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Sample records for archean banded iron

  1. Geochemistry of some banded iron-formations of the archean supracrustals, Jharkhand–Orissa region, India

    Indian Academy of Sciences (India)

    H N Bhattacharya; Indranil Chakraborty; Kaushik K Ghosh

    2007-06-01

    Banded iron-formations (BIF) form an important part of the Archean supracrustal belts of the Jharkhand–Orissa region, India. Major, trace and REE chemistry of the banded iron-formation of the Gandhamardan, Deo Nala, Gorumahisani and Noamundi sections of the Jharkhand–Orissa region are utilized to explore the source of metals and to address the thermal regime of the basin floor and the redox conditions of the archean sea. Hydrothermal fluids of variable temperatures might have contributed the major part of the Fe and other trace elements to the studied banded iron-formations. Diagenetic fluids from the sea floor sediments and river water might have played a subdued role in supplying the Fe and other elements for the banded iron-formations.

  2. Geologic evolution of iron quadrangle on archean and early proterozoic

    International Nuclear Information System (INIS)

    The preliminary results of U-Pb geochronology of iron quadrangle. Brazil are presented, using the Davis linear regression program for determining of intersection concordance-discord and for estimation the associate mistakes. (C.G.C.)

  3. Development of Sintered Iron Driving Bands

    Directory of Open Access Journals (Sweden)

    R. P. Khanna

    1974-07-01

    Full Text Available The present investigation reports some detailed studies carried out on the development testing and proving of sintered Iron Driving Bands. Sintering studies on two different types of iron powders together with a few Fe-Cu compositions have been made and based on the results there of, parameters for development iron driving bands have been standardised. The results obtained clearly demonstrate that substitution of copper by sintered iron is highly practicable alternative.

  4. An iron shuttle for deepwater silica in Late Archean and early Paleoproterozoic iron formation

    OpenAIRE

    Fischer, Woodward W.; Andrew H. Knoll

    2009-01-01

    Iron formations are typically thinly bedded or laminated sedimentary rocks containing 15% or more of iron and a large proportion of silica (commonly > 40%). In the ca. 2590-2460 Ma Campbellrand-Kuruman Complex, Transvaal Supergroup, South Africa, iron formation occurs as a sediment-starved deepwater facies distal to carbonates and shales. Iron minerals, primarily siderite, define the lamination. The silica primarily occurs as thin beds and nodules of diagenetic chert (now microcrystalline qua...

  5. Reconciling atmospheric temperatures in the early Archean

    DEFF Research Database (Denmark)

    Pope, Emily Catherine; Bird, Dennis K.; Rosing, Minik Thorleif;

    Average surface temperatures of Earth in the Archean remain unresolved despite decades of diverse approaches to the problem. As in the present, early Earth climates were complex systems dependent on many variables. With few constraints on such variables, climate models must be relatively simplistic...... Archean rock record. The goal of this study is to compile and reconcile Archean geologic and geochemical features that are in some way controlled by surface temperature and/or atmospheric composition, so that at the very least paleoclimate models can be checked by physical limits. Data used to this end...... include the oxygen isotope record of chemical sediments and ancient ocean crust, chemical equilibria amongst primary phases in banded iron formations (BIFs), sedimentary features indicative of temperate or glacial environments, and paleosol indicators of atmospheric CO2. Further, we explore the extent to...

  6. Iron isotopes in ancient and modern komatiites: Evidence in support of an oxidised mantle from Archean to present

    Science.gov (United States)

    Hibbert, K. E. J.; Williams, H. M.; Kerr, A. C.; Puchtel, I. S.

    2012-03-01

    The mantle of the modern Earth is relatively oxidised compared to the initially reducing conditions inferred for core formation. The timing of the oxidation of the mantle is not conclusively resolved but has important implications for the timing of the development of the hydrosphere and atmosphere. In order to examine the timing of this oxidation event, we present iron isotope data from three exceptionally well preserved komatiite localities, Belingwe (2.7 Ga), Vetreny (2.4 Ga) and Gorgona (0.089 Ga). Measurements of Fe isotope compositions of whole-rock samples are complemented by the analysis of olivine, spinel and pyroxene separates. Bulk-rock and olivine Fe isotope compositions (δ57Fe) define clear linear correlations with indicators of magmatic differentiation (Mg#, Cr#). The mean Fe isotope compositions of the 2.7-2.4 Ga and 0.089 Ga samples are statistically distinct and this difference can be explained by greater extent of partial melting represented by the older samples and higher mantle ambient temperatures in the Archean and early Proterozoic relative to the present day. Significantly, samples of all ages define continuous positive linear correlations between bulk rock δ57Fe and V/Sc and δ57Fe and V, and between V/Sc and V with TiO2, providing evidence for the incompatible behaviour of V (relative to Sc) and of isotopically heavy Fe. Partial melting models calculated using partition coefficients for V at oxygen fugacities (fO2s) of 0 and + 1 relative to the fayalite-magnetite-quartz buffer (FMQ) best match the data arrays, which are defined by all samples, from late Archean to Tertiary. These data, therefore, provide evidence for komatiite generation under moderately oxidising conditions since the late Archean, and argue against a change in mantle fO2 concomitant with atmospheric oxygenation at ~ 2.4 Ga.

  7. Chemostratigraphy of Neoproterozoic Banded Iron Formation (BIF)

    DEFF Research Database (Denmark)

    Gaucher, Claudio; Sial, Alcides N.; Frei, Robert

    2015-01-01

    Neoproterozoic banded iron formations (BIFs) are not restricted to the middle Cryogenian, c. 715 Ma glaciation, occurring in Tonian, Cryogenian, and Ediacaran successions. Many Neoproterozoic BIFs were deposited in glacially influenced settings, such as the Rapitan Group (Canada), Jacadigo Group (W...... study of BIFs include rare earth element distribution, especially Eu and Ce normalized concentrations, iron speciation, and Nd and Cr isotopes (δ53Cr). Whereas Rapitan type BIFs exhibit no Eu or Ce anomalies, the Algoma-type Neoproterozoic BIFs show both. Positive δ53Cr values characterize glacially...

  8. Geology and geochemistry of the Macheng Algoma-type banded iron-formation, North China Craton: Constraints on mineralization events and genesis of high-grade iron ores

    Science.gov (United States)

    Wu, Huaying; Niu, Xianglong; Zhang, Lianchang; Pirajno, Franco; Luo, Huabao; Qin, Feng; Cui, Minli; Wang, Changle; Qi, Min

    2015-12-01

    The Macheng iron deposit is located in the eastern Hebei province of the North China Craton (NCC). It is hosted in Neoarchean metamorphic rocks of Baimiaozi formation in the Dantazi Group, consisting of biotite-leptynite, plagioclase-gneiss, plagioclase-amphibolite, migmatite, migmatitic granite and quartz schist. Geochemical analyses of the host biotite leptynite and plagioclase amphibolites show that their protoliths are both volcanics, inferred to be trachytic basalt and basaltic andesite, respectively. Based on the geochemical signature of the host rocks, together with geology of the iron deposit, it is inferred that the Macheng BIF is an Algoma-type iron exhalative formation, formed in an arc-related basin in the Neoarchean. Post-Archean Australian Shale (PAAS)-normalized rare earth elements (REEs) plus yttrium (Y) concentrations of different BIF ores with gneissic, striated and banded structure in the Macheng deposit, show similar patterns with depletions in light rare earth elements (LREEs) and middle rare earth elements (MREEs) relative to heavy rare earth elements (HREEs) and with apparently positive La, Y and Eu anomalies. Y/Ho ratios of the gneissic, striated and banded BIF ores vary from 37 to 56. These geochemical features of the BIF ores reveal their affinity with the sea water and the presence of a high-temperature hydrothermal component, indicating that both the seawater and high temperature hydrothermal fluids derived from alteration of oceanic basalts and komatiites may contribute to formation of the Macheng BIF. Geological, mineralogical and geochemical studies of the Macheng deposit recognized two kinds of high-grade iron ores. One is massive oxidized high-grade ore (Fe2O3T = 74.37-86.20 wt.%), mainly consisting of hematite with some magnetite, which shows geochemical characteristics of the gneissic, striated and banded BIF ores. The other type is magnetite high-grade ore, also massive and consisting of magnetite, with distinct characteristics

  9. Trace-element and multi-isotope geochemistry of Late-Archean black shales in the Carajas iron-ore district, Brazil

    DEFF Research Database (Denmark)

    Cabral, A. R.; Creaser, R. A.; Naegler, T.; Lehmann, B.; Voegelin, A. R.; Belyatsky, B.; Pasava, J.; Seabra Gomes, Jr., A. A.; Galbiatti, H.; Boettcher, M. E.; Escher, P.

    The 250-300-m-thick Carajas Formation in the Carajas mineral province, northern Brazil, consists of banded iron formation (including giant high-grade iron-ore deposits) and minor black shale, overlying a thick pile (2-3 km) of about 2.75-Ga-old metabasalt. Carbonaceous shale with pyrite-and locally......, with heavy data restricted to pyrrhotite-free samples. The data suggest microbial sulfate reduction under, at least partially, sulfate-limiting conditions with later overprint by migrating solutions. The black shale is affected by pronounced low-temperature potassium metasomatism (K2O/Na2O > 100; up to...

  10. Raman Spectroscopic Characterisation of Australian Banded Iron Formation and Iron Ore

    Science.gov (United States)

    Wells, M. A.; Ramanaidou, E. R.

    2012-04-01

    In Australia and world-wide over the past 5-10 years, declining reserves of premium, high-grade (>64% Fe), low-P bearing iron ore, have seen iron ore producers increase their utilisation of lower Fe-grade, higher P/Al/Si ore. In Australia, the channel iron deposits (CID), bedded iron deposits (BID) and, more recently, BIF-derived magnetite iron deposits (MID) have seen increased usage driven mainly by the increased demand from Chinese steel mills (Ramanaidou and Wells, 2011). Efficient exploitation and processing of these lower-grade iron ores requires a detailed understanding of their iron oxide and gangue mineralogy and geochemistry. The common Fe-bearing minerals (e.g., hematite, magnetite, goethite and kenomagnetite) in these deposits, as well as gangue minerals such as quartz and carbonates, are all strongly Raman active (e.g., de Faria et al., 1997). Their distinct Raman spectra enable them to be easily detected and mapped in situ in either unprepared material or samples prepared as polished blocks. In this paper, using representative examples of Australian CID ore, martite-goethite bedded iron deposit (BID) ore and banded iron formation (BIF) examined as polished blocks, we present a range of Raman spectra of the key iron ore minerals, and discuss how Raman spectroscopy can be applied to characterising iron ore mineralogy. Raman imaging micrographs, obtained using a StreamLine Plus Raman imaging system, clearly identified the main Fe-oxide and gangue components in the CID, BID and BIF samples when compared to optical micrographs. Raman analysis enabled the unequivocal identification of diamond in the CID ore as a contaminant from the polishing paste used to prepare the sample, and confirmed the presence of hematite in the BID ore in the form of martite, which can be morphologically similar to magnetite and, thus, difficult to otherwise distinguish. Image analysis of Raman mineral maps could be used to quantify mineral abundance based on the number of 'pixels

  11. Neodymium isotopes in Archean seawater and implications for the marine Nd cycle in Earth's early oceans

    Science.gov (United States)

    Alexander, Brian W.; Bau, Michael; Andersson, Per

    2009-06-01

    Published neodymium (Nd) isotopic data for Archean iron-formations (IF) suggest that, overall, seawater throughout the Archean typically displayed 143Nd/ 144Nd close to bulk Earth values, with ЄNd( t) between - 1.5 and + 2.5. Neodymium isotopic ratios in seawater during deposition of the ~ 3.8 Isua (Greenland) IF likely displayed positive ЄNd(3.8 Ga) of + 2.5, as suggested by IF-G, an Isua reference IF that is considered the best archive for Early Archean seawater. Seawater 143Nd/ 144Nd ratios dominated by radiogenic Nd (positive ЄNd( t)) seem to have persisted for much of the Archean, as IF from the Pietersburg greenstone belt, South Africa, suggest seawater ЄNd(2.95 Ga) ≥ + 1. However, similarly aged (~ 2.9 Ga) IFs from South Africa indicate that significant variations in seawater 143Nd/ 144Nd occurred, and clearly show influences from isotopically distinct crustal sources. These variations are apparently related to depositional environment, with cratonic margin, shallow-water IFs possessing a continental ЄNd( t) of - 3, while IFs associated with sub-aqueous mafic volcanics display more radiogenic, positive ЄNd( t) values. Such variation in seawater 143Nd/ 144Nd is not possible in an isotopically well-mixed ocean, and similar to today, it appears that marine Nd cycling in the Archean produced water masses with distinct Nd isotopic ratios. Since the presence of banded iron-formations requires a reducing Archean ocean capable of transporting Fe, metal-oxide precipitation and scavenging processes near deep sea hydrothermal vent systems would not have scavenged mantle Nd, i.e., Nd sourced from alteration of oceanic crust. We propose that bulk anoxic seawater prior to 2.7 Ga possessed relatively constant positive ЄNd( t) of + 1 to + 2, whereas local shallow-water masses associated with exposed evolved crust could possess distinctly different, lower ЄNd( t).

  12. Mineralogy and geochemistry of banded iron formation and iron ores from eastern India with implications on their genesis

    Indian Academy of Sciences (India)

    Subrata Roy; A S Venkatesh

    2009-12-01

    The geological complexities of banded iron formation (BIF) and associated iron ores of Jilling–Langalata iron ore deposits, Singhbhum–North Orissa Craton, belonging to Iron Ore Group (IOG) eastern India have been studied in detail along with the geochemical evaluation of different iron ores. The geochemical and mineralogical characterization suggests that the massive, hard laminated, soft laminated ore and blue dust had a genetic lineage from BIFs aided with certain input from hydrothermal activity. The PAAS normalized REE pattern of Jilling BIF striking positive Eu anomaly, resembling those of modern hydrothermal solutions from mid-oceanic ridge (MOR). Major part of the iron could have been added to the bottom sea water by hydrothermal solutions derived from hydrothermally active anoxic marine environments. The ubiquitous presence of intercalated tuffaceous shales indicates the volcanic signature in BIF. Mineralogical studies reveal that magnetite was the principal iron oxide mineral, whose depositional history is preserved in BHJ, where it remains in the form of martite and the platy hematite is mainly the product of martite. The different types of iron ores are intricately related with the BHJ. Removal of silica from BIF and successive precipitation of iron by hydrothermal fluids of possible meteoric origin resulted in the formation of martite-goethite ore. The hard laminated ore has been formed in the second phase of supergene processes, where the deep burial upgrades the hydrous iron oxides to hematite. The massive ore is syngenetic in origin with BHJ. Soft laminated ores and biscuity ores were formed where further precipitation of iron was partial or absent.

  13. Oxidative Weathering and Euxinia in the Late Archean (Invited)

    Science.gov (United States)

    Reinhard, C.; Raiswell, R.; Scott, C.; Anbar, A. D.; Lyons, T. W.

    2009-12-01

    A large body of evidence points to a sharp rise in the concentration of atmospheric oxygen during the Paleoproterozoic between 2.45 and 2.32 billion years ago (Ga), but the history of deep ocean oxygenation is less well known. The deposition of banded iron formation (BIF) during the Archean and early Proterozoic (~3.8 - 1.8 Ga) has been taken to imply that deep ocean water masses were anoxic and rich in dissolved ferrous iron (Fe2+) derived from high temperature weathering of seafloor basalt under low oceanic sulfate (SO42-) concentrations. Reducing and iron-rich (ferruginous) deep ocean conditions are thought to have persisted for most of Earth’s early history, although a notable lack of BIF between 2.4 - 2.0 Ga has rendered deep ocean chemistry during this period obscure. In any case, the cessation of BIF deposition at ~1.8 Ga is generally linked to the oxygenation of the atmosphere through the eventual removal of Fe2+ from the ocean either as ferric (hydr)oxides or as pyrite in euxinic (anoxic and sulfidic) basins. A corollary of the latter model is that oxidative delivery of sulfate to the ocean was not sufficient to remove reactive iron, via microbial sulfide production, before ~1.8 Ga. However, recent studies of the late Archean Mt. McRae Formation suggest that oxidative sulfur cycling may have preceded the Paleoproterozoic rise in atmospheric oxygen and that conditions sufficient to authigenically enrich molybdenum (Mo) in marine sediments existed at ~2.5 Ga. On the modern Earth, significant enrichment of Mo into sediments occurs following the conversion of soluble molybdate (MoO42-) to particle-reactive thiomolybdates (MoO4-xSx2-) in stable sulfidic environments, indicating that the Mo enrichments seen in the Mt. McRae shale may have resulted from the accumulation of free sulfide in the water column. Here, we present iron speciation data for the late Archean Mt. McRae Shale that provide evidence for a euxinic water column at ~2.5 Ga. Sulfur isotope data

  14. Microbes: mini iron factories.

    Science.gov (United States)

    Joshi, Kumar Batuk

    2014-12-01

    Microbes have flourished in extreme habitats since beginning of the Earth and have played an important role in geological processes like weathering, mineralization, diagenesis, mineral formation and destruction. Biotic mineralization is one of the most fascinating examples of how microbes have been influencing geological processes. Iron oxidizing and reducing bacteria are capable of precipitating wide varieties of iron oxides (magnetite), carbonates (siderite) and sulphides (greigite) via controlled or induced mineralization processes. Microbes have also been considered to play an important role in the history of evolution of sedimentary rocks on Earth from the formation of banded iron formations during the Archean to modern biotic bog iron and ochre deposits. Here, we discuss the role that microbes have been playing in precipitation of iron and the role and importance of interdisciplinary studies in the field of geology and biology in solving some of the major geological mysteries. PMID:25320452

  15. The Archean Dongwanzi ophiolite complex, North China craton: 2.505-billion-year-old oceanic crust and mantle.

    Science.gov (United States)

    Kusky, T M; Li, J H; Tucker, R D

    2001-05-11

    We report a thick, laterally extensive 2505 +/- 2.2-million-year-old (uranium-lead ratio in zircon) Archean ophiolite complex in the North China craton. Basal harzburgite tectonite is overlain by cumulate ultramafic rocks, a mafic-ultramafic transition zone of interlayered gabbro and ultramafic cumulates, compositionally layered olivine-gabbro and pyroxenite, and isotropic gabbro. A sheeted dike complex is rooted in the gabbro and overlain by a mixed dike-pillow lava section, chert, and banded iron formation. The documentation of a complete Archean ophiolite implies that mechanisms of oceanic crustal accretion similar to those of today were in operation by 2.5 billion years ago at divergent plate margins and that the temperature of the early mantle was not extremely elevated, as compared to the present-day temperature. Plate tectonic processes similar to those of the present must also have emplaced the ophiolite in a convergent margin setting. PMID:11349144

  16. Petrological and geochemical features of the Jingtieshan banded iron formation (BIF): A unique type of BIF from the Northern Qilian Orogenic Belt, NW China

    Science.gov (United States)

    Yang, Xiu-Qing; Zhang, Zuo-Heng; Duan, Shi-Gang; Zhao, Xin-Min

    2015-12-01

    The Jingtieshan banded iron formation (BIF) is located in the Northern Qilian Orogenic Belt (NQOB) in NW China. The BIFs are hosted in Mesoproterozoic Jingtieshan Group, a dominantly clastic-carbonate sedimentary formation, and was metamorphosed to lower greenschist facies. The Jingtieshan BIFs include oxide-, carbonate- and mixed carbonate-oxide facies, and consist of alternating iron-rich and silica-rich bands. The BIFs are composed essentially of specularite and jasper, with minor carbonate minerals and barite. The SiO2 + Fe2O3 content is markedly high in the oxide facies BIF, followed by FeO, CO2 and Ba, with the other elements usually lower than 1%, suggesting that the original chemical sediments were composed of Fe, Si, CO32- and Ba. The positive correlation between Al2O3, TiO2 and Zr in the BIFs indicates that these chemical sediments incorporate minor detrital components. Oxide facies BIF shows low HFSE, low ∑REE and low Y/Ho. The Post Archean Australian Shale-normalized REE patterns for Jingtieshan BIFs are characterized slight LREE depletion, strong positive Eu anomalies and lack of significant negative Ce anomalies. Siderite in the carbonate- and mixed carbonate-oxide facies BIF shows negative δ13C values varying from -8.4‰ to -3.0‰, and δ18O values show a range of -16.6‰ to -11.7‰. The geochemical signatures and carbon-oxygen isotopes suggest origin from high-temperature hydrothermal fluids with weak seawater signature for the sediments of Jingtieshan BIFs. The absence of negative Ce anomalies and the high Fe3+/∑Fe ratios of the oxide facies BIF do not support ocean anoxia. In contrast to the three main types (Algoma-, Superior- and Rapitan-type) of global BIFs, the Jingtieshan BIFs represent a unique type with features similar to those of sedimentary-exhalative mineralization.

  17. Melting in the FeOsbnd SiO2 system to deep lower-mantle pressures: Implications for subducted Banded Iron Formations

    Science.gov (United States)

    Kato, Chie; Hirose, Kei; Nomura, Ryuichi; Ballmer, Maxim D.; Miyake, Akira; Ohishi, Yasuo

    2016-04-01

    Banded iron formations (BIFs), consisting of layers of iron oxide and silica, are far denser than normal mantle material and should have been subducted and sunk into the deep lower mantle. We performed melting experiments on Fe2SiO4 from 26 to 131 GPa in a laser-heated diamond-anvil cell (DAC). The textural and chemical characterization of a sample recovered from the DAC revealed that SiO2 is the liquidus phase for the whole pressure range examined in this study. The chemical compositions of partial melts are very rich in FeO, indicating that the eutectic melt compositions in the FeOsbnd SiO2 binary system are very close to the FeO end-member. The eutectic temperature is estimated to be 3540 ± 150 K at the core-mantle boundary (CMB), which is likely to be lower than the temperature at the top of the core at least in the Archean and Paleoproterozoic eons, suggesting that subducted BIFs underwent partial melting in a thermal boundary layer above the CMB. The FeO-rich melts formed by partial melting of the BIFs were exceedingly dense and therefore migrated downward. We infer that such partial melts have caused iron enrichment in the bottom part of the mantle, which may have contributed to the formation of ultralow velocity zones (ULVZs) observed today. On the other hand, solid residues left after the segregation of the FeO-rich partial melts have been almost pure SiO2, and therefore buoyant in the deep lower mantle to be entrained in mantle upwellings. They have likely been stretched and folded repeatedly by mantle flow, forming SiO2 streaks within the mantle "marble cake". Mantle packages enhanced by SiO2 streaks may be the origin of seismic scatterers in the mid-lower mantle.

  18. Examining Archean methanotrophy

    Science.gov (United States)

    Slotznick, Sarah P.; Fischer, Woodward W.

    2016-05-01

    The carbon isotope ratios preserved in sedimentary rocks can be used to fingerprint ancient metabolisms. Organic carbon in Late Archean samples stands out from that of other intervals with unusually low δ13C values (∼-45 to -60‰). It was hypothesized that these light compositions record ecosystem-wide methane cycling and methanotrophy, either of the aerobic or anaerobic variety. To test this idea, we studied the petrography and carbon and oxygen isotope systematics of well-known and spectacular occurrences of shallow water stromatolites from the 2.72 Ga Tumbiana Formation of Western Australia. We examined the carbonate cements and kerogen produced within the stromatolites, because methanotrophy is expected to leave an isotopic fingerprint in these carbon reservoirs. Mathematical modeling of Archean carbonate chemistry further reveals that methanotrophy should still have a discernible signature preserved in the isotopic record, somewhat diminished from those observed in Phanerozoic sedimentary basins due to higher dissolved inorganic carbon concentrations. These stromatolites contain kerogen with δ13Corg values of ∼ - 50 ‰. By microsampling different regions and textures within the stromatolites, we determined that the isotopic compositions of the authigenic calcite cements show a low degree of variation and are nearly identical to values estimated for seawater at this time; the lack of low and variable δ13Ccarb values implies that methanotrophy does not explain the low δ13Corg seen in the coeval kerogen. These observations do not support a methanotrophy hypothesis, but instead hint that the Late Archean may constitute an interval wherein autotrophs employed markedly different biochemical processes of energy conservation and carbon fixation.

  19. Application of factor analysis to XPS valence band of superparamagnetic iron oxide nanoparticles

    International Nuclear Information System (INIS)

    X-Ray photoelectron spectra of nano-sized superparamagnetic iron oxide nanoparticles were examined with the aim to discriminate the different degree of iron oxidation. Careful analysis of the valence band regions reveals the presence of both Fe3O4 and Fe2O3. The application of factor analysis enabled us to extract the relative molar concentrations of these oxides in the nanoparticles. This is of particular interest in improving the magnetic properties of iron oxide nanoparticles whose superparamagnetic character can be optimized to obtain better contrast in images from nuclear magnetic resonance. As a result, the factor analysis allows tuning the nanoparticle synthesis conditions in order to obtain the optimal magnetic properties for imaging. Results obtained by the XPS valence band analysis were compared to the transmission electron microscopy, X-ray diffraction and Raman measurements.

  20. Iterative LCAO treatment with overlap and band occupation in the iron-group metals

    OpenAIRE

    Del Re, G.; Kolár, M.; Cyrot-Lackmann, F.

    1985-01-01

    A study of the LCAO scheme for the iron-group s- and d-bands is carried out with special emphasis on : (a) the choice of the AO basis and its adjustment to reproduce approaches like the renormalized-atom ansatz; (b) the dependence of the final results on overlap and the number of neighbours taken into account (s-band calculations require at least neighbours from up to the 12th shell, whereas for d-band 2nd neighbours are required at worst); (c) principle of Fermi-level equalization as a techn...

  1. The Case for a Hot Archean Climate and its Implications to the History of the Biosphere

    CERN Document Server

    Schwartzman, David W

    2015-01-01

    The case for a much warmer climate on the early Earth than now is presented. The oxygen isotope record in sedimentary chert and the compelling case for a near constant isotopic oxygen composition of seawater over geologic time support thermophilic surface temperatures prevailing in the Archean, with some support for hot conditions lasting until about 1.5 billion years ago, aside from lower temperatures including glacial episodes at 2.1-2.4 Ga and possibly an earlier one at 2.9 Ga. Other evidence includes the following: 1) Melting temperatures of proteins resurrected from sequences inferred from robust molecular phylogenies give paleotemperatures at emergence consistent with a very warm early climate. 2) High atmospheric pCO2 levels in the Archean are consistent with high climatic temperatures near the triple point of primary iron minerals in banded iron formations, the formation of Mn-bicarbonate clusters leading to oxygenic photosynthesis and generally higher weathering intensities on land. These higher weat...

  2. Magnetite: What it reveals about the origin of the banded iron formations. [Abstract only

    Science.gov (United States)

    Schwartz, D. E.; Mancinelli, R. L.; White, M. R.

    1994-01-01

    Magnetite, Fe3O4 is produced abiotically and biotically. Abiotically, magnetite is a late magmatic mineral and forms as a consequence of the cooling of iron rich magma. Biotically, magnetite is produced by several organisms, including magnetotactic bacteria. Hematite, Fe2O3, is also produced abiotically and biotically. Abiotically, hematite rarely occurs as a primary mineral in igneous rocks, but is common as an alteration product, fumarole deposit, and in some metamorphosed Fe-rich rocks. Biotically, hematite is produced by several types of microorganisms. Biologically-produced magnetite and hematite are formed under the control of the host organism, and consequently, have characteristics not found in abiotically produced magnetite and hematite crystals. To determine if the magnetite and hematite in the Banded Iron Formation was biologically or abiotically produced, the characteristics of biologically-produced magnetite and hematite (concentrated from Aquaspirillum magnetotacticum) and abiotically-produced magnetite and hematite obtained from Wards Scientific Supply Company, were compared with characteristics of magnetite and hematite concentrated from the Gunflint Banded Iron Formation (Ontario, Canada) using thermal and crystallographic analytical techniques. Whole rock analysis of the Gunflint Banded Iron Formation by x-ray diffraction (XRD) and differential thermal analysis (DTA) revealed the presence of quartz, hematite, siderite and dolomite as the major minerals, and magnetite, greenalite, pyrite, pyrrhotite and apatite as the minor minerals. Analysis of a crude magnetic fraction of the Gunflint showed the minerals quartz, hematite, siderite, dolomite, and magnetite. Analysis of the crude magnetic fraction from Aquaspirillum magnetotacticum revealed organic compounds plus hematite and magnetite. The mineral identification and particle size distribution data obtained from the DTA along with XRD data indicate that the magnetite and hematite from the Gunflint

  3. Iron-absorption band analysis for the discrimination of iron-rich zones. [infrared spectral reflectance of Nevada iron deposits

    Science.gov (United States)

    Rowan, L. C. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. Most major rock units and unaltered and altered areas in the study area can be discriminated on the basis of visible and near-infrared spectral reflectivity differences recorded from satellite altitude. These subtle spectral differences are detectable by digital ratioing of the MSS bands and subsequent stretching to increase the contrast to enhance spectral differences. Hydrothermally altered areas appear as anomalous color patches within the volcanic-rock areas. A map has been prepared which can be regarded as an excellent reconnaissance exploration map, for use in targeting areas for more detailed geological, geochemical, and geophysical studies. Mafic and felsic rock types are easily discriminated on the color stretched-ratio composite. The ratioing process minimizes albedo effects, leaving only the recorded characteristic spectral response. The spectra of unaltered rocks appear different from those of altered rocks, which are typically dominated by limonite and clay minerals. It seems clear that differences in spectral shape can provide a basis for discrimination of geologic material, although the relations between visible and near-infrared spectral reflectivity and mineralogical composition are not yet entirely understood.

  4. Unveiling the broad band X-ray continuum and iron line complex in Mkr 841

    CERN Document Server

    Petrucci, P O; Matt, G; Longinotti, A L; Malzac, J; Mouchet, M; Boisson, C; Maraschi, L; Nandra, K; Ferrando, P

    2007-01-01

    Mkr 841 is a bright Seyfert 1 galaxy known to harbor a strong soft excess and a variable K$\\alpha$ iron line. It has been observed during 3 different periods by XMM for a total cumulated exposure time of $\\sim$108 ks. We present in this paper a broad band spectral analysis of the complete EPIC-pn data sets. We were able to test two different models for the soft excess, a relativistically blurred photoionized reflection (\\r model) and a relativistically smeared ionized absorption (\\a model). The continuum is modeled by a simple cut-off power law and we also add a neutral reflection. These observations reveal the extreme and puzzling spectral and temporal behaviors of the soft excess and iron line. The 0.5-3 keV soft X-ray flux decreases by a factor 3 between 2001 and 2005 and the line shape appears to be a mixture of broad and narrow components. We succeed in describing this complex broad-band 0.5-10 keV spectral variability using either \\r or \\a to fit the soft excess. Both models give statistically equivalen...

  5. Increasing the band gap of iron pyrite by alloying with oxygen

    Science.gov (United States)

    Law, Matthew; Hu, Jun; Zhang, Yanning; Wu, Ruqian

    2013-03-01

    Systematic density functional theory studies and model analyses have been used to show that the band gap of iron pyrite (FeS2) can be increased from ~ 1.0 to 1.2 -1.3 eV by replacing ~ 10% of the sulfur atoms with oxygen atoms (i.e., ~ 10% OS impurities). OS formation is exothermic, and the oxygen atoms tend to avoid O-O dimerization, which favors the structural stability of homogeneous FeS2-xOx alloys and frustrates phase separation into FeS2 and iron oxides. With an ideal band gap, absence of OSinduced gap states, high optical absorptivity, and low electron effective mass, FeS2-xOx alloys are promising for the development of pyrite-based heterojunction solar cells that feature large photovoltages and high device efficiencies. Acknowledgement: We thank the NSF SOLAR Program (Award CHE-1035218) and the UCI School of Physical Sciences Center for Solar Energy for support of this work. Calculations were performed on parallel computers at NERSC and at NSF supercomputer centers.

  6. Origin of iron oxide spherules in the banded iron formation of the Bababudan Group, Dharwar Craton, Southern India

    Science.gov (United States)

    Orberger, Beate; Wagner, Christiane; Wirth, Richard; Quirico, Eric; Gallien, Jean Paul; Derré, Colette; Montagnac, Gilles; Noret, Aurélie; Jayananda, Mudlappa; Massault, Marc; Rouchon, Virgile

    2012-06-01

    The banded iron formation of the Bababudan Group (Western Dharwar Craton, India) is composed of millimetric to centimetric alternating quartz and grey to red Fe-oxide bands. Major phases are quartz and martite (hematized magnetite) with minor Fe-sulfides and Ca-Mg-Fe-carbonates. Micrometric Fe-oxide spherules fill cavities in discontinuous micrometric layers of Fe-oxides that occur in the massive quartz layers and at the interface of massive Fe-oxide and quartz layers. The spherules are composed of micrometric radial plates of hematite intergrown with nanometric magnetite. These spherules contain carbonaceous matter (CM) with nanometric Fe-particles and have low N contents (˜900 ppm; CM1). The spherule formation is attributed to a low temperature hydrothermal process (150-200 °C) at around 2.52 Ga, possibly favored by the presence of CM. These hydrothermal fluids dissolved diagenetic interstitial sulfides or carbonates creating cavities which, provided space for the spherule precipitation. Carbonaceous matter of semi-anthracite maturity is encapsulated in quartz grains adjacent to the Fe-oxide spherules (CM2) and it is thus concluded that CM1 and CM2 are most likely contemporaneous and of the same origin, either incorporated at the time of BIF formation or during the hydrothermal event at 2.52 Ga from the underlying phyllitised black shales. Carbonaceous matter (CM3) was also found around the Fe-oxide spherules and the martite grains. CM3 has much higher N contents (>5000 ppm), is of a lower maturity than CM1 and CM2, and is related to weathering, which is also indicated by the presence of goethite and kaolinite. The δ13C of all CMs varies from -19.4 to -24.7‰, similar to values measured in the underlying phyllitised black shales and likely reflect denitrifying microbial activity.

  7. Iron isotope and REE+Y composition of the Cauê banded iron formation and related iron ores of the Quadrilátero Ferrífero, Brazil

    Science.gov (United States)

    Mendes, Mônica; Lobato, Lydia M.; Kunzmann, Marcus; Halverson, Galen P.; Rosière, Carlos A.

    2016-04-01

    The Minas Supergroup banded iron formations (BIFs) of the Brazilian Quadrilátero Ferrífero (QF) mineral province experienced multiple deformational events synchronous with hypogene mineralization, which resulted in the metamorphism of BIFs to itabirites and their upgrade to high-grade iron ore. Here, we present rare earth element and yttrium (REE+Y) compositions together with iron isotope ratios of itabirites and their host iron orebodies from 10 iron deposits to constrain environmental conditions during BIF deposition and the effects of hypogene iron enrichment. The REE+Y characteristics of itabirites (positive Eu anomaly and LREE depletion) indicate hydrothermal iron contribution to the Minas basin. Iron isotope data and Ce anomalies suggest BIFs were precipitated by a combination of anoxic biological-mediated ferrous iron oxidation and abiotic oxidation in an environment with free oxygen (such as an oxygen oasis), perhaps related to increase in oxygen concentrations before the Great Oxidation Event (GOE). The similarity of the REE+Y composition of the itabirites from the different QF deformational domains, as well as to other Superior-type BIFs, indicates that the metamorphism and synchronous hydrothermal mineralization did not significantly affect the geochemical signature of the original BIFs. However, iron isotope compositions of iron ore vary systematically between deformational domains of the QF, likely reflecting the specific mineralization features in each domain.

  8. Petrology and geochemistry of the ~2.9 Ga Itilliarsuk banded iron formation and associated supracrustal rocks, West Greenland

    DEFF Research Database (Denmark)

    Haugaard, Rasmus; Frei, Robert; Stendal, Henrik;

    2013-01-01

    Here we present new field, petrographic and geochemical data from the ∼2.9 Ga Itilliarsuk banded iron formation (BIF) and associated lithologies within the Itilliarsuk supracrustal belt, south-eastern Nussuuaq, West Greenland. The supracrustals represent a volcanic–sedimentary sequence, which res...

  9. Anisotropic energy-gaps of iron-based superconductivity from intra-band quasiparticle interference in LiFeAs

    International Nuclear Information System (INIS)

    Cooper pairing in the Fe-based superconductors is thought to occur due to the projection of the antiferromagnetic interactions between iron atoms onto the complex momentum-space electronic structure. A key consequence is that distinct anisotropic energy gaps Δi(k) with specific relative orientations should occur on the different electronic bands i. To determine this previously unresolved gap structure high-precision spectroscopy is required. Here we introduce the STM technique of intra-band Bogolyubov quasiparticle scattering interference (QPI) to iron-based superconductor studies, focusing on LiFeAs. We identify the QPI signatures of three hole-like dispersions and, by introducing a new QPI technique, determine the magnitude and relative orientations of corresponding anisotropic Δi(k). Intra-band Bogolyubov QPI therefore yields the spectroscopic information required to identify the mechanism of superconductivity in Fe-based superconductors.

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

    Science.gov (United States)

    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

  11. The reliability of ∼2.9 Ga old Witwatersrand banded iron formations (South Africa) as archives for Mesoarchean seawater: Evidence from REE and Nd isotope systematics

    Science.gov (United States)

    Viehmann, Sebastian; Bau, Michael; Smith, Albertus J. B.; Beukes, Nicolas J.; Dantas, Elton L.; Bühn, Bernhard

    2015-11-01

    Pure marine chemical sediments, such as (Banded) Iron Formations, (B)IFs, are archives of geochemical proxies for the composition of Precambrian seawater and may provide information about the ancient hydrosphere-atmosphere system. We here present rare earths and yttrium (REY) and high precision Sm-Nd isotope data of ∼2.90 Ga old Superior-type BIFs from the Witwatersrand Supergroup, South Africa, and compare those with data for near-contemporaneous BIFs from the correlative Pongola Supergroup (Superior-type BIF) and from the Pietersburg Greenstone Belt (Algoma-type IF), respectively. All Witwatersrand samples studied display the typical general REY distribution of Archean seawater, but their REY anomalies are less pronounced and their immobile element concentrations are higher than those of other pure (B)IFs. These observations indicate the presence of significant amounts of detrital aluminosilicates in the Witwatersrand BIFs and question the reliability of the Contorted Bed and Water Tower BIFs (Parktown Formation, West Rand Group) as archives of Mesoarchean seawater. Significant post-depositional alteration of the REY budget and the Sm-Nd isotope system is not observed. The Nd isotopic compositions of the purest BIF samples, i.e. the most reliable archives for Witwatersrand seawater, show initial εNd values between -3.95 and -2.25. This range is more negative than what is observed in ambient shales, indicating a decoupling of suspended and dissolved loads in the "near-shore" Witwatersrand Basin seawater. However, εNd range overlaps with that of the correlative Pongola BIF (Alexander et al., 2008). The deeper-water Algoma-type Pietersburg BIF shows more positive (i.e. more mantle-like) εNd2.9Ga values, supporting the hypothesis that a significant amount of its REY inventory was derived from black smoker-style, high-temperature hydrothermal fluids that had altered seafloor basalts. In marked contrast, the dissolved REY budgets (including the Nd isotopic

  12. Empirical Records of Environmental Change across the Archean-Proterozoic Transition

    Science.gov (United States)

    Kaufman, A. J.

    2011-12-01

    Time-series geochemical analyses of scientific drill cores intersecting the Archean-Proterozoic transition suggest a coupling of environmental and biological change that culminated in the pervasive oxygenation of Earth's atmosphere and oceans. Elemental and multiple isotope measurements of sedimentary archives, including carbonate, shale, and banded iron-formation from Western Australia, South Africa, Brazil, and southern Canada, indicate important changes in the carbon, sulfur, and nitrogen cycles that monitor the redox state of the oceans and the cyanobacterial buildup of atmospheric oxygen and ozone. In response, continental weathering would have increased, resulting in the enhanced delivery of sulfate and nutrients to seawater, further stimulating photoautotrophic fluxes of oxygen to surface environments. The positive feedback may additionally be responsible for the decline of atmospheric methane and surface refrigeration, represented by a series of discrete ice ages beginning around 2.4 billion years ago, due to the loss of greenhouse capacity during a time of lower solar luminosity. While speculative, the linkage of surface oxidation with enhanced nutrient supply and development of stratospheric sunscreen soon after the Archean-Proterozoic boundary suggests that the earliest perturbation in the carbon cycle may be associated with the rapid expansion of single-celled eukaryotes. Both sterol synthesis in eukaryotes and aerobic respiration require significant levels of oxygen in the ambient environment. Hence, Earth's earliest ice age(s) and onset of a modern and far more energetic carbon cycle may have been directly related to the global expansion of cyanobacteria that released oxygen to the environment, and of eukaryotes that respired it.

  13. Spin-wave band-pass filters based on yttrium iron garnet films for tunable microwave photonic oscillators

    Science.gov (United States)

    Ustinov, A. B.; Drozdovskii, A. V.; Nikitin, A. A.; Kalinikos, B. A.

    2015-12-01

    The paper reports on development of tunable band-pass microwave filters for microwave photonic generators. The filters were fabricated with the use of epitaxial yttrium iron garnet films. Principle of operation of the filters was based on excitation, propagation, and reception of spin waves. In order to obtain narrow pass band, the filtering properties of excitation and reception antennas were exploited. The filters demonstrated insertion losses of 2-3 dB, bandwidth of 25-35 MHz, and tuning range of up to 1.5 GHz in the range 3-7 GHz.

  14. Complex Permittivity and Permeability Measurements and Numerical Simulation of carbonyl iron rubber in X-Band frequency

    Directory of Open Access Journals (Sweden)

    Adriano Luiz de Paula

    2014-06-01

    Full Text Available Recognizing the importance of an adequate characterization of radar absorbing materials (RAM, and consequently their development, the present study aims to contribute for the establishment and validation of experimental determination and numerical simulation of complex permittivity and permeability of electromagnetic materials, using for this a carbonyl iron was seventy percent of the mass concentration. The present work branches out into two related topics. The first one is concerned with the implementation of a computational modeling to predict the behavior of electromagnetic materials in confined environment by using electromagnetic three-dimensional simulation. The second topic re-examines the Nicolson-Ross-Weir mathematical model to retrieve the constitutive parameters (complex permittivity and permeability of a homogeneous sample (carbonyl iron from scattering coefficient measurements. The measured and calculated results show a good convergence that guarantees the application of the used methodologies for the characterization of carbonyl iron rubber in x-band frequency.

  15. Iron

    Science.gov (United States)

    Iron is a mineral that our bodies need for many functions. For example, iron is part of hemoglobin, a protein which carries ... It helps our muscles store and use oxygen. Iron is also part of many other proteins and ...

  16. Red Supergiant Stars as Cosmic Abundance Probes: NLTE Effects in J-band Iron and Titanium Lines

    CERN Document Server

    Bergemann, Maria; Plez, Bertrand; Davies, Ben; Lind, Karin; Gazak, Zach

    2012-01-01

    Detailed non-LTE calculations for red supergiant stars are presented to investigate the influence of NLTE on the formation of atomic iron and titanium lines in the J-band. With their enormous brightness at J-band red supergiant stars are ideal probes of cosmic abundances. Recent LTE studies have found that metallicities accurate to 0.15 dex can be determined from medium resolution spectroscopy of individual red supergiants in galaxies as distant as 10 Mpc. The non-LTE results obtained in this investigation support these findings. Non-LTE abundance corrections for iron are smaller than 0.05 dex for effective temperatures between 3400K to 4200K and 0.1 dex at 4400K. For titanium the non-LTE abundance corrections vary smoothly between -0.4 dex and +0.2 dex as a function of effective temperature. For both elements, the corrections also depend on stellar gravity and metallicity. The physical reasons behind the non-LTE corrections and the consequences for extragalactic J-band abundance studies are discussed.

  17. RED SUPERGIANT STARS AS COSMIC ABUNDANCE PROBES: NLTE EFFECTS IN J-BAND IRON AND TITANIUM LINES

    International Nuclear Information System (INIS)

    Detailed non-LTE (NLTE) calculations for red supergiant (RSG) stars are presented to investigate the influence of NLTE on the formation of atomic iron and titanium lines in the J band. With their enormous brightness at J band RSG stars are ideal probes of cosmic abundances. Recent LTE studies have found that metallicities accurate to 0.15 dex can be determined from medium-resolution spectroscopy of individual RSGs in galaxies as distant as 10 Mpc. The NLTE results obtained in this investigation support these findings. NLTE abundance corrections for iron are smaller than 0.05 dex for effective temperatures between 3400 K and 4200 K and 0.1 dex at 4400 K. For titanium the NLTE abundance corrections vary smoothly between –0.4 dex and +0.2 dex as a function of effective temperature. For both elements, the corrections also depend on stellar gravity and metallicity. The physical reasons behind the NLTE corrections and the consequences for extragalactic J-band abundance studies are discussed.

  18. Fermi surface shrinking, band shifts and interband coupling in iron-based pnictides

    Energy Technology Data Exchange (ETDEWEB)

    Cappelluti, E., E-mail: emmanuele.cappelluti@romal.infn.i [SMC Research Center, CNR-INFM, Rome (Italy); Department of Physics, University ' La Sapienza' , Rome (Italy); Ortenzi, L.; Benfatto, L.; Pietronero, L. [Department of Physics, University ' La Sapienza' , Rome (Italy)

    2010-12-15

    Band shifts are systematically observed in pnictides using de Hass-van Alphen and ARPES techniques. Most interesting, such shifts result to be band-sensitive, so that hole-like bands are shifted downwards while electron-like ones are shifted upwards. In this contribution we present a comprehensive explanation for the origin of such band shifts. Using a four band Eliashberg analysis, we show that they are a natural consequence of the multiband character of these systems and of the strong particle-hole asymmetry of the bands. We also show that the relative sign of such shifts provides a direct experimental evidence of a dominant interband scattering. A quantitative analysis in LaFePO yields a spin-mediated interband coupling of the order V {approx} 0.46 eV which corresponds to a mass enhancement Z{approx}1.5.

  19. ^(40)Ar/^(39)Ar constraints on the age and thermal history of the Urucum Neoproterozoic banded iron-formation, Brazil

    OpenAIRE

    Piacentini, Thiago; Vasconcelos, Paulo M.; Farley, Kenneth A.

    2013-01-01

    Urucum is one of the youngest banded iron-formations (BIFs) yet its exact age remains uncertain. ^(40)Ar/^(39)Ar geochronology on late-diagenetic to early metamorphic cryptomelane from the Urucum sequence reveals a minimum depositional age of 587 ± 7 Ma. Metamorphic braunite age spectra yield flat segments defining apparent ages of 547 ± 3 Ma to 513 ± 4 Ma, interpreted as recrystallization or cooling ages. Metamorphic muscovite grains from a meta-arkose interbedded with the BIF yield reproduc...

  20. The Phenomenology of Iron Pnictides Superconductors Explained in the Framework of -Wave Three-Band Eliashberg Theory

    Directory of Open Access Journals (Sweden)

    G. A. Ummarino

    2010-01-01

    Full Text Available The s-wave three-band Eliashberg theory can simultaneously reproduce the experimental critical temperatures and the gap values of the superconducting materials LaFeAsO0.9F0.1, Ba0.6K0.4Fe2As2 and SmFeAsO0.8F0.2 as exponent of the more important families of iron pnictides. In this model the dominant role is played by interband interactions and the order parameter undergoes a sign reversal between hole and electron bands (±-wave symmetry. The values of all the gaps (with the exact experimental critical temperature can be obtained by using high values of the electron-boson coupling constants and small typical boson energies (in agreement with experiments.

  1. Iron

    Science.gov (United States)

    ... seafood, and foods that contain vitamin C , like citrus fruits, strawberries, sweet peppers, tomatoes, and broccoli. What ... diets. What are some effects of iron on health? Scientists are studying iron to understand how it ...

  2. Iron

    DEFF Research Database (Denmark)

    Hansen, Jakob Bondo; Moen, I W; Mandrup-Poulsen, T

    2014-01-01

    The interest in the role of ferrous iron in diabetes pathophysiology has been revived by recent evidence of iron as an important determinant of pancreatic islet inflammation and as a biomarker of diabetes risk and mortality. The iron metabolism in the β-cell is complex. Excess free iron is toxic......, but at the same time, iron is required for normal β-cell function and thereby glucose homeostasis. In the pathogenesis of diabetes, iron generates reactive oxygen species (ROS) by participating in the Fenton chemistry, which can induce oxidative damage and apoptosis. The aim of this review is to...... present and discuss recent evidence, suggesting that iron is a key pathogenic factor in both type 1 and type 2 diabetes with a focus on inflammatory pathways. Pro-inflammatory cytokine-induced β-cell death is not fully understood, but may include iron-induced ROS formation resulting in dedifferentiation...

  3. Observation of a Hidden Hole-Like Band Approaching the Fermi Level in K-Doped Iron Selenide Superconductor

    Science.gov (United States)

    Sunagawa, Masanori; Terashima, Kensei; Hamada, Takahiro; Fujiwara, Hirokazu; Fukura, Tetsushi; Takeda, Aya; Tanaka, Masashi; Takeya, Hiroyuki; Takano, Yoshihiko; Arita, Masashi; Shimada, Kenya; Namatame, Hirofumi; Taniguchi, Masaki; Suzuki, Katsuhiro; Usui, Hidetomo; Kuroki, Kazuhiko; Wakita, Takanori; Muraoka, Yuji; Yokoya, Takayoshi

    2016-07-01

    One of the ultimate goals of the study of iron-based superconductors is to identify the common feature that produces the high critical temperature (Tc). In the early days, based on a weak-coupling viewpoint, the nesting between hole- and electron-like Fermi surfaces (FSs) leading to the so-called s± state was considered to be one such key feature. However, this theory has faced a serious challenge ever since the discovery of alkali-metal-doped FeSe (AFS) superconductors, in which only electron-like FSs with a nodeless superconducting gap are observed. Several theories have been proposed, but a consistent understanding is yet to be achieved. Here we show experimentally that a hole-like band exists in KxFe2-ySe2, which presumably forms a hole-like Fermi surface. The present study suggests that AFS can be categorized in the same group as iron arsenides with both hole- and electron-like FSs present. This result provides a foundation for a comprehensive understanding of the superconductivity in iron-based superconductors.

  4. Ridge-trench collision in Archean and Post-Archean crustal growth: evidence from southern Chile

    International Nuclear Information System (INIS)

    The growth of continental crust at convergent plate margins involves both continuous and episodic processes. Ridge-trench collision is one episodic process that can cause significant magmatic and tectonic effects on convergent plate margins. Because the sites of ridge collision (ridge-trench triple junctions) generally migrate along convergent plate boundaries, the effects of ridge collision will be highly diachronous in Andean-type orogenic belts and may not be adequately recognized in the geologic record. The Chile margin triple junction (CMTJ, 46 deg S), where the actively spreading Chile rise is colliding with the sediment-filled Peru-Chile trench, is geometrically and kinematically the simplest modern example of ridge collision. The south Chile margin illustrates the importance of the ridge-collision tectonic setting in crustal evolution at convergent margins. Similarities between ridge-collision features in southern Chile and features of Archean greenstone belts raise the question of the importance of ridge collision in Archean crustal growth. Archean plate tectonic processes were probably different than today; these differences may have affected the nature and importance of ridge collision during Archean crustal growth. In conclusion, it is suggested that smaller plates, greater ridge length, and/or faster spreading all point to the likelihood that ridge collision played a greater role in crustal growth and development of the greenstone-granite terranes during the Archean. However, the effects of modern ridge collision, and the processes involved, are not well enough known to develop specific models for the Archean ridge collison

  5. Preparation of Ni-B Coating on Carbonyl Iron and Its Microwave Absorption Properties in the X Band

    Science.gov (United States)

    Li, Rong; Zhou, Wan-Cheng; Qing, Yu-Chang

    2014-09-01

    Ni-B coated carbonyl iron particles (CI@Ni-B) are prepared by the electroless plating technique. The structure, morphology, and antioxidant properties of the CI@Ni-B particles are analyzed. The results demonstrate that the CI particles have been coated with intact spherical-shell Ni-B coating, indicating the core-shell structure of CI@Ni-B particles, and the Ni-B coating can prevent the further oxidation of the CI particles. Compared with the raw CI particles/paraffin coatings with the same coating thickness of 2.0 mm and particles content of 70%, the CI@Ni-B particles/paraffin coatings possess higher microwave absorption (the RL exceeding -10 dB is obtained in the whole X band (8.2-12.4 GHz) with minimal RL of -35.0 dB at 9.2 GHz).

  6. Venus and the Archean Earth: Thermal considerations

    International Nuclear Information System (INIS)

    The Archean Era of the Earth is not a direct analog of the present tectonics of Venus. In this regard, it is useful to review the state of the Archean Earth. Most significantly, the temperature of the adiabatic interior of the Earth was 200 to 300 C hotter than the current temperature. Preservation biases limit what can be learned from the Archean record. Archean oceanic crust, most of the planetary surface at any one time, has been nearly all subducted. More speculatively, the core of the Earth has probably cooled more slowly than the mantle. Thus the temperature contrast above the core-mantle boundary and the vigor of mantle plumes has increased with time on the Earth. The most obvious difference between Venus and the present Earth is the high surface temperature and hence a low effective viscosity of the lithosphere. In addition, the temperature contrast between the adiabatic interior and the surface, which drives convection, is less on Venus than on the Earth. It appears that the hot lithosphere enhanced tectonics on the early Venus significantly enough that its interior cooled faster than the Earth's. The best evidence for a cool interior of Venus comes from long wavelength gravity anomalies. The low interior temperatures retard seafloor spreading on Venus. The high surface temperatures on Venus enhance crustal deformation. That is, the lower crust may become ductile enough to permit significant flow between the upper crust and the mantle. There is thus some analogy to modern and ancient areas of high heat flow on the Earth. Archean crustal blocks typically remained stable for long intervals and thus overall are not good analogies to the deformation style on Venus

  7. Pressure-induced magneto-structural transition in iron via a modified solid-state nudged elastic band method

    Science.gov (United States)

    Zarkevich, Nikolai A.; Johnson, Duane D.

    2015-03-01

    Materials under pressure may exhibit critical electronic and structural transitions that affect equation of states, as known for superconductors and the magneto-structural transformations of iron with both geophysical and planetary implications. While experiments often use constant-pressure (diamond-anvil cell, DAC) measurements, many theoretical results address a constant-volume transitions, which avoid issues with magnetic collapse but cannot be directly compared to experiment. We establish a modified solid-state nudge elastic band (MSS-NEB) method to handle magnetic systems that may exhibit moment (and volume) collapse during transformation. We apply it to the pressure-induced transformation in iron between the low-pressure body-centered cubic (bcc) and the high-pressure hexagonal close-packed (hcp) phases, find the bcc-hcp equilibrium coexistence pressure and a transitional pathway, and compare to shock and DAC experiments. We use methods developed with support by the U.S. Department of Energy (DE-FG02-03ER46026 and DE-AC02-07CH11358). Ames Laboratory is operated for the DOE by Iowa State University under contract DE-AC02-07CH11358.

  8. Effect of band filling in the paramagnetic tetragonal phase of iron chalcogenides

    International Nuclear Information System (INIS)

    The normal state of layered Fe-chalcogenide superconductors shows a range of anomalous, non-Fermi liquid responses. Unconventional metallic resistivity, characteristic pseudogap and saturating features and proximity to insulating states mark these systems as correlated metals. Motivated thereby, we use a combination of first-principles and many-particle calculations to show that multiband electronic correlations generate a low-energy pseudogap in the normal state of Fe(Te,Se) end-members, which, depending on the band filling, promotes incoherent metallic or orbital-selective insulating states. Upon comparison, good qualitative agreement with experimental (photoemission and electrical resistivity) data of FeTe1−xSe x systems is found. Based on observed charge transport we propose that the parent bulk compounds are best described as partially filled multiband systems. (paper)

  9. Texture-specific Si isotope variations in Barberton Greenstone Belt cherts record low temperature fractionations in early Archean seawater

    Science.gov (United States)

    Stefurak, Elizabeth J. T.; Fischer, Woodward W.; Lowe, Donald R.

    2015-02-01

    Sedimentary cherts are unusually abundant in early Archean (pre-3.0 Ga) sequences, suggesting a silica cycle that was profoundly different than the modern system. Previously applied for the purpose of paleothermometry, Si isotopes in ancient cherts can offer broader insight into mass fluxes and mechanisms associated with silica concentration, precipitation, diagenesis, and metamorphism. Early Archean cherts contain a rich suite of sedimentological and petrographic textures that document a history of silica deposition, cementation, silicification, and recrystallization. To add a new layer of insight into the chemistry of early cherts, we have used wavelength-dispersive spectroscopy and then secondary ion mass spectrometry (SIMS) to produce elemental and Si and O isotope ratio data from banded black-and-white cherts from the Onverwacht Group of the Barberton Greenstone Belt, South Africa. This geochemical data is then interpreted in the framework of depositional and diagenetic timing of silica precipitation provided by geological observations. SIMS allows the comparison of Si and O isotope ratios of distinct silica phases, including black carbonaceous chert beds and bands (many including well-defined sedimentary grains), white relatively pure chert bands including primary silica granules, early cavity-filling cements, and later quartz-filled veins. Including all chert types and textures analyzed, the δ30Si dataset spans a range from -4.78‰ to +3.74‰, with overall mean 0.20‰, median 0.51‰, and standard deviation 1.30‰ (n = 1087). Most samples have broadly similar δ30Si distributions, but systematic texture-specific δ30Si differences are observed between white chert bands (mean +0.60‰, n = 750), which contain textures that represent primary and earliest diagenetic silica phases, and later cavity-filling cements (mean -1.41‰, n = 198). We observed variations at a ∼100 μm scale indicating a lack of Si isotope homogenization at this scale during

  10. Archean Paleo-climate: The first snowball?

    CERN Document Server

    Durand-Manterola, Hector Javier

    2010-01-01

    The model accepted is one where during the Archean Eon the Earths climate was clement despite the weaker Sun. The observational evidence that supports this concept is: the emergence of life, the existence of evaporitic sediments and the presence of terrigenous sediments, all of which require liquid water and clement conditions. A theoretical argument used to support this idea is the so called ice-albedo feedback, which states that if the Earth was frozen, it would still be frozen.The aim of this document is to present an alternative scenario in which a frozen world, "snowball" style, with liquid water at the bottom of the sea, also allows for the emergence of life and evaporitic and terrigenous sedimentation. Archean climatic evidence, available at present, is discussed and can be reinterpreted to support the idea that, in Archean times, the surface of the Earth was frozen. Also, a mathematical model is being developed to demonstrate that the ice-albedo feedback is not an inevitable consequence of a frozen Ar...

  11. Interpretation of high resolution aeromagnetic data for lineaments study and occurrence of Banded Iron Formation in Ogbomoso area, Southwestern Nigeria

    Science.gov (United States)

    Oladunjoye, Michael Adeyinka; Olayinka, Abel Idowu; Alaba, Mustapha; Adabanija, Moruffdeen Adedapo

    2016-02-01

    The quest for solid mineral resource as an alternative for oil income in Nigeria presents opportunity to diversify the resource base of the country. To fill some information gap on the long abandoned Ajase and Gbede Banded Iron Formations (BIF) in Ogbomoso area, Southwestern Nigeria, high resolution aeromagnetic data of Ogbomoso - Sheet 222 was interpreted; to provide a better understanding of the mode of occurrence of the iron ore and associated structural features and geologic model. These were accomplished by subjecting reduced-to-pole (RTP) residual aeromagnetic intensity map to various data filtering and processing involving total horizontal derivative, vertical derivative, Upward Continuation (UC), Downward Continuation (DC), Euler Deconvolution at different Spectral Indices (SI), and Analytical signal using Geosoft Oasis Montaj 6.4.2 (HJ) data processing and analysis software. The resultants maps were overlain, compared and or plotted on RTP residual aeromagnetic intensity map and or geological map and interpreted in relation to the surface geological map. Positive magnetic anomalies observed on the RTP residual aeromagnetic intensity map ranged from 2.1 to 94.0 nT and associated with contrasting basement rocks, Ajase and Gbede BIF; while negative magnetic anomalies varied between -54.7 nT and -2.8 nT and are associated with intrusive bodies. Interpreted lineaments obtained from total horizontal derivative map were separated into two categories namely ductile and brittle based on their character vis-à-vis magnetic anomalies on RTP intensity map. Whilst the brittle lineaments were interpreted as fracture or faults; the ductile lineaments were interpreted as folds or representing the internal fabric of the rock units. In addition prominent magnetic faults mainly due to offset of similar magnetic domain/gradient were also interpreted. The iron ore mineralization is distributed within the eastern portion of the study area with Ajase BIF at relatively greater

  12. Stratigraphic and tectonic settings of Proterozoic glaciogenic rocks and banded iron-formations: relevance to the snowball Earth debate

    Science.gov (United States)

    Young, Grant M.

    2002-11-01

    Among Palaeoproterozoic glacial deposits on four continents, the best preserved and documented are in the Huronian on the north shore of Lake Huron, Ontario, where three glaciogenic formations have been recognized. The youngest is the Gowganda Formation. The glacial deposits of the Gowganda Formation were deposited on a newly formed passive margin. To the west, on the south side of Lake Superior, the oldest Palaeoproterozoic succession (Chocolay Group) begins with glaciogenic diamictites that have been correlated with the Gowganda Formation. The >2.2 Ga passive margin succession (Chocolay Group=upper Huronian) is overlain, with profound unconformity, by a >1.88 Ga succession that includes the superior-type banded iron-formations (BIFs). The iron-formations are therefore not genetically associated with Palaeoproterozoic glaciation but were deposited ˜300 Ma later in a basin that formed as a result of closure of the "Huronian" ocean. In Western Australia, Palaeoproterozoic glaciogenic deposits of the Meteorite Bore Member appear to have formed part of a similar basin fill. The glaciogenic rocks are, however, separated from underlying BIF by a thick siliciclastic succession. In both North America and Western Australia, BIF-deposition took place in compressional (possibly foreland basin) settings but the iron-formations are of greatly different age, suggesting that the most significant control on their formation was not oxygenation of the Earth's atmosphere but rather, emplacement of Fe-rich waters (uplifted as a result of ocean floor destruction?) in a siliciclastic-starved environment where oxidation (biogenic?) could take place. Some of the Australian BIFs appear to predate the appearance of red beds in North American Palaeoproterozoic successions and are therefore unlikely to be related to oxygenation of the atmosphere. Neoproterozoic glaciogenic deposits are widespread on the world's continents. Some are associated with iron-formations. Two theories have emerged

  13. Sulphur tales from the early Archean world

    Science.gov (United States)

    Montinaro, A.; Strauss, H.

