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Sample records for oxygen deficient strontium

  1. Thermal conductivity reduction in oxygen-deficient strontium titanates

    NARCIS (Netherlands)

    Yu, Choongho; Scullin, Matthew L.; Huijben, Mark; Ramesh, Ramamoorthy; Majumdar, Arun

    2008-01-01

    We report significant thermal conductivity reduction in oxygen-deficient lanthanum-doped strontium titanate (Sr1−xLaxTiO3−δ) films as compared to unreduced strontium titanates. Our experimental results suggest that the oxygen vacancies could have played an important role in the reduction. This could

  2. Persistent optically induced magnetism in oxygen-deficient strontium titanate.

    Science.gov (United States)

    Rice, W D; Ambwani, P; Bombeck, M; Thompson, J D; Haugstad, G; Leighton, C; Crooker, S A

    2014-05-01

    Strontium titanate (SrTiO3) is a foundational material in the emerging field of complex oxide electronics. Although its bulk electronic and optical properties are rich and have been studied for decades, SrTiO3 has recently become a renewed focus of materials research catalysed in part by the discovery of superconductivity and magnetism at interfaces between SrTiO3 and other non-magnetic oxides. Here we illustrate a new aspect to the phenomenology of magnetism in SrTiO3 by reporting the observation of an optically induced and persistent magnetization in slightly oxygen-deficient bulk SrTiO3-δ crystals using magnetic circular dichroism (MCD) spectroscopy and SQUID magnetometry. This zero-field magnetization appears below ~18 K, persists for hours below 10 K, and is tunable by means of the polarization and wavelength of sub-bandgap (400-500 nm) light. These effects occur only in crystals containing oxygen vacancies, revealing a detailed interplay between magnetism, lattice defects, and light in an archetypal complex oxide material.

  3. Colossal positive magnetoresistance in surface-passivated oxygen-deficient strontium titanite

    KAUST Repository

    David, Adrian

    2015-05-15

    Modulation of resistance by an external magnetic field, i.e. magnetoresistance effect, has been a long-lived theme of research due to both fundamental science and device applications. Here we report colossal positive magnetoresistance (CPMR) (>30,000% at a temperature of 2 K and a magnetic field of 9 T) discovered in degenerate semiconducting strontium titanite (SrTiO3) single crystals capped with ultrathin SrTiO3/LaAlO3 bilayers. The low-pressure high-temperature homoepitaxial growth of several unit cells of SrTiO3 introduces oxygen vacancies and high-mobility carriers in the bulk SrTiO3, and the three-unit-cell LaAlO3 capping layer passivates the surface and improves carrier mobility by suppressing surface-defect-related scattering. The coexistence of multiple types of carriers and inhomogeneous transport lead to the emergence of CPMR. This unit-cell-level surface engineering approach is promising to be generalized to others oxides, and to realize devices with high-mobility carriers and interesting magnetoelectronic properties.

  4. Colossal positive magnetoresistance in surface-passivated oxygen-deficient strontium titanite

    KAUST Repository

    David, Adrian; Tian, Yufeng; Yang, Ping; Gao, Xingyu; Lin, Weinan; Shah, Amish B.; Zuo, Jian-Min; Prellier, Wilfrid; Wu, Tao

    2015-01-01

    ,000% at a temperature of 2 K and a magnetic field of 9 T) discovered in degenerate semiconducting strontium titanite (SrTiO3) single crystals capped with ultrathin SrTiO3/LaAlO3 bilayers. The low-pressure high-temperature homoepitaxial growth of several unit

  5. Strontium cobaltite oxygen sponge catalyst and methods of use

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ho Nyung; Jeen, Hyoungjeen; Choi, Woo Seok; Biegalski, Michael; Folkman, Chad M.; Tung, I-Cheng; Fong, Dillon D.; Freeland, John W.; Shin, Dongwon; Ohta, Hiromichi; Chisholm, Matthew F.

    2017-01-24

    Rapid, reversible redox activity may be accomplished at significantly reduced temperatures, as low as about 200.degree. C., from epitaxially stabilized, oxygen vacancy ordered SrCoO.sub.2.5 and thermodynamically unfavorable perovskite SrCoO.sub.3-.delta.. The fast, low temperature redox activity in SrCoO.sub.3-.delta. may be attributed to a small Gibbs free energy difference between the two topotactic phases. Epitaxially stabilized thin films of strontium cobaltite provide a catalyst adapted to rapidly transition between oxidation states at substantially low temperatures. Methods of transitioning a strontium cobaltite catalyst from a first oxidation state to a second oxidation state are described.

  6. ODH, oxygen deficiency hazard cryogenic analysis

    International Nuclear Information System (INIS)

    Augustynowicz, S.D.

    1994-01-01

    An oxygen deficiency exists when the concentration of oxygen, by volume, drops to a level at which atmosphere supplying respiratory protection must be provided. Since liquid cryogens can expand by factors of 700 (LN 2 ) to 850 (LH e ), the uncontrolled release into an enclosed space can easily cause an oxygen-deficient condition. An oxygen deficiency hazard (ODH) fatality rate per hour (OE) is defined as: OE = Σ N i P i F i , where N i = number of components, P i = probability of failure or operator error, and F i = fatality factor. ODHs range from open-quotes unclassifiedclose quotes (OE -9 1/h) to class 4, which is the most hazardous (OE>10 -1 1/h). For Superconducting Super Collider Laboratory (SSCL) buildings where cryogenic systems exist, failure rate, fatality factor, reduced oxygen ratio, and fresh air circulation are examined

  7. Investigation of ferromagnetism in oxygen deficient hafnium oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hildebrandt, Erwin; Kurian, Jose; Krockenberger, Yoshiharu; Alff, Lambert [Institut fuer Materialwissenschaft, TU Darmstadt (Germany); Suter, Andreas [PSI, Villingen (Switzerland); Wilhelm, Fabrice; Rogalev, Andrei [ESRF, Grenoble (France)

    2008-07-01

    Oxygen deficient thin films of hafnium oxide were grown on single crystal r-cut and c-cut sapphire by reactive molecular beam epitaxy. RF-activated oxygen was used for the in situ oxidation of hafnium oxide thin films. Oxidation conditions were varied substantially in order to create oxygen deficiency in hafnium oxide films intentionally. The films were characterized by X-ray and magnetic measurements. X-ray diffraction studies show an increase in lattice parameter with increasing oxygen deficiency. Oxygen deficient hafnium oxide thin films also showed a decreasing bandgap with increase in oxygen deficiency. The magnetisation studies carried out with SQUID did not show any sign of ferromagnetism in the whole oxygen deficiency range. X-ray magnetic circular dichroism measurements also confirmed the absence of ferromagnetism in oxygen deficient hafnium oxide thin films.

  8. Oxygen Stoichiometry in Cation Deficient (La,Sr)_{1-z}MnO_3 SOFC Cathode Materials

    DEFF Research Database (Denmark)

    Zachau-Christiansen, Birgit; Jacobsen, Torben; Skaarup, Steen

    1997-01-01

    by the imposed potential.It is found that the oxygen stoichiometry and hence the defect chemistry is different whether A-site charge deficiency is established by Sr-doping or by A-site vacancies. Furthermore,A-site deficient lanthanum strontium manganates expel a secondary phase of manganese oxide when exposed...... to low oxygen partial pressures. The presence of small amounts of secondary phase isobserved and identified by its reoxidation peak. The amount of this foreign phase is determined by the charge used for its oxidation....

  9. A high reliability oxygen deficiency monitoring system

    International Nuclear Information System (INIS)

    Parry, R.; Claborn, G.; Haas, A.; Landis, R.; Page, W.; Smith, J.

    1993-01-01

    The escalating use of cryogens at national laboratories in general and accelerators in particular, along with the increased emphasis placed on personnel safety, mandates the development and installation of oxygen monitoring systems to insure personnel safety in the event of a cryogenic leak. Numerous vendors offer oxygen deficiency monitoring systems but fail to provide important features and/or flexibility. This paper describes a unique oxygen monitoring system developed for the Magnet Test Laboratory (MTL) at the Superconducting Super Collider Laboratory (SSCL). Features include: high reliability, oxygen cell redundancy, sensor longevity, simple calibration, multiple trip points, offending sensor audio and visual indication, global alarms for building evacuation, local and remote analog readout, event and analog data logging, EMAIL event notification, phone line voice status system, and multi-drop communications network capability for reduced cable runs. Of particular importance is the distributed topology of the system which allows it to operate in a stand-alone configuration or to communicate with a host computer. This flexibility makes it ideal for small applications such as a small room containing a cryogenic dewar, as well as larger systems which monitor many offices and labs in several buildings

  10. A high reliability oxygen deficiency monitoring system

    International Nuclear Information System (INIS)

    Parry, R.; Claborn, G.; Haas, A.; Landis, R.; Page, W.; Smith, J.

    1993-05-01

    The escalating use of cryogens at national laboratories in general and accelerators in particular, along with the increased emphasis placed on personnel safety, mandates the development and installation of oxygen monitoring systems to insure personnel safety in the event of a cryogenic leak. Numerous vendors offer oxygen deficiency monitoring systems but fail to provide important features and/or flexibility. This paper describes a unique oxygen monitoring system developed for the Magnet Test Laboratory (MTL) at the Superconducting Super Collider Laboratory (SSCL). Features include: high reliability, oxygen cell redundancy, sensor longevity, simple calibration, multiple trip points, offending sensor audio and visual indication, global alarms for building evacuation, local and remote analog readout, event and analog data logging, EMAIL event notification, phone line voice status system, and multi-drop communications network capability for reduced cable runs. Of particular importance is the distributed topology of the system which allows it to operate in a stand-alone configuration or to communicate with a host computer. This flexibility makes it ideal for small applications such as a small room containing a cryogenic dewar, as well as larger systems which monitor many offices and labs in several buildings

  11. Oxygen nonstoichiometry and transport properties of strontium substituted lanthanum cobaltite

    DEFF Research Database (Denmark)

    Søgaard, Martin; Hendriksen, Peter Vang; Mogensen, Mogens Bjerg

    2006-01-01

    Oxygen nonstoichiometry, structure and transport properties of the two compositions (La-0.6 Sr-0.4)(0.99)CoO3-delta (LSC40) and La0.85Sr0.15CoO3-delta (LSC15) were measured. It was found that the oxygen nonstoichiometry as a function of the temperature and oxygen partial pressure could be described...... using the itinerant electron model. The electrical conductivity, sigma, of the materials is high (sigma > 500 S cm(-1)) in the measured temperature range (650 - 1000 degrees C) and oxygen partial pressure range (0.209-10(-4) atm). At 900 degrees C the electrical conductivity is 1365 and 1491 S cm(-1......) in air for LSC40 and LSC15, respectively. A linear correlation between the electrical conductivity and the oxygen vacancy concentration was found for both samples. The mobility of the electron-holes was inversely proportional with the absolute temperature indicating a metallic type conductivity for LSC40...

  12. Deposition of Lanthanum Strontium Cobalt Ferrite (LSCF) Using Suspension Plasma Spraying for Oxygen Transport Membrane Applications

    Science.gov (United States)

    Fan, E. S. C.; Kesler, O.

    2015-08-01

    Suspension plasma spray deposition was utilized to fabricate dense lanthanum strontium cobalt ferrite oxygen separation membranes (OSMs) on porous metal substrates for mechanical support. The as-sprayed membranes had negligible and/or reversible material decomposition. At the longer stand-off distance (80 mm), smooth and dense membranes could be manufactured using a plasma with power below approximately 81 kW. Moreover, a membrane of 55 μm was observed to have very low gas leakage rates desirable for OSM applications. This thickness could potentially be decreased further to improve oxygen diffusion by using metal substrates with finer surface pores.

  13. The effect of oxygen impurity on the electronic and optical properties of calcium, strontium and barium chalcogenide compounds

    International Nuclear Information System (INIS)

    Dadsetani, M.; Beiranvand, R.

    2010-01-01

    Electronic and optical properties of calcium, strontium and barium chalcogenide compounds in NaCl structure are studied using the band structure results obtained through the full potential linearized augmented palne wave method. Different linear relationships are observed between theoretical band gap and 1/a 2 (where a is lattice constant) for calcium, strontium and barium chalcogenide compounds with and without oxygen, respectively. An abnormal behavior of electronic and optical properties are found for compounds containing oxygen. These effects are ascribed to the special properties of Ca-O, Sr-O and Ba-O bonds, which are different from chemical bonds between Ca, Sr and Ba and other chalcogen atoms.

  14. Are macroinvertebrates in high altitude streams affected by oxygen deficiency?

    DEFF Research Database (Denmark)

    Jacobsen, Dean; Rostgaard, S.; Vásconez, J. J.

    2003-01-01

    1. The solubility of oxygen in water increases with decreasing temperature. This has led to a general perception of cold, high mountain streams as more oxygen rich than warmer lowland streams, and that macroinvertebrates inhabiting high altitude streams have had no need to adapt to critical oxygen...... conditions. However, this fails to take into account that oxygen solubility declines with decreasing atmospheric pressure, which may be of importance at high altitudes. 2. Based on samples of macroinvertebrate benthos and in situ measurements of respiratory oxygen demand of macroinvertebrates in small...... the mean weight-specific respiratory rate of macroinvertebrates declined by only 50%, from 400 to 3800 m. We suggest that this disproportionately large gap between availability and demand of oxygen at high altitudes may imply a potential oxygen deficiency for the fauna, and we discuss how oxygen deficiency...

  15. Oxygen deficiency at CERN: Hazards, risks & mitigation measures

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    Compressed and liquified gases are used at many places at CERN. If they are introduced to the atmosphere, they can present an oxygen deficiency hazard (ODH) and lead to reduced abilities, unconsciousness or even death. The CERN method for ODH risk assessments is done on a case-by-case basis as each situation is unique. It is crucial to make sure the personnel can evacuate safely in case of an ODH situation. My talk will explain human reactions to reduced oxygen levels and I will give some practical examples on how one can assess and control the hazards from a possible oxygen deficient atmosphere. Some real accidents involving oxygen deficiency will also be mentioned.

  16. Surface strontium enrichment on highly active perovskites for oxygen electrocatalysis in solid oxide fuel cells

    KAUST Repository

    Crumlin, Ethan J.; Mutoro, Eva; Liu, Zhi; Grass, Michael E.; Biegalski, Michael D.; Lee, Yueh-Lin; Morgan, Dane; Christen, Hans M.; Bluhm, Hendrik; Shao-Horn, Yang

    2012-01-01

    Perovskite oxides have high catalytic activities for oxygen electrocatalysis competitive to platinum at elevated temperatures. However, little is known about the oxide surface chemistry that influences the activity near ambient oxygen partial pressures, which hampers the design of highly active catalysts for many clean-energy technologies such as solid oxide fuel cells. Using in situ synchrotron-based, ambient pressure X-ray photoelectron spectroscopy to study the surface chemistry changes, we show that the coverage of surface secondary phases on a (001)-oriented La 0.8Sr 0.2CoO 3-δ (LSC) film becomes smaller than that on an LSC powder pellet at elevated temperatures. In addition, strontium (Sr) in the perovskite structure enriches towards the film surface in contrast to the pellet having no detectable changes with increasing temperature. We propose that the ability to reduce surface secondary phases and develop Sr-enriched perovskite surfaces of the LSC film contributes to its enhanced activity for O 2 electrocatalysis relative to LSC powder-based electrodes. © 2012 The Royal Society of Chemistry.

  17. Strontium and oxygen isotopic variations in mesozoic and tertiary plutons of central Idaho

    International Nuclear Information System (INIS)

    Fleck, R.J.; Criss, R.E.

    1985-01-01

    Regional variations in initial 87 Sr/ 86 Sr ratios (rsub(i)) of Mesozoic plutons in central Idaho locate the edge of Precambrian continental crust at the boundary between the late Paleozoic-Mesozoic accreted terranes and Precambrian sialic crust in western Idaho. The rsub(i) values increase abruptly but continuously from less than 0.704 in the accreted terranes to greater than 0.708 across a narrow, 5 to 15 km zone, characterized by elongate, lens-shaped, highly deformed plutons and schistose metasedimentary and metavolcanic units. The chemical and petrologic character of the plutons changes concomitantly from ocean-arc-type units to a weakly peraluminous, calcit to calcalkalic suite. Plutons in both suites yield Late Cretaceous ages, but Permian through Early Cretaceous bodies are confined to the accreted terranes and early Tertiary intrusions are restricted to areas underlain by Precambrian crust. The two major terranes were juxtaposed between 75 and 130 m.y. ago, probably between 80 and 95 m.y. Oxygen and strontium isotopic ratios and Rb and Sr concentrations of the plutonic rocks document a significant upper-crustal contribution to the magmas that intrude Precambrian crust. Magmas intruding the arc terranes were derived from the upper mantle/subducted oceanic lithosphere and may have been modified by anatexis of earlier island-arc volcanic and sedimentary units. (orig./PW)

  18. Isotopic strontium, carbon and oxygen study on neoproterozoic marbles from Sierra de Umango, Andean Foreland, Argentina

    International Nuclear Information System (INIS)

    Varela, R; Valencio, S.; Ramos, A; Sato, K; Gonzalez, P; Panarello, H; Roverano, D

    2001-01-01

    The Umango Hill (La Rioja Province, 29 o 00'S-68 o 40'W) is one of the mountain blocks of Sierras Pampeanas Occidentales (Caminos, 1979), bounded by thrust faults and surrounded by Upper Devonian to Tertiary marine and continental sedimentites. The exposed crystalline basement is composed of basic igneous rocks and a siliciclastic-limestone sequence, both affected by amphibolite facies metamorphic peak. In the southern area (Juchi creek), the metamorphic complex carries relics of granitic orthogneisses, with Rb/Sr and U/Pb dates of ∼1000 Ma (Varela et al., 1996). These ancient inliers were asigned to a Mesoproterozoic Grenville Orogenic Cycle. Granitic bodies, intrusives at different ages in the Metamorphic Complex, have also been distinguished. The most ancient is El Penon Granite, with 469±9 Ma Rb/Sr age (Varela et al., 2000) and 523±26 Ma U/Pb zircon age (unpublished data). In this way it is possible to point out broadly that the siliciclastic-limestone sequence belongs to the Neoproterozoic-Early Palaeozoic times. It was a platform cover over grenvillian cratonic basement. The metamorphism and deformation, we understand, took place in the Early Palaeozoic, related to the Pampean-Famatinian Orogenic Cycle. In this work, compositional and isotopic data of Strontium ( 87 Sr/ 86 Sr), Carbon (δ 13 Cv PDB ) and Oxygen (δ 18 Ov PDB ) of the marbles derived from the siliciclastic-limestone sequence are presented. The results are interpreted and correlated with the temporal variation curves of 87 Sr/ 86 Sr and δ 13 C from Neoproterozoic marine carbonates (Jacobsen and Kaufman, 1999) (au)

  19. Ethanol flame synthesis of carbon nanotubes in deficient oxygen environments

    Science.gov (United States)

    Hu, Wei-Chieh; Lin, Ta-Hui

    2016-04-01

    In this study, carbon nanotubes (CNTs) were synthesized using ethanol diffusion flames in a stagnation-flow system composed of an upper oxidizer duct and a lower liquid pool. In the experiments, a gaseous mixture of oxygen and nitrogen flowed from the upper oxidizer duct, and then impinged onto the vertically aligned ethanol pool to generate a planar and steady diffusion flame in a deficient oxygen environment. A nascent nickel mesh was used as the catalytic metal substrate to collect deposited materials. The effect of low oxygen concentration on the formation of CNTs was explored. The oxygen concentration significantly influenced the flame environment and thus the synthesized carbon products. Lowering the oxygen concentration increased the yield, diameter, and uniformity of CNTs. The optimal operating conditions for CNT synthesis were an oxygen concentration in the range of 15%-19%, a flame temperature in the range of 460 °C-870 °C, and a sampling position of 0.5-1 mm below the upper edge of the blue flame front. It is noteworthy that the concentration gradient of C2 species and CO governed the CNT growth directly. CNTs were successfully fabricated in regions with uniform C2 species and CO distributions.

  20. Scaling up aqueous processing of A-site deficient strontium titanate for SOFC anode supports

    DEFF Research Database (Denmark)

    Verbraeken, Maarten C.; Sudireddy, Bhaskar Reddy; Vasechko, Viacheslav

    2018-01-01

    All ceramic anode supported half cells of technically relevant scale were fabricated in this study, using a novel strontium titanate anode material. The use of this material would be highly advantageous in solid oxide fuel cells due to its redox tolerance and resistance to coking and sulphur...... poisoning. Successful fabrication was possible through aqueous tape casting of both anode support and electrolyte layers and subsequent lamination. Screen printing of electrolyte layers onto green anode tapes was also attempted but resulted in cracked electrolyte layers upon firing. Microstructural...

  1. Hafnium carbide formation in oxygen deficient hafnium oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Rodenbücher, C. [Forschungszentrum Jülich GmbH, Peter Grünberg Institute (PGI-7), JARA-FIT, 52425 Jülich (Germany); Hildebrandt, E.; Sharath, S. U.; Kurian, J.; Komissinskiy, P.; Alff, L. [Technische Universität Darmstadt, Institute of Materials Science, 64287 Darmstadt (Germany); Szot, K. [Forschungszentrum Jülich GmbH, Peter Grünberg Institute (PGI-7), JARA-FIT, 52425 Jülich (Germany); University of Silesia, A. Chełkowski Institute of Physics, 40-007 Katowice (Poland); Breuer, U. [Forschungszentrum Jülich GmbH, Central Institute for Engineering, Electronics and Analytics (ZEA-3), 52425 Jülich (Germany); Waser, R. [Forschungszentrum Jülich GmbH, Peter Grünberg Institute (PGI-7), JARA-FIT, 52425 Jülich (Germany); RWTH Aachen, Institute of Electronic Materials (IWE 2), 52056 Aachen (Germany)

    2016-06-20

    On highly oxygen deficient thin films of hafnium oxide (hafnia, HfO{sub 2−x}) contaminated with adsorbates of carbon oxides, the formation of hafnium carbide (HfC{sub x}) at the surface during vacuum annealing at temperatures as low as 600 °C is reported. Using X-ray photoelectron spectroscopy the evolution of the HfC{sub x} surface layer related to a transformation from insulating into metallic state is monitored in situ. In contrast, for fully stoichiometric HfO{sub 2} thin films prepared and measured under identical conditions, the formation of HfC{sub x} was not detectable suggesting that the enhanced adsorption of carbon oxides on oxygen deficient films provides a carbon source for the carbide formation. This shows that a high concentration of oxygen vacancies in carbon contaminated hafnia lowers considerably the formation energy of hafnium carbide. Thus, the presence of a sufficient amount of residual carbon in resistive random access memory devices might lead to a similar carbide formation within the conducting filaments due to Joule heating.

  2. High-temperature vaporization behavior of oxygen-deficient thoria

    International Nuclear Information System (INIS)

    Ackermann, R.J.; Tetenbaum, M.

    1979-01-01

    The experimental results of the present study on the vaporization behavior of oxygen-deficient thoria are directed toward a more precise and detailed study of the lower phase boundary (l.p.b.) and congruently vaporizing composition (c.v.c), and intermediate compositions, and the corresponding oxygen potentials and total pressure at temperatures above 2000K. The l.p.b. and c.v.c. values were found to fit an equation of the form log x = A + (B/T), where x is the stoichiometric defect in ThO 2 -x. Oxygen potentials corresponding to the l.p.b. and c.v.c. have been estimated from vapor pressures and thermodynamic data. A very sharp decrease in oxygen potential occurs when thoria isreduced only slightly from the stoichiometric composition. In the temperature range from 2400 to 2655 K, the oxygen partial pressure dependency of x in ThO 2 -x was found to be approximately proportional to PO 2 - 1 /4to PO 2 - 1 /. The small extent of reduction over a wide range of oxygen potentials at these temperatures is a clear illustration of the higher stability of the ThO 2 -x phase compared with that of UO 2 -x. Values of ΔHO 2 and ΔSO 2 have been estimated for selected compositions from the dependence of the measured oxygen potential on temperature. Estimates of the standard free energy of formation of bivariant ThO 2 -x compositions have been made. A substantial increase in the total pressure of thorium-bearing species occurs when stoichiometric thoria is reduced toward the lower phase boundary. (orig.) [de

  3. Oxygen deficiency impacts on burying habitats for lesser sandeel, Ammodytes tobianus, in the inner Danish waters

    DEFF Research Database (Denmark)

    Behrens, Jane; Ærtebjerg, Gunni; Petersen, Jens Kjerulf

    2009-01-01

    Starting in 1980s, the inner Danish waters have yearly been exposed to seasonal oxygen deficiency (hypoxia). Through spatial–temporal interpolation of monitoring data (1998–2005), we investigated oxygen deficiency impacts on suitable burying habitats for lesser sandeel (Ammodytes tobianus...

  4. (La1-xSrx)0.98MnO3 perovskite with A-site deficiencies toward oxygen reduction reaction in aluminum-air batteries

    Science.gov (United States)

    Xue, Yejian; Miao, He; Sun, Shanshan; Wang, Qin; Li, Shihua; Liu, Zhaoping

    2017-02-01

    The strontium doped Mn-based perovskites have been proposed as one of the best oxygen reduction reaction catalysts (ORRCs) to substitute the noble metal. However, few studies have investigated the catalytic activities of LSM with the A-site deficiencies. Here, the (La1-xSrx)0.98MnO3 (LSM) perovskites with A-site deficiencies are prepared by a modified solid-liquid method. The structure, morphology, valence state and oxygen adsorption behaviors of these LSM samples are characterized, and their catalytic activities toward ORR are studied by the rotating ring-disk electrode (RRDE) and aluminum-air battery technologies. The results show that the appropriate doping with Sr and introducing A-site stoichiometry can effectively tailor the Mn valence and increase the oxygen adsorption capacity of LSM. Among all the LSM samples in this work, the (La0.7Sr0.3)0.98MnO3 perovskite composited with 50% carbon (50%LSM30) exhibits the best ORR catalytic activity due to the excellent oxygen adsorption capacity. Also, this catalyst has much higher durability than that of commercial 20%Pt/C. Moreover, the maximum power density of the aluminum-air battery using 50%LSM30 as the ORRC can reach 191.3 mW cm-2. Our work indicates that the LSM/C composite catalysts with A-site deficiencies can be used as a promising ORRC in the metal-air batteries.

  5. Strontium-free rare earth perovskite ferrites with fast oxygen exchange kinetics: Experiment and theory

    Science.gov (United States)

    Berger, Christian; Bucher, Edith; Windischbacher, Andreas; Boese, A. Daniel; Sitte, Werner

    2018-03-01

    The Sr-free mixed ionic electronic conducting perovskites La0.8Ca0.2FeO3-δ (LCF82) and Pr0.8Ca0.2FeO3-δ (PCF82) were synthesized via a glycine-nitrate process. Crystal structure, phase purity, and lattice constants were determined by XRD and Rietveld analysis. The oxygen exchange kinetics and the electronic conductivity were obtained from in-situ dc-conductivity relaxation experiments at 600-800 °C and 1×10-3≤pO2/bar≤0.1. Both LCF82 and PCF82 show exceptionally fast chemical surface exchange coefficients and chemical diffusion coefficients of oxygen. The oxygen nonstochiometry of LCF82 and PCF82 was determined by precision thermogravimetry. A point defect model was used to calculate the thermodynamic factors of oxygen and to estimate self-diffusion coefficients and ionic conductivities. Density Functional Theory (DFT) calculations on the crystal structure, oxygen vacancy formation as well as oxygen migration energies are in excellent agreement with the experimental values. Due to their favourable properties both LCF82 and PCF82 are of interest for applications in solid oxide fuel cell cathodes, solid oxide electrolyser cell anodes, oxygen separation membranes, catalysts, or electrochemical sensors.

  6. Growth and Properties of Oxygen and Ion Doped BISMUTH(2) STRONTIUM(2) Calcium COPPER(2) Oxygen (8+DELTA) Single Crystals

    Science.gov (United States)

    Mitzi, David Brian

    1990-01-01

    A directional solidification method for growing large single crystals in the Bi_2Sr _2CaCu_2O _{8+delta} system is reported. Ion substitutions, with replacement of La for Sr and Y for Ca, as well as oxygen doping in these crystals has been explored. Ion doping results in little change of the superconducting transition for substitution levels below 20-25% (as a result of simultaneous oxygen intercalation), while beyond this level, the Meissner signal broadens and the low temperature Meissner signal decreases. Microprobe analysis and x-ray diffraction performed on these more highly substituted single crystals, provides evidence for inhomogeneity and phase segregation into regions of distinct composition. Annealing unsubstituted crystals in increasing partial pressures of oxygen reversibly depresses the superconducting transition temperature from 90K (as made) to 77K (oxygen pressure annealed) while the Hall concentrations increase from n = 3.1(3) times 10 ^{21} cm^{ -3} (0.34 holes/Cu site) to 4.6(3) times 10^{21} cm^{-3} (0.50 holes/Cu site). Further suppression of T_{c} to 72K is possible by annealing in oxygen pressures up to 100atm. No degradation of the Meissner transition or other indications of inhomogeneity or phase segregation with doping are noted, suggesting that oxygen doped Bi_2Sr _2CaCu_2O _{8+delta} is a suitable system for pursuing doping studies. The decrease in T _{c} with concentration for 0.34 <=q n <=q 0.50 indicates that a high carrier concentration regime exists where T_{c} decreases with n and suggests that this decrease does not arise from material inhomogeneity or other materials problems. The physical properties of these Bi _2Sr_2CaCu _2O_{8+delta} crystals, in this high carrier concentration regime, will be discussed.

  7. High temperature thermoelectric properties of strontium titanate thin films with oxygen vacancy and niobium doping

    KAUST Repository

    Sarath Kumar, S. R.

    2013-08-14

    We report the evolution of high temperature thermoelectric properties of SrTiO3 thin films doped with Nb and oxygen vacancies. Structure-property relations in this important thermoelectric oxide are elucidated and the variation of transport properties with dopant concentrations is discussed. Oxygen vacancies are incorporated during growth or annealing in Ar/H2 above 800 K. An increase in lattice constant due to the inclusion of Nb and oxygen vacancies is found to result in an increase in carrier density and electrical conductivity with simultaneous decrease in carrier effective mass and Seebeck coefficient. The lattice thermal conductivity at 300 K is found to be 2.22 W m-1 K-1, and the estimated figure of merit is 0.29 at 1000 K. © 2013 American Chemical Society.

  8. High temperature thermoelectric properties of strontium titanate thin films with oxygen vacancy and niobium doping

    KAUST Repository

    Sarath Kumar, S. R.; Barasheed, Abeer Z.; Alshareef, Husam N.

    2013-01-01

    We report the evolution of high temperature thermoelectric properties of SrTiO3 thin films doped with Nb and oxygen vacancies. Structure-property relations in this important thermoelectric oxide are elucidated and the variation of transport properties with dopant concentrations is discussed. Oxygen vacancies are incorporated during growth or annealing in Ar/H2 above 800 K. An increase in lattice constant due to the inclusion of Nb and oxygen vacancies is found to result in an increase in carrier density and electrical conductivity with simultaneous decrease in carrier effective mass and Seebeck coefficient. The lattice thermal conductivity at 300 K is found to be 2.22 W m-1 K-1, and the estimated figure of merit is 0.29 at 1000 K. © 2013 American Chemical Society.

  9. Oxygen exchange and diffusion coefficients of strontium-doped lanthanum ferrites by electrical conductivity relaxation

    NARCIS (Netherlands)

    ten Elshof, Johan E.; Lankhorst, M.H.R.; Lankhorst, M.H.R.; Bouwmeester, Henricus J.M.

    1997-01-01

    Electrical conductivity relaxation experiments were performed on thin specimens of La1–xSrxFeO3–delta (x = 0.1, 0.4) at oxygen partial pressures pO2 = 10–5 – 1 bar in the temperature range 923 to 1223 K. The transient response of the electrical conductivity after a sudden change of the ambient

  10. Strontium geochemistry and carbon and oxygen isotopic compositions of Lower Proterozoic dolomite and calcite marbles from the Marmorilik Formation, West Greenland

    International Nuclear Information System (INIS)

    Garde, A.A.

    1979-01-01

    The Marmorilik Formation, Rinkian mobile belt, West Greenland, is a large, Lower Proterozoic carbonate-rock sequence, deformed and metamorphosed under greenschist to amphibolite facies conditions. The pre-deformation thickness of the sequence is at least 2000 m, with about 1400 m of dolomite marble and 350 m of calcite marble. Strontium contents of forty-two dolomite and calcite marbles range from 30 to 100 ppm and 300 to 800 ppm, respectively, whereas samples with calcite of secondary origin have strontium contents between 80 ppm and 200 ppm. Carbon and oxygen isotope ratios were determined for forty calcite and dolomite marbles as -0.2+-1.0 per 1000 delta 13 C and -9.9+-1.5 per 1000 delta 18 O (vs. PDB) and are compatible with the isotopic compositions of unmetamorphosed carbonates of similar age. Calcite from eight calciumsilicate rocks, breccias and calcite veins is significantly more negative in delta 13 C and delta 18 O. Five 13 C analyses of graphite in marble range from -9.6 to -14 per 1000. Possible post-depositional changes in the strontium content and carbon and oxygen isotope compositions are discussed. It is concluded that (a) the calcite marbles are not dedolomites and are therefore of primary origin, (b) the delta 13 C and delta 18 O values of the marbles are primary or diagenetic (i.e., pre-metamorphic), and (c) the isotopic composition of the graphite is compatible with, though not necessarily evidence for, a biogenic origin. (Auth.)

  11. Conversion of toluene and water to methylcyclohexane and oxygen using niobium-doped strontium titanate photoelectrodes.

    Science.gov (United States)

    Kalousek, Vit; Wang, Peng; Minegishi, Tsutomu; Hisatomi, Takashi; Nakagawa, Kojiro; Oshima, Shinji; Kobori, Yoshihiro; Kubota, Jun; Domen, Kazunari

    2014-09-01

    Methylcyclohexane (MCH) is regarded as a promising hydrogen carrier that enables hydrogen to be harnessed as an alternate fuel source, which paves the way to a clean-energy future. A photoelectrochemical (PEC) system with a Nb:SrTiO3 photoelectrode for oxygen evolution from an aqueous electrolyte and a Pt/C electrode for toluene (TL) hydrogenation to MCH was investigated under UV irradiation. A Nb:SrTiO3 single-crystal electrode and an ionomer/Pt/C membrane-electrode assembly (MEA) were used as the photoanode and cathode, respectively. A steady-state current density of 0.12 mA cm(-2) was observed for the two-electrode system without any bias voltage for >2 h, and a Faradaic efficiency of 97% was obtained for MCH production from TL. This is the first demonstration of the production of MCH from TL and water using only light energy. This means that light energy was converted directly into MCH from TL and water without any electricity. The PEC properties of the devices are discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Effects of diagenesis on strontium, carbon, nitrogen and oxygen concentration and isotopic composition of bone

    Science.gov (United States)

    Nelson, Bruce K.; Deniro, Michael J.; Schoeninger, Margaret J.; De Paolo, Donald J.; Hare, P. E.

    1986-09-01

    Paleodietary analysis based on variations in the trace element and stable isotopic composition of inorganic and organic phases in fossil bone depends on the assumption that measured values reflect in vivo values. To test for postmortem alteration, we measured 87Sr /86Sr , 13C /12C , 18O /16O and 15N /14N ratios and Sr concentrations in modern and prehistoric (610 to 5470 yr old) bones of animals with marine or terrestrial diets from Greenland. Bones from modern terrestrial feeders have substantially lower Sr concentrations and more radiogenic 87Sr /86Sr ratios than those from modern marine feeders. This contrast was not preserved in the prehistoric samples, which showed almost complete overlap for both Sr concentration and isotopic composition in bones from the two types of animals. Leaching experiments, X-ray diffraction analysis and infrared spectroscopy indicate that alteration of the Sr concentration and isotopic composition in prehistoric bone probably results from nearly complete exchange with groundwater. Oxygen isotope ratios in fossil apatite carbonate also failed to preserve the original discrimination between modern terrestrial and marine feeders. The C isotope ratio of apatite carbonate did not discriminate between animals with marine or terrestrial diets in the modern samples. Even so, the ranges of apatite δ 13C values in prehistoric bone are more scattered than in modern samples for both groups, suggesting alteration had occurred. δ 13C and δ 15N values of collagen in modern bone are distinctly different for the two feeding types, and this distinction is preserved in most of the prehistoric samples. Our results suggest that postmortem alteration of dietary tracers in the inorganic phases of bone may be a problem at all archaeological sites and must be evaluated in each case. While collagen analyzed in this study was resistant to alteration, evaluation of the possibility of diagenetic alteration of its isotopic composition in bones from other

  13. Seasonal oxygen deficiency over the western continental shelf of India

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Naik, H.; Jayakumar, D.A.; Shailaja, M.S.; Narvekar, P.V.

    , and their impact on biology and chemistry off the west coast of India are described here. The O2 deficiency in this region, associated with the seasonal (southwest monsoon) upwelling, seems to have intensified in recent years, presumably in response to enhanced...

  14. Effect of oxygen deficiency on electronic properties and local structure of amorphous tantalum oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Denny, Yus Rama [Department of Physics Education, University of Sultan Ageng Tirtayasa, Banten 42435 (Indonesia); Firmansyah, Teguh [Department of Electrical Engineering, University of Sultan Ageng Tirtayasa, Banten 42435 (Indonesia); Oh, Suhk Kun [Department of Physics, Chungbuk National University, Cheongju 28644 (Korea, Republic of); Kang, Hee Jae, E-mail: hjkang@cbu.ac.kr [Department of Physics, Chungbuk National University, Cheongju 28644 (Korea, Republic of); Yang, Dong-Seok [Department of Physics Education, Chungbuk National University, Cheongju 28644 (Korea, Republic of); Heo, Sung; Chung, JaeGwan; Lee, Jae Cheol [Analytical Engineering Center, Samsung Advanced Institute of Technology, Suwon 16678 (Korea, Republic of)

    2016-10-15

    Highlights: • The effect of oxygen flow rate on electronic properties and local structure of tantalum oxide thin films was studied. • The oxygen deficiency induced the nonstoichiometric state a-TaOx. • A small peak at 1.97 eV above the valence band side appeared on nonstoichiometric Ta{sub 2}O{sub 5} thin films. • The oxygen flow rate can change the local electronic structure of tantalum oxide thin films. - Abstract: The dependence of electronic properties and local structure of tantalum oxide thin film on oxygen deficiency have been investigated by means of X-ray photoelectron spectroscopy (XPS), Reflection Electron Energy Loss Spectroscopy (REELS), and X-ray absorption spectroscopy (XAS). The XPS results showed that the oxygen flow rate change results in the appearance of features in the Ta 4f at the binding energies of 23.2 eV, 24.4 eV, 25.8, and 27.3 eV whose peaks are attributed to Ta{sup 1+}, Ta{sup 2+}, Ta{sup 3+}/Ta{sup 4+}, and Ta{sup 5+}, respectively. The presence of nonstoichiometric state from tantalum oxide (TaOx) thin films could be generated by the oxygen vacancies. In addition, XAS spectra manifested both the increase of coordination number of the first Ta-O shell and a considerable reduction of the Ta-O bond distance with the decrease of oxygen deficiency.

  15. STRONTIUM PRECIPITATION

    Science.gov (United States)

    McKenzie, T.R.

    1960-09-13

    A process is given for improving the precipitation of strontium from an aqueous phosphoric-acid-containing solution with nickel or cobalt ferrocyanide by simultaneously precipitating strontium or calcium phosphate. This is accomplished by adding to the ferrocyanide-containing solution calcium or strontium nitrate in a quantity to yield a concentration of from 0.004 to 0.03 and adjusting the pH of the solution to a value of above 8.

  16. Effect of oxygen deficiency on the magnetic field-dependent entropy ...

    Indian Academy of Sciences (India)

    Moreover, to account for the applicability of the theory at high field, we have incorporated the effect of vortex overlapping in the London theory done by Nanda (1995). Here, we have presented the variation of change in entropy (S) with magnetic field for different oxygen deficiencies = 0, 0.04, and 0.06. On comparison ...

  17. Ordered oxygen deficient '112'perovskites, LnBaCo2 O5⋅ 50 ...

    Indian Academy of Sciences (India)

    ... Refresher Courses · Symposia · Live Streaming. Home; Journals; Bulletin of Materials Science; Volume 32; Issue 3. Ordered oxygen deficient '112' perovskites, LnBaCo2O5.50+: complex magnetism and transport properties. B Raveau Md Motin Seikh V Pralong V Caignaert. Volume 32 Issue 3 June 2009 pp 305-312 ...

  18. Deficient by oxygen perovskites and superconductor with transition temperature 93 K

    International Nuclear Information System (INIS)

    Ross, N.L.; Angel, R.J.; Finger, L.W.; Hazen, R.M.; Prewitt, K.T.

    1988-01-01

    Structural changes in some perovskites deficient by oxygen is reviewd. The structure of the high-temperature YBa 2 Cu 3 O 7-x superconductor is shown to develop usual for perovskites properties and at the same time to possess specific features. The specific feature includes the fact that ordering of vacancies and oxygen atoms is the consequence of Ba 2+ and Y 3+ ordering in positions A. Such ordering causes the removal of oxygen atoms plane from the structure and accurrence of pyramidal-coordinated atoms Cu2 in positions B. 22 refs.; 3 figs.; 2 tabs

  19. Dinitrogen Fixation Within and Adjacent to Oxygen Deficient Waters of the Eastern Tropical South Pacific Ocean

    Science.gov (United States)

    Widner, B.; Mulholland, M. R.; Bernhardt, P. W.; Chang, B. X.; Jayakumar, A.

    2016-02-01

    Recent work suggests that planktonic diazotrophs are geographically more widely distributed than previously thought including relatively warm (14-23oC) aphotic oxygenated pelagic waters and in aphotic waters within oxygen deficient zones. Because the volume of aphotic water in the ocean is large and may increase in the future, if dinitrogen (N2) fixation is widely occurring at sub-euphotic depths, this could result in a dramatic upward revision of global nitrogen (N) inputs via this process. N2 fixation rates were measured during a cruise in the Eastern Tropical South Pacific using stable isotope tracer techniques that account for slow gas dissolution. Results are compared with light, nutrient, and oxygen gradients (and necessarily temperature gradients). In addition, rates of N2 fixation made in vertical profiles within and above oxygen deficient waters are compared with those measured in vertical profiles adjacent to oxygen deficient waters. Results suggest that while rates of N2 fixation were measurable in deeper anoxic waters, volumetric N2 fixation rates were higher in surface waters.

  20. Oxygen deficiency in MoO{sub 3} polycrystalline nanowires and nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Varlec, Ana, E-mail: ana.varlec@ijs.si [Condensed Matter Physics, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Arčon, Denis [Condensed Matter Physics, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Faculty of Mathematics and Physics, University of Ljubljana, Jadranska cesta 19, SI-1000 Ljubljana (Slovenia); Škapin, Srečo D. [Advanced Materials Department, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Remškar, Maja [Condensed Matter Physics, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia)

    2016-02-15

    We report on the synthesis of polycrystalline molybdenum oxide (MoO{sub 3}) nanowires via oxidation of molybdenum-sulfur-iodine (Mo{sub 6}S{sub 2}I{sub 8}) nanowires. This unique synthesis route results in an interesting morphology comprising porous nanowires and nanotubes. We found the nanowires to have the orthorhombic MoO{sub 3} structure. The structure is slightly oxygen deficient which results in the appearance of a new resonant Raman band (1004 cm{sup −1}) and paramagnetic defects (Mo{sup 5+}) of both the point and crystallographic shear plane nature. - Highlights: • Polycrystalline MoO{sub 3} nanowires were obtained via oxidation of Mo{sub 6}S{sub 2}I{sub 8} nanowires. • Nanowires are porous and tubular with either filled or empty interior. • Nanowires are slightly oxygen deficient which leads to a new Raman band.

  1. Molecular diversity of fungi from marine oxygen-deficient environments (ODEs)

    Digital Repository Service at National Institute of Oceanography (India)

    Manohar, C.S.; Forster, D.; Kauff, F.; Stoeck, T.

    . Sparrow Jr F K (1936) Biological observations of the marine fungi of woods hole waters. Biol Bull 70: 236-263. States JS & Christensen M (2001) Fungi Associated with Biological Soil Crusts in Desert Grasslands of Utah and Wyoming. Mycologia 93: 432... version: Biology of marine fungi. Ed. by: Raghukumar, C. (Prog. Mol. Subcellular Biol). Springer, vol.53 (Chap 10); 2012; 189-208 Chapter # 10 Molecular diversity of fungi from marine oxygen-deficient environments (ODEs) Cathrine S. Jebaraj 1...

  2. Magnetism and metal-insulator transition in oxygen deficient SrTiO3

    Science.gov (United States)

    Lopez-Bezanilla, Alejandro; Ganesh, P.; Littlewood, Peter

    2015-03-01

    We report new findings in the electronic structure and magnetism of oxygen vacancies in SrTiO3. By means of first-principles calculations we show that the appearance of magnetism in oxygen-deficient SrTiO3 is not determined solely by the presence of a single oxygen vacancy but by the density of free carriers and the relative proximity of the vacant sites. While an isolated vacancy behaves as a non-magnetic double donor, manipulation of the doping conditions allows the stability of a single donor state with emergent local moments. Strong local lattice distortions enhance the binding of this state. Consequently we find that the free-carrier density and strain are fundamental components to obtaining trapped spin-polarized electrons in oxygen-deficient SrTiO3, which may have important implications in the design of switchable magneto-optic devices. AL-B and PBL were supported by DOE-BES under Contract No. DE-AC02-06CH11357. PG was sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT- Battelle, LLC, for the US Department of Energy.

  3. Accumulation of Fe oxyhydroxides in the Peruvian oxygen deficient zone implies non-oxygen dependent Fe oxidation

    Science.gov (United States)

    Heller, Maija I.; Lam, Phoebe J.; Moffett, James W.; Till, Claire P.; Lee, Jong-Mi; Toner, Brandy M.; Marcus, Matthew A.

    2017-08-01

    Oxygen minimum zones (OMZs) have been proposed to be an important source of dissolved iron (Fe) into the interior ocean. However, previous studies in OMZs have shown a sharp decrease in total dissolved Fe (dFe) and/or dissolved Fe(II) (dFe(II)) concentrations at the shelf-break, despite constant temperature, salinity and continued lack of oxygen across the shelf-break. The loss of both total dFe and dFe(II) suggests a conversion of the dFe to particulate form, but studies that have coupled the reduction-oxidation (redox) speciation of both dissolved and particulate phases have not previously been done. Here we have measured the redox speciation and concentrations of both dissolved and particulate forms of Fe in samples collected during the U.S. GEOTRACES Eastern tropical Pacific Zonal Transect (EPZT) cruise in 2013 (GP16). This complete data set allows us to assess possible mechanisms for loss of dFe. We observed an offshore loss of dFe(II) within the oxygen deficient zone (ODZ), where dissolved oxygen is undetectable, accompanied by an increase in total particulate Fe (pFe). Total pFe concentrations were highest in the upper ODZ. X-ray absorption spectroscopy revealed that the pFe maximum was primarily in the Fe(III) form as Fe(III) oxyhydroxides. The remarkable similarity in the distributions of total particulate iron and nitrite suggests a role for nitrite in the oxidation of dFe(II) to pFe(III). We present a conceptual model for the rapid redox cycling of Fe that occurs in ODZs, despite the absence of oxygen.

  4. Evolution of Oxygen Deficiency Center on Fused Silica Surface Irradiated by Ultraviolet Laser and Posttreatment

    Directory of Open Access Journals (Sweden)

    Hai-Bing Lü

    2014-01-01

    Full Text Available Evolution of oxygen deficiency centers (ODCs on a fused silica surface irradiated using a 355 nm ultraviolet (UV laser beam in both vacuum and atmospheric conditions was quantitatively studied using photoluminescence and X-ray photoelectron spectroscopy. When the fusedsilica surface was exposed to the UV laser in vacuum, the laser damage threshold was decreased whereas the concentration of the ODCs was increased. For the fuse silica operated under the high power lasers, creation of ODCs on their surface resulted from the UV laser irradiation, and this is more severe in a high vacuum. The laser fluence and/or laser intensity have significant effects on the increase of the ODCs concentration. The ODCs can be effectively repaired using postoxygen plasma treatment and UV laser irradiation in an excessive oxygen environment. Results also demonstrated that the “gain” and “loss” of oxygen at the silica surface is a reversible and dynamic process.

  5. High-resolution spectra of stars in globular clusters. VI - Oxygen-deficient red giant stars in M13

    International Nuclear Information System (INIS)

    Brown, J.A.; Wallerstein, G.; Oke, J.B.

    1991-01-01

    From high-resolution, high signal-to-noise spectra, abundances of carbon, nitrogen, and oxygen and the C-12/C-13 ratio for five red giants in M13, including star II-67, which has previously been reported to be deficient in oxygen have been determined. Three of the five stars exhibit substantial oxygen deficiencies; O/Fe values range from +0.5 to less than about 0.3. The sum of the CNO nuclides is the same for all stars, which is interpreted as evidence that mixing of CNO-cycled material into the envelope is the cause of the variations in oxygen abundance. 41 refs

  6. Charge doping and large lattice expansion in oxygen-deficient heteroepitaxial WO3

    Science.gov (United States)

    Mattoni, Giordano; Filippetti, Alessio; Manca, Nicola; Zubko, Pavlo; Caviglia, Andrea D.

    2018-05-01

    Tungsten trioxide (WO3) is a versatile material with widespread applications ranging from electrochromics and optoelectronics to water splitting and catalysis of chemical reactions. For technological applications, thin films of WO3 are particularly appealing, taking advantage from a high surface-to-volume ratio and tunable physical properties. However, the growth of stoichiometric crystalline thin films is challenging because the deposition conditions are very sensitive to the formation of oxygen vacancies. In this paper, we show how background oxygen pressure during pulsed laser deposition can be used to tune the structural and electronic properties of WO3 thin films. By performing x-ray diffraction and low-temperature electrical transport measurements, we find changes in the WO3 lattice volume of up to 10% concomitantly with a resistivity drop of more than five orders of magnitude at room temperature as a function of increased oxygen deficiency. We use advanced ab initio calculations to describe in detail the properties of the oxygen vacancy defect states and their evolution in terms of excess charge concentration. Our results depict an intriguing scenario where structural, electronic, optical, and transport properties of WO3 single-crystal thin films can all be purposely tuned by controlling the oxygen vacancy formation during growth.

  7. Intracellular nitrate in sediments of an oxygen-deficient marine basin is linked to pelagic diatoms

    DEFF Research Database (Denmark)

    Kamp, Anja; Petro, Caitlin; Røy, Hans

    2018-01-01

    Intracellular nitrate is an important electron acceptor in oxygen-deficient aquatic environments, either for the nitrate-storing microbes themselves, or for ambient microbial communities through nitrate leakage. This study links the spatial distribution of intracellular nitrate with the abundance...... and identity of nitrate-storing microbes in sediments of the Bornholm Basin, an environmental showcase for severe hypoxia. Intracellular nitrate (up to 270 nmol cm−3 sediment) was detected at all 18 stations along a 35-km transect through the basin and typically extended as deep as 1.6 cm into the sediment...

  8. μ+ SR study of antiferromagnetism and superconductivity in oxygen deficient YBa2Cu3Ox

    International Nuclear Information System (INIS)

    Brewer, J.H.; Carolan, J.; Chaklader, A.C.D.; Hardy, W.N.; Hayden, M.; Kaplan, N.; Kempton, J.; Kiefl, R.F.; Kreitzman, S.R.; Kulpa, A.; Luke, G.M.; Riseman, T.M.; Roehmer, G.; Schleger, P.; Williams, D.L.; Ansaldo, E.J.; Kossler, W.J.; Watanabe, Y.; Yamazaki, T.

    1987-12-01

    Positive muon spin rotation and relaxation (μ + SR) measurements of the oxygen-deficient perovskite YBa 2 Cu 3 O x have revealed local antiferromagnetic (AFM) order for 6.0 ≤ ∼ x ≤ ∼ 6.4 with a Neel temperature T N that decreases rapidly with increasing oxygen content x. For carefully annealed samples with 6.35 ≤ ∼ x ≤ ∼ 6.5 the superconducting (SC) transition temperature T C increases smoothly with x from 25 K at x=6.348 to 60 K at x=6.507. Two such samples with x = 6.348 and x = 6.400 seem to 'switch' from SC to AFM at low temperatures. (Author) (10 refs., 3 figs.)

  9. Study on the effects of fluorine and oxygen deficiency on YBa2Cu3O7 by ab initio method

    Institute of Scientific and Technical Information of China (English)

    刘洪霖; 曹晓卫; 瞿丽曼; 陈念贻

    1997-01-01

    The calculations of clusters modeling the fluorine-doping and oxygen deficiency of YBa2Cu3O2,have been performed by the method of all-electron ab initio Hartree-Fock with self-consistent crystal field Results show that in CuO planes electric charge significantly increases,the chemical valence of Cu decreases and the covalent bonding of Cu-O greatly weakens owing to oxygen deficiency,while the effect of F restores the local electronic structure of YBa2Cu3O7 The reported opinion that F occupied the oxygen vacancy in Cu-O chains seems disputable according to the calculated bonding characteristics.

  10. A normalised seawater strontium isotope curve. Possible implications for Neoproterozoic-Cambrian weathering rates and the further oxygenation of the Earth

    International Nuclear Information System (INIS)

    Shields, G.A.

    2007-01-01

    The strontium isotope composition of seawater is strongly influenced on geological time scales by changes in the rates of continental weathering relative to ocean crust alteration. However, the potential of the seawater 87 Sr/ 86 Sr curve to trace globally integrated chemical weathering rates has not been fully realised because ocean 87 Sr/ 86 Sr is also influenced by the isotopic evolution of Sr sources to the ocean. A preliminary attempt is made here to normalise the seawater 87 Sr/ 86 Sr curve to plausible trends in the 87 Sr/ 86 Sr ratios of the three major Sr sources: carbonate dissolution, silicate weathering and submarine hydrothermal exchange. The normalised curve highlights the Neoproterozoic-Phanerozoic transition as a period of exceptionally high continental influence, indicating that this interval was characterised by a transient increase in global weathering rates and/or by the weathering of unusually radiogenic crustal rocks. Close correlation between the normalised 87 Sr/ 86 Sr curve, a published seawater δ 34 S curve and atmospheric pCO 2 models is used here to argue that elevated chemical weathering rates were a major contributing factor to the steep rise in seawater 87 Sr/ 86 Sr from 650 Ma to 500 Ma. Elevated weathering rates during the Neoproterozoic-Cambrian interval led to increased nutrient availability, organic burial and to the further oxygenation of Earth's surface environment. Use of normalised seawater 87 Sr/ 86 Sr curves will, it is hoped, help to improve future geochemical models of Earth System dynamics. (orig.)

  11. Lack of oxygen effect in glutathione-deficient human cells in culture

    International Nuclear Information System (INIS)

    Edgren, M.; Larsson, A.; Nilsson, K.; Revesz, L.; Scott, O.C.A.

    1980-01-01

    The frequency of X-ray-induced DNA breaks was determined in human cell lines which are deficient in glutathione synthetase and have a greatly reduced glutathione content. Hydroxyapatite chromatography was used for the estimation of the DNA breaks in cell cultures, which were derived either from lymphoblasts transformed by infection with EB virus or from fibroblasts. The dose-effect relationship for the induction of breaks when radiation exposure was made in argon, was similar to that found when exposure was made in air. In control cultures with normal glutathione content, the induction of breaks was enhanced when irradiation was made under aerobic, instead of anaerobic, conditions. Treatment of the glutathione-deficient cells with the hypoxic radiosensitizer misonidazole did not enhance the induction of breaks by radiation delivered either in air or in argon. In control cultures, radiation induction of breaks was enhanced by misonidazole under anaerobic but not under aerobic conditions. When the glutathione-deficient cells were pretreated with cysteamine however, irradiation in the absence of oxygen resulted in a decreased frequency of DNA breaks. (author)

  12. Synthesis of surface oxygen-deficient BiPO{sub 4} nanocubes with enhanced visible light induced photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Bingtao; Yin, Haoyong; Li, Tao; Gong, Jianying; Lv, Shumei; Nie, Qiulin, E-mail: yhy@hdu.edu.cn [College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou (China)

    2017-05-15

    The visible light driven BiPO{sub 4} nanocubes with sufficient surface oxygen deficiency were fabricated by a hydrothermal process and subsequently ultrasonic assistant Fe reduction process. The products were characterized by XRD, DRS, XPS, SEM and TEM which showed that the BiPO{sub 4} had cuboid-like shape with a smooth surface and clear edges and the oxygen vacancies were successfully introduced on the surface of the BiPO{sub 4} nanocubes. The as prepared oxygen-deficient BiPO{sub 4} nanocubes showed greatly enhanced visible light induced photocatalytic activity in degradation of Rhodamine B. The enhanced photocatalytic performance and expanded visible light response of BiPO{sub 4} may be due to the introduction of surface oxygen vacancies which can generate the oxygen vacancies mid-gap states lower to the conduction band of BiPO{sub 4}. (author)

  13. Interplay of oxygen octahedral rotations and electronic instabilities in strontium ruthenate Ruddlesden-Poppers from first principles

    Science.gov (United States)

    Voss, Johannes; Fennie, Craig J.

