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Sample records for doped strontium fluoroapatite

  1. 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

  2. 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

  3. 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

  4. Biocompatible Er, Yb co-doped fluoroapatite upconversion nanoparticles for imaging applications

    Science.gov (United States)

    Anjana, R.; K. M., Kurias; M. K., Jayaraj

    2017-08-01

    Upconversion luminescence, visible emission on infra red (IR) excitation was achieved in a biocompatible material, fluoroapatite. Fluoroapatite crystals are well known biomaterials, which is a component of tooth enamel. Also it can be considered as an excellent host material for lanthanide doping since the ionic radii of lanthanide is similar to that of calcium ion(Ca2+) hence successful incorporation of dopants within the lattice is possible. Erbium (Er), Ytterbium (Yb) co-doped fluorapatite (FAp) nanoparticles were prepared by precipitation method. The particles show intense visible emission when excited with 980 nm laser. Since upconversion luminescence is a multiphoton process the excitation power dependence on emission will give number of photons involved in the emission of single photon. Excitation power dependence studies show that two photons are involved in the emission of single photons. The value of slope was different for different emission peak because of the difference in intermediate energy level involved. The crystal structure and morphology of the particle were determined using X-ray diffractometer (XRD) and field emission scanning electron microscope (FESEM). These particles with surface functionalisation can be used for live cell imaging.

  5. Microwave-assisted synthesis of biocompatible europium-doped calcium hydroxyapatite and fluoroapatite luminescent nanospindles functionalized with poly(acrylic acid).

    Science.gov (United States)

    Escudero, Alberto; Calvo, Mauricio E; Rivera-Fernández, Sara; de la Fuente, Jesús M; Ocaña, Manuel

    2013-02-12

    Europium-doped calcium hydroxyapatite and fluoroapatite nanophosphors functionalized with poly(acrylic acid) (PAA) have been synthesized through a one-pot microwave-assisted hydrothermal method from aqueous basic solutions containing calcium nitrate, sodium phosphate monobasic, and PAA, as well as sodium fluoride in the case of the fluoroapatite particles. In both cases a spindlelike morphology was obtained, resulting from an aggregation process of smaller subunits which also gave rise to high specific surface area. The size of the nanospindles was 191 (32) × 40 (5) nm for calcium hydroxyapatite and 152 (24) × 38 (6) nm for calcium fluoroapatite. The luminescent nanoparticles showed the typical red luminescence of Eu(3+), which was more efficient for the fluoroapatite particles than for the hydroxyapatite. This is attributed to the presence of OH(-) quenchers in the latter. The nanophosphors showed negligible toxicity for Vero cells. Both PAA-functionalized nanophosphors showed a very high (up to at least 1 week) colloidal stability in 2-(N-morpholino)ethanesulfonic acid (MES) at pH 6.5, which is a commonly used buffer for physiological pH. All these features make both kinds of apatite-based nanoparticles promising tools for biomedical applications, such as luminescent biolabels and tracking devices in drug delivery systems.

  6. 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.

  7. 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.

  8. Effect of temperature on polarization reversal of strontium-doped ...

    Indian Academy of Sciences (India)

    The effect of temperature on polarization reversal of strontium-doped lead zirconate titanate ceramics was studied. The piezoelectric properties viz. dielectric constant and piezoelectric coupling coefficient, were used for polarization reversal characteristic. These properties and apparent coercive field weremeasured during ...

  9. Strontium doped hydroxyapatite film formed by micro-arc oxidation

    International Nuclear Information System (INIS)

    Nan Kaihui; Wu Tao; Chen Jionghao; Jiang Shan; Huang Yong; Pei Guoxian

    2009-01-01

    A porous strontium-doped hydroxyapatite (Sr-HA) film was prepared on titanium substrates by an electrochemical oxidation method, i.e. micro-arc oxidation (MAO). The reaction was processed using a pulse power supply with titanium substrate acted as the anode in electrolytic solution containing calcium acetate, strontium acetate and β-glycerol phosphate disodium salt pentahydrate (β-GP). The thickness, phase, composition and morphology of the coatings were investigated with X-ray diffraction (XRD), electron probe microanalysis (EPMA) and scanning electron microscopy (SEM) with energy dispersive X-ray spectrometer (EDS). The thickness of the film was about 20 μm with the porous and uneven surfaces. XRD showed that the film was mainly made up of hydroxyapatite doped with strontium and the (Sr/(Sr + Ca) ratios ranged from 0-100%, which could be expressed as the general formula of Ca 10-X Sr X (PO 4 ) 6 (OH) 2 , 0 ≤ X ≤ 10). Such films are expected to have significant medical applications as dental implants and artificial bone joints.

  10. Niobium-doped strontium titanates as SOFC anodes

    DEFF Research Database (Denmark)

    Blennow Tullmar, Peter; Kammer Hansen, Kent; Wallenberg, L. Reine

    2008-01-01

    been synthesized with a recently developed modified glycine-nitrate process. The synthesized powders have been calcined and sintered in air or in 9% H(2) / N(2) between 800 - 1400 degrees C. After calcination the samples were single phase Nb-doped strontium titanate with grain sizes of less than 100 nm...... in diameter on average. The phase purity, defect structure, and microstructure of the materials have been analyzed with SEM, XRD, and TGA. The electrical conductivity of the Nb-doped titanate decreased with increasing temperature and showed a phonon scattering conduction mechanism with sigma > 120 S...... ability of the Nb-doped titanates to be used as a part of a SOFC anode. However, the catalytic activity of the materials was not sufficient and it needs to be improved if titanate based materials are to be realized as constituents in SOFC anodes....

  11. 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

  12. 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.

  13. Laser irradiation in Nd3+ doped strontium barium niobate glass

    International Nuclear Information System (INIS)

    Haro-Gonzalez, P.; Martin, I. R.; Arbelo-Jorge, E.; Gonzalez-Perez, S.; Caceres, J. M.; Nunez, P.

    2008-01-01

    A local nanocrystalline formation in a neodymium doped strontium barium niobate (SBN) glass has been obtained under argon laser irradiation. The intense emission around 880 nm, originated from the 4 F 3/2 ( 4 F 5/2 ) thermalized level when the glass structure changes to a glass ceramic structure due to the irradiation of the laser beam, has been studied. The intensities and lifetimes change from this level inside and outside the irradiated area made by the laser excitation. They have been analyzed and demonstrated that the desvitrification process has been successfully achieved. These results confirm that nanocrystals of SBN have been created by the laser action confirming that the transition from glass to glass ceramic has been completed. These results are in agreement with the emission properties of nanocrystals of the bulk glass ceramic sample. The present study also suggests that the SBN nanocrystal has a potential application as temperature detector

  14. 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...

  15. Strontium

    Science.gov (United States)

    Angulo, M.A.

    2010-01-01

    In 2009, U.S. apparent consumption of strontium (contained in celestite and manufactured strontium compounds) increased to 16 kt (17,600 st) from 10.6 kt (11,700 st) in 2008, an increase of 52 percent. This increase was attributed primarily to an increase in imported celestite. Gross weight of imports totaled 25.3 kt (27,900 st), of which 91 percent came from Mexico. Imports in 2009 were 18 percent more than in 2008. Exports of strontium compounds in 2009 decreased 15 percent to 9.3 kt (10,250 st) from 10.9 kt (12,000 st) in 2008. In 2009, the U.S. Customs value of imported strontium carbonate was 65 cents/kg (29 cents/lb); for strontium nitrate, the unit value was $ 1/kg (45 cents/lb). The unit value of imported celestite, all of which was from Mexico, was about $47/t ($43/st).

  16. Scandium doped Strontium Titanate Ceramics: Structure, Microstructure, and Dielectric Properties

    Directory of Open Access Journals (Sweden)

    Tkach, Alexander

    2008-08-01

    Full Text Available Sc-doped strontium titanate (ST ceramics were synthesised by solid state reaction, according to the composition Sr1-1.5xScxTiO3 with x = 0-0.01. Structural properties and microstructure development was examined by XRD and SEM. The dielectric properties were evaluated as a function of the temperature and frequency in the radio frequency range. Lattice parameter, density and grain size, were found to decrease slightly with increasing Sc content. The dielectric permittivity and losses decrease also. Sc-doping has only a weak effect on the quantum paraelectric behaviour of ST and no dielectric anomaly was observed, what is probably related to the limited solubility of Sc on the Sr site of the perovskite lattice of ST.

    Se sintetizaron materiales cerámicos de titanato de estroncio dopado con escandio mediante reacción en estado sólido De acuerdo a la composición Sr1-1.5xScxTiO3 con x= 0-0.1. Las propiedades estructurales y el desarrollo microestructural se estudiaron mediante XRD y SEM. La propiedades dieléctricas se estudiaron como función de la temperatura y de la frecuencia en el rango de la frecuencias de radio. Se observó que los parámetros de red, la densidad y el tamaño del grano disminuyen ligeramente con el contenido en Sc. La permitividad dieléctrica y las perdidas también disminuyen. El dopado con Sc tiene un efecto muy ligero sobre el comportamiento paraeléctrico cuántico del titanato de estroncio y no se observó anomalías dioeléctricas , lo que está probablemente relacionado con la baja solubilidad del Sc en posiciones del Sr en la estructura tipo perovskita del titanato de estroncio.

  17. Doping site dependent thermoelectric properties of epitaxial strontium titanate thin films

    KAUST Repository

    Abutaha, Anas I.

    2014-01-01

    We demonstrate that the thermoelectric properties of epitaxial strontium titanate (STO) thin films can be improved by additional B-site doping of A-site doped ABO3 type perovskite STO. The additional B-site doping of A-site doped STO results in increased electrical conductivity, but at the expense of Seebeck coefficient. However, doping on both sites of the STO lattice significantly reduces the lattice thermal conductivity of STO by adding more densely and strategically distributed phononic scattering centers that attack wider phonon spectra. The additional B-site doping limits the trade-off relationship between the electrical conductivity and total thermal conductivity of A-site doped STO, leading to an improvement in the room-temperature thermoelectric figure of merit, ZT. The 5% Pr3+ and 20% Nb5+ double-doped STO film exhibits the best ZT of 0.016 at room temperature. This journal is

  18. Thermoelectric power and electrical conductivity of strontium-doped lanthanum manganite

    DEFF Research Database (Denmark)

    Ahlgren, E.O.; Poulsen, F.W.

    1996-01-01

    Thermoelectric power and electrical conductivity of pure and 5, 10 and 20% strontium-doped lanthanum manganite are determined as function of temperature in air and of P-O2 at 1000 degrees C. At high temperatures the thermoelectric power is negative. Both thermoelectric power and conductivity...

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

    Indian Academy of Sciences (India)

    TECS

    logical revolution. The impact of single crystals is clearly visible in industries like semiconductor, optics, etc. With the invention of lasers, the field of non-linear optics touched new heights and practical implementation was possible with the application of non-linear optical crystals. Growth of single crystals of strontium tartrate ...

  20. Strontium-Doped Hematite as a Possible Humidity Sensing Material for Soil Water Content Determination

    OpenAIRE

    Tulliani, Jean-Marc; Baroni, Chiara; Zavattaro, Laura; Grignani, Carlo

    2013-01-01

    The aim of this work is to study the sensing behavior of Sr-doped hematite for soil water content measurement. The material was prepared by solid state reaction from commercial hematite and strontium carbonate heat treated at 900 °C. X-Ray diffraction, scanning electron microscopy and mercury intrusion porosimetry were used for microstructural characterization of the synthesized powder. Sensors were then prepared by uniaxially pressing and by screen-printing, on an alumina substrate, the prep...

  1. Allergen-loaded strontium-doped hydroxyapatite spheres improve allergen-specific immunotherapy in mice

    OpenAIRE

    Garbani, M; Xia, W; Rhyner, C; Prati, M; Scheynius, A; Malissen, B; Engqvist, H; Maurer, M; Crameri, R; Terhorst, D

    2017-01-01

    Background Immunomodulatory interventions play a key role in the treatment of infections and cancer as well as allergic diseases. Adjuvants such as micro- and nanoparticles are often added to immunomodulatory therapies to enhance the triggered immune response. Here, we report the immunological assessment of novel and economically manufactured microparticle adjuvants, namely strontium-doped hydroxyapatite porous spheres (SHAS), which we suggest for the use as adjuvant and carrier in allergen-s...

  2. Morphology, Composition, and Bioactivity of Strontium-Doped Brushite Coatings Deposited on Titanium Implants via Electrochemical Deposition

    Directory of Open Access Journals (Sweden)

    Yongqiang Liang

    2014-06-01

    Full Text Available Surface modification techniques have been applied to generate titanium implant surfaces that promote osseointegration for use in dental applications. In this study, strontium-doped brushite coatings were deposited on titanium by electrochemical deposition. The phase composition of the coating was investigated by energy dispersive X-ray spectroscopy and X-ray diffraction. The surface morphologies of the coatings were studied through scanning electron microscopy, and the cytocompatibility and bioactivity of the strontium-doped brushite coatings were evaluated using cultured osteoblasts. Osteoblast proliferation was enhanced by the addition of strontium, suggesting a possible mechanism by which strontium incorporation in brushite coatings increased bone formation surrounding the implants. Cell growth was also strongly influenced by the composition of the deposited coatings, with a 10% Sr-doped brushite coating inducing the greatest amount of bone formation among the tested materials.

  3. Sintering and electrical properties of strontium-doped lanthanum manganite

    Energy Technology Data Exchange (ETDEWEB)

    Tarrago, Diego Pereira; Sousa, Vania Caldas de [Universidade Federal do Rio Grande do Sul (LABIOMAT/PPGEM/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia de Minas, Metalurgica e de Materiais. Lab. de Biomateriais], Email: dptarrago@gmail.com; Moreno Buriel, Berta; Chinarro Martini, Eva; Jurado Egea, Jose Ramon [Consejo Superior de Investigaciones Cientificas (ICV/CSIC), Madrid (Spain). Inst. de Ceramica y Vidrio; Malfatti, Celia de Fraga [Universidade Federal do Rio Grande do Sul (LAPEC/PPGEM/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia de Minas, Metalurgica e de Materiais. Lab. de Pesquisa em Corrosao

    2010-07-01

    Lanthanum strontium manganites (LSM) are potential materials for cathode applications in solid oxide fuel cells (SOFC) due to their good catalytic activity, chemical stability and compatibility with electrolyte materials in high temperatures. The sinterability of single phase La{sub 1-x}Sr{sub x}Mn{sub O3} (x=0.18) perovskite powders and the electrical properties of the resulting samples are analyzed in this study. Using a heating microscope, the powders were pressed and sintered at different pressures and temperatures, resulting in an open porosity of 33.36% when compacted at 125 MPa and sintered at 1200 degree C. Top and cross-section s canning electron microscopy (SEM) micrographs revealed interconnected pores in the sintered body and, hence, a suitable microstructure for the application. The activation energy for conductance was 0.04 eV and the tested LSM bulk started to exhibit adequate electrical properties at about 500 degree C. (author)

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

    Indian Academy of Sciences (India)

    The crystal structure of the compound was confirmed by X-ray diffractometry and dopant concentration with ICP–atomic emission spectrometer system. Thermal decomposition of the grown crystals is investigated by TGA and DTA studies. The FTIR spectra of pure and doped crystals are recorded and analysed. Kurtz powder ...

  5. Photoluminescence of Pr3+-doped calcium and strontium stannates

    OpenAIRE

    Stanulis, Andrius; Katelnikovas, Arturas; Van Bael, Marlies K.; Hardy, An; Kareiva, Aivaras; Jüstel, Thomas

    2016-01-01

    A series of Pr3+-doped CaSnO3, SrSnO3 and Ca2SnO4 samples were prepared by a conventional high temperature solid-state reaction route. All samples were characterized by powder X-ray diffraction (XRD) analysis, photoluminescence (PL), photoluminescence thermal quenching (TQ) and fluorescence lifetime (FL) measurements. Moreover, luminous efficacies (LE) and color points according to the CIE 1931 color space diagram were calculated and discussed. The incorporation of Pr3+ ions into CaSnO3 an...

  6. Structural, topographical and electrical properties of cerium doped strontium barium niobate (Ce:SBN60) ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Raj, S. Gokul [Department of Physics, C. Kandaswami Naidu College For Men (CKNC), Annanagar, Chennai-600102 (India); Mathivanan, V.; Mohan, R. [Department of Physics, Presidency College, Chennai – 600005 (India); Kumar, G. Ramesh, E-mail: rameshvandhai@gmail.com; Yathavan, S. [Department of Physics, University College of Engineering Arni, Anna University Chennai, Arni-632317 (India)

    2016-05-06

    Tungsten bronze type cerium doped strontium barium niobate (Ce:SBN - Sr{sub 0.6}B{sub 0.4}Nb{sub 2}O{sub 6}) ceramics were synthesized by solid state process. Cerium was used as dopant to improve its electrical properties. Influence of Ce{sup +} ions on the photoluminescence properties was investigated in detail. The grain size topographical behavior of SBN powders and their associated abnormal grain growth (AGG) were completely analyzed through SEM studies. Finally dielectric, measurement discusses about the broad phase transition observed due to cerium dopant The results were discussed in detail.

  7. Optical properties of rare earth doped strontium aluminate (SAO) phosphors: A review

    Science.gov (United States)

    Kshatri, D. S.; Khare, A.

    2014-11-01

    After the first news on rare earth (RE) doped strontium aluminate (SAO) phosphors in late 1990s, researchers all over the world geared up to develop stable and efficient persistent phosphors. Scientists studied various features of long lasting phosphors (LLP) and tried to earmark appropriate mechanism. However, about two decades after the discovery of SrAl2O4: Eu2+, Dy3+, the number of persistent luminescent materials is not significant. In this review, we present an overview of the optical characteristics of RE doped SAO phosphors in terms of photoluminescence (PL), thermoluminescence (TL) and afterglow spectra. Also, we refresh the work undertaken to study diverse factors like dopant concentration, temperature, surface energy, role of activator, etc. Simultaneously, some of our important findings on SAO are reported and discussed in the end.

  8. Allergen-loaded strontium-doped hydroxyapatite spheres improve allergen-specific immunotherapy in mice.

    Science.gov (United States)

    Garbani, M; Xia, W; Rhyner, C; Prati, M; Scheynius, A; Malissen, B; Engqvist, H; Maurer, M; Crameri, R; Terhorst, D

    2017-04-01

    Immunomodulatory interventions play a key role in the treatment of infections and cancer as well as allergic diseases. Adjuvants such as micro- and nanoparticles are often added to immunomodulatory therapies to enhance the triggered immune response. Here, we report the immunological assessment of novel and economically manufactured microparticle adjuvants, namely strontium-doped hydroxyapatite porous spheres (SHAS), which we suggest for the use as adjuvant and carrier in allergen-specific immunotherapy (ASIT). Scanning electron microscopy revealed that the synthesis procedure developed for the production of SHAS results in a highly homogeneous population of spheres. Strontium-doped hydroxyapatite porous spheres bound and released proteins such as ovalbumin (OVA) or the major cat allergen Fel d 1. SHAS-OVA were taken up by human monocyte-derived dendritic cells (mdDCs) and murine DCs and did not have any necrotic or apoptotic effects even at high densities. In a murine model of ASIT for allergic asthmatic inflammation, we found that OVA released from subcutaneously injected SHAS-OVA led to a sustained stimulation of both CD4 + and CD8 + T cells. Allergen-specific immunotherapy with SHAS-OVA as compared to soluble OVA resulted in similar humoral responses but in a higher efficacy as assessed by symptom scoring. We conclude that SHAS may constitute a suitable carrier and adjuvant for ASIT with great potential due to its unique protein-binding properties. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  9. Enhancement of tetragonality and role of strontium vacancies in heterovalent doped SrTiO.sub.3./sub..

    Czech Academy of Sciences Publication Activity Database

    Tkach, A.; Almeida, A.; Moreira, J.A.; Correia, T.M.; Chaves, M. R.; Okhay, O.; Vilarinho, P. M.; Gregora, Ivan; Petzelt, Jan

    2011-01-01

    Roč. 98, č. 5 (2011), "052903-1"-"052903-2" ISSN 0003-6951 R&D Projects: GA AV ČR KAN301370701 Institutional research plan: CEZ:AV0Z10100520 Keywords : strontium titanate * doping * phase transition * Raman spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.844, year: 2011

  10. Sensitization of Perovskite Strontium Stannate SrSnO3 towards Visible-Light Absorption by Doping

    Directory of Open Access Journals (Sweden)

    Hungru Chen

    2014-01-01

    Full Text Available Perovskite strontium stannate SrSnO3 is a promising photocatalyst. However, its band gap is too large for efficient solar energy conversion. In order to sensitize SrSnO3 toward visible-light activities, the effects of doping with various selected cations and anions are investigated by using hybrid density functional calculations. Results show that doping can result in dopant level to conduction band transitions which lie lower in energy compared to the original band gap transition. Therefore, it is expected that doping SrSnO3 can induce visible-light absorption.

  11. Studies on luminescence from a cerium-doped strontium stannate phosphor.

    Science.gov (United States)

    Karabulut, Yüksel; Ayvacikli, Mehmet; Canimoglu, Adil; Garcia Guinea, Javier; Can, Nurdogan

    2015-06-01

    The crystal structure and morphology of Ce(3+) -doped SrSnO3 materials prepared using the solid-state reaction method were extensively characterized using experimental techniques. X-Ray diffraction results show that the cerium substitution of strontium does not change the structure of the strontium stannate. Raman spectroscopy was used to investigate the microstructures and lattice vibrations. Environmental scanning electron microscopy images showed that phosphors aggregate and their particles form irregular shapes. SrSnO3 exhibits an intense green emission with a broad band originating from the 5d(1)  → 4f(1) transition of cerium. It was observed that, after exposure to beta-irradiation, the glow curve of this material has two broad thermoluminescence peaks, one centered at ~ 127°C and the other at ~ 245°C for a heating rate of 5 K/s. The kinetic parameters, which include the frequency factor and the activation energy of the material, were calculated using Chen's method, after beta-irradiation. The fading and reusability of the phosphor were also studied and it was found that the phosphor is suitable for radiation dosimetry. Copyright © 2014 John Wiley & Sons, Ltd.

  12. Strontium-Doped Hematite as a Possible Humidity Sensing Material for Soil Water Content Determination

    Directory of Open Access Journals (Sweden)

    Carlo Grignani

    2013-09-01

    Full Text Available The aim of this work is to study the sensing behavior of Sr-doped hematite for soil water content measurement. The material was prepared by solid state reaction from commercial hematite and strontium carbonate heat treated at 900 °C. X-Ray diffraction, scanning electron microscopy and mercury intrusion porosimetry were used for microstructural characterization of the synthesized powder. Sensors were then prepared by uniaxially pressing and by screen-printing, on an alumina substrate, the prepared powder and subsequent firing in the 800–1,000 °C range. These sensors were first tested in a laboratory apparatus under humid air and then in an homogenized soil and finally in field. The results evidenced that the screen printed film was able to give a response for a soil matric potential from about 570 kPa, that is to say well below the wilting point in the used soil.

  13. Strontium-doped hematite as a possible humidity sensing material for soil water content determination.

    Science.gov (United States)

    Tulliani, Jean-Marc; Baroni, Chiara; Zavattaro, Laura; Grignani, Carlo

    2013-09-10

    The aim of this work is to study the sensing behavior of Sr-doped hematite for soil water content measurement. The material was prepared by solid state reaction from commercial hematite and strontium carbonate heat treated at 900 °C. X-Ray diffraction, scanning electron microscopy and mercury intrusion porosimetry were used for microstructural characterization of the synthesized powder. Sensors were then prepared by uniaxially pressing and by screen-printing, on an alumina substrate, the prepared powder and subsequent firing in the 800-1,000 °C range. These sensors were first tested in a laboratory apparatus under humid air and then in an homogenized soil and finally in field. The results evidenced that the screen printed film was able to give a response for a soil matric potential from about 570 kPa, that is to say well below the wilting point in the used soil.

  14. Optical properties of Er3+-doped strontium barium niobate nanocrystals obtained by thermal treatment in glass

    International Nuclear Information System (INIS)

    Haro-Gonzalez, P.; Lahoz, F.; Gonzalez-Platas, J.; Caceres, J.M.; Gonzalez-Perez, S.; Marrero-Lopez, D.; Capuj, N.; Martin, I.R.

    2008-01-01

    Measurements of the optical properties of Er 3+ ions in strontium barium niobate glass and glass ceramics have been carried out. The glasses have been fabricated using a melt-quenching method, and the glass ceramic samples have been obtained from the glass precursor by a thermal treatment. The ceramic samples formed by a glassy phase, and a crystalline phase contains nanocrystals of Sr 1-x Ba x Nb 2 O 6 (SBN) doped with Er 3+ ions with a mean size of ∼50 nm, as confirmed with XRD. Green up-conversion emission has been obtained under excitation at 800 nm, and the temporal evolution of this emission has been reported with the purpose of determining the involved up-conversion mechanism. These optical measures have confirmed that the Er 3+ ions have been incorporated into the SBN matrix, after a thermal treatment, which produced an increment of the up-conversion efficiency

  15. Impedance spectroscopy and dielectric studies of nanocrystalline iron doped barium strontium titanate ceramics

    Directory of Open Access Journals (Sweden)

    Reenu Jacob

    2015-06-01

    Full Text Available Barium titanate compounds have great research attention due to their good electric and in some case interesting magnetic properties. The synthesis and characterization of iron doped barium strontium titanate (BSFTO make an attempt to understand its structure and investigate electric/dielectric properties. The formation of a perovskite compound with tetragonal phase was confirmed through X-ray structural studies. Dielectric and electrical impedance properties of the sintered BSFTO ceramics were measured in the frequency range from 42 Hz to 2 MHz and at different temperatures (up to 600 °C. It was shown that the properties of this material are highly dependent on temperature and frequency. The nature of frequency dependence of AC conductivity confirms the Jonscher’s power law. The temperature dependence of DC conductivity obeys the Arrhenius behaviour.

  16. Synthesis and characterization of strontium molybdate doped with copper, cobalt and zinc for purposes photocatalytic

    International Nuclear Information System (INIS)

    Dutra, F.B.; Silva, M.M.S.; Moriyama, A.L.L.; Souza, C.P.

    2016-01-01

    The broad concerns of contemporary society with environmental problems requires legislation and more effective techniques for wastewater treatment. In recent years, ceramic materials that have properties such as high melting points and high stability have been receiving great emphasis in several studies in particular heterogeneous photocatalysis, rapid and efficient method for the complete mineralization of contaminants. In this context, the present work deals with the synthesis and characterization of molybdate Strontium (SrMoO4) doped with copper, cobalt and zinc for the purpose of photocatalytic studies. The compounds were synthesized by complexation method EDTA / Citrate basic medium. The powders were characterized by Thermogravimetric Analysis (TG), X-Ray Diffraction (XRD), Particle size distribution by laser diffraction, Spectroscopy in the UV-Visible region, Energy Dispersive Spectroscopy (EDS) and Scanning Electron Microscopy (SEM), showing promising results as the crystalline phase of development and potential uses for the purpose of heterogeneous photocatalysis. (author)

  17. Silica-coated gadolinium-doped lanthanum strontium manganite nanoparticles for self-controlled hyperthermia applications

    Science.gov (United States)

    Ahmad, Ashfaq; Bae, Hongsub; Rhee, Ilsu

    2018-01-01

    Gadolinium-doped lanthanum strontium manganite (LSM) nanoparticles were synthesized by using a citrate-gel technique. The particles were then annealed at 850 oC to remove defects for a good crystallinity, followed by coating with silica for possible biomedical application to magnetic hyperthermia. The chemical composition was determined to be La0.54Sr0.27Gd0.19MnO3 using an inductively coupled plasma mass spectrometer. The nanoparticles were characterized by X-ray diffraction, transmission electron microscope, and Fourier transform infrared spectrometer to check the perovskite crystalline structure and to observe the particles size and coating status of silica on the surface of the particles. The Curie temperature of the particles was found to be about 280 K. The saturation temperature of the aqueous solution of the particles remained at the hyperthermia target temperature of 42 oC with increasing concentration of particles from 6 to 60 mg/mL in the dispersion. This saturation temperature for a highly concentrated 120-mg/mL-sample increased further, but less than the dangerous temperature of 47 oC for normal tissues. The saturation temperature of the powder sample reached only up to 53 oC. These results showed that the gadolinium-doped LSM nanoparticles can be used for the self-controlled hyperthermia in which the temperature does not exceed the target temperature of hyperthermia even at the tissue site of highly accumulated nanoparticles.