    2016-07-01

    Sedimentary and magmatic rocks and their distinct sulphur isotopic signatures indicate the sources and processes of sulphur cycling, in particular through the analysis of all four stable sulphur isotopes (32S, 33S, 34S and 36S). Research over the past 15 years has substantially advanced our understanding of sulphur cycling on the early Earth, most notably through the discovery of mass-independently fractionated sulphur isotopic signatures. A strong atmospheric influence on the early Archean global sulphur cycle is apparent, much in contrast to the modern world. Diverse microbially driven sulphur cycling is clearly discernible, but its importance for Earth surface environments remains to be quantified.

  14. Sulfate was a trace constituent of Archean seawater

    DEFF Research Database (Denmark)

    Crowe, Sean Andrew; Paris, Guillaume; Katsev, Sergei;

    2014-01-01

    In the low-oxygen Archean world (>2400 million years ago), seawater sulfate concentrations were much lower than today, yet open questions frustrate the translation of modern measurements of sulfur isotope fractionations into estimates of Archean seawater sulfate concentrations. In the water column...

  15. Development of an X-ray Telescope with a Large Effective Area for the Iron K Line Band

    Science.gov (United States)

    Matsumoto, Hironori; Tachibana, Sasagu; Yoshikawa, Shun; Tamura, Keisuke; Mori, Hideyuki; Mitsuishi, Ikuyuki; Tawara, Yuzuru; Kunieda, Hideyo; Yamashita, Kojun

    2015-08-01

    X-ray micro-calorimeters such as the Soft X-ray Spectrometer (SXS) on board ASTRO-H will enable precise spectroscopy of iron K lines even for spatially extended objects. To exploit the full power of the high-energy resolution, X-ray telescopes with a large effective area around 6 keV are essentially important. Conventional Wolter-I X-ray telescopes aimed at X-rays below 10 keV have used the principle of total reflection to collect the X-rays. Enlarging the diameter of this type of telescopes is not effective to obtain the large effective area, since the incident angle of X-rays for the outer part of the telescope exceeds the critical angle, and the X-ray reflectivity of the outer part is significantly low. For example, the critical angle of Ir for an X-ray of 6 keV is 0.748 deg. Thus if we assume a focal length of 6 m for a Wolter-I optics using mirrors covered with Ir as a reflector, the mirrors the radial position of which are larger than 34 cm cannot reflect X-rays above 6 keV effectively. If multi-layer mirrors are applied to the outer part of the telescope, however, the X-ray reflectivity can be enhanced significantly by the principle of Bragg reflection. Our objective is to develop a Wolter-I X-ray telescope with an aperture of 110 cm and a focal length of 6 m, and make all mirrors in the telescope can reflect X-rays around 6 keV effectively by utilizing the multi-layer mirrors. The size of the telescope is determined by a boundary condition that can be launched by the epsilon rocket of ISAS/JAXA. The multi-layer is designed to enhance the reflectivity at 6.4 keV, 6.7 keV, or 6.9 keV. Our simulation suggests that the effective area averaged in the 5.7-7.7 keV band could be 2000 cm2, whichis comparable to the effective area of Athena launched in 2028 by ESA. Furthermore, we showed that the Ir/C multi-layers produced by our DC magnetron sputtering machine has a surface roughness of less than 4 angstrom. This value is smaller than the average surface roughness

  16. Zircon Archean of the Transuralian megazone

    Science.gov (United States)

    Krasnobaev, A. A.; Puchkov, V. N.; Puzhakov, B. A.; Busharina, S. V.; Sergeeva, N. D.

    2015-12-01

    The Il'inka metamorphic complex (IC) is located in the Transuralian megazone at the latitude of the Chelyabinsk granite pluton, east of the Chelyabinsk graben. The petrological, mineralogical, and age data on the IC indicate the presence of Archean complexes during its formation. Taking into account the importance of the age data on IC, zircons were additionally analyzed using a SHRIMP. For the Transuralian megazone, the analytical data allowed us for the first time to establish the presence of the Neoarchean (2715 ± 15 Ma) substance and two stages of metamorphism of gneisses. The early stage was in the Paleoproterozoic (1970-2130 Ma). The metamorphism of 648 ± 18 Ma ends the evolution of IC.

  17. Generation of hydrothermal Fe-Si oxyhydroxide deposit on the Southwest Indian Ridge and its implication for the origin of ancient banded iron formations

    Science.gov (United States)

    Sun, Zhilei; Li, Jun; Huang, Wei; Dong, Hailiang; Little, Crispin T. S.; Li, Jiwei

    2015-01-01

    hydrothermal Fe-Si oxyhydroxide deposits are now known to be analogues to ancient siliceous iron formations. In this study, samples of Fe-Si oxyhydroxide deposits were collected from hydrothermal field on the Southwest Indian Ridge. An investigation of mineralization in these deposits was carried out based on a series of mineralogical and morphological methods. X-ray diffraction and selected area electron diffraction analysis show that amorphous opal and poorly crystalline ferrihydrite are the major minerals. Furthermore, some typical filament structures detected by scanning electronic microscopy examinations, probably indicating the presence of Fe-oxidizing bacteria (FeOB), are pervasive with the main constituents being Fe, Si, P, and C. We thus believe that chemolithoautotrophic FeOB play a significant role in the formation of Fe oxyhydroxide which can effectively oxidize reduced Fe(II) sourced from hydrothermal fluids. Precipitation of amorphous silica, in contrast, is only a passive process with the Fe oxyhydroxide acting as a template. The distinct microlaminae structure alternating between the Fe-rich and Si-rich bands was observed in our samples for the first time in modern seafloor hydrothermal systems. We propose that its formation was due to the episodic temperature variation of the hydrothermal fluid which controls the biogenic Fe oxyhydroxide formation and passive precipitation of silica in this system. Our results might provide a clue for the formation mechanism of ancient banded iron formations.

  18. Source heterogeneity for the major components of ~3.7 Ga banded iron formations (Isua Greenstone Belt, Western Greenland)

    DEFF Research Database (Denmark)

    Frei, Robert; Polat, Ali

    2006-01-01

    protocrustal landmass (eNd(3.7 Ga)   + 1.6). The validity of two different and periodically interacting water masses (an essentially two-component mixing system) in the deposition of alternating iron- and silica-rich layers is also reflected by systematic trends in germanium (Ge)/silicon (Si) ratios. These...

  19. Observation of a Hidden Hole-Like Band Approaching the Fermi Level in K-Doped Iron Selenide Superconductor

    OpenAIRE

    Sunagawa, Masanori; Terashima, Kensei; Hamada, Takahiro; Fujiwara, Hirokazu; Fukura, Tetsushi; Takeda, Aya; Tanaka, Masashi; Takeya, Hiroyuki; Takano, Yoshihiko; Arita, Masashi; Shimada, Kenya; Namatame, Hirofumi; Taniguchi, Masaki; Suzuki, Katsuhiro; Usui, Hidetomo

    2016-01-01

    One of the ultimate goals of the study of iron-based superconductors is to identify the common feature that produces the high critical temperature (Tc). In the early days, based on a weak-coupling viewpoint, the nesting between hole- and electron-like Fermi surfaces (FSs) leading to the so-called $s\\pm$ state was considered to be one such key feature. However, this theory has faced a serious challenge ever since the discovery of alkali-metal-doped FeSe (AFS) superconductors, in which only ele...

  20. An investigation of the Archean climate using the NCAR CCm

    International Nuclear Information System (INIS)

    The Archean (2.5 to 3.8 billion years ago) is of interest climatically, because of the 'Faint-Young Sun Paradox', which can be characterized by the Sun's reduced energy output. This lower energy output leads to a frozen planet if the climate existed as it does today. But, the geologic record shows that water was flowing at the earth's surface 3.8 billion years ago. Energy Balance Models (EBMs) and one-dimensional radiative-convective (1DRC) models predict a frozen planet for this time period, unless large carbon dioxide (CO2) concentrations exist in the Archean atmosphere. The goal is to explore the Archean climate with the National Center for Atmospheric Research (NCAR), Community Climate Model (CCM). The search for negative feedbacks to explain the 'Faint-Young Sun Paradox' is the thrust of this study. This study undertakes a series of sensitivity simulations which first explores individual factors that may be important for the Archean. They include rotation rate, lower solar luminosity, and land fraction. Then, these climatic factors along with higher CO2 concentrations are combined into a set of experiments. A faster rotation rate may have existed in the Archean. The faster rotation rate simulations show warmer globally averaged surface temperatures that are caused by a 20 percent decrease in the total cloud fraction. The smaller cloud fraction is brought about by dynamical changes. A global ocean is a possibility for the Archean. A global ocean simulation predicts 4 K increase in global mean surface temperatures compared to the present-day climate control

  1. Intrinsic Josephson junctions in the iron-based multi-band superconductor (V2Sr4O6)Fe2As2

    Science.gov (United States)

    Moll, Philip J. W.; Zhu, Xiyu; Cheng, Peng; Wen, Hai-Hu; Batlogg, Bertram

    2014-09-01

    In layered superconductors, Josephson junctions may be formed within the unit cell as a result of sufficiently low inter-layer coupling. These intrinsic Josephson junction (iJJ) systems have attracted considerable interest for their application potential in quantum computing as well as efficient sources of THz radiation, closing the famous `THz gap'. So far, iJJ have been demonstrated in single-band, copper-based high-Tc superconductors, mainly in Bi-Sr-Ca-Cu-O (refs , , ). Here we report clear experimental evidence for iJJ behaviour in the iron-based superconductor (V2Sr4O6)Fe2As2. The intrinsic junctions are identified by periodic oscillations of the flux-flow voltage on increasing a well-aligned in-plane magnetic field. The periodicity is explained by commensurability effects between the Josephson vortex lattice and the crystal structure, which is a hallmark signature of Josephson vortices confined into iJJ stacks. This finding adds the pnictide (V2Sr4O6)Fe2As2 to the copper-based iJJ materials of interest for Josephson junction applications. In particular, novel devices based on multi-band Josephson coupling may be realized.

  2. Geochemistry of Archean metasedimentary rocks of the Aravalli craton, NW India: Implications for provenance, paleoweathering and supercontinent reconstruction

    Science.gov (United States)

    Ahmad, Iftikhar; Mondal, M. E. A.; Satyanarayanan, M.

    2016-08-01

    Basement complex of the Aravalli craton (NW India) known as the Banded Gneissic Complex (BGC) is classified into two domains viz. Archean BGC-I and Proterozoic BGC-II. We present first comprehensive geochemical study of the Archean metasedimentary rocks occurring within the BGC-I. These rocks occur associated with intrusive amphibolites in a linear belt within the basement gneisses. The association is only concentrated on the western margin of the BGC-I. The samples are highly mature (MSm) to very immature (MSi), along with highly variable geochemistry. Their major (SiO2/Al2O3, Na2O/K2O and Al2O3/TiO2) and trace (Th/Sc, Cr/Th, Th/Co, La/Sc, Zr/Sc) element ratios, and rare earth element (REE) patterns are consistent with derivation of detritus from the basement gneisses and its mafic enclaves, with major contribution from the former. Variable mixing between the two end members and closed system recycling (cannibalism) resulted in the compositional heterogeneity. Chemical index of alteration (CIA) of the samples indicate low to moderate weathering of the source terrain in a sub-tropical environment. In A-CN-K ternary diagram, some samples deceptively appear to have undergone post-depositional K-metasomatism. Nevertheless, their petrography and geochemistry (low K2O and Rb) preclude the post-depositional alteration. We propose non-preferential leaching of elements during cannibalism as the cause of the deceptive K-metasomatism as well as enigmatic low CIA values of some highly mature samples. The Archean metasedimentary rocks were deposited on stable basement gneisses, making the BGC-I a plausible participant in the Archean Ur supercontinent.

  3. Radiometric dating of bioalteration textures in Archean basaltic metaglasses

    International Nuclear Information System (INIS)

    Full text: Direct in-situ U-Pb dating of titanite which infills tubular bioalteration textures in pillow basalt rims from the ∼ 3.35 Ga Euro basalt of the Pilbara craton, W. Australia (PWA) confirms their Archean age. A novel in situ laser ablation multi-collector-ICP-MS technique is here reported that has enabled the first radiometric age determination of an Archean biosignature. Multiple lines of evidence suggest that these tubular bioalteration textures formed by microbial etching of formerly glassy Archean lavas that were subsequently mineralized by titanite. Firstly, there are striking morphological similarities between tubular structures from both the Pilbara and Barberton (BGB) cratons and bioalteration textures in modern glasses. Secondly, x-ray mapping indicates C enriched along the margins of the tubular structures from both the BGB and PWA. Thirdly, disseminated carbonates in the BGB pillow rims have C-isotopes depleted by as much as -16 %o, which is consistent with microbial oxidation of organic matter. A pre-metamorphic age for these microtubes is indicated by their segmentation caused by metamorphic chlorite overgrowths. A laser ablation spot size of ∼ 40 μm was used to analyze titanite in the 'root zones' at the centre of microtube clusters. Thirteen analyzes upon three thin sections gave a weighted average 206Pb/238U age of 2921 ± 110 Ma. This corresponds to the oldest metamorphic episode that has affected the PWA rocks and gives a minimum, late Archean age estimate for the bioalteration. (author)

  4. Petrogenesis of calcic plagioclase megacrysts in Archean rocks

    Science.gov (United States)

    Phinney, W. C.; Morrison, D. A.

    1986-01-01

    Anorthositic complexes with large equidimensional plagioclase grains of highly calcic composition occur in nearly all Archean cratons. Similar plagioclase occur as megacrysts in many Archean sills, dikes, and volcanic flows. In the Canadian Shield these units occur throughout the Archean portions of the entire shield and are particularly common as dikes over an area of a few 100,000 sq km in Ontario and Manitoba during a period of at least 100 m.y. in many different rock types and metamorphic grades. The plagioclase generally occurs in three modes: as inclusions in mafic intrusions at various stages of fractionation, as crystal segregations in anorthosite complexes, or as megacrysts in fractionated sills, dikes, and flows. Most occurrences suggest that the plagioclase was formed elsewhere before being transported to its present location. The evidence seems to be quite clear that occurrences of these types of calcic plagioclase require: (1) ponding of a relatively undifferentiated Archean tholeiitic melt at some depth; (2) isothermal crystallization of large, equidimensional homogeneous plagioclase crystals; (3) separation of the plagioclase crystals from any other crystalline phases; (4) further fractionation of melt; (5)transport of various combinations of individual plagioclase crystals and clusters of crystals by variously fractionated melts; and (6) emplacement as various types of igneous intrusions or flows.

  5. Progressive removal of an upper-mantle KREEP component by TTG magmatism through the Archean

    Science.gov (United States)

    Guitreau, M.; Blichert-Toft, J.; Herve, M.; Mojzsis, S. J.; Albarede, F.

    2010-12-01

    It has been suggested [1,2] that the proto-crust parental to the host granites of the Hadean Jack Hills zircons formed at ~4.35 Ga and evolved from a geochemically enriched KREEPy mantle derived from the primordial differentiation of the magma ocean. The prevalence of TTGs in the Archean may be connected with their role as a source intermediary between KREEP-soaked magma ocean cumulates and Jack Hills-type granites [1]. Here we report Lu-Hf isotope analyses by solution MC-ICP-MS of 182 globally distributed TTGs ranging in age from 2.5 to 4.0 Ga. Of these, 127 samples have initial ɛHf from -1 to +4, 46 samples display negative initial ɛHf (-1 to -17), and 9 show positive initial ɛHf (+5 to +15), all without age or geographic correlations. Values of ɛHf>+4 are thought to reflect either too old ages resulting in too radiogenic initial 176Hf/177Hf, or disturbance of the Lu-Hf system. Negative ɛHf values represent either too young ages or reworking of earlier formed crust. Comparing our TTG results with literature data for detrital and igneous zircons, three features stand out: (1) a 2D density plot of literature zircons show that each orogenic segment (starting at 4.2, 3.8, 3.3, 2.7, and 2.5 Ga) forms a coherent positive trend (‘band’) with a positive slope characteristic of the Lu/Hf ratio of that particular crust segment; (2) the slopes of the bands become progressively steeper through the Archean, attesting to a correlative decrease in the Lu/Hf ratio; (3) the most radiogenic ɛHf values in each zircon-defined band are also the oldest and are always matched by TTGs and increase systematically from -2 at 4.2 Ga to +6 at 2.5 Ga. Each individual band probably corresponds to a particular orogenic episode starting with juvenile material extracted from the mantle and evolving through reworking of earlier crust from previous orogenic events. Although the overall increase in maximum ɛHf values of the origins of the individual bands should be viewed in light of the

  6. Magneto-structural transformations via a solid-state nudged elastic band method: Application to iron under pressure

    International Nuclear Information System (INIS)

    We extend the solid-state nudged elastic band method to handle a non-conserved order parameter, in particular, magnetization, that couples to volume and leads to many observed effects in magnetic systems. We apply this formalism to the well-studied magneto-volume collapse during the pressure-induced transformation in iron—from ferromagnetic body-centered cubic (bcc) austenite to hexagonal close-packed (hcp) martensite. We find a bcc-hcp equilibrium coexistence pressure of 8.4 GPa, with the transition-state enthalpy of 156 meV/Fe at this pressure. A discontinuity in magnetization and coherent stress occurs at the transition state, which has a form of a cusp on the potential-energy surface (yet all the atomic and cell degrees of freedom are continuous); the calculated pressure jump of 25 GPa is related to the observed 25 GPa spread in measured coexistence pressures arising from martensitic and coherency stresses in samples. Our results agree with experiments, but necessarily differ from those arising from drag and restricted parametrization methods having improperly constrained or uncontrolled degrees of freedom

  7. The Orosirian-Statherian banded iron formation-bearing sequences of the southern border of the Espinhaço Range, Southeast Brazil

    Science.gov (United States)

    Rolim, Vassily Khoury; Rosière, Carlos A.; Santos, João Orestes Schneider; McNaughton, Neal J.

    2016-01-01

    The Serra da Serpentina and the Serra de São José groups are two distinct banded iron formation-bearing metasedimentary sequences along the eastern border of the southern Espinhaço Range that were deposited on the boundary between the Orosirian and Statherian periods. The Serra da Serpentina Group (SSG) has an Orosirian maximum depositional age (youngest detrital zircon grain age = 1990 ± 16 Ma) and consists of fine clastic metasediments at the base and chemical sediments, including banded iron formations (BIFs), on the top, corresponding to the Meloso and Serra do Sapo formations, respectively, and correlating with the pre-Espinhaço Costa Sena Group. The SSG represents sedimentary deposition on an epicontinental-epeiric, slow downwarping sag basin with little tectonic activity. The younger Serra de São José Group (SJG) is separated from the older SSG by an erosional unconformity and was deposited in a tectonically active continental rift-basin in the early stages of the opening of the Espinhaço Trough. The Serra do São José sediments stretch along the north-south axis of the rift and comprise a complete cycle of transgressive sedimentary deposits, which were subdivided, from base to top, into the Lapão, Itapanhoacanga, Jacém and Canjica formations. The Itapanhoacanga Formation has a maximum depositional age of 1666 ± 32 Ma (Statherian), which coincides with the maximum depositional age (i.e., 1683 ± 11 Ma) of the São João da Chapada Formation, one of the Espinhaço Supergroup's basal units. The Serra de São José Rift and the Espinhaço Rift likely represent the same system, with basal units that are facies variations of the same sequence. The supracrustal rocks have undergone two stages of deformation during the west-verging Brasiliano orogeny that affected the eastern margin of the São Francisco Craton and generated a regional-scale, foreland N-S trending fold-thrust belt, which partially involved the crystalline basement. Thrust faults have

  8. Dating carbonaceous matter in archean cherts by electron paramagnetic resonance

    OpenAIRE

    Bourbin, Mathilde; Gourier, Didier; Binet, Laurent; Le Du, Yann; Derenne, Sylvie; Westall, Francès; Kremer, Barbara; Gautret, Pascale

    2013-01-01

    Ancient geological materials are likely to be contaminated through geological times. Thus, establishing the syngeneity of the organic matter embedded in a mineral matrix is a crucial step in the study of very ancient rocks. This is particularly the case for Archean siliceous sedimentary rocks (cherts), which record the earliest traces of life. We used electron paramagnetic resonance (EPR) for assessing the syngeneity of organic matter in cherts that have a metamorphic grade no higher than gre...

  9. Radiative forcings for 28 potential Archean greenhouse gases

    OpenAIRE

    B. Byrne; Goldblatt, C.

    2014-01-01

    Despite reduced insolation in the late Archean, evidence suggests a~warm climate which was likely sustained by a stronger greenhouse effect, the so-called faint young sun problem (FYSP). CO2 and CH4 are generally thought to be the mainstays of this enhanced greenhouse, though many other gases have been proposed. We present high accuracy radiative forcings for CO2, CH4, and 26 other gases, performing the radiative transfer calculations at line-by-line resolution and using HIT...

  10. Comment on "Radiative forcings for 28 potential Archean greenhouse gases" by Byrne and Goldblatt (2014)

    Science.gov (United States)

    Kochanov, R. V.; Gordon, I. E.; Rothman, L. S.; Sharpe, S. W.; Johnson, T. J.; Sams, R. L.

    2015-08-01

    In the recent article by Byrne and Goldblatt, "Radiative forcing for 28 potential Archean greenhouse gases", Clim. Past. 10, 1779-1801 (2014), the authors employ the HITRAN2012 spectroscopic database to evaluate the radiative forcing of 28 Archean gases. As part of the evaluation of the status of the spectroscopy of these gases in the selected spectral region (50-1800 cm-1), the cross sections generated from the HITRAN line-by-line parameters were compared with those of the PNNL database of experimental cross sections recorded at moderate resolution. The authors claimed that for NO2, HNO3, H2CO, H2O2, HCOOH, C2H4, CH3OH and CH3Br there exist large or sometimes severe disagreements between the databases. In this work we show that for only three of these eight gases a modest discrepancy does exist between the two databases and we explain the origin of the differences. For the other five gases, the disagreements are not nearly at the scale suggested by the authors, while we explain some of the differences that do exist. In summary, the agreement between the HITRAN and PNNL databases is very good, although not perfect. Typically differences do not exceed 10 %, provided that HITRAN data exist for the bands/wavelengths of interest. It appears that a molecule-dependent combination of errors has affected the conclusions of the authors. In at least one case it appears that they did not take the correct file from PNNL (N2O4 (dimer)+ NO2 was used in place of the monomer). Finally, cross sections of HO2 from HITRAN (which do not have a PNNL counterpart) were not calculated correctly in BG, while in the case of HF misleading discussion was presented there based on the confusion by foreign or noise features in the experimental PNNL spectra.

  11. Comment on "Radiative forcings for 28 potential Archean greenhouse gases" by Byrne and Goldblatt (2014

    Directory of Open Access Journals (Sweden)

    R. V. Kochanov

    2015-08-01

    Full Text Available In the recent article by Byrne and Goldblatt, "Radiative forcing for 28 potential Archean greenhouse gases", Clim. Past. 10, 1779–1801 (2014, the authors employ the HITRAN2012 spectroscopic database to evaluate the radiative forcing of 28 Archean gases. As part of the evaluation of the status of the spectroscopy of these gases in the selected spectral region (50–1800 cm−1, the cross sections generated from the HITRAN line-by-line parameters were compared with those of the PNNL database of experimental cross sections recorded at moderate resolution. The authors claimed that for NO2, HNO3, H2CO, H2O2, HCOOH, C2H4, CH3OH and CH3Br there exist large or sometimes severe disagreements between the databases. In this work we show that for only three of these eight gases a modest discrepancy does exist between the two databases and we explain the origin of the differences. For the other five gases, the disagreements are not nearly at the scale suggested by the authors, while we explain some of the differences that do exist. In summary, the agreement between the HITRAN and PNNL databases is very good, although not perfect. Typically differences do not exceed 10 %, provided that HITRAN data exist for the bands/wavelengths of interest. It appears that a molecule-dependent combination of errors has affected the conclusions of the authors. In at least one case it appears that they did not take the correct file from PNNL (N2O4 (dimer+ NO2 was used in place of the monomer. Finally, cross sections of HO2 from HITRAN (which do not have a PNNL counterpart were not calculated correctly in BG, while in the case of HF misleading discussion was presented there based on the confusion by foreign or noise features in the experimental PNNL spectra.

  12. Iron oxide copper-gold deposits in the Islamic Republic of Mauritania (phase V, deliverable 79): Chapter M in Second projet de renforcement institutionnel du secteur minier de la République Islamique de Mauritanie (PRISM-II)

    Science.gov (United States)

    Fernette, Gregory

    2015-01-01

    Mauritania hosts one significant copper-gold deposit, Guelb Moghrein and several occurrences, which have been categorized as iron oxide copper-gold (IOCG) deposits but which are atypical in some important respects. Nonetheless, Guelb Moghrein is an economically significant mineral deposit and an attractive exploration target. The deposit is of Archean age and is hosted by a distinctive metacarbonate rock which is part of a greenstone-banded iron formation (BIF) package within a thrust stack in the northern part of the Mauritanide Belt. The surrounding area hosts a number of similar copper-gold occurrences. Based on the characteristics of the Guelb Moghrein deposit and its geologic environment, five tracts which are considered permissive for IOCG type mineralization similar to Guelb Moghrein have been delineated.

  13. In situ carbon isotope analysis of Archean organic matter with SIMS

    Science.gov (United States)

    Williford, K. H.; Ushikubo, T.; Lepot, K.; Hallmann, C.; Spicuzza, M. J.; Eigenbrode, J. L.; Summons, R. E.; Valley, J. W.

    2011-12-01

    rates as low as 10% relative to anthracite. Samples from the ABDP-9 (n=3; Mount McRae Shale, ~2.5 Ga), RHDH2a (n=2; Carrawine Dolomite and Jeerinah Fm, ~2.6 Ga), WRL1 (n=3; Wittenoom Fm, Marra Mamba Iron Formation, and Jeerinah Fm, ~2.6 Ga), and SV1 (n=1; Tumbiana Fm, ~2.7 Ga) drill cores, each previously analyzed for bulk organic carbon isotope composition, yielded 100 new, in situ data from Neoarchean sedimentary OM. In these samples, δ13C varies between -53.1 and -28.3% and offsets between in situ and bulk compositions range from -8.3 to 18.8%. In some cases, isotopic composition and mode of occurrence (e.g. morphology and mineral associations) are statistically correlated, enabling the identification of distinct reservoirs of OM. Our results support previous evidence for aerobiosis and depth gradients of oxidation in Neoarchean environments driven by photosynthesis and methane metabolism. The relevance of these findings to questions of bio- and syngenicity as well as the alteration history of this OM and similar, previously reported Archean OM will be discussed.

  14. Radiative forcings for 28 potential Archean greenhouse gases

    Directory of Open Access Journals (Sweden)

    B. Byrne

    2014-05-01

    Full Text Available Despite reduced insolation in the late Archean, evidence suggests a warm climate which was likely sustained by a stronger greenhouse effect, the so-called Faint Young Sun Problem (FYSP. CO2 and CH4 are generally thought to be the mainstays of this enhanced greenhouse, though many other gases have been proposed. We present high accuracy radiative forcings for CO2, CH4 and 26 other gases, performing the radiative transfer calculations at line-by-line resolution and using HITRAN 2012 line data for background pressures of 0.5, 1, and 2 bar. For CO2 to resolve the FYSP alone, 0.21 bar is needed with 0.5 bar of atmospheric pressure, 0.13 bar with 1 bar of atmospheric pressures, or 0.07 bar with 2 bar of atmospheric pressure. For CH4, we find that near-infrared absorption is much stronger than previously thought, arising from updates to the HITRAN database. CH4 radiative forcing peaks at 10.3, 9, or 8.3 W m−2 for background pressures of 0.5, 1 or 2 bar, likely limiting the utility of CH4 for warming the Archean. For the other 26 HITRAN gases, radiative forcings of up to a few to 10 W m−2 are obtained from concentrations of 0.1–1 ppmv for many gases. We further calculate the reduction of radiative forcing due to gas overlap for the 20 strongest gases. We recommend the forcings provided here be used both as a first reference for which gases are likely good greenhouse gases, and as a standard set of calculations for validation of radiative forcing calculations for the Archean.

  15. Radiative forcings for 28 potential Archean greenhouse gases

    OpenAIRE

    B. Byrne; Goldblatt, C.

    2014-01-01

    Despite reduced insolation in the late Archean, evidence suggests a warm climate which was likely sustained by a stronger greenhouse effect, the so-called Faint Young Sun Problem (FYSP). CO2 and CH4 are generally thought to be the mainstays of this enhanced greenhouse, though many other gases have been proposed. We present high accuracy radiative forcings for CO2, CH4 and 26 other gases, performing the radiative transfer calculations at line-by-line resolution and using HITRAN 2012 line data ...

  16. Iron and Iron Metabolism

    OpenAIRE

    Melike Sezgin Evim; Birol Baytan; Adalet Meral Güneş

    2012-01-01

    Iron is an essential element for almost all living organisms except some bacteria. A great number of new articles related to the iron metabolism have been published in recent years explaining new findings. Hepsidine, a peptide hormon, that is recently found, regulates iron methabolism by effecting iron absorbsion from gut, secreting iron from hepatic store and flows iron from macrophages. Hepsidin blockes to effluxe iron from cells by bounding to ferroportin and by inducing ferroportin destru...

  17. Biogenic nitrogen and carbon in Fe-Mn-oxyhydroxides from an Archean chert, Marble Bar, Western Australia

    Science.gov (United States)

    Pinti, Daniele L.; Hashizume, Ko; Orberger, Beate; Gallien, Jean-Paul; Cloquet, Christophe; Massault, Marc

    2007-02-01

    To quantify and localize nitrogen (N) and carbon (C) in Archean rocks from the Marble Bar formation, Western Australia, and to gain insights on their origin and potential biogenicity, we conducted nuclear reaction analyses (NRA) and carbon and nitrogen isotope ratio measurements on various samples from the 3460-Myr-old Fe-rich Marble Bar chert. The Marble Bar chert formed during the alteration of basaltic volcanoclastic rocks with Fe- and Si-rich hydrothermal fluids, and the subsequent precipitation of magnetite, carbonates, massive silica, and, locally, sulfides. At a later stage, the magnetite, sulfides, and carbonates were replaced by Fe-Mn-oxyhydroxides. Nuclear reaction analyses indicate that most of the N and C resides within these Fe-Mn-oxyhydroxides, but a minor fraction is found in K-feldspars and Ba-mica dispersed in the silica matrix. The N and C isotopic composition of Fe-oxides suggests the presence of a unique biogenic source with δ 15NAIR values from +6.0 +/- 0.5‰ to 7.3 +/- 1.1‰ and a δ 13CPDB value of -19.9 +/- 0.1‰. The C and N isotope ratios are similar to those observed in Proterozoic and Phanerozoic organic matter. Diffusion-controlled fractionation of N and C released during high combustion temperatures indicates that these two elements are firmly embedded within the iron oxides, with activation energies of 18.7 +/- 3.7 kJ/mol for N and 13.0 +/- 3.8 kJ/mol for C. We propose that N and C were chemisorbed on iron and were subsequently embedded in the crystals during iron oxidation and crystal growth. The Fe-isotopic composition of the Marble Bar chert (δ 56Fe = -0.38 +/- 0.02‰) is similar to that measured in iron oxides formed by direct precipitation of iron from hydrothermal plumes in contact with oxygenated waters. To explain the N and C isotopic composition of Marble Bar chert, we propose either (1) a later addition of N and C at the end of Archean when oxygen started to rise or (2) an earlier development of localized oxygenated

  18. Coupled Fe and S isotope variations in pyrite nodules from Archean shale

    Science.gov (United States)

    Marin-Carbonne, Johanna; Rollion-Bard, Claire; Bekker, Andrey; Rouxel, Olivier; Agangi, Andrea; Cavalazzi, Barbara; Wohlgemuth-Ueberwasser, Cora C.; Hofmann, Axel; McKeegan, Kevin D.

    2014-04-01

    Iron and sulfur isotope compositions recorded in ancient rocks and minerals such as pyrite (FeS2) have been widely used as a proxy for early microbial metabolisms and redox evolution of the oceans. However, most previous studies focused on only one of these isotopic systems. Herein, we illustrate the importance of in-situ and coupled study of Fe and S isotopes on two pyrite nodules in a c. 2.7 Ga shale from the Bubi Greenstone Belt (Zimbabwe). Fe and S isotope compositions were measured both by bulk-sample mass spectrometry techniques and by ion microprobe in-situ methods (Secondary Ion Mass Spectrometry, SIMS). Spatially-resolved analysis across the nodules shows a large range of variations at micrometer-scale for both Fe and S isotope compositions, with δ56Fe and δ34S values from -2.1 to +0.7‰ and from -0.5 to +8.2‰, respectively, and Δ33S values from -1.6 to +2.9‰. The Fe and S isotope variations in these nodules cannot be explained by tandem operation of Dissimilatory Iron Reduction (DIR) and Bacterial Sulfate Reduction (BSR) as was previously proposed, but rather they reflect the contributions of different Fe and S sources during a complex diagenetic history. Pyrite formed from two different mineral precursors: (1) mackinawite precipitated in the water column, and (2) greigite formed in the sediment during early diagenesis. The in-situ analytical approach reveals a complex history of the pyrite nodule growth and allows us to better constrain environmental conditions during the Archean.

  19. Spatially Resolved, In Situ Carbon Isotope Analysis of Archean Organic Matter

    Science.gov (United States)

    Williford, Kenneth H.; Ushikubo, Takayuki; Lepot, Kevin; Hallmann, Christian; Spicuzza, Michael J.; Eigenbrode, Jennifer L.; Summons, Roger E.; Valley, John W.

    2011-01-01

    Archean OM suggest that instrumental bias is consistent for 12C count rates as low as 10% relative to anthracite. Samples from the ABDP-9 (n=3; Mount McRae Shale, approximately 2.5 Ga), RHDH2a (n=2; Carrawine Dolomite and Jeerinah Fm, approximately 2.6 Ga), WRL1 (n=3; Wittenoom Fm, Marra Mamba Iron Formation, and Jeerinah Fm, approximately 2.6 Ga), and SV1 (n=1; Tumbiana Fm, approximately 2.7 Ga) drill cores, each previously analyzed for bulk organic carbon isotope composition, yielded 100 new, in situ data from Neoarchean sedimentary OM. In these samples, delta C-13 varies between -53.1 and -28.3 % and offsets between in situ and bulk compositions range from -8.3 to 18.8%. In some cases, isotopic composition and mode of occurrence (e.g. morphology and mineral associations) are statistically correlated, enabling the identification of distinct reservoirs of OM. Our results support previous evidence for gradients of oxidation with depth in Neoarchean environments driven by photosynthesis and methane metabolism. The relevance of these findings to questions of bio- and syngenicity as well as the alteration history of previously reported Archean OM will be discussed.

  20. Late Archean Euxinia as a Window into Early Biogeochemical Cycles

    Science.gov (United States)

    Scott, C.; Bekker, A.; Reinhard, C.; Lyons, T. W.

    2009-12-01

    A number of transition metals present in seawater in trace amounts (10-10 to 10-7 moles/L) are nevertheless bioessential micronutrients, utilized in a wide range of cellular activities. Because their abundances in seawater are largely a reflection of redox-controlled sources and sinks, Precambrian biogeochemists increasingly focus on the interrelated nature of major redox transitions, the chemical composition of the oceans, and the evolution of life on Earth. Of particular interest are temporal trends in seawater inventories of elements utilized in the nitrogen cycle, both nitrogen fixation (Fe, V, Mo) and denitrification (Cu). Recent work on the link between trace metal abundance and the biologically mediated nitrogen cycle has focused on the Proterozoic Eon, when oxidative weathering was well established and sulfidic conditions were common in the deep ocean. However, we know little about trace metal availability during the Archean Eon, when oxygenic photosynthesis first appeared on Earth and began to alter the chemical composition of the oceans and atmosphere. The development of euxinic conditions, or anoxic and sulfidic bottom waters, provides important information regarding the cycling of major elements such as C, S and Fe. However, euxinic black shales can also provide a record of trace metal abundance. Mo is highly enriched in these shales and displays a conspicuous covariation with the concentration of total organic carbon (TOC). Furthermore, it has been demonstrated that the ratio Mo/TOC is proportional to the concentration of Mo in seawater. Cu and V are also enriched in euxinic black shales, and both correlate with TOC. By analogy with Mo, it is likely that the ratios Cu/TOC and V/TOC also contain information on the concentration of these transition metals in seawater. Here we present C-S-Fe systematics as well as trace metal concentrations from black shales of the Roy Hill Member of the late Archean Jeerinah Formation. Fe speciation indicates that the

  1. Broad-band X-ray emission and the reality of the broad iron line from the neutron star-white dwarf X-ray binary 4U 1820-30

    Science.gov (United States)

    Mondal, Aditya S.; Dewangan, G. C.; Pahari, M.; Misra, R.; Kembhavi, A. K.; Raychaudhuri, B.

    2016-09-01

    Broad relativistic iron lines from neutron star X-ray binaries are important probes of the inner accretion disc. The X-ray reflection features can be weakened due to strong magnetic fields or very low iron abundances such as is possible in X-ray binaries with low mass, first generation stars as companions. Here, we investigate the reality of the broad iron line detected earlier from the neutron-star low-mass X-ray binary 4U 1820-30 with a degenerate helium dwarf companion. We perform a comprehensive, systematic broad-band spectral study of the atoll source using Suzaku and simultaneous NuSTAR and Swift observations. We have used different continuum models involving accretion disc emission, thermal blackbody and thermal Comptonization of either disc or blackbody photons. The Suzaku data show positive and negative residuals in the region of Fe K band. These features are well described by two absorption edges at 7.67 ± 0.14 keV and 6.93 ± 0.07 keV or partial covering photoionized absorption or by blurred reflection. Though, the simultaneous Swift and NuSTAR data do not clearly reveal the emission or absorption features, the data are consistent with the presence of either absorption or emission features. Thus, the absorption based models provide an alternative to the broad iron line or reflection model. The absorption features may arise in winds from the inner accretion disc. The broad-band spectra appear to disfavour continuum models in which the blackbody emission from the neutron-star surface provides the seed photons for thermal Comptonization. Our results suggest emission from a thin accretion disc (kTdisc ˜ 1 keV), Comptonization of disc photons in a boundary layer most likely covering a large fraction of the neutron-star surface and innermost parts of the accretion disc, and blackbody emission (kTbb ˜ 2 keV) from the polar regions.

  2. Drilling for the Archean Roots of Life and Tectonic Earth in the Barberton Mountains

    Directory of Open Access Journals (Sweden)

    Nicola McLoughlin

    2009-09-01

    Full Text Available In the Barberton Scientific Drilling Program (BSDP we successfully completed three drill holes in 2008 across strategically selected rock formations in the early Archean Barberton Greenstone Belt, South Africa. This collaborative project’s goal is to advance understanding of geodynamic and biogeochemical processes of the young Earth. The program aims to better define and characterize Earth’s earliest preserved ocean crust shear zones and microbial borings in Archean basaltic glass, and to identify biogeochemical fingerprints of ancient ecological niches recorded in rocks. The state-of-the-art analytical and imaging work will address the question of earliest plate tectonics in the Archean, the δ18O composition, the redox state and temperature of Archean seawater, and the origin of life question.

  3. Archean upper crust transition from mafic to felsic marks the onset of plate tectonics.

    Science.gov (United States)

    Tang, Ming; Chen, Kang; Rudnick, Roberta L

    2016-01-22

    The Archean Eon witnessed the production of early continental crust, the emergence of life, and fundamental changes to the atmosphere. The nature of the first continental crust, which was the interface between the surface and deep Earth, has been obscured by the weathering, erosion, and tectonism that followed its formation. We used Ni/Co and Cr/Zn ratios in Archean terrigenous sedimentary rocks and Archean igneous/metaigneous rocks to track the bulk MgO composition of the Archean upper continental crust. This crust evolved from a highly mafic bulk composition before 3.0 billion years ago to a felsic bulk composition by 2.5 billion years ago. This compositional change was attended by a fivefold increase in the mass of the upper continental crust due to addition of granitic rocks, suggesting the onset of global plate tectonics at ~3.0 billion years ago. PMID:26798012

  4. Archean upper crust transition from mafic to felsic marks the onset of plate tectonics

    Science.gov (United States)

    Tang, Ming; Chen, Kang; Rudnick, Roberta L.

    2016-01-01

    The Archean Eon witnessed the production of early continental crust, the emergence of life, and fundamental changes to the atmosphere. The nature of the first continental crust, which was the interface between the surface and deep Earth, has been obscured by the weathering, erosion, and tectonism that followed its formation. We used Ni/Co and Cr/Zn ratios in Archean terrigenous sedimentary rocks and Archean igneous/metaigneous rocks to track the bulk MgO composition of the Archean upper continental crust. This crust evolved from a highly mafic bulk composition before 3.0 billion years ago to a felsic bulk composition by 2.5 billion years ago. This compositional change was attended by a fivefold increase in the mass of the upper continental crust due to addition of granitic rocks, suggesting the onset of global plate tectonics at ~3.0 billion years ago.

  5. Dating Archean zircon by ion microprobe: New light on an old problem

    Science.gov (United States)

    Williams, I. S.; Kinny, P. D.; Black, L. P.; Compston, W.; Froude, D. O.; Ireland, T. R.

    1985-01-01

    Ion microprobe analysis of zircons from three sites (Watersmeet Dome in northern Michigan, Mount Sones in eastern Antarctica, and Mount Narryer in western Australia) is discussed. Implications of the results to Archean geochronology and early Earth crust composition are addressed.

  6. Geostable molecules and the Late Archean 'Whiff of Oxygen'

    Science.gov (United States)

    Summons, R. E.; Illing, C. J.; Oduro, H. D.; French, K. L.; Ono, S.; Hallmann, C.; Strauss, H.

    2012-12-01

    exhibits a 'MIF' signal that is significantly amplified compared to co-occurring pyrite sulfur. Limited isotopic exchange between the organic and inorganic sulfur pools suggests Archean origin of these organic sulfur compounds. We also report new results from the 2012 Agouron Pilbara drilling project. Anbar A.D. et al. A whiff of oxygen before the great oxidation event. Science 317, 1903-1906. (2007). Bosak T. et al., Morphological record of oxygenic photosynthesis in conical stromatolites. Proc. Natl. Acad. Sci. USA 106:10939-10943 (2009). Kopp, R.E. et al.,The Paleoproterozoic snowball Earth: A climate disaster triggered by the evolution of oxygenic photosynthesis. Proc. Natl. Acad. Sci. USA 102: 11131-11136 (2005). Waldbauer J.R. et al., Late Archean molecular fossils from the Transvaal Supergroup record the antiquity of microbial diversity and aerobiosis. Precambrian Research 169, 28-47 (2008). Waldbauer J.R. et al., 2011. Microaerobic steroid biosynthesis and the molecular fossil record of Archean life. Proceedings of the National Academy of Sciences (USA) 108, 13409-13414

  7. Geochemical evolution of magmatism in Archean granite-greenstone terrains

    Science.gov (United States)

    Samsonov, A. V.; Larionova, Yu. O.

    2006-05-01

    Evolution of Archean magmatism is one of the key problems concerning the early formation stages of the Earth crust and biosphere, because that evolution exactly controlled variable concentrations of chemical elements in the World Ocean, which are important for metabolism. Geochemical evolution of magmatism between 3.5 and 2.7 Ga is considered based on database characterizing volcanic and intrusive rock complexes of granite-greenstone terrains (GGT) studied most comprehensively in the Karelian (2.9-2.7 Ga) and Kaapvaal (3.5-2.9 Ga) cratons and in the Pilbara block (3.5-2.9 Ga). Trends of magmatic geochemical evolution in the mentioned GGTs were similar in general. At the early stage of their development, tholeiitic magmas were considerably enriched in chalcophile and siderophile elements Fe2O3, MgO, Cr, Ni, Co, V, Cu, and Zn. At the next stage, calc-alkaline volcanics of greenstone belts and syntectonic TTG granitoids were enriched in lithophile elements Rb, Cs, Ba, Th, U, Pb, Nb, La, Sr, Be and others. Elevated concentrations of both the “crustal” and “mantle-derived” elements represented a distinctive feature of predominantly intrusive rocks of granitoid composition, which were characteristic of the terminal stage of continental crust formation in the GGTs, because older silicic rocks and lithospheric mantle were jointly involved into processes of magma generation. On the other hand, the GGTs different in age reveal specific trends in geochemical evolution of rock associations close in composition and geological position. First, the geochemical cycle of GGT evolution was of a longer duration in the Paleoarchean than in the Meso-and Neoarchean. Second, the Paleoarche an tholeiitic associations had higher concentrations of LREE and HFSE (Zr, Ti, Th, Nb, Ta, Hf) than their Meso-and Neoarchean counterparts. Third, the Y and Yb concentrations in Paleoarchean calc-alkaline rock associations are systematically higher than in Neoarchean rocks of the same type

  8. Lightning associated to archean volcanic ash-gas clouds

    International Nuclear Information System (INIS)

    Lightning discharges of hundreds of meters in length are frequently generated during volcanic eruptions, in which gases and tephra are emitted simultaneously into the atmosphere. It is estimated that the lightning flux would be about 105 J km-2 min-1 during the explosive phase of a volcano. Was volcanic lightning an efficient energy source in the archean for the synthesis of prebiotic molecules? To answer this question, one must know the chemical compositions of the gases emitted by volcanoes as well as that of the atmosphere, due to instant dilution effects. It is now generally accepted that the primitive Earth's atmosphere was composed of carbon dioxide, nitrogen and water vapor. The composition of volcanic gases is, however, a subject for considerable variations due to a heterogenous mantle from which the volatiles are released. Recent isotopic analyses of noble gases trapped in volcanic glasses suggest that Hawaiian volcanoes originate from a primordial, undegassed reservoir deep in the Earth's mantle. Therefore, the volatiles emitted by Hawaiian volcanoes could, perhaps, exemplify more accurately the nature of gases emitted by archean volcanoes. The typical composition of the gases emitted by the Kilauea during a one-stage degassing process is: H2O (52.30%), CO2 (30.87%), SO2 (14.59%), CO (1.00%), H2 (0.79%) and H2S (0.16%), among others. A priori it could be inferred that volcanic lightning is advantageous for the synthesis of hydrogen cyanide and formaldehyde, due to the presence of reduced gases within the volcanic ash-gas cloud. However, previous electric discharge experiments have not been done in the presence of significant amounts of water vapor, which could cause an inhibitory effect. Consequently there is a necessity for an experimental evaluation. We are currently studying the effects of spark discharges through a gas mixture composed of H2O CO2, N2, CO and H2 by GC-FTIR-MS. To determine the energy yields of the products formed, we are also measuring

  9. Radiative forcings for 28 potential Archean greenhouse gases

    CERN Document Server

    Byrne, Brendan

    2014-01-01

    Despite reduced insolation in the late Archean, evidence suggests a warm climate which was likely sustained by a stronger greenhouse effect, the so-called Faint Young Sun Problem (FYSP). CO2 and CH4 are generally thought to be the mainstays of this enhanced greenhouse, though many other gases have been proposed. We present high accuracy radiative forcings for CO2, CH4 and 26 other gases, performing the radiative transfer calculations at line-by-line resolution and using HITRAN 2012 line data for background pressures of 0.5, 1, and 2 bar of atmospheric N2. For CO2 to resolve the FYSP alone at 2.8 Gyr BP (80% of present solar luminosity), 0.32 bar is needed with 0.5 bar of atmospheric N2, 0.20 bar with 1 bar of atmospheric N2, or 0.11 bar with 2 bar of atmospheric N2. For CH4, we find that near-infrared absorption is much stronger than previously thought, arising from updates to the HITRAN database. CH4 radiative forcing peaks at 10.3, 9, or 8.3 Wm-2 for background pressures of 0.5, 1 or 2 bar, likely limiting ...

  10. Late Archean Cu-Au-Mo mineralization at Gameleira and Serra Verde, Carajàs Mineral Province, Brazil: constraints from Re-Os molybdenite ages

    Science.gov (United States)

    Marschik, Robert; Mathur, Ryan; Ruiz, Joaquin; Leveille, Richard A.; de Almeida, Antonio-José

    2005-03-01

    New Re-Os molybdenite ages provide constraints on the timing of Late Archean Cu-Au-Mo mineralization in the northern Carajás Mineral Province. Molybdenite from the Gameleira iron oxide Cu-Au-Mo deposit yielded an age of 2,614±14 Ma. This age overlaps within its analytical error with Re-Os ages of molybdenite from the Serra Verde Cu-Au-Mo vein deposit (2,609±13 Ma) and from the nearby small Garimpo Fernando gold mining operation (2,592±13 and 2,602±13 Ma), which is probably related to the latter. The geochronological data imply that the hydrothermal Cu-Au-Mo mineralization in these three deposits was epigenetic and coincides with a regional tectonic regime changing from dextral transtension and clastic sedimentation at 2.7 2.6 Ga to sinistral transpression and inversion at 2.6 Ga. Previously reported stable isotope and microthermometric data are compatible with a magmatic affiliation of the Cu-Au-Mo ores at Gameleira and Serra Verde. A genetic relationship of mineralization may therefore exist with 2.56 2.76 Ga Archean alkaline granitoids or with 2.6 2.7 calc-alkaline to tholeiitic volcanic-arc type magmatism.

  11. Intrinsic Josephson junctions in the iron-based multi-band superconductor (V2Sr4O6)Fe2As2

    OpenAIRE

    Moll, Philip J. W.; Zhu, Xiyu; Cheng, Peng; Wen, Hai-Hu; Batlogg, Bertram

    2014-01-01

    In layered superconductors, Josephson junctions may be formed within the unit cell due to sufficiently low interlayer coupling. These intrinsic Josephson junction (iJJ) systems have attracted considerable interest for their application potential in quantum computing as well as efficient sources of THz radiation, closing the famous "THz gap". So far, iJJ have been demonstrated in single-band, copper-based high-Tc superconductors, mainly in Ba-Sr-Ca-Cu-O. Here we report clear experimental evide...

  12. Mineralogical and geochemical characteristics of the Noamundi-Koira basin iron ore deposits (India)

    Science.gov (United States)

    Mirza, Azimuddin; Alvi, Shabbar Habib; Ilbeyli, Nurdane

    2015-04-01

    India is one of the richest sources of iron ore deposits in the world; and one of them is located in the Noamundi-Koira basin, Singhbhum-Orissa craton. The geological comparative studies of banded iron formation (BIF) and associated iron ores of Noamundi-Koira iron ore deposits, belonging to the iron ore group in eastern India, focus on the study of mineralogy and major elemental compositions along with the geological evaluation of different iron ores. The basement of the Singhbhum-Orissa craton is metasedimentary rocks which can be traced in a broadly elliptical pattern of granitoids, surrounded by metasediments and metavolcanics of Greenstone Belt association. The Singhbhum granitoid is intrusive into these old rocks and to younger, mid Archaean metasediments, including iron formations, schists and metaquartzites and siliciclastics of the Precambrian Iron Ore Group (Saha et al., 1994; Sharma, 1994). The iron ore of Noamundi-Koira can be divided into seven categories (Van Schalkwyk and Beukes 1986). They are massive, hard laminated, soft laminated, martite-goethite, powdery blue dust and lateritic ore. Although it is more or less accepted that the parent rock of iron ore is banded hematite jasper (BHJ), the presence of disseminated martite in BHJ suggests that the magnetite of protore was converted to martite. In the study area, possible genesis of high-grade hematite ore could have occurred in two steps. In the first stage, shallow, meteoric fluids affect primary, unaltered BIF by simultaneously oxidizing magnetite to martite and replacing quartz with hydrous iron oxides. In the second stage of supergene processes, deep burial upgrades the hydrous iron oxides to microplaty hematite. Removal of silica from BIF and successive precipitation of iron resulted in the formation of martite- goethite ore. Soft laminated ores were formed where precipitation of iron was partial or absent. The leached out space remains with time and the interstitial space is generally filled

  13. Geochemical characteristics of gold bearing boninites and banded iron formations from Shimoga greenstone belt, India: Implications for gold genesis and hydrothermal processes in diverse tectonic settings

    Digital Repository Service at National Institute of Oceanography (India)

    Ganguly, S.; Manikyamba, C.; Saha, A.; Lingadevaru, M.; Santosh, M.; Rambabu, S.; Khelen, A.C.; Purushotham, D.; Linga, D.

    added to this mixture and thoroughly shaken for complete homogenization. Care was taken to avoid lumping of flux. The mixture was transferred to a preheated and cooled graphite crucible and kept for fusion in preheated muffle furnace at 1050± 25 °C... for one hour. Themelt obtained after fu- sion was swirled and poured into an iron mould to which a thin oil film D A B SD %RSD 88 0.002 1 3.13 0.345 71 236.975 230 0.029 0.012 11 14.094 12 0.016 0.114 03 28.517 25 0.023 0.079 12 3.187 3 0.013 0.408 86 13...

  14. Archean accretion in the Sao Jose do Campestre massif, Borborema Province, Northeast Brazil

    International Nuclear Information System (INIS)

    Preliminary U-Pb and Sm-Nd geochronological results from the Sao Jose do Campestre (formerly Caldas Brandao) Massif in the Borborema Province of NE Brazil show evidence for three distinct stages of Archean petrogenesis. The first stage occurred at 3.45 Ga and involved reworking of a slightly older, primitive crust. The second stage took place at 3.2 Ga (Mesoarchean) and is market by the generation of juvenile crust, with a large production of trondhemitic rocks. The latest magmatic event occurred about 2.7 Ga (Neo-Archean) and produced alkali-rich magmas. recognition of these different Archean events involving accretion of continental crust into a older cratonic nuclei is an important contribution to the knowledge of the regional tectonic history of the Borborema Province in particular and Gondwana in general. (author)

  15. Geological Sulfur Isotopes Indicate Elevated OCS in the Archean Atmosphere, Solving the Faint Young Sun Paradox

    DEFF Research Database (Denmark)

    Ueno, Yuichiro; Johnson, Matthew Stanley; Danielache, Sebastian Oscar;

    2009-01-01

    Distributions of sulfur isotopes in geological samples would provide a record of atmospheric composition if the mechanism producing the isotope effects could be described quantitatively. We determined the UV absorption spectra of 32SO2, 33SO2, and 34SO2 and use them to interpret the geological re......-rich, reducing Archean atmosphere. The radiative forcing, due to this level of OCS, is able to resolve the faint young sun paradox. Further, the decline of atmospheric OCS may have caused the late Archean glaciation....

  16. Exploring Archean seawater sulfate via triple S isotopes in carbonate associated sulfate.

    Science.gov (United States)

    Paris, G.; Fischer, W. W.; Sessions, A. L.; Adkins, J. F.

    2015-12-01

    Multiple sulfur isotope ratios in Archean sedimentary rocks provide powerful insights into the behavior of the ancient sulfur cycle, the redox state of fluid Earth, and the timing of the rise of atmospheric oxygen [1]. The Archean sulfur isotope record is marked by pronounced mass-independent fractionation (Δ33S≠0)—signatures widely interpreted as the result of SO2 photolysis from "short-wavelength" UV light resulting in a reduced phase carrying positive Δ33S values (ultimately recorded in pyrite) and an oxidized phase carrying negative Δ33S values carried by sulfate [2]. Support for this hypothesis rests on early laboratory experiments and observations of negative Δ33S from barite occurrences in mixed volcanic sedimentary strata in Mesoarchean greenstone terrains. Despite forming the framework for understanding Archean sulfur cycle processes, this hypothesis is still largely untested, notably due to the lack of sulfate minerals in Archean strata. Using a new MC-ICP-MS approach combined with petrography and X-ray spectroscopy we have generated a growing S isotope dataset from CAS extracted from Archean carbonates from a range of sedimentary successions, including: the 2.6 to 2.521 Ga Campbellrand-Malmani carbonate platform (Transvaal Supergroup, South Africa), 2.7 Ga Cheshire Formation (Zimbabwe), and 2.9 Ga Steep Rock Formation (Canada). Importantly, we observe positive δ34S and Δ33S values across a range of different lithologies and depositional environments. These results demonstrate that dissolved sulfate in seawater was characterized by positive Δ33S values—a result that receives additional support from recent laboratory and theoretical experiments [e.g. 4, 5]. [1] Farquhar et al., 2000, Science [2] Farquhar et al., 2001, Journal of Geophysical Research: Planets [3] Paris et al., 2014, Science. [4] Whitehill et al., 2013, Proceedings of the National Academy of Sciences. [5] Claire et al., 2014 Geochimica et Cosmochimica Acta

  17. Iron overdose

    Science.gov (United States)

    Iron is a mineral found in many over-the-counter supplements. Iron overdose occurs when someone takes more than the ... This can be by accident or on purpose. Iron overdose is especially dangerous for children. A severe ...

  18. IRON-TOLERANT CYANOBACTERIA: IMPLICATIONS FOR ASTROBIOLOGY

    Science.gov (United States)

    Brown, Igor I.; Allen, Carlton C.; Mummey, Daniel L.; Sarkisova, Svetlana A.; McKay, David S.

    2006-01-01

    The review is dedicated to the new group of extremophiles - iron tolerant cyanobacteria. The authors have analyzed earlier published articles about the ecology of iron tolerant cyanobacteria and their diversity. It was concluded that contemporary iron depositing hot springs might be considered as relative analogs of Precambrian environment. The authors have concluded that the diversity of iron-tolerant cyanobacteria is understudied. The authors also analyzed published data about the physiological peculiarities of iron tolerant cyanobacteria. They made the conclusion that iron tolerant cyanobacteria may oxidize reduced iron through the photosystem of cyanobacteria. The involvement of both Reaction Centers 1 and 2 is also discussed. The conclusion that iron tolerant protocyanobacteria could be involved in banded iron formations generation is also proposed. The possible mechanism of the transition from an oxygenic photosynthesis to an oxygenic one is also discussed. In the final part of the review the authors consider the possible implications of iron tolerant cyanobacteria for astrobiology.

  19. Abiologic silicon isotope fractionation between aqueous Si and Fe(III)-Si gel in simulated Archean seawater: Implications for Si isotope records in Precambrian sedimentary rocks

    Science.gov (United States)

    Zheng, Xin-Yuan; Beard, Brian L.; Reddy, Thiruchelvi R.; Roden, Eric E.; Johnson, Clark M.

    2016-08-01

    Precambrian Si-rich sedimentary rocks, including cherts and banded iron formations (BIFs), record a >7‰ spread in 30Si/28Si ratios (δ30Si values), yet interpretation of this large variability has been hindered by the paucity of data on Si isotope exchange kinetics and equilibrium fractionation factors in systems that are pertinent to Precambrian marine conditions. Using the three-isotope method and an enriched 29Si tracer, a series of experiments were conducted to constrain Si isotope exchange kinetics and fractionation factors between amorphous Fe(III)-Si gel, a likely precursor to Precambrian jaspers and BIFs, and aqueous Si in artificial Archean seawater under anoxic conditions. Experiments were conducted at room temperature, and in the presence and absence of aqueous Fe(II) (Fe(II)aq). Results of this study demonstrate that Si solubility is significantly lower for Fe-Si gel than that of amorphous Si, indicating that seawater Si concentrations in the Precambrian may have been lower than previous estimates. The experiments reached ∼70-90% Si isotope exchange after a period of 53-126 days, and the highest extents of exchange were obtained where Fe(II)aq was present, suggesting that Fe(II)-Fe(III) electron-transfer and atom-exchange reactions catalyze Si isotope exchange through breakage of Fe-Si bonds. All experiments except one showed little change in the instantaneous solid-aqueous Si isotope fractionation factor with time, allowing extraction of equilibrium Si isotope fractionation factors through extrapolation to 100% isotope exchange. The equilibrium 30Si/28Si fractionation between Fe(III)-Si gel and aqueous Si (Δ30Sigel-aqueous) is -2.30 ± 0.25‰ (2σ) in the absence of Fe(II)aq. In the case where Fe(II)aq was present, which resulted in addition of ∼10% Fe(II) in the final solid, creating a mixed Fe(II)-Fe(III) Si gel, the equilibrium fractionation between Fe(II)-Fe(III)-Si gel and aqueous Si (Δ30Sigel-aqueous) is -3.23 ± 0.37‰ (2

  20. Chemistry of sands from the modern Indus River and the Archean Witwatersrand basin: Implications for the composition of the Archean atmosphere

    International Nuclear Information System (INIS)

    Both the Indus River and the Witwatersrand basin contain sand with grains of detrital uraninite. Because this mineral is easily oxidized, its presence in Archean strata as a detrital particle has been used as evidence for a low-oxygen atmosphere before 2.5 Ga. However, its presence in modern sand from the Indus River system has been used to argue that detrital uraninite does not provide information about the oxygen concentration of Earth's early atmosphere. Petrographic and chemical study of sand from these two sources reveals differences that suggest the modern Indus sand cannot be used as an analog for the Archean Witwatersrand occurrences. The Witwatersrand quartzites are depleted in Ca, Mg, and Na, indicating that the original sand from which they formed had been subjected to intense weathering. The chemical index of alteration (CIA), a commonly used indicator of degree of weathering, yields an average value of about 0.80 for Witwatersrand quartzites, comparable to modern tropical streams such as the Orinoco that drain deeply weathered terrains under tropical conditions (CIA=0.75). In contrast, the CIA for Indus sand is 0.45, indicating virtually no chemical weathering. The significance of Archean quartz-pebble conglomerates is not just that they contain unstable detrital phases like uraninite and pyrite, but that these particles are associated with rocks whose compositions suggest intense weathering. These conglomerates must have been subjected to intense weathering under tropical conditions, either in their source area or at the site of deposition, and the preservation of minerals like uraninite such conditions is indeed strong evidence for a low-oxygen atmosphere

  1. An actualistic perspective into Archean worlds - (cyano-)bacterially induced sedimentary structures in the siliciclastic Nhlazatse Section, 2.9 Ga Pongola Supergroup, South Africa.

