ilmenite). The average δ 56Fe values of low-Ti basalts (0.073 ± 0.018‰, n = 8) and high-Ti basalts (0.191 ± 0.020‰, n = 7) may directly record that of their parent mantle sources. Oxygen isotope compositions of mantle sources of low-Ti and high-Ti basalts are calculated using existing models of lunar magma ocean crystallization and mixing, the estimated equilibrium mantle olivine δ 18O value, and equilibrium oxygen-fractionation between olivine and other mineral phases. The differences between the calculated whole-rock δ 18O values for source regions, 5.57‰ for low-Ti and 5.30‰ for high-Ti mare basalt mantle source regions

  19. Iron isotope fractionation during magmatic differentiation in Kilauea Iki lava lake

    USGS Publications Warehouse

    Teng, F.-Z.; Dauphas, N.; Helz, R.T.

    2008-01-01

    Magmatic differentiation helps produce the chemical and petrographic diversity of terrestrial rocks. The extent to which magmatic differentiation fractionates nonradiogenic isotopes is uncertain for some elements. We report analyses of iron isotopes in basalts from Kilauea Iki lava lake, Hawaii. The iron isotopic compositions (56Fe/54Fe) of late-stage melt veins are 0.2 per mil (???) greater than values for olivine cumulates. Olivine phenocrysts are up to 1.2??? lighter than those of whole rocks. These results demonstrate that iron isotopes fractionate during magmatic differentiation at both whole-rock and crystal scales. This characteristic of iron relative to the characteristics of magnesium and lithium, for which no fractionation has been found, may be related to its complex redox chemistry in magmatic systems and makes iron a potential tool for studying planetary differentiation.

  20. Experimental differential cross sections, level densities, and spin cutoffs as a testing ground for nuclear reaction codes

    DOE PAGES

    Voinov, Alexander V.; Grimes, Steven M.; Brune, Carl R.; Burger, Alexander; Gorgen, Andreas; Guttormsen, Magne; Larsen, Ann -Cecilie; Massey, Thomas N.; Siem, Sunniva

    2013-11-08

    Proton double-differential cross sections from 59Co(α,p)62Ni, 57Fe(α,p)60Co, 56Fe(7Li,p)62Ni, and 55Mn(6Li,p)60Co reactions have been measured with 21-MeV α and 15-MeV lithium beams. Cross sections have been compared against calculations with the empire reaction code. Different input level density models have been tested. It was found that the Gilbert and Cameron [A. Gilbert and A. G. W. Cameron, Can. J. Phys. 43, 1446 (1965)] level density model is best to reproduce experimental data. Level densities and spin cutoff parameters for 62Ni and 60Co above the excitation energy range of discrete levels (in continuum) have been obtained with a Monte Carlo technique. Furthermore,more » excitation energy dependencies were found to be inconsistent with the Fermi-gas model.« less

  1. Analysis of mutant quantity and quality in human-hamster hybrid AL and AL-179 cells exposed to 137Cs-gamma or HZE-Fe ions

    NASA Technical Reports Server (NTRS)

    Waldren, C.; Vannais, D.; Drabek, R.; Gustafson, D.; Kraemer, S.; Lenarczyk, M.; Kronenberg, A.; Hei, T.; Ueno, A.; Chatterjee, A. (Principal Investigator)

    1998-01-01

    We measured the number of mutants and the kinds of mutations induced by 137Cs-gamma and by HZE-Fe (56Fe [600 MeV/amu, LET = 190 KeV/micrometer) in standard AL human hamster hybrid cells and in a new variant hybrid, AL-179. We found that HZE-Fe was more mutagenic than 137Cs-gamma per unit dose (about 1.6 fold), but was slightly less mutagenic per mean lethal dose, DO, at both the S1 and hprt- loci of AL cells. On the other hand, HZE-Fe induced about nine fold more complex S1- mutants than 137Cs-gamma rays, 28% vs 3%. 137Cs-gamma rays induced about twice as many S1- mutants and hprt-mutants in AL-179 as in AL cells, and about nine times more of the former were complex, and potentially unstable kinds of mutations.

  2. Absolute stability window and upper bound on the magnetic field strength in a strongly magnetized strange quark star

    NASA Astrophysics Data System (ADS)

    Isayev, A. A.

    2014-11-01

    Magnetized strange quark stars, composed of strange quark matter (SQM) and self-bound by strong interactions, can be formed if the energy per baryon of magnetized SQM is less than that of the most stable 56Fe nucleus under the zero external pressure and temperature. Utilizing the MIT bag model description of magnetized SQM under charge neutrality and beta equilibrium conditions, the corresponding absolute stability window in the parameter space of the theory is determined. It is shown that there exists the maximum magnetic field strength allowed by the condition of absolute stability of magnetized SQM. The value of this field, H 3 × 1018G, represents the upper bound on the magnetic field strength which can be reached in a strongly magnetized strange quark star.

  3. Phosphorus in the young supernova remnant Cassiopeia A.

    PubMed

    Koo, Bon-Chul; Lee, Yong-Hyun; Moon, Dae-Sik; Yoon, Sung-Chul; Raymond, John C

    2013-12-13

    Phosphorus ((31)P), which is essential for life, is thought to be synthesized in massive stars and dispersed into interstellar space when these stars explode as supernovae (SNe). Here, we report on near-infrared spectroscopic observations of the young SN remnant Cassiopeia A, which show that the abundance ratio of phosphorus to the major nucleosynthetic product iron ((56)Fe) in SN material is up to 100 times the average ratio of the Milky Way, confirming that phosphorus is produced in SNe. The observed range is compatible with predictions from SN nucleosynthetic models but not with the scenario in which the chemical elements in the inner SN layers are completely mixed by hydrodynamic instabilities during the explosion. PMID:24337291

  4. Cherenkov light detection as a velocity selector for uranium fission products at intermediate energies

    NASA Astrophysics Data System (ADS)

    Yamaguchi, T.; Enomoto, A.; Kouno, J.; Yamaki, S.; Matsunaga, S.; Suzaki, F.; Suzuki, T.; Abe, Y.; Nagae, D.; Okada, S.; Ozawa, A.; Saito, Y.; Sawahata, K.; Kitagawa, A.; Sato, S.

    2014-12-01

    The in-flight particle separation capability of intermediate-energy radioactive ion (RI) beams produced at a fragment separator can be improved with the Cherenkov light detection technique. The cone angle of Cherenkov light emission varies as a function of beam velocity. This can be exploited as a velocity selector for secondary beams. Using heavy ion beams available at the HIMAC synchrotron facility, the Cherenkov light angular distribution was measured for several thin radiators with high refractive indices (n = 1.9 ~ 2.1). A velocity resolution of ~10-3 was achieved for a 56Fe beam with an energy of 500 MeV/nucleon. Combined with the conventional rigidity selection technique coupled with energy-loss analysis, the present method will enable the efficient selection of an exotic species from huge amounts of various nuclides, such as uranium fission products at the BigRIPS fragment separator located at the RI Beam Factory.

  5. A comparison of the photocatalytic activity of six tunneled titanates

    SciTech Connect

    Sanford, Stephen; Misture, Scott T.; Edwards, Doreen D.

    2013-04-15

    The photocatalytic behavior of six tunneled titanates—Na{sub 0.7}Ga{sub 4.7}Ti{sub 0.3}O{sub 8}, Na{sub 0.8}Ga{sub 4.8}Ti{sub 1.2}O{sub 10}, Na{sub 0.8}Ga{sub 4.8}Ti{sub 2.2}O{sub 12}, K{sub 1}Ga{sub 17}Ti{sub 15}O{sub 56}, K{sub 1.5}Ga{sub 1.5}Ti{sub 6.5}O{sub 16}, and BaTi{sub 4}O{sub 9}—was investigated using methylene blue as an indicator and a xenon arc lamp as the radiation source. Powders prepared by solid state reaction had surface areas ranging from 0.40 to 1.58 m{sup 2}/g and particle sizes ranging from 1 to 25 μm. Bandgaps, as measured from diffuse reflectance data, ranged from 2.84 to 4.15 eV. Two of the tunneled titanates—Na{sub 0.8}Ga{sub 4.8}Ti{sub 1.2}O{sub 10} and Na{sub 0.7}Ga{sub 4.7}Ti{sub 0.3}O{sub 8}—exhibited negligible photocatalytic activity. The activities of Na{sub 0.8}Ga{sub 4.8}Ti{sub 2.2}O{sub 12}, KGa{sub 17}Ti{sub 15}O{sub 56}, and K{sub 1.5}Ga{sub 1.5}Ti{sub 6.5}O{sub 16} were similar to each other, exhibiting apparent first-order reaction rates of 0.275 to 0.31 h{sup −1} using 100 mg of powder in 125 ml of 20 μM methylene blue at room temperature. The BaTi{sub 4}O{sub 9} sample exhibited the highest photocatalytic activity with an apparent first-order reaction rate of 0.53 h{sup −1} under the same conditions. The addition of a RuO{sub 2} co-catalyst improved the photocatalytic activity of Na{sub 0.7}Ga{sub 4.7}Ti{sub 0.3}O{sub 8}, decreased the activity of BaTi{sub 4}O{sub 9}, and had little effect on the activity of the other powders. A comparison of the structural features in the six materials shows that photocatalytic activity is strongly related to the density of TiO{sub 6} octahedra in the different crystal structures. Among the gallium-containing tunneled titanates, photocatalytic activity increased with decreasing band gap. - Graphical abstract: Na{sub 0.7}Ga{sub 4.7}Ti{sub 0.3}O{sub 8}—One of the tunneled titanates investigated. Highlights: ► The photocatalytic activity of six tunneled titanates was compared. ► Na{sub 0.8}Ga{sub 4.8}Ti{sub 1.2}O{sub 10} and Na{sub 0.7}Ga{sub 4.7}Ti{sub 0.3}O{sub 8} exhibited negligible photocatalytic activity. ► The activities of Na{sub 0.8}Ga{sub 4.8}Ti{sub 2.2}O{sub 12}, KGa{sub 17}Ti{sub 15}O{sub 56}, and K{sub 1.5}Ga{sub 1.5}Ti{sub 6.5}O{sub 16} were similar to each other. ► BaTi{sub 4}O{sub 9} exhibited the highest photocatalytic activity. ► Photocatalytic activity is related to the density of TiO{sub 6} octahedra.