    2011-03-01

    The Ruddlesden-Popper ruthenates Sr n+1 Ru n O3 n + 1 display a broad range of electronic phases including p -wave superconductivity, electronic nematicity, and ferromagnetism. Elucidating the role of the number of perovskite blocks, n , in the realization of these differently ordered electronic states remains a challenge. Additionally dramatic experimental advances now enable the atomic scale growth of these complex oxide thin films on a variety of substrates coherently, allowing for the application of tunable epitaxial strain and subsequently the ability to control structural distortions such as oxygen octahedral rotations. Here we investigate from first principles the effect of oxygen octahedral rotations on the electronic structure of Sr 2 Ru O4 and Sr 3 Ru 2 O7 . We discuss possible implications for the physics of the bulk systems and point towards new effects in thin films.

  14. A study on oxygen-deficient YBa2Cu3O7-δ superconductors by positron lifetime spectroscopy

    International Nuclear Information System (INIS)

    Zhang Jincang; Liu Fengqi; Liu Junzheng; Cao Shixun; Cheng Guosheng

    1995-01-01

    Positron lifetime spectroscopy has been used for studying various oxygen-deficient YBa 2 Cu 3 O 7 - δ (δ = 0.06-0.68) at normal state (300 K) and Superconducting state (77 K). Using the two-state trapping model, the experimental results were analysed and there exists a typical positron annihilation characteristics in this systems. The local electron density n e and vacancy concentration C v are calculated as a function of oxygen-deficiency δ. The mechanism of positron annihilation and the correlation with superconductivity are also discussed

  15. Oxygen-deficient hematite nanorods as high-performance and novel negative electrodes for flexible asymmetric supercapacitors.

    Science.gov (United States)

    Lu, Xihong; Zeng, Yinxiang; Yu, Minghao; Zhai, Teng; Liang, Chaolun; Xie, Shilei; Balogun, Muhammad-Sadeeq; Tong, Yexiang

    2014-05-21

    Oxygen-deficient α-Fe2 O3 nanorods with outstanding capacitive performance are developed and demonstrated as novel negative electrodes for flexible asymmetric supercapacitors. The asymmetric-supercapacitor device based on the oxygen-deficient α-Fe2 O3 nanorod negative electrode and a MnO2 positive electrode achieves a maximum energy density of 0.41 mW·h/cm(3) ; it is also capable of charging a mobile phone and powering a light-emitting diode indicator. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Fluctuations Magnetiques des Gaz D'electrons Bidimensionnels: Application AU Compose Supraconducteur LANTHANE(2-X) Strontium(x) Cuivre OXYGENE(4)

    Science.gov (United States)

    Benard, Pierre

    . Il est ensuite demontre que le modele a trois bandes predit les memes resultats pour la position des structures du facteur de structure magnetique que le modele a une bande, dans la limite ou l'hybridation des orbitales des atomes d'oxygene des plans Cu-O_2 et l'amplitude de sauts vers les seconds voisins sont nulles. Il est de plus constate que l'effet de l'hybridation des orbitales des atomes d'oxygene est bien modelise par le terme de saut vers les seconds voisins. Meme si ils decrivent correctement le comportement qualitatif des maximums du facteur de structure magnetique, les modeles a trois bandes et a une bande ne permettent pas d'obtenir une position de ces structures conforme avec les mesures experimentales, si on suppose que la bande est rigide, c'est-a-dire que les parametres du Hamiltonien sont independants de la concentration de strontium. Ceci peut etre cause par la dependance des parametres du Hamiltonien sur la concentration de strontium. Finalement, les resultats sont compares avec les experiences de diffusion de neutrons et les autres theories, en particulier celles de Littlewood et al. (1993) et de Q. Si et al. (1993). La comparaison avec les resultats experimentaux pour le compose de lanthane suggere que le liquide de Fermi possede une surface de Fermi disjointe, et qu'il est situe pres d'une instabilite magnetique incommensurable.

  17. Distribution and Magnitude of Dinitrogen Fixation in the Eastern Tropical North Pacific Oxygen Deficient Zone.

    Science.gov (United States)

    Selden, C.; Mulholland, M. R.; Widner, B.; Bernhardt, P. W.; Macías Tapia, A.; Jayakumar, A.

    2016-12-01

    The Eastern Tropical North Pacific Ocean (ETNP) hosts one of the world's three major open ocean oxygen deficient zones (ODZs). Hotspots for fixed nitrogen (N) loss processes, ODZs have classically been discounted as areas of significant dinitrogen (N2) fixation, the microbe-mediated reduction of N2 to ammonium (NH4+), which has historically been ascribed primarily to euphotic, nutrient-deplete tropical waters. Challenging this paradigm, active expression of nifH (the dinitrogen reductase structural gene) has recently been documented in the ETNP, Eastern Tropical South Pacific, and Arabian Sea ODZs, implying a closer coupling of fixed nitrogen input and loss processes than previously thought. Here, we report rates of N­2 fixation measured in the ETNP ODZ along vertical gradients of oxygen, light, and dissolved N concentrations. Detailed vertical profiles of N2 fixation rates and dissolved N concentrations made within the ODZ were compared with similar profiles from oxic waters outside the ODZ. In addition, different organic carbon sources were investigated as potential rate-limiting factors for N2 fixation in sub-euphotic waters. By establishing the magnitude and distribution of N­2 fixation in the ETNP ODZ, this study contributes to current understanding of N cycling in anoxic and aphotic waters, and serves to elucidate nuances in the global N budget, enabling more accurate biogeochemical modeling. Understanding these processes in present day ODZs is crucial for predicting how ongoing anthropogenic intensification of coastal ODZs will alter biogeochemical cycles in the future.

  18. Mechanical control of magnetism in oxygen deficient perovskite SrTiO3.

    Science.gov (United States)

    Zhang, Yajun; Wang, Jie; Sahoo, M P K; Shimada, Takahiro; Kitamura, Takayuki

    2015-10-28

    Mechanical control of magnetism in perovskite oxides is an important and promising approach in spintronics. Based on the first-principles calculations, we demonstrate that a negative pressure leads to a great enhancement of magnetic moment in deficient SrTiO3 with oxygen vacancies, whereas a positive pressure results in the gradual disappearance of magnetism. Spin charge density, Bader charge analysis and electronic density of states successfully elucidate the origin and underlying physics of the enhancement and disappearance of magnetism. It is found that the split electronic states of dz(2), dyz and dzx in the 3d orbitals of Ti atoms remarkably contribute to the occupancy of majority spin states under negative pressure, which induces a large magnetic moment. Under positive pressure, however, the equal occupancy of both majority and minority t2g and eg states leads to the disappearance of magnetization. In addition, both negative and positive pressures can largely lower the vacancy formation enthalpy, suggesting that the oxygen vacancy is preferable with pressure. Our findings may provide a mechanism to achieve the pressure control of magnetization in nonmagnetic perovskite oxides.

  19. Facile Aluminum Reduction Synthesis of Blue TiO2 with Oxygen Deficiency for Lithium-Ion Batteries.

    Science.gov (United States)

    Zheng, Jing; Ji, Guangbin; Zhang, Peng; Cao, Xingzhong; Wang, Baoyi; Yu, Linghui; Xu, Zhichuan J

    2015-12-07

    An ultrafacile aluminum reduction method is reported herein for the preparation of blue TiO2 nanoparticles (donated as Al-TiO2 , anatase phase) with abundant oxygen deficiency for lithium-ion batteries. Under aluminum reduction, the morphology of the TiO2 nanosheets changes from well-defined rectangular into uniform round or oval nanoparticles and the particle size also decreases from 60 to 31 nm, which can aggressively accelerate the lithium-ion diffusion. Electron paramagnetic resonance (EPR) and positron annihilation lifetime spectroscopy (PALS) results reveal that plentiful oxygen deficiencies relative to the Ti(3+) species were generated in blue Al-TiO2 ; this effectively enhances the electron conductivity of the TiO2 . X-ray photoelectron spectrometry (XPS) analysis indicates that a small peak is observed for the Al-O bond, which probably plays a very important role in the stabilization of the oxygen deficiencies/Ti(3+) species. As a result, the blue Al-TiO2 possesses significantly higher capacity, better rate performance, and a longer cycle life than the white pure TiO2 . Such improvements can be attributed to the decreased particle size, as well as the existence of the oxygen deficiencies/Ti(3+) species. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. On the oxygen deficiency of high-Tc Y1Ba2Cu3O7-μ ceramics

    International Nuclear Information System (INIS)

    Szasz, A.; Dankhazi, Z.; Kojnok, J.; Trager, T.; Matrai, J.; Gyorgy, I.; Kirchmayr, H.; Mueller, H.; Watson, L.M.

    1991-01-01

    The role of oxygen deficiency in Y 1 Ba 2 Cu 3 O 7-μ ceramics was investigated by differential thermal analysis (DTA), differential thermogravimetry (DTG), linear thermal expansion (LTE), and by soft x-ray fluorescence spectroscopy (SXFS). The interdependence of the measured parameters and some of the stability criteria are discussed

  1. Positron-annihilation study of oxygen-deficient YBa2Cu3Ox (6.3

    International Nuclear Information System (INIS)

    Tang, C.Q.; Li, B.R.; Chen, A.

    1990-01-01

    We have measured the positron-lifetime spectra of oxygen-deficient YBa 2 Cu 3 O x for 6.3 m , τ 1 , τ 2 , and I 2 have a significant oxygen-content dependence. It is suggested that there are many kinds of positron states in polycrystalline YBa 2 Cu 3 O x , the disordering of O(1) vacancies strongly affects positron lifetime, and with gradually decreasing x the average electronic density decreases and the configuration and/or the charge states of the oxygen vacancies change in the region containing Cu(1)-O(1) chains

  2. TrxR2 deficiencies promote chondrogenic differentiation and induce apoptosis of chondrocytes through mitochondrial reactive oxygen species

    International Nuclear Information System (INIS)

    Yan, Jidong; Xu, Jing; Fei, Yao; Jiang, Congshan; Zhu, Wenhua; Han, Yan; Lu, Shemin

    2016-01-01

    Thioredoxin reductase 2 (TrxR2) is a selenium (Se) containing protein. Se deficiency is associated with an endemic osteoarthropathy characterized by impaired cartilage formation. It is unclear whether TrxR2 have roles in cartilage function. We examined the effects of TrxR2 on chondrogenic ATDC5 cells through shRNA-mediated gene silencing of TrxR2. We demonstrated TrxR2 deficiencies could enhance chondrogenic differentiation and apoptosis of ATDC5 cells. TrxR2 deficiencies increased accumulation of cartilage glycosaminoglycans (GAGs) and mineralization. TrxR2 deficiencies also stimulated expression of extracellular (ECM) gene including Collagen II and Aggrecan. The enhanced chondrogenic properties were further confirmed by activation of Akt signaling which are required for chondrogenesis. In addition, TrxR2 deficiencies promoted chondrocyte proliferation through acceleration of cell cycle progression by increase in both S and G2/M phase cell distribution accompanied with induction of parathyroid hormone-related protein (PTHrP). Moreover, TrxR2 deficiencies induced chondrocyte death via apoptosis and increased cell sensitivity to exogenous oxidative stress. Furthermore, TrxR2 deficiencies induced emission of mitochondrial reactive oxygen species (ROS) without alteration of mitochondrial membrane potential and intracellular ATP content. Finally, treatment of TrxR2 deficiency cells with N-acetylcysteine (NAC) inhibited mitochondrial ROS production and chondrocyte apoptosis. NAC also prevented chondrogenic differentiation of TrxR2 deficiency cells by suppression of ECM gene expression, GAGs accumulation and mineralization, as well as attenuation of Akt signaling. Thus, TrxR2-mediated mitochondrial integrity is indispensable for chondrogenic differentiation of ATDC5 cells. TrxR2 deficiency-induced impaired proliferation and death of chondrocytes may be the pathological mechanism of the osteoarthropathy due to Se deficiency. Notably, this study also uncover the roles of

  3. TrxR2 deficiencies promote chondrogenic differentiation and induce apoptosis of chondrocytes through mitochondrial reactive oxygen species

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Jidong [Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi 710061 (China); Xu, Jing [Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi 710061 (China); Fei, Yao [College of Life Sciences, Northwest University, Xi’an, Shaanxi Province 710069 (China); Jiang, Congshan; Zhu, Wenhua; Han, Yan [Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi 710061 (China); Lu, Shemin, E-mail: lushemin@xjtu.edu.cn [Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi 710061 (China); Key Laboratory of Environment and Genes Related to Diseases, Xi’an Jiaotong University, Ministry of Education of China (China)

    2016-05-15

    Thioredoxin reductase 2 (TrxR2) is a selenium (Se) containing protein. Se deficiency is associated with an endemic osteoarthropathy characterized by impaired cartilage formation. It is unclear whether TrxR2 have roles in cartilage function. We examined the effects of TrxR2 on chondrogenic ATDC5 cells through shRNA-mediated gene silencing of TrxR2. We demonstrated TrxR2 deficiencies could enhance chondrogenic differentiation and apoptosis of ATDC5 cells. TrxR2 deficiencies increased accumulation of cartilage glycosaminoglycans (GAGs) and mineralization. TrxR2 deficiencies also stimulated expression of extracellular (ECM) gene including Collagen II and Aggrecan. The enhanced chondrogenic properties were further confirmed by activation of Akt signaling which are required for chondrogenesis. In addition, TrxR2 deficiencies promoted chondrocyte proliferation through acceleration of cell cycle progression by increase in both S and G2/M phase cell distribution accompanied with induction of parathyroid hormone-related protein (PTHrP). Moreover, TrxR2 deficiencies induced chondrocyte death via apoptosis and increased cell sensitivity to exogenous oxidative stress. Furthermore, TrxR2 deficiencies induced emission of mitochondrial reactive oxygen species (ROS) without alteration of mitochondrial membrane potential and intracellular ATP content. Finally, treatment of TrxR2 deficiency cells with N-acetylcysteine (NAC) inhibited mitochondrial ROS production and chondrocyte apoptosis. NAC also prevented chondrogenic differentiation of TrxR2 deficiency cells by suppression of ECM gene expression, GAGs accumulation and mineralization, as well as attenuation of Akt signaling. Thus, TrxR2-mediated mitochondrial integrity is indispensable for chondrogenic differentiation of ATDC5 cells. TrxR2 deficiency-induced impaired proliferation and death of chondrocytes may be the pathological mechanism of the osteoarthropathy due to Se deficiency. Notably, this study also uncover the roles of

  4. Superconductivity, structure and oxygen deficiency in the Ba2YCu2WOY system

    International Nuclear Information System (INIS)

    Bokhimi, M.; Portilla, M.; Perez, R.; Universidad Nacional Autonoma de Mexico, Mexico City

    1991-01-01

    It is shown that the Ba-2YCu x WO y system with O≤x≤2 is composed of 2 phases, the first with composition Ba 2 YWO 6 with a small copper-solution replacing yttrium, it has cubic ordered perovskite structure with the space group Fm3m, the solution of the copper gives rise to a lattice contraction. The second phase corresponds to CuO, or Cu 2 O depending on sample preparation At large copper concentrations the first phase appears as small precipitates embedded in the second one. Reducing the samples at 1150 o C in H 2 gives rise to a separation of the phases, segregating the copper in the form of liquid metal. The reduction eliminates from the first phase the dissolved copper, and produces also some oxygen deficiency in the sample, both effects give origin to a lattice distortion in the ordered perovskite structure. Although the samples are black after the reduction, they are not electrical conductors. (author). 8 refs., 8 figs

  5. Photoluminescence of Se-related oxygen deficient center in ion-implanted silica films

    International Nuclear Information System (INIS)

    Zatsepin, A.F.; Buntov, E.A.; Pustovarov, V.A.; Fitting, H.-J.

    2013-01-01

    The results of low-temperature time-resolved photoluminescence (PL) investigation of thin SiO 2 films implanted with Se + ions are presented. The films demonstrate an intensive PL band in the violet spectral region, which is attributed to the triplet luminescence of a new variant of selenium-related oxygen deficient center (ODC). The main peculiarity of the defect energy structure is the inefficient direct optical excitation. Comparison with spectral characteristics of isoelectronic Si-, Ge- and SnODCs show that the difference in electronic properties of the new center is related to ion size factor. It was established that the dominating triplet PL excitation under VUV light irradiation is related to the energy transfer from SiO 2 excitons. A possible model of Se-related ODC is considered. -- Highlights: • The low-temperature photoluminescence of thin SiO 2 films implanted with Se + ions was studied. • The 3.4 eV PL band was attributed to triplet luminescence of Se-related ODC. • The peculiarity of SeODC electronic properties is related to ion size factor. • The dominating VUV excitation of triplet PL is related to energy transfer from SiO 2 excitons. • A possible model of Se-related ODC is considered

  6. Cardiomyocyte hypertrophy induced by Endonuclease G deficiency requires reactive oxygen radicals accumulation and is inhibitable by the micropeptide humanin.

    Science.gov (United States)

    Blasco, Natividad; Cámara, Yolanda; Núñez, Estefanía; Beà, Aida; Barés, Gisel; Forné, Carles; Ruíz-Meana, Marisol; Girón, Cristina; Barba, Ignasi; García-Arumí, Elena; García-Dorado, David; Vázquez, Jesús; Martí, Ramon; Llovera, Marta; Sanchis, Daniel

    2018-06-01

    The endonuclease G gene (Endog), which codes for a mitochondrial nuclease, was identified as a determinant of cardiac hypertrophy. How ENDOG controls cardiomyocyte growth is still unknown. Thus, we aimed at finding the link between ENDOG activity and cardiomyocyte growth. Endog deficiency induced reactive oxygen species (ROS) accumulation and abnormal growth in neonatal rodent cardiomyocytes, altering the AKT-GSK3β and Class-II histone deacethylases (HDAC) signal transduction pathways. These effects were blocked by ROS scavengers. Lack of ENDOG reduced mitochondrial DNA (mtDNA) replication independently of ROS accumulation. Because mtDNA encodes several subunits of the mitochondrial electron transport chain, whose activity is an important source of cellular ROS, we investigated whether Endog deficiency compromised the expression and activity of the respiratory chain complexes but found no changes in these parameters nor in ATP content. MtDNA also codes for humanin, a micropeptide with possible metabolic functions. Nanomolar concentrations of synthetic humanin restored normal ROS levels and cell size in Endog-deficient cardiomyocytes. These results support the involvement of redox signaling in the control of cardiomyocyte growth by ENDOG and suggest a pathway relating mtDNA content to the regulation of cell growth probably involving humanin, which prevents reactive oxygen radicals accumulation and hypertrophy induced by Endog deficiency. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

  7. Fatty acid binding protein 4 deficiency protects against oxygen-induced retinopathy in mice.

    Directory of Open Access Journals (Sweden)

    Magali Saint-Geniez

    Full Text Available Retinopathy of prematurity (ROP is a leading cause of blindness in children worldwide due to increasing survival rates of premature infants. Initial suppression, followed by increased production of the retinal vascular endothelial growth factor-A (VEGF expression are key events that trigger the pathological neovascularization in ROP. Fatty acid binding protein 4 (FABP4 is an intracellular lipid chaperone that is induced by VEGF in a subset of endothelial cells. FABP4 exhibits a pro-angiogenic function in cultured endothelial cells and in airway microvasculature, but whether it plays a role in modulation of retinal angiogenesis is not known. We hypothesized that FABP4 deficiency could ameliorate pathological retinal vascularization and investigated this hypothesis using a well-characterized mouse model of oxygen-induced retinopathy (OIR. We found that FABP4 was not expressed in retinal vessels, but was present in resident macrophages/microglial cells and endothelial cells of the hyaloid vasculature in the immature retina. While FABP4 expression was not required for normal development of retinal vessels, FABP4 expression was upregulated and localized to neovascular tufts in OIR. FABP4-/- mice demonstrated a significant decrease in neovessel formation as well as a significant improvement in physiological revascularization of the avascular retinal tissues. These alterations in retinal vasculature were accompanied by reduced endothelial cell proliferation, but no effect on apoptosis or macrophage/microglia recruitment. FABP4-/- OIR samples demonstrated decreased expression of genes involved in angiogenesis, such as Placental Growth Factor, and angiopoietin 2. Collectively, our findings suggest FABP4 as a potential target of pathologic retinal angiogenesis in proliferative retinopathies.

  8. Survival curves of irradiated glutathione-deficient human fibroblasts: indication of a reduced enhancement of radiosensitivity by oxygen and misonidazole

    International Nuclear Information System (INIS)

    Midander, J.; Deschavanne, P.J.; Malaise, E.P.; Revesz, L.

    1982-01-01

    Fibroblasts derived from a patient with 5-oxoprolinuria are genetically deficient in glutathione synthetase. This deficiency causes a dramatic decrease in intracellular glutathione (GSH) level. The radiosensitivity of GSH deficient cells (GSH) was studied in vitro using colony forming ability as an endpoint. Cells with normal GSH level, obtained from the healthy brother of the patient, were used as controls. When irradiated in 95% air-5% CO 2 , GSH - cells are slightly but significantly more radiosensitive than GSH + controls (dose modifying factor (DMF) of 1.2). When irradiated in argon, the survival curve of GSH - cells indicates an oxygen enhancement ratio (OER) of 1.5 when compared to the curve obtained in oxic conditions. The OER of control cells in the same conditions is 2.9. In comparison to results obtained in air, 100% oxygen moderately increases the radiosensitivity of GSH + cells (DMF 1,23), while it has a very low effect on GSH - cells (DMF 1.06). These results suggest that intracellular GSH plays an essential protective role in hypoxia, its effect is reduced in air and practically disappears in 100% oxygen. When cells are incubated with 8 mM misonidazole 2 hours before irradiation, the drug has a much greater sensitizing effect on GSH + cells (DMF 2.33) than on GSH - cells (DMF 1.55). The results demonstrate that intracellular GSH level plays a major role in the response of hypoxic cells, irradiated either alone or in the presence of misonidazole

  9. Oxygen enhancement ratios for glutathione-deficient human fibroblasts determined from the frequency of radiation induced micronuclei

    International Nuclear Information System (INIS)

    Midander, J.

    1982-01-01

    The yield of micronuclei (MN) was determined to study the radiosensitizing effect of oxygen on three human fibroblast strains, characterized by genetically defined differences in their glutathione (GSH) level. Cells were irradiated in paired experiments with x-ray doses of 2.66 and 6.65 gy in their exponential growth phase in a monolayer under oxic and anoxic conditions. Results indicated a reduced oxygen effect for the GSH deficient cells, the reduction of o.e.r. being most pronounced in the case of GSHsup(-/-) cells, when it was close to unity. The o.e.r. value was intermediate for the GSHsup(+/-) in comparison with the two other cell strains. It is concluded that the data indicate a correlation between the cellular content of GSH and the oxygen enhancement of the formation of micronuclei after irradiation. (U.K.)

  10. Oxygen transport in waterlogged soils, Part I. Approaches to modelling soil and crop response to oxygen deficiency

    International Nuclear Information System (INIS)

    Obando Moncayo, F.H.

    2004-01-01

    This lecture outlines in a simple way the mathematics of various cases of diffusion which have been widely used in modelling soil aeration. Simplifications of the general equation of diffusion (Fick's law) giving two possible forms of the problem: planar or one-dimensional diffusion and radial diffusion are given. Furthermore, the solution of diffusion equation is obtained by the analogy to the problem of electrical flow (Ohm's law). Taking into consideration the soil respiration process, the continuity equation which accounts for the law of conservation of mass is solved. The purpose of this paper has been to review the interrelation soil structure-air movement in waterlogged clay soils, and its consequences on plant growth and crop production. Thus, the mathematics of diffusion is presented, and then its application to specific cases of soil aeration such as diffusion in the soil profile, soil aggregates and roots is given. The following assumptions are taken into consideration. Gas flow in soils is basically diffusion-dependent. Gas-phase diffusion is the major mechanism for vertical or longitudinal transport (long distance transport); this means, with depth Z in the soil profile (macro diffusion). For horizontal transport (short distance transport or micro diffusion) which is assumed to be in X direction; in this case, the geometry of aggregates and the liquid phase are the major components of resistance for diffusion. Soil aggregates and roots are considered to be spherical and cylindrical in shape respectively. Soil oxygen consumption, Sr, is taken to be independent of the oxygen concentration and considered to proceed at the same rate until oxygen supply drops to critical levels. Thus, aeration problems are assumed to begin when at any time, in the root zone, the oxygen diffusion rate, ODR, becomes less than 30x10 -8 g.cm -2 .sec -1 , or the value of redox potential Eh is less than +525 mv

  11. Both AtrbohD and AtrbohF are essential for mediating responses to oxygen deficiency in Arabidopsis.

    Science.gov (United States)

    Liu, Bo; Sun, Lirong; Ma, Liya; Hao, Fu-Shun

    2017-06-01

    Both AtrbohD and AtrbohF promote the increases in activities of ADH, PDC, LDH, and Ca 2+ levels, and induce the expression of multiple hypoxia response genes, thus improving Arabidopsis adaptation to oxygen deficiency. NADPH oxidase AtrbohD and AtrbohF cooperatively play key roles in regulation of growth and stress signaling in Arabidopsis. However, reports on AtrbohD and AtrbohF functioning together in hypoxia signaling are scarce, and the underlying mechanisms remain elusive. Here, we show that the double null mutant atrbohD/F is more sensitive to oxygen deprivation compared with wild type (WT) and the single mutant atrbohD and atrbohF. Under oxygen deficiency, enhancements of the transcripts of alcohol dehydrogenase 1 (ADH1) and pyruvate decarboxylase 1 (PDC1) and the activities of ADH, PDC and lactate dehydrogenase in WT are clearly reduced in the single mutants, and more strongly reduced in the double mutant. Moreover, increases in the production of ATP, H 2 O 2 and Ca 2+ in WT are significantly arrested in atrbohD, atrbohF, and especially in atrbohD/F. Hypoxia-promoted rise in the expression of some hypoxic responsive genes is also inhibited in atrbohD/F relative to WT, atrbohD and atrbohF. These genes include ethylene response factor 73, lactate dehydrogenase, MYB transcription factor 2, sucrose synthase 1 (SUS1), SUS4, heat stress transcription factor A2 and heat-shock protein 18.2. These results suggest that both AtrbohD and AtrbohF are essential for mediating hypoxia signaling. H 2 O 2 derived from AtrbohD and AtrbohF triggers the Ca 2+ increase and induces the expression of multiple hypoxia response genes, thus improving Arabidopsis tolerance to low-oxygen stress. These findings provide new insights into the mechanisms of AtrbohF in regulating the responses to oxygen deprivation in Arabidopsis.

  12. Strontium influence on the oxygen electrocatalysis of La2−xSrxNiO4±δ (0.0 ≤ xSr ≤ 1.0) thin films

    KAUST Repository

    Lee, Dongkyu; Lee, Yueh-Lin; Grimaud, Alexis; Hong, Wesley T.; Biegalski, Michael D.; Morgan, Dane; Shao-Horn, Yang

    2014-01-01

    Substitution of lanthanum by strontium (Sr) in the A-site of cobalt-containing perovskites can greatly promote oxygen surface exchange kinetics at elevated temperatures. Little is known about the effect of A-site substitution on the oxygen electrocatalysis of Ruddlesden-Popper (RP) oxides. In this study, we report, for the first time, the growth and oxygen surface exchange kinetics of La2-xSrxNiO 4±δ (LSNO, 0.0 ≤ xSr ≤ 1.0) thin films grown on (001)cubic-Y2O3-stabilized ZrO 2 (YSZ) by pulsed laser deposition. High-resolution X-ray diffraction analysis revealed that the LSNO film orientation was changed gradually from the (100)tetra. (in-plane) to the (001)tetra. (out-of-plane) orientation in the RP structure with increasing Sr from La2NiO 4+δ (xSr = 0) to LaSrNiO4±δ (xSr = 1.0). Such a change in the LSNO film orientation was accompanied by reduction in the oxygen surface exchange kinetics by two orders of magnitude as shown from electrochemical impedance spectroscopy results. Density functional theory (DFT) calculations showed that Sr substitution could stabilize the (001)tetra. surface relative to the (100) tetra. surface and both Sr substitution and increasing (001) tetra. surface could greatly weaken adsorption of molecular oxygen in the La-La bridge sites in the RP structure, which can reduce oxygen surface exchange kinetics. This journal is © the Partner Organisations 2014.

  13. Enhanced metabolic versatility of planktonic sulfur-oxidizing γ-proteobacteria in an oxygen-deficient coastal ecosystem

    Directory of Open Access Journals (Sweden)

    Alejandro A. Murillo

    2014-07-01

    Full Text Available Sulfur-oxidizing Gamma-proteobacteria are abundant in marine oxygen-deficient waters, and appear to play a key role in a previously unrecognized cryptic sulfur cycle. Metagenomic analyses of members of the uncultured SUP05 lineage in the Canadian seasonally anoxic fjord Saanich Inlet (SI, hydrothermal plumes in the Guaymas Basin (GB and single cell genomics analysis of two ARCTIC96BD-19 representatives from the South Atlantic Sub-Tropical Gyre (SASG have shown them to be metabolically versatile. However, SI and GB SUP05 bacteria seem to be obligate chemolithoautotrophs, whereas ARCTIC96BD-19 has the genetic potential for aerobic respiration. Here, we present results of a metagenomic analysis of sulfur-oxidizing Gamma-proteobacteria (GSO, closely related to the SUP05/ARCTIC96BD-19 clade, from a coastal ecosystem in the eastern South Pacific (ESP. This ecosystem experiences seasonal anoxia and accumulation of nitrite and ammonium at depth, with a corresponding increase in the abundance of GSO representatives. The ESP-GSOs appear to have a significantly different gene complement than those from Saanich Inlet, Guaymas Basin and SASG. Genomic analyses of de novo assembled contigs indicate the presence of a complete aerobic respiratory complex based on the cytochrome bc1 oxidase. Furthermore, they appear to encode a complete TCA cycle and several transporters for dissolved organic carbon species, suggesting a mixotrophic lifestyle. Thus, the success of sulfur-oxidizing Gamma-proteobacteria in oxygen-deficient marine ecosystems appears due not only to their previously recognized anaerobic metabolic versatility, but also to their capacity to function under aerobic conditions using different carbon sources. Finally, members of ESP-GSO cluster also have the genetic potential for reducing nitrate to ammonium based on the nirBD genes, and may therefore facilitate a tighter coupling of the nitrogen and sulfur cycles in oxygen-deficient waters.

  14. BMI-1 Mediates Estrogen-Deficiency-Induced Bone Loss by Inhibiting Reactive Oxygen Species Accumulation and T Cell Activation.

    Science.gov (United States)

    Li, Jinbo; Wang, Qian; Yang, Renlei; Zhang, Jiaqi; Li, Xing; Zhou, Xichao; Miao, Dengshun

    2017-05-01

    Previous studies have shown that estrogen regulates bone homeostasis through regulatory effects on oxidative stress. However, it is unclear how estrogen deficiency triggers reactive oxygen species (ROS) accumulation. Recent studies provide evidence that the B lymphoma Mo-MLV insertion region 1 (BMI-1) plays a critical role in protection against oxidative stress and that this gene is directly regulated by estrogen via estrogen receptor (ER) at the transcriptional level. In this study, ovariectomized mice were given drinking water with/without antioxidant N-acetyl-cysteine (NAC, 1 mg/mL) supplementation, and compared with each other and with sham mice. Results showed that ovariectomy resulted in bone loss with increased osteoclast surface, increased ROS levels, T cell activation, and increased TNF and RANKL levels in serum and in CD4 T cells; NAC supplementation largely prevented these alterations. BMI-1 expression levels were dramatically downregulated in CD4 T cells from ovariectomized mice. We supplemented drinking water to BMI-1-deficient mice with/without NAC and compared them with each other and with wild-type (WT) mice. We found that BMI-1 deficiency mimicked alterations observed in ovariectomy whereas NAC supplementation reversed all alterations induced by BMI-1 deficiency. Because T cells are critical in mediating ovariectomy-induced bone loss, we further assessed whether BMI-1 overexpression in lymphocytes can protect against estrogen deficiency-induced osteoclastogenesis and bone loss by inhibiting oxidative stress, T cell activation, and RANKL production. When WT and Eμ-BMI-1 transgenic mice with BMI-1 specifically overexpressed in lymphocytes were ovariectomized and compared with each other and with WT sham mice, we found that BMI-1 overexpression in lymphocytes clearly reversed all alterations induced by ovariectomy. Results from this study indicate that estrogen deficiency downregulates BMI-1 and subsequently increases ROS, T cell activation, and

  15. Some aspects of the oxygen-deficient conditions and denitrification in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.

    Utilizing a fairly large amount of recently collected data, some outstanding questions concerning the Arabian Sea denitrification problem are addressed. The true level of dissolved oxygen, determined colorimetrically, are about an order of magnitude...

  16. The spatial distribution of temperature and oxygen deficiency in spark-plasma sintered superconducting Bi-based materials

    International Nuclear Information System (INIS)

    Govea-Alcaide, E.; Pérez-Fernández, J.E.; Machado, I.F.; Jardim, R.F.

    2014-01-01

    Pre-reacted powders of (Bi–Pb) 2 Sr 2 Ca 2 Cu 3 O 10+δ (Bi-2223) were consolidated by using the spark plasma sintering (SPS) technique under vacuum and at different consolidate temperatures T D . X-ray diffraction patterns revealed that the dominant phase in all SPS samples is the Bi-2223 phase, but traces of the Bi 2 Sr 2 CaCu 2 O 10+x (Bi-2212) phase were identified. We have found that the transport properties of SPS samples depend on their oxygen content because the SPS process is performed under vacuum. Simulations by using the finite element method (FEM) were performed for determining the actual temperature in which powders are consolidated. From these results we have inferred that SPS samples are oxygen deficient and such a deficiency is more marked near the grain boundaries, suggesting the occurrence of grains with core–shell morphology. We also argued that the width of the shell depends on the consolidation temperature, a feature corroborated by the FEM simulations

  17. Crystallization of carbonate hydroxyapatite in the presence of strontium ranelate

    Science.gov (United States)

    Izmailov, R. R.; Golovanova, O. A.

    2015-11-01

    The influence of strontium ranelate on the crystallization of carbonate hydroxyapatite from a prototype of synovial fluid of humans has been investigated. The synthesis products are studied by IR Fourier spectroscopy, X-ray diffraction, and differential thermal analysis. The amount of strontium in the samples is determined by atomic emission analysis. The sizes of crystallites in the synthesized phases are calculated from the Selyakov-Scherrer formula; the lattice parameters are also determined. The phases obtained are found to be species of calcium-deficient strontium-containing carbonate hydroxyapatite of mixed A and B types. Schemes of chemical reactions occurring during heat treatment are proposed.

  18. Thermal expansion behaviour in the oxygen deficient perovskites Sr2BSbO5.5 (B=Ca, Sr, Ba). Competing effects of water and oxygen ordering

    International Nuclear Information System (INIS)

    Zhou Qingdi; Kennedy, Brendan J.; Avdeev, Maxim

    2011-01-01

    Neutron diffractions studies reveal the presence of oxygen disorder in the oxygen deficient perovskites Sr 2 BSbO 5.5 (B=Ca, Sr, Ba). Synchrotron X-ray studies demonstrate that these oxides have a double perovskite-type structure with the cell size increasing as the size of the B cation increases from 8.2114(2) A for B=Ca to 8.4408(1) A for B=Ba. It is postulated that a combination of local clustering of the anions and vacancies together with water-water and water-host hydrogen bonds plays a role in defining the volume of the encapsulated water clusters and that changes in the local structure upon heating result in anomalous thermal expansion observed in variable temperature diffraction measurements. - Graphical abstract: The oxides Sr 2 BSbO 5.5 (B=Ca, Sr, Ba) have unusual anion disorder. There is a lag in the contraction in the cell size of Sr 2 CaSbO 5.5 nH 2 O established from X-ray diffraction measurements following the loss of water suggesting changes on the local structure are important. Highlights: → The average structures of the defect perovskites Sr 2 MSbO 5.5 established. → Anion and cation disorder quantified by neutron and synchrotron X-ray diffraction. → Anomalous thermal expansion due to local clustering of anions and vacancies observed.

  19. μSR in oxygen deficient YBa2Cu3Ox (6.5≤x≤7.0)

    International Nuclear Information System (INIS)

    Puempin, B.; Keller, H.; Kuendig, W.; Savic, I.M.; Schneider, J.W.; Simmler, H.; Zimmermann, P.; Kaldis, E.; Rusiecki, S.; Rossel, C.

    1991-01-01

    A systematic μSR study of the local magnetic field distribution in a series of oxygen deficient YBa 2 Cu 3 O x samples with 6.5≤x≤7.0 is reported. Special attention was given to perform the experiments under the same conditions, so that the oxygen content of the measured samples was the only parameter varied. The behavior of the depolarization rate σ as a function of the oxygen content x was found to have strong similarities with the behavior of the critical temperature Tc as a function of x. In particular, two step-like increases of σ were observed above x=6.7 and 6.9. The temperature dependence of the normalized depolarization rate σ(T)/σ(0) is well described by the two-fluid model for x≥6.781(1) and clearly deviates from this behavior for x≤6.704(1). Our results are compared to those obtained by other groups. (orig.)

  20. Ordered oxygen deficient '112' perovskites, LnBaCo2 : complex ...

    Indian Academy of Sciences (India)

    Administrator

    are labeled on the graph. .... in agreement with Kanamori Goodenough rules. In sum- mary, these results ... exhibit very rich phase diagrams as illustrated in figure 9. The latter .... which make that the control of oxygen content in these phases is ...

  1. Study on the Key Technology of High Purity Strontium Titanate Powder Synthesized from Oxalic Acid Co-sediment Precipitation

    Science.gov (United States)

    Bi, Xiaoguo; Dong, Yingnan; Li, Yingjie; Niu, Wei; Tang, Jian; Ding, Shuang; Li, Meiyang

    2017-09-01

    Oxalate coprecipitation is applied in this paper, high purity titanium tetrachloride, and after the purification of strontium chloride, match with a certain concentration of solution, oxalate and strontium chloride and titanium tetrachloride in 1.005:1.000 make strontium titanium mixture ratio, slowly under 60°C to join in oxalic acid solution, aging around 4 h, get oxygen titanium strontium oxalate (SrTiO(C2O4)2 • 4H2 ) precipitation, after washing, drying and other process made oxygen titanium strontium oxalate powder.

  2. Enhanced thermoelectric property of oxygen deficient nickel doped SnO2 for high temperature application

    Science.gov (United States)

    Paulson, Anju; Sabeer, N. A. Muhammad; Pradyumnan, P. P.

    2018-04-01

    Motivated by the detailed investigation on the thermoelectric performance of oxide materials our work concentrated on the influence of acceptor dopants and defect density in the lattice plane for the enhancement of thermoelectric power. The series of Sn1‑x Nix O2 (0.01 ≤ x ≤ 0.05) compositions were prepared by solid state reaction mechanism and found that 3 atomic percentage Ni doped SnO2 can be considered as a good candidate due to its promising electrical and transport properties. Defect lattices were introduced in the sample and the deviation from oxygen stochiometry was ensured using photoluminescence measurement. High power factor was obtained for the 3 atomic percentage nickel doped SnO2 due to the effective number of charge carrier concentration and the depletion of oxygen rich layers. Defect centered and acceptor doped SnO2 lattice opens a new door for energy harvesting at higher temperatures.

  3. Upper-critical fields of YBa2Cu3O7-δ epitaxial thin films with variable oxygen deficiency δ

    International Nuclear Information System (INIS)

    Jones, E.C.; Christen, D.K.; Thompson, J.R.; Ossandon, J.G.; Feenstra, R.; Phillips, J.M.; Siegal, M.P.

    1994-01-01

    Fluctuation analysis in the limit of high magnetic fields was performed on three epitaxial thin films of YBa 2 Cu 3 O 7-δ for various oxygen deficiencies δ c2 (T) slope of -1.7 T/K for H parallel c, consistent with previous observations of transport and magnetic properties. Moreover, the 3D scaling showed better convergence than the 2D scaling, which gave relatively low values of H c2 . In contrast, the transitions were not adequately described by either scaling for T c off the 90-K plateau; it is speculated that this is due to an extrinsic broadening of the transitions, possibly due to the lack of a complete percolation path of the ortho-I phase (δ=0)

  4. Magnetic studies of current conduction and flux pinning in high-Tc cuprates: Virgin, irradiated, and oxygen deficient materials

    International Nuclear Information System (INIS)

    Thompson, J.R.; Civale, L.; Marwick, A.D.; Holtzberg, F.

    1992-09-01

    To increase the current density and pinning of magnetic flux in high temperature superconductors, defects with point-like and line-like geometries were created in controlled numbers using ion irradiation methods. Single crystals of Y 1 Ba 2 Cu 3 O 7 and Bi 2 Sr 2 Ca 1 Cu 2 0 8 superconductors were studied using dc magnetic methods. These studies showed greatly increased irreversibility in the vortex state magnetization and enhanced intragrain current density J c following irradiation. Linear defects, created by irradiation with energetic heavy ions, are particularly effective in pinning vortices at higher temperatures and magnetic fields. Further investigations of ''flux creep'' (the time dependence of magnetization) are well described by recent vortex glass and collective pinning theories. Complementary investigations have delineated the role of oxygen deficiency δ on pinning in aligned Y 1 Ba 2 Cu 3 O 7-δ materials

  5. A close correlation between induced ferromagnetism and oxygen deficiency in Fe doped In2O3

    International Nuclear Information System (INIS)

    Singhal, R.K.; Samariya, A.; Kumar, Sudhish; Sharma, S.C.; Xing, Y.T.; Deshpande, U.P.; Shripathi, T.; Saitovitch, E.

    2010-01-01

    We report on the reversible manipulation of room temperature ferromagnetism in Fe (5%) doped In 2 O 3 polycrystalline magnetic semiconductor. The X-ray diffraction and photoemission measurements confirm that the Fe ions are well incorporated into the lattice, substituting the In 3+ ions. The magnetization measurements show that the host In 2 O 3 has a diamagnetic ground state, while it shows weak ferromagnetism at 300 K upon Fe doping. The as-prepared sample was then sequentially annealed in hydrogen, air, vacuum and finally in air. The ferromagnetic signal shoots up by hydrogenation as well as vacuum annealing and bounces back upon re-annealing the samples in air. The sequence of ferromagnetism shows a close inter-relationship with the behavior of oxygen vacancies (V o ). The Fe ions tend to a transform from 3+ to 2+ state during the giant ferromagnetic induction, as revealed by photoemission spectroscopy. A careful characterization of the structure, purity, magnetic, and transport properties confirms that the ferromagnetism is due to neither impurities nor clusters but directly related to the oxygen vacancies. The ferromagnetism can be reversibly controlled by these vacancies while a parallel variation of carrier concentration, as revealed by resistance measurements, appears to be a side effect of the oxygen vacancy variation.

  6. Rubidium-strontium method

    International Nuclear Information System (INIS)

    Dubansky, A.

    1980-01-01

    The rubidium-strontium geological dating method is based on the determination of the Rb and Sr isotope ratio in rocks, mainly using mass spectrometry. The method is only practical for silicate minerals and rocks, potassium feldspars and slates. Also described is the rubidium-strontium isochrone method. This, however, requires a significant amount of experimental data and an analysis of large quantities of samples, often of the order of tons. The results are tabulated of rubidium-strontium dating of geological formations in the Czech Socialist Republic. (M.S.)

  7. Magnetization and flux pinning in high-Tc cuprates: Irradiated and oxygen deficient materials

    International Nuclear Information System (INIS)

    Thompson, J.R.; Civale, L.; Marwick, A.D.; Holtzberg, F.

    1992-11-01

    This work surveys recent studies of the intragrain current density J and vortex pinning in high Tc superconductors. Materials include Y 1 Ba 2 Cu 3 O 7-δ and Bi 2 Sr 2 Ca 1 Cu 2 O 8 single crystals and aligned polycrystals. To probe the flux pinning, we modified the strength, number, and morphology of defects. Varying the oxygen content (7-δ) in YBa 2 Cu 3 O 7-δ or irradiating the materials with ions, having either light or heavy masses, gives systematic changes in the character of the all-important defects

  8. p53-competent cells and p53-deficient cells display different susceptibility to oxygen functionalized graphene cytotoxicity and genotoxicity.

    Science.gov (United States)

    Petibone, Dayton M; Mustafa, Thikra; Bourdo, Shawn E; Lafont, Andersen; Ding, Wei; Karmakar, Alokita; Nima, Zeid A; Watanabe, Fumiya; Casciano, Daniel; Morris, Suzanne M; Dobrovolsky, Vasily N; Biris, Alexandru S

    2017-11-01

    Due to the distinctive physical, electrical, and chemical properties of graphene nanomaterials, numerous efforts pursuing graphene-based biomedical and industrial applications are underway. Oxidation of pristine graphene surfaces mitigates its otherwise hydrophobic characteristic thereby improving its biocompatibility and functionality. Yet, the potential widespread use of oxidized graphene derivatives raises concern about adverse impacts on human health. The p53 tumor suppressor protein maintains cellular and genetic stability after toxic exposures. Here, we show that p53 functional status correlates with oxygen functionalized graphene (f-G) cytotoxicity and genotoxicity in vitro. The f-G exposed p53-competent cells, but not p53-deficient cells, initiated G 0 /G 1 phase cell cycle arrest, suppressed reactive oxygen species, and entered apoptosis. There was p53-dependent f-G genotoxicity evident as increased structural chromosome damage, but not increased gene mutation or chromatin loss. In conclusion, the cytotoxic and genotoxic potential for f-G in exposed cells was dependent on the p53 functional status. These findings have broad implications for the safe and effective implementation of oxidized graphene derivatives into biomedical and industrial applications. Published 2017. This article has been contributed to by US Government employees and their work is in the public domain in the USA. Published 2017. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

  9. Stoichiometric and Oxygen-Deficient VO2 as Versatile Hole Injection Electrode for Organic Semiconductors.

    Science.gov (United States)

    Fu, Keke; Wang, Rongbin; Katase, Takayoshi; Ohta, Hiromichi; Koch, Norbert; Duhm, Steffen

    2018-03-28

    Using photoemission spectroscopy, we show that the surface electronic structure of VO 2 is determined by the temperature-dependent metal-insulator phase transition and the density of oxygen vacancies, which depends on the temperature and ultrahigh vacuum (UHV) conditions. The atomically clean and stoichiometric VO 2 surface is insulating at room temperature and features an ultrahigh work function of up to 6.7 eV. Heating in UHV just above the phase transition temperature induces the expected metallic phase, which goes in hand with the formation of oxygen defects (up to 6% in this study), but a high work function >6 eV is maintained. To demonstrate the suitability of VO 2 as hole injection contact for organic semiconductors, we investigated the energy-level alignment with the prototypical organic hole transport material N, N'-di(1-naphthyl)- N, N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (NPB). Evidence for strong Fermi-level pinning and the associated energy-level bending in NPB is found, rendering an Ohmic contact for holes.

  10. Conditions for oxygen-deficient combustion during accidents with severe core concrete thermal attack

    International Nuclear Information System (INIS)

    Luangdilok, W.; Elicson, G.T.; Berger, W.E. Jr.

    1993-01-01

    This paper addresses the interactions between MCCI (molten core-concrete interactions)-induced offgas releases, mostly the combustible gases, natural circulation between the cavity and the lower containment based on recent research developments in the area of mixed convection flow (Epstein, et al., 1989; Epstein, 1988; Epstein, 1992) between compartments, and their effects on combustion in PWR containments during prolonged severe accidents. Specifically, large dry PWR containments undergoing severe core-concrete attack during station blackouts where the containment atmosphere is expected to be inerted are objects of this analysis. The purpose of this paper, given the conditions that oxygen can be brought to the cavity, is to demonstrate that consumption of most oxygen present in the containment can be achieved in a reasonable time scale assuming that combustion is not subject to flammability limits due to the high cavity temperatures. The conditions for cavity combustion depend on several factors including good gas flowpaths between the cavity and other containment regions, and combustion processes within the cavity with the hot debris acting as the ignition source

  11. Photostriction of strontium ruthenate

    KAUST Repository

    Wei, Tzu-Chiao; Wang, Hsin-Ping; Liu, Heng-Jui; Tsai, Dung-Sheng; Ke, Jr-Jian; Wu, Chung-Lun; Yin, Yu-Peng; Zhan, Qian; Lin, Gong-Ru; Chu, Ying-Hao; He, Jr-Hau

    2017-01-01

    Transition metal oxides with a perovskite crystal structure exhibit a variety of physical properties associated with the lattice. Among these materials, strontium ruthenate (SrRuO3) displays unusually strong coupling of charge, spin and lattice

  12. Selective oxidation of n-butane to maleic anhydride under oxygen-deficient conditions over V-P-O mixed oxides

    NARCIS (Netherlands)

    Bosch, H.; Bruggink, A.A.; Ross, J.R.H.

    1987-01-01

    The selective oxidation of n-butane to maleic anhydride over V-P-O mixed oxides was studied under oxygen deficient conditions. The mixed oxides were prepared with P/V atomic ratios ranging from 0.7 to 1.0. Catalysts with P/V <1.0 did not show any selectivity to maleic anhydride formation, regardless

  13. Electrical conductivity in oxygen-deficient phases of tantalum pentoxide from first-principles calculations

    International Nuclear Information System (INIS)

    Bondi, Robert J.; Desjarlais, Michael P.; Thompson, Aidan P.; Brennecka, Geoff L.; Marinella, Matthew J.

    2013-01-01

    We apply first-principles density-functional theory (DFT) calculations, ab-initio molecular dynamics, and the Kubo-Greenwood formula to predict electrical conductivity in Ta 2 O x (0 ≤ x ≤ 5) as a function of composition, phase, and temperature, where additional focus is given to various oxidation states of the O monovacancy (V O n ; n = 0,1+,2+). In the crystalline phase, our DFT calculations suggest that V O 0 prefers equatorial O sites, while V O 1+ and V O 2+ are energetically preferred in the O cap sites of TaO 7 polyhedra. Our calculations of DC conductivity at 300 K agree well with experimental measurements taken on Ta 2 O x thin films (0.18 ≤ x ≤ 4.72) and bulk Ta 2 O 5 powder-sintered pellets, although simulation accuracy can be improved for the most insulating, stoichiometric compositions. Our conductivity calculations and further interrogation of the O-deficient Ta 2 O 5 electronic structure provide further theoretical basis to substantiate V O 0 as a donor dopant in Ta 2 O 5 . Furthermore, this dopant-like behavior is specific to the neutral case and not observed in either the 1+ or 2+ oxidation states, which suggests that reduction and oxidation reactions may effectively act as donor activation and deactivation mechanisms, respectively, for V O n in Ta 2 O 5

  14. Electrical conductivity in oxygen-deficient phases of tantalum pentoxide from first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Bondi, Robert J., E-mail: rjbondi@sandia.gov; Desjarlais, Michael P.; Thompson, Aidan P.; Brennecka, Geoff L.; Marinella, Matthew J. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

    2013-11-28

    We apply first-principles density-functional theory (DFT) calculations, ab-initio molecular dynamics, and the Kubo-Greenwood formula to predict electrical conductivity in Ta{sub 2}O{sub x} (0 ≤ x ≤ 5) as a function of composition, phase, and temperature, where additional focus is given to various oxidation states of the O monovacancy (V{sub O}{sup n}; n = 0,1+,2+). In the crystalline phase, our DFT calculations suggest that V{sub O}{sup 0} prefers equatorial O sites, while V{sub O}{sup 1+} and V{sub O}{sup 2+} are energetically preferred in the O cap sites of TaO{sub 7} polyhedra. Our calculations of DC conductivity at 300 K agree well with experimental measurements taken on Ta{sub 2}O{sub x} thin films (0.18 ≤ x ≤ 4.72) and bulk Ta{sub 2}O{sub 5} powder-sintered pellets, although simulation accuracy can be improved for the most insulating, stoichiometric compositions. Our conductivity calculations and further interrogation of the O-deficient Ta{sub 2}O{sub 5} electronic structure provide further theoretical basis to substantiate V{sub O}{sup 0} as a donor dopant in Ta{sub 2}O{sub 5}. Furthermore, this dopant-like behavior is specific to the neutral case and not observed in either the 1+ or 2+ oxidation states, which suggests that reduction and oxidation reactions may effectively act as donor activation and deactivation mechanisms, respectively, for V{sub O}{sup n} in Ta{sub 2}O{sub 5}.

  15. Infrared characterization of strontium titanate thin films

    International Nuclear Information System (INIS)

    Almeida, B.G.; Pietka, A.; Mendes, J.A.

    2004-01-01

    Strontium titanate thin films have been prepared at different oxygen pressures with various post-deposition annealing treatments. The films were deposited by pulsed laser ablation at room temperature on Si(0 0 1) substrates with a silica buffer layer. Infrared reflectance measurements were performed in order to determine relevant film parameters such as layer thicknesses and chemical composition. The infrared reflectance spectra were fitted by using adequate dielectric function forms for each layer. The fitting procedure provided the extraction of the dielectric functions of the strontium titanate film, the silica layer and the substrate. The as-deposited films are found to be amorphous, and their infrared spectra present peaks corresponding to modes with high damping constants. As the annealing time and temperature increases the strontium titanate layer becomes more ordered so that it can be described by its SrTiO 3 bulk mode parameters. Also, the silica layer grows along with the ordering of the strontium titanate film, due to oxidation during annealing

  16. Strontium-82/rubidium-82 generator

    International Nuclear Information System (INIS)

    Gennaro, G.P.; Haney, P.S.

    1986-01-01

    Hydroxylapatite, a compound having the formula: M 10 (PO 4 ) 6 (OH) 2 wherein M is calcium, strontium, barium, lead, iron, sodium, potassium, zinc, cadmium, magnesium, aluminium or a rare earth metal, is provided as a support medium for strontium-82 in a strontium-82/rubidium-82 parent-daughter radionuclide generator

  17. Strontium Localization in Bone Tissue Studied by X-Ray Absorption Spectroscopy

    DEFF Research Database (Denmark)

    Frankær, Christian Grundahl; Raffalt, Anders Christer; Ståhl, Kenny

    2014-01-01

    Strontium has recently been introduced as a pharmacological agent for the treatment and prevention of osteoporosis. We determined the localization of strontium incorporated into bone matrix from dogs treated with Sr malonate by X-ray absorption spectroscopy. A new approach for analyzing the X...... highly ordered sites, and at least 30 % is located at less ordered sites where only the first solvation shell is resolved, suggesting that strontium is sur- rounded by only oxygen atoms similar to Sr2? in solution. Strontium was furthermore shown to be absorbed in collagen in which it obtains a higher...

  18. Transport and magnetoresistance effect in an oxygen-deficient SrTiO3/La0.67Sr0.33MnO3 heterojunction

    International Nuclear Information System (INIS)

    Wang Jing; Chen Chang-Le; Yang Shi-Hai; Luo Bing-Cheng; Duan Meng-Meng; Jin Ke-Xin

    2013-01-01

    An oxygen-deficient SrTiO 3 /La 0.67 Sr 0.33 MnO 3 heterojunction is fabricated on an SrTiO 3 (001) substrate by a pulsed laser deposition method. The electrical characteristics of the heterojunction are studied systematically in a temperature range from 80 K to 300 K. The transport mechanism follows I ∞ exp(eV/nkT) under small forward bias, while it becomes space charge limited and follows I ∞ V m(T) with 1.49 < m < 1.99 under high bias. Such a heterojunction also exhibits magnetoresistance (MR) effect. The absolute value of negative MR monotonically increases with temperature decreasing and reaches 26.7% at 80 K under H = 0.7 T. Various factors, such as strain and oxygen deficiency play dominant roles in the characteristics. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  19. Strontium isotope stratigraphy of the Pelotas Basin

    Energy Technology Data Exchange (ETDEWEB)

    Zerfass, Geise de Santana dos Anjos, E-mail: geise.zerfass@petrobras.com.br [Petroleo Brasileiro S.A. (PETROBRAS/CENPES/PDGEO/BPA), Rio de Janeiro, RJ (Brazil). Centro de Pesquisas e Desenvolvimento Leopoldo Americo Miguez de Mello; Chemale Junior, Farid, E-mail: fchemale@unb.br [Universidade de Brasilia (UnB), DF (Brazil). Instituto de Geociencias; Moura, Candido Augusto Veloso, E-mail: candido@ufpa.br [Universidade Federal do Para (UFPA), Belem, PA (Brazil). Centro de Geociencias. Dept. de Geoquimica e Petrologia; Costa, Karen Badaraco, E-mail: karen.costa@usp.br [Instituto Oceanografico, Sao Paulo, SP (Brazil); Kawashita, Koji, E-mail: koji@usp.br [Unversidade de Sao Paulo (USP), SP (Brazil). Centro de Pesquisas Geocronologicas

    2014-07-01

    Strontium isotope data were obtained from foraminifera shells of the Pelotas Basin Tertiary deposits to facilitate the refinement of the chronostratigraphic framework of this section. This represents the first approach to the acquisition of numerical ages for these strata. Strontium isotope stratigraphy allowed the identification of eight depositional hiatuses in the Eocene-Pliocene section, here classified as disconformities and a condensed section. The reconnaissance of depositional gaps based on confident age assignments represents an important advance considering the remarkably low chronostratigraphic resolution in the Cenozoic section of the Pelotas Basin. The recognition of hiatuses that match hiatuses is based on biostratigraphic data, as well as on global events. Furthermore, a substantial increase in the sedimentation rate of the upper Miocene section was identified. Paleotemperature and productivity trends were identified based on oxygen and carbon isotope data from the Oligocene-Miocene section, which are coherent with worldwide events, indicating the environmental conditions during sedimentation. (author)

  20. Thermoluminescence of strontium tetraborate

    International Nuclear Information System (INIS)

    Santiago, M.; Caselli, E.; Lester, M.