    Science.gov (United States)

    Noffke, N; Beukes, N; Bower, D; Hazen, R M; Swift, D J P

    2008-01-01

    Extensive microbial mats colonize sandy tidal flats that form along the coasts of today's Earth. The microbenthos (mainly cyanobacteria) respond to the prevailing physical sediment dynamics by biostabilization, baffling and trapping, as well as binding. This biotic-physical interaction gives rise to characteristic microbially induced sedimentary structures (MISS) that differ greatly from both purely physical structures and from stromatolites. Actualistic studies of the MISS on modern tidal flats have been shown to be the key for understanding equivalent fossil structures that occur in tidal and shelf sandstones of all Earth ages. However, until now the fossil record of Archean MISS has been poor, and relatively few specimens have been found. This paper describes a study location that displays a unique assemblage with a multitude of exceptionally preserved MISS in the 2.9-Ga-old Pongola Supergroup, South Africa. The 'Nhlazatse Section' includes structures such as 'erosional remnants and pockets', 'multidirected ripple marks', 'polygonal oscillation cracks', and 'gas domes'. Optical and geochemical analyses support the biogenicity of microscopic textures such as filamentous laminae or 'orientated grains'. Textures resembling filaments are lined by iron oxide and hydroxides, as well as clay minerals. They contain organic matter, whose isotope composition is consistent with carbon of biological origin. The ancient tidal flats of the Nhlazatse Section record four microbial mat facies that occur in modern tidal settings as well. We distinguish endobenthic and epibenthic microbial mats, including planar, tufted, and spongy subtypes. Each microbial mat facies is characterized by a distinct set of MISS, and relates to a typical tidal zone. The microbial mat structures are preserved in situ, and are consistent with similar features constructed today by benthic cyanobacteria. However, other mat-constructing microorganisms also could have formed the structures in the Archean

  2. Accretion, Trapping and Binding of Sediment in Archean Stromatolites—Morphological Expression of the Antiquity of Life

    Science.gov (United States)

    Altermann, Wladyslaw

    2008-03-01

    This paper reviews and discusses Archean stromatolite occurrences and their modes of growth in the context of sedimentary facies. Modes of sediment accretion and trapping and binding of sedimentary grains, together with the resulting morphology of stromatolites and microbial mats in the Archean are analysed, in order to show existing interaction between the growth patterns, morphology and facies association. Architectural elements of sediment arrangement in Archean stromatolites, together with the dependence of stromatolite distribution and morphology on sedimentary facies changes, clearly argue for a biological origin of stromatolitic lamination preserved in Archean cherts and carbonates. The observed sediment behaviour of laminae accretion and sediment precipitation, trapping and binding cannot be explained by abiogenic carbonate or silica precipitation from saturated solutions. The time-dependent, increasing complexity of stromatolitic structures in the Archean is an additional strong argument for biologic impact on stromatolite formation. Therefore, biogenic stromatolites and microbial mats were undoubtfully present at 3.5 Ga and occupied an increasingly wide range of sedimentary environments during the Archean.

  3. Early Archean sialic crust of the Siberian craton: Its composition and origin of magmatic protoliths

    Science.gov (United States)

    Vovna, G. M.; Mishkin, M. A.; Sakhno, V. G.; Zarubina, N. V.

    2009-12-01

    This study demonstrates that the base of the Archean deep-seated granulite complexes within the Siberian craton consists of a metabasite-enderbite association. The major and trace element distribution patterns revealed that the protoliths of this association are represented by calc-alkaline andesites and dacites, containing several minor sequences of komatiitic-tholeiitic volcanic rocks. The origin of the primary volcanic rocks of the metabasite-enderbite association is inferred on the basis of a model of mantle plume magmatism, which postulates that both andesitic and dacitic melts were derived from the primary basitic crust at the expense of heat generated by ascending mantle plumes. The formation of the protoliths of the Archen metabasite-enderbite association of the Siberian craton began at 3.4 Ga and continued until the late Archean.

  4. Phase separation in iron chalcogenide superconductor Rb0.8+xFe1.6+ySe2 as seen by Raman light scattering and band structure calculations

    Science.gov (United States)

    Pashkevich, Yu.; Gnezdilov, V.; Lemmens, P.; Shevtsova, T.; Gusev, A.; Lamonova, K.; Wulferding, D.; Gnatchenko, S.; Pomjakushina, E.; Conder, K.

    2016-06-01

    We report Raman light scattering in the phase separated superconducting single crystal Rb0.77Fe1.61Se2 with Tc = 32 K over a wide temperature region 3-500 K. The observed phonon lines from the majority vacancy ordered Rb2Fe4Se5 (245) antiferromagnetic phase with TN = 525 K demonstrate modest anomalies in the frequency, intensity and halfwidth at the superconductive phase transition. We identify phonon lines from the minority compressed RbδFe2Se2 (122) conductive phase. The superconducting gap with d x 2 - y 2 symmetry has been detected in our spectra. In the range 0-600 cm-1 we observe a weak but highly polarized B1g-type background which becomes well-structured upon cooling. A possible magnetic or multiorbital origin of this background is discussed. We argue that the phase separation in M0.8+xFe1.6+ySe2 is of pure magnetic origin. It occurs below the Néel temperature when the magnetic moment of iron reaches a critical value. We state that there is a spacer between the majority 245 and minority 122 phases. Using ab initio spin-polarized band structure calculations we demonstrate that the compressed vacancy ordered Rb2Fe4Se5 phase can be conductive and therefore may serve as a protective interface spacer between the purely metallic RbδFe2Se2 phase and the insulating Rb2Fe4Se5 phase providing percolative Josephson-junction like superconductivity all throughout of Rb0.8+xFe1.6+ySe2. Our lattice dynamics calculations show significant differences in the phonon spectra of the conductive and insulating Rb2Fe4Se5 phases.

  5. Two-dimensional measurement of natural radioactivity of some Archean and Proterozoic rocks from South Africa

    OpenAIRE

    Tsuchiya, Noriyoshi/Hareyama, Mihoko

    2001-01-01

    The imaging plate is employed as a radiation sensor for obtaining two-dimensional radiation images of natural radioactivity. We used it to evaluate the autoradiography of several types of Archean and Proterozoic granitoids and ultramafic rocks from South Africa for obtaining the distribution of radiation emitters. The semiquantitative dose of natural radioactivity, represented by PSL value in the imaging plate measuring system (the intensity of photostimulated luminescence per unit area), is ...

  6. Albedo and heat transport in 3-dimensional model simulations of the early Archean climate

    Directory of Open Access Journals (Sweden)

    H. Kienert

    2013-01-01

    Full Text Available At the beginning of the Archean eon (ca. 3.8 billion yr ago, the Earth's climate state was significantly different from today due to the lower solar luminosity, smaller continental fraction, higher rotation rate and, presumably, significantly larger greenhouse gas concentrations. All these aspects play a role in solutions to the "faint young Sun problem" which must explain why the ocean surface was not fully frozen at that time. Here, we present 3-dimensional model simulations of climate states that are consistent with early Archean boundary conditions and have different CO2 concentrations, aiming at an understanding of the fundamental characteristics of the early Archean climate system. We focus on three states: one of them is ice-free, one has the same mean surface air temperature of 288 K as today's Earth and the third one is the coldest stable state in which there is still an area with liquid surface water (i.e. the critical state at the transition to a "snowball Earth". We find a reduction in meridional heat transport compared to today which leads to a steeper latitudinal temperature profile and has atmospheric as well as oceanic contributions. Ocean surface velocities are largely zonal, and the strength of the atmospheric meridional circulation is significantly reduced in all three states. These aspects contribute to the observed relation between global mean temperature and albedo, which we suggest as a parameterisation of the ice-albedo feedback for 1-dimensional model simulations of the early Archean and thus the faint young Sun problem.

  7. Archean to Recent aeolian sand systems and their preserved successions: current understanding and future prospects

    OpenAIRE

    Rodríguez-López, JP; Clemmensen, L; Lancaster, N.; Mountney, NP; Veiga, G

    2014-01-01

    The sedimentary record of aeolian sand systems extends from the Archean to the Quaternary, yet current understanding of aeolian sedimentary processes and product remains limited. Most preserved aeolian successions represent inland sand-sea or dunefield (erg) deposits, whereas coastal systems are primarily known from the Cenozoic. The complexity of aeolian sedimentary processes and facies variability are under-represented and excessively simplified in current facies models, which are not suffi...

  8. Albedo and heat transport in 3-D model simulations of the early Archean climate

    Directory of Open Access Journals (Sweden)

    H. Kienert

    2013-08-01

    Full Text Available At the beginning of the Archean eon (ca. 3.8 billion years ago, the Earth's climate state was significantly different from today due to the lower solar luminosity, smaller continental fraction, higher rotation rate and, presumably, significantly larger greenhouse gas concentrations. All these aspects play a role in solutions to the "faint young Sun paradox" which must explain why the ocean surface was not fully frozen at that time. Here, we present 3-D model simulations of climate states that are consistent with early Archean boundary conditions and have different CO2 concentrations, aiming at an understanding of the fundamental characteristics of the early Archean climate system. In order to do so, we have appropriately modified an intermediate complexity climate model that couples a statistical-dynamical atmosphere model (involving parameterizations of the dynamics to an ocean general circulation model and a thermodynamic-dynamic sea-ice model. We focus on three states: one of them is ice-free, one has the same mean surface air temperature of 288 K as today's Earth and the third one is the coldest stable state in which there is still an area with liquid surface water (i.e. the critical state at the transition to a "snowball Earth". We find a reduction in meridional heat transport compared to today, which leads to a steeper latitudinal temperature profile and has atmospheric as well as oceanic contributions. Ocean surface velocities are largely zonal, and the strength of the atmospheric meridional circulation is significantly reduced in all three states. These aspects contribute to the observed relation between global mean temperature and albedo, which we suggest as a parameterization of the ice-albedo feedback for 1-D model simulations of the early Archean and thus the faint young Sun problem.

  9. Were kinetics of Archean calcium carbonate precipitation related to oxygen concentration?

    Science.gov (United States)

    Sumner, D. Y.; Grotzinger, J. P.

    1996-01-01

    Archean carbonates commonly contain decimetre- to metre-thick beds consisting entirely of fibrous calcite and neomorphosed fibrous aragonite that precipitated in situ on the sea floor. The fact that such thick accumulations of precipitated carbonate are rare in younger marine carbonates suggests an important change in the modes of calcium carbonate precipitation through time. Kinetics of carbonate precipitation depend on the concentration of inhibitors to precipitation that reduce crystallization rates and crystal nuclei formation, leading to kinetic maintenance of supersaturated solutions. Inhibitors also affect carbonate textures by limiting micrite precipitation and promoting growth of older carbonate crystals on the sea floor. Fe2+, a strong calcite-precipitation inhibitor, is thought to have been present at relatively high concentrations in Archean seawater because oxygen concentrations were low. The rise in oxygen concentration at 2.2-1.9 Ga led to the removal of Fe2+ from seawater and resulted in a shift from Archean facies, which commonly include precipitated beds, to Proterozoic facies, which contain more micritic sediment and only rare precipitated beds.

  10. Comparison of Archean and Phanerozoic granulites: Southern India and North American Appalachians

    Science.gov (United States)

    Mcsween, Harry Y., Jr.; Kittleson, Roger C.

    1988-01-01

    Archean granulites at the southern end of the Dharwar craton of India and Phanerozoic granulites in the southern Appalachians of North America share an important characteristic: both show continuous transitions from amphibolite facies rocks to higher grade. This property is highly unusual for granulite terranes, which commonly are bounded by major shears or thrusts. These two terranes thus offer an ideal opportunity to compare petrogenetic models for deep crustal rocks formed in different time periods, which conventional wisdom suggests may have had different thermal profiles. The salient features of the Archean amphibolite-to-granulite transition in southern India have been recently summarized. The observed metamorphic progression reflects increasing temperature and pressure. Conditions for the Phanerozoic amphibolite-to-granulite transition in the southern Appalachians were documented. The following sequence of prograde reactions was observed: kyanite = sillimanite, muscovite = sillimanite + K-feldspar, partial melting of pelites, and hornblende = orthopyroxene + clinopyroxene + garnet. The mineral compositions of low-variance assemblages in mafic and intermediate rocks are almost identical for the two granulite facies assemblages. In light of their different fluid regimes and possible mechanisms for heat flow augmentation, it seems surprising that these Archean and Phanerozoic granulite terranes were apparently metamorphosed under such similar conditions of pressure and temperature. Comparison with other terrains containing continuous amphibolite-to-granulite facies transitions will be necessary before this problem can be addressed.

  11. Gastric Banding

    Science.gov (United States)

    ... gastric banding before deciding to have the procedure. Advertisements for a device or procedure may not include ... feeds Follow FDA on Twitter Follow FDA on Facebook View FDA videos on YouTube View FDA photos ...

  12. Iron Overload

    Science.gov (United States)

    ... drug called an iron chelator to remove excess iron from your body because of transfusion-dependent anemias. Be sure to talk with your doctor about the potential benefits and risks of using these drugs. Previous Article ...

  13. Iron-tolerant Cyanobacteria as a Tool to Study Terrestrial and Extraterrestrial Iron Deposition

    Science.gov (United States)

    Brown, I. I.; Mummey, D.; Cooksey, K. E.; McKay, D. S.

    2005-01-01

    We are investigating biological mechanisms of terrestrial iron deposition as analogs for Martian hematite recently confirmed by. Possible terrestrial analogs include iron oxide hydrothermal deposits, rock varnish, iron-rich laterites, ferricrete soils, moki balls, and banded iron formations (BIFs). With the discovery of recent volcanic activity in the summit craters of five Martian volcanoes, renewed interest in the iron dynamics of terrestrial hydrothermal environments and associated microorganisms is warranted. In this study we describe a new genus and species of CB exhibiting elevated dissolved iron tolerance and the ability to precipitate hematite on the surface of their exopolymeric sheathes.

  14. Nb/Ta variations of mafic volcanics on the Archean-Proterozoic boundary: Implications for the Nb/Ta imbalance

    Institute of Scientific and Technical Information of China (English)

    LIU; Yongsheng; GAO; Shan; WANG; Xuance; HU; Shenghong; WA

    2005-01-01

    The HFSE and REE of the Precambrian mafic volcanics from the North China craton demonstrate obvious A(Archean)-P(Proterozoic) boundary. The Neoarchean mafic vol-canics show weak correlation between HFSE and TiO2. Their superchondritic Nb/Ta ratio (18.8(1.2) could be attributed to partial melting of mantle peridotite in the presence of garnet. Compared with Neoarchean mafic volcanics, the Paleoproterozoic ones have higher HFSE contents and lower Nb/Ta ratio (15.6(2.9). The significantly elevated HFSE and REE contents of Paleoproterozoic mafic volcanics imply metasomatic enrichment of mantle source, in which Ti-rich silicates could be present as suggested by significant positive correlations between TiO2 and HFSE. The global database of Precambrian mafic volcanics shows a similar A-P boundary. 23 Archean mafic volcanic suites yield an average Nb/Ta ratio of 17.8(1.9 higher than or close to the PM value; Proterozoic mafic volcanics from 28 suites yield an average Nb/Ta ratio of 14.7(4.1 deficit could be mainly formed in post-Archean time. Archean mafic volcanics could be one of the geochemical reservoirs complementing the low Nb/Ta of the post-Archean continental crust and DM.

  15. EPR study of thermally treated Archean microbial mats analogues and comparison with Archean cherts: towards a possible marker of oxygenic photosynthesis?

    Science.gov (United States)

    Bourbin, M.; Derenne, S.; Westall, F.; Gourier, D.; Gautret, P.; Rouzaud, J.-N.; Robert, F.

    2012-04-01

    The datation of photosynthesis apparition remains an open question nowadays: did oxygenic photosynthesis appear just before the Great Oxidation Event (GOE) of the atmosphere, 2.3 to 2.4 Gyr ago, or does it originate much earlier? It is therefore of uttermost interest to find markers of oxygenic photosynthesis, applicable to samples of archean age. In order to handle this problem, Microcoleus Chtonoplastes cyanobacteria and Chloroflexus-like non-oxygenic photosynthetic bacteria, were studied using Electron Paramagnetic Resonance (EPR) spectroscopy, a high sensitivity technique for the study of organic radicals in mature geological samples (coals, cherts, meteorites...). M. chtonoplastes and Chloroflexus-like bacteria were sampled in mats from the hypersaline lake "La Salada de Chiprana" (Spain), an analogue to an Archean environment, and were submitted to accelerated ageing through cumulative thermal treatments. For thermal treatment temperatures higher than 620° C, a drastic increase in the EPR linewidth of the oxygenic photosynthetic bacteria (M. chtonoplastes) occurred, as compared with the anoxygenic photosynthetic one (Chloroflexus-like). The EPR study of a thermally treated mixture of the two bacteria evidences that this linewidth increase is driven by catalytic reaction at high temperatures on an element selectively fixed by M. chtonoplastes. Based on comparative EDS analyses, Mg is a potential candidate for this catalytic activity but its precise role and the nature of the reaction are still to be determined. The EPR study of organic radicals in chert rocks of ages ranging from 0.42 to 3.5 Gyr, from various localities and that underwent various metamorphisms, revealed a dispersion of the signal width for the most mature samples. This comparative approach between modern bacterial samples and Precambrian cherts leads to propose the EPR linewidth of mature organic matter in cherts as a potential marker of oxygenic photosynthesis. If confirmed, this marker

  16. New Sm/Nd and U/Pb geochronological constraints of the Archean to neoproterozoic evolution of the Amparo basement complex of the Central Ribeira Belt, Southeastern Brazil

    International Nuclear Information System (INIS)

    The Amparo Basement Complex is a distinctive collage of migmatitic tronjhemitetonalite- granodiorite (TTG) orthogneisses that represents the older basement exposures within the Central Ribeira Belt, a Late Neoproterozoic (ca. 600 Ma) collisional belt in southeastern Brazil. These basement gneisses are overlain by Mesoproterozoic to Neoproterozoic supracrustal sequences, and intruded by Neoproterozoic collisional granitoids. Pioneering Rb/Sr, Pb/Pb and K/Ar geochronological studies of the Amparo Complex, e.g. (Wernick et al., 1981; Wernick and Oliveira, 1986; Arthur, 1988; Tassinari, 1988; Campos Neto, 1991) provided some initial insights into the antiquity and geologic evolution of the complex, but little about the crustal evolution of the constituent gneisses. Furthermore, the susceptibility of these systems to partial isotopic resetting, left some doubt about the timing and true number of geologic events recorded by these polydeformed rocks. Recent Sm/Nd whole rock (Dantas et al., 2000) and new U/Pb single crystal zircon and monazite data obtained from the Amparo Complex, however, now furnish information on the crustal growth history of the basement and provide precise age constraints on the timing of events related to the geologic evolution of the complex. Based on these new data, it appears that the oldest rocks within the complex are polymigmatized tronjhemitic gneisses located near the town of Amparo. The oldest phase of this migmatite yields a U/Pb zircon age of 3,024 +/- 9 Ma. Sm/Nd data from this locale yields a Nd T(DM) model age of 3.28 Ga suggesting that the genesis of this crustal unit involved some input from yet older crust. Data from banded tonalitic gneisses collected ca. 50 km south of Amparo indicate that subsequent Archean crustal growth around the older core occurred around 2.77 Ga (U/Pb zircon age of 2,772 +/- 26 Ma. A Nd T(DM) model age of 3.02 Ga obtained from these tonalites also indicate enrichment from older crustal sources during their

  17. Iron Homeostasis and Nutritional Iron Deficiency123

    OpenAIRE

    Theil, Elizabeth C.

    2011-01-01

    Nonheme food ferritin (FTN) iron minerals, nonheme iron complexes, and heme iron contribute to the balance between food iron absorption and body iron homeostasis. Iron absorption depends on membrane transporter proteins DMT1, PCP/HCP1, ferroportin (FPN), TRF2, and matriptase 2. Mutations in DMT1 and matriptase-2 cause iron deficiency; mutations in FPN, HFE, and TRF2 cause iron excess. Intracellular iron homeostasis depends on coordinated regulation of iron trafficking and storage proteins enc...

  18. The world turns over: Hadean-Archean crust-mantle evolution

    Science.gov (United States)

    Griffin, W. L.; Belousova, E. A.; O'Neill, C.; O'Reilly, Suzanne Y.; Malkovets, V.; Pearson, N. J.; Spetsius, S.; Wilde, S. A.

    2014-02-01

    We integrate an updated worldwide compilation of U/Pb, Hf-isotope and trace-element data on zircon, and Re-Os model ages on sulfides and alloys in mantle-derived rocks and xenocrysts, to examine patterns of crustal evolution and crust-mantle interaction from 4.5 Ga to 2.4 Ga ago. The data suggest that during the period from 4.5 Ga to ca 3.4 Ga, Earth's crust was essentially stagnant and dominantly mafic in composition. Zircon crystallized mainly from intermediate melts, probably generated both by magmatic differentiation and by impact melting. This quiescent state was broken by pulses of juvenile magmatic activity at ca 4.2 Ga, 3.8 Ga and 3.3-3.4 Ga, which may represent mantle overturns or plume episodes. Between these pulses, there is evidence of reworking and resetting of U-Pb ages (by impact?) but no further generation of new juvenile crust. There is no evidence of plate-tectonic activity, as described for the Phanerozoic Earth, before ca 3.4 Ga, and previous modelling studies indicate that the early Earth may have been characterised by an episodic-overturn, or even stagnant-lid, regime. New thermodynamic modelling confirms that an initially hot Earth could have a stagnant lid for ca 300 Ma, and then would experience a series of massive overturns at intervals on the order of 150 Ma until the end of the EoArchean. The subcontinental lithospheric mantle (SCLM) sampled on Earth today did not exist before ca 3.5 Ga. A lull in crustal production around 3.0 Ga coincides with the rapid buildup of a highly depleted, buoyant SCLM, which peaked around 2.7-2.8 Ga; this pattern is consistent with one or more major mantle overturns. The generation of continental crust peaked later in two main pulses at ca 2.75 Ga and 2.5 Ga; the latter episode was larger and had a greater juvenile component. The age/Hf-isotope patterns of the crust generated from 3.0 to 2.4 Ga are similar to those in the internal orogens of the Gondwana supercontinent, and imply the existence of plate

  19. Ferride geochemistry of Swedish precambrian iron ores

    Science.gov (United States)

    Loberg, B. E. H.; Horndahl, A.-K.

    1983-10-01

    Chemical analysis for major and trace elements have been performed on 30 Swedish Precambrian iron ores and on some from Iran and Chile. The Swedish ores consist of apatite iron ores, quartz-banded iron ores, skarn and limestone iron ores from the two main ore districts of Sweden, the Bergslagen and the Norrbotten province. Some Swedish titaniferous iron ores were also included in the investigation. The trace element data show that the Swedish ores can be subdivided into two major groups: 1. orthomagmatic and exhalative, 2. sedimentary. Within group 1 the titaniferous iron ores are distinguished by their high Ti-contents. From the ferride contents of the Kiruna apatite iron ores, the ores are considered to be mobilization products of skarn iron ores from the Norbotten province.

  20. Leucogranites of the Teton Range, Wyoming: A record of Archean collisional orogeny

    Science.gov (United States)

    Frost, Carol D.; Swapp, Susan M.; Frost, B. Ronald; Finley-Blasi, Lee; Fitz-Gerald, D. Braden

    2016-07-01

    Leucogranitic rocks formed by crustal melting are a prominent feature of collisional orogens of all ages. This study describes leucogranitic gneisses associated with an Archean collisional orogeny preserved in the Teton Range of northwestern Wyoming, USA. These leucogneisses formed at 2.68 Ga, and initial Nd isotopic compositions suggest they are derived from relatively juvenile sources. Two distinct groups of leucogneisses, both trondhjemitic, are identified on the basis of field relations, petrology, and geochemistry. The Webb Canyon gneiss forms large, sheet-like bodies of hornblende biotite trondhjemite and granodiorite. This gneiss is silica-rich (SiO2 = 70-80%), strongly ferroan, comparatively low in alumina, and is characterized by high Zr and Y, low Sr, and high REE contents that define "seagull"-shaped REE patterns. The Bitch Creek gneiss forms small sills, dikes, and plutons of biotite trondhjemite. Silica, Zr, Y, and REE are lower and alumina and Sr are higher than in the Webb Canyon gneiss. These differences reflect different melting conditions: the Webb Canyon gneiss formed by dehydration melting in which amphibole and quartz breaks down, accounting for the low alumina, high FeO, high silica content and observed trace element characteristics. The Bitch Creek gneiss formed by H2O-excess melting in which plagioclase breaks down leaving an amphibole-rich restite, producing magmas higher in alumina and Sr and lower in FeO and HREE. Both melt mechanisms are expected in collisional environments: dehydration melting accompanies gravitational collapse and tectonic extension of dramatically thickened crust, and water-excess melting may occur when collision places a relatively cool, hydrous lower plate beneath a hotter upper plate. The Archean leucogranitic gneisses of the Teton Range are calcic trondhjemites and granodiorites whereas younger collisional leucogranites typically are true granites. The difference in leucogranite composition reflects the

  1. Oxidative Weathering of Archean Sulfides: Implications for the Great Oxidation Event

    Science.gov (United States)

    Johnson, A.; Romaniello, S. J.; Reinhard, C.; Garcia-Robledo, E.; Revsbech, N. P.; Canfield, D. E.; Lyons, T. W.; Anbar, A. D.

    2015-12-01

    The first widely accepted evidence for oxidation of Earth's atmosphere and oceans occurs ~2.45 Ga immediately prior to the Great Oxidation Event (GOE). A major line of evidence for this transition includes the abundances and isotopic variations of redox-sensitive transition metals in marine sediments (e.g., Fe, Mo, Re, Cr, and U). It is often assumed that oxidative weathering is required to liberate these redox-sensitive elements from sulfide minerals in the crust, and hence that their presence in early Archean marine sediments signifies that oxidative weathering was stimulated by small and/or transient "whiffs" of O2 in the environment.1 However, studies of crustal sulfide reactivity have not been conducted at O2 concentrations as low as those that would have prevailed when O2 began its rise during the late Archean (estimated at <10-5 present atmospheric O2).2 As a result, it is difficult to quantify O2 concentrations implied by observed trace metal variations. As a first step toward providing more quantitative constraints on late Archean pO2, we conducted laboratory studies of pyrite and molybdenite oxidation kinetics at the nanomolar O2 concentrations that are relevant to late Archean environments. These measurements were made using recently developed, highly sensitive optical O2 sensors to monitor the rates at which the powdered minerals consumed dissolved O2 in a range of pH-buffered solutions.3Our data extend the range of experimental pyrite oxidation rates in the literature by three orders of magnitude from ~10-3 present atmospheric O2 to ~10-6. We find that molybdenite and pyrite oxidation continues to <1 nM O2 (4 x 10-6 present atmospheric O2). This implies that oxidative weathering of sulfides could occur under conditions which preserve MIF S fractionation. Furthermore, our results indicate that the rate law and reaction order of pyrite oxidation kinetics change significantly at nanomolar concentrations of O2 when compared to previous compilations.2 Our

  2. An Archean Geomagnetic Reversal in the Kaap Valley Pluton, South Africa

    Science.gov (United States)

    Layer; Kroner; McWilliams

    1996-08-16

    The Kaap Valley pluton in South Africa is a tonalite intrusion associated with the Archean Barberton Greenstone Belt. Antipodal paleomagnetic directions determined from the central and marginal parts of the pluton record a geomagnetic reversal that occurred as the pluton cooled. The age of the reversal is constrained by an 40Ar/39Ar plateau age from hornblende at 3214 +/- 4 million years, making it the oldest known reversal. The data presented here suggest that Earth has had a reversing, perhaps dipolar, magnetic field since at least 3.2 billion years ago. PMID:8688075

  3. Earth's Archean Impact Record In The ICDP Drilling "Barberton Mountain Land".

    Science.gov (United States)

    Fritz, Jörg; Schmitt, Ralf-Thomas; Reimold, Uwe; Koeberl, Christian; Mc Donald, Ian; Hofmann, Axel; Luais, Beatrice

    2013-04-01

    The marine meta-sedimentary successions in the "Barberton Mountain Land" are formed by Archean volcanic and sedimentary rocks including the oldest known impact ejecta layers on Earth. The chemical signature (high iridium concentrations, chromium isotopic ratios) of some of these up to tens of cm thick Archean spherule layers advocate that these ejecta deposits represent mainly extraterrestrial material [1]. These ejecta layers contain millimetre sized spherules that are larger and accumulated thicker layers compared to any impact ejecta layer known from Phanerozoic sediments, including the global ejecta layer of the Chicxulub impact catering event terminating the Mesozoic era of Earth's history [2]. The Archean spherule layers are interpreted as products of large impacts by 20 to >100 km diameter objects [3, 4]. Identifying traces of mega-impacts in Earth's ancient history could be of relevance for the evolution of atmosphere, biosphere, and parts of the Earth's crust during that time. In addition, recognizing global stratigraphic marker horizons is highly valuable for inter-correlating sedimentary successions between Archean cratons [5]. However estimates regarding size of the impact event and correlations between the different outcrops in the Barberton mountain land are complicated by post depositional alterations of the tectonically deformed sediments [6, 7]. The relatively fresh samples recovered from below the water table during the 2011-2012 ICDP drilling "Barberton Mountain Land" are promising samples to investigate and to discriminate primary and secondary features of these rare rocks. We plan to conduct 1) petrographic, micro-chemical and mineralogical characterization of the impact ejecta layers, 2) bulk chemical analyses of major and trace elements, and 3) LAICP- MS elemental mapping of platinum group element (PGE) distributions. and elemental analyses of moderately siderophile elements. This aims at 1) characterization of the ejecta layers, 2

  4. Calc-alkaline magmatism at the Archean-Proterozoic transition : The caic complex basement (NE Brazil)

    OpenAIRE

    De Souza, Z. S.; Martin, Hervé; Peucat, J. J.; Jardim de Sa, E. F.; De Freitas Macedo, M. H.

    2007-01-01

    The Paleoproterozoic metaplutonic rocks of the Caico Complex Basement (Serid region, NE Brazil) provide important and crucial insights into the petrogenetic processes governing crustal growth and may potentially be a proxy for understanding the ArcheanProterozoic transition. These rocks consist of high-K calc-alkaline diorite to granite, with RbSr, UPb, PbPb and SmNd ages of c. 225215 Ga. They are metaluminous, with high Yb-N, K2O/Na2O and Rb/Sr, low I-Sr ratios, and are large ion lithophile ...

  5. Archean inheritance in zircon from late Paleozoic granites from the Avalon zone of southeastern New England: an African connection

    Science.gov (United States)

    Zartman, R.E.; Don, Hermes O.

    1987-01-01

    In southeastern New England the Narragansett Pier Granite locally intrudes Carboniferous metasedimentary rocks of the Narragansett basin, and yields a monazite UPb Permian emplacement age of 273 ?? 2 Ma. Zircon from the Narragansett Pier Granite contains a minor but detectable amount of an older, inherited component, and shows modern loss of lead. Zircon from the late-stage, aplitic Westerly Granite exhibits a more pronounced lead inheritance -permitting the inherited component to be identified as Late Archean. Such old relict zircon has not been previously recognized in Proterozoic to Paleozoic igneous rocks in New England, and may be restricted to late Paleozoic rocks of the Avalon zone. We suggest that the Archean crustal component reflects an African connection, in which old Archean crust was underplated to the Avalon zone microplate in the late Paleozoic during collision of Gondwanaland with Avalonia. ?? 1987.

  6. Chondritic-like xenon trapped in Archean rocks: A possible signature of the ancient atmosphere

    Science.gov (United States)

    Pujol, Magali; Marty, Bernard; Burgess, Ray

    2011-08-01

    Ancient sedimentary rocks may have retained a record of the past atmospheric composition. We present evidence for the geological preservation of remnants of the Archean atmosphere. Hydrothermal quartz containing fluid inclusions from a core drilled in 3.5 Ga-old terrains at North Pole, (Western Australia), has a Ar-Ar plateau age of 3.0 ± 0.2 Ga. An Archean age is confirmed independently by 130Ba- 130Xe dating of fluid inclusions. Xenon trapped in the present sample and in 3.5 Ga-old barite from the same locality (Pujol et al., 2009; Srinivasan, 1976) presents an isotopic composition intermediate between the atmospheric composition and that of chondritic, or solar, xenon. In contrast, the stable isotopes of neon and krypton are isotopically atmospheric. This observation suggests that the well known but unexplained enrichment of heavy Xe isotopes in the atmosphere relative to cosmochemical (chondritic or solar) end-members was progressive, and not complete ≥ 3 Ga ago. This Xe isotopic fractionation might have taken place during prolongated irradiation of the atmosphere by the ancient Sun.

  7. Moho offsets beneath the Western Ghat and the contact of Archean crusts of Dharwar Craton, India

    Science.gov (United States)

    Saikia, Utpal; Rai, S. S.; Meena, Rishikesh; Prasad, B. N. V.; Borah, Kajaljyoti

    2016-03-01

    We present the Moho depth variation along a 600 km long profile from the west to the east coast of South India covering the passive continental margin, and the Western Ghat escarpment created during India-Madagascar separation at ~ 85 Ma; Archean western and eastern Dharwar Craton, and Proterozoic basin. The image is generated through three different approaches: H - vP/vS stacking, common conversion point (CCP) migration and inversion of teleseismic receiver functions at 38 locations. The Moho depth along the profile varies smoothly between 34 and 41 km, except beneath the Western Ghat and at the contact of east and west Dharwar Craton, where it is offset by up to ~ 8 km. The study suggests (i) the possible differential uplift of the Western Ghat, as a consequence of India-Madagascar separation and the prominent role of deep crustal structure in the location of the escarpment, compared to the surface process and (ii) presence of long-lived steeply dipping fault separating the two distinct Archean crustal blocks indicative of mechanically strong continental lithosphere beneath the Dharwar Craton.

  8. Electron Paramagnetic Resonance Study of a Photosynthetic Microbial Mat and Comparison with Archean Cherts

    Science.gov (United States)

    Bourbin, M.; Derenne, S.; Gourier, D.; Rouzaud, J.-N.; Gautret, P.; Westall, F.

    2012-12-01

    Organic radicals in artificially carbonized biomass dominated by oxygenic and non-oxygenic photosynthetic bacteria, Microcoleus chthonoplastes-like and Chloroflexus-like bacteria respectively, were studied by Electron Paramagnetic Resonance (EPR) spectroscopy. The two bacteria species were sampled in mats from a hypersaline lake. They underwent accelerated ageing by cumulative thermal treatments to induce progressive carbonization of the biological material, mimicking the natural maturation of carbonaceous material of Archean age. For thermal treatments at temperatures higher than 620 °C, a drastic increase in the EPR linewidth is observed in the carbonaceous matter from oxygenic photosynthetic bacteria and not anoxygenic photosynthetic bacteria. This selective EPR linewidth broadening reflects the presence of a catalytic element inducing formation of radical aggregates, without affecting the molecular structure or the microstructure of the organic matter, as shown by Raman spectroscopy and Transmission Electron Microscopy. For comparison, we carried out an EPR study of organic radicals in silicified carbonaceous rocks (cherts) from various localities, of different ages (0.42 to 3.5 Gyr) and having undergone various degrees of metamorphism, i.e. various degrees of natural carbonization. EPR linewidth dispersion for the most primitive samples was quite significant, pointing to a selective dipolar broadening similar to that observed for carbonized bacteria. This surprising result merits further evaluation in the light of its potential use as a marker of past bacterial metabolisms, in particular oxygenic photosynthesis, in Archean cherts.

  9. Oxygen-Dependent Morphogenesis of Modern Clumped Photosynthetic Mats and Implications for the Archean Stromatolite Record

    Directory of Open Access Journals (Sweden)

    Malcolm R. Walter

    2012-10-01

    Full Text Available Some modern filamentous oxygenic photosynthetic bacteria (cyanobacteria form macroscopic tufts, laminated cones and ridges that are very similar to some Archean and Proterozoic stromatolites. However, it remains unclear whether microbes that constructed Archean clumps, tufts, cones and ridges also produced oxygen. Here, we address this question by examining the physiology of cyanobacterial clumps, aggregates ~0.5 mm in diameter that initiate the growth of modern mm- and cm-scale cones. Clumps contain more particulate organic carbon in the form of denser, bowed and bent cyanobacterial filaments, abandoned sheaths and non-cyanobacterial cells relative to the surrounding areas. Increasing concentrations of oxygen in the solution enhance the bending of filaments and the persistence of clumps by reducing the lateral migration of filaments away from clumps. Clumped mats in oxic media also release less glycolate, a soluble photorespiration product, and retain a larger pool of carbon in the mat. Clumping thus benefits filamentous mat builders whose incorporation of inorganic carbon is sensitive to oxygen. The morphogenetic sequence of mm-scale clumps, reticulate ridges and conical stromatolites from the 2.7 Ga Tumbiana Formation likely records similar O2-dependent behaviors, preserving currently the oldest morphological signature of oxygenated environments on Early Earth.

  10. Petrogenesis of basalts from the Archean Matachewan Dike Swarm Superior Province of Canada

    Science.gov (United States)

    Nelson, Dennis O.

    1987-01-01

    The Matachewan Dike swarm of eastern Ontario comprises Archean age basalts that were emplaced in the greenstone, granite-greenstone, and metasedimentary terrains of the Superior Province of Canada. The basalts are Fe-rich tholeiites, characterized by the near ubiquitos presence of large, compositionally uniform, calcic plagioclase. Major and trace element whole-rock compositions, along with microprobe analyses of constituent phases, from a group of dikes from the eastern portion of the province, were evaluated to constrain petrological processes that operated during the formation and evolution of the magmas. Three compositional groupings, were identified within the dikes. One group has compositional characteristics similar to modern abyssal tholeiites and is termed morb-type. A second group, enriched in incompatible elements and light-REE enriched, is referred to as the enriched group. The third more populated group has intermediate characteristics and is termed the main group. The observation of both morb-type and enriched compositions within a single dike strongly argues for the contemporaneous existence of magmas derived through different processes. Mixing calculations suggest that two possibilities exist. The least evolved basalts lie on a mixing line between the morb-type and enriched group, suggesting mixing of magmas derived from heterogeneous mantle. Mixing of magmas derived from a depleted mantle with heterogeneous Archean crust can duplicate certain aspects of the Matachewan dike composition array.

  11. Iron load

    Directory of Open Access Journals (Sweden)

    Filippo Cassarà

    2013-03-01

    Full Text Available Recent research addressed the main role of hepcidin in the regulation of iron metabolism. However, while this mechanism could be relevant in causing iron load in Thalassemia Intermedia and Sickle-Cell Anemia, its role in Thalassemia Major (TM is marginal. This is mainly due to the high impact of transfusional requirement into the severe increase of body iron. Moreover, the damage of iron load may be worsened by infections, as HCV hepatitis, or liver and endocrinological damage. One of the most relevant associations was found between splenectomy and increase of risk for mortality due,probably, to more severe iron load. These issues suggest as morbidity and mortality of this group of patients they do not depend only by our ability in controlling heart damage but even in preventing or treating particular infections and complications. This finding is supported by the impairment of survival curves in patients with complications different from heart damage. However, because, during recent years different direct and indirect methods to detect iron overload in patients affected by secondary hemochromatosis have been implemented, our ability to maintain under control iron load is significantly improved. Anyway, the future in iron load management remains to be able to have an iron load map of our body for targeting chelation and other medical treatment according to the single organ damage.

  12. Archean to Paleoproterozoic polymetamorphic history of the Salma eclogite in Kola Peninsula, Russia

    Science.gov (United States)

    Imayama, Takeshi; Oh, Chang-Whan; Park, Chan-Soo; Yi, Keewook; Jung, Haemyeong

    2015-04-01

    One of the most important questions in the Earth Science is when and how plate tectonics operate in the Precambrian time. The tectonic and thermal evolution of the Precambrian eclogite is significant key for understanding the Precambrian geodynamic mechanisms. Eclogites in Kola Peninsula, Russia are some of the oldest eclogites of the world, but there has been much debate about the timing of eclogite-facies metamorphism: Archean (e.g. Volodichev et al. 2004; Mints et al., 2010) or Paleoproterozoic (e.g. Skublob et al., 2011, 2012). The controversy is mainly because of the lack of zircon dating coupled with the formation of garnet and omphacite. In this study, we present geochronological, petrographic, and geochemical data from the Salma eclogites in the Kola Peninsula, Russia to characterize subduction and collision processes in the Precambrian. Microstructural observations, P-T analyses, zircon inclusion analyses, and U-Pb zircon dating revealed multiple metamorphic stages that the Salma eclogite underwent. The amphibolite facies metamorphic event firstly occurred at 2.73-2.72 Ga during Archean. In the Paleoproterozoic period, the Salma eclogites underwent prograde stage of epidote-amphibolite facies metamorphism. The eclogite facies metamorphic event took place under the P-T condition of 16-18 kbar and 740-770 °C at 1.89-1.88 Ga, with a subsequent granulite facies metamorphism during decompression stage from 18 kbar to 9-12 kbar. Finally, later amphibolite facies metamorphism occurred at 8-10 kbar and 590-610 °C on cooling. The Archean metamorphic zircons that contain inclusions of Grt + Am + Bt + Pl + Qtz + Rt are unzoned grains with dark CL, and they are relatively enriched in HREE. In contrast, the 1.89-1.88 Ga sector or concentric zoned zircons with pale-grey CL include inclusions of Grt + Omp + Ca-Cpx + Am + Bt + Qtz + Rt, and they have the flat pattern of HREE due to the amounts of abundant garnet during the eclogite-facies metamorphism. Whole rock

  13. Iron deficiency

    DEFF Research Database (Denmark)

    Schou, Morten; Bosselmann, Helle; Gaborit, Freja;

    2015-01-01

    BACKGROUND: Both iron deficiency (ID) and cardiovascular biomarkers are associated with a poor outcome in heart failure (HF). The relationship between different cardiovascular biomarkers and ID is unknown, and the true prevalence of ID in an outpatient HF clinic is probably overlooked. OBJECTIVES...... understand iron metabolism in elderly HF patients....

  14. Fractionation products of basaltic komatiite magmas at lower crustal pressures: implications for genesis of silicic magmas in the Archean

    Science.gov (United States)

    Mandler, B. E.; Grove, T. L.

    2015-12-01

    Hypotheses for the origin of crustal silicic magmas include both partial melting of basalts and fractional crystallization of mantle-derived melts[1]. Both are recognized as important processes in modern environments. When it comes to Archean rocks, however, partial melting hypotheses dominate the literature. Tonalite-trondhjemite-granodiorite (TTG)-type silicic magmas, ubiquitous in the Archean, are widely thought to be produced by partial melting of subducted, delaminated or otherwise deeply buried hydrated basalts[2]. The potential for a fractional crystallization origin for TTG-type magmas remains largely unexplored. To rectify this asymmetry in approaches to modern vs. ancient rocks, we have performed experiments at high pressures and temperatures to closely simulate fractional crystallization of a basaltic komatiite magma in the lowermost crust. These represent the first experimental determinations of the fractionation products of komatiite-type magmas at elevated pressures. The aim is to test the possibility of a genetic link between basaltic komatiites and TTGs, which are both magmas found predominantly in Archean terranes and less so in modern environments. We will present the 12-kbar fractionation paths of both Al-depleted and Al-undepleted basaltic komatiite magmas, and discuss their implications for the relative importance of magmatic fractionation vs. partial melting in producing more evolved, silicic magmas in the Archean. [1] Annen et al., J. Petrol., 47, 505-539, 2006. [2] Moyen J-F. & Martin H., Lithos, 148, 312-336, 2012.

  15. Sulfur MIF, Organic Haze, and the Gaia Hypothesis in the Archean

    Science.gov (United States)

    Domagal-Goldman, S.; James, K. F.

    2006-05-01

    The presence of mass-independent fractionation (MIF) of sulfur isotopes in Archean sedimentary rocks provides evidence for a low-O2 atmosphere prior to 2.4 Ga. Recent data suggest that S-MIF vanished transiently between ~3.2 Ga and 2.8 Ga. The absence of S-MIF after 2.4 Ga is commonly attributed to the rise of O2 in the atmosphere, as the presence of free O2 would have oxidized all sulfur species, thereby erasing any MIF created by atmospheric photochemistry. However, if free O2 did not appear in the atmosphere until 2.4 Ga, then why did S-MIF disappear transiently much earlier? Could S-MIF have been eliminated from the rock record without the presence of free atmospheric O2? We used a 1-dimensional photochemical model to demonstrate how this might have happened. Increasing the CH4/CO2 ratio in the model atmosphere results in the formation of organic haze. If the haze was sufficiently thick, it would have blocked out much of the solar UV radiation shortward of 220 nm that dissociates SO2 and SO, and thereby causes MIF. The haze should also have caused anti-greenhouse cooling and may have triggered the (putative) 2.8-Ga glaciations. Speculatively, an increase in CH4 at 3.0 Ga could have been caused by the evolution of methanogens, while a CH4 decrease at 2.7 Ga could correspond to the evolution of cyanobacteria. The presence of an optically thin organic haze between 2.4 and 2.7 Ga may explain the larger S-MIF values seen at this time, as compared to the early Archean. If such an organic haze existed, it could have resulted in a biologically-mediated negative feedback loop that stabilized the Archean climate. This feedback loop would have operated as follows: an increase in the biological CH4 flux would have led to an increase in haze thickness and a stronger anti-greenhouse effect, cooling the surface. The surface cooling would have caused a reduction of methanogen productivity, thus offsetting the original increase in the CH4 flux. Such stabilizing feedbacks

  16. Effect of iron overload and iron deficiency on liver hemojuvelin protein.

    Directory of Open Access Journals (Sweden)

    Jan Krijt

    Full Text Available INTRODUCTION: Hemojuvelin (Hjv is a key component of the signaling cascade that regulates liver hepcidin (Hamp expression. The purpose of this study was to determine Hjv protein levels in mice and rats subjected to iron overload and iron deficiency. METHODS: C57BL/6 mice were injected with iron (200 mg/kg; iron deficiency was induced by feeding of an iron-deficient diet, or by repeated phlebotomies. Erythropoietin (EPO-treated mice were administered recombinant EPO at 50 U/mouse. Wistar rats were injected with iron (1200 mg/kg, or fed an iron-deficient diet. Hjv protein was determined by immunoblotting, liver samples from Hjv-/- mice were used as negative controls. Mouse plasma Hjv content was determined by a commercial ELISA kit. RESULTS: Liver crude membrane fraction from both mice and rats displayed a major Hjv-specific band at 35 kDa, and a weaker band of 20 kDa. In mice, the intensity of these bands was not changed following iron injection, repeated bleeding, low iron diet or EPO administration. No change in liver crude membrane Hjv protein was observed in iron-treated or iron-deficient rats. ELISA assay for mouse plasma Hjv did not show significant difference between Hjv+/+ and Hjv-/- mice. Liver Hamp mRNA, Bmp6 mRNA and Id1 mRNA displayed the expected response to iron overload and iron deficiency. EPO treatment decreased Id1 mRNA, suggesting possible participation of the bone morphogenetic protein pathway in EPO-mediated downregulation of Hamp mRNA. DISCUSSION: Since no differences between Hjv protein levels were found following various experimental manipulations of body iron status, the results indicate that, in vivo, substantial changes in Hamp mRNA can occur without noticeable changes of membrane hemojuvelin content. Therefore, modulation of hemojuvelin protein content apparently does not represent the limiting step in the control of Hamp gene expression.

  17. Controversial Pb-Pb and Sm-Nd isotope results in the early Archean Isua (West Greenland) oxide iron formation

    DEFF Research Database (Denmark)

    Frei, Robert; Rosing, Minik; Stecher, Ole

    1999-01-01

    -dominated layers yield unrealistically high Nd(3800) of +14.8 and +14.4, indicative of Sm/Nd ratios resembling REE fractionated, continental sources. These high Nd(3800), together with radiogenic Sr leached from the magnetite-enriched separates, is ascribed to secondary hydroxyapatite, which predominantly forms as...

  18. Selection of Portable Spectrometers for Planetary Exploration: A Comparison of 532 nm and 785 nm Raman Spectroscopy of Reduced Carbon in Archean Cherts.

    Science.gov (United States)

    Harris, Liam V; Hutchinson, Ian B; Ingley, Richard; Marshall, Craig P; Marshall, Alison Olcott; Edwards, Howell G M

    2015-06-01

    Knowledge and understanding of the martian environment has advanced greatly over the past two decades, beginning with NASA's return to the surface of Mars with the Pathfinder mission and its rover Sojourner in 1997 and continuing today with data being returned by the Curiosity rover. Reduced carbon, however, is yet to be detected on the martian surface, despite its abundance in meteorites originating from the planet. If carbon is detected on Mars, it could be a remnant of extinct life, although an abiotic source is much more likely. If the latter is the case, environmental carbonaceous material would still provide a source of carbon that could be utilized by microbial life for biochemical synthesis and could therefore act as a marker for potential habitats, indicating regions that should be investigated further. For this reason, the detection and characterization of reduced or organic carbon is a top priority for both the ESA/Roscosmos ExoMars rover, currently due for launch in 2018, and for NASA's Mars 2020 mission. Here, we present a Raman spectroscopic study of Archean chert Mars analog samples from the Pilbara Craton, Western Australia. Raman spectra were acquired with a flight-representative 532 nm instrument and a 785 nm instrument with similar operating parameters. Reduced carbon was successfully detected with both instruments; however, its Raman bands were detected more readily with 785 nm excitation, and the corresponding spectra exhibited superior signal-to-noise ratios and reduced background levels. PMID:26060980

  19. Origin of Archean anorthosites - Evidence from the Bad Vermilion Lake anorthosite complex, Ontario

    Science.gov (United States)

    Ashwal, L. D.; Morrison, D. A.; Phinney, W. C.; Wood, J.

    1983-01-01

    Studies of the petrology and geochemistry of the anorthosite complex at Bad Vermillion Lake, Canada, based on 400 samples collected in summer, 1979, are presented. Petrographic, microprobe, X-ray-fluorescence, and instrumental-neutron-activation analyses were performed. Major and trace-element abundances of the anorthositic rocks and surrounding mafic and felsic rocks are reported in tables, chondrite-normalized rare-earth-element patterns are shown, and the anorthositic, intrusive, and metavolcanic formations are characterized in detail. The anothrositic plagioclases are found to have a coarse porphyritic texture and calcic composition (80 normative mol percent An) similar to those of other Archean anorthosite complexes. Chemical similarities indicate that the gabbro and mafic to felsic metavolcanic formations associated with the anorthosite complex may be comagmatic with it, while the absence of ultramafic material and the bulk composition of the comagmatic basalt (about 20 wt percent Al2O3) suggest that much of the original comagmatic material has been separated.

  20. Crustal anisotropy in the Archean Minnesota River Valley Subprovince and its significance

    Science.gov (United States)

    Gebelin, A.; Ferre, E. C.; Teyssier, C.

    2007-12-01

    The origin and evolution of the American continental lithosphere is a key question addressed by EarthScope. The Superior Province formed as an amalgamation of Archean/ Proterozoic terranes that subsequently acted as a stabilizing nucleus. This province is characterized by a strong seismic anisotropy (SWS = 1.3 s) of unknown origin. As suggested for the Archean Kaapvaal Craton (South Africa), this could be attributed (1) to current asthenospheric flow, or (2) to fossil lithospheric anisotropy, or (3) to the role of lithospheric keels on modern asthenospheric flow. The first hypothesis is not favored because SWS data for the Superior Province do not fit global mantle flow models. The second hypothesis would be compatible with obliquity between lithospheric mantle and crustal seismic anisotropies, possibly due to oblique docking. The third hypothesis would require asthenospheric flow to be controlled by lithospheric block geometry. The origin of seismic anisotropy and its spatial variations need to be determined to test these hypotheses. The deployment of USArray in the Superior Province in FY10, along with the prospect of deployment of a Flexible Array and the GeoFrame Superior focus area should provide a wealth of seismic data. Yet, the contribution of the Archean-early Proterozoic continental crust to seismic anisotropy is unknown. This study focusses on the Minnesota River Valley (MRV) Subprovince, part of the Superior Province. The MRV Subprovince consists of four juxtaposed blocks (Benson, Montevideo, Morton and Jeffers) of amphibolite to granulite grade migmatites, tonalites, granodiorites, diorites and pelitic rocks interlayered into each other. These blocks are separated by EW-dipping shear zones broadly parallel to SWS observations. In other parts of the world, the crustal seismic anisotropy is generally considered to be modest (SWS = 0.1-0.2 s), although experiments specifically designed to constrain it are scarce. The MRV represents a 200 km-wide, tilted

  1. Characterizing the Purple Earth: Modeling the globally integrated spectral variability of the Archean Earth

    Energy Technology Data Exchange (ETDEWEB)

    Sanromá, E.; Pallé, E.; López, R.; Montañés-Rodríguez, P. [Instituto de Astrofísica de Canarias (IAC), Vía Láctea s/n E-38200, La Laguna (Spain); Parenteau, M. N. [NASA Ames Research Center, Exobiology Branch, Mountain View, CA 94035 (United States); Kiang, N. Y. [NASA Goddard Institute for Space Studies, New York, NY 10025 (United States); Gutiérrez-Navarro, A. M., E-mail: mesr@iac.es [Department of Microbiology, Faculty of Biology, University of La Laguna, ES-38206 La Laguna (Spain)

    2014-01-01

    Ongoing searches for exoplanetary systems have revealed a wealth of planets with diverse physical properties. Planets even smaller than the Earth have already been detected and the efforts of future missions are aimed at the discovery, and perhaps characterization, of small rocky exoplanets within the habitable zone of their stars. Clearly, what we know about our planet will be our guideline for the characterization of such planets. However, the Earth has been inhabited for at least 3.8 Gyr and its appearance has changed with time. Here, we have studied the Earth during the Archean eon, 3.0 Gyr ago. At that time, one of the more widespread life forms on the planet was purple bacteria. These bacteria are photosynthetic microorganisms and can inhabit both aquatic and terrestrial environments. Here, we use a radiative transfer model to simulate the visible and near-infrared radiation reflected by our planet, taking into account several scenarios regarding the possible distribution of purple bacteria over continents and oceans. We find that purple bacteria have a reflectance spectrum that has a strong reflectivity increase, similar to the red edge of leafy plants, although shifted redward. This feature produces a detectable signal in the disk-averaged spectra of our planet, depending on cloud amount and purple bacteria concentration/distribution. We conclude that by using multi-color photometric observations, it is possible to distinguish between an Archean Earth in which purple bacteria inhabit vast extensions of the planet and a present-day Earth with continents covered by deserts, vegetation, or microbial mats.

  2. Characterizing the Purple Earth: Modeling the globally integrated spectral variability of the Archean Earth

    International Nuclear Information System (INIS)

    Ongoing searches for exoplanetary systems have revealed a wealth of planets with diverse physical properties. Planets even smaller than the Earth have already been detected and the efforts of future missions are aimed at the discovery, and perhaps characterization, of small rocky exoplanets within the habitable zone of their stars. Clearly, what we know about our planet will be our guideline for the characterization of such planets. However, the Earth has been inhabited for at least 3.8 Gyr and its appearance has changed with time. Here, we have studied the Earth during the Archean eon, 3.0 Gyr ago. At that time, one of the more widespread life forms on the planet was purple bacteria. These bacteria are photosynthetic microorganisms and can inhabit both aquatic and terrestrial environments. Here, we use a radiative transfer model to simulate the visible and near-infrared radiation reflected by our planet, taking into account several scenarios regarding the possible distribution of purple bacteria over continents and oceans. We find that purple bacteria have a reflectance spectrum that has a strong reflectivity increase, similar to the red edge of leafy plants, although shifted redward. This feature produces a detectable signal in the disk-averaged spectra of our planet, depending on cloud amount and purple bacteria concentration/distribution. We conclude that by using multi-color photometric observations, it is possible to distinguish between an Archean Earth in which purple bacteria inhabit vast extensions of the planet and a present-day Earth with continents covered by deserts, vegetation, or microbial mats.

  3. Native iron

    DEFF Research Database (Denmark)

    Brooks, Charles Kent

    2015-01-01

    We live in an oxidized world: oxygen makes up 22 percent of the atmosphere and by reacting with organic matter produces most of our energy, including the energy our bodies use to function: breathe, think, move, etc. It has not always been thus. Originally the Earth, in common with most of the Solar...... System, was reduced. The oxidized outer layers of the Earth have formed by two processes. Firstly, water is decomposed to oxygen and hydrogen by solar radiation in the upper parts of the atmosphere, the light hydrogen diffusing to space, leaving oxygen behind. Secondly, plants, over the course of...... situation unique in the Solar System. In such a world, iron metal is unstable and, as we all know, oxidizes to the ferric iron compounds we call 'rust'. If we require iron metal it must be produced at high temperatures by reacting iron ore, usually a mixture of ferrous (Fe2+) and ferric (Fe3+) oxides (Fe2O3...

  4. Isotopic geochronological evidence for the Paleoproterozoic age of gold mineralization in Archean greenstone belts of Karelia, the Baltic Shield

    Science.gov (United States)

    Larionova, Yu. O.; Samsonov, A. V.; Shatagin, K. N.; Nosova, A. A.

    2013-09-01

    The Rb-Sr age of metasomatic rocks from four gold deposits and occurrences localized in Archean granite-greenstone belts of the western, central, and southern Karelian Craton of the Baltic Shield has been determined. At the Pedrolampi deposit in central Karelia, the dated Au-bearing beresite and quartz-carbonate veins are located in the shear zone and replace Mesoarchean (˜2.9 Ga) mafic and felsic metavolcanic rocks of the Koikar-Kobozero greenstone belt. At the Taloveis ore occurrence in the Kostomuksha greenstone belt of western Karelia, the dated beresite replaces Neoarchean (˜2.7 Ga) granitoids and is conjugated with quartz veins in the shear zone. At the Faddeinkelja occurrence of southern Karelia, Aubearing beresite in the large tectonic zone, which transects Archean granite and Paleoproterozoic mafic dikes, has been studied. At the Hatunoja occurrence in the Jalonvaara greenstone belt of southwestern Karelia, the studied quartz veins and related gold mineralization are localized in Archean granitoids. The Rb-Sr isochrons based on whole-rock samples and minerals from ore-bearing and metasomatic wall rocks and veins yielded ˜1.7 Ga for all studied objects. This age is interpreted as the time of development of ore-bearing tectonic zones and ore-forming hydrothermal metasomatic alteration. New isotopic data in combination with the results obtained by our precursors allow us to recognize the Paleoproterozoic stage of gold mineralization in the Karelian Craton. This stage was unrelated to the Archean crust formation in the Karelian Block and is a repercussion of the Paleoproterozoic (2.0-1.7 Ga) crust-forming tectonic cycle, which gave rise to the formation of the Svecofennian and Lapland-Kola foldbelts in the framework of the Karelain Craton. The oreforming capability of Paleoproterozoic tectonics in the Archean complexes of the Karelian Craton was probably not great, and its main role consisted in reworking of the Archean gold mineralization of various

  5. METABOLISM OF IRON STORES

    OpenAIRE

    Saito, Hiroshi

    2014-01-01

    ABSTRACT Remarkable progress was recently achieved in the studies on molecular regulators of iron metabolism. Among the main regulators, storage iron, iron absorption, erythropoiesis and hepcidin interact in keeping iron homeostasis. Diseases with gene-mutations resulting in iron overload, iron deficiency, and local iron deposition have been introduced in relation to the regulators of storage iron metabolism. On the other hand, the research on storage iron metabolism has not advanced since th...

  6. A summary of Rb-Sr isotope studies in the Archean Hopedale Block and the adjacent proterozoic Makkovik subprovince, Labrador

    International Nuclear Information System (INIS)

    Rb-Sr isotope study of thirteen whole-rock suites of Archean and Proterozoic rocks from Hopedale block and Makkovik Subprovince shows that the crustal history began about 3115 Ma ago. We tentatively recognize younger crustal segments that formed 2920 Ma ago, from which Kanairktok intrusives were derived at 2832 +- 178 Ma. In Makkovik Subprovince the Island Harbour granites range in age from 1843 +- 90 to 1794 +- 71 Ma. These ages overlap with the 1847 +-87 Ma age for Kanairktok shear zone mylonites. The Island Harbour granodiorites from inland localities to the southwest are contaminated with Archean rocks in Makkovik Subprovince and their initial 87Sr/86 ratios imply a crustal contribution to their source. In contrast, the Island Harbour granites of Striped Island were derived from a mantle source. The sills of Striped Island are 1635 +- 47 Ma old. An undeformed northeast trending Kikkertavak dolerite dyke from Hopedale block is 1206 +- 120 Ma

  7. Diamonds in an Archean greenstone belt: Diamond suites in unconventional rocks of Wawa, Northern Ontario (Canada)

    Science.gov (United States)

    Kopylova, Maya; Bruce, Loryn; Ryder, John

    2010-05-01

    Diamonds typically are found on Archean cratons entrained by younger Phanerozoic kimberlites. In contrast, Wawa diamonds are hosted in "unconventional", non-kimberlitic rocks that formed contemporaneously with the mafic and sedimentary rocks of the Archean Michipicoten Greenstone Belt (MGB). We studied two diamond suites that occur within the 2.9-2.7 Ga greenschist facies rocks of MGB located in the southwest portion of the Superior Craton (E. Canada). The first diamond suite henceforth referred to as the Wawa breccia diamonds (384 stones), are hosted in the 2618-2744 Ma calc-alkaline lamprophyres and volcaniclastic breccias, contemporaneous with pillow basalts and felsic volcanics of MGB. The second suite, the Wawa conglomerate diamonds (80 crystals), are hosted in the 2697-2700 Ma poorly sorted sedimentary polymictic conglomerate which is interpreted as a proximal alluvial fan debris flow in a fan-delta environment. The majority of the diamonds was found within the matrix of the conglomerate. The diamondiferous breccia occurs 20 km north of the town of Wawa, whereas the conglomerate is found 12 km northeast of Wawa. Diamonds from the 2 occurrences were characterized and described for provenance studies. Both the breccia and conglomerate diamonds show similar crystal habits, with the predominance of octahedral single crystals and ~ 10% of cubes. The conglomerate diamonds are significantly less resorbed (no resorbtion in 43% of the stones) than the breccia diamonds (8% non-resorbed stones). In both suites, only 21-24% show high degrees of resorption. The majority of crystals in both suites are colourless, with some yellow, brown and grey stones. Conglomerate diamonds had a wider variety of colours that were not seen in the breccia diamonds, including green and pink. The breccia diamonds contain 0-740 ppm N and show two modes of N aggregation at 0-30 and 60-95%. Among the breccia diamonds, Type IaA stones comprise 17%, whereas IaAB stones make up 49% of the

  8. Origin of Archean Chromitites in the Nuggihalli Schist Belt, Dharwar Craton (India)

    Science.gov (United States)

    Mukherjee, R.; Mondal, S. K.; Rosing, M. T.; Frei, R.