  18. Multicomponent doped barium strontium titanate thin films for tunable microwave applications

    Science.gov (United States)

    Alema, Fikadu Legesse

    In recent years there has been enormous progress in the development of barium strontium titanate (BST) films for tunable microwave applications. However, the properties of BST films still remain inferior compared to bulk materials, limiting their use for microwave technology. Understanding the film/substrate mismatch, microstructure, and stoichiometry of BST films and finding the necessary remedies are vital. In this work, BST films were deposited via radio frequency magnetron sputtering method and characterized both analytically and electrically with the aim of optimizing their properties. The stoichiometry, crystal structure, and phase purity of the films were studied by varying the oxygen partial pressure (OPP) and total gas pressure (TGP) in the chamber. A better stoichiometric match between film and target was achieved when the TGP is high (> 30 mTorr). However, the O2/Ar ratio should be adjusted as exceeding a threshold of 2 mTorr in OPP facilitates the formation of secondary phases. The growth of crystalline film on platinized substrates was achieved only with a lower temperature grown buffer layer, which acts as a seed layer by crystallizing when the temperature increases. Concurrent Mg/Nb doping has significantly improved the properties of BST thin films. The doped film has shown an average tunability of 53%, which is only ˜8 % lower than the value for the undoped film. This drop is associated with the Mg ions whose detrimental effects are partially compensated by Nb ions. Conversely, the doping has reduced the dielectric loss by ˜40 % leading to a higher figure of merit. Moreover, the two dopants ensure a charge neutrality condition which resulted in significant leakage current reduction. The presence of large amounts of empty shallow traps related to Nb Ti localize the free carriers injected from the contacts; thus increase the device control voltage substantially (>10 V). A combinatorial thin film synthesis method based on co-sputtering of two BST

  19. Influence of organic solvent treatment on elasticoluminescent property of europium-doped strontium aluminates

    International Nuclear Information System (INIS)

    Fujio, Yuki; Xu, Chao-Nan; Terasaki, Nao; Ueno, Naohiro

    2014-01-01

    The influence of an organic solvent treatment on elasticoluminescent (ELS) characteristics of mechanoluminescent (ML) sensor using the composite film consisting of an ELS material and epoxy resin was investigated. We used strontium aluminate doped with a small amount of europium (SrAl 2 O 4 :Eu, SAOE) as an ELS material in this study. After evaluating the ELS characteristics of the fabricated ML sensors using SAOE treated with/without various organic solvents, SAOE treated with methanol and ethanol showed lower ELS intensities than that of untreated SAOE. In contrast, the ELS response curves against strain for the ML sensors using SAOE treated with acetone and toluene, overlapped with that of untreated SAOE. From the characterization of SAOE treated with alcohols, such as methanol and ethanol, we can hypothesize that poor ELS characteristics is due to the degradation of the SAOE grain surfaces by the hydrolyze reaction of SAOE with hydroxyl group of alcohol. Thus, on the basis of the obtained results, we can conclude that the selection of organic solvent used in the preparation of SAOE film is of considerable importance in the development of ML sensor with a highly-reliable ELS characteristic. -- Highlights: • Influence of organic solution treatment on the sensing characteristics of a mechanoluminescent (ML) sensor using SrAl 2 O 4 :Eu has been investigated. • An alcohol treatment of SAOE powder has considerable effect on its ML characteristic. • There is almost no influence of acetone and toluene treatments on ML characteristics

  20. Ho3+-doped strontium-aluminium-bismuth-borate glasses for green light emission.

    Science.gov (United States)

    Rajesh, D; Dhamodhara Naidu, M; Ratnakaram, Y C; Balakrishna, A

    2014-11-01

    Strontium-aluminium-bismuth-borate glasses (SAlBiB) doped with different concentrations of Ho(3+) were prepared using conventional melt quenching technique and their structural and optical properties investigated. X-ray diffraction and scanning electron microscopy analysis were used to study the structural properties. Optical properties were studied by measuring the optical absorption and visible luminescence spectra. The Judd-Ofelt (J-O) theory was applied to evaluate J-O intensity parameters, Ω(λ) (λ = 2, 4 and 6). Using J-O intensity parameters, radiative properties such as spontaneous transition probabilities (A(R)), branching ratios (β(R)) and radiative lifetimes (τ(R)) were determined. From the emission spectra, a strong green emission nearly at 549 nm corresponding to the transition, (5)S2 ((5)F4)→(5)I(8) was observed. Emission peak positions (λ(P)), effective bandwidths (Δλ(eff)) and stimulated emission cross-sections (σ(p)) were calculated for the observed emission transitions, (5)F3 →(5)I(8), (5)S2((5)F4)→(5)I(8) and (5)F5 →(5)I(8) of Ho(3+) in all the glass matrices. Chromaticity color coordinates were calculated using the emission spectra. The experimental results suggest that SAlBiB glass matrix with 1.5 mol% of Ho(3+) has better emission properties. Copyright © 2014 John Wiley & Sons, Ltd.

  1. Gelcasting of strontium doped lanthanum manganite for solid oxide fuel cell applications

    International Nuclear Information System (INIS)

    Abdul Haleem, B.; Bhuvana, R.; Udayakumar, A.

    2009-01-01

    Solid oxide fuel cells (SOFCs) are devices that offer high efficiency power output with negligible emissions. Cathode supported tubular SOFCs consist of porous cathode tubes made up of strontium doped lanthanum manganite, La 1-x Sr x MnO 3 (LSM) that work as functional component as well as structural support for the rest of the cell components. Gelcasting is one of the most suitable methods for the fabrication of porous ceramics. This paper describes the fabrication of porous LSM cathode by gelcasting process. Gelcasting parameters such as monomer concentration, powder volume fraction, pH of the slurry, etc were optimized. Slow drying of green specimens minimized warpage and cracking. Sintered specimens with controlled porosity were obtained by the use of suitable pore-forming agents. The coefficient of thermal expansion (CTE) of sintered specimens was measured, which was found matching with the CTE values of cell components reported in the literature. These results have shown the suitability of the gelcast generated LSM cathodes for SOFC applications. (author)

  2. Luminescence studies on the europium doped strontium metasilicate phosphor prepared by solid state reaction method

    Directory of Open Access Journals (Sweden)

    Ishwar Prasad Sahu

    2017-03-01

    Full Text Available Europium doped strontium meta-silicate (namely SrSiO3:Eu3+ phosphor was prepared by a high temperature solid state reaction method. The sintered SrSiO3:Eu3+ phosphor possesses a monoclinic structure by the XRD. Energy dispersive X-ray spectrum (EDS confirms the presence of elements in the desired sample. Thermoluminescence (TL kinetic parameters such as activation energy (E, order of kinetics (b, and frequency factor (s were calculated by the peak shape method. The orange–red emission was shown to originate from the 5D0–7FJ (J = 0, 1, 2, 3, 4 transitions of Eu3+ ions as the sample was excited at 396 nm. The SrSiO3:Eu3+ phosphor with almost pure orange-red color purity (99.62% shows the quantum efficiency of 10.2% (excited by 396 nm, which is higher than those of commercial red phosphors Y2O3:Eu3+ and Y2O2S:Eu3+ with quantum efficiencies of 9.6% (excited by 394 nm and 4.2% (excited by 395 nm, respectively. Mechanoluminescence (ML intensity of the SrSiO3:Eu3+ phosphor was also found to increase linearly with increasing the impact velocity of the moving piston, suggesting that the discussed phosphor can be used as a stress sensor.

  3. Bioactivity and corrosion properties of gelatin-containing and strontium-doped calcium phosphate composite coating

    Science.gov (United States)

    Huang, Yong; Yan, Yajing; Pang, Xiaofeng; Ding, Qiongqiong; Han, Shuguang

    2013-10-01

    To improve coating corrosion resistance and bioactivity, strontium (Sr) and gelatin (GLT) were simultaneously incorporated in calcium phosphate (Ca-P) to form Sr-Ca-P/GLT composite coating on titanium (Ti) by electrodeposition. The surface morphology, chemical composition, phase identification, bond strength, corrosion resistance, and cytocompatibility of the films were studied. Results revealed that the Sr-Ca-P/GLT layer was rough and inhomogeneous, with floral-like crystals or flake agglomerate morphology. The Sr-Ca-P crystals were Sr-doped apatite (hydroxyapatite and brushite), and Sr2+ ions and GLT were homogeneously distributed in the Ca-P coating. The thickness of the composite coating was almost 10 μm without delamination and/or cracking at the interface. The bond strength of the composite coating was 5.6 ± 1.8 MPa. The Sr-Ca-P/GLT coated Ti had lower corrosion rates than bare Ti, suggesting a protective character of the composite coating. Osteoblast cellular tests demonstrated that the Sr-Ca-P/GLT composite coating better enhanced the in vitro biocompatibility of Ti than Ca-P coating.

  4. 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.

  5. Influence of single and binary doping of strontium and lithium on in vivo biological properties of bioactive glass scaffolds

    Science.gov (United States)

    Khan, Pintu Kumar; Mahato, Arnab; Kundu, Biswanath; Nandi, Samit K.; Mukherjee, Prasenjit; Datta, Someswar; Sarkar, Soumya; Mukherjee, Jayanta; Nath, Shalini; Balla, Vamsi K.; Mandal, Chitra

    2016-01-01

    Effects of strontium and lithium ion doping on the biological properties of bioactive glass (BAG) porous scaffolds have been checked in vitro and in vivo. BAG scaffolds were prepared by conventional glass melting route and subsequently, scaffolds were produced by evaporation of fugitive pore formers. After thorough physico-chemical and in vitro cell characterization, scaffolds were used for pre-clinical study. Soft and hard tissue formation in a rabbit femoral defect model after 2 and 4 months, were assessed using different tools. Histological observations showed excellent osseous tissue formation in Sr and Li + Sr scaffolds and moderate bone regeneration in Li scaffolds. Fluorochrome labeling studies showed wide regions of new bone formation in Sr and Li + Sr doped samples as compared to Li doped samples. SEM revealed abundant collagenous network and minimal or no interfacial gap between bone and implant in Sr and Li + Sr doped samples compared to Li doped samples. Micro CT of Li + Sr samples showed highest degree of peripheral cancellous tissue formation on periphery and cortical tissues inside implanted samples and vascularity among four compositions. Our findings suggest that addition of Sr and/or Li alters physico-chemical properties of BAG and promotes early stage in vivo osseointegration and bone remodeling that may offer new insight in bone tissue engineering. PMID:27604654

  6. SYNTHESIS OF DENTAL FLUOROAPATITE GLASS-CERAMIC GLAZES

    Directory of Open Access Journals (Sweden)

    G. Aabolfathi

    2011-12-01

    Full Text Available A dental glass-ceramic glaze based on the SiO2–Li2O3–P2O5–CaO system, which is currently used as dentin for lithiumdisilicate glass-ceramic cores, was synthesized. The role of Na2O, CaO and P2O5 in sintering and crystallization of the related glasses were studied by firing at temperatures higher than their dilatometric softening point. Sintering of glasses led to precipitation of needle - like fluoroapatite crystalline particles. However, in spite of current definition about glassceramics, the final synthesized composition and a similar trade mark sample, which was used as reference, did not show considerable amounts of crystalline phases after sintering process. Furthermore, reducing the constituent‘s of fluoroapatite in glass composition led to reduction of sinterability and fusibility of the system.

  7. Local environments and transport properties of heavily doped strontium barium niobates Sr0.5Ba0.5Nb2O6

    Science.gov (United States)

    Ottini, Riccardo; Tealdi, Cristina; Tomasi, Corrado; Tredici, Ilenia G.; Soffientini, Alessandro; Burriel, Ramón; Palacios, Elías; Castro, Miguel; Anselmi-Tamburini, Umberto; Ghigna, Paolo; Spinolo, Giorgio

    2018-02-01

    Undoped as well as K-doped (40%), Y-doped (40%), Zr-doped (10%), and Mo-doped (12.5%) strontium barium niobate Sr0.5Ba0.5Nb2O6 (SBN50) materials have been investigated to explore the effect of heavy doping on the structural and functional properties (thermo-power, thermal and electrical conductivities) both in the as prepared (oxidized) and reduced states. For all materials, the EXAFS spectra at the Nb - K edge can be consistently analyzed with the same model of six shells around the Nb sites. Doping mostly gives a simple size effect on the structural parameters, but doping on the Nb sites weakens the Nb-O bond regardless of dopant size and charge. Shell sizes and Debye-Waller factors are almost unaffected by temperature and oxidation state, and the disorder is of static nature. The functional effects of heavy doping do not agree with a simple model of hole or electron injection by aliovalent substitutions on a large band gap semiconductor. With respect to the undoped samples, doping with Mo depresses the thermal conductivity by 30%, Y doping enhances the electrical conductivity by an order of magnitude, while Zr doping increases the Seebeck coefficient by a factor of 2-3. Globally, the ZT efficiency factor of the K-, Y-, and Zr-doped samples is enhanced at least by one order of magnitude with respect to the undoped or Mo-doped materials.

  8. Application of fluorine-19 CRAMPS to the analysis of calcium fluoride/fluoroapatite mixtures

    Science.gov (United States)

    Smith, Karen Ann; Burum, Douglas P.

    This paper presents fluorine-19 CRAMPS (combined rotation and multiple-pulse spectroscopy) of mixtures of calcium fluoride and fluoroapatite and demonstrates that fluorine-19 CRAMPS can be used to quantitate the relative amounts in physical mixtures of calcium fluoride and fluoroapatite. The observed results agree with calculated values to within 10%. CRAMPS, which is the combination of MASS (to remove chemical-shift anisotropy) and multiple-pulse (to remove dipole-dipole interactions), allows resolution of the isotropic peaks from calcium fluoride and fluoroapatite. Quadrature detection is used in the MREV-8 sequence to cover the large range of chemical shifts present. A linewidth difference is observed between the calcium fluoride and the fluoroapatite. This difference is shown not to be due to magnetic centers, other crystal defects, bulk susceptibility differences, T2 effects, chemical-shift dispersion, or the presence of residual protons in the fluoroapatite. The ultimate cause of the linewidth difference has not been determined.

  9. Novel bone substitute composed of chitosan and strontium-doped α-calcium sulfate hemihydrate: Fabrication, characterisation and evaluation of biocompatibility

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yirong; Zhou, Yilin [Department of Orthopaedics and Traumatology, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China); Yang, Shenyu [Department of Materials Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Li, Jiao Jiao [Biomaterials and Tissue Engineering Research Unit, School of AMME, University of Sydney, Sydney, NSW 2006 (Australia); Li, Xue; Ma, Yunfei; Hou, Yilong; Jiang, Nan; Xu, Changpeng; Zhang, Sheng [Department of Orthopaedics and Traumatology, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China); Zeng, Rong [Department of Materials Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Tu, Mei, E-mail: tumei@jnu.edu.cn [Department of Materials Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Yu, Bin, E-mail: yubinol@163.com [Department of Orthopaedics and Traumatology, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China)

    2016-09-01

    Calcium sulfate is in routine clinical use as a bone substitute, offering the benefits of biodegradability, biocompatibility and a long history of use in bone repair. The osteoconductive properties of calcium sulfate may be further improved by doping with strontium ions. Nevertheless, the high degradation rate of calcium sulfate may impede bone healing as substantial material degradation may occur before the healing process is complete. The purpose of this study is to develop a novel composite bone substitute composed of chitosan and strontium-doped α-calcium sulfate hemihydrate in the form of microcapsules, which can promote osteogenesis while matching the natural rate of bone healing. The developed microcapsules exhibited controlled degradation that facilitated the sustained release of strontium ions. In vitro testing showed that the microcapsules had minimal cytotoxicity and ability to inhibit bacterial growth. In vivo testing in a mouse model showed the absence of genetic toxicity and low inflammatory potential of the microcapsules. The novel microcapsules developed in this study demonstrated suitable degradation characteristics for bone repair as well as favourable in vitro and in vivo behaviour, and hold promise for use as an alternative bone substitute in orthopaedic surgery. - Highlights: • Chitosan + Sr-doped α-calcium sulfate hemihydrate microcapsules were synthesised. • The novel composite microcapsules had potential application as a bone substitute. • The microcapsules showed controlled degradation and release of strontium ions. • The microcapsules showed in vitro biocompatibility by cytotoxicity test. • The microcapsules showed in vivo biocompatibility in a mouse model.

  10. Spectroscopic investigations on Pr³+ and Nd³+ doped strontium-lithium-bismuth borate glasses.

    Science.gov (United States)

    Rajesh, D; Balakrishna, A; Seshadri, M; Ratnakaram, Y C

    2012-11-01

    Spectroscopic investigations on different concentrations (0.1, 0.5, 1.0, 1.5 and 2.0mol%) of Pr(3+) and Nd(3+) doped strontium lithium bismuth borate glasses have been done. X-ray diffraction, SEM with EDS, absorption and luminescence spectra were recorded for all the glass matrices and analyzed. X-ray diffraction profiles and SEM images conformed amorphous nature of investigated glass samples. EDS spectra of host glass and Pr(3+)doped glass matrices gave information about the chemical composition of glass samples. From the absorption spectra of Pr(3+) and Nd(3+) ions, Judd-Ofelt (J-O) intensity parameters (Ω(λ),λ=2, 4 and 6) have been calculated and compared with other glass matrices. The emission characteristics such as radiative lifetimes (τ(R)), measured and calculated branching ratios (β) and stimulated emission cross-sections (σ(P)) have been obtained for the observed emission transitions of Pr(3+) and Nd(3+) ions in the above glass matrix for all the concentrations. From the emission spectra of Pr(3+) and Nd(3+) doped glass matrices, the effect of concentration on the quenching of intensity of (1)D(2)→(3)H(4) transition of Pr(3+) ion and (4)F(3/2)→(4)I(9/2), (4)I(11/2) and (4)I(13/2) transitions of Nd(3+) have been studied and discussed. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. The effect of strontium and barium doping on perovskite-structured energy materials for photovoltaic applications

    Science.gov (United States)

    Wu, Ming-Chung; Chen, Wei-Cheng; Chan, Shun-Hsiang; Su, Wei-Fang

    2018-01-01

    Perovskite solar cell is a novel photovoltaic technology with the superior progress in efficiency and the simple solution processes. Develop lead-free or lead-reduced perovskite materials is a significant concern for high-performance perovskite solar cell. Among the alkaline earth metals, the Sr2+ and Ba2+ are suitable for Pb2+ replacement in perovskite film due to fitting Goldschmidt's tolerance factor. In this study, we adopted Ba-doped and Sr-doped perovskite structured materials with different doping levels, including 1.0, 5.0, and 10.0 mol%, to prepare perovskite solar cells. Both Ba-doped and Sr-doped perovskite structured materials have a related tendency in absorption behavior and surface morphology. At 10.0 mol% doping level, the power conversion efficiency (PCE) of Sr-doped perovskite solar cells is only ∼0.5%, but the PCE of Ba-doped perovskite solar cells can be achieved to ∼9.7%. Ba-doped perovskite solar cells showed the acceptable photovoltaic characteristics than Sr-doped perovskite solar cells. Ba dopant can partially replace the amount of lead in the perovskite solar cells, and it could be a potential candidate in the field of lead-free or lead-reduced perovskite energy materials.

  12. Thermoluminescence (TL dosimeter of dysprosium doped strontium borate glass for different glass modifiers (Na, Li, Ca subjected from 1 to 9 Gy doses

    Directory of Open Access Journals (Sweden)

    Hamzah S. A.

    2017-01-01

    Full Text Available This article reports TL response for different glass modifier and doping concentration. Alkali oxides (Na2O and Li2O and alkali earth oxide (CaO will be used as a glass modifier for strontium borate based glass. The samples were prepared by melt quenching technique. Dy2O3 concentrations ranging from 0.00 to 0.70 mol% and exposure doses of 1 to 9 Gy will be varied. All glass samples exhibit the prominent peak temperature positioned at 186 oC to 232 oC. From all the samples, one of the samples shows an excellent linearity dose response, higher TL and show good reproducibility after 5 cycles exposure which is sodium strontium borate doped with 0.1 mol% Dy2O3 (optimum concentration.

  13. Thermoluminescence (TL) dosimeter of dysprosium doped strontium borate glass for different glass modifiers (Na, Li, Ca) subjected from 1 to 9 Gy doses

    Science.gov (United States)

    Hamzah, S. A.; Saeed, M. A.; Wagiran, H.; Hashim, I. H.

    2017-10-01

    This article reports TL response for different glass modifier and doping concentration. Alkali oxides (Na2O and Li2O) and alkali earth oxide (CaO) will be used as a glass modifier for strontium borate based glass. The samples were prepared by melt quenching technique. Dy2O3 concentrations ranging from 0.00 to 0.70 mol% and exposure doses of 1 to 9 Gy will be varied. All glass samples exhibit the prominent peak temperature positioned at 186 oC to 232 oC. From all the samples, one of the samples shows an excellent linearity dose response, higher TL and show good reproducibility after 5 cycles exposure which is sodium strontium borate doped with 0.1 mol% Dy2O3 (optimum concentration).

  14. Fabrication and Properties of Silica Gel/Calcium Sulfate/Strontium-doped β-tricalcium Phosphate Composite Porous Scaffolds for Bone Tissue Engineering

    Directory of Open Access Journals (Sweden)

    QIN Xiao-su

    2018-03-01

    Full Text Available The calcium sulfate/strontium-doped β-tricalcium phosphate composite spherical pellets was fabricated, using the calcium sulfate/strontium-doped β-TCP as raw material, and through the stirring spray drying method, and then composite spherical pellets were combined with silica gel, porous silica gel/calcium sulfate/strontium-doped β-tricalcium phosphate scaffold was obtained by stacking aggregation method in the mould. The XRD, SEM and FT-IR, etc are employed to examine the chemical composition, composite morphology and structure characteristics, and the degradability, porosity, mechanical properties and cytotoxicity of the scaffolds materials were studied. The results reveal that the composite porous scaffolds have irregular pore structure with pore size between 0.2-1.0mm, and they have a large number of micropores on each of the composite spherical pellets, with the aperture between 50-200μm. Moreover, the porosity of the composite scaffolds is about 62%, which can meet the requirements of scaffolds for bone tissue engineering in porosity; the cytotoxicity tests show the composite scaffolds have no cytotoxic effect and it has good degradation. Therefore, it has good application prospect in bone tissue engineering of the bone defect repair of non-bearing site.

  15. Lanthanum-doped mesostructured strontium titanates synthesized via sol–gel combustion route using citric acid as complexing agent

    Energy Technology Data Exchange (ETDEWEB)

    Sukpanish, Polthep [Department of Chemical Technology, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Center of Excellence on Petrochemical and Materials Technology (PETROMAT), Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Lertpanyapornchai, Boontawee [Program in Petrochemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Yokoi, Toshiyuki [Division of Catalytic Chemistry, Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Ngamcharussrivichai, Chawalit, E-mail: Chawalit.Ng@chula.ac.th [Department of Chemical Technology, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Center of Excellence on Petrochemical and Materials Technology (PETROMAT), Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand)

    2016-09-15

    In the present work, a series of lanthanum-doped mesostructured strontium titanate (LMST) materials with different La/Sr ratios were synthesized via a sol–gel combustion method in the presence of citric acid as a complexing agent and Pluronic P123 as a templating agent. The effects of the amount of doped La and calcination temperature on the physicochemical properties of the LMSTs were examined using various techniques. Powder X-ray diffraction confirmed the substitution of La{sup 3+} into the SrTiO{sub 3} lattice, generating cubic perovskite La{sub x}Sr{sub 1−x}TiO{sub 3}, for the LMST materials calcined at 600 °C. The purity and crystallinity of the desired perovskite phase were enhanced by citric acid addition. The solubility limit of La{sup 3+} substitution at an La/Sr ratio of 0.43 was determined by structural and morphological studies. Increasing the La doping amount decreased the crystallinity and compositional homogeneity, because an La-rich amorphous phase segregated on the surface, but improved the mesoporosity. N{sub 2} physisorption measurements indicated that the LMSTs had a bimodal pore size distribution, of which the larger one was characterized by the crystallite size of mixed oxides, and the specific surface area of 24.9–37.3 m{sup 2} g{sup −1}. The formation of mesopores in the LMST materials synthesized via sol–gel combustion was explained based on a combination of soft- and hard-templating chemistries. - Highlights: • La-doped mesoporous SrTiO{sub 3} (LMST) was prepared first time via sol-gel combustion. • Pluronic P123 triblock copolymer was used as a cheap templating agent. • Citric acid as a complexing agent enhanced the purity and crystallinity of SrTiO{sub 3}. • The textural properties of LMST were improved by increasing the La doping amount. • Mesopore formation was explained by a combined soft- and hard-templating route.

  16. Study of damage and helium diffusion in fluoro-apatites; Etude de l'endommagement et de la diffusion de l'helium dans des fluoroapatites

    Energy Technology Data Exchange (ETDEWEB)

    Miro, S

    2004-12-15

    This work lies within the scope of the study of the radionuclides containment matrices. The choice of the fluoro-apatites as potential matrices of containment was suggested by the notable properties of these latter (thermal and chemical stability even under radioactive radiation). By irradiations with heavy ions and a helium implantation we simulated the effects related to the alpha radioactivity and to the spontaneous nuclear fission of the radionuclides. Thanks to the study of Durango fluoro-apatite single crystals and fluoro-apatite sintered ceramics, we evidenced that the damage fraction as well as the unit cell deformations increase with the electronic energy loss and with the substitution. These effects are followed at high fluences by a phenomenon of re-crystallization. The study of the helium diffusion points out that the thermal diffusion process improves with the substitution and strongly increases with heavy ions irradiation. (author)

  17. Microstructural Study of Neodmium Nickelate Doped with Strontium Synthesized by Gelatin Method

    Directory of Open Access Journals (Sweden)

    R. M. P. B. Oliveira

    2013-01-01

    Full Text Available In this work nickelate nanoparticles were synthesized using a simple and fast new route, which makes use of gelatin as an organic precursor in order to evaluate the performance of the synthesis method to obtain materials and the influence of the strontium replacement on the structural parameters of the powders. Samples of Nd2-xSrxNiO4 (x=0 and 0.4 were calcined at 700 and 900°C at a heating of 10°C/min for 4 hours. X-ray powder diffraction patterns were obtained for all the samples, and the Rietveld Method was applied in order to determine the crystallite size using Scherrer's equation, the lattice parameters, and phase concentration. The results obtained using these techniques confirmed that the main crystal structure consists of the distorted K2NiF4-type tetragonal I4/mmm. In addition, scanning electron microscopy images revealed the formation of nanosized particles.

  18. Niobium Doped Lanthanum Strontium Ferrite as A Redox-Stable and Sulfur-Tolerant Anode for Solid Oxide Fuel Cells.

    Science.gov (United States)

    Li, Jingwei; Wei, Bo; Cao, Zhiqun; Yue, Xing; Zhang, Yaxin; Lü, Zhe

    2018-01-10

    The Nb-doped lanthanum strontium ferrite perovskite oxide La 0.8 Sr 0.2 Fe 0.9 Nb 0.1 O 3-δ (LSFNb) is evaluated as an anode material in a solid oxide fuel cell (SOFC). The effects of Nb partial substitution in the crystal structure, the electrical conductivity, and the valence of Fe ions are studied. LSFNb exhibits good structural stability in a severe reducing atmosphere at 800 °C, suggesting that high-valent Nb can effectively promote the stability of the lattice structure. The concentration of Fe 2+ increases after Nb doping, as confirmed by X-ray photoelectron spectroscopy. The maximum power density of a thick Sc-stabilized zirconia (ScSZ) electrolyte-supported single cell reached 241.6 mW cm -2 at 800 °C with H 2 as fuel. The cell exhibited excellent stability for 100 h continuous operation without detectable degeneration. Scanning electron microscopy clearly revealed exsolution on the LSFNb surface after operation. Meanwhile, LSFNb particles agglomerated significantly during long-term stability testing. Impedance spectra suggested that both the LSFNb anode and the (La 0.75 Sr 0.25 ) 0.95 MnO 3-δ /ScSZ cathode underwent an activation process during long-term testing, through which the charge transfer ability increased significantly. Meanwhile, low-frequency resistance (R L ) mainly attributed to the anode (80 %) significantly increased, probably due to the agglomeration of LSFNb particles. The LSFNb anode exhibits excellent anti-sulfuring poisoning ability and redox stability. These results demonstrate that LSFNb is a promising anode material for SOFCs. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Fabrication of barium- and strontium-doped silica/titania hollow nanoparticles and their synergetic effects on promoting neuronal differentiation by activating ERK and p38 pathways.

    Science.gov (United States)

    Kim, Sojin; Jang, Yoonsun; Oh, Wan-Kyu; Kim, Chanhoi; Jang, Jyongsik

    2014-07-01

    Pristine, barium-doped, and strontium-doped hollow nanoparticles (p-HNPs, Ba-HNP, and Sr-HNP; HNPs) are prepared by sonication-mediated etching and redeposition (SMER) method and alkali-earth-metal hydroxide solution treatment. The HNPs are investigated to facilitate synergetic neuronal differentiation through alkali-earth-metal doping and in conjunction with nerve growth factor (NGF). PC12 cells are used as model cells for neuronal differentiation. The differentiation efficiency is improved in the presence of the HNPs+NGF, and the neurite length is in the order of Sr-HNP+NGF > Ba-HNP+NGF > p-HNP+NGF > NGF. Silica/titania have increasing effect on both differentiation efficiency and neurite length, and doped barium/strontium influences additional elongation of the average neurite length. Take advantage of hollow structure, NGF is encapsulated into HNPs, and they are further applied for directly inducing differentiation. The maximum differentiation efficiency is 67% in presence of the NGF-encapsulated Sr-HNP, which was 1.3 times higher than previous research. Furthermore, the neurite length is also 2.7 times higher than MnO2 decorated poly(3,4-ethylenedioxythiophene) nanoellipsoids. Ba- and Sr-HNP may offer a possibility for novel application of metal-hybrid nanomaterials for cell differentiation, and can be expanded to other cellular applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Optical properties of Er{sup 3+}-doped strontium barium niobate nanocrystals obtained by thermal treatment in glass

    Energy Technology Data Exchange (ETDEWEB)

    Haro-Gonzalez, P. [Dep. of Fisica Fundamental Experimental, Electronica y Sistemas, Universidad de La Laguna Avda Astrofisico Franscisco Sanchez, 38206 La Laguna, S/C de Tenerife (Spain)], E-mail: patharo@ull.es; Lahoz, F. [Dep. of Fisica Fundamental Experimental, Electronica y Sistemas, Universidad de La Laguna Avda Astrofisico Franscisco Sanchez, 38206 La Laguna, S/C de Tenerife (Spain); Gonzalez-Platas, J. [Dep. of Fisica Fundamental II, Universidad de La Laguna, 38206 La Laguna, S/C de Tenerife (Spain); Caceres, J.M. [Dep. of Edafologia y Geologia, Universidad de La Laguna, 38206 La Laguna, S/C de Tenerife (Spain); Gonzalez-Perez, S. [Dep. of Fisica Fundamental Experimental, Electronica y Sistemas, Universidad de La Laguna Avda Astrofisico Franscisco Sanchez, 38206 La Laguna, S/C de Tenerife (Spain); Marrero-Lopez, D. [Dep. of Quimica Inorganica, Universidad de La Laguna, 38206 La Laguna, S/C de Tenerife (Spain); Capuj, N. [Dep. of Fisica Basica, Universidad de La Laguna, 38206 La Laguna, S/C de Tenerife (Spain); Martin, I.R. [Dep. of Fisica Fundamental Experimental, Electronica y Sistemas, Universidad de La Laguna Avda Astrofisico Franscisco Sanchez, 38206 La Laguna, S/C de Tenerife (Spain)

    2008-05-15

    Measurements of the optical properties of Er{sup 3+} ions in strontium barium niobate glass and glass ceramics have been carried out. The glasses have been fabricated using a melt-quenching method, and the glass ceramic samples have been obtained from the glass precursor by a thermal treatment. The ceramic samples formed by a glassy phase, and a crystalline phase contains nanocrystals of Sr{sub 1-x}Ba{sub x}Nb{sub 2}O{sub 6} (SBN) doped with Er{sup 3+} ions with a mean size of {approx}50 nm, as confirmed with XRD. Green up-conversion emission has been obtained under excitation at 800 nm, and the temporal evolution of this emission has been reported with the purpose of determining the involved up-conversion mechanism. These optical measures have confirmed that the Er{sup 3+} ions have been incorporated into the SBN matrix, after a thermal treatment, which produced an increment of the up-conversion efficiency.