    1999-01-01

    The thermoluminescent properties of crystalline strontium tetraborate are reported. Without activators it has an efficiency comparable to that of TLD-700 powder. Its fading after 40 days amount to less than 2%. The isometric plot shows that most of the emitted light is concentrated at wavelengths ranging from 350 to 450 nm, which accounts partially for the high efficiency. (author)

  1. The origin and crust/mantle mass balance of Central Andean ignimbrite magmatism constrained by oxygen and strontium isotopes and erupted volumes

    Science.gov (United States)

    Freymuth, Heye; Brandmeier, Melanie; Wörner, Gerhard

    2015-06-01

    Volcanism during the Neogene in the Central Volcanic Zone (CVZ) of the Andes produced (1) stratovolcanoes, (2) rhyodacitic to rhyolitic ignimbrites which reach volumes of generally less than 300 km3 and (3) large-volume monotonous dacitic ignimbrites of up to several thousand cubic kilometres. We present models for the origin of these magma types using O and Sr isotopes to constrain crust/mantle proportions for the large-volume ignimbrites and explore the relationship to the evolution of the Andean crust. Oxygen isotope ratios were measured on phenocrysts in order to avoid the effects of secondary alteration. Our results show a complete overlap in the Sr-O isotope compositions of lavas from stratovolcanoes and low-volume rhyolitic ignimbrites as well as older (>9 Ma) large-volume dacitic ignimbrites. This suggests that the mass balance of crustal and mantle components are largely similar. By contrast, younger (estimated the volume of these ignimbrite deposits throughout the Central Andes during the Neogene and examined the spatiotemporal pattern of so-called ignimbrite flare-ups. We observe a N-S migration of maximum ages of the onset of large-volume "ignimbrite pulses" through time: Major pulses occurred at 19-24 Ma (e.g. Oxaya, Nazca Group), 13-14 Ma (e.g. Huaylillas and Altos de Pica ignimbrites) and 70 km3 Ma-1 km-1 (assuming plutonic/volcanic ratios of 1:5) which are additional to, but within the order of, the arc background magmatic flux. Comparing our results to average shortening rates observed in the Andes, we observe a "lag-time" with large-volume eruptions occurring after accelerated shortening. A similar delay exists between the ignimbrite pulses and the subduction of the Juan Fernandez ridge. This is consistent with the idea that large-volume ignimbrite eruptions occurred in the wake of the N-S passage of the ridge after slab steepening has allowed hot asthenospheric mantle to ascend into and cause the melting of the mantle wedge. In our model, the

  2. Analysis of radioactive strontium

    International Nuclear Information System (INIS)

    1977-01-01

    In environmental radiation survey, radioactive strontium has been analyzed in compliance with the manual ''Analyzing methods for radioactive strontium'' published in 1960 by the Science and Technology Agency, Japan, and revised in 1963. However, in a past decade, progress and development in analyzing methods and measuring equipments have been significant, therefore the manual was revised in 1974. Major revisions are as follows. (1) Analysis of 90 Sr with long half life was changed to the main theme and that of 89 Sr with short half life became a subordinate one. (2) Measuring criteria and sampling volume were revised. (3) Sample collection method was unified. (4) Analyzing method for soil was improved to NaOH-HCl method which has good recovery rate. (5) 90 Y separation method of simple operation was added for sea water analysis besides EDTA and fuming nitric acid methods. (6) Flame spectrometry for quantitative analysis of stable strontium was revised to atomic absorption spectrometry. The contents of the manual comprises 11 chapters describing introduction, measuring criteria for 90 Sr ( 89 Sr), rain and dust, land water, sea water, soil, sea bottom and river bottom sediments (changed from human urine and human bones), crops, milk (the previous one chapter was divided into two), marine organisms, and everyday foods, respectively. (Wakatsuki, Y.)

  3. Combined effect of oxygen deficient point defects and Ni doping in radio frequency magnetron sputtering deposited ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Saha, B., E-mail: biswajit.physics@gmail.com [Thin Film and Nano Science Laboratory, Department of Physics, Jadavpur University, 700 032 Kolkata (India); Department of Physics, National Institute of Technology Agartala, Jirania 799046, Tripura (India); Das, N.S.; Chattopadhyay, K.K. [Thin Film and Nano Science Laboratory, Department of Physics, Jadavpur University, 700 032 Kolkata (India)

    2014-07-01

    Ni doped ZnO thin films with oxygen deficiency have been synthesized on glass substrates by radio frequency magnetron sputtering technique using argon plasma. The combined effect of point defects generated due to oxygen vacancies and Ni doping on the optical and electrical properties of ZnO thin films has been studied in this work. Ni doping concentrations were varied and the structural, optical and electrical properties of the films were studied as a function of doping concentrations. The films were characterized with X-ray diffractometer, UV–Vis–NIR spectrophotometer, X-ray photoelectron spectroscopy, atomic force microscopy and electrical conductivity measurements. Oxygen deficient point defects (Schottky defects) made the ZnO thin film highly conducting while incorporation of Ni dopant made it more functional regarding their electrical and optical properties. The films were found to have tunable electrical conductivity with Ni doping concentrations. - Highlights: • ZnO thin films prepared by radio frequency magnetron sputtering technique • Synthesis process was stimulated to introduce Schottky-type point defects. • Point defects and external doping of Ni made ZnO thin films more functional. • Point defect induced high electrical conductivity in ZnO thin film. • Significant shift in optical bandgap observed in ZnO with Ni doping concentrations.

  4. Mass-specific respiration of mesozooplankton and its role in the maintenance of an oxygen-deficient ecological barrier (BEDOX) in the upwelling zone off Chile upon presence of a shallow oxygen minimum zone

    Science.gov (United States)

    Donoso, Katty; Escribano, Ruben

    2014-01-01

    A shallow oxygen minimum zone (OMZ) in the coastal upwelling zone off Chile may vertically confine most zooplankton to a narrow (oxygen consumption of the mesozooplankton community obtained in Bay of Mejillones, northern Chile (23°S) in May 2010, December 2010 and August 2011. Mass-specific respiration rates were in the range of 8.2-24.5 μmol O2 mg dry mass- 1 day- 1, at an average temperature of 12 °C. Estimates of the mesozooplankton biomass in the water column indicated that its aerobic respiration may remove daily a maximum of about 20% of oxygen available at the base of the oxycline. Since previous work indicates that zooplankton aggregate near the base of the oxycline, the impact of aerobic respiration on oxygen content might be even stronger at this depth. Mesozooplankton respiration, along with community respiration by microorganisms near the base of the oxycline and a strongly stratified condition (limiting vertical flux of O2), are suggested as being critical factors causing and maintaining a persistent subsurface oxygen-deficient ecological barrier (BEDOX) in the upwelling zone. This BEDOX layer can have a major role in affecting and regulating zooplankton distribution and their dynamics in the highly productive coastal upwelling zone of the Humboldt Current System.

  5. Enhanced magnetoresistance induced by oxygen deficiency in La0.4Ca0.6MnO3-δ oxides

    International Nuclear Information System (INIS)

    Triki, M.; Dhahri, E.; Hlil, E. K.; Garden, J. L.

    2014-01-01

    We report electrical features and magnetoresistance behavior of the oxygen deficient La 0.4 Ca 0.6 MnO 3-δ perovskites (δ = 0, 0.15, and 0.2). These samples will be referred to as S0, S15, and S20, respectively. The dependence of electrical transport on temperature and magnetic field is systematically investigated between 2 K and 400 K in magnetic field ranging up to 5 T. The parent compound shows a stable charge ordering/antiferromagnetic state with a semiconductor-like behavior in all considered temperature range. The variable range hopping and thermally activated hopping models are found to fit well with the electrical resistivity data at low and high temperatures, respectively. Oxygen deficiency tends to weaken the charge ordering and induce ferromagnetism and metallicity at low temperature. Metal insulator transition appears at higher fields for lower oxygen deficit (S15 sample) and without field for the S20 sample. The resistivity data for S15 sample are discussed in the framework of the variable-range hopping model. Abnormal transport properties were observed in the S20 sample, characterized by the double metal-insulator transitions and low minimum behavior. These results are discussed in terms of phenomenological percolation model, based on the phase segregation of ferromagnetic metallic clusters and paramagnetic insulating regions. While the parent compound shows no magnetoresistance, a large magnetoresistance is observed in the deficient samples at low temperature reaching 90% and 75% at 2 T for S15 and S20 samples, respectively. Noticeably, these values reached 98% and 91% at 5 T. The appearance of colossal magnetoresistance is attributed to the spin dependent hopping between spin clusters and/or ferromagnetic domains

  6. Intrinsic ZnO films fabricated by DC sputtering from oxygen-deficient targets for Cu(In,Ga)Se2 solar cell application

    Institute of Scientific and Technical Information of China (English)

    Chongyin Yang; DongyunWan; Zhou Wang; Fuqiang Huang

    2011-01-01

    Intrinsic zinc oxide films, normally deposited by radio frequency (RF) sputtering, are fabricated by direct current (DC) sputtering. The oxygen-deficient targets are prepared via a newly developed double crucible method. The 800-nm-thick film obtaines significantly higher carrier mobility compareing with that of the 800-nm-thick ZnO film. This is achieved by the widely used RF sputtering, which favors the prevention of carrier recombination at the interfaces and reduction of the series resistance of solar cells. The optimal ZnO film is used in a Cu (In, Ga) Se2 (CIGS) solar cell with a high efficiency of 11.57%. This letter demonstrates that the insulating ZnO films can be deposited by DC sputtering from oxygen-deficient ZnO targets to lower the cost of thin film solar cells.%Intrinsic zinc oxide films,normally deposited by radio frequency (RF) sputtering,are fabricated by direct current (DC) sputtering.The oxygen-deficient targets are prepared via a newly developed double crucible method.The 800-nm-thick film obtaines significantly higher carrier mobility compareing with that of the 800-nm-thick ZnO film.This is achieved by the widely used RF sputtering,which favors the prevention of carrier recombination at the interfaces and reduction of the series resistance of solar cells.The optimal ZnO film is used in a Cu (In,Ga) Se2 (C1GS) solar cell with a high efficiency of 11.57%.This letter demonstrates that the insulating ZnO films can be deposited by DC sputtering from oxygen-deficient ZnO targets to lower the cost of thin film solar cells.High resistance transparent intrinsic zinc oxide (i-ZnO)thin film has been widely nsed as the front electrode in transparent electronics and photovoltaic devices because of its low cost and nontoxicity.Owing to its unique characteristics of high transparency and adjustable resistivity in a certain range,the use of i-ZnO thin films as diffusion barrier layers of a-Si/μc-Si,CdTe,and CIGS thin-film solar cells has been advantageous

  7. Gas thermodesorption study of barium and strontium cerates

    International Nuclear Information System (INIS)

    Aksenova, T.I.; Khromushin, I.V.; Zhotabaev, Zh.R.; Bukenov, K.D.; Medvedeva, Z.V.; Berdauletov, A.K.

    2002-01-01

    Kinetic of water, oxygen, hydrogen and carbon dioxide molecules release from doped and undoped samples of barium cerates and doped strontium cerates during vacuum heating was studied. The samples were prepared by inductive melting method. The following two kinds of preliminary samples treatments were used: annealing in air (650-750 deg. C) and wet nitrogen atmosphere (625 deg.C). Main results of thermodesorption studies of barium and strontium cerates are represented in the table. The samples of doped LaSrMnO were investigated also. It was found that the initial doped samples (without preliminary annealing) did not show any gas release in temperature range of 20-1100 deg. C. This fact indicates on high stability of compositions and strong bond of 'host' oxygen in their lattice. A significant amount of water and oxygen molecules were released from BaCe 0.9 Nd 0.1 O 3 samples whereas water and hydrogen molecules desorption from SrCe 0.95 Y 0.05 O 3 samples took place. Hydrogen molecules desorption was found for strontium cerates samples; no hydrogen molecules release was observed for doped and pure barium cerate samples.Intensive water molecules release from doped samples confirms the necessity of oxygen vacancies creation in these compounds to get properties of proton conductivity, since it was not found any water molecules release from annealed undoped samples of BaCeO 3 It is necessary to notice that oxygen molecules release from these samples took place at ∼1000 deg. C that is significantly higher then from BaCeNdO samples. Forms of high temperatures part of oxygen and low temperature part of water spectra indicate that phase transformations are responsible for oxygen and water molecules desorption in this cases. These results are in good agreement with literature data. Desorption of water molecules from barium and strontium cerates took place. Oxygen desorption took place only from barium cerates. It can be explained as the following: doped barium cerates have

  8. High-resolution stratigraphy with strontium isotopes.

    Science.gov (United States)

    Depaolo, D J; Ingram, B L

    1985-02-22

    The isotopic ratio of strontium-87 to strontium-86 shows no detectable variation in present-day ocean water but changes slowly over millions of years. The strontium contained in carbonate shells of marine organisms records the ratio of strontium-87 to strontium-86 of the oceans at the time that the shells form. Sedimentary rocks composed of accumulated fossil carbonate shells can be dated and correlated with the use of high precision measurements of the ratio of strontium-87 to strontium-86 with a resolution that is similar to that of other techniques used in age correlation. This method may prove valuable for many geological, paleontological, paleooceanographic, and geochemical problems.

  9. Correlations between the Hall coefficient and the superconducting transport properties of oxygen-deficient YBa2Cu3O7-δ epitaxial thin films

    International Nuclear Information System (INIS)

    Jones, E.C.; Christen, D.K.; Thompson, J.R.; Feenstra, R.; Zhu, S.; Lowndes, D.H.; Phillips, J.M.; Siegal, M.P.; Budai, J.D.

    1993-01-01

    Strong correlations between the Hall coefficient R H , the transition temperature T c , and the critical current density J c were established in a series of epitaxial YBa 2 Cu 3 O 7-δ thin films as a function of oxygen deficiency δ. Steady increases in R H with δ suggest that deoxygenation reduces the density of states which, according to BCS theory, should lead to corresponding decreases in T c . In contrast, two well-known plateaus occurring at 90 K and 60 K were observed in T c vs δ. Others have ascribed these plateaus to either electronic phenomena or phase separations. We find that in the 90-K plateau, the critical current density J c (δ,H=0) decreases with δ and extrapolates toward zero at the edge of the plateau, while the relative-field dependence of J c (δ,H) and the flux-creep pinning energies are independent of δ. These observations suggest that the phase-separation scenario occurs on the 90-K plateau. However, electronic origins cannot be ruled out at present due to difficulties in determining the equilibrium superconducting properties of oxygen-deficient YBa 2 Cu 3 O 7-δ films

  10. Oxygen effect on mutagenic ionizing radiation damage in Bacillus subtilis spores of DNA polymerase I-proficient and -deficient strains

    International Nuclear Information System (INIS)

    Tanooka, H.

    1980-01-01

    The nature of mutagenic ionizing radiation damage modified by the presence of oxygen or water was examined by comparing mutagenic with lethal expression of the damage in Bacillus subtilis spores irradiated with 6-MeV electrons. No specific difference was recognized between oxygen-dependent and -independent damages or between polA + -dependent and -independent damages with this system. The induced mutation frequency for His + mutation per lethal hit was 4.7 x 10 -5 for all tested cases

  11. Magnetoresistance Versus Oxygen Deficiency in Epi-stabilized SrRu1 - x Fe x O3 - δ Thin Films

    Science.gov (United States)

    Dash, Umasankar; Acharya, Susant Kumar; Lee, Bo Wha; Jung, Chang Uk

    2017-03-01

    Oxygen vacancies have a profound effect on the magnetic, electronic, and transport properties of transition metal oxide materials. Here, we studied the influence of oxygen vacancies on the magnetoresistance (MR) properties of SrRu1 - x Fe x O3 - δ epitaxial thin films ( x = 0.10, 0.20, and 0.30). For this purpose, we synthesized highly strained epitaxial SrRu1 - x Fe x O3 - δ thin films with atomically flat surfaces containing different amounts of oxygen vacancies using pulsed laser deposition. Without an applied magnetic field, the films with x = 0.10 and 0.20 showed a metal-insulator transition, while the x = 0.30 thin film showed insulating behavior over the entire temperature range of 2-300 K. Both Fe doping and the concentration of oxygen vacancies had large effects on the negative MR contributions. For the low Fe doping case of x = 0.10, in which both films exhibited metallic behavior, MR was more prominent in the film with fewer oxygen vacancies or equivalently a more metallic film. For semiconducting films, higher MR was observed for more semiconducting films having more oxygen vacancies. A relatively large negative MR ( 36.4%) was observed for the x = 0.30 thin film with a high concentration of oxygen vacancies ( δ = 0.12). The obtained results were compared with MR studies for a polycrystal of (Sr1 - x La x )(Ru1 - x Fe x )O3. These results highlight the crucial role of oxygen stoichiometry in determining the magneto-transport properties in SrRu1 - x Fe x O3 - δ thin films.

  12. Depression Mechanism of Strontium Ions in Bastnaesite Flotation with Salicylhydroxamic Acid as Collector

    Directory of Open Access Journals (Sweden)

    Shiming Cao

    2018-02-01

    Full Text Available Metal ions are widely present in flotation pulp. Metal ions change solution chemistry and mineral surface properties, consequently affecting mineral flotation. In this work, the effect of strontium ions on bastnaesite flotation with salicylhydroxamic acid (SHA was investigated by microflotation tests, contact angle measurements, zeta-potential measurements, and X-ray photoelectron spectroscopy (XPS analysis. Microflotation tests confirmed that the addition of strontium ions decreased bastnaesite floatability, compared with that in the absence of strontium ions. Contact angle measurements suggested that the pretreatment of strontium ions decreased SHA adsorption. Zeta potential measurements confirmed that the bastnaesite was depressed by the adsorption of positively charged strontium species, and the lower adsorption capacity of SHA onto the bastnaesite surfaces was obtained after modifying with strontium ions. XPS analysis demonstrated that strontium ions adsorbed onto the bastnaesite surfaces through the interaction between strontium ions and oxygen atoms of surface ≡ CeOH 0 groups. This occurrence hindered surface Ce sites which chelated with SHA and therefore, decreased bastnaesite floatability.

  13. Strontium-90 - ED 4309

    International Nuclear Information System (INIS)

    Ammerich, M.; Frot, P.; Gambini, D.; Gauron, C.; Moureaux, P.; Herbelet, G.; Lahaye, T.; Le Guen, B.; Pihet, P.; Rannou, A.; Vidal, E.

    2012-12-01

    This sheet presents the characteristics of strontium-90, its origin, and its radio-physical and biological properties. It briefly describes its use in nuclear medicine. It indicates its dosimetric parameters for external exposure, cutaneous contamination, and internal exposure due to acute contamination or to chronic contamination. It indicates and comments the various exposure control techniques: ambient dose rate measurement, surface contamination measurement, atmosphere contamination. It addresses the means of protection: premise design, protection against external exposure and against internal exposure. It describes how areas are delimited and controlled within the premises: regulatory areas, controls to be performed. It addresses the personnel classification, training and medical survey. It addresses the issue of wastes and effluents. It briefly recalls the administrative procedures related to the authorization and declaration of possession and use of sealed and unsealed sources. It indicates regulatory aspects related to the transport of strontium-90, describes what is to be done in case of incident or accident (for the different types of contamination or exposure)

  14. High Rate and Stable Li-Ion Insertion in Oxygen-Deficient LiV3O8 Nanosheets as a Cathode Material for Lithium-Ion Battery.

    Science.gov (United States)

    Song, Huanqiao; Luo, Mingsheng; Wang, Aimei

    2017-01-25

    Low performance of cathode materials has become one of the major obstacles to the application of lithium-ion battery (LIB) in advanced portable electronic devices, hybrid electric vehicles, and electric vehicles. The present work reports a versatile oxygen-deficient LiV 3 O 8 (D-LVO) nanosheet that was synthesized successfully via a facile oxygen-deficient hydrothermal reaction followed by thermal annealing in Ar. When used as a cathode material for LIB, the prepared D-LVO nanosheets display remarkable capacity properties at various current densities (a capacity of 335, 317, 278, 246, 209, 167, and 133 mA h g -1 at 50, 100, 200, 500, 1000, 2000, and 4000 mA g -1 , respectively) and excellent lithium-ion storage stability, maintaining more than 88% of the initial reversible capacity after 200 cycles at 1000 mA g -1 . The outstanding electrochemical properties are believed to arise largely from the introduction of tetravalent V (∼15% V 4+ ) and the attendant oxygen vacancies into LiV 3 O 8 nanosheets, leading to intrinsic electrical conductivity more than 1 order of magnitude higher and lithium-ion diffusion coefficient nearly 2 orders of magnitude higher than those of LiV 3 O 8 without detectable V 4+ (N-LVO) and thus contributing to the easy lithium-ion diffusion, rapid phase transition, and the excellent electrochemical reversibility. Furthermore, the more uniform nanostructure, as well as the larger specific surface area of D-LVO than N-LVO nanosheets may also improve the electrolyte penetration and provide more reaction sites for fast lithium-ion diffusion during the discharge/charge processes.

  15. Strontium-90 fluoride data sheet

    Energy Technology Data Exchange (ETDEWEB)

    Fullam, H.T.

    1981-06-01

    This report is a compilation of available data and appropriate literature references on the properties of strontium-90 fluoride and nonradioactive strontium fluoride. The objective of the document is to compile in a single source pertinent data to assist potential users in the development, licensing, and use of /sup 90/SrF/sub 2/-fueled radioisotope heat sources for terrestrial power conversion and thermal applications. The report is an update of the Strontium-90 Fluoride Data Sheet (BNWL-2284) originally issued in April 1977.

  16. Magnetism, Spin Texture, and In-Gap States: Atomic Specialization at the Surface of Oxygen-Deficient SrTiO_{3}.

    Science.gov (United States)

    Altmeyer, Michaela; Jeschke, Harald O; Hijano-Cubelos, Oliver; Martins, Cyril; Lechermann, Frank; Koepernik, Klaus; Santander-Syro, Andrés F; Rozenberg, Marcelo J; Valentí, Roser; Gabay, Marc

    2016-04-15

    Motivated by recent spin- and angular-resolved photoemission (SARPES) measurements of the two-dimensional electronic states confined near the (001) surface of oxygen-deficient SrTiO_{3}, we explore their spin structure by means of ab initio density functional theory (DFT) calculations of slabs. Relativistic nonmagnetic DFT calculations display Rashba-like spin winding with a splitting of a few meV and when surface magnetism on the Ti ions is included, bands become spin-split with an energy difference ∼100  meV at the Γ point, consistent with SARPES findings. While magnetism tends to suppress the effects of the relativistic Rashba interaction, signatures of it are still clearly visible in terms of complex spin textures. Furthermore, we observe an atomic specialization phenomenon, namely, two types of electronic contributions: one is from Ti atoms neighboring the oxygen vacancies that acquire rather large magnetic moments and mostly create in-gap states; another comes from the partly polarized t_{2g} itinerant electrons of Ti atoms lying further away from the oxygen vacancy, which form the two-dimensional electron system and are responsible for the Rashba spin winding and the spin splitting at the Fermi surface.

  17. Double photoionization of strontium

    Energy Technology Data Exchange (ETDEWEB)

    Sokell, Emma; Grimm, Michael; Sheridan, Paul, E-mail: emma.sokell@ucd.i [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland)

    2010-02-01

    Resonant triple-differential cross-section (TDCS) measurements have been used to study the double photoionization process in strontium. Two sets of measurements were made at the photon energy of the 4p {yields} 4d resonance. The coplanar geometry was used and the fixed analyser, positioned at -90{sup 0} to the main axis of polarization of the photons, detected electrons with {approx}65% of the available excess energy. The mutual angle between the two electrons had a range just short of 90 {yields} 270{sup 0}. The TDCS exhibit unexpected lobes at a mutual angle of 180{sup 0}. Comparison with other measurements made with the same geometry but with different sharings of the available energy indicate that these TDCS all show the unexpected lobe. Some possible explanations for the lobe are considered.

  18. The effect of short-term dimethylglycine treatment on oxygen consumption in cytochrome oxidase deficiency: a double-blind randomized crossover clinical trial.

    Science.gov (United States)

    Liet, Jean-Michel; Pelletier, Véronique; Robinson, Brian H; Laryea, Maurice D; Wendel, Udo; Morneau, Sylvain; Morin, Charles; Mitchell, Grant; Lacroix, Jacques

    2003-01-01

    To study the effectiveness of dimethylglycine (DMG) on oxygen consumption (VO(2)) in children with Saguenay-Lac-Saint-Jean cytochrome-c oxidase (SLSJ-COX) deficiency (OMIM 220111). In a crossover randomized double-blind clinical trial, 5 children with SLSJ-COX deficiency, who were stable and old enough to comply with VO(2) measurement, were treated with placebo or DMG for 3 days, and with the alternate treatment after a 2-week washout period. VO(2) was measured by indirect calorimetry before and after treatment. Dietary caloric intake was calculated for 3 days before each measurement. Mean caloric intakes per day were 1562 and 1342 kcal x m(-2) before and during placebo, 1,336 and 1,380 before and during DMG, respectively. DMG was well tolerated and, in all cases, resulted in markedly increased blood DMG levels (617 + 203 mmol x L(-1)), versus 0 to 2 mmol x L(-1) without treatment. Mean VO(2) was lower after administration of either DMG (-1 +/- 3 mL x min(-1) x m(-2)) or placebo (-6 +/- 4), but neither difference was statistically significant. There was no detectable effect of DMG treatment on blood levels of lactate, pyruvate, bicarbonate, or pH. VO(2) values of patients (range, 101-135 mL x min(-1) x m(-2)) were lower than published norms (150-160 mL x min(-1) x m(-2)). This study suggests that treatment with DMG does not substantially change VO(2) in children with SLSJ-COX deficiency.

  19. Growth and micro structural studies on Yittria Stabilized Zirconia (YSZ) and Strontium Titanate (STO) buffer layers

    Energy Technology Data Exchange (ETDEWEB)

    Srinivas, S.; Bhatnagar, A.K. [Univ. of Hyderabad (India); Pinto, R. [Solid State Electronics Group, Bombay (India)] [and others

    1994-12-31

    Microstructure of Yittria Stabilized Zirconia (YSZ) and Strontium Titanate (STO) of radio frequency magnetron sputtered buffer layers was studied at various sputtering conditions on Si<100>, Sapphire and LaAlO{sub 3} <100> substrates. The effect of substrate temperatures upto 800 C and sputtering gas pressures in the range of 50 mTorr. of growth conditions was studied. The buffer layers of YSZ and STO showed a strong tendency for columnar structure with variation growth conditions. The buffer layers of YSZ and STO showed orientation. The tendency for columnar growth was observed above 15 mTorr sputtering gas pressure and at high substrate temperatures. Post annealing of these films in oxygen atmosphere reduced the oxygen deficiency and strain generated during growth of the films. Strong c-axis oriented superconducting YBa{sub 2}Cu{sub 9}O{sub 7-x} (YBCO) thin films were obtained on these buffer layers using pulsed laser ablation technique. YBCO films deposited on multilayers of YSZ and STO were shown to have better superconducting properties.

  20. Isotope exchange of strontium and molybdate ions in strontium polymolybdates

    International Nuclear Information System (INIS)

    Atun, G.

    2002-01-01

    The heterogeneous isotopic exchange reactions in strontium polymolybdates of Sr 2+ and MoO 4 2- ions in the strontium nitrate and sodium molybdate solutions have been studied using 90 Sr and 99 Mo as tracers. Electrometric methods have been used to study the compositions of strontium molybdates obtained by adding strontium chloride to a progressively acidified solution of sodium molybdate. It has been found that the exchange fraction increases with increasing chain length of strontium polymolybdate. The exchange equilibrium constant (K ex ) has been calculated between 298 and 348 K as well as ΔG deg, ΔH deg and ΔS deg. The results indicate that Sr 2+ cations have a much higher affinity for exchangers than MoO 4 2- anions. By fitting the data to the Dubinin-Radushkevich (D-R) isotherm it has been shown that the exchange capacity (X m ) for both ions is affected by the ion adsorption process at low temperatures and by the ion exchange process at high temperatures. At high concentrations, the recrystallization process contributes to on the cation exchange but is ineffective on the anion exchange mechanism. (author)

  1. Combined Increases in Mitochondrial Cooperation and Oxygen Photoreduction Compensate for Deficiency in Cyclic Electron Flow in Chlamydomonas reinhardtii[W][OPEN

    Science.gov (United States)

    Dang, Kieu-Van; Plet, Julie; Tolleter, Dimitri; Jokel, Martina; Cuiné, Stéphan; Carrier, Patrick; Auroy, Pascaline; Richaud, Pierre; Johnson, Xenie; Alric, Jean; Allahverdiyeva, Yagut; Peltier, Gilles

    2014-01-01

    During oxygenic photosynthesis, metabolic reactions of CO2 fixation require more ATP than is supplied by the linear electron flow operating from photosystem II to photosystem I (PSI). Different mechanisms, such as cyclic electron flow (CEF) around PSI, have been proposed to participate in reequilibrating the ATP/NADPH balance. To determine the contribution of CEF to microalgal biomass productivity, here, we studied photosynthesis and growth performances of a knockout Chlamydomonas reinhardtii mutant (pgrl1) deficient in PROTON GRADIENT REGULATION LIKE1 (PGRL1)–mediated CEF. Steady state biomass productivity of the pgrl1 mutant, measured in photobioreactors operated as turbidostats, was similar to its wild-type progenitor under a wide range of illumination and CO2 concentrations. Several changes were observed in pgrl1, including higher sensitivity of photosynthesis to mitochondrial inhibitors, increased light-dependent O2 uptake, and increased amounts of flavodiiron (FLV) proteins. We conclude that a combination of mitochondrial cooperation and oxygen photoreduction downstream of PSI (Mehler reactions) supplies extra ATP for photosynthesis in the pgrl1 mutant, resulting in normal biomass productivity under steady state conditions. The lower biomass productivity observed in the pgrl1 mutant in fluctuating light is attributed to an inability of compensation mechanisms to respond to a rapid increase in ATP demand. PMID:24989042

  2. Structural and superconducting properties of oxygen-deficient NdBa sub 2 Cu sub 3 O sub 7 minus. delta

    Energy Technology Data Exchange (ETDEWEB)

    Shaked, H. (Nuclear Research Center-Negev, Post Office Box 9001, Beer Sheva, Israel (IL) Ben Gurion University of the Negev, Post Office Box 653, Beer Sheva, Israel (IL)); Veal, B.W.; Faber, J. Jr.; Hitterman, R.L.; Balachandran, U.; Tomlins, G.; Shi, H.; Morss, L.; Paulikas, A.P. (Argonne National Laboratory, Argonne, Illinois 60439 (USA))

    1990-03-01

    Neutron diffraction was used to determine the structural properties of oxygen deficient NdBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} for 0.09{lt}{delta}{lt}0.74. It was found that superconductivity disappears at the orthorhombic-to-tetragonal phase transition which occurs at {delta}{sub {ital O}{ital T}}=0.45. Structural parameters vary smoothly with {delta} but exhibit a change in slope at the orthorhombic-to-tetragonal transition. The structural properties exhibit the same features found in YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} where {delta}{sub {ital O}{ital T}}=0.65. It is shown that the repulsion energy of oxygen atoms in the O(1) and O(5) sites in NdBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} is smaller than in YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}. This lower repulsion energy stabilizes the orthorhombic phase at lower values of {delta}. It is argued that the disappearance of superconductivity at the orthorhombic-to-tetragonal transition is an inherent property of the {ital R}Ba{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} ({ital R} denotes rare earth) system.

  3. Lung transplantation and survival outcomes in patients with oxygen-dependent COPD with regard to their alpha-1 antitrypsin deficiency status

    Directory of Open Access Journals (Sweden)

    Ekström M

    2017-11-01

    Full Text Available Magnus Ekström, Hanan Tanash Department of Respiratory Medicine and Allergology, Skåne University Hospital, Lund University, Lund, Sweden Background: Individuals with severe alpha-1 antitrypsin deficiency (AATD have an increased risk of developing COPD. However, outcomes during long-term oxygen therapy (LTOT in patients with severe AATD and hypoxemia are unknown.Patients and methods: This was a prospective, population-based, consecutive cohort study of patients on LTOT due to COPD in the period from January 1, 1987, to June 30, 2015, in the Swedish National Registry for Respiratory Failure (Swedevox. Severe AATD was identified using the Swedish AATD registry and confirmed by isoelectric focusing. Data on lung transplantation (LTx were obtained from the two lung transplantation centers in Sweden. Mortality and causes of death were assessed based on the National Causes of Death Registry and analyzed using multivariable Cox regression.Results: A total of 14,644 patients who started LTOT due to COPD were included in this study. No patient was lost to follow up. Patients with AATD were younger, included more males and more never smokers, and had fewer comorbidities. During a median follow-up of 1.6 years (interquartile range [IQR], 2.7 on LTOT, patients without severe AATD had a higher mortality, hazard ratio [HR] 1.53 (95% CI, 1.24–1.88, adjusting for age, sex, smoking status, body mass index, performance status, level of hypoxemia, and comorbidities. Cardiovascular deaths were increased. A higher proportion of AATD patients underwent LTx, 53 (19% vs 118 (1%. Survival after LTx was similar for AATD and non-AATD patients and was predicted by age.Conclusion: In oxygen-dependent COPD, patients with severe AATD have a longer survival time on LTOT, but they have a similar prognosis after lung transplantation compared with patients without AATD. Keywords: COPD, long-term oxygen therapy, lung transplantation, severe alpha-1 antitrypsin deficiency

  4. Stable and strontium isotopic records of molluscan shells, lower jurassic, Cuenca Neuquina, southwestern Mendoza, Argentina

    International Nuclear Information System (INIS)

    Cagnoni, M.C.; Valencio, S.A.; Ramos, A.M; Riccardi, A.C; Panarello, H.O

    2001-01-01

    The strontium, carbon and oxygen isotopic signal of the past oceans is accurately recorded by authigenic marine minerals such as carbonates, sulfates and phosphates. The variation of these isotope ratios through the geological time is used as a tool in correlating and dating marine sedimentary rocks. Many works have been done concerning to the changes in carbon, oxygen and strontium isotope ratios of different marine successions in the world. These allow the construction of curves of secular variations of the isotope signals with geological time (Jones et al., 1994a, 1994b; Veizer et al., 1999; Jacobsen and Kaufman, 1999). This work presents strontium, carbon and oxygen isotope ratios of Early Jurassic biogenic marine carbonates of Cuenca Neuquina in southwestern Mendoza (au)

  5. Polymeric strontium ranelate nonahydrate

    Directory of Open Access Journals (Sweden)

    Kenny Stahl

    2011-04-01

    Full Text Available The title compound, poly[[μ-aqua-tetraaqua{μ-5-[bis(carboxylatomethylamino]-3-carboxylatomethyl-4-cyanothiophene-2-carboxylato}distrontium(II] tetrahydrate], [Sr2(C12H6N2O8S(H2O5]·3.79H2O, crystallizes with nine- and eight-coordinated Sr2+ cations. They are bound to seven of the eight ranelate O atoms and five of the water molecules. The SrO8 and SrO9 polyhedra are interconnected by edge-sharing, forming hollow layers parallel to (011. The layers are, in turn, interconnected by ranelate anions, forming a metal–organic framework (MOF structure with channels along the a axis. The four water molecules not coordinated to strontium are located in these channels and hydrogen bonded to each other and to the ranelates. Part of the water H atoms are disordered. The compound dehydrates very easily and 0.210 (4 water molecules out of nine were lost during crystal mounting causing additional disorder in the water structure.

  6. Photostriction of strontium ruthenate

    KAUST Repository

    Wei, Tzu-Chiao

    2017-04-24

    Transition metal oxides with a perovskite crystal structure exhibit a variety of physical properties associated with the lattice. Among these materials, strontium ruthenate (SrRuO3) displays unusually strong coupling of charge, spin and lattice degrees of freedom that can give rise to the photostriction, that is, changes in the dimensions of material due to the absorption of light. In this study, we observe a photon-induced strain as high as 1.12% in single domain SrRuO3, which we attribute to a nonequilibrium of phonons that are a result of the strong interaction between the crystalline lattice and electrons excited by light. In addition, these light-induced changes in the SrRuO3 lattice affect its electrical resistance. The observation of both photostriction and photoresistance in SrRuO3 suggests the possibility of utilizing the mechanical and optical functionalities of the material for next-generation optoelectronics, such as remote switches, light-controlled elastic micromotors, microactuators and other optomechanical systems.

  7. Spin polarized electronic states and spin textures at the surface of oxygen-deficient SrTiO3

    Science.gov (United States)

    Jeschke, Harald O.; Altmeyer, Michaela; Rozenberg, Marcelo; Gabay, Marc; Valenti, Roser

    We investigate the electronic structure and spin texture at the (001) surface of SrTiO3 in the presence of oxygen vacancies by means of ab initio density functional theory (DFT) calculations of slabs. Relativistic non-magnetic DFT calculations exhibit Rashba-like spin winding with a characteristic energy scale ~ 10 meV. However, when surface magnetism on the Ti ions is included, bands become spin-split with an energy difference ~ 100 meV at the Γ point. This energy scale is comparable to the observations in SARPES experiments performed on the two-dimensional electronic states confined near the (001) surface of SrTiO3. We find the spin polarized state to be the ground state of the system, and while magnetism tends to suppress the effects of the relativistic Rashba interaction, signatures of it are still clearly visible in terms of complex spin textures. We gratefully acknowledge financial support from the Deutsche Forschungsgemeinschaft through grants SFB/TR 49 and FOR 1346.

  8. Strontium 90 fallout prediction

    International Nuclear Information System (INIS)

    Sarmiento, J.L.; Gwinn, E.

    1986-01-01

    An empirical formula is developed for predicting monthly sea level strontium 90 fallout (F) in the northern hemisphere as a function of time (t), precipitation rate (P), latitude (phi), longitude (lambda), and the sea level concentration of stronium 90 in air (C): F(lambda, phi, t) = C(t, phi)[v /sub d/(phi) + v/sub w/(lambda, phi, t)], where v/sub w/(lambda, phi, t) = a(phi)[P(lambda, phi, t)/P/sub o/]/sup b//sup (//sup phi//sup )/ is the wet removal, v/sub d/(phi) is the dry removal and P 0 is 1 cm/month. The constants v/sub d/, a, and b are determined as functions of latitude by fitting land based observations. The concentration of 90 Sr in air is calculated as a function of the deseasonalized concentration at a reference latitude (C-bar/sub r//sub e//sub f/), the ratio of the observations at the latitude of interest to the reference latitude (R), and a function representing the seasonal trend in the air concentration (1 + g): C-bar(t, phi) = C/sub r//sub e//sub f/(t)R(phi)[1 + g(m, phi)]; m is the month. Zonal trends in C are shown to be relatively small. This formula can be used in conjuction with precipitation observations and/or estimates to predict fallout in the northern hemisphere for any month in the years 1954 to 1974. Error estimates are given; they do not include uncertainty due to errors in precipitation data

  9. The chemical composition of TS 01, the most oxygen-deficient planetary nebula. AGB nucleosynthesis in a metal-poor binary star

    Science.gov (United States)

    Stasińska, G.; Morisset, C.; Tovmassian, G.; Rauch, T.; Richer, M. G.; Peña, M.; Szczerba, R.; Decressin, T.; Charbonnel, C.; Yungelson, L.; Napiwotzki, R.; Simón-Díaz, S.; Jamet, L.

    2010-02-01

    The planetary nebula TS 01 (also called PN G 135.9+55.9 or SBS 1150+599A) with its record-holding low oxygen abundance and its double degenerate close binary core (period 3.9 h) is an exceptional object located in the Galactic halo. We have secured observational data in a complete wavelength range to pin down the abundances of half a dozen elements in the nebula. The abundances are obtained via detailed photoionization modelling which takes into account all the observational constraints (including geometry and aperture effects) using the pseudo-3D photoionization code Cloudy_3D. The spectral energy distribution of the ionizing radiation is taken from appropriate model atmospheres. Incidentally we find from the new observational constraints that both stellar components contribute to the ionization: the “cool” one provides the bulk of hydrogen ionization, while the “hot” one is responsible for the presence of the most highly charged ions, which explains why previous attempts to model the nebula experienced difficulties. The nebular abundances of C, N, O, and Ne are found to be 1/3.5, 1/4.2, 1/70, and 1/11 of the solar value respectively, with uncertainties of a factor 2. Thus the extreme O deficiency of this object is confirmed. The abundances of S and Ar are less than 1/30 of solar. The abundance of He relative to H is 0.089 ± 0.009. Standard models of stellar evolution and nucleosynthesis cannot explain the abundance pattern observed in the nebula. To obtain an extreme oxygen deficiency in a star whose progenitor has an initial mass of about 1 M⊙ requires an additional mixing process, which can be induced by stellar rotation and/or by the presence of the close companion. We have computed a stellar model with an initial mass of 1 M⊙, appropriate metallicity, and initial rotation of 100 km s-1, and find that rotation greatly improves the agreement between the predicted and observed abundances. Based on observations obtained at the Canada

  10. Regional gradients in surface sediment nitrogen isotopes as a reflection of nutrient cycling and oxygen deficiency in upwelling areas off Peru and Namibia (Invited)

    Science.gov (United States)

    Schneider, R. R.; Mollier-Vogel, E.; Martinez, P.

    2010-12-01

    The sedimentary d15N signal is commonly considered as a reflection of the marine nutrient cycling and related biochemical processes in the overlying water masses. In the modern ocean all processes together result in a mean d15N value of about 5 to 6 per mill for dissolved nitrate. Deviations from this value are considered as a product mainly of nitrogen fixation and nitrate supply causing lower values, while nitrate utilization and denitrification, as well as organic matter degradation tend to shift the signal to higher values. As denitrification is only occurring under conditions of strong oxygen limitation in the water column outstandingly high d15N values in sediment records are commonly taken as indirect evidence for strong oxygen minimum conditions in the past. By comparing surface sediment values from coastal upwelling areas off Namibia and Peru, we test whether such an approach is applicable. Only the Peruvian system is characterized by a pronounced oxygen minimum zone (OMZ) that extends across the shelf and slope far into the Eastern Equatorial Pacific. For comparison we present new results for the Peruvian margin between 2°N and 20°S within and below the Peruvian OMZ in combination with a similar data set from the Namibian margin with an OMZ restricted to the inner shelf. The Peruvian sediment data is furthermore compared to d15N of dissolved nitrate in the overlying water column to better understand how regional oceanography effects the water column d15N and thus the sediment surface signal. Productivity and nitrate uptake is maximal at the position of local and perennial upwelling cells in both systems. However, due to continuous nutrient supply into the upwelling systems sedimentary d15N values on the outer shelves and slopes reveal an increase of only about 2 to 3 per mill over the mean ocean value. Only where extreme oxygen deficiency occurs, as off Peru between 10 and 20 S, the sedimentary d15N signal reaches very high values above 10 per mill

  11. Rb-Sr whole-rock and mineral ages, K-Ar, 40Ar/39Ar, and U-Pb mineral ages, and strontium, lead, neodymium, and oxygen isotopic compositions for granitic rocks from the Salinian Composite Terrane, California:

    Science.gov (United States)

    Kistler, R.W.; Champion, D.E.

    2001-01-01

    This report summarizes new and published age and isotopic data for whole-rocks and minerals from granitic rocks in the Salinian composite terrane, California. Rubidium-strontium whole-rock ages of plutons are in two groups, Early Cretaceous (122 to 100 Ma) and Late Cretaceous (95 to 82 Ma). Early Cretaceous plutons occur in all granitic rock exposures from Bodega Head in the north to those from the Santa Lucia and Gabilan Ranges in the central part of the terrane. Late Cretaceous plutons have been identified in the Point Reyes Peninsula, the Santa Lucia and the Gabilan Ranges, and in the La Panza Range in the southern part of the terrane. Ranges of initial values of isotopic compositions are 87Sr/86Sr, 0.7046-0.7147, δ18O, +8.5 to +12.5 per mil, 206Pb/204Pb, 18.901-19.860, 207Pb/204Pb, 15.618-15.814, 208Pb/204Pb, 38.569- 39.493, and εNd, +0.9 to -8.6. The initial 87Sr/86Sr=0.706 isopleth is identified in the northern Gabilan Range and in the Ben Lomond area of the Santa Cruz Mountains, in Montara Mountain, in Bodega Head, and to the west of the Farallon Islands on the Cordell Bank. This isotopic boundary is offset about 95 miles (160km) by right-lateral displacements along the San Gregorio-Hosgri and San Andreas fault systems.

  12. PHYTOALEXIN DEFICIENT 4 affects reactive oxygen species metabolism, cell wall and wood properties in hybrid aspen (Populus tremula L. × tremuloides).

    Science.gov (United States)

    Ślesak, Ireneusz; Szechyńska-Hebda, Magdalena; Fedak, Halina; Sidoruk, Natalia; Dąbrowska-Bronk, Joanna; Witoń, Damian; Rusaczonek, Anna; Antczak, Andrzej; Drożdżek, Michał; Karpińska, Barbara; Karpiński, Stanisław

    2015-07-01

    The phytoalexin deficient 4 (PAD4) gene in Arabidopsis thaliana (AtPAD4) is involved in the regulation of plant--pathogen interactions. The role of PAD4 in woody plants is not known; therefore, we characterized its function in hybrid aspen and its role in reactive oxygen species (ROS)-dependent signalling and wood development. Three independent transgenic lines with different suppression levels of poplar PAD expression were generated. All these lines displayed deregulated ROS metabolism, which was manifested by an increased H2O2 level in the leaves and shoots, and higher activities of manganese superoxide dismutase (MnSOD) and catalase (CAT) in the leaves in comparison to the wild-type plants. However, no changes in non-photochemical quenching (NPQ) between the transgenic lines and wild type were observed in the leaves. Moreover, changes in the ROS metabolism in the pad4 transgenic lines positively correlated with wood formation. A higher rate of cell division, decreased tracheid average size and numbers, and increased cell wall thickness were observed. The results presented here suggest that the Populus tremula × tremuloides PAD gene might be involved in the regulation of cellular ROS homeostasis and in the cell division--cell death balance that is associated with wood development. © 2014 John Wiley & Sons Ltd.

  13. Artificial oxygen transport protein

    Science.gov (United States)

    Dutton, P. Leslie

    2014-09-30

    This invention provides heme-containing peptides capable of binding molecular oxygen at room temperature. These compounds may be useful in the absorption of molecular oxygen from molecular oxygen-containing atmospheres. Also included in the invention are methods for treating an oxygen transport deficiency in a mammal.

  14. Porous allograft bone scaffolds: doping with strontium.

    Directory of Open Access Journals (Sweden)

    Yantao Zhao

    Full Text Available Strontium (Sr can promote the process of bone formation. To improve bioactivity, porous allograft bone scaffolds (ABS were doped with Sr and the mechanical strength and bioactivity of the scaffolds were evaluated. Sr-doped ABS were prepared using the ion exchange method. The density and distribution of Sr in bone scaffolds were investigated by inductively coupled plasma optical emission spectrometry (ICP-OES, X-ray photoelectron spectroscopy (XPS, and energy-dispersive X-ray spectroscopy (EDS. Controlled release of strontium ions was measured and mechanical strength was evaluated by a compressive strength test. The bioactivity of Sr-doped ABS was investigated by a simulated body fluid (SBF assay, cytotoxicity testing, and an in vivo implantation experiment. The Sr molar concentration [Sr/(Sr+Ca] in ABS surpassed 5% and Sr was distributed nearly evenly. XPS analyses suggest that Sr combined with oxygen and carbonate radicals. Released Sr ions were detected in the immersion solution at higher concentration than calcium ions until day 30. The compressive strength of the Sr-doped ABS did not change significantly. The bioactivity of Sr-doped material, as measured by the in vitro SBF immersion method, was superior to that of the Sr-free freeze-dried bone and the Sr-doped material did not show cytotoxicity compared with Sr-free culture medium. The rate of bone mineral deposition for Sr-doped ABS was faster than that of the control at 4 weeks (3.28 ± 0.23 µm/day vs. 2.60 ± 0.20 µm/day; p<0.05. Sr can be evenly doped into porous ABS at relevant concentrations to create highly active bone substitutes.

  15. Iron deficiency in childhood

    NARCIS (Netherlands)

    Uijterschout, L.

    2015-01-01

    Iron deficiency (ID) is the most common micronutrient deficiency in the world. Iron is involved in oxygen transport, energy metabolism, immune response, and plays an important role in brain development. In infancy, ID is associated with adverse effects on cognitive, motor, and behavioral development

  16. Enhanced Reactive Oxygen Species Production, Acidic Cytosolic pH and Upregulated Na+/H+ Exchanger (NHE) in Dicer Deficient CD4+ T Cells.

    Science.gov (United States)

    Singh, Yogesh; Zhou, Yuetao; Zhang, Shaqiu; Abdelazeem, Khalid N M; Elvira, Bernat; Salker, Madhuri S; Lang, Florian

    2017-01-01

    MicroRNAs (miRNAs) negatively regulate gene expression at a post-transcriptional level. Dicer, a cytoplasmic RNase III enzyme, is required for the maturation of miRNAs from precursor miRNAs. Dicer, therefore, is a critical enzyme involved in the biogenesis and processing of miRNAs. Several biological processes are controlled by miRNAs, including the regulation of T cell development and function. T cells generate reactive oxygen species (ROS) with parallel H+ extrusion accomplished by the Na+/H+-exchanger 1 (NHE1). The present study explored whether ROS production, as well as NHE1 expression and function are sensitive to the lack of Dicer (miRNAs deficient) and could be modified by individual miRNAs. CD4+ T cells were isolated from CD4 specific Dicer deficient (DicerΔ/Δ) mice and the respective control mice (Dicerfl/fl). Transcript and protein levels were quantified with RT-PCR and Western blotting, respectively. For determination of intracellular pH (pHi) cells were incubated with the pH sensitive dye bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF) and Na+/H+ exchanger (NHE) activity was calculated from re-alkalinization after an ammonium pulse. Changes in cell volume were measured using the forward scatter in flow cytometry, and ROS production utilizing 2',7' -dichlorofluorescin diacetate (DCFDA) fluorescence. Transfection of miRNA-control and mimics in T cells was performed using DharmaFECT3 reagent. ROS production, cytosolic H+ concentration, NHE1 transcript and protein levels, NHE activity, and cell volume were all significantly higher in CD4+ T cells from DicerΔ/Δ mice than in CD4+ T cells from Dicerfl/fl mice. Furthermore, individual miR-200b and miR-15b modify pHi and NHE activity in Dicerfl/fl and DicerΔ/Δ CD4+ T cells, respectively. Lack of Dicer leads to oxidative stress, cytosolic acidification, upregulated NHE1 expression and activity as well as swelling of CD4+ T cells, functions all reversed by miR-15b or miR-200b. © 2017 The Author

  17. Simulating the Transfer of Strontium-90 from Soil to Leafy Vegetables by Using Strontium-88

    OpenAIRE

    Kuke, Ding; Shujuan, Liu; Yingxue, He; Dong, Yan; Fengshou, Zhang; Shuifeng, Wang; Jinghua, Guo; Wei, Zhang; Xin, Wang; Xiaoyan, Jiang

    2016-01-01

    The transfer, from soil to Chinese cabbage and spinach, of radioactive strontium-90 released as a result of accidents in nuclear power stations was studied using a stable isotope of strontium, namely nuclide strontium-88 (88Sr). The study led to an experimental model for assessing the hazard of radionuclide strontium-90 (90Sr) entering the food chain and for predicting the risk to food safety. Chinese cabbage and spinach were grown in pots in a greenhouse and irrigated with deionized water co...

  18. In situ XANES cell used for the study of lanthanum strontium cuprate deNOx catalysts

    DEFF Research Database (Denmark)

    Hagen, Anke

    2011-01-01

    , maintaining charge neutrality, with the concentration of oxygen vacancies likely increasing at substitution ratios larger than Sr/La>0.08. During heating in air, the valence of copper ions in the structure increased. Upon exposure to NO at 500 °C the valence of copper ions in a lanthanum strontium cuprate...

  19. Storage Pool Deficiencies

    Science.gov (United States)

    ... Deficiency Factor V Deficiency Combined FV & FVIII Deficiencies Factor VII Deficiency Factor X Deficiency Factor XI Deficiency Factor ... Deficiency Factor V Deficiency Combined FV & FVIII Deficiencies Factor VII Deficiency Factor X Deficiency Factor XI Deficiency Factor ...

  20. Combined transuranic-strontium extraction process

    Science.gov (United States)

    Horwitz, E. Philip; Dietz, Mark L.

    1992-01-01

    The transuranic (TRU) elements neptunium, plutonium and americium can be separated together with strontium from nitric acid waste solutions in a single process. An extractant solution of a crown ether and an alkyl(phenyl)-N,N-dialkylcarbanylmethylphosphine oxide in an appropriate diluent will extract the TRU's together with strontium, uranium and technetium. The TRU's and the strontium can then be selectively stripped from the extractant for disposal.

  1. Ion exchange of strontium on synthetic hydroxyapatite

    International Nuclear Information System (INIS)

    Lazic, S.; Vukovic, Z.

    1991-01-01

    Adsorption of strontium ions on synthetic hydroxyapatite was examined using both batch and column methods. The apatite was prepared from aqueous solutions and characterized by standard analytical methods. The sample obtained had characteristics of well crystallized stoichiometric hydroxyapatite. The experimental data for sorption of strontium can be very well fitted with Langmuir's adsorption isotherm. It was found that sorption occurs by an ion exchange reaction between strontium ions in solution and calcium ions in apatite. (author) 14 refs.; 5 figs.; 1 tab

  2. Kinetics of strontium sorption in calcium phosphate

    International Nuclear Information System (INIS)

    Bacic, S.; Komarov, V.F.; Vukovic, Z.

    1989-01-01

    Kinetics of strontium sorption by highly dispersed solids: tricalcium phosphate (Ca 3 (PO 4 ) 2 , TCP) and hydroxyapatite (Ca 5 (PO 4 ) 3 )H, HAP) were investigated. Analysis of sorption data was made taking into consideration composition and morphology of ultra micro particles. Conclusion is that the isomorphous strontium impurity is structurally sensitive element for calcium phosphate. It was determined that the beginning of strontium desorption corresponds to the beginning of transformation of the TCP - HAP (author)

  3. Reactive Oxygen Species-Mediated Loss of Synaptic Akt1 Signaling Leads to Deficient Activity-Dependent Protein Translation Early in Alzheimer's Disease.

    Science.gov (United States)

    Ahmad, Faraz; Singh, Kunal; Das, Debajyoti; Gowaikar, Ruturaj; Shaw, Eisha; Ramachandran, Arathy; Rupanagudi, Khader Valli; Kommaddi, Reddy Peera; Bennett, David A; Ravindranath, Vijayalakshmi

    2017-12-01

    Synaptic deficits are known to underlie the cognitive dysfunction seen in Alzheimer's disease (AD). Generation of reactive oxygen species (ROS) by β-amyloid has also been implicated in AD pathogenesis. However, it is unclear whether ROS contributes to synaptic dysfunction seen in AD pathogenesis and, therefore, we examined whether altered redox signaling could contribute to synaptic deficits in AD. Activity dependent but not basal translation was impaired in synaptoneurosomes from 1-month old presymptomatic APP Swe /PS1ΔE9 (APP/PS1) mice, and this deficit was sustained till middle age (MA, 9-10 months). ROS generation leads to oxidative modification of Akt1 in the synapse and consequent reduction in Akt1-mechanistic target of rapamycin (mTOR) signaling, leading to deficiency in activity-dependent protein translation. Moreover, we found a similar loss of activity-dependent protein translation in synaptoneurosomes from postmortem AD brains. Loss of activity-dependent protein translation occurs presymptomatically early in the pathogenesis of AD. This is caused by ROS-mediated loss of pAkt1, leading to reduced synaptic Akt1-mTOR signaling and is rescued by overexpression of Akt1. ROS-mediated damage is restricted to the synaptosomes, indicating selectivity. We demonstrate that ROS-mediated oxidative modification of Akt1 contributes to synaptic dysfunction in AD, seen as loss of activity-dependent protein translation that is essential for synaptic plasticity and maintenance. Therapeutic strategies promoting Akt1-mTOR signaling at synapses may provide novel target(s) for disease-modifying therapy in AD. Antioxid. Redox Signal. 27, 1269-1280.