    2009-12-01

    Layered ultramafic-mafic rocks with chromitite bodies occur as sill-like intrusions within the Archean greenstone sequences of the Nuggihalli belt, Western Dharwar Craton. The 3.1Ga chromitite-bearing ultramafic-mafic rocks occur as dismembered en echelon, lenticular units that are conformable within the metasedimentary rocks, and surrounded by the tonalite-trondhjemite-granodiorite suite. The chromitite bodies are hosted within intensely deformed serpentinite, and associated with gabbro. The chromitite bodies have high length/width ratio (60-500 m/15 m) and occur in the form of pods and elongated lenses. Detailed electron microprobe study reveals high Cr/(Cr+Al)=0.85-0.86 and moderate Mg/(Mg+Fe2+)=0.38-0.58 of the primary chromite from the massive chromitite. Interstitial and included olivine and pyroxene grains within massive chromitite, exhibit very high Fo content (Fo96-98) and Mg-numbers (94-99) respectively. Chromite grains exhibit intense compositional variability due to subsolidus re-equilibration and low temperature hydrothermal alteration processes such as in the altered massive chromitite (70% chromite), serpentinite (2% chromite) and silicate-rich chromitite (45% chromite). In these associations, chromite grains are compositionally zoned and commonly altered to ferritchromit (rarely magnetite) along the rim and fractures. The primary chromite compositions are used to compute the parent melt that is characterised by low Al2O3 (8.38-10.63 wt%), moderate to high TiO2 (0.94-1.58 wt%) and FeO/MgO ratios of 0.46-0.92 wt%. The parent melt calculations indicate derivation from a high-Mg komatiitic basalt, and matches with the compositions of komatiitic rocks reported from the greenstone terrain. Parent melts are produced by high degrees of partial melting of a depleted source mantle evident from the refractory compositions of chromite, olivine and pyroxene. Tectonic discrimination diagrams indicate a supra-subduction zone setting (SSZ) for the Archean

  9. Multiple sulfur-isotope signatures in Archean sulfates and their implications for the chemistry and dynamics of the early atmosphere

    Science.gov (United States)

    Muller, Élodie; Philippot, Pascal; Rollion-Bard, Claire; Cartigny, Pierre

    2016-07-01

    Sulfur isotopic anomalies (∆33S and ∆36S) have been used to trace the redox evolution of the Precambrian atmosphere and to document the photochemistry and transport properties of the modern atmosphere. Recently, it was shown that modern sulfate aerosols formed in an oxidizing atmosphere can display important isotopic anomalies, thus questioning the significance of Archean sulfate deposits. Here, we performed in situ 4S-isotope measurements of 3.2- and 3.5-billion-year (Ga)-old sulfates. This in situ approach allows us to investigate the diversity of Archean sulfate texture and mineralogy with unprecedented resolution and from then on to deconvolute the ocean and atmosphere Archean sulfur cycle. A striking feature of our data is a bimodal distribution of δ34S values at ˜+5‰ and +9‰, which is matched by modern sulfate aerosols. The peak at +5‰ represents barite of different ages and host-rock lithology showing a wide range of ∆33S between ‑1.77‰ and +0.24‰. These barites are interpreted as primary volcanic emissions formed by SO2 photochemical processes with variable contribution of carbonyl sulfide (OCS) shielding in an evolving volcanic plume. The δ34S peak at +9‰ is associated with non–33S-anomalous barites displaying negative ∆36S values, which are best interpreted as volcanic sulfate aerosols formed from OCS photolysis. Our findings confirm the occurrence of a volcanic photochemical pathway specific to the early reduced atmosphere but identify variability within the Archean sulfate isotope record that suggests persistence throughout Earth history of photochemical reactions characteristic of the present-day stratosphere.

  10. Multiple sulfur-isotope signatures in Archean sulfates and their implications for the chemistry and dynamics of the early atmosphere.

    Science.gov (United States)

    Muller, Élodie; Philippot, Pascal; Rollion-Bard, Claire; Cartigny, Pierre

    2016-07-01

    Sulfur isotopic anomalies (∆(33)S and ∆(36)S) have been used to trace the redox evolution of the Precambrian atmosphere and to document the photochemistry and transport properties of the modern atmosphere. Recently, it was shown that modern sulfate aerosols formed in an oxidizing atmosphere can display important isotopic anomalies, thus questioning the significance of Archean sulfate deposits. Here, we performed in situ 4S-isotope measurements of 3.2- and 3.5-billion-year (Ga)-old sulfates. This in situ approach allows us to investigate the diversity of Archean sulfate texture and mineralogy with unprecedented resolution and from then on to deconvolute the ocean and atmosphere Archean sulfur cycle. A striking feature of our data is a bimodal distribution of δ(34)S values at ∼+5‰ and +9‰, which is matched by modern sulfate aerosols. The peak at +5‰ represents barite of different ages and host-rock lithology showing a wide range of ∆(33)S between -1.77‰ and +0.24‰. These barites are interpreted as primary volcanic emissions formed by SO2 photochemical processes with variable contribution of carbonyl sulfide (OCS) shielding in an evolving volcanic plume. The δ(34)S peak at +9‰ is associated with non-(33)S-anomalous barites displaying negative ∆(36)S values, which are best interpreted as volcanic sulfate aerosols formed from OCS photolysis. Our findings confirm the occurrence of a volcanic photochemical pathway specific to the early reduced atmosphere but identify variability within the Archean sulfate isotope record that suggests persistence throughout Earth history of photochemical reactions characteristic of the present-day stratosphere. PMID:27330111

  11. Quasiparticles in calcium doped yttrium-iron garnets

    International Nuclear Information System (INIS)

    In yttrium-iron garnets an electrical charge is carried by quasiparticles based on compensating holes which move either at oxygen or iron ions of the tetragonal sublattice. The quasiparticles can also get localized because of their coupling to optical phonons on the iron sites. A multi-band model of holes coupled to phonons is applied to find additional energy levels in the gap between the lower of the narrow 3d bands and the wide 2p band, whose occurrence plays a crucial role in the conductivity mechanism. The density of states is considerably modified by the interaction between the holes and local distortion of the lattice. (author)

  12. Eclogite-High-Pressure Granulite Belt in Northern Edge of the Archean North China Craton

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    The discovery of retrograded eclogites and high-pressure basic granulites in the joining region of Hebei-Shanxi-Inner Mongolia (HSIM) abandon the old thoughts that Archean granulites in the North China craton are of middle or low pressure facies and promote the reconsideration of Early Precambrian cratonization tectonic process, and reveal the geological fact that the scale, rigid behavior and geological structure of Archean cratonic blocks have strong similarities to the present fundamental plate tectonics, which suggest new tectonic mechanism to understand the early continental evolution of the North China craton. (1) The retrograded eclogites and high-pressure granulites constitute a ENE-NE-striking structure-rock zone termed as the Sanggan structural belt. (2) The retrograded eclogites are closely associated with high-pressure granulites. We can call this belt a transitional eclogite-granulite facies metamorphic belt. Petrographically three metamorphic stages, at least, in the retrograded eclogite can be distinguished. ① The main mineral assemblage is composed of garnet+clinopyroxene+quartz+rutile. The mineral inclusions in garnet are fine-grained quartz, rutile and small inclusions of fine-grained second stage mineral aggregate. This aggregate consists of hypersthene+albite, and has the typical texture of small hypersthene core surrounded by albite micro-grained grains. ② The second mineral assemblage is represented by corona of garnet and symplectite of clinopyroxene. The corona of garnet is composed of hypersthene+plagioclase+clinopyroxene+a minor amount of quartz and magnetite. The symplectite of clinopyroxene is composed of hypersthene + albite+clinopyroxene. The secondary mineral assemblage along boundaries between quartz and garnet (or clinopyroxene) is fine-grained aggregate of hypersthene and clinopyroxene. ③ The third retrograded metamorphic minerals are mainly amphiboles replacing pyroxenes and plagioclases replacing garnets. The estimated

  13. How to draw down CO2 from severe Hadean to habitable Archean?

    Science.gov (United States)

    Zhelezinskaia, I.; Ding, S.; Mulyukova, E.; Martirosyan, N.; Johnson, A.; West, J. D.; Kolesnichenko, M.; Saloor, N.; Moucha, R.

    2015-12-01

    It has been hypothesized that as the magma ocean crystallized in the Hadean, volatiles such as CO2 and H2O were released to the surface culminating with the formation of a liquid ocean by about 4.4 Ga [1] and hot CO2-rich atmosphere [2]. The resulting late Hadean atmospheric pCO2 may have been as high as 100 bars [3] with corresponding surface temperatures ~500 K [4]. Geological evidence suggests that by the early-to-mid Archean, atmospheric pCO2 became less than 1 bar [5]. However, the mechanisms responsible for the great amount of CO2 drawdown in a relatively short period of time remain enigmatic. To identify these possible mechanisms, we have developed a box model during the CIDER 2015 Summer Program that takes into account geological constraints on basalt alteration [6, 7] and possible rate of new oceanic crust formation [8] for the Archean. Our model integrates geodynamic and geochemical approaches of interaction between the Hadean atmosphere, hydrosphere, oceanic crust, and mantle to drawdown CO2. Our primary assumption for the Hadean is the absence of the continental crust and thus continental weathering. Therefore in the model we present, the level of CO2 in the atmosphere is regulated by the formation of oceanic crust (OC), rate of the interaction between the ocean and OC, and carbonate subduction/CO2 degassing. Preliminary results suggest that it would take about 1 billion years for the atmospheric CO2 to decrease to 1 bar if the production of oceanic crust was 10 times more than today and the pH of the ocean was less than 7, making the basalt alteration more efficient. However, there is evidence that some continental crust began to form as early as 4.4 Ga [9] and therefore the role of continental weathering and its rate of CO2 drawdown will need to be further explored. References: [1] Wilde et al. (2001). Nature 409(6817), 175-178. [2] Walker (1985). Origins of Life and Evolution of the Biosphere 16(2), 117-127. [3] Elkins-Tanton (2008). EPSL, 271, 181

  14. Iron and Your Child

    Science.gov (United States)

    ... Story" 5 Things to Know About Zika & Pregnancy Iron and Your Child KidsHealth > For Parents > Iron and ... enough iron in their daily diets. How Much Iron Do Kids Need? Kids require different amounts of ...

  15. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... have enough iron in your body. Low iron levels usually are due to blood loss, poor diet, ... iron supplements and multivitamins to improve her iron levels. Susan also made changes to her diet, such ...

  16. Iron homeostasis and nutritional iron deficiency.

    Science.gov (United States)

    Theil, Elizabeth C

    2011-04-01

    Nonheme food ferritin (FTN) iron minerals, nonheme iron complexes, and heme iron contribute to the balance between food iron absorption and body iron homeostasis. Iron absorption depends on membrane transporter proteins DMT1, PCP/HCP1, ferroportin (FPN), TRF2, and matriptase 2. Mutations in DMT1 and matriptase-2 cause iron deficiency; mutations in FPN, HFE, and TRF2 cause iron excess. Intracellular iron homeostasis depends on coordinated regulation of iron trafficking and storage proteins encoded in iron responsive element (IRE)-mRNA. The noncoding IRE-mRNA structures bind protein repressors, IRP1 or 2, during iron deficiency. Integration of the IRE-RNA in translation regulators (near the cap) or turnover elements (after the coding region) increases iron uptake (DMT1/TRF1) or decreases iron storage/efflux (FTN/FPN) when IRP binds. An antioxidant response element in FTN DNA binds Bach1, a heme-sensitive transcription factor that coordinates expression among antioxidant response proteins like FTN, thioredoxin reductase, and quinone reductase. FTN, an antioxidant because Fe(2+) and O(2) (reactive oxygen species generators) are consumed to make iron mineral, is also a nutritional iron concentrate that is an efficiently absorbed, nonheme source of iron from whole legumes. FTN protein cages contain thousands of mineralized iron atoms and enter cells by receptor-mediated endocytosis, an absorption mechanism distinct from transport of nonheme iron salts (ferrous sulfate), iron chelators (ferric-EDTA), or heme. Recognition of 2 nutritional nonheme iron sources, small and large (FTN), will aid the solution of iron deficiency, a major public health problem, and the development of new policies on iron nutrition. PMID:21346101

  17. Neutron spectrometry measurements in iron

    International Nuclear Information System (INIS)

    A compact structure was prepared for use in making measurements of neutron penetration in iron which could serve as reference data and as a check for computer codes. About 30 iron plates were put together giving a useful overall length of 130 cm. At various depths along the central axis of the iron block, measurements were made with liquid scintillator spectrometers and proton recoil proportional counters. The energy band explored was between 14 KeV and 10 MeV. Here we report the original spectra of the impulses and the neutron spectra found by the NE213 code based on the differential method and by unfolding with the SPEC4 code for liquid scintillation counters and proton recoil spectrometers, respectively. 12 figs., 60 tabs., 6 refs

  18. Petrogenesis of silicic magmatism related to the ˜ 2.44 Ga rifting of Archean crust in Koillismaa, eastern Finland

    Science.gov (United States)

    Lauri, L. S.; Rämö, O. T.; Huhma, H.; Mänttäri, I.; Räsänen, J.

    2006-01-01

    Early Paleoproterozoic extension in the Archean craton of the Fennoscandian shield led to the emplacement of several 2.44 Ga layered gabbroic intrusive complexes in northern Finland and adjacent Russia. Closely associated with them are felsic rocks of similar age: (1) the Sirniö Group volcanic rocks on top of the Koillismaa layered complex; (2) a quartz alkali feldspar syenite at Kynsijärvi near the Koillismaa complex; and (3) an aluminous A-type granite at Nuorunen near the Oulanka layered complex. In the Koillismaa area, the ruptured Archean crust consists of ortho- and paragneisses that were intruded and migmatized by somewhat younger granites. U-Pb zircon data indicate that the gneisses are at least ˜2.8 Ga old and that the granites were crystallized at ˜2.7 Ga. Both rock types show a common monazite age of 2695 Ma that registers the peak of granulite facies metamorphism and, possibly, the intrusion of the granites. The local Neoarchean crust has ɛNd(at 2440 Ma) values between - 5 and - 8.5. The mafic rocks of the Koillismaa complex show initial ɛNd(at 2440 Ma) values around - 1.5 and those of the Oulanka complex range from - 2.1 to 0. The ɛNd value (- 4.8) and TDM model age (2.9-3.0 Ga) of the Kynsijärvi quartz alkali feldspar syenite are within the limits of the evolution path of the local Archean crust. The corresponding values for the Nuorunen granite are - 2.0 and 2.76 Ga and are thus closer to those of the mafic rocks. The volcanic rocks of the Sirniö Group show more scatter with initial ɛNd(at 2440 Ma) values of - 1.1 to - 5.3; the lowest ɛNd values probably reflect later disturbance-magmatic values cluster around - 2. Major and trace element modeling shows that fractional crystallization of the Koillismaa complex parental magma or partial melting of the Archean crust cannot account for the ˜ 2.44 Ga silicic rocks of Koillismaa. The geochemical and Nd isotope characteristics of the volcanic rocks and the Kynsijärvi quartz alkali feldspar

  19. Iron and iron derived radicals

    International Nuclear Information System (INIS)

    We have discussed some reactions of iron and iron-derived oxygen radicals that may be important in the production or treatment of tissue injury. Our conclusions challenge, to some extent, the usual lines of thought in this field of research. Insofar as they are born out by subsequent developments, the lessons they teach are two: Think fast! Think small! In other words, think of the many fast reactions that can rapidly alter the production and fate of highly reactive intermediates, and when considering the impact of competitive reactions on such species, think how they affect the microenvironment (on the molecular scale) ''seen'' by each reactive molecule. 21 refs., 3 figs., 1 tab

  20. Archean Earth Atmosphere Fractal Haze Aggregates: Light Scattering Calculations and the Faint Young Sun Paradox

    Science.gov (United States)

    Boness, D. A.; Terrell-Martinez, B.

    2010-12-01

    As part of an ongoing undergraduate research project of light scattering calculations involving fractal carbonaceous soot aggregates relevant to current anthropogenic and natural sources in Earth's atmosphere, we have read with interest a recent paper [E.T. Wolf and O.B Toon,Science 328, 1266 (2010)] claiming that the Faint Young Sun paradox discussed four decades ago by Carl Sagan and others can be resolved without invoking heavy CO2 concentrations as a greenhouse gas warming the early Earth enough to sustain liquid water and hence allow the origin of life. Wolf and Toon report that a Titan-like Archean Earth haze, with a fractal haze aggregate nature due to nitrogen-methane photochemistry at high altitudes, should block enough UV light to protect the warming greenhouse gas NH3 while allowing enough visible light to reach the surface of the Earth. To test this hypothesis, we have employed a rigorous T-Matrix arbitrary-particle light scattering technique, to avoid the simplifications inherent in Mie-sphere scattering, on haze fractal aggregates at UV and visible wavelenths of incident light. We generate these model aggregates using diffusion-limited cluster aggregation (DLCA) algorithms, which much more closely fit actual haze fractal aggregates than do diffusion-limited aggregation (DLA) algorithms.

  1. Characterizing the purple Earth: Modelling the globally-integrated spectral variability of the Archean Earth

    CERN Document Server

    Sanromá, E; Parenteau, M N; Kiang, N Y; Gutiérrez-Navarro, A M; López, R; Montañés-Rodríguez, P

    2013-01-01

    The ongoing searches for exoplanetary systems have revealed a wealth of planets with diverse physical properties. Planets even smaller than the Earth have already been detected, and the efforts of future missions are placed on the discovery, and perhaps characterization, of small rocky exoplanets within the habitable zone of their stars. Clearly what we know about our planet will be our guideline for the characterization of such planets. But the Earth has been inhabited for at least 3.8 Ga, and its appearance has changed with time. Here, we have studied the Earth during the Archean eon, 3.0 Ga ago. At that time one of the more widespread life forms on the planet were purple bacteria. These bacteria are photosynthetic microorganisms and can inhabit both aquatic and terrestrial environments. Here, we used a radiative transfer model to simulate the visible and near-IR radiation reflected by our planet, taking into account several scenarios regarding the possible distribution of purple bacteria over continents an...

  2. Analysis of shear banding in twelve materials

    Science.gov (United States)

    Batra, R. C.; Kim, C. H.

    The problem of the initiation and growth of shear bands in 12 different materials, namely, OFHC copper, Cartridge brass, Nickel 200, Armco IF (interstitial free) iron, Carpenter electric iron, 1006 steel, 2024-T351 aluminum, 7039 aluminum, low alloy steel, S-7 tool steel, Tungsten alloy, and Depleted Uranium (DU -0.75 Ti) is studied with the objectives of finding out when a shear band initiates, and upon what parameters does the band width depend. The nonlinear coupled partial differential equations governing the overall simple shearing deformations of a thermally softening viscoplastic block are analyzed. It is assumed that the thermomechanical response of these materials can be adequately represented by the Johnson-Cook law, and the only inhomogeneity present in the block is the variation in its thickness. The effect of the defect size on the initiation and subsequent growth of the band is also studied. It is found that, for each one of these 12 materials, the deformation has become nonhomogeneous by the time the maximum shear stress occurs. Also the band width, computed when the shear stress has dropped to 85 percent of its peak value, does not correlate well with the thermal conductivity of the material. The band begins to grow rapidly when the shear stress has dropped to 90 percent of its maximum value.

  3. The evaluation of iron deficiency and anemia in male blood donors with other related factors

    Directory of Open Access Journals (Sweden)

    Yousefinejad Vahid

    2010-01-01

    Full Text Available Aims and Background: Iron deficiency is one of the most common nutritional disorders worldwide and blood donation may cause iron depletion. Limited studies with large sample size have been done on male donors. The aim of this study is to determine the prevalence of iron deficiency and iron deficiency anemia among male donors in the Kurdistan Organization of Blood Transfusion in Iran. Materials and Methods: This was a cross-sectional study. Sample size was 1184 blood donors selected by systematic random sampling. Hemoglobin, serum iron, serum ferritin, total iron banding capacity (TIBC and transferin saturation were measured in donors. Iron depletion, lack of iron stores, iron deficiency, iron deficiency anemia and anemia were evaluated among them. Data was analyzed with SPSS software and X΂, one-way ANOVA, and LSD test. Results: Iron deficiency, anemia, iron deficiency anemia, iron depletion and lack of iron resources were seen in 2.3, 4.08, 2.14, 22.76 and 4.66 percent respectively. There was a significant relationship of iron deficiency and iron deficiency anemia with instances of donation and interval from last donation (P < 0.05. A significant relationship was seen between iron deficiency and iron deficiency anemia among blood donors with more than ten times blood donation (P < 0.05. Conclusions: This study showed regular male donors require especial attention. Therefore, serum ferritin is recommended as a more adequate index to use for iron deficiency screening and planning purposes for iron supplementation among them.

  4. Pb, Sr and Nd isotopic compositions of a suite of Late Archean, igneous rocks, eastern Beartooth Mountains: Implications for crust-mantle evolution

    International Nuclear Information System (INIS)

    A series of compositionally diverse, Late Archean rocks (2.74-2.79 Ga old) from the eastern Beartooth Mountains, Montana and Wyoming, U.S.A., have the same initial Pb, Sr, and Nd isotopic ratios. Lead and Sr initial ratios are higher and Nd initial ratios lower than would be expected for rocks derived from model mantle sources and strongly indicate the involvement of an older crustal reservoir in the genesis of these rocks. Crustal contamination during emplacement can be ruled out for a variety of reasons. Instead a model involving subduction of continental detritus and contamination of the overlying mantle as is often proposed for modern subduction environments is preferred. This contaminated mantle would have all the isotopic characteristics of mantle enriched by internal mantle metasomatism but would require no long-term growth or changes in parent to daughter element ratios. This contaminated mantle would make a good source for some of the Cenozoic mafic volcanics of the Columbia River, Snake River Plain, and Yellowstone volcanic fields that are proposed to come from ancient, enriched lithospheric mantle. The isotopic characteristics of the 2.70 Ga old Stillwater Complex are a perfect match for the proposed contaminated mantle which provides an alternative to crustal contamination during emplacement. The Pb isotopic characteristics of the Late Archean rocks of the eastern Beartooth Mountains are similar to those of other Late Archean rocks of the Wyoming Province and suggest that Early Archean, upper crustal rocks were common in this terrane. The isotopic signatures of Late Archean rocks in the Wyoming Province and distinctive from those of other Archean cratons in North America which are dominated by a MORB-like, Archean mantle source (Superior Province) and/or a long-term depleted crustal source (Greenland). (orig.)

  5. The F'derik-Zouerate iron district: Mesoarchean and Paleoproterozoic iron formation of the Tiris Complex, Islamic Republic of Mauritania

    Science.gov (United States)

    Taylor, Cliff D.; Finn, Carol A.; Anderson, Eric D.; Bradley, Dwight C.; Joud, Mohamed; Taleb Mohamed, Ahmed; Horton, John D.; Johnson, Craig A.

    2016-01-01

    High-grade hematitic iron ores (of HIF, containing 60-65 wt%Fe) have been mined in Mauritania since 1952 from Superior-type iron deposits of the F'derik-Zouerate district.  Depletion of the high-grade ores in recent years has resulted in new exploration projects focused on lower-grade magnetite ores occurring in Algoma-type banded iron formation (of BIF, containing ca. 35 wt% Fe).  Mauritania is the seventeenth largest iron producer in the world and currently has about 1.1 Gt of crude iron ore reserves. 

  6. Human iron transporters

    OpenAIRE

    Garrick, Michael D.

    2010-01-01

    Human iron transporters manage iron carefully because tissues need iron for critical functions, but too much iron increases the risk of reactive oxygen species. Iron acquisition occurs in the duodenum via divalent metal transporter (DMT1) and ferroportin. Iron trafficking depends largely on the transferrin cycle. Nevertheless, non-digestive tissues have a variety of other iron transporters that may render DMT1 modestly redundant, and DMT1 levels exceed those needed for the just-mentioned task...

  7. Iron bioavailability from commercially available iron supplements

    OpenAIRE

    Christides, Tatiana; Wray, David; McBride, Richard; Fairweather, Rose; Sharp, Paul

    2015-01-01

    Purpose Iron deficiency anaemia (IDA) is a global public health problem. Treatment with the standard of care ferrous iron salts may be poorly tolerated, leading to non-compliance and ineffective correction of IDA. Employing supplements with higher bioavailability might permit lower doses of iron to be used with fewer side effects, thus improving treatment efficacy. Here, we compared the iron bioavailability of ferrous sulphate tablets with alternative commercial iron products, including th...

  8. Alteration mineral mapping for iron prospecting using ETM+ data, Tonkolili iron field, northern Sierra Leone

    Science.gov (United States)

    Mansaray, Lamin R.; Liu, Lei; Zhou, Jun; Ma, Zhimin

    2013-10-01

    The Tonkolili iron field in northern Sierra Leone has the largest known iron ore deposit in Africa. It occurs in a greenstone belt in an Achaean granitic basement. This study focused mainly on mapping areas with iron-oxide and hydroxyl bearing minerals, and identifying potential areas for haematite mineralization and banded iron formations (BIFs) in Tonkolili. The predominant mineral assemblage at the surface (laterite duricrust) of this iron field is haematitegoethite- limonite ±magnetite. The mineralization occurs in quartzitic banded ironstones, layered amphibolites, granites, schists and hornblendites. In this study, Crosta techniques were applied on Enhanced Thematic Mapper (ETM+) data to enhance areas with alteration minerals and target potential areas of haematite and BIF units in the Tonkolili iron field. Synthetic analysis shows that alteration zones mapped herein are consistent with the already discovered magnetite BIFs in Tonkolili. Based on the overlaps of the simplified geological map and the remote sensing-based alteration mineral maps obtained in this study, three new haematite prospects were inferred within, and one new haematite prospect was inferred outside the tenement boundary of the Tonkolili exploration license. As the primary iron mineral in Tonkolili is magnetite, the study concludes that, these haematite prospects could also be underlain by magnetite BIFs. This study also concludes that, the application of Crosta techniques on ETM+ data is effective not only in mapping iron-oxide and hydroxyl alterations but can also provide a basis for inferring areas of potential iron resources in Algoma-type banded iron formations (BIFs), such as those in the Tonkolili field.

  9. Feasibility of infrared analysis of iron in zircon

    International Nuclear Information System (INIS)

    A feasibility study has concluded that quantitative infrared analysis can be employed to determine the concentration of iron in zircon. The spectral transmission curves have shown that the iron absorption band is located at 1.15 microns. These curves also revealed a second absorption band at 1.49 microns. The source of this second peak is not known; but it exhibits some features which suggest its dependance on natural α-recoil damage. 23 references, 14 figures, 2 tables

  10. Geological Setting of Diamond Drilling for the Archean Biosphere Drilling Project, Pilbara Craton, Western Australia

    Science.gov (United States)

    Hickman, A.

    2004-12-01

    The Archean Biosphere Drilling Project (ABDP) is a collaborative international research project conducting systematic (bio)geochemical investigations to improve our understanding of the biosphere of the early Earth. The Pilbara Craton of Western Australia, which includes exceptionally well preserved 3.52 to 2.70 Ga sedimentary sequences, was selected for an innovative sampling program commencing in 2003. To avoid near-surface alteration and contamination effects, sampling was by diamond drilling to depths of between 150 and 300 m, and was located at sites where the target lithologies were least deformed and had lowest metamorphic grade (below 300°C). The first of five successful drilling sites (Jasper Deposit) targeted red, white and black chert in the 3.46 Ga Marble Bar Chert Member. This chert marks the top of a thick mafic-felsic volcanic cycle, the third of four such cycles formed by mantle plumes between 3.52 and 3.43 Ga. The geological setting was a volcanic plateau founded on 3.72 to 3.60 Ga sialic crust (isotopic evidence). The second hole (Salgash) was sited on the basal section of the fourth cycle, and sampled sulfidic (Cu-Zn-Fe), carbon-rich shale and sandstone units separated by flows of peridotite. The third hole (Eastern Creek) was sited on the margin of a moderately deep-water rift basin, the 2.95 to 2.91 Ga Mosquito Creek Basin. This is dominated by turbidites, but the sandstones and carbon-rich shales intersected at the drilling site were deposited in shallower water. The fourth and fifth holes, located 300 km apart, sampled 2.77 to 2.76 Ga continental formations of the Fortescue Group; both holes included black shales.

  11. Iron and iron derived radicals

    Energy Technology Data Exchange (ETDEWEB)

    Borg, D.C.; Schaich, K.M.

    1987-04-01

    We have discussed some reactions of iron and iron-derived oxygen radicals that may be important in the production or treatment of tissue injury. Our conclusions challenge, to some extent, the usual lines of thought in this field of research. Insofar as they are born out by subsequent developments, the lessons they teach are two: Think fastexclamation Think smallexclamation In other words, think of the many fast reactions that can rapidly alter the production and fate of highly reactive intermediates, and when considering the impact of competitive reactions on such species, think how they affect the microenvironment (on the molecular scale) ''seen'' by each reactive molecule. 21 refs., 3 figs., 1 tab.

  12. Block and shear-zone architecture of the Minnesota River Valley subprovince: Implications for late Archean accretionary tectonics

    Science.gov (United States)

    Southwick, D.L.; Chandler, V.W.

    1996-01-01

    The Minnesota River Valley subprovince of the Superior Province is an Archean gneiss terrane composed internally of four crustal blocks bounded by three zones of east-northeast-trending linear geophysical anomalies. Two of the block-bounding zones are verified regional-scale shears. The geological nature of the third boundary has not been established. Potential-field geophysical models portray the boundary zones as moderately north-dipping surfaces or thin slabs similar in strike and dip to the Morris fault segment of the Great Lakes tectonic zone at the north margin of the subprovince. The central two blocks of the subprovince (Morton and Montevideo) are predominantly high-grade quartzofeldspathic gneiss, some as old as 3.6 Ga, and late-tectonic granite. The northern and southern blocks (Benson and Jeffers, respectively) are judged to contain less gneiss than the central blocks and a larger diversity of syntectonic and late-tectonic plutons. A belt of moderately metamorphosed mafic and ultramafic rocks having some attributes of a dismembered ophiolite is partly within the boundary zone between the Morton and Montevideo blocks. This and the other block boundaries are interpreted as late Archean structures that were reactivated in the Early Proterozoic. The Minnesota River Valley subprovince is interpreted as a late accretionary addition to the Superior Province. Because it was continental crust, it was not subductible when it impinged on the convergent southern margin of the Superior Craton in late Archean time, and it may have accommodated to convergent-margin stresses by dividing into blocks and shear zones capable of independent movement.

  13. Mantle derivation of Archean amphibole-bearing granitoid and associated mafic rocks: evidence from the southern Superior Province, Canada

    Science.gov (United States)

    Sutcliffe, Richard H.; Smith, Alan R.; Doherty, William; Barnett, Robert L.

    1990-08-01

    Amphibole-bearing, Late Archean (2.73 2.68 Ga) granitoids of the southern Superior Province are examined to constrain processes of crustal development. The investigated plutons, which range from tonalite and diorite to monzodiorite, monzonite, and syenite, share textural, mineralogical and geochemical attributes suggesting a common origin as juvenile magmas. Despite variation in modal mineralogy, the plutons are geochemically characterized by normative quartz, high Al2O3 (> 15 wt%), Na-rich fractionation trends (mol Na2O/K2O >2), low to moderate Rb (generallyenclaves and igneous layers and as intrusive units which exhibit textures indicative of contemporaneous mafic and felsic magmatism. Mafic mineral assemblages include: hornblende + biotite in tonalites; augite + biotite ± orthopyroxene ± pargasitic hornblende or hornblende+biotite in dioritic to monzodioritic rocks; and aegirine-augite ± silicic edenite ± biotite in syenite to alkali granite. Discrete plagioclase and microcline grains are present in most of the suites, however, some of the syenitic rocks are hypersolvus granitoids and contain only perthite. Mafic-ultramafic rocks have REE and Y contents indicative of their formation as amphibole-rich cumulates from the associated granitoids. Some cumulate rocks have skeletal amphibole with XMg(Mg/(Mg+ Fe2+)) indicative of crystallization from more primitive liquids than the host granitoids. Geochemical variation in the granitoid suites is compatible with fractionation of amphibole together with subordinate plagioclase and, in some cases, mixing of fractionated and primitive magmas. Mafic to ultramafic units with magnesium-rich cumulus phases and primitive granitoids (mol MgO/ (MgO+0.9 FeOTOTAL) from 0.60 to 0.70 and CT >150 ppm) are comagmatic with the evolved granitoids and indicate that the suites are mantle-derived. Isotopic studies of Archean monzodioritic rocks have shown LREE enrichment and initial 143Nd/144Nd ratios indicating derivation from mantle

  14. Mineral inclusions in diamonds from the Kelsey Lake Mine, Colorado, USA: Depleted Archean mantle beneath the Proterozoic Yavapai province

    Science.gov (United States)

    Schulze, Daniel J.; Coopersmith, Howard G.; Harte, Ben; Pizzolato, Lori-Ann

    2008-03-01

    Thirty-four silicate and oxide inclusions large enough for in situ WDS electron microprobe analysis were exposed by grinding/polishing of 19 diamonds from the Kelsey Lake Mine in the Colorado-Wyoming State Line Kimberlite district. Eighteen olivines, seven Cr-pyropes, four Mg-chromites, and one orthopyroxene in 15 stones belong to the peridotite (P) suite and three garnets and one omphacite in three stones belong to the eclogite (E) suite. The fact that this suite is dominated by the peridotite population is in stark contrast to the other diamond suites studied in the State Line district (Sloan, George Creek), which are overwhelmingly eclogitic. Kelsey Lake olivine inclusions are magnesian (17 of 18 grains in 9 stones are in the range Fo 92.7-93.1), typical of harzburgitic P-suite stones worldwide, but unlike the more Fe-rich (lherzolitic) Sloan olivine suite. Mg-chromites (wt% MgO = 12.8-13.8; wt% Cr 2O 3 = 61.4-66.6) are in the lower MgO range of diamond inclusion chromites worldwide. Seven harzburgitic Cr-pyropes in five stones have moderately low calcium contents (wt% CaO = 3.3-4.3) but are very Cr-rich (wt% Cr 2O 3 = 9.7-16.7). A few stones have been analyzed by SIMS for carbon isotope composition and nitrogen abundance. One peridotitic stone is apparently homogeneous in carbon isotope composition (δ 13C PDB = -6.2‰) but with variable nitrogen abundance (1296-2550 ppm). Carbon isotopes in eclogitic stones range from "normal" for the upper mantle (δ 13C PDB = -5.5‰) to somewhat low (δ 13C PDB = -10.2‰), with little internal variation in individual stones (maximum difference is 3.6‰). Nitrogen contents (2-779 ppm) are lower than in the peridotitic stone, and are lower in cores than in rims. As, worldwide, harzburgite-suite diamonds have been shown to have formed in Archean time, we suggest that the Kelsey Lake diamond population was derived from a block of Archean lithosphere that, at the time of kimberlite eruption, existed beneath the Proterozoic

  15. Tectonic environment of Precambrian quartz-pebble conglomerate uranium deposits formed along the southern margin of the Archean Shield in North America

    International Nuclear Information System (INIS)

    Uraniferous Early Proterozoic conglomerates have been discovered at several localities in Canada and the United States near the southeastern edge of the Archean Superior and Wyoming Provinces. Sedimentary successions that contain the uraniferous conglomerates apparently were deposited in fault-bounded troughs or basins and on faulted coastal plains that formed on or near the margin of an Archean craton or cratons. The Early Proterozoic history of this cratonal margin, called the Proterozoic-Archean boundary zone, is characterized by approximately synchronous periods of (1) extensional tectonics with rifting, volcanism, and subsidence; (2) intrusion of mafic dikes and sills; (3) carbonate shelf development; (4) eugeoclinal sedimentation and volcanism; and (5) orogeny. (author). 47 refs, 4 figs, 4 tabs

  16. Iron Sucrose Injection

    Science.gov (United States)

    ... is in a class of medications called iron replacement products. It works by replenishing iron stores so ... ferumoxytol (Feraheme), iron dextran (Dexferrum, Infed, Proferdex), or sodium ferric gluconate (Ferrlecit); any other medications; or any ...

  17. Iron Dextran Injection

    Science.gov (United States)

    ... is in a class of medications called iron replacement products. It works by replenishing iron stores so ... carboxymaltose (Injectafer), ferumoxytol (Feraheme), iron sucrose (Venofer), or sodium ferric gluconate (Ferrlecit);any other medications; or any ...

  18. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... refers to a condition in which your blood has a lower than normal number of red blood ... iron, your body starts using the iron it has stored. Soon, the stored iron gets used up. ...

  19. Taking iron supplements

    Science.gov (United States)

    ... medlineplus.gov/ency/article/007478.htm Taking iron supplements To use the sharing features on this page, ... levels. You may also need to take iron supplements as well to rebuild iron stores in your ...

  20. Iron deficiency anemia

    Science.gov (United States)

    ... Iron-rich foods include: Chicken and turkey Dried lentils, peas, and beans Fish Meats (liver is the ... and egg yolks are high sources of iron. Flour, bread, and some cereals are fortified with iron. ...

  1. Pharmacology of Iron Transport

    OpenAIRE

    Byrne, Shaina L.; Krishnamurthy, Divya; Wessling-Resnick, Marianne

    2012-01-01

    Elucidating the molecular basis for the regulation of iron uptake, storage, and distribution is necessary to understand iron homeostasis. Pharmacological tools are emerging to identify and distinguish among different iron transport pathways. Stimulatory or inhibitory small molecules with effects on iron uptake can help characterize the mechanistic elements of iron transport and the roles of the transporters involved in these processes. In particular, iron chelators can serve as potential phar...

  2. Genetics Home Reference: iron-refractory iron deficiency anemia

    Science.gov (United States)

    ... refractory iron deficiency anemia iron-refractory iron deficiency anemia Enable Javascript to view the expand/collapse boxes. ... All Close All Description Iron-refractory iron deficiency anemia is one of many types of anemia , which ...

  3. Gutzwiller theory of band magnetism in LaOFeAs

    International Nuclear Information System (INIS)

    For the iron pnictide LaOFeAs we investigate multi-band Hubbard models which are assumed to capture the relevant physics. In our calculations, we employ the Gutzwiller variational theory which is a genuine many particle approach. We will present results both on the paramagnetic and antiferromagnetic phases of our model systems. These results show that a five band-model is not adequate to capture the relevant physics in LaOFeAs. However, our results for the eight band-model which includes the arsenic 4p bands reproduce the experimental data, especially the small magnetic moment, for a broad parameter regime.

  4. Iron and stony-iron meteorites

    DEFF Research Database (Denmark)

    Benedix, Gretchen K.; Haack, Henning; McCoy, T.J.

    2014-01-01

    Without iron and stony-iron meteorites, our chances of ever sampling the deep interior of a differentiated planetary object would be next to nil. Although we live on a planet with a very substantial core, we will never be able to sample it. Fortunately, asteroid collisions provide us with a rich...... sampling of the deep interiors of differentiated asteroids. Iron and stony-iron meteorites are fragments of a large number of asteroids that underwent significant geological processing in the early solar system. Parent bodies of iron and some stony-iron meteorites completed a geological evolution similar...... to that continuing on Earth – although on much smaller length- and timescales – with melting of the metal and silicates; differentiation into core, mantle, and crust; and probably extensive volcanism. Iron and stony-iron meteorites are our only available analogues to materials found in the deep...

  5. Geochemistry and source of iron-formation from Guanhaes group, Guanhaes district, Minas Gerais, Brazil

    International Nuclear Information System (INIS)

    The Guanhaes district is underlain by metavolcano-sedimentary rocks of the Guanhaes Group, emplaced over an older Archean basement and intruded by granitic bodies. The Guanhaes Group is composed of pelitic, mafic and ultramafic schists at the base; silicate and carbonate facies iron-formation, calcarious schists, calcsilicates rocks and quartzites at the median portion and para-gneisses (meta-graywacks) at the top. Geochemistry of iron-formation suggest a hydrothermal affinity comparable to the hydrothermal sediments flanking East Pacific Rise. Paragenetic studies indicates that the rocks were submited to two metamorphic processes: one of regional character (high-amphibolite facies) and one of themal character (pyroxene-hornfels facies). Chemical analysis, as X-ray and optic spectrography, atomic absorption and plasma spectrography are presented. (author)

  6. Role of Plumes and Plates in the Construction and Preservation of Hadean-Archean Continental Nuclei

    Science.gov (United States)

    Mueller, P. A.; Mogk, D. W.; Henry, D.; Wooden, J.

    2014-12-01

    Crust and lithosphere formed in modern island arc and plume environments exhibit strong contrasts in both structure and composition compared to present day continents. The limited inventory of Hadean and Eoarchean material available for study, the possibility that the preserved record is biased, and the lack of continental crust on other terrestrial planets, make it difficult to determine the nature of the first continental nuclei. Nonetheless, certain first order similarities in preserved Archean continental crust suggest that these continental nuclei (microcontinents or protocontinents) allow us to establish limits on processes of early crustal genesis Based on geochemical (elemental and isotopic), geochronologic, and petrologic data from Paleo- to Mesoarchean rocks preserved in the northern Wyoming Province, we propose a multi-stage evolution of a continental nucleus that reflects a secular change from plume- to plate-related processes. 1) 4.0-4.1 Ga: mafic and ultramafic magmas formed a section of thickened lithosphere over a zone of upwelling primitive mantle; 2) 3.6-4.0 Ga: continuity of magmatism recorded in detrital zircons does not favor growth by episodic subduction; Hf isotopes in zircon suggest extensive crustal recycling with some juvenile additions; 3) 3.6-3.2 Ga: a major crust-forming interval with infusion of new crust derived from more depleted sources, including a hydrous, garnet-bearing source; 4) intervening granulite facies metamorphism of supracrustal rocks and orthogneisses, clockwise PTt path, coupled with ductile deformation (~ 750-800oC and 6-8 Kbar); 5) ~2.8-2-9 Ga: a second period of major magmatism resulted from subduction and a volcanic arc was built on the older 3.2-3.5 Ga crust. This geochemical record indicates that the earliest crust formed through diapiric upwelling and anhydrous melting of primitive mantle in a plume setting, followed by recycling of this crust with only limited juvenile additions in the Paleoarchean; in the

  7. Formation of the Archean crust of the ancient Vodlozero domain (Baltic shield)

    Science.gov (United States)

    Arestova, N. A.; Chekulaev, V. P.; Lobach-Zhuchenko, S. B.; Kucherovskii, G. A.

    2015-03-01

    The available geological, petrological, and isotopic data on Archean rocks of the Baltic shield are used to analyze the formation of the crust of the ancient Vodlozero domain. This made it possible to reveal the succession of endogenic processes in different parts of the domain and correlate them between each other. Several stages of magmatic processes reflecting changes in magma-generation environments are definable in the crust formation. The earliest stages of magmatism (3.24 and 3.13-3.15 Ga) are mostly represented by rocks of the tonalite-trondhjemite-granodiorite association. The next stage of endogenic activity (3020-2900 Ma) was marked by the formation of volcanics of the komatiite-basalt and andesite-dacite associations constituting greenstone belts in marginal parts of the Vodlozero domain and basic dikes accompanied by layered pyroxenite-norite-diorite intrusion in its central part. These basic bodies crossing earlier tonalities were formed in extension settings related to the formation of the mantle plume, which is confirmed by the rock composition. This stage culminated in the formation of trondhjemites at margins of greenstone structure. The next stage of endogenic activity commenced at 2890-2840 Ma by the emplacement of high-magnesian gabbro and diorite dikes in the western margin of the domain, where they cross rocks of the tonalitetrondhjemite association. This stage was marked by the formation of intermediate-acid subvolcanic bodies and dikes as well as basite intrusions including the layered and differentiated Semch intrusion, the largest one in the Vodlozero domain. The stage culminated at approximately 2850 Ma in the emplacement of tonalities of the limited distribution being represented by the Shilos massif in the north of the domain and Shal'skii massif on the eastern shore of Lake Onega. The important stage in the geological history of the Vodlozero domain is the formation of the intracratonic Matkalakhta greenstone belt at approximately 2

  8. Archean and proterozoic continental crust in South America: Main building events

    International Nuclear Information System (INIS)

    Available geochronological data reveal that the first building blocks of the South American continental crust were set up in the early Paleoarchean, ca. 3.4-3.5 Ga ago, although the presence of components as old as 3.7 Ga is indicated by Nd TDM model ages. The oldest rocks so far recognized are exposed in northeast Brazil and Uruguay. In the Sao Jose do Campestre block, Rio Grande do Norte, 3.45 Ga old tonalite, migmatized and intruded by granitoids between 3.3 and 3.0 Ga, is part of the basement to the Borborema Province (Dantas et al. 1998). In Bahia 3.42 Ga old tonalitic grey gneisses of Sete Voltas, Boa Vista, and Mairi form the basement of the Gaviao block, within the core of the Sao Francisco Craton (Nutman and Cordani, 1993, Martin et al., 1997). The Paleoarchean TTG suites as well as greenstone remnants of unknown age were involved in crust accretion events between 3.1 and 3.3 Ga ago (Teixeira et al. 2000 and references therein), which are also recorded in Campo Belo and Uaua (Teixeira et al., 1998, Oliveira et al., 1999), as attested by TTG intrusions and the ca. 3.1 Ga Pium-hi greenstone belt of W Minas Gerais (Machado and Schrank 1989). Microcontinents then formed were involved in deformation, metamorphism, and migmatization around 2.8-3.0 Ga ago, probably during amalgamation events. Widespread granite-greenstone associations in the Quadrilatero Ferrifero and other areas represent new crust built during the very important Neoarchean Rio das Velhas cycle, ca. 2.7-2.8 Ga ago (Machado and Carneiro 1992, Machado et al. 1992). Layered mafic-ultramafic and granite intrusions ca. 2.5-2.7 Ga old are recorded all over the Sao Francisco Craton, including the high-grade terrain of southern Bahia, formed during the late Archean Jequie Cycle (Teixeira et al. 2000 and references therein). Similar intrusions are recorded in many basement areas within Neoproterozoic fold belts (au)

  9. Band structure of semiconductors

    CERN Document Server

    Tsidilkovski, I M

    2013-01-01

    Band Structure of Semiconductors provides a review of the theoretical and experimental methods of investigating band structure and an analysis of the results of the developments in this field. The book presents the problems, methods, and applications in the study of band structure. Topics on the computational methods of band structure; band structures of important semiconducting materials; behavior of an electron in a perturbed periodic field; effective masses and g-factors for the most commonly encountered band structures; and the treatment of cyclotron resonance, Shubnikov-de Haas oscillatio

  10. Rare-earth element modelling of Archean meta-igneous and igneous rocks, Lake Despair area, northwestern Ontario

    International Nuclear Information System (INIS)

    Archean felsic to intermediate meta-igneous rocks from the Lake Despair area, northwestern Ontario, have highly-fractionated REE patterns (Lasub(N)/Lusub(N) 10-100). They are rich in LREEs (ca. 40-100 x chondrites) and poor in HREEs (ca, 1-7 x chondrites). Simple models for the REEs suggest eclogite-quartz eclogite parents for these rocks. The Footprint Gneiss, the major rock type of the Rainy Lake Batholith, was formed by limited melting (ca. 10%) of a quartz eclogite under hydrous conditions. The putative parent may have been transformed basalt derived from primitive, LREE-rich Archean mantle. The mafic metavolcanic rocks have a REE chemistry similar to modern island-arc or mid-ocean ridge tholeiites. Felsic metavolcanic rocks, and granodiorite from the Northwest Bay complex, have REE abundances compatible with an origin by partial melting (ca. 10%), under hydrous conditions, of quartz eclogite of tholeiitic REE chemistry. The Jackfish Lake plutonic complex, which is composed mostly of diorite, has REE abundances that are best described by 10% melting of eclogite (with tholeiitic-REE chemistry) under hydrous conditions. A small portion of the diorite magma was subsequently fractionated, largely by the early crystallization of amphibole, and formed more leucocratic rock types (e.g. leucodiorite and granodiorite). The REE data were obtained by neutron activation analysis. (Auth.)

  11. Iron from Zealandic bog iron ore -

    DEFF Research Database (Denmark)

    Lyngstrøm, Henriette Syrach

    2011-01-01

    og geologiske materiale, metallurgiske analyser og eksperimentel arkæologiske forsøg - konturerne af en jernproduktion med udgangspunkt i den sjællandske myremalm. The frequent application by archaeologists of Werner Christensen’s distribution map for the occurrence of bog iron ore in Denmark (1966...... contours are sketched of iron production based on bog iron ore from Zealand....

  12. Liver iron transport

    Institute of Scientific and Technical Information of China (English)

    Ross M Graham; Anita CG Chua; Carly E Herbison; John K Olynyk; Debbie Trinder

    2007-01-01

    The liver plays a central role in iron metabolism. It is the major storage site for iron and also expresses a complex range of molecules which are involved in iron transport and regulation of iron homeostasis. An increasing number of genes associated with hepatic iron transport or regulation have been identified. These include transferrin receptors (TFR1 and 2), a ferrireductase (STEAP3), the transporters divalent metal transporter-1 (DMT1) and ferroportin (FPN) as well as the haemochromatosis protein, HFE and haemojuvelin (HJV),which are signalling molecules. Many of these genes also participate in iron regulatory pathways which focus on the hepatic peptide hepcidin. However, we are still only beginning to understand the complex interactions between liver iron transport and iron homeostasis. This review outlines our current knowledge of molecules of iron metabolism and their roles in iron transport and regulation of iron homeostasis.

  13. Petrogenesis of the Paleoproterozoic rapakivi A-type granites of the Archean Carajás metallogenic province, Brazil

    Science.gov (United States)

    Dall'Agnol, Roberto; Teixeira, Nilson P.; Rämö, O. Tapani; Moura, Candido A. V.; Macambira, Moacir J. B.; de Oliveira, Davis C.

    2005-03-01

    Three Paleoproterozoic A-type rapakivi granite suites (Jamon, Serra dos Carajás, and Velho Guilherme) are found in the Carajás metallogenic province, eastern Amazonian craton. Liquidus temperatures in the 900-870 °C range characterize the Jamon suite, those for Serra dos Carajás and Velho Guilherme are somewhat lower. Pressures of emplacement decrease from Jamon (3.2±0.7 kbar) through Serra dos Carajás (2.0±1.0 kbar) to Velho Guilherme (1.0±0.5 kbar). Oxidizing conditions (NNO+0.5) characterized the crystallization of the Jamon magma, the Velho Guilherme magmas were reducing (marginally below FMQ), and the Serra dos Carajás magmas were intermediate between the two in this respect. The three granite suites have Archean T DM model ages and strongly negative ɛNd values (-12 to -8 at 1880 Ma), and they were derived from Archean crust. The Jamon granite suite may have been derived from a quartz dioritic source, and the Velho Guilherme granites from K-feldspar-bearing granitoid rocks with some sedimentary input. The Serra dos Carajás granites either had a somewhat more mafic source than Velho Guilherme or were derived by a larger degree of melting. Underplating of mafic magma was probably the heat source for the melting. The petrological and geochemical characteristics of the Carajás granite suites imply considerable compositional variation in the Archean of the eastern Amazonian craton. The oxidized Jamon suite granites are similar to the Mesoproterozoic magnetite-series granites of Laurentia, and they were derived from Archean igneous sources that were more oxidized than the sources of the Fennoscandian rapakivi granites. The Serra dos Carajás and Velho Guilherme granites approach the classic reduced rapakivi series of Fennoscandia and Laurentia. No counterparts of the Mesoproterozoic two-mica granites of Laurentia have been found, however. Following the model of Hoffman [Hoffman, P., 1989. Speculations on Laurentia's first gigayear (2.0 to 1.0 Ga

  14. Photonic band gap materials

    International Nuclear Information System (INIS)

    An overview of the theoretical and experimental efforts in obtaining a photonic band gap, a frequency band in three-dimensional dielectric structures in which electromagnetic waves are forbidden, is presented

  15. Band parameters of phosphorene

    DEFF Research Database (Denmark)

    Lew Yan Voon, L. C.; Wang, J.; Zhang, Y.;

    2015-01-01

    Phosphorene is a two-dimensional nanomaterial with a direct band-gap at the Brillouin zone center. In this paper, we present a recently derived effective-mass theory of the band structure in the presence of strain and electric field, based upon group theory. Band parameters for this theory are co...

  16. Flat Band Quastiperiodic Lattices

    Science.gov (United States)

    Bodyfelt, Joshua; Flach, Sergej; Danieli, Carlo

    2014-03-01

    Translationally invariant lattices with flat bands (FB) in their band structure possess irreducible compact localized flat band states, which can be understood through local rotation to a Fano structure. We present extension of these quasi-1D FB structures under incommensurate lattices, reporting on the FB effects to the Metal-Insulator Transition.

  17. [Iron-refractory iron deficiency anemia].

    Science.gov (United States)

    Kawabata, Hiroshi

    2016-02-01

    The major causes of iron deficiency anemia (IDA) include iron loss due to bleeding, increased iron requirements, and decreased iron absorption by the intestine. The most common cause of IDA in Japanese women is iron loss during menstruation. Autoimmune atrophic gastritis and Helicobacter pylori infection can also cause IDA by reducing intestinal iron absorption. In addition to these common etiologies, germline mutations of TMPRSS6 can cause iron-refractory IDA (IRIDA). TMPRSS6 encodes matriptase-2, a membrane-bound serine protease primarily expressed in the liver. Functional loss of matriptase-2 due to homozygous mutations results in an increase in the expression of hepcidin, which is the key regulator of systemic iron homeostasis. The serum hepcidin increase in turn leads to a decrease in iron supply from the intestine and macrophages to erythropoietic cells. IRIDA is microcytic and hypochromic, but decreased serum ferritin is not observed as in IDA. IRIDA is refractory to oral iron supplementation, but does respond to intravenous iron supplementation to some extent. Because genetic testing is required for the diagnoses of IRIDA, a considerable number of cases may go undiagnosed and may thus be overlooked. PMID:26935626

  18. Special thermite cast irons

    OpenAIRE

    Yu. Zhiguts; I. Kurytnik

    2008-01-01

    The given paper deals with the problems of the synthesis of cast iron by metallothermy synthesis. On the basis of investigated method of calculations structures of charges have been arranged and cast iron has been synthesized further. Peculiarities metallothermic smelting were found, mechanical properties and structure of received cast iron were investigated and different technologies for cast iron receiving were worked out.

  19. Iron deficiency anemia

    Science.gov (United States)

    Anemia - iron deficiency ... iron from old red blood cells. Iron deficiency anemia develops when your body's iron stores run low. ... You may have no symptoms if the anemia is mild. Most of the time, ... slowly. Symptoms may include: Feeling weak or tired more often ...

  20. Nutritional iron deficiency

    NARCIS (Netherlands)

    Zimmermann, M.B.; Hurrell, R.F.

    2007-01-01

    Iron deficiency is one of the leading risk factors for disability and death worldwide, affecting an estimated 2 billion people. Nutritional iron deficiency arises when physiological requirements cannot be met by iron absorption from diet. Dietary iron bioavailability is low in populations consuming

  1. Paleomagnetism of the Marble Bar Chert Member, Western Australia: Implications for apparent polar wander path for Pilbara craton during Archean time

    Science.gov (United States)

    Suganuma, Yusuke; Hamano, Yozo; Niitsuma, Sachiko; Hoashi, Masamichi; Hisamitsu, Toshio; Niitsuma, Nobuaki; Kodama, Kazuto; Nedachi, Munetomo

    2006-12-01

    The Archean Biosphere Drilling Project (ABDP) drilled a continuous 270 m long oriented core from the Towers Formation, which includes the Marble Bar Chert Member (3456.1-3476.0 Ma) in the Pilbara craton, northwestern Australia. A paleomagnetic study of 261 discrete specimens, collected from a 158.5 to 182.0 m section of the Marble Bar Chert Member, revealed two distinct magnetic components (LT and MT). The MT component yields seven different mean paleomagnetic directions clustered as MB1 to MB7. These, together with the published paleomagnetic poles of early Archean rocks from the Pilbara craton, draw a continuous paleomagnetic pole path, which likely to be regarded as the early to late Archean apparent polar wander path (APWP) for the Pilbara craton. The APWP implies that the Pilbara craton underwent a latitudinal drift of about 21° during the interval when the magnetization of the Marble Bar Chert Member was acquired. The estimated speed of the lateral drift is 12-112 cm/yr (120-1120 km/Myr), which is large compared with current plate motion velocities, suggesting that continents might have moved during the Archean faster than in the Phanerozoic.

  2. Urinary iron excretion test in iron deficiency anemia.

    OpenAIRE

    Kimura,Ikuro; Yamana,Masatoshi; NNishishita,Akira; Sugiyama,Motoharu; Miyata, Akira

    1980-01-01

    A urinary iron excretion test was carried out in 22 patients with iron deficiency anemia. The iron excretion index was significantly higher in patients with intractable iron deficiency anemia compared with normal subjects and anemic patients who were responsive to iron therapy. The findings suggest that iron excretion may be a factor that modulates the response of patients to iron therapy.

  3. Mammalian iron transport.

    Science.gov (United States)

    Anderson, Gregory Jon; Vulpe, Christopher D

    2009-10-01

    Iron is essential for basic cellular processes but is toxic when present in excess. Consequently, iron transport into and out of cells is tightly regulated. Most iron is delivered to cells bound to plasma transferrin via a process that involves transferrin receptor 1, divalent metal-ion transporter 1 and several other proteins. Non-transferrin-bound iron can also be taken up efficiently by cells, although the mechanism is poorly understood. Cells can divest themselves of iron via the iron export protein ferroportin in conjunction with an iron oxidase. The linking of an oxidoreductase to a membrane permease is a common theme in membrane iron transport. At the systemic level, iron transport is regulated by the liver-derived peptide hepcidin which acts on ferroportin to control iron release to the plasma. PMID:19484405

  4. Iron metabolism and iron supplementation in cancer patients

    OpenAIRE

    Ludwig, Heinz; Evstatiev, Rayko; Kornek, Gabriela; Aapro, Matti; Bauernhofer, Thomas; Buxhofer-Ausch, Veronika; Fridrik, Michael; Geissler, Dietmar; Geissler, Klaus; Gisslinger, Heinz; Koller, Elisabeth; Kopetzky, Gerhard; Lang, Alois; Rumpold, Holger; Steurer, Michael

    2015-01-01

    Summary Iron deficiency and iron deficiency-associated anemia are common complications in cancer patients. Most iron deficient cancer patients present with functional iron deficiency (FID), a status with adequate storage iron, but insufficient iron supply for erythroblasts and other iron dependent tissues. FID is the consequence of the cancer-associated cytokine release, while in absolute iron deficiency iron stores are depleted resulting in similar but often more severe symptoms of insuffici...

  5. Kyanite/corundum eclogites from the Kaapvaal Craton: subducted troctolites and layered gabbros from the Mid- to Early Archean

    Science.gov (United States)

    Shu, Qiao; Brey, Gerhard P.; Hoefer, Heidi E.; Zhao, Zhidan; Pearson, D. Graham

    2016-02-01

    An oceanic crustal origin is the commonly accepted paradigm for mantle-derived eclogites. However, the significance of the aluminous members of the eclogite suite, containing kyanite and corundum, has long been underrated and their role neglected in genetic models of cratonic evolution. Here, we present a geochemical and petrological study of a suite of kyanite- and corundum-bearing eclogites from the Bellsbank kimberlite, S. Africa, which originate from depths between 150 and 200 km. Although clearly of high-pressure provenance, these rocks had a low-pressure cumulative origin with plagioclase and olivine as major cumulate phases. This is shown by the very pronounced positive Eu anomalies, low REE abundances, and δ 18O values lower than the Earth's mantle. Many chemical features are identical to modern-day troctolitic cumulates including a light REE depletion akin to MORB, but there are also distinguishing features in that the eclogites are richer in Na, Fe, and Ni. Two of the eclogites have a minimum age of ~3.2 Ga, defined by the extremely unradiogenic 87Sr/86Sr (0.7007) in clinopyroxene. Phase equilibria indicate that the parent melts were formed by partial melting below an Archean volcanic center that generated (alkali-)picritic to high-alumina tholeiitic melts from a mantle whose oxygen fugacity was lower than today. Fractional crystallization produced troctolites with immiscible sulfide melt droplets within the mafic crust. Instability of the mafic crust led to deep subduction and re-equilibration at 4-6 GPa. Phase relationships plus the presence of a sample with appreciable modal corundum but no Eu anomaly suggest that kyanite- and corundum-bearing eclogites may also originate as plagioclase-free, higher pressure cumulates of highly aluminous clinopyroxene, spinel, and olivine. This is consistent with the crystallizing phase assemblage from an olivine tholeiitic to picritic magma deeper in the Archean oceanic crust or uppermost mantle. We postulate that

  6. Paleomagnetism of the Astrobiology Drilling Project 8 drill core, Pilbara, Western Australia: implications for the early geodynamo and Archean tectonics

    Science.gov (United States)

    Bradley, K.; Weiss, B.; Carporzen, L.; Anbar, A.; Buick, R.

    2008-12-01

    Paleomagnetic measurements from the Archean Pilbara craton have recently been used to argue for the presence of a substantial magnetic field at 3.2 Ga (Tarduno et al., 2007), as well as for extremely fast plate motions or true polar wander (Strik et al., 2003, Suganuma et al., 2006). Paleomagnetic records in the Archean are fundamentally limited by the scarcity of well-preserved, low metamorphic grade Archean rocks. Where such rocks are exposed, paleomagnetic sampling is often difficult or impossible due to pervasive lightning remagnetization and deep weathering of the cratonic surface. More pristine samples can potentially be obtained from shallow drill cores like those obtained by the Astrobiology Drilling Project (ABDP). We present a paleomagnetic analysis of the ~350 m deep ABDP-8 drill core, which was drilled in the East Strelley greenstone belt and which penetrated the Double Bar Formation of the Warrawoona Group, as well as the unconformably overlying Euro Basalt and Strelley Pool Chert units of the Kelly Group. Full sample orientation (declination and inclination) was achieved through the use of a Ballmark orientation system. A strong drilling overprint was removed for most samples by alternating field demagnetization to 20 mT. Subsequent thermal demagnetization revealed single-polarity magnetic directions within the Euro Basalt and Double Bar Formation carried by magnetite. The directions from these two Formations are statistically different to >95% confidence, which constitutes a positive unconformity test and indicates that the Euro Basalt direction is primary. Upon tilt correction, the ~3.34-3.37 Ga Euro Basalt direction is indistinguishable from the tilt-corrected direction found previously in the ~3.46 Ga Duffer Formation of the Warrawoona Group (McElhinny and Senanayake, 1980). The Euro Basalt direction, if taken at face value, implies small relative motion of the Pilbara Craton from ~3.46 Ga to ~3.34 Ga. This is inconsistent with the apparent polar

  7. Early terrestrial impact events: Archean spherule layers in the Barberton Greenstone Belt, South Africa

    Science.gov (United States)

    Ozdemir, Seda; Koeberl, Christian; Schulz, Toni; Reimold, W. Uwe; Hofmann, Axel

    2015-04-01

    In addition to the oldest known impact structure on Earth, the 2.02-billion-year-old Vredefort Structure in South Africa, the evidence of Early Earth impact events are Archean spherule beds in South Africa and Australia. These spherules have been interpreted as condensation products from impact plumes and molten impact ejecta or/and impact ejecta that were melted during atmospheric re-entry [e.g., 1,2]. The 3.2-3.5 Ga spherule layers in the Barberton Greenstone Belt in South Africa currently represent the oldest known remnants of impact deposits on Earth. Aiming at identification of extraterrestrial components and to determine the diagenetic and metamorphic history of spherule layer intersections recently recovered in the CT3 drill core from the northeastern part of the Barberton Greenstone Belt, we have studied samples from these layers in terms of petrography and geochemistry. All samples, including spherule layer intersections and intercalating country rocks, were studied for mineral identification by optical and electron microscopy, as well as electron microprobe analysis (EPMA) at Natural History Museum Vienna and Museum für Naturkunde Berlin (MfN). Major and trace element compositions were determined via X-ray fluorescence spectrometry at MfN and instrumental neutron activation analysis (INAA) at University of Vienna. Os isotopes were measured by thermal ionization mass spectrometry (N-TIMS) at University of Vienna. Eighteen spherule beds are distributed over 150 meter drill core in CT3. Spherules are variably, deformed or undeformed. The high number of these layers may have been caused by tectonic duplication. Spherule beds are intercalated with shale, chert, carbonate, and/or sulfide deposits (country rocks). The size range of spherules is 0.5 to 2 mm, and some layers exhibit gradation. Shapes of spherules differ from spherical to ovoid, as well as teardrops, and spherules commonly show off-center vesicles, which have been interpreted as a primary

  8. Coupled Fe and S isotope variations in pyrite nodules from Archean shale

    OpenAIRE

    Marin-Carbonne, Johanna; Rollion-Bard, Claire; Bekker, Andrey; Rouxel, Olivier; Agangi, Andrea; Cavalazzi, Barbara; Wohlgemuth-ueberwasser, Cora C.; Hofmann, Axel; McKeegan, Kevin D.