  1. Orange-red emitting europium doped strontium ortho-silicate phosphor prepared by a solid state reaction method.

    Science.gov (United States)

    Sahu, Ishwar Prasad

    2017-05-01

    In the present article we report europium-doped strontium ortho-silicates, namely Sr 2 SiO 4 :xEu 3+ (x = 1.0, 1.5, 2.0, 2.5 or 3.0 mol%) phosphors, prepared by solid state reaction method. The crystal structures of the sintered phosphors were consistent with orthorhombic crystallography with a Pmna space group. The chemical compositions of the sintered phosphors were confirmed by energy dispersive X-ray spectroscopy (EDS). Thermoluminescence (TL) kinetic parameters such as activation energy, order of kinetics and frequency factors were calculated by the peak shape method. Orange-red emission originating from the 5 D 0 - 7 F J (J = 0, 1, 2, 3) transitions of Eu 3+ ions could clearly be observed after samples were excited at 395 nm. The combination of these emissions constituted orange-red light as indicated on the Commission Internationale de l'Eclairage (CIE) chromaticity diagram. Mechanoluminescence (ML) intensity of the prepared phosphor increased linearly with increasing impact velocity of the moving piston that suggests that these phosphors can also be used as sensors to detect the stress of an object. Thus, the present investigation indicates that the piezo-electricity was responsible for producing ML in the prepared phosphor. Copyright © 2016 John Wiley & Sons, Ltd.

  2. Magnetic and electromagnetic properties of Pr doped strontium ferrite/polyaniline composite film

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Ying; Li, Yuqing; Wang, Yan, E-mail: wangyan287580632@126.com

    2014-11-15

    This paper reported three acid (including hydrochloric acid HCl, p-toluenesulfonic acid PTS and D-camphor-10-acid CSA) doped SrPr{sub 0.2}Fe{sub 11.8}O{sub 19}/PANI composite film and the HCl–PANI film prepared by a sol–gel method and in-situ oxidative polymerization. The characteristics of the film phase structure, surface morphology, conductivity and magnetic and electromagnetic properties were studied by using XRD, XPS, FESEM, four-probe tester, VSM and Vector Network Analyzer. The resistivity of organic acid doped composite films is higher than that of the HCl doped one. The saturation and remanent magnetization of PTS and HCl doped composite films are greater than the CSA-doped one; however, the coercivity of the three acid doped composite films is basically 5546 Oe. The saturation magnetization, remanent magnetization and coercivity of SrPr{sub 0.2}Fe{sub 11.8}O{sub 19} film are greater than those of the SrPr{sub 0.2}Fe{sub 11.8}O{sub 19}–PANI composite film. In the frequency range of 8–12 GHz, the dielectric loss of HCl–PANI film is the maximum, and the dielectric loss of SrPr{sub 0.2}Fe{sub 11.8}O{sub 19} film is the minimum; the magnetic loss of the four films is in descending order as SrPr{sub 0.2}Fe{sub 11.8}O{sub 19} film, PrSrM/(HCl–PANI) composite film, PrSrM/(CSA–PANI) and HCl–PANI film. - Highlights: • Synthesizing three acid doped SrPr{sub 0.2}Fe{sub 11.8}O{sub 19}/PANI composite films. • By sol–gel method and in-situ oxidative polymerization. • With excellent magnetic and electromagnetic properties. • The particular coating structure of PANI and Sr-ferrite. • Great interest for magnetic material and microwave absorbers.

  3. Tailoring structure and magnetic characteristics of strontium hexaferrite via Al doping engineering

    Energy Technology Data Exchange (ETDEWEB)

    Wang, H.Z.; Hai, Y.N. [State Key Lab of High Power Semiconductor Laser of Changchun University Science and Technology, Changchun University Science and Technology, Changchun 130022 (China); Yao, B., E-mail: binyao@jlu.edu.cn [State Key Lab of Superhard Materials and Department of Physics, Jilin University, Changchun 130023 (China); Xu, Y. [School of Physics, Northeast Normal University, Changchun 130024 (China); Shan, L. [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry and Department of Chemistry, Jilin University, Changchun 130012 (China); Xu, L.; Tang, J.L.; Wang, Q.H. [State Key Lab of High Power Semiconductor Laser of Changchun University Science and Technology, Changchun University Science and Technology, Changchun 130022 (China)

    2017-01-15

    Emerging structure and magnetic properties of Al{sup 3+}-modified SrFe{sub 12}O{sub 19} M-type hexaferrite system (SrAl{sub x}Fe{sub 12−x}O{sub 19}) had been studied in detail via doping engineering. With Al{sup 3+} ion nominal content ranging from 0 to 4 (0≤x≤4), the lattice parameters decrease due to the substitution of Fe{sup 3+} ions by smaller Al{sup 3+} ions, and the magnetization shows a continuous reduction with the increasing of Al content. For the coercivity, its value initially increases, reaching a maximum value of 16,876.9 Oe at x=3, and then reduces with the Al content further increase. When all the Fe{sup 3+} ions (x=4) are replaced by Al{sup 3+} ions, the net magnetic moment will be closed to zero, that will weaken the exchange interaction between Fe{sup 3+} ions, resulting in decrease of coercivity sharply and transformation ferrimagnetism into antiferromagnetism. The mechanism of the improvement of the magnetic properties induced by Al doping is discussed in the present work. - Highlights: • The coercivity reach a maximum value at x=3 in the SrAl{sub x}Fe{sub 12−x}O{sub 19}. • The coercivity of SrFe{sub 12}O{sub 19} increases due to nonmagnetic Al doping. • The saturation magnetization of SrFe{sub 12}O{sub 19} decreases due to nonmagnetic Al doping. • The transformation ferrimagnetism into antiferromagnetism by nonmagnetic Al doping.

  4. Spectroscopic and nonlinear optical studies of pure and Nd-doped lanthanum strontium borate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Harde, G. B. [Department of Physics, Shri R. R. Lahoti Science College, Morshi, Maharashtra, India-444905 (India); Department of Physics, Sant Gadge Baba Amravati University, Amravati, Maharashtra, India-444602 (India); Muley, G. G., E-mail: gajananggm@yahoo.co.in [Department of Physics, Sant Gadge Baba Amravati University, Amravati, Maharashtra, India-444602 (India)

    2016-05-06

    Borate glasses of the system xNd{sub 2}O{sub 3}-(1-x) La{sub 2}O{sub 3}-SrCO{sub 3}-10H{sub 3}BO{sub 3} (with x = 0 and 0.05) were prepared by using a convectional melt quenching technique. The amorphous nature of the quenched glasses has been confirmed by powder X-ray diffraction analysis. In order to study the spectroscopic and nonlinear optical properties of fabricated glasses, ultraviolet-visible transmission spectroscopy and open aperture z-scan measurements have been employed. In Nd doped glasses, the transition {sup 4}I{sub 9/2} → {sup 4}G{sub 5/2} + {sup 2}G{sub 7/2} has found more prominent than the other transitions. Optical band gap energies of glasses have been determined and found less for Nd doped glass.

  5. Magnetic study of M-type Ru–Ti doped strontium hexaferrite nanocrystalline particles

    Energy Technology Data Exchange (ETDEWEB)

    Alsmadi, A. M.; Bsoul, I.; Mahmood, S. H.; Alnawashi, G.; Al-Dweri, F. M.; Maswadeh, Y.; Welp, U.

    2015-11-01

    We carried out a systematic study on the effect of the substitution of Ti2+ and Ru4+ ions for Fe3+ ions on the structural and magnetic properties of the strontium ferrite SrFe12-2xRuxTixO19 nanoparticles with (0 <= x <= 0: 3), using x-ray diffraction, Quantum Design PPMS-9 magnetometry, and electrical resistivity. A clear irreversibility between the zero-field-cooled and field-cooled curves was observed below room temperature and the zero-field-cooled magnetization curves displayed a broad peak at a temperature TM. These results were discussed within the framework of random particle assembly model and associated with the magnetic domain wall motion. The resistivity data showed some kind of a transition from insulator to perfect insulator around TM. The high-temperature magnetization measurements exhibited sharp peaks just below T-c indicating a superparamagnetic behavior. With Ru-Ti substitution, the saturation magnetization at 5 K showed small variations were it slightly increased with increasing x up to 0.2, and then decrease for x = 0.3, while the coercivity decreased monotonically, recording a reduction of about 78% at x = 0.3. These results were discussed in light of the cationic distributions based on the results of the structural refinements.

  6. Effect of strontium doping on dielectric, ferroelectric and piezoelectric properties of PLZTN ceramics

    International Nuclear Information System (INIS)

    Ramam, Koduri; Lopez, Marta

    2007-01-01

    Ceramic compositions of [Pb 1-x-y La x Sr y ][(Zr z Ti 1-z ) (1-(x/4)-(5/4)k) Nb k ]O 3 (PLSZTN), where y = 0, 0.5, 1.0 and 1.5 mol% have been fabricated by solid-state reaction method. Introduction of strontium in PLZTN lattice showed ferroelectric tetragonal nature and further increment of Sr 2+ favored intensified tetragonality. Microstructure studies revealed that grain growth enhanced with the addition of Sr 2+ and inter-diffusion between multiple ions promoted apparent density in the ceramics. The substitution of isovalent Sr 2+ at Pb-site and donor pentavalent Nb 5+ at Zr/Ti-site enhanced the dielectric constant (ε RT = 2384) while decreasing the Curie temperature (T c ). The substitution of 1.5 mol% Sr evidently increased ferroelectric properties (remanent (P r = 32.66 μC/cm 2 ) and spontaneous (P s = 38.54 μC/cm 2 ) polarization), respectively. Sr-modified PLZTN showed a significant influence on the piezoelectric properties which enhanced till 1.5 mol% Sr in PLZTN ceramic system, which may be applicable for possible sensor and actuator applications

  7. Structural and magnetic properties of conventional and microwave treated Ni-Zr doped barium strontium hexaferrite

    Energy Technology Data Exchange (ETDEWEB)

    Kanagesan, S., E-mail: kanagu1980@gmail.com [Center for Materials Science and Nano Devices, Department of Physics, SRM University, Kattankulathur 603203, Tamil Nadu (India); Jesurani, S. [Center for Materials Science and Nano Devices, Department of Physics, SRM University, Kattankulathur 603203, Tamil Nadu (India); Department of Physics, Jeyaraj Annapackium College for Women, Periyakulam 625601, Tamil Nadu (India); Velmurugan, R. [Center for Materials Science and Nano Devices, Department of Physics, SRM University, Kattankulathur 603203, Tamil Nadu (India); Prabu, S. [Department of Chemistry, S.K.P. Engineering College, Anna University of Technology Chennai, Thiruvannamalai 606 611, Tamil Nadu (India); Kalaivani, T. [Center for Materials Science and Nano Devices, Department of Physics, SRM University, Kattankulathur 603203, Tamil Nadu (India)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Saturation magnetization increases whereas the coercivity decreases. Black-Right-Pointing-Pointer The transition from hard phase to soft phase. Black-Right-Pointing-Pointer Therefore, it is used for high-density magnetic recording applications. -- Abstract: M-type hexaferrites of component B{sub 0.5}Sr{sub 0.5}Fe{sub 12-2x}Ni{sub x}Zr{sub x}O{sub 19} were investigated. The XRD patterns show single phase of the magnetoplumbite barium strontium ferrite and no other phases were present. Significant increase in line broadening of the XRD patterns was observed indicating a decrease of grain size. The samples exhibit well defined crystallization; all of them are hexagonal platelet grains. As the substitution level increased x = 0.2-0.8 mol%, the grains are agglomerated and the average diameter increased. The H{sub c} decreases remarkably with increasing Ni and Zr ions content. It was found that the particle size could be effectively decreased and coercivity H{sub c} could easily be controlled by varying the concentration (x) without significantly decreasing saturation magnetization. In particular, Ba{sub 0.5}Sr{sub 0.5}Fe{sub 12-2x}Ni{sub x}Zr{sub x}O{sub 19} with x = 0.2, 0.4, 0.6, 0.8 mol% has suitable magnetic characteristics with particle size small enough for high-density magnetic recording applications.

  8. Strontium-Doped Calcium Phosphate and Hydroxyapatite Granules Promote Different Inflammatory and Bone Remodelling Responses in Normal and Ovariectomised Rats

    Science.gov (United States)

    Xia, Wei; Emanuelsson, Lena; Norlindh, Birgitta; Omar, Omar; Thomsen, Peter

    2013-01-01

    The healing of bone defects may be hindered by systemic conditions such as osteoporosis. Calcium phosphates, with or without ion substitutions, may provide advantages for bone augmentation. However, the mechanism of bone formation with these materials is unclear. The aim of this study was to evaluate the healing process in bone defects implanted with hydroxyapatite (HA) or strontium-doped calcium phosphate (SCP) granules, in non-ovariectomised (non-OVX) and ovariectomised (OVX) rats. After 0 (baseline), six and 28d, bone samples were harvested for gene expression analysis, histology and histomorphometry. Tumour necrosis factor-α (TNF-α), at six days, was higher in the HA, in non-OVX and OVX, whereas interleukin-6 (IL-6), at six and 28d, was higher in SCP, but only in non-OVX. Both materials produced a similar expression of the receptor activator of nuclear factor kappa-B ligand (RANKL). Higher expression of osteoclastic markers, calcitonin receptor (CR) and cathepsin K (CatK), were detected in the HA group, irrespective of non-OVX or OVX. The overall bone formation was comparable between HA and SCP, but with topological differences. The bone area was higher in the defect centre of the HA group, mainly in the OVX, and in the defect periphery of the SCP group, in both non-OVX and OVX. It is concluded that HA and SCP granules result in comparable bone formation in trabecular bone defects. As judged by gene expression and histological analyses, the two materials induced different inflammatory and bone remodelling responses. The modulatory effects are associated with differences in the spatial distribution of the newly formed bone. PMID:24376855

  9. 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.

  10. Near-infrared quantum cutting in Yb3+ ion doped strontium vanadate

    Science.gov (United States)

    Sawala, N. S.; Bajaj, N. S.; Omanwar, S. K.

    2016-05-01

    The materials Sr3-x(VO4)2:xYb were successfully synthesized by co-precipitation method varying the concentration of Yb3+ ions from 0 to 0.06 mol. It was characterize by powder X-ray powder diffraction (XRD) and surface morphology was studied by scanning electronic microscope (SEM). The photoluminescence (PL) properties were studied by spectrophotometers in near infra red (NIR) and ultra violet visible (UV-VIS) region. The Yb3+ ion doped tristrontium vanadate (Sr3(VO4)2) phosphors that can convert a photon of UV region (349 nm) into photons of NIR region (978, 996 and 1026 nm). Hence this phosphor could be used as a quantum cutting (QC) luminescent convertor in front of crystalline silicon solar cell (c-Si) panels to reduce thermalization loss due to spectral mismatch of the solar cells. The theoretical value of quantum efficiency (QE) was calculated from steady time decay measurement and the maximum efficiency approached up to 144.43%. The Sr(3-x) (VO4)2:xYb can be potentiality used for betterment of photovoltaic (PV) technology.

  11. Enhanced Magnetization of Sol-Gel Synthesized Pb-Doped Strontium Hexaferrites Nanocrystallites at Low Temperature

    Directory of Open Access Journals (Sweden)

    Shahid M. Ramay

    2014-01-01

    Full Text Available Effect of Pb doping on the structural and low temperature magnetic properties of SrPbxFe12-xO19 (x=0,0.1,0.2,0.3,and  0.4, synthesized by sol-gel autocombustion technique, has been investigated. The powder samples were sintered at 800°C for 2 h in order to develop the stable hexagonal phase, characteristic of the SrFe12O19 structure. The consequences of Pb substitution (at iron sites on various structural parameters like lattice constants, unit cell volume, crystallite size, and porosity have been discussed. Fourier transform infrared frequency bands were utilized to determine the formation of tetrahedral and octahedral clusters of M-type ferrites. Hexagonal texture of the grains, a characteristic of the hexagonal crystal structure of SrFe12O19, was refined by Pb substitution. The magnetic properties, determined using a vibrating sample magnetometer, revealed that saturation magnetization decreased, while coercivity was increased with the increase of Pb contents. However, the increased squareness ratio and hence the energy product motivate the utilization of these ferrite compositions where hard magnetic characteristics are required. The increased values of saturation magnetization were observed at reduced temperature of 200 K, attributable to the better spin alignments of individual magnetic moments at low temperature.

  12. Synthesis of magnesium- and manganese-doped hydroxyapatite structures assisted by the simultaneous incorporation of strontium

    Energy Technology Data Exchange (ETDEWEB)

    Moreira, Mirna Pereira [Laboratório de Biomateriais, P" 2CEM/UFS, Av. Marechal Rondon, s/n, São Cristóvão 49100-000, Sergipe (Brazil); Dulce de Almeida Soares, Gloria [Dep. de Eng. Metal. e de Materiais, COPPE/UFRJ, CP 68505, Rio de Janeiro 21941-972 (Brazil); Dentzer, Joseph; Anselme, Karine [Institut de Science des Matériaux de Mulhouse (IS2M), CNRS UMR7361, Université de Haute-Alsace, 15, rue Jean Starcky, BP 2488, 68057 Mulhouse (France); Sena, Lídia Ágata de; Kuznetsov, Alexei [Divisão de Metrologia de Materiais, Inmetro, Av. N. Sra. das Graças, 50, Duque de Caxias 25250-020, Rio de Janeiro (Brazil); Santos, Euler Araujo dos, E-mail: euler@ufs.br [Laboratório de Biomateriais, P" 2CEM/UFS, Av. Marechal Rondon, s/n, São Cristóvão 49100-000, Sergipe (Brazil)

    2016-04-01

    Samples of crystalline hydroxyapatite (HA) with and without the addition of individual Mg{sup 2+}, Mn{sup 2+} and Sr{sup 2+} ions and samples with the addition of all three ions simultaneously were prepared using the precipitation method in an aqueous medium. Chemical, structural, spectroscopic and thermophysical analyses of the synthesized samples were conducted. The obtained results indicate that Sr{sup 2+} ions were easily incorporated into the HA crystal structure, whereas it was difficult to incorporate Mg{sup 2+} and Mn{sup 2+} ions into the HA lattice when these ions were individually introduced into the samples. The synthesis of HA with Mg{sup 2+} or Mn{sup 2+} ions is characterized by the formation of HA with a low concentration of doping elements that is outweighed by the amount of these atoms present in less biocompatible phases that formed simultaneously. However, the incorporation of Sr{sup 2+} along with Mg{sup 2+} and Mn{sup 2+} ions into the samples allowed for the synthesis of HA with considerably higher concentrations of Mg{sup 2+} and Mn{sup 2+} in the crystal lattice. - Graphical abstract: Sr{sup 2+} ions were easily incorporated into the HA lattice, whereas Mg{sup 2+} and Mn{sup 2+} ions were hardly retained in the HA structure after heating to 1000 °C when they were individually incorporated in the samples. Nevertheless, co-substitution with Sr{sup 2+} ions allowed for better fixation of the Mg{sup 2+} and Mn{sup 2+} ions into the HA lattice. - Highlights: • Mg{sup 2+} and Mn{sup 2+} ions have a great difficulty being stabilized in the apatite lattice. • Sr{sup 2+} ions can stabilize Mg{sup 2+} and Mn{sup 2+} in the hydroxyapatite structure. • Except for Mn{sup 2+}, Sr{sup 2+} and Mg{sup 2+} obstruct the release of CO{sub 2}.

  13. Effect of Co-Zr doping on structural and magnetic properties of nanocrystalline strontium hexaferrite SrCoxZrxFe(12-2x): a neutron diffraction study

    International Nuclear Information System (INIS)

    Meena, Sher Singh; Jain, Anil; Yusuf, S.M.; Kaur, Prabhjyot; Chawla, S.K.

    2016-01-01

    Extensive research is being carried out on strontium hexaferrites (SHF) to optimize its structural and macroscopic magnetic properties for its use in microwave devices, recording media with high density magnetic recording, multiferroic, bioceramics and nanoscience and technology. The current focus is to synthesize ferrites with well controlled shape and size, fine morphology, uniform composition and desired magnetic properties at lower sintering temperatures for their use in electronic material industry. Tailoring of magnetic properties has been realized by the substitution of one or more cations at Fe or Sr sites. Citrate precursor solgel technique is simple and ensures a lower sintering temperature because the decomposition of precursor is extremely exothermic. We employed this route to accomplish the synthesis of Co-Zr doped nanocrystalline M-type hexaferrites SrCo x Zr x Fe (12-2x )O 19 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) with a purpose to investigate the structural properties and dependence of magnetic properties on the occupancy of five cystallographic positions by dopant ions. Correlation between the distribution of dopant cations over five crystallographic positions and magnetic properties of strontium hexaferrites are probed by Neutron diffraction and Mössbauer spectroscopy studies. Neutron powder diffraction experiments at room temperature were carried out using neutron powder diffractometer-1 at Dhurva reactor, Trombay, India. Rietveld refinements of room temperature neutron diffraction patterns confirm the formation of pure single phase hexagonal ferrites at 800°C. Upon Co-Zr doping both the lattice constants a and c are increased. Room temperature Mössbauer spectra show five sextets (Zeeman splitting patterns) belongs to five Fe sites. Hyperfine filed of all five sextets are decreased with doping at Fe site. Neutron diffraction results are also supported by the Mössbauer data. (author)

  14. Synthesis, processing and characterization of the solid oxide half-cells cathode/electrolyte of strontium-doped lanthanum manganite/Yttria-stabilized zirconia

    International Nuclear Information System (INIS)

    Chiba, Rubens

    2010-01-01

    The ceramic films of strontium-doped lanthanum manganite (LSM) and strontium doped lanthanum manganite/Yttria-stabilized zirconia (LSM/YSZ) are used as cathodes of the high temperature solid oxide fuel cells (HTSOFC). These porous ceramic films had been deposited on the YSZ dense ceramic substrate, used as electrolyte, structural component of the module, thus conferring a configuration of half-cell called auto-support. The study of the half-cell it is basic, therefore in the interface cathode/electrolyte occurs the oxygen reduction reaction, consequently influencing in the performance of the HTSOFC. In this direction, the present work contributes for the processing of thin films, using the wet powder spraying technique, adopted for the conformation of the ceramic films for allowing the attainment of porous layers with thicknesses varied in the order of micrometers. The LSM powders were synthesized by the citrate technique and the LSM/YSZ powders synthesized by the solid mixture technique. In the stage of formation were prepared organic suspensions of LSM and LSM/YSZ fed by gravity in a manual aerograph. For the formation of the YSZ substrate was used a hydraulic uniaxial press. The attainment of solid oxide half-cells cathode/electrolyte was possible of crystalline structures hexagonal for phase LSM and cubic for phase YSZ. The half-cells micrographs show that the YSZ substrate is dense, enough to be used as solid electrolyte, and the LSM and LSM/YSZ films are presented porous with approximately 30 μm of thickness and good adherence between the cathodes and the electrolyte. The presence of composite cathode between the LSM cathode and YSZ substrate, presented an increase in the electrochemical performance in the oxygen reduction reaction. (author)

  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. Role of glass structure in defining the chemical dissolution behavior, bioactivity and antioxidant properties of zinc and strontium co-doped alkali-free phosphosilicate glasses.

    Science.gov (United States)

    Kapoor, Saurabh; Goel, Ashutosh; Tilocca, Antonio; Dhuna, Vikram; Bhatia, Gaurav; Dhuna, Kshitija; Ferreira, José M F

    2014-07-01

    We investigated the structure-property relationships in a series of alkali-free phosphosilicate glass compositions co-doped with Zn(2+) and Sr(2+). The emphasis was laid on understanding the structural role of Sr(2+) and Zn(2+) co-doping on the chemical dissolution behavior of glasses and its impact on their in vitro bioactivity. The structure of glasses was studied using molecular dynamics simulations in combination with solid state nuclear magnetic resonance spectroscopy. The relevant structural properties are then linked to the observed degradation behavior, in vitro bioactivity, osteoblast proliferation and oxidative stress levels. The apatite-forming ability of glasses has been investigated by X-ray diffraction, infrared spectroscopy and scanning electron microscopy-energy-dispersive spectroscopy after immersion of glass powders/bulk in simulated body fluid (SBF) for time durations varying between 1h and 14 days, while their chemical degradation has been studied in Tris-HCl in accordance with ISO 10993-14. All the glasses exhibit hydroxyapatite formation on their surface within 1-3h of their immersion in SBF. The cellular responses were observed in vitro on bulk glass samples using human osteosarcoma MG63 cell line. The dose-dependent cytoprotective effect of glasses with respect to the concentration of zinc and strontium released from the glasses is also discussed. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  17. High temperature dielectric relaxation anomaly of Y³⁺ and Mn²⁺ doped barium strontium titanate ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Shiguang; Mao, Chaoliang, E-mail: maochaoliang@mail.sic.ac.cn, E-mail: xldong@mail.sic.ac.cn; Wang, Genshui; Yao, Chunhua; Cao, Fei; Dong, Xianlin, E-mail: maochaoliang@mail.sic.ac.cn, E-mail: xldong@mail.sic.ac.cn [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China)

    2014-10-14

    Relaxation like dielectric anomaly is observed in Y³⁺ and Mn²⁺ 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.

  18. Improvement in crystallization and electrical properties of barium strontium titanate thin films by gold doping using metal-organic deposition method

    International Nuclear Information System (INIS)

    Wang, H.-W.; Nien, S.-W.; Lee, K.-C.; Wu, M.-C.

    2005-01-01

    The effect of gold (Au) on the crystallization, dielectric constant and leakage current density of barium strontium titanate (BST) thin films was investigated. BST thin films with various gold concentrations were prepared via a metal-organic deposition process. The X-ray diffraction shows enhanced crystallization as well as expanded lattice constants for the gold-doped BST films. Thermal analysis reveals that the gold dopant induces more complete decomposition of precursor for the doped films than those of undoped ones. The leakage current density of BST films is greatly reduced by the gold dopant over a range of biases (1-5 V). The distribution of gold was confirmed by electron energy loss spectroscopy and found to be inside the BST grains, not in the grain-boundaries. Gold acted as a catalyst, inducing the nucleation of crystallites and improving the crystallinity of the structure. Its addition is shown to be associated to the improvement of the electrical properties of BST films

  19. Analysis of the optical properties of Er{sup 3+}-doped strontium barium niobate nanocrystals using time-resolved laser spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kowalska, D.; Haro-Gonzalez, P. [Universidad de La Laguna, Departamento de Fisica Fundamental, Experimental, Electronica y Sistemas, La Laguna, Tenerife (Spain); Martin, I.R. [Universidad de La Laguna, Departamento de Fisica Fundamental, Experimental, Electronica y Sistemas, La Laguna, Tenerife (Spain); Malta Consolider Team, La Laguna, Tenerife (Spain); Caceres, J.M. [Universidad de La Laguna, Departamento de Edafologia y Geologia, La Laguna, Tenerife (Spain)

    2010-06-15

    This paper reports the results obtained in strontium barium niobate (SBN) nanocrystals in glasses doped with 1, 2.5 and 5 mol% of Er{sup 3+} ions. The melt-quenching method was applied to fabricate the glasses with composition SrO-BaO-Nb{sub 2}O{sub 5}-B{sub 2}O{sub 3} and further thermal treatment was used to obtain glass ceramic samples from the glass precursor. X-ray diffraction patterns confirmed the formation of SBN nanocrystals with an average size of about 50 nm in diameter. Time-resolved fluorescence spectra for the emission of Er{sup 3+} ions at 1550 nm have been analyzed in order to confirm the incorporation of the Er{sup 3+} ions into the nanocrystals. Green frequency upconversion emission under excitation at 975 nm coming from the ions in the nanocrystals has been obtained. This intense upconversion is about a factor of 500 higher than that obtained from the ions which reside in the glassy phase. Moreover, temporal evolution studies have been carried out with the purpose of determining the involved upconversion mechanism and the importance of these processes as a source of losses for the optical amplification at 1550 nm. (orig.)