  6. High Precision Fe Isotope Analysis in low Concentration Samples by High Resolution MC-ICPMS

    NASA Astrophysics Data System (ADS)

    Chung, C.; Wu, J.; You, C.

    2009-12-01

    Iron availability has been shown to be the main limitation factor for phytoplankton growth in the ocean. However, due to the limitation of analytical technique, the database of dissolved Fe concentrations and isotope ratio distribution in the ocean is still very limited. In particular, the iron sources to the ocean remain uncertain. Aeolian dust from the continental is considered as the primary source, also the digenetic dissolution at the continental margins is proposed to contribute significant portion of iron content of the sea surface water. The field of Fe isotope geochemistry has seen important developments in methodology and scope since the advent of Multi-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS). Although increasing the number of replicates in High Resolution MC-ICPMS reduces the uncertainty related to instability in instrumental mass bias and counting statistics, many other parameters include mass fractionation during column separation, matrix effect in ICPMS analysis and the presence of isobaric interferences can affect the precision and accuracy of Fe isotopic analyses. In this study, a high precision analytical method of Fe isotope measurement for low concentration samples was developed using HR-MC-ICPMS. Several parameters that may affect the accuracy and precision of 56Fe/54Fe result such as background, instrumental mass discrimination, isobaric interferences, type of introduction system and acid molarity were identified and evaluated. External precisions better than 0.04‰ for δ56Fe can be achieve using only 10ng of iron sample with APEX and X-cone as introduction system. Significant improvement in terms of sample size was made. This method can be applied on very low concentration samples such as coral and seawater.

  7. Interactions between natural organic matter, sulfur, arsenic and iron oxides in re-oxidation compounds within riparian wetlands: nanoSIMS and X-ray adsorption spectroscopy evidences.

    PubMed

    Al-Sid-Cheikh, Maya; Pédrot, Mathieu; Dia, Aline; Guenet, Hélène; Vantelon, Delphine; Davranche, Mélanie; Gruau, Gérard; Delhaye, Thomas

    2015-05-15

    Arsenic (As) is a toxic and ubiquitous element which can be responsible for severe health problems. Recently, Nano-scale Secondary Ions Mass Spectrometry (nanoSIMS) analysis has been used to map organomineral assemblages. Here, we present a method adapted from Belzile et al. (1989) to collect freshly precipitated compounds of the re-oxidation period in a natural wetland environment using a polytetrafluoroethylene (PTFE) sheet scavenger. This method provides information on the bulk samples and on the specific interactions between metals (i.e. As) and the natural organic matter (NOM). Our method allows producing nanoSIMS imaging on natural colloid precipitates, including (75)As(-), (56)Fe(16)O(-), sulfur ((32)S(-)) and organic matter ((12)C(14)N) and to measure X-ray adsorption of sulfur (S) K-edge. A first statistical treatment on the nanoSIMS images highlights two main colocalizations: (1) (12)C(14)N(-), (32)S(-), (56)Fe(16)O(-) and (75)As(-), and (2) (12)C(14)N(-), (32)S(-) and (75)As(-). Principal component analyses (PCAs) support the importance of sulfur in the two main colocalizations firstly evidenced. The first component explains 70% of the variance in the distribution of the elements and is highly correlated with the presence of (32)S(-). The second component explains 20% of the variance and is highly correlated with the presence of (12)C(14)N(-). The X-ray adsorption near edge spectroscopy (XANES) on sulfur speciation provides a quantification of the organic (55%) and inorganic (45%) sulfur compositions. The co-existence of reduced and oxidized S forms might be attributed to a slow NOM kinetic oxidation process. Thus, a direct interaction between As and NOM through sulfur groups might be possible.

  8. Direct-Semidirect Thermal Neutron Capture Calculations

    SciTech Connect

    Arbanas, G; Dietrich, F S; Kerman, A K

    2005-12-20

    A method for computing direct-semidirect (DSD) neutron radiative capture is presented and applied to thermal neutron capture on {sup 19}F, {sup 27}Al, {sup 28,29.30}Si, {sup 35,37}Cl, {sup 39,41}K, {sup 56}Fe, and {sup 238}U, in support of data evaluation effort at the O.R.N.L. The DSD method includes both direct and semidirect capture; the latter is a core-polarization term in which the giant dipole resonance is formed. We study the effects of a commonly used ''density'' approximation to the EM operator and find it to be unsatisfactory for the nuclei considered here. We also study the magnitude of semidirect capture relative to the pure direct capture. Furthermore, we compare our results with those obtained from another direct capture code (Tedca [17]). We also compare our results with those obtained from analytical expression for external capture derived by Lane and Lynn [3], and its extension to include internal capture [7]. To estimate the effect of nuclear deformation on direct capture, we computed direct thermal capture on {sup 238}U with and without imposition of spherical symmetry. Direct capture for a spherically symmetric {sup 238}U was approximately 6 mb, while a quadrupole deformation of 0.215 on the shape of {sup 238}U lowers this cross section down to approximately 2 mb. This result suggests that effects of nuclear deformation on direct capture warrant a further study. We also find out that contribution to the direct capture on {sup 238}U from the nuclear interior significantly cancels that coming from the exterior region, and hence both contributions must be taken into account. We reproduced a well known discrepancy between the computed and observed branching ratios in {sup 56}Fe(n,{gamma}). This will lead us to revisit the concept of doorway states in the particle-hole model.

  9. Fe, Zn, and Cd stable isotopes from the eastern tropical South Pacific from GEOTRACES cruise GP16 - Methods and data

    NASA Astrophysics Data System (ADS)

    Helgoe, J. M.; Townsend, E.; John, S.

    2014-12-01

    A new method has been developed for the rapid analysis of metal concentrations and stable isotope ratios using a prepFAST automated sample processing robot. Although concentrations and isotopes are processed separately, similar methods are used for both. Initially all seawater is acidified to pH 2. Then Nobias resin with EDTA/IDA functional groups is added to either 10mL of sample for concentrations or ~1L samples for isotopes. Fe binds to the resin at low pH, and the pH is subsequently raised to allow Zn and Cd to bind. For concentration analyses, all subsequent chemistry is automated on the prepFAST including removal of seawater, rinsing of resin, and elution of resin into acid. For isotope samples these extraction techniques are performed manually, but the subsequent purification of Fe, Zn, and Cd by anion exchange chromatography is automated using the prepFAST. With these new methods, samples from the US GEOTRACES cruise GP16, in the eastern tropical South Pacific, are being analyzed. High concentrations of dissolved Fe are observed near the continental shelf and near submarine hydrothermal vents. Interestingly, isotope data show that dissolved Fe near the continental shelf generally has a δ56Fe close to 0 ‰. This δ56 Fe signature is suggestive of a non-reductive dissolution source for Fe, as Fe(II) released by reductive dissolution is typically closer to -2 ‰. Preliminary data show nutrient-type profiles for Zn and Cd, with Zn matching Si and Cd having a similar distribution to P. An increase in dissolved Zn near hydrothermal vents suggests a possible hydrothermal zinc source to the deep ocean. Continuing analysis of isotope data will reveal more about the source and biogeochemical cycling of these three chemically and biologically important trace metals throughout the eastern tropical Pacific Ocean.

  10. Calculations of Excitation Functions of Some Structural Fusion Materials for ( n, t) Reactions up to 50 MeV Energy

    NASA Astrophysics Data System (ADS)

    Tel, E.; Durgu, C.; Aktı, N. N.; Okuducu, Ş.