  4. ABOUT A CHOICE OF MATHEMATICAL MODELS OF KINETICS OF CULTIVATION OF SACCHAROMYCES CEREVISIAE YEAST IN THE CONDITIONS OF DEFICIENCY OF OXYGEN

    Directory of Open Access Journals (Sweden)

    V. B. Tishin

    2015-01-01

    Full Text Available Summary. In the production technology of many foods microbiological processes are crucial to the economic indicators of enterprises and the quality of the products manufactured. The examples of this are the production, where the biomass is the end product. For example, the production of various strains of the yeast Saccharomyces for different branches of the food industry: baking, brewing, winemaking, as well as for the pharmaceutical industry. The development of mathematical models of microbial cells is one of the greatest challenges of microbiology. The need to search for mathematical models is dictated by the continuous development of microbiological industry, increases in the requirements for the production design, maintenance and predictions of the processes depending on the change of process parameters. However, this requires knowledge of the laws governing material and energy exchange between the culture medium and the cell and the availability of mathematical models describing them. This knowledge cannot be obtained without studying the biological processes kinetics. Kinetic regularities of microbial growth is largely determined by the selection method of the microbiological process and the type of equipment in which these processes occur. Many biological processes can be described with a simple mathematical model, but there are kinetic regularities of biological processes that can only be described by equations of more complex type. Culturing yeast kinetic models, reflecting the complexity of the biological processes occurring during the cultivation were obtained. According to the analysis of experimental data on the Saccharomyces cerevisiae yeast culturing with a batch process, a system of equations (mathematical model, giving a functional relationship of biomass growth and cells consumption of carbohydrates with their different initial values in a culture medium under conditions of oxygen deficiency without stirring is obtained.

  5. Strontium sorption on Savannah River Plant soils

    International Nuclear Information System (INIS)

    Hoeffner, S.L.

    1984-12-01

    A laboratory study of strontium-85 sorption was conducted using Savannah River Plant soil and groundwater from the low-level waste burial ground. Systematic variation of soil and water composition indicates that strontium sorption is most strongly a function of pH. Changes in clay content and in K + , Ca 2+ , or Mg 2+ concentrations influence strontium sorption indirectly through the slight pH changes which result. The ions Na + , Cl - , and NO 3 - have no effect. Ferrous ion, added to groundwater to simulate the conditions of water at the bottom of waste trenches, did not account for low strontium sorption observed with some trench waters

  6. Optimization of a Strontium Aluminate

    Energy Technology Data Exchange (ETDEWEB)

    Bone, Alexandria N. [Maryville College, TN (United States)

    2017-08-01

    Strontium aluminate with Eu2+ and Dy3+ has been at the forefront of emerging applications for storage phosphors since its discovery in 1996. In this study, the emission intensity and luminescence lifetime of SrAl2O4: Eu2+, Dy3+ were enhanced by partial substitution of Ca2+ into Sr2+ sites in the matrix.

  7. Simulating the Transfer of Strontium-90 from Soil to Leafy Vegetables by Using Strontium-88.

    Science.gov (United States)

    Kuke, Ding; Shujuan, Liu; Yingxue, He; Dong, Yan; Fengshou, Zhang; Shuifeng, Wang; Jinghua, Guo; Wei, Zhang; Xin, Wang; Xiaoyan, Jiang

    The transfer, from soil to Chinese cabbage and spinach, of radioactive strontium-90 released as a result of accidents in nuclear power stations was studied using a stable isotope of strontium, namely nuclide strontium-88 ( 88 Sr). The study led to an experimental model for assessing the hazard of radionuclide strontium-90 ( 90 Sr) entering the food chain and for predicting the risk to food safety. Chinese cabbage and spinach were grown in pots in a greenhouse and irrigated with deionized water containing known quantities of strontium. Based on the strontium content of that water, the plants were divided into five groups (treatments) and strontium content of the soil, and 30-day-old plants were determined by inductively coupled plasma atomic emission spectroscopy instrument (ICP-AES). Data on the strontium content of soil and plants enabled the development of a model using MATLAB, a mathematical software package, which included curve fitting and problem solving using regression equations and differential equations. Although strontium curves for leaves, stems, and roots of Chinese cabbage were not exactly the same, all showed a non-linear increase when compared with the increase in the content of strontium in soil. Strontium curves for leaves, stems, and roots of spinach were very similar and showed an initial increase followed by a decrease. Strontium concentrations in both Chinese cabbage and spinach were initially related to the concentrations of sodium and sulfur, the next two relevant nuclides being calcium and magnesium. The relationship between calcium and strontium in Chinese cabbage was different from that in spinach. By using 88 Sr to simulate the transfer of radionuclide 90 Sr from soil to a crop, the relevant data required to deal with accidental release of strontium can be obtained using a fitting curve and regression equations, thereby providing some experimental basis for evaluating the potential hazards posed by such accidents to the food chain.

  8. Strontium 90 in Swedish dairy milk 1978

    International Nuclear Information System (INIS)

    Gillberg-Wickman, M.; Oestergren, I.

    1980-01-01

    The contamination of strontium-90 in Swedish milk during 1978 is practically the same as in 1977. The country-wide mean ratio of strontium-90 to calcium in milk is 0.12 Bq 90 Sr(gCa) -1 , based on monthly determinations of samples obtained from 8 dairy plants situated throughout the country. (author)

  9. Corrosion of copper in oxygen-deficient groundwater with and without deep bedrock micro-organisms: Characterisation of microbial communities and surface processes

    Energy Technology Data Exchange (ETDEWEB)

    Huttunen-Saarivirta, E., E-mail: elina.huttunen-saarivirta@vtt.fi [VTT Technical Research Centre of Finland, Materials Performance, Kemistintie 3, FI-02044 VTT (Finland); Rajala, P. [VTT Technical Research Centre of Finland, Materials Performance, Kemistintie 3, FI-02044 VTT (Finland); Bomberg, M. [VTT Technical Research Centre of Finland, Geobiotechnology, Tietotie 2, FI-02044 VTT (Finland); Carpén, L. [VTT Technical Research Centre of Finland, Materials Performance, Kemistintie 3, FI-02044 VTT (Finland)

    2017-02-28

    Highlights: • Copper was exposed to groundwater with and without deep bedrock micro-organisms. • Biofilm composition was determined and correlated with the behaviour of copper. • Under biotic conditions, the film of Cu{sub 2}S formed on copper surfaces. • Bacterial pool was in a key role for the morphology and properties of Cu{sub 2}S film. • Under abiotic conditions, Cu{sub 2}O systematically developed on copper surfaces. - Abstract: Copper specimens were exposed to oxygen-deficient artificial groundwater in the presence and absence of micro-organisms enriched from the deep bedrock of the planned nuclear waste repository site at Olkiluoto island on the western coast of Finland. During the exposure periods of 4 and 10 months, the copper specimens were subjected to electrochemical measurements. The biofilm developed on the specimens and the water used in the exposures were subjected to microbiological analyses. Changes in the water chemistry were also determined and surfaces of the copper specimens were characterized with respect to the morphology and composition of the formed corrosion products. The results showed that under biotic conditions, redox of the water and open circuit potential (OCP) of the copper specimens were generally negative and resulted in the build-up of a copper sulphide, Cu{sub 2}S, layer due to the activity of sulphate-reducing bacteria (SRB) that were included in the system. In the 4-month test, the electrochemical behaviour of the specimens changed during the exposure and alphaproteobactria Rhizobiales were the dominant bacterial group in the biofilm where the highest corrosion rate was observed. In the 10-month test, however, deltaproteobacteria SRB flourished and the initial electrochemical behaviour and the low corrosion rate of the copper were retained until the end of the test period. Under abiotic conditions, the positive water redox potential and specimen OCP correlated with the formation of copper oxide, Cu{sub 2}O

  10. Corrosion of copper in oxygen-deficient groundwater with and without deep bedrock micro-organisms: Characterisation of microbial communities and surface processes

    International Nuclear Information System (INIS)

    Huttunen-Saarivirta, E.; Rajala, P.; Bomberg, M.; Carpén, L.

    2017-01-01

    Highlights: • Copper was exposed to groundwater with and without deep bedrock micro-organisms. • Biofilm composition was determined and correlated with the behaviour of copper. • Under biotic conditions, the film of Cu_2S formed on copper surfaces. • Bacterial pool was in a key role for the morphology and properties of Cu_2S film. • Under abiotic conditions, Cu_2O systematically developed on copper surfaces. - Abstract: Copper specimens were exposed to oxygen-deficient artificial groundwater in the presence and absence of micro-organisms enriched from the deep bedrock of the planned nuclear waste repository site at Olkiluoto island on the western coast of Finland. During the exposure periods of 4 and 10 months, the copper specimens were subjected to electrochemical measurements. The biofilm developed on the specimens and the water used in the exposures were subjected to microbiological analyses. Changes in the water chemistry were also determined and surfaces of the copper specimens were characterized with respect to the morphology and composition of the formed corrosion products. The results showed that under biotic conditions, redox of the water and open circuit potential (OCP) of the copper specimens were generally negative and resulted in the build-up of a copper sulphide, Cu_2S, layer due to the activity of sulphate-reducing bacteria (SRB) that were included in the system. In the 4-month test, the electrochemical behaviour of the specimens changed during the exposure and alphaproteobactria Rhizobiales were the dominant bacterial group in the biofilm where the highest corrosion rate was observed. In the 10-month test, however, deltaproteobacteria SRB flourished and the initial electrochemical behaviour and the low corrosion rate of the copper were retained until the end of the test period. Under abiotic conditions, the positive water redox potential and specimen OCP correlated with the formation of copper oxide, Cu_2O. Furthermore, in the absence of

  11. Strontium-90 measurements in Switzerland

    International Nuclear Information System (INIS)

    Friedli, C.; Geering, J.J.; Lerch, P.

    1988-01-01

    Strontium-90 contamination in Switzerland has been measured since the sixties. The determination of 90 Sr in human vertebrae, milk-teeth, milk and wine have shown a maximum activity between 1964 and 1966. Since 1976, the survey has been extended to the food chain. After the Chernobyl accident, the measurements indicated a significative 90 Sr contamination in the Tessin and the north-east of Switzerland. The partition of 90 Sr in wheat has been determined and transfer factors are given for the milk - cheese - whey chain

  12. Imprint and oxygen deficiency in (Pb,La)(Zr,Ti)O3 thin-film capacitors with La-Sr-Co-O electrodes

    International Nuclear Information System (INIS)

    Lee, J.; Ramesh, R.; Keramidas, V.G.; Warren, W.L.; Pike, G.E.; Evans, J.T. Jr.

    1995-01-01

    La-Sr-Co-O/Pb-La-Zr-Ti-O/La-Sr-Co-O thin-film capacitors have been grown in various oxygen ambients by pulsed laser deposition. As the oxygen ambient became more reducing, the capacitors developed more voltage asymmetry in hysteresis loops and a more preferred polarization state directed towards the top electrode. PLZT capacitors cooled in a fully oxidizing atmosphere (i.e., 1 atm oxygen pressure) exhibited nominally symmetric hysteresis loops and also showed little imprint both with and without fully saturating bias fields. We find that ambient oxygen pressure is an important process parameter and the imprint behavior is closely related with ambient oxygen induced effects such as oxygen vacancies, its related defect-dipole complexes and trapping of free charges. The different imprint behavior under negative and positive bias also suggests that the dipolar-defect complexes tend to cause imprint in PLZT capacitors

  13. Strontium metabolism and mechanism of interaction with mineralized tissues

    International Nuclear Information System (INIS)

    Wadkins, C.L.; Fu Peng, C

    1981-01-01

    This paper examines the administration of strontium to birds and mammals which results in limited incorporation into skeletal tissue, depressed intestinal calcium absorption, and development of rachitic bone lesions. Comparison of radiostrontium and radiocalcium incorporation by intact animals reveals discrimination against strontium in favor of calcium. Comparison of the Sr 85 - Ca 2+ and Ca 45 - Ca 2+ exchange reveals discrimination against strontium in favor of calcium. Thus, this system manifests product specificity, strontium inhibition, strontium exchange, and discrimination observed with intact animals

  14. Fixation of Radioactive Strontium in Soil

    DEFF Research Database (Denmark)

    Gregers-Hansen, Birte

    1964-01-01

    of the other long-lived fission products. Much work2–5 has, therefore, been concerned with the possibility of bringing down the strontium-90 uptake by plants through ploughing or through the addition of lime or fertilizer to the soil. Another factor, the effect of ageing on the availability of strontium, has...... been considered6,7. In general, these methods appear to be of little practical value, except for deep ploughing and the liming of acid soils, both of which will reduce the strontium uptake by a factor of 3–4....

  15. Ceria and strontium titanate based electrodes

    DEFF Research Database (Denmark)

    2010-01-01

    A ceramic anode structure obtainable by a process comprising the steps of: (a) providing a slurry by dispersing a powder of an electronically conductive phase and by adding a binder to the dispersion, in which said powder is selected from the group consisting of niobium-doped strontium titanate......, vanadium-doped strontium titanate, tantalum-doped strontium titanate, and mixtures thereof, (b) sintering the slurry of step (a), (c) providing a precursor solution of ceria, said solution containing a solvent and a surfactant, (d) impregnating the resulting sintered structure of step (b...

  16. Strontium clusters: electronic and geometry shell effects

    DEFF Research Database (Denmark)

    Lyalin, Andrey G.; Solov'yov, Ilia; Solov'yov, Andrey V.

    2008-01-01

    charged strontium clusters consisting of up to 14 atoms, average bonding distances, electronic shell closures, binding energies per atom, and spectra of the density of electronic states (DOS). It is demonstrated that the size-evolution of structural and electronic properties of strontium clusters...... is governed by an interplay of the electronic and geometry shell closures. Influence of the electronic shell effects on structural rearrangements can lead to violation of the icosahedral growth motif of strontium clusters. It is shown that the excessive charge essentially affects the optimized geometry...

  17. Sorption isolation of strontium from seawater

    International Nuclear Information System (INIS)

    Avramenko, V.A.; Zheleznov, V.V.; Kaplun, E.V.; Sokol'nitskaya, T.A.; Yukhkam, A.A.

    2001-01-01

    Sorption isolation of strontium from seawater is considered and prospects of use of selective adsorbents for purification of seawater or liquid radioactive wastes mixed with seawater from 90 Sr are discussed. Comparative analysis of sorptive properties of adsorbents of different nature is done. It is shown that sorption-reagent materials developed by authors can to afford effective separation of 90 Sr from seawater. Possible mechanism of strontium sorption by these adsorbents is considered. The prospect of their use for purification of liquid radioactive wastes from strontium is shown [ru

  18. Atom states and interatomic interactions in complex perovskite-like oxides. Communication XX. Origin of electron-ionic conductivity in lanthanum gallates doped with strontium and chromium

    International Nuclear Information System (INIS)

    Chezhina, N.V.; Zolotukhina, N.V.; Pijr, I.V.

    2006-01-01

    Magnetic susceptibilities and electric conductivities of solid solutions based on lanthanum gallate containing chromium and strontium atoms in the ratio of 10 : 2 were studied. It was shown that no partial oxidation of chromium to Cr(IV) occurs when lanthanum gallate is doped with chromium and strontium simultaneously, whereas the ionic conductivity is associated with the appearance of vacancies stabilized by chromium atoms in the oxygen sublattice [ru

  19. Strontium doped injectable bone cement for potential drug delivery applications.

    Science.gov (United States)

    Taha, Ali; Akram, Muhammad; Jawad, Zaidoon; Alshemary, Ammar Z; Hussain, Rafaqat

    2017-11-01

    Microwave assisted wet precipitation method was used to synthesize calcium deficient strontium doped β-tricalcium phosphate (Sr-βTCP) with a chemical formula of Ca 2.96-x Sr x (PO 4 ) 2 . Sr-βTCP was reacted with monocalcium phosphate monohydrate [Ca(H 2 PO 4 ) 2 .H 2 O, MCPM] in presence of water to furnish corresponding Sr containing brushite cement (Sr-Brc). The samples were characterized by using X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). Strontium content in the prepared samples was determined by using inductively coupled plasma optical emission spectrometry (ICP-OES). The effect of Sr 2+ ions on the structural, mechanical, setting properties and drug release of the cement is reported. Incorporation of Sr 2+ ions improved the injectability, setting time and mechanical properties of the Brc. The release profiles of antibiotics incorporated in Brc and Sr-Brc confirmed that the Sr incorporation into the Brc results in the efficient release of the antibiotics from the cement. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Separation of cesium and strontium with zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Kanno, T; Hashimoto, H [Tohoku Univ., Sendai (Japan). Research Inst. of Mineral Dressing and Metallurgy

    1976-06-01

    The basic studies of separation of cesium and strontium were made with specimens of zeolite, which are synthetic zeolites A, X and Y; synthetic mordenite; natural mordenite; and clinoptilolite. Ammonium chloride was used as eluent, because it was considered to be a most appropriate eluent in alkaline chlorides. Cesium was easily eluted from the zeolites A and X by ammonium chloride solution, but it was difficult to elute from the synthetic mordenite, natural mordenite and clinoptilolite by ammonium chloride solution, but it was difficult to elute from the zeolites A and X. The zeolite Y is the only one zeolite among these zeolites from which both of cesium and strontium were easily eluted by ammonium chloride solution. Strontium could be separated from cesium with zeolites by formation of Sr-EDTA chelate at pH above 11. In this process, cesium was only exchanged in zeolite column, but strontium flow out from it.

  1. Separation of cesium and strontium with zeolites

    International Nuclear Information System (INIS)

    Kanno, Takuji; Hashimoto, Hiroyuki

    1976-01-01

    The basic studies of separation of cesium and strontium were made with specimens of zeolite, which are synthetic zeolites A, X and Y; synthetic mordenite; natural mordenite; and clinoptilolite. Ammonium chloride was used as eluent, because it was considered to be a most appropriate eluent in alkaline chlorides. Cesium was easily eluted from the zeolites A and X by ammonium chloride solution, but it was difficult to elute from the synthetic mordenite, natural mordenite and clinoptilolite by ammonium chloride solution, but it was difficult to elute from the zeolites A and X. The zeolite Y is the only one zeolite among these zeolites from which both of cesium and strontium were easily eluted by ammonium chloride solution. Strontium could be separated from cesium with zeolites by formation of Sr-EDTA chelate at pH above 11. In this process, cesium was only exchanged in zeolite column, but strontium flow out from it. (auth.)

  2. Dielectric behaviour of strontium tartrate single crystals

    Indian Academy of Sciences (India)

    Unknown

    dielectric loss (tan δ) as functions of frequency and temperature. Ion core type ... Since the data on dielectric properties of strontium tartrate trihydrate (STT) do not ... through 'AE' make 15-amp dimmerstat, the rate of heating was maintained ...

  3. Hanford waste encapsulation: strontium and cesium

    International Nuclear Information System (INIS)

    Jackson, R.R.

    1976-06-01

    The strontium and cesium fractions separated from high radiation level wastes at Hanford are converted to the solid strontium fluoride and cesium chloride salts, doubly encapsulated, and stored underwater in the Waste Encapsulation and Storage Facility (WESF). A capsule contains approximately 70,000 Ci of 137 Cs or 70,000 to 140,000 Ci of 90 Sr. Materials for fabrication of process equipment and capsules must withstand a combination of corrosive chemicals, high radiation dosages and frequently, elevated temperatures. The two metals selected for capsules, Hastelloy C-276 for strontium fluoride and 316-L stainless steel for cesium chloride, are adequate for prolonged containment. Additional materials studies are being done both for licensing strontium fluoride as source material and for second generation process equipment

  4. Strontium Diibuprofenate Dihydrate, Strontium Malonate Sesquihydrate, Strontium Diascorbate Dihydrate and Strontium 2-Oxidobenzoate Hydrate at 120 K

    DEFF Research Database (Denmark)

    Stahl, Kenny; Andersen, Jens Enevold Thaulov; Cristgau, Stephan

    2006-01-01

    -sharing to form chains. The Sr coordination chains are packed into layers, which are stacked by van der Waals interactions. Poly[-aqua-diaquadi--malonato-distrontium(II)], [Sr2(C3H2O4)2(H2O)3]n, crystallizes with nine-coordinated Sr atoms three-dimensionally interconnected into a framework structure. One...... of the two crystallographically independent water molecules is located on a twofold axial site. catena-Poly[[diaqua(ascorbato)strontium(II)]--ascorbato], [Sr(C6H7O6)2(H2O)2]n, crystallizes with isolated eight-coordinated Sr polyhedra. One of the ascorbate ligands bridges two Sr atoms, forming zigzag...

  5. Determination of radioactive strontium in seawater

    International Nuclear Information System (INIS)

    Grahek, Zeljko; Rozmaric Macefat, Martina

    2005-01-01

    This paper describes the procedures of isolating strontium and yttrium from seawater that enable the determination of 89,90 Sr. In one procedure, strontium is directly isolated from seawater on the column filled with Sr resin by binding of strontium to the resin from 3 M HNO 3 in a seawater, and successive elution with HNO 3 . In others, strontium is precipitated from seawater with (NH 4 ) 2 CO 3 , followed by isolation on a Sr column or an anion exchange column. It is shown that strontium precipitation is optimal with concentration of 0.3 M (NH 4 ) 2 CO 3 at pH = 11. In these conditions, 100% Y, 78% Sr, 80% Ca and 50% Mg are precipitated. Strontium is bound on to Sr column from 5 to 8 M HNO 3 , separated from other elements by elution with 3 M HNO 3 and 0.05 M HNO 3 . Strontium and yttrium are bound on to anion exchange column from alcoholic solutions of nitric acid. The optimum mixture of alcohols for sample binding is a mixture of ethanol and methanol with the volume ratio 1:3. Strontium and yttrium are separated from Mg, Ca, K, and other elements by elution with 0.25 M HNO 3 in the mixture of ethanol and methanol. After the separation, yttrium and strontium are eluted from the column with water or methanol. In the procedure of direct isolation from 1 l of the sample, the average recovery of 50% was obtained. In the remaining two procedures, the strontium recovery was about 60% for the Sr column and 65% for anion exchange column. Recovery of yttrium is about 70% for the anion exchange column. It turned out that the procedure with the Sr resin (direct isolation and isolation after precipitation) is simpler and faster in the phase of the isolation on the column in comparison with the procedure with the anion exchanger. The procedure with the anion exchanger, however, enables the simultaneous isolation of yttrium and strontium and rapid determination of 89,90 Sr. These procedures were tested by determination of 89,90 Sr on liquid scintillation counter and Cherenkov

  6. Strontium-90 migration in Hanford sediments, USA

    International Nuclear Information System (INIS)

    Steefel, C.I.; Yang, L.; Carroll, S.A.; Roberts, S.; Zachara, J.M.; Yabusaki, S.B.

    2005-01-01

    Full text of publication follows: Strontium-90 is an important risk-driving contaminant at the Hanford site in eastern Washington, USA. Disposal operations at the Hanford 100-N area released millions of liters of reactor cooling water containing high concentrations of strontium-90 into the vadose zone immediately adjacent to the Columbia River. The effectiveness of pump-and-treat methods for remediation have been questioned, largely because the strontium is strongly sorbed on subsurface sediments via ion exchange reactions and co-precipitation in carbonates. In addition, groundwater monitoring wells show a fluctuating seasonal behavior in which high strontium-90 concentrations correlate with high Columbia River stage, even while average concentrations remain approximately constant. A series of fully saturated reactive transport column experiments have been conducted to investigate the important controls on strontium migration in Hanford groundwater [1]. The experiments were designed to investigate the multicomponent cation exchange behavior of strontium in competition with the cations Na + , Ca +2 , and Mg +2 , the concentration of which differs between river water and groundwater. Reactive transport modeling of the experiments indicates that the Sr +2 selectivity coefficient becomes larger with increasing NaNO 3 concentration, a behavior also shown by the divalent cations Ca +2 and Mg +2 . A new set of column experiments investigates the effect of wetting and drying cycles on strontium- 90 sorption and migration by considering episodic flow in Hanford sediments. In addition, the effect of fluctuating aquifer chemistry as a result of changes in the Columbia River stage on Sr +2 sorption is addressed. Modeling of multicomponent reactive transport under variably saturated conditions is used to interpret the results of the episodic flow/chemistry experiments. [1] Experimental and modeling studies of the migration behavior of strontium in Hanford sediments, USA. C

  7. Magnetoresistance Versus Oxygen Deficiency in Epi-stabilized SrRu1 - x Fe x O3 - δ Thin Films.

    Science.gov (United States)

    Dash, Umasankar; Acharya, Susant Kumar; Lee, Bo Wha; Jung, Chang Uk

    2017-12-01

    Oxygen vacancies have a profound effect on the magnetic, electronic, and transport properties of transition metal oxide materials. Here, we studied the influence of oxygen vacancies on the magnetoresistance (MR) properties of SrRu 1 - x Fe x O 3 - δ epitaxial thin films (x = 0.10, 0.20, and 0.30). For this purpose, we synthesized highly strained epitaxial SrRu 1 - x Fe x O 3 - δ thin films with atomically flat surfaces containing different amounts of oxygen vacancies using pulsed laser deposition. Without an applied magnetic field, the films with x = 0.10 and 0.20 showed a metal-insulator transition, while the x = 0.30 thin film showed insulating behavior over the entire temperature range of 2-300 K. Both Fe doping and the concentration of oxygen vacancies had large effects on the negative MR contributions. For the low Fe doping case of x = 0.10, in which both films exhibited metallic behavior, MR was more prominent in the film with fewer oxygen vacancies or equivalently a more metallic film. For semiconducting films, higher MR was observed for more semiconducting films having more oxygen vacancies. A relatively large negative MR (~36.4%) was observed for the x = 0.30 thin film with a high concentration of oxygen vacancies (δ = 0.12). The obtained results were compared with MR studies for a polycrystal of (Sr 1 - x La x )(Ru 1 - x Fe x )O 3 . These results highlight the crucial role of oxygen stoichiometry in determining the magneto-transport properties in SrRu 1 - x Fe x O 3 - δ thin films.

  8. Iodine Deficiency

    Science.gov (United States)

    ... Fax/Phone Home » Iodine Deficiency Leer en Español Iodine Deficiency Iodine is an element that is needed ... world’s population remains at risk for iodine deficiency. Iodine Deficiency FAQs WHAT IS THE THYROID GLAND? The ...

  9. Kinetics of isotopic exchange between strontium polymolybdate and strontium ions in aqueous solution

    International Nuclear Information System (INIS)

    Atun, Gulten; Bilgin, Binay; Kilislioglu, Ayben

    2002-01-01

    A heterogeneous isotopic exchange reaction of strontium polymolybdate in strontium chloride solution was studied using 90 Sr as a tracer. The effects of low and high strontium chloride concentration on the rate and mechanism of the isotopic exchange reaction were investigated. It was found that, at high concentrations, the rate is independent of strontium concentration, but, at low concentrations, the rate is proportional to the strontium concentration. These results support a hypothesis that, at low concentrations, the rate is controlled by film diffusion, whereas at high concentrations it is controlled by particle diffusion. Experiments were performed at 293, 303 and 313 K. Activation energy of isotopic exchange reaction and thermodynamic parameters ΔH*, ΔS*, and ΔG* were calculated using the Arrhenius and Eyring equations. The results also indicated that recrystallization is a predominant factor in the present exchange reaction

  10. Kinetics of isotopic exchange between strontium polymolybdate and strontium ions in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Atun, Gulten E-mail: gultena@istanbul.edu.tr; Bilgin, Binay; Kilislioglu, Ayben

    2002-06-01

    A heterogeneous isotopic exchange reaction of strontium polymolybdate in strontium chloride solution was studied using {sup 90}Sr as a tracer. The effects of low and high strontium chloride concentration on the rate and mechanism of the isotopic exchange reaction were investigated. It was found that, at high concentrations, the rate is independent of strontium concentration, but, at low concentrations, the rate is proportional to the strontium concentration. These results support a hypothesis that, at low concentrations, the rate is controlled by film diffusion, whereas at high concentrations it is controlled by particle diffusion. Experiments were performed at 293, 303 and 313 K. Activation energy of isotopic exchange reaction and thermodynamic parameters {delta}H*, {delta}S*, and {delta}G* were calculated using the Arrhenius and Eyring equations. The results also indicated that recrystallization is a predominant factor in the present exchange reaction.

  11. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Complications Undiagnosed or untreated iron-deficiency anemia may cause the following complications: Depression Heart problems. If you do not have enough hemoglobin-carrying red blood cells, your heart has to work harder to move oxygen-rich blood through your ...

  12. Electrical properties and thermal expansion of strontium aluminates

    Energy Technology Data Exchange (ETDEWEB)

    Zakharchuk, K.V. [Department of Materials and Ceramic Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Yaremchenko, A.A., E-mail: ayaremchenko@ua.pt [Department of Materials and Ceramic Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Fagg, D.P. [TEMA-NRD, Mechanical Engineering Department, University of Aveiro, 3810-193 Aveiro (Portugal)

    2014-11-15

    Highlights: • Sr{sub 3}Al{sub 2}O{sub 6}, SrAl{sub 2}O{sub 4} and Sr{sub 4}Al{sub 14}O{sub 25} ceramics are semiconductors. • Electrical conductivity is as low as 10{sup −6}−4×10{sup −5} S/cm at 1273 K in dry air. • SrAl{sub 2}O{sub 4} is a mixed conductor with predominant ionic conductivity. • Sr{sub 3}Al{sub 2}O{sub 6} shows significant contribution of protonic transport in wet atmospheres. • Average TECs vary in the range (8.5–11.1)×10{sup −6} K{sup −1} and are p(O{sub 2})-independent. - Abstract: Strontium aluminate ceramics, including Sr{sub 3}Al{sub 2}O{sub 6}, SrAl{sub 2}O{sub 4} and Sr{sub 4}Al{sub 14}O{sub 25}, synthesized by glycine–nitrate combustion and sintered at 1773 K in air, were characterized by thermal analysis, dilatometry and electrical measurements in controlled atmospheres. All studied strontium aluminates are semiconductors with electrical conductivities as low as 10{sup −6}−4×10{sup −5} S/cm at 1273 K in dry air. Electrical measurements in controlled atmospheres in combination with ion transference number determination demonstrated that SrAl{sub 2}O{sub 4} is a mixed conductor with predominant ionic conductivity and increasing n-type and p-type electronic contributions under highly reducing and oxidizing conditions, respectively. While the behavior of electrical conductivity of Sr{sub 3}Al{sub 2}O{sub 6} in dry atmospheres was qualitatively similar to that of SrAl{sub 2}O{sub 4}, a significant increase of conductivity in wet atmospheres was attributed to a protonic contribution to electrical conduction, in correlation with thermogravimetric data and the tendency of this material to form a hydrogarnet at low temperatures. The average thermal expansion coefficients of strontium aluminates, (8.5–11.1)×10{sup −6} K{sup −1} at 333–1373 K, increase with increasing strontium content in the sequence Sr{sub 4}Al{sub 14}O{sub 25} < SrAl{sub 2}O{sub 4} < Sr{sub 3}Al{sub 2}O{sub 6} and are essentially

  13. Amino acid-assisted synthesis of strontium hydroxyapatite bone ...

    Indian Academy of Sciences (India)

    Strontium-incorporated calcium phosphates show potential in biomedical application, particularly the doped stron- tium may ... shows that the addition of glycine plays an important role in reducing the particle size of strontium hydroxyapatite.

  14. Reduced-graphene-oxide-and-strontium-titanate-based double ...

    Indian Academy of Sciences (India)

    GO)/strontium titanate were pre- ... R-GO and strontium titanate were synthesized and characterized before ... Microwave absorption capabilities of the composite absorbers were investigated using a .... was backed with a conducting metal sheet.

  15. The oxygen deficient Ruddlesden-Popper La3Ni2O7-δ (δ = 0.65) phase: Structure and properties

    International Nuclear Information System (INIS)

    Poltavets, Viktor V.; Lokshin, Konstantin A.; Egami, Takeshi; Greenblatt, Martha

    2006-01-01

    La 3 Ni 2 O 7-δ (δ = 0.65) was synthesized by hydrogen reduction of the parent La 3 Ni 2 O 7 Ruddlesden-Popper nickelate. The crystal structure of La 3 Ni 2 O 6.35 (space group: I4/mmm, a = 3.8742 (1) A and c = 20.055 (1) A) has been determined from powder neutron diffraction data by the Rietveld method for the first time. The oxygen vacancies are located in the LaO x planes between two of the NiO 2 layers. Removal of these oxygen atoms from the parent phase results in a significant (∼0.4 A) shrinkage of the perovskite block along c-direction and splitting of the Ni position. The major part of Ni cations is surrounded by five oxygen atoms forming square pyramids, while the rest are coordinated to six octahedrally arranged oxygen atoms. Over the 170-400 K temperature range, the conductivity of La 3 Ni 2 O 6.35 follows Mott's variable range hopping model modified for a 2D case

  16. Direct observation of hopping induced spin polarization current in oxygen deficient Co-doped ZnO by Andreev reflection technique

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Kung-Shang; Huang, Tzu-Yu; Dwivedi, G.D. [Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan (China); Lin, Lu-Kuei; Lee, Shang-Fan [Taiwan Institute of Physics, Academia Sinica, Taipei, Taiwan (China); Sun, Shih-Jye [Department of Applied Physics, National Kaohsiung University, Kaohsiung, Taiwan (China); Chou, Hsiung, E-mail: hchou@mail.nsysu.edu.tw [Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan (China)

    2017-07-01

    Highlights: • Co-doped ZnO thin-films were grown with varying V{sub O} concentartion. • PCAR measurements were done to study the SPC. • High spin polarization was observed above a certain V{sub O} concentartion. • High V{sub O} samples provide a high density of completed percolation path. • This complete percolation path gives rise to high SPC. - Abstract: Oxygen vacancy induced ferromagnetic coupling in diluted magnetic oxide (DMO) semiconductors have been reported in several studies, but technologically more crucial spin-polarized current (SPC) is still under-developed in DMOs. Few studies have claimed that VRH mechanism can originate the SPC, but, how VRH mechanism associated with percolation path, is not clearly understood. We used Point-contact Andreev reflection (PCAR) technique to probe the SPC in Co-doped ZnO (CZO) films. Since the high resistance samples cause broadening in conductance(G)-voltage(V) curves, which may result in an unreliable evaluation of spin polarization, we include two extra parameters, (i) effective temperature and (ii) spreading resistance, for the simulation to avoid the uncertainty in extracting spin polarization. The effective G-V curves and higher spin polarization can be obtained above a certain oxygen vacancy concentration. The number of completed and fragmentary percolation paths is proportional to the concentration of oxygen vacancies. For low oxygen vacancy samples, the Pb-tip has a higher probability of covering fragmentary percolation paths than the complete ones, due to its small contact size. The completed paths may remain independent of one another and get polarized in different directions, resulting in lower spin-polarization value. High oxygen vacancy samples provide a high density of completed path, most of them link to one another by crossing over, and gives rise to high spin-polarization value.

  17. Measurement of strontium 90 in the rain fall-out

    International Nuclear Information System (INIS)

    Suratman; Soedyartomo; Suhartono.

    1976-01-01

    The procedure of radioactivity measurement of strontium 90 in the rain fallout as well as the measurement of the fallout gross beta activity have been studied. In the preliminary study strontium 90 is separated from other cations especially fission products by fuming nitric acid, and radioactivity measurement is carried out in the form of strontium oxalate. Data of radioactivity measurement of strontium 90 and the gross beta activity in the fallout are given. (author)

  18. Manganese deficiency in plants

    DEFF Research Database (Denmark)

    Schmidt, Sidsel Birkelund; Jensen, Poul Erik; Husted, Søren

    2016-01-01

    Manganese (Mn) is an essential plant micronutrient with an indispensable function as a catalyst in the oxygen-evolving complex (OEC) of photosystem II (PSII). Even so, Mn deficiency frequently occurs without visual leaf symptoms, thereby masking the distribution and dimension of the problem...... restricting crop productivity in many places of the world. Hence, timely alleviation of latent Mn deficiency is a challenge in promoting plant growth and quality. We describe here the key mechanisms of Mn deficiency in plants by focusing on the impact of Mn on PSII stability and functionality. We also address...... the mechanisms underlying the differential tolerance towards Mn deficiency observed among plant genotypes, which enable Mn-efficient plants to grow on marginal land with poor Mn availability....

  19. Strontium hydroxyapatite and strontium carbonate as templates for the precipitation of calcium-phosphates in the absence and presence of fluoride

    Science.gov (United States)

    Sternitzke, Vanessa; Janousch, Markus; Heeb, Michèle B.; Hering, Janet G.; Johnson, C. Annette

    2014-06-01

    The heterogeneous precipitation of calcium-phosphates on calcium hydroxyapatite (Ca10(PO4)6(OH)2 or HAP) in the presence and absence of fluoride is important in the formation of bone and teeth, protection against tooth decay, dental and skeletal fluorosis and defluoridation of drinking water. Strontium hydroxyapatite (Sr10(PO4)6(OH)2 or SrHAP) and strontium carbonate (SrCO3) were used as calcium-free seed templates in precipitation experiments conducted with varying initial calcium-to-phosphate (Ca/P) or calcium-to-phosphate-to-fluoride (Ca/P/F) ratios. Suspensions of SrHAP or SrCO3 seed templates (which were calcium-limited for both templates and phosphate-limited in the case of SrCO3) were reacted at pH 7.3 (25 °C) over 3 days. The resulting solids were examined with Scanning Transmission Electron Microscopy (STEM), X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), and X-ray Photoelectron Spectroscopy (XPS), X-ray Absorption Near Edge Structure (XANES), and Extended X-ray Absorption Fine Structure spectroscopy (EXAFS). Calcium apatite was the predominant phase identified by all techniques independent of the added Ca/P ratios and of the presence of fluoride. It was not possible to make an unambiguous distinction between HAP and fluorapatite (Ca10(PO4)6F2, FAP). The apatite was calcium-deficient and probably contained some strontium.

  20. Distribution of strontium in milk component

    International Nuclear Information System (INIS)

    Rosskopfova, O.; Galambos, M.; Rajec, P.

    2011-01-01

    The distribution of strontium between the milk components, i.e., serum, casein micelles, whey and hydroxyapatite was determined. The sorption on hydroxyapatite was investigated using batch method and radiotracer technique. The aqueous phase comprised of either milk or whey. The sorption of strontium on hydroxyapatite depended on the method of its preparation and on the composition of the aqueous phase. The sorption of strontium was increased with an increase of pH. The presence of citrate species resulted in decrease of the sorption of strontium on hydroxyapatite. The sorption of 85 Sr on hydroxyapatite decreased with the increasing concentration of Ca 2+ ions. Addition of Ca 2+ ions to milk resulted in milk pH decrease. The decrease in pH value after calcium addition to milk is related to exchanges between added calcium and micellar H + . The average value of strontium sorption on casein micelles in milk with presence of hydroxyapatite was (47.3 ± 5.6) %. The average value of sorption of 85 Sr on casein micelles in milk without the addition of hydroxyapatite was (68.9 ± 2.2) %. (author)

  1. Growth and characterization of pure and lithium doped strontium ...

    Indian Academy of Sciences (India)

    TECS

    Abstract. The effect of lithium ion as dopant on the size and transparency of strontium tartrate tetrahydrate. (SrC4H4O6⋅4H2O) crystals are presented in this paper. Growth of single crystals of undoped and lithium doped strontium tartrate tetrahydrate by controlled diffusion of strontium nitrate into the gel charged with.

  2. Growth of strontium oxalate crystals in agar–agar gel

    Indian Academy of Sciences (India)

    Growth of strontium oxalate crystals in agar–agar gel. P V DALAL. ∗ and K B SARAF. Postgraduate Department of Physics, Pratap College, Amalner 425 401, India. MS received 16 March 2008; revised 5 April 2010. Abstract. Single crystals of strontium oxalate have been grown by using strontium chloride and oxalic acid in.

  3. Rapid determination of strontium-89 and strontium-90 in food and environmental samples by Cerenkov counting

    International Nuclear Information System (INIS)

    Melin, Judith; Suomela, Jorma

    1995-01-01

    The method has been developed for emergency situations. Minimum detectable concentrations of 5 Bq/liter, kilogram of strontium-89 and strontium-90 respectively is achievable in the presence of nuclides considered to be released under accidental conditions. Result on the strontium-89 and strontium-90 content in a sample can be obtained within 12 hours. One technician can easily handle 8-10 samples during a working day of eight hours. The determination of the strontium isotopes is accomplished by monitoring the Cerenkov radiation from strontium-89 and yttrium-90 in a liquid scintillation counter. The latter is the daughter product of strontium-90. Prior to the Cerenkov counting the sample is separated from interfering nuclides by oxalate precipitation, chromate precipitation and HDEHP-extraction. The method has to be further improved and evaluated with respect to different soil types such as forest mineral soil layers, agricultural soils and pastures. Furthermore, the decontamination procedure should be evaluated for a sample containing freshly irradiated uranium. (author)

  4. Anion and cation diffusion in barium titanate and strontium titanate

    International Nuclear Information System (INIS)

    Kessel, Markus Franz

    2012-01-01

    Perovskite oxides show various interesting properties providing several technical applications. In many cases the defect chemistry is the key to understand and influence the material's properties. In this work the defect chemistry of barium titanate and strontium titanate is analysed by anion and cation diffusion experiments and subsequent time-of-flight secondary ion mass spectrometry (ToF-SIMS). The reoxidation equation for barium titanate used in multi-layer ceramic capacitors (MLCCs) is found out by a combination of different isotope exchange experiments and the analysis of the resulting tracer diffusion profiles. It is shown that the incorporation of oxygen from water vapour is faster by orders of magnitude than from molecular oxygen. Chemical analysis shows the samples contain various dopants leading to a complex defect chemistry. Dysprosium is the most important dopant, acting partially as a donor and partially as an acceptor in this effectively acceptor-doped material. TEM and EELS analysis show the inhomogeneous distribution of Dy in a core-shell microstructure. The oxygen partial pressure and temperature dependence of the oxygen tracer diffusion coefficients is analysed and explained by the complex defect chemistry of Dy-doped barium titanate. Additional fast diffusion profiles are attributed to fast diffusion along grain boundaries. In addition to the barium titanate ceramics from an important technical application, oxygen diffusion in cubic, nominally undoped BaTiO 3 single crystals has been studied by means of 18 O 2 / 16 O 2 isotope exchange annealing and subsequent determination of the isotope profiles in the solid by ToF-SIMS. It is shown that a correct description of the diffusion profiles requires the analysis of the diffusion through the surface space-charge into the material's bulk. Surface exchange coefficients, space-charge potentials and bulk diffusion coefficients are analysed as a function of oxygen partial pressure and temperature. The

  5. The performance of spinel bulk-like oxygen-deficient CoGa2O4 as an air-cathode catalyst in microbial fuel cell

    Science.gov (United States)

    Liu, Di; Mo, Xiaoping; Li, Kexun; Liu, Yi; Wang, Junjie; Yang, Tingting

    2017-08-01

    Nano spinel bulk-like CoGa2O4 prepared via a facile hydrothermal method is used as a high efficient electrochemical catalyst in activated carbon (AC) air-cathode microbial fuel cell (MFC). The maximum power density of the modified MFC is 1911 ± 49 mW m-2, 147% higher than the MFC of untreated AC cathode. Transmission electron microscope (TEM) and X-ray diffraction (XRD) exhibit the morphology and crystal structure of CoGa2O4. Rotating disk electrode (RDE) confirms the four-electron pathway at the cathode during the oxygen reduction reaction (ORR). Thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) illustrate that the high rate oxygen vacancy exist in the CoGa2O4. The oxygen vacancy of CoGa2O4 plays an important role in catalytic activity. In a word, the prepared nano spinel bulk-like CoGa2O4 provides an alternative to the costly Pt in air-cathode for power output.

  6. Health Deficiencies

    Data.gov (United States)

    U.S. Department of Health & Human Services — A list of all health deficiencies currently listed on Nursing Home Compare, including the nursing home that received the deficiency, the associated inspection date,...

  7. Strontium and fluorine in tuatua shells

    International Nuclear Information System (INIS)

    Trompetter, W.J.; Coote, G.E.

    1993-01-01

    This report describes the research to date on the elemental distributions of strontium, calcium, and fluorine in a collection of 24 tuatua shells (courtesy of National Museum). Variations in elemental concentrations were measured in the shell cross-sections using a scanning proton microprobe (PIXE and PIGME). In this paper we report the findings to date, and present 2-D measurement scans as illustrative grey-scale pictures. Our results support the hypothesis that increased strontium concentrations are deposited in the shells during spawning, and that fluorine concentration is proportional to growth rate. (author). 15 refs.; 13 figs.; 1 appendix

  8. Printed Barium Strontium Titanate capacitors on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Sette, Daniele [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Luxembourg Institute of Science and Technology LIST, Materials Research and Technology Department, L-4422 Belvaux (Luxembourg); Kovacova, Veronika [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Defay, Emmanuel, E-mail: emmanuel.defay@list.lu [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Luxembourg Institute of Science and Technology LIST, Materials Research and Technology Department, L-4422 Belvaux (Luxembourg)

    2015-08-31

    In this paper, we show that Barium Strontium Titanate (BST) films can be prepared by inkjet printing of sol–gel precursors on platinized silicon substrate. Moreover, a functional variable capacitor working in the GHz range has been made without any lithography or etching steps. Finally, this technology requires 40 times less precursors than the standard sol–gel spin-coating technique. - Highlights: • Inkjet printing of Barium Strontium Titanate films • Deposition on silicon substrate • Inkjet printed silver top electrode • First ever BST films thinner than 1 μm RF functional variable capacitor that has required no lithography.

  9. Surface adsorption in strontium chloride ammines

    DEFF Research Database (Denmark)

    Ammitzbøll, Andreas L.; Lysgaard, Steen; Klukowska, Agata

    2013-01-01

    An adsorbed state and its implications on the ab- and desorption kinetics of ammonia in strontium chloride ammine is identified using a combination of ammonia absorption measurements, thermogravimetric analysis, and density functional theory calculations. During thermogravimetric analysis, ammonia...... desorption originating from the adsorbed state is directly observed below the bulk desorption temperature, as confirmed by density functional theory calculations. The desorption enthalpy of the adsorbed state of strontium chloride octa-ammine is determined with both techniques to be around 37-39 k...

  10. Implanted strontium titanate single crystals for energy storage applications

    Energy Technology Data Exchange (ETDEWEB)

    Stoeber, Max; Cherkouk, Charaf; Walter, Juliane; Strohmeyer, Ralph; Leisegang, Tilmann; Meyer, Dirk Carl [TU Bergakademie, Freiberg (Germany); Schelter, Matthias; Zosel, Jens [Kurt Schwabe Institute, Meinsberg (Germany); Prucnal, Slawomir [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf (Germany)

    2016-07-01

    A rapid increase of the demand on efficient energy storage solutions requires new approaches beyond the Li-ion technology. In particular, metal-air batteries as well as solid-state fuel cells offer a great potential for high-energy-density storage devices. Since the efficiency of such devices is significantly limited by the activation of both the oxygen reduction reaction (ORR) and the ionic and electronic conductivities, an adequate porosity as well as a controlled doping are required. The ion implantation is a key technology to achieve this goal. In this work, p- and n-doped strontium titanate (SrTiO{sub 3}) single crystals were used as oxidic materials. The oxygen exchange kinetics as well as the structural changes of the SrTiO{sub 3} crystal surface induced by the ion implantation were investigated. On one hand, the depth profile of dopant concentration and dopant valence state were determined using sputtered X-ray photoelectron spectroscopy (XPS). On the other hand, the overall oxygen exchange kinetic of the implanted SrTiO{sub 3} crystal was quantitatively described by means of coulometric titration using Zirox system (ZIROX GmbH, Germany). Furthermore, the surface morphology of the samples was investigated using atomic force microscopy (AFM).

  11. Understanding the defect chemistry of alkali metal strontium silicate solid solutions: insights from experiment and theory

    KAUST Repository

    Bayliss, Ryan D.; Cook, Stuart N.; Scanlon, David O.; Fearn, Sarah; Cabana, Jordi; Greaves, Colin; Kilner, John A.; Skinner, Stephen J.

    2014-01-01

    © the Partner Organisations 2014. Recent reports of remarkably high oxide ion conduction in a new family of strontium silicates have been challenged. It has recently been demonstrated that, in the nominally potassium substituted strontium germanium silicate material, the dominant charge carrier was not the oxygen ion, and furthermore that the material was not single phase (R. D. Bayliss et. al., Energy Environ. Sci., 2014, DOI: 10.1039/c4ee00734d). In this work we re-investigate the sodium-doped strontium silicate material that was reported to exhibit the highest oxide ion conductivity in the solid solution, nominally Sr0.55Na0.45SiO2.775. The results show lower levels of total conductivity than previously reported and sub-micron elemental mapping demonstrates, in a similar manner to that reported for the Sr0.8K0.2Si0.5Ge0.5O2.9 composition, an inhomogeneous chemical distribution correlating with a multiphase material. It is also shown that the conductivity is not related to protonic mobility. A density functional theory computational approach provides a theoretical justification for these new results, related to the high energetic costs associated with oxygen vacancy formation. This journal is

  12. Understanding the defect chemistry of alkali metal strontium silicate solid solutions: insights from experiment and theory

    KAUST Repository

    Bayliss, Ryan D.

    2014-09-24

    © the Partner Organisations 2014. Recent reports of remarkably high oxide ion conduction in a new family of strontium silicates have been challenged. It has recently been demonstrated that, in the nominally potassium substituted strontium germanium silicate material, the dominant charge carrier was not the oxygen ion, and furthermore that the material was not single phase (R. D. Bayliss et. al., Energy Environ. Sci., 2014, DOI: 10.1039/c4ee00734d). In this work we re-investigate the sodium-doped strontium silicate material that was reported to exhibit the highest oxide ion conductivity in the solid solution, nominally Sr0.55Na0.45SiO2.775. The results show lower levels of total conductivity than previously reported and sub-micron elemental mapping demonstrates, in a similar manner to that reported for the Sr0.8K0.2Si0.5Ge0.5O2.9 composition, an inhomogeneous chemical distribution correlating with a multiphase material. It is also shown that the conductivity is not related to protonic mobility. A density functional theory computational approach provides a theoretical justification for these new results, related to the high energetic costs associated with oxygen vacancy formation. This journal is

  13. Effect of annealing temperature on the structural, photoluminescence and magnetic properties of sol-gel derived Magnetoplumbite-type (M-type) hexagonal strontium ferrite

    International Nuclear Information System (INIS)

    Teh, Geok Bee; Wong, Yat Choy; Tilley, Richard D.

    2011-01-01

    Magnetoplumbite-type (M-type) hexagonal strontium ferrite particles were synthesized via sol-gel technique employing ethylene glycol as the gel precursor at two different calcination temperatures (800 and 1000 deg. C). Structural properties were systematically investigated via X-ray diffraction (XRD), field emission scanning electron microscopy, high resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), photoluminescence spectrophotometry and superconducting quantum interference device magnetometer. XRD results showed that the sample synthesized at 1000 deg. C was of single-phase with a space group of P6 3 /mmc and lattice cell parameter values of a=5.882 A and c=23.048 A. EDS confirmed the composition of strontium ferrite calcined at 1000 deg. C being mainly of M-type SrFe 12 O 19 with HRTEM micrographs confirming the ferrites exhibiting M-type long range ordering along the c-axis of the crystal structure. The photoluminescence (PL) property of strontium ferrite was examined at excitation wavelengths of 260 and 270 nm with significant PL emission peaks centered at 350 nm being detected. Strontium ferrite annealed at higher temperature (1000 deg. C) was found to have grown into larger particle size, having higher content of oxygen vacancies and exhibited 83-85% more intense PL. Both the as-prepared strontium ferrites exhibited significant oxygen vacancies defect structures, which were verified via TGA. Higher calcination temperature turned strontium ferrite into a softer ferrite. - Highlights: → High annealing temperature produced M-type ferrite with higher oxygen vacancies. → Photoluminescence intensity is proportional to the existence of oxygen vacancies. → XRD data showed cell contraction well suited to the change of oxygen vacancies. → Shift in hysteresis loop due to defect-induced exchange bias was observed.

  14. Effect of annealing temperature on the structural, photoluminescence and magnetic properties of sol-gel derived Magnetoplumbite-type (M-type) hexagonal strontium ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Teh, Geok Bee, E-mail: sharonteh2009@gmail.com [Division of Bioscience and Chemistry, School of Arts and Science, Tunku Abdul Rahman College, Jalan Genting Kelang, 53300 Kuala Lumpur (Malaysia); Wong, Yat Choy [Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, PO Box 218, Hawthorn, Victoria 3122 (Australia); Tilley, Richard D. [School of Chemical and Physical Sciences, MacDiarmid Institute of Advanced Materials and Nanotechnology, Victoria University of Wellington, PO Box 600, Wellington (New Zealand)

    2011-09-15

    Magnetoplumbite-type (M-type) hexagonal strontium ferrite particles were synthesized via sol-gel technique employing ethylene glycol as the gel precursor at two different calcination temperatures (800 and 1000 deg. C). Structural properties were systematically investigated via X-ray diffraction (XRD), field emission scanning electron microscopy, high resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), photoluminescence spectrophotometry and superconducting quantum interference device magnetometer. XRD results showed that the sample synthesized at 1000 deg. C was of single-phase with a space group of P6{sub 3}/mmc and lattice cell parameter values of a=5.882 A and c=23.048 A. EDS confirmed the composition of strontium ferrite calcined at 1000 deg. C being mainly of M-type SrFe{sub 12}O{sub 19} with HRTEM micrographs confirming the ferrites exhibiting M-type long range ordering along the c-axis of the crystal structure. The photoluminescence (PL) property of strontium ferrite was examined at excitation wavelengths of 260 and 270 nm with significant PL emission peaks centered at 350 nm being detected. Strontium ferrite annealed at higher temperature (1000 deg. C) was found to have grown into larger particle size, having higher content of oxygen vacancies and exhibited 83-85% more intense PL. Both the as-prepared strontium ferrites exhibited significant oxygen vacancies defect structures, which were verified via TGA. Higher calcination temperature turned strontium ferrite into a softer ferrite. - Highlights: > High annealing temperature produced M-type ferrite with higher oxygen vacancies. > Photoluminescence intensity is proportional to the existence of oxygen vacancies. > XRD data showed cell contraction well suited to the change of oxygen vacancies. > Shift in hysteresis loop due to defect-induced exchange bias was observed.

  15. Observation of the strain-driven charge-ordered state in La sub 0 sub . sub 7 sub C a sub 0 sub . sub 3 MnO sub 3 sub - sub d elta thin film with oxygen deficiency

    CERN Document Server

    Prokhorov, V G; Kaminsky, G G; Svetchnikov, V L; Zandbergen, H W; Lee, Y P; Park, J S; Kim, K W

    2003-01-01

    The magnetic and transport properties of La sub 0 sub . sub 7 Ca sub 0 sub . sub 3 MnO sub 3 sub - sub d elta films with an oxygen deficiency (delta approx 0.1) and a La sub 0 sub . sub 9 Ca sub 0 sub . sub 1 MnO sub 3 film with the stoichiometric oxygen content are investigated in a wide temperature range. It is shown that the charge-ordered insulating (COI) state is observed for a La sub 0 sub . sub 7 Ca sub 0 sub . sub 3 MnO sub 2 sub . sub 9 film with thickness d <= 30 nm, which manifests mainly a cubic crystal structure with an anomalously small lattice parameter for this composition. An increase in the film thickness (d approx 60 nm) leads to a structural transition from the lattice-strained cubic to the relaxed rhombohedral phase, is accompanied by a shift of the Curie point (T sub C) to lower temperature and a frustration of the COI state. The magnetic and transport properties of the La sub 0 sub . sub 7 Ca sub 0 sub . sub 3 MnO sub 2 sub . sub 9 film with d approx 60 nm are similar to those exhibi...

  16. Deposition of strontium and calcium in snail shell

    Energy Technology Data Exchange (ETDEWEB)

    Rosenthal, Jr, G M; Nelson, D J; Gardiner, D A

    1965-07-03

    The relative effects of strontium and calcium concentrations in the environment on their uptake and incorporation into snail shell were investigated. /sup 45/Ca and /sup 85/Sr were used as tracers and specific activities were used to determine deposition. Data are presented in tables and graphs. Deposition of both calcium and strontium in the snail shell depended primarily on the respective concentrations of these elements in the immediate environment. A slight effect of strontium on calcium deposition was observed. There was found to be a minimum strontium deposition for various combinations of strontium and calcium in the environment. It was concluded that strontium uptake is more closely associated with environmental strontium concentrations than with calcium concentrations.