    2014-01-01

    Iron and sulfur isotope compositions recorded in ancient rocks and minerals such as pyrite (FeS2) have been widely used as a proxy for early microbial metabolisms and redox evolution of the oceans. However, most previous studies focused on only one of these isotopic systems. Herein, we illustrate the importance of in-situ and coupled study of Fe and S isotopes on two pyrite nodules in a c. 2.7 Ga shale from the Bubi Greenstone Belt (Zimbabwe). Fe and S isotope compositions were measured both ...

  9. Simple Lu-Hf isotope patterns resulting from complex Archean geodynamics: example of the Pietersburg block (South Africa)

    Science.gov (United States)

    Laurent, Oscar; Zeh, Armin

    2015-04-01

    The combined use of U-Pb and Lu-Hf isotope data from Hadean and Archean zircons is widely used to constrain the mechanisms of continental crust formation and evolution in the early Earth. Such data generally define ɛHf-time arrays, interpreted as reflecting the closed-system, protracted reworking of single crustal reservoirs episodically extracted from depleted mantle (DM) sources. Many models about early Earth evolution and continental growth rely on this interpretation and its consequences (i.e. determination of Hf model ages and crustal residence times). However, this straightforward interpretation is difficult to reconcile with the complex evolution of Archean terranes, involving progressive crustal maturation and a range of crustal and mantle sources to granitoid magmas. Here we present a database of U-Pb and Lu-Hf isotopes measured in situ by LA-(MC-)ICPMS in zircons from >30 samples, representative of the temporal and spatial record of a single segment of Archean crust, the Pietersburg block (Kaapvaal Craton, South Africa). Coupling of age-Hf data with petrological and geochemical constraints shows that >1 Ga-long crustal evolution in the PB is characterized by (i) crustal nucleation in an intra-oceanic setting between 3.4 and 3.1 Ga; (ii) rapid formation of large volumes of juvenile TTG crust in an accretionary orogen at the northern edge of the proto-Kaapvaal craton between 3.1 and 2.9 Ga; (iii) intracrustal reworking and subduction of TTG-derived sediments along an Andean-type continental margin between 2.9 and 2.75 Ga; (iv) continental collision with the Central Zone of the Limpopo Belt at 2.75-2.69 Ga, resulting in magmatism derived from local crust and metasomatized mantle; (v) a discrete anorogenic event at ~2.05 Ga with the emplacement of SCLM-derived alkaline magmas. Despite the diversity of magmas and geodynamic settings depicted by this evolution, all samples emplaced between 3.0 and 2.0 Ga plot along a single, robust array of decreasing

  10. Archean and proterozoic multiple tectonothermal events recorded by gneisses in the Amparo Region, Sao Paulo State, Brazil

    International Nuclear Information System (INIS)

    The basement of the Mesoproterozoic graywacke-volcanic arc of the Alto Rio Grande Belt, is a microplate between the Sao Francisco Craton and the Ribeira Fold Belt of southeastern Brazil. This basement is composed of migmatites/orthogneisses and intrusive metagranitoid rocks. These orthogneisses were derived from calc-alkaline plutonic rocks (Campos Neto, 1991), and have been considered to be Archean in age but affected by Proterozoic tectonothermal episodes (Tassinari and Campos Neto, 1988; Artur, 1988). In order to investigate further the age of the protoliths plus their subsequent high temperature crustal history, U-Pb zircon (SHRIMP) and Sm-Nd model ages were determined for different components of the migmatites and intrusive metagranitoids (au)

  11. Iron and stony-iron meteorites

    DEFF Research Database (Denmark)

    Benedix, Gretchen K.; Haack, Henning; McCoy, T. J.

    2014-01-01

    interiors of Earth and other terrestrial planets. This chapter deals with our current knowledge of these meteorites. How did they form? What can they tell us about the early evolution of the solar system and its solid bodies? How closely do they resemble the materials from planetary interiors? What do and...... sampling of the deep interiors of differentiated asteroids. Iron and stony-iron meteorites are fragments of a large number of asteroids that underwent significant geological processing in the early solar system. Parent bodies of iron and some stony-iron meteorites completed a geological evolution similar......Without iron and stony-iron meteorites, our chances of ever sampling the deep interior of a differentiated planetary object would be next to nil. Although we live on a planet with a very substantial core, we will never be able to sample it. Fortunately, asteroid collisions provide us with a rich...

  12. Pb-Pb and U-Pb zircon ages of archean syntetocnic granites of the Carajas metallogenic province, northern Brazil

    International Nuclear Information System (INIS)

    The Carajas Metallogenic Province is located in the southeastern Amazonian Craton. It has been divided in two domains, the southernmost comprises the Rio Maria region and the northernmost corresponds to Caraj region (Souza et al. 1996). The former domain is made up of Archean greenstone sequences (2,97 Ga), TTG (2,9 Ga) and calc-alkaline granitoids (2,87 Ga) (Macambira and Lafon 1995, Leite et al. 1999, Althoff et al. 2000). The Carajas block is constituted of minor mafic granulites (3,00 Ga) and quartzofeldspathic gneisses (2,81 Ga), metavolcanosedimentary sequences (2,76 Ga) and granites (2,76 to 2,56 Ga) (Machado et al. 1991; Huhn et al. 1999, Pidgeon et al. 2000). Widespread anorogenic A-type granites are found in both areas (Docegeo 1988; Dall'Agnol et al. 1994). In the last two decades several authors (Lindenamyer et al. 1994, Barros and Barbey 1998, Huhn et al. 1999 and others) have emphasized the role of the Archean granite magmatism in the tectonicthermal evolution in the Carajas Province. In this paper we discuss the tectonic significance of the Pb- Pb and U-Pb ages obtained in some granitoids from the Carajas region. The Estrela Granite Complex and the granitoids located to the north of Parauapebas were dated by Pb- Pb evaporation zircon method (cf. Kober 1987). Data are presented considering 2σ∼. The Pb corrections have been done in the basis of the evolution model of Pb in double stage (cf. Stacey and Kramers 1975). U-Pb zircon method (cf. Krogh 1973, Stacey and Kramers 1975, Parrish 1987, Ludwuig 1999), recently put on routine in the Para-Iso laboratories, was employed to date the granite from the Serra do Rabo area. Analyses were carried on the Finnigan Mat 262 spectrometer (au)

  13. Strontium, neodymium and lead isotopic compositions of deep crustal xenoliths from the Snake River Plain: Evidence for Archean basement

    International Nuclear Information System (INIS)

    Xenoliths of intermediate to felsic granulites found in evolved lavas from the Snake River Plain have been analyzed for Nd, Pd, and Sr isotopic compositions and related trace element contents. Overall, they exhibit wide ranges in present-day values of 87Sr/86Sr (0.70235-0.83011), 143Nd/144Nd (0.51023-0.51148) and 206Pb/204Pb (13.43-24.65). The Rb-Sr, U-Pb, Th-Pb, and Sm-Nd decay schemes have been variably affected by granulite facies metamorphism and possibly by transport in the host magmas. However, Pb-Pb and Sm-Nd isochron systematics seemingly are preserved in many of the xenoliths and indicate essentially concordant metamorphic ages of about 2.8 Ga. Nd model ages are significantly older (ca. 3.1-3.4 Ga) for many of the xenoliths. Precambrian metasediments exposed along the southern margin of the Snake River Plain have Sm-Nd systematics similar to those of the xenoliths. These results suggest that at least two significant thermal events occurred during Archean evolution of the crust in this region: a) early (ca. 3.1-3.4 Ga) additions of mantle-derived magmas to the crust, and b) regional metamorphism at 2.8 Ga accompanied at least locally by magmatism. Concordance between the Sm-Nd and Pb-Pb ages suggests that these isotopic systems are little affected by high-grade metamorphism in this case. The distribution of xenoliths in Snake River Plain lavas supports the presence of Archean crust beneath much of southern Idaho, although such rocks rarely are exposed at the surface. Thus, Nd and Pb isotopic studies of crustal xenoliths can provide a useful means of determining the extent of crustal age provinces where surface exposures are lacking. (orig.)

  14. One-man band

    OpenAIRE

    Stillman, R.

    2013-01-01

    This website presents practice-based research related to solo simultaneous instrumental performance ('one-man band'). The site was conceived as a creative and widely accessible platform for music and ideas resulting from one-man band activates carried out between 2008 and 2013. Central to this project is an interest in how one-man band technique informs compositional process, including studio production. Through presentation and analysis of the author’s own creative practice, the site exp...

  15. Iron deficiency in Europe.

    Science.gov (United States)

    Hercberg, S; Preziosi, P; Galan, P

    2001-04-01

    In Europe, iron deficiency is considered to be one of the main nutritional deficiency disorders affecting large fractions of the population, particularly such physiological groups as children, menstruating women and pregnant women. Some factors such as type of contraception in women, blood donation or minor pathological blood loss (haemorrhoids, gynaecological bleeding...) considerably increase the difficulty of covering iron needs. Moreover, women, especially adolescents consuming low-energy diets, vegetarians and vegans are at high risk of iron deficiency. Although there is no evidence that an absence of iron stores has any adverse consequences, it does indicate that iron nutrition is borderline, since any further reduction in body iron is associated with a decrease in the level of functional compounds such as haemoglobin. The prevalence of iron-deficient anaemia has slightly decreased in infants and menstruating women. Some positive factors may have contributed to reducing the prevalence of iron-deficiency anaemia in some groups of population: the use of iron-fortified formulas and iron-fortified cereals; the use of oral contraceptives and increased enrichment of iron in several countries; and the use of iron supplements during pregnancy in some European countries. It is possible to prevent and control iron deficiency by counseling individuals and families about sound iron nutrition during infancy and beyond, and about iron supplementation during pregnancy, by screening persons on the basis of their risk for iron deficiency, and by treating and following up persons with presumptive iron deficiency. This may help to reduce manifestations of iron deficiency and thus improve public health. Evidence linking iron status with risk of cardiovascular disease or cancer is unconvincing and does not justify changes in food fortification or medical practice, particularly because the benefits of assuring adequate iron intake during growth and development are well established

  16. Crust Formation and Stabilization of the Western Archean Kaapvaal Craton: Evidence from U-Pb Geochronology of Basement Blocks and Deep Crustal Xenoliths from the Kimberley Region, South Africa

    Science.gov (United States)

    Schmitz, M. D.; Bowring, S. A.

    2001-05-01

    The kimberlites of the Kimberley region of South Africa have yielded one of the most abundantly sampled and studied suites of lithospheric mantle xenoliths in the world, providing a detailed picture of the composition and thermal evolution of the continental mantle beneath the western Kaapvaal craton. Surprisingly however, little published data exist regarding the nature of the basement and deeper crustal rocks in the western craton, with which to contrast the evolution of the crustal and mantle portions of this Archean cratonic region. Crustal xenoliths collected in the various mine dumps around Kimberley are predominantly large blocks of near-surface basement lithologies, including deformed granitic to tonalitic gneisses and amphibolites, weakly deformed pegmatoids, and non-deformed biotite granite. U-Pb zircon geochronological data for a number of xenoliths have been used to develop a preliminary framework for the age and evolution of the Archean crust of the Kimberley region. The youngest component of the Kimberley basement is a non-deformed sample of biotite granite with an age of 2724+/-2 Ma. A major episode of metamorphism and crustal anatexis is recorded by 2928+/-2 Ga metamorphic zircon growth in amphibolitic and tonalitic components of banded gneisses, and igneous zircons of identical age in weakly deformed cross-cutting pegmatoids. Zircons from these same pegmatoids also have inherited cores which yield 207Pb/206Pb dates as old as 3265 Ma. These inherited zircons, as well as cores of zircons from a foliated granodioritic xenolith with 207Pb/206Pb dates as old as 3184 Ma, indicate the antiquity of the oldest crustal components of the Kimberley basement. These data are consistent with cursory SHRIMP U-Pb zircon geochronological information reported for lithologies collected in situ in the diamond mine walls of Kimberley. Two important implications of this data are considered: first, we interpret the major metamorphism and crustal anatexis at 2.93 Ga as

  17. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Deficiency Anemia Explore Iron-Deficiency Anemia What Is... CAUSES WHO IS AT RISK SIGNS & SYMPTOMS DIAGNOSIS TREATMENTS ... less hemoglobin than normal. Iron-deficiency anemia can cause fatigue (tiredness), shortness of breath, chest pain, and ...

  18. Total iron binding capacity

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003489.htm Total iron binding capacity To use the sharing features on this page, please enable JavaScript. Total iron binding capacity (TIBC) is a blood test to ...

  19. Iron in diet

    Science.gov (United States)

    Diet - iron; Ferric acid; Ferrous acid; Ferritin ... The human body needs iron to make the oxygen-carrying proteins hemoglobin and myoglobin. Hemoglobin is found in red blood cells and myoglobin is found ...

  20. Iron supplements (image)

    Science.gov (United States)

    The mineral iron is an essential nutrient for humans because it is part of blood cells, which carry oxygen to all body cells. There is no conclusive evidence that iron supplements contribute to heart attacks.

  1. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... and women are the two groups at highest risk for iron-deficiency anemia. Outlook Doctors usually can successfully ... With and Managing Iron-Deficiency Anemia 05/18/2011 This video— ...

  2. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... levels usually are due to blood loss, poor diet, or an inability to absorb enough iron from ... iron levels. Susan also made changes to her diet, such as focusing more on green leafy vegetables, ...

  3. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... This Content: NEXT >> Featured Video Living With and Managing Iron-Deficiency Anemia 05/18/2011 This video— ... treatment. For more information about living with and managing iron-deficiency anemia, go to the Health Topics ...

  4. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... iron-rich protein that carries oxygen from the lungs to the rest of the body. Iron-deficiency ... 2011 This video—presented by the National Heart, Lung, and Blood Institute, part of the National Institutes ...

  5. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... intravenous iron therapy. Rate This Content: NEXT >> Featured Video Living With and Managing Iron-Deficiency Anemia 05/18/2011 This video—presented by the National Heart, Lung, and Blood ...

  6. Iron Therapy for Preterm Infants

    OpenAIRE

    Rao, Raghavendra; Georgieff, Michael K.

    2009-01-01

    Preterm infants are at risk for both iron deficiency and iron overload. The role of iron in multiple organ functions suggests that iron supplementation is essential for the preterm infant. Conversely, the potential for iron overload and the poorly developed anti-oxidant measures in the preterm infant argues against indiscriminate iron supplementation in this population. The purpose of this article is to review the predisposing factors and consequences of iron deficiency and iron overload in t...

  7. Special thermite cast irons

    Directory of Open Access Journals (Sweden)

    Yu. Zhiguts

    2008-07-01

    Full Text Available The given paper deals with the problems of the synthesis of cast iron by metallothermy synthesis. On the basis of investigated method of calculations structures of charges have been arranged and cast iron has been synthesized further. Peculiarities metallothermic smelting were found, mechanical properties and structure of received cast iron were investigated and different technologies for cast iron receiving were worked out.

  8. Alternative iron making routes

    Energy Technology Data Exchange (ETDEWEB)

    Kaushik, P.; Sharma, T. [Indian School of Mines, Dhanbad (India)

    2002-07-01

    The versatile route of iron production 'blast furnace' technique is being replaced by widely accepted Corex technology, Midrex process using Fastmelt ironmaking, eco-friendly Romelt process, more innovative Ausmelt & Hismelt technology, TATA KORF Mini blast furnace improvement, 'quickest iron through Orbiting Plasma', Direct iron ore smelting process, Conred, AISI-Hyl, Inred processes, Direct iron ore reduction methods, their comparison and proposed modifications. 18 refs., 11 figs., 14 tabs.

  9. Iron deficiency and cognition

    OpenAIRE

    Hulthén, Lena

    2003-01-01

    Iron deficiency is the most prevalent nutritional disorder in the world. One of the most worrying consequences of iron deficiency in children is the alteration of behaviour and cognitive performance. In iron-deficient children, striking behavioural changes are observed, such as reduced attention span, reduced emotional responsiveness and low scores on tests of intelligence. Animal studies on nutritional iron deficiency show effects on learning ability that parallel the human studies. Despite ...

  10. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... the body. Iron-deficiency anemia usually develops over time if your body doesn't have enough iron ... Institutes of Health—shows how Susan, a full-time worker and student, has coped with having iron- ...

  11. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... body. Low iron levels usually are due to blood loss, poor diet, or an inability to absorb enough iron from food. Overview Iron-deficiency anemia is a common type of anemia . The term "anemia" usually refers to ...

  12. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... the NHLBI on Twitter. What Is Iron-Deficiency Anemia? Español Iron-deficiency anemia is a common, easily ... Featured Video Living With and Managing Iron-Deficiency Anemia 05/18/2011 This video—presented by the ...

  13. Iron-Deficiency Anemia

    Science.gov (United States)

    ... the NHLBI on Twitter. What Is Iron-Deficiency Anemia? Español Iron-deficiency anemia is a common, easily ... Featured Video Living With and Managing Iron-Deficiency Anemia 05/18/2011 This video—presented by the ...

  14. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... page from the NHLBI on Twitter. What Is Iron-Deficiency Anemia? Español Iron-deficiency anemia is a ... Content: NEXT >> Featured Video Living With and Managing Iron-Deficiency Anemia 05/18/2011 This video—presented ...

  15. DFT studies of iron-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Boeri, Lilia; Dolgov, Oleg V.; Krogh Andersen, Ole [MPI-FKF, Heisenbergstrasse 1, D-70569 Stuttgart (Germany); Golubov, Alexander A. [Faculty of Science and Technology, MESA+ Institute for Nanotechnology, University of Twente,7500 AE Enschede (Netherlands)

    2009-07-01

    The discovery of superconductivity in iron pnicticides has generated considerable interest. So far, however, not only the pairing mechanism, but even the basic electronic structure of these materials is not well understood. We use Density Functional Theory to understand the electronic and vibrational properties of LaOFeAs, which can be considered a prototype for iron pnictides. First, we calculate the phonon dispersions and electron-phonon coupling using linear response and show that standard Migdal-Eliashberg theory cannot explain the experimental T{sub c}. Then we derive ab-initio an accurate tight-binding Hamiltonian, which allows us to elucidate the origin of the complicated band structure of iron pnicticides. As a first application of our model, we study itinerant magnetism.

  16. Broad iron lines in Active Galactic Nuclei

    CERN Document Server

    Fabian, A C; Reynolds, C S; Young, A J

    2000-01-01

    An intrinsically narrow line emitted by an accretion disk around a black hole appears broadened and skewed as a result of the Doppler effect and gravitational redshift. The fluorescent iron line in the X-ray band at 6.4-6.9keV is the strongest such line and is seen in the X-ray spectrum of many active galactic nuclei and, in particular, Seyfert galaxies. It is an important diagnostic with which to study the geometry and other properties of the accretion flow very close to the central black hole. The broad iron line indicates the presence of a standard thin accretion disk in those objects, often seen at low inclination. The broad iron line has opened up strong gravitational effects around black holes to observational study with wide-reaching consequences for both astrophysics and physics.

  17. Nature of the emission band of Dergaon meteorite in the region 5700—6700 Å

    Indian Academy of Sciences (India)

    S Bhattacharyya; A Gohain Barua; R Konwar; R Changmai; G D Baruah

    2004-06-01

    An emission band system in the region 5700—6700 Å from Dergaon stoney iron meteorite which fell at Dergaon, India on March 2, 16.40 local time (2001) was excited with the help of a continuous 500 mW Ar+ laser. The band system is attributed to silicate (olivine), a major component of the meteorite.

  18. Archean cherts from the Barberton Greenstone Belt (3.5-3.2Ga), South africa. Formation process and usability as paleo-environmental proxies

    OpenAIRE

    Ledevin, Morgane,

    2013-01-01

    Archean cherts potentially constrain the primitive environment in which life emerged and evolved. These siliceous rocks formed by three processes : C-cherts (primary cherts) formed by the chemical precipitation of oceanic silica, either as a siliceous ooze (or silica gel) on the seabed, or as cement within still soft sediments at the surface ; F-cherts (fracturefilling cherts) precipitated from circulating fluids in concordant or crosscutting veins in the shallow crust ; S-cherts (secondary c...

  19. Effect of neutrase, alcalase, and papain hydrolysis of whey protein concentrates on iron uptake by Caco-2 cells

    OpenAIRE

    Ou, K.Q.; Y. Z. Liu; Zhang, L B; Yang, X.G.; Z.W. Huang; Nout, M.J.R.; Liang, J.

    2010-01-01

    Effects of enzymatic hydrolysates of whey protein concentrates (WPC) on iron absorption were studied using in vitro digestion combined with Caco-2 cell models for improved iron absorption. Neutrase- and papain-treated WPC could improve iron absorption; especially hydrolysates by Neutrase could significantly increase iron absorption to 12.8% compared to 3.8% in the control. Hydrolysates by alcalase had negative effects to the lowest at 0.57%. Two new bands at molecular weights (MW) around and ...

  20. Iron toxicity in yeast.

    Science.gov (United States)

    Wiśnicka, R; Krzepiłko, A; Wawryn, J; Biliński, T

    1997-01-01

    It has been found that yeast cells are sensitive to iron overload only when grown on glucose as a carbon source. Effective concentration of ferrous iron is much higher than that found in natural environments. Effects of ferrous iron are strictly oxygen dependent, what suggest that the formation of hydroxyl radicals in the Fenton reaction is a cause of the toxicity. Respiratory deficiency and pretreatment of cells with antimycin A prevent toxic effects in the late exponential phase of growth, whereas uncouplers and 2mM magnesium salts completely protect even the most vulnerable exponential cells. Generally, toxic effects correlate with the ability of cells to take up this metal. The results presented suggest that during ferrous iron overload iron is transported through the unspecific divalent cation uptake system which is known in fungi. The data suggest that recently described high and low affinity systems of iron uptake in yeast are the only source of iron in natural environments. PMID:9516981

  1. Sm-Nd ages of two meta-anorthosite complexes around Holenarsipur: constraints on the antiquity of Archean supracrustal rocks of the Dharwar craton

    International Nuclear Information System (INIS)

    Whole-rock Sm-Nd isochron ages are reported for two stratiform meta-anorthosite complexes emplaced into the Archean supracrustal-gneiss association in the amphibolite facies terrain around Holenarsipur, in the Dharwar craton, South India. While these metaperidotite-pyroxenite- gabbro-anorthosite complexes are petrologically and geochemically similar, they differ in the intensity of tectonic fabric developed during the late Archean (c. 2.5 Ga) deformation. They also differ in their whole-rock Sm-Nd isochron ages and initial Nd isotopic compositions: 3.285 ± 0.17 Ga. εNd = 0.82±0.78 for the Honnavalli meta-anorthosite complex from a supracrustal enclave in the low-strain zone, and 2.495 ± 0.033 Ga, εNd = -2.2±0.3 for the Dodkadnur meta-anorthosites from the high-strain southern arm of the Holenarsipur Supracrustal Belt (HSB). We interpret these results as indicating that the magmatic protoliths of both meta-anorthosite complexes were derived from a marginally depleted mantle at c. 3.29 Ga but only the Dodkadnur rocks were isotopically reequilibrated on a cm-scale about 800 Ma later presumably due to the development of strong penetrative fabrics in them during Late Archean thermotectonic event around 2.5 Ga. Our results set a younger age limit at c. 3.29 Ga for the supracrustal rocks of the HSB in the Dharwar craton. (author)

  2. Sm-Nd Ages of Two Meta-Anorthosite Complexes Around Holenarsipur: Constraints on the Antiquity of Archean Supracrustal Rocks of the Dharwar Craton

    Indian Academy of Sciences (India)

    Y J Bhaskar Rao; Anil Kumar; A B Vrevsky; R Srinivasan; G V Anantha Iyer

    2000-03-01

    Whole-rock Sm-Nd isochron ages are reported for two stratiform meta-anorthosite complexes emplaced into the Archean supracrustal-gneiss association in the amphibolite facies terrain around Holenarsipur, in the Dharwar carton, South India. While these metaperidotite-pyroxenite-gabbro-anorthosite complexes are petrologically and geochemically similar, they differ in the intensity of tectonic fabric developed during the late Archean (c.2.5Ga) deformation. They also differ in their whole-rock Sm-Nd isochron ages and initial Nd isotopic compositions: 3.285 ± 0.17 Ga, Nd = 0.82 ± 0.78 for the Honnavalli meta-anorthosite complex from a supracrustal enclave in the low-strain zone, and 2.495 ± 0.033 Ga, Nd = -2.2+-0.3 for the Dodkadnur meta-anorthosites from the high-strain southern arm of the Holenarsipur Supracrustal Belt (HSB). We interpret these results as indicating that the magmatic protoliths of both meta-anorthosite complexes were derived from a marginally depleted mantle at c.3.29 Ga but only the Dodkadnur rocks were isotopically reequilibrated on a cm-scake about 800 Ma later presumably due to the development of strong penetrative fabrics in them during Late Archean thermotectonic event around 2.5Ga. Our results set a younger age limit at c.3.29Ga for the supracrustal rocks of the HSB in the Dharwar craton.

  3. Laparoscopic gastric banding

    Science.gov (United States)

    ... make the band tighter or looser any time after you have this surgery. It may be tightened or ... Having problems eating Not losing enough weight Vomiting after you eat Outlook (Prognosis) The final weight loss with ...

  4. CSF oligoclonal banding - slideshow

    Science.gov (United States)

    ... presentations/100145.htm CSF oligoclonal banding - series—Normal anatomy ... Overview The cerebrospinal fluid (CSF) serves to supply nutrients to the central nervous system (CNS) and collect waste products, as well as ...

  5. The Band Pass Filter

    OpenAIRE

    Christiano, Lawrence J.; Terry J. Fitzgerald

    1999-01-01

    The `ideal' band pass filter can be used to isolate the component of a time series that lies within a particular band of frequencies. However, applying this filter requires a dataset of infinite length. In practice, some sort of approximation is needed. Using projections, we derive approximations that are optimal when the time series representations underlying the raw data have a unit root, or are stationary about a trend. We identify one approximation which, though it is only optimal for one...

  6. Iliotibial band friction syndrome

    OpenAIRE

    Lavine, Ronald

    2010-01-01

    Published articles on iliotibial band friction syndrome have been reviewed. These articles cover the epidemiology, etiology, anatomy, pathology, prevention, and treatment of the condition. This article describes (1) the various etiological models that have been proposed to explain iliotibial band friction syndrome; (2) some of the imaging methods, research studies, and clinical experiences that support or call into question these various models; (3) commonly proposed treatment methods for ili...

  7. Ferrite grade iron oxides from ore rejects

    Indian Academy of Sciences (India)

    K S Rane; V M S Verenkar; P Y Sawant

    2001-06-01

    Iron oxyhydroxides and hydroxides were synthesized from chemically beneficiated high SiO2/Al2O3 low-grade iron ore (57.49% Fe2O3) rejects and heated to get iron oxides of 96–99.73% purity. The infrared band positions, isothermal weight loss and thermogravimetric and chemical analysis established the chemical formulas of iron-oxyhydroxides as -FeOOH.0.3H2O; -FeOOH.0.2H2O and amorphous FeOOH. The thermal products of all these were -Fe2O3 excepting that of -FeOOH.0.3H2O which gave mainly -Fe2O3 and some admixture of -Fe2O3. The hydrazinated iron hydroxides and oxyhydroxides, on the other hand, decomposed autocatalytically to mainly -Fe2O3. Hydrazine method modifies the thermal decomposition path of the hydroxides. The saturation magnetization, s, values were found to be in the range 60–71 emu g–1 which are close to the reported values for -Fe2O3. Mechanism of the -Fe2O3 formation by hydrazine method is discussed.

  8. Band-edge BCS–BEC crossover in a two-band superconductor: physical properties and detection parameters

    International Nuclear Information System (INIS)

    Superconductivity in iron-based magnesium diborides and other novel superconducting materials has a strong multi-band and multi-gap character. Recent experiments support the possibillity for a BCS–BEC crossover induced by strong-coupling and proximity of the chemical potential to the edge of one of the bands. Here we study the simplest theoretical model which accounts for the BCS–BEC crossover in a two-band superconductor, considering tunable interactions and tunable energy separations between the bands. Mean-field results for condensate fraction, correlation length, and superconducting gap are reported in typical crossover diagrams to locate the boundaries of the BCS, crossover and BEC regimes. When the superconducting gap is of the order of the local chemical potential, superconductivity is in the crossover regime of the BCS–BEC crossover and the Fermi surface of the small band is smeared by the gap opening. In this situation, small and large Cooper pairs coexist in the total condensate, which is the optimal condition for high-Tc superconductivity. The ratio between the gap and the Fermi energy in a given band results in the best detection parameter for experiments to locate the system in the BCS–BEC crossover. Using available experimental data, our analysis shows that iron-based superconductors have the partial condensate of the small Fermi surface in the crossover regime of the BCS–BEC crossover, supporting the recent ARPES findings. (paper)

  9. Exploring the faint young Sun problem and the possible climates of the Archean Earth with a 3-D GCM

    CERN Document Server

    Charnay, Benjamin; Wordsworth, Robin; Leconte, Jérémy; Millour, Ehouarn; Codron, Francis; Spiga, Aymeric

    2013-01-01

    Different solutions have been proposed to solve the "faint young Sun problem", defined by the fact that the Earth was not fully frozen during the Archean despite the fainter Sun. Most previous studies were performed with simple 1-D radiative convective models and did not account well for the clouds and ice-albedo feedback or the atmospheric and oceanic transport of energy. We apply a global climate model (GCM) to test the different solutions to the faint young Sun problem. We explore the effect of greenhouse gases (CO2 and CH4), atmospheric pressure, cloud droplet size, land distribution, and Earth's rotation rate. We show that neglecting organic haze, 100 mbar of CO2 with 2 mbar of CH4 at 3.8 Ga and 10 mbar of CO2 with 2 mbar of CH4 at 2.5 Ga allow a temperate climate (mean surface temperature between 10{\\deg}C and 20{\\deg}C). Such amounts of greenhouse gases remain consistent with the geological data. Removing continents produces a warming lower than +4{\\deg}C. The effect of rotation rate is even more limit...

  10. The magmatic model for the origin of Archean Au-quartz vein ore systems: an assessment of the evidence

    International Nuclear Information System (INIS)

    The magmatic model for the origin of Archean Au-quartz vein ore systems suggests that Au was derived by partition between silicate (± sulphide) melts of certain compositions and H2 O-CO2-NaCl magmatic fluids. Supporting evidence includes partial/structural geological relationships, timing relationships, H and C isotope geochemistry, probable primary Au enrichment in the Lamaque stocks, and fluid inclusion volatile geochemistry. Evidence is currently negative with respect to various within- and sub-greenstone belt metamorphic/deep crustal fluid models for primary Au mineralization; however a U-Pb age for vein stage 3 sphene from the Camflo deposit, Quebec which is ∼ 55-60 Ma younger than the host stock at 2685-2680 Ma indicates dissolution/reprecipitation of Au by late, (?) upper crustal saline fluids. Evidence is accumulating that epithermal-meso thermal Au-Ag mineralization in island arc and cordilleran settings may also have been magmatically derived ± high level fluid mixing from calc-alkaline, shoshonitic and other igneous compositions. (author)

  11. Late Archean intermediate-felsic magmatism of the South Vygozersky and Kamennozersky greenstone structures of Central Karelia

    Science.gov (United States)

    Myskova, T. A.; Zhitnikova, I. A.; L'vov, P. A.

    2015-07-01

    The geochemistry and zircon geochronology (U-Pb, SHRIMP-II) of Late Archean intermediate-felsic dikes and plagiogranites of the Shilossky massif of the South Vygozersky and Kamennozersky greenstone belts of Central Karelia were studied. Subvolcanic rocks of the dike complex vary in composition from andesitobasalts to rhyolites, in structural-textural peculiarities, and in the formation age, from 2862 ± 8 to 2785 ± 15 Ma. Compositionally and geochronologically (2853 ± 11 Ma), plagiogranites of the Shilossky massif of the South Vygozersky greenstone belts are close to the most ancient dacite and granodiorite porphyry dikes. Dikes intruded synchronously with intrusion of plagiogranites over a period of at least 70 m.y. Geochronologically, subvolcanic rocks of the dike complex and plagiogranites of the Shilossky massif are similar to granitoids of the TTG assemblages of I- and M-type granites. The Sm-Nd model age of some dikes (2970-2880 Ma) is close to the age of rock crystallization, which is evidence in favor of juvenile origin of magma. Dikes with more ancient model age (3050 Ma) are presumed to contain crustal material. Variations in age and ɛNd (from -2.7 to +2.9) indicate the absence of a unified magmatic source.

  12. Processes of luminescence sensibility and quenching of iron and lanthanide ions in silicate glass

    International Nuclear Information System (INIS)

    Processes of sensibilization and quenching of luminescence of iron and lanthanide ions in silicate glasses were investigated. It is shown that luminescence of examined iron-containing glasses is composed of a series of wide bands, conditioned by interconfigurational transition of Fe(2) ions, electron recombination with photoionized Fe(2)+ ions, as well as by decomposition of excited Fe(3) states. All three types of luminescence centers of iron-containing glasses participate in sensibilization of Nd(3), Er(3), Yb(3) luminescence

  13. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Liu Jincheng

    2010-01-01

    @@ Chapter 3 Spheroidal Graphite Cast Iron(I) Spheroidal Graphite Cast Iron, SG iron in short, refers to the cast iron in which graphite precipitates as spheroidal shape during solidification of liquid iron. The graphite in common commercial cast iron can only be changed from flake to spheroidal shape by spheroidising treatment. Since spheroidal graphite reduces the cutting effect of stress concentration, the metal matrix strength of SG iron can be applied around 70%-90%, thus the mechanical property of SG iron is significantly superior to other cast irons;even the tensile strength of SG iron is higher than that carbon steel.

  14. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Liu Jincheng

    2010-01-01

    @@ Spheroidal Graphite Cast Iron(Ⅳ) 3.7 Segregation of SG iron The non-uniform distribution of solute elements during solidification results in the micro segregation of SG iron.As for the redistribution of elements in the phases of the solidification structure,there is no intrinsic difference between SG iron and grey iron[132].

  15. Iron regulation by hepcidin

    OpenAIRE

    Zhao, Ningning; Zhang, An-Sheng; Enns, Caroline A

    2013-01-01

    Hepcidin is a key hormone that is involved in the control of iron homeostasis in the body. Physiologically, hepcidin is controlled by iron stores, inflammation, hypoxia, and erythropoiesis. The regulation of hepcidin expression by iron is a complex process that requires the coordination of multiple proteins, including hemojuvelin, bone morphogenetic protein 6 (BMP6), hereditary hemochromatosis protein, transferrin receptor 2, matriptase-2, neogenin, BMP receptors, and transferrin. Misregulati...

  16. Iron deficiency anemia Review

    OpenAIRE

    Yıldız, İnci

    2009-01-01

    Iron deficiency anemia is the most frequent and widespread anemia around the world Its prevalence is increased in infants and adolescent girls The etiologic factors may vary but anemia is essentially related to iron deficient nutrition blood loss and malabsorption Children may have paleness cardiovascular and neurologic impacts of anemia pica epithelial changes as koilonychia glossitis angular stomatitis Treatment is by oral or parenteral supplementation of iron Turk Arch Ped 2009; 44 Suppl: ...

  17. Iron overload and immunity

    Institute of Scientific and Technical Information of China (English)

    Gra(c)a Porto; Maria De Sousa

    2007-01-01

    Progress in the characterization of genes involved in the control of iron homeostasis in humans and in mice has improved the definition of iron overload and of the cells affected by it. The cell involved in iron overload with the greatest effect on immunity is the macrophage.Intriguing evidence has emerged, however, in the last 12 years indicating that parenchymal iron overload is linked to genes classically associated with the immune system. This review offers an update of the genes and proteins relevant to iron metabolism expressed in cells of the innate immune system, and addresses the question of how this system is affected in clinical situations of iron overload. The relationship between iron and the major cells of adaptive immunity, the T lymphocytes,will also be reviewed. Most studies addressing this last question in humans were performed in the clinical model of Hereditary Hemochromatosis. Data will also be reviewed demonstrating how the disruption of molecules essentially involved in adaptive immune responses result in the spontaneous development of iron overload and how they act as modifiers of iron overload.

  18. Recalling the Iron Girls

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    The phrase "iron girl" is symbolic of an era. Widely used in the 1960s and the early 1970s, it was a term that described women who, in the spirit of sexual equality, found in themselves a physical strength that surpassed their psychologi cal expectations. With their might and power, they proved to society that women could do everything that men could. The title of "iron girl" was their pride.The well-known writer Fan Xiaoqing, was one such iron girl. She says the "iron girls" were nothing less than a quest for perfection.

  19. Iron metabolism and iron supplementation in cancer patients.

    Science.gov (United States)

    Ludwig, Heinz; Evstatiev, Rayko; Kornek, Gabriela; Aapro, Matti; Bauernhofer, Thomas; Buxhofer-Ausch, Veronika; Fridrik, Michael; Geissler, Dietmar; Geissler, Klaus; Gisslinger, Heinz; Koller, Elisabeth; Kopetzky, Gerhard; Lang, Alois; Rumpold, Holger; Steurer, Michael; Kamali, Houman; Link, Hartmut

    2015-12-01

    Iron deficiency and iron deficiency-associated anemia are common complications in cancer patients. Most iron deficient cancer patients present with functional iron deficiency (FID), a status with adequate storage iron, but insufficient iron supply for erythroblasts and other iron dependent tissues. FID is the consequence of the cancer-associated cytokine release, while in absolute iron deficiency iron stores are depleted resulting in similar but often more severe symptoms of insufficient iron supply. Here we present a short review on the epidemiology, pathophysiology, diagnosis, clinical symptoms, and treatment of iron deficiency in cancer patients. Special emphasis is given to intravenous iron supplementation and on the benefits and limitations of different formulations. Based on these considerations and recommendations from current international guidelines we developed recommendations for clinical practice and classified the level of evidence and grade of recommendation according to the principles of evidence-based medicine. PMID:26373748

  20. Preliminary Iron Distribution on Vesta

    Science.gov (United States)

    Mittlefehldt, David W.; Mittlefehldt, David W.

    2013-01-01

    The distribution of iron on the surface of the asteroid Vesta was investigated using Dawn's Gamma Ray and Neutron Detector (GRaND) [1,2]. Iron varies predictably with rock type for the howardite, eucrite, and diogenite (HED) meteorites, thought to be representative of Vesta. The abundance of Fe in howardites ranges from about 12 to 15 wt.%. Basaltic eucrites have the highest abundance, whereas, lower crustal and upper mantle materials (cumulate eucrites and diogenites) have the lowest, and howardites are intermediate [3]. We have completed a mapping study of 7.6 MeV gamma rays produced by neutron capture by Fe as measured by the bismuth germanate (BGO) detector of GRaND [1]. The procedures to determine Fe counting rates are presented in detail here, along with a preliminary distribution map, constituting the necessary initial step to quantification of Fe abundances. We find that the global distribution of Fe counting rates is generally consistent with independent mineralogical and compositional inferences obtained by other instruments on Dawn such as measurements of pyroxene absorption bands by the Visual and Infrared Spectrometer (VIR) [4] and Framing Camera (FC) [5] and neutron absorption measurements by GRaND [6].

  1. Banded transformer cores

    Science.gov (United States)

    Mclyman, C. W. T. (Inventor)

    1974-01-01

    A banded transformer core formed by positioning a pair of mated, similar core halves on a supporting pedestal. The core halves are encircled with a strap, selectively applying tension whereby a compressive force is applied to the core edge for reducing the innate air gap. A dc magnetic field is employed in supporting the core halves during initial phases of the banding operation, while an ac magnetic field subsequently is employed for detecting dimension changes occurring in the air gaps as tension is applied to the strap.

  2. Ultra wide band antennas

    CERN Document Server

    Begaud, Xavier

    2013-01-01

    Ultra Wide Band Technology (UWB) has reached a level of maturity that allows us to offer wireless links with either high or low data rates. These wireless links are frequently associated with a location capability for which ultimate accuracy varies with the inverse of the frequency bandwidth. Using time or frequency domain waveforms, they are currently the subject of international standards facilitating their commercial implementation. Drawing up a complete state of the art, Ultra Wide Band Antennas is aimed at students, engineers and researchers and presents a summary of internationally recog

  3. Exploring Microbial Iron Oxidation in Wetland Soils

    Science.gov (United States)

    Wang, J.; Muyzer, G.; Bodelier, P. L. E.; den Oudsten, F.; Laanbroek, H. J.

    2009-04-01

    sequences all represented novel culturable iron oxidizers most closely related to Gallionella spp. Based on their nucleotide sequences four groups could be identified, which were comparable to the DGGE banding pattern obtained before with the gradient tubes enrichments. The above mentioned nested PCR-DGGE method was used to study the distribution and community composition of Gallionella-like iron-oxidizing bacteria under the influence of plants species, soil depth, as well as season. Soil samples from Appels, Belgium, an intertidal, freshwater marsh known to hold intensive iron cycling, were taken from 5 different vegetation types in April, July and October 2007. Soil cores were sliced at 1-cm intervals and subjected to chemical and molecular analyses. The DGGE patterns showed that the community of iron-oxidizing bacteria differed with vegetation type, and sediment depth. Samples taken in autumn held lower diversity in Gallionella-related iron oxidizers than those sampled in spring and summer.

  4. Molecular control of vertebrate iron homeostasis by iron regulatory proteins

    OpenAIRE

    Wallander, Michelle L.; Leibold, Elizabeth A.; Eisenstein, Richard S.

    2006-01-01

    Both deficiencies and excesses of iron represent major public health problems throughout the world. Understanding the cellular and organismal processes controlling iron homeostasis is critical for identifying iron-related diseases and in advancing the clinical treatments for such disorders of iron metabolism. Iron regulatory proteins (IRPs) 1 and 2 are key regulators of vertebrate iron metabolism. These RNA binding proteins post-transcriptionally control the stability or translation of mRNAs ...

  5. Amniotic Band Syndrome

    OpenAIRE

    Shetty, Prathvi; Menezes, Leo Theobald; Tauro, Leo Francis; Diddigi, Kumar Arun

    2012-01-01

    Amniotic band syndrome is an uncommon congenital disorder without any genetic or hereditary disposition. It involves fetal entrapment in strands of amniotic tissue and causes an array of deletions and deformations. Primary treatment is plastic and reconstructive surgery after birth with in utero fetal surgery also coming in vogue.

  6. Electronic and vibrational properties of graphene monolayers with iron adatoms: A density functional theory study

    Science.gov (United States)

    Dimakis, Nicholas; Navarro, Nestor E.; Velazquez, Julian; Salgado, Andres

    2015-04-01

    Periodic density functional calculations on graphene monolayers with and without an iron adatom have been used to elucidate iron-graphene adsorption and its effects on graphene electronic and vibrational properties. Density-of-states calculations and charge density contour plots reveal charge transfer from the iron s orbitals to the d orbitals, in agreement with past reports. Adsorbed iron atoms covalently bind to the graphene substrate, verified by the strong hybridization of iron d-states with the graphene bands in the energy region just below the Fermi level. This adsorption is weak and compared to the well-analyzed CO adsorption on Pt: It is indicated by its small adsorption energy and the minimal change of the substrate geometry due to the presence of the iron adatoms. Graphene vibrational spectra are analyzed though a systematic variation of the graphene supercell size. The shifts of graphene most prominent infrared active vibrational modes due to iron adsorption are explored using normal mode eigenvectors.

  7. Hepcidin in iron overload disorders

    OpenAIRE

    Papanikolaou, George; Tzilianos, Michalis; Christakis, John I.; Bogdanos, Dionisios; Tsimirika, Konstantina; MacFarlane, Julie; Goldberg, Y. Paul; Sakellaropoulos, Nikos; Ganz, Tomas; Nemeth, Elizabeta

    2005-01-01

    Hepcidin is the principal regulator of iron absorption in humans. The peptide inhibits cellular iron efflux by binding to the iron export channel ferroportin and inducing its internalization and degradation. Either hepcidin deficiency or alterations in its target, ferroportin, would be expected to result in dysregulated iron absorption, tissue maldistribution of iron, and iron overload. Indeed, hepcidin deficiency has been reported in hereditary hemochromatosis and attributed to mutations in ...

  8. DUAL BAND MONOPOLE ANTENNA DESIGN

    Directory of Open Access Journals (Sweden)

    P. Jithu

    2013-06-01

    Full Text Available The WLAN and Bluetooth applications become popular in mobile devices, integrating GSM and ISM bands operation in one compact antenna, can reduce the size of mobile devices. Recently, lot many investigations are carried out in designing a dual band antennas with operating frequencies in GSM band and in ISM band for mobile devices. Printed monopoles are under this investigation. In this paper, dual-band printed monopoles are presented to operate at GSM band i.e. 900 MHz and ISM band i.e. 2.4 GHz. We intend to observe the antenna characteristics on the network analyzer and verify the theoretical results with the practical ones.

  9. Thin Wall Iron Castings

    Energy Technology Data Exchange (ETDEWEB)

    J.F. Cuttino; D.M. Stefanescu; T.S. Piwonka

    2001-10-31

    Results of an investigation made to develop methods of making iron castings having wall thicknesses as small as 2.5 mm in green sand molds are presented. It was found that thin wall ductile and compacted graphite iron castings can be made and have properties consistent with heavier castings. Green sand molding variables that affect casting dimensions were also identified.

  10. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Susan got counseling on how to improve her health and well-being. She began taking iron supplements and multivitamins to improve her iron levels. Susan also made changes to her diet, such as focusing more on green leafy vegetables, red meats, nuts, dried fruits, and beans. Other ...

  11. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Blood Tests Blood Transfusion Restless Legs Syndrome Send a link to NHLBI to someone by E-MAIL | ... Iron-Deficiency Anemia? Español Iron-deficiency anemia is a common, easily treated condition that occurs if you ...

  12. Evidence for ancient atmospheric xenon in Archean rocks and implications for the early evolution of the atmosphere

    Science.gov (United States)

    Pujol, M.; Marty, B.; Burnard, P.; Hofmann, A.

    2012-12-01

    The initial atmospheric xenon isotopic composition has been much debated over the last 4 decades. A Non radiogenic Earth Atmospheric xenon (NEA-Xe) composition has been proposed to be the best estimate of the initial signature ([1]). NEA-Xe consists of modern atmospheric Xe without fission (131-136Xe) or radioactive decay (129Xe) products. However, the isotope composition of such non-radiogenic xenon is very different to that of potential cosmochemical precursors such as solar or meteoritic Xe, as it is mass-fractionated by up to 3-4 % per amu relative to the potential precursors, and it is also elementally depleted relative to other noble gases. Because the Xe isotopic composition of the Archean appears to be intermediate between that of these cosmochemical end-members and that of the modern atmosphere, we argued that isotopic fractionation of atmospheric xenon did not occur early in Earth's history by hydrodynamic escape, as postulated by all other models ([1], [2], [3]), but instead was a continuous, long term process that lasted during at least the Hadean and Archean eons. Taken at face value, the decrease of the Xe isotopic fractionation from 1.6-2.1 % amu-1 3.5 Ga ago ([4]) to 1 % amu-1 3.0 Ga ago (Ar-Ar age in fluid inclusions trapped in quartz from the same Dresser Formation, [5]) could reflect a secular variation of the atmospheric Xe signature. Nevertheless, up until now, all data showing an isotopic mass fractionation have been measured in rocks and fluids from the same formation (Dresser Formation, Western Australia, aged 3.5 Ga), and have yet to be confirmed in rocks from different locations. In order to better constrain xenon isotopic fractionation of the atmosphere through time, we decided to analyze barites from different ages, geological environments and metamorphism grade. We started this study with barite from the Fig Tree Formation (South Africa, aged 3.26 Ga). This barite was sampled in old mines so have negligible modern exposure time. It is

  13. Discrimination of iron ore deposits of granulite terrain of Southern Peninsular India using ASTER data

    Science.gov (United States)

    Rajendran, Sankaran; Thirunavukkarasu, A.; Balamurugan, G.; Shankar, K.

    2011-04-01

    This work describes a new image processing technique for discriminating iron ores (magnetite quartzite deposits) and associated lithology in high-grade granulite region of Salem, Southern Peninsular India using visible, near-infrared and short wave infrared reflectance data of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). Image spectra show that the magnetite quartzite and associated lithology of garnetiferrous pyroxene granulite, hornblende biotite gneiss, amphibolite, dunite, and pegmatite have absorption features around spectral bands 1, 3, 5, and 7. ASTER band ratios ((1 + 3)/2, (3 + 5)/4, (5 + 7)/6) in RGB are constructed by summing the bands representing the shoulders of absorption features as a numerator, and the band located nearest the absorption feature as a denominator to map iron ores and band ratios ((2 + 4)/3, (5 + 7)/6, (7 + 9)/8) in RGB for associated lithology. The results show that ASTER band ratios ((1 + 3)/2, (3 + 5)/4, (5 + 7)/6) in a Red-Green-Blue (RGB) color combination identifies the iron ores much better than previously published ASTER band ratios analysis. A Principal Component Analysis (PCA) is applied to reduce redundant information in highly correlated bands. PCA (3, 2, and 1 for iron ores and 5, 4, 2 for granulite rock) in RGB enabled the discrimination between the iron ores and garnetiferrous pyroxene granulite rock. Thus, this image processing technique is very much suitable for discriminating the different types of rocks of granulite region. As outcome of the present work, the geology map of Salem region is provided based on the interpretation of ASTER image results and field verification work. It is recommended that the proposed methods have great potential for mapping of iron ores and associated lithology of granulite region with similar rock units of granulite regions of Southern Peninsular India. This work also demonstrates the ability of ASTER's to provide information on iron ores, which is valuable

  14. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Liu Jincheng

    2011-01-01

    White Cast Iron (Ⅰ) White cast iron or ‘white iron' refers to the type of cast iron in which all of the carbon exists as carbide;there is no graphite in the as-cast structure and the fractured surface shows a white colour.White cast iron can be divided in three classes:· Normal white cast iron — this iron contains only C,Si,Mn,P and S,with no other alloying elements.· Low-alloy white cast iron — the total mass fraction of alloying elements is less than 5%.

  15. Re-Os, Rb-Sr, and O isotopic systematics of the Archean Kolar schist belt, Karnataka, India

    Science.gov (United States)

    Walker, R.J.; Shirey, S.B.; Hanson, G.N.; Rajamani, V.; Horan, M.F.

    1989-01-01

    The Re-Os, Rb-Sr, and O isotopic compositions of mafic and ultramafic amphibolites, gold ores, and granitic gneisses of the circa 2700 Ma Kolar schist belt reveal at least two episodes of post-magmatic alteration that affected these systems. The Re-Os isotopic systematics of many of the rocks of the belt indicate that Os was introduced to the area via fluids that carried very radiogenic Os ( 187Os 186Os2.4Ga > 39). The source of the radiogenic Os was likely ancient crust. On an outcrop scale, this alteration is also characterized by relatively minor additions of excess 87Sr and ??18O values higher than magmatic. The Rb-Sr systematics of most of these rocks are consistent with closed-system behavior since a period between 2700 and 2400 Ma ago, indicating that the alteration event likely occurred no later than the early Proterozoic. In contrast to this late Archean or early Proterozoic alteration, samples of several komatiitic amphibolites have very 187Os-depleted compositions, indicating that open-system behavior also occurred at a much later time. This alteration may have been caused by surficial weathering or the interaction of the rocks with fluids bearing unradiogenic Os. Results suggest that the Re-Os system may have only limited utility for geochronologic applications in regions for which post-crystallization noble metal mineralization is evident (e.g., gold ores). In such regions, however, the system may have an important application in assessing the timing and the ultimate sources of noble metal additions. ?? 1989.

  16. Iron replacement therapy

    DEFF Research Database (Denmark)

    Nielsen, Ole Haagen; Coskun, Mehmet; Weiss, Günter

    2016-01-01

    PURPOSE OF REVIEW: Approximately, one-third of the world's population suffers from anemia, and at least half of these cases are because of iron deficiency. With the introduction of new intravenous iron preparations over the last decade, uncertainty has arisen when these compounds should be...... administered and under which circumstances oral therapy is still an appropriate and effective treatment. RECENT FINDINGS: Numerous guidelines are available, but none go into detail about therapeutic start and end points or how iron-deficiency anemia should be best treated depending on the underlying cause of...... iron deficiency or in regard to concomitant underlying or additional diseases. SUMMARY: The study points to major issues to be considered in revisions of future guidelines for the true optimal iron replacement therapy, including how to assess the need for treatment, when to start and when to stop...

  17. Iron economy in Chlamydomonas reinhardtii

    Science.gov (United States)

    Glaesener, Anne G.; Merchant, Sabeeha S.; Blaby-Haas, Crysten E.

    2013-01-01

    While research on iron nutrition in plants has largely focused on iron-uptake pathways, photosynthetic microbes such as the unicellular green alga Chlamydomonas reinhardtii provide excellent experimental systems for understanding iron metabolism at the subcellular level. Several paradigms in iron homeostasis have been established in this alga, including photosystem remodeling in the chloroplast and preferential retention of some pathways and key iron-dependent proteins in response to suboptimal iron supply. This review presents our current understanding of iron homeostasis in Chlamydomonas, with specific attention on characterized responses to changes in iron supply, like iron-deficiency. An overview of frequently used methods for the investigation of iron-responsive gene expression, physiology and metabolism is also provided, including preparation of media, the effect of cell size, cell density and strain choice on quantitative measurements and methods for the determination of metal content and assessing the effect of iron supply on photosynthetic performance. PMID:24032036

  18. From Iron Bowl to Iron Stomach

    Institute of Scientific and Technical Information of China (English)

    MICHAEL; L.; O’NEAL

    2009-01-01

    A few decades ago, "Iron Bowl" referred to not having to go hungry in China if you were employed by the Agovernment. The government gave you a job that secured the filling of one’s rice bowl. This concept and practice did create loyalty, as the times were hard. China has moved far past those times to become the

  19. Diffuse interstellar absorption bands

    Institute of Scientific and Technical Information of China (English)

    XIANG FuYuan; LIANG ShunLin; LI AiGen

    2009-01-01

    The diffuse interstellar bands (DIBs) are a large number of absorption bands that are superposed on the interstellar extinction curve and are of interstellar origin. Since the discovery of the first two DIBs in the 1920s, the exact nature of DIBs still remains unclear. This article reviews the history of the detec-tions of DIBs in the Milky Way and external galaxies, the major observational characteristics of DIBs, the correlations or anti-correlations among DIBs or between DIBs and other interstellar features (e.g. the prominent 2175 Angstrom extinction bump and the far-ultraviolet extinction rise), and the proposed candidate carriers. Whether they are also present in circumstellar environments is also discussed.

  20. Rotational Remanent Magnetization (RRM) to Identify Pyrrhotite in Natural Iron-Sulfide-Bearing Samples

    Science.gov (United States)

    Slotznick, S. P.; Kirschvink, J. L.; Fischer, W. W.; Webb, S. M.

    2014-12-01

    Pyrrhotite has been known for several decades to have anomalous demagnetization behavior when using tumbling AF techniques. This was quantified by Thomson (1990) to show that pyrrhotite can acquire rotational remanent magnetization (RRM) similar to the more intensely-studied iron sulfide, greigite. Use of RRM as an identification tool in natural samples has not become standard practice, perhaps due to the decrease in use of tumbling AF techniques. However, using the 2G SQuID magnetometer with in-line AF/ARM coils and RAPID automated protocols (Kirschvink et al. 2008), one can easily produce and measure RRM. This method of measuring RRM has been used to identify greigite (Suzuki et al. 2006), but not pyrrhotite. We present room temperature RRM measurements for samples spinning from -20 to +20 rev/sec, perpendicular to peak AF fields of 90mT (at 950 Hz) in iron-sulfide-bearing shales, argillites, and carbonates throughout Earth History (Miocene, Cretaceous, Mesoproterozoic, Late Archean). Presence of pyrrhotite was confirmed using AF demagnetization of NRM (GRM), IRM acquisition/AF demagnetization (Cisowski plots), Kappabridge thermal susceptibility, ultra-high resolution scanning SQuID microscopy (UHRSSM), and/or X-ray absorption near edge spectroscopy (XANES)/multiple energy X-ray fluorescence (XRF) imaging. Although the total absence of pyrrhotite cannot be proven, the same techniques were applied to rocks that do not gain RRM easily to identify their iron sulfides and ferromagnetic minerals, and no magnetic iron sulfides were found. The RRM signal for pyrrhotite is distinct from that of greigite, suggesting it could be used as a tool for distinguishing these magnetic iron sulfides from each other. Further work on room temperature RRM could define a unique non-destructive rock magnetic test for pyrrhotite.

  1. Aerogravity and remote sensing observations of an iron deposit in Gara Djebilet, southwestern Algeria

    Science.gov (United States)

    Bersi, Mohand; Saibi, Hakim; Chabou, Moulley Charaf

    2016-04-01

    The Gara Djebilet iron ore region is one of the most important regions in Africa. Located in the southwestern part of Algeria at the border with Mauritania, the Gara Djebilet region is characterized by steep terrain, which makes this area not easily accessible. Due to these conditions, remote sensing techniques and geophysics are the best ways to map this iron ore. The Gara Djebilet formations are characterized by high iron content that is especially rich in hematite, chamosite and goethite. The high iron content causes an absorption band at 0.88 μm, which is referred to as band 5 in the Operational Land Imager (OLI) Landsat 8 images. In this study, we integrated geological data, aerogravity data, and remote sensing data for the purpose of mapping the distribution of the Gara Djebilet iron deposit. Several remote sensing treatments were applied to the Landsat 8 OLI image, such as color composites, band ratioing, principal component analysis and a mathematical index, which helped locate the surface distribution of the iron ore. The results from gravity gradient interpretation techniques, 2-D forward modeling and 3-D inversion of aerogravity data provided information about the 2-D and 3-D distribution of the iron deposit. The combination of remote sensing and gravity results help us evaluate the ore potential of Gara Djebilet. The estimated tonnage of the iron ore at Gara Djebilet is approximately 2.37 billion tonnes with 57% Fe.

  2. A cytosolic iron chaperone that delivers iron to ferritin

    OpenAIRE

    Shi, Haifeng; Bencze, Krisztina Z.; Stemmler, Timothy L.; Philpott, Caroline C.

    2008-01-01

    Ferritins are the main iron storage proteins found in animals, plants, and bacteria. The capacity to store iron in ferritin is essential for life in mammals, but the mechanism by which cytosolic iron is delivered to ferritin is unknown. Human ferritins expressed in yeast contain little iron. Human Poly r(C)-Binding Protein 1 (PCBP1) increased the amount of iron loaded into ferritin when expressed in yeast. PCBP1 bound to ferritin in vivo, and bound iron and facilitated iron loading into ferri...

  3. 21 CFR 310.518 - Drug products containing iron or iron salts.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 5 2010-04-01 2010-04-01 false Drug products containing iron or iron salts. 310... Drug products containing iron or iron salts. Drug products containing elemental iron or iron salts as...) that contains iron or iron salts for use as an iron source shall bear the following statement:...

  4. Geology of East Egypt greenstone field in Neoproterozoic isoand arc: Reconstruction of Iron formation sedimentary environment.

    Science.gov (United States)

    Kiyokawa, S.; Suzuki, T.

    2015-12-01

    Geology of East Egypt greenstone-granit belt which is northern part of Nubia shield was identified neoproterozoic island arc amalgamated sections. There are several iron formation within these greenstone belt. Age data shows this iron formation may be overlaped during 700 Ma Snowball period, how ever, there is no detail report of well preserved ice related evidences. We now started detail field work for identified tectonic reconstruction, original stratigraphy around Iron formation and sedimentary environment during the iron formation sedimentation area. East Egyptian shield was divided three geology, Proterozoic greenstone complex, 700-600 Granitic domes and cover sequence (Hammamet Group). We focus three area to identified sedimentary environment of iron sedimentation. Along the north-south trend of Wadi EL Dabban area are, we named Wadi branch as West site is RW-0 ~ 12, East site is RE-0 ~ 12 from north to south. Northern area is structurally moderate, southern portion is north dipping. Southern portion was intruded by granite and several place contain granitic dikes. Northeast to eastern area are identified younger sedimentary sequence (Hammamat Group) which is unconformablly overlay on the other iron formation bearing greenstone belt. Structurally these area is divided four units. Wadi was divided by right-lateral strike-ship fault. The displacement are more than 3 km. Also north dipping faults are identified.East-West trend fault are divided two units. It is divided NE, SE, NW and NS units.SW unit is most well preserved thick sequence of the Iron formation. SW unit is well preserved iron formation sequence within thick volcaniclastics. This unit mostly north dipping around 40-60 degree. Structural repetition in not well understand. Reconstract stratigraphy in this unit is at least 4000m in thickness. 5 member is identified in this sequence. Several thin iron formations are observed with in pillow lava and volcaniclastic sequence. These very thick

  5. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Ph.D Liu Jincheng

    2010-01-01

    @@ Note: This book consists of five sections: Chapter 1 Introduction, Chapter 2 Grey Iron, Chapter 3 Spheroidal Graphite Cast Iron, Chapter 4 Vermicular Cast Iron, and Chapter 5 White Cast Iron. CHINA FOUNDRY publishes this book in several parts serially, starting from the first issue of 2009.

  6. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Liu Jincheng

    2009-01-01

    @@ This book consists of five sections:Chapter 1 Introduction,Chapter 2 Grey Iron,Chapter 3 Ductile Iron,Chapter 4Vermicular Cast Iron,and Chapter 5 White Cast Iron. CHINA FOUNDRY publishs this book in several parts serially,starting from the first issue of 2009.