  20. Surface modification of strontium-doped porous bioactive ceramic scaffolds via poly(DOPA) coating and immobilizing silk fibroin for excellent angiogenic and osteogenic properties.

    Science.gov (United States)

    Wang, Xu; Gu, Zhipeng; Jiang, Bo; Li, Li; Yu, Xixun

    2016-04-01

    For bioceramic scaffolds employed in clinical applications, excellent bioactivity and tenacity were of great importance. Modifying inorganic SCPP scaffolds with biological macromolecules could obviously improve its bioactivity and eliminate its palpable brittleness. However, it was hard to execute directly due to extremely bad interfacial compatibility between them. In this research, dopamine (DOPA) was introduced onto strontium-doped calcium polyphosphate (SCPP) scaffolds, subsequently the preliminary material was successfully further modified by silk fibroin (SF). SCPP/D/SF possessed suitable biomechanical properties, ability to stimulate angiogenic factor secretion and excellent biocompatibility. Biomechanical examination demonstrated that SCPP/D/SF scaffolds yielded better compressive strength because of improved interfacial compatibility. MTT assay and CLSM observation showed that SCPP/D/SF scaffolds had good cytocompatibility and presented better inducing-cell-migration potential than pure SCPP scaffolds. Meanwhile, its ability to stimulate angiogenic factor secretion was measured through the ELISA assay and immunohistological analysis in vitro and in vivo respectively. The results revealed, superior to SCPP, SCPP/D/SF could effectively promote VEGF and bFGF expression, possibly leading to enhancing angiogenesis and osteogenesis. In a word, SCPP/D/SF could serve as a potential bone tissue engineering scaffold for comparable biomechanical properties and excellent bioactivity. It provided a novel idea for modification of inorganic materials to prepare promising bone tissue engineering scaffolds with the ability to accelerate bone regeneration and vascularization.

  1. Strontium doping promotes bioactivity of rhBMP-2 upon calcium phosphate cement via elevated recognition and expression of BMPR-IA.

    Science.gov (United States)

    Huang, Baolin; Tian, Yu; Zhang, Wenjing; Ma, Yifan; Yuan, Yuan; Liu, Changsheng

    2017-11-01

    Preserving and improving osteogenic activity of bone morphogenetic protein-2 (BMP-2) upon implants remains one of the key limitations in bone regeneration. With calcium phosphate cement (CPC) as model, we have developed a series of strontium (Sr)-doped CPC (SCPC) to address this issue. The effects of fixed Sr on the bioactivity of recombinant human BMP-2 (rhBMP-2) as well as the underlying mechanism were investigated. The results suggested that the rhBMP-2-induced osteogenic activity was significantly promoted upon SCPCs, especially with a low amount of fixed Sr (SrCO 3 content IA (BMPR-IA) to rhBMP-2 and an increased expression of BMPR-IA in C2C12 model cells. As a result, the activations of BMP-induced signaling pathways were different in C2C12 cells incubated upon CPC/rhBMP-2 and SCPCs/rhBMP-2. These findings explicitly decipher the mechanism of SCPCs promoting osteogenic bioactivity of rhBMP-2 and signify the promising application of the SCPCs/rhBMP-2 matrix in bone regeneration implants. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Physical and magnetic properties of highly aluminum doped strontium ferrite nanoparticles prepared by auto-combustion route

    Energy Technology Data Exchange (ETDEWEB)

    Luo, H.; Rai, B.K. [Department of Physics, University of Memphis, Memphis, TN 38152 (United States); Mishra, S.R., E-mail: srmishra@memphis.edu [Department of Physics, University of Memphis, Memphis, TN 38152 (United States); Nguyen, V.V.; Liu, J.P. [Department of Physics, University of Texas, Arlington, TX 76019 (United States)

    2012-08-15

    Highly Al{sup 3+} ion doped nanocrystalline SrFe{sub 12-x}Al{sub x}O{sub 19} (0{<=}x{<=}12), were prepared by the auto-combustion method and heat treated in air at 1100 Degree-Sign C for 12 h. The phase identification of the powders performed using x-ray diffraction show presence of high-purity hexaferrite phase and absence of any secondary phases. With Al{sup 3+} doping, the lattice parameters decrease due to smaller Al{sup 3+} ion replacing Fe{sup 3+} ions. Morphological analysis performed using transmission electron microscope show growth of needle shaped ferrites with high aspect ratio at Al{sup 3+} ion content exceeding x{>=}2. Al{sup 3+} substitution modifies saturation magnetization (M{sub S}) and coercivity (H{sub C}). The room temperature M{sub S} values continuously reduced while H{sub C} value increased to a maximum value of 18,100 Oe at x=4, which is an unprecedented increase ({approx}321%) in the coercivity as compared to pure Sr-Ferrite. However, at higher Al{sup 3+} content x>4, a decline in magnetization and coercivity has been observed. The magnetic results indicate that the best results for applications of this ferrite will be obtained with an iron deficiency in the stoichiometric formulation. - Highlights: Black-Right-Pointing-Pointer The study reports synthesis and characterization of highly aluminum doped SrFe{sub 12-x}Al{sub x}O{sub 19} ferrite. Black-Right-Pointing-Pointer Synthesis of pure phase aluminum doped Sr-Ferrite using autocombustion method is reported. Black-Right-Pointing-Pointer An unprecedented increase in coercivity {approx}321% is observed upon aluminum at x=4 Al doping. Black-Right-Pointing-Pointer The observed magnetic properties of SrFe{sub 12-x}Al{sub x}O{sub 19} are related to changes in anisotropy. Black-Right-Pointing-Pointer And morphology in compound upon aluminum doping.

  3. Magnetic and microwave absorption properties of rare earth ions (Sm{sup 3+}, Er{sup 3+}) doped strontium ferrite and its nanocomposites with polypyrrole

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Juhua, E-mail: luojuhua@163.com [School of Materials Engineering, Yancheng Institute of Technology, Yancheng 224051 (China); Xu, Yang; Mao, Hongkai [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2015-05-01

    M-type strontium ferrite substituted by RE (RE=Sm{sup 3+}, Er{sup 3+}) were prepared via a sol–gel method. Polypyrrole (PPy)/ferrite nanocomposites (with 20 wt% ferrite) were prepared by in situ polymerization method in the presence of ammonium persulfate. Effect of the substituted RE ions on structure, magnetic properties and microwave absorption properties were investigated by X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and vector network analyzer. All XRD patterns show the single phase of strontium hexaferrite without other intermediate phases. The crystallite size of synthesized particle is within the range of 22.2–38.1 nm. The structural in character of the composites were investigated with FT-IR analysis. It shows that the ferrite successfully packed by PPy. TEM photographs show that the particle size had grown up to 50–100 nm after coating with PPy. In the magnetization for the PPy/SrSm{sub 0.3}Fe{sub 11.7}O{sub 19} (SrEr{sub 0.3}Fe{sub 11.7}O{sub 19}) composites, the coercivity (H{sub c}) of the composites both increased compared with the undoped composite while the saturation magnetization (M{sub s}) appeared opposite change with different RE ions. Considering the electromagnetic loss and impedance matching comprehensively, the Er-doped ferrite/PPy composite got the better microwave absorption performance with the maximum RL value of −24.01 dB in 13.8 GHz at 3.0 mm. And its width (<−10 dB) has reached 7.2 GHz which has covered the whole Ku band. - Highlights: • The influence of RE ions on the structure of PPy/SrRE{sub 0.3}Fe{sub 11.7}O{sub 19} is discussed. • The influence of RE ions on the magnetic properties of PPy/SrRE{sub 0.3}Fe{sub 11.7}O{sub 19} is discussed. • The influence of RE ions on electromagnetic losses of PPy/SrRE{sub 0.3}Fe{sub 11.7}O{sub 19} is discussed. • PPy/SrEr{sub 0.3}Fe{sub 11.7}O{sub 19} possessed the excellent absorption property.

  4. Role of aluminum on the physical and spectroscopic properties of chromium-doped strontium alumino borate glasses

    Science.gov (United States)

    Ahmed, Mohamed Raheem; Sekhar, K. Chandra; Hameed, Abdul; Chary, M. Narasimha; Shareefuddin, Md

    2018-03-01

    The glass samples were prepared in accordance with the formula: (30-x)SrO-xAl2O3-69.8B2O3-0.2Cr2O3 (0 ≤x ≤ 15 mol %) by melt quenching method. The absence of Bragg’s peaks confirmed the amorphous nature of the prepared glass samples. It was observed that the molar volume was increasing while the density is decreasing with increasing of Al2O3 content. Optical absorption study was performed to evaluate the optical bandgap, oxygen packing density, ionic packing density and Urbach energies. The Racah parameters (B and C) and Dq/B ratio have been calculated. Fourier transform infrared (FTIR) spectra recorded in the region from 400-1600 cm-1 at room-temperature (RT) confirmed the formation of BO3, BO4 and AlO4 groups upon the addition of strontium oxide as modifier. The Raman spectra of all the glasses recorded over continuous spectral range 200-1600 cm-1 exhibited different spectral bands. The EPR spectra recorded at 9.7 GHz (X-band frequency) have four resonance signals. The signal at g ≈ 5.33 is due to Cr3+ ion sites of rhombic symmetry and signal at g ≈ 1.97 is due to contribution from Cr3+ and Cr5+ ion pairs.

  5. Antibacterial and osteo-stimulatory effects of a borate-based glass series doped with strontium ions.

    Science.gov (United States)

    Li, Yiming; Stone, Wendy; Schemitsch, Emil H; Zalzal, Paul; Papini, Marcello; Waldman, Stephen D; Towler, Mark R

    2016-11-01

    This work considered the effect of both increasing additions of Strontium (Sr 2+ ) and incubation time on solubility and both antibacterial and osteo-stimulatory effects of a series of glasses based on the B 2 O 3 -P 2 O 5 -CaCO 3 -Na 2 CO 3 -TiO 2 -SrCO 3 series. The amorphous nature of all the glasses was confirmed by X-ray diffraction. Discs of each glass were immersed in de-ionized water for 1, 7 and 30 days, and the water extracts were used for ion release profiles, pH measurements and cytotoxicity testing. Atomic absorption spectroscopy was employed to detect the release of Na + , Ca 2+ and Sr 2+ ions from the glasses with respect to maturation, which indicated that the addition of Sr 2+ retarded solubility of the glass series. This effect was also confirmed by weight loss analysis through comparing the initial weight of glass discs before and after periods of incubation. The incorporation of Sr 2+ in the glasses did not influence the pH of the water extracts when the glasses were stored for up to 30 days. Cytotoxicity testing with an osteoblastic cell line (MC3T3-E1) indicated that glasses with the higher (20 mol% and 25 mol%) Sr 2+ incorporation promoted proliferation of osteoblast cells, while the glasses with lower Sr 2+ contents inhibited cell growth. The glass series, except for Ly-B5 (which contained the highest Sr 2+ incorporation; 25 mol%), were bacteriostatic against S. aureus in the short term (1-7 days) as a result of the dissolution products released. © The Author(s) 2016.

  6. 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

  7. Synthesis and characterization of calcium hydroxy and fluoroapatite functionalized with methyl phosphonic dichloride

    Energy Technology Data Exchange (ETDEWEB)

    Agougui, Hassen; Aissa, Abdallah [Laboratoire de Physico-Chimie des Materiaux, Faculte des Sciences de Monastir, 5019 Monastir (Tunisia); Debbabi, Mongi, E-mail: m.debbabi@yahoo.fr [Laboratoire de Physico-Chimie des Materiaux, Faculte des Sciences de Monastir, 5019 Monastir (Tunisia)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Surface reactivity of apatites toward methyl phosphonic dichloride is tested. Black-Right-Pointing-Pointer Chemical analysis shows that hydroxyapatite is more reactive. Black-Right-Pointing-Pointer NMR spectra show the formation of Ca-O-P{sub org} and P{sub inorg}-O-P{sub org} bonds. Black-Right-Pointing-Pointer AFM indicated that the texture surface was changed by grafting. - Abstract: The nature of apatite-organic molecule interaction was the subject of many investigations. Grafting the organic molecule onto the inorganic support may precede through either formation of covalent bonds or ionic interaction between superficial hydroxyl on the apatite surface and organic functions. The hybrid materials obtained by functionalization of apatite surfaces with phosphonate moieties are of interest for their potential applications such in catalysis, chromatography and biomedical domain. In this scope, calcium hydroxyl and fluoroapatite (CaHAp and CaFAp) were prepared in the presence of the methyl phosphonic dichloride (MPO), by contact method in organic solvent at 25 Degree-Sign C for 2 days. The products are rigorously characterized by chemical analysis, infrared (IR), MAS-NMR spectroscopies, powder X-ray diffraction (XRD), atomic force microscopy (AFM) and specific surface area (SSA). The X-ray powder analysis showed that the crystallinity was sensibly affected by the presence of organic moieties. The IR spectroscopy showed new vibration modes appearing related to phosphonate groups essentially at 2930, 1315, 945, 764 and 514 cm{sup -1}. The {sup 31}P MAS NMR spectrum for hydroxy and fluoroapatite exhibits a single signal at 2.8 ppm. After reaction with (MPO) the spectra show the presence of new signals, assigned to the formation of organic-inorganic bond between the superficial hydroxyl groups of the apatite ({identical_to}CaOH) and ({identical_to}POH) and methyl phosphonic dichloride. The SSA decreases with increasing

  8. Synthesis and characterization of strontium molybdate doped with copper, cobalt and zinc for purposes photocatalytic; Sintese e caracterizacao do molibdato de estroncio dopado com cobre, cobalto e zinco para fins fotocataliticos

    Energy Technology Data Exchange (ETDEWEB)

    Dutra, F.B.; Silva, M.M.S.; Moriyama, A.L.L.; Souza, C.P., E-mail: faby_qui@hotmail.com [Universidade Federal do Rio Grande do Norte (LAMNRC/UFRN), Natal, RN (Brazil). Lab. de Materiais Nanoestruturados e Reatores Catalicos

    2016-07-01

    The broad concerns of contemporary society with environmental problems requires legislation and more effective techniques for wastewater treatment. In recent years, ceramic materials that have properties such as high melting points and high stability have been receiving great emphasis in several studies in particular heterogeneous photocatalysis, rapid and efficient method for the complete mineralization of contaminants. In this context, the present work deals with the synthesis and characterization of molybdate Strontium (SrMoO4) doped with copper, cobalt and zinc for the purpose of photocatalytic studies. The compounds were synthesized by complexation method EDTA / Citrate basic medium. The powders were characterized by Thermogravimetric Analysis (TG), X-Ray Diffraction (XRD), Particle size distribution by laser diffraction, Spectroscopy in the UV-Visible region, Energy Dispersive Spectroscopy (EDS) and Scanning Electron Microscopy (SEM), showing promising results as the crystalline phase of development and potential uses for the purpose of heterogeneous photocatalysis. (author)

  9. Investigation of adding fluoroapatite nanoparticles on compressive strength and corrosion behaviour of dental amalgams

    Directory of Open Access Journals (Sweden)

    Fahimeh Mirlohi

    2012-12-01

    Full Text Available In recent years, there have been many efforts to improve biological and biocompatibility features of amalgam. The aim of this research was investigating the effect of adding fluoroapatite (FA nanoparticles on compressive strength and corrosion behaviour of dental amalgam. An amalgam alloy powder was mixed with 1, 3 and 5 wt.% of FA nanoparticles to form composite powders. Compressive strength of the corresponding dental amalgam samples was measured on the first and seventh day after preparation and the corrosion behaviour was investigated by potentiodynamic polarization electrochemical test in 0.9 wt.% salt solution (physiologic serum. The results showed that the amalgam containing 1 wt.% FA nanoparticles has higher compressive strength then the pure amalgam and with increasing the FA content in amalgam to 3 and 5 wt.%, the compressive strength decreases. The results also indicated that the corrosion behaviour of the amalgam sample with 1 wt.% FA is similar to the corrosion behaviour of the original amalgam, while with increasing the weight percentage of fluorapatite, the corrosion resistance decreases. The results of this research showed that adding FA nanoparticles in amounts of up to 1 wt.% to amalgam alloy improve compressive strength, has no destructive effect on corrosion behaviour of the material and can increase its biocompatibility and biological activity.

  10. Effective improvement of interface modified strontium titanate based solid oxide fuel cell anodes by infiltration with nano-sized palladium and gadolinium-doped cerium oxide

    DEFF Research Database (Denmark)

    Abdul Jabbar, Mohammed Hussain; Høgh, Jens Valdemar Thorvald; Zhang, Wei

    2013-01-01

    The development of low temperature solid oxide fuel cell (SOFC) anodes by infiltration of Pd/Gd-doped cerium oxide (CGO) electrocatalysts in Nb-doped SrTiO3 (STN) backbones has been investigated. Modification of the electrode/electrolyte interface by thin layer of spin-coated CGO (400-500 nm) con...

  11. Study of effect of co-doping on CIE coordinates of strontium cerium oxide phosphor (Sr2CeO4)

    International Nuclear Information System (INIS)

    Zambare, Pradip Z.; Ahirrao, P.B.; Chaudhari, D.B.; Zambare, A.P.; Mahajan, O.H.

    2016-01-01

    The phosphors Sr 2 CeO 4 doped europium and gadolinium were synthesized by modified solid state diffusion method. From emission spectra, the CIE coordinates (x, y) of x% Eu 3+ and 0.5 %Gd 3+ doped Sr 2 CeO 4 phosphors was calculated. In present paper, we investigate luminescence properties and colorimetric study of Sr 2 CeO 4 doped 0.5% Gd 3+ , x% Eu 3+ . The phosphors Sr 2 CeO 4 doped europium and gadolinium were successfully synthesized by modified solid state diffusion method. X-ray diffraction (XRD) profile confirms the orthorhombic nature of Eu 3+ and 0.5% Gd 3+ doped Sr 2 CeO 4 phosphors. In addition, scanning electron Microscopy (SEM), Fourier-Transformation IR spectroscopy (FTIR), was also used to study the synthesized phosphors

  12. Fluoro-apatite surface composition in aqueous solution deduced from potentiometric, electrokinetic, and solubility measurements, and spectroscopic observations

    International Nuclear Information System (INIS)

    Chairat, C.; Oelkers, E.H.; Schott, J.; Lartigue, J.E.

    2007-01-01

    The surface chemistry of fluoro-apatite in aqueous solution was investigated using electrokinetic techniques, potentiometric titrations, solubility measurements, and attenuated total reflection infrared spectroscopy. All methods indicate the formation of Ca/F depleted, P enriched altered layer via exchange reactions between H + and Ca 2+ , and OH - and F - at the fluoro-apatite (FAP) surface. Observations suggest that this leached layer has a di-calcium phosphate (CaHPO 4 ) composition and that it controls the apparent solubility of FAP. Electrokinetic measurements yield an iso-electric point value of 1 ± 0.5 consistent with a negatively charged FAP surface at pH ≥ 1. In contrast, surface titrations give an apparent pH of point of zero charge of similar to 7.7, consistent with a positively charged surface at pH ≤ 7.7. These differences are shown to stem from proton consumption by both proton exchange and dissolution reactions at the FAP surface. After taking account for these effects, FAP surface charge is shown to be negative to at least pH 4 by surface titration analysis. (authors)

  13. Influence of La content on magnetic properties of Cu doped M-type strontium hexaferrite: Structural, magnetic, and Mossbauer spectroscopy study

    Science.gov (United States)

    Ghimire, M.; Yoon, S.; Wang, L.; Neupane, D.; Alam, J.; Mishra, S. R.

    2018-05-01

    The present study investigates the influence of Cu2+ and La3+-Cu2+ doping on the magnetic properties of Sr1-xLaxFe12-xCuxO19 (x = 0.0-0.5) hexaferrite (SrM) compounds. The samples were prepared via facile autocombustion technique followed by sintering. X-ray powder diffraction patterns show the formation of the pure phase of M-type hexaferrite for all x. Invariance in lattice parameters was observed with only Cu2+ substitution while lattice contraction along c-axis was observed with co-doping La3+-Cu2+ in SrM. The magnetic property of these compounds is explained based on Cu2+ occupancy in the absence and presence of La3+ in SrM magnetoplumbite structure. The Cu2+ doped SrFe12-xCuxO19 sample showed a monotonic decrease in Ms value while La3+-Cu2+ showed a noticeable increase in Ms value with x. Furthermore, while coercivity of Cu2+ doped SrM reduced with x, the coercivity of La3+-Cu2+ doped SrM showed a marked 12% increase in coercivity at x = 0.1 (Hc = 4391 Oe) from that of x = 0.0 (3918 Oe). Interestingly, Cu2+ doped SrM displayed invariance in Tc ∼ 458.6 °C with x, while La3+-Cu2+ doping reduced Tc by 5% from its x = 0 (Tc = 451.9 °C) to 429.6 °C. The room temperature Mossbauer spectral analysis confirmed a Cu2+ preference for the 12k site and its occupancy is observed to be influenced by the presence of La3+ ion at the Sr2+ site.

  14. Processing of strontium-doped lanthanum manganite suspensions for cathode production of the solid oxide fuel cell; Processamento das suspensoes de manganito de lantanio dopado com estroncio para fabricacao do catodo da celula a combustivel de oxido solido

    Energy Technology Data Exchange (ETDEWEB)

    Chiba, R.; Vargas, R.A.; Andreoli, M.; Seo, E.S.M. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Ciencia e Tecnologia de Materiais. Lab. de SOFC - Insumos e Componentes

    2008-07-01

    The ceramic material, strontium-doped lanthanum manganite (La{sub 0,85}Sr{sub 0,15}MnO{sub 3} - LSM), has been used as cathode in Solid Oxide Fuel Cells (SOFCs). The cathode attainment as component of the SOFCs has been studied for diverse routes of synthesis and thin films forming in Yttria-stabilized zirconia (ZrO{sub 2}/Y{sub 2}O{sub 3} - YSZ) electrolyte. In this work, the LSM was synthesized by the citrate technique and deposited in YSZ substrate using the forming technique wet powder spraying. Rheological studies of suspensions and chemical, physical and microstructural characterizations of LSM powders were made, aiming at the deposition for thin films formation until 50 mum. The half unit cells LSM/YSZ sintered were characterized by scanning electron microscopy, for verification of porosity and adherence. In this sense, this work is a contribution for production of porous cathode using the forming technique wet powder spraying in the SOFCs. (author)

  15. Effects of surrounding powder in sintering process on the properties of Sb and Mn- doped barium-strontium titanate PTCR ceramics

    Directory of Open Access Journals (Sweden)

    Pornsuda Bomlai

    2006-05-01

    Full Text Available In this research, the effects of surrounding powder used during sintering of Sb and Mn doped bariumstrontium titanate (BST ceramics were studied. The ceramic samples were prepared by a conventional mixed-oxide method and placed on different powders during sintering. Phase formation, microstructure and PTCR behavior of the samples were then observed. Microstructures and PTCR behavior varied with the type of surrounding powder, whereas the crystal structure did not change. The surrounding powder has more effects on the shape of the grain than on the size. The grain size of samples was in the range of 5-20 μm. The most uniform grain size and the highest increase of the ratio of ρmax/ρRT were found to be about 106 for samples which had been sintered on Sb-doped BST powder. This value was an order of magnitude greater than for samples sintered on a powder of the equivalent composition to that of the sample pellet.

  16. Modulation of electromagnetic and absorption properties in 18-26.5 GHz frequency range of strontium hexaferrites with doping of cobalt-zirconium

    Energy Technology Data Exchange (ETDEWEB)

    Pubby, Kunal; Narang, Sukhleen Bindra [Guru Nanak Dev University, Department of Electronics Technology, Amritsar (India); Kaur, Prabhjyot; Chawla, S.K. [Guru Nanak Dev University, Department of Chemistry, Centre for Advanced Studies-I, Amritsar (India)

    2017-05-15

    Hexaferrite nano-particles of stoichiometric composition Sr(CoZr){sub x}Fe{sub 12-2x}O{sub 19}, with x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0 were prepared using sol-gel auto-combustion route owing to its advantages such as low sintering temperature requirement, homogeneity and uniformity of grains. Tartaric acid as a fuel was utilized to complete the chemical reaction. The goal of this study is to analyse the effect of co-substitution of cobalt and zirconium on the electromagnetic and absorption properties of pure SrFe{sub 12}O{sub 19} hexaferrite. The properties were measured on the rectangular pellets of thickness 2.5 mm for K-frequency band using Vector Network Analyzer. The doping of Co-Zr has resulted in increase in real as well as imaginary parts of permittivity. The values of real permittivity lie in the range 3.6-7.0 for all the composition. The real part of permeability remains in range 0.7-1.6 in the studied frequency band for all the samples and shows slightly increasing trend with frequency. The maximum values of dielectric loss tangent peak (3.04) and magnetic loss tangent peak (2.34), among all the prepared compositions, have been observed for composition x = 0.2. Compositions with x = 0.6 and x = 0.0 also have high dielectric and magnetic loss peaks. Dielectric loss peaks are attributed to dielectric resonance and magnetic loss peaks are attributed to natural resonance. Experimentally determined reflection loss results show that all six compositions of prepared series have high values of absorption to propose them as single-layer absorbers in 18-26.5 GHz frequency range. The composition with x = 0.2 has maximum absorption capacity with reflection loss peak of -37.2 dB at 24.3 GHz frequency. The undoped composition also has high absorption peak (-25.46 dB), but -10 dB absorption bandwidth is minimum (2.2 GHz) out of the present series. Maximum absorption bandwidth is obtained for x = 1.0 (4.1 GHz). Other doped compositions also have high absorption bandwidth

  17. Modulation of electromagnetic and absorption properties in 18-26.5 GHz frequency range of strontium hexaferrites with doping of cobalt-zirconium

    Science.gov (United States)

    Pubby, Kunal; Narang, Sukhleen Bindra; Kaur, Prabhjyot; Chawla, S. K.

    2017-05-01

    Hexaferrite nano-particles of stoichiometric composition {{Sr}}{({{CoZr}})_x}{{F}}{{{e}}_{12 - 2x}}{{{O}}_{19}}, with x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0 were prepared using sol-gel auto-combustion route owing to its advantages such as low sintering temperature requirement, homogeneity and uniformity of grains. Tartaric acid as a fuel was utilized to complete the chemical reaction. The goal of this study is to analyse the effect of co-substitution of cobalt and zirconium on the electromagnetic and absorption properties of pure {{SrF}}{{{e}}_{12}}{{{O}}_{19}} hexaferrite. The properties were measured on the rectangular pellets of thickness 2.5 mm for K-frequency band using Vector Network Analyzer. The doping of Co-Zr has resulted in increase in real as well as imaginary parts of permittivity. The values of real permittivity lie in the range 3.6-7.0 for all the composition. The real part of permeability remains in range 0.7-1.6 in the studied frequency band for all the samples and shows slightly increasing trend with frequency. The maximum values of dielectric loss tangent peak (3.04) and magnetic loss tangent peak (2.34), among all the prepared compositions, have been observed for composition x = 0.2. Compositions with x = 0.6 and x = 0.0 also have high dielectric and magnetic loss peaks. Dielectric loss peaks are attributed to dielectric resonance and magnetic loss peaks are attributed to natural resonance. Experimentally determined reflection loss results show that all six compositions of prepared series have high values of absorption to propose them as single-layer absorbers in 18-26.5 GHz frequency range. The composition with x = 0.2 has maximum absorption capacity with reflection loss peak of -37.2 dB at 24.3 GHz frequency. The undoped composition also has high absorption peak (-25.46 dB), but -10 dB absorption bandwidth is minimum (2.2 GHz) out of the present series. Maximum absorption bandwidth is obtained for x = 1.0 (4.1 GHz). Other doped compositions also

  18. 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

  19. 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)

  20. Strontium-89 Chloride

    Science.gov (United States)

    ... may harm the fetus.notify any health care professional (especially other doctors) giving you treatment that you will be taking strontium-89 chloride.do not have any vaccinations (e.g., measles or flu shots) without talking to your doctor.

  1. Characterization of Lanthanum Ferric Cobaltite doped with Strontium (LSCF) films deposited by spray-pyrolysis for application as cathode in PaCOS-TI; Caracterizacao de filmes de CFLE depositados por spray-pirolise para utilizacao como catodo em PaCOS-TI

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, L.S.; Guimaraes, V.F.; Paes Junior, H.R. [Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF), Campos dos Goytacazes, RJ (Brazil). Lab. de Materiais Avancados], Emails: laryssadsa@yahoo.com.br, valtencyguimaraes@yahoo.com.br, herval@uenf.br

    2010-07-01

    The lanthanum ferric cobaltite doped with strontium (LSCF) is a ceramic material with the perovskite structure that stands out in the field of research for its use as cathode in solid oxide fuel cells at intermediate temperatures (IT-SOFC). The films were synthesized by spray-pyrolysis technique on 8% mol Yttria stabilized zirconia (YSZ) substrates. It was studied the influence of heat treatment temperatures (600-1000 deg C) on the properties of the films under the conditions of treatment during four hours. Samples were tested electrically by measuring the variation of electrical conductivity with temperature, structurally by X-ray diffraction (XRD) and morphologically by scanning electron microscopy (SEM). The films heat treated at 700 deg C for 4 hours showed better performance for application as cathode. (author)

  2. Accumulation of bone strontium measured by in vivo XRF in rats supplemented with strontium citrate and strontium ranelate.