    2010-06-01

    Fusion serves an inexhaustible energy for humankind. Although there have been significant research and development studies on the inertial and magnetic fusion reactor technology, there is still a long way to go to penetrate commercial fusion reactors to the energy market. Tritium self-sufficiency must be maintained for a commercial power plant. For self-sustaining (D-T) fusion driver tritium breeding ratio should be greater than 1.05. So, the working out the systematics of ( n, t) reaction cross sections is of great importance for the definition of the excitation function character for the given reaction taking place on various nuclei at different energies. In this study, ( n, t) reactions for some structural fusion materials such as 27Al, 51V, 52Cr, 55Mn, and 56Fe have been investigated. The new calculations on the excitation functions of 27Al( n, t)25Mg, 51V( n, t)49Ti, 52Cr( n, t)50V, 55Mn( n, t)53Cr and 56Fe( n, t)54Mn reactions have been carried out up to 50 MeV incident neutron energy. In these calculations, the pre-equilibrium and equilibrium effects have been investigated. The pre-equilibrium calculations involve the new evaluated the geometry dependent hybrid model, hybrid model and the cascade exciton model. Equilibrium effects are calculated according to the Weisskopf-Ewing model. Also in the present work, we have calculated ( n, t) reaction cross-sections by using new evaluated semi-empirical formulas developed by Tel et al. at 14-15 MeV energy. The calculated results are discussed and compared with the experimental data taken from the literature.

  11. Diffusion-driven magnesium and iron isotope fractionation in Hawaiian olivine

    USGS Publications Warehouse

    Teng, F.-Z.; Dauphas, N.; Helz, R.T.; Gao, S.; Huang, S.

    2011-01-01

    Diffusion plays an important role in Earth sciences to estimate the timescales of geological processes such as erosion, sediment burial, and magma cooling. In igneous systems, these diffusive processes are recorded in the form of crystal zoning. However, meaningful interpretation of these signatures is often hampered by the fact that they cannot be unambiguously ascribed to a single process (e.g., magmatic fractionation, diffusion limited transport in the crystal or in the liquid). Here we show that Mg and Fe isotope fractionations in olivine crystals can be used to trace diffusive processes in magmatic systems. Over sixty olivine fragments from Hawaiian basalts show isotopically fractionated Mg and Fe relative to basalts worldwide, with up to 0.4??? variation in 26Mg/24Mg ratios and 1.6??? variation in 56Fe/54Fe ratios. The linearly and negatively correlated Mg and Fe isotopic compositions [i.e., ??56Fe=(??3.3??0.3)????26Mg], co-variations of Mg and Fe isotopic compositions with Fe/Mg ratios of olivine fragments, and modeling results based on Mg and Fe elemental profiles demonstrate the coupled Mg and Fe isotope fractionation to be a manifestation of Mg-Fe inter-diffusion in zoned olivines during magmatic differentiation. This characteristic can be used to constrain the nature of mineral zoning in igneous and metamorphic rocks, and hence determine the residence times of crystals in magmas, the composition of primary melts, and the duration of metamorphic events. With improvements in methodology, in situ isotope mapping will become an essential tool of petrology to identify diffusion in crystals. ?? 2011 Elsevier B.V.

  12. A comparison of the measured responses of a tissue-equivalent proportional counter to high energy heavy (HZE) particles and those simulated using the Geant4 Monte Carlo code

    PubMed Central

    Taddei, Phillip J.; Zhao, Zhongxiang; Borak, Thomas B.

    2010-01-01

    Monte Carlo simulations of heavy ion interactions using the Geant4 toolkit were compared with measurements of energy deposition in a spherical tissue-equivalent proportional counter (TEPC). A spherical cavity with a physical diameter of 12.7 mm was filled with propane-based tissue-equivalent gas surrounded by a wall of A-150 tissue-equivalent plastic that was 2.54 mm to thick. Measurements and Monte Carlo simulations were used to record the energy deposition and the trajectory of the incident particle on an event-by-event basis for ions ranging in atomic number from 2 (4He) to 26 (56Fe) and in energy from 200 MeV/nucleon to 1000 MeV/nucleon. In the simulations, tracking of secondary electrons was terminated when the range of an electron was below a specified threshold. The effects of range cuts for electrons at 0.5 μm, 1 μm, 10 μm, and 100 μm were evaluated. To simulate an energy deposition influenced by large numbers of low energy electrons with large transverse momentum, it was necessary to track electrons down to range cuts of 10 μm or less. The Geant4 simulated data closely matched the measured data acquired using a TEPC for incident particles traversing the center of the detector as well as near the gas-wall interface. Values of frequency mean lineal energy and dose mean lineal energy were within 8% of the measured data. The production of secondary particles in the aluminum vacuum chamber had no effect on the response of the TEPC for 56Fe at 1000 MeV/nucleon. The results of this study confirm that Geant4 can simulate patterns of energy deposition for existing microdosimeters and is valuable for improving the design of a new generation of detectors used for space dosimetry and for characterizing particle beams used in hadron radiotherapy. PMID:20862212

  13. Galactic Cosmic Radiation Leads to Cognitive Impairment and Increased Aβ Plaque Accumulation in a Mouse Model of Alzheimer’s Disease

    PubMed Central

    Cherry, Jonathan D.; Liu, Bin; Frost, Jeffrey L.; Lemere, Cynthia A.; Williams, Jacqueline P.; Olschowka, John A.; O’Banion, M. Kerry

    2012-01-01

    Galactic Cosmic Radiation consisting of high-energy, high-charged (HZE) particles poses a significant threat to future astronauts in deep space. Aside from cancer, concerns have been raised about late degenerative risks, including effects on the brain. In this study we examined the effects of 56Fe particle irradiation in an APP/PS1 mouse model of Alzheimer’s disease (AD). We demonstrated 6 months after exposure to 10 and 100 cGy 56Fe radiation at 1 GeV/µ, that APP/PS1 mice show decreased cognitive abilities measured by contextual fear conditioning and novel object recognition tests. Furthermore, in male mice we saw acceleration of Aβ plaque pathology using Congo red and 6E10 staining, which was further confirmed by ELISA measures of Aβ isoforms. Increases were not due to higher levels of amyloid precursor protein (APP) or increased cleavage as measured by levels of the β C-terminal fragment of APP. Additionally, we saw no change in microglial activation levels judging by CD68 and Iba-1 immunoreactivities in and around Aβ plaques or insulin degrading enzyme, which has been shown to degrade Aβ. However, immunohistochemical analysis of ICAM-1 showed evidence of endothelial activation after 100 cGy irradiation in male mice, suggesting possible alterations in Aβ trafficking through the blood brain barrier as a possible cause of plaque increase. Overall, our results show for the first time that HZE particle radiation can increase Aβ plaque pathology in an APP/PS1 mouse model of AD. PMID:23300905

  14. Galactic cosmic radiation leads to cognitive impairment and increased aβ plaque accumulation in a mouse model of Alzheimer's disease.

    PubMed

    Cherry, Jonathan D; Liu, Bin; Frost, Jeffrey L; Lemere, Cynthia A; Williams, Jacqueline P; Olschowka, John A; O'Banion, M Kerry

    2012-01-01

    Galactic Cosmic Radiation consisting of high-energy, high-charged (HZE) particles poses a significant threat to future astronauts in deep space. Aside from cancer, concerns have been raised about late degenerative risks, including effects on the brain. In this study we examined the effects of (56)Fe particle irradiation in an APP/PS1 mouse model of Alzheimer's disease (AD). We demonstrated 6 months after exposure to 10 and 100 cGy (56)Fe radiation at 1 GeV/µ, that APP/PS1 mice show decreased cognitive abilities measured by contextual fear conditioning and novel object recognition tests. Furthermore, in male mice we saw acceleration of Aβ plaque pathology using Congo red and 6E10 staining, which was further confirmed by ELISA measures of Aβ isoforms. Increases were not due to higher levels of amyloid precursor protein (APP) or increased cleavage as measured by levels of the β C-terminal fragment of APP. Additionally, we saw no change in microglial activation levels judging by CD68 and Iba-1 immunoreactivities in and around Aβ plaques or insulin degrading enzyme, which has been shown to degrade Aβ. However, immunohistochemical analysis of ICAM-1 showed evidence of endothelial activation after 100 cGy irradiation in male mice, suggesting possible alterations in Aβ trafficking through the blood brain barrier as a possible cause of plaque increase. Overall, our results show for the first time that HZE particle radiation can increase Aβ plaque pathology in an APP/PS1 mouse model of AD.