  7. Nonlinear FMR spectra in yttrium iron garnet

    Directory of Open Access Journals (Sweden)

    Yu.M. Bunkov, P.M. Vetoshko, I.G. Motygullin, T.R. Safin, M.S. Tagirov, N.A. Tukmakova

    2015-12-01

    Full Text Available Results of demagnetizing effect studies in yttrium iron garnet Y3Fe5O12 thin films are reported. Experiments were performed on X-Band of electron paramagnetic resonance spectrometer at room temperature. The ferromagnetic resonance (FMR spectra were obtained for one-layer single crystal YIG films for different values of the applied microwave power. Nonlinear FMR spectra transformation by the microwave power increasing in various directions of magnetic field sweep was observed. It is explained by the influence of the demagnetization action of nonequilibrium magnons.

  8. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... symptoms. Severe iron-deficiency anemia can lead to heart problems, infections, problems with growth and development in ... 18/2011 This video—presented by the National Heart, Lung, and Blood Institute, part of the National ...

  9. Study of iron fluorination

    International Nuclear Information System (INIS)

    This report deals with the action of fluorine on iron. Comprehensive descriptions are given of the particular technological methods and of the preparation of the reactants. This fluorination reaction has been investigated over a very broad range of temperature and pressure. A nucleation and growth phenomenon is described. The influence of a pollution of the gas phase by oxygen on the fluorination process is reported. The solid-state reaction between ferric fluoride and iron has been studied by calorimetry and hydrated fluorides βFeF3, 3 H2O and FeF3, H2O have been studied by Moessbauer effect. A special study has been made of the growth of iron deposits by thermal decomposition of gaseous iron fluorides. (author)

  10. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Entire Site Health Topics News & Resources Intramural Research Public Health Topics Education & Awareness Resources Contact The Health ... Severe iron-deficiency anemia can lead to heart problems, infections, problems with growth and development in children, ...

  11. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... of red blood cells. Red blood cells carry oxygen and remove carbon dioxide (a waste product) from ... Hemoglobin is an iron-rich protein that carries oxygen from the lungs to the rest of the ...

  12. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Digg. Share this page from the NHLBI on Facebook. Add this link to the NHLBI to my ... such as tiredness, poor skin tone, dizziness, and depression. After her doctor diagnosed her with iron-deficiency ...

  13. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Deficiency Anemia What Is... CAUSES WHO IS AT RISK SIGNS & SYMPTOMS DIAGNOSIS TREATMENTS PREVENTION LIVING WITH CLINICAL ... and women are the two groups at highest risk for iron-deficiency anemia. Outlook Doctors usually can ...

  14. Ocean iron fertilization

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Smetacek, V.

    In 2009 and 2010, an Indo-German scientific expedition dusted the ocean with iron to stimulate the biological pump that captures atmosphereic carbon dioxide. Two onboard scientists tell the story of this controversial project. Besides raising...

  15. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Topics Anemia Blood Tests Blood Transfusion Restless Legs Syndrome Send a link to NHLBI to someone by ... symptoms. Severe iron-deficiency anemia can lead to heart problems, infections, problems with growth and development in ...

  16. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... CAUSES WHO IS AT RISK SIGNS & SYMPTOMS DIAGNOSIS TREATMENTS PREVENTION LIVING WITH CLINICAL TRIALS LINKS Related Topics ... Doctors usually can successfully treat iron-deficiency anemia. Treatment will depend on the cause and severity of ...

  17. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Events Spokespeople Email Alerts E-Newsletters About NHLBI Organization NHLBI Director Budget, Planning, & Legislative Advisory Committees Contact ... counseling on how to improve her health and well-being. She began taking iron supplements and multivitamins ...

  18. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Health Topics Education & Awareness Resources Contact The Health Information Center Health Professionals Systematic Evidence Reviews & Clinical Practice ... and see the benefits of treatment. For more information about living with and managing iron-deficiency anemia, ...

  19. Iron in diet

    Science.gov (United States)

    ... Soybeans Dried beans and peas Kidney beans Seeds: Almonds Brazil nuts Vegetables: Broccoli Spinach Kale Collards Asparagus ... infant's additional iron needs are met by breast milk. Infants that are not breastfed should be given ...

  20. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Alerts E-Newsletters About NHLBI Organization NHLBI Director Budget, Planning, & Legislative Advisory Committees Contact Us FAQs Home » ... severity of the condition. Treatments may include dietary changes, medicines, and surgery. Severe iron-deficiency anemia may ...

  1. Petrogenesis and Tectonic Implications of Paleoproterozoic Metapelitic Rocks in the Archean Kongling Complex from the Northern Yangtze Craton, South China

    Science.gov (United States)

    Li, Y.; Zheng, J.; Wang, W.; Xiong, Q.

    2015-12-01

    The Archean Kongling Complex in the northern Yangtze Craton is an ideal target to investigate the Precambrian accretion and evolution of continental crust in South China. This study aims to unravel the crustal evolution and tectonic setting of the Yangtze Craton during the Paleoproterozoic time, using integrated studies of petrography, zircon U-Pb and Hf isotopes and whole-rock geochemistry of Paleoproterozoic metapelitic rocks in the Kongling Complex. These rocks contain garnet, sillimanite, biotite, plagioclase, minor graphite and ilmenite. Zircons from the samples show nebulous sector-zoning and rim-core structure, suggesting both metamorphic origin and detrital origin with metamorphic overprints. The metamorphic zircons and metamorphic overprints have concordant 207Pb/206Pb age at ~2.0 Ga, while detrital grains yield three distinct concordant-age populations of >2.5 Ga, 2.4-2.2 Ga and 2.2-2.1 Ga. The age patterns indicate that the depositional age of the metasedimentary rocks was 2.1-2.0 Ga. Those 2.2-2.1 Ga detrital zircons with variable ɛHf(t) values (-7.28 to 2.97) suggest the addition of juvenile materials from depleted mantle to the crust during 2.2-2.1 Ga. The 2.4-2.2 Ga zircons have Hf model ages (TDM2) of ~2.6-3.5 Ga and >2.5 Ga zircons have TDM2 ages varying from 2.9 Ga to 3.3 Ga. The new data suggest that the Kongling Complex was originally a Paleoarchean (old up to 3.5 Ga) continental nucleus, which experienced multiple episodes of growth and reworking events at 3.3-3.2 Ga, 2.9 Ga, 2.7-2.6 Ga, 2.4-2.2 Ga and 2.2-2.1 Ga. In combination with available data, the new results in this study suggest a continent-arc-continent evolution model to explain the tectonic evolution of the Yangtze Craton during the Paleoproterozoic time: the western margin of Yangtze Craton was originally an individual continent, which underwent a reworking event during 2.4-2.2 Ga and a crust growth event caused by continent-arc collision during 2.2-2.1 Ga; it subsequently collided

  2. Deciphering post-Deccan weathering and erosion history of South Indian Archean rocks from cryptomelane 40Ar-39Ar dating

    Science.gov (United States)

    Bonnet, Nicolas; Arnaud, Nicolas; Beauvais, Anicet; Chardon, Dominique

    2015-04-01

    Since the extrusion of Deccan traps ~ 63 Ma ago, weathering and erosion processes have shaped the landscapes of this Peninsula India. This resulted in pervasive bauxitic weathering on traps and deep lateritic weathering of their basement on either side of the Western Ghats Escarpment, which separates a coastal lowland from an East-dipping highland plateau. Mn-rich lateritic profiles formed by supergene weathering of Late Archean manganiferous protores in the different greenstone belts are exposed on relict paleosurfaces, which are preserved at different elevations on the highland plateau and in the coastal lowland, allowing for direct comparison of paleosurfaces and geomorphological processes across one of the most prominent relief in the Indian peninsula. Detailed petrological and geochemical investigations of samples collected in the different Mn-rich lateritic profiles allowed for precise characterization of cryptomelane [Kx Mn8-xIV MnxIII O16, nH2O], a Mn-oxide suitable for 40Ar-39Ar dating. The ages obtained document major weathering periods at ~ 53-50 Ma, ~ 40-32 Ma, and ~ 30-23 Ma in the highland profiles, and ~ 47-45 Ma, ~ 24-19 Ma and a younger age at ~ 9 Ma in the coastal lowland profiles. The age clusters are in good agreement with major regional and global Cenozoic paleoclimatic events, e.g., the Eocene climatic optimum and the early beginnings of Asian monsoons at ~ 40 Ma. The old ages obtained both in the coastal lowland and high plateau indicate synchronous lateritic (mostly bauxitic) weathering on both sides of the escarpment. The ages also indicate that most of the incision and dissection of plateau landsurfaces must have taken place during successive periods after 45, 32 and 23 Ma, while the coastal lowland surface was only weakly incised after 19 Ma. Our results thus document post-Eocene divergent erosion and weathering histories across the escarpment since it was formed at least 47 Ma ago, suggesting installation of a dual climatic regime on

  3. Iron-Air Rechargeable Battery

    Science.gov (United States)

    Narayan, Sri R. (Inventor); Prakash, G.K. Surya (Inventor); Kindler, Andrew (Inventor)

    2014-01-01

    Embodiments include an iron-air rechargeable battery having a composite electrode including an iron electrode and a hydrogen electrode integrated therewith. An air electrode is spaced from the iron electrode and an electrolyte is provided in contact with the air electrode and the iron electrodes. Various additives and catalysts are disclosed with respect to the iron electrode, air electrode, and electrolyte for increasing battery efficiency and cycle life.

  4. Iron status in the elderly

    OpenAIRE

    Fairweather-Tait, Susan J; Anna A Wawer; Gillings, Rachel; Jennings, Amy; Phyo K. Myint

    2014-01-01

    Iron deficiency anaemia is prevalent in older age, particularly after the age of 80. Serum ferritin concentrations also decline, although there is no evidence to suggest that changes in iron stores are an inevitable consequence of ageing. Chronic inflammation is a common condition in older people, making the measurement of iron status difficult, and it is likely that elevated levels of circulating hepcidin are responsible for changes in iron metabolism that result in systemic iron depletion. ...

  5. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Liu Jincheng

    2011-01-01

    @@ Vermicular graphite cast iron(VG iron for short in the following sections)is a type of cast iron in which the graphite is intermediate in shape between flake and spheroidal.Compared with the normal flake graphite in grey iron, the graphite in VG iron is shorter and thicker and shows a curved, more rounded shape.Because its outer contour is exactly like a worm, hence it is called vermicular graphite.

  6. Fe (Plasma Iron Turnover)

    OpenAIRE

    Montanaro, Zac Kime

    2011-01-01

    Fe (Plasma Iron Turnover) is a work, or compilation of interrelating works, endeavoring to generate a custom strategy for conducting experimental information exploration. Beginning with a single event in world news, the explosion of a gas plant in Western Australia in June of 2008, Fe (Plasma Iron Turnover) teases out the physical, contextual, and subtextual cues of the story to develop and articulate a methodology for discovering related events, both backwards and forwards in history, and fo...

  7. Microbes: Mini Iron Factories

    OpenAIRE

    Joshi, Kumar Batuk

    2014-01-01

    Microbes have flourished in extreme habitats since beginning of the Earth and have played an important role in geological processes like weathering, mineralization, diagenesis, mineral formation and destruction. Biotic mineralization is one of the most fascinating examples of how microbes have been influencing geological processes. Iron oxidizing and reducing bacteria are capable of precipitating wide varieties of iron oxides (magnetite), carbonates (siderite) and sulphides (greigite) via con...

  8. Iron and Liver Diseases

    OpenAIRE

    Fargion, Silvia; Mattioli, Michela; Fracanzani, Anna Ludovica; Fiorelli, Gemino

    2000-01-01

    A mild to moderate iron excess is found in patients with liver diseases apparently unrelated to genetic hemochromatosis. Iron appears to affect the natural history of hepatitis C virus-related chronic liver diseases, alcoholic liver disease and nonalcoholic steatohepatitis by leading to a more severe fibrosis and thus aiding the evolution to cirrhosis.Ahigher frequency of mutations of the HFE gene, the gene responsible for hereditary hemochromatosis, is found in patients with liver diseases a...

  9. Semiconductors bonds and bands

    CERN Document Server

    Ferry, David K

    2013-01-01

    As we settle into this second decade of the twenty-first century, it is evident that the advances in micro-electronics have truly revolutionized our day-to-day lifestyle. The technology is built upon semiconductors, materials in which the band gap has been engineered for special values suitable to the particular application. This book, written specifically for a one semester course for graduate students, provides a thorough understanding of the key solid state physics of semiconductors. It describes how quantum mechanics gives semiconductors unique properties that enabled the micro-electronics revolution, and sustain the ever-growing importance of this revolution.

  10. Archean crustal growth of the Imataca complex, Amazonian craton: Evidence from U-Pb-Sm-Nd and Rb-Sr geochronology

    International Nuclear Information System (INIS)

    The Archean Imataca Complex (IC), NW Amazonian Craton, forms a ENE-trending, fault-bounded block adjacent to the Paleoproterozoic Maroni-Itacai as magmatic arc (2.2 2.0 Ga) (Tassinari and Macambira, 1999). The IC rocks are complexely deformed, exhibiting elongated and symmetrical domes and thrusts combined with isoclinal folds. Transcurrent faults are also important, like the Guri Fault System - a zone of multiple faulting, shearing and mylonitization along the southeastern edge of the IC. In a pre-Pangean reconstruction using paleomagnetic data from rocks of the African counterpart, the Guri System is contiguous to the Sassandra (Ivory coast) and Zednes (Mauritaine) faults, in agreement also with the comparable geologic evolution between the NW Amazonian and the West Africa cratons, during the Archean and Late-Paleoproterozoic. The IC mainly composed of medium- to high grade quartz-feldspathic paragneiss, exhibits extensive mortar, augen, flaser and mylonitic textures. Calc-alkaline gneiss and granitoid rocks of igneous protolith are also present in the IC, as well as dolomitic marbles, orthopyroxene and magnetite quartzites, and BIFs that include huge ore deposits of Algoma type. Moreover, migmatite injections and anatexis (devoid of metasedimentary components) are widespread in the western part of Complex, the largest migmatite mass centered in Cerro La Ceiba. This paper reports zircon U-Pb SHRIMP, Sm-Nd and Rb-Sr isotopic data of different IC rocks in order to investigate their age and geological evolution within the tectonic framework of the Amazonian Craton (au)

  11. Separation of hematite from banded hematite jasper (BHJ) by magnetic coating

    Institute of Scientific and Technical Information of China (English)

    Subhashree Singh; H.Sahoo; S.S.Rath; B.B.Palei; B.Das

    2015-01-01

    The separation of iron oxide from banded hematite jasper (BHJ) assaying 47.8% Fe, 25.6% SiO2 and 2.30%Al2O3 using selective magnetic coating was studied. Characterization studies of the low grade ore indicate that besides hematite and goethite, jasper, a microcrystalline form of quartzite, is the major impurity associated with this ore. Beneficiation by conventional magnetic separation technique could yield a magnetic concentrate containing 60.8% Fe with 51% Fe recovery. In order to enhance the recovery of the iron oxide minerals, fine magnetite, colloidal magnetite and oleate colloidal magnetite were used as the coating material. When subjected to magnetic separation, the coated ore produces an iron concentrate containing 60.2% Fe with an enhanced recovery of 56%. The AFM studies indicate that the coagulation of hematite particles with the oleate colloidal magnetite facilitates the higher recovery of iron particles from the low grade BHJ iron ore under appropriate conditions.

  12. Iron isomaltoside 1000: a new intravenous iron for treating iron deficiency in chronic kidney disease

    DEFF Research Database (Denmark)

    Wikström, Björn; Bhandari, Sunil; Barany, Peter;

    2011-01-01

    Patients with chronic kidney disease (CKD) often suffer from iron deficiency anemia necessitating treatment with intravenous iron. This study was designed to assess the safety of iron isomaltoside 1000 (Monofer) in CKD patients. The secondary objective was to assess its effect on iron deficiency...... anemia....

  13. Superconductivity between standard types: Multiband versus single-band materials.

    Energy Technology Data Exchange (ETDEWEB)

    Vagov, A.; Shanenko, A. A.; Milosevic, M. V.; Axt, V. M.; Vinokur, V. M.; Aguiar, J. Albino; Peeters, F. M.

    2016-05-06

    In the nearest vicinity of the critical temperature, types I and II of conventional single-band superconductors interchange at the Ginzburg-Landau parameter κ = 1/√2. At lower temperatures this point unfolds into a narrow but finite interval of κ’s, shaping an intertype (transitional) domain in the (κ,T ) plane. In the present work, based on the extended Ginzburg-Landau formalism, we show that the same picture of the two standard types with the transitional domain in between applies also to multiband superconductors. However, the intertype domain notably widens in the presence of multiple bands and can become extremely large when the system has a significant disparity between the band parameters. It is concluded that many multiband superconductors, such as recently discovered borides and iron-based materials, can belong to the intertype regime.

  14. Evidence for Archean inheritance in the pre-Panafrican crust of Central Cameroon: Insight from zircon internal structure and LA-MC-ICP-MS Usbnd Pb ages

    Science.gov (United States)

    Ganwa, Alembert Alexandre; Klötzli, Urs Stephan; Hauzenberger, Christoph

    2016-08-01

    contributing sources. It is likely that erosion, transport and deposition took place between 2116 and 821 Ma. Geochemical data show that the REE, Y, Yb, Sr/Y of some samples are similar to the known Archean craton formations (depletion in REE, Y ≤ 10 ppm, Yb ≤ 1 ppm, Sr/Y ≥ 30). These characteristics are known as specific for the Archean TTG (Tonalite-Trondhjemite-Granodiorite). It means that: i) Archean TTG contribute significantly to the detritus of the sedimentary basin, ii) The depositional basin and the source rock were close and the detritus was immature. Our results show that the Pre-Panafrican history of central Cameroon includes Meso- to Neo-Archean crustal accretion and associated magmatism prior to the Paleoproterozoic event of the West Central African Belt. In respect to this new insight, any evolutionary reconstruction of the area should integrate the presence of Archean crust.

  15. Effect of Iron Deficiency on Heterocyst Differentiation and Physiology of the Filamentous Cyanobacterium Anabaena sp. PCC 7120

    Institute of Scientific and Technical Information of China (English)

    XuWen-liang; LiuYong-ding; ZhangCheng-cai

    2003-01-01

    The effect of iron deficiency on heterocyst differentiation and some physiological properties of the filamentous cyanobacterium Anabaena sp. PCC 7120 was investigated. Under moderate iron limitation conditions, achieved by addition of iron chelator 2,2′-Dipyridyl (<80 μmol/L) led to delayed heterocyst differentiation,no heterocyst differentiation was observed under severe iron limitation conditions,when the concentration of 2,2′-Dipyridyl in the medium was more than 100 μmol/L.It seemed that there are certain iron-regulated genes or operons whose function is to control heterocyst development. In addition, iron deficiency impaired the growth.Low-iron cells had a decrease in the quantities of pigment content (chlorophyll and phycocyanin content), the whole cell in vivo absorbance spectra confirmed the decrease, the protein electrophoretic profiles revealed that iron-deficient cells had less protein bands, with the increase of 2,2'-Dipyridyl , the protein bands was more and more less. And differently, iron deficiency also caused an increase of ROS (Reactive Oxygen Species)and SOD activity, it suggests that iron deficiency led to oxidative stress, which uenerallv occured under hiuh-iron conditions.

  16. Effect of Iron Deficiency on Heterocyst Differentiation and Physiology of the Filamentous Cyanobacterium Anabaena sp. PCC 7120

    Institute of Scientific and Technical Information of China (English)

    Zhang Cheng-cai

    2003-01-01

    The effect of iron deficiency on heterocyst differentiation and some physiological properties of the filamentous cyanobacterium Anabaena sp. PCC 7120was investigated. Under moderate iron limitation conditions, achieved by addition of iron chelator 2,2′-Dipyridyl (<80 μmol/L) led to delayed heterocyst differentiation,no heterocyst differentiation was observed under severe iron limitation conditions,when the concentration of 2,2′-Dipyridyl in the medium was more than 100 μmol/L.It seemed that there are certain iron-regulated genes or operons whose function is to control heterocyst development. In addition, iron deficiency impaired the growth.Low-iron cells had a decrease in the quantities of pigment content (chlorophyll and phycocyanin content), the whole cell in vivo absorbance spectra confirmed the de crease, the protein electrophoretic profiles revealed that iron-deficient cells had less protein bands, with the increase of 2,2′ Dipyridyl , the protein bands was more and more less. And differently, iron deficiency also caused an increase of ROS (Reactive Oxygen Species)and SOD activity, it suggests that iron deficiency led to oxidative stress, which generally occured under high-iron conditions.

  17. Severe plastic deformation through adiabatic shear banding in Fe-C steels

    Energy Technology Data Exchange (ETDEWEB)

    Lesuer, D; Syn, C; Sherby, O

    2004-12-01

    Severe plastic deformation is observed within adiabatic shear bands in iron-carbon steels. These shear bands form under high strain rate conditions, in excess of 1000 s{sup -1}, and strains in the order 5 or greater are commonly observed. Studies on shear band formation in a ultrahigh carbon steel (1.3%C) are described in the pearlitic condition. A hardness of 11.5 GPa (4600 MPa) is obtained within the band. A mechanism is described to explain the high strength based on phase transformation to austenite from adiabatic heating resulting from severe deformation. Rapid re-transformation leads to an ultra-fine ferrite grain size containing carbon principally in the form of nanosize carbides. It is proposed that the same mechanism explains the ultrahigh strength of iron-carbon steels observed in ball-milling, ball drop tests and in severely deformed wires.

  18. The Moessbauer investigation in iron nitride/expanded graphite

    International Nuclear Information System (INIS)

    We successfully prepared the composites possessed high magnetic properties and shielding effectiveness (SE) in RF band with the methods of loading iron nitride nanoparticles on expanded graphite (EG) by the gaseous reduction and nitridation. XRD measurement shows that the ferric phases changed in different nitridation temperature. The phase components of nanoparticles were analyzed in detail by the measurement of 57Fe Moessbauer spectra. The result shows that as the temperature increased, the Fe particles were gradually nitride until completely before 400℃ and the γ'-Fe4N was gradually converted to ε-FexN (2iron nitride after 400℃. (authors)

  19. Iron Absorption in Drosophila melanogaster

    Directory of Open Access Journals (Sweden)

    Fanis Missirlis

    2013-05-01

    Full Text Available The way in which Drosophila melanogaster acquires iron from the diet remains poorly understood despite iron absorption being of vital significance for larval growth. To describe the process of organismal iron absorption, consideration needs to be given to cellular iron import, storage, export and how intestinal epithelial cells sense and respond to iron availability. Here we review studies on the Divalent Metal Transporter-1 homolog Malvolio (iron import, the recent discovery that Multicopper Oxidase-1 has ferroxidase activity (iron export and the role of ferritin in the process of iron acquisition (iron storage. We also describe what is known about iron regulation in insect cells. We then draw upon knowledge from mammalian iron homeostasis to identify candidate genes in flies. Questions arise from the lack of conservation in Drosophila for key mammalian players, such as ferroportin, hepcidin and all the components of the hemochromatosis-related pathway. Drosophila and other insects also lack erythropoiesis. Thus, systemic iron regulation is likely to be conveyed by different signaling pathways and tissue requirements. The significance of regulating intestinal iron uptake is inferred from reports linking Drosophila developmental, immune, heat-shock and behavioral responses to iron sequestration.

  20. Band-gap measurements of bulk and nanoscale hematite by soft x-ray spectroscopy

    DEFF Research Database (Denmark)

    Gilbert, B.; Frandsen, Cathrine; Maxey, E.R.;

    2009-01-01

    Chemical and photochemical processes at semiconductor surfaces are highly influenced by the size of the band gap, and ability to control the band gap by particle size in nanomaterials is part of their promise. The combination of soft x-ray absorption and emission spectroscopies provides band......-gap determination in bulk and nanoscale itinerant electron semiconductors such as CdS and ZnO, but this approach has not been established for materials such as iron oxides that possess band-edge electronic structure dominated by electron correlations. We performed soft x-ray spectroscopy at the oxygen K-edge to...... reveal band-edge electronic structure of bulk and nanoscale hematite. Good agreement is found between the hematite band gap derived from optical spectroscopy and the energy separation of the first inflection points in the x-ray absorption and emission onset regions. By applying this method to two sizes...

  1. Correlation effects in the iron pnictides

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Jian-xin [Los Alamos National Laboratory; Si, Qimiao [RICE UNIV; Abrahams, Elihu [RUTGERS UNIV; Dai, Jianhui [ZHEJIANG UNIV

    2009-01-01

    One of the central questions about the iron pnictides concerns the extent to which their electrons are strongly correlated. Here we address this issue through the phenomenology of the charge transport and dynamics, single-electron excitation spectrum, and magnetic ordering and dynamics. We outline the evidence that the parent compounds, while metallic, have electron interactions that are sufficiently strong to produce incipient Mott physics. In other words, in terms of the strength of electron correlations compared to the kinetic energy, the iron pnictides are closer to intermediately-coupled systems lying at the boundary between itinerancy and localization, such as V{sub 2}O{sub 3} a or Se-doped NiS{sub 2} , rather than to simple antiferromagnetic metals like Cr. This level of electronic correlations produces a new small parameter for controlled theoretical analyses, namely the fraction of the single-electron spectral weight that lies in the coherent part. Using this expansion parameter, we construct the effective low-energy Hamiltonian and discuss its implications for the magnetic order and magnetic quantum criticality. Finally, this approach sharpens the notion of magnetic frustration for such a metallic system, and brings about a multi band matrix t-J{sub 1}-J{sub 2} model for the carrier-doped iron pnictides.

  2. A juvenile oceanic island arc origin for the Archean (ca. 2.97 Ga) Fiskenæsset anorthosite complex, southwestern Greenland: Evidence from oxygen isotopes

    Science.gov (United States)

    Polat, Ali; Longstaffe, Fred J.

    2014-06-01

    The Archean (ca. 2.97 Ga) Fiskenæsset layered intrusion, southwestern Greenland, consists of an association of anorthosite, leucogabbro, gabbro, hornblendite, pyroxenite, peridotite and dunite. The intrusion is characterized by well-preserved igneous layering, cumulate texture and primary igneous minerals including olivine, pyroxene, plagioclase, hornblende and chromite. We use new whole-rock (n=36) and mineral (n=32) oxygen isotopic data for all major lithologic units from the best preserved stratigraphic section of the Fiskenæsset Complex at Majorqap qâva to revisit geodynamic and petrogenetic hypotheses proposed for the origin of Archean terranes. The Fiskenæsset Complex has modern mantle-like whole-rock O-isotope compositions (δO18=5.8±0.5‰). Average δO18 values increase from peridotite (δO18=5.0‰), through hornblendite (δO18=5.7‰), gabbro (δO18=5.8‰), pyroxene hornblendite (δO18=6.0‰) and leucogabbro (δO18=6.3‰), to anorthosite (δO18=6.3‰). These whole-rock isotopic compositions reflect the approximate modal abundances of olivine (average δO18=4.9‰), hornblende (average δO18=5.7‰), clinopyroxene (average δO18=6.4‰) and plagioclase (average δO18=6.4‰) in each rock type, as a consequence of mineral fractionation in the magma chamber(s). Field relationships and the absence of crustal contamination suggest that the Fiskenæsset Complex formed in an oceanic setting. Subduction zone-like whole-rock trace element signatures and mantle-like δO18 and initial εNd values are consistent with formation of these rocks in a juvenile oceanic island arc setting. Field and geochemical data from the Fiskenæsset region and adjacent terranes suggest that the origin of Archean crust in southwestern Greenland is consistent with Phanerozoic-like plate tectonic processes rather than density-driven sinking, delamination and diapiric processes requiring formation of greenstone belts and anorthosite complexes on pre-existing continental crust

  3. Forging the anthropogenic iron cycle.

    Science.gov (United States)

    Wang, Tao; Müller, Daniel B; Graedel, T E

    2007-07-15

    Metallurgical iron cycles are characterized for four anthropogenic life stages: production, fabrication and manufacturing, use, and waste management and recycling. This analysis is conducted for year 2000 and at three spatial levels: 68 countries and territories, nine world regions, and the planet. Findings include the following: (1) contemporary iron cycles are basically open and substantially dependent on environmental sources and sinks; (2) Asia leads the world regions in iron production and use; Oceania, Latin America and the Caribbean, Africa, and the Commonwealth of Independent States present a highly production-biased iron cycle; (3) purchased scrap contributes a quarter of the global iron and steel production; (4) iron exiting use is three times less than that entering use; (5) about 45% of global iron entering use is devoted to construction, 24% is devoted to transport equipment, and 20% goes to industrial machinery; (6) with respect to international trade of iron ore, iron and steel products, and scrap, 54 out of the 68 countries are net iron importers, while only 14 are net exporters; (7) global iron discharges in tailings, slag, and landfill approximate one-third of the iron mined. Overall, these results provide a foundation for studies of iron-related resource policy, industrial development, and waste and environmental management. PMID:17711233

  4. Iron deficiency and cognitive functions

    Directory of Open Access Journals (Sweden)

    Jáuregui-Lobera I

    2014-11-01

    Full Text Available Ignacio Jáuregui-Lobera Department of Nutrition and Bromatology, Pablo de Olavide University, Seville, Spain Abstract: Micronutrient deficiencies, especially those related to iodine and iron, are linked to different cognitive impairments, as well as to potential long-term behavioral changes. Among the cognitive impairments caused by iron deficiency, those referring to attention span, intelligence, and sensory perception functions are mainly cited, as well as those associated with emotions and behavior, often directly related to the presence of iron deficiency anemia. In addition, iron deficiency without anemia may cause cognitive disturbances. At present, the prevalence of iron deficiency and iron deficiency anemia is 2%–6% among European children. Given the importance of iron deficiency relative to proper cognitive development and the alterations that can persist through adulthood as a result of this deficiency, the objective of this study was to review the current state of knowledge about this health problem. The relevance of iron deficiency and iron deficiency anemia, the distinction between the cognitive consequences of iron deficiency and those affecting specifically cognitive development, and the debate about the utility of iron supplements are the most relevant and controversial topics. Despite there being methodological differences among studies, there is some evidence that iron supplementation improves cognitive functions. Nevertheless, this must be confirmed by means of adequate follow-up studies among different groups. Keywords: iron deficiency, anemia, cognitive functions, supplementation

  5. Iron-Ore Sintering Process Optimization / Optymalizacja Procesu Aglomeracji Rudy Żelaza

    Directory of Open Access Journals (Sweden)

    Fröhlichová M.

    2015-12-01

    Full Text Available The work deals with examination of the influence of the ratio between iron ore concentrate and iron ore on quality of produced iron ore sinter. One of the possibilities to increase iron content in sinter is the modification of raw materials ratio, when iron ore materials are added into sintering mixture. If the ratio is in favor of iron ore sinter, iron content in resulting sintering mixture will be lower. If the ratio is in favor of iron ore concentrate and recycled materials, which is more finegrained, a proportion of a fraction under 0.5 mm will increase, charge permeability property will be reduced, sintering band performance will decrease and an occurrence of solid particulate matter in product of sintering process will rise. The sintering mixture permeability can be optimized by increase of fuel content in charge or increase of sinter charge moisture. A change in ratio between concentrate and iron ore has been experimentally studied. An influence of sintering mixture grain size composition, a charge grains shape on quality and phase composition on quality of the produced iron sinter has been studied.

  6. Electronic and vibrational properties of graphene monolayers with iron adatoms: A density functional theory study

    International Nuclear Information System (INIS)

    Highlights: • Periodic density functional calculations were performed on graphene monolayers with and without an iron adatom. • Densities of states, charge transfers, and overlap populations were used to elucidate the effects of weak iron adsorption on graphene compared to CO adsorption on Pt. • Infrared intensities and normal mode analysis verify weak iron adsorption on graphene by studying the shift in prominent vibrational modes and changes in lattice dynamics. - Abstract: Periodic density functional calculations on graphene monolayers with and without an iron adatom have been used to elucidate iron-graphene adsorption and its effects on graphene electronic and vibrational properties. Density-of-states calculations and charge density contour plots reveal charge transfer from the iron s orbitals to the d orbitals, in agreement with past reports. Adsorbed iron atoms covalently bind to the graphene substrate, verified by the strong hybridization of iron d-states with the graphene bands in the energy region just below the Fermi level. This adsorption is weak and compared to the well-analyzed CO adsorption on Pt: It is indicated by its small adsorption energy and the minimal change of the substrate geometry due to the presence of the iron adatoms. Graphene vibrational spectra are analyzed though a systematic variation of the graphene supercell size. The shifts of graphene most prominent infrared active vibrational modes due to iron adsorption are explored using normal mode eigenvectors

  7. Electronic and vibrational properties of graphene monolayers with iron adatoms: A density functional theory study

    Energy Technology Data Exchange (ETDEWEB)

    Dimakis, Nicholas, E-mail: dimakis@utpa.edu [Department of Physics and Geology, University of Texas-Pan American, Edinburg, TX (United States); Navarro, Nestor E. [Department of Chemistry, University of Texas-Pan American, Edinburg, TX (United States); Velazquez, Julian; Salgado, Andres [Department of Physics and Geology, University of Texas-Pan American, Edinburg, TX (United States)

    2015-04-15

    Highlights: • Periodic density functional calculations were performed on graphene monolayers with and without an iron adatom. • Densities of states, charge transfers, and overlap populations were used to elucidate the effects of weak iron adsorption on graphene compared to CO adsorption on Pt. • Infrared intensities and normal mode analysis verify weak iron adsorption on graphene by studying the shift in prominent vibrational modes and changes in lattice dynamics. - Abstract: Periodic density functional calculations on graphene monolayers with and without an iron adatom have been used to elucidate iron-graphene adsorption and its effects on graphene electronic and vibrational properties. Density-of-states calculations and charge density contour plots reveal charge transfer from the iron s orbitals to the d orbitals, in agreement with past reports. Adsorbed iron atoms covalently bind to the graphene substrate, verified by the strong hybridization of iron d-states with the graphene bands in the energy region just below the Fermi level. This adsorption is weak and compared to the well-analyzed CO adsorption on Pt: It is indicated by its small adsorption energy and the minimal change of the substrate geometry due to the presence of the iron adatoms. Graphene vibrational spectra are analyzed though a systematic variation of the graphene supercell size. The shifts of graphene most prominent infrared active vibrational modes due to iron adsorption are explored using normal mode eigenvectors.

  8. Iron resorption and iron stores in piglets after intramuscular injection of 59Fe-iron dextran

    International Nuclear Information System (INIS)

    Iron resorption from intramuscular injection of an iron dextran complex (Fedex) is almost complete in piglets one week after injection. The excess of resorbed iron is stored in liver and spleen. The stored iron is made available for the growing pig since half of the iron recorded on the 14th day after injection is used during the third week. The remaining iron stores might well be enough to cover the needs for the fourth week also, although it is not absolutely necessary for the pigs at this age. (orig.)

  9. The Irony of Iron – Biogenic Iron Oxides as an Iron Source to the Ocean

    OpenAIRE

    Emerson, David

    2016-01-01

    Primary productivity in at least a third of the sunlit open ocean is thought to be iron-limited. Primary sources of dissolved iron (dFe) to the ocean are hydrothermal venting, flux from the sediments along continental margins, and airborne dust. This article provides a general review of sources of hydrothermal and sedimentary iron to the ocean, and speculates upon the role that iron-cycling microbes play in controlling iron dynamics from these sources. Special attention is paid to iron-oxidiz...

  10. Determination of serum iron and iron binding capacity by NMR

    International Nuclear Information System (INIS)

    The presented data show that NMR can measure serum iron and total iron binding capacity of healthy and the examined pathological cases. The data also suggest that the loss of paramagnetic contribution of serum iron upon the addition of ascorbic acid is detectable by MRI. (author)

  11. Anemia caused by low iron - children

    Science.gov (United States)

    Anemia - iron deficiency - children ... able to absorb iron well, even though the child is eating enough iron Slow blood loss over ... bleeding in the digestive tract Iron deficiency in children can also be related to lead poisoning .

  12. Iron deficiency anemia in children.

    Science.gov (United States)

    Subramaniam, Girish; Girish, Meenakshi

    2015-06-01

    Iron deficiency is not just anemia; it can be responsible for a long list of other manifestations. This topic is of great importance, especially in infancy and early childhood, for a variety of reasons. Firstly, iron need is maximum in this period. Secondly, diet in infancy is usually deficient in iron. Thirdly and most importantly, iron deficiency at this age can result in neurodevelopmental and cognitive deficits, which may not be reversible. Hypochromia and microcytosis in a complete blood count (CBC) makes iron deficiency anemia (IDA) most likely diagnosis. Absence of response to iron should make us look for other differential diagnosis like β thalassemia trait and anemia of chronic disease. Celiac disease is the most important cause of true IDA not responding to oral iron therapy. While oral ferrous sulphate is the cheapest and most effective therapy for IDA, simple nonpharmacological and pharmacological measures can go a long way in prevention of iron deficiency. PMID:25636824

  13. Protein degradation and iron homeostasis.

    Science.gov (United States)

    Thompson, Joel W; Bruick, Richard K

    2012-09-01

    Regulation of both systemic and cellular iron homeostasis requires the capacity to sense iron levels and appropriately modify the expression of iron metabolism genes. These responses are coordinated through the efforts of several key regulatory factors including F-box and Leucine-rich Repeat Protein 5 (FBXL5), Iron Regulatory Proteins (IRPs), Hypoxia Inducible Factor (HIF), and ferroportin. Notably, the stability of each of these proteins is regulated in response to iron. Recent discoveries have greatly advanced our understanding of the molecular mechanisms governing iron-sensing and protein degradation within these pathways. It has become clear that iron's privileged roles in both enzyme catalysis and protein structure contribute to its regulation of protein stability. Moreover, these multiple pathways intersect with one another in larger regulatory networks to maintain iron homeostasis. This article is part of a Special Issue entitled: Cell Biology of Metals. PMID:22349011

  14. Iron prophylaxis during pregnancy -- how much iron is needed? A randomized dose- response study of 20-80 mg ferrous iron daily in pregnant women

    DEFF Research Database (Denmark)

    Milman, Nils; Bergholt, Thomas; Eriksen, Lisbeth;

    2005-01-01

    To determine the lowest dose of iron preventative of iron deficiency and iron deficiency anemia in pregnancy.......To determine the lowest dose of iron preventative of iron deficiency and iron deficiency anemia in pregnancy....

  15. Flat Bands Under Correlated Perturbations

    OpenAIRE

    Bodyfelt, Joshua D.; Leykam, Daniel; Danieli, Carlo; Yu, Xiaoquan; Flach, Sergej

    2014-01-01

    Flat band networks are characterized by coexistence of dispersive and flat bands. Flat bands (FB) are generated by compact localized eigenstates (CLS) with local network symmetries, based on destructive interference. Correlated disorder and quasiperiodic potentials hybridize CLS without additional renormalization, yet with surprising consequencies: (i) states are expelled from the FB energy $E_{FB}$, (ii) the localization length of eigenstates vanishes as $\\xi \\sim 1 / \\ln (E- E_{FB})$, (iii)...

  16. Cluster banding heat source model

    Institute of Scientific and Technical Information of China (English)

    Zhang Liguo; Ji Shude; Yang Jianguo; Fang Hongyuan; Li Yafan

    2006-01-01

    Concept of cluster banding heat source model is put forward for the problem of overmany increment steps in the process of numerical simulation of large welding structures, and expression of cluster banding heat source model is deduced based on energy conservation law.Because the expression of cluster banding heat source model deduced is suitable for random weld width, quantitative analysis of welding stress field for large welding structures which have regular welds can be made quickly.

  17. Development of Wide Band Feeds

    Science.gov (United States)

    Ujihara, H.; Ichikawa, R.

    2012-12-01

    Wide Band feeds are being developed at NICT, NAOJ, and some universities in Japan for VLBI2010, SKA, and MARBLE. SKA, the Square Kilometre Array, will comprise thousands of radio telescopes with square kilometer aperture size for radio astronomy. MARBLE consists of small portable VLBI stations developed at NICT and GSI in Japan. They all need wide band feeds with a greater than 1:10 frequency ratio. Thus we have been studying wide band feeds with dual linear polarization for these applications.

  18. Iron and Pseudomonas aeruginosa biofilm formation

    OpenAIRE

    Banin, Ehud; Vasil, Michael L.; Greenberg, E. Peter

    2005-01-01

    Iron serves as a signal in Pseudomonas aeruginosa biofilm development. We examined the influence of mutations in known and putative iron acquisition-signaling genes on biofilm morphology. In iron-sufficient medium, mutants that cannot obtain iron through the high-affinity pyoverdine iron acquisition system form thin biofilms similar to those formed by the parent under low iron conditions. If an iron source for a different iron acquisition system is provided to a pyoverdine mutant, normal biof...

  19. Iron chelation and multiple sclerosis

    OpenAIRE

    Kelsey J. Weigel; Sharon G. Lynch; Steven M. LeVine

    2014-01-01

    Histochemical and MRI studies have demonstrated that MS (multiple sclerosis) patients have abnormal deposition of iron in both gray and white matter structures. Data is emerging indicating that this iron could partake in pathogenesis by various mechanisms, e.g., promoting the production of reactive oxygen species and enhancing the production of proinflammatory cytokines. Iron chelation therapy could be a viable strategy to block iron-related pathological events or it can confer cellular prote...

  20. Cast iron - a predictable material

    OpenAIRE

    Jorg C. Sturm; Guido Busch

    2011-01-01

    High strength compacted graphite iron (CGI) or alloyed cast iron components are substituting previously used non-ferrous castings in automotive power train applications. The mechanical engineering industry has recognized the value in substituting forged or welded structures with stiff and light-weight cast iron castings. New products such as wind turbines have opened new markets for an entire suite of highly reliable ductile iron cast components. During the last 20 years, casting process s...

  1. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang

    2009-01-01

    @@ Grey Iron(Ⅲ) 2.5 Crystallization of the LTF during final stage of eutectic solidification of grey iron In the final stage of eutectic solidification, eutectic cells grow gradually into large sizes; the liquid iron between the cells enters the last stage of solidification. At this time, the region of the remaining liquid iron is called last to freeze volume, LTF in short, as shown in Fig.2-39.

  2. Granite-hosted molybdenite mineralization from Archean Bundelkhand craton-molybdenite characterization, host rock mineralogy, petrology, and fluid inclusion characteristics of Mo-bearing quartz

    Science.gov (United States)

    Pati, J. K.; Panigrahi, M. K.; Chakarborty, M.

    2014-06-01

    The dominantly high-K, moderate to high SiO2 containing, variably fractionated, volcanic-arc granitoids (± sheared) from parts of Bundelkhand craton, northcentral India are observed to contain molybdenite (Mo) in widely separated 23 locations in the form of specks, pockets, clots and stringers along with quartz ± pyrite ± arsenopyrite ± chalcopyrite ± bornite ± covellite ± galena ± sphalerite and in invisible form as well. The molybdenite mineralization is predominantly associated with Bundelkhand Tectonic Zone, Raksa Shear Zone, and localized shear zones. The incidence of molybdenite is also observed within sheared quartz and tonalite-trondhjemite-granodiorite (TTG) gneisses. The fluid inclusion data show the presence of bi-phase (H2O-CO2), hypersaline and moderate temperature (100°-300°C) primary stretched fluid inclusions suggesting a possible hydrothermal origin for the Mo-bearing quartz occurring within variably deformed different granitoids variants of Archean Bundelkhand craton.

  3. Granite-hosted molybdenite mineralization from Archean Bundelkhand cratonmolybdenite characterization, host rock mineralogy, petrology, and fluid inclusion characteristics of Mo-bearing quartz

    Indian Academy of Sciences (India)

    J K Pati; M K Panigrahi; M Chakarborty

    2014-07-01

    The dominantly high-K, moderate to high SiO2 containing, variably fractionated, volcanic-arc granitoids (± sheared) from parts of Bundelkhand craton, northcentral India are observed to contain molybdenite (Mo) in widely separated 23 locations in the form of specks, pockets, clots and stringers along with quartz ± pyrite ± arsenopyrite ± chalcopyrite ± bornite ± covellite ± galena ± sphalerite and in invisible form as well. The molybdenite mineralization is predominantly associated with Bundelkhand Tectonic Zone, Raksa Shear Zone, and localized shear zones. The incidence of molybdenite is also observed within sheared quartz and tonalite–trondhjemite–granodiorite (TTG) gneisses. The fluid inclusion data show the presence of bi-phase (H2O–CO2), hypersaline and moderate temperature (100°–300°C) primary stretched fluid inclusions suggesting a possible hydrothermal origin for the Mo-bearing quartz occurring within variably deformed different granitoids variants of Archean Bundelkhand craton.

  4. The origin and evolution of sulfur in an Archean volcano-sedimentary basin, Deer Lake area, Minnesota. M.S. Thesis

    Science.gov (United States)

    Nicol, D. L.

    1980-01-01

    Rocks of the Deer Lake area, northcentral Minnesota, consist of Archean (age greater than 2.6 billion years) metasediments and metavolcanics intruded by mafic layered sills. Geologic and sulfur isotopic data suggest that sulfides in the sediments are bacteriogenic, having formed in response to the activity of sulfate reducing bacteria during diagenesis. Deposition of the sediments appears to have occurred in a deep marine basin with restricted circulation of sea water. The bulk of the sulfur in the igneous rocks is of deep seated origin, but basal contacts of the sills show evidence of assimilation of biogenic sulfur from the intruded sediments. This assimilation of biogenic sulfur is the primary geochemical control of local Cu-Ni sulfide mineralization.

  5. Archean and proterozoic in the West-European Hercynian chain: isotopic geochemistry (Sr-Nd-Pb) and U-Pb geochronology on zircons

    International Nuclear Information System (INIS)

    The first part of this research thesis reports the study of isotopic (Sr-Nd-Pb) geochemistry and U-Pb geochronology on zircons in the immersed granulites of the Bay of Biscay: U-Pb geochronology on zircons, Nd isotopic geochemistry, Sr isotopic geochemistry, common Pb, Rb-Sr, Sm-Nd and rare earth data on minerals, comparison with other European granulites, comparison with West-Africa, study of Archean and proterozoic in the Hercynian chain. The second part reports the study of the U-Pb geochronology on zircon in the Cadomian, and the third part addresses the Sr-Nd isotopic geochemistry of some Cadomian granitoid, and the crust contamination in different regions

  6. A biological switch at the ocean surface as a cause of laminations in a Precambrian iron formation

    Science.gov (United States)

    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

  7. Garage Band or GarageBand[R]? Remixing Musical Futures

    Science.gov (United States)

    Vakeva, Lauri

    2010-01-01

    In this paper, I suggest that it is perhaps time to consider the pedagogy of popular music in more extensive terms than conventional rock band practices have to offer. One direction in which this might lead is the expansion of the informal pedagogy based on a "garage band" model to encompass various modes of digital artistry wherever this artistry…

  8. Phytases for improved iron absorption

    DEFF Research Database (Denmark)

    Nielsen, Anne Veller Friis; Meyer, Anne S.

    2016-01-01

    Phytase enzymes present an alternative to iron supplements, because they have been shown to improve iron absorption by means of catalysing the degradation of a potent iron absorption inhibitor: phytic acid. Phytic acid is a hexaphosphate of inositol and is particularly prevalent in cereal grains...

  9. Intracellular iron minerals in a dissimilatory iron-reducing bacterium.

    Science.gov (United States)

    Glasauer, Susan; Langley, Sean; Beveridge, Terry J

    2002-01-01

    Among prokaryotes, there are few examples of controlled mineral formation; the formation of crystalline iron oxides and sulfides [magnetite (Fe3O4) or greigite (Fe3S4)] by magnetotactic bacteria is an exception. Shewanella putrefaciens CN32, a Gram-negative, facultative anaerobic bacterium that is capable of dissimilatory iron reduction, produced microscopic intracellular grains of iron oxide minerals during growth on two-line ferrihydrite in a hydrogen-argon atmosphere. The minerals, formed at iron concentrations found in the soil and sedimentary environments where these bacteria are active, could represent an unexplored pathway for the cycling of iron by bacteria. PMID:11778045

  10. Model calculation of oscillatory magnetic breakdown in metals with multiply degenerate bands

    Science.gov (United States)

    Thalmeier, P.; Falicov, L. M.

    1981-03-01

    We present a model calculation of the oscillatory magnetoresistance in a metal with three degenerate bands. We have in mind the example of body-centered cubic iron where, in the neighborhood of the H point of the Brillouin zone, three bands have multiple intersections and contacts. For magnetic fields along the [011] direction, the Fermi surface in the vicinity of H exhibits a complicated three-band interferometer which leads to complex oscillations in the magnetoresistance. A Fourier analysis of this magnetoresistance reveals that frequencies corresponding to split-beam interference, closed-orbit interference, and mixed type are all present with comparable strength. The connection to the experimental situation is discussed.

  11. Simultaneous confidence bands in linear regression analysis

    OpenAIRE

    Ah-Kine, Pascal Soon Shien

    2010-01-01

    A simultaneous confidence band provides useful information on the plausible range of an unknown regression model. For a simple linear regression model, the most frequently quoted bands in the statistical literature include the two-segment band, the three-segment band and the hyperbolic band, and for a multiple linear regression model, the most com- mon bands in the statistical literature include the hyperbolic band and the constant width band. The optimality criteria for confid...

  12. The Archean komatiite-hosted, PGE-bearing Ni-Cu sulfide deposit at Vaara, eastern Finland: evidence for assimilation of external sulfur and post-depositional desulfurization

    Science.gov (United States)

    Konnunaho, J. P.; Hanski, E. J.; Bekker, A.; Halkoaho, T. A. A.; Hiebert, R. S.; Wing, B. A.

    2013-12-01

    Archean komatiites host important resources of Ni, Cu, Co, and PGE, particularly in Western Australia and Canada. In Finland, several small, low-grade sulfide deposits have been found in komatiites, including the ca. 2.8 Ga Vaara deposit in the Archean Suomussalmi greenstone belt. It occurs in the central part of the serpentinized olivine cumulate zone of a komatiitic extrusive body and is composed of disseminated interstitial sulfides consisting of pyrite, pentlandite, millerite, violarite, and chalcopyrite accompanied by abundant magnetite. Although currently subeconomic, the mineralization is interesting due to the very high chalcophile element contents of the sulfide fraction (38 wt% Ni, 3.4 wt% Cu, 0.7 wt% Co, 22.4 ppm Pd, and 9.5 ppm Pt). The sulfides occur in relatively Cr-poor olivine cumulates suggesting involvement of a chromite-undersaturated magma. The parental magma was an Al-undepleted komatiite with an estimated MgO content of at least 24 wt%. In contrast to the common komatiite types in the eastern Finland greenstone belts, the Vaara rocks are moderately enriched in LREE relative to MREE, suggesting that crustal contamination played an important role in the genesis of the Vaara deposit. Multiple sulfur isotope data reveal considerable mass-independent sulfur isotope fractionation both in country rock sedimentary sulfides (Δ33S ranges from -0.50 to +2.37 ‰) and in the Vaara mineralization (Δ33S ranges from +0.53 to +0.66 ‰), which provides strong evidence for incorporation of crustal sulfur. Extensive replacement of interstitial sulfides by magnetite and the presence of millerite- and violarite-bearing, pyrrhotite-free sulfide assemblages indicate significant post-magmatic, low-temperature hydrothermal oxidation of the primary magmatic pyrrhotite-pentlandite-chalcopyrite assemblages and associated sulfur loss that led to a significant upgrading of the original metal tenors of the Vaara deposit.

  13. Archean Mass-independent Fractionation of Sulfur Isotope:New Evidence of Bedded Sulfide Deposits in the Yanlingguan-Shihezhuang area of Xintai, Shandong Province

    Institute of Scientific and Technical Information of China (English)

    LI Yanhe; HOU Kejun; WAN Defang; YUE Guoliang

    2008-01-01

    Multiple sulfur isotope ratios (34S/33S/32S) of Archean bedded sulfides deposits were measured in the Yanlingguan Formation of the Taishan Group in Xintai, Shandong Province, East of China; δ33S =-0.7‰ to 3.8‰,δ34S = 0.1‰-8.8‰, △33S = -2.3‰ to -0.7‰ The sulfur isotope compositions show obvious mass-independent fractionation (MIF) signatures. The presence of MIF of sulfur isotope in Archean sulfides indicates that the sulfur was from products of photochemical reactions of volcanic SO2 induced by solar UV radiation, implying that the ozone shield was not formed in atmosphere at that time, and the oxygen level was less than 10-5PAL (the present atmosphere level). The sulfate produced by photolysis of SO2 with negative △33S precipitated near the volcanic activity center; and the product of element S with positive △33S precipitated far away from the volcanic activity center. The lower △33S values of sulfide (-2.30‰ to-0.25‰) show that Shihezhuang was near the volcanic center,and sulfur was mostly from sulfate produced by photolysis. The higher △33S values (-0.5‰ to-2‰)indicate that Yanlingguan was far away from the volcanic center and that some of sulfur were from sulfate, another from element S produced by photolysis. The data points of sulfur isotope from Yanlingguan are in a line parallel to MFL (mass dependent fractionation line) on the plot of δ34S-δ33S,showing that the volcanic sulfur species went through the atmospheric cycle into the ocean, and then mass dependent fractionation occurred during deposition of sulfide. The data points of sulfur isotope from Shihezhuang represent a mix of different sulfur source.

  14. Iron oxide modified minerals

    Czech Academy of Sciences Publication Activity Database

    Mashlan, M.; Bartoňková, H.; Jančík, D.; Tuček, J.; Martinec, Petr

    2009-01-01

    Roč. 191, 1-3 (2009), s. 151-157. ISSN 0304-3843 Institutional research plan: CEZ:AV0Z30860518 Keywords : Mössbauer spectroscopy * clay minerals * iron oxide * nanoparticle Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.209, year: 2007 http://www.springerlink.com/content/9870444lu2g66382/fulltext.pdf

  15. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... of red blood cells. Red blood cells carry oxygen and remove carbon dioxide (a waste product) from your body. Anemia ... Hemoglobin is an iron-rich protein that carries oxygen from the lungs to the rest of the ...

  16. State of the iron

    DEFF Research Database (Denmark)

    Reinisch, Walter; Staun, Michael; Bhandari, Sunil;

    2013-01-01

    Iron deficiency anemia (IDA) frequently occurs in patients suffering from inflammatory bowel disease (IBD) and negatively impacts their quality of life. Nevertheless, the condition appears to be both under-diagnosed and undertreated. Regular biochemical screening of patients with IBD for anemia...

  17. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... of red blood cells. Red blood cells carry oxygen and remove carbon dioxide (a waste product) from your body. Anemia also can occur if your red blood cells don't contain enough hemoglobin (HEE-muh-glow-bin). Hemoglobin is an iron-rich protein that carries oxygen from the lungs to the rest of the ...

  18. Iron oxides photochemical dissolution

    International Nuclear Information System (INIS)

    This work was intended to study the light irradiation influence of diverse wave-lengths on iron oxides dissolution in aqueous solutions. The objectives of this work were: the exploration of photochemical processes with the aim of its eventual application in: a) decontamination and chemical cleaning under special conditions; b) materials for solar energy conversion. (Author)

  19. Iron Ore Spies

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    China has begun to attack industrial spies to prevent state security from being compromised Four employees of Rio Tinto, including Hu Shitai, former head of Rio’s Shanghai office and Rio’s China iron ore division, were detained in Shanghai on July 5, on charges of espionage. A senior executive of

  20. Amorphous iron (II) carbonate

    DEFF Research Database (Denmark)

    Sel, Ozlem; Radha, A.V.; Dideriksen, Knud;

    2012-01-01

    Abstract The synthesis, characterization and crystallization energetics of amorphous iron (II) carbonate (AFC) are reported. AFC may form as a precursor for siderite (FeCO3). The enthalpy of crystallization (DHcrys) of AFC is similar to that of amorphous magnesium carbonate (AMC) and more...

  1. Iron dominated magnets

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, G.E.

    1985-07-01

    These two lectures on iron dominated magnets are meant for the student of accelerator science and contain general treatments of the subjects design and construction. The material is arranged in the categories: General Concepts and Cost Considerations, Profile Configuration and Harmonics, Magnetic Measurements, a few examples of ''special magnets'' and Materials and Practices. Extensive literature is provided.

  2. Iron ERRs with Salmonella

    OpenAIRE

    Fang, Ferric C.; Weiss, Günter

    2014-01-01

    The hormone hepcidin promotes iron sequestration by macrophages. A recent study by Kim et al (2014) implicates the orphan receptor ERRγ in the regulation of hepcidin production and suggests that targeting the ERRγ-hepcidin axis may be beneficial during infection with the facultative intracellular pathogen Salmonella.

  3. Development of iron aluminides

    Energy Technology Data Exchange (ETDEWEB)

    Viswanathan, S.; Sikka, V.K.; Andleigh, V.K. [and others

    1995-06-01

    The primary reason for the poor room-temperature ductility of Fe{sub 3}Al-based alloys is generally accepted to be environmental embrittlement due to hydrogen produced by the reaction of aluminum with water vapor present in the test atmosphere. In the as-cast condition, another possible reason for the low room-temperature ductility is the large grain size (0.5 to 3 mm) of the cast material. While recent studies on iron aluminides in the wrought condition have led to higher room-temperature ductility and increased high-temperature strength, limited studies have been conducted on iron aluminides in the as-cast condition. The purpose of this study was to induce grain refinement of the as-cast alloy through alloying additions to the melt and study the effect on room-temperature ductility as measured by the strain corresponding to the maximum stress obtained in a three-point bend test. A base charge of Fe-28% Al-5% Cr alloy was used; as in previous studies this ternary alloy exhibited the highest tensile ductility of several alloys tested. Iron aluminide alloys are being considered for many structural uses, especially for applications where their excellent corrosion resistance is needed. Several alloy compositions developed at ORNL have been licensed to commercial vendors for development of scale-up procedures. With the licensees and other vendors, several applications for iron aluminides are being pursued.

  4. Ironing out warming wrinkles

    International Nuclear Information System (INIS)

    The controversy regarding the fertilization of the ocean with iron to slow down global warming was outlined. The world's oceans absorb up to one-third of annual carbon dioxide released annually from fossil fuels. Some scientists believe they can engineer the oceans to absorb even more carbon if they fertilize them with iron. The iron would promote algae growth which would draw carbon dioxide from the atmosphere. Phytoplankton (algae suspended in the ocean water) convert carbon dioxide into biomass. When the algae die, they would sink to the ocean depths and remain there for thousands of years. Other scientists argue that iron fertilization is not a feasible mitigation tool because not enough is known about the effects of fertilization or the potential ramifications. They argue that some changes of this kind may even accelerate global warming. One beneficial effect resulting from the controversy is that it has drawn attention to the philosophical dimension of massive intervention in the earth's biogeochemical cycles. In this context the question that needs to be answered is: if such a tool for large-scale low-cost manipulation of the earth really becomes available, what framework will be used to make decisions about whether such option should be exercised

  5. Iron Deficiency Anemia

    Directory of Open Access Journals (Sweden)

    Hassan Ahari

    1965-01-01

    Full Text Available The object of this paper is to draw attention to iron deficiency anemia which is the most common nutritional disturbance in infants and children. Iron deficiency anemia constitutes the most prevalent form of anemia in this age group. The records of infants and children admitted to the Pediatric Department of Tehran University Puhlavi Hospital for various ailments during a one year period (Mnrch l!l63 - HHi-t were analyzed. 262 infants and children out of a total number of an5, or 7t•/., showed iron deficiency anemia detect cd by blood film studies and hemoglobin determination, The majority, 123 or 4{.!t•/., of these patients were infants and children between six months and two years of age. The etiology indicates that faulty feeding is the main cause. Infections, parnsitcs, and hemorrhage were among other causes observed. ,'('itll regard to treatment, parenteral iron was preferred because cf its ef., Icctivcncss in short periods of hospital stay. In conclusion, the routine study of blood films and hemoglobin determiualion, especially in the low socio _ economic group of medically less organized countries is advised

  6. Iron dominated magnets

    International Nuclear Information System (INIS)

    These two lectures on iron dominated magnets are meant for the student of accelerator science and contain general treatments of the subjects design and construction. The material is arranged in the categories: General Concepts and Cost Considerations, Profile Configuration and Harmonics, Magnetic Measurements, a few examples of ''special magnets'' and Materials and Practices. Extensive literature is provided

  7. Iron, transferrin and myelinogenesis

    Science.gov (United States)

    Sergeant, C.; Vesvres, M. H.; Devès, G.; Baron, B.; Guillou, F.

    2003-09-01

    Transferrin (Tf), the iron binding protein of vertebrates serum, is known to be synthesized by oligodendrocytes (Ols) in the central nervous system. It has been postulated that Tf is involved in Ols maturation and myelinogenesis. This link is particularly important in the understanding of a severe human pathology: the multiple sclerosis, which remains without efficient treatment. We generated transgenic mice containing the complete human Tf gene and extensive regulatory sequences from the 5 ' and 3 ' untranslated regions that specifically overexpress Tf in Ols. Brain cytoarchitecture of the transgenic mice appears to be normal in all brain regions examined, total myelin content is increased by 30% and motor coordination is significantly improved when compared with non-transgenic littermates. Tf role in the central nervous system may be related to its affinity for metallic cations. Normal and transgenic mice were used for determination of trace metals (iron, copper and zinc) and minerals (potassium and calcium) concentration in cerebellum and corpus callosum. The freeze-dried samples were prepared to allow proton-induced X-ray emission and Rutherford backscattering spectrometry analyses with the nuclear microprobe in Bordeaux. Preliminary results were obtained and carbon distribution was revealed as a very good analysis to distinguish precisely the white matter region. A comparison of metallic and mineral elements contents in brain between normal and transgenic mice shows that iron, copper and zinc levels remained constant. This result provides evidence that effects of Tf overexpression in the brain do not solely relate to iron transport.

  8. Ironing out industrial wastes

    International Nuclear Information System (INIS)

    This article describes a hazardous waste treatment known as the catalytic extraction process, which also stabilizes and reduces low-level radioactive wastes to a fraction of their original volume, easing their disposal. It uses molten iron and other metals to convert hazardous wastes into useful materials

  9. Extracting phosphoric iron under laboratorial conditions smelting bog iron ores

    International Nuclear Information System (INIS)

    In recent years it has been indicated by archaeometric investigations that phosphoric-iron (P-iron, low carbon steel with 0,5-1,5wt% P), which is an unknown and unused kind of steel in the modern industry, was widely used in different parts of the world in medieval times. In this study we try to explore the role of phosphorus in the arhaeometallurgy of iron and answer some questions regarding the smelting bog iron ores with high P-content. XRF analyses were performed on bog iron ores collected in Somogy county. Smelting experiments were carried out on bog iron ores using a laboratory model built on the basis of previously conducted reconstructed smelting experiments in copies of excavated furnaces. The effect of technological parameters on P-content of the resulted iron bloom was studied. OM and SEM-EDS analyses were carried out on the extracted iron and slag samples. On the basis of the material analyses it can be stated that P-iron is usually extracted but the P-content is highly affected by technological parameters. Typical microstructures of P-iron and of slag could also be identified. It could also be established that arsenic usually solved in high content in iron as well

  10. First-principles thermoelasticity of bcc iron under pressure

    OpenAIRE

    Sha, Xianwei; Cohen, R. E.