    Science.gov (United States)

    Wohl, Gregory R; Chettle, David R; Pejović-Milić, Ana; Druchok, Cheryl; Webber, Colin E; Adachi, Jonathan D; Beattie, Karen A

    2013-01-01

    Strontium ranelate is an approved pharmacotherapy for osteoporosis in Europe and Australia, but not in Canada or the United States. Strontium citrate, an alternative strontium salt, however, is available for purchase over-the-counter as a nutritional supplement. The effects of strontium citrate on bone are largely unknown. The study's objectives were 1) to quantify bone strontium accumulation in female Sprague Dawley rats administered strontium citrate (N=7) and compare these levels to rats administered strontium ranelate (N=6) and vehicle (N=6) over 8 weeks, and 2) to verify an in vivo X-ray fluorescence spectroscopy (XRF) system for measurement of bone strontium in the rat. Daily doses of strontium citrate and strontium ranelate were determined with the intention to achieve equivalent amounts of elemental strontium. However, post-hoc analyses of each strontium compound conducted using energy dispersive spectrometry microanalysis revealed a higher elemental strontium concentration in strontium citrate than strontium ranelate. Bone strontium levels were measured at baseline and 8 weeks follow-up using a unique in vivo XRF technique previously used in humans. XRF measurements were validated against ex vivo measurements of bone strontium using inductively coupled plasma mass spectrometry. Weight gain in rats in all three groups was equivalent over the study duration. A two-way ANOVA was conducted to compare bone strontium levels amongst the three groups. Bone strontium levels in rats administered strontium citrate were significantly greater (p<0.05) than rats administered strontium ranelate and vehicle. ANCOVA analyses were performed with Sr dose as a covariate to account for differences in strontium dosing. The ANCOVA revealed differences in bone strontium levels between the strontium groups were not significant, but that bone strontium levels were still very significantly greater than vehicle. Copyright © 2012 Elsevier Inc. All rights reserved.

  3. Synthesis and characterization of nickel oxide doped barium strontium titanate ceramics Síntese e caracterização de cerâmicas de titanato de estrôncio e bário dopado com óxido de níquel

    Directory of Open Access Journals (Sweden)

    M. Banerjee

    2012-03-01

    Full Text Available Barium strontium titanate (BST ceramics (Ba0.6Sr0.4TiO3 were synthesized by solid state sintering using barium carbonate, strontium carbonate and rutile as the precursor materials. The samples were doped with nickel oxide in different proportions. Different phases present in the sintered samples were determined from X-ray diffraction investigation and the distribution of different phases in the microstructure was assessed from scanning electron microscopy study. It was observed that the dielectric properties of BST were modified significantly with nickel oxide doping. These ceramics held promise for applications in tuned circuits.Cerâmicas de titanato de bário e estrôncio (TBS (Ba0,6Sr0,4TiO3 foram sintetizadas por sinterização do estado sólido usando carbonato de bário, carbonato de estrôncio e rutilo como materiais precursores. As amostras foram dopadas com diferentes proporções de óxido de níquel. Diferentes fases presentes nas amostras sinterizadas foram determinadas por difração de raios X e a distribuição de diferentes fases na microestrutura foi avaliada por microscopia eletrônica de varredura. Foi observado que as propriedades dielétricas do TBS foram modificadas significativamente com a dopagem do óxido de níquel. Essas cerâmicas são promissoras para aplicação em dispositivos.

  4. Strontium and Osteoporosis

    Directory of Open Access Journals (Sweden)

    Ferda Özdemir

    2004-06-01

    Full Text Available Osteoporosis (OP is a condition of bone fragility resulting from micro-architectural deterioration and decreased bone mass. OP depends on the interaction of genetic, hormonal, environmental and nutritional factors. Chronically low intakes of vitamin D and possibly magnesium, zinc, fluoride and vitamins K, B12, B6 and folic acid may predispose to osteoporosis. Minerals and oligo elements affect the process of formation and resorption by direct and indirect effects on the bone cells. Strontium is a oligo element, which is found widespread in the nature, and suggested for the treatment of osteoporosis. Strontium’s effection the bones depend on dose. High intake of Sr damage bones mineralization. When it is taken at low dose, for a long time, bone resorption is decreased but formation is increased. Trabecular and cortical bones both are increased with strontium.

  5. 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.)

  6. Fission products analysis. Strontium 89 and strontium 90 radiometric determination

    International Nuclear Information System (INIS)

    Anon.

    Determination of strontium 89 et 90 in nitric solutions of fission products, suitable for strontium content giving a nuclear activity of at least 10 -5 microcurie/ml. Calcium, barium, yttrium and rare earths are eliminated before beta counting with and without threshold [fr

  7. Substantial enhancement in intrinsic coercivity on M-type strontium hexaferrite through the increase in magneto-crystalline anisotropy by co-doping of group-V and alkali elements

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Kyunghan, E-mail: kyunghan.ahn@samsung.com; Ryu, Byungki; Korolev, Dmitry; Jae Kang, Young [Materials R and D Center, Samsung Advanced Institute of Technology, Yongin-si, Gyeonggi-do 446-712 (Korea, Republic of)

    2013-12-09

    The effect of d{sup 1} impurity doping in Sr-hexaferrite (SrM) on the magnetic anisotropy is investigated. First-principles calculations revealed that group-V elements (V, Nb) are stabilized with co-doping of alkali elements. Na{sup 1+}/K{sup 1+} doping at Sr{sup 2+}-site is found to be critical to form the d{sup 1} impurities at Fe-site. Experimentally, Na–V doped SrM shows the intrinsic coercivity of ∼5.4 kOe, which is ∼300% enhancement compared to undoped SrM and comparable value to La–Co co-doped SrM. Finally, the spin-orbit coupling from non-vanishing angular momentum of d{sup 1} impurity in SrM should be a main factor for such a substantial improvement of intrinsic coercivity.

  8. Barium iodide and strontium iodide crystals andd scintillators implementing the same

    Science.gov (United States)

    Payne, Stephen A; Cherepy, Nerine J; Hull, Giulia E; Drobshoff, Alexander D; Burger, Arnold

    2013-11-12

    In one embodiment, a material comprises a crystal comprising strontium iodide providing at least 50,000 photons per MeV. A scintillator radiation detector according to another embodiment includes a scintillator optic comprising europium-doped strontium iodide providing at least 50,000 photons per MeV. A scintillator radiation detector in yet another embodiment includes a scintillator optic comprising SrI.sub.2 and BaI.sub.2, wherein a ratio of SrI.sub.2 to BaI.sub.2 is in a range of between 0:1 A method for manufacturing a crystal suitable for use in a scintillator includes mixing strontium iodide-containing crystals with a source of Eu.sup.2+, heating the mixture above a melting point of the strontium iodide-containing crystals, and cooling the heated mixture near the seed crystal for growing a crystal. Additional materials, systems, and methods are presented.

  9. 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)

  10. Electrochemically assisted deposition of strontium modified magnesium phosphate on titanium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Meininger, M. [Department for Functional Materials in Medicine and Dentistry, University of Würzburg, Pleicherwall 2, D-97070 Würzburg (Germany); Wolf-Brandstetter, C. [Max Bergmann Center for Biomaterials, Technical University of Dresden, Budapester Straße 27, D-01069 Dresden (Germany); Zerweck, J.; Wenninger, F.; Gbureck, U.; Groll, J. [Department for Functional Materials in Medicine and Dentistry, University of Würzburg, Pleicherwall 2, D-97070 Würzburg (Germany); Moseke, C., E-mail: claus.moseke@fmz.uni-wuerzburg.de [Department for Functional Materials in Medicine and Dentistry, University of Würzburg, Pleicherwall 2, D-97070 Würzburg (Germany)

    2016-10-01

    Electrochemically assisted deposition was utilized to produce ceramic coatings on the basis of magnesium ammonium phosphate (struvite) on corundum-blasted titanium surfaces. By the addition of defined concentrations of strontium nitrate to the coating electrolyte Sr{sup 2+} ions were successfully incorporated into the struvite matrix. By variation of deposition parameters it was possible to fabricate coatings with different kinetics of Sr{sup 2+} into physiological media, whereas the release of therapeutically relevant strontium doses could be sustained over several weeks. Morphological and crystallographic examinations of the immersed coatings revealed that the degradation of struvite and the release of Sr{sup 2+} ions were accompanied by a transformation of the coating to a calcium phosphate based phase similar to low-crystalline hydroxyapatite. These findings showed that strontium doped struvite coatings may provide a promising degradable coating system for the local application of strontium or other biologically active metal ions in the implant–bone interface. - Highlights: • Sr-doped struvite coatings have been deposited on titanium by electrochemically assisted deposition. • Sr content can be adjusted by means of process time, current density and pulse mode. • Sr-doped coatings release therapeutically relevant Sr doses in physiological media for several weeks. • During immersion in physiological media Sr-doped struvite coatings transform into a low crystalline calcium phosphate phase.

  11. Electrochemically assisted deposition of strontium modified magnesium phosphate on titanium surfaces

    International Nuclear Information System (INIS)

    Meininger, M.; Wolf-Brandstetter, C.; Zerweck, J.; Wenninger, F.; Gbureck, U.; Groll, J.; Moseke, C.

    2016-01-01

    Electrochemically assisted deposition was utilized to produce ceramic coatings on the basis of magnesium ammonium phosphate (struvite) on corundum-blasted titanium surfaces. By the addition of defined concentrations of strontium nitrate to the coating electrolyte Sr 2+ ions were successfully incorporated into the struvite matrix. By variation of deposition parameters it was possible to fabricate coatings with different kinetics of Sr 2+ into physiological media, whereas the release of therapeutically relevant strontium doses could be sustained over several weeks. Morphological and crystallographic examinations of the immersed coatings revealed that the degradation of struvite and the release of Sr 2+ ions were accompanied by a transformation of the coating to a calcium phosphate based phase similar to low-crystalline hydroxyapatite. These findings showed that strontium doped struvite coatings may provide a promising degradable coating system for the local application of strontium or other biologically active metal ions in the implant–bone interface. - Highlights: • Sr-doped struvite coatings have been deposited on titanium by electrochemically assisted deposition. • Sr content can be adjusted by means of process time, current density and pulse mode. • Sr-doped coatings release therapeutically relevant Sr doses in physiological media for several weeks. • During immersion in physiological media Sr-doped struvite coatings transform into a low crystalline calcium phosphate phase.

  12. Strontium titanate resistance modulation by ferroelectric field effect

    CERN Document Server

    Marré, D; Bellingeri, E; Pallecchi, I; Pellegrino, L; Siri, A S

    2003-01-01

    Among perovskite oxides strontium titanate (STO) SrTiO sub 3 undergoes a metal-insulator transition at very low carrier concentration and exhibits high mobility values at low temperature. We exploited such electrical properties and the structural compatibility of perovskite oxide materials in realizing ferroelectric field effect epitaxial heterostructures. By pulsed laser deposition, we grew patterned field effect devices, consisting of lanthanum doped STO and Pb(Zr,Ti)O sub 3. Such devices showed a resistance modulation up to 20%, consistent with geometrical parameters and carrier concentration of the semiconducting channel.

  13. 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.

  14. 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.

  15. 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

    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......Four strontium(II) salts with organic acids have been studied. Poly[diaquadi--ibuprofenato-strontium(II)] or poly[diaquabis[-2-(4-isobutylphenyl)propionato]strontium(II)], [Sr(C13H17O2)2(H2O)2]n, crystallizes with eight-coordinated Sr atoms. The coordination polyhedra are interconnected by edge...... polyhedral ascorbate chains. These chains are tied together by a three-dimensional hydrogen-bonding network. Poly[aqua--2-oxidobenzoato-strontium(II)], [Sr(C7H4O3)(H2O)]n, crystallizes with eight-coordinated Sr atoms. The polyhedra are interconnected by face- and edge-sharing into layers. These layers...

  16. Instrument Development and Gamma Spectroscopy with Strontium Iodide

    Energy Technology Data Exchange (ETDEWEB)

    Cherepy, Nerine [Lawrence Livermore National Laboratory (LLNL); Payne, Stephen A. [Lawrence Livermore National Laboratory (LLNL); Sturm, Benjamin [Lawrence Livermore National Laboratory (LLNL); Drury, Owen [Lawrence Livermore National Laboratory (LLNL); O’Neal, S P [Lawrence Livermore National Laboratory (LLNL); Thelin, P [Lawrence Livermore National Laboratory (LLNL); Shah, Kanai [Radiation Monitoring Devices, Watertown, MA; Hawrami, Rastgo [Fisk University, Nashville, TN; Momayezi, M [Bridgeport Instruments, Austin TX; Hurst, B. [Bridgeport Instruments, Austin TX; Wiggen, B. [Fisk University, Nashville, TN; Bhattacharya, P. [Fisk University, Nashville, TN; Burger, Arnold [Fisk University, Nashville, TN; Boatner, Lynn A [ORNL; Ramey, Joanne Oxendine [ORNL

    2012-01-01

    Development of the Europium-doped Strontium Iodide scintillator, SrI2(Eu), involves advances in crystal growth, optics and readout methodology for prototype detectors. We have demonstrated energy resolution of 3% at 662 keV for a 26 cm3 SrI2(Eu) crystal, which is comparable to the performance obtained with Cerium-doped Lanthanum Bromide of equivalent size. Compared to standard analog readout, use of a digital readout method allows improved energy resolution to be obtained with large-volume SrI2(Eu) crystals. Comparative gamma spectra acquired with LaBr3(Ce) and NaI(Tl) quantitatively depict the value of the high resolution and low intrinsic radioactivity of SrI2(Eu) in discriminating closely spaced gamma lines for radioisotope identification applications.

  17. Effects of focused ion beam milling on electron backscatter diffraction patterns in strontium titanate and stabilized zirconia

    DEFF Research Database (Denmark)

    Saowadee, Nath; Agersted, Karsten; Bowen, Jacob R.

    2012-01-01

    This study investigates the effect of focused ion beam (FIB) current and accelerating voltage on electron backscatter diffraction pattern quality of yttria‐stabilized zirconia (YSZ) and Nb‐doped strontium titanate (STN) to optimize data quality and acquisition time for 3D‐EBSD experiments by FIB...

  18. Laser sintering of doped strontium aluminate via modified sol-gel for use as a ceramic pigment; Sinterizacao a laser do aluminato de estroncio dopado via sol-gel modificado para aplicacao como pigmento ceramico

    Energy Technology Data Exchange (ETDEWEB)

    Soares, F.M. dos S.; Valerio, M.E.G. [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil)

    2017-01-15

    Powder of Dy{sup 3+} co-doped SrAl{sub 2}O{sub 4} :Eu{sup 3+} was produced via proteic sol-gel method, a modified sol-gel route which allows the formation of oxides at lower temperatures than other methods. CO{sub 2} laser sintering was used as a method for heat treatment, effective in reducing trivalent europium ions in doped samples. Thermal analysis of the precursors, performed by TG and DTA, revealed that the crystallization of SrAl{sub 2}O{sub 4} phase occurred at approximately 1060 °C. X-ray diffraction showed that the samples, before and after sintering, had monoclinic and hexagonal phases formation. DLS technique revealed the presence of nanosized and micrometric particles, and particle agglomerates, confirmed by SEM images. Micrographs of the fracture surface of a sintered pellet revealed a high degree of densification caused by heat treatment. Photoluminescence measurements showed that the samples after synthesis and before heat treatment with laser had reddish emission, composed of characteristic narrow emission lines from Eu{sup 3+} and more intense emission when the samples were excited at 265 nm. The laser treatment promoted the reduction of Eu{sup 3+} to Eu{sup 2+} and this effect was confirmed by the presence of a wide emission band in the green region of the spectrum with a maximum emission obtained after excitation at 350 nm. The luminescent decay time of the thermally treated sample was approximately 100 min. Via XRF measurements of acquired frit and DTA and TG of the frit, pigment and mixtures of both, it was noticed good compatibility in terms of thermal processes, that indicated that the pigment has a potential to be used in ceramic tiles. (author)

  19. Study of retention properties of fluoro-apatite carbonate relative to Ni(II), Am(III) and Th(IV)

    International Nuclear Information System (INIS)

    Perrone, Jane

    1999-01-01

    Apatite minerals and particularly the carbonated species (francolites), are characterized by their chemical and geological stability and also by their capacity to retain durably a large number of elements. Therefore, they should be able to improve the retention properties of the engineered barriers of a deep geological nuclear waste repository. But there is a wide variety of francolites, so we focused our study on a synthetic carbonate fluoro-apatite of formula: Ca 10 (PO 4 ) 5 (CO 3 )(F,OH) 3 and on a natural apatite. We first studied their solubility which is an important criterion for the choice of the materials. A particular attention was also paid to the determination of their surface characteristics and to the study of the radionuclide/solution interactions. Sorption experiments have been performed for the three radionuclides and the influence of various parameters has been investigated. The modelling of the sorption isotherms with surface complexation models leads us to estimate the values of the constants associated to the equilibria under consideration. We have also demonstrated that the phosphate ions of the solution participate to the immobilization of americium as the AmPO 4 ,xH 2 O compound. Both apatites show high retention levels for the actinides: the sorption is quite total over all the pH range studied and the Kd values are close to 10 4 m 3 kg -1 . Consequently, the use of apatites could be considered as a specific solution for the immobilisation of heavy elements, specially actinides. Moreover, the results indicate that high amounts of carbonates and impurities do not alter the retention properties of francolites. This bears out the feasibility of the use of natural apatites as additives for the engineered barrier materials. (author)

  20. Hydrogen Solubility in Pr-doped and Un-doped YSZ for One Chamber Fuel Cell

    DEFF Research Database (Denmark)

    Bay, Lasse; Horita, T.; Sakai, N.

    1998-01-01

    Yttria-stabilised zirconia electrolytes (YSZ and Pr-doped YSZ) and yttria-doped strontium cerate (SYC) were tested in a one chamber fuel cell fed with a mixture of methane and air at 1223 K. The obtained performances were 4 mW cm(-2), 3 mW cm(-2), 2.5 mW cm(-2), and 0.15 mW cm(-2) for SYC, 1.8 mo...

  1. Influence of milling and calcination steps on phase assemblage of strontium and magnesium doped lanthanum gallate; Influencia das etapas de calcinacao e moagem na composicao de fases do galato de lantanio contendo estroncio e magnesio

    Energy Technology Data Exchange (ETDEWEB)

    Reis, S.L.; Muccillo, E.N.S., E-mail: shirley.reis@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    Sr- and Mg- doped lanthanum gallate (La{sub 1-x}Sr{sub x}Ga{sub 1-y}Mg{sub y}O{sub 3δ}) is one of the most promising solid electrolyte and electrode components for solid oxide fuel cells operating at low-temperature, due to its high electric conductivity and stability over a wide range of oxygen partial pressures. In this work, La{sub 0,9}Sr{sub 0,1}Ga{sub 0,8}Mg{sub 0,2}O{sub 2,8}5 was prepared by different solid state reaction routes. The main purpose is to determine a suitable processing route that enables high sintering density along with free or negligible secondary phase contents. Phase analysis was carried out by X-ray diffraction and the sintered density was obtained from the water immersion method. Results on X-ray diffraction showed negligible secondary phases formed even for sintering at relatively high temperatures. The apparent density obtained was higher than 95% of the theoretical value for all routes. The main difference observed among the studied routes is the final contents of secondary phases. (author)

  2. 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...

  3. 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...... of strontium clusters. Ionization of small strontium clusters results in the alteration of the magic numbers. The strong dependence of the DOS spectra on details of ionic structure allows one to perform a reliable geometry identification of strontium clusters....

  4. 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

  5. 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.

  6. Photoexcited-carrier transport in barium strontium titanate/strontium titanate heterostructures

    Science.gov (United States)

    Yan, H.; Wang, J. Y.; Zhang, Z. T.; Yang, B.; Chen, C. L.; Jin, K. X.

    2017-09-01

    Photoexcited-carrier transport properties at the surface and the interface of barium strontium titanate/strontium titanate heterostructures are reported. Under a 365 nm light irradiation, the surfaces of barium strontium titanate films exhibit a metal-to-insulator transition, while the interfaces favor the metallic conduction with increasing temperatures. By analyzing, we consider that these results might be attributed to the intrinsic features of strontium titanate and the polarization state of barium strontium titanate films under the irradiation. Our results would contribute to further understanding of the photocarrier effect at the interface and demonstrate great potential applications in optoelectronic devices of all-oxide heterostructures.

  7. Magnetic properties of Sn-Mg substituted strontium hexaferrite nanoparticles synthesized via coprecipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Davoodi, A. [Department of Materials Science and Engineering, School of Engineering, Shiraz University, Shiraz (Iran, Islamic Republic of); Hashemi, B., E-mail: hashemib@shirazu.ac.ir [Department of Materials Science and Engineering, School of Engineering, Shiraz University, Shiraz (Iran, Islamic Republic of)

    2011-05-12

    Highlights: > Decreasing mean particle size from 82 to 56 nm with increasing the Sn-Mg proportion from x = 0.0 to x = 0.8. > Reducing the coercivity from 4728.9 to 1455.5 Oe and increasing the saturation magnetization from 51.34 to 65.49 emu/g with increasing the Sn-Mg from x = 0.0 to x = 0.8. > The higher effective electromagnetic absorption properties for strontium hexaferrite-acrylic resin composites which contained doped hexaferrite with x = 0.8. - Abstract: Nanoparticles of Sn-Mg substituted strontium hexaferrite with the composition of SrFe{sub 12-x}(Sn{sub 0.5} Mg{sub 0.5}){sub x}O{sub 19} (x = 0.0-1.0) were synthesized by chemical coprecipitation method. Deionized water/ethanol (50/50) was used as the solvent. The single phase strontium hexaferrites were obtained at pH 13 and Fe{sup 3+}/Sr{sup 2+} molar ratio of 9 after calcination at 800 deg. C. The mean particle size of samples was decreased from 82 to 56 nm with increasing the Sn-Mg content from x = 0.0 to x = 0.8. The effect of Sn-Mg substitution on magnetic properties of hexaferrites was studied using vibrating-sample magnetometer. It was found that increasing the Sn-Mg from x = 0.0 to x = 0.8 reduced the coercivity from 4728.9 to 1455.5 Oe and increased the saturation magnetization from 51.34 to 65.49 emu/g. A vector network analyzer was used to investigate the microwave absorption properties. According to microwave measurements, doped strontium hexaferrite composites had much more effective electromagnetic absorption properties than undoped strontium hexaferrite composite.

  8. An epitaxial transparent conducting perovskite oxide: double-doped SrTiO3

    NARCIS (Netherlands)

    Ravichandran, Jayakanth; Siemons, W.; Heijmerikx, Herman; Huijben, Mark; Majumdar, Arun; Ramesh, Ramamoorthy

    2010-01-01

    Epitaxial thin films of strontium titanate doped with different concentrations of lanthanum and oxygen vacancies were grown on LSAT substrates by pulsed laser deposition technique. Films grown with 5−15% La doping and a critical growth pressure of 1−10 mTorr showed high transparency (>70−95%) in the

  9. 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)

  10. Persistent photoconductivity in strontium titanate.

    Science.gov (United States)

    Tarun, Marianne C; Selim, Farida A; McCluskey, Matthew D

    2013-11-01

    Persistent photoconductivity was observed in strontium titanate (SrTiO(3)) single crystals. When exposed to sub-bandgap light (2.9 eV or higher) at room temperature, the free-electron concentration increases by over 2 orders of magnitude. After the light is turned off, the enhanced conductivity persists for several days, with negligible decay. From positron lifetime measurements, the persistent photoconductivity is attributed to the excitation of an electron from a titanium vacancy defect into the conduction band, with a very low recapture rate.

  11. EPR of Mn2+ in strontium tartrate trihydrate single crystals

    International Nuclear Information System (INIS)

    Korkmaz, M.; Aktas, B.

    1985-01-01

    Electron paramagnetic resonance spectra of Mn 2+ doped in single crystals of strontium tartrate trihydrate grown by a diffusion technique are investigated at room temperature. Mn 2+ enters the lattice substitutionally and is trapped at two magnetically equivalent but crystallographically inequivalent sites. The EPR measurements give the following values for the spin-Hamiltonian parameters: g/sub x/(= g/sub y/) = 1.9781, g/sub z/ = 2.0012, A/sub x/(= A/sub y/) = -94.9 x 10 -4 T, A/sub z/ = -96.2 x 10 -4 T, B 0 2 (= D/3) = +160.9 x 10 -4 T, B 2 2 (= E) = +101.2 x 10 -4 T, B 0 4 = +0.013 x 10 -4 T, and B 2 4 = +0.088 x 10 -4 T. (author)

  12. Thermal Transport and Phonon Hydrodynamics in Strontium Titanate

    Science.gov (United States)

    Martelli, Valentina; Jiménez, Julio Larrea; Continentino, Mucio; Baggio-Saitovitch, Elisa; Behnia, Kamran

    2018-03-01

    We present a study of thermal conductivity, κ , in undoped and doped strontium titanate in a wide temperature range (2-400 K) and detecting different regimes of heat flow. In undoped SrTiO3 , κ evolves faster than cubic with temperature below its peak and in a narrow temperature window. Such behavior, previously observed in a handful of solids, has been attributed to a Poiseuille flow of phonons, expected to arise when momentum-conserving scattering events outweigh momentum-degrading ones. The effect disappears in the presence of dopants. In SrTi1 -xNbx O3 , a significant reduction in lattice thermal conductivity starts below the temperature at which the average inter-dopant distance and the thermal wavelength of acoustic phonons become comparable. In the high-temperature regime, thermal diffusivity becomes proportional to the inverse of temperature, with a prefactor set by sound velocity and Planckian time (τp=(ℏ/kBT ) ).

  13. Study of retention properties of fluoro-apatite carbonate relative to Ni(II), Am(III) and Th(IV); Etude des proprietes de retention des carbonate fluoroapatites vis-a-vis de Ni(II), Am(III) et Th(IV)

    Energy Technology Data Exchange (ETDEWEB)

    Perrone, Jane [Inst. de Physique Nucleaire, Paris-11 Univ., 91 - Orsay (France)

    1999-07-12

    Apatite minerals and particularly the carbonated species (francolites), are characterized by their chemical and geological stability and also by their capacity to retain durably a large number of elements. Therefore, they should be able to improve the retention properties of the engineered barriers of a deep geological nuclear waste repository. But there is a wide variety of francolites, so we focused our study on a synthetic carbonate fluoro-apatite of formula: Ca{sub 10}(PO{sub 4}){sub 5}(CO{sub 3})(F,OH){sub 3} and on a natural apatite. We first studied their solubility which is an important criterion for the choice of the materials. A particular attention was also paid to the determination of their surface characteristics and to the study of the radionuclide/solution interactions. Sorption experiments have been performed for the three radionuclides and the influence of various parameters has been investigated. The modelling of the sorption isotherms with surface complexation models leads us to estimate the values of the constants associated to the equilibria under consideration. We have also demonstrated that the phosphate ions of the solution participate to the immobilization of americium as the AmPO{sub 4},xH{sub 2}O compound. Both apatites show high retention levels for the actinides: the sorption is quite total over all the pH range studied and the Kd values are close to 10{sup 4} m{sup 3} kg{sup -1}. Consequently, the use of apatites could be considered as a specific solution for the immobilisation of heavy elements, specially actinides. Moreover, the results indicate that high amounts of carbonates and impurities do not alter the retention properties of francolites. This bears out the feasibility of the use of natural apatites as additives for the engineered barrier materials. (author)

  14. Rapid methods for strontium determination in environmental samples

    International Nuclear Information System (INIS)

    Buchtela, Karl

    1995-01-01

    The simultaneous determination of strontium-90 and strontium-89 is usually done by separation of yttrium-90 after a suitable time for the growth of yttrium-90. Investigations are of interest to try a yttrium-90 measurement without separation by observing the increase of activity of the strontium sample due to the production and decay of the daughter nuclide yttrium-90. Also it can be tried to use liquid scintillation spectroscopy to discriminate strontium-89 (1.46 MeV) from strontium-90 (0.55 MeV) immediately after the strontium precipitation. Until now all these determinations are only possible if the strontium-90 activity is not too low compared with the the strontium-89 content of the sample. Unfortunately regarding this possibility of determination but fortunately from the point of view of radiation protection immediately after a nuclear accident in most cases the activity of strontium-90 is much lower than that of strontium-89. Liquid scintillation spectroscopy does not give reliable results for low strontium-90 activity if a high strontium-89 activity is observed in a sample. The growth of yttrium-90 in a sample of strontium-89/90 will increase the total activity. After a suitable period of time this increase might be sufficiently high to provide reliable information about the strontium-90 content. Due to statistics no reliable information will be provided for samples with an excess of strontium-89. If the strontium-89 activity is 20 times higher than the strontium-90 activity, no reliable information can be obtained, if it is 5 times higher, it is possible to provide a quantitative information about the growth of yttrium-90 after 36 hours, and if twice the activity of strontium-89 compared to the strontium-90 were observed, there would be no difficulties for the simultaneous determination of both radionuclides. Dealing with the situation of high strontium-89 contribution an yttrium separation probably is unavoidable

  15. Strontium Iodide Radiation Instrumentation (SIRI)

    Science.gov (United States)

    Mitchell, Lee J.; Phlips, Bernard F.; Woolf, Richard S.; Finne, Theodore T.; Johnson, W. Neil; Jackson, Emily G.