  15. Atom exchange between aqueous Fe(II) and structural Fe in clay minerals.

    PubMed

    Neumann, Anke; Wu, Lingling; Li, Weiqiang; Beard, Brian L; Johnson, Clark M; Rosso, Kevin M; Frierdich, Andrew J; Scherer, Michelle M

    2015-03-01

    Due to their stability toward reductive dissolution, Fe-bearing clay minerals are viewed as a renewable source of Fe redox activity in diverse environments. Recent findings of interfacial electron transfer between aqueous Fe(II) and structural Fe in clay minerals and electron conduction in octahedral sheets of nontronite, however, raise the question whether Fe interaction with clay minerals is more dynamic than previously thought. Here, we use an enriched isotope tracer approach to simultaneously trace Fe atom movement from the aqueous phase to the solid ((57)Fe) and from the solid into the aqueous phase ((56)Fe). Over 6 months, we observed a significant decrease in aqueous (57)Fe isotope fraction, with a fast initial decrease which slowed after 3 days and stabilized after about 50 days. For the aqueous (56)Fe isotope fraction, we observed a similar but opposite trend, indicating that Fe atom movement had occurred in both directions: from the aqueous phase into the solid and from the solid into aqueous phase. We calculated that 5-20% of structural Fe in clay minerals NAu-1, NAu-2, and SWa-1 exchanged with aqueous Fe(II), which significantly exceeds the Fe atom layer exposed directly to solution. Calculations based on electron-hopping rates in nontronite suggest that the bulk conduction mechanism previously demonstrated for hematite1 and suggested as an explanation for the significant Fe atom exchange observed in goethite2 may be a plausible mechanism for Fe atom exchange in Fe-bearing clay minerals. Our finding of 5-20% Fe atom exchange in clay minerals indicates that we need to rethink how Fe mobility affects the macroscopic properties of Fe-bearing phyllosilicates and its role in Fe biogeochemical cycling, as well as its use in a variety of engineered applications, such as landfill liners and nuclear repositories.

  16. Space radiation-associated lung injury in a murine model.

    PubMed

    Christofidou-Solomidou, Melpo; Pietrofesa, Ralph A; Arguiri, Evguenia; Schweitzer, Kelly S; Berdyshev, Evgeny V; McCarthy, Maureen; Corbitt, Astrid; Alwood, Joshua S; Yu, Yongjia; Globus, Ruth K; Solomides, Charalambos C; Ullrich, Robert L; Petrache, Irina

    2015-03-01

    Despite considerable progress in identifying health risks to crewmembers related to exposure to galactic/cosmic rays and solar particle events (SPE) during space travel, its long-term effects on the pulmonary system are unknown. We used a murine risk projection model to investigate the impact of exposure to space-relevant radiation (SR) on the lung. C3H mice were exposed to (137)Cs gamma rays, protons (acute, low-dose exposure mimicking the 1972 SPE), 600 MeV/u (56)Fe ions, or 350 MeV/u (28)Si ions at the NASA Space Radiation Laboratory at Brookhaven National Laboratory. Animals were irradiated at the age of 2.5 mo and evaluated 23.5 mo postirradiation, at 26 mo of age. Compared with age-matched nonirradiated mice, SR exposures led to significant air space enlargement and dose-dependent decreased systemic oxygenation levels. These were associated with late mild lung inflammation and prominent cellular injury, with significant oxidative stress and apoptosis (caspase-3 activation) in the lung parenchyma. SR, especially high-energy (56)Fe or (28)Si ions markedly decreased sphingosine-1-phosphate levels and Akt- and p38 MAPK phosphorylation, depleted anti-senescence sirtuin-1 and increased biochemical markers of autophagy. Exposure to SR caused dose-dependent, pronounced late lung pathological sequelae consistent with alveolar simplification and cellular signaling of increased injury and decreased repair. The associated systemic hypoxemia suggested that this previously uncharacterized space radiation-associated lung injury was functionally significant, indicating that further studies are needed to define the risk and to develop appropriate lung-protective countermeasures for manned deep space missions. PMID:25526737

  17. Quantification of dissolved iron sources to the North Atlantic Ocean.

    PubMed

    Conway, Tim M; John, Seth G

    2014-07-10

    Dissolved iron is an essential micronutrient for marine phytoplankton, and its availability controls patterns of primary productivity and carbon cycling throughout the oceans. The relative importance of different sources of iron to the oceans is not well known, however, and flux estimates from atmospheric dust, hydrothermal vents and oceanic sediments vary by orders of magnitude. Here we present a high-resolution transect of dissolved stable iron isotope ratios (δ(56)Fe) and iron concentrations ([Fe]) along a section of the North Atlantic Ocean. The different iron sources can be identified by their unique δ(56)Fe signatures, which persist throughout the water column. This allows us to calculate the relative contribution from dust, hydrothermal venting and reductive and non-reductive sedimentary release to the dissolved phase. We find that Saharan dust aerosol is the dominant source of dissolved iron along the section, contributing 71-87 per cent of dissolved iron. Additional sources of iron are non-reductive release from oxygenated sediments on the North American margin (10-19 per cent), reductive sedimentary dissolution on the African margin (1-4 per cent) and hydrothermal venting at the Mid-Atlantic Ridge (2-6 per cent). Our data also indicate that hydrothermal vents in the North Atlantic are a source of isotopically light iron, which travels thousands of kilometres from vent sites, potentially influencing surface productivity. Changes in the relative importance of the different iron sources through time may affect interactions between the carbon cycle and climate.

  18. Space radiation-associated lung injury in a murine model

    PubMed Central

    Pietrofesa, Ralph A.; Arguiri, Evguenia; Schweitzer, Kelly S.; Berdyshev, Evgeny V.; McCarthy, Maureen; Corbitt, Astrid; Alwood, Joshua S.; Yu, Yongjia; Globus, Ruth K.; Solomides, Charalambos C.; Ullrich, Robert L.; Petrache, Irina

    2014-01-01

    Despite considerable progress in identifying health risks to crewmembers related to exposure to galactic/cosmic rays and solar particle events (SPE) during space travel, its long-term effects on the pulmonary system are unknown. We used a murine risk projection model to investigate the impact of exposure to space-relevant radiation (SR) on the lung. C3H mice were exposed to 137Cs gamma rays, protons (acute, low-dose exposure mimicking the 1972 SPE), 600 MeV/u 56Fe ions, or 350 MeV/u 28Si ions at the NASA Space Radiation Laboratory at Brookhaven National Laboratory. Animals were irradiated at the age of 2.5 mo and evaluated 23.5 mo postirradiation, at 26 mo of age. Compared with age-matched nonirradiated mice, SR exposures led to significant air space enlargement and dose-dependent decreased systemic oxygenation levels. These were associated with late mild lung inflammation and prominent cellular injury, with significant oxidative stress and apoptosis (caspase-3 activation) in the lung parenchyma. SR, especially high-energy 56Fe or 28Si ions markedly decreased sphingosine-1-phosphate levels and Akt- and p38 MAPK phosphorylation, depleted anti-senescence sirtuin-1 and increased biochemical markers of autophagy. Exposure to SR caused dose-dependent, pronounced late lung pathological sequelae consistent with alveolar simplification and cellular signaling of increased injury and decreased repair. The associated systemic hypoxemia suggested that this previously uncharacterized space radiation-associated lung injury was functionally significant, indicating that further studies are needed to define the risk and to develop appropriate lung-protective countermeasures for manned deep space missions. PMID:25526737

  19. Genotype differences in anxiety and fear learning and memory of WT and ApoE4 mice associated with enhanced generation of hippocampal reactive oxygen species.

    PubMed

    Villasana, Laura E; Weber, Sydney; Akinyeke, Tunde; Raber, Jacob

    2016-09-01

    Apolipoprotein E (apoE), involved in cholesterol and lipid metabolism, also influences cognitive function and injury repair. In humans, apoE is expressed in three isoforms. E4 is a risk factor for age-related cognitive decline and Alzheimer's disease, particularly in women. E4 might also be a risk factor for developing behavioral and cognitive changes following (56) Fe irradiation, a component of the space environment astronauts are exposed to during missions. These changes might be related to enhanced generation of reactive oxygen species (ROS). In this study, we compared the behavioral and cognitive performance of sham-irradiated and irradiated wild-type (WT) mice and mice expressing the human E3 or E4 isoforms, and assessed the generation of ROS in hippocampal slices from these mice. E4 mice had greater anxiety-like and conditioned fear behaviors than WT mice, and these genotype differences were associated with greater levels of ROS in E4 than WT mice. The greater generation of ROS in the hippocampus of E4 than WT mice might contribute to their higher anxiety levels and enhanced fear conditioning. In E4, but not WT, mice, phorbol-12-myristate-13-acetate-treated hippocampal slices showed more dihydroxy ethidium oxidation in sham-irradiated than irradiated mice and hippocampal heme oxygenase-1 levels were higher in irradiated than sham-irradiated E4 mice. Mice with apolipoprotein E4 (E4), a risk factor for Alzheimer's disease, have greater anxiety-like and conditioned fear behaviors than wild-type (WT) mice. Generation of reactive oxygen species (ROS, in red) 3 months following (56) Fe irradiation, a component of the space environment astronauts are exposed to, is more pronounced in the hippocampus of E4 than WT mice. In E4, but not WT, mice, hippocampal levels of the oxidative stress-relevant marker heme oxygenase-1 are higher in irradiated than sham-irradiated E4 mice. PMID:27412623

  20. Galactic cosmic radiation leads to cognitive impairment and increased aβ plaque accumulation in a mouse model of Alzheimer's disease.