  17. Measurement of strontium-89 and strontium-90 in environmental waters. A tentative reference method

    International Nuclear Information System (INIS)

    1976-03-01

    A tentative reference method for the measurement of 89 Sr and 90 Sr in environmental waters is described. Samples of environmental water sources are collected, preserved with acid-strontium carrier, and analyzed for 89 Sr and/or 90 Sr. The isotopes are separated from the sample water by precipitating with stable strontium carrier as carbonate. The strontium carbonate is dissolved, 90 Sr separated, the strontium reprecipitated as carbonate, filtered, and counted for the combined 89 Sr and 90 Sr activity. The 90 y is allowed to grow in from the 90 y activity; the strontium carbonate is redissolved; the 90 y is separated, precipitated, and counted for the 90 Sr determination. The 89 Sr activity is then determined by difference of the total 89 Sr and 90 y and the separate 90 Sr activities. Recoveries are determined from the added and found (recovered) strontium carrier. Counting efficiencies are determined with prepared standard reference samples. Results are reported in pCi/liter

  18. Calcium and Strontium in Swedish Waters and Fish, and Accumulation of Strontium-90

    Energy Technology Data Exchange (ETDEWEB)

    Agnedal, P O

    1966-04-15

    The purpose of this study has been to investigate the correlation between calcium and strontium in fish in relation to the concentration of these elements in the water. An investigation of the uptake of strontium-90 has also been made and permissible levels of strontium-90 in the water is calculated based upon the uptake in fish muscle tissues. Lakes with calcium concentrations between 2 - 63 mg/l have been studied and samples from the Baltic coastal water are also included. Three fish species are studied, viz. pike (Esox lucius (L.)), perch (Perca fluviatilis (L.)) and roach (Leuciscus rutilus (L.)). Bones, muscle tissues and skin + scales have been analysed. Strontium-90 measurements have been made showing an increase in both water and fish. Calculations show that in water with about 2 mg Ca/l a 10-fold increase of the existing strontium-90 level might give strontium-90 concentrations in fish muscle tissues close to what is permissible. In lakes with calcium concentrations 20 - 40 mg/l the permissible levels for drinking water will be exceeded before the fish consumption would have to be restricted.

  19. Calcium and Strontium in Swedish Waters and Fish, and Accumulation of Strontium-90

    International Nuclear Information System (INIS)

    Agnedal, P.O.

    1966-04-01

    The purpose of this study has been to investigate the correlation between calcium and strontium in fish in relation to the concentration of these elements in the water. An investigation of the uptake of strontium-90 has also been made and permissible levels of strontium-90 in the water is calculated based upon the uptake in fish muscle tissues. Lakes with calcium concentrations between 2 - 63 mg/l have been studied and samples from the Baltic coastal water are also included. Three fish species are studied, viz. pike (Esox lucius (L.)), perch (Perca fluviatilis (L.)) and roach (Leuciscus rutilus (L.)). Bones, muscle tissues and skin + scales have been analysed. Strontium-90 measurements have been made showing an increase in both water and fish. Calculations show that in water with about 2 mg Ca/l a 10-fold increase of the existing strontium-90 level might give strontium-90 concentrations in fish muscle tissues close to what is permissible. In lakes with calcium concentrations 20 - 40 mg/l the permissible levels for drinking water will be exceeded before the fish consumption would have to be restricted

  20. Resonant double photoionisation spectroscopy of strontium

    Energy Technology Data Exchange (ETDEWEB)

    Sokell, E; Grimm, M; Sheridan, P, E-mail: emma.sokell@ucd.i, E-mail: paul.sheridan@ucd.i [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland)

    2009-11-01

    Resonant triple-differential cross-section (TDCS) measurements on atomic strontium on the 4p {yields} 4d resonance are presented. All of these TDCS measurements display unexpected lobes at a mutual emission angle for the two electrons of 180{sup o}. Possible explanations for these lobes are explored.

  1. Strontium Removal: Full-Scale Ohio Demonstrations

    Science.gov (United States)

    The objectives of this presentation are to present a brief overview of past bench-scale research to evaluate the impact lime softening on strontium removal from drinking water and present full-scale drinking water treatment studies to impact of lime softening and ion exchange sof...

  2. The coprecipitation of strontium with hydroxyapatite

    International Nuclear Information System (INIS)

    Fujino, Osamu

    1975-01-01

    The distribution behavior of the strontium ion between hydroxyapatite and the parent solution was investigated. The hydroxyapatite was formed by the extremely slow addition of diammonium hydrogenphosphate to solutions of calcium and strontium nitrate buffered with ethylenediamine at 80 0 C. The precipitate yielded a typical X-ray diffraction pattern of hydroxyapatite and had a composition in which the Ca/P molar ratio was 1.67 at pH 6.80. The strontium ion was coprecipitated in the apatite, obeying the Doerner and Hoskins logarithnmic distribution law. The distribution coefficient was scarcely affected by the strontium concentration on the pH value in the parent solution, and had a value of 0.26+-0.02 at 80 0 C. On the other hand, the apparent distribution coefficient was a little affected by such organic anions as acetate, citrate, lactate, glycinate, and glutamate ions. The lattice constants of the precipitates prepared in the research were measured in order to confirm the formation of the solid solutions. (auth.)

  3. Cesium and Strontium Separation Technologies Literature Review

    Energy Technology Data Exchange (ETDEWEB)

    T. A. Todd; T. A. Todd; J. D. Law; R. S. Herbst

    2004-03-01

    Integral to the Advanced Fuel Cycle Initiative (AFCI) Program’s proposed closed nuclear fuel cycle, the fission products cesium and strontium in the dissolved spent nuclear fuel stream are to be separated and managed separately. A comprehensive literature survey is presented to identify cesium and strontium separation technologies that have the highest potential and to focus research and development efforts on these technologies. Removal of these high-heat-emitting fission products reduces the radiation fields in subsequent fuel cycle reprocessing streams and provides a significant short-term (100 yr) heat source reduction in the repository. This, along with separation of actinides, may provide a substantial future improvement in the amount of fuel that could be stored in a geologic repository. The survey and review of the candidate cesium and strontium separation technologies are presented herein. Because the AFCI program intends to manage cesium and strontium together, technologies that simultaneously separate both elements are of the greatest interest, relative to technologies that separate only one of the two elements.

  4. Strontium ranelate in the treatment of osteoporosis

    African Journals Online (AJOL)

    2006-11-05

    Nov 5, 2006 ... postmenopausal women (mean age 69 years) with osteoporosis or osteopenia. Strontium ranelate significantly decreased markers of bone resorption and increased biomarkers of formation. Spinal BMD increased by 14%, while vertebral fractures decreased by 49% within the first year, a reduction that was.

  5. Redox transitions in strontium vanadates: Electrical conductivity and dimensional changes

    International Nuclear Information System (INIS)

    Macías, J.; Yaremchenko, A.A.; Frade, J.R.

    2014-01-01

    Highlights: • Electrical conductivity and thermal expansion of strontium vanadates are measured. • Conductivity of SrVO 3−δ is 10 6 –10 8 times higher compared to Sr 2 V 2 O 7 and Sr 3 V 2 O 8 . • Sr 2 V 2 O 7 transforms on reduction to SrVO 3−δ via (5Sr 3 V 2 O 8 + SrV 6 O 11 ) intermediate. • This process is kinetically stagnated due to good redox stability of Sr 3 V 2 O 8 . • Large volume changes on Sr 2 V 2 O 7 ↔ SrVO 3 transformation are confirmed by dilatometry. - Abstract: The reversibility of redox-induced phase transformations and accompanying electrical conductivity and dimensional changes in perovskite-type SrVO 3−δ , a parent material for a family of potential solid oxide fuel cell anode materials, were evaluated employing X-ray diffraction, thermal analysis, dilatometry and electrical measurements. At 873–1273 K, the electrical conductivity of SrVO 3−δ is metallic-like and 6–8 orders of magnitude higher compared to semiconducting V 5+ -based strontium pyrovanadate Sr 2 V 2 O 7 and strontium orthovanadate Sr 3 V 2 O 8 existing under oxidizing conditions. SrVO 3−δ is easily oxidized to a pyrovanadate phase at atmospheric oxygen pressure. Inverse reduction in 10%H 2 –90%N 2 atmosphere occurs in two steps through (5Sr 3 V 2 O 8 + SrV 6 O 11 ) intermediate. As Sr 3 V 2 O 8 is relatively stable even under reducing conditions, the perovskite phase and its high level of electrical conductivity cannot be recovered completely in a reasonable time span at temperatures ⩽1273 K. Dilatometric studies confirmed that SrVO 3 ↔ Sr 2 V 2 O 7 redox transformation is accompanied with significant dimensional changes. Their extent depends on the degree of phase conversion and, apparently, on microstructural features

  6. Effects of calcium and magnesium on strontium distribution coefficients

    Science.gov (United States)

    Bunde, R.L.; Rosentreter, J.J.; Liszewski, M.J.; Hemming, C.H.; Welhan, J.

    1997-01-01

    The effects of calcium and magnesium on the distribution of strontium between a surficial sediment and simulated wastewater solutions were measured as part of an investigation to determine strontium transport properties of surficial sediment at the Idaho National Engineering Laboratory (INEL), Idaho. The investigation was conducted by the U.S. Geological Survey and Idaho State University, in cooperation with the U.S. Department of Energy. Batch experimental techniques were used to determine strontium linear sorption isotherms and distribution coefficients (K(d)'s) using simulated wastewater solutions prepared at pH 8.0??0.1 with variable concentrations of calcium and magnesium. Strontium linear sorption isotherm K(d)'s ranged from 12??1 to 85??3 ml/g, increasing as the concentration of calcium and magnesium decreased. The concentration of sorbed strontium and the percentage of strontium retained by the sediment were correlated to aqueous concentrations of strontium, calcium, and magnesium. The effect of these cation concentrations on strontium sorption was quantified using multivariate least-squares regression techniques. Analysis of data from these experiments indicates that increased concentrations of calcium and magnesium in wastewater discharged to waste disposal ponds at the INEL increases the availability of strontium for transport beneath the ponds by decreasing strontium sorption to the surficial sediment.

  7. Enhancing photocatalytic CO{sub 2} reduction by coating an ultrathin Al{sub 2}O{sub 3} layer on oxygen deficient TiO{sub 2} nanorods through atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Huilei; Chen, Jiatang; Rao, Guiying; Deng, Wei; Li, Ying, E-mail: yingli@tamu.edu

    2017-05-15

    Highlights: • Oxygen deficient TiO{sub 2} anatase nanorods are coated with an ultrathin Al{sub 2}O{sub 3} layer by ALD. • Exposed {100} facets and oxygen vacancies promote CO{sub 2} photoreduction to CO and CH{sub 4}. • Al{sub 2}O{sub 3} overlayer passivates surface states and mitigates surface charge recombination. • Two cycles of ALD coating lead to maximum photocatalytic CO{sub 2} reduction. • More than five cycles of ALD coating prohibits electron transfer to the surface. - Abstract: In this work, anatase nanorods (ANR) of TiO{sub 2} with active facet {100} as the major facet were successfully synthesized, and reducing the ANR by NaBH{sub 4} led to the formation of gray colored oxygen deficient TiO{sub 2-x} (ReANR). On the surface of ReANR, a thin layer of Al{sub 2}O{sub 3} was deposited using atomic layer deposition (ALD), and the thickness of Al{sub 2}O{sub 3} varied by the number of ALD cycles (1, 2, 5, 10, 50, 100, or 200). The growth rate of Al{sub 2}O{sub 3} was determined to be 0.25 Å per cycle based on high-resolution TEM analysis, and the XRD result showed the amorphous structure of Al{sub 2}O{sub 3}. All the synthesized photocatalysts (ANR, ReANR, and Al{sub 2}O{sub 3} coated ReANR) were tested for CO{sub 2} photocatalytic reduction in the presence of water vapor, with CO detected as the major reduction product and CH{sub 4} as the minor product. Compared with ANR, ReANR had more than 50% higher CO production and more than ten times higher CH{sub 4} production due to the oxygen vacancies that possibly enhanced CO{sub 2} adsorption and activation. By applying less than 5 cycles of ALD, the Al{sub 2}O{sub 3} coated ReANR had enhanced overall production of CO and CH{sub 4} than uncoated ReANR, with 2 cycles being the optimum, about 40% higher overall production than ReANR. Whereas, both CO and CH{sub 4} production decreased with increasing number of ALD cycles when more than 5 cycles were applied. Photoluminescence (PL) analysis showed an

  8. Iodine Deficiency

    NARCIS (Netherlands)

    Zimmermann, M.B.

    2009-01-01

    Iodine deficiency has multiple adverse effects in humans, termed iodine deficiency disorders, due to inadequate thyroid hormone production. Globally, it is estimated that 2 billion individuals have an insufficient iodine intake, and South Asia and sub-Saharan Africa are particularly affected.

  9. Isomorfic Substitutions of Calcium by Strontium in Calcium Hydroxyapatite

    International Nuclear Information System (INIS)

    Christensen, Hilbert

    1962-12-01

    By means of homogeneous precipitation it has been possible to synthesize crystalline solid solutions of calcium strontium hydroxyapatite from aqueous solutions. The lattice constants for the solid solutions were measured in the range Ca 9 Sr(PO 4 ) 6 (OH) 2 - CaSr 9 (PO 4 ) 6 (OH) 2 . The investigations show that the discrimination of strontium against calcium is considerably smaller than reported elsewhere (1). Strontium is preferentially built into the c-axis direction of the apatite lattice

  10. Strontium isotopic study of sediment from the Ross Sea

    International Nuclear Information System (INIS)

    Kovach, J.; Faure, G.

    1977-01-01

    A preliminary report summarizing the results of a study of the strontium-87/strontium-86 ratios and of the rubidium and strontium concentrations of the fine-grained (less than 150 microns) noncarbonate fractions of sediment samples from core E32-25 raised from a depth of 327 fathoms in the Ross Sea at 78 0 31.0'S 164 0 24.7'W was presented. The strontium-87/strontium-86 ratios of the samples analyzed range from 0.7119 to 0.7220. Rubidium and strontium concentrations range, respectively, from 126 to 164 parts per million and from 113 to 174 parts per million. The observed strontium-87/strontium-86 ratios and strontium concentrations in sediment samples from core E32-25 fit a hyperbolic curve. These ratios can be used to estimate the concentrations of volcanogenic detritus in the sediment samples. The results of this study provide additional baseline data for anticipated future studies of sediment cores to be recovered from beneath the Ross Ice Shelf by the Ross Ice Shelf Project. 1 figure

  11. Removal of Strontium from Drinking Water by Conventional ...

    Science.gov (United States)

    The United States Environmental Protection Agency Contaminant Candidate List 3 lists strontium as a contaminant for potential regulatory consideration in drinking water. There is very little data available on strontium removal from drinking water. As a result, there is an immediate need to perform treatment studies. The objective of this work is to evaluate the effectiveness of conventional and lime-soda ash softening treatments to remove strontium from surface and ground waters. Conventional drinking water treatment with aluminum and iron coagulants were able to achieve 12% and 5.9% strontium removal at best, while lime softening removed as much as 78% from natural strontium-containing ground water. Systematic fundamental experiments showed that strontium removal during the lime-soda ash softening was related to pH, calcium concentration and dissolved inorganic carbon concentration. Final strontium concentration was also directly associated with initial strontium concentration. Precipitated solids showed well-formed crystals or agglomerates of mixed solids, two polymorphs of calcium carbonate (vaterite and calcite), and strontianite, depending on initial water quality conditions. X-ray diffraction analysis suggested that strontium likely replaced calcium inside the crystal lattice and was likely mainly responsible for removal during lime softening. To inform the public.

  12. Lanthanide doped strontium-barium cesium halide scintillators

    Science.gov (United States)

    Bizarri, Gregory; Bourret-Courchesne, Edith; Derenzo, Stephen E.; Borade, Ramesh B.; Gundiah, Gautam; Yan, Zewu; Hanrahan, Stephen M.; Chaudhry, Anurag; Canning, Andrew

    2015-06-09

    The present invention provides for a composition comprising an inorganic scintillator comprising an optionally lanthanide-doped strontium-barium, optionally cesium, halide, useful for detecting nuclear material.

  13. System of lithium, sodium, and strontium bromides

    International Nuclear Information System (INIS)

    Litvinova, G.N.; Yagub'yan, E.S.; Bukhalova, G.A.

    1988-01-01

    The visual-polythermal and partially differential thermal methods of analysis have been applied to investigate the meltability diagram of the Li 2 Br 2 -Na 2 Br 2 -SrBr 2 ternary system. Three fields of crystallization belonging to strontium bromide, to the compound LiSr 2 Br 5 and solid solutions of lithium and sodium bromides are found. Two points complying with nonvariant equilibria are discovered

  14. Scale of human mobility in the southern Andes (Argentina and Chile): A new framework based on strontium isotopes.

    Science.gov (United States)

    Barberena, Ramiro; Durán, Víctor A; Novellino, Paula; Winocur, Diego; Benítez, Anahí; Tessone, Augusto; Quiroga, María N; Marsh, Erik J; Gasco, Alejandra; Cortegoso, Valeria; Lucero, Gustavo; Llano, Carina; Knudson, Kelly J

    2017-10-01

    The goal of this article is to assess the scale of human paleomobility and ecological complementarity between the lowlands and highlands in the southern Andes during the last 2,300 years. By providing isotope results for human bone and teeth samples, we assess a hypothesis of "high residential mobility" suggested on the basis of oxygen isotopes from human remains. We develop an isotopic assessment of human mobility in a mountain landscape combining strontium and oxygen isotopes. We analyze bone and teeth samples as an approach to life-history changes in spatial residence. Human samples from the main geological units and periods within the last two millennia are selected. We present a framework for the analysis of bioavailable strontium based on the combination of the geological data with isotope results for rodent samples. The 87 Sr/ 86 Sr values from human samples indicate residential stability within geological regions along life history. When comparing strontium and oxygen values for the same human samples, we record a divergent pattern: while δ 18 O values for samples from distant regions overlap widely, there are important differences in 87 Sr/ 86 Sr values. Despite the large socio-economic changes recorded, 87 Sr/ 86 Sr values indicate a persisting scenario of low systematic mobility between the different geological regions. Our results suggest that strontium isotope values provide the most germane means to track patterns of human occupation of distinct regions in complex geological landscapes, offering a much higher spatial resolution than oxygen isotopes in the southern Andes. © 2017 Wiley Periodicals, Inc.

  15. A new method for the preparation of strontium titanate and strontium hypovanadate

    International Nuclear Information System (INIS)

    Balasubramanian, M.R.

    1985-01-01

    Strontium titanate has been a prized chemical by virtue of its dielectric, photoelectric and surface properties. The compound crystallises with the cubic perovskite structure. Till now only two techniques (and a few variants therein) have been employed for its synthesis, one of them is a solid state reaction between SrCO 3 and TiO 2 at 1100deg, and the other is a coprecipitation of strontium titanyl oxalate followed by calcination at 850deg. As ternary oxides, such as copper chromite, have been prepared by complex formation, the author found it interesting to apply this method to the preparation of strontium titanate. The most easily accessible and versatile complexing agent, EDTA, was used. (author)

  16. Influence of granular strontium chloride as additives on some ...

    Indian Academy of Sciences (India)

    Influence of granular strontium chloride as additives on some electrical and mechanical properties for pure polyvinyl alcohol. A B Elaydy M Hafez ... Keywords. Polyvinyl-alcohol (PVA); granular strontium chloride, SrCl2; a.c. electrical conductivity; dielectric constant; dielectric loss; Young's modulus; creep relaxation curve.

  17. Thermal reactions of some calcium, strontium, and barium chromates

    International Nuclear Information System (INIS)

    Piekarska-Piesse, B.; Gontarz, Z.; Ostrowski, A.; Kucharski, R.

    2000-01-01

    Thermal decomposition of calcium chromates and solid state reactions of barium and strontium chromates(VI) with barium and strontium hydroxides and carbonates, as well as the reduction of chromates by carbon and hydrogen, have been investigated. The mechanisms of individual stages of the thermal decomposition have been proposed on the basis of morphological classification. (author)

  18. Strontium-90 and cesium-137 in powdered milk

    International Nuclear Information System (INIS)

    1977-01-01

    Japan Chemical Analysis Center has analysed the strontium-90 and cesium-137 content in powdered milk. The samples were purchased on the open market in Tokyo from the powdered milk producers. The analysis of Strontium-90 and Cesium-137 content was carried out using the method recommended by Science and Technology Agency. (author)

  19. Reduced-graphene-oxide-and-strontium-titanate-based double

    Indian Academy of Sciences (India)

    Microwave-absorbing materials based on reduced graphene oxide (r-GO)/ strontium titanate were prepared by embedding in epoxy matrix. R-GO and strontium titanate were synthesized and characterized before composite fabrication. Microstructures of the constituent elements were studied by scanning electron ...

  20. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium calcium...

  1. Uptake behavior of titanium molybdophosphate for cesium and strontium

    International Nuclear Information System (INIS)

    Yavari, R.; Ahmadi, S.J.; Huang, Y.D.

    2010-01-01

    This study investigates uptake of cesium and strontium from aqueous solution similar to nuclear waste on three samples of titanium molybdophosphate (TMP) synthesized under various conditions. Effects of concentration of sodium nitrate, pH and contact time on the uptake of cesium and strontium have been studied by bath method. The results showed that TMP has high affinity toward cesium and strontium at pH > 2 and relatively low concentration of sodium nitrate. Kinetic data indicated that cesium uptake process to achieve equilibrium was faster than strontium. Cesium and strontium breakthrough curves were examined at 25 deg C using column packed with H 3 O + form of TMP and breakthrough curves showed symmetrical S-shaped profiles. At the same time, the calculated breakthrough capacity for cesium was higher than strontium. The results of desorption studies showed that over 99% of cesium and strontium was washed out of column by using 4 M NH 4 Cl solution. This study suggests that TMP can have great potential applications for the removal of strontium and specially cesium from nuclear waste solution. (author)

  2. Calcium versus strontium handling by the heart muscle.

    Science.gov (United States)

    Hendrych, Michal; Olejnickova, Veronika; Novakova, Marie

    2016-01-01

    Calcium plays a crucial role in numerous processes in living systems, from both intracellular and intercellular signalling to blood clotting. Calcium can be replaced by strontium in various intracellular processes due to high level of their similarity and strontium thus may serve as a valuable tool for different experimental studies. On the other hand, strontium is also used in clinical medicine and is commonly taken to the human body with food and water. The negative cardiac side effects of strontium therapy of osteoporosis and bone metastases are well known, but still not fully explained. This fact explains enhanced interest in this element and its impact on human body. This article reviews effects of calcium and strontium on several biochemical and physiological processes, with special emphasis on cardiac muscle.

  3. Strontium 90 in silts of the Dnieper cascade water reservoirs

    International Nuclear Information System (INIS)

    Romanenko, V.D.; Kuz'menko, M.I.; Matvienko, L.P.; Klenus, V.G.; Nasvit, O.I.

    1989-01-01

    The change of strontium-90 content in water and silts of the Dnieper cascade water reservoirs was analyzed. It was shown, that decrease of strontium-90 content in water in time connected basically with ion exchange adsorption of strontium-90 by residues. A high sorption ability of residues made it possible for radioisotopes to reduce sharply their concentration along depth of soils. The highest concentration of radioisotopes was in the upper layers, enriched by silt. It was ascertained, that strontium-90 migration along depth of residues took place rapidly in the Kiev's water reservoir. Down the cascade strontium-90 content reduced in lower layers of residues as well as in upper layers. 4 tabs

  4. Strontium Promotes Cementoblasts Differentiation through Inhibiting Sclerostin Expression In Vitro

    Directory of Open Access Journals (Sweden)

    Xingfu Bao

    2014-01-01

    Full Text Available Cementogenesis, performed by cementoblasts, is important for the repair of root resorption caused by orthodontic treatment. Based on recent studies, strontium has been applied for osteoporosis treatment due to its positive effect on osteoblasts. Although promising, the effect of strontium on cementoblasts is still unclear. So the aim of this research was to clarify and investigate the effect of strontium on cementogenesis via employing cementoblasts as model. A series of experiments including MTT, alkaline phosphatase activity, gene analysis, alizarin red staining, and western blot were carried out to evaluate the proliferation and differentiation of cementoblasts. In addition, expression of sclerostin was checked to analyze the possible mechanism. Our results show that strontium inhibits the proliferation of cementoblasts with a dose dependent manner; however, it can promote the differentiation of cementoblasts via downregulating sclerostin expression. Taking together, strontium may facilitate cementogenesis and benefit the treatment of root resorption at a low dose.

  5. Oxygen deficiency in the North Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.

    carentes de oxigeno. Se describen los impactos de la deficiencia de oxigeno sobre la biogcoquimica, especial- mente sobre las transformaciones anaerobicas del nitrogeno. Se realizara una comparacion entre la ZMO mesopelagica perenne del Occano Indico nor...-occidental y un sistema deficicnte en oxigeno mas somero que se desarrolla estacionalmente (durante el final del verano y el otono) sobre la plataforma continental de la India occidental. Este ultimo parece inlensificarse en los ultimos anos debido a la carga...

  6. Nondestructive measurement of environmental radioactive strontium

    Directory of Open Access Journals (Sweden)

    Saiba Shuntaro

    2014-03-01

    Full Text Available The Fukushima Daiichi nuclear power plant accident was triggered by the 2011 Great East Japan Earthquake. The main radioactivity concerns after the accident are I-131 (half-life: 8.0 days, Cs-134 (2.1 years, Cs-137 (30 years, Sr-89 (51 days, and Sr-90 (29 years. We are aiming to establish a new nondestructive measurement and detection technique that will enable us to realize a quantitative evaluation of strontium radioactivity without chemical separation processing. This technique is needed to detect radiation contained in foods, environmental water, and soil, to prevent us from undesired internal exposure to radiation.

  7. Strontium-90 and promethium-147 recovery

    International Nuclear Information System (INIS)

    Hoisington, J.E.; McDonell, W.R.

    1982-01-01

    Strontium-90 and promethium-147 are fission product radionuclides with potential for use as heat source materials in high reliability, non-interruptible power supplies. Interest has recently been expressed in their utilization for Department of Defense (DOD) applications. This memorandum summarizes the current inventories, the annual production rates, and the possible recovery of Sr-90 and Pm-147 from nuclear materials production operations at Hanford and Savannah River. Recovery of these isotopes from LWR spend fuel utilizing the Barnwell Nuclear Fuels Plant (BNFP) is also considered. Unit recovery costs at each site are provided

  8. Investigation of strontium accumulation on ovariectomized Sprague–Dawley rat tibia by micro-PIXE

    Energy Technology Data Exchange (ETDEWEB)

    Li, X.; Li, Y. [Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Jin, W. [Institute of Radiation Medicine, Fudan University, Shanghai 200032 (China); Zheng, Y.; Rong, C.; Lyu, H. [Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Shen, H., E-mail: haoshen@fudan.edu.cn [Institute of Modern Physics, Fudan University, Shanghai 200433 (China)

    2014-08-01

    Strontium ranelate is a newly developed drug effective in osteoporosis treatment by depressing bone resorption and maintaining bone formation. Strontium accumulation and distribution are determined in bones of rat after strontium ranelate administration by using micro-PIXE. The investigated rats are divided into four groups: (A) control, (B) ovariectomized, (C) ovariectomized followed with strontium chloride, (D) ovariectomized followed with strontium ranelate. It was found that strontium ranelate would result in increasing trabecular volume and decreasing bone resorption to treat osteoporosis. There are similar contours of calcium and strontium in two-dimensional images, while the strontium is not evenly distributed in the bone. It supports the conclusion that strontium has an affinity for bone and it is capable of replacing calcium atoms as a part of the strontium mechanism in the osteoporosis treatment. The results related to biochemistry are also discussed.

  9. Leaching of strontium sulfide from produced clinker in conversion furnace

    International Nuclear Information System (INIS)

    Ghorbanian, S. A.; Salehpour, A. R.; Radpour, S. R.

    2009-01-01

    Iran is rich in mineral resources one of which is mineral Celestine. Basing on current estimations, the capacity of mineral Celestine is over two million tons, 75-95% of which is strontium sulfate. However; in industries such as Color cathode Ray Tubes, pyrochemical processes, ceramics, paint production, zinc purification processes; strontium sulfate is not a direct feed, rather it is largely consumed in the form of strontium carbonate. Two conventional methods are used to produce strontium carbonate from the sulfate; that is direct reaction and black ash methods. Strontium sulfide, as an intermediate component has a key role in black ash process including strontium sulfate reduction by coke, hence producing and leaching the strontium sulfide by hot water. Finally the reaction of strontium sulfate with sodium carbonate lead to strontium carbonate. In this paper, a system was designed to analyze and optimize the process parameters of strontium sulfide production which is less expensive and available solvent in water. Fundamentally, when strontium sulfide becomes in contact with strontium sulfate; Sr(SH) 2 , and Sr(OH) 2 , are produced. The solubility of strontium sulfide depends on water temperature and the maximum solubility achieved at 90 d egree C . The results showed that in the experimental scale, at water to SrS ratio of 6; they sediment for 45 minutes at 95 d egree C in five operational stages; the separation of 95 and 97.1 percent of imported SrS is possible in effluent of fourth and fifth stages, respectively. Thus; four leaching stages could be recommended for pilot scale plants. Also, the results show that at water to SrS ratio of 8, 40 minutes sedimentation at 85-95 d egree C in one operational stage, the separation of 95 percent separation of inputted SrS, is possible. Solvent leaching process is continued till no smell of sulfur components is felt. It could be used as a key role to determine the number of leaching stages in experiments. Finally, the

  10. What Are Rare Clotting Factor Deficiencies?

    Science.gov (United States)

    ... Deficiency Factor V Deficiency Combined FV & FVIII Deficiencies Factor VII Deficiency Factor X Deficiency Factor XI Deficiency Factor ... Deficiency Factor V Deficiency Combined FV & FVIII Deficiencies Factor VII Deficiency Factor X Deficiency Factor XI Deficiency Factor ...

  11. Laser Stabilization with Laser Cooled Strontium

    DEFF Research Database (Denmark)

    Christensen, Bjarke Takashi Røjle

    The frequency stability of current state-of-the-art stabilized clock lasers are limited by thermal fluctuations of the ultra-stable optical reference cavities used for their frequency stabilization. In this work, we study the possibilities for surpassing this thermal limit by exploiting the nonli......The frequency stability of current state-of-the-art stabilized clock lasers are limited by thermal fluctuations of the ultra-stable optical reference cavities used for their frequency stabilization. In this work, we study the possibilities for surpassing this thermal limit by exploiting...... the nonlinear effects from coupling of an optical cavity to laser cooled atoms having a narrow transition linewidth. Here, we have realized such a system where a thermal sample of laser cooled strontium-88 atoms are coupled to an optical cavity. The strontium-88 atoms were probed on the narrow 1S0-3P1 inter......-combination line at 689 nm in a strongly saturated regime. The dynamics of the atomic induced phase shift and absorption of the probe light were experimentally studied in details with the purpose of applications to laser stabilization. The atomic sample temperature was in the mK range which brought this system out...

  12. A study on characteristic of selective membrane for strontium analysis

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Seung Hyun; Choi, Young Woo [Kwang-ju Institute of Science and Technology, Kwangju (Korea)

    1999-04-01

    In this study, supported liquid membranes (SLMs) using crown ether were prepared in order to separate strontium ion selectively from a calcium contained solution However, at the higher than 3 N nitric acid concentration of a strip solution, stability of a SLM was declined remarkably owing to the hasty loss of carrier impregnated in supporter and, on account of this phenomena, facilitated transports were not accomplished. And DC18C6 as a neutral carrier affected remarkably the selectivity of strontium and the factor determining permeabilities of metal ions was as a role of DNNS. Consequently, in order to be a optimal SLM for the high permeability and the stable selectivity of strontium, concentration of DC18C6 and DNNS should be 0.1 M and 25 mM, respectively and, at this condition, the relative removal ratio of strontium to calcium was 93.3%. And the change of calcium concentration in the feed solution affected the permeability of strontium. In particular, when the ratio of strontium to calcium concentration in the feed solution was in the range of 1/5 - 1/50, strontium could be separated selectively at stable permeabilities. (author). 17 refs., 19 figs., 3 tabs.

  13. Growth and characterization of strontium oxalate crystals by the decomposition of ascorbic acid in presence of strontium chloride

    International Nuclear Information System (INIS)

    Bijini, B.R.; Prasanna, S.; Rajendra Babu, K.; Deepa, M.

    2010-01-01

    Full text: Ascorbic acid (vitamin c) is an important organic compound that helps to maintain the optimal health of human body. It is essential for the development and maintenance of connective tissues. Vitamin C plays an important role in a number of metabolic functions including the activation of the B vitamin, folic acid, the conversion of cholesterol to bile acids and the conversion of the amino acid, tryptophan, to the neurotransmitter, serotonin. During the process of metabolism it decomposes into oxalic acid. This compound is photosensitive and has least thermal stability. The decomposition of Ascorbic acid has been studied in various conditions. It is reported that decomposition of ascorbic acid in presence of Cd 2+ ions leads to the formation of cadmium oxalate crystals. In the present work, in presence of Sr 2+ ion the ascorbic acid is decomposed to Strontium Oxalate in gel media. In this technique, silica gel is used as a medium to grow crystals. Slow diffusion of reactants in the gel medium can be considered to mimic the growth of crystals in the human body. Gels were prepared by mixing appropriate quantities of sodium meta silicate and ascorbic acid, adjusting the pH in the range 5-7.5. Over the set gel, the feed solution of 1M Strontium chloride was added. Yellowish prismatic and bar shaped crystals were obtained within 24 hours. The nucleation density is maximum at a pH of 6 and minimum at 5. Good quality crystals were obtained for a pH of 5 and gel density 1.05g/cc. The FTIR spectra of grown crystals are recorded and analyzed.The band at 3431 cm -1 is assigned to OH stretching frequency of co-ordinated water molecule and the band at 1637cm -1 corresponds to C=O Stretching of carbonyl group. The band at 1319cm -1 is assigned to symmetric stretching of COO- group. The IR band at 767cm -1 corresponds to the combined effect of inplane deformation of CO 2 and the presence of metal oxygen bond .The band at 505cm -1 is due to wagging mode

  14. Influence of reactor irradiation on the protons intercalation and stability of barium cerates and strontium cerates

    International Nuclear Information System (INIS)

    Aksenova, T.I.; Khromushin, I.V.; Zhotabaev, Zh.R.; Kornienko, P.A.; Munasbaeva, K.K.

    2005-01-01

    The work is devoted to study of reactor irradiation influence on the gas-solid exchange processes in the high-temperature proton semiconductors on the base of cerates and strontium. A number of new regularities of influence of content of some proton semiconductors on the gas-solid exchange processes was established. It is shown, that increase of rate of cation doping rate leads to considerable lowering in its of carbonic gas content, and therefore to improvement their tribological properties. It is revealed, that irradiation of polycrystalline samples leads to growth of oxygen amount desorbed from samples, whereas irradiation of monocrystalline samples practically does not has effect on the desorbed oxygen amount. It was found, that character of relation of intercalated in the sample protons depend on sample doping rate

  15. Calcium phosphate cements with strontium halides as radiopacifiers.

    Science.gov (United States)

    López, Alejandro; Montazerolghaem, Maryam; Engqvist, Håkan; Ott, Marjam Karlsson; Persson, Cecilia

    2014-02-01

    High radiopacity is required to monitor the delivery and positioning of injectable implants. Inorganic nonsoluble radiopacifiers are typically used in nondegradable bone cements; however, their usefulness in resorbable cements is limited due to their low solubility. Strontium halides, except strontium fluoride, are ionic water-soluble compounds that possess potential as radiopacifiers. In this study, we compare the radiopacity, mechanical properties, composition, and cytotoxicity of radiopaque brushite cements prepared with strontium fluoride (SrF2 ), strontium chloride (SrCl2 ·6H2 O), strontium bromide (SrBr2 ), or strontium iodide (SrI2 ). Brushite cements containing 10 wt % SrCl2 ·6H2 O, SrBr2 , or SrI2 exhibited equal to or higher radiopacity than commercial radiopaque cements. Furthermore, the brushite crystal lattice in cements that contained the ionic radiopacifiers was larger than in unmodified cements and in cements that contained SrF2 , indicating strontium substitution. Despite the fact that the strontium halides increased the solubility of the cements and affected their mechanical properties, calcium phosphate cements containing SrCl2 ·6H2 O, SrBr2 , and SrI2 showed no significant differences in Saos-2 cell viability and proliferation with respect to the control. Strontium halides: SrCl2 ·6H2 O, SrBr2 , and SrI2 may be potential candidates as radiopacifiers in resorbable biomaterials although their in vivo biocompatibility, when incorporated into injectable implants, is yet to be assessed. Copyright © 2013 Wiley Periodicals, Inc.

  16. Strontium-90 and cesium-137 in freshwater from May 1984

    International Nuclear Information System (INIS)

    1984-01-01

    Strontium-90 and cesium-137 in freshwater measured in May 1984 are given in pCi/l. The sampling point is 1, Kasumigaura-Lake (Ibaraki). Collection and pretreatment of samples, preparation of samples for analysis, separation of strontium-90 and cesium-137, determination of stable strontium, calcium and potassium, and counting are described. The sample was passed through a cation exchange column. After the radiochemical separation, the mounted precipitates were counted for activity using low background beta counters normally for 60 minutes. (Mori, K.)

  17. Isomorfic Substitutions of Calcium by Strontium in Calcium Hydroxyapatite

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, Hilbert

    1962-12-15

    By means of homogeneous precipitation it has been possible to synthesize crystalline solid solutions of calcium strontium hydroxyapatite from aqueous solutions. The lattice constants for the solid solutions were measured in the range Ca{sub 9}Sr(PO{sub 4}){sub 6}(OH){sub 2} - CaSr{sub 9}(PO{sub 4}){sub 6}(OH){sub 2}. The investigations show that the discrimination of strontium against calcium is considerably smaller than reported elsewhere (1). Strontium is preferentially built into the c-axis direction of the apatite lattice.

  18. Strontium D-Glutamate Hexahydrate and Strontium Di(hydrogen L-glutamate) Pentahydrate

    DEFF Research Database (Denmark)

    Christgau, Stephan; Odderhede, Jette; Stahl, Kenny

    2005-01-01

    Sr(C5H7NO4)] center dot 6H(2)O, ( I), and [Sr(C5H8NO4)(2)] center dot 5H(2)O, (II), both crystallize with similar strontium - glutamate - water layers. In ( I), the neutral layers are connected through hydrogen bonds by water molecules, while in ( II), the positively charged layers are connected...... through hydrogen bonds and electrostatic interactions by interleaving layers of hydrogen glutamate anions and water molecules....

  19. Strontium-90 and cesium-137 in tea (Japanese tea)

    International Nuclear Information System (INIS)

    1982-01-01

    Strontium-90 and cesium-137 in tea (Japanese tea) were determined. Five hundred grams of manufactured green tea was collected from six sampling locations in Japan. The results are shown in a table. (Namekawa, K.)

  20. Reaction of strontium zirconate with refractory borides and carbides

    International Nuclear Information System (INIS)

    Bowker, J.C.; Lane, J.E.

    1990-01-01

    The chemical compatibility of the potential oxide ceramic matrix material, strontium zirconate, and several different potential nonoxide ceramic reinforcement materials was studied by elevated temperature reaction. Results are presented in this paper

  1. Cation interdiffusion in polycrystalline calcium and strontium titanate

    International Nuclear Information System (INIS)

    Butler, E.P.; Jain, H.; Smyth, D.M.

    1991-01-01

    This paper discusses a method that has been developed to study bulk lattice interdiffusion between calcium and strontium titanate by fabrication of a diffusion couple using cosintering. The measured interdiffusion coefficients, D(C), indicate that strontium impurity diffusion in calcium titanate occurs at a faster rate than calcium impurity diffusion in strontium titanate. These interdiffusion coefficients are composition independent when the concentration of the calcium cation exceeds that of the strontium cation; otherwise D(C) is strongly composition dependent. Investigations into the effect of cation nonstoichiometry give results that are consistent with a defect incorporation reaction in which excess TiO 2 , within the solid solubility limit, produces A-site cation vacancies as compensating defects. The interdiffusion coefficients increase with increasing concentrations of TiO 2 , so it is concluded that interdiffusion of these alkaline-earth cations in their titanates occurs via a vacancy mechanism

  2. A combined cesium-strontium extraction/recovery process

    International Nuclear Information System (INIS)

    Horwitz, E.P.; Dietz, M.L.; Jensen, M.P.

    1996-01-01

    A new solvent extraction process for the simultaneous extraction of cesium and strontium from acidic nitrate media is described. This process uses a solvent formulation comprised of 0.05 M di-t-butylcyclohexano-18-crown-6 (DtBuCH18C6), 0.1 M Crown 100' (a proprietary, cesium-selective derivative of dibenzo-18-crown-6), 1.2 M tributyl phosphate (TBP), and 5% (v/v) lauryl nitrile in an isoparaffinic hydrocarbon diluent. Distribution ratios for cesium and strontium from 4 M nitric acid are 4.13 and 3.46, respectively. A benchtop batch countercurrent extraction experiment indicates that >98% of the cesium and strontium initially present in the feed solution can be removed in only four extraction stages. Through proper choice of extraction and strip conditions, extracted cesium and strontium can be recovered either together or individually

  3. Strontium removal jar test dataset for all figures and tables.

    Data.gov (United States)

    U.S. Environmental Protection Agency — The datasets where used to generate data to demonstrate strontium removal under various water quality and treatment conditions. This dataset is associated with the...

  4. Strontium-90 Error Discovered in Subcontract Laboratory Spreadsheet. Topical Report

    International Nuclear Information System (INIS)

    Brown, D.D.; Nagel, A.S.

    1999-07-01

    West Valley Demonstration Project health physicists and environment scientists discovered a series of errors in a subcontractor's spreadsheet being used to reduce data as part of their strontium-90 analytical process

  5. Adsorption of strontium (II) metal ions using phosphonate ...

    Indian Academy of Sciences (India)

    Chelation is a process wherein metalions and a polymer/matrix are bound together ... waste: evaporation, chemical precipitation/flocculation, solid-phase separation ... sary to remove strontium from the waste streams before it is discharged to ...

  6. Secondary laser cooling of strontium-88 atoms

    Energy Technology Data Exchange (ETDEWEB)

    Strelkin, S. A.; Khabarova, K. Yu., E-mail: kseniakhabarova@gmail.com; Galyshev, A. A.; Berdasov, O. I.; Gribov, A. Yu.; Kolachevsky, N. N.; Slyusarev, S. N. [Federal State Unitary Enterprise “All-Russia Research Institute for Physicotechnical and Radio Engineering Measurements” (VNIIFTRI) (Russian Federation)

    2015-07-15

    The secondary laser cooling of a cloud of strontium-88 atoms on the {sup 1}S{sub 0}–{sup 3}P{sub 1} (689 nm) intercombination transition captured into a magneto-optical trap has been demonstrated. We describe in detail the recapture of atoms from the primary trap operating on the strong {sup 1}S{sub 0}–{sup 1}P{sub 1} (461 nm) transition and determine the recapture coefficient κ, the number of atoms, and their temperature in the secondary trap as a function of experimental parameters. A temperature of 2 µK has been reached in the secondary trap at the recapture coefficient κ = 6%, which confirms the secondary cooling efficiency and is sufficient to perform metrological measurements of the {sup 1}S{sub 0}–{sup 3}P{sub 1} (698 nm) clock transition in an optical lattice.

  7. Strontium isotopic stratigraphy utilizing authigenic dolomites in hemipelagic sediments

    Energy Technology Data Exchange (ETDEWEB)

    Baker, P.A. (Duke Univ., Durham, NC (USA)); Kastner, M. (Scripps Institute of Oceanography, La Jolla, CA (USA)); Elderfield, H. (Univ. of Cambridge (England))

    1990-05-01

    Authigenic dolomites commonly occur in organic-rich, continental margin marine sediments. These dolomites play a key role in the age dating of stratigraphic sections. The dolomites often are the only lithology amenable to paleomagnetic stratigraphy; they preserve siliceous microfossils against diagenetic; recrystallization, and provide useful strontium isotopic stratigraphic ages. Several potential sources of error frequently are unique to the use of authigenic dolomites in the strontium isotope methods. (1) The dolomites occur as cements of the host lithology, hence, they are not a pure phase. Potentially important contaminants during analysis include gypsum clay minerals, feldspars, and iron and manganese oxides. Strontium may occur as a structural substituent ion in these minerals or as a surface-adsorbed ion. Various leaching techniques have been tested to isolate dolomitic strontium. Purer dolomites and strontium-enriched dolomites often can be selected to ease these problems. (2) The dolomites form after the deposition of the host sediment, therefore, they record the diagenetic age not the depositional age. The stable isotopic composition of the dolomites can aid in selection of early formed samples. (3) The dolomites record pore-water strontium isotope compositions, not seawater isotopic compositions. This problem is also minimized by choosing dolomites formed near the sediment-water interface. (4) The dolomites formed near the sediment-water interface originated as rotodolomites and undergo subsequent burial diagenesis, creating a potential for later strontium isotope exchange. This problem is minimized by selecting fresh samples from the interior of nearly impermeable beds and nodules. Results from the Miocene Monterey Formation of California and from the Eocene through Pliocene Pisco basin of Peru show that authigenic dolomites can provide useful strontium isotopic age estimates.

  8. Separation of fission strontium from nuclear fuels by ammonium molybdatophosphate

    International Nuclear Information System (INIS)

    Hermann, A.

    1984-01-01

    The separation of fission strontium from solutions of prolonged cooled nuclear fuel has been performed using ammoniummolybdatophosphate (AMP) columns. The sorption mechanism of bivalent ions of AMP has been investigated by column and batch experiments. A pure ion exchange of Sr 2+ for two H + or NH 4 + ions has been established. Conditions for the sepasorption and elution of fission strontium and other fission products on AMP columns are described. (author)

  9. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Research Home / < Back To Health Topics / Iron-Deficiency Anemia Iron-Deficiency Anemia Also known as Leer en español Iron-deficiency ... iron-deficiency anemia. Blood tests to screen for iron-deficiency anemia To screen for iron-deficiency anemia, your doctor ...

  10. Strontium ranelate for preventing and treating postmenopausal osteoporosis.

    Science.gov (United States)

    O'Donnell, S; Cranney, A; Wells, G A; Adachi, J D; Reginster, J Y

    2006-10-18

    Strontium ranelate is a new treatment for osteoporosis therefore, its benefits and harms need to be known. To determine the efficacy and safety of strontium ranelate for the treatment and prevention of postmenopausal osteoporosis. We searched MEDLINE (1996 to March 2005), EMBASE (1996 to week 9 2005), the Cochrane Library (1996 to Issue 1 2005), reference lists of relevant articles and conference proceedings from the last two years. Additional data was sought from authors. We included randomized controlled trials (RCTs) of at least one year duration comparing strontium ranelate versus placebo reporting fracture incidence, bone mineral density (BMD), health related quality of life or safety in postmenopausal women. Treatment (versus prevention) population was defined as women with prevalent vertebral fractures and/or lumbar spine BMD T score gastritis or death. Additional data suggests that the risk of vascular and nervous system side-effects is slightly increased with taking 2 g of strontium ranelate daily over three to four years. There is silver level evidence (www.cochranemsk.org) to support the efficacy of strontium ranelate for the reduction of fractures (vertebral and to a lesser extent non-vertebral) in postmenopausal osteoporotic women and an increase in BMD in postmenopausal women with/without osteoporosis. Diarrhea may occur however, adverse events leading to study withdrawal were not significantly increased with taking 2 g of strontium ranelate daily. Potential vascular and neurological side-effects need to be further explored.

  11. Flame Spectrophotometric Determination of Strontium in Water and Biological Material

    Energy Technology Data Exchange (ETDEWEB)

    Joensson, G

    1964-10-15

    A flame spectrophotometric method has been developed for the determination of strontium in biological material and water samples. Strontium is determined in the presence of calcium at a wavelength of 4607 A. The intensity of the strontium emission from the sample is increased if n-butanol is added to a solution of the sample in water. With a 6 vol% solution of n-butanol in water, an optimum intensity of 3.5 times that obtained with pure water solution is obtained. Anions and alkali metals which might interfere with the flame spectrophotometric determination are separated from the sample by a simple ion exchange operation. The method allows determination of strontium in solutions down to 0.1{mu}g/ml. In this case the standard deviation is 3.1 % and with a strontium concentration of 1 {mu}g/ml the deviation is 0.9 %. This method has been used for the determination of strontium in samples of varying composition such as bone, meat and skin from fishes, samples of human bones, shell-fish, milk, and water, in which case Sr quantities of 5{mu}g were determined with an analytical error of less than 5 % and Sr{sub q}uantities greater than 10 {mu}g with an error of less than 3 %.

  12. Strontium-90 (90Sr) determination using liquid scintillation counting

    International Nuclear Information System (INIS)

    Cheberle, L.T.V.; Rosa, M.M.L.; Ferreira, M.T.; Taddei, M.H.T.

    2015-01-01

    This procedure describes a method for separation and measurement of strontium 90 Sr in water, soils, and biological samples. Water samples may be concentrated using evaporation or calcium phosphate coprecipitation. Soils and biological materials must be dissolved using wet digestion. Tracers and carriers must be added before the attack. Radioactive strontium is separated employing a specific resin before determination by liquid scintillation counting using the double energetic window method. The resin is used to concentrate strontium from samples. Stable strontium is used to monitor method yields and correct results to improve precision and accuracy. The presence of elemental strontium in the sample may bias the gravimetric yield determination. If it is suspected that natural strontium is present in the sample, its concentration should be determined by a suitable means (ICP), and the yield calculation properly modified. Sr-Spec resin with an 8M HNO 3 load solution is used to effectively remove 140 Ba and 40 K isotopes, as well as other interferences from the matrix. Tetravalent plutonium, neptunium, cerium and ruthenium, however, are not removed using nitric acid. The radiochemical procedure was tested using PROCORAD intercomparison exercises and PNI samples. (author)

  13. Flame Spectrophotometric Determination of Strontium in Water and Biological Material

    International Nuclear Information System (INIS)

    Joensson, G.

    1964-10-01

    A flame spectrophotometric method has been developed for the determination of strontium in biological material and water samples. Strontium is determined in the presence of calcium at a wavelength of 4607 A. The intensity of the strontium emission from the sample is increased if n-butanol is added to a solution of the sample in water. With a 6 vol% solution of n-butanol in water, an optimum intensity of 3.5 times that obtained with pure water solution is obtained. Anions and alkali metals which might interfere with the flame spectrophotometric determination are separated from the sample by a simple ion exchange operation. The method allows determination of strontium in solutions down to 0.1μg/ml. In this case the standard deviation is 3.1 % and with a strontium concentration of 1 μg/ml the deviation is 0.9 %. This method has been used for the determination of strontium in samples of varying composition such as bone, meat and skin from fishes, samples of human bones, shell-fish, milk, and water, in which case Sr quantities of 5μg were determined with an analytical error of less than 5 % and Sr q uantities greater than 10 μg with an error of less than 3 %

  14. 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.......043). CONCLUSION: ID is frequent in an outpatient HF clinic. ID is not associated with cardiovascular biomarkers after adjustment for traditional confounders. Inflammation, but not neurohormonal activation is associated with ID in systolic HF. Further studies are needed to understand iron metabolism in elderly HF...

  15. The Strontium Isotope Record of Zavkhan Terrane Carbonates: Strontium Isotope Stability Through the Ediacaran-Cambrian Transition

    OpenAIRE

    Petach, Tanya N.

    2015-01-01

    First order trends in the strontium isotopic (87Sr/86Sr) composition of seawater are controlled by radiogenic inputs from the continent and non-radiogenic inputs from exchange at mid-ocean ridges. Carbonates precipitated in seawater preserve trace amounts of strontium that record this isotope ratio and therefore record the relative importance of mid-ocean ridge and weathering chemical inputs to sea water composition. It has been proposed that environmental changes during the Ediacaran-Cambria...

  16. Strontium-90 at the Hanford Site and its ecological implications

    International Nuclear Information System (INIS)

    RE Peterson; TM Poston

    2000-01-01

    Strontium-90, a radioactive contaminant from historical operations at the U.S. Department of Energy (DOE) Hanford Site, enters the Columbia River at several locations associated with former plutonium production reactors at the Site. Strontium-90 is of concern to humans and the environment because of its moderately long half-life (29.1 years), its potential for concentrating in bone tissue, and its relatively high energy of beta decay. Although strontium-90 in the environment is not a new issue for the Hanford Site, recent studies of near-river vegetation along the shoreline near the 100 Areas raised public concern about the possibility of strontium-90-contaminated groundwater reaching the riverbed and fall chinook salmon redds. To address these concerns, DOE asked Pacific Northwest National Laboratory (PNNL) to prepare this report on strontium-90, its distribution in groundwater, how and where it enters the river, and its potential ecological impacts, particularly with respect to fall chinook salmon. The purpose of the report is to characterize groundwater contaminants in the near-shore environment and to assess the potential for ecological impact using salmon embryos, one of the most sensitive ecological indicators for aquatic organisms. Section 2.0 of the report provides background information on strontium-90 at the Hanford Site related to historical operations. Public access to information on strontium-90 also is described. Section 3.0 focuses on key issues associated with strontium-90 contamination in groundwater that discharges in the Hanford Reach. The occurrence and distribution of fall chinook salmon redds in the Hanford Reach and characteristics of salmon spawning are described in Section 4.0. Section 5.0 describes the regulatory standards and criteria used to set action levels for strontium-90. Recommendations for initiating additional monitoring and remedial action associated with strontium-90 contamination at the Hanford Site are presented in Section 6

  17. Strontium-90 at the Hanford Site and its ecological implications

    Energy Technology Data Exchange (ETDEWEB)

    RE Peterson; TM Poston

    2000-05-22

    Strontium-90, a radioactive contaminant from historical operations at the U.S. Department of Energy (DOE) Hanford Site, enters the Columbia River at several locations associated with former plutonium production reactors at the Site. Strontium-90 is of concern to humans and the environment because of its moderately long half-life (29.1 years), its potential for concentrating in bone tissue, and its relatively high energy of beta decay. Although strontium-90 in the environment is not a new issue for the Hanford Site, recent studies of near-river vegetation along the shoreline near the 100 Areas raised public concern about the possibility of strontium-90-contaminated groundwater reaching the riverbed and fall chinook salmon redds. To address these concerns, DOE asked Pacific Northwest National Laboratory (PNNL) to prepare this report on strontium-90, its distribution in groundwater, how and where it enters the river, and its potential ecological impacts, particularly with respect to fall chinook salmon. The purpose of the report is to characterize groundwater contaminants in the near-shore environment and to assess the potential for ecological impact using salmon embryos, one of the most sensitive ecological indicators for aquatic organisms. Section 2.0 of the report provides background information on strontium-90 at the Hanford Site related to historical operations. Public access to information on strontium-90 also is described. Section 3.0 focuses on key issues associated with strontium-90 contamination in groundwater that discharges in the Hanford Reach. The occurrence and distribution of fall chinook salmon redds in the Hanford Reach and characteristics of salmon spawning are described in Section 4.0. Section 5.0 describes the regulatory standards and criteria used to set action levels for strontium-90. Recommendations for initiating additional monitoring and remedial action associated with strontium-90 contamination at the Hanford Site are presented in Section 6

  18. A comparative study of the metastable equilibrium solubility behavior of high-crystallinity and low-crystallinity carbonated apatites using pH and solution strontium as independent variables.

    Science.gov (United States)

    Heslop, D D; Bi, Y; Baig, A A; Otsuka, M; Higuchi, W I

    2005-09-01

    Using solution strontium and pH as independent variables, the metastable equilibrium solubility (MES) behavior of two carbonated apatite (CAP) samples has been examined, a high-crystallinity CAP (properties expected to be similar to dental enamel) and a low-crystallinity CAP (properties expected to be similar to bone mineral). CAP samples were prepared by precipitation/digestion: (CAP A: high-crystallinity, 1.3 wt% CO3, synthesized at 85 degrees C; CAP B: low-crystallinity, 6.4 wt% CO3, synthesized at 50 degrees C). Baseline MES distributions were determined in a series of 0.1 M acetate buffers containing only calcium and phosphate (no strontium) over a broad range of solution conditions. To assess the influence of strontium, MES profiles were determined in a similar fashion with 20, 40, 60, and 80% of the solution calcium being replaced on an equal molar basis by solution strontium. To determine the correct function governing CAP dissolution, ion activity products (IAPs) were calculated from the compositions of buffer solutions based on the hydroxyapatite template (Ca(10-n)Sr(n)(PO4)6(OH)2 (n = 0-10)) and the calcium/hydroxide deficient hydroxyapatite template (Ca(9-n)Sr(n)(HPO4)(PO4)5OH (n = 0-9)). (a) for CAP A, at high solution strontium/calcium ratios, the MES profiles were essentially superimposable when the solution IAPs were calculated using the stoichiometry of Ca6Sr4(PO4)6(OH)2 and for CAP B by a stoichiometry of Ca7Sr2(HPO4)(PO4)5OH; (b) for CAP A, at low strontium/calcium ratios, the stoichiometry yielding MES data superpositioning was found to be that of hydroxyapatite and for CAP B, that of calcium/hydroxide deficient hydroxyapatite. When other stoichiometries were assumed, good superpositioning of the data was not possible.