    2017-08-01

    The Strontium Iodide Radiation Instrumentation (SIRI) is designed to space-qualify new gamma-ray detector technology for space-based astrophysical and defense applications. This new technology offers improved energy resolution, lower power consumption and reduced size compared to similar systems. The SIRI instrument consists of a single europiumdoped strontium iodide (SrI2:Eu) scintillation detector. The crystal has an energy resolution of 3% at 662 keV compared to the 6.5% of traditional sodium iodide and was developed for terrestrial-based weapons of mass destruction (WMD) detection. SIRI's objective is to study the internal activation of the SrI2:Eu material and measure the performance of the silicon photomultiplier (SiPM) readouts over a 1-year mission. The combined detector and readout measure the gammaray spectrum over the energy range of 0.04 - 4 MeV. The SIRI mission payoff is a space-qualified compact, highsensitivity gamma-ray spectrometer with improved energy resolution relative to previous sensors. Scientific applications in solar physics and astrophysics include solar flares, Gamma Ray Bursts, novae, supernovae, and the synthesis of the elements. Department of Defense (DoD) and security applications are also possible. Construction of the SIRI instrument has been completed, and it is currently awaiting integration onto the spacecraft. The expected launch date is May 2018 onboard STPSat-5. This work discusses the objectives, design details and the STPSat-5 mission concept of operations of the SIRI spectrometer.

  16. Strontium-90 determination in environmental samples

    International Nuclear Information System (INIS)

    Figueira, Rubens Cesar Lopes.

    1994-01-01

    The study to establish radiochemical methods for strontium-90 analysis in environmental samples, such as water, seawater, fish, marina sediment, soil and air filters is presented. The analyses were divided in the following steps: leaching of strontium-90 from fish, marine sediment, soil and air filter samples with nitric acid and hydrogen peroxide; strontium-90 preconcentration in seawater by using sodium carbonate and from other matrices sulfuric acid; magnesium separation in seawater matrix with ammonium chloride; separation of interferents elements, time to reach radioactive equilibrium between strontium-90 and yttrium-90; separation of strontium-90 from yttrium-90, by precipitation with hydroxide and conversion to oxalate, and beta counting of yttrium-90 in Geiger-Mueller detector with low background radiation and high counting efficiency. The methodology developed for strontium-90 analysis in environmental samples, presented a strontium-90 recuperation of about 90%, for water, 66% for seawater and higher than 80% for fish bones and muscles, marine sediment, soil and air filter samples. (author). 78 refs., 6 figs., 21 tabs

  17. 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....

  18. 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

  19. 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

  20. 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, ammoni...

  1. Microstructure and magnetic microstructure of La + Co doped strontium hexaferrites

    Energy Technology Data Exchange (ETDEWEB)

    Pang Zhiyong, E-mail: pang@sdu.edu.c [School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Shanda South Road 27, Jinan, Shandong 250100 (China); Zhang Xijian [School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Shanda South Road 27, Jinan, Shandong 250100 (China); Ding Boming; Bao Daxin [Central Research Institute, HENGDIAN DMEGC MAGNETICS Co., LTD, Dongyang, Zhejiang 322118 (China); Han Baoshan [Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China)

    2010-03-04

    After being cut, carefully ground, meticulously polished and properly eroded, the microstructure and magnetic microstructure of La{sub 0.3}Sr{sub 0.7}Fe{sub 11.8}Co{sub 0.2}O{sub 19} hexaferrites were investigated by using magnetic force microscopy. The shapes of a large amount of the La{sub 0.3}Sr{sub 0.7}Fe{sub 11.8}Co{sub 0.2}O{sub 19} grains were determined to be mostly irregular flat columns. The shape anisotropy of the hexaferrite grains can be explained by an abnormal grain growth process occurs for La + Co-containing hexaferrite powders. The magnetizations mainly align parallel or anti-parallel to the direction of oriented magnetic field. The magnetic domain sizes are in the same order of magnitude with the grain sizes. No complex domain structures like corrugation and spike were observed. Micromagnetic simulations were also performed to help analyzing the magnetic microstructure.

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

    Indian Academy of Sciences (India)

    TECS

    Kurtz and Perry powder second harmonic generation. (SHG) method was used to sense NLO behaviour of crystals. To measure SHG efficiency, samples were derived from the crystals grown with full morphology, which ensures homogeneity of the material. The input power of the laser beam was measured to be 5⋅7 ...

  3. Minerals yearbook, 1991: Strontium. Annual report

    Energy Technology Data Exchange (ETDEWEB)

    Ober, J.A.

    1992-12-01

    The sole U.S. strontium carbonate producer voluntarily provided domestic production data to the U.S. Bureau of Mines. Production and stock data, however, were withheld from publication to avoid disclosing company proprietary data. The Bureau also estimated the distribution of strontium compounds by end use. Of the 10 operations to which a survey request was sent, 8 responded. The information collected from the survey represents almost 100% of the end-use data shown in table 2.

  4. 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

  5. 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)

  6. 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)

  7. 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

  8. Surface adsorption in strontium chloride ammines.

    Science.gov (United States)

    Ammitzbóll, Andreas L; Lysgaard, Steen; Klukowska, Agata; Vegge, Tejs; Quaade, Ulrich J

    2013-04-28

    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 kJ∕mol. A simple kinetic model is proposed that accounts for the absorption of ammonia through the adsorbed state.

  9. 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

  10. 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.

  11. 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

  12. Determination of strontium and lanthanum zirconates in YPSZ-LSM mixtures for SOFC

    Energy Technology Data Exchange (ETDEWEB)

    Cortes-Escobedo, Claudia Alicia [Centro de Investigacion e Innovacion Tecnologica del IPN, Cda. Cecati s/n, Col. Sta. Catarina, CP 02250, Azcapotzalco, D.F. (Mexico); Munoz-Saldana, Juan [Centro de Investigacion y Estudios Avanzados del IPN, Unidad Queretaro, pdo. Postal 1-798, 76001 Queretaro, Qro. (Mexico); Bolarin-Miro, Ana Maria; Sanchez-de Jesus, Felix [Centro de Investigaciones en Materiales y Metalurgia, Universidad Autonoma del Estado de Hidalgo, CU, Carr. Pachuca-Tulancingo Km. 4.5, Mineral de la Reforma, CP 42184, Hidalgo (Mexico)

    2008-05-15

    Mixtures of 3% yttria- and partially-stabilized zirconia with LSM{sub x} (strontium-doped lanthanum manganite, x = 0, 0.15 and 0.2) were prepared and heat treated at temperatures between 1000 and 1300 C to recreate the cathode-electrolyte interface interactions taking place during preparation and operation of solid oxide fuel cells (SOFC). Such interactions include the formation of La{sub 2}Zr{sub 2}O{sub 7} and SrZrO{sub 3}, which are undesirable for SOFC. The effect of the manganese oxidation number on the mechanosynthesis of LSM during zirconate formation is also discussed. A quantitative analysis of zirconate formation by X-ray diffraction and Rietveld refinement was undertaken. Formation of lanthanum and strontium zirconates was completely avoided at temperatures as high as 1300 C by synthesizing lanthanum manganites from MnO{sub 2} doped with 15 at.% of Sr. Finally, in the presence of LSM, monoclinic phase content was diminished to less than 1.5 mol% after heat treatment at 1300 C. (author)

  13. Strontium clusters: electronic and geometry shell effects

    DEFF Research Database (Denmark)

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

    2008-01-01

    The optimized structure and electronic properties of neutral, singly and doubly charged strontium clusters have been investigated using it ab initio theoretical methods based on density-functional theory. We have systematically calculated the optimized geometries of neutral, singly and doubly...

  14. 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...

  15. 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.

  16. 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.)

  17. 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.

  18. Dielectric and impedance behavior of neodymium substituted strontium hexaferrite

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, Bilal Hamid; Samad, Rubiya; Want, Basharat [University of Kashmir, Solid State Research Lab., Department of Physics, Srinagar (India)

    2016-09-15

    In this study, dielectric behavior and complex impedance of neodymium (Nd) substituted strontium hexaferrite system: Sr{sub 1-x}Nd{sub x}Fe{sub 12}O{sub 19} (x = 0.0, 0.05, 0.1, 0.15, 0.20), synthesized by citrate precursor technique, have been evaluated as a function of applied frequency and temperature. Variation of dielectric constant and dielectric loss with frequency shows the identical behavior for all the compositions. The value of dielectric constant increases with Nd doping. Relaxation process is observed in the composition x = 0.20, and the peaks in this composition shift toward the higher-frequency region as the temperature increases. The dielectric constants show temperature-independent behavior at low temperature, whereas at higher temperatures it increases for all the frequencies. The AC conductivity follows Jonscher's power law, showing that conduction mechanism is due to polaron hopping. Complex impedance as a function of composition and temperature is used to examine the role of grain and grain boundary in the prepared material. Cole-cole plot shows only one semicircle up to x = 0.15, while as for x = 0.20 two semicircles are observed. The conduction mechanism is explained on the basis of both grain and grain boundary. (orig.)

  19. Fibrous growth of strontium substituted hydroxyapatite and its drug release

    International Nuclear Information System (INIS)

    Suganthi, R.V.; Elayaraja, K.; Joshy, M.I. Ahymah; Chandra, V. Sarath; Girija, E.K.; Kalkura, S. Narayana

    2011-01-01

    The effect of strontium on the crystallization of helical ribbon of hydroxyapatite (HAp) was investigated by single diffusion technique in silica gel matrix at 27 deg. C and physiological pH. Fibers of HAp were obtained on addition of strontium. The length of the HAp fibers, were found to decrease as the strontium substitution increases. The presence of strontium ion increased the crystallinity as well as crystallite size of HAp. The strontium substituted HAp (Sr-HAp) has similar stoichiometry to that of biological apatite. Sr-HAp was found to have increased surface area (35%) compared to control. Further, strontium substitution leads to an enhancement of in vitro bioactivity. The cumulative in-vitro amoxicillin drug release in phosphate buffer solution (PBS, pH 7.2) showed a prolonged release profile for Sr-HAp.

  20. Fibrous growth of strontium substituted hydroxyapatite and its drug release

    Energy Technology Data Exchange (ETDEWEB)

    Suganthi, R.V.; Elayaraja, K.; Joshy, M.I. Ahymah; Chandra, V. Sarath [Crystal Growth Centre, Anna University, Chennai 600 025 (India); Girija, E.K. [Department of Physics, Periyar University, Salem 636 011 (India); Kalkura, S. Narayana, E-mail: kalkura@yahoo.com [Crystal Growth Centre, Anna University, Chennai 600 025 (India)

    2011-04-08

    The effect of strontium on the crystallization of helical ribbon of hydroxyapatite (HAp) was investigated by single diffusion technique in silica gel matrix at 27 deg. C and physiological pH. Fibers of HAp were obtained on addition of strontium. The length of the HAp fibers, were found to decrease as the strontium substitution increases. The presence of strontium ion increased the crystallinity as well as crystallite size of HAp. The strontium substituted HAp (Sr-HAp) has similar stoichiometry to that of biological apatite. Sr-HAp was found to have increased surface area (35%) compared to control. Further, strontium substitution leads to an enhancement of in vitro bioactivity. The cumulative in-vitro amoxicillin drug release in phosphate buffer solution (PBS, pH 7.2) showed a prolonged release profile for Sr-HAp.

  1. Observed variations in the strontium concentration of sea water

    Science.gov (United States)

    Angino, E.E.; Billings, G.K.; Andersen, N.

    1966-01-01

    On samples obtained from five widely separated areas of the North Atlantic Ocean 91 determinations of strontium were made. These include surface and deep-water samples from both the cold North Atlantic area and the warm subtropical Caribbean area. The results differ from many of the previously reported values for strontium in sea water. It appears that the more correct value for soluble strontium in sea water is less than the commonly accepted figure of 8.0-8.2 mg/l and most likely lies between 7.2 and 7.8 mg/l. The use of an "average" figure for strontium in sea water should be discouraged as it is clear that the soluble strontium content in sea water does vary considerably; consequently the assumption of a "constant" strontium/chlorinity ratio in the ocean is in error. ?? 1966.

  2. Airplane dopes and doping

    Science.gov (United States)

    Smith, W H

    1919-01-01

    Cellulose acetate and cellulose nitrate are the important constituents of airplane dopes in use at the present time, but planes were treated with other materials in the experimental stages of flying. The above compounds belong to the class of colloids and are of value because they produce a shrinking action on the fabric when drying out of solution, rendering it drum tight. Other colloids possessing the same property have been proposed and tried. In the first stages of the development of dope, however, shrinkage was not considered. The fabric was treated merely to render it waterproof. The first airplanes constructed were covered with cotton fabric stretched as tightly as possible over the winds, fuselage, etc., and flying was possible only in fine weather. The necessity of an airplane which would fly under all weather conditions at once became apparent. Then followed experiments with rubberized fabrics, fabrics treated with glue rendered insoluble by formaldehyde or bichromate, fabrics treated with drying and nondrying oils, shellac, casein, etc. It was found that fabrics treated as above lost their tension in damp weather, and the oil from the motor penetrated the proofing material and weakened the fabric. For the most part the film of material lacked durability. Cellulose nitrate lacquers, however were found to be more satisfactory under varying weather conditions, added less weight to the planes, and were easily applied. On the other hand, they were highly inflammable, and oil from the motor penetrated the film of cellulose nitrate, causing the tension of the fabric to be relaxed.

  3. 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)

  4. Laser Stabilization with Laser Cooled Strontium

    DEFF Research Database (Denmark)

    Christensen, Bjarke Takashi Røjle

    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....... The studies presented in this work open novel possibilities for alternative and simple strategies for surpassing the state-of-the-art laser stabilization and for realizing active light sources involving collective emission from narrow-line atoms....

  5. 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.

  6. Effect of long-term treatment with strontium ranelate on bone strontium content

    DEFF Research Database (Denmark)

    Bärenholdt, Olaf; Kolthoff, Niels; Nielsen, Stig Pors

    2009-01-01

    at the end of treatment. No effect was demonstrated on distal radius relative bone Ca hydroxy apatite. Bone strontium uptake and retention data were compatible with a power function model. Withdrawal of SrR resulted in a decline in bone Sr, but 73 %Sr and 67 %Sr, respectively remained in UD-radius three...... measured by DPA showed a slight decline like in an untreated population. Strontium containing drugs may influence DXA bone mineral measurements several years after treatment withdrawal. According to the power function model the skeletal retention three and six months after stopping the treatment would...

  7. High temperature superconducting material: Bismuth strontium calcium copper oxide. (Latest citations from the Aerospace database). Published Search

    International Nuclear Information System (INIS)

    1993-11-01

    The bibliography contains citations concerning the development, fabrication, and analysis of a high temperature superconducting material based on bismuth-strontium-calcium-copper-oxides (Bi-Sr-Ca-Cu-O). Topics include the physical properties, structural and compositional analysis, magnetic field and pressure effects, and noble metal dopings of Bi-Sr-Ca-Cu-O based systems. The highest transition temperature recorded to date for this material was 120 degrees Kelvin. Fabrication methods and properties of Bi-Sr-Ca-Cu-O films and ceramics are also considered. (Contains 250 citations and includes a subject term index and title list.)

  8. 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)

  9. 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.

  10. Age and gender specific biokinetic model for strontium in humans

    Energy Technology Data Exchange (ETDEWEB)

    Shagina, N. B.; Tolstykh, E. I.; Degteva, M. O.; Anspaugh, L. R.; Napier, Bruce A.

    2015-03-01

    A biokinetic model for strontium in humans is necessary for quantification of internal doses due to strontium radioisotopes. The ICRP-recommended biokinetic model for strontium has limitation for use in a population study, because it is not gender specific and does not cover all age ranges. The extensive Techa River data set on 90Sr in humans (tens of thousands of measurements) is a unique source of data on long-term strontium retention for men and women of all ages at intake. These, as well as published data, were used for evaluation of age- and gender-specific parameters for a new compartment biokinetic model for strontium (Sr-AGe model). The Sr-AGe model has similar structure as the ICRP model for the alkaline earth elements. The following parameters were mainly reevaluated: gastro-intestinal absorption and parameters related to the processes of bone formation and resorption defining calcium and strontium transfers in skeletal compartments. The Sr-AGe model satisfactorily describes available data sets on strontium retention for different kinds of intake (dietary and intravenous) at different ages (0–80 years old) and demonstrates good agreement with data sets for different ethnic groups. The Sr-AGe model can be used for dose assessment in epidemiological studies of general population exposed to ingested strontium radioisotopes.

  11. Process for the extraction of strontium from acidic solutions

    Science.gov (United States)

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

    1994-09-06

    The invention is a process for selectively extracting strontium values from aqueous nitric acid waste solutions containing these and other fission product values. The extractant solution is a macrocyclic polyether in an aliphatic hydrocarbon diluent containing a phase modifier. The process will selectively extract strontium values from nitric acid solutions which are up to 6 molar in nitric acid. 4 figs.

  12. Determination of strontium in rat plasma and plasma ultrafiltrate by ...

    African Journals Online (AJOL)

    A rapid and sensitive analytical assay for the determination of total strontium concentrations in rat plasma was developed and validated. The total strontium levels were determined by use of graphitefurnace atomic-absorption spectrometry (GF-AAS) with Zeeman correction, 1000°Ci n ashing temperatures and 2700°C in ...

  13. 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...

  14. 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 ...

  15. STRONTIUM AS AN EFFICIENT PROMOTER FOR SUPPORTED PALLADIUM HYDROGENATION CATALYSTS

    Science.gov (United States)

    The effect of strontium promotion is studied for a series of supported palladium catalysts such as Pd/zeolite-β, Pd/Al2O3, Pd/SiO2, Pd/hydrotalcite and Pd/MgO. Strontium is found to be an effective promoter for enhancing the metal area, perce...

  16. 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 ...

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

    Indian Academy of Sciences (India)

    Strontium hydroxyapatite, a bioac- tive bone cement, is used in spinal and bone fracture surgery and it is also used in bone replacement, bone fillings, bone adhesives and for treatment of osteoporosis (Ni et al 2006). The synthesis of strontium hydroxyapatite can be accom- plished by using various methods of synthesis like ...

  18. Determination of strontium in rat plasma and plasma ultrafiltrate by ...

    African Journals Online (AJOL)

    use

    2011-12-07

    Dec 7, 2011 ... A rapid and sensitive analytical assay for the determination of total strontium concentrations in rat plasma was developed and validated. The total strontium levels were determined by use of graphite- furnace atomic-absorption spectrometry (GF-AAS) with Zeeman correction, 1000°Ci n ashing temperatures ...

  19. 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

  20. 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.

  1. 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.

  2. 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

  3. Complex permittivity, permeability and microwave absorbing properties of Co–Ti substituted strontium hexaferrite

    Directory of Open Access Journals (Sweden)

    Bindra Narang Sukhleen

    2016-03-01

    Full Text Available M-type strontium ferrite with compositions SrFe(12-2xCoxTixO19 (x = 0.0, 0.3, 0.5, 0.7, 1.0, were prepared by two route ceramic method. The effects of Co–Ti substitution on their microstructure, electromagnetic properties, and microwave absorptive behavior were analyzed. The complex permittivity (∊′-j∊″ and complex permeability (μ′-jμ″ have been measured from 8.2 to 12.4 GHz using a network analyzer. Scanning electron microscope was used to analyze the grain size distribution and porosity of the ferrite. X-ray diffraction confirmed the M-type structure of the doped strontium ferrite. Vibrating sample magnetometer was used to study hysteresis loop of the ferrite. This study suggests that the control of grain size, decrease in coercivity and enhanced values of dielectric constant and loss are effective means to improve microwave absorption. The dielectric constant and loss were enhanced in comparison to the permeability constant and loss over the entire frequency range.

  4. 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.

  5. Spin injection and detection in lanthanum- and niobium-doped SrTiO3 using the Hanle technique

    KAUST Repository

    Han, Wei

    2013-07-08

    There has been much interest in the injection and detection of spin-polarized carriers in semiconductors for the purposes of developing novel spintronic devices. Here we report the electrical injection and detection of spin-polarized carriers into Nb-doped strontium titanate single crystals and La-doped strontium titanate epitaxial thin films using MgO tunnel barriers and the three-terminal Hanle technique. Spin lifetimes of up to ∼100 ps are measured at room temperature and vary little as the temperature is decreased to low temperatures. However, the mobility of the strontium titanate has a strong temperature dependence. This behaviour and the carrier doping dependence of the spin lifetime suggest that the spin lifetime is limited by spin-dependent scattering at the MgO/strontium titanate interfaces, perhaps related to the formation of doping induced Ti 3+. Our results reveal a severe limitation of the three-terminal Hanle technique for measuring spin lifetimes within the interior of the subject material. © 2013 Macmillan Publishers Limited. All rights reserved.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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.)

  11. Seaweed against strontium and preussian blue against cesium

    Directory of Open Access Journals (Sweden)

    G Michanek

    1988-06-01

    Full Text Available The fact that alginates bind strontium and cyanates bind cesium and are capable of removing these elements from living organisms is scientifically verified. Zeolites offer another possibility for exchange of these ions. Practical research should be initiated to find the right doses and procedure to decrease the body burden of radioactive isotopes in reindeer.Alger mot strontium och berlinerblått mot cesium.Abstract in Swedish / Sammanfattning: Mitt budskap år kort: Alger binder strontium, Berlinerblått binder cesium, Sätt fart på forskning och forsök!

  12. 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....

  13. 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

  14. 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...

  15. 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

  16. DRESS syndrome with autoimmune hepatitis from strontium ranelate.

    Science.gov (United States)

    di Meo, Nicola; Gubertini, Nicoletta; Crocè, Lory; Tiribelli, Claudio; Trevisan, Giusto

    2016-05-01

    Strontium ranelate, which is used for postmenopausal osteoporosis, has been associated with drug rash with eosinophilia and systemic symptoms (DRESS) syndrome, a severe, acute, potentially fatal, multisystem adverse drug reaction characterized by skin rash, fever, hematological abnormalities, and lymphadenopathy with involvement of several internal organs. We report the case of a woman who developed DRESS syndrome with a generalized maculopapular rash, eosinophilia, dyspnea, bilateral cervical lymphadenopathy, and reactivation of Epstein-Barr virus (EBV) with liver damage 3 weeks after administration of strontium ranelate for postmenopausal osteoporosis. Approximately 6 months after total remission of cutaneous symptoms, the patient developed autoimmune hepatitis. This case confirms that strontium ranelate should be considered as a possible factor in the etiopathology of DRESS syndrome as well as in the subsequent development of autoimmune hepatitis. The possibility of developing autoimmune hepatitis as a part of DRESS syndrome related to strontium ranelate use can occur months after the acute episode.

  17. Modified strontium titanates: From defect chemistry to SOFC anodes

    DEFF Research Database (Denmark)

    Verbraeken, M.C.; Ramos, Tania; Agersted, Karsten

    2015-01-01

    Modified strontium titanates have received much attention recently for their potential as anode material in solid oxide fuel cells (SOFC). Their inherent redox stability and superior tolerance to sulphur poisoning and coking as compared to Ni based cermet anodes could improve durability of SOFC...... systems dramatically. Various substitution strategies can be deployed to optimise materials properties in these strontium titanates, such as electronic conductivity, electrocatalytic activity, chemical stability and sinterability, and thus mechanical strength. Substitution strategies not only cover choice...... of modified strontium titanates, this paper reviews three different A-site deficient donor (La, Y, Nb) substituted strontium titanates for their electrical behaviour and fuel cell performance. Promising performances in both electrolyte as well as anode supported cell designs have been obtained, when using...

  18. 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.)

  19. Cesium and strontium in Black Sea macroalgae.

    Science.gov (United States)

    Nonova, Tzvetana; Tosheva, Zornitza

    2014-03-01

    The trace level of metals and particularly radioactive ones should be monitored to evaluate the transfer along the trophic chain, assess the risk for biota and can be used for global changes assessment. Plants respond rapidly to all changes in the ecosystem conditions and are widely used as indicators and predictors for changes in hydrology and geology. In this work we represent our successful development and applications of a methodology for monitoring of stable and radioactive strontium and cesium in marine biota (Black Sea algae's). In case of radioactive release they are of high interest. We use ED-XRF, gamma spectrometers and LSC instrumentation and only 0.25 g sample. Obtained results are compared with those of other authors in same regions. The novelty is the connection between the radioactive isotopes and their stable elements in algae in time and space scale. All our samples were collected from Bulgarian Black Sea coast. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Process for the recovery of strontium from acid solutions

    Science.gov (United States)

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

    1992-03-31

    The invention is a process for selectively extracting strontium and technetium values from aqueous nitric acid waste solutions containing these and other fission product values. The extractant is a macrocyclic polyether in a diluent which is insoluble in water, but which will itself dissolve a small amount of water. The process will extract strontium and technetium values from nitric acid solutions which are up to 6 molar in nitric acid. 5 figs.

  1. 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)

  2. Could binary mixture of Nd-Ni ions control the electrical behavior of strontium-barium M-type hexaferrite nanoparticles?

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Muhammad Javed, E-mail: mjiqauchem@yahoo.com [Surface and Solid State Chemistry Laboratory, Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Farooq, Saima [Surface and Solid State Chemistry Laboratory, Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

    2011-05-15

    Research highlights: {yields} Strontium-barium hexaferrites (Sr{sub 0.5}Ba{sub 0.5}Fe{sub 12}O{sub 19}) in single magnetoplumbite phase solid structure are synthesized by the co-precipitation method. {yields} Structural and electrical properties of Nd-Ni substituted ferrites are investigated. {yields} These ferrite materials possess high electrical resistivity (108 {Omega} cm) that is essential to curb the eddy current loss, which is pre-requisite for surface mount devices. -- Abstract: Cationic substitution in M-type hexaferrites is considered to be an important tool for modification of their electrical properties. This work is part of our comprehensive study on the synthesis and characterization of Nd-Ni doped strontium-barium hexaferrite nanomaterials of nominal composition Sr{sub 0.5}Ba{sub 0.5-x}Nd{sub x}Fe{sub 12-y}Ni{sub y}O{sub 19} (x = 0.00-0.10; y = 0.00-1.00). Doping with this binary mixture modulates the physical and electrical properties of strontium-barium hexaferrite nanoparticles. Structural and electrical properties of the co-precipitated ferrites are investigated using state-of-the-art techniques. The results of X-ray diffraction analysis reveal that the lattice parameters and cell volume are inversely related to the dopant content. Temperature dependent DC-electrical resistivity measurements infer that resistivity of strontium-barium hexaferrites decreases from 1.8 x 10{sup 10} to 2.0 x 10{sup 8} {Omega} cm whereas the drift mobility, dielectric constant and dielectric loss tangent are directly related to the Nd-Ni content. The results of the study demonstrate a relationship between the modulation of electrical properties of substituted ferrites and nature of cations and their lattice site occupancy.

  3. 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)

  4. 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 %

  5. The removal of strontium from the mouse by chelating agents

    Energy Technology Data Exchange (ETDEWEB)

    Ortega, A.; Gomez, M.; Domingo, J.L.; Corbella, J.

    1989-07-01

    The effects of the chelating agents monosodium glutamate, Tiron, tartaric acid, ascorbic acid, 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6), 2,3-dimercaptosuccinic acid (DMSA), succinic acid, malic acid, ethylendiaminetetraacetic acid (EDTA), ethylenglycol-bis-(beta-amino-ethylether)-N,N'tetraacetic acid (EGTA), cyclohexane-diaminetetraacetic acid (CDTA) and diethylentria-minepentaacetic acid (DTPA) on the distribution and excretion of intraperitoneally injected strontium were investigated in male Swiss mice. Strontium nitrate was given at a dose equal to 3.78 mmol/kg and ten minutes after, chelators were administered intraperitoneally at doses approximately equal to one-fourth of their respective LD50 values. DTPA, followed by CDTA, EDTA and tartaric acid, was consistently the most effective in increasing the urinary excretion of strontium. Only ascorbic acid increased significantly the fecal excretion of strontium. CDTA, DTPA and ascorbic acid were also the most effective chelators in reducing the concentration of strontium found in various tissues. CDTA, DTPA and tartaric acid are the most effective agents of those tested in the removal of strontium after a single administration.

  6. Superfluid density and carrier concentration across a superconducting dome: The case of strontium titanate

    Science.gov (United States)

    Collignon, Clément; Fauqué, Benoît; Cavanna, Antonella; Gennser, Ulf; Mailly, Dominique; Behnia, Kamran

    2017-12-01

    We present a study of the lower critical field, Hc 1, of SrTi1 -xNbxO3 as a function of carrier concentration with the aim of quantifying the superfluid density. At low carrier concentration (i.e., the underdoped side), superfluid density and the carrier concentration in the normal state are equal within experimental margin. A significant deviation between the two numbers starts at optimal doping and gradually increases with doping. The inverse of the penetration depth and the critical temperature follow parallel evolutions as in the case of cuprate superconductors. In the overdoped regime, the zero-temperature superfluid density becomes much lower than the normal-state carrier density before vanishing all together. We show that the density mismatch and the clean-to-dirty crossover are concomitant. Our results imply that the discrepancy between normal and superconducting densities is expected whenever the superconducting gap becomes small enough to put the system in the dirty limit. A quantitative test of the dirty BCS theory is not straightforward, due to the multiplicity of the bands in superconducting strontium titanate.

  7. 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...

  8. 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

  9. 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

  10. Sintering and Electrical Characterization of La and Nb Co‐doped SrTiO3 Electrode Materials for Solid Oxide Cell Applications

    DEFF Research Database (Denmark)

    Sudireddy, Bhaskar Reddy; Agersted, Karsten

    2014-01-01

    Single‐phase lanthanum and niobium co‐doped strontium titanate (Sr1–3x/2LaxTi0.9Nb0.1O3; x = 0–0.02) ceramics were prepared. Dilatometry in reducing atmosphere showed an increase in the sintering rate and sintered density with an increase in La amount. Microscopy of fractured surfaces of sintered...