    PubMed

    Cherry, Jonathan D; Liu, Bin; Frost, Jeffrey L; Lemere, Cynthia A; Williams, Jacqueline P; Olschowka, John A; O'Banion, M Kerry

    2012-01-01

    Galactic Cosmic Radiation consisting of high-energy, high-charged (HZE) particles poses a significant threat to future astronauts in deep space. Aside from cancer, concerns have been raised about late degenerative risks, including effects on the brain. In this study we examined the effects of (56)Fe particle irradiation in an APP/PS1 mouse model of Alzheimer's disease (AD). We demonstrated 6 months after exposure to 10 and 100 cGy (56)Fe radiation at 1 GeV/µ, that APP/PS1 mice show decreased cognitive abilities measured by contextual fear conditioning and novel object recognition tests. Furthermore, in male mice we saw acceleration of Aβ plaque pathology using Congo red and 6E10 staining, which was further confirmed by ELISA measures of Aβ isoforms. Increases were not due to higher levels of amyloid precursor protein (APP) or increased cleavage as measured by levels of the β C-terminal fragment of APP. Additionally, we saw no change in microglial activation levels judging by CD68 and Iba-1 immunoreactivities in and around Aβ plaques or insulin degrading enzyme, which has been shown to degrade Aβ. However, immunohistochemical analysis of ICAM-1 showed evidence of endothelial activation after 100 cGy irradiation in male mice, suggesting possible alterations in Aβ trafficking through the blood brain barrier as a possible cause of plaque increase. Overall, our results show for the first time that HZE particle radiation can increase Aβ plaque pathology in an APP/PS1 mouse model of AD. PMID:23300905

  1. Ab initio calculations of the Fe(II) and Fe(III) isotopic effects in citrates, nicotianamine, and phytosiderophore, and new Fe isotopic measurements in higher plants

    NASA Astrophysics Data System (ADS)

    Moynier, Frédéric; Fujii, Toshiyuki; Wang, Kun; Foriel, Julien

    2013-05-01

    Iron is one of the most abundant transition metal in higher plants and variations in its isotopic compositions can be used to trace its utilization. In order to better understand the effect of plant-induced isotopic fractionation on the global Fe cycling, we have estimated by quantum chemical calculations the magnitude of the isotopic fractionation between different Fe species relevant to the transport and storage of Fe in higher plants: Fe(II)-citrate, Fe(III)-citrate, Fe(II)-nicotianamine, and Fe(III)-phytosiderophore. The ab initio calculations show firstly, that Fe(II)-nicotianamine is ˜3‰ (56Fe/54Fe) isotopically lighter than Fe(III)-phytosiderophore; secondly, even in the absence of redox changes of Fe, change in the speciation alone can create up to ˜1.5‰ isotopic fractionation. For example, Fe(III)-phytosiderophore is up to 1.5‰ heavier than Fe(III)-citrate2 and Fe(II)-nicotianamine is up to 1‰ heavier than Fe(II)-citrate. In addition, in order to better understand the Fe isotopic fractionation between different plant components, we have analyzed the iron isotopic composition of different organs (roots, seeds, germinated seeds, leaves and stems) from six species of higher plants: the dicot lentil (Lens culinaris), and the graminaceous monocots Virginia wild rye (Elymus virginicus), Johnsongrass (Sorghum halepense), Kentucky bluegrass (Poa pratensis), river oat (Uniola latifolia), and Indian goosegrass (Eleusine indica). The calculations may explain that the roots of strategy-II plants (Fe(III)-phytosiderophore) are isotopically heavier (by about 1‰ for the δ56Fe) than the upper parts of the plants (Fe transported as Fe(III)-citrate in the xylem or Fe(II)-nicotianamine in the phloem). In addition, we suggest that the isotopic variations observed between younger and older leaves could be explained by mixing of Fe received from the xylem and the phloem.

  2. Iron isotope fractionation between aqueous ferrous iron and goethite

    NASA Astrophysics Data System (ADS)

    Beard, Brian L.; Handler, Robert M.; Scherer, Michelle M.; Wu, Lingling; Czaja, Andrew D.; Heimann, Adriana; Johnson, Clark M.

    2010-06-01

    The equilibrium Fe isotope fractionation factor between aqueous Fe(II) and goethite has been experimentally measured to be - 1.05 ± 0.08‰ in 56Fe/54Fe (2σ) at 22 °C, using the three-isotope method. Experiments were done using two sizes of goethite (81 × 11 nm and 590 × 42 nm), and the experimental products were subjected to serial extraction using acid partial dissolution techniques to determine if surface Fe(III) atoms have different isotopic properties than the bulk goethite. These experiments indicate that the interaction of Fe(II)aq and goethite is dynamic and results in complete or near-complete Fe isotope exchange over 30 days, involving at least four components: Fe(II)aq, goethite, sorbed Fe(II), and Fe(III)surface. The equilibrium fractionation factor between Fe(II)aq and Fe(II)sorb is the same for both sizes of goethite, at Δ56FeFe(II)aq-Fe(II)sorb = - 1.24 ± 0.14‰; this fractionation factor is significantly different than the results of previous studies on Fe(II) sorption to goethite. The proportion of the Fe(III)surface component is greatest in the experiments that used the smallest goethite, and the Fe(III)surface-Fe(II)aq fractionation is estimated to be at least + 2.1‰. The high Fe(III)surface-Fe(II)aq fractionation may exert a significant influence on the Fe isotope compositions of aqueous Fe(II) in natural systems that contain nanoparticulate goethite, including those involving bacterial iron reduction. These results demonstrate that the isotopic properties of nano-scale minerals may be distinct from micron-scale or larger minerals, as is the case for other thermodynamic properties of nanoparticles.

  3. Changes in the distribution and function of leukocytes after whole-body iron ion irradiation

    PubMed Central

    Gridley, Daila S.; Pecaut, Michael J.

    2016-01-01

    High-energy particle radiation could have a considerable impact on health during space missions. This study evaluated C57BL/6 mice on Day 40 after total-body 56Fe26+ irradiation at 0, 1, 2 and 3 gray (Gy). Radiation consistently increased thymus mass (one-way ANOVA: P < 0.005); spleen, liver and lung masses were similar among all groups. In the blood, there was no radiation effect on the white blood cell (WBC) count or major leukocyte types. However, the red blood cell count, hemoglobin, hematocrit and the CD8+ T cytotoxic (Tc) cell count and percentage all decreased, while both the CD4:CD8 (Th:Tc) cell ratio and spontaneous blastogenesis increased, in one or more irradiated groups compared with unirradiated controls (P < 0.05 vs 0 Gy). In contrast, splenic WBC, lymphocyte, B cell and T helper (Th) counts, %B cells and the CD4:CD8 ratio were all significantly elevated, while Tc percentages decreased, in one or more of the irradiated groups compared with controls (P < 0.05 vs 0 Gy). Although there were trends for minor, radiation-induced increases in %CD11b+ granulocytes in the spleen, cells double-labeled with adhesion markers (CD11b+CD54+, CD11b+CD62E+) were normal. Splenocyte spontaneous blastogenesis and that induced by mitogens (PHA, ConA, LPS) was equivalent to normal. In bone marrow, the percentage of cells expressing stem cell markers, Sca-1 and CD34/Sca-1, were low in one or more of the irradiated groups (P < 0.05 vs 0 Gy). Collectively, the data indicate that significant immunological abnormalities still exist more than a month after 56Fe irradiation and that there are differences dependent upon body compartment. PMID:27380804

  4. The effects of proton exposure on neurochemistry and behavior

    NASA Technical Reports Server (NTRS)

    Shukitt-Hale, B.; Szprengiel, A.; Pluhar, J.; Rabin, B. M.; Joseph, J. A.

    2004-01-01

    Future space missions will involve long-term travel beyond the magnetic field of the Earth, where astronauts will be exposed to radiation hazards such as those that arise from galactic cosmic rays. Galactic cosmic rays are composed of protons, alpha particles, and particles of high energy and charge (HZE particles). Research by our group has shown that exposure to HZE particles, primarily 600 MeV/n and 1 GeV/n 56Fe, can produce significant alterations in brain neurochemistry and behavior. However, given that protons can make up a significant portion of the radiation spectrum, it is important to study their effects on neural functioning and on related performance. Therefore, these studies examined the effects of exposure to proton irradiation on neurochemical and behavioral endpoints, including dopaminergic functioning, amphetamine-induced conditioned taste aversion learning, and spatial learning and memory as measured by the Morris water maze. Male Sprague-Dawley rats received a dose of 0, 1.5, 3.0 or 4.0 Gy of 250 MeV protons at Loma Linda University and were tested in the different behavioral tests at various times following exposure. Results showed that there was no effect of proton irradiation at any dose on any of the endpoints measured. Therefore, there is a contrast between the insignificant effects of high dose proton exposure and the dramatic effectiveness of low dose (<0.1 Gy) exposures to 56Fe particles on both neurochemical and behavioral endpoints. Published by Elsevier Ltd on behalf of COSPAR.

  5. The effects of proton exposure on neurochemistry and behavior

    NASA Astrophysics Data System (ADS)

    Shukitt-Hale, B.; Joseph, J.; Rabin, B.