  19. Layer-by-Layer Epitaxial Growth of Defect-Engineered Strontium Cobaltites

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, Tassie K. [Materials Science; Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States; Cook, Seyoung [Materials Science; Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States; Wan, Gang [Materials Science; Hong, Hawoong [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States; Marks, Laurence D. [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States; Fong, Dillon D. [Materials Science

    2018-01-31

    Control over structure and composition of (ABO(3)) perovskite oxides offers exciting opportunities since these materials possess unique, tunable properties. Perovskite oxides with cobalt B-site cations are particularly promising, as the range of the cations stable oxidation states leads to many possible structural frameworks. Here, we report growth of strontium cobalt oxide thin films by molecular beam epitaxy, and conditions necessary to stabilize different defect concentration phases. In situ X-ray scattering is used to monitor structural evolution during growth, while in situ X-ray absorption near-edge spectroscopy is used to probe oxidation state and measure changes to oxygen vacancy concentration as a function of film thickness. Experimental results are compared to kinetically limited thermodynamic predictions, in particular, solute trapping, with semiquantitative agreement. Agreement between observations of dependence of cobaltite phase on oxidation activity and deposition rate, and predictions indicates that a combined experimental/theoretical approach is key to understanding phase behavior in the strontium cobalt oxide system.

  20. Oxygen toxicity

    Directory of Open Access Journals (Sweden)

    C. A. van der Westhuizen

    1990-07-01

    Full Text Available Oxygen has been discovered about 200 years ago. Since then the vital physiological involvement of oxygen in various biologi­cal processes, mainly energy production, has been established. However, in the body molecular oxygen can be converted to toxic oxygen metabolites such as superoxide anion, hydrogen peroxide, the hydroxyl radical and singlet oxygen. These toxic metabolites are produced mainly in the mitochondria, plasma membranes and endoplasmic reticulum.

  1. Migration of strontium-90 from a strontium-90 fluoride deep ocean source

    International Nuclear Information System (INIS)

    Yabusaki, S.

    1981-06-01

    A hypothetical rupture of a heat source capsule on the ocean floor is analyzed for strontium-90 migration and attenuation. The evolution of the three-dimensional contaminant plume is simulated by a modified version of the Okubo-Pritchard radially symmetrical, diffusion velocity dispersion model. Results from this study indicate that released solutes are confined vertically to a layer near the level of introduction. Along the plume centerline, however, water quality is affected for considerably distances downstream from the source, with the maximum effect occurring after one year

  2. Optical lattice clock with strontium atoms; Horloge a reseau optique a atomes de strontium

    Energy Technology Data Exchange (ETDEWEB)

    Baillard, X.; Le Targat, R.; Fouche, M.; Brusch, A.; Westergaard, Ph.G.; Lecallier, A.; Lodewyck, J.; Lemonde, P. [Observatoire de Paris, LNE-SYRTE, Systemes de Reference Temps Espace, 75 (France)

    2009-07-01

    Optical lattice clocks, which were first imagined in 2000, should allow one to achieve unprecedented performances in the domain of atomic clocks. We present here the Strontium lattice clock, developed at LNE-SYRTE. The principle, in particular trapping atoms in the Lamb-Dicke regime and the notion of magic wavelength, is first explained. We then present the results obtained for the {sup 87}Sr isotope, with a frequency accuracy of 2,6.10{sup -15}, and the {sup 88}Sr isotope, with. which we perform the first frequency measurement of an optical lattice clock with bosonic atoms. (authors)

  3. Effect of competing cations on strontium sorption to surficial sediments

    International Nuclear Information System (INIS)

    Bunde, R.L.; Rosentreter, J.J.

    1995-01-01

    The following study was conducted to determine strontium distribution coefficients (K d 'S) of a surficial sediment at the Idaho National Engineering Laboratory (INEL), Idaho. Batch experimental techniques were used to determine K d 's which describe the partitioning of a solute between the solution and solid phase. A surficial sediment was mixed with synthesized aqueous solutions designed to chemically simulate wastewater disposed to infiltrations ponds near the Idaho Chemical Processing Plant at the INEL with respect to major ionic character and pH. The effects of variable concentrations of competing cations (sodium, potassium, calcium and magnesium) on strontium sorption were investigated at a fixed pH of 8.00. The pH of the natural system shows no appreciable variation, whereas a marked variability in cation concentration has been noted. Strontium sorption was impacted to a greater degree by the concentration of calcium and magnesium in solution than by the presence of sodium or potassium. However, extreme sodium solution concentrations of 1.0 to 5.0 g/L dramatically reduced strontium sorption. In all cases, strontium K d 's decreased as the concentration of calcium and magnesium in solution increased. Linear isotherm model K d 's ranged from 12.0 to 84.7 mL/g. Analysis of data from these experiments indicated that moderate concentrations of calcium and magnesium (less than 40 mg/L) and high concentrations of sodium (1.0 to 5.0 g/L) in wastewater increase strontium mobility by decreasing the sorption of strontium on surficial sediments beneath infiltration ponds at the INEL

  4. Energetics of magnesium, strontium, and barium doped lanthanum gallate perovskites

    International Nuclear Information System (INIS)

    Cheng Jihong; Navrotsky, Alexandra

    2004-01-01

    LaGaO 3 perovskites doped with Sr or Ba at the La site and Mg at the Ga site were prepared by solid-state reaction or sol-gel method and characterized. Enthalpies of formation from constituent oxides at 298 K were determined by high-temperature oxide melt solution calorimetry. Energetic trends are discussed in terms of defect chemistry. As oxygen deficiency increases, formation enthalpies define three trends, LaGa 1-y Mg y O 3-δ (LGM), La 1-x Sr x Ga 1-y Mg y O 3-δ (LSGM), and La 1-x Ba x Ga 1-y Mg y O 3-δ (LBGM). They become less exothermic with increasing doping, suggesting a dominant destabilization effect from oxygen vacancies. The endothermic enthalpy of vacancy formation is 275±37, 166±18 and 138±12 kJ/mol of V O ·· for LGM, LBGM and LSGM, respectively. Tolerance factor and ion size mismatch also affect enthalpies. In terms of energetics, Sr is the best dopant for the La site and Mg for the Ga site, supporting earlier studies, including oxygen ion conductivity and computer modeling

  5. Energetics of magnesium, strontium, and barium doped lanthanum gallate perovskites

    Science.gov (United States)

    Cheng, Jihong; Navrotsky, Alexandra

    2004-01-01

    LaGaO 3 perovskites doped with Sr or Ba at the La site and Mg at the Ga site were prepared by solid-state reaction or sol-gel method and characterized. Enthalpies of formation from constituent oxides at 298 K were determined by high-temperature oxide melt solution calorimetry. Energetic trends are discussed in terms of defect chemistry. As oxygen deficiency increases, formation enthalpies define three trends, LaGa 1- yMg yO 3- δ (LGM), La 1- xSr xGa 1- yMg yO 3- δ (LSGM), and La 1- xBa xGa 1- yMg yO 3- δ (LBGM). They become less exothermic with increasing doping, suggesting a dominant destabilization effect from oxygen vacancies. The endothermic enthalpy of vacancy formation is 275±37, 166±18 and 138±12 kJ/mol of VO·· for LGM, LBGM and LSGM, respectively. Tolerance factor and ion size mismatch also affect enthalpies. In terms of energetics, Sr is the best dopant for the La site and Mg for the Ga site, supporting earlier studies, including oxygen ion conductivity and computer modeling.

  6. Radiopaque strontium fluoroapatite glass-ceramics

    Directory of Open Access Journals (Sweden)

    Wolfram eHöland

    2015-10-01

    Full Text Available The controlled precipitation of strontium fluoroapatite crystals, was studied in four base glass compositions derived from the SiO2 – Al2O3 – Y2O3 – SrO – Na2O – K2O/Rb2O/Cs2O – P2O5 – F system. The crystal phase formation of these glasses and the main properties of the glass-ceramics, such as thermal and optical properties and radiopacity were compared with a fifth, a reference glass-ceramic. The reference glass-ceramic was characterized as Ca-fluoroapatite glass-ceramic. The four strontium fluoroapatite glass-ceramics showed the following crystal phases: a Sr5(PO43F – leucite, KAlSi2O6 , b Sr5(PO43F – leucite, KAlSi2O6, and nano-sized NaSrPO4 c Sr5(PO43F – pollucite, CsAlSiO4 , and nano-sized NaSrPO4, d Sr5(PO43F – Rb-leucite, RbAlSi2O6, and nano-sized NaSrPO4.The proof of crystal phase formation was possible by X-ray diffraction (XRD. The microstructures, which were studied using scanning electron microscopy (SEM demonstrated a uniform distribution of the crystals in the glass matrix. The Sr-fluoroapatites were precipitated based on an internal crystallization process, and the crystals demonstrated a needlelike morphology. The study of the crystal growth of needlelike Sr-fluoroapatites gave a clear evidence of an Ostwald ripening mechanism.The formation of leucite, pollucite and Rb-leucite was based on a surface crystallization mechanism. Therefore, a twofold crystallization mechanism was successfully applied to develop these types of glass-ceramics. The main focus of this study was the controlled development of glass-ceramics exhibiting high radiopacity in comparison to the reference glass-ceramic. This goal could be achieved with all four glass-ceramics with the preferred development of the Sr-fluoroapatite – pollucite-type glass-ceramic. In addition to this main development, it was possible to control the thermal properties. Especially the Rb-leucite containing glass-ceramic showed the highest coefficient of thermal

  7. Mechanoluminescence of Dy doped strontium aluminate nanophosphors

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Ravi, E-mail: rvsharma65@gmail.com [Department of Physics, Govt. Arts and Commerce Girls College, Raipur, C.G. 492001 (India); Bisen, D.P. [School of Studies in Physics and Astrophysics, Pt. Ravishankar Shukla University, Raipur, C.G. 492010 (India); Chandra, B.P. [Department of Postgraduate Studies and Research in Physics and Electronics, Rani Durgavati University, Jabalpur 482001 (India)

    2015-12-15

    Nanosized strontium aluminate phosphors activated with Dy{sup 3+} were prepared by a combustion method. Nanophosphor was prepared by this method at reaction temperatures as low as 600 °C. Powder X-ray diffraction (XRD), scanning electron microscope analysis was used to characterize the prepared product. The monoclinic phase was observed in the XRD pattern. The particle size of the samples was calculated around 35 nm. The SEM images show irregular shape of the prepared nanophosphor. Two peaks were found in the mechanoluminescence (ML) response curve plotted between time and ML intensity. The H{sub 3}BO{sub 3} added strontium aluminate phosphors activated with Dy show more bright ML peak as compared to the powders of SrAl{sub 2}O{sub 4}:Dy{sup 3+} without H{sub 3}BO{sub 3.} It was found that the PL and ML intensity increases with increasing concentration of Dy, it becomes maximum for 3% of Dy. The photoluminescence emission shows two intense fluorescence transitions peaks at 498 nm and 583 nm, {sup 4}F{sub 9/2}→{sup 6}H{sub 15/2} in the blue and {sup 4}F{sub 9/2}→{sup 6}H{sub 13/2} in the yellow-orange wavelength region. - Highlights: • Combustion synthesis route is used to prepare the SrAl{sub 2}O{sub 4}: Dy {sup 3+} nanophosphors. • The size of the synthesized sample was found to be in the nano-meter range. • The mechanoluminescence of SrAl{sub 2}O{sub 4}:Dy {sup 3+} nanophosphors is studied. • The photoluminescence of SrAl{sub 2}O{sub 4}: Dy {sup 3+} nanophosphors showed blue-shift as compared to bulk. • Effect of H{sub 3}BO{sub 3} on the mechanoluminescence of SrAl{sub 2}O{sub 4}:Dy{sup 3+} was studied.

  8. Stable strontium isotopic ratios from archaeological organic remains from the Thorsberg peat bog

    DEFF Research Database (Denmark)

    Nosch, Marie-Louise Bech; von Carnap-Bornheim, Claus; Grupe, Gisela

    2007-01-01

    Pilot study analysing stable strontium isotopic ratios from Iron Age textile and leather finds from the Thorsberg peat bog.......Pilot study analysing stable strontium isotopic ratios from Iron Age textile and leather finds from the Thorsberg peat bog....

  9. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... To Health Topics / Iron-Deficiency Anemia Iron-Deficiency Anemia Also known as Leer en español Iron-deficiency ... anemia. Blood tests to screen for iron-deficiency anemia To screen for iron-deficiency anemia, your doctor ...

  10. Iron-Deficiency Anemia

    Science.gov (United States)

    ... To Health Topics / Iron-Deficiency Anemia Iron-Deficiency Anemia Also known as Leer en español Iron-deficiency ... anemia. Blood tests to screen for iron-deficiency anemia To screen for iron-deficiency anemia, your doctor ...

  11. Flotation separation of strontium via phosphate precipitation.

    Science.gov (United States)

    Thanh, Luong H V; Liu, J C

    2017-06-01

    Flotation separation of strontium (Sr) from wastewater via phosphate precipitation was investigated. While 37.33% of Sr precipitated at highly alkaline pH in the absence of PO 4 3- , it completely precipitated as Sr 3 (PO 4 ) 2 at a molar ratio ([PO 4 3- ]:[Sr 2+ ]) of 0.62 at a lower pH value. The presence of Ca 2+ hindered Sr precipitation, yet it could be overcome by increasing the PO 4 3- dose. Sodium dodecyl sulfate (SDS) was a better collector for dispersed air flotation of Sr 3 (PO 4 ) 2 than cetyl trimethyl ammonium bromide, or mixed collector systems of SDS and saponin. The highest separation efficiency of 97.5% was achieved at an SDS dose of 40 mg/L. The main mechanism in the precipitate flotation is adsorption of anionic SDS on the positively charged surface of colloidal Sr 3 (PO 4 ) 2 via electrostatic interaction. SDS enhanced the aggregation of Sr 3 (PO 4 ) 2 precipitates as the size increased from 1.65 to 28.0 μm, which was beneficial to separation as well.

  12. Optical lattice clock with Strontium atoms

    International Nuclear Information System (INIS)

    Baillard, X.

    2008-01-01

    This thesis presents the latest achievements regarding the optical lattice clock with Strontium atoms developed at LNE-SYRTE. After a review of the different types of optical clocks that are currently under development, we stress on the concept of optical lattice clock which was first imagined for Sr 87 using the 1 S 0 → 3 P 0 transition. We exhibit the features of this atom, in particular the concept of magic wavelength for the trap, and the achievable performances for this kind of clock. The second part presents the experimental aspects, insisting particularly on the ultra-stable laser used for the interrogation of the atoms which is a central part of the experiment. Among the latest improvements, an optical pumping phase and an interrogation phase using a magnetic field have been added in order to refine the evaluation of the Zeeman effect. Finally, the last part presents the experimental results. The last evaluation of the clock using Sr 87 atoms allowed us to reach a frequency accuracy of 2.6*10 -15 and a measurement in agreement with the one made at JILA (Tokyo university) at the 10 -15 level. On another hand, thanks to recent theoretical proposals, we made a measurement using the bosonic isotope Sr 88 by adapting the experimental setup. This measurement represents the first evaluation for this type of clock, with a frequency accuracy of 7*10 -14 . (author)

  13. Measurements of cesium and strontium diffusion in biotite gneiss

    International Nuclear Information System (INIS)

    Skagius, K.; Neretnieks, I.

    1988-01-01

    A significant retardation of radionuclides transported by flowing water from an underground repository can be expected if the nuclides are able to diffuse into the water filled micropores in the rock. This diffusion into the pores will also increase the surface available to interactions between the nuclides in the ground water and the rock material, such as sorption. To calculate the retardation, it is necessary to know the sorption properties and the diffusivities in the rock matrix for the radionuclides. Diffusion experiments with cesium and strontium in biotite gneiss samples have been performed. Both the transport of strontium and cesium through rock samples and the concentration profiles of cesium and strontium inside rock samples have been determined. The result shows that diffusion of cesium and strontium occurs in the rock material. A diffusion model has been used to evaluate the diffusivity. Both pore diffusion and surface diffusion had to be included in the model to give good agreement with the experimental data. If surface diffusion is not included in the model, the effective pore diffusivity that gives the best fit to the experimental data is found to be higher than expected from earlier measurement of iodide diffusion in the same type of rock material. This indicates that the diffusion of cesium and strontium (sorbing components) in rock material is caused by both pore diffusion and surface diffusion acting in parallel

  14. Accumulation of strontium 90 and cesium 137 in some hydrobionts

    International Nuclear Information System (INIS)

    Boyadzhiev, A.; Keslev, D.; Kerteva, A.; Novakova, E.

    1974-01-01

    Factors responsible for the accumulation of strontium 90 and cesium 137 in some plant organisms, characteristic for fishes in Bulgarian fresh-water reservoirs and in Black Seawater, were examined. The investigated samples were taken during spring, summer and autumn-winter seasons 1967/1968. Each sample burnt to ashes at 450 0 C was examined for strontium 90 and cesium 137 content as well as stable isotopes of calcuim and potassium. Accumulation factors for strontium 90 and cesium 137 were significantly higher in freshwater hydrobionts than in seawater hydrobionts. This could be explained by variations in the concentration of stable isotopes of calcium and potassium from freshwater reservoirs and from seawater. Potassium and calcium concentrations were relatively constant in seawater while in freshwater they were significantly variable. Accumulation factors for these radionuclides increased according to the amount of rain and the altitude above sea level. Strontium 90 was deposited mostly in fins, less in scales and least in the meat of fishes; cesium 137 was mainly deposited in the meat and less in the other parts of fishes. The highest accumulation factors for strontium 90 were determined in fishes and for cesium 137 in plant organisms. The most convenient plant and fish species for tracing radioactive contamination of freshwater reservoirs and in the Black Sea were indicated. (A.B.)

  15. A process for the development of strontium hydroxyapatite

    International Nuclear Information System (INIS)

    Zahra, N.; Fayyaz, M.; Iqbal, W.; Irfan, M.; Alam, S.

    2013-01-01

    A procedure for the preparation of Strontium Hydroxyapatite is adapted to produce high purity and better homogeneity ceramic with good Crystallinity. The strontium substituted bone cement has potential for use in orthopedic surgeries. Ionic Strontium (Sr) in humans shares the same physiological pathway as calcium and can be deposited in the mineral structure of the bone. In the present study, a novel concept of preparing Sr-contained Hydroxyapatite bone cement by using a precipitation method is proposed to get an ideal biomaterial that possesses potential degradability and more excellent pharmacological effect. Chemical analysis, Fourier Transform Infra Red analysis and Thermogravimetric/ Differential Scanning Calorimetric studies were conducted on prepared Strontium Hydroxyapatite sample to characterize the incorporation of 15 percentage Sr2+ into the crystal lattice of Hydroxyapatite. Strontium was quantitatively incorporated into Hydroxyapatite where its substitution for calcium provoked a linear shift of the infrared absorption bands of the hydroxyl and phosphate groups. Thus, the formation of Sr-HAp was confirmed by Chemical Analysis, FT-IR and TGA/DSC results. (author)

  16. Investigation of Varied Strontium-Transuranic Precipitation Chemistries for Crossflow

    International Nuclear Information System (INIS)

    Nash, C.A.

    2000-01-01

    Precipitation chemistries for strontium and transuranic (TRU) removal have been tested for crossflow filterability and lanthanide removal with simulants of Hanford tank 241-AN-107 supernate. This is the initial work indicating the usefulness of a strontium and permanganate precipitation process as applied to the Hanford River Protection Project. Precipitations with both ferric and ferrous iron were shown to be at least two orders of magnitude less filterable than a 0.1 gpm/ft target average flux that was desired at the time. A precipitate from a strontium nitrate strike alone was found to filter easily and to make the desired average flux. Other chemistries tested included precipitant of lanthanum(III), nickel (II), calcium (II), and a redox chemistry using sodium permanganate. Of these chemistries a strontium and permanganate strike including calcium provided the highest filter flux compared to the other chemistries. It showed the most promise in lanthanide removal as well. This work provides a promising direction for further work to achieve both acceptable filterability and decontamination for Envelope C wastes to be treated by the Hanford River Protection Project. The work reported here was originally intended to satisfy needs for crossflow filter testing of a strontium and ferric precipitation method for treating Envelope C using a 241-AN-107 simulant

  17. Method for strontium isolation from high-mineralized water

    International Nuclear Information System (INIS)

    Evzhanov, Kh.; Andriyasova, G.M.

    1983-01-01

    A method to isolate strontium from high-mineralized waters containing sodium, magnesium, calcium and strontium chlorides, which differ from the prototype method in a considerable decrease in energy consumption with the preservation of a high degree of Sr, Mg and Ca isolation selectivity, has been suggested. According to the method suggested mineralized waters are treated with alkali (NaOH) in the amount of 95-97% of stoichiometry by magnesium, then after separation of magnesium hydroxide precipitate mother liquor is treated with sodium carbonate in the amount of 50-60% of stoichiometry by calcium. After separation of calcium carbonate precipitate mother liquor is treated with NaOH in the amount of 130-135% of stoichiometry by calcium. After separation of calcium hydroxide precipitate from mother liquor by means of sodium carbonate introduction strontium carbonate is isolated. The degree of strontium extraction in the form of SrCO 3 constitutes 90.5% of its content in the initial solution. The method presented can be used for strontium separation from natural and waste waters

  18. Diffusion measurements of cesium and strontium in biotite gneiss

    International Nuclear Information System (INIS)

    Skagius, K.; Neretnieks, I.

    1985-01-01

    A significant retardation of radionuclides transported by flowing water from an underground repository can be expected if the nuclides are able to diffuse into the water filled micropores in the rock. This diffusion into the pores will also increase the surface available to interaction between the nuclides in the groundwater and the rock material, such as sorption. To calculate the retardation it is necessary to know the sorption properties and the diffusivities in the rock matrix for the radionuclides. Diffusion experiments with cesium and strontium in biotite gneiss samples have been performed. Both the transport of strontium and cesium through rock samples and the concentration profiles of cesium and strontium inside rock samples have been determined. The result show that diffusion of cesium and strontium occurs in the rock material. A diffusion model has been used to evaluate the diffusivity. Both pore diffusion and surface diffusion had to be included in the model to give good agreement with the experimental data. If surface diffusion is not included in the model, the effective pore diffusivity that gives the best fit to the experimental data is found to be higher than expected from earlier measurements of iodide diffusion in the same type of rock material. This indicates that the diffusion of cesium and strontium (sorbing components) in rock material is caused by both pore diffusion and surface diffusion acting in parallel. (author)

  19. A process for the development of strontium hydroxyapatite

    International Nuclear Information System (INIS)

    Zahra, N; Fayyaz, M; Iqbal, W; Irfan, M; Alam, S

    2014-01-01

    A procedure for the preparation of Strontium Hydroxyapatite is adapted to produce high purity and better homogeneity ceramic with good Crystallinity. The strontium substituted bone cement has potential for use in orthopedic surgeries. Ionic Strontium (Sr) in humans shares the same physiological pathway as calcium and can be deposited in the mineral structure of the bone. In the present study, a novel concept of preparing Sr-contained Hydroxyapatite bone cement by using a precipitation method is proposed to get an ideal biomaterial that possesses potential degradability and more excellent pharmacological effect. Chemical analysis, Fourier Transform Infra Red analysis and Thermogravimetric/ Differential Scanning Calorimetric studies were conducted on prepared Strontium Hydroxyapatite sample to characterize the incorporation of 15% Sr 2 + into the crystal lattice of Hydroxyapatite. Strontium was quantitatively incorporated into Hydroxyapatite where its substitution for calcium provoked a linear shift of the infrared absorption bands of the hydroxyl and phosphate groups. Thus, the formation of Sr-HAp was confirmed by Chemical Analysis, FT-IR and TGA/DSC results

  20. A process for the development of strontium hydroxyapatite

    Science.gov (United States)

    Zahra, N.; Fayyaz, M.; Iqbal, W.; Irfan, M.; Alam, S.

    2014-06-01

    A procedure for the preparation of Strontium Hydroxyapatite is adapted to produce high purity and better homogeneity ceramic with good Crystallinity. The strontium substituted bone cement has potential for use in orthopedic surgeries. Ionic Strontium (Sr) in humans shares the same physiological pathway as calcium and can be deposited in the mineral structure of the bone. In the present study, a novel concept of preparing Sr-contained Hydroxyapatite bone cement by using a precipitation method is proposed to get an ideal biomaterial that possesses potential degradability and more excellent pharmacological effect. Chemical analysis, Fourier Transform Infra Red analysis and Thermogravimetric/ Differential Scanning Calorimetric studies were conducted on prepared Strontium Hydroxyapatite sample to characterize the incorporation of 15% Sr2+ into the crystal lattice of Hydroxyapatite. Strontium was quantitatively incorporated into Hydroxyapatite where its substitution for calcium provoked a linear shift of the infrared absorption bands of the hydroxyl and phosphate groups. Thus, the formation of Sr-HAp was confirmed by Chemical Analysis, FT-IR and TGA/DSC results.

  1. Spectroscopy and Laser-SNMS on stable and radioactive strontium

    Energy Technology Data Exchange (ETDEWEB)

    Bosco, Hauke; Walther, Clemens [Institut fuer Radiooekologie und Strahlenschutz, Leibniz Universitaet Hannover (Germany); Franzmann, Michael [Institut fuer Radiooekologie und Strahlenschutz, Leibniz Universitaet Hannover (Germany); Institut fuer Physik, Johannes Gutenberg Universitaet Mainz (Germany); Kron, Tobias; Wendt, Klaus [Institut fuer Physik, Johannes Gutenberg Universitaet Mainz (Germany)

    2016-07-01

    Nuclear accidents as experienced e.g. in Chernobyl or Fukushima and nuclear weapon tests released considerable activity levels and a variety of medium to long-lived radionuclides into the environment. Strontium-90 appears as a significant share of the fission products in spent nuclear fuel and correspondingly in any possible release. Due to its chemical properties it is subject to long range transport through the environment and can cause considerable dose to man when entering the food chain. Correspondingly, the investigation of speciation and migration channels is of major relevance. A radioanalytical approach is severely hampered by the low beta energy of the strontium-90 decay and the need to separate strontium-90 from the secular equilibrated daughter yttrium-90. Hence, application of a mass spectrometric method without chemical separation of the elements is a promising alternative for low-level investigation of strontium-90. Application of the new Laser-SNMS system at IRS Hannover could well suit those needs. It applies three Ti:Sa lasers for resonant ionization of neutral atoms produced by primary ion sputtering in a SIMS together with a time-of-flight mass analysis which provides high spatial resolution. The analytical measurements are preceded by spectroscopic studies on the level structure of strontium to develop a most efficient ionization scheme.

  2. Investigation of Varied Strontium-Transuranic Precipitation Chemistries for Crossflow

    Energy Technology Data Exchange (ETDEWEB)

    Nash, C.A.

    2000-07-27

    Precipitation chemistries for strontium and transuranic (TRU) removal have been tested for crossflow filterability and lanthanide removal with simulants of Hanford tank 241-AN-107 supernate. This is the initial work indicating the usefulness of a strontium and permanganate precipitation process as applied to the Hanford River Protection Project. Precipitations with both ferric and ferrous iron were shown to be at least two orders of magnitude less filterable than a 0.1 gpm/ft target average flux that was desired at the time. A precipitate from a strontium nitrate strike alone was found to filter easily and to make the desired average flux. Other chemistries tested included precipitant of lanthanum(III), nickel (II), calcium (II), and a redox chemistry using sodium permanganate. Of these chemistries a strontium and permanganate strike including calcium provided the highest filter flux compared to the other chemistries. It showed the most promise in lanthanide removal as well. This work provides a promising direction for further work to achieve both acceptable filterability and decontamination for Envelope C wastes to be treated by the Hanford River Protection Project. The work reported here was originally intended to satisfy needs for crossflow filter testing of a strontium and ferric precipitation method for treating Envelope C using a 241-AN-107 simulant.

  3. Column studies of strontium and cesium migration in a granular geologic material

    International Nuclear Information System (INIS)

    Reynolds, W.D.; Gilham, R.W.; Cherry, J.A.

    1981-06-01

    Infinite-pulse, miscible-displacement experiments were conducted to investigate the applicability of batch Ksub(d) values in the prediction of reactive solute transport during dynamic flow through porous media. Non-reactive tracers (chloride, tritium and oxygen-18), and the reactive tracers (strontium-85 and cesium-137) were passed through a column 5.0 cm long and 6.5 cm in diameter packed with a medium to fine sand. The effluent concentrations of the nonreactive solutes were accurately predicted using the advection-dispersion equation; however, there were large discrepancies between the measured and predicted effluent concentrations for both reactive species. Good agreement was obtained between the measured and computed results by incorporating an empirical isotherm into the advection-dispersion model

  4. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... you are diagnosed with iron-deficiency anemia. Risk Factors You may have an increased risk for iron- ... iron-deficiency anemia if you have certain risk factors , including pregnancy. To prevent iron-deficiency anemia, your ...

  5. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... to moderate iron-deficiency anemia, or red blood cell transfusion for severe iron-deficiency anemia. You may ... body needs iron to make healthy red blood cells. Iron-deficiency anemia usually develops over time because ...

  6. Vitamin Deficiency Anemia

    Science.gov (United States)

    ... are unique to specific vitamin deficiencies. Folate-deficiency anemia risk factors include: Undergoing hemodialysis for kidney failure. ... the metabolism of folate. Vitamin B-12 deficiency anemia risk factors include: Lack of intrinsic factor. Most ...

  7. Placental transfer of calcium and strontium and of their radionuclides

    International Nuclear Information System (INIS)

    Griessl, I.; Stieve, F.E.

    1987-11-01

    The first part of the report deals with the occurrence and the chemistry of strontium and its radioisotopes, and the second part discusses the calcium and the strontium metabolism in man. General information on the biology and physiology of the human skeleton is given in part 3, whereas part 4 again discusses the calcium and strontium metabolism in man, however with particular emphasis on the conditions during pregnancy and lactation. Part 5 presents an evaluation of the literature in this subject field, concentrating on results obtained with experimental animals such as cows, swine, dogs, guinea pigs, rats, and mice, and discusses the applicability of these findings to the conditions in man. An annex presents data on the yttrium metabolism in man and animal. (MG) [de

  8. Bulgarian regional patterns of contamination by global fallout (strontium 90)

    International Nuclear Information System (INIS)

    Boyadzhiev, A.; Shopov, N.; Simova, G.; Andreev, E.; Mikha lov, M.G.

    1980-01-01

    For selected districts in the country, mean annual atmospheric precipitation rates were related to strontium-90 contents in milk over the period 1970-1977. Strontium-90 in milk was determined by the method of Popov, using Va-Z-310 counters for activity measurements. The impact of annual precipitation means was examined by monofactorial spread analysis, with sites distributed into three groups according to precipitation rates observed over longer time periods: up to 650 l/m 2 from 650 to 750 l/m 2 ; and above 750 L/M 2 . Values of coefficient F were estimated, representing the ratio of group to random spreads. These figures were compared with critical values in Student's tables for 0.05 significance level. The F data indicated a definite alternative relationship to exist between strontium-90 amounts in mils and annual precipitation rates, which is prognostically meaningful from the strandpoint of radiological protection of the population

  9. Strontium titanate thin film deposition - structural and electronical characterization

    Energy Technology Data Exchange (ETDEWEB)

    Hanzig, Florian; Hanzig, Juliane; Stoecker, Hartmut; Mehner, Erik; Abendroth, Barbara; Meyer, Dirk C. [TU Bergakademie Freiberg, Institut fuer Experimentelle Physik (Germany); Franke, Michael [TU Bergakademie Freiberg, Institut fuer Elektronik- und Sensormaterialien (Germany)

    2012-07-01

    Strontium titanate is on the one hand a widely-used model oxide for solids which crystallize in perovskite type of structure. On the other hand, with its large band-gap energy and its mixed ionic and electronic conductivity, SrTiO{sub 3} is a promising isolating material in metal-insulator-metal (MIM) structures for resistive switching memory cells. Here, we used physical vapour deposition methods (e. g. electron-beam and sputtering) to produce strontium titanate layers. Sample thicknesses were probed with X-ray reflectometry (XRR) and spectroscopic ellipsometry (SE). Additionally, layer densities and dielectric functions were quantified with XRR and SE, respectively. Using infrared spectroscopy free electron concentrations were obtained. Phase and element composition analysis was carried out with grazing incidence X-ray diffraction and X-ray photoelectron spectroscopy. Subsequent temperature treatment of samples lead to crystallization of the initially amorphous strontium titanate.

  10. Oxygen Therapy

    Science.gov (United States)

    ... their breathing to dangerously low levels. Will I need oxygen when I sleep? Usually if you use supplemental oxygen during the ... your health care provider tells you you only need to use oxygen for exercise or sleep. Even if you feel “fine” off of your ...

  11. Improved Internal Reference Oxygen Sensors with Composite Ceramic Electrodes

    DEFF Research Database (Denmark)

    Hu, Qiang; Jacobsen, Torben; Hansen, Karin Vels

    2012-01-01

    Potentiometric oxygen sensors with an internal reference electrode, which uses the equilibrium pO2 of the binary mixture of Ni/NiO as the reference, are demonstrated. The cells employ Pt or composite ceramics as the sensing electrode. The cells are fabricated by a flexible and potentially low cost...... and performance are highly reproducible. The composite ceramics, based on strontium doped manganite and yttria doped zirconia, are proven superior over Pt to serve as the electrode material....

  12. Strontium effects on root dentin tubule occlusion and nanomechanical properties.

    Science.gov (United States)

    Saeki, Kuniko; Marshall, Grayson W; Gansky, Stuart A; Parkinson, Charles R; Marshall, Sally J

    2016-02-01

    Dentin hypersensitivity often is treated by promotion of dentin tubule occlusion. In this in vitro study we evaluated nanomechanical properties and degree of tubule occlusion conferred to sound and demineralized human root dentin following treatment with a 10% (w/w) strontium acetate solution and its relation to the treatment duration and delivery method. 24 human cervical root dentin disks (8 groups of 3) were polished through 0.25 μm. 12 disks were subjected to an acid challenge (1% citric acid, pH 3.8) for 2 min. The specimens were incubated in artificial saliva, treated by soaking or brushing with deionized (DI) water or a solution of 10% strontium acetate for 2 min twice a day for 28 days. The occlusion percent and nanomechanical properties were determined at the baseline, 5, 14 and 28 days. Cross-sectioned specimens were prepared to evaluate the depth affected by strontium acetate / dentin interaction by SEM. Statistical analysis was performed using linear mixed effects models. A 10% strontium acetate treatment over 5-28 days significantly increased tubule occlusion for normal root dentin and to a lesser extent for demineralized dentin and increased the AFM based nanomechanical properties of demineralized dentin. Brushing was more effective than soaking in recovery of properties of demineralized dentin when treated with strontium. No difference in tubuleocclusion was found between the two delivery methods. Strontium acetate itself proved to have the ability to occlude dentin tubules and result in small changes in the mechanical properties of dentin. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  13. Radiopaque Strontium Fluoroapatite Glass-Ceramics

    Science.gov (United States)

    Höland, Wolfram; Schweiger, Marcel; Dittmer, Marc; Ritzberger, Christian

    2015-01-01

    The controlled precipitation of strontium fluoroapatite crystals was studied in four base glass compositions derived from the SiO2–Al2O3–Y2O3–SrO–Na2O–K2O/Rb2O/Cs2O–P2O5–F system. The crystal phase formation of these glasses and the main properties of the glass-ceramics, such as thermal and optical properties and radiopacity were compared with a fifth, a reference glass-ceramic. The reference glass-ceramic was characterized as Ca-fluoroapatite glass-ceramic. The four strontium fluoroapatite glass-ceramics showed the following crystal phases: (a) Sr5(PO4)3F – leucite, KAlSi2O6, (b) Sr5(PO4)3F – leucite, KAlSi2O6, and nano-sized NaSrPO4, (c) Sr5(PO4)3F – pollucite, CsAlSi2O6, and nano-sized NaSrPO4, and (d) Sr5(PO4)3F – Rb-leucite, RbAlSi2O6, and nano-sized NaSrPO4. The proof of crystal phase formation was possible by X-ray diffraction. The microstructures, which were studied using scanning electron microscopy, demonstrated a uniform distribution of the crystals in the glass matrix. The Sr-fluoroapatites were precipitated based on an internal crystallization process, and the crystals demonstrated a needle-like morphology. The study of the crystal growth of needle-like Sr-fluoroapatites gave a clear evidence of an Ostwald ripening mechanism. The formation of leucite, pollucite, and Rb-leucite was based on a surface crystallization mechanism. Therefore, a twofold crystallization mechanism was successfully applied to develop these types of glass-ceramics. The main focus of this study was the controlled development of glass-ceramics exhibiting high radiopacity in comparison to the reference glass-ceramic. This goal could be achieved with all four glass-ceramics with the preferred development of the Sr-fluoroapatite – pollucite-type glass-ceramic. In addition to this main development, it was possible to control the thermal properties. Especially the Rb-leucite containing glass-ceramic showed the highest coefficient of thermal

  14. Radiopaque Strontium Fluoroapatite Glass-Ceramics.

    Science.gov (United States)

    Höland, Wolfram; Schweiger, Marcel; Dittmer, Marc; Ritzberger, Christian

    2015-01-01

    The controlled precipitation of strontium fluoroapatite crystals was studied in four base glass compositions derived from the SiO2-Al2O3-Y2O3-SrO-Na2O-K2O/Rb2O/Cs2O-P2O5-F system. The crystal phase formation of these glasses and the main properties of the glass-ceramics, such as thermal and optical properties and radiopacity were compared with a fifth, a reference glass-ceramic. The reference glass-ceramic was characterized as Ca-fluoroapatite glass-ceramic. The four strontium fluoroapatite glass-ceramics showed the following crystal phases: (a) Sr5(PO4)3F - leucite, KAlSi2O6, (b) Sr5(PO4)3F - leucite, KAlSi2O6, and nano-sized NaSrPO4, (c) Sr5(PO4)3F - pollucite, CsAlSi2O6, and nano-sized NaSrPO4, and (d) Sr5(PO4)3F - Rb-leucite, RbAlSi2O6, and nano-sized NaSrPO4. The proof of crystal phase formation was possible by X-ray diffraction. The microstructures, which were studied using scanning electron microscopy, demonstrated a uniform distribution of the crystals in the glass matrix. The Sr-fluoroapatites were precipitated based on an internal crystallization process, and the crystals demonstrated a needle-like morphology. The study of the crystal growth of needle-like Sr-fluoroapatites gave a clear evidence of an Ostwald ripening mechanism. The formation of leucite, pollucite, and Rb-leucite was based on a surface crystallization mechanism. Therefore, a twofold crystallization mechanism was successfully applied to develop these types of glass-ceramics. The main focus of this study was the controlled development of glass-ceramics exhibiting high radiopacity in comparison to the reference glass-ceramic. This goal could be achieved with all four glass-ceramics with the preferred development of the Sr-fluoroapatite - pollucite-type glass-ceramic. In addition to this main development, it was possible to control the thermal properties. Especially the Rb-leucite containing glass-ceramic showed the highest coefficient of thermal expansion (CTE). These

  15. ADSORPTION OF STRONTIUM IONS FROM WATER ON MODIFIED ACTIVATED CARBONS

    Directory of Open Access Journals (Sweden)

    Mihai Ciobanu

    2016-12-01

    Full Text Available Adsorption of strontium ions from aqueous solutions on active carbons CAN-7 and oxidized CAN-8 has been studied. It has been found that allure of the adsorption isotherms for both studied active carbons are practically identical. Studies have shown that the adsorption isotherms for strontium ions from aqueous solutions are well described by the Langmuir and Dubinin-Radushkevich equations, respectively. The surface heterogeneity of activated carbons CAN-7 and oxidized CAN-8 has been assessed by using Freundlich equation.

  16. Conductivity and thermodynamic characteristic of superionic transition in strontium chloride

    International Nuclear Information System (INIS)

    Voronin, B.M.; Prisyazhnyj, V.D.

    1989-01-01

    Electric conductivity of strontium polycrystalline chloride in the wide temperature range including melting point is measured. Reciprocally caused anomalous behaviour of kinetic and thermodynamic properties, which relates to peculiarities of salt transition to a superionic state is established in the region of high temperatures. Thermodynamic functions corresponding to crystal anion sublattice disordering are determined and characterized. Comparative analysis of data on strontium chloride and other structural-like salts testifies about step-by-step washing-out character of superionic transition, and the depth of transition (the degree of disordering) reached at melting points relates regularly to relative sizes of cations and anions in the fluorite lattice

  17. Spectrographic determination of strontium in yttrium-90 solutions

    International Nuclear Information System (INIS)

    Roca, M.; Capdevila, C.

    1970-01-01

    The copper spark method has been used for determining strontium in the concentration range 1-100 g/ml in yttrium-90 solutions containing 0,5 % or thereabouts of ammonium citrate. The influence of the citric acid as well as the ammonium citrate with regard to 2N HCL solutions has been studied: the citric acid enhances the line intensities of strontium. The employment of either barium or lanthanum as reference element compensates for this enhancement. Because of the increase in sensitivity mentioned above, the study of influence of the citric acid has been extended and several impurities usually determined in radioisotope solutions have been considered. (Author) 4 refs

  18. Dielectric loss of strontium titanate thin films

    Science.gov (United States)

    Dalberth, Mark Joseph

    1999-12-01

    Interest in strontium titanate (STO) thin films for microwave device applications continues to grow, fueled by the telecommunications industry's interest in phase shifters and tunable filters. The optimization of these devices depends upon increasing the phase or frequency tuning and decreasing the losses in the films. Currently, the dielectric response of thin film STO is poorly understood through lack of data and a theory to describe it. We have studied the growth of STO using pulsed laser deposition and single crystal substrates like lanthanum aluminate and neodymium gallate. We have researched ways to use ring resonators to accurately measure the dielectric response as a function of temperature, electric field, and frequency from low radio frequencies to a few gigahertz. Our films grown on lanthanum aluminate show marked frequency dispersion in the real part of the dielectric constant and hints of thermally activated loss behavior. We also found that films grown with conditions that optimized the dielectric constant showed increased losses. In an attempt to simplify the system, we developed a technique called epitaxial lift off, which has allowed us to study films removed from their growth substrates. These free standing films have low losses and show obvious thermally activated behavior. The "amount of tuning," as measured by a figure of merit, KE, is greater in these films than in the films still attached to their growth substrates. We have developed a theory that describes the real and imaginary parts of the dielectric constant. The theory models the real part using a mean field description of the ionic motion in the crystal and includes the loss by incorporating the motion of charged defects in the films.

  19. Crystal structure of strontium dinickel iron orthophosphate

    Directory of Open Access Journals (Sweden)

    Said Ouaatta

    2015-10-01

    Full Text Available The title compound, SrNi2Fe(PO43, synthesized by solid-state reaction, crystallizes in an ordered variant of the α-CrPO4 structure. In the asymmetric unit, two O atoms are in general positions, whereas all others atoms are in special positions of the space group Imma: the Sr cation and one P atom occupy the Wyckoff position 4e (mm2, Fe is on 4b (2/m, Ni and the other P atom are on 8g (2, one O atom is on 8h (m and the other on 8i (m. The three-dimensional framework of the crystal structure is built up by [PO4] tetrahedra, [FeO6] octahedra and [Ni2O10] dimers of edge-sharing octahedra, linked through common corners or edges. This structure comprises two types of layers stacked alternately along the [100] direction. The first layer is formed by edge-sharing octahedra ([Ni2O10] dimer linked to [PO4] tetrahedra via common edges while the second layer is built up from a strontium row followed by infinite chains of alternating [PO4] tetrahedra and FeO6 octahedra sharing apices. The layers are held together through vertices of [PO4] tetrahedra and [FeO6] octahedra, leading to the appearance of two types of tunnels parallel to the a- and b-axis directions in which the Sr cations are located. Each Sr cation is surrounded by eight O atoms.

  20. Strontium stable isotope behaviour accompanying basalt weathering

    Science.gov (United States)

    Burton, K. W.; Parkinson, I. J.; Gíslason, S. G. R.

    2016-12-01

    The strontium (Sr) stable isotope composition of rivers is strongly controlled by the balance of carbonate to silicate weathering (Krabbenhöft et al. 2010; Pearce et al. 2015). However, rivers draining silicate catchments possess distinctly heavier Sr stable isotope values than their bedrock compositions, pointing to significant fractionation during weathering. Some have argued for preferential release of heavy Sr from primary phases during chemical weathering, others for the formation of secondary weathering minerals that incorporate light isotopes. This study presents high-precision double-spike Sr stable isotope data for soils, rivers, ground waters and estuarine waters from Iceland, reflecting both natural weathering and societal impacts on those environments. The bedrock in Iceland is dominantly basaltic, d88/86Sr ≈ +0.27, extending to lighter values for rhyolites. Geothermal waters range from basaltic Sr stable compositions to those akin to seawater. Soil pore waters reflect a balance of input from primary mineral weathering, precipitation and litter recycling and removal into secondary phases and vegetation. Rivers and ground waters possess a wide range of d88/86Sr compositions from +0.101 to +0.858. Elemental and isotope data indicate that this fractionation primarily results from the formation or dissolution of secondary zeolite (d88/86Sr ≈ +0.10), but also carbonate (d88/86Sr ≈ +0.22) and sometimes anhydrite (d88/86Sr ≈ -0.73), driving the residual waters to heavier or lighter values, respectively. Estuarine waters largely reflect mixing with seawater, but are also be affected by adsorption onto particulates, again driving water to heavy values. Overall, these data indicate that the stability and nature of secondary weathering phases, exerts a strong control on the Sr stable isotope composition of silicate rivers. [1] Krabbenhöft et al. (2010) Geochim. Cosmochim. Acta 74, 4097-4109. [2] Pearce et al. (2015) Geochim. Cosmochim. Acta 157, 125-146.

  1. Oxygen Therapy

    Directory of Open Access Journals (Sweden)

    Bonnie Solmes

    2000-01-01

    Full Text Available LTOT is prescribed for people with chronic lung disease in whom there is a decrease in the ability of the lungs to supply enough oxygen to the body. The heart is obliged to pump faster to meet the body's oxygen requirements. This may place undue stress on the heart, resulting in palpitations, dizziness and fatigue. A low oxygen level in arterial blood is also harmful to the heart, the brain and the pulmonary blood vessels. Oxygen therapy is used to break this cycle. A person with low blood oxygen will often be able to accomplish more with less fatigue with the help of supplemental oxygen therapy. Shortness of breath is a mechanical problem resulting from the effects of chronic obstructive pulmonary disease. Oxygen therapy may or may not reduce shortness of breath, but it will help the lungs and heart to function with less stress.

  2. Antimony doped barium strontium ferrite perovskites as novel cathodes for intermediate-temperature solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Ling, Yihan, E-mail: lyhyy@mail.ustc.edu.cn [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou, 221116 (China); Lu, Xiaoyong [China Anhui Key Laboratory of Low Temperature Co-fired Materials, Department of Chemistry, Huainan Normal University, Huainan, Anhui, 232001 (China); Niu, Jinan; Chen, Hui [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou, 221116 (China); Ding, Yanzhi [China Anhui Key Laboratory of Low Temperature Co-fired Materials, Department of Chemistry, Huainan Normal University, Huainan, Anhui, 232001 (China); Ou, Xuemei [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou, 221116 (China); Zhao, Ling [Department of Material Science and Chemistry, China University of Geosciences, Wuhan, 430074 (China)

    2016-05-05

    Antimony was doped to barium strontium ferrite to produce ferrite-based perovskites with a composition of Ba{sub 0.5}Sr{sub 0.5}Fe{sub 1−x}Sb{sub x}O{sub 3−δ} (x = 0.0, 0.05, 0.1) as novel cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The perovskite properties including oxygen nonstoichiometry (δ), mean valence of B-site, tolerance factors, thermal expansion coefficient (TEC) and electrical conductivity (σ) are explored as a function of antimony content. By defect chemistry analysis, the TECs decrease since the variable oxygen vacancy concentration is decreased by Sb doping, and σ decreases with x due to the reduced charge concentration of Fe{sup 4+} content. Consequently, the electrochemical performance was substantially improved and the interfacial polarization resistance was reduced from 0.213 to 0.120 Ωcm{sup 2} at 700 °C with Sb doping. The perovskite with x = 1.0 is suggested as the most promising composition as SOFC cathode material. - Highlights: • Antimony is doped to barium strontium ferrite to produce novel cathodes. • δ, TECs and σ are evaluated as a function of antimony content. • The electrochemical performance is substantially improved with antimony doping.

  3. Novel Pharmaceutical Strontium Malonate Influence on Calcium and Strontium Adsorption by Dog Femur and by Dog Teeth in a Four-Week Toxicity Study

    DEFF Research Database (Denmark)

    Raffalt, Anders Christer; Christgau, Stephan; Andersen, Jens Enevold Thaulov

    of osteoporosis. As part of this development the compound was administered in doses of 0 (placebo), 300, 1000 and 3000 mg/kg/day to beagle dogs for a period of 4 weeks. We measured the incorporation of strontium in bone, marrow and teeth in this study. Analysis by inductively coupled plasma mass spectrometry...... marginally higher incorporation of strontium suggesting that saturation levels were reached with the lowest dose level. There was no gender difference in strontium incorporation. Correlations of strontium levels with Sr/Ca-ratio and other important biological parameters were investigated....

  4. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Iron-Deficiency Anemia Iron-Deficiency Anemia Also known as Leer en español Iron-deficiency anemia is a ... address the cause of your iron deficiency, such as any underlying bleeding. If undiagnosed or untreated, iron- ...

  5. Optical response of oxygen deficient La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films deposited by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Cesaria, M., E-mail: maura.cesaria@le.infn.it [Department of Mathematics and Physics “Ennio De Giorgi”, University of Salento, Via Arnesano, 73100 Lecce (Italy); Caricato, A.P.; Leggieri, G.; Martino, M. [Department of Mathematics and Physics “Ennio De Giorgi”, University of Salento, Via Arnesano, 73100 Lecce (Italy); Maruccio, G. [Department of Mathematics and Physics “Ennio De Giorgi”, University of Salento, Via Arnesano, 73100 Lecce (Italy); National Nanotechnology Laboratory (NNL)-Nanoscience Institute-CNR, Via Arnesano, 73100 Lecce (Italy)

    2013-10-31

    The optical response of 200 nm thick La{sub 0.7}Sr{sub 0.3}MnO{sub (3−δ)} films, deposited by pulsed laser deposition on amorphous silica substrates heated at nearly 600 °C, under different oxygen pressures (0.1 Pa, 0.5 Pa, 1 Pa, 5 Pa and 10 Pa), is reported. The effects of the oxygen non-stoichiometry are investigated at room temperature dealing with the absorption coefficient and the Tauc's plot method rather than conventional optical conductivity. The absorption curves are evaluated by an algorithm able to realistically describe the behavior of thin films without exploiting numerical extrapolations or simplified theoretical models or ab-initio calculations. Optical features, tunable by the growth oxygen pressure, are discussed based on the known theoretical and experimental scenario. - Highlights: • Overview of the La{sub 0.7}Sr{sub 0.3}MnO{sub 3} basics to highlight basic questions to be assessed. • Optical analysis by the absorption coefficient rather than optical conductivity. • Realistic absorption response that avoids numerical refinements and simulations. • Analysis of the role of oxygen vacancies in tuning the electronic dispersion. • First investigation of direct and indirect transitions by the Tauc's plot.

  6. Thermal behaviour of strontium tartrate single crystals grown in gel

    Indian Academy of Sciences (India)

    Unknown

    Keywords. Strontium tartrate; dopant; effect of magnetic field; thermal behaviour. 1. Introduction ... tals of such type of compounds cannot be grown by either slow evaporation or ... is observed under a stereo binocular microscope (Carl. Zeiss) and ... a depth of 1⋅8 cm due to the diffusion of the top solution. After about a week ...

  7. New Composite Sorbents for Caesium and Strontium Ions Sorption

    Directory of Open Access Journals (Sweden)

    Mykola Kartel

    2017-06-01

    Full Text Available Composite lignocellulose-inorganic sorbents derived from plant residues of agriculture and food industry, modified with ferrocyanides of d-metals and hydrated antimony pentoxide were prepared. Caesium and strontium ions removal from water was tested by radiotracer method. Sorption of heavy metal ions, methylene blue, gelatin, vitamin B12 was also studied.

  8. Thermal behaviour of strontium tartrate single crystals grown in gel

    Indian Academy of Sciences (India)

    Thermal behaviour of strontium tartrate crystals grown with the aid of sodium metasilicate gel is investigated using thermogravimetry (TG) and differential thermal analysis (DTA). Effect of magnetic field and dopant (Pb)2+ on the crystal stability is also studied using thermal analysis. This study reveals that water molecules are ...

  9. Strontium adsorption and penetration in kaolinite at low Sr

    NARCIS (Netherlands)

    Ning, Zigong; Ishiguro, Munehide; Koopal, Luuk K.; Sato, Tsutomu; Kashiwagi, Junichi

    2017-01-01

    Behavior of radioactive strontium (Sr2+) in contaminated soils is an important issue in relation to nuclear power plant accidents. The Sr2+ adsorption on kaolinite and its migration in a kaolinite soil were investigated because toxic effects of radioactive Sr2+ have been found to be very severe for

  10. Study of sorption processes of strontium on the synthetic hydroxyapatite

    International Nuclear Information System (INIS)

    Rosskopfova, O.; Galambos, M.; Rajec, P.

    2011-01-01

    The sorption of strontium on synthetic hydroxyapatite was investigated using batch method and radiotracer technique. The hydroxyapatite samples were prepared by a wet precipitation process followed by calcination of calcium phosphate that precipitated from aqueous solution. Also, commercial hydroxyapatites were used. The sorption of strontium on hydroxyapatite depended on the method of preparation and it was pH independent ranging from 4 to 9 as a result of buffering properties of hydroxyapatite. The distribution coefficient K d was significantly decreased with increasing concentration of Sr 2+ and Ca 2+ ions in solution with concentration above 1 x 10 -3 mol dm -3 . The percentage strontium sorption for commercial and by wet method prepared hydroxyapatite was in the range of 83-96%, while calcined hydroxyapatite was ranging from 10 to 30%. The experimental data for sorption of strontium have been interpreted in the term of Langmuir isotherm. The sorption of Sr 2+ ions was performed by ion-exchange with Ca 2+ cations on the crystal surface of hydroxyapatite. Although calcined hydroxyapatite is successfully used as biomaterial for hard tissues repair, it is not used for the treatment of liquid wastes. (author)

  11. Coherent normalization of finger strontium XRF measurements: feasibility and limitations

    Energy Technology Data Exchange (ETDEWEB)

    Zamburlini, M; Pejovic-Milic, A; Chettle, D R [Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, L8S 4K1 (Canada)

    2008-08-07

    A non-invasive in vivo x-ray fluorescence (XRF) method of measuring bone strontium concentrations has previously been reported as a potential diagnostic tool able to detect strontium concentration in the finger and ankle bones. The feasibility of coherent normalization for {sup 125}I-source-based finger bone strontium x-ray fluorescence (XRF) measurements is assessed here by theoretical considerations and Monte Carlo simulations. Normalization would have several advantages, among which are the correction for the signal attenuation by the overlying soft tissue, and intersubject variability in the bone size and shape. The coherent normalization of bone strontium XRF measurements presents several challenges dictated by the behaviour of the coherent cross section and mass attenuation coefficient at the energies involved. It was found that the coherent normalization alone with either 22.1 keV or 35.5 keV photons was not successful in correcting for the overlying soft tissue attenuation. However, it was found that the coherent peak at 35.5 keV was able to correct effectively for variability in the finger bone size between people. Thus, it is suggested that, if the overlying soft tissue thickness can be obtained by means of an independent measurement, the 35.5 keV peak can be used to correct for the bone size, with an overall accuracy of the normalization process of better than 10%. (note)

  12. Phonons in face-centred cubic calcium and strontium

    International Nuclear Information System (INIS)

    Singh, S.P.; Rathore, R.P.S.

    1984-01-01

    The axially symmetric and unpaired forces are employed to analyse the phonon dispersion and elastic behaviour of face centred cubic calcium and strontium which have so far not been studied adequately. The model with three parameters predicts the results which agree marvellously with the recently measured data. (author)

  13. Substitution of strontium for calcium in glass ionomer cements (Part ...

    African Journals Online (AJOL)

    Objectives: To investigate the effects of substituting strontium for calcium in fluoroaluminosilicate glass on the mechanical and ion-releasing properties of high-viscosity glass ionomer cements. Design: An exploratory, laboratory-based study. Setting: Dental biomaterials research laboratory, Dental Physical Sciences Unit, ...