  11. Effect of certain alkaline metals on Pr doped glasses to investigate spectroscopic studies

    Science.gov (United States)

    Lenkennavar Susheela, K.; Madhu, A.; Eraiah, B.; Kokila, M. K.

    2018-02-01

    Incorporation of different Alkaline earth metal like Barium, Calcium and strontium in sodium lead borate glass doped with Pr3+ is studied. Physical parameters such as density, molar volume, molar refractivity etc have been evaluated. Effect of different atomic size of alkaline metal using optical and physical parameters is analysed. XRD and FTIR were carried out to know the structural behaviour of the glasses. Absorption and Emission spectra are recorded at room temperature and the results were discussed.

  12. 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)

  13. 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

  14. Studies of Bone Metabolism with the Aid of Radioactive Strontium

    Energy Technology Data Exchange (ETDEWEB)

    Jones, D.C.; Copp, D.H., M.D.

    1948-04-01

    The kinetics of skeletal uptake and urinary excretion of radiostrontium were studied during the critieal first hour following intraperitoneal injection of a carrier-free dose. These experiments not only provided valuable data con.cerning the metabolism and fixation of this important fission product, but, because of the close similarity of strontium and calcium, also gave basic information on the process of calcification. Three groups of rats were compared: normal mature adults, young growing normal animals, and young rachitic rats. In all groups, the blood radioactive strontium rose to a maximum in 10-15 minutes, and then declined as the strontium continued to deposit in the skeleton or to be excreted in the urine. Muscle and skin strontium curves followed those of blood quite closely, suggesting a rapid equilibrium between their extracellular fluid and blood plasma. In all groups there was a continous uptake of strontium by the skeleton. In the adults, this was almost constant, suggesting uptek e by absorption and exchange with the calcium of the bone mineral. In the young rats, both normal and rachitic, the very rapid initial rate of uptake of radio-strontium tapered off sharply with time, indicating that some of this radio-element was coming back from the bone into the blood stream. This suggested a rapid labile combination of strontiunl in these animals, which, since it also occured in the rachitic group in which normal calcification is inhibited, probably associated with the protein osteoid matrix present in both. A hypothetical calcification mechanism was suggested by these findings. Urinary excretion and renal clearance of strontium was constant in all three groups, but the clearance was almost ten times as great in the rachitic as in the normal young and adult rats. This would seem to indicate a direct effect of rickets on the renal mechanism of radiostrontium (and calcium) excretion.

  15. STRONTIUM-90 LIQUID CONCENTRATION SOLUBILITY CORRELATION IN THE HANFORD TANK WASTE OPERATIONS SIMULATOR

    Energy Technology Data Exchange (ETDEWEB)

    HOHL, T.; PLACE, D.; WITTMAN, R.

    2004-08-05

    A new correlation was developed to estimate the concentration of strontium-90 in a waste solution based on total organic carbon. This correlation replaces the strontium-90 wash factors, and when applied in the Hanford Tank Waste Operations Simulator, significantly reduced the estimated quantity of strontium-90 in the delivered low-activity waste feed. This is thought to be a more realistic estimate of strontium-90 than using the wash-factor method.

  16. 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.

  17. 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

  18. 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.)

  19. Surface functionalization with strontium-containing nanocomposite coatings via EPD.

    Science.gov (United States)

    Ma, Kena; Huang, Dan; Cai, Jing; Cai, Xinjie; Gong, Lingling; Huang, Pin; Wang, Yining; Jiang, Tao

    2016-10-01

    Metal orthopedic implants still face challenges in some compromised conditions, partly due to bio-inertness. The present study aimed to functionalize metallic implants with organic-inorganic nanocomposite (strontium-containing chitosan/gelatin) coatings through a simple single-step electrophoretic deposition under mild conditions. The surface characterization and in vitro cellular response were studied and compared with chitosan/gelatin (CS/G) coatings. SEM images suggested the inorganic nanoparticles may be encapsulated within or mixed with organic polymers. The XRD patterns showed that strontium carbonate was generated in the coatings. The TEM images revealed strontium-containing nanoparticles were released from the coatings in PBS. The continuous release after the initial burst release ensured the enduring effects of the functionalized surface. The tensile bond strength of the coatings to the substrates increased after the addition of strontium. In vitro cellular study confirmed that strontium-containing coatings supported the proliferation of MC3T3-E1 cells and exhibited excellent ability to enhance the differentiation of such pre-osteoblasts. Therefore, such organic-inorganic nanocomposite coatings are a promising candidate to functionalize orthopedic implant surfaces. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. 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.

  1. 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.

  2. Removal of radioactive strontium from the rat by feeding stable strontium

    International Nuclear Information System (INIS)

    Kshirsagar, S.G.

    1979-01-01

    The effect of administering the stable isotope of strontium (as phosphate) at different dietary levels to adult rats (fed on a cereal and pulse-based diet containing 0.4% Ca) on the retention of radiostrontium ( 89 Sr) and radiocalcium ( 45 Ca) in the femur and the whole skeleton was studied for a period up to 6 weeks after an intraperitoneal injection of the two radioisotopes. The ability of strontium to remove 89 Sr under the above dietary conditions was examined. Feeding Sr at 0.5% or 1% levels for 6 weeks had no effect on the skeletal content of 89 Sr or 45 Ca while a dietary regimen of 2% Sr (2000 times the normal content), significantly lowered the 89 Sr and 45 Ca content by about 30% in the femur but not in the whole skeleton. At this Sr level, the urinary excretion of the isotopes increased with a concomitant decrease in their excretion in the faeces. This study underscores the limitations of dietary Sr to mobilise 89 Sr from the bones after it is incorporated in the bone mineral. (author)

  3. Measurement of Elastic Modulus of Alumina and Barium Strontium Titanate Wafers Produced by Tape Casting Method

    Science.gov (United States)

    2014-02-01

    DATES COVERED (From – To) 4. TITLE AND SUBTITLE MEASUREMENT OF ELASTIC MODULUS OF ALUMINA AND BARIUM STRONTIUM TITANATE WAFERS PRODUCED BY...configuration testing method. Samples of barium strontium titanate (BST) were made using a regular powder pressing, sintering, pelletizing, and...fabricated using thin wafers of barium strontium titanate (BST) and aluminum oxide (alumina) ceramic during launch of a system. Sandia National

  4. Morphology control of hexagonal strontium ferrite micro/nano-crystals

    Directory of Open Access Journals (Sweden)

    Deyang Chen

    2017-05-01

    Full Text Available In this study, controllable morphology evolution of hexagonal strontium ferrite (SrFe12O19 micro/nano-crystals has been demonstrated. Single phase strontium ferrite platelets with hexagonal morphology were successfully prepared by conventional ceramic process. In the hexagonal crystals, it is revealed that the anisotropic growth rate is changed, with the increasing of ball milling time, from relatively high rate along the direction (c-axis to direction, leading to the morphology evolution. Moreover, the optimal saturation magnetization (MS is 69.5 emu/g, which is intensely close to the theoretical value (72 emu/g. This study provides the direct evidence of the enhanced reaction activity induced by high energy ball milling in strontium hexaferrite platelets and the obtained SrFe12O19 particles are promising for the hard magnet application and the magnetoelectric electronics.

  5. 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

  6. Strontium ranelate related Stevens-Johnson syndrome: a case report.

    Science.gov (United States)

    Yang, C-Y; Chen, C-H; Wang, H-Y; Hsiao, H-L; Hsiao, Y-H; Chung, W-H

    2014-06-01

    Strontium ranelate is a relatively new medication with good safety profile for the treatment of postmenopausal osteoporosis. However, severe cutaneous adverse drug reactions have been reported, such as drug rash with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN). We report the case of a 70-year-old woman who developed multiple itching erythematous macules and plaques about 1 month after beginning strontium ranelate medication. The cutaneous lesions progressed over the entire body with severe oral and ocular mucosa involvement. Probable mild SJS was diagnosed, compatible with the pathology findings, and strontium ranelate was discontinued immediately. Systemic methylprednisolone was administered to suppress the overactive immune system and ameliorate cutaneous symptoms. With early recognition and prompt treatment, the patient's prognosis was good.

  7. [Impact of a health safety warning on strontium ranelate utilization].

    Science.gov (United States)

    Carracedo-Martínez, Eduardo; Pía-Morandeira, Agustín

    2010-01-01

    To evaluate changes in the use of strontium ranelate following a health safety warning in November 2007 on the risks of the development of DRESS (Drug Rash with Eosinophilia and Systemic Symptoms) with the use of this medicine. Monthly strontium ranelate DHD (daily defined doses/1,000 inhabitants/day) were calculated between 2006 and 2008 in a health area of Spain. The data were analyzed graphically and through a multiple regression model. Graphical representation showed a long-term rising trend throughout the study period, although growth slowed after the safety warning was issued. The multiple regression model showed that the health warning was statistically significant. The use of strontium ranelate continues to grow after the issue of the health safety warning, although at a slower pace than previously. Copyright (c) 2009 SESPAS. Published by Elsevier Espana. All rights reserved.

  8. 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.

  9. Continental fragmentation and the strontium isotopic evolution of seawater.

    Science.gov (United States)

    Eric, H.; Jean Pascal, C.

    2008-12-01

    The time evolution of the strontium isotopic composition of seawater over the last 600 million years has the form of an asymmetric trough. The values are highest in the Cambrian and recent and lowest in the Jurassic. Superimposed on this trend are a number of smaller oscillations. The mechanisms responsible for these global isotopic fluctuations are subject to much debates. In order to get a quantitative picture of the changing paleogeography, we have characterized land-ocean distributions over Late Proterozoic to Phanerozoic times from measurement of perimeters and areas of continental fragments, based on paleomagnetic reconstructions. These measurements served to calculate geophysically constrainted breakup and scatter indexes of continental land masses from 0 to 1100 Ma (Cogne and Humler, 2008). Both parameters (strontium isotopic ratios of seawater and continental fragmentation indexes) are obviously highly correlated during the last 600 Ma. Low continental dispersion (that is large continental land masses) are associated with low seawater strontium isotopic ratios (that is when the continental inputs to oceans are minimum) and high continental dispersion (that is relatively small and widely distributed continents) with high seawater strontium isotopic ratios (that is when the continental input to ocean is maximum). Importantly, this first order evolution appears to conflict with the common idea of mountains erosion as a source for radiogenic strontium to oceans because high strontium isotopic ratios in seawater correspond to period of maximum dispersion of continents and not with period of general collisions. At first glance, it would seem that continental erosion increases with the degree of continental dispersion. Models showing that continental precipitation increases when continental masses are smaller and more widely dispersed and/or the length of continental margins available for rivers to carry continental material to oceans are thus favoured in order

  10. All-alkoxide synthesis of strontium-containing metal oxides

    Science.gov (United States)

    Boyle, Timothy J.

    2001-01-01

    A method for making strontium-containing metal-oxide ceramic thin films from a precursor liquid by mixing a strontium neo-pentoxide dissolved in an amine solvent and at least one metal alkoxide dissolved in a solvent, said at least one metal alkoxide selected from the group consisting of alkoxides of calcium, barium, bismuth, cadmium, lead, titanium, tantalum, hafnium, tungsten, niobium, zirconium, yttrium, lanthanum, antimony, chromium and thallium, depositing a thin film of the precursor liquid on a substrate, and heating the thin film in the presence of oxygen at between 550 and 700.degree. C.

  11. 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

  12. 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.

  13. Recycler model magnet test on temperature compensation for strontium ferrite

    International Nuclear Information System (INIS)

    Yamada, R.; Foster, W.; Ostiguy, F.; Wake, M.

    1995-10-01

    The Recycler ring magnet will be made of Strontium ferrite permanent magnets. A strontium ferrite permanent magnet without compensation has a temperature coefficient of -0.2 % in dB/dT. To compensate this effect, we are utilizing 30 % Ni 70 % Fe alloy, a temperature compensation ferromagnetic material with a low Curie point. To search for optimum commercially available material and optimum condition, we made a couple of simple model magnets, and tested with several different compensating material. The test results are reported and its optimal conditions are shown. Several different configurations were tested including a possible 2 kG magnet configuration

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

    Strontium is known to have a positive effect on bone by concomitantly increasing bone formation while decreasing bone resorption thereby providing a sustained skeletal benefit. Strontium malonate is being developed as a novel orally available pharmaceutical for the treatment and prevention...... 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...... showed that administration of strontium malonate caused a significant increase in the strontium contents of all three kinds of tissue. Bone samples showed an approximately 80 fold increase in strontium content in the dogs treated with 300 mg/kg/day compared to placebo. The higher dose groups showed only...

  19. Varistor property of SnO{sub 2}.CoO.Ta{sub 2}O{sub 5} ceramic modified by barium and strontium

    Energy Technology Data Exchange (ETDEWEB)

    Dhage, S.R. [School of Environmental and Chemical Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)], E-mail: sanjay.dhage@gmail.com; Ravi, V. [Physical and Materials Chemistry Division, National Chemical Laboratory, Pune 411008 (India)], E-mail: r.venkat@ncl.res.in; Yang, O.B. [School of Environmental and Chemical Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)

    2008-10-20

    The influence of an alkali earth (Ba/Sr) element in small quantities (<1 at.%) on non-linear electrical properties of 98.5% SnO{sub 2} + 1% CoO + 0.5% Ta{sub 2}O{sub 5} (all in at.%) varistor system has been investigated. The non-linear coefficient increases from 33 to 52 whereas breakdown field strength varies 5025-6050 V cm{sup -1} for the barium-doped samples. In case of strontium-doped specimens moderate increase in non-linear coefficient but significant increase in breakdown field is observed. It is proposed that due to ionic size misfit, Ba and Sr segregates to grain boundaries thereby modifying their barrier properties. The contribution from grain boundary phase to the electrical property is confirmed by the impedance analysis.

  20. Assessment of the effect of strontium, lead, and aluminum in bone on dual-energy x-ray absorptiometry and quantitative ultrasound measurements: A phantom study.

    Science.gov (United States)

    Jang, Deok Hyun; Da Silva, Eric; Tavakkoli, Jahan; Slatkovska, Lubomira; Cheung, Angela M; Pejović-Milić, Ana

    2018-01-01

    Dual-energy X-ray absorptiometry (DXA) is the gold standard technique to measure areal bone mineral density (aBMD) for the diagnosis of osteoporosis. Because DXA relies on the attenuation of photon to estimate aBMD, deposition of bone-seeking metallic elements such as strontium, lead, and aluminum that differ in atomic numbers from calcium can cause inaccurate estimation of aBMD. Quantitative ultrasound (QUS) is another technique available to assess bone health by measuring broadband ultrasound attenuation (BUA), speed of sound (SOS), and an empirically derived quantity called stiffness index (SI). Because the acoustic properties are not prone to significant change due to changes in microscopic atomic composition of bone, it is hypothesized that QUS is unaffected by the presence of bone-seeking elements in the bone. The objective of this study was to investigate the effect of strontium, lead, and aluminum on DXA-derived aBMD and QUS parameters using bone-mimicking phantoms compatible with both techniques. Bone-mimicking phantoms were produced by homogeneously mixing finely powdered hydroxyapatite compounds that contain varying concentrations of strontium, lead, or aluminum with porcine gelatin solution. Seven strontium-substituted phantoms were produced with varying molar ratio of Sr/(Sr + Ca) ranging from 0% to 2%. Four lead-doped phantoms and four aluminum-doped phantoms were constructed with the respective analyte concentrations ranging from 50 to 200 ppm. An additional 0 ppm phantom was produced to be used as a baseline for the lead and aluminum phantom measurements. All phantoms had uniform volumetric bone mineral density (vBMD) of 200 mg/cm 3 , and were assessed using a Hologic Horizon ® DXA device and a Hologic Sahara ® QUS device. Furthermore, theoretical aBMD bias for mol/mol% substitution of calcium with the three bone-seeking elements was calculated. Strong positive linear relationship was found between aBMD measured by DXA and strontium concentration

  1. Determination of Strontium-89 and -90 in soil with total sample decomposition

    International Nuclear Information System (INIS)

    Martin, D.B.

    1979-01-01

    Potassium fluoride and pyrosulfate fusions of soil guarantee strontium is in the ionic state. After dissolving the fusion cake, strontium sulfate is coprecipitated with lead and calcium which are preferentially dissolved into EDTA and discarded. Subsequently, strontium sulfate is dissolved in EDTA and hydrolytic elements are separated on ferric hydroxide. Strontium sulfate is precipitated from EDTA at a lower pH, dissolved in DTPA, and set aside for 90 Y ingrowth. After ingrowth the strontium sulfate is reprecipitated, and the 90 Y is extracted from the supernate into bis(2-ethyhexyl) phosphoric acid. When both 89 Sr and 90 Sr are being determined, barium chromate is separated from a DTPA solution of strontium. Strontium sulfate is precipitated from the barium chromate supernate and counted for 89 Sr plus 90 Sr. Yttrium-90 is counted on yttrium oxalate to determine 90 Sr, and 89 Sr is determined by difference. Precision, accuracy, sensitivity, and the effects of interferences are discussed. 4 tables, 1 figure

  2. The effects of strontium ranelate treatment on ovariectomized Sprague-Dawley rat tibia

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Y. [Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Jin, W. [Institute of Radiation Medicine, Fudan University, Shanghai 200032 (China); Wang, C.; Yang, M. [Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Shen, H. [Institute of Modern Physics, Fudan University, Shanghai 200433 (China)], E-mail: haoshen@fudan.edu.cn; Eisa, M.H. [Department of Physics, College of Science, Sudan University of Science and Technology, Box 407, Khartoum 111113 (Sudan); Mi, Y. [Institute of Modern Physics, Fudan University, Shanghai 200433 (China)

    2009-06-15

    Micro Proton Induced X-ray Emission (micro-PIXE) technique was used to study the effect of strontium ranelate on osteoporosis resulted from estrogen deficiency. The contents of calcium and strontium in tibia, as well as calcium distribution for structural determination were investigated. Three groups of tibia samples were respectively taken from three groups of female Sprague-Dawley (S.D.) rats, i.e. control, ovariectomized and ovariectomized followed strontium ranelate treatment. It was found that the strontium content was decreasing in the bone from ovariectomized rat compared with that in control, but significantly increasing in the bone from strontium ranelate treated ovariectomized rat. Our study showed that strontium content is a feasible parameter for the diagnosis of osteoporosis caused by estrogen deficiency. Strontium ranelate is an effective antiosteoporosis chemical to rebuild the bone structure and prevent deterioration of bone strength as well.

  3. Conductivity of A- and B-site doped LaAlO3, LaGaO3, LaScO3 and LaInO3 perovskites

    DEFF Research Database (Denmark)

    Lybye, D.; Poulsen, F.W.; Mogensen, Mogens Bjerg

    2000-01-01

    The conductivity of the materials LaAlO3, LaGaO3, LaScO3 and LaInO3 all doped with 10% strontium on the A-site and 10% magnesium at the B-site has been measured at different temperatures and oxygen partial pressures. The doped LaGaO3 is found to be an almost pure ionic conductor with a conductivi...

  4. Assessment of strontium and calcium levels in Pakistani diet

    International Nuclear Information System (INIS)

    Akhter, P.; Baloch, N.Z.; Mohammad, D.; Orfi, S.D.; Ahmad, N.

    2004-01-01

    To cope with nuclear emergency effectively due to ingestion of fission fragment 90 Sr, adequacy of nutritionally and radiologically important elements strontium and calcium was studied in typical Pakistani diet and baseline analytical data were generated. Concentrations of strontium and calcium were measured by using inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and atomic absorption spectrometry (AAS) techniques. Daily dietary intake of strontium and calcium varied from 0.9 to 5.7 mg and 217 to 713 mg with the geometric mean valuexgeometric standard deviation of 2.6x1.7 and 487.1x1.4 mg d -1 , respectively. The average Sr concentration in the Pakistani diet was 1.4 times higher while Ca concentration was 0.4 times lower than the recommended values of the International Commission on Radiological Protection (ICRP). The calculated Sr/Ca ratio 5.3E-03 was also higher than the ICRP value. The study depicts that the strontium concentration in the Pakistani diet is adequate, while the calcium concentration is inadequate according to international standards and needs improvement

  5. 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

  6. 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/

  7. 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)

  8. 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)

  9. Possible benefits of strontium ranelate in complicated long bone fractures.

    Science.gov (United States)

    Alegre, Duarte Nuno; Ribeiro, Costa; Sousa, Carlos; Correia, João; Silva, Luís; de Almeida, Luís

    2012-02-01

    Osteoporosis drugs are prescribed to prevent fragility fractures, which is the principal aim of the management of osteoporosis. However, if fracture does occur, then it is also important to promote a fast and uneventful healing process. Despite this, little is known about the effect of osteoporosis drugs on bone healing in humans. Strontium ranelate is an osteoporosis agent that increases bone formation and reduces bone resorption and may therefore be beneficial in fracture healing. We report four cases of fracture non-union for up to 20 months. Treatment with strontium ranelate (2 g/day) for between 6 weeks and 6 months appeared to contribute to bone consolidation in the four cases. Animal studies support beneficial effects of strontium ranelate on bone healing via improvement of bone material properties and microarchitecture in the vicinity of the fracture. The clinical cases described herein provide new information on these effects, in the absence of randomized controlled studies on the clinical efficacy of pharmacological treatments in osteoporosis in fracture repair. Further studies are necessary. Fracture healing is an important topic in orthopedic research and is also a concern for patients with postmenopausal osteoporosis. Evidence from case reports and animal studies suggests that strontium ranelate improves bone microarchitecture and accelerates fracture healing. A positive effect of osteoporosis treatments on bone healing is an interesting possibility and merits further clinical research.

  10. 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 ...

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

    Indian Academy of Sciences (India)

    adhesives and for treatment of osteoporosis (Ni et al 2006). The synthesis of strontium hydroxyapatite can be accom- plished by using various methods of synthesis like sol–gel. (Balamurugan et al 2009), solid titrations (Pan et al 2009), wet chemical (Bigi et al 2007) and sol–gel- supercritical fluid drying (SCFD) methods ...

  12. Laser sources for precision spectroscopy on atomic strontium.

    Science.gov (United States)

    Poli, N; Ferrari, G; Prevedelli, M; Sorrentino, F; Drullinger, R E; Tino, G M

    2006-04-01

    We present a new laser setup designed for high-precision spectroscopy on laser cooled atomic strontium. The system, which is entirely based on semiconductor laser sources, delivers 200 mW at 461 nm for cooling and trapping atomic strontium from a thermal source, 4 mW at 497 nm for optical pumping from the metastable P23 state, 12 mW at 689 nm on linewidth less than 1 kHz for second-stage cooling of the atomic sample down to the recoil limit, 1.2 W at 922 nm for optical trapping close to the "magic wavelength" for the 0-1 intercombination line at 689 nm. The 689 nm laser was already employed to perform a frequency measurement of the 0-1 intercombination line with a relative accuracy of 2.3 x 10(-11), and the ensemble of laser sources allowed the loading in a conservative dipole trap of multi-isotopes strontium mixtures. The simple and compact setup developed represents one of the first steps towards the realization of a transportable optical standards referenced to atomic strontium.

  13. 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.

  14. 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 ...

  15. 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

  16. 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 ...

  17. 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)

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

    Indian Academy of Sciences (India)

    All the results are discussed in terms of complex permeability and permittivity. The study revealed that intrinsic conductivity and polarization of the r-GO particles and dielectric polarization of the strontium titanate within epoxy matrix contribute to the microwave absorption. Keywords. Composite; absorption; reflection loss; ...

  19. Thermal expansion behaviour of barium and strontium zirconium ...

    Indian Academy of Sciences (India)

    Unknown

    Thermal expansion behaviour of barium and strontium zirconium phosphates. P SRIKARI TANTRI, K GEETHA†, A M UMARJI† and SHEELA K RAMASESHA*. Materials Science Division, National Aerospace Laboratories, Bangalore 560 017, India. †Materials Research Centre, Indian Institute of Science, Bangalore 560 ...

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

    Indian Academy of Sciences (India)

    A matrix composed of polyvinyl-alcohol (PVA) mixed with different concentration ratios of the granular strontium chloride (SrCl2.6H2O) were prepared by casting technique method at room temperature (about 30°C). The electric and dielectric properties such as a.c. electrical conductivity by a conventional method, using ...

  1. 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)

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

    Indian Academy of Sciences (India)

    analysis and solubility. The synthesized polymer was used for sequestering strontium metal from the aqueous solu- tion. The metal binding was examined by the energy dispersive spectroscopy and scanning electron microscopy for the adsorbed Sr(II). Batch adsorption studies were performed by varying three parameters, ...

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

    Indian Academy of Sciences (India)

    The synthesized polymer was used for sequestering strontium metal from the aqueous solu- tion. The metal binding was examined by the energy dispersive spectroscopy and scanning electron microscopy for the adsorbed Sr(II). Batch adsorption studies were performed by varying three parameters, namely initial pH, adsor-.

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

    Indian Academy of Sciences (India)

    Crystal growth; strontium oxalate; X-ray spectroscopy; FT–IR. 1. Introduction. The growth of single crystals of various substances has gained considerable attention of several investigators. Sophisticated and strenuous equipments have been devel- oped and employed for growing a wide variety of crystals; either may be due ...

  5. Structure and magnetic properties of Zr–Mn substituted strontium ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 39; Issue 5. Structure and magnetic properties of Zr–Mn substituted strontium hexaferrite Sr(Zr,Mn) x Fe 12 − 2 x O 19 nanoparticles synthesized by sol–gel auto-combustion method. S ALAMOLHODA S M MIRKAZEMI Z GHIAMI M NIYAIFAR. Volume 39 Issue 5 ...

  6. Photoluminescence properties of non-stoichiometric strontium zirconate powder phosphor

    Czech Academy of Sciences Publication Activity Database

    Jarý, Vítězslav; Boháček, Pavel; Mihóková, Eva; Havlák, Lubomír; Trunda, Bohumil; Nikl, Martin

    2013-01-01

    Roč. 35, č. 5 (2013), s. 1019-1022 ISSN 0925- 3467 Grant - others:GA AV ČR(CZ) M100101212 Institutional support: RVO:68378271 Keywords : photoluminescence * non-stoichiometry * strontium zirconate * phenomenological mode * ionization * exciton Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.075, year: 2013 http://www.sciencedirect.com/science/article/pii/S0925346712005447

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

    Indian Academy of Sciences (India)

    Administrator

    Polyvinyl-alcohol (PVA); granular strontium chloride, SrCl2; a.c. electrical conductivity; dielec- tric constant; dielectric loss; Young's modulus; creep relaxation curve. 1. Introduction. The purpose of this article is to review the available experimental evidences pertaining to electric, dielectric and mechanical properties on a ...

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

    Indian Academy of Sciences (India)

    Administrator

    granular strontium chloride (SrCl2⋅6H2O) were prepared by casting technique method at room temperature. (about 30°C). The electric and dielectric ... stored properties for these samples were also determined at room temperature. Keywords. ..... decrease in the elasticity of the samples leading to a decrease in average ...

  9. Novel bioresorbable strontium hydroxyapatite membrane for guided bone regeneration.

    Science.gov (United States)

    Hao, J; Acharya, A; Chen, K; Chou, J; Kasugai, S; Lang, N P

    2015-01-01

    Membrane materials have been widely used for guided bone regeneration (GBR). However, due to bio-functional limitation of the current membranes, the ideal resorbable membrane that can stimulate bone regeneration has yet to be developed. This study seeks to investigate the effects of a strontium hydroxyapatite (SrHA)-containing membrane for GBR. Strontium hydroxyapatite powder was synthesized and mixed with gelatin solution to the final concentration of 10 mg/ml (Sr10) and 20 mg/ml (Sr20). Approximately 100-μm-thick membranes were fabricated, and the mechanical properties and strontium ion release pattern were analyzed. Rat bone marrow stromal cell (BMSC) responses were investigated in vitro. Bilaterial rat calvarial defects were used in vivo to compare the SrHA membranes against commercially available collagen membranes and evaluated radiologically and histologically. Strontium hydroxyapatite membranes exhibited higher elasticity and strength than the collagen membrane, and slow strontium ion release was also confirmed. No BMSC cytotoxicity was found on the SrHA membranes, and the alkaline phosphatase positively stained area was significantly greater than the collagen membrane at earlier time point. At 4 weeks, both micro-CT and histological analyses revealed that the Sr20 group yielded significantly greater bone formation. The SrHA-containing membrane developed in this study was found to be a biocompatible material that can stimulate BMSC differentiation as well as bone regeneration and maturation in rat calvarial defects at early time point compared with collagen membrane. The best result was observed in Sr20 group, which can be potentially effective for GBR. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. Multifunction Sr, Co and F co-doped microporous coating on titanium of antibacterial, angiogenic and osteogenic activities

    OpenAIRE

    Zhou, Jianhong; Zhao, Lingzhou

    2016-01-01

    Advanced multifunction titanium (Ti) based bone implant with antibacterial, angiogenic and osteogenic activities is stringently needed in clinic, which may be accomplished via incorporation of proper inorganic bioactive elements. In this work, microporous TiO2/calcium-phosphate coating on Ti doped with strontium, cobalt and fluorine (SCF-TiCP) was developed, which had a hierarchical micro/nano-structure with a microporous structure evenly covered with nano-grains. SCF-TiCP greatly inhibited t...