    2006-01-01

    We investigate the elastic and isotropic aggregate properties of ferromagnetic bcc iron as a function of temperature and pressure by computing the Helmholtz free energies for the volume-conserving strained structures using the first-principles linear response linear-muffin-tin-orbital method and the generalized-gradient approximation. We include the electronic excitation contributions to the free energy from the band structures, and phonon contributions from quasi-harmonic lattice dynamics. W...

  11. The Moral Ends of Band

    Science.gov (United States)

    Allsup, Randall Everett

    2012-01-01

    This article provides a theoretical framework through which to reimagine and revitalize contemporary music education practices, using the large ensemble paradigm called "band" as the primary unit of analysis. Literature suggests that band places too much emphasis on teacher control and external measures of validation. Critics propose replacing…

  12. INTRAVENOUS IRON VERSUS ORAL IRON IN ANTENATAL WOMEN WITH IRON DEFICIENCY ANEMIA IN SUB - HIMALAYAN SETTINGS

    OpenAIRE

    Shraddha; Anup

    2015-01-01

    OBJECTIVE: Compare Intravenous Iron sucrose and Oral Ferrous sulphate in the treatment of iron deficiency anaemia during pregnancy. METHOD: 100 sub - himalayan antenatal women between 12 to 36 weeks gestation from Central Referral Hospital with Iron deficiency anemia; hemoglobin 6 – 9 gm/dl, MCV

  13. Iron-fortified milk can improve iron status in young women with low iron stores

    NARCIS (Netherlands)

    Scholz-Ahrens, K.E.; Schaafsma, G.; Kip, P.; Elbers, F.; Boeing, H.; Schrezenmeir, J.

    2004-01-01

    A considerable proportion of the populations of developing and industrialised nations does not meet the recommended daily allowance for iron and are thus at risk of chronic iron-deficiency anaemia. In a placebo-controlled, double-blind study we investigated whether supplementation with iron-enriched

  14. Iron Deficiency After Roux-en-Y Gastric Bypass: Insufficient Iron Absorption from Oral Iron Supplements

    OpenAIRE

    Gesquiere, Ina; Lannoo, Matthias; Augustijns, Patrick; Matthys, Christophe; Van der Schueren, Bart; Foulon, Veerle

    2014-01-01

    Roux-en-Y gastric bypass (RYGB) may reduce the absorption of iron, but the extent to which this absorption is impeded is largely unknown. First, we determined the prevalence of iron deficiency following RYGB and explored the risk factors for its development. Second, we examined to what extent oral iron supplements are absorbed after RYGB.

  15. 49 CFR 192.373 - Service lines: Cast iron and ductile iron.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Service lines: Cast iron and ductile iron. 192.373... Regulators, and Service Lines § 192.373 Service lines: Cast iron and ductile iron. (a) Cast or ductile iron... cast iron pipe or ductile iron pipe is installed for use as a service line, the part of the...

  16. Iron and cancer: recent insights.

    Science.gov (United States)

    Manz, David H; Blanchette, Nicole L; Paul, Bibbin T; Torti, Frank M; Torti, Suzy V

    2016-03-01

    Iron is an essential dietary element. However, the ability of iron to cycle between oxidized and reduced forms also renders it capable of contributing to free radical formation, which can have deleterious effects, including promutagenic effects that can potentiate tumor formation. Dysregulation of iron metabolism can increase cancer risk and promote tumor growth. Cancer cells exhibit an enhanced dependence on iron relative to their normal counterparts, a phenomenon we have termed iron addiction. Work conducted in the past few years has revealed new cellular processes and mechanisms that deepen our understanding of the link between iron and cancer. Control of iron efflux through the combined action of ferroportin, an iron efflux pump, and its regulator hepcidin appears to play an important role in tumorigenesis. Ferroptosis is a form of iron-dependent cell death involving the production of reactive oxygen species. Specific mechanisms involved in ferroptosis, including depletion of glutathione and inhibition of glutathione peroxidase 4, have been uncovered. Ferritinophagy is a newly identified mechanism for degradation of the iron storage protein ferritin. Perturbations of mechanisms that control transcripts encoding proteins that regulate iron have been observed in cancer cells, including differences in miRNA, methylation, and acetylation. These new insights may ultimately provide new therapeutic opportunities for treating cancer. PMID:26890363

  17. Band structure of 79Br

    International Nuclear Information System (INIS)

    High-spin states of 79Br have been studied in the reaction 76Ge(7Li, 4nγ) at 32 MeV. A gamma-detector array with twelve Compton-suppressed HPGe detectors was used. The positive-parity yrast states, interpreted as a rotationally aligned g(9(2)) proton band, and the negative-parity ground state band have been extended to spins of (33(2+)) and (25(2-)), respectively. Lifetime measurements indicate that both bands have a similar quadrupole deformation of β2 ∼ 0.2. The positive-parity α = -(1(2)) band has been identified. Several new inter-band transitions are observed. A cranked-shell model analysis shows that the νg(9(2)) and πg(9(2)) alignments occur in the positive-parity and the negative-parity bands at rotational frequencies of ℎω ∼ 0.6 and 0.4 MeV, respectively. The level energies and the electromagnetic properties of the g(9(2)) band can be well reproduced by a particle-rotor model calculation with an axially symmetric core

  18. Hepcidin: regulation of the master iron regulator

    OpenAIRE

    2015-01-01

    Iron, an essential nutrient, is required for many diverse biological processes. The absence of a defined pathway to excrete excess iron makes it essential for the body to regulate the amount of iron absorbed; a deficiency could lead to iron deficiency and an excess to iron overload and associated disorders such as anaemia and haemochromatosis respectively. This regulation is mediated by the iron-regulatory hormone hepcidin. Hepcidin binds to the only known iron export protein, ferroportin (FP...

  19. Iron regulation by hepatocytes and free radicals

    OpenAIRE

    Takami, Taro; Sakaida, Isao

    2011-01-01

    Iron is an essential metallic microelement for life. However, iron overload is toxic. The liver serves an important role as a storehouse for iron in the body. About 20–25 mg of iron is required each day for hemoglobin synthesis. To maintain iron homeostasis, transferrin and transferrin receptors are primarily involved in the uptake of iron into hepatocytes, ferritin in its storage, and ferroportin in its export. Moreover, hepcidin controls ferroportin and plays a central role in the iron meta...

  20. Iron pages of HTSC

    International Nuclear Information System (INIS)

    Experimental data are presented on the superconducting and electronic properties of iron-based high-temperature superconductors in the normal and superconducting states. The following topics are discussed: lattice structure; structure of magnetic vortices; magnetic penetration depth; Fermi surface; isotope effect; and critical magnetic fields both in oxide compounds of 1111 type and oxide-free compounds of 122, 111, and 011 types as a function of the doping level, temperature, and external pressure.

  1. Microstrip microwave band gap structures

    Indian Academy of Sciences (India)

    V Subramanian

    2008-04-01

    Microwave band gap structures exhibit certain stop band characteristics based on the periodicity, impedance contrast and effective refractive index contrast. These structures though formed in one-, two- and three-dimensional periodicity, are huge in size. In this paper, microstrip-based microwave band gap structures are formed by removing the substrate material in a periodic manner. This paper also demonstrates that these structures can serve as a non-destructive characterization tool for materials, a duplexor and frequency selective coupler. The paper presents both experimental results and theoretical simulation based on a commercially available finite element methodology for comparison.

  2. Collective bands in superdeformed nuclei

    International Nuclear Information System (INIS)

    The collective properties of excited superdeformed bands have been investigated in the framework of self-consistent cranked Nilsson plus quasiparticle random-phase approximation. The expected octupole nature of some bands observed recently in some nuclei has been confirmed by a comparative analysis of their E1 decays to the yrast band and of the anomalous behavior of their dynamical moment of inertia. It is also shown that the onset of supederformation affects considerably the structure of the giant resonances and greatly enhances the collectivity of the low-lying scissors mode. (author)

  3. Rotational Bands in 172W

    Science.gov (United States)

    Greenberg, J.; Guess, C. J.; Tandel, S.; Chowdhury, P.; Carpenter, M. P.; Hartley, D. J.; Janssens, R. V. F.; Khoo, T. L.; Lauritsen, T.; Lister, C. J.; Seweryniak, D.; Shirwadkar, U.; Wang, X.; Zhu, S.

    2015-10-01

    Studying the structure of rotational bands in 172W is valuable for gaining a better understanding of deformed nuclei. Highly excited states of the isotope were populated from a 230 MeV 50Ti beam incident on a 128Te target at Argonne National Laboratory using the ATLAS accelerator. γ emissions from 172W in the range were measured using Compton suppressed germanium detectors in the Gammasphere array. Using this data, three new rotational bands were found, and several other bands were expanded. Swarthmore College Summer Research Fellowship.

  4. Superparamagnetic iron oxide

    International Nuclear Information System (INIS)

    Superparamagnetic iron oxide (AMI 25) is a promising new contrast agent for imaging the reticuloendothelial-system. Iron oxide crystals possess a large magnetic susceptibility and enhance proton relaxation rates, especially transverse relaxation (T2). In order to guide the clinical utilization of this contrast media 4 patients with malignant lesions of the liver are analyzed before and after slow intravenous administration (20 μmol Fe/kg) of AMI 25. Two magnetic resonance (MR) sequences are performed at different times using 0.35 T magnet. MR signal-to-noise ratio (SNR) of the reticuloendothelial-system (particularly the liver SNR) decrease promptly. The maximum decrease in SNR (67-72 percent for the liver, 46-65 percent for the spleen, 23-41 percent for the bone marrow) is observed 3 h after injection (P<0.01). However, except the peak of contrast enhancement in T1-weighted sequence of splenic tissue, the curve describes a plateau within 30 min and 6 h, allowing a delay between injection and imaging. T2-weighted sequences give a greater contrast-to-noise ratio (CNR) by adding the spontaneous tumor contrast to the effect yielded by AMI 25. These results suggest that images must be acquired between 1 and 6 h after intravenous administration of superparamagnetic iron oxide. (author). 18 refs.; 6 figs

  5. Iron and immunity: immunological consequences of iron deficiency and overload

    OpenAIRE

    Cherayil, Bobby J.

    2010-01-01

    The influence of iron on immune function has been long appreciated. However, the molecular basis for this interaction is less well understood. Recently, there have been several important advances that have shed light on the mechanisms that regulate mammalian iron metabolism. The new insights provide a conceptual framework for understanding and manipulating the cross-talk between iron homeostasis and the immune system. This article will review what is currently known about how disturbances of ...

  6. LDA++ approach to electronic structure of magnets: correlation effects in iron

    OpenAIRE

    Katsnelson, M.I.; Lichtenstein, A. I.

    1998-01-01

    A novel approach to investigation of correlation effects in the electronic structure of magnetic crystals which takes into account a frequency dependence of the self energy (so called ``LDA++ approach'') is developed. The fluctuation exchange approximation is generalized to the spin-polarized multi-band case and its local version is proposed. As an example, we calculate the electronic quasiparticle spectrum of ferromagnetic iron. It is shown that the Fermi liquid description of the bands near...

  7. Analysis of a prehistoric Egyptian iron bead with implications for the use and perception of meteorite iron in ancient Egypt

    Science.gov (United States)

    Johnson, Diane; Tyldesley, Joyce; Lowe, Tristan; Withers, Philip J.; Grady, Monica M.

    2013-06-01

    Tube-shaped beads excavated from grave pits at the prehistoric Gerzeh cemetery, approximately 3300 BCE, represent the earliest known use of iron in Egypt. Using a combination of scanning electron microscopy and micro X-ray microcomputer tomography, we show that microstructural and chemical analysis of a Gerzeh iron bead is consistent with a cold-worked iron meteorite. Thin fragments of parallel bands of taenite within a meteoritic Widmanstätten pattern are present, with structural distortion caused by cold-working. The metal fragments retain their original chemistry of approximately 30 wt% nickel. The bulk of the bead is highly oxidized, with only approximately 2.4% of the total bead volume remaining as metal. Our results show that the first known example of the use of iron in Egypt was produced from a meteorite, its celestial origin having implications for both the perception of meteorite iron by ancient Egyptians and the development of metallurgical knowledge in the Nile Valley.

  8. Some parallel banded system solvers

    Energy Technology Data Exchange (ETDEWEB)

    Dongarra, J.J.; Sameh, A.H.

    1984-12-01

    This paper describes algorithms for solving narrow banded systems and the Helmholtz difference equations that are suitable for multiprocessing systems. The organization of the algorithms highlight the large grain parallelism inherent in the problems. 13 references, 5 tables.

  9. 冀西北晚太古代岩石单元的地质关系:对早期陆壳形成的指示%Geological relation of Late Archean lithologic units in Northwest Hebei, North China Craton: Implication for building of early continental crust

    Institute of Scientific and Technical Information of China (English)

    彭澎; 李云; 刘富; 王芳

    2012-01-01

    the ages of the grey gneisses in this area, field relations clearly show that the Hongqiyingzi Group has formed earlier. In the grey gneiss domain, pieces of the Hongqiyingzi Group and other meta-gabbros appear as sheets, lens or "dyke"-like bands. These lens and bands sometimes have numbers of lined smaller lens around the main bodies, with no fine-grained margins and intrusive branches, which can distinguish from the Paleoproterozoic mafic dykes ( also metamorphosed) in this same area. These gabbroic sheets could be roots or partly the magma chamber relics of the Hongqiyingzi Group, or they could also be partly the remanents of ancient crust. Element and isotope geochemistry show that the volcanics are akin of grey gneisses or dioritic intrusions in the grey gneisses in this area. Both geological relations and geochemistry show that these volcanic rocks may have similar origins with the grey gneisses and dioritic rocks. According to the geological relationships of the Late Archean units in this area, the volcano-sedimentary sequence (the Hongqiyingzi Group) and the grey gneiss complex (Sanggan and Chongli complexes) composed a 2-dimension Late Archean crust structure. Identifying the spatial continuity of such crustal structure, as well as the time and material evolution of the related units, can reveal the forming mechanism of Late Archean continental crust in the North China Craton.

  10. Narrow-Band Microwave Filters

    Directory of Open Access Journals (Sweden)

    A.V. Strizhachenko

    2010-01-01

    Full Text Available Original design of the narrow-band compact filters based on the high-quality waveguide-dielectric resonator with anisotropic materials has been presented in this work. Designed filters satisfy the contradictory requirements: they provide the narrow frequency band (0.05 ÷ 0.1 % of the main frequency f0 and the low initial losses α0 ≤ 1 dB.

  11. Dipole Bands in 196Hg

    International Nuclear Information System (INIS)

    High spin states in 196Hg have been populated in the 198Pt(α,6n) reaction at 65 MeV and the level scheme has been extended. A new dipole band has been observed and a previously observed dipole has been confirmed. Excitation energies, spins and parities of these bands were determined from DCO ratio and linear polarization measurements. Possible quasiparticle excitations responsible for these structures are discussed.

  12. Intestinal Iron Homeostasis and Colon Tumorigenesis

    Directory of Open Access Journals (Sweden)

    Yatrik M. Shah

    2013-06-01

    Full Text Available Colorectal cancer (CRC is the third most common cause of cancer-related deaths in industrialized countries. Understanding the mechanisms of growth and progression of CRC is essential to improve treatment. Iron is an essential nutrient for cell growth. Iron overload caused by hereditary mutations or excess dietary iron uptake has been identified as a risk factor for CRC. Intestinal iron is tightly controlled by iron transporters that are responsible for iron uptake, distribution, and export. Dysregulation of intestinal iron transporters are observed in CRC and lead to iron accumulation in tumors. Intratumoral iron results in oxidative stress, lipid peroxidation, protein modification and DNA damage with consequent promotion of oncogene activation. In addition, excess iron in intestinal tumors may lead to increase in tumor-elicited inflammation and tumor growth. Limiting intratumoral iron through specifically chelating excess intestinal iron or modulating activities of iron transporter may be an attractive therapeutic target for CRC.

  13. The irony of iron -- biogenic iron oxides as an iron source to the ocean

    Directory of Open Access Journals (Sweden)

    David eEmerson

    2016-01-01

    Full Text Available Primary productivity in at least a third of the sunlit open ocean is thought to be iron-limited. Primary sources of dissolved iron (dFe to the ocean are hydrothermal venting, flux from the sediments along continental margins, and airborne dust. This article provides a general review of sources of hydrothermal and sedimentary iron to the ocean, and speculates upon the role that iron-cycling microbes play in controlling iron dynamics from these sources. Special attention is paid to iron-oxidizing bacteria (FeOB that live by oxidizing iron and producing biogenic iron oxides as waste products. The presence and ubiquity of FeOB both at hydrothermal systems and in sediments is only beginning to be appreciated. The biogenic oxides they produce have unique properties that could contribute significantly to the dynamics of dFe in the ocean. Changes in the physical and chemical characteristics of the ocean due to climate change and ocean acidification will undoubtedly impact the microbial iron cycle. A better understanding of the contemporary role of microbes in the iron cycle will help in predicting how these changes could ultimately influence marine primary productivity.

  14. INTRAVENOUS IRON VERSUS ORAL IRON IN ANTENATAL WOMEN WITH IRON DEFICIENCY ANEMIA IN SUB - HIMALAYAN SETTINGS

    Directory of Open Access Journals (Sweden)

    Shraddha

    2015-09-01

    Full Text Available OBJECTIVE: Compare Intravenous Iron sucrose and Oral Ferrous sulphate in the treatment of iron deficiency anaemia during pregnancy. METHOD: 100 sub - himalayan antenatal women between 12 to 36 weeks gestation from Central Referral Hospital with Iron deficiency anemia; hemoglobin 6 – 9 gm/dl, MCV<78fl, MCH <30pg, and serum ferritin <15μg/l; were randomized to receive either 200mg ferrous sulphate tablet twice daily for 6 weeks or receive intravenous ferric hydroxide sucrose complex in water after calculating Total dose infusion. The primary outcome measure was change in hemoglobin, RBC indices, serum ferritin and total serum iron. RESULTS: The mean increase in total serum iron following iron sucrose was 40.20±5.11μg/dl compared to a increase of 33.56±3.39 μg/dl with oral ferrous sulphate, which was statistically highly significant (P< 0.0001. Similarly, the mean increase in serum ferritin with iron sucrose was 31.72 ±10.74μg/dl and with ferrous sulphate being 23.31±4.06 μg/dl which was also statistically highly significant (P<0.001. There was no difference in the increase in hemoglobin, MCV and MCHC between the two groups. CONCLUSION : Though increase in hemoglobin an d RBC indices were not significantly higher with iron sucrose, the main highlight of the study was that iron sucrose significantly increased serum ferritin and serum iron, suggesting that it replenishes iron stores much better than oral iron. Iron sucrose also had a more favourable improvement in clinical features with fewer side - effects , and more effective in later months of pregnancy. This may be of relevance to pregnant mothers residing in difficult Sub - Himalayan terrain.

  15. 俄罗斯白海活动带中的太古宙榴辉岩%Archean eclogites from Belomorian Mobile Belt, Russia

    Institute of Scientific and Technical Information of China (English)

    李小犁; 张立飞; 魏春景

    2013-01-01

    The oldest eclogite outcrops with Archean age were found in Belomorian Mobile Belt in Russia, which is a sharp breakthrough in geology. The Belomorian Mobile Belt is located at the north-east of Archean nucleus of the Fennoscandian shield, in the Belomorian accretionary-collisional orogeny between Kola Peninsula and Karelian craton, which was affected many times by high-moderate-pressure metamorphism and structural deformation in Neoarchean and Paleoproterozoic periods. There are two eclogite-bearing areas, Gridino and Salma. Gidino eclogites include polygenetic Archean eclogite fragments (-2. 72 Ga) with complicated composition, consisting of migmatized and strongly deformed tectonic melange, and various Paleoproterozoic mafic dykes and veins. Salma eclogites were considered to be formed at 2. 87 Ga, and the Fe-Ti-eclogite variety at 2. 8 Ga. The two eclogite assemblages have similar p-T evolution paths in general, and the p-T condition of Gridino eclogite (T= 740 - 865 ℃ , p= 1. 4 - 1. 8 GPa) should be higher than that of Salma eclogites (T≈700 ℃ , p=1. 3 - 1. 4 GPa). The protolith of Salma eclogite might be related with oceanic environment.%在俄罗斯白海活动区发现的迄今为止最古老的太古宙榴辉岩的出露,对整个地质学领域是一次革命性事件.白海活动带位于芬诺斯干地亚地盾东北部太古宙陆核,处于科拉半岛大陆和卡累利阿克拉通之间的太古宙增生碰撞带中,在新太古代和古元古代期间多次受到中高压变质和构造变形作用.榴辉岩出露包括Gridino和Salma两大地区.Gridino榴辉岩区的榴辉岩产状可分为TTG片麻岩围岩中具有复杂成因的太古宙榴辉岩包裹镶体(2.72 Ga),组成强烈构造变形的混合混杂岩体(mélange),以及众多古元古代侵入岩墙岩脉状基性榴辉岩.Salma榴辉岩区的榴辉岩年龄应该晚于2.87 Ga,其中的Fe-Ti-榴辉岩年龄测定为约2.80 Ga.两大榴辉岩区的p-T演化轨迹比较类

  16. Magnetostructural study of iron sucrose

    International Nuclear Information System (INIS)

    Magnetic and structural analyses have been performed on an iron sucrose complex used as a haematinic agent. The system contains two-line ferrihydrite particles of about 5 nm that are superparamagnetic above approximately 50 K. The observed low-temperature magnetic dynamics of this compound is closer to simple models than in the case of other iron-containing drugs for intravenous use like iron dextran

  17. Assessing the Antiquity of Microbial Metal Respiration in the Geologic Record

    Science.gov (United States)

    Craddock, P. R.; Dauphas, N.

    2011-03-01

    We present Fe and C isotope data of Fe-carbonates in Archean banded iron formations (Hamersley, Australia and Isua, Greenland) that support their formation in marine sediments by microbial Fe respiration and record evidence of Fe catabolism at 3.8 Ga.

  18. Iron-Refractory Iron Deficiency Anemia

    Directory of Open Access Journals (Sweden)

    Ebru Yılmaz Keskin

    2015-03-01

    Full Text Available Demir, oksijenin taşınması, DNA sentezi ve hücre çoğalması gibi çeşitli biyolojik reaksiyonlar için vazgeçilmez olduğundan, yaşam için zorunludur. Demir metabolizması ve bu elementin düzenlenmesiyle ilgili bilgilerimiz, son yıllarda belirgin şekilde değişmiştir. Demir metabolizması ile ilgili yeni bozukluklar tanımlanmış ve demirin başka bozuklukların kofaktörü olduğu anlaşılmaya başlamıştır. Hemokromatozis ve demir tedavisine dirençli demir eksikliği anemisi (IRIDA; “iron-refractory iron deficiency anemia” gibi genetik durumlar üzerinde yapılan çalışmalar, vücuttaki demir dengesini kontrol eden moleküler mekanizmalar ile ilgili önemli ipuçları sunmuştur. Bu ilerlemeler, gelecekte, hem genetik hem de kazanılmış demir bozukluklarının daha etkili şekilde tedavi edilmesi amacıyla kullanılabilir. IRIDA, demir eksikliği ile giden durumlarda, hepsidin üretimini baskılayan matriptaz-2’yi kodlayan TMPRSS6 genindeki mutasyonlardan kaynaklanmaktadır. Hastalığın tipik özellikleri, hipokrom, mikrositer anemi, çok düşük ortalama eritrosit hacmi, oral demir tedavisine yanıtsızlık (veya yetersiz yanıt ve parenteral demire kısmi yanıttır. Klasik demir eksikliği anemisinin aksine, serum ferritin değeri genellikle hafif düşük ya da normal aralıkta; serum ve idrar hepsidin değerleri ise, aneminin derecesi ile orantısız şekilde yüksek bulunur. Şimdiye kadar literatürde bildirilmiş olguların sayısı 100’ü geçmediği halde, IRIDA’nın, “atipik” mikrositik anemilerin en sık nedeni olduğu düşünülmektedir. Bu derlemenin amacı, IRIDA hakkındaki güncel bilgileri araştırıcılar ile paylaşmak ve bu alandaki farkındalıklarını arttırmaktır.

  19. Iron and Ferritin Levels in Saliva of Patients with Thalassemia and Iron Deficiency Anemia

    OpenAIRE

    Canatan, Duran; Akdeniz, Sevgi Kosaci

    2012-01-01

    Most of the techniques for measuring iron stores such as serum iron concentration, iron binding capacity, serum ferritin level, liver biopsy can be troublesome or invasive for patients with thalassemia. The salivary iron measurement could be of potential advantage being an easy and non invasive approach for diagnosis of iron deficiency and iron overload . The aim of this study was to compare the levels of iron and ferritin in saliva and serum of patients affected by thalassemia or iron defici...

  20. Iron Imports. III. Transfer of iron from the mucosa into circulation

    OpenAIRE

    Wessling-Resnick, Marianne

    2006-01-01

    Transfer of iron from the mucosa is a critical step in dietary iron assimilation that is tightly regulated to ensure the appropriate amount of iron is absorbed to meet the body's demands. Too much iron is highly toxic, and failure to properly control intestinal iron export causes iron overload associated with hereditary forms of hemochromatosis. One form of genetic iron overload, ferroportin disease, originates due to defects in ferroportin, the membrane iron exporter. Ferroportin acts in con...

  1. Iron in Skin of Mice with Three Etiologies of Systemic Iron Overload

    OpenAIRE

    Adams, Brian D.; Lazova, Rossitza; Andrews, Nancy C.; Milstone, Leonard M

    2005-01-01

    In human hemochromatosis, tissue toxicity is a function of tissue iron levels. Despite reports of skin toxicity in hemochromatosis, little is known about iron levels in skin of individuals with systemic iron overload. We measured skin iron and studied skin histology in three mouse models of systemic iron overload: mice with a deletion of the hemochromatosis (Hfe) gene, mice fed a high iron diet, and mice given parenteral injections of iron. In Hfe−/− mice, iron content in the epidermis and de...

  2. Phytases for Improved Iron Absorption

    DEFF Research Database (Denmark)

    Nielsen, Anne Veller Friis; Nyffenegger, Christian; Meyer, Anne S.

    2014-01-01

    Microbial phytases (EC 3.1.3.8) catalyse dephosphorylation of phytic acid, which is the primary storage compound for phosphorous in cereal kernels. The negatively charged phosphates in phytic acid chelate iron (Fe3+) and thus retards iron bioavailability in humans 1. Supplementation of microbial...... phytase can improve iron absorption from cereal-based diets 2. In order for phytase to catalyse iron release in vivo the phytase must be robust to low pH and proteolysis in the gastric ventricle. Our work has compared the robustness of five different microbial phytases, evaluating thermal stability...

  3. Nd-Sr Isotopic Geochemistry of the Late Archean-Paleoproterozoic Granitoids in the Lüliang-Wutai Terrain, North China Craton,and Implications for Petrogenesis

    Institute of Scientific and Technical Information of China (English)

    CHEN Bin; LIU Shuwen; WANG Rui; CHEN Zhichao; LIU Chaoqun

    2006-01-01

    In this paper we report geochemical and Nd-Sr isotopic data for a late Archean gneissic granitic pluton (Hengling pluton), an early Paleoproterozoic complex (Xipan complex) and a late China, to trace the source of these late Archean-Paleoproterozoic granitoids and, particularly, to understand the nature and mechanism of continental growth at that time. The Hengling granitic gneisses (ca. 2.51 Ga) are characterized by high Na2O and LILEs, TTG-like REE patterns (highly depleted HREE and minor Eu anomalies) and moderately depleted Nd-Sr isotopic compositions (εNd(t)=1.2-2.7, ISr=0.7015-0.7019), and were considered as being products of arc magmatism that was developed upon the North China craton. The Xipan complex (ca. 2.2 Ga) contain gabbroic diorite and monzonite, mostly being Na2O-rich, highly fractionated REE patterns and isotopically enriched (εNd(t)=-1.5 to -4.1, ISr=0.7038-0.706). The gabbroic diorites probably originated from melting of an enriched mantle source, but significantly contaminated by lower crustal material, and the monzonites probably represent a product of a mixture between the gabbroic dioritic magma and granitic melts of crustal origin. The Yunzhongshan post-collisional granitoids (ca. 1.8 Ga) are characterized by high-K affinity and highly-enriched and homogeneous Nd isotopic compositions (εNd(t)=-4.9 to -5.7), although they split into two groups in terms of REE patterns: one group showing elevated HREE (and Sc, Y and Zr)with significant negative Eu anomalies and the other showing highly depleted HREE and, to a lesser extent, mid-REE with negligible Eu anomalies. These granites are genetically related to a process of extensional collapse of a thickened orogen. They formed through magma mixing between mantlederived basaltic magmas and crust-derived granitic melts, followed by significant fractionation of ferromagnesian phases (like hornblende and Cpx) and feldspar and accessory zircons. Some Yunzhongshan granites show very old Nd model ages

  4. A linear Hf isotope-age array despite different granitoid sources and complex Archean geodynamics: Example from the Pietersburg block (South Africa)

    Science.gov (United States)

    Laurent, Oscar; Zeh, Armin

    2015-11-01

    Combined U-Pb and Lu-Hf isotope data from zircon populations are widely used to constrain Hadean-Archean crustal evolution. Linear Hf isotope-age arrays are interpreted to reflect the protracted, internal reworking of crust derived from the (depleted) mantle during a short-lived magmatic event, and related 176Lu/177Hf ratios are used to constrain the composition of the reworked crustal reservoir. Results of this study, however, indicate that Hf isotope-age arrays can also result from complex geodynamic processes and crust-mantle interactions, as shown by U-Pb and Lu-Hf isotope analyses of zircons from well characterized granitoids of the Pietersburg Block (PB), northern Kaapvaal Craton (South Africa). Apart from scarce remnants of Paleoarchean crust, most granitoids of the PB with ages between 2.94 and 2.05 Ga (n = 32) define a straight Hf isotope-age array with low 176Lu/177Hf of 0.0022, although they show a wide compositional range, were derived from various sources and emplaced successively in different geodynamic settings. The crustal evolution occurred in five stages: (I) predominately mafic crust formation in an intra-oceanic environment (3.4-3.0 Ga); (II) voluminous TTG crust formation in an early accretionary orogen (3.0-2.92 Ga); (III) internal TTG crust reworking and subduction of TTG-derived sediments in an Andean-type setting (2.89-2.75 Ga); (IV) (post-)collisional high-K magmatism from both mantle and crustal sources (2.71-2.67 Ga); and (V) alkaline magmatism in an intra-cratonic environment (2.05-2.03 Ga). The inferred array results from voluminous TTG crust formation during stage II, and involvement of this crust during all subsequent stages by two different processes: (i) internal crust reworking through both partial melting and assimilation at 2.89-2.75 Ga, leading to the formation of biotite granites coeval with minor TTGs, and (ii) subduction of TTG-derived sediments underneath the PB, causing enrichment of the mantle that subsequently became

  5. Duodenal mucosal reductase in wild-type and Hfe knockout mice on iron adequate, iron deficient, and iron rich feeding

    OpenAIRE

    Simpson, R.J.; Debnam, E.; Beaumont, N.; Bahram, S; Schümann, K.; Srai, S. K. S.

    2003-01-01

    Background: Genetic haemochromatosis is a common hereditary iron loading disorder in humans. The disease is associated with loss of function mutations in the HFE gene. This is thought to change iron stores via increased iron absorption.

  6. Band loss by nestling mourning doves

    Science.gov (United States)

    Kaczynski, C.F.; Kiel, W.H.

    1963-01-01

    Nestling mourning doves (Zenaidura macroura) were banded and checked for band loss prior to fledging at Parchman, Mississippi, during the months of June-August, 1960. Three hundred seventy-seven nestlings 4-6 days of age were banded, 117 with size 3 bands, 120 with size 3A bands, and 140 with size 3A bands secured by Dalzoflex tape. Two hundred twenty nestlings 7-9 days of age were banded, 114 with size 3 bands and 106 with size 3A bands. In the 4- to 6-day age group, 66.3 percent of the size 3A bands were lost. This was a statistically significant departure from the 7.7 percent loss of size 3 bands. No taped bands were lost. However, predators ate 13.8 percent of the nestlings with taped bands and significantly fewer of the nestlings banded without tape. In the 4- to 6-day age group, percentages of nestlings known to be available for band recovery at 9 days or older were: size 3, 69.2 percent; size 3A with tape, 59.0 percent; size 3A, 25.8 percent. In the 7-to 9-day age group, there was a 3.3 percent loss of size 3A bands and no loss of size 3 bands. The minimum age at which nestlings were banded without subsequent loss of bands was 6 days for size 3 and 8 days for size 3A.

  7. Iron oxide surfaces

    Science.gov (United States)

    Parkinson, Gareth S.

    2016-03-01

    The current status of knowledge regarding the surfaces of the iron oxides, magnetite (Fe3O4), maghemite (γ-Fe2O3), haematite (α-Fe2O3), and wüstite (Fe1-xO) is reviewed. The paper starts with a summary of applications where iron oxide surfaces play a major role, including corrosion, catalysis, spintronics, magnetic nanoparticles (MNPs), biomedicine, photoelectrochemical water splitting and groundwater remediation. The bulk structure and properties are then briefly presented; each compound is based on a close-packed anion lattice, with a different distribution and oxidation state of the Fe cations in interstitial sites. The bulk defect chemistry is dominated by cation vacancies and interstitials (not oxygen vacancies) and this provides the context to understand iron oxide surfaces, which represent the front line in reduction and oxidation processes. Fe diffuses in and out from the bulk in response to the O2 chemical potential, forming sometimes complex intermediate phases at the surface. For example, α-Fe2O3 adopts Fe3O4-like surfaces in reducing conditions, and Fe3O4 adopts Fe1-xO-like structures in further reducing conditions still. It is argued that known bulk defect structures are an excellent starting point in building models for iron oxide surfaces. The atomic-scale structure of the low-index surfaces of iron oxides is the major focus of this review. Fe3O4 is the most studied iron oxide in surface science, primarily because its stability range corresponds nicely to the ultra-high vacuum environment. It is also an electrical conductor, which makes it straightforward to study with the most commonly used surface science methods such as photoemission spectroscopies (XPS, UPS) and scanning tunneling microscopy (STM). The impact of the surfaces on the measurement of bulk properties such as magnetism, the Verwey transition and the (predicted) half-metallicity is discussed. The best understood iron oxide surface at present is probably Fe3O4(100); the structure is

  8. Ab initio downfolding study of the iron-based ladder superconductor BaFe2S3

    Science.gov (United States)

    Arita, Ryotaro; Ikeda, Hiroaki; Sakai, Shiro; Suzuki, Michi-To

    2015-08-01

    Motivated by the recent discovery of superconductivity in the iron-based ladder compound BaFe2S3 under high pressure, we derive low-energy effective Hamiltonians from first principles. We show that the complex band structure around the Fermi level is represented only by the Fe 3 dx z (mixed with 3 dx y ) and 3 dx2-y2 orbitals. The characteristic band degeneracy allows us to construct a four-band model with the band unfolding approach. We also estimate the interaction parameters and show that the system is more correlated than the 1111 family of iron-based superconductors. Provided the superconductivity is mediated by spin fluctuations, the 3 dx z -like band plays an essential role, and the gap function changes its sign between the Fermi surface around the Γ point and that around the Brillouin-zone boundary.

  9. Iron-based superconductivity

    CERN Document Server

    Johnson, Peter D; Yin, Wei-Guo

    2015-01-01

    This volume presents an in-depth review of experimental and theoretical studies on the newly discovered Fe-based superconductors.  Following the Introduction, which places iron-based superconductors in the context of other unconventional superconductors, the book is divided into three sections covering sample growth, experimental characterization, and theoretical understanding.  To understand the complex structure-property relationships of these materials, results from a wide range of experimental techniques and theoretical approaches are described that probe the electronic and magnetic prope

  10. DETERMINATION OF FERRITIN AND HEMOSIDERIN IRON IN PATIENTS WITH NORMAL IRON STORES AND IRON OVERLOAD BY SERUM FERRITIN KINETICS

    OpenAIRE

    Saito, Hiroshi; Tomita, Akihiro; Ohashi, Haruhiko; MAEDA, HIDEAKI; Hayashi, Hisao; Naoe, Tomoki

    2012-01-01

    ABSTRACT We attempted to clarify the storage iron metabolism from the change in the serum ferritin level. We assumed that the nonlinear decrease in serum ferritin was caused by serum ferritin increase in iron mobilization. Under this assumption, we determined both ferritin and hemosiderin iron levels by computer-assisted simulation of the row of decreasing assay-dots of serum ferritin in 11 patients with normal iron stores free of both iron deficiency and iron overload; chronic hepatitis C (C...

  11. Uranium, thorium, gross alpha and gross beta assessment in fountain waters in towns of the Iron Quadrangle, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Claudia A.; Palmieri, Helena E.L.; Menezes, Maria Angela de B.C.; Chaves, Renata D.A.; Dalmazio, Ilza, E-mail: cferreiraquimica@yahoo.com.br, E-mail: help@cdtn.br, E-mail: menezes@cdtn.br, E-mail: rda@cdtn.br, E-mail: id@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2013-07-01

    The Iron Quadrangle region is known worldwide for its diversity, both ores and rock types, which record a long and important period of Earth's history. For thousands of years erosive processes have exposed ancient rocks, Archean and Proterozoic, in this region. The concentration of uranium, thorium, gross alpha and gross beta activities has been assessed in 34 fountains water samples collected from different towns in the Iron Quadrangle. The results obtained were compared to values established by CONAMA nº 396/2008 and Decree nº 2914/2011 by the Ministry of Health. For Th in water consumption there is no value established in the Brazilian legislation and the concentrations in all samples were lower than 0.01 μg L{sup -1}. For uranium, the values ranged from less than 0.002 to 0.61 μg L{sup -1}, and all results were lower than the value allowed of 15 μg L{sup -1} and 30 μg L{sup -1} established by the legislations above, respectively. The results for the radiation levels of gross alpha and gross beta activity in some fountains waters were slightly above the limits (0.5 Bq L{sup -1} and 1.0 Bq L{sup -1}) established by CONAMA nº 396/2008 and Decreet nº 2914/2011, respectively. (author)

  12. Uranium, thorium, gross alpha and gross beta assessment in fountain waters in towns of the Iron Quadrangle, Brazil

    International Nuclear Information System (INIS)

    The Iron Quadrangle region is known worldwide for its diversity, both ores and rock types, which record a long and important period of Earth's history. For thousands of years erosive processes have exposed ancient rocks, Archean and Proterozoic, in this region. The concentration of uranium, thorium, gross alpha and gross beta activities has been assessed in 34 fountains water samples collected from different towns in the Iron Quadrangle. The results obtained were compared to values established by CONAMA nº 396/2008 and Decree nº 2914/2011 by the Ministry of Health. For Th in water consumption there is no value established in the Brazilian legislation and the concentrations in all samples were lower than 0.01 μg L-1. For uranium, the values ranged from less than 0.002 to 0.61 μg L-1, and all results were lower than the value allowed of 15 μg L-1 and 30 μg L-1 established by the legislations above, respectively. The results for the radiation levels of gross alpha and gross beta activity in some fountains waters were slightly above the limits (0.5 Bq L-1 and 1.0 Bq L-1) established by CONAMA nº 396/2008 and Decreet nº 2914/2011, respectively. (author)

  13. Iron is essential for photosynthesis and respiration : iron deficiency

    OpenAIRE

    HEUVELINK, E.; Kierkels, T.

    2016-01-01

    Iron plays a major role in photosynthesis. That’s why a shortage directly affects the production capacity of the plant. The application of chelates has made iron much more easy to absorb. Nevertheless it’s an element that we have to keep an eye on.

  14. Core-shell iron-iron oxide nanoparticles

    DEFF Research Database (Denmark)

    Kuhn, Luise Theil; Bojesen, A.; Timmermann, L.; Fauth, K.; Goering, E.; Johnson, Erik; Nielsen, Martin Meedom; Mørup, Steen

    We present studies of the magnetic properties of core-shell iron-iron oxide nanoparticles. By combining Mossbauer and X-ray absorption spectroscopy we have been able to measure the change from a Fe3O4-like to a gamma-Fe2O3-like composition from the interface to the surface. Furthermore, we have...

  15. Core-shell iron-iron oxide nanoparticles

    DEFF Research Database (Denmark)

    Kuhn, Luise Theil; Bojesen, A.; Timmermann, L.;

    2004-01-01

    We present studies of the magnetic properties of core-shell iron-iron oxide nanoparticles. By combining Mossbauer and X-ray absorption spectroscopy we have been able to measure the change from a Fe3O4-like to a gamma-Fe2O3-like composition from the interface to the surface. Furthermore, we have...

  16. Genetics Home Reference: African iron overload

    Science.gov (United States)

    ... shedding of excess iron through blood loss in menstruation and childbirth. The prevalence of increased iron stores ... is absorbed through the walls of the small intestine. Ferroportin then transports iron from the small intestine ...

  17. Iron-Deficiency Anemia (For Parents)

    Science.gov (United States)

    ... Things to Know About Zika & Pregnancy Iron-Deficiency Anemia KidsHealth > For Parents > Iron-Deficiency Anemia Print A ... common nutritional deficiency in children. About Iron-Deficiency Anemia Every red blood cell in the body contains ...

  18. U/Pb (SHRIMP), 207Pb/206Pb, Rb/Sr, Sm/Nd e K/Ar geochronology of granite-greenstone terrains of Gaviao Block: implications for the Proterozoic and Archean evolution of Sao Francisco Craton, Brazil

    International Nuclear Information System (INIS)

    The Gaviao Block (GB) in the northern portion of the Sao Francisco Craton-Northeast of Brazil, constitutes one of the oldest Archean fragments of the South American Platform Archean crust. GB underwent several events of juvenile accretion and reworking of continental crust along its evolutionary history, notably between the Archean and the Paleoproterozoic. 207Pb/206Pb isotopic analyses were carried out in two zircons populations from strongly migmatized TTG terranes found in the proximity of Brumado: the first population (7 crystals) is taken as representative of the crystallization period of the TTG terranes at 3300 ± 45 Ma; the second (2 crystals) represents the age of the first even of metamorphism/migmatization at 2910 ± 10 Ma. 207 Pb/206 Pb analyses in zircons from an outcrop of non-migmatized TTG in the area yielded a 3202 ± 15 Ma age (4 crystals), interpreted to be the crystallization period of the gneiss protolith. Sm/Nd analyses on the TTG rocks of the Brumado region yielded TDM model ages varying between 3.26 and 3.36 Ga and εNd(t) between -3.5 and +0.7. These data suggest the occurrence of juvenile accretions to the continental crust during the Archean, with differential involvement of crustal materials. The geochemical data of rare earth elements corresponding to the TTG terranes revealed moderate LRRE contents (LaN=83,5), low HREE contents (LaN=2,5) and a fairly fractionated pattern (La/Yb)N=34, besides lack of negative Eu anomaly, showing that these rocks have similar compositions to those TTG terranes of cratonic continents, as well as some Archean rocks from CSF (e.g. Sete Voltas, Boa Vista). Finally, the youngest ages present in GB rocks (ca. 1.2-0.45 Ga) represent the role played by tectono thermal events, which produced partial or total rejuvenation of the Rb/Sr and K/Ar isotopic systems during the Espinhaco and Brasiliano cycles. In particular, K/Ar ages illustrate the effect of younger regional cooling episodes related to the Brasiliano

  19. The case for iron

    International Nuclear Information System (INIS)

    Excess major nutrients occur in offshore areas ranging from the tropical equatorial Pacific to the polar Antarctic. In spite of the great ecological differences in these environments, the authors believe they share a common trait: iron deficiency. Here they present the case of iron; they point out that all of these areas are far from Fe-rich terrestrial sources and that atmospheric dust loads in these regions are among the lowest in the world. The authors summarize experiments performed in three nutrient-rich areas: The Gulf of Alaska, the Ross Sea, and the equatorial Pacific. In general, populations without added Fe doubled at rates 11-40% of the expected maxima at various temperatures. The additions of nanomole quantities of Fe increased these doubling rates by factors of 2-3. In spite of the lack of Fe, tightly coupled phytoplankton/zooplankton communities seem to inhabit these major nutrient-rich areas. Since Fe is required for the synthesis of chlorophyll and nitrate reductase, little chlorophyll is found and NH3 is the favored N source. Normal rate values of specific productivity indicate that these populations are healthy, but limited by the insufficient Fe supply. When Fe becomes available either artificially in bottle experiments or in the environment as Fe-rich land masses are approached, diatoms quickly bloom, chlorophyll levels increase, and nutrient stocks are rapidly depleted. These combined results indicate that Fe availability is the primary factor controlling phytoplankton production in nutrient-rich areas of the open sea

  20. Iron Transport Systems in Neisseria meningitidis†

    OpenAIRE

    Perkins-Balding, Donna; Ratliff-Griffin, Melanie; Stojiljkovic, Igor

    2004-01-01

    Acquisition of iron and iron complexes has long been recognized as a major determinant in the pathogenesis of Neisseria meningitidis. In this review, high-affinity iron uptake systems, which allow meningococci to utilize the human host proteins transferrin, lactoferrin, hemoglobin, and haptoglobin-hemoglobin as sources of essential iron, are described. Classic features of bacterial iron transport systems, such as regulation by the iron-responsive repressor Fur and TonB-dependent transport act...

  1. Iron, Oxidative Stress and Gestational Diabetes

    OpenAIRE

    Taifeng Zhuang; Huijun Han; Zhenyu Yang

    2014-01-01

    Both iron deficiency and hyperglycemia are highly prevalent globally for pregnant women. Iron supplementation is recommended during pregnancy to control iron deficiency. The purposes of the review are to assess the oxidative effects of iron supplementation and the potential relationship between iron nutrition and gestational diabetes. High doses of iron (~relative to 60 mg or more daily for adult humans) can induce lipid peroxidation in vitro and in animal studies. Pharmaceutical doses of iro...

  2. The Role of Hepcidin in Iron Metabolism

    OpenAIRE

    Nemeth, Elizabeta; Ganz, Tomas

    2009-01-01

    Hepcidin is the central regulator of systemic iron homeostasis. Dysregulation of hepcidin production results in a variety of iron disorders. Hepcidin deficiency is the cause of iron overload in hereditary hemochromatosis, iron-loading anemias, and hepatitis C. Hepcidin excess is associated with anemia of inflammation, chronic kidney disease and iron-refractory iron deficiency anemia. Diagnostic and therapeutic applications of this new knowledge are beginning to emerge. Dr. Ernest Beutler play...

  3. Hepcidin and its role in iron absorption

    OpenAIRE

    Robson, K J

    2004-01-01

    Maintaining the correct iron balance is crucial to good health. Disorders of iron homeostasis have a global distribution. As iron is not actively excreted by the body, understanding the role of proteins involved in regulating iron uptake is essential to our understanding of disease involving iron homeostasis. Over the past 10 years, major advances have been made in understanding the genetics of iron metabolism and this has led to identification of a number of new proteins, including hepcidin,...

  4. The cellular mechanisms of body iron homeostasis

    OpenAIRE

    MARCO T NUÑEZ; MARCO A GARATE; MIGUEL ARREDONDO; VICTORIA TAPlA; PATRICIA MUÑOZ

    2000-01-01

    Cells tightly regulate iron levels through the activity of iron regulatory proteins (IRPs) that bind to RNA motifs called iron responsive elements (IREs). When cells become iron-depleted, IRPs bind to IREs present in the mRNAs of ferritin and the transferrin receptor, resulting in diminished translation of the ferritin mRNA and increased translation of the transferrin receptor mRNA. Similarly, body iron homeostasis is maintained through the control of intestinal iron absorption. Intestinal ep...

  5. The complex systematics of zircons in migmatitic gneisses: An example from an Archean migmatite along the Patos Shear Zone, Borborema Province, NE Brazil

    International Nuclear Information System (INIS)

    The Northem Tectonic Domain Borborema Province, in Northeast of Brazil records a complex history of tectonic activity ranging from 3.4 Ga to 0.6 Ga (Brito Neves, 1995 and Dantas, 1996). U-Pb systematics of zircons from a migmatitic gneiss just north of the Patos Shear Zone provide an excellent example of the difficulties encountered using conventional single-grain U/Pb zircon geochronology in polydeformed gneiss terranes. Our conventional single grain zircon analyses of a migmatite yielded Archean ages between ca. 3.3 at 2.8 a, as well as some highly discordant Paleoproterozoic ages. Subsequent cathodoluminescence images of these zircon grains showed complex internal structures that possibly record up to 4 separate stages of zircon growth. With such internal complexity, is impossible resolve primary crystallization ages as well as the ages of subsequent overgrowth events using conventional single grain analyses. Such resolution will require analyses of the individual grain domains using the SHRIMP method (au)

  6. Direct band gap silicon allotropes.

    Science.gov (United States)

    Wang, Qianqian; Xu, Bo; Sun, Jian; Liu, Hanyu; Zhao, Zhisheng; Yu, Dongli; Fan, Changzeng; He, Julong

    2014-07-16

    Elemental silicon has a large impact on the economy of the modern world and is of fundamental importance in the technological field, particularly in solar cell industry. The great demand of society for new clean energy and the shortcomings of the current silicon solar cells are calling for new materials that can make full use of the solar power. In this paper, six metastable allotropes of silicon with direct or quasidirect band gaps of 0.39-1.25 eV are predicted by ab initio calculations at ambient pressure. Five of them possess band gaps within the optimal range for high converting efficiency from solar energy to electric power and also have better optical properties than the Si-I phase. These Si structures with different band gaps could be applied to multiple p-n junction photovoltaic modules. PMID:24971657

  7. X-Band PLL Synthesizer

    Directory of Open Access Journals (Sweden)

    P. Kutin

    2006-04-01

    Full Text Available This paper deals with design and realization of a PLL synthesizer for the microwave X−band. The synthesizer is intended for use as a local oscillator in a K−band downconverter. The design goal was to achieve very low phase noise and spurious free signal with a sufficient power level. For that purpose a low phase noise MMIC VCO was used in phase locked loop. The PLL works at half the output frequency, therefore there is a frequency doubler at the output of the PLL. The output signal from the frequency doubler is filtered by a band-pass filter and finally amplified by a single stage amplifier.

  8. Studies of iron carbon alloys

    International Nuclear Information System (INIS)

    Precipitation of carbon in α iron during a thermal treatment was followed using the magnetic after effect. A study was made of the influence of different parameters such as quenching speed, annealing rate, carbon concentration with or without impurity, irradiation effects. A transient sur-saturation occurs during dissolution of carbon in iron at 500 C. (author)

  9. Iron contamination in silicon technology

    Science.gov (United States)

    Istratov, A. A.; Hieslmair, H.; Weber, E. R.

    This article continues the review of fundamental physical properties of iron and its complexes in silicon (Appl. Phys. A 69, 13 (1999)), and is focused on ongoing applied research of iron in silicon technology. The first section of this article presents an analysis of the effect of iron on devices, including integrated circuits, power devices, and solar cells. Then, sources of unintentional iron contamination and reaction paths of iron during device manufacturing are discussed. Experimental techniques to measure trace contamination levels of iron in silicon, such as minority carrier lifetime techniques (SPV, μ-PCD, and ELYMAT), deep-level transient spectroscopy (DLTS), total X-ray fluorescence (TXRF) and vapor-phase decomposition TXRF (VPD-TXRF), atomic absorption spectroscopy (AAS), mass spectrometry and its modifications (SIMS, SNMS, ICP-MS), and neutron activation analysis (NAA) are reviewed in the second section of the article. Prospective analytical tools, such as heavy-ion backscattering spectroscopy (HIBS) and synchrotron-based X-ray microprobe techniques (XPS, XANES, XRF) are briefly discussed. The third section includes a discussion of the present achievements and challenges of the electrochemistry and physics of cleaning of silicon wafers, with an emphasis on removal of iron contamination from the wafers. Finally, the techniques for gettering of iron are presented.

  10. Hunting for Iron Ore Bargains

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    One of China’s leading steel mills has turned to smaller mines for long-term, lowcost iron ore supplies china’s oldest steel producer is looking to South America to fulfill its iron ore needs in the face of rising prices from

  11. Strain hardening and ductility of iron: axisymmetric vs. plane strain elongation. Technical progress report

    Energy Technology Data Exchange (ETDEWEB)

    Langford, G.

    1979-05-01

    The strain hardening of iron at high strains in plane strain elongation (strip drawing) is shown to fall increasngly below that of drawn iron wires at true strains above 2. This makes it unnecessary to invoke shear band formation simultaneously as a strengthening mechanism and as a ductility reducing mechanism in the drawn strip. Rather, shear bands may be a weakening mechanism in all contexts. A set of specimens of interstitial-free iron deformed in three of the four main classifications of deformation symmetry (wire, strip, and chips, representing axisymmetric elongation, plane strain elongation, and pure shear) has been prepared in the form of mechanical test specimens and thin foils for high resolution selected area diffraction. A simple technique for rapid discovery of the <110> axis of foils of strongly textured bcc wire has been worked out.

  12. Radiolabeled iron in soybeans: intrinsic labeling and bioavailability of iron to rats from defatted flour

    International Nuclear Information System (INIS)

    Soybeans can be efficiently labeled with radiolabeled iron by supplying the iron via a nutrient culture medium as an iron salt or as a chelate. By using dual labeled iron and EDTA, it was determined that none of the chelator was transported to the shoots with the iron. Therefore, the use of chelated iron as the iron source in the nutrient medium should not affect assessments of bioavailability of iron from plants. Bioavailability (determined from whole-body retention curves of 59Fe in rats) of iron from defatted soy flour was relatively high and addition of vitamin C did not significantly enhance absorption of iron from defatted soy flour

  13. Pseudogap and superconductivity in iron-pnictides

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, Hiroaki, E-mail: hiroaki@scphys.kyoto-u.ac.j [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan)

    2010-12-15

    We investigate interplay between magnetic fluctuations and superconductivity in the effective five-band Hubbard model for iron-pnictide superconductors on the basis of the fluctuation-exchange approximation. As for the normal-state properties, we find the pseudogap behavior in the NMR relaxation rate 1/T{sub 1}T in the electron-doped region, while we find strong enhancement of 1/T{sub 1}T in the hole-doped region. Such pseudogap behavior originates from the band structure effect, that is, existence of high density of states just below the Fermi level and its broadening by the correlation effect. Solving the superconducting Eliashberg equation, we find that the most probable candidate for the pairing symmetry is the sign-changing s-wave spin-singlet state. For small exchange coupling J, the eigenvalue is not so sensitive to carrier doping, and seems to be irrelevant with antiferromagnetic (AF) spin fluctuation. We suggest that the orbital degrees of freedom is important as the pairing mechanism as well as the AF spin fluctuation.

  14. Nanocrystalline gadolinium iron garnet for circulator applications

    International Nuclear Information System (INIS)

    Due to high resistivity and low microwave losses, gadolinium iron garnets (GdIG) are useful materials for non-reciprocal devices such as circulators or isolators. Keeping the miniaturization and cost reduction in mind, the trend is to modify the conventional methods of preparation of samples. In this connection we have synthesized nanocystalline GdIG by using the Microwave Hydrothermal method at 160 °C/45 min. As synthesized powders were characterized by using X-ray diffraction (XRD), transmission electron microscopy and Fourier Transform Infrared Spectroscopy. XRD patterns show the formation of a garnet phase with crystallite size varying between 19 nm and 40 nm. Differential Thermal Analysis studies were also carried out on the nanopowders. The powders were densified at a lower sintering temperature of 1100 °C/45 min using a microwave sintering method. The sintered samples were characterized by XRD and atomic force microscopy. The frequency dependence of complex permittivity and ferromagnetic resonance were measured in the Ka band frequency (27–40 GHz). Magnetic properties were also measured at room temperature. - Highlights: ► GdIG ferrites were synthesized using the microwave hydrothermal method. ► Densification of the GdIG samples was done at a low temperature of 1100 °C/45 min. ► Our samples possess low dielectric constant and loss at a Ka band frequency. ► Nanocrystalline GdIG samples for circulator application have been tested.

  15. Iron deficiency in the tropics.

    Science.gov (United States)

    Fleming, A F

    1982-06-01

    Iron in food is classified as belonging to the haem pool, the nonhaem pool, and extraneous sources. Haem iron is derived from vegetable and animal sources with varying bioavailability. Hookworm infestation of the intestinal tract affects 450 million people in the tropics. Schistosoma mansoni caused blood loss in 7 Egyptian patients of 7.5- 25.9 ml/day which is equivalent to a daily loss of iron of .6-7.3 mg daily urinary loss of iron in 9 Egyptian patients. Trichuris trichiura infestation by whipworm is widespread in children with blood loss of 5 ml/day/worm. The etiology of anemia in children besides iron deficiency includes malaria, bacterial or viral infections, folate deficiency and sickle-cell disease. Severe infections cause profound iron-deficiency anemia in children in central American and Malaysia. Plasmodium falciparum malaria-induced anaemia in tropical Africa lowers the mean haemoglobin concentration in the population by 2 g/dI, causing profound anaemia in some. The increased risk of premature delivery, low birthweight, fetal abnormalities, and fetal death is directly related to the degree of maternal anemia. Perinatal mortality was reduced from 38 to 4% in treated anemic mothers. Mental performance was significantly lower in anemic school children and improved after they received iron. Supplements of iron, soy-protein, calcium, and vitamins given to villagers with widespread malnutrition, iron deficiency, and hookworm infestation in Colombia reduced enteric infections in children. Severe iron-deficiency anemia was treated in adults in northern Nigeria by daily in Ferastral 10 ml, which is equivalent to 500 mg of iron per day. Choloroquine, folic acid, rephenium hydroxynaphthoate, and tetrachlorethylene treat adults with severe iron deficiency from hookworm infestation in rural tropical Africa. Blood transfusion is indicated if the patient is dying of anaemia or is pregnant with a haemoglobin concentration 6 gm/dl. In South East Asia, mg per day

  16. The Pharmacokinetics and Pharmacodynamics of Iron Preparations

    Directory of Open Access Journals (Sweden)

    Susanna Burckhardt

    2011-01-01

    Full Text Available Standard approaches are not appropriate when assessing pharmacokinetics of iron supplements due to the ubiquity of endogenous iron, its compartmentalized sites of action, and the complexity of the iron metabolism. The primary site of action of iron is the erythrocyte, and, in contrast to conventional drugs, no drug-receptor interaction takes place. Notably, the process of erythropoiesis, i.e., formation of new erythrocytes, takes 3−4 weeks. Accordingly, serum iron concentration and area under the curve (AUC are clinically irrelevant for assessing iron utilization. Iron can be administered intravenously in the form of polynuclear iron(III-hydroxide complexes with carbohydrate ligands or orally as iron(II (ferrous salts or iron(III (ferric complexes. Several approaches have been employed to study the pharmacodynamics of iron after oral administration. Quantification of iron uptake from radiolabeled preparations by the whole body or the erythrocytes is optimal, but alternatively total iron transfer can be calculated based on known elimination rates and the intrinsic reactivity of individual preparations. Degradation kinetics, and thus the safety, of parenteral iron preparations are directly related to the molecular weight and the stability of the complex. High oral iron doses or rapid release of iron from intravenous iron preparations can saturate the iron transport system, resulting in oxidative stress with adverse clinical and subclinical consequences. Appropriate pharmacokinetics and pharmacodynamics analyses will greatly assist our understanding of the likely contribution of novel preparations to the management of anemia.

  17. Shear Banding of Complex Fluids

    Science.gov (United States)

    Divoux, Thibaut; Fardin, Marc A.; Manneville, Sebastien; Lerouge, Sandra

    2016-01-01

    Even in simple geometries, many complex fluids display nontrivial flow fields, with regions where shear is concentrated. The possibility for such shear banding has been known for several decades, but in recent years, we have seen an upsurge in studies offering an ever-more precise understanding of the phenomenon. The development of new techniques to probe the flow on multiple scales with increasing spatial and temporal resolution has opened the possibility for a synthesis of the many phenomena that could only have been thought of separately before. In this review, we bring together recent research on shear banding in polymeric and soft glassy materials and highlight their similarities and disparities.

  18. Pathology of hepatic iron overload

    Institute of Scientific and Technical Information of China (English)

    Yves Deugnier; Bruno Turlin

    2007-01-01

    Although progress in imaging and genetics allow for a noninvasive diagnosis of most cases of genetic iron overload, liver pathology remains often useful (1) to assess prognosis by grading fibrosis and seeking for associated lesions and (2) to guide the etiological diagnosis, especially when no molecular marker is available.Then, the type of liver siderosis (parenchymal, mesenchymal or mixed) and its distribution throughout the lobule and the liver are useful means for suggesting its etiology: HLA-linked hemochromatosis gene (HFE) hemochromatosis or other rare genetic hemochromatosis,nonhemochromatotic genetic iron overload (ferroportin disease, aceruloplasminemia), or iron overload secondary to excessive iron supply, inflammatory syndrome,noncirrhotic chronic liver diseases including dysmetabolic iron overload syndrome, cirrhosis, and blood disorders.