    Future space missions will involve long-term travel beyond the magnetic field of the Earth, where astronauts will be exposed to radiation hazards such as those that arise from galactic cosmic rays. Galactic cosmic rays are composed of protons, alpha particles, and particles of high energy and charge (HZE particles). Research by our group has shown that exposure to HZE particles, primarily 600 MeV/n and 1 GeV/n 56Fe, can produce significant alterations in brain neurochemistry and behavior. However, given that protons can make up a significant portion of the radiation spectrum, it is important to study their effects on neural functioning and on related performance. Therefore, these studies exa mined the effects of exposure to proton irradiation on neurochemical and behavioral endpoints, including dopaminergic functioning, amphetamine-induced conditioned taste aversion learning, operant conditioning, and spatial learning and memory as measured by the Morris water maze. Male Sprague-Dawley rats received a dose of 0, 1.5, 3.0 or 4.0 Gy of 250MeV protons at Loma Linda University and were tested in the different behavioral tests at various times following exposure. Results showed that there was no e fect of protonf irradiation at any dose on any of the endpoints measured. Therefore, there is a contrast between the insignificant effects of high dose proton exposure and the dramatic effectiveness of low dose (<0.1 Gy) exposures to 56Fe particles on both neurochemical and behavioral endpoints. Supported by N.A.S.A. Grant NAG9-1190.

  6. Space radiation-associated lung injury in a murine model.

    PubMed

    Christofidou-Solomidou, Melpo; Pietrofesa, Ralph A; Arguiri, Evguenia; Schweitzer, Kelly S; Berdyshev, Evgeny V; McCarthy, Maureen; Corbitt, Astrid; Alwood, Joshua S; Yu, Yongjia; Globus, Ruth K; Solomides, Charalambos C; Ullrich, Robert L; Petrache, Irina

    2015-03-01

    Despite considerable progress in identifying health risks to crewmembers related to exposure to galactic/cosmic rays and solar particle events (SPE) during space travel, its long-term effects on the pulmonary system are unknown. We used a murine risk projection model to investigate the impact of exposure to space-relevant radiation (SR) on the lung. C3H mice were exposed to (137)Cs gamma rays, protons (acute, low-dose exposure mimicking the 1972 SPE), 600 MeV/u (56)Fe ions, or 350 MeV/u (28)Si ions at the NASA Space Radiation Laboratory at Brookhaven National Laboratory. Animals were irradiated at the age of 2.5 mo and evaluated 23.5 mo postirradiation, at 26 mo of age. Compared with age-matched nonirradiated mice, SR exposures led to significant air space enlargement and dose-dependent decreased systemic oxygenation levels. These were associated with late mild lung inflammation and prominent cellular injury, with significant oxidative stress and apoptosis (caspase-3 activation) in the lung parenchyma. SR, especially high-energy (56)Fe or (28)Si ions markedly decreased sphingosine-1-phosphate levels and Akt- and p38 MAPK phosphorylation, depleted anti-senescence sirtuin-1 and increased biochemical markers of autophagy. Exposure to SR caused dose-dependent, pronounced late lung pathological sequelae consistent with alveolar simplification and cellular signaling of increased injury and decreased repair. The associated systemic hypoxemia suggested that this previously uncharacterized space radiation-associated lung injury was functionally significant, indicating that further studies are needed to define the risk and to develop appropriate lung-protective countermeasures for manned deep space missions.

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

    SciTech Connect

    Nabi, Jameel-Un; Tawfik, Abdel Nasser

    2013-03-15

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

  8. Mobility of iron and nickel at low temperatures: Implications for 60Fe-60Ni systematics of chondrules from unequilibrated ordinary chondrites

    NASA Astrophysics Data System (ADS)

    Telus, Myriam; Huss, Gary R.; Ogliore, Ryan C.; Nagashima, Kazuhide; Howard, Daryl L.; Newville, Matthew G.; Tomkins, Andrew G.

    2016-04-01

    The Fe and Ni isotopic composition of ferromagnesian silicates in chondrules from unequilibrated ordinary chondrites (UOCs) have been used to estimate the initial abundance of the short-lived radionuclide, 60Fe, in the early Solar System. However, these estimates vary widely, and there are systematic discrepancies in initial 60Fe/56Fe ratios inferred from in situ and bulk analyses of chondrules. A possible explanation is that the Fe-Ni isotope system in UOC chondrules has not remained closed (a necessary condition for isotopic dating), and Fe and Ni have been redistributed since the chondrules formed. In order to evaluate this, we collected high-spatial-resolution X-ray fluorescence (XRF) maps of UOC chondrules to better understand the distribution and mobility of Fe and Ni at the low metamorphic temperatures of these chondrites. We used synchrotron X-ray-fluorescence microscopy to map the distribution of Fe, Ni and other elements in portions of 71 chondrules from 8 UOCs (types 3.00-3.2). The synchrotron XRF maps show clear enrichment of Fe and/or Ni in fractures ranging down to micrometer scale in chondrules from all UOCs analyzed for this study regardless of petrologic type and regardless of whether fall or find, indicating that there was significant exchange of Fe and Ni between chondrules and matrix and that the Fe-Ni system was not closed. Sixty percent of chondrules in Semarkona (LL3.00) have Fe and Ni enrichment along fractures, while 80-100% of chondrules analyzed from the other UOCs show these enrichments. Mobilization was likely a result of fluid transport of Fe and Ni during aqueous alteration on the parent body and/or during terrestrial weathering. In situ and bulk Fe-Ni analyses that incorporate extraneous Fe and Ni from chondrule fractures will result in lowering the inferred initial 60Fe/56Fe ratios.

  9. Kinetics of iron import into developing mouse organs determined by a pup-swapping method.

    PubMed

    Chakrabarti, Mrinmoy; Barlas, Mirza Nofil; McCormick, Sean P; Lindahl, Lora S; Lindahl, Paul A

    2015-01-01

    The kinetics of dietary iron import into various organs of mice were evaluated using a novel pup-swapping approach. Newborn pups whose bodies primarily contained (56)Fe or (57)Fe were swapped at birth such that each nursed on milk containing the opposite isotope. A pup from each litter was euthanized weekly over a 7-week period. Blood plasma was obtained, and organs were isolated typically after flushing with Ringer's buffer. (56)Fe and (57)Fe concentrations were determined for organs and plasma; organ volumes were also determined. Mössbauer spectra of equivalent (57)Fe-enriched samples were used to quantify residual blood in organs; this fraction was excluded from later analysis. Rates of import into brain, spleen, heart, and kidneys were highest during the first 2 weeks of life. In contrast, half of iron in the newborn liver exited during that time, and influx peaked later. Two mathematical models were developed to analyze the import kinetics. The only model that simulated the data adequately assumed that an iron-containing species enters the plasma and converts into a second species and that both are independently imported into organs. Consistent with this, liquid chromatography with an on-line ICP-MS detector revealed numerous iron species in plasma besides transferrin. Model fitting required that the first species, assigned to non-transferrin-bound iron, imports faster into organs than the second, assigned to transferrin-bound-iron. Non-transferrin-bound iron rather than transferrin-bound-iron appears to play the dominant role in importing iron into organs during early development of healthy mice.

  10. Iron isotope composition of some Archean and Proterozoic iron formations

    NASA Astrophysics Data System (ADS)

    Planavsky, Noah; Rouxel, Olivier J.; Bekker, Andrey; Hofmann, Axel; Little, Crispin T. S.; Lyons, Timothy W.

    2012-03-01

    Fe isotopes can provide new insight into redox-dependent biogeochemical processes. Precambrian iron formations (IF) are deserving targets for Fe isotope studies because they are composed predominantly of authigenic Fe phases and record a period of unprecedented iron deposition in Earth's history. We present Fe isotope data for bulk samples from 24 Archean and Proterozoic IF and eight Phanerozoic Fe oxide-rich deposits. These data reveal that many Archean and early Paleoproterozoic iron formations were a sink for isotopically heavy Fe, in contrast to later Proterozoic and Phanerozoic Fe oxide-rich rocks. The positive δ56Fe values in IF are best explained by delivery of particulate ferric oxides formed in the water column to the sediment-water interface. Because IF are a net sink for isotopically heavy Fe, there must be a corresponding pool of isotopically light Fe in the sedimentary record. Earlier work suggested that Archean pyritic black shales were an important part of this light sink before 2.35 billion years ago (Ga). It is therefore likely that the persistently and anomalously low δ56Fe values in shales are linked with the deposition of isotopically heavy Fe in IF in the deeper parts of basins. IF deposition produced a residual isotopically light dissolved Fe pool that was captured by pyritic Fe in shales. Local dissimilatory Fe reduction in porewater and associated diagenetic reactions resulting in pyrite and carbonate precipitation may have further enhanced Fe isotope heterogeneity in marine sediments, and an 'iron shuttle' may have transported isotopically light Fe from shelf sediments to the basin. Nevertheless, water-column processing of hydrothermally delivered Fe likely had the strongest influence on the bulk iron isotope composition of Archean and Paleoproterozoic iron formations and other marine sediments.