  14. Strontium-90 content of human bone collected in 1967

    International Nuclear Information System (INIS)

    Jeanmaire, L.; Patti, F.

    1969-01-01

    This report follows report CEA-R-3381 and presents the strontium 90 content of human bones collected in 1967 in the Paris area. The main trend is much the same as during 1966; contamination levels are falling down in infants up to 5 year old. Beyond this age, the values are the same or experience a slight increase. (authors) [fr

  15. Effect of selected foodstuffs on strontium 89 metabolism in rats

    International Nuclear Information System (INIS)

    Keslev, D.; Jotov, M.

    1975-01-01

    The influence of a variety of food products used in human nutrition on strontium-89 cumulation in rat organism is studied. To this end the animals were fed for a week with meat, beans, maize, white and brown bread, cabbage, milk or potatoes prepared so as to be edible by man. Then for additional 15 days the animals were fed the same diet + a daily oral dose of 2 μCi strontium-89. On the 16th day radionuclide activity in the thigh bone was measured. Beans was the food product exerting optimal limiting effect on strontium deposition (reduction factor (RF) 17), milk and ranking next (RF 13, resp. 6.5). All other products showed approximately equal efforts (RF 1.4 - 1.8). The different calcium content of each of these food products is responsible for their different effectiveness. Together with the discrimination which the living organism displays in the presence of calcium, other constituents of the food products which form complexes with strontium and prevent its deposition in the bones are equally essential. (Ch.K.)

  16. Quaternary system of lithium, potassium, calcium and strontium fluorides

    International Nuclear Information System (INIS)

    Garkushin, I.K.; Voronin, K.Yu.; Dibirov, M.A.; Miftakhov, T.T.

    1996-01-01

    Four-component system of lithium, potassium, calcium and strontium fluorides is studied by differential thermal analysis. A low-melting eutectic composition is revealed, specific fusion heat of the composition is experimentally determined, its thermal properties are calculated. 8 refs., 5 figs., 1 tab

  17. Influence of strontium on the cubic to ordered hexagonal phase

    Indian Academy of Sciences (India)

    ... Refresher Courses · Symposia · Live Streaming. Home; Journals; Bulletin of Materials Science; Volume 23; Issue 6. Influence of strontium on the cubic to ordered hexagonal phase transformation in barium magnesium niobate. M Thirumal A K Ganguli. Phase Transitions Volume 23 Issue 6 December 2000 pp 495-498 ...

  18. Strontium-90 and cesium-137 in fresh water

    International Nuclear Information System (INIS)

    1978-01-01

    Japan Chemical Analysis Center has analysed the strontium-90 and Cesium-137 contents in fresh water from 7 prefectures in Japan by the commission of Science and Technology Agency of Japanese Government. The method described in ''Radioactivity Survey Data in Japan No. 43 (NIRS-RSD-43, 1977) was applied to the analysis of these two radionuclides in samples. (author)

  19. Membrane-based separation technologies for cesium, strontium, and technetium

    International Nuclear Information System (INIS)

    Kafka, T.

    1996-01-01

    This work is one of two parallel projects that are part of an ESP task to develop high-capacity, selective, solid extractants for cesium, strontium, and technetium from nuclear wastes. In this subtask, Pacific Northwest National Laboratory (PNNL) is collaborating with 3M, St. Paul, Minnesota, working in cooperation with IBC Advanced Technologies, American Fork, Utah

  20. Rubidium-strontium and uranium-lead isotopic age studies

    International Nuclear Information System (INIS)

    Loveridge, W.D.

    1980-01-01

    Rubidium-strontium whole rock isochron ages and initial 87 Sr/ 86 Sr ratios and uranium-lead ages on zircon from suites of samples selected from localities across Canada are presented. Descriptions of the geological probelms and interpretations of the measured ages are included. Laboratory age determination methods and techniques are described or referenced. (auth)

  1. Effects of strontium ranelate on spinal osteoarthritis progression

    DEFF Research Database (Denmark)

    Bruyere, O; Delferriere, D; Roux, C

    2008-01-01

    OBJECTIVE: The aim of this study was to determine whether a 3-year treatment with strontium ranelate could delay the progression of spinal osteoarthritis (OA). METHODS: This study was a post-hoc analysis of pooled data from the Spinal Osteoporosis Therapeutic Intervention (SOTI) and TReatment...

  2. Study of strontium and cesium migration in fractured crystalline rock

    International Nuclear Information System (INIS)

    Gustafsson, E.; Klockars, C.E.

    1984-01-01

    The purpose of this investigation has been to study the retardation and dilution of non-active strontium and cesium relative to a non-absorbing substance (iodide) in a well-defined fracture zone in the Finnsjoen field research area. The investigation was carried out in a previously tracer-tested fracture zone. The study has encompassed two separate test runs with prolonged injection of strontium and iodide and of cesium and iodide. The test have shown that: - Strontium is not retarded, but rather absorbed to about 40% at equilibrium. - At injection stop, 36.3% of the injected mass of strontium has been absorbed and there is no deabsorption. -Cesium is retarded a factor of 2-3 and absorbed to about 30% at equilibrium. - At injection stop, 39.4% of the injected mass of cesium has been absorbed. Cesium is deabsorbed after injection stop (400h) and after 1300 hours, only 22% of the injected mass of cesium is absorbed. (author)

  3. Dielectric Strontium Zirconate Sprayed by a Plasma Torch.

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Sedláček, J.; Janata, Marek

    2017-01-01

    Roč. 10, č. 4 (2017), s. 225-230 ISSN 2008-2134 Institutional support: RVO:61389021 Keywords : Plasma spraying * Electrical properties * Strontium Zirconate * Insulators Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass OBOR OECD: Ceramics www.pccc.icrc.ac.ir/Articles/18/1/18/1010/

  4. Substitution of strontium for calcium in glass ionomer cements (Part ...

    African Journals Online (AJOL)

    Substitution of strontium for calcium in glass ionomer cements (Part 1): Glass synthesis and characterisation, and the effects on the cement handling variables and ... acid to form glass ionomer cements, whose properties were investigated at different time points: working and setting times were determined by rheometry; and, ...

  5. The Effect of Humidity and Oxygen Partial Pressure on LSM–YSZ Cathode

    DEFF Research Database (Denmark)

    Knöfel, Christina; Chen, Ming; Mogensen, Mogens Bjerg

    2011-01-01

    Two series of anode supported solid oxide fuel cells (SOFC) were prepared, one with a composite cathode layer of lanthanum strontium manganite (LSM) and yttria stabilized zirconia (YSZ) on top and the other further has a LSM current collector layer on top. The fuel cells were heat treated at 1...... of manganese concentration and strontium enrichment on the surface of the materials. Formation of monoclinic zirconia and zirconate phases was also observed. These results give a closer insight into possible degradation mechanisms of SOFC composite cathode materials in dependence of humidity and oxygen partial...

  6. DNA repair deficiency in neurodegeneration

    DEFF Research Database (Denmark)

    Jeppesen, Dennis Kjølhede; Bohr, Vilhelm A; Stevnsner, Tinna V.

    2011-01-01

    Deficiency in repair of nuclear and mitochondrial DNA damage has been linked to several neurodegenerative disorders. Many recent experimental results indicate that the post-mitotic neurons are particularly prone to accumulation of unrepaired DNA lesions potentially leading to progressive...... neurodegeneration. Nucleotide excision repair is the cellular pathway responsible for removing helix-distorting DNA damage and deficiency in such repair is found in a number of diseases with neurodegenerative phenotypes, including Xeroderma Pigmentosum and Cockayne syndrome. The main pathway for repairing oxidative...... base lesions is base excision repair, and such repair is crucial for neurons given their high rates of oxygen metabolism. Mismatch repair corrects base mispairs generated during replication and evidence indicates that oxidative DNA damage can cause this pathway to expand trinucleotide repeats, thereby...

  7. First-Principles Study on Cathode Properties of Li2MTiO4 (M = V, Cr, Mn, Fe, Co, and Ni) with Oxygen Deficiency for Li-Ion Batteries

    Science.gov (United States)

    Hamaguchi, Motoyuki; Momida, Hiroyoshi; Oguchi, Tamio

    2018-04-01

    We study the cathode properties of Li2MTiO4 (M = V, Cr, Mn, Fe, Co, and Ni) for Li-ion batteries by performing first-principles calculations. Formation energies and voltages for Li2-xMTiO4 (0 ≤ x ≤ 2) models with rock-salt-based structures considering several Li concentrations (2 - x) are calculated. Two dominant charge/discharge reaction mechanisms associated with redox reactions of M and O are found mainly in the ranges of lower and higher x, respectively. In the higher-x region, the O redox reactions can destabilize atomic structures, because the electron removal from O-p states produces high peaks at the fermi level in the density of states. The structural stability of O using the models with O deficiency is calculated, and the result shows that O can dissociate much more easily than Li in the higher-x region. The critical Li concentration at which the vacancy formation energy of O becomes lower than that of Li is estimated, and the critical x value decreases with increasing number of 3d electrons as M changes from V to Ni. The calculated voltages of Li2MTiO4 with O deficiency are lower than those without O deficiency, showing that the O dissociation degrades battery performances. Our systematic study for the series of M predicts that Li2CrTiO4 may be the best cathode material considering its cathode properties of high voltage and stability against O dissociation.

  8. Effect of strontium ranelate on bone mineral: Analysis of nanoscale compositional changes.

    Science.gov (United States)

    Rossi, André L; Moldovan, Simona; Querido, William; Rossi, Alexandre; Werckmann, Jacques; Ersen, Ovidiu; Farina, Marcos

    2014-01-01

    Strontium ranelate has been used to prevent bone loss and stimulate bone regeneration. Although strontium may integrate into the bone crystal lattice, the chemical and structural modifications of the bone when strontium interacts with the mineral phase are not completely understood. The objective of this study was to evaluate apatite from the mandibles of rats treated with strontium ranelate in the drinking water and compare its characteristics with those from untreated rats and synthetic apatites with and without strontium. Electron energy loss near edge structures from phosphorus, carbon, calcium and strontium were obtained by electron energy loss spectroscopy in a transmission electron microscope. The strontium signal was detected in the biological and synthetic samples containing strontium. The relative quantification of carbon by analyzing the CK edge at an energy loss of ΔE = 284 eV showed an increase in the number of carbonate groups in the bone mineral of treated rats. A synthetic strontium-containing sample used as control did not exhibit a carbon signal. This study showed physicochemical modifications in the bone mineral at the nanoscale caused by the systemic administration of strontium ranelate. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Microwave-assisted fabrication of strontium doped apatite coating on Ti6Al4V

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Huan, E-mail: huanzhou@cczu.edu.cn [Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu 213164 (China); Kong, Shiqin [Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu 213164 (China); School of Materials Science and Engineering, Changzhou University, Changzhou, Jiangsu 213164 (China); Pan, Yan; Zhang, Zhiguo [Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu 213164 (China); Deng, Linhong, E-mail: dlh@cczu.edu.cn [Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu 213164 (China)

    2015-11-01

    Strontium has been shown to be a beneficial dopant to calcium phosphates when incorporated at nontoxic level. In the present work we studied the possibility of solution derived doping strontium into calcium phosphate coatings on titanium alloy Ti6Al4V based implants by a recently reported microwave-assisted method. By using this method strontium doped calcium phosphate nuclei were deposited to pretreated titanium alloy surface dot by dot to compose a crack-free coating layer. The presence of strontium in solution led to reduced roughness of the coating and finer nucleus size formed. In vitro study found that proliferation and differentiation of osteoblast cells seeded on the coating were influenced by strontium content in coatings, showing an increasing followed by a decreasing behavior with increasing substitution of calcium by strontium. It is suggested that this new microwave-assisted strontium doped calcium phosphate coatings may have great potential in implant modification. - Highlights: • Strontium doped calcium phosphate coating is deposited with microwave irradiation. • Increase of strontium reduces coating roughness and results in finer nucleus size. • Proliferation and differentiation of osteoblasts depend on doped strontium content.

  10. Dissolved strontium and calcium levels in the tropical Indian Ocean

    Science.gov (United States)

    Steiner, Zvi; Sarkar, Amit; Turchyn, Alexandra

    2017-04-01

    Measurements of seawater alkalinity and dissolved calcium concentrations along oceanic transects are often used to calculate calcium carbonate precipitation and dissolution rates. Given that the distribution coefficient of strontium in CaCO3 varies greatly between different groups of organisms, adding precise measurements of dissolved strontium concentrations provides opportunities to also track relative contributions of these different groups to the regional CaCO3 cycle. However, there are several obstacles to this approach. These obstacles include unresolved systematic discrepancies between seawater calcium and alkalinity data, very large analytical noise around the calcium concentration measurements and the unconstrained role of acantharia (radiolarian precipitating SrSO4 skeletons) in the marine strontium cycle. During the first cruise of the second International Indian Ocean Expedition (IIOE-2) water samples were collected along 67°E from 9°N to 5°S to explore the dissolution rate of calcium carbonate in the water. The dissolution rate can be calculated by combining measurements of water column potential alkalinity with calcium and strontium concentrations measured by ICP-OES and calcium concentration measurements using isotope dilution thermal ionization mass spectrometry (ID-TIMS). CaCO3 mineral saturation state calculated using pH and total alkalinity suggests that along 67°E, the aragonite saturation horizon lays at depth of 500 m on both sides of the equator. Across the cruise transect, dissolved strontium concentrations increase by 2-3% along the thermocline suggesting rapid recycling of strontium rich phases. This is particularly evident just below the thermocline at 8-9°N and below 1000 m water depth, south of the equator. The deep, southern enrichment in strontium does not involve a change in the Sr/Ca ratio, suggesting that this strontium enrichment is related to CaCO3 dissolution. In contrast, in the intermediate waters of the northern part of

  11. Remarkable Strontium B-Site Occupancy in FerroelectricPb(Zr1-xTix)O3 Solid Solutions Doped with Cryolite-Type StrontiumNiobate

    Energy Technology Data Exchange (ETDEWEB)

    Feltz, A.; Schmidt-Winkel, P.; Schossman, M.; Booth, C.H.; Albering, J.

    2007-04-26

    New high-performance ferroelectric materials based on Pb(Zr{sub 1-x}Ti{sub x})O{sub 3} (PZT) that are doped with cryolite-type strontium niobate (SNO, Sr{sub 4}(Sr{sub 2-2y/3}Nb{sub 2+2y/3})O{sub 11+y}V{sub 0,1-y} with 0 {le} y {le} 1), hence denoted PZT:SNO, and their microscopic structure are described. The combination of exceptional piezoelectric properties, i.e. a piezoelectric strain constant of d{sub 33} {approx} 760 pm/V, with excellent stability and degradation resistance makes ferroelectric PZT:SNO solid solutions very attractive for use in novel and innovative piezoelectric actuator and transducer applications. Extended X-ray absorption fine-structure (EXAFS) analyses of PZT:SNO samples revealed that {approx}10 % of the Sr cations occupy the nominal B-sites of the perovskite-type PZT host lattice. This result was supported by EXAFS analyses of both a canonical SrTiO{sub 3} perovskite and two SNO model and reference compounds. Fit models that do not account for Sr cations on B-sites were ruled out. A clear Sr-Pb peak in Fourier transformed EXAFS data visually confirmed this structural model. The generation of temporary oxygen vacancies and the intricate defect chemistry induced by SNO-doping of PZT are crucial for the exceptional materials properties exhibited by PZT:SNO materials.

  12. Observations on intestinal secretions of calcium by strontium-85 in normal Indian subjects and patients of nutritiond osteomalacia

    International Nuclear Information System (INIS)

    Rizvi, S.N.A.; Sumesh Chandra; Vaishnava, H.

    1979-01-01

    Fifty cases of nutritional osteomalacia were studied and compared with 25 adult subjects of comparable age, sex and socio-economic status without any suspicion of metabolic bone disease. The diagnosis of nutritional osteomalacia was established by clinical, biochemical, radiological and histopathological studies. 15 of the 50 patients were restudied after treatment with vitamin D. Total digestive juice calcium (TDJCa), true absorption of calcium and endogenous faecal calcium (EFCa) were measured in all by the intravenous administration of strontium 85 and balance studies for the stable calcium were carried out simultaneously. In nutritional osteomalacia there was no evidence of more active secretions of calcium into the intestines and endogenous loss of calcium was not high. It was interesting to note that absorption of calcium from the gut was normal even with relative vitamin D deficiency. It was also observed that vitamin D increased the bidirectional (absorption and secretion) permeability of calcium into the gut. (author)

  13. Optical lattice clock with Strontium atoms; Horloge a reseau optique a atomes de strontium

    Energy Technology Data Exchange (ETDEWEB)

    Baillard, X

    2008-01-15

    This thesis presents the latest achievements regarding the optical lattice clock with Strontium atoms developed at LNE-SYRTE. After a review of the different types of optical clocks that are currently under development, we stress on the concept of optical lattice clock which was first imagined for Sr{sup 87} using the {sup 1}S{sub 0} {yields} {sup 3}P{sub 0} transition. We exhibit the features of this atom, in particular the concept of magic wavelength for the trap, and the achievable performances for this kind of clock. The second part presents the experimental aspects, insisting particularly on the ultra-stable laser used for the interrogation of the atoms which is a central part of the experiment. Among the latest improvements, an optical pumping phase and an interrogation phase using a magnetic field have been added in order to refine the evaluation of the Zeeman effect. Finally, the last part presents the experimental results. The last evaluation of the clock using Sr{sup 87} atoms allowed us to reach a frequency accuracy of 2.6*10{sup -15} and a measurement in agreement with the one made at JILA (Tokyo university) at the 10{sup -15} level. On another hand, thanks to recent theoretical proposals, we made a measurement using the bosonic isotope Sr{sup 88} by adapting the experimental setup. This measurement represents the first evaluation for this type of clock, with a frequency accuracy of 7*10{sup -14}. (author)

  14. Strontium isotope geochemistry of soil and playa deposits near Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Marshall, B.D.; Mahan, S.A.

    1994-01-01

    The isotopic composition of strontium contained in the carbonate fractions of soils provides an excellent tracer which can be used to test models for their origin. This paper reports data on surface coatings and cements, eolian sediments, playas and alluvial fan soils which help to constrain a model for formation of the extensive calcretes and fault infillings in the Yucca Mountain region. The playas contain carbonate with a wide range of strontium compositions; further work will be required to fully understand their possible contributions to the pedogenic carbonate system. Soils from an alluvial fan to the west of Yucca Mountain show that only small amounts of strontium are derived from a fan draining a carbonate terrane have strontium component. Although much evidence points to an eolian source for at least some of the strontium in the pedogenic carbonates near Yucca Mountain, an additional component or past variation of strontium composition in the eolian source is required to model the pedogenic carbonate system

  15. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... fatigue or tiredness, shortness of breath, or chest pain. If your doctor diagnoses you with iron-deficiency ... Common symptoms of iron-deficiency anemia include: Chest pain Coldness in the hands and feet Difficulty concentrating ...

  16. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... heart failure . Increased risk of infections Motor or cognitive development delays in children Pregnancy complications, such as ... for iron-deficiency anemia. Learn about exciting research areas that NHLBI is exploring about iron-deficiency anemia. ...

  17. Factor VII deficiency

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000548.htm Factor VII deficiency To use the sharing features on this page, please enable JavaScript. Factor VII (seven) deficiency is a disorder caused by a ...

  18. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... deficiency anemia can cause serious complications, including heart failure and development delays in children. Explore this Health ... lead to iron-deficiency anemia include: End-stage kidney failure, where there is blood loss during dialysis. ...

  19. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... for iron-deficiency anemia. Lifestyle habits Certain lifestyle habits may increase your risk for iron-deficiency anemia, including: Vegetarian or vegan eating patterns. Not eating enough iron-rich foods, such ...

  20. Iron-Deficiency Anemia

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    Full Text Available ... deficiency anemia can cause serious complications, including heart failure and development delays in children. Explore this Health ... to iron-deficiency anemia include: End-stage kidney failure, where there is blood loss during dialysis. People ...

  1. Iron-Deficiency Anemia

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    Full Text Available ... view the colon directly. What if my doctor thinks something else is causing my iron-deficiency anemia? ... deficiency anemia early in life affects later behavior, thinking, and mood during adolescence. Treating anemia in premature ...

  2. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... mg and women need 18 mg. After age 51, both men and women need 8 mg. Pregnant ... for iron-deficiency anemia. Learn about exciting research areas that NHLBI is exploring about iron-deficiency anemia. ...

  3. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... iron-deficiency anemia. These conditions include: Intestinal and digestive conditions, such as celiac disease; inflammatory bowel diseases, ... iron-deficiency anemia , such as bleeding in the digestive or urinary tract or heavy menstrual bleeding, your ...

  4. Iron-Deficiency Anemia

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    Full Text Available ... conditions that can cause iron-deficiency anemia. Blood tests to screen for iron-deficiency anemia To screen ... the size of your liver and spleen. Blood tests Based on results from blood tests to screen ...

  5. Iron-Deficiency Anemia

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    Full Text Available ... from developing iron-deficiency anemia. Foods that are good sources of iron include dried beans, dried fruits, eggs, lean red meat, ... signs of iron-deficiency anemia include: Brittle nails ...

  6. Iron-Deficiency Anemia

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    Full Text Available ... your doctor may recommend you eat heart-healthy foods or control other conditions that can cause iron-deficiency anemia. Blood tests to screen for iron-deficiency anemia To screen ...

  7. Fire Safety Deficiencies

    Data.gov (United States)

    U.S. Department of Health & Human Services — A list of all fire safety deficiencies currently listed on Nursing Home Compare, including the nursing home that received the deficiency, the associated inspection...

  8. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... learning how having iron-deficiency anemia early in life affects later behavior, thinking, and mood during adolescence. ... iron-deficiency anemia in blood donors affects the quality of donated red blood cells, such as how ...

  9. Iron-Deficiency Anemia

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    Full Text Available ... iron-deficiency anemia in blood donors affects the quality of donated red blood cells, such as how ... Cells From Iron-deficient Donors: Recovery and Storage Quality. Learn more about participating in a clinical trial . ...

  10. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... leaving cells where it is stored or from being absorbed in the duodenum, the first part of ... treatments for iron-deficiency anemia. Living With After being diagnosed with iron-deficiency anemia, it is important ...

  11. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... cells that carries oxygen from the lungs to tissues and organs in the body. Hemoglobin also carries ... oxygen-rich blood through your body. Cells in tissues need a steady supply of oxygen to work ...

  12. Distribution of strontium in DB18K6 and DTBDB18K6 systems

    International Nuclear Information System (INIS)

    Usarov, Z.O.; Khujaev, S.

    2007-01-01

    Distributions of strontium in DB18K6 and DTBDB18K6 crown-ethers in chloroform were investigated for extraction of strontium from water solutions of nitric acid. Nitrate solutions with various pH were considered. In both crown-ethers the most extraction of strontium was observed for the moderate pH values. Equilibrium of extraction process is reached for comparatively short time and is occurred to be 20 min (authors)

  13. An optimization on strontium separation model for fission products (inactive trace elements) using artificial neural networks

    International Nuclear Information System (INIS)

    Moosavi, K.; Setayeshi, S.; Maragheh, M.Gh.; Ahmadi, S.J.; Kardan, M.R.; Banaem, L.M.

    2009-01-01

    In this study, an experimental design using artificial neural networks for an optimization on the strontium separation model for fission products (inactive trace elements) is investigated. The goal is to optimize the separation parameters to achieve maximum amount of strontium that is separated from the fission products. The result of the optimization method causes a proper purity of Strontium-89 that was separated from the fission products. It is also shown that ANN may be establish a method to optimize the separation model.

  14. Investigation of the elution by seawater of caesium and strontium from loaded clinoptilolite

    International Nuclear Information System (INIS)

    Harder, B.R.; Mitchell, I.H.; Smyth, M.J.

    1985-07-01

    Simple investigations of the elution of caesium and strontium from loaded clinoptilolite are described. The clinoptilolite was loaded to levels expected in the British Nuclear Fuels plc SIXEP plant and contacted with seawater at approx. 15 C. (The elution time was measured until about 99% of the caesium and strontium had been eluted.) It was found that 99% of the caesium was eluted in 35 hours but the strontium (with more variable results) took at least 400 hours for 99% elution. (author)

  15. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... if you are diagnosed with iron-deficiency anemia. Risk Factors You may have an increased risk for iron-deficiency anemia because of your age, ... or sex. Age You may be at increased risk for iron deficiency at certain ages: Infants between ...

  16. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Home / < Back To Health Topics / Iron-Deficiency Anemia Iron-Deficiency Anemia Also known as Leer en español ... bleeding Consuming less than recommended daily amounts of iron Iron-deficiency anemia can be caused by getting ...

  17. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Topics News & Resources Intramural Research Home / < Back To Health Topics / Iron-Deficiency Anemia Iron-Deficiency Anemia Also known as Leer ... and symptoms as well as complications from iron-deficiency anemia. Research for Your Health The NHLBI is part of the U.S. Department ...

  18. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... anemia, your doctor may order the following blood tests to diagnose iron-deficiency anemia: Complete blood count (CBC) to ... than normal when viewed under a microscope. Different tests help your doctor diagnose iron-deficiency anemia. In iron-deficiency anemia, blood ...

  19. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... for iron-deficiency anemia if you have certain risk factors , including pregnancy. To prevent iron-deficiency anemia, your doctor may recommend you eat heart-healthy foods or control other conditions that can cause iron-deficiency anemia. ...

  20. Alarm points for fixed oxygen monitors

    International Nuclear Information System (INIS)

    Miller, G.C.

    1987-05-01

    Oxygen concentration monitors were installed in a vault where numerous pipes carried inert cryogens and gases to the Mirror Fusion Test Facility (MFTF-B) experimental vessel at Lawrence Livermore National Laboratory (LLNL). The problems associated with oxygen-monitoring systems and the reasons why such monitors were installed were reviewed. As a result of this review, the MFTF-B monitors were set to sound an evacuation alarm when the oxygen concentration fell below 18%. We chose the 18% alarm criterion to minimize false alarms and to allow time for personnel to escape in an oxygen-deficient environment

  1. Migration Behaviour of Strontium in Czech Bentonite Clay

    Directory of Open Access Journals (Sweden)

    Lucie Baborova

    2016-09-01

    Full Text Available The study deals with sorption and diffusion behaviour of strontium in Czech bentonite B75. The study is a part of a research on reactive transport of radioactive contaminants in barrier materials of a deep geological repository of radioactive waste in the Czech Republic. Series of sorption and diffusion experiments with Sr and non-activated Ca bentonite B75 produced in the Czech Republic were performed in two background solutions (CaCl2 and NaCl. On the basis of sorption batch experiments the kinetics of strontium sorption on bentonite was assessed and the sorption isotherms for various experimental conditions were obtained. As a result of performed diffusion experiments the parameters of diffusion (i.e. effective diffusion coefficient De and apparent diffusion coefficient Da were determined. The observed discrepancies between sorption characteristics obtained from the sorption and diffusion experiments are discussed.

  2. Strontium isotopic geochemistry of intrusive rocks, Puerto Rico, Greater Antilles

    International Nuclear Information System (INIS)

    Jones, L.M.; Kesler, S.E.

    1980-01-01

    The strontium isotope geochemistry is given for three Puerto Rican intrusive rocks: the granodioritic Morovis and San Lorenzo plutons and the Rio Blanco stock of quartz dioritic composition. The average calculated initial 87 Sr/ 86 Sr ratios are 0.70370, 0.70355 and 0.70408, respectively. In addition, the San Lorenzo data establish a whole-rock isochron of 71 +- 2 m.y., which agrees with the previously reported K-Ar age of 73 m.y. Similarity of most of the intrusive rocks in the Greater Antilles with respect to their strontium isotopic geochemistry regardless of their major element composition indicates that intrusive magmas with a wide range of composition can be derived from a single source material. The most likely source material, in view of the available isotopic data, is the mantle wedge overlying the subduction zone. (orig.)

  3. Strontium-90 and cesium-137 in service water

    International Nuclear Information System (INIS)

    1979-01-01

    Prefectural public health laboratories and institutes and Japan Chemical Analysis Center have analysed the contents of strontium-90 and cesium-137 in service water under the commission of Science and Technology Agency. At each prefectural public health laboratories and institutes, 100 literes of service water (8 prefectures, water from the intake of each station of water works) and tap water (32 prefectures) were collected as sample twice a year. The samples were filtrated with large filter papers after addition and mixture of both some carries. The filtration was then applied on a column filled the sodium cation exchange resin, and all the cations were absorbed on it. These resin and filter papers were collected at Japan Chemical Analysis Center. At Japan Chemical Analysis Center, these collected samples were radiochemically analysed for strontium-90 and cesium-137 using the method applied for the analysis of rain and dry fallout materials. (author)

  4. Determination of lithium, rubidium and strontium in foodstuffs

    International Nuclear Information System (INIS)

    Evans, W.H.; Read, J.I.

    1985-01-01

    For the determination of total lithium, rubidium and strontium in foodstuffs the organic matter is destroyed by a wet-oxidation procedure. Both lithium and rubidium are measured by flame atomic-emission spectrophotometry, rubidium with the addition of a radiation buffer and strontium is measured by flame atomic-absorption spectrophotometry using the same radiation buffer. The optimum conditions for measurement are described and interferences noted. The accuracy of the method was assessed by measuring the recovery of these metals from foodstuff homogenates and values for standard reference materials are listed, for comparison with certified levels where these exist. From the results obtained standard deviations were calculated and derived limits of detection and confidence intervals are given. (author)

  5. Strontium-90 and cesium-137 in total diet

    International Nuclear Information System (INIS)

    1977-01-01

    Under the commission of Science and Technology Agency, Japan Chemical Analysis Center has analysed total diet samples collected from 30 prefectures (2 times per year), and determined to content of strontium-90 and cesium-137 in these samples. Each Prefectural public health laboratories and institutes have collected all the daily regular diet consumed for five persons, namely three meals and other eating between meals, for radiochemical analysis in polyethylene containers. These samples were collected to Japan Chemical Analysis Center after carbonization without smoke rising in the large stainless dish. At Japan Chemical Analysis Center, these samples were asked in an electric muffle furnance. And the ask to which both some carriers and hydrochloric acid were added, was destroyed under heating. The nuclides were dissolved into hydrochloric acid and filtrated, after it was added with nitric acid and heated to dryness. The filtrates was analysed for strontium-90 and cesium-137 using the method recommended by Science and Technology Agency. (author)

  6. Sea water strontium isotopes, acid rain, and the cretaceous-tertiary boundary

    International Nuclear Information System (INIS)

    MacDougall, J.D.

    1988-01-01

    A large bolide impact at the end of the Cretaceous would have produced significant amounts of nitrogen oxides by shock heating of the atmosphere. The resulting acid precipitation would have increased continental weathering greatly and could be an explanation for the observed high ratio of strontium-87 to strontium-86 in sea water at about this time, due to the dissolution of large amounts of strontium from the continental crust. Spikes to high values in the sea water strontium isotope record at other times may reflect similar episodes. 17 references, 1 figure, 1 table

  7. [Effects of strontium in drinking water on the growth of school-age children].

    Science.gov (United States)

    Tao, Y; Cao, S; Xu, F; Li, J

    1999-09-30

    An epidemiological study on the effect of strontium in drinking water on body shape development, bone age, prevalence of caries and dental fluorosis was carried out. The results show: there is a certain promotion on the development of bone age of school-age children, especially of girls, and there is no obvious impact on body shape developing when the concentration of strontium in drinking water is only 10 mg/L. The correlation between strontium in drinking water and the prevalence of caries in children could not get a conclusive evidence in this paper. A further epidemiological investigation is necessary if the role of strontium against caries should be proved.

  8. Strontium-90 in ion-exchange resin used in the Australian FIEFS network

    International Nuclear Information System (INIS)

    Wise, K.N.

    1977-10-01

    In order to determine monthly strontium-90 fallout deposited at the eight Australian monitoring stations, account must be taken of the level of strontium-90 contamination of the ion-exchange resin as prepared for use in the FIEFS. This procedure has always been important in monitoring strontium-90 fallout deposit in Australia because the level of strontium-90 contamination of ion-exchange resin, supplied by manufacturers in the Northern Hemisphere, has remained of the same order of magnitude as the monthly fallout deposit in the Southern Hemisphere

  9. Seawater strontium isotopes, acid rain, and the Cretaceous-Tertiary boundary

    Science.gov (United States)

    Macdougall, J. D.

    1988-01-01

    A large bolide impact at the end of the Cretaceous would have produced significant amounts of nitrogen oxides by shock heating of the atmosphere. The resulting acid precipitation would have increased continental weathering greatly and could be an explanation for the observed high ratio of strontium-87 to strontium-86 in seawater at about this time, due to the dissolution of large amounts of strontium from the continental crust. Spikes to high values in the seawater strontium isotope record at other times may reflect similar episodes.

  10. Strontium eluting graphene hybrid nanoparticles augment osteogenesis in a 3D tissue scaffold

    Science.gov (United States)

    Kumar, Sachin; Chatterjee, Kaushik

    2015-01-01

    The objective of this work was to prepare hybrid nanoparticles of graphene sheets decorated with strontium metallic nanoparticles and demonstrate their advantages in bone tissue engineering. Strontium-decorated reduced graphene oxide (RGO_Sr) hybrid nanoparticles were synthesized by the facile reduction of graphene oxide and strontium nitrate. X-ray diffraction, transmission electron microscopy, and atomic force microscopy revealed that the hybrid particles were composed of RGO sheets decorated with 200-300 nm metallic strontium particles. Thermal gravimetric analysis further confirmed the composition of the hybrid particles as 22 wt% of strontium. Macroporous tissue scaffolds were prepared by incorporating RGO_Sr particles in poly(ε-caprolactone) (PCL). The PCL/RGO_Sr scaffolds were found to elute strontium ions in aqueous medium. Osteoblast proliferation and differentiation was significantly higher in the PCL scaffolds containing the RGO_Sr particles in contrast to neat PCL and PCL/RGO scaffolds. The increased biological activity can be attributed to the release of strontium ions from the hybrid nanoparticles. This study demonstrates that composites prepared using hybrid nanoparticles that elute strontium ions can be used to prepare multifunctional scaffolds with good mechanical and osteoinductive properties. These findings have important implications for designing the next generation of biomaterials for use in tissue regeneration.The objective of this work was to prepare hybrid nanoparticles of graphene sheets decorated with strontium metallic nanoparticles and demonstrate their advantages in bone tissue engineering. Strontium-decorated reduced graphene oxide (RGO_Sr) hybrid nanoparticles were synthesized by the facile reduction of graphene oxide and strontium nitrate. X-ray diffraction, transmission electron microscopy, and atomic force microscopy revealed that the hybrid particles were composed of RGO sheets decorated with 200-300 nm metallic strontium

  11. Reduction in the absorption and retention of strontium in rats

    Energy Technology Data Exchange (ETDEWEB)

    Slat, B; Kostial, K; Harrison, G E

    1971-12-01

    Rats were fed a stock diet supplemented with calcium phosphate and sodium alginate, both separately and simultaneously, over a period of 4-5 months. Observations were made at intervals on the growth rate and on visual and histological abnormalities in some body tissues. No toxic effects were observed. The absorption and skeletal retention of calcium for rats on the combined supplements remained almost unchanged but the absorption and retention of strontium was reduced 7-fold.

  12. Strontium borate glass: potential biomaterial for bone regeneration

    OpenAIRE

    Pan, H. B.; Zhao, X. L.; Zhang, X.; Zhang, K. B.; Li, L. C.; Li, Z. Y.; Lam, W. M.; Lu, W. W.; Wang, D. P.; Huang, W. H.; Lin, K. L.; Chang, J.

    2009-01-01

    Boron plays important roles in many life processes including embryogenesis, bone growth and maintenance, immune function and psychomotor skills. Thus, the delivery of boron by the degradation of borate glass is of special interest in biomedical applications. However, the cytotoxicity of borate glass which arises with the rapid release of boron has to be carefully considered. In this study, it was found that the incorporation of strontium into borate glass can not only moderate the rapid relea...

  13. Extraction of cesium and strontium from nuclear waste

    Science.gov (United States)

    Davis, Jr., Milton W.; Bowers, Jr., Charles B.

    1988-01-01

    Cesium is extracted from acidified nuclear waste by contacting the waste with a bis 4,4'(5) [1-hydroxy-2-ethylhexyl]benzo 18-crown-6 compound and a cation exchanger in a matrix solution. Strontium is extracted from acidified nuclear waste by contacting the waste with a bis 4,4'(5') [1-hydroxyheptyl]cyclohexo 18-crown-6 compound, and a cation exchanger in a matrix solution.

  14. Applications of Random Nonlinear Photonic Crystals Based on Strontium Tetraborate

    Directory of Open Access Journals (Sweden)

    Alexandre I. Zaitsev

    2012-10-01

    Full Text Available Properties of strontium tetraborate (SBO and features of as-grown anti-parallel domains are summarized. From the point of view of nonlinear optics, these domains form nonlinear photonic crystals (NPC. Applications of NPC to the deep ultraviolet generation and fs pulse diagnostics are described. NPC and SBO are prospective media for the creation of a widely tunable source of fs pulses in the vacuum ultraviolet and for autocorrelation diagnostics of broadly tunable sources.

  15. Electrical behaviour of strontium-doped lanthanum manganite interfaces

    DEFF Research Database (Denmark)

    Koch, Søren; Hendriksen, P.V.; Jacobsen, Torben

    2005-01-01

    The contact resistance of strontium-doped lanthanum manganite (LSM) contact pairs is investigated by polarisation analysis at different temperatures and atmospheres. The ceramic contacts have a high contact resistance, and strongly nonlinear current–voltage behaviour is observed at low temperatur....... The nonlinear behaviour is ascribed to the presence of energy barriers at the contact interface. Generally, point contacts showed a more linear behaviour than plane contact interfaces....

  16. Strontium-rubidium infusion pump with in-line dosimetry

    International Nuclear Information System (INIS)

    Barker, S.L.; Loberg, M.D.

    1986-01-01

    A strontium-rubidium infusion system is described which consists of: (a) means for generating rubidium 82 in a solution which can be infused into a patient; (b) means for infusing the solution into a patient; (c) means for measuring the radioactivity present in the solution as it is infused into the patient; and (d) means for controlling the means for infusing in response to the amount of radioactivity which has been infused into the patient

  17. Practical aspects of the environmental behavior of strontium isotopes

    International Nuclear Information System (INIS)

    Madelmont, Claude; Bittel, Robert; Daburon, Francois.

    1977-03-01

    The practical aspects of contamination patterns of the food chain by strontium isotopes are reviewed - plants with special emphasis on the consequences of irrigation (contamination level at equilibrium); dairy products and the adjustement of a general model to regional conditions (a table of quantitative parameters for some French regions is included); marine and freshwater products. One should keep in mind that transfer parameters may change with time and cannot be assessed definitively [fr

  18. TAILORING INORGANIC SORBENTS FOR SRS STRONTIUM AND ACTINIDE SEPARATIONS: OPTIMIZED MONOSODIUM TITANATE PHASE II FINAL REPORT

    International Nuclear Information System (INIS)

    Hobbs, D; Thomas Peters, T; Michael Poirier, M; Mark Barnes, M; Major Thompson, M; Samuel Fink, S

    2007-01-01

    This document provides a final report of Phase II testing activities for the development of a modified monosodium titanate (MST) that exhibits improved strontium and actinide removal characteristics compared to the baseline MST material. The activities included determining the key synthesis conditions for preparation of the modified MST, preparation of the modified MST at a larger scale by a commercial vendor, demonstration of the strontium and actinide removal characteristics with actual tank waste supernate and measurement of filtration characteristics. Key findings and conclusions include the following. Testing evaluated three synthetic methods and eleven process parameters for the optimum synthesis conditions for the preparation on an improved form of MST. We selected the post synthesis method (Method 3) for continued development based on overall sorbate removal performance. We successfully prepared three batches of the modified MST using Method 3 procedure at a 25-gram scale. The laboratory prepared modified MST exhibited increased sorption kinetics with simulated and actual waste solutions and similar filtration characteristics to the baseline MST. Characterization of the modified MST indicated that the post synthesis treatment did not significantly alter the particle size distribution, but did significantly increase the surface area and porosity compared to the original MST. Testing indicated that the modified MST exhibits reduced affinity for uranium compared to the baseline MST, reducing risk of fissile loading. Shelf-life testing indicated no change in strontium and actinide performance removal after storing the modified MST for 12-months at ambient laboratory temperature. The material releases oxygen during the synthesis and continues to offgas after the synthesis at a rapidly diminishing rate until below a measurable rate after 4 months. Optima Chemical Group LLC prepared a 15-kilogram batch of the modified MST using the post synthesis procedure (Method

  19. Controlled manipulation of oxygen vacancies using nanoscale flexoelectricity

    Energy Technology Data Exchange (ETDEWEB)

    Das, Saikat [Inst. for Basic Science (IBS), Seoul (Republic of Korea). Center for Correlated Electron Systems; Seoul National University (SNU), Seoul (Republic of Korea). Dept. of Physics and Astronomy; Wang, Bo [Pennsylvania State Univ., University Park, PA (United States).Dept. of Materials Science and Engineering; Cao, Ye [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Inst. for; Rae Cho, Myung [Inst. for Basic Science (IBS), Seoul (Republic of Korea). Center for Correlated Electron Systems; Seoul National University (SNU), Seoul (Republic of Korea). Dept. of Physics and Astronomy; Jae Shin, Yeong [Inst. for Basic Science (IBS), Seoul (Republic of Korea). Center for Correlated Electron Systems; Seoul National University (SNU), Seoul (Republic of Korea). Dept. of Physics and Astronomy; Mo Yang, Sang [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS); Sookmyung Women' s Univ., Seoul (Republic of Korea). Dept. of Physics; Wang, Lingfei [Inst. for Basic Science (IBS), Seoul (Republic of Korea). Center for Correlated Electron Systems; Seoul National University (SNU), Seoul (Republic of Korea). Dept. of Physics and Astronomy; Kim, Minu [Inst. for Basic Science (IBS), Seoul (Republic of Korea). Center for Correlated Electron Systems; Seoul National University (SNU), Seoul (Republic of Korea). Dept. of Physics and Astronomy; Kalinin, Sergei V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Inst. for Functional Imaging of Materials; Chen, Long-Qing [Pennsylvania State Univ., University Park, PA (United States).Dept. of Materials Science and Engineering; Noh, Tae Won [Inst. for Basic Science (IBS), Seoul (Republic of Korea). Center for Correlated Electron Systems; Seoul National University (SNU), Seoul (Republic of Korea). Dept. of Physics and Astronomy

    2017-09-20

    Oxygen vacancies, especially their distribution, are directly coupled to the electromagnetic properties of oxides and related emergent functionalities that have implications for device applications. Here using a homoepitaxial strontium titanate thin film, we demonstrate a controlled manipulation of the oxygen vacancy distribution using the mechanical force from a scanning probe microscope tip. By combining Kelvin probe force microscopy imaging and phase-field simulations, we show that oxygen vacancies can move under a stress-gradient-induced depolarisation field. When tailored, this nanoscale flexoelectric effect enables a controlled spatial modulation. In motion, the scanning probe tip thereby deterministically reconfigures the spatial distribution of vacancies. Finally, the ability to locally manipulate oxygen vacancies on-demand provides a tool for the exploration of mesoscale quantum phenomena and engineering multifunctional oxide devices.

  20. Literature survey of strontium-89/90 analysis

    International Nuclear Information System (INIS)

    Kwakman, P.J.M.

    1994-08-01

    At the RIVM Laboratory of Radiation Research (LSO), the determination of strontium-89/90 in grass and milk samples using fuming nitric acid is a bottle neck in the routine monitoring programme, mainly due to the use of hazardous chemicals. In recent scientific articles, a number of alternatives have been described. This report gives an overview of the latest developments in this field and compares the pros and cons of these methods. The most promising method appears to be the 'Sr-spec' method developed by EIChrom Industries. In this method, an ion-exchanger is used for sorption of cations from the sample solution and, subsequently, a crown ether on a polymer support is applied for the selective complexation of bivalent strontium ions in the presence of other interfering bivalent ions. An important advantage is that the hazardous fuming nitric acid can be omitted and that the total number of chemical separation steps can be largely reduced. The possibility of a routine application of the 'Sr-spec' method for the determination of strontium-89/90 in grass and milk at RIVM/LSO is proposed. 2 tabs., 1 appendix, 23 refs

  1. Microwave-hydrothermal synthesis of barium strontium titanate nanoparticles

    International Nuclear Information System (INIS)

    Simoes, A.Z.; Moura, F.; Onofre, T.B.; Ramirez, M.A.; Varela, J.A.; Longo, E.

    2010-01-01

    Research highlights: → Barium strontium titanate nanoparticles were obtained by the Hydrothemal microwave technique (HTMW) → This is a genuine technique to obtain nanoparticles at low temperature and short times → Barium strontium titanate free of carbonates with tetragonal structure was grown at 130 o C. - Abstract: Hydrothermal-microwave method (HTMW) was used to synthesize crystalline barium strontium titanate (Ba 0.8 Sr 0.2 TiO 3 ) nanoparticles (BST) in the temperature range of 100-130 o C. The crystallization of BST with tetragonal structure was reached at all the synthesis temperatures along with the formation of BaCO 3 as a minor impurity at lower syntheses temperatures. Typical FT-IR spectra for tetragonal (BST) nanoparticles presented well defined bands, indicating a substantial short-range order in the system. TG-DTA analyses confirmed the presence of lattice OH- groups, commonly found in materials obtained by HTMW process. FE/SEM revealed that lower syntheses temperatures led to a morphology that consisted of uniform grains while higher syntheses temperature consisted of big grains isolated and embedded in a matrix of small grains. TEM has shown BST nanoparticles with diameters between 40 and 80 nm. These results show that the HTMW synthesis route is rapid, cost effective, and could serve as an alternative to obtain BST nanoparticles.

  2. Strontium borate glass: potential biomaterial for bone regeneration.

    Science.gov (United States)

    Pan, H B; Zhao, X L; Zhang, X; Zhang, K B; Li, L C; Li, Z Y; Lam, W M; Lu, W W; Wang, D P; Huang, W H; Lin, K L; Chang, J

    2010-07-06

    Boron plays important roles in many life processes including embryogenesis, bone growth and maintenance, immune function and psychomotor skills. Thus, the delivery of boron by the degradation of borate glass is of special interest in biomedical applications. However, the cytotoxicity of borate glass which arises with the rapid release of boron has to be carefully considered. In this study, it was found that the incorporation of strontium into borate glass can not only moderate the rapid release of boron, but also induce the adhesion of osteoblast-like cells, SaOS-2, thus significantly increasing the cyto-compatibility of borate glass. The formation of multilayers of apatite with porous structure indicates that complete degradation is optimistic, and the spread of SaOS-2 covered by apatite to form a sandwich structure may induce bone-like tissue formation at earlier stages. Therefore, such novel strontium-incorporated borosilicate may act as a new generation of biomaterial for bone regeneration, which not only renders boron as a nutritious element for bone health, but also delivers strontium to stimulate formation of new bones.

  3. Assessment of strontium in the Savannah River Site environment

    International Nuclear Information System (INIS)

    Carlton, W.H.; Evans, A.G.; Geary, L.A.; Murphy, C.E. Jr.; Strom, R.N.

    1992-01-01

    This document on strontium is published as a part of the Radiological Assessment Program (RAP). It is the sixth in a series of eight documents on individual radioisotopes released to the environment as a result of SRS (Savannah River Site) operations. Strontium exists in the environment as a result of above-ground nuclear weapons tests, the Chernobyl accident, the destruction of satellite Cosmos 954, small releases from reactors and reprocessing plants, and the operation of industrial, medical, and educational facilities. Strontium has been produced at SRS during the operation of 5 production reactors. About 300 curies of radiostrontium were released into streams in the late 50s and 60s, primarily from leaking fuel elements in reactor storage basins. Smaller quantities were released from the fuel reprocessing operations. About 400 Ci were released to seepage basins. A much smaller quantity, about 2 Ci, was released to the atmosphere. The overall radiological impact of SRS releases on the offsite maximum individual can be characterized by total doses of 6.2 mrem (atmospheric) and 1.4 mrem (liquid), compared with a dose of 12,960 mrem from non-SRS sources during the same period of time. Radiostrontium releases have resulted in a negligible risk to the environment and the population it supports

  4. Assessment of strontium in the Savannah River Site environment

    Energy Technology Data Exchange (ETDEWEB)

    Carlton, W.H.; Evans, A.G.; Geary, L.A.; Murphy, C.E. Jr.; Strom, R.N.

    1992-12-31

    This document on strontium is published as a part of the Radiological Assessment Program (RAP). It is the sixth in a series of eight documents on individual radioisotopes released to the environment as a result of SRS (Savannah River Site) operations. Strontium exists in the environment as a result of above-ground nuclear weapons tests, the Chernobyl accident, the destruction of satellite Cosmos 954, small releases from reactors and reprocessing plants, and the operation of industrial, medical, and educational facilities. Strontium has been produced at SRS during the operation of 5 production reactors. About 300 curies of radiostrontium were released into streams in the late 50s and 60s, primarily from leaking fuel elements in reactor storage basins. Smaller quantities were released from the fuel reprocessing operations. About 400 Ci were released to seepage basins. A much smaller quantity, about 2 Ci, was released to the atmosphere. The overall radiological impact of SRS releases on the offsite maximum individual can be characterized by total doses of 6.2 mrem (atmospheric) and 1.4 mrem (liquid), compared with a dose of 12,960 mrem from non-SRS sources during the same period of time. Radiostrontium releases have resulted in a negligible risk to the environment and the population it supports.

  5. Carnitine Deficiency and Pregnancy

    Directory of Open Access Journals (Sweden)

    Anouk de Bruyn

    2015-01-01

    Full Text Available We present two cases of carnitine deficiency in pregnancy. In our first case, systematic screening revealed L-carnitine deficiency in the first born of an asymptomatic mother. In the course of her second pregnancy, maternal carnitine levels showed a deficiency as well. In a second case, a mother known with carnitine deficiency under supplementation was followed throughout her pregnancy. Both pregnancies had an uneventful outcome. Because carnitine deficiency can have serious complications, supplementation with carnitine is advised. This supplementation should be continued throughout pregnancy according to plasma concentrations.

  6. Comment on: 'The strontium isotopic composition of seawater and seawater-oceanic crust interaction' by E.T.C. Spooner

    International Nuclear Information System (INIS)

    Brass, G.W.; Turekian, K.L.

    1977-01-01

    Various processes have been proposed as the source of strontium to the oceans but there is no evidence to support the mechanism of release of relatively unradiogenic strontium from deep dea basalts to sea-water. (B.D.)

  7. Strontium migration in a crystalline medium: effects of the presence of bentonite colloids.

    Science.gov (United States)

    Albarran, Nairoby; Missana, Tiziana; García-Gutiérrez, Miguel; Alonso, Ursula; Mingarro, Manuel

    2011-03-25

    The effects of bentonite colloids on strontium migration in fractured crystalline medium were investigated. We analyzed first the transport behaviour of bentonite colloids alone at different flow rates; then we compared the transport behaviour of strontium as solute and of strontium previously adsorbed onto stable bentonite colloids at a water velocity of approximately 7.1·10(-6)m/s-224m/yr. Experiments with bentonite colloids alone showed that - at the lowest water flow rate used in our experiments (7.1·10(-6)m/s) - approximately 70% of the initially injected colloids were retained in the fracture. Nevertheless, the mobile colloidal fraction, moved through the fracture without retardation, at any flow rate. Bentonite colloids deposited over the fracture surface were identified during post-mortem analyses. The breakthrough curve of strontium as a solute, presented a retardation factor, R(f)~6, in agreement with its sorption onto the granite fracture surface. The breakthrough curve of strontium in the presence of bentonite colloids was much more complex, suggesting additional contributions of colloids to strontium transport. A very small fraction of strontium adsorbed on mobile colloids moved un-retarded (R(f)=1) and this fraction was much lower than the expected, considering the quantity of strontium initially adsorbed onto colloids (90%). This behaviour suggests the hypothesis of strontium sorption reversibility from colloids. On the other hand, bentonite colloids retained within the granite fracture played a major role, contributing to a slower strontium transport in comparison with strontium as a solute. This was shown by a clear peak in the breakthrough curve corresponding to a retardation factor of approximately 20. Copyright © 2010 Elsevier B.V. All rights reserved.

  8. Strontium incorporates at sites critical for bone mineralization in rats with renal failure

    International Nuclear Information System (INIS)

    Oste, Line; Verberckmoes, Steven C.; Behets, Geert J.; Dams, Geert; Bervoets, An R.; De Broe, Marc E.; D'Haese, Patrick C.; Van Hoof, Viviane O.; Bohic, Sylvain; Drakopoulos, Michael

    2007-01-01

    We previously demonstrated the development of a mineralization defect during strontium administration and its reversibility after withdrawal in rats with chronic renal failure. Recently, strontium ranelate has been introduced as a therapeutic agent for osteoporosis. However, caution has to be taken, as this bone disorder mainly develops in elderly people who may present a moderately decreased renal function. In order to assess the ultra-structural localization of strontium in bone and thereby to get a better insight into the element's systemic effects on bone, synchrotron-based x-ray micro-fluorescence was applied, which showed that after 2 weeks of strontium loading (2 g l -1 in drinking water) in rats with renal failure, concomitant with the development of impaired mineralization, the element was localized mainly at the outer edge of the mineralized bone, while after longer loading periods, a more homogeneous distribution was found. After washout, strontium was found at sites deeper within the trabeculae, while newly deposited low-strontium-containing mineral was found at the outer edges. Synchrotron x-ray micro-diffraction analysis showed that strontium is incorporated in the apatite crystal lattice through exchange with calcium. The results show that strontium is initially incorporated in bone at sites of active bone mineralization, close to the osteoid/mineralization front.Most likely, strontium binds to matrix proteins serving as crystal nucleation points and by hetero-ionic substitution with calcium within the hydroxyapatite crystals, thereby impairing further hydroxyapatite formation. After withdrawal, strontium is released from these sites, by which mineralization is restored and the previously formed strontium-containing hydroxyapatite is buried under a new layer of mineralized bone. (authors)

  9. Antiferromagnetic ordering states of oxygen-deficient NdBa2Cu3O6+x and Nd1+yBa2-yCu3O6+x single crystals

    DEFF Research Database (Denmark)

    Brecht, E.; Schweiss, P.; Wolf, T.

    1999-01-01

    The paper describes a study of the antiferromagnetic ordering of oxygen-deficient Nd1 + yBa2 - yCu3O6 + x single crystals. In pure, stoichiometric samples, y = 0, with different oxygen contents x in the Cu(1) plane (0.02AFI) phase appears to be stable down to 316 m...... of this reordering suggests that the Nd3+ ions on Ba sites are very effective defects forcing the AFIAFII reordering. The mechanism of reordering is explained in terms of the creation of Cu2+ moments within the Cu(1) layer due to the Nd3+ ions on Ba sites, which via polarization lead to an effective ferromagnetic...

  10. Oxygen safety

    Science.gov (United States)

    ... sure you have working smoke detectors and a working fire extinguisher in your home. If you move around the house with your oxygen, you may need more than one fire extinguisher in different locations. Smoking can be very dangerous. No one should smoke ...

  11. Anion and cation diffusion in barium titanate and strontium titanate; Anionen- und Kationendiffusion in Barium- und Strontiumtitanat

    Energy Technology Data Exchange (ETDEWEB)

    Kessel, Markus Franz

    2012-12-19

    Perovskite oxides show various interesting properties providing several technical applications. In many cases the defect chemistry is the key to understand and influence the material's properties. In this work the defect chemistry of barium titanate and strontium titanate is analysed by anion and cation diffusion experiments and subsequent time-of-flight secondary ion mass spectrometry (ToF-SIMS). The reoxidation equation for barium titanate used in multi-layer ceramic capacitors (MLCCs) is found out by a combination of different isotope exchange experiments and the analysis of the resulting tracer diffusion profiles. It is shown that the incorporation of oxygen from water vapour is faster by orders of magnitude than from molecular oxygen. Chemical analysis shows the samples contain various dopants leading to a complex defect chemistry. Dysprosium is the most important dopant, acting partially as a donor and partially as an acceptor in this effectively acceptor-doped material. TEM and EELS analysis show the inhomogeneous distribution of Dy in a core-shell microstructure. The oxygen partial pressure and temperature dependence of the oxygen tracer diffusion coefficients is analysed and explained by the complex defect chemistry of Dy-doped barium titanate. Additional fast diffusion profiles are attributed to fast diffusion along grain boundaries. In addition to the barium titanate ceramics from an important technical application, oxygen diffusion in cubic, nominally undoped BaTiO{sub 3} single crystals has been studied by means of {sup 18}O{sub 2}/{sup 16}O{sub 2} isotope exchange annealing and subsequent determination of the isotope profiles in the solid by ToF-SIMS. It is shown that a correct description of the diffusion profiles requires the analysis of the diffusion through the surface space-charge into the material's bulk. Surface exchange coefficients, space-charge potentials and bulk diffusion coefficients are analysed as a function of oxygen partial

  12. Decorporation of mixture of strontium and cesium isotopes with domestic mineral waters

    International Nuclear Information System (INIS)

    Slavov, S.; Filev, G.; Kiradzhiev, G.