  19. Instant Noodles and Iron Nutrition

    International Nuclear Information System (INIS)

    Instant noodles represent the biggest category of instant foods in the supermarket. This study was undertaken to determine dietary availability for iron from their varieties without and with an addition of pork and/or vitamin C rich-vegetables by in vitro radiometric (59Fe) method. The results showed that 8 to 13 percent of iron in the noodles was available for absorption of which contributed to 0.79 mg absorbed iron per day. This amount was too low to meet certain requirements for children, adolescents and menstruating women. With added pork or vegetables, iron availability increased by 2 to 3 times, and by 4 times with added pork and collard or cabbage (p<0.001). The amounts as high as 1.5 to 3.4 mg absorbed iron per day can meet the FAO/WHO requirements for most of the high-risk groups

  20. Quantitative analysis of dietary iron utilization for erythropoiesis in response to body iron status.

    Science.gov (United States)

    Matsuo-Tezuka, Yukari; Noguchi-Sasaki, Mariko; Kurasawa, Mitsue; Yorozu, Keigo; Shimonaka, Yasushi

    2016-06-01

    Erythropoiesis requires large amounts of iron for hemoglobin synthesis. There are two sources of iron for erythropoiesis, dietary and stored iron; however, their relative contributions to erythropoiesis remain unknown. In this study, we used the stable iron isotope (57)Fe to quantify synthesis of hemoglobin derived from dietary iron. Using this method, we investigated the activities of dietary iron absorption and the utilization of dietary iron for erythropoiesis in responses to stimulated erythropoiesis and to interventions to alter body iron status. Under iron-loaded conditions, the activity of dietary iron absorption was clearly lowered in response to up-regulation of hepcidin, although the estimated activity of iron release from stored iron was not compared with that under control conditions. This result was supported by the observation that two duodenal iron transporters, divalent metal transporter 1 (DMT1) and ferroportin, were downregulated by iron loading, although the levels of expression of ferroportin in iron storage tissues were not changed by iron loading under erythropoietic stimulation by epoetin-β pegol (C.E.R.A., a long-acting erythropoiesis-stimulating agent). These results indicate that the dietary iron absorption system is more sensitive to body iron status than are reticuloendothelial iron- release mechanisms. Our data indicated that there could be a regulatory mechanism favoring use of stored iron over dietary iron under iron-loaded conditions. PMID:26911670

  1. Iron pnictide superconductors

    International Nuclear Information System (INIS)

    The scope of this dissertation therefore has not only been the synthesis of various new superconducting and non-superconducting iron pnictides of several structural families but also their in-depth crystallographic and physical characterisation. In Chapters 3 - 6, the family of the ZrCuSiAs-type (1111) compounds is subject of discussion. The solid solution series La(CoxFe1-x)PO is analysed regarding magnetic and superconducting properties and the new compounds EuMnPF and REZnPO, as well as the new superconductor parent compound SrFeAsF are presented. Chapters 7 - 9 are dedicated to the new iron arsenide superconductors of the ThCr2Si2-type (122 family). Therein, also the discovery of the first superconductor in this structural family, Ba0.6K0.4Fe2As2, is unveiled. A detailed examination of the complete solid solution series (Ba1-xKx)Fe2As2 is presented. Moreover, the crystallographic phase transitions of the closely related compounds SrFe2As2 and EuFe2As2 are characterised and the superconductors Sr1-xKxFe2As2 and Ca1-xNaxFe2As2 are examined for magnetic and phononic excitations. In Chapter 10, the redetermined crystal structure of the superconductor Fe(Se1-xTex) (11-type) is presented from a chemist's point of view. Chapters 11 - 14 look into the superconducting and non-superconducting iron arsenides of more complex structural families (32522-type and 21311-type). Therein, crystallographic and magnetic details of Sr3Sc2O5Fe2As2 are presented and Ba2ScO3FeAs and Sr2CrO3FeAs, the first two members of the new 21311-type are portrayed. Sr2CrO3FeAs is looked at in close detail with various methods, so e.g. the spin structure of the magnetically ordered compound is solved and a possible reason for the absence of superconductivity in this compound is given. Finally, the superconductor Sr2VO3FeAs is scrutinised and necessary prerequisites for superconductivity in this compound are suggested. (orig.)

  2. Iron biomineralization by anaerobic neutrophilic iron-oxidizing bacteria

    Science.gov (United States)

    Miot, Jennyfer; Benzerara, Karim; Morin, Guillaume; Kappler, Andreas; Bernard, Sylvain; Obst, Martin; Férard, Céline; Skouri-Panet, Fériel; Guigner, Jean-Michel; Posth, Nicole; Galvez, Matthieu; Brown, Gordon E., Jr.; Guyot, François

    2009-02-01

    Minerals formed by bio-oxidation of ferrous iron (Fe(II)) at neutral pH, their association with bacterial ultrastructures as well as their impact on the metabolism of iron-oxidizing bacteria remain poorly understood. Here, we investigated iron biomineralization by the anaerobic nitrate-dependent iron-oxidizing bacterium Acidovorax sp. strain BoFeN1 in the presence of dissolved Fe(II) using electron microscopy and Scanning Transmission X-ray Microscopy (STXM). All detected minerals consisted mainly of amorphous iron phosphates, but based on their morphology and localization, three types of precipitates could be discriminated: (1) mineralized filaments at distance from the cells, (2) globules of 100 ± 25 nm in diameter, at the cell surface and (3) a 40-nm thick mineralized layer within the periplasm. All of those phases were shown to be intimately associated with organic molecules. Periplasmic encrustation was accompanied by an accumulation of protein moieties. In the same way, exopolysaccharides were associated with the extracellular mineralized filaments. The evolution of cell encrustation was followed by TEM over the time course of a culture: cell encrustation proceeded progressively, with rapid precipitation in the periplasm (in a few tens of minutes), followed by the formation of surface-bound globules. Moreover, we frequently observed an asymmetric mineral thickening at the cell poles. In parallel, the evolution of iron oxidation was quantified by STXM: iron both contained in the bacteria and in the extracellular precipitates reached complete oxidation within 6 days. While a progressive oxidation of Fe in the bacteria and in the medium could be observed, spatial redox (oxido-reduction state) heterogeneities were detected at the cell poles and in the extracellular precipitates after 1 day. All these findings provide new information to further the understanding of molecular processes involved in iron biomineralization by anaerobic iron-oxidizing bacteria and

  3. Iron based superconductors: Pnictides versus chalcogenides

    International Nuclear Information System (INIS)

    We present a brief review of the present day situation with studies of high-temperature superconductivity in iron pnictides and chalcogenides. Recent discovery of superconductivity with Tc>30K in AxFe2−x/2Se2 (A=K, Cs, Tl, etc) represents the major new step in the development of new concepts in the physics of Fe-based high-temperature superconductors. We compare LDA and ARPES data on the band structure and Fermi surfaces of novel superconductors and those of the previously studied FeAs superconductors, especially isostructural 122-superconductors like BaFe2As2. It appears that electronic structure of new superconductors is rather different from that of FeAs 122-systems. In particular, no nesting properties of electron and hole-like Fermi surfaces is observed, casting doubts on most popular theoretical schemes of Cooper pairing for these systems. Doping of novel materials is extremely important as a number of topological transitions of Fermi surface near the Γ point in the Brillouin zone are observed for different doping levels. The discovery of Fe vacancies ordering and antiferromagnetic (AFM) ordering at pretty high temperatures (TN>500K), much exceeding superconducting Tc makes these systems unique antiferromagnetic superconductors with highest TN observed up to now. This poses very difficult problems for theoretical understanding of superconductivity. We discuss the role of both vacancies and AFM ordering in transformations of band structure and Fermi surfaces, as well as their importance for superconductivity. In particular, we show that system remains metallic with unfolded Fermi surfaces quite similar to that in paramagnetic state. Superconducting transition temperature Tc of new superconductors is discussed within the general picture of superconductivity in multiple band systems. It is demonstrated that both in FeAs-superconductors and in new FeSe-systems the value of Tc correlates with the value of the total density of states (DOSs) at the Fermi level.

  4. Crystallographic phases and magnetic properties of iron nitride films

    International Nuclear Information System (INIS)

    Iron nitride films, including single phase films of α-FeN (expanded bcc Fe), γ′-Fe4N, ε-Fe3−xN (0 ≤ x ≤ 1), and γ″-FeN, were sputtered onto AlN buffered glass substrates. It was found possible to control the phases in the films merely by changing the nitrogen partial pressure during deposition. The magnetization decreased with increased nitrogen concentration and dropped to zero when the N:Fe ratio was above 0.5. The experimental results, along with spin polarized band calculations, have been used to discuss and analyze the magnetic properties of iron nitrides. It has been demonstrated that in addition to influencing the lattice constant of the various iron nitrides, the nearest N atoms have a significant influence on the exchange splitting of the Fe atoms. Due to the hybridization of Fe-3d and N-2p states, the magnetic moment of Fe atoms decreases with an increase in the number of nearest neighbor nitrogen atoms. - Highlights: • Single phase γ′-Fe4N, ε-Fe3−xN, and γ″-FeN films were obtained using dc sputtering. • The phases in iron nitride films can be controlled by the nitrogen partial pressure. • The nearest N neighbors have a significant influence on the exchange splitting of Fe

  5. PREPARATION AND CHARACTERIZATION OF IRON OXIDE NANOPARTICLES ON DISACCHARIDE TEMPLATES

    Directory of Open Access Journals (Sweden)

    B ANILREDDY

    2013-09-01

    Full Text Available We report here the preparation of nanoparticles of iron oxide in the presence of polysaccharidetemplates. Interaction between iron sulfate and template has been carried out in aqueous phase,followed by the selective and controlled removal of the template to achieve narrow distribution ofparticle size. Particles of iron oxide obtained have been characterized for their stability in solventmedia, size, size distribution and crystallinity and it was found that when the negative value of thezeta potential increases, particle size decreases. A narrow particle size distribution with D100 = 275nm was obtained with chitosan and starch templates. SEM measurements further confirm the particlesize measurement. Diffuse reflectance UV–VIS spectra values show that the template is completelyremoved from the final iron oxide particles and powder XRD measurements show that the peaks ofthe diffractogram are in agreement with the theoretical data of hematite. The salient observations ofour study shows that there occurs a direct correlation between zeta potential, polydispersity index,band gap energy and particle size. The crystallite size of the particles was found to be 30–35 nm. Alarge negative zeta potential was found to be advantageous for achieving lower particle sizes, as theparticles remained discrete without agglomeration.

  6. Weak-coupling superconductivity in a strongly correlated iron pnictide

    Science.gov (United States)

    Charnukha, A.; Post, K. W.; Thirupathaiah, S.; Pröpper, D.; Wurmehl, S.; Roslova, M.; Morozov, I.; Büchner, B.; Yaresko, A. N.; Boris, A. V.; Borisenko, S. V.; Basov, D. N.

    2016-01-01

    Iron-based superconductors have been found to exhibit an intimate interplay of orbital, spin, and lattice degrees of freedom, dramatically affecting their low-energy electronic properties, including superconductivity. Albeit the precise pairing mechanism remains unidentified, several candidate interactions have been suggested to mediate the superconducting pairing, both in the orbital and in the spin channel. Here, we employ optical spectroscopy (OS), angle-resolved photoemission spectroscopy (ARPES), ab initio band-structure, and Eliashberg calculations to show that nearly optimally doped NaFe0.978Co0.022As exhibits some of the strongest orbitally selective electronic correlations in the family of iron pnictides. Unexpectedly, we find that the mass enhancement of itinerant charge carriers in the strongly correlated band is dramatically reduced near the Γ point and attribute this effect to orbital mixing induced by pronounced spin-orbit coupling. Embracing the true band structure allows us to describe all low-energy electronic properties obtained in our experiments with remarkable consistency and demonstrate that superconductivity in this material is rather weak and mediated by spin fluctuations.

  7. Southern Ocean Iron Experiment (SOFex)

    Energy Technology Data Exchange (ETDEWEB)

    Coale, Kenneth H.

    2005-07-28

    The Southern Ocean Iron Experiment (SOFeX) was an experiment decades in the planning. It's implementation was among the most complex ship operations that SIO has been involved in. The SOFeX field expedition was successful in creating and tracking two experimentally enriched areas of the Southern Ocean, one characterized by low silicic acid, one characterized by high silicic acid. Both experimental sites were replete with abundant nitrate. About 100 scientists were involved overall. The major findings of this study were significant in several ways: (1) The productivity of the southern ocean is limited by iron availability. (2) Carbon uptake and flux is therefore controlled by iron availability (3) In spite of low silicic acid, iron promotes non-silicious phytoplankton growth and the uptake of carbon dioxide. (4) The transport of fixed carbon from the surface layers proceeds with a C:N ratio that would indicate differential remineralization of nitrogen at shallow depths. (5) These finding have major implications for modeling of carbon export based on nitrate utilization. (6) The general results of the experiment indicate that, beyond other southern ocean enrichment experiments, iron inputs have a much wider impact of productivity and carbon cycling than previously demonstrated. Scientific presentations: Coale, K., Johnson, K, Buesseler, K., 2002. The SOFeX Group. Eos. Trans. AGU 83(47) OS11A-0199. Coale, K., Johnson, K. Buesseler, K., 2002. SOFeX: Southern Ocean Iron Experiments. Overview and Experimental Design. Eos. Trans. AGU 83 (47) OS22D-01. Buesseler, K.,et al. 2002. Does Iron Fertilization Enhance Carbon Sequestration? Particle flux results from the Southern Ocean Iron Experiment. Eos. Trans. AGU 83 (47), OS22D-09. Johnson, K. et al. 2002. Open Ocean Iron Fertilization Experiments From IronEx-I through SOFeX: What We Know and What We Still Need to Understand. Eos. Trans. AGU 83 (47), OS22D-12. Coale, K. H., 2003. Carbon and Nutrient Cycling During the

  8. Correlations in a band insulator

    Czech Academy of Sciences Publication Activity Database

    Sentef, M.; Kuneš, Jan; Werner, P.; Kampf, A. P.

    2009-01-01

    Roč. 80, č. 15 (2009), 155116/1-155116/7. ISSN 1098-0121 Institutional research plan: CEZ:AV0Z10100521 Keywords : electronic correlations * dynamical mean-field theory * band insulator Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.475, year: 2009

  9. Band structure and nuclear dynamics

    International Nuclear Information System (INIS)

    The relation between the Variable Moment of Inertia model and the Interacting Boson Model are discussed from a phenomenological viewpoint. New results on ground state mean-square radii in nuclei far from stability are reported, and a discussion of band structure extending to high angular momentum states and methods of extracting information on the underlying dynamics is given

  10. Metaphyseal bands in osteogenesis imperfecta

    International Nuclear Information System (INIS)

    An increasing number of patients with osteogenesis imperfecta are undergoing pamidronate therapy to prevent the incidence of fragility fractures. The authors herein report a child aged 3 years who received five cycles of pamidronate, resulting in metaphyseal bands, known as “zebra lines.”

  11. Tolerance bands for functional data.

    Science.gov (United States)

    Rathnayake, Lasitha N; Choudhary, Pankaj K

    2016-06-01

    Often the object of inference in biomedical applications is a range that brackets a given fraction of individual observations in a population. A classical estimate of this range for univariate measurements is a "tolerance interval." This article develops its natural extension for functional measurements, a "tolerance band," and proposes a methodology for constructing its pointwise and simultaneous versions that incorporates both sparse and dense functional data. Assuming that the measurements are observed with noise, the methodology uses functional principal component analysis in a mixed model framework to represent the measurements and employs bootstrapping to approximate the tolerance factors needed for the bands. The proposed bands also account for uncertainty in the principal components decomposition. Simulations show that the methodology has, generally, acceptable performance unless the data are quite sparse and unbalanced, in which case the bands may be somewhat liberal. The methodology is illustrated using two real datasets, a sparse dataset involving CD4 cell counts and a dense dataset involving core body temperatures. PMID:26574904

  12. A PHOTONIC BAND GAP FIBRE

    DEFF Research Database (Denmark)

    1999-01-01

    An optical fibre having a periodicidal cladding structure provididing a photonic band gap structure with superior qualities. The periodical structure being one wherein high index areas are defined and wherein these are separated using a number of methods. One such method is the introduction of...

  13. Band gap ion mass filter

    International Nuclear Information System (INIS)

    Ions in a plasma may be radially separated according to mass using a combination of an axial magnetic field and either a radial or azimuthal electric field. The separation is qualitatively different from that obtained by a plasma centrifuge and the characteristics of confined and unconfined ion orbits are analogous to the phenomenon of band gaps in semiconductors

  14. Evaluation of Ferric and Ferrous Iron Therapies in Women with Iron Deficiency Anaemia

    OpenAIRE

    Ilhami Berber; Halit Diri; Mehmet Ali Erkurt; Ismet Aydogdu; Emin Kaya; Irfan Kuku

    2014-01-01

    Introduction. Different ferric and ferrous iron preparations can be used as oral iron supplements. Our aim was to compare the effects of oral ferric and ferrous iron therapies in women with iron deficiency anaemia. Methods. The present study included 104 women diagnosed with iron deficiency anaemia after evaluation. In the evaluations performed to detect the aetiology underlying the iron deficiency anaemia, it was found and treated. After the detection of the iron deficiency anaemia aetiolog...

  15. Superparamagnetic iron oxide

    International Nuclear Information System (INIS)

    This paper assesses the value of MR imaging of hepatic malignant tumors after injection of different concentrations of superparamagnetic iron oxide (AMI-25) at 1.5 T. Fourteen patients with pathologically proved hepatic malignant tumors were imaged on a 1.5 T magnet. T1-weighted (TR = 400 msec, TE = 20 msec) and T2-weighted (TR = 2,000 msec, TE = 40, 90 msec) sequences were obtained before and 1 hour after intravenous injection of varying concentrations of AMI-25 (10-20 μmol/kg). Signal intensity measurements were obtained from tumor, liver, and background noise. The contrast-to-noise ratio was calculated at the lesion-to-liver signal intensity difference scaled to image noise, including ghost artifacts. Statistical tests were then applied to compare the lesion-to-liver contrast before and after injection

  16. CALCIUM CARBONATE REDUCES IRON ABSORPTION FROM IRON SULFATE, BUT NOT WHEN IRON IS PRESENTED AS AN ORGANIC COMPLEX

    Directory of Open Access Journals (Sweden)

    E. C. CONCEI�O

    2008-09-01

    Full Text Available

    Experimental and epidemiological evidences have demonstrated that calcium inhibits iron absorption; calcium carbonate being one of the most effective calcium sources to reduce iron absorption from dietary origin or from iron sulfate. In the present work, the short-term effect of calcium from calcium carbonate on iron absorption was studied in rats, using different iron compounds (monosodium ferric EDTA, iron-bys-glicine, iron peptide complex with iron sulfate as a control. Eighty (80 animals were divided into groups of 10 animals each with homogeneous weight. After 18h fast, the animals received by gavage 5 mL of a dispersion containing one of the iron compounds (1mg Fe/kg body weight, concomitantly or not with calcium carbonate at a molar ratio of 150:1 (Ca/Fe. Two hours after the administration, the animals were sacrificed and blood was collected for serum iron determination (iron transfer rate from intestinal lumen to blood compartment. Additionally, the intestines were collected for soluble iron determination (available iron. The results demonstrated that calcium ion from calcium carbonate inhibits the iron absorption from iron sulfate, but not from organic iron (di- or trivalent complexes.

  17. Fabrication and electromagnetic characteristics of microwave absorbers containing PPY and carbonyl iron composite

    Energy Technology Data Exchange (ETDEWEB)

    Li Dengao, E-mail: lidengao123@163.com [College of Information Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Wang Hongbin; Zhao Jumin [College of Information Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Yang Xiaoli [Department of Electrical and Computer Engineering, Purdue University Calumet, IN 46323-2094 (United States)

    2011-10-17

    Highlights: {yields} Polypyrrole powders are prepared by in situ polymerization method. {yields} Then PPY-carbonyl iron composite with different mixture ratios have been prepared. {yields} The effect of the mass ratio of PPY-carbonyl iron on the microwave loss properties of the composites is investigated. {yields} A possible microwave absorbing mechanism of PPY-carbonyl iron composite has been proposed. - Abstract: The objective of this study is to develop microwave absorbers using both dielectric and magnetic lossy materials. Polypyrrole (PPY) is used as dielectric lossy materials and carbonyl iron particles is used as magnetic lossy materials. Polypyrrole powders are prepared by in situ polymerization method. Then PPY-carbonyl iron composite with different mixture ratios have been prepared by as-prepared material. The structure, morphology and properties of the composites are characterized with IR, XRD, scanning electron microscope (SEM), Net-work Anlyzer. The complex permittivity ({epsilon}{sup '}{sub r}-j{epsilon}{sup ''}{sub r}) and reflection loss (dB) of the composites have been measured at different microwave frequencies in S-band and C-band (30-6000 MHz) employing vector network analyzer model HP 8722ET vector. The effect of the mass ratio of PPY-carbonyl iron on the microwave loss properties of the composites is investigated. A possible microwave absorbing mechanism of PPY-carbonyl iron composite has been proposed. The PPY-carbonyl iron composite can find applications in suppression of electromagnetic interference (EMI), and reduction of radar signature.

  18. Synthesis of nanocrystalline iron oxide ultrathin films by thermal decomposition of iron nitropruside: Structural and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Bhar, Sanjib Kumar [Department of Chemistry, Vivekananda College, Thakurpukur, Kolkata 700063 (India); Mukherjee, Nillohit; Maji, Swarup Kumar; Adhikary, Bibhutosh [Department of Chemistry, Bengal Engineering and Science University, Shibpur, Howrah 711103 (India); Mondal, Anup, E-mail: anupmondal2000@yahoo.co.in [Department of Chemistry, Bengal Engineering and Science University, Shibpur, Howrah 711103 (India)

    2010-12-15

    Ultrathin films of nanocrystalline {alpha}-Fe{sub 2}O{sub 3} have been deposited on glass substrates from an inorganic precursor, iron nitropruside. This is a novel route of synthesis for iron oxide thin films on glass substrates, by annealing the precursor thin film in air at 650 {sup o}C for 15 min. The films were characterized using TG-DTA analysis, X-ray diffraction, UV-visible, FESEM, AFM and Raman measurements. X-ray diffraction and Raman analyses revealed that the deposited films contain {alpha}-phase of Fe{sub 2}O{sub 3} (hematite). The synthetic route described here provides a very simple and cost-effective method to deposit {alpha}-Fe{sub 2}O{sub 3} thin films on glass substrates with band gap energy of about 2.75 eV. The deposited films were found to show catalytic effect for the photo-degradation of phenol.

  19. Monoclonal antibodies against the iron regulated outer membrane Proteins of Acinetobacter baumannii are bactericidal

    Directory of Open Access Journals (Sweden)

    Goel Vikas

    2001-08-01

    Full Text Available Abstract Background Iron is an important nutrient required by all forms of life.In the case of human hosts,the free iron availability is 10-18M,which is far less than what is needed for the survival of the invading bacterial pathogen.To survive in such conditions, bacteria express new proteins in their outer membrane and also secrete iron chelators called siderophores. Results/ Discussion Acinetobacter baumannii ATCC 19606, a nosocomial pathogen which grows under iron restricted conditions, expresses four new outer membrane proteins,with molecular weight ranging from 77 kDa to 88 kDa, that are called Iron Regulated Outer Membrane Proteins (IROMPs. We studied the functional and immunological properties of IROMPs expressed by A.baumanii ATCC 19606.The bands corresponding to IROMPs were eluted from SDS-PAGE and were used to immunize BALB/c mice for the production of monoclonal antibodies. Hybridomas secreting specific antibodies against these IROMPs were selected after screening by ELISA and their reactivity was confirmed by Western Blot. The antibodies then generated belonged to IgM isotype and showed bactericidical and opsonising activities against A.baumanii in vitro.These antibodies also blocked siderophore mediated iron uptake via IROMPs in bacteria. Conclusion This proves that iron uptake via IROMPs,which is mediated through siderophores,may have an important role in the survival of A.baumanii inside the host,and helps establishing the infection.

  20. Hydrolysis of soybean protein improves iron bioavailability

    Science.gov (United States)

    Iron is an important trace metal element in human body. Iron deficiency affects human health, especially pregnant women and children. Soybean protein is a popular food in Asia and can contain a high amount of iron (145.70±0.74 ug/g); however, it is usually reported as an inhibitor of iron absorption...

  1. Iron loss analysis in linear dc motor

    Energy Technology Data Exchange (ETDEWEB)

    Hippner, M.; Yamada, H.; Mizuno, T.

    1999-09-01

    The paper presents analysis of iron loss in a linear dc motor with a solid iron core. The analysis is based on a finite element magnetic field solution. The influence of magnetic bias on the iron loss is discussed. The results of the iron loss calculations are verified experimentally.

  2. Iron Biofortification of Modern Wheat Cultivar

    DEFF Research Database (Denmark)

    Shirvanehdeh, Behrooz Darbani; Brinch-Pedersen, Henrik; Tauris, Birgitte;

    2011-01-01

    an iron storage complex. Primary evaluation of Bobwhite cv. has approved that endosperm expression of wheat’s own ferritin, works as a sink for iron and accumulates two to three folds more iron in the endosperm. To bring the bioavailable iron on the people's tables, modern cultivars were applied for...

  3. Assessment of polyphase sintered iron-cobalt-iron boride cermets

    International Nuclear Information System (INIS)

    Sintering of iron, cobalt and boron powders has been analysed. As a result iron-iron boride, Fe-Fe2B and iron/cobalt boride with a slight admixture of molybdenum, Fe - Co - (FeMoCo)2B cermets have been produced. Iron was introduced to the mixture as the Astalloy Mo Hoeganaes grade powder. Elemental amorphous boron powder was used, and formation of borides occurred both during heating and isothermal sintering periods causing dimensional changes of the sintered body. Dilatometry was chosen to control basic phenomena taking place during multiphase sintering of investigated systems. The microstructure and phase constituents of sintered compacts were controlled as well. The cermets produced were substituted to: metallographic tests, X-ray analysis, measurements of hardness and of microhardness, and of wear in the process of sliding dry friction. Cermets are made up of two phases; hard grains of iron - cobalt boride, (FeCo)2B (1800 HV) constituting the reinforcement and a relatively soft and plastic eutectic mixture Fe2B - Co (400-500 HV) constituting the matrix. (author)

  4. Lithophile and siderophile element systematics of Earth's mantle at the Archean-Proterozoic boundary: Evidence from 2.4 Ga komatiites

    Science.gov (United States)

    Puchtel, I. S.; Touboul, M.; Blichert-Toft, J.; Walker, R. J.; Brandon, A. D.; Nicklas, R. W.; Kulikov, V. S.; Samsonov, A. V.

    2016-05-01

    likely ancient mafic crust. The large positive 182W anomaly present in the tonalites requires that the precursor crust incorporated a primordial component with Hf/W that became fractionated, relative to the bulk mantle, within the first 50 Ma of Solar System history. The absolute HSE abundances in the mantle source of the Vetreny komatiite system are estimated to be 66 ± 7% of those in the present-day Bulk Silicate Earth. This observation, coupled with the normal 182W/184W composition of the komatiitic basalts, when corrected for crustal contamination (μ182W = -0.5 ± 4.5 ppm), indicates that the W-HSE systematics of the Vetreny komatiite system most likely were established as a result of late accretion of chondritic material to Earth. Our present results, combined with isotopic and chemical data available for other early and late Archean komatiite systems, are inconsistent with the model of increasing HSE abundances in komatiitic sources as a result of slow downward mixing into the mantle of chondritic material accreted to Earth throughout the Archean. The observed HSE concentration variations rather reflect sluggish mixing of diverse post-magma ocean domains characterized by variably-fractionated lithophile and siderophile element abundances.

  5. Re-Os ages for Archean molybdenite and pyrite, Kuittila-Kivisuo, Finland and Proterozoic molybdenite, Kabeliai, Lithuania: Testing the chronometer in a metamorphic and metasomatic setting

    Science.gov (United States)

    Stein, H.J.; Sundblad, K.; Markey, R.J.; Morgan, J.W.; Motuza, G.

    1998-01-01

    that the Re-Os isotopic system in pyrite has been reset on the millimeter scale and that the 21 ppt 187Os intercept reflects the in situ decay of 187Re during the ~160 to 170 m.y. interval from ~2778 Ma (time of molybdenite ?? pyrite deposition) to ~2607 Ma (time of pyrite resetting). When the Re-Os data for molybdenites from the nearby Kivisuo prospect are plotted together with the Kuittila molybdenite and pyrite data, a well-constrained five-point isochron with an age of 2780 ?? 8 Ma and a 187Os intercept (-2.4 ?? 3.8 ppt) of essentially zero results (MSWD = 1.5). We suggest that the pyrite isochron age records a regional metamorphic and/or hydrothermal event, possibly the time of Au mineralization. A proposed Re-Os age of ~2607 Ma for Au mineralization is in good agreement with radiometric ages by other methods that address the timing of Archean Au mineralization in deposits worldwide (so-called 'late Au model'). Molybdenite, in contrast, provides a robust Re-Os chronometer, retaining its original formation age of ~2780 Ma, despite subsequent metamorphic disturbances in Archean and Proterozoic time.

  6. Iron shielded MRI optimization

    Science.gov (United States)

    Borghi, C. A.; Fabbri, M.

    1998-09-01

    The design of the main current systems of an actively shielded and of an iron shielded MRI device for nuclear resonance imaging, is considered. The model for the analysis of the magnetic induction produced by the current system, is based on the combination of a Boundary Element technique and of the integration of two Fredholm integral equations of the first and the second kind. The equivalent current magnetization model is used for the calculation of the magnetization produced by the iron shield. High field uniformity in a spherical region inside the device, and a low stray field in the neighborhood of the device are required. In order to meet the design requirements a multi-objective global minimization problem is solved. The minimization method is based on the combination of the filled function technique and the (1+1) evolution strategy algorithm. The multi-objective problem is treated by means of a penalty method. The actively shielded MRI system results to utilize larger amount of conductor and produce higher magnetic energy than the iron shield device. On veut étudier le projet du système des courants principaux d'un MRI à écran en fer et d'un MRI à écran actif. Le modèle d'analyse du champ magnétique produit par le système de courants est basé sur la combinaison d'une technique Boundary Element et de l'intégration de deux équations intégrales de Fredholm de première et de seconde sorte. On utilise pour calculer la magnétisation produite par l'écran en fer le modèle à cou rants de magné ti sa tion équivalents. On exige une élévation uniforme du champ dans une région sphérique au cœur de l'appareil et un bas champ magnétique dispersé à proximité de l'appareil. Dans le but de répondre aux impératifs du projet, on va résoudre un problème multiobjectif de minimisation globale. On utilise une technique de minimisation obtenue par la combinaison des méthodes “Filled Function” et “(1+1) Evolution Strategy”. Le probl

  7. Iron pnictide superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Tegel, Marcus Christian

    2011-03-22

    The scope of this dissertation therefore has not only been the synthesis of various new superconducting and non-superconducting iron pnictides of several structural families but also their in-depth crystallographic and physical characterisation. In Chapters 3 - 6, the family of the ZrCuSiAs-type (1111) compounds is subject of discussion. The solid solution series La(Co{sub x}Fe{sub 1-x})PO is analysed regarding magnetic and superconducting properties and the new compounds EuMnPF and REZnPO, as well as the new superconductor parent compound SrFeAsF are presented. Chapters 7 - 9 are dedicated to the new iron arsenide superconductors of the ThCr{sub 2}Si{sub 2}-type (122 family). Therein, also the discovery of the first superconductor in this structural family, Ba{sub 0.6}K{sub 0.4}Fe{sub 2}As{sub 2}, is unveiled. A detailed examination of the complete solid solution series (Ba{sub 1-x}K{sub x})Fe{sub 2}As{sub 2} is presented. Moreover, the crystallographic phase transitions of the closely related compounds SrFe{sub 2}As{sub 2} and EuFe{sub 2}As{sub 2} are characterised and the superconductors Sr{sub 1-x}K{sub x}Fe{sub 2}As{sub 2} and Ca{sub 1-x}Na{sub x}Fe{sub 2}As{sub 2} are examined for magnetic and phononic excitations. In Chapter 10, the redetermined crystal structure of the superconductor Fe(Se{sub 1-x}Te{sub x}) (11-type) is presented from a chemist's point of view. Chapters 11 - 14 look into the superconducting and non-superconducting iron arsenides of more complex structural families (32522-type and 21311-type). Therein, crystallographic and magnetic details of Sr{sub 3}Sc{sub 2}O{sub 5}Fe{sub 2}As{sub 2} are presented and Ba{sub 2}ScO{sub 3}FeAs and Sr{sub 2}CrO{sub 3}FeAs, the first two members of the new 21311-type are portrayed. Sr{sub 2}CrO{sub 3}FeAs is looked at in close detail with various methods, so e.g. the spin structure of the magnetically ordered compound is solved and a possible reason for the absence of superconductivity in this compound

  8. Linear methods in band theory

    DEFF Research Database (Denmark)

    Andersen, O. Krogh

    1975-01-01

    Two approximate methods for solving the band-structure problem in an efficient and physically transparent way are presented and discussed in detail. The variational principle for the one-electron Hamiltonian is used in both schemes, and the trial functions are linear combinations of energy......-independent augmented plane waves (APW) and muffin-tin orbitals (MTO), respectively. The secular equations are therefore eigenvalue equations, linear in energy. The trial functions are defined with respect to a muffin-tin (MT) potential and the energy bands depend on the potential in the spheres through potential...... parameters which describe the energy dependence of the logarithmic derivatives. Inside the spheres, the energy-independent APW is that linear combination of an exact solution, at the arbitrary but fixed energy Eν, and its energy derivative which matches continuously and differentiably onto the plane...

  9. ALMA Band 5 Cartridge Performance

    Science.gov (United States)

    Billade, Bhushan; Lapkin, I.; Nystrom, O.; Sundin, E.; Fredrixon, M.; Finger, R.; Rashid, H.; Desmaris, V.; Meledin, D.; Pavolotsky, A.; Belitsky, Victor

    2010-03-01

    Work presented here concerns the design and performance of the ALMA Band 5 cold cartridge, one of the 10 frequency channels of ALMA project, a radio interferometer under construction at Atacama Desert in Chile. The Band 5 cartridge is a dual polarization receiver with the polarization separation performed by orthomode transducer (OMT). For each polarization, Band 5 receiver employs sideband rejection (2SB) scheme based on quadrature layout, with SIS mixers covering 163-211 GHz with 4-8 GHz IF. The LO injection circuitry is integrated with mixer chip and is implemented on the same substrate, resulting in a compact 2SB assembly. Amongst the other ALMA bands, the ALMA Band 5 being the lowest frequency band that uses all cold optics, has the largest mirror. Consequently, ALMA Band 5 mirror along with its support structure leaves very little room for placing OMT, mixers and IF subsystems. The constraints put by the size of cold optics and limited cartridge space, required of us to revise the original 2SB design and adopt a design where all the components like OMT, mixer, IF hybrid, isolators and IF amplifier are directly connected to each other without using any co-ax cables in-between. The IF subsystem uses the space between 4 K and 15 K stage of the cartridge and is thermally connected to 4 K stage. Avoiding co-ax cabling required use of custom designed IF hybrid, furthermore, due to limited cooling capacity at 4 K stage, resistive bias circuitry for the mixers is moved to 15 K stage and the IF hybrid along with an integrated bias-T is implemented using superconducting micro-strip lines. The E-probes for both LO and RF waveguide-to-microstrip transitions are placed perpendicular to the wave direction (back-piece configuration). The RF choke at the end of the probes provides a virtual ground for the RF/LO signal, and the choke is DC grounded to the chassis. The on-chip LO injection is done using a microstrip line directional coupler with slot-line branches in the

  10. Sm-Nd and Rb-Sr isotope systematics of an Archean anorthosite and related rocks from the Superior Province of the Canadian Shield

    International Nuclear Information System (INIS)

    Sm-Nd and Rb-Sr isotopic data for the Bad Vermilion Lake anorthosite complex (BVL) in the Rainy Lake area of the Superior Province of northwestern Ontario show that direct ages of Archean anorthosites can be obtained with these isotopic systems despite the effects of low-grade metamorphism. There is sufficient spread in Sm/Nd between plagioclase megacrysts and coexisting mafic groundmass to allow the determination of reasonably precise internal Sm-Nd isochrons. Anorthosite samples from BVL show an unusually large range in LIL concentrations such that there is sufficient spread in Rb/Sr for a whole-rock isochron (2.69+-0.10 Ga, Isub(Sr)=0.70079+-8). This variability may have been caused by Rb introduction during hydrothermal alteration and/or low-grade metamorphism. The Sm-Nd isochron for BVL (2747+-58 Ma, epsilonsub(Nd)=+2.0+-1.4) includes data for anorthosite, gabbro and metabasalt, and is consistent with the consanguineity of these units in the Rainy Lake area. The age is interpreted as the time of crystallization of the anorthosite complex and related mafic plutonics and volcanics. Visibly altered samples show evidence for disturbance of the Sm-Nd and Rb-Sr isotopic systems. In one altered porphyritic dike plagioclase appears to have exchanged light REE with the relatively REE-rich basaltic matrix. This sample yields an internal Sm-Nd age of 2.16+-0.05 Ga, which may correspond to the time of local heating or represent a partial resetting from a still younger event. Initial isotopic ratios of Nd and Sr determined here add to the growing body of data indicating that the Superior Province is underlain by depleted mantle. (orig.)

  11. Oxidative release of chromium from Archean ultramafic rocks, its transport and environmental impact – A Cr isotope perspective on the Sukinda valley ore district (Orissa, India)

    International Nuclear Information System (INIS)

    Highlights: • Cr in lateritic soil profiles in Sukinda valley are partly highly negatively fractionated. • Oxidative weathering and mining operations affect the Cr isotope composition of the local surface water. • Isotopically heavy Cr from land is probably preserved during its transport to the sea. • The environmental impact of toxic Cr(VI) can potentially be diminished by microbial mats. - Abstract: This study investigates Cr isotope fractionation during soil formation from Archean (3.1–3.3 Ga) ultramafic rocks in a chromite mining area in the southern Singhbhum Craton (Orissa, India). The Cr-isotope signatures of two studied weathering profiles, range from non-fractionated mantle values to negatively fractionated values as low as δ53Cr = −1.29 ± 0.04‰. Local surface waters are isotopically heavy relative to the soils. This supports the hypothesis that during oxidative weathering isotopically heavy Cr(VI) is leached from the soils to runoff. The impact of mining pollution is observed downstream from the mine where surface water Cr concentrations are significantly increased, accompanied by a shift to less positive δ53Cr values relative to upstream unpolluted surface water. A microbial mat sample indicates that microbes have the potential to reduce and immobilize Cr(VI), which could be a factor in controlling the hazardous impact of Cr(VI) on health and environment. The positive Cr isotope signatures of the Brahmani estuary and coastal seawater collected from the Bay of Bengal further indicate that the positively fractionated Cr isotope signal from the catchment area is preserved during its transport to the sea. Isotopically lighter Cr(VI) downstream from the mine is probably back-reduced to Cr(III) during riverine transport leading to similar Cr-isotope values in the estuary as observed upstream from the mine

  12. Single-zircon dating by stepwise Pb-evaporation constrains the Archean history of detrital zircons from the Jack Hills, Western Australia

    International Nuclear Information System (INIS)

    Pb isotope analyses have been carried out on 42 zircon grains from a Western Australian metaconglomerate using stepwise Pb-evaporation directly in the ion source of a thermal ionization mass spectrometer. The metaconglomerate is from the Archean Jack Hills Metasedimentary Belt, and is known from ion microprobe (''SHRIMP'') analyses to contain a complex zircon population with ages between 4.2 Ga and 3.1 Ga. The same complex pattern of ages is found by the Pb evaporation studies. Five grains yielded minimum crystallization ages from 4.17 Ga to 4.07 Ga. The main population appears significantly younger, having been generated at about 3.55-3.3 Ga. The agreement between the two analytical approaches confirms the SHRIMP results and demonstrates the value of the stepwise-evaporation technique in determining the age patterns of mixing zircon populations. In many of the evaporative Pb isotope records the 207/206 ratios remained constant for all evaporation steps, which we interpret as evaporation from concordant zircon phases. However, for the majority of zircons 207/206 ratios increased with increasing evaporation temperature, and usually approached constant values during evaporation at the highest temperatures. This can be attributed to mixing of different radiogenic Pb components from either crystalline zircon phases of different ages or from domains of isotopically disturbed metamict zircon. Present results confirm > 4 Ga zircon ages in the metaconglomerate from the Hack Hills and substantiate formation of crust at a very early stage in the evolution of the earth. Results also confirm a major crust-forming event 3.55-3.3 Ga ago. (orig.)

  13. Intestinal absorbtion from therapeutic iron doses

    International Nuclear Information System (INIS)

    On a total of 105 persons with normal iron stores, iron depletion, and iron deficiency the intestinal absorption from therapeutic iron doses (100 mg Fe and 50 mg Fe as ferrous glycocoll sulphate) of a special galenic form was measured. The measurements were performed by means of a whole-body counter and preparations labelled with radio iron (59Fe). Mean values of absorption rates from 100 mg Fe in healthy males were 5.0% and in healthy females 5.6% whereas in latent iron deficiency and in iron deficiency anemia mean values of 10% and 13% were obtained, respectively. The maximum absorption rate of 20 to 25% is reached already in the late stage of latent iron deficiency. Advancing severeness of iron deficiency is not followed by an increase of iron absorption. Investigations an 21 persons showed no significant difference between absorption rates of the galenic preparations used when administered orally before or after breakfast, respectively. (orig.)

  14. Iron metabolism in the mononuclear phagocyte system

    Institute of Scientific and Technical Information of China (English)

    Weina Kong; Xianglin Duan; Zhenhua Shi; Yanzhong Chang

    2008-01-01

    The maintenance of body iron homeostasis requires the coordination of multiple regulatory mechanisms of iron metabolism.The mononuclear phagocyte system (MPS,composed of monocytes,macrophages,and their precursor cells) is crucial in the maintenance of iron homeostasis.Recycling of iron is carried out by specialized macrophages via engulfment of aged erythrocytes.The iron stores of macrophages depend on the levels of recovered and exported iron.However,the molecular mechanisms underlying iron homeostasis in macrophages are poorly understood.Recent studies characterizing the function and regulation of natural resistance-associated macrophage protein 1 (Nrampl),divalent metal transporter 1 (DMTI),HLA-linked hemechromatosis gene (HFE),ferroportin 1 (FPN1),and hepcidin are rapidly expanding our knowledge on the molecular level of MPS iron handling.These studies are deepening our understanding about the molecular mechanism of iron homeostasis and iron-related diseases.

  15. Electrosynthesis and studies on Cadmium-Iron-Sulphide thin films

    International Nuclear Information System (INIS)

    Cadmium-Iron-Sulphide (Cd-Fe-S) thin films have prepared on indium doped tin oxide (ITO) coated conducting glass substrates by potentiostatic electrodeposition technique. X-ray diffraction pattern shows that the deposited films exhibit mixture of hexagonal CdS and hexagonal FeS phases. Surface morphology and film composition represent that films with smooth surface and better stoichiometry are obtained at 0.0375 M CdSO4 concentration. Optical parameters such as band gap, refractive index and extinction coefficient which are evaluated from optical absorption measurements. The experimental observations are discussed in detail.

  16. NCenter wide band neutrino beam

    International Nuclear Information System (INIS)

    This memo describes the physical properties of the currently operating N-Center wide band neutrino beam---commonly called the triplet train, following a past tradition of a triplet lens configuration. In reality, in order to gain a larger momentum acceptance and to minimize the angular divergence of the beam, a quadruplet beam (4 lenses) employing point-to-parallel optics at a central momentum of 300 GeV was built. 6 refs., 13 figs., 1 tab

  17. Shear Banding of Complex Fluids

    OpenAIRE

    Divoux, Thibaut; Fardin, Marc-Antoine; Manneville, Sebastien; Lerouge, Sandra

    2015-01-01

    Even in simple geometries many complex fluids display non-trivial flow fields, with regions where shear is concentrated. The possibility for such shear banding has been known since several decades, but the recent years have seen an upsurge of studies offering an ever more precise understanding of the phenomenon. The development of new techniques to probe the flow on multiple scales and with increasing spatial and temporal resolution has opened the possibility for a synthesis of the many pheno...

  18. Niobium in gray cast iron

    International Nuclear Information System (INIS)

    The potential for utilization of niobium in gray cast iron is appraised and reviewed. Experiments described in literature indicate that niobium provides structural refinement of the eutectic cells and also promotes pearlite formation. (Author)

  19. Hereditary iron and copper deposition

    DEFF Research Database (Denmark)

    Aaseth, Jan; Flaten, Trond Peder; Andersen, Ole

    2007-01-01

    Hereditary deposition of iron (primary haemochromatosis) or copper (Wilson's disease) are autosomal recessive metabolic disease characterized by progressive liver pathology and subsequent involvement of various other organs. The prevalence of primary haemochromatosis is approximately 0.5%, about...

  20. Iron oxides in human spleen

    Czech Academy of Sciences Publication Activity Database

    Kopáni, M.; Miglierini, M.; Lančok, Adriana; Dekan, J.; Čaplovicová, M.; Jakubovský, J.; Boča, R.; Mrazova, H.

    2015-01-01

    Roč. 28, č. 5 (2015), s. 913-928. ISSN 0966-0844 Institutional support: RVO:61388980 Keywords : diffraction * iron * magnetic properties Subject RIV: CA - Inorganic Chemistry Impact factor: 2.503, year: 2014

  1. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang

    2009-01-01

    @@ Preface Cast iron, as a traditional metal material, has advantages of low total cost, good castability and machinability, good wear resistance and low notch sensitivity, and is still facing tough challenge in quality, property and variety of types etc.

  2. Galactic cosmic ray iron composition

    Science.gov (United States)

    Scherzer, R.; Enge, W.; Beaujean, R.; Hertzman, S.; Kristansson, K.; Soederstroem, K.

    1980-11-01

    The isotopic composition of galactic cosmic ray iron was studied in the energy interval 500-750 MeV/nucleon with a visual track detector system consisting of nuclear emulsion and cellulose nitrate plastic. Stopping iron nuclei were identified from ionization range measurements in the two detector parts. Cone lengths were measured in the plastic sheets and the residual ranges of the particles were measured in plastic and in emulsion. The mass of iron-17 nuclei was determined with an uncertainty of about 0.3 amu. The isotopic composition at the detector level was found to be Fe-52:Fe-53:Fe-54:Fe-55:Fe-56:Fe-57:Fe-58 = 0:1:4:3:8:1:0. These numbers are not in conflict with the assumption that the isotopic composition of cosmic ray iron at the source is similar to the solar system composition.

  3. Discovery of the Iron Isotopes

    OpenAIRE

    Schuh, A.; A. Fritsch; Heim, M.; SHORE, A.; Thoennessen, M

    2009-01-01

    Twenty-eight iron isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  4. Band-selective radiofrequency pulses

    Science.gov (United States)

    Geen, Helen; Freeman, Ray

    A theoretical treatment is given of the general problem of designing amplitude-modulated radiofrequency pulses that will excite a specified band of frequencies within a high-resolution NMR spectrum with uniform intensity and phase but with negligible excitation elsewhere. First a trial pulse envelope is defined in terms of a finite Fourier series and its frequency-domain profile calculated through the Bloch equations. The result is compared with the desired target profile to give a multidimensional error surface. The method of simulated annealing is then used to find the global minimum on this surface and the result refined by standard gradient-descent optimization. In this manner, a family of new shaped radio-frequency pulses, known as BURP ( band-selective, uniform response, pure-phase) pulses, has been created. These are of two classes—pulses that excite or invert z magnetization and those that act as general-rotation πr/2 or π pulses irrespective of the initial condition of the nuclear magnetization. It was found convenient to design the latter class as amplitude-modulated time-symmetric pulses. Tables of Fourier coefficients and pulse-shape ordinates are given for practical implementation of BURP pulses, together with the calculated frequency-domain responses and experimental verifications. Examples of the application of band-selective pulses in conventional and multidimensional spectroscopy are given. Pure-phase pulses of this type should also find applications in magnetic resonance imaging where refocusing schemes are undesirable.

  5. 辽河坳陷太古宇变质岩内幕油藏成藏特征%Forming features of interior reservoir in metamorphic rock of Archean Eonothem, Liaohe depression

    Institute of Scientific and Technical Information of China (English)

    马志宏

    2013-01-01

    It has been a great breakthrough of bed rock exploration in Liaohe depression that the interior reservoirs are found in the metamorphic rock of Archean Eonothem. Because the current understanding constrained that only the weathered crust of metamorphic rock can form reservoirs, and it has been changed, and that, the formation theory of hydrocarbon reservoirs of bed rock in Liaohe depression has been enriched. The interior oil pools in metamorphic rock of Archean Eonothem in Liaohe depression will be important prospective target because it has important potential capacities for exploration. With continuous exploration, the new difficulty questions will gradually appear, so, it will become more important that the formation features of interior oil pools in metamorphic rock of Archean Eonothem should be clarified. This paper discusses the known interior reservoir in metamorphic rock of Archean Eonothem. Firstly, their properties of crude oil are analyzed, then, the formation features of known interior reservoir, such as Xinggu7, Shen311, Zhaogul and so on, are presented, ultimately, the formation features of interior reservoir in metamorphic rock of Archean Eonothem in Liaohe depression are proposed. The theoretical knowledge in this paper will have important directive significance for the exploration of interior oil pools in metamorphic rock of Archean Eonothem in Liaohe depression and other similar exploration areas all over the world.%太古宇变质岩内幕油藏的发现是辽河坳陷基岩勘探的重大突破,改变了以往只有变质岩风化壳才能形成油气成藏的认识,丰富了辽河坳陷基岩油气成藏理论,是今后重要的勘探目标.但随着勘探的不断深入,明确太古宇变质岩内幕油藏的成藏特征显得越来越重要.为此,从典型的太古宇变质岩内幕油藏入手,首先对其原油性质进行分析,然后对兴古7、沈311和赵古1等油藏进行剖析,最后总结出成藏特征.辽河坳陷太古宇变

  6. Investigation of iron status in Terric Histosols

    Directory of Open Access Journals (Sweden)

    Sokołowska Z.

    2002-06-01

    Full Text Available The iron status in 14 differently transformed muck formations (Terric Histosols was studied. The Moessbauer spectra showed that most of the iron in all the samples was trivalent. An attempt to find the relationship between the iron content and the state of the soil transformation was performed. The w/w percentage of the total iron as well as the (alkaline extractable organic iron increased with the increase of the ratio of humic to fulvic acids.

  7. Hyperferritinaemia in the absence of iron overload

    OpenAIRE

    Arnold, J.; Mumford, A.; Lindsay, J.; Hegde, U; Hagan, M.; Hawkins, J.

    1997-01-01

    Background—Serum ferritin is normally a marker of iron overload. Ferritin genes are sited at chromosomes 19 and 11. Regulation of ferritin synthesis involves an interaction between an iron regulatory protein (IRP) and part of the ferritin mRNA designated the iron regulatory element (IRE). A disorder of ferritin synthesis resulting in hyperferritinaemia in the absence of iron overload has been described recently. 
Patients and methods—Hyperferriti- naemia in the absence of iron ove...

  8. Iron in Innate Immunity: Starve the Invaders

    OpenAIRE

    Ganz, Tomas

    2009-01-01

    Iron is essential for nearly all living organisms. Innate immunity effectively restricts iron availability to microbial invaders. Some microbes have evolved effective countermeasures that blunt the effect of iron restriction. Recent epidemiologic studies have highlighted the potentiating effect of iron on microbial infections. Laboratory studies have focused on specific immune mechanisms that mediate iron withholding from microbes constitutively and in response to infections. Specialized infl...

  9. Treatment of Iron Deficiency in Women

    OpenAIRE

    Breymann, C; Römer, T.; Dudenhausen, J. W.

    2013-01-01

    Iron deficiency with and without anaemia is a common cause of morbidity, particularly in women. Iron deficiency is generally the result of an imbalance between iron loss and iron absorption. In women with symptoms suspicious for iron deficiency, it is important to confirm or exclude the suspicion using proper tests. The use of serum ferritin levels is considered the gold standard for diagnosis. Although the ideal ferritin levels are not unknown the current consent is that le...

  10. Targeting Iron Deficiency Anemia in Heart Failure.

    Science.gov (United States)

    Saraon, Tajinderpal; Katz, Stuart D

    2016-01-01

    Iron deficiency is common in heart failure (HF) patients, and is associated with increased risk of adverse clinical outcomes. Clinical trials of intravenous iron supplementation in iron-deficient HF patients have demonstrated short-term improvement in functional capacity and quality of life. In some trials, the benefits of iron supplementation were independent of the hemoglobin levels. Additional investigations of iron supplementation are needed to characterize the mechanisms contributing to clinical benefit and long-term safety in HF. PMID:26657161

  11. Iron Deficiency and Bariatric Surgery

    OpenAIRE

    Ignacio Jáuregui-Lobera

    2013-01-01

    It is estimated that the prevalence of anaemia in patients scheduled for bariatric surgery is higher than in the general population and the prevalence of iron deficiencies (with or without anaemia) may be higher as well. After surgery, iron deficiencies and anaemia may occur in a higher percentage of patients, mainly as a consequence of nutrient deficiencies. In addition, perioperative anaemia has been related with increased postoperative morbidity and mortality and poorer quality of life aft...

  12. Streamlining Iron and Steel Production

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Eliminating unproductive iron and steel facilities is vital to environmental protection and sustainable development of this industry The Chinese Government is once again shutting down unproductive plants in tune with its green policy and the march toward sustainable development.This time it’s the iron and steel industry to feel the brunt of the Chinese Government’s stringent measures. The deafening buzz of factory floors have

  13. Maximum stellar iron core mass

    Indian Academy of Sciences (India)

    F W Giacobbe

    2003-03-01

    An analytical method of estimating the mass of a stellar iron core, just prior to core collapse, is described in this paper. The method employed depends, in part, upon an estimate of the true relativistic mass increase experienced by electrons within a highly compressed iron core, just prior to core collapse, and is significantly different from a more typical Chandrasekhar mass limit approach. This technique produced a maximum stellar iron core mass value of 2.69 × 1030 kg (1.35 solar masses). This mass value is very near to the typical mass values found for neutron stars in a recent survey of actual neutron star masses. Although slightly lower and higher neutron star masses may also be found, lower mass neutron stars are believed to be formed as a result of enhanced iron core compression due to the weight of non-ferrous matter overlying the iron cores within large stars. And, higher mass neutron stars are likely to be formed as a result of fallback or accretion of additional matter after an initial collapse event involving an iron core having a mass no greater than 2.69 × 1030 kg.

  14. Neoproterozoic Anatexis of 2.9 Ga Old Granitoids in the Goiás-Crixás Archean Block, Central Brazil: Evidence From New SHRIMP U-Pb Data and Sm-Nd Isotopes

    Directory of Open Access Journals (Sweden)

    Márcio Martins Pimentel

    2003-08-01

    Full Text Available The first SHRIMP U-Pb ages for granitoid rocks from the southern part of the Goiás-Crixás Archean Block (Caiçara andUvá complexes are presented and discussed in combination with Sm-Nd isotopic data in order to elucidate the main aspectsof the geological evolution of that part of the Brasília Belt in central Brazil. Zircon grains from a tonalitic gneiss (GOV-4 inthe Uvá Complex show that the original tonalite crystallized at 2934 ± 5 Ma. One metamorphic zircon crystal is concordantand indicates an Archean age for the recrystallization episode (2793 ± 3 Ma and one inherited grain with an age of 3092 ± 9suggests, together with negative values of eNd(T (+0.4 and –4.6, that the magma was contaminated with older crust. Oneleucocratic granite (GOV-1 exposed north of the Goiás greenstone belt crystallized at 626 ± 7 Ma, as indicated by theigneous overgrowths surrounding older inherited cores. The latter indicate a crystallization age of 2893 ± 12 Ma. This rockis interpreted therefore as the product of Neoproterozoic anatexis of ca. 2.89 Ga-old rocks of the Caiçara Complex. This isreinforced by strongly negative eNd(T = 626 values of – 28.0 and –29.0. Its crystallization age is identical to the U-Pb agesof the Itapuranga granite and Uruana quartz syenite, which are exposed to the north of the investigated area and interpretedas syn-tectonic intrusions in relation to the main Brasiliano tectonic event. This represents, therefore, the first evidence ofNeoproterozoic magmatism within the Goiás Archean Block and raises the possibility that other leucogranite dykes andstocks identified regionally may also have been formed during the Brasiliano orogeny.

  15. Iron, Oxidative Stress and Gestational Diabetes

    Directory of Open Access Journals (Sweden)

    Taifeng Zhuang

    2014-09-01

    Full Text Available Both iron deficiency and hyperglycemia are highly prevalent globally for pregnant women. Iron supplementation is recommended during pregnancy to control iron deficiency. The purposes of the review are to assess the oxidative effects of iron supplementation and the potential relationship between iron nutrition and gestational diabetes. High doses of iron (~relative to 60 mg or more daily for adult humans can induce lipid peroxidation in vitro and in animal studies. Pharmaceutical doses of iron supplements (e.g., 10× RDA or more for oral supplements or direct iron supplementation via injection or addition to the cell culture medium for a short or long duration will induce DNA damage. Higher heme-iron intake or iron status measured by various biomarkers, especially serum ferritin, might contribute to greater risk of gestational diabetes, which may be mediated by iron oxidative stress though lipid oxidation and/or DNA damage. However, information is lacking about the effect of low dose iron supplementation (≤60 mg daily on lipid peroxidation, DNA damage and gestational diabetes. Randomized trials of low-dose iron supplementation (≤60 mg daily for pregnant women are warranted to test the relationship between iron oxidative stress and insulin resistance/gestational diabetes, especially for iron-replete women.

  16. Experimental Signatures of Orbital Fluctuations in Iron Based Superconductors

    Science.gov (United States)

    Lee, Wei-Cheng

    2015-03-01

    Understanding the high temperature superconductivity has been one of main subjects in the condensed matter physics. The discovery of new classes of high-temperature superconductors, iron pnictides in 2008, launched an international wave of research in the past few years. While the magnetic interactions are certainly important in these materials, there have been significant evidences suggesting that the orbital degrees of freedom could play an important role as well. In this talk, I will demonstrate that the orbital degrees of freedom do play a significant role in physical properties of iron-based superconductors. At the level of single particle properties, while the orbital order in the quasi-1D dxz and dyz bands has been proposed to be a possible driving mechanism for the structural phase transition, our study shows that the fluctuations associated with the orbital order could further drive a non-Fermi liquid behavior in the critical region of the orbital ordering phase transition. I will show that this non-Fermi liquid behavior could induce a zero-bias anomaly in the point contact spectroscopy, which has been observed in a variety of iron based superconductors. As for the magnetic properties, we also find that the orbital order and fluctuations can qualitatively change the nature of the spin excitation spectrum, giving rise to the novel incommensurate-to-commensurate transformation observed in a recent neutron scattering measurement. In the superconducting state, we predict that a new collective excitation, termed as orbital resonance mode, could exist generally in the iron-based superconductors, which in principle can be measured by Raman spectroscopy. Our findings offer a new perspective on the pairing mechanism of iron based superconductors, and suggest that orbital degrees of freedom could provide a new route to high temperature superconductivity.

  17. Neoproterozoic Anatexis of 2.9 Ga Old Granitoids in the Goiás-Crixás Archean Block, Central Brazil: Evidence From New SHRIMP U-Pb Data and Sm-Nd Isotopes

    OpenAIRE

    Márcio Martins Pimentel; Hardy Jost; Reinhardt Adolfo Fuck; Richard Austin Armstrong; Elton Luiz Dantas; Alain Potrel

    2003-01-01

    The first SHRIMP U-Pb ages for granitoid rocks from the southern part of the Goiás-Crixás Archean Block (Caiçara andUvá complexes) are presented and discussed in combination with Sm-Nd isotopic data in order to elucidate the main aspectsof the geological evolution of that part of the Brasília Belt in central Brazil. Zircon grains from a tonalitic gneiss (GOV-4) inthe Uvá Complex show that the original tonalite crystallized at 2934 ± 5 Ma. One metamorphic zircon crystal is concordantand indica...

  18. Mechanical behavior of a bulk nanostructured iron alloy

    Science.gov (United States)

    Carsley, J. E.; Fisher, A.; Milligan, W. W.; Aifantis, E. C.

    1998-09-01

    Bulk, fully dense materials were prepared from Fe-10Cu with grain diameters between 45 nm and 1.7 µm. The materials were prepared by ball milling of powders in a glove box, followed by hot isostatic pressing (hipping) or powder forging. Larger grain sizes were obtained by thermal treatment of the consolidated powders. The bulk materials were relatively clean, with oxygen levels below 1500 wpm and other contaminants less than 0.1 at. pct. The mechanical behavior of these materials was unique. At temperatures from 77 to 470 K, the first and only mechanism of plastic deformation was intense shear banding, which was accompanied by a perfectly plastic stress-strain response (absence of strain hardening). There was a large tension-compression asymmetry in the strength, and the shear bands did not occur on the plane of maximum shear stress or the plane of zero extension. This behavior, while unusual for metals, has been observed in amorphous polymers and metallic glasses. On the other hand, the fine-grained Fe-10Cu materials behaved like coarse-grained iron in some respects, particularly by obeying the Hall-Petch equation with constants reasonably close to those of pure iron and by exhibiting low-temperature mechanical behavior which was very similar to that of steels. Transmission electron microscopy (TEM) studies found highly elongated grains within shear bands, indicating that shear banding occurred by a dislocation-based mechanism, at least at grain sizes above 100 nm. Similarities and differences between the fine-grained Fe-10Cu and metals, polymers, metallic glasses, radiation-damaged metals, and quench-damaged metals are discussed.

  19. Design of smooth orthogonal wavelets with beautiful structure from 2-band to 4-band

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A complete algorithm to design 4-band orthogonal wavelets with beautiful structure from 2-band orthogonal wavelets is presented. For more smoothness, the conception of transfer vanishing moment is introduced by transplanting the requirements of vanishing moment from the 4-band wavelets to the 2-band ones. Consequently, the design of 4-band orthogonal wavelets with P vanishing moments and beautiful structure from 2-band ones with P transfer vanishing moments is completed.

  20. Effect of Erythropoietin, Iron Deficiency and Iron Overload on Liver Matriptase-2 (TMPRSS6 Protein Content in Mice and Rats.

    Directory of Open Access Journals (Sweden)

    Jana Frýdlová

    Full Text Available Matriptase-2 (TMPRSS6 is an important negative regulator of hepcidin expression; however, the effects of iron overload or accelerated erythropoiesis on liver TMPRSS6 protein content in vivo are largely unknown. We determined TMPRSS6 protein content in plasma membrane-enriched fractions of liver homogenates by immunoblotting, using a commercial antibody raised against the catalytic domain of TMPRSS6. Plasma membrane-enriched fractions were obtained by centrifugation at 3000 g and washing. TMPRSS6 was detected in the 3000 g fraction as a 120 kDa full-length protein in both mice and rats. Feeding of iron-deficient diet as well as erythropoietin treatment increased TMPRSS6 protein content in rats and mice by a posttranscriptional mechanism; the increase in TMPRSS6 protein by erythropoietin was also observed in Bmp6-mutant mice. Administration of high doses of iron to mice (200, 350 and 700 mg/kg decreased TMPRSS6 protein content. Hemojuvelin was detected in the plasma membrane-enriched fractions of control animals as a full length protein of approximately 52 kDa; in iron deficient animals, the full length protein was partially cleaved at the N-terminus, resulting in an additional weak band of approximately 47 kDa. In livers from hemojuvelin-mutant mice, TMPRSS6 protein content was strongly decreased, suggesting that intact hemojuvelin is necessary for stable TMPRSS6 expression in the membrane. Overall, the results demonstrate posttranscriptional regulation of liver TMPRSS6 protein by iron status and erythropoietin administration, and provide support for the interaction of TMPRSS6 and hemojuvelin proteins in vivo.