  11. Iron-oxidizing microbial ecosystems thrived in late Paleoproterozoic redox-stratified oceans

    NASA Astrophysics Data System (ADS)

    Planavsky, Noah; Rouxel, Olivier; Bekker, Andrey; Shapiro, Russell; Fralick, Phil; Knudsen, Andrew

    2009-08-01

    We conducted a geochemical and petrographic study of the 1.89 billion year old Gunflint and Biwabik iron formations, with the goal of determining the importance of microbial iron-oxidation in the formation of iron- and microfossil-rich stromatolites. We used redox-sensitive tracers, such as iron isotopes and rare earth elements, to decipher whether these ancient microbial ecosystems harbored cyanobacteria or Fe-oxidizing bacteria as primary producers. Iron-rich stromatolites contain non-significant or positive Ce anomalies, which contrast with shallow water deposits having negative Ce anomalies. This trend in Ce anomalies indicates that the stromatolites formed in low oxygen conditions, which is the ideal setting for the proliferation of Fe-oxidizing bacterial ecosystems. The stromatolites yield a large range of δ 56Fe values, from -0.66 to +0.82‰, but contain predominantly positive values indicating the prevalence of partial Fe-oxidation. Based on modern analogues, Fe-oxides precipitated in cyanobacterial mats are expected to record an isotopic signature of quantitative oxidation, which in marine settings will yield negative δ 56Fe values. The stromatolite iron isotope data, therefore, provide evidence for the presence of Fe-oxidizing bacteria. The stromatolites can be traced for a distance of over 100 km in these iron formations, indicating that they record a pervasive rather than localized ecosystem. Their preservation in late Paleoproterozoic successions deposited along the margins of the Superior craton suggests that there was a global expansion of iron-oxidizing bacterial communities at shallow-water redox boundaries in late Paleoproterozoic oceans.

  12. Ground and excited states Gamow-Teller strength distributions of iron isotopes and associated capture rates for core-collapse simulations

    NASA Astrophysics Data System (ADS)

    Nabi, Jameel-Un

    2011-02-01

    This paper reports on the microscopic calculation of ground and excited states Gamow-Teller (GT) strength distributions, both in the electron capture and electron decay direction, for 54,55,56Fe. The associated electron and positron capture rates for these isotopes of iron are also calculated in stellar matter. These calculations were recently introduced and this paper is a follow-up which discusses in detail the GT strength distributions and stellar capture rates of key iron isotopes. The calculations are performed within the framework of the proton-neutron quasiparticle random phase approximation (pn-QRPA) theory. The pn-QRPA theory allows a microscopic state-by-state calculation of GT strength functions and stellar capture rates which greatly increases the reliability of the results. For the first time experimental deformation of nuclei are taken into account. In the core of massive stars isotopes of iron, 54,55,56Fe, are considered to be key players in decreasing the electron-to-baryon ratio ( Y e ) mainly via electron capture on these nuclide. The structure of the presupernova star is altered both by the changes in Y e and the entropy of the core material. Results are encouraging and are compared against measurements (where possible) and other calculations. The calculated electron capture rates are in overall good agreement with the shell model results. During the presupernova evolution of massive stars, from oxygen shell burning stages till around end of convective core silicon burning, the calculated electron capture rates on 54Fe are around three times bigger than the corresponding shell model rates. The calculated positron capture rates, however, are suppressed by two to five orders of magnitude.

  13. The effects of metamorphism on O and Fe isotope compositions in the Biwabik Iron Formation, northern Minnesota

    NASA Astrophysics Data System (ADS)

    Hyslop, Elizabeth Valaas; Valley, John W.; Johnson, Clark M.; Beard, Brian L.

    2008-03-01

    The Biwabik Iron Formation of Minnesota (1.9 Ga) underwent contact metamorphism by intrusion of the Duluth Complex (1.1 Ga). Apparent quartz-magnetite oxygen isotope temperatures decrease from ˜700°C at the contact to ˜375°C at 2.6 km distance (normal to the contact in 3D). Metamorphic pigeonite at the contact, however, indicates that peak temperatures were greater than 825°C. The apparent O isotope temperatures, therefore, reflect cooling, and not peak metamorphic conditions. Magnetite was reset in δ18O as a function of grain size, indicating that isotopic exchange was controlled by diffusion of oxygen in magnetite for samples from above the grunerite isograd. Apparent quartz-magnetite O isotope temperatures are similar to calculated closure temperatures for oxygen diffusion in magnetite at a cooling rate of ˜5.6°C/kyr, which suggests that the Biwabik Iron Formation cooled from ˜825 to 400°C in ˜75 kyr at the contact with the Duluth Complex. Isotopic exchange during metamorphism also occurred for Fe, where magnetite-Fe silicate fractionations decrease with increasing metamorphic grade. Correlations between quartz-magnetite O isotope fractionations and magnetite-iron silicate Fe isotope fractionations suggest that both reflect cooling, where the closure temperature for Fe was higher than for O. The net effect of metamorphism on δ18O-δ56Fe variations in magnetite is a strong increase in δ18OMt and a mild decrease in δ56Fe with increasing metamorphic grade, relative to the isotopic compositions that are expected at the low temperatures of initial magnetite formation. If metamorphism of Iron Formations occurs in a closed system, bulk O and Fe isotope compositions may be preserved, although re-equilibration among the minerals may occur for both O and Fe isotopes.

  14. Genotype differences in anxiety and fear learning and memory of WT and ApoE4 mice associated with enhanced generation of hippocampal reactive oxygen species.

    PubMed

    Villasana, Laura E; Weber, Sydney; Akinyeke, Tunde; Raber, Jacob

    2016-09-01

    Apolipoprotein E (apoE), involved in cholesterol and lipid metabolism, also influences cognitive function and injury repair. In humans, apoE is expressed in three isoforms. E4 is a risk factor for age-related cognitive decline and Alzheimer's disease, particularly in women. E4 might also be a risk factor for developing behavioral and cognitive changes following (56) Fe irradiation, a component of the space environment astronauts are exposed to during missions. These changes might be related to enhanced generation of reactive oxygen species (ROS). In this study, we compared the behavioral and cognitive performance of sham-irradiated and irradiated wild-type (WT) mice and mice expressing the human E3 or E4 isoforms, and assessed the generation of ROS in hippocampal slices from these mice. E4 mice had greater anxiety-like and conditioned fear behaviors than WT mice, and these genotype differences were associated with greater levels of ROS in E4 than WT mice. The greater generation of ROS in the hippocampus of E4 than WT mice might contribute to their higher anxiety levels and enhanced fear conditioning. In E4, but not WT, mice, phorbol-12-myristate-13-acetate-treated hippocampal slices showed more dihydroxy ethidium oxidation in sham-irradiated than irradiated mice and hippocampal heme oxygenase-1 levels were higher in irradiated than sham-irradiated E4 mice. Mice with apolipoprotein E4 (E4), a risk factor for Alzheimer's disease, have greater anxiety-like and conditioned fear behaviors than wild-type (WT) mice. Generation of reactive oxygen species (ROS, in red) 3 months following (56) Fe irradiation, a component of the space environment astronauts are exposed to, is more pronounced in the hippocampus of E4 than WT mice. In E4, but not WT, mice, hippocampal levels of the oxidative stress-relevant marker heme oxygenase-1 are higher in irradiated than sham-irradiated E4 mice.

  15. Chromatographic speciation of Cr(III)-species, inter-species equilibrium isotope fractionation and improved chemical purification strategies for high-precision isotope analysis.

    PubMed

    Larsen, K K; Wielandt, D; Schiller, M; Bizzarro, M

    2016-04-22

    Chromatographic purification of chromium (Cr), which is required for high-precision isotope analysis, is complicated by the presence of multiple Cr-species with different effective charges in the acid digested sample aliquots. The differing ion exchange selectivity and sluggish reaction rates of these species can result in incomplete Cr recovery during chromatographic purification. Because of large mass-dependent inter-species isotope fractionation, incomplete recovery can affect the accuracy of high-precision Cr isotope analysis. Here, we demonstrate widely differing cation distribution coefficients of Cr(III)-species (Cr(3+), CrCl(2+) and CrCl2(+)) with equilibrium mass-dependent isotope fractionation spanning a range of ∼1‰/amu and consistent with theory. The heaviest isotopes partition into Cr(3+), intermediates in CrCl(2+) and the lightest in CrCl2(+)/CrCl3°. Thus, for a typical reported loss of ∼25% Cr (in the form of Cr(3+)) through chromatographic purification, this translates into 185 ppm/amu offset in the stable Cr isotope ratio of the residual sample. Depending on the validity of the mass-bias correction during isotope analysis, this further results in artificial mass-independent effects in the mass-bias corrected (53)Cr/(52)Cr (μ(53)Cr* of 5.2 ppm) and (54)Cr/(52)Cr (μ(54)Cr* of 13.5 ppm) components used to infer chronometric and nucleosynthetic information in meteorites. To mitigate these fractionation effects, we developed strategic chemical sample pre-treatment procedures that ensure high and reproducible Cr recovery. This is achieved either through 1) effective promotion of Cr(3+) by >5 days exposure to HNO3H2O2 solutions at room temperature, resulting in >∼98% Cr recovery for most types of sample matrices tested using a cationic chromatographic retention strategy, or 2) formation of Cr(III)-Cl complexes through exposure to concentrated HCl at high temperature (>120 °C) for several hours, resulting in >97.5% Cr recovery using a

  16. Chromatographic speciation of Cr(III)-species, inter-species equilibrium isotope fractionation and improved chemical purification strategies for high-precision isotope analysis

    PubMed Central

    Larsen, K.K.; Wielandt, D.; Schiller, M.; Bizzarro, M.