    1990-01-01

    The possibilities of Bulgarian mineral waters to decorporate mixtures of strontium and cesium radioisotopes, simultaneous entering the body, were studied. A modified effect in respect to radioactive strontium was found. Modification of the effect of mixing two diferent types of mineral waters was not proven. No effect was found of potassium-containing mineral water on radioactive cesium kinetics. 1 tab., 7 refs

  13. Full-Scale and Bench-Scale Studies on the Removal of Strontium from Water (abstract)

    Science.gov (United States)

    Strontium (Sr) is a natural and commonly occurring alkaline earth metal which has an oxidation state of +2 under normal environmental conditions. Stable strontium is suspended in water and is dissolved after water runs through rocks and soil. It behaves very similar to calcium. G...

  14. Marking pike fry otoliths with alizarin complexone and strontium : an evaluation of methods

    DEFF Research Database (Denmark)

    Skov, Christian; Grønkjær, P.; Nielsen, C.

    2001-01-01

    Laboratory experiments demonstrated that both alizarin complexone and strontium are useful in mass marking of pike Esox lucius fry otoliths. Visual detection of alizarin complexone marks was considered more reliable than the quantitative analysis of strontium for differentiating marked and unmarked...

  15. Comparison of modification with strontium and the refining with antimony in A 356 aluminium alloys

    International Nuclear Information System (INIS)

    Fuoco, Ricardo; Correa, Edison Roberto; Correa, Alzira V.O.; Bocalini Junior, Mario

    1992-01-01

    Strontium and Antimony treated A356 aluminium alloy samples were metallographically characterized in the as cast and solution and aged conditions. Antimony treated alloy has shown slower spheroidizing kinetics of the Silicon particles during solution treatment, lower porosity level and higher tensile strength and elongation than Strontium treated one. (author)

  16. Oxygen therapy - infants

    Science.gov (United States)

    ... breathe increased amounts of oxygen to get normal levels of oxygen in their blood. Oxygen therapy provides babies with the extra oxygen. Information Oxygen is a gas that the cells in your body need to work properly. The ...

  17. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... increased need for iron during growth spurts. Older adults, especially those over age ... athletes. Athletes, especially young females, are at risk for iron deficiency. Endurance ...

  18. Iodine deficiency disorders

    Energy Technology Data Exchange (ETDEWEB)

    Ali, S M [Pakistan Council for Science and Technology, Islamabad (Pakistan)

    1994-12-31

    Iodine deficiency (IDD) is one of the common problem in the diet. Iodine deficiency as prevalence of goiter in population occurs in the mountainous areas. There is consensus that 800 million people are at risk of IDD from living in iodine deficient area and 190 million from goiter. Very high prevalence of IDD in different parts of the world are striking. It has generally observed that in iodine-deficient areas about 50% are affected with goiter, 1-5% from cretinsim and 20% from impaired mental and/or mortor function. (A.B.).

  19. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Small Business Innovation Research (SBIR) and Small Business Technology Transfer (STTR) programs. Our ... more information about Donor Iron Deficiency Study - Red Blood Cells ...

  20. DETERMINATION OF STRONTIUM IONS IN WATERS WITH A HIGH CONTENT OF SODIUM IONS

    Directory of Open Access Journals (Sweden)

    Tatiana Mitina

    2015-06-01

    Full Text Available This paper reports on the influence of sodium ions on experimental determination of strontium ions concentration in waters with a high content of sodium ions by using emission flame photometry and atomic absorption spectroscopy. For the method of emission flame photometry it was shown that at a wavelength of 460.7 nm (spectral emission line of strontium the emission is linearly dependent on the concentration of sodium ions. The greatest impact of high concentrations of sodium ions on the result of determination the strontium ions concentration has been registered at low levels of strontium. The influence of nitric acid on the results is also discussed. In the case of using atomic absorption spectroscopy method no influence of sodium ions and nitric acid on the results of determination the strontium ions concentration was revealed. The metrological characteristics of both methods are evaluated.

  1. Application of empore TM strontium rad disks to the analysis of radiostrontium in environmental water samples

    International Nuclear Information System (INIS)

    Smith, L.L.; Seely, D.C.; Shannon, R.T.

    1996-01-01

    A solid phase extraction method for analyzing radioactive strontium in surface, ground, and drinking waters is presented. Strontium is simply isolated by pulling an acidified sample aliquot through an Empore TM strontium rad disk with a vacuum, and the disk is subsequently assayed for beta activity. The method is efficient, safe, reliable, and potentially field deployable. Sample preparation and counting source preparation may be condensed into a single procedure, thereby improving efficiency and eliminating many potential sources of laboratory error. Moreover, many of the hazardous chemicals associated with traditional strontium procedures are eliminated. Samples are easily batched, and a one-liter sample may be prepared with as little as 20 min of effort. For a one-liter aqueous sample, up to 3 mg of strontium can be retained by the disks. Chemical and radiometric interferences are discussed. (orig.)

  2. Study of the separation of strontium from solutions which imitate natural waters of increased mineralization

    International Nuclear Information System (INIS)

    Golub, A.M.; Voitko, I.N.; Glushchenko, L.V.; Mitrofanova, O.G.; Zyryanova, N.P.

    1976-01-01

    It has been shown by experiments on synthetically prepared solutions that it is possible to separate strontium and calcium by carbonate precipitation from the larger part of the magnesium accompanying them in natural high mineral waters. In this way the residual content of strontium is reduced to a value of 40-50 mg/liter and, under conditions of removing CO 2 from the solution, to 5-10 mg/liter. The high ionic strength of the solution prevented a more complete precipitation of strontium. Magnesium may be isolated from the filtrate after precipitation of the calcium-strontium mixture. The possibility has been shown of isolating strontium from the mixture of carbonates by means of pyrolysis at 1100-1200 0 and the selective solution of SrO in hot water

  3. Atomization of magnesium, strontium, barium and lead nitrates on surface of graphite atomizers

    International Nuclear Information System (INIS)

    Nagdaev, V.K.; Pupyshev, A.A.

    1982-01-01

    Modelling of the processes on graphite surface using differential-thermal analysis and graphite core with identification of decomposition products of magnesium, strontium, barium and lead nitrates by X-ray analysis has shown that carbon promotes the formation of strontium, barium and lead carbonates. The obtained temperatures of strontium and barium carbonate decomposition to oxides agree satisfactorily with calculation ones. Magnesium nitrate does not react with carbon. Formation of strontium and barium carbonates results in considerable slowing down of the process of gaseous oxide dissociation. Lead carbonate is unstable and rapidly decomposes to oxide with subsequent reduction to free metal. Formation of magnesium, strontium and barium free atoms is connected with appearance of gaseous oxides in analytical zone. Oxide and free metal lead are present on graphite surface simultaneously

  4. Characteristics of strontium-doped ZnO films on love wave filter applications

    International Nuclear Information System (INIS)

    Water, Walter; Yan, Y.-S.

    2007-01-01

    The effect of dopant concentrations in strontium-doped ZnO films on Love wave filter characteristics was investigated. Strontium-doped ZnO films with a c-axis preferred orientation were grown on ST-cut quartz by radio frequency magnetron sputtering. The crystalline structures and surface morphology of films were studied by X-ray diffraction, scanning electron microscopy and atomic force microscopy. The electromechanical coupling coefficient, dielectric constant, and temperature coefficient of frequency of filters were then determined using a network analyzer. A uniform crystalline structure and smooth surface of the ZnO films were obtained at the 1-2 mol% strontium dopant level. The electromechanical coupling coefficient of the 1 mol% strontium-doped ZnO film reaches a maximum of 0.61%, and the temperature coefficient of frequency declines to + 12.87 ppm/deg. C at a 1.5 mol% strontium dopant level

  5. Formation of barium strontium titanate powder by solid state reaction using different calcination temperatures

    International Nuclear Information System (INIS)

    Teoh Wah Tzu; Ahmad Fauzi Mohd Noor; Zainal Arifin Ahmad

    2002-01-01

    The unique electrical properties of large permittivity in Barium Strontium Titanate have been widely used to make capacitors; it can be produced by solid state reaction. In this study, the mixture of Barium Carbonate, Strontium Carbonate and Titanium Dioxide was calcined at 500 degree C, 1000 degree C, 1100 degree C , 1150 degree C, 1200 degree C, 1250 degree C and 1300 degree C. The results of the phases change in each stage were investigated via X ay Diffraction. The results show that the formation of Barium Strontium Titanate started at 1100 degree C with the presence of other phases. The mixture is fully reacted to form Barium Strontium Titanate at 1150 degree C. Only Barium Strontium Titanate was formed as the calcination temperature was set higher. (Author)

  6. Strontium and calcium accumulation in fish as affected by food composition

    International Nuclear Information System (INIS)

    Ophel, I.L.; Judd, J.M.

    1976-01-01

    Radioactive tracers ( 85 Sr and 47 Ca) were used to investigate the effects of food composition on the accumulation of strontium and calcium by fish and their discrimination between these two elements. The total amount of calcium assimilated by fish was the same for all experimental conditions. Calcium not obtainable from food was absorbed from the water, even when the water concentration was less than 10 mg Ca/l. The major discriminatory process occurred during direct (gill) uptake from water. Gut uptake provided least discrimination against strontium. Strontium content of fish was closely related to the Sr/Ca ratio in their food. Strontium assimilation was found to be a function of: the Sr/Ca ratios of food and water, the amounts of calcium derived from each source and the biological discrimination against strontium relative to calcium

  7. Baseline concentrations of strontium and 90Sr in seawater from the northern Gulf

    International Nuclear Information System (INIS)

    Uddin, S.; Al Ghadban, A.N.; Behbahani, M.

    2013-01-01

    Highlights: • This is the first baseline for strontium and 90 Sr from northern Gulf. • The total strontium concentration is much higher than reported for other oceans. • The Sr/salinity ratio correlates well with global averages. • High Sr might be due to increased salinity/CaCo 3 dissolution in acidifying Gulf waters. -- Abstract: Baseline concentration of strontium and Sr-90 in Gulf is presented. The strontium concentration is much higher than reported for other oceanic waters, while the Sr-90 concentration is low at 0.7–1.0 mBq l −1 , that represents the background level following nuclear tests and can be used as an effective tracer in case of any radioactive release in the region. The strontium concentration is primarily related to the increasing salinity off the Gulf coast

  8. High temperature dielectric relaxation anomaly of Y3+ and Mn2+ doped barium strontium titanate ceramics

    International Nuclear Information System (INIS)

    Yan, Shiguang; Mao, Chaoliang; Wang, Genshui; Yao, Chunhua; Cao, Fei; Dong, Xianlin

    2014-01-01

    Relaxation like dielectric anomaly is observed in Y 3+ and Mn 2+ doped barium strontium titanate ceramics when the temperature is over 450 K. Apart from the conventional dielectric relaxation analysis method with Debye or modified Debye equations, which is hard to give exact temperature dependence of the relaxation process, dielectric response in the form of complex impedance, assisted with Cole-Cole impedance model corrected equivalent circuits, is adopted to solve this problem and chase the polarization mechanism in this paper. Through this method, an excellent description to temperature dependence of the dielectric relaxation anomaly and its dominated factors are achieved. Further analysis reveals that the exponential decay of the Cole distribution parameter n with temperature is confirmed to be induced by the microscopic lattice distortion due to ions doping and the interaction between the defects. At last, a clear sight to polarization mechanism containing both the intrinsic dipolar polarization and extrinsic distributed oxygen vacancies hopping response under different temperature is obtained.

  9. Electronic and magnetic properties of 3d transition metal-doped strontium clusters: Prospective magnetic superatoms

    International Nuclear Information System (INIS)

    Chauhan, Vikas; Sen, Prasenjit

    2013-01-01

    Highlights: • Structural, electronic and magnetic properties of TM-Sr clusters are studied using DFT methods. • CrSr 9 and MnSr 10 have enhanced stability in the CrSr n and MnSrn series. • These two clusters behave as magnetic superatoms. • A qualitative understanding of the magnetic coupling between two superatom units is offered. • Reactivity of these superatoms to molecular oxygen also studied. - Abstract: Structural, electronic and magnetic properties of 3d transition metal doped strontium clusters are studied using first-principles electronic structure methods based on density functional theory. Clusters with enhanced kinetic and thermodynamic stability are identified by studying their hardness, second order energy difference and adiabatic spin excitation energy. CrSr 9 and MnSr 10 are found to have enhanced stability. They retain their structural identities in assemblies, and are classified as magnetic superatoms. A qualitative understanding of the magnetic coupling between two cluster units is arrived at. Reactivity of these superatoms with O 2 molecule is also studied. Prospects for using these magnetic superatoms in applications are discussed

  10. Dosing of low-activity strontium 90 in human bone ashes - A method based on the quantitative precipitation of strontium nitrate

    International Nuclear Information System (INIS)

    Patti, Francois; Bullier, Denise

    1969-02-01

    The specific separation of strontium nitrate in bone ash samples by red fuming nitric acid requires a succession of precipitation varying in number according to the weight of ashes. The interest of the technique is to define the experimental conditions required for a reproducible quantitative separation of strontium. The operating process tested on over 1.500 samples allowed to obtain chemical yields of about 90 per cent. (authors) [fr

  11. Migration of strontium in the food chain of plants, animals and man - problems and risks

    International Nuclear Information System (INIS)

    Anke, M.; Seifert, M.; Jaritz, M.; Schaefer, U.; Mueller, R.; Hoppe, Ch.

    2008-01-01

    The aims of investigation were to follow the Sr transport in the food chain from the flora to the fauna and humans, and its dependence on the geological origin og the plant site, industrial emissions, the age and site of plants, the part of plant used for nutrition and the strontium content in the drinking water, to determine the Sr intake of humans with the help of the duplicate method, and to estimate the apparent absorption rate and balance of strontium depending on of the form of diet (mixed or ovolactovegetarian), sex, season, age, region (geological origin of the living space) and method of intake measurement (duplicate or basket method). Strontium, an ultra trace element widespread in the earth's crust, is not essential and only mildly toxic for plants, animals and man according to current knowledge. The biological essentiality of Sr has not been investigated yet. Amoeba species living in sea water use Sr for the formation of their skeleton instead of Ca. There have been no Sr deficiency experiments in animals. Sr is assumed to have cariostatic effect. The toxicity of Sr to humans is not high but is discussed controversially. Therefore, the interest in this ultra trace element used to be exclusively concentrated on the ''9 0 Sr isotope released after nuclear tests. The Sr content in the flora is determined by the geological origin of the habitat and anthropogenic Sr emissions. Syenite and granite weathering soils, moor and loess sites produce a Sr-rich vegetation, whereas plants growing on alluvial riverside and Muschelkalk weathering soils are poor in Sr. The age of plants only has an insignificant effect on their Sr content. Leafy dicotyledons store much, while monocotyledons store less Sr. Root and stem thickenings (carrots, kohlrabi) accumulate medium Sr amounts, whereas fruit and seeds (tuber) are Sr-poor. The winter grazing of game is Sr-rich. The fauna reflects the Sr offer very well through the Sr content in the body or particular tissues. The

  12. Determination of mineral radioactive strontium-{sup 90} in urines; Recherche du strontium mineral radioactif {sup 90}Sr dans les urines

    Energy Technology Data Exchange (ETDEWEB)

    Jeanmaire, L; Jammet, H; Bertrand, S [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1959-07-01

    An analytical procedure for radioactive strontium in urine is described. As a first step, a precipitation of calcium oxalate performed on the urine, allows to detect the presence of various fission products and particularly of strontium which is carried by the precipitate. Strontium can then be selectively separated on ion exchange resins. By studying the growth curve of {beta} activity, it is possible to determine the activities which may be attributed to {sup 89}Sr and {sup 90}Sr respectively. (author) [French] Cet article decrit une technique de dosage du strontium radioactif dans les urines. Dans un premier stade, une precipitation d'oxalate de calcium effectuee sur l'urine permet de deceler la presence de differents produits de fission et en particulier du strontium qui est entraine sur ce precipite. Il est possible ensuite de separer selectivement le strontium au moyen de resines echangeuses d'ions. L'examen de le courbe de croissance de l'activite {beta} permet de determiner les activites dues respectivement a {sup 89}Sr et {sup 90}Sr. (auteur)

  13. Barium strontium titanate powders prepared by spray pyrolysis

    International Nuclear Information System (INIS)

    Brankovic, G.; Brankovic, Z.; Goes, M.S.; Paiva-Santos, C.O.; Cilense, M.; Varela, J.A.; Longo, E.

    2005-01-01

    Ultasonic spray pyrolysis (SP) has been investigated for the production of the barium strontium titanate (BST) powders from the polymeric precursors. The processing parameters, such as flux of aerosol and temperature profile inside the furnace, were optimized to obtain single phase BST. The powders were characterized by the methods of X-ray diffraction analysis, SEM, EDS and TEM. The obtained powders were submicronic, consisting of spherical, polycrystalline particles, with internal nanocrystalline structure. Crystallite size of 10 nm, calculated using Rietveld refinement, is in a good agreement with results of HRTEM

  14. Run-off of strontium with melting snow in spring

    International Nuclear Information System (INIS)

    Quenild, C.; Tveten, U.

    1986-09-01

    When assessing the consequences of atmospheric releases caused by a large reactor accident, one usually finds that the major contributions to the dose are via nutrition and from exposure to radiation from radioactive materials deposited on ground. The experiment described is concerned with run-off from agricultural surface which has been contaminated with strontiom while covered with snow. Migration experiments show a significant difference between summer and winter conditions. Roughly 54% of the strontium with which the experimental area was contaminated, ran off with the melt-water. Under winter conditions, portions of the contaminant will flow with the melt-water without coming in contact with the soil

  15. Determination of strontium-90 in the environmental samples at PINSTECH

    International Nuclear Information System (INIS)

    Perveen, N.; Aziz, A.

    1979-01-01

    Strontium-90 a bone seeking radionuclide and a long lived beta emitter is one of the toxic radionuclides detected in the environment arising mainly from the fall out from nuclear detonations. Its concentration in various environmental media such as air, precipitation, surface water, vegetables and other items of diet was measured. This report describes the method of collection, treatment and radiochemical analyses of environmental samples for the determination of Sr-90. The levels of Sr-90 concentration in these media are also recorded. (authors)

  16. Synthesis and thermal properties of strontium and calcium peroxides

    Science.gov (United States)

    Philipp, Warren H.; Kraft, Patricia A.

    1989-01-01

    A practical synthesis and a discussion of some chemical properties of pure strontium peroxide and calcium peroxide are presented. The general synthesis of these peroxides involves precipitation of their octahydrates by addition of H2O2 to aqueous ammoniacal Sr(NO3)2 or CaCl2. The octahydrates are converted to the anhydrous peroxides by various dehydration techniques. A new x-ray diffraction powder pattern for CaO2 x 8H2O is given from which lattice parameters a=6.212830 and c=11.0090 were calculated on the basis of the tetragonal crystal system.

  17. Spectroscopy of strontium Rydberg states using electromagnetically induced transparency

    International Nuclear Information System (INIS)

    Mauger, S; Millen, J; Jones, M P A

    2007-01-01

    We report on the all-optical detection of Rydberg states in an effusive atomic beam of strontium atoms using electromagnetically induced transparency (EIT). Using narrow-linewidth CW lasers we obtain an EIT linewidth of 5 MHz. To illustrate the high spectroscopic resolution offered by this method, we have measured isotope shifts of the 5s18d 1 D 2 and 5s19s 1 S 0 Rydberg states. This technique could be applied to high-resolution, non-destructive measurements of ultra-cold Rydberg gases and plasmas. (fast track communication)

  18. Strontium vanadate nanoribbons: Synthesis, characterization and detection of dopamine

    International Nuclear Information System (INIS)

    Zhou, Qing; Shao, Mingwang; Chen, Tao; Xu, Hongyan

    2010-01-01

    Large-scale, high-purity and uniform strontium vanadate (Sr 2 V 2 O 7 ) nanoribbons were easily synthesized via a hydrothermal process without any surfactants. The as-prepared products were up to hundreds of micrometers in length, 200-600 nm in width, and 20 nm in thickness. These nanomaterials were employed to modify glassy carbon electrode, which displayed excellent electrochemical sensitivity in detecting dopamine in the presence of ascorbic acid. A linear relationship between the concentrations of dopamine and its oxidation peak currents was obtained. The modified electrode exhibited high reproducibility and stability, which might be found potential application in the biosensors.

  19. Magnetite effect in radionuclide retention : cesium, strontium, molybdenum and selenium

    International Nuclear Information System (INIS)

    Rovira, M.; Casas, I.; Gimenez, J.; Clarens, F.; Pablo, J. de

    2004-01-01

    In this work we have investigated the interaction of magnetite with cesium, strontium, molybdenum and selenium, in the frame of radionuclide retention by canister corrosion products. For each radionuclide, the retention on magnetite has been studied as a function of pH and the mass/ volume ratio. The experimental results have been modeled by means of Surface Complexation Models (SCM), that constitute a tool that allows an approach to sorption mechanisms in a wide range of experimental conditions taking into account electrostatic interactions at the mineral-water interface.(Author)

  20. Experimental study of strontium sorption on fissure filling material

    Energy Technology Data Exchange (ETDEWEB)

    Eriksen, T E; Cui, Daqing [Royal Institute of Technology, Stockholm (Sweden). Dept. of Chemistry

    1994-12-01

    We have carried out a comparative study of sorption and desorption of strontium in groundwater on separated magnetic and size fractions of fissure filling material taken from natural fissures in granitic rock. Complete reversibility of the sorption process was demonstrated by identical Freundlich isotherms, isotopic exchangeability and pH dependence of the distribution coefficients Rd. The sorption was found to be strongly pH dependent in the range 3-11. The pH effect can be accommodated in the sorption model by considering the surface areas and surface charges of the minerals in the fissure filling material. 20 refs, 9 figs, 3 tabs.

  1. Experimental study of strontium sorption on fissure filling material

    International Nuclear Information System (INIS)

    Eriksen, T.E.; Cui, Daqing

    1994-12-01

    We have carried out a comparative study of sorption and desorption of strontium in groundwater on separated magnetic and size fractions of fissure filling material taken from natural fissures in granitic rock. Complete reversibility of the sorption process was demonstrated by identical Freundlich isotherms, isotopic exchangeability and pH dependence of the distribution coefficients Rd. The sorption was found to be strongly pH dependent in the range 3-11. The pH effect can be accommodated in the sorption model by considering the surface areas and surface charges of the minerals in the fissure filling material. 20 refs, 9 figs, 3 tabs

  2. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... carrying red blood cells, your heart has to work harder to move oxygen-rich blood through your ... tissues need a steady supply of oxygen to work well. Normally, hemoglobin in red blood cells takes ...

  3. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... exploring about iron-deficiency anemia. Read more New treatments for disorders that lead to iron-deficiency anemia. We are ... and other pathways. This could help develop new therapies for conditions that ... behavior, thinking, and mood during adolescence. Treating anemia in ...

  4. Muscle phosphorylase kinase deficiency

    DEFF Research Database (Denmark)

    Preisler, N; Orngreen, M C; Echaniz-Laguna, A

    2012-01-01

    To examine metabolism during exercise in 2 patients with muscle phosphorylase kinase (PHK) deficiency and to further define the phenotype of this rare glycogen storage disease (GSD).......To examine metabolism during exercise in 2 patients with muscle phosphorylase kinase (PHK) deficiency and to further define the phenotype of this rare glycogen storage disease (GSD)....

  5. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... loss and lead to iron-deficiency anemia. Common causes of blood loss that lead to iron-deficiency anemia include: Bleeding in your GI tract, from an ulcer, colon cancer, or regular use of medicines such as aspirin ...

  6. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... iron-deficiency anemia. Search the NIH Research Portfolio Online Reporting Tools (RePORT) to learn about research that ... iron-deficiency anemia in blood donors affects the quality of donated red blood cells, such as how ...

  7. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... blocks the intestine from taking up iron. Other medical conditions Other medical conditions that may lead to iron-deficiency anemia ... daily amount of iron. If you have other medical conditions that cause iron-deficiency anemia , such as ...

  8. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... anemia if you have certain risk factors , including pregnancy. To prevent iron-deficiency anemia, your doctor may recommend you eat heart-healthy foods or control other conditions that can cause iron-deficiency anemia. Blood tests to screen for ...

  9. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Are you curious about how inflammation from chronic diseases can cause iron-deficiency anemia? Read more When there is ... DBDR) is a leader in research on the causes, prevention, and treatment of blood diseases, including iron-deficiency anemia. Search the NIH Research ...

  10. 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

  11. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Topics section only, or the News and Resources section. NHLBI Entire Site NHLBI Entire Site Health ... español Iron-deficiency anemia is a common type of anemia that occurs if you do not have enough iron in your body. People with mild or moderate iron-deficiency anemia ...

  12. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... for iron-deficiency anemia. Lifestyle habits Certain lifestyle habits may increase your risk for iron-deficiency anemia, including: Vegetarian or vegan eating patterns. Not eating enough iron-rich foods, such as meat and fish, may result in ...

  13. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... blood cells. Iron-deficiency anemia usually develops over time because your body’s intake of iron is too ... clamping of your newborn’s umbilical cord at the time of delivery. This may help prevent iron-deficiency ...

  14. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... other conditions that can cause iron-deficiency anemia. Blood tests to screen for iron-deficiency anemia To screen ... check the size of your liver and spleen. Blood tests Based on results from blood tests to screen ...

  15. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... also are hoping to determine which iron supplements work best to treat iron-deficiency anemia in children who do not consume the daily recommended amount of iron. Read less Participate in NHLBI Clinical Trials We lead or sponsor many studies related to iron-deficiency anemia. See if you ...

  16. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... en español Iron-deficiency anemia is a common type of anemia that occurs if you do not ... iron-deficiency anemia and help rule out other types of anemia. Treatment will explain treatment-related complications ...

  17. Iron-Deficiency Anemia

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    Full Text Available ... anemia. Return to Signs, Symptoms, and Complications to review signs and symptoms as well as complications from iron-deficiency ... NIH]) Heavy Menstrual Bleeding (Centers for Disease Control and ... Dietary Supplement Fact Sheet (NIH) Iron-Deficiency Anemia (National Library ...

  18. 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 ...

  19. Iron-Deficiency Anemia

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    Full Text Available ... be at risk for iron-deficiency anemia. Lifestyle habits Certain lifestyle habits may increase your risk for iron-deficiency anemia, ... you are experiencing side effects such as a bad metallic taste, vomiting, diarrhea, constipation, or upset stomach. ...

  20. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... how we are using current research and advancing research to prevent iron-deficiency anemia. Participate in NHLBI Clinical Trials will explain our ongoing clinical studies that are investigating prevention strategies for iron-deficiency anemia. Signs, Symptoms, and Complications ...

  1. Separation and determination of strontium-90 in burnout nuclear fuel

    International Nuclear Information System (INIS)

    Khermann, A.; Katsvinkel', I.

    1975-01-01

    Developed was a simple and selective chromatographic method of the separation of strontium-90, by the content of which it is possible to judge about the degree of nuclear fuel burnup. Among the studied ion exchangers for strontium separation the best results are exhibited by strongly acidic organic cationite, i.e. vofatite (on the base of styrene, 8%-divinylbenzene) in the H + form. Elution was performed by hydrochloric or oxalic acids. The method allows to achieve a high degree of Sr-90 purification from other fission products. Using the method the Sr-90 content was determined in burnup fuel of the fuel elements of EK-10 type. At the fuel storage period less than 2 years it becomes necessary to determine both Sr-90 and Sr-89. Determination of Sr-90 in the presence of Sr-89 was made by daughter product of Sr-90 - Y-90, which is separated in ion-exchange coloumn. Some other methods of Sr-90 determination in the presence of Sr-89 are noted

  2. Sorption of strontium on bentonites from Slovak deposits

    International Nuclear Information System (INIS)

    Kufcakova, J.; Galambos, M.; Rajc, P.

    2005-01-01

    Sorption on bentonite from different Slovak deposits / Jelsovy potok, Kopernica and Lieskove has been investigated under various experimental conditions, such as contact time, pH, sorbate concentrations, presence of complementary cation. The sorption of strontium from aqueous solutions was investigated using a radiometric determination of distribution coefficient, Kd. The individual solutions were labelled with radiotracer. Radiation stability has been investigated, the higher sorption parameters were observed for the irradiated bentonites /tab.l/ , which can be explained by the increase of specific surface and change of solubility of the irradiated samples of bentonite. The presence of complementary cations, Na + , K + , NH 4 + , Ca 2+ , Mg 2+ and Ba 2+ depresses the sorption of Sr on bentonite. In the case of bentonite Kopernica the effectiveness in reducing the sorption of strontium by cations followed the order K + 4 + + 2+ 2+ 2+ . Results indicate that the sorption of Sr + on bentonite will be affected by the presence of high concentrations of various salts in the waste water effluents. (author)

  3. Physico-chemical studies for strontium sulfate radiation dosimeter

    Directory of Open Access Journals (Sweden)

    M.A.H. Rushdi

    2015-04-01

    Full Text Available Anhydrous strontium sulfate (SrSO4 has shown a promise candidate as a dosimeter for low dose applications producing unique EPR signals with γ-rays which it has a linear response relationship (r2 = 0.999 in the range of 1–100 Gy. The present study extended to evaluate the properties of strontium sulfate dosimeter in intermediate dose range of technology applications. It was observed that the intensity of the EPR signal at g = 2.01081 increases with a 3rd polynomial function in the range of 0.10–15 kGy. In addition, the radical (SO4− provides a stable signal with a good reproducibility (0.107%. Other physics characteristic including the collision of mass stopping power dependence of the system and the effect of atomic number in different energy regions were investigated. The uncertainty budget for high doses has obtained from the measurement with value of 3.57% at 2σ confidence level.

  4. Analysis of leachants from strontium chlorapatite glass ceramics

    International Nuclear Information System (INIS)

    Vijayalakshmi, S.; Ushalakshmi, K.; Annapoorani, S.; Sriram, S.; Uma Maheshwari, R.; Deivanayaki, R.; Sekar, J.K.; Sankaran, K.

    2013-01-01

    Strontium chlorapatite glass ceramics is being tried out as one of the candidate matrices for immobilizing pyrochemical salt waste produced in the nuclear industry. To find-out the suitability of such material for immobilising the waste, leaching of various constituents of the ceramics in water is required. Therefore, in Chemistry Group of IGCAR experiments are being carried out with simulated salt waste (chlorides of Li, Na, K, Cs, Ba, Nd and Ce) of pyrochemical reprocessing method for studying the utilisation of strontium chlorapatite glass ceramics towards the immobilization of radioactive waste. Leaching behaviour study requires the determination of alkali, alkaline earth and rare earth elements in the leachant solutions of the glass ceramic material. Apart from cations, leaching study of anions especially chloride is required as the chloride salts are used in pyrochemical experiments. Considering the good sensitivity of alkali elements in Flame-AES method, all the alkali elements were determined by flame-AES. Ba, Sr and rare earth elements in the leachant solutions were determined using ICP-OES. Chloride was determined using ISE and IC. Standardisation of instrumental techniques and the application of various techniques for the sample analysis will be discussed in the paper. (author)

  5. Structure and thermodynamic properties of molten strontium chloride

    International Nuclear Information System (INIS)

    Pastore, G.; Ballone, P.; Tosi, M.P.; Trieste Univ.

    1985-05-01

    Self-consistent calculations of pair distribution functions and thermodynamic properties are presented for a pair-potentials model of molten strontium chloride. The calculations extend to a strongly asymmetric ionic liquid an earlier assessment of bridge diagrams in a modified hypernetted chain approach to the liquid structure of alkali halides. Good agreement is found with computer simulation data obtained by de Leeuw with the same set of pair potentials, showing that the present approach incorporates genuine general features of liquid structure theory for multicomponent liquids with strong relative ordering of the component species. It is further shown that the strong correlations between the divalent cations, both in the model and in real molten strontium chloride, can be approximately reproduced on the basis of a simple one-component-plasma model, provided that dielectric screening is allowed for in the real liquid. This allows us to tentatively attribute the significant level of disagreement between a pair potentials model of this liquid and the neutron diffraction data of McGreevy and Mitchell to many-body distortions of the electronic shells of the ions. (author)

  6. Seawater strontium isotopes at the Cretaceous-Tertiary boundary

    Science.gov (United States)

    Macdougall, J. D.; Martin, E.

    1988-01-01

    Anomalously high values of Seawater Sr-87/Sr-86 near the Cretaceous-Tertiary (K-T) boundary have been reported. However, few of the data from the literature are from a single continuous section, and perhaps the most complete study of the boundary region, from a shallow marine limestone sequence in Alabama, showed elevated Sr-87/Sr-86 but no pronounced spike. Thus, in order to investigate the cause of the change in strontium isotopic composition, it is important to determine the exact nature and magnitude of the increase by studying in detail continuous sections through the boundary. If there is indeed a Sr isotope spike at the K-T boundary, it requires the addition of a large amount of radiogenic Sr to the oceans over a short time period, a phenomenon that may be linked to other large-scale environmental disturbances which occurred at that time. In order to address this question, a high-resolution strontium isotope study of foraminifera from three Deep Sea Drilling Project (DSDP) cores which recovered the K-T boundary section: Site 356 in the South Atlantic, Site 384 in the North Atlantic and Site 577 from the Shatsky Rise in the Pacific was initiated. The isotope measurements are being made on either single or small numbers of forams carefully picked and identified and in most cases examined by SEM before analysis. Because this work is not yet complete, conclusions drawn here must be viewed as tentative. They are briefly discussed.

  7. Textured strontium titanate layers on platinum by atomic layer deposition

    International Nuclear Information System (INIS)

    Blomberg, T.; Anttila, J.; Haukka, S.; Tuominen, M.; Lukosius, M.; Wenger, Ch.; Saukkonen, T.

    2012-01-01

    Formation of textured strontium titanate (STO) layers with large lateral grain size (0.2–1 μm) and low X-ray reflectivity roughness (∼ 1.36 nm) on Pt electrodes by industry proven atomic layer deposition (ALD) method is demonstrated. Sr(t-Bu 3 Cp) 2 , Ti(OMe) 4 and O 3 precursors at 250 °C were used to deposit Sr rich STO on Pt/Ti/SiO 2 /Si ∅200 mm substrates. After crystallization post deposition annealing at 600 °C in air, most of the STO grains showed a preferential orientation of the {001} plane parallel to the substrate surface, although other orientations were also present. Cross sectional and plan view transmission electron microscopy and electron diffraction analysis revealed more than an order of magnitude larger lateral grain sizes for the STO compared to the underlying multicrystalline {111} oriented platinum electrode. The combination of platinum bottom electrodes with ALD STO(O 3 ) shows a promising path towards the formation of single oriented STO film. - Highlights: ► Amorphous strontium titanate (STO) on platinum formed a textured film after annealing. ► Single crystal domains in 60 nm STO film were 0.2–1 μm wide. ► Most STO grains were {001} oriented.

  8. Study of interaction of the bacterium cupriavidus metallidurans with strontium

    International Nuclear Information System (INIS)

    Boussiga, Rim

    2010-01-01

    Cupriavidus metallidurans strain Ch 34 (previously known as Ralstonia metallidurans, Ralstonia eutropha, and Alcaligenes eutrophus) is an ideal subject to study heavy metal disturbance of cellular processes. Moreover, the capacity of C. metallidurans Ch 34 for in situ bioremediation was assessed and proved to be feasible on pilot scale. In this work, the molecular and physiological response to strontium cations (Sr 2+ ) by C.metallidurans Ch 34 was studied. Results showed that C. metallidurans Ch 34 resisted to high concentrations of Sr (120 m M) and that this resistance is not linked to the presence of its 2 large plasmid pMOL30 or pMOL28. During this study, a tctCBA-dependent tripartite tricarboxylate transport (TTT) system in strain Ch 34 was discovered. Transmission Electron Microscopy (TEM) observation of C.metallidurans challenged with strontium confirms the precipitation of Sr 2+ ) directly onto the surface of cells, inside and in the microenvironment around the cells. These results highlight the potential of C. metalliduras Ch 34 to endure environmental extremes and suggest that in situ bioremediation of Sr-containing waste with Ch 34 might be feasible.

  9. Rapid method for the radioactive strontium determination in natural samples; Brza metoda za odredjivanje radioaktivnog stroncija u prirodnim uzorcima

    Energy Technology Data Exchange (ETDEWEB)

    Grahek, Z; Kosutic, K; Lulic, S [Rudjer Boskovic Institute, Zagreb (Croatia)

    1997-12-31

    Radioactive strontium isotopes belong to the group of isotopes that are very dangerous for human health. Therefore radioactive strontium is regularly determined in natural samples. When determining strontium isotopes in natural samples, it is necessary to isolate strontium from the sample because strontium isotopes are pure {beta}-emitters. As natural samples contain much more calcium and sodium than strontium it is necessary to isolate a small quantity of strontium from large sample with simultaneous separation of calcium and other interfering elements. For this purposes an elegant method based on ion exchange chromatography has been developed. Namely, examinations with model system have shown that strontium may be separated from calcium on the column filled with anion exchanger and the mixture of the methanol and nitric acid as eluent. It was also shown that yttrium does not separate from strontium but elutes almost simultaneously with it. Yttrium may be separated from strontium on the column filled with cation exchanger DOWEX 50X8 and nitric acid as eluent. According to the above examinations, the procedure of isolation of strontium and yttrium from natural sample has been created (on assumption that {sup 90}Sr and {sup 90}Y in secular equilibrium in sample). Strontium and yttrium have been isolated from natural sample (standard IAEA A-7) on the column filled with the exchanger AMBERLITE CG-400 and the mixture of methanol and nitric acid as eluent. Strontium and yttrium have been separated on the column with cation exchanger. {sup 90}Sr has been determined through {sup 90}Y by counting the solid yttrium oxalate immediately upon isolation and separation from strontium. {sup 90}Sr has also been determined by counting {sup 90}Sr-{sup 90}Y in secular equilibrium after 15 days. The obtained results of determination of {sup 90}Sr through {sup 90}Y and through secular equilibrium {sup 90}Sr-{sup 90}Y correspond to the declared values of standard. (author). 2 figs., 1

  10. Hydrologic inferences from strontium isotopes in pore water from the unsaturated zone at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Marshall, B.D.; Futa, K.; Peterman, Z.E.

    1997-01-01

    Calcite is ubiquitous at Yucca Mountain, occurring in the soils and as fracture and cavity coatings within the volcanic tuff section. Strontium is a trace element in calcite, generally at the tens to hundreds of ppm level. Because calcite contains very little rubidium and the half-life of the 87 Rb parent is billions of years, the 87 Sr/ 86 Sr ratios of the calcite record the ratio in the water from which the calcite precipitated. Dissolution and reprecipitation does not alter these compositions so that, in the absence of other sources of strontium, one would expect the strontium ratios along a flow path to preserve variations inherited from strontium in the soil zone. Strontium isotope compositions of calcites from various settings in the Yucca Mountain region have contributed to the understanding of the unsaturated zone (UZ), especially in distinguishing unsaturated zone calcite from saturated zone calcite. Different populations of calcite have been compared, either to group them together or distinguish them from each other in terms of their strontium isotope compositions. Ground water and perched water have also been analyzed; this paper presents strontium isotope data obtained on pore water

  11. Preparation of strontium hexaferrite magnets from celestite and blue dust by mechanochemical route

    Directory of Open Access Journals (Sweden)

    Tiwary R.K.

    2008-01-01

    Full Text Available In the present investigation celestite (natural ore of strontium and blue dust (iron ore fines have been used for the preparation of strontium hexaferrite powder. The mechanical alloying process has been adopted to prepare strontium hexaferrite powder. The celestite after chemical upradation and physically upgraded blue dust alongwith sodium carbonate was taken for the preparation of strontium hexaferrite in this experiment. The high-energy planetary ball mill with tungsten carbide jar and ball was used to prepare strontium hexaferrite powder. A long time of ball milling for different duration has led to displacement solid-state reaction. At the end of each experiment the product was washed thoroughly and dried. The X-ray diffaction study after annealing shows the development of single-phase strontium hexaferrite after 40 hrs. of milling. The resultant powder was compacted under magnetic field and sintered to prepare the magnet after annealing the ferrite powder. The magnetic properties were measured by Pulse magneto meter. The moderate value of coercivity, remanence and energy product were observed in this sintered magnet. The work illustrates the feasibility to prepare strontium hexaferrite magnetic powders directly from natural ores which can reduce the total cost of production as compared to conventional method.

  12. Urinary strontium and the risk of breast cancer: A case-control study in Guangzhou, China

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Li-Juan [The School of Public Health, Sun Yat-sen University, 74 Zhongshan 2nd Rd, Guangzhou 510080 (China); Tang, Lu-Ying [The School of Public Health, Sun Yat-sen University, 74 Zhongshan 2nd Rd, Guangzhou 510080 (China); The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou 510630 (China); He, Jian-Rong [The School of Public Health, Sun Yat-sen University, 74 Zhongshan 2nd Rd, Guangzhou 510080 (China); Guangzhou Women and Children' s Medical Center, Guangzhou 510623 (China); Su, Yi; Cen, Yu-Ling; Yu, Dan-Dan [The School of Public Health, Sun Yat-sen University, 74 Zhongshan 2nd Rd, Guangzhou 510080 (China); Wu, Bang-Hua [The Guangdong Prevention and Treatment Center for Occupational Diseases, Guangzhou 510300 (China); Lin, Ying [The First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510080 (China); Chen, Wei-Qing [The School of Public Health, Sun Yat-sen University, 74 Zhongshan 2nd Rd, Guangzhou 510080 (China); Song, Er-Wei, E-mail: songerwei02@yahoo.com.cn [The Second Affiliated Hospital, Sun Yat-sen University, 107 Yanjiang West, Guangzhou 510120 (China); Ren, Ze-Fang, E-mail: renzef@mail.sysu.edu.cn [The School of Public Health, Sun Yat-sen University, 74 Zhongshan 2nd Rd, Guangzhou 510080 (China)

    2012-01-15

    Strontium has been widely used in industries like electronic and pharmacy. It has a carcinogenic potential, however, and no study has been conducted to evaluate its effects on cancer risk. The aim of this study was to explore the possible association between strontium and breast cancer risk in a case-control study including 240 incident invasive breast cancer patients and 246 age-matched controls. We measured the urinary concentrations of strontium by inductively coupled plasma mass spectrometry, and conducted face-to-face interviews to obtain information on potential breast cancer risk factors. Multivariable analysis was used to estimate the association. Creatinine-adjusted levels [median (25th, 75th) {mu}g/g] of strontium were 155.59 (99.05, 230.70) in the breast cancer patients and 119.62 (81.97, 163.76) in the controls. Women in the highest tertile of strontium showed 124% increased risk of breast cancer, when compared with those in the lowest tertile after adjustment for the potential risk factors [OR (95% CI): 2.24 (1.42-3.81)]. This association was particularly strong for HER2 positive breast cancer [OR (95% CI): 10.92 (3.53-33.77)], and only occurred among premenopausal women. These results suggest a potential role of strontium in the development of breast cancer and urge further studies on the environmental contamination and the physiological and pathological mechanisms of strontium.

  13. Strontium isotope geochemistry of soil and playa a deposits near Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Marshall, B.D.; Mahan, S.A.

    1994-01-01

    The isotopic composition of strontium contained in the carbonate fractions of soils provides an excellent tracer which can be used to test models for their origin. This paper reports data on surface coatings and cements, eolian sediments, playas and alluvial fan soils which help to constrain a model for formation of the extensive calcretes and fault infilling in the Yucca Mountain region. The playas contain carbonate with a wide range of strontium compositions; further work will be required to fully understand their possible contributions to the pedogenic carbonate system. Soils from an alluvial fan to the west of Yucca Mountain show that only small amounts of strontium are derived from weathering of silicate detritus. However, calcretes from a fan draining a carbonate terrane have strontium compositions dominated locally by the limestone strontium component. Although much evidence points to an eolian source for at least some of the strontium in the pedogenic carbonates near Yucca Mountain, an additional component or past variation of strontium composition in the eolian source is required to model the pedogenic carbonate system

  14. Organic composite-mediated surface coating of human acellular bone matrix with strontium.

    Science.gov (United States)

    Huang, Yi-Zhou; Wang, Jing-Jing; Huang, Yong-Can; Wu, Cheng-Guang; Zhang, Yi; Zhang, Chao-Liang; Bai, Lin; Xie, Hui-Qi; Li, Zhao-Yang; Deng, Li

    2018-03-01

    Acellular bone matrix (ACBM) provides an osteoconductive scaffold for bone repair, but its osteoinductivity is poor. Strontium (Sr) improves the osteoinductivity of bone implants. In this study, we developed an organic composite-mediated strontium coating strategy for ACBM scaffolds by using the ion chelating ability of carboxymethyl cellulose (CMC) and the surface adhesion ability of dopamine (DOPA). The organic coating composite, termed the CMC-DOPA-Sr composite, was synthesized under a mild condition, and its chemical structure and strontium ion chelating ability were then determined. After surface decoration, the physicochemical properties of the strontium-coated ACBM (ACBM-Sr) scaffolds were characterized, and their biocompatibility and osteoinductivity were determined in vitro and in vivo. The results showed that the CMC-DOPA-Sr composite facilitated strontium coating on the surface of ACBM scaffolds. The ACBM-Sr scaffolds possessed a sustained strontium ion release profile, exhibited good cytocompatibility, and enhanced the osteogenic differentiation of mesenchymal stem cells in vitro. Furthermore, the ACBM-Sr scaffolds showed good histocompatibility after subcutaneous implantation in nude mice. Taken together, this study provided a simple and mild strategy to realize strontium coating for ACBM scaffolds, which resulted in good biocompatibility and improved osteoinductivity. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Vitamin B12 deficiency

    DEFF Research Database (Denmark)

    Green, Ralph; Allen, Lindsay H; Bjørke-Monsen, Anne-Lise

    2017-01-01

    , subclinical deficiency affects between 2.5% and 26% of the general population depending on the definition used, although the clinical relevance is unclear. B12 deficiency can affect individuals at all ages, but most particularly elderly individuals. Infants, children, adolescents and women of reproductive age...... remain debated. Management depends on B12 supplementation, either via high-dose oral routes or via parenteral administration. This Primer describes the current knowledge surrounding B12 deficiency, and highlights improvements in diagnostic methods as well as shifting concepts about the prevalence, causes...

  16. Strontium zirconate as silicon and aluminum scavenger in yttria stabilized zirconia

    DEFF Research Database (Denmark)

    Andersen, Thomas; Hansen, Karin Vels; Chorkendorff, Ib

    2011-01-01

    Here we report on strontium zirconate as a getter for silicon dioxide and aluminum oxide in yttria stabilized zirconia (YSZ) single crystals for cleaning purposes. YSZ single crystals were covered with strontium zirconate powder and heat treated at 1450°C in water vapor. After treatment the YSZ...... by transmission electron microscopy (TEM) the interface region between bump and YSZ single crystal bulk was examined. EDS showed a homogeneous distribution of silicon and aluminum through the cross section of a bump. The results suggest strontium zirconate as a good getter for silicon and aluminum from bulk...

  17. Physicochemical Properties and Cellular Responses of Strontium-Doped Gypsum Biomaterials

    OpenAIRE

    Pouria, Amir; Bandegani, Hadis; Pourbaghi-Masouleh, Milad; Hesaraki, Saeed; Alizadeh, Masoud

    2012-01-01

    This paper describes some physical, structural, and biological properties of gypsum bioceramics doped with various amounts of strontium ions (0.19–2.23 wt%) and compares these properties with those of a pure gypsum as control. Strontium-doped gypsum (gypsum:Sr) was obtained by mixing calcium sulfate hemihydrate powder and solutions of strontium nitrate followed by washing the specimens with distilled water to remove residual salts. Gypsum was the only phase found in the composition of both pu...

  18. Regulation of strontium migration and translocation in chemical reclamation of acid soils

    International Nuclear Information System (INIS)

    Velichko, V.A.; Okonskij, A.I.; Shestakov, E.I.; Panov, N.P.

    1993-01-01

    Results of chemical testing are presented of the local reclamants (ashes of various deposits and ferrochromium plant slags) to study the possibilities of their use for chemical soil reclamation. Attention was paid to the investigation of pollutant (strontium) behaviour in the reclamant-acid soil-plant-ground water system. Tracer method was used, 85 Sr was applied as a label. Prospects of zeolite application to control the strontium behaviour following the reclamant introduction into soil were considered. It was shown that zeolite application permitted to regulate strontium behaviour in the reclamant-soil-plant-ground water system. At that the modified zeolites possessing high Sr selectivity are recommended for application

  19. Bactericidal strontium-releasing injectable bone cements based on bioactive glasses

    OpenAIRE

    Brauer, Delia S.; Karpukhina, Natalia; Kedia, Gopal; Bhat, Aditya; Law, Robert V.; Radecka, Izabela; Hill, Robert G.

    2013-01-01

    Strontium-releasing injectable bone cements may have the potential to prevent implant-related infections through the bactericidal action of strontium, while enhancing bone formation in patients suffering from osteoporosis. A melt-derived bioactive glass (BG) series (SiO2–CaO–CaF2–MgO) with 0–50% of calcium substituted with strontium on a molar base were produced. By mixing glass powder, poly(acrylic acid) and water, cements were obtained which can be delivered by injection and set in situ, gi...

  20. Review and evaluation of extractants for strontium removal using magnetically assisted chemical separation

    International Nuclear Information System (INIS)

    Bauer, C.B.; Rogers, R.D.

    1995-11-01

    A literature review on extractants for strontium removal was initially performed at Northern Illinois University to assess their potential in magnetically assisted chemical separation. A series of potential strontium extractants was systematically evaluated there using radioanalytical methods. Initial experiments were designed to test the uptake of strontium from nitric acid using several samples of magnetic extractant particles that were coated with various crown ether ligands. High partition coefficient (K d ) values for stimulant tank waste were obtained. Further studies demonstrated that the large partitioning was due to uncoated particles

  1. Isotope ratios of strontium and neodymium for characterizing earth mantle materials

    International Nuclear Information System (INIS)

    Brandt, S.B.; Lepin, V.S.; Maslovskaja, M.N.

    1985-01-01

    It is shown that the shares of mantle, crustal and sedimentary materials in rocks and ore deposits can be determined by isotope methods. Using Yakutian kimberlites as an example, mixing processes of mantle and crustal materials are illustrated with the aid of strontium isotopes. Due to the high sensitivity of strontium to hydrothermal effects, the combined use of neodymium and strontium isotopes is considered more appropriate to solve the problem of determining the share of mantle materials. This is demonstrated for rare earth minerals and alkaline rocks of Eastern Siberia and Mongolia. (author)

  2. Thermodynamic study on the adsorption of strontium on polyantimonic acid exchanger

    International Nuclear Information System (INIS)

    Li Mingyu; Chen Jing; Wang Jianchen; Zhao Jing

    2007-01-01

    The adsorption of strontium on the polyantimonic acid adsorbent was studied. The equilibrium data for the adsorption of strontium on polyantimonic acid exchanger from aqueous solutions were obtained and correlated with Langmuir-type and Freundlich-type isotherm equation within the temperature range of 293-323 K and the experimental concentration range. Freundlich adsorption isotherms and the isosteric enthalpy indicate that the adsorption of strontium on polyantimonic acid is an endothermic process from aqueous solutions. The enthalpy, free energy, and entropy of adsorption were calculated. The results indicate that the adsorption process is a complex interaction of physical and chemical processes. The adsorption behaviors were reasonably explained. (authors)

  3. Local structure and speciation of uranium in strontium orthosilicate: TRFS and EXAFS studies

    International Nuclear Information System (INIS)

    Gupta, Santosh K.; Thulasidas, S.K.; Natarajan, V.; Yadav, A.K.; Bhattacharya, D.

    2015-01-01

    TRFS is used to investigate the valence state and coordination behavior of uranium in strontium orthosilicate. From TRFS measurement it was observed that uranium exists as U(VI) in the form of UO 2 2+ in Sr 2 SiO 4 . Based on life time measurement and EXAFS studies it was inferred that uranyl is stabilized on both 9- and 10- coordinated strontium polyhedra. Majority of uranyl ion occupy relatively asymmetric site in strontium silicate most probably 9-coordinated Sr sites. (author)

  4. A distribution ratio model of strontium by crown ether extraction from simulated HLLW

    International Nuclear Information System (INIS)

    Chen Jing; Wang Qiuping; Wang Jianchen; Song Chongli

    1995-01-01

    An experiential distribution ratio model for strontium extraction by dicyclohexano-18-crown-6-n-octanol from simulated high-level waste is established. The experimental points for the model are designed by experimental homogeneous-design method. The regression of distribution ratio model of strontium is carried out by the complex-optimization method. The model is verified with experimental distribution ratio data in different extraction conditions. The results show that the relative deviations are within +-10% and the mean relative divination is 4.4% between the calculated data and the experimental ones. The experiential model together with an iteration program can be used for the strontium extraction process calculation

  5. Effects of mineralogy on sorption of strontium and cesium onto Calico Hills Tuff

    International Nuclear Information System (INIS)

    Meyer, R.E.; Arnold, W.D.; Case, F.I.; O'Kelley, G.D.; Land, J.F.

    1990-04-01

    The sorption properties of tuff formations at the proposed site for the high-level nuclear waste repository at Yucca Mountain, Nevada, have been extensively studied. Sorption and desorption measurements were made of strontium and cesium onto clinoptilolite and Calico Hills Tuff. The object was to see whether there was a correlation between sorption of strontium and cesium onto Calico Hills Tuff and the sorption of strontium and cesium onto clinoptilolite based on the content of clinoptilolite in the Calico Hills Tuff. 13 refs., 10 figs., 6 tabs

  6. Sorption and desorption of cesium and strontium on TA-2 and TA-41 soils and sediments

    International Nuclear Information System (INIS)

    Kung, K. Stephen; Li, Benjamin W.; Longmire, P.A.; Fowler, M.M.

    1996-04-01

    Current environmental monitoring has detected radioactive contaminants in alluvial groundwater, soils, and sediments in the TA-2 and TA-41 areas along the north central edge of Los Alamos National Laboratory. Because of this contamination, this study was initiated. The objective of this study is to quantify the sorptivity of cesium and strontium onto TA-2 and TA-41 site specific soil samples under a controlled environment in the laboratory. The purposes of this work are to determine cesium and strontium sorption coefficient for these sit specific soils and to evaluate the potential transport of cesium and strontium. Based on this information, a risk assessment and remediation strategy can be developed

  7. Review and evaluation of extractants for strontium removal using magnetically assisted chemical separation

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, C.B.; Rogers, R.D. [Northern Illinois Univ., De Kalb, IL (United States). Dept. of Chemistry; Nunez, L.; Ziemer, M.D.; Pleune, T.T.; Vandegrift, G.F. [Argonne National Lab., IL (United States)

    1995-11-01

    A literature review on extractants for strontium removal was initially performed at Northern Illinois University to assess their potential in magnetically assisted chemical separation. A series of potential strontium extractants was systematically evaluated there using radioanalytical methods. Initial experiments were designed to test the uptake of strontium from nitric acid using several samples of magnetic extractant particles that were coated with various crown ether ligands. High partition coefficient (K{sub d}) values for stimulant tank waste were obtained. Further studies demonstrated that the large partitioning was due to uncoated particles.

  8. Simplified method for the determination of strontium-90 in large amounts of bone-ash

    International Nuclear Information System (INIS)

    Patti, F.; Jeanmaire, L.

    1966-06-01

    The principle of the determination is based on a 3-step process: 1) concentrating the strontium by attacking the ash with nitric acid; 2) elimination of residual phosphoric ions by a double precipitation of strontium oxalate; and 3) extraction of yttrium 90, counted in the oxalate form. The advantages of the method: -) using simple techniques it makes it possible to process 50 g of ash; -) the initial concentration of strontium considerably reduces the volume of the solutions as well as the size of precipitates handled. Fuming nitric acid is used in a specially designed burette. (authors) [fr

  9. Solid solution barium–strontium chlorides with tunable ammonia desorption properties and superior storage capacity

    DEFF Research Database (Denmark)

    Bialy, Agata; Jensen, Peter Bjerre; Blanchard, Didier

    2015-01-01

    with spray drying and in situ thermogravimetric and structural characterization, we synthesize a range of new, stable barium-strontium chloride solid solutions with superior ammonia storage densities. By tuning the barium/strontium ratio, different crystallographic phases and compositions can be obtained...... with different ammonia ab- and desorption properties. In particular it is shown, that in the molar range of 35–50% barium and 65–50% strontium, stable materials can be produced with a practically usable ammonia density (both volumetric and gravimetric) that is higher than any of the pure metal halides...

  10. Iron-Deficiency Anemia

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