  11. Raman and Rietveld structural characterization of sintered alkaline earth doped ceria

    Energy Technology Data Exchange (ETDEWEB)

    Siqueira Junior, Jose Marcio; Brum Malta, Luiz Fernando; Garrido, Francisco M.S. [Departamento de Quimica Inorganica, Instituto de Quimica, Universidade Federal do Rio de Janeiro, Av. Athos da Silveira Ramos, 149, Centro de Tecnologia, Bloco A, room 632, CEP 68563, 21941-909 Rio de Janeiro, RJ (Brazil); Ogasawara, Tsuneharu [Programa de Engenharia Metalurgica e de Materiais, Coordenacao dos Programas de Pos - Graduacao de Engenharia, Centro de Tecnologia, Universidade Federal do Rio de Janeiro, Ilha do Fundao, CEP 68505, 21941-972 Rio de Janeiro, RJ (Brazil); Medeiros, Marta Eloisa, E-mail: chico@iq.ufrj.br [Departamento de Quimica Inorganica, Instituto de Quimica, Universidade Federal do Rio de Janeiro, Av. Athos da Silveira Ramos, 149, Centro de Tecnologia, Bloco A, room 632, CEP 68563, 21941-909 Rio de Janeiro, RJ (Brazil)

    2012-08-15

    Nanocrystalline calcium and strontium singly doped ceria and co-doped ceria materials for solid electrolytes were prepared via a hydrothermal route. The effect of the hydrothermal treatment time on the solid solution composition was evaluated. Sr doped ceria was the most difficult to form, due to the Sr{sup 2+} large ionic radius. The small crystal size (12-16 nm) of powders allowed sintering into dense ceramic pellets at 1350 Degree-Sign C for 5 h. Raman spectroscopy evidenced a great lattice distortion for Sr doped and co-doped ceria materials, explaining the deterioration of the electrical properties for these ceramics. Besides that, a second phase was detected for Sr doped ceria pellet by using X-ray powder diffraction and Rietveld refinement of XRD data. Impedance measurements showed that Ca-doped ceria behaves as the best ionic conductor ({sigma}{sub g} 390 Degree-Sign C = 1.0 Multiplication-Sign 10{sup -3} S cm{sup -1}) since the nominal composition was achieved; on the other hand, Sr doped ceria performed as resistive materials since Sr incorporation into ceria lattice was critical. These results enhance the close interlace between electrical performance and chemical composition of alkaline earth doped ceria. -- Highlights: Black-Right-Pointing-Pointer Hydrothermally synthesized calcium doped ceria nanoparticles. Black-Right-Pointing-Pointer Incorporation of alkaline earth dopant into ceria lattice. Black-Right-Pointing-Pointer Raman and Rietveld structural characterization. Black-Right-Pointing-Pointer Calcium doped ceria ceramic pellets with high ionic conductivity. Black-Right-Pointing-Pointer Problems associated with the Sr{sup 2+} incorporation into ceria lattice.

  12. 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.

  13. 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

  14. Strontium content and strontium-calcium ratio in timothy (Phleum pratense L.) and soil in Finland

    International Nuclear Information System (INIS)

    Paasikallio, Arja

    1979-01-01

    Strontium and calcium contents were determined about 2 000 sample pairs of timothy and soil. An investigation into these element contents was made with reference to parishes and latitudinal zones. The effect of some soil factors on the Sr content of timothy in Carex peat soil was also studied. The Sr content of timothy was highest in northern Finland, while the highest contents of soluble Sr and Ca were generally found in the soils of southern Finland. The Ca content of timothy also tended to rise from the southern to the northern regions but to a lesser extent than Sr. The Sr/Ca ratio both in timothy and soil was generally highest between latitudes 64 deg and 66 deg N. The highest Sr content of timothy in the north was suggested to be due to at least some of the following factors: regional differences in the distribution of soil types, the occurrence of nutritionally poorer soils in the northern regions, climatological factors and plant competition. The present material did not contain any exceptionally high Sr contents in timothy or soil. In Carex peat, the Sr content of timothy increased with decreasing volume weight and pH of the soil. In these soils, the variation in the low Sr content of timothy was explained significantly by soluble Sr in the soil and the straw height; plant Sr increased with increasing soluble Sr and decreasing plant height. In higher Sr contents, plant Sr increased with decreasing soluble Ca. (author)

  15. 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)

  16. 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

  17. Optical Properties of Rare Earth Doped SrS Phosphor: A Review

    Science.gov (United States)

    Khare, Ayush; Mishra, Shubhra; Kshatri, D. S.; Tiwari, Sanjay

    2017-02-01

    Rare earth (RE) doped SrS phosphor has attracted a lot of attention on a wide range of photo-, cathodo-, thermo-, and electroluminescent applications. Upon doping with different RE elements (e.g., Ce, Pr, Eu, Yb), the luminescence from SrS can be varied over the entire visible region by appropriately choosing the composition of the strontium sulfide host. The main applications include flat panel displays and SrS-based powder electroluminescence (EL) for back lights. Sulfide materials known for providing Eu2+ based red emission band and preferred as a color conversion material in white light emitting diodes are discussed. Especially, the applications of RE doped SrS are described in light of their utility as conversion and storage phosphors. The effect of energy level splitting, EL efficiency, post-annealing, milling time, and impurity on luminescence properties for SrS are also discussed.

  18. 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.

  19. 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)

  20. Growth of strontium hydrogen phosphate/gelatin composites: a biomimetic approach

    OpenAIRE

    Parvinzadeh Gashti, Mazeyar; Stir, Manuela Elena; Hulliger, Jürg

    2016-01-01

    Recent research has focused on the crystal growth of strontium phosphates via different methods due to the bioactivity and biocompatibility of these materials with bone tissue. Here, we use a biomimetic method to synthesize strontium hydrogen phosphate/gelatin composites via single diffusion in gelatin. We compare the composite crystals with analytical-grade strontium hydrogen phosphate using infrared spectroscopy (IR), scanning electron microscopy (SEM), thermal gravimetric analysis, and X-r...

  1. 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)

  2. Effect of donor and acceptor dopants on crystallization, microstructural and dielectric behaviors of barium strontium titanate glass ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Avadhesh Kumar, E-mail: yadav.av11@gmail.com [Department of Physics, Dr. Bheem Rao Ambedkar Government Degree College, Anaugi, Kannauj (India); Gautam, C.R. [Department of Physics, University of Lucknow, Lucknow 226007 (India); Singh, Prabhakar [Department of Physics, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India)

    2016-07-05

    Bulk transparent barium strontium titanate borosilicate glasses in glass system (65-x)[(Ba{sub 0.6}Sr{sub 0.4}).TiO{sub 3}]-30[2SiO{sub 2}.B{sub 2}O{sub 3}]-5[K{sub 2}O]-x[A{sub 2}O{sub 3}], A = La, Fe (x = 2, 5 and 10) were prepared by rapid melt-quench technique and subsequently, converted into glass ceramics by regulated heat treatment process. The phase identification was carried out by X-ray powder diffraction and their surface morphology was studied by scanning electron microscopy. The dielectric properties were studied by impedance spectroscopic technique. Investigated glass samples were crystallized into major and secondary phases of Ba{sub 1.91}Sr{sub 0.09}TiO{sub 4} and Ba{sub 2}TiSi{sub 2}O{sub 8}, respectively. A very high dielectric constant having value upto 68000 was found in glass ceramic sample BST5K10F. This high value of dielectric constant was attributed to interfacial polarization, which arose due to conductivity difference among semiconducting crystalline phases, conducting grains and insulating grain boundaries. Donor dopant La{sub 2}O{sub 3} and acceptor dopant Fe{sub 2}O{sub 3} play an important role for enhancing crystallization, dielectric constant and retardation of dielectric loss in the samples. Moreover, higher value of dielectric constant and lower value of dielectric loss was found in Fe{sub 2}O{sub 3} doped samples in comparison to La{sub 2}O{sub 3} doped samples. - Highlights: • Bulk transparent barium strontium titanate glasses are successfully prepared. • A very high dielectric constant upto 68000 was found in glass ceramics. • La{sub 2}O{sub 3} and Fe{sub 2}O{sub 3} play role for enhancing value of dielectric constant. • Higher dielectric constant with low dielectric loss was found in Fe{sub 2}O{sub 3} doped sample. • Such glass ceramics may be used in making capacitors for high energy storage.

  3. Synthesis and characterization of Sr doped LaMnO3 electrospun fibers

    International Nuclear Information System (INIS)

    Lubini, M.; Alves, A. K.; Bergmann, C.P.; Malfatti, C.

    2012-01-01

    In this paper, fibers of lanthanum manganite doped with strontium were obtained by electrospinning using lanthanum chloride, manganese nitrate, strontium chloride and polyvinyl butyral as precursors. During the electrospinning process, we studied the influences of parameters such as the concentration of polymer (10 and 15 wt%), the flow, and the distance between the electrodes in the morphologic characteristics of the fibers. After synthesis the fibers were heat treated at different temperatures. Morphological characterization was performed by electron microscopy, thermal analysis was used to evaluate the thermal behavior, and X-ray diffraction to identify the phases present. We observed the formation of micro-and nanostructured fibers consisting mainly of LaMnO 3 . (author)

  4. 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)

  5. 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)

  6. 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.

  7. 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)

  8. On effect of medium composition on strontium sulfate solubility

    International Nuclear Information System (INIS)

    Likhachev, D.S.; Keskinov, V.A.; Karmanova, E.G.; Pyartman, A.K.

    1987-01-01

    Solubility of strontium sulfate at 25 deg C in aqueous solutions of ammonium sulfate, as well as in solutions of the mixture of lanthanum nitrate and ammonium sulfate, at different acidities of the medium is determined. It is established that an increase in the medium acidity and addition of lanthanum nitrate at the constant total concentration of sulfate-ions in solution results in the increase of SrSO 4 solubility due to the binding of sulfate-ions into forms HSO 4 - and LaSO 4 + . The values of solubility product of SrSO 4 in solutions of the mixture of ammonium sulfate, strontium nitrate and lanthanum nitrate at different temperatures are determined

  9. 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

  10. 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

  11. [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.

  12. 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...

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. Selective extractor for strontium contained in aqueous solution

    International Nuclear Information System (INIS)

    Kobuya, Yoshiaki; Togashi, Akio; Ozawa, Masaki; Watabe, Masayuki.

    1995-01-01

    The present invention concerns an extractor effective for selectively extracting and removing strontium (Sr) contained in highly radioactive liquid wastes. The selective extractor for Sr according to the present invention comprises 1, 2 benzene bis (1, 4-dioxanonyl-6, 8-dioxanate) metal complex having metal ions such as of Cu, Zn or Ni. The compound has an inner cavity as a space for capturing Sr, so that it can be used effectively as an extractor upon selectively removing Sr. (T.M.)

  18. Study on the extraction of strontium with amido podand

    International Nuclear Information System (INIS)

    Ye Guoan; Luo Fangxiang; Jiang Yongqing; Chen Wenjun; Ding Songdong

    2001-01-01

    By using n-octanol and kerosene as diluent, the extraction behavior of strontium from nitric acid solution is studied with N,N,N',N'-tetrabutyl-3-oxa-pentanediamide (TBOPDA), N,N,N',N'-tetra-isobutyl-3-oxa-pentanediamide (TiBOPDA) and N,N,N',N'-tetrabutyl-3,5-dioxa-octane diamide (TBDOODA). The extraction equilibrium is an exothermic reaction. The composition of the extraction complex and the extraction mechanism are also examined

  19. Quantum Simulation and Quantum Sensing with Ultracold Strontium

    Science.gov (United States)

    2015-09-18

    Arlington VA 22203 Approved for public release. We have built an ultra -high vacuum experimental apparatus for trapping and cooling of strontium, demonstrated...isotope source. As the atom trap re- quires ultra -high vacuum, an adequate pressure ratio between the oven and trapping regions is maintained by two 40 L...and a final temperature of approximately 4 mK , which is limited by the relatively broad 32 MHz transition linewidth. Ground state atoms are

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

    Indian Academy of Sciences (India)

    Unknown

    This is in conformity with the IR spectral studies. Table 1 summarizes the decomposition steps and the expected and observed mass losses at different steps for. Sr(C4H4O6)⋅4H2O. Figure 3a illustrates DTA curve recor- ded for strontium tartrate tetrahydrate. The DTA curve was recorded taking 14⋅4 mg of SrT. The heating ...

  1. 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...

  2. Effect of Strontium Nitrate on Extremely Slow Strobe Compositions

    Science.gov (United States)

    2017-01-01

    describes the evaluation of the slow strobe’s pulse rate, based on the mesh size of the metal powder and the effect of the variation of strontium...nitrate and potassium nitrate concentration . Small test pellets of this less-toxic strobe mixture, containing only 10 g of pyrotechnic composition, had...blood and kidneys (5). The perchlorate ion is known to be stable and nonreactive in aqueous systems, which leads to a high persistency in groundwater

  3. 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

  4. Searching Room Temperature Ferromagnetism in Wide Gap Semiconductors Fe-doped Strontium Titanate and Zinc Oxide

    CERN Document Server

    Pereira, LMC; Wahl, U

    Scientific findings in the very beginning of the millennium are taking us a step further in the new paradigm of technology: spintronics. Upgrading charge-based electronics with the additional degree of freedom of the carriers spin-state, spintronics opens a path to the birth of a new generation of devices with the potential advantages of non-volatility and higher processing speed, integration densities and power efficiency. A decisive step towards this new age lies on the attribution of magnetic properties to semiconductors, the building block of today's electronics, that is, the realization of ferromagnetic semiconductors (FS) with critical temperatures above room temperature. Unfruitful search for intrinsic RT FS lead to the concept of Dilute(d) Magnetic Semiconductors (DMS): ordinary semiconductor materials where 3 d transition metals randomly substitute a few percent of the matrix cations and, by some long-range mechanism, order ferromagnetically. The times are of intense research activity and the last fe...

  5. Reduction of to CO in presence of on strontium doped lanthanum ...

    Indian Academy of Sciences (India)

    NEETU KUMARI

    2017-10-26

    Oct 26, 2017 ... polarization resistance indicated an enhanced activity of LSM for CO2 reduction reaction. Furthermore, the cathode polarization resistance for CO2/H2 of 92/08, is observed to be decreased from 16.20 cm2 (OCV. 0.89 V) to ..... Acknowledgements. We acknowledge the financial support of GAIL R&D, and.

  6. 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.

  7. Magnetic transitions and electrical transport in Bi-doped lanthanum strontium manganites

    Science.gov (United States)

    Ahmed, A. M.; Mohamed, H. F.; Šoka, Martin

    2014-05-01

    The temperature dependence of the electrical resistivity ρ, thermoelectric power S and the magnetic susceptibility χ of La0.7-xBixSr0.3MnO3 (x = 0.05, 0.10, and 0.15 at. %) manganites were investigated. La0.7-xBixSr0.3MnO3 crystallizes in a single phase rhombohedral structure with parasitic phase inclusions. With increasing Bi concentration, a systematic decrease in the ferromagnetic transition temperature (Tc), the metal-semiconducting transition temperature (Tms1) and also the values of activation energies Eρ and ES from ρ(T) and S(T) were observed. On the other hand, in the high-temperature (T > Tms) paramagnetic semiconductor regime, the adiabatic small polaron hopping model fit well, thereby indicating that polaron hopping might be responsible for the conduction mechanism. In addition, the thermoelectric power data at low temperatures were analyzed by considering both the magnon and the phonon drag concept, while the high-temperature data were confirmed a small polaron hopping conduction mechanism.

  8. 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

  9. Preparation and properties of porous PMN-PZT ceramics doped with strontium

    International Nuclear Information System (INIS)

    Zeng Tao; Dong Xianlin; Mao Chaoliang; Chen Shutao; Chen Heng

    2006-01-01

    The piezoelectric and dielectric properties of lead magnesium niobate-lead zirconate titanate (PMN-PZT) ceramics were investigated as a function of density for transducer applications. A decrease in density increased elastic compliance and improved acoustic impedance matching between PMN-PZT ceramics and ambient media. The reduced dielectric constant (ε 33 ) and enhanced hydrostatic figure of merit (d h g h ) of PMN-PZT were observed with decreased density. The results showed the d h g h of PMN-PZT ceramic with density of about 5.4 g/cm 3 reached 4000 x 10 -15 m 2 /N, and the ε 33 was very close to 2000, which demonstrates that porous PMN-PZT ceramic is a promising material for transducer applications. Moreover, the low density PMN-PZT ceramics exhibited lower dielectric loss than high density PMN-PZT ceramics during the temperature from 250 deg. C to 500 deg. C

  10. Reduction of to CO in presence of on strontium doped lanthanum ...

    Indian Academy of Sciences (India)

    NEETU KUMARI

    Electrochemical performance of La0.8Sr0.2MnO3−δ (LSM) for CO2 reduction in solid oxide cell is studied by performing impedance ... utilized in a fuel cell as a stable cathode to provide a rea- sonably high power density.18 In ..... perature electrolysis using solid oxide fuel cells: a review. J. Power Sources 203 4. 8. Sun X ...

  11. Effects of Nb and Sr doping on crystal structure of epitaxial BaTiO3 thin films on MgO substrates

    International Nuclear Information System (INIS)

    Kim, Yongsam; Chen, Chunhua; Saiki, Atsushi; Wakiya, Naoki; Shinozaki, Kazuo; Mizutani, Nobuyasu

    2002-01-01

    Niobium (Nb) and strontium (Sr) doped barium titanate (BT) films were deposited by radio frequency (RF) magnetron sputtering with Nb and Sr doped BT ceramic targets, respectively. The effect of Nb and Sr doping on the crystal structure of epitaxial BaTiO 3 thin films on MgO substrates was investigated. The crystal structure of the films was examined using the reciprocal space mapping measurement. All the films exhibit a cube-on-cube relation with respect to the substrates. As the amount of doped Sr increased, both of the in-plane and out-of-plane lattice constants of Sr doped BT films slowly approached the BT bulk values. On the other hand, the lattice constants of Nb doped BT films were rapidly coming close to the bulk values. These indicated that the lattices of doped BT films were relaxed as the amount of doped elements increased. In addition, Nb doping had greater influence on the relaxation of the films than Sr doping for the same content of dopant. (author)

  12. Microwave-hydrothermal synthesis of barium strontium titanate nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Simoes, A.Z., E-mail: alezipo@yahoo.co [Universidade Federal de Itajuba- Unifei - Campus Itabira, Rua Sao Paulo, 377, Bairro, Amazonas, CEP 35900-37, Itabira, MG (Brazil); Universidade Estadual Paulista- Unesp - Faculdade de Engenharia de Guaratingueta, Av. Dr. Ariberto Pereira da Cunha, 333, Bairro Pedregulho, CEP 12516-410 Guaratingueta, SP (Brazil); Moura, F.; Onofre, T.B. [Universidade Federal de Itajuba- Unifei - Campus Itabira, Rua Sao Paulo, 377, Bairro, Amazonas, CEP 35900-37, Itabira, MG (Brazil); Ramirez, M.A.; Varela, J.A.; Longo, E. [Laboratorio Interdisciplinar em Ceramica (LIEC), Departamento de Fisico-Quimica, Instituto de Quimica, UNESP, CEP 14800-900, Araraquara, SP (Brazil)

    2010-10-22

    Research highlights: {yields} Barium strontium titanate nanoparticles were obtained by the Hydrothemal microwave technique (HTMW) {yields} This is a genuine technique to obtain nanoparticles at low temperature and short times {yields} Barium strontium titanate free of carbonates with tetragonal structure was grown at 130 {sup o}C. - Abstract: Hydrothermal-microwave method (HTMW) was used to synthesize crystalline barium strontium titanate (Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3}) nanoparticles (BST) in the temperature range of 100-130 {sup o}C. The crystallization of BST with tetragonal structure was reached at all the synthesis temperatures along with the formation of BaCO{sub 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.

  13. 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

  14. 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.

  15. 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.

  16. 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

  17. 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.)

  18. 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.

  19. 10 CFR 32.103 - Schedule D-prototype tests for ice detection devices containing strontium-90.

    Science.gov (United States)

    2010-01-01

    ... visible evidence of physical contact between the water and the strontium-90. Absolute pressure of the air... water and the strontium-90 shall be considered leakage. (e) Observations. After each of the tests... of strontium-90 per 100 square centimeters of surface wiped or in the water of more than 0.1 percent...

  20. 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

  1. 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...

  2. 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)

  3. 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...

  4. 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...

  5. Determination of strontium transfer coefficients in soil-plant system at nuclear power plant sites

    International Nuclear Information System (INIS)

    Szabova, T.; Bartha, S.; Mitro, A.; Sipko, J.

    1985-01-01

    In the surroundings of the Mochovce and Dukovany nuclear power plants samples were taken of soils and some plants, namely wheat, barley, clover and lucerne. Strontium was determined by flame emission spectrometry. The found strontium transfer coefficients and discrimination factors in the soil-plant system are tabulated for both localities. (E.S.)

  6. Synthesis and characterization of strontium carboxylates at room temperature and at high temperature in autoclave vessels

    DEFF Research Database (Denmark)

    Christgau, Stephan; Ståhl, Kenny; Andersen, Jens Enevold Thaulov

    2006-01-01

    -ray crystallography. Optimum conditions were found at T = 120-1400C, a base-to-acid ratio of 1.2 and 15 min. of reaction-time in an autoclave vessel. Large crystals were readily obtained within a time period of hours. The crystal structures of strontium D-glutamate hexahydrate (I) and strontium di-(hydrogen L...

  7. Enhancement of the luminescence intensity by co-doping Mn{sup 2+} into Er{sup 3+}-doped SrAl{sub 2}O{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Herval, L.K.S. de [Departamento de Física, Universidade Federal de São Carlos (UFSCAR), 13560-905 São Carlos, SP (Brazil); Tuncer Arslanlar, Y.; Ayvacikli, M. [Celal Bayar University, Faculty of Arts and Sciences, Department of Physics, 45010 Muradiye-Manisa (Turkey); Iikawa, F. [Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas (UNICAMP), 13083-859 Campinas, SP (Brazil); Nobrega, J.A.; Pizani, P.S.; Galvão Gobato, Y. [Departamento de Física, Universidade Federal de São Carlos (UFSCAR), 13560-905 São Carlos, SP (Brazil); Can, N. [Celal Bayar University, Faculty of Arts and Sciences, Department of Physics, 45010 Muradiye-Manisa (Turkey); Physics Department, Jazan University, P.O. Box 114, 45142 Jazan (Saudi Arabia); Henini, M. [School of Physics and Astronomy, Nottingham Nanotechnology and Nanoscience Centre, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Godoy, M.P.F. de, E-mail: mgodoy@ufscar.br [Departamento de Física, Universidade Federal de São Carlos (UFSCAR), 13560-905 São Carlos, SP (Brazil)

    2015-07-15

    Structural and optical properties of erbium- and manganese-doped strontium aluminates (SrAl{sub 2}O{sub 4}) phosphor materials synthesized by a solid state reaction were investigated. The samples presented the fundamental optical transitions due to Er{sup 3+} and Mn{sup 2+} which are typical features of the well-diluted doping process. A significant enhancement of the Er{sup 3+} optical emission band at 1530 nm was observed when the matrix is co-doped with Mn. Photoluminescence intensity under ultraviolet excitation was three times larger as compared to samples without Mn content. A model of energy transfer mechanism from Mn{sup 2+} to Er{sup 3+} ions due to optical energy matching is proposed to explain the experimental results. This result, presented first time, can be applied as useful tool for developments in optical communications. - Highlights: • Er-doped and Mn-doped aluminates were synthesized by solid state reaction method. • XRD shows that the dopants do not change the crystal structure of the matrix SrAl{sub 2}O{sub 4}. • The optical matching enhances the emission of Er{sup 3+} under UV excitation. • This improvement in the NIR range is explained by energy transfer from Mn{sup 2+} to Er{sup 3+}.

  8. Theoretical and experimental study of the incorporation of tobramycin and strontium-ions into hydroxyapatite by means of co-precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Baochang [Applied Materials Physics, Department of Materials and Engineering, Royal Institute of Technology (KTH), S 100 44 Stockholm (Sweden); Lilja, Mirjam, E-mail: mirjam.lilja@sandvik.com [Division for Nanotechnology and Functional Materials, The Ångström Laboratory, Uppsala University, 751 21 Uppsala (Sweden); Sandvik Coromant Sverige AB, 12680 Stockholm (Sweden); Ma, Taoran [Applied Materials Physics, Department of Materials and Engineering, Royal Institute of Technology (KTH), S 100 44 Stockholm (Sweden); Sörensen, Jan; Steckel, Hartwig [Department of Pharmaceutics and Biopharmaceutics, Christian Albrecht University Kiel, Kiel (Germany); Ahuja, Rajeev [Condensed Matter Theory, Uppala University (Sweden); Strømme, Maria, E-mail: maria.stromme@angstrom.uu.se [Division for Nanotechnology and Functional Materials, The Ångström Laboratory, Uppsala University, 751 21 Uppsala (Sweden)

    2014-09-30

    Highlights: • We investigate incorporation of tobramycin into hydroxyapatite using co-precipitation by theory and experiment. • The drug molecule shows larger adsorption energy on a submicron HA surface compared to a TiO{sub 2} surface. • Strontium substitution allows for production of thinner coatings with enhanced drug incorporation capacity. - Abstract: Antibiotic incorporation into hydroxyapatite (HA) coatings by co-precipitation and the impact of bone relevant doping elements on the adsorption kinetics are investigated from both theoretical and experimental points of view. Tobramycin interactions with bioactive TiO{sub 2} and HA surfaces are analyzed using density functional theory. According to the calculations, the drug molecule has larger adsorption energy than the Ca{sup +} ion on both surfaces under study in Phosphate Buffered Saline (PBS). The results support the experimental observations that HA nucleation and growth are strongly limited on TiO{sub 2} surfaces in the presence of clinically relevant antibiotic concentrations in PBS. The drug molecule is more likely to adopt parallel arrangement onto the HA surface, as the adsorption energy of such arrangement is higher compared to a perpendicular one. Strontium substitution of the HA surface is found to results in a weaker drug–surface interaction, and leads also to a decrease in coating thickness. However, the presence of strontium gives rise to a coating morphology with enhanced drug incorporation capacity and slower antibiotic release compared to non-substituted, co-precipitated counterparts. Our theoretical calculation results were found to be in excellent agreement with experimental data and provide a powerful tool to understand the interaction mechanism between drug and different surface chemistries necessary for development of future versatile orthopedic and dental implant surfaces.

  9. 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.

  10. 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

  11. 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.)

  12. 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

  13. 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

  14. Doping control in sport

    DEFF Research Database (Denmark)

    Overbye, Marie Birch

    2016-01-01

    Doping testing is a key component enforced by anti-doping authorities to detect and deter doping in sport. Policy is developed to protect athletes' right to participate in doping-free sport; and testing is a key tool to secure this right. Accordingly, athletes' responses to anti-doping efforts.......e., the efforts of stakeholders involved in testing) in their own sport both nationally and worldwide. Moreover, it seeks to identify whether specific factors such as previous experience of testing and perceived proximity of doping have an impact on athletes' perceptions of the testing system. The study comprises...... a web-based questionnaire (N = 645; response rate 43%) and uses qualitative findings to elaborate on and explain quantitative results. Results showed that two-thirds of the athletes reported the national testing programme in their sport to be appropriate. A majority of the athletes who had an opinion...

  15. Composition-structure-properties relationship of strontium borate glasses for medical applications.

    Science.gov (United States)

    Hasan, Muhammad S; Werner-Zwanziger, Ulrike; Boyd, Daniel

    2015-07-01

    We have synthesized TiO2 doped strontium borate glasses, 70B2O3-(30-x)SrO-xTiO2 and 70B2 O3 -20SrO(10-x)Na2 O-xTiO2 . The composition dependence of glass structure, density, thermal properties, durability, and cytotoxicity of degradation products was studied. Digesting the glass in mineral acid and detecting the concentrations of various ions using an ICP provided the actual compositions that were 5-8% deviated from the theoretical values. The structure was investigated by means of (11)B magic angle spinning (MAS) NMR spectroscopy. DSC analyses provided the thermal properties and the degradation rates were measured by measuring the weight loss of glass disc-samples in phosphate buffered saline at 37°C in vitro. Finally, the MTT assay was used to analyze the cytotoxicity of the degradation products. The structural analysis revealed that replacing TiO2 for SrO or Na2 O increased the BO3/BO4 ratio suggesting the network-forming role of TiO2 . Thermal properties, density, and degradation rates also followed the structural changes. Varying SrO content predominantly controlled the degradation rates, which in turn controlled the ion release kinetics. A reasonable control (2-25% mass loss in 21 days) over mass loss was achieved in current study. Even though, very high concentrations (up to 5500 ppm B, and 1200 ppm Sr) of ions were released from the ternary glass compositions that saturated the degradation media in 7 days, the degradation products from ternary glass system was found noncytotoxic. However, quaternary glasses demonstrated negative affect on cell viability due to very high (7000 ppm) Na ion concentration. All the glasses investigated in current study are deemed fast degrading with further control over degradation rates, release kinetics desirable. © 2014 Wiley Periodicals, Inc.

  16. 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

  17. Polarization induced doped transistor

    Science.gov (United States)

    Xing, Huili; Jena, Debdeep; Nomoto, Kazuki; Song, Bo; Zhu, Mingda; Hu, Zongyang

    2016-06-07

    A nitride-based field effect transistor (FET) comprises a compositionally graded and polarization induced doped p-layer underlying at least one gate contact and a compositionally graded and doped n-channel underlying a source contact. The n-channel is converted from the p-layer to the n-channel by ion implantation, a buffer underlies the doped p-layer and the n-channel, and a drain underlies the buffer.

  18. Determination of strontium in rocks by atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Tamari, Yuzo; Tsuji, Haruo; Kusaka, Yuzuru