    2016-01-01

    Chromatographic purification of chromium (Cr), which is required for high-precision isotope analysis, is complicated by the presence of multiple Cr-species with different effective charges in the acid digested sample aliquots. The differing ion exchange selectivity and sluggish reaction rates of these species can result in incomplete Cr recovery during chromatographic purification. Because of large mass-dependent inter-species isotope fractionation, incomplete recovery can affect the accuracy of high-precision Cr isotope analysis. Here, we demonstrate widely differing cation distribution coefficients of Cr(III)-species (Cr3+, CrCl2+ and CrCl2+) with equilibrium mass-dependent isotope fractionation spanning a range of ~1‰/amu and consistent with theory. The heaviest isotopes partition into Cr3+, intermediates in CrCl2+ and the lightest in CrCl2+/CrCl3°. Thus, for a typical reported loss of ~25% Cr (in the form of Cr3+) through chromatographic purification, this translates into 185 ppm/amu offset in the stable Cr isotope ratio of the residual sample. Depending on the validity of the mass-bias correction during isotope analysis, this further results in artificial mass-independent effects in the mass-bias corrected 53Cr/52Cr (μ53 Cr* of 5.2 ppm) and 54Cr/52Cr (μ54Cr* of 13.5 ppm) components used to infer chronometric and nucleosynthetic information in meteorites. To mitigate these fractionation effects, we developed strategic chemical sample pre-treatment procedures that ensure high and reproducible Cr recovery. This is achieved either through 1) effective promotion of Cr3+ by >5 days exposure to HNO3 —H2O2 solutions at room temperature, resulting in >~98% Cr recovery for most types of sample matrices tested using a cationic chromatographic retention strategy, or 2) formation of Cr(III)-Cl complexes through exposure to concentrated HCl at high temperature (>120 °C) for several hours, resulting in >97.5% Cr recovery using a chromatographic elution strategy that

  17. Development of odd-Z-projectile reactions for transactinide element synthesis

    SciTech Connect

    Folden III, Charles Marvin

    2004-11-04

    The development of new odd-Z-projectile reactions leading to the production of transactinide elements is described. The cross section of the even-Z-projectile 208Pb(64Ni, n)271Ds reaction was measured at two new energies using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. In total, seven decay chains attributable to 271Ds were observed. These data, combined with previous results, establish an excitation function for the production of 271Ds. The maximum cross section was 20 +15 -11 pb at a center-of-target energy of 311.5 MeV in the laboratory frame.The data from the 271Ds experiments were used to estimate the optimum beam energy for the new odd-Z-projectile 208Pb(65Cu, n)272-111 reaction using the Fusion by Diffusion theory proposed by Swiatecki, Siwek-Wilczynska, and Wilczynski. A cross section for this reaction was measured for the first time, at a center-of-target energy of 321.1 MeV in the laboratory frame. The excitation energy f or compound nuclei formed at the target center was 13.2 MeV. One decay chain was observed, resulting in a measured cross section of 1.7 +3.9 -1.4 pb. This decay chain is in good agreement with previously published data on the decay of 272-111.The new odd-Z-projectile 208Pb(55Mn, n)262Bh reaction was studied at three different projectile energies, and 33 decay chains of 262Bh were observed. The existence of a previously reported alpha-decaying isomeric state in this nuclide was confirmed. Production of the ground state was preferred at all three beam energies. The maximum cross section was 540 +180 -150 pb at a projectile center-of-target energy of 264.0 MeV. This cross section is much larger than that previously reported for the even-Z-projectile 209Bi(54Cr, n)262Bh reaction, which may be because the 54Cr projectile energies in the latter reaction were too high for optimum production of the 1n product. At the highest projectile energy of 268.0 MeV in the target center, two decay

  18. Chemical separation and mass spectrometry of Cr, Fe, Ni, Zn, and Cu in terrestrial and extraterrestrial materials using thermal ionization mass spectrometry.

    PubMed

    Yamakawa, Akane; Yamashita, Katsuyuki; Makishima, Akio; Nakamura, Eizo

    2009-12-01

    A sequential chemical separation technique for Cr, Fe, Ni, Zn, and Cu in terrestrial and extraterrestrial silicate rocks was developed for precise and accurate determination of elemental concentration by the isotope dilution method (ID). The technique uses a combination of cation-anion exchange chromatography and Eichrom nickel specific resin. The method was tested using a variety of matrixes including bulk meteorite (Allende), terrestrial peridotite (JP-1), and basalt (JB-1b). Concentrations of each element was determined by thermal ionization mass spectrometry (TIMS) using W filaments and a Si-B-Al type activator for Cr, Fe, Ni, and Zn and a Re filament and silicic acid-H3PO4 activator for Cu. The method can be used to precisely determine the concentrations of these elements in very small silicate samples, including meteorites, geochemical reference samples, and mineral standards for microprobe analysis. Furthermore, the Cr mass spectrometry procedure developed in this study can be extended to determine the isotopic ratios of 53Cr/52Cr and 54Cr/52Cr with precision of approximately 0.05epsilon and approximately 0.10epsilon (1epsilon = 0.01%), respectively, enabling cosmochemical applications such as high precision Mn-Cr chronology and investigation of nucleosynthetic isotopic anomalies in meteorites. PMID:19886654

  19. Irradiation-induced microchemical changes in highly irradiated 316 stainless steel

    NASA Astrophysics Data System (ADS)

    Fujii, K.; Fukuya, K.

    2016-02-01

    Cold-worked 316 stainless steel specimens irradiated to 74 dpa in a pressurized water reactor (PWR) were analyzed by atom probe tomography (APT) to extend knowledge of solute clusters and segregation at higher doses. The analyses confirmed that those clusters mainly enriched in Ni-Si or Ni-Si-Mn were formed at high number density. The clusters were divided into three types based on their size and Mn content; small Ni-Si clusters (3-4 nm in diameter), and large Ni-Si and Ni-Si-Mn clusters (8-10 nm in diameter). The total cluster number density was 7.7 × 1023 m-3. The fraction of large clusters was almost 1/10 of the total density. The average composition (in at%) for small clusters was: Fe, 54; Cr, 12; Mn, 1; Ni, 22; Si, 11; Mo, 1, and for large clusters it was: Fe, 44; Cr, 9; Mn, 2; Ni, 29; Si, 14; Mo,1. It was likely that some of the Ni-Si clusters correspond to γ‧ phase precipitates while the Ni-Si-Mn clusters were precursors of G phase precipitates. The APT analyses at grain boundaries confirmed enrichment of Ni, Si, P and Cu and depletion of Fe, Cr, Mo and Mn. The segregation behavior was consistent with previous knowledge of radiation induced segregation.

  20. Quasifission and fusion-fission in reactions with massive nuclei: Comparison of reactions leading to the Z=120 element

    SciTech Connect

    Nasirov, A. K.; Giardina, G.; Mandaglio, G.; Manganaro, M.; Hanappe, F.; Heinz, S.; Hofmann, S.; Muminov, A. I.; Scheid, W.

    2009-02-15

    The yields of evaporation residues, fusion-fission, and quasifission fragments in the {sup 48}Ca+{sup 144,154}Sm and {sup 16}O+{sup 186}W reactions are analyzed in the framework of the combined theoretical method based on the dinuclear system concept and advanced statistical model. The measured yields of evaporation residues for the {sup 48}Ca+{sup 154}Sm reaction can be well reproduced. The measured yields of fission fragments are decomposed into contributions coming from fusion-fission, quasifission, and fast-fission. The decrease in the measured yield of quasifission fragments in {sup 48}Ca+{sup 154}Sm at the large collision energies and the lack of quasifission fragments in the {sup 48}Ca+{sup 144}Sm reaction are explained by the overlap in mass angle distributions of the quasifission and fusion-fission fragments. The investigation of the optimal conditions for the synthesis of the new element Z=120 (A=302) show that the {sup 54}Cr+{sup 248}Cm reaction is preferable in comparison with the {sup 58}Fe+{sup 244}Pu and {sup 64}Ni+{sup 238}U reactions because the excitation function of the evaporation residues of the former reaction is some orders of magnitude larger than that for the last two reactions.

  1. Excitation function for the production of {sup 262}Bh (Z=107) in the odd-Z-projectile reaction {sup 208}Pb({sup 55}Mn, n)

    SciTech Connect

    Folden, C.M. III; Nelson, S.L.; Duellmann, Ch.E.; Schwantes, J.M.; Zielinski, P.M.; Nitsche, H.; Hoffman, D.C.; Sudowe, R.; Gregorich, K.E.

    2006-01-15

    The excitation function for production of {sup 262}Bh in the odd-Z-projectile reaction {sup 208}Pb({sup 55}Mn, n) has been measured at three projectile energies using the Berkeley Gas-filled Separator at the Lawrence Berkeley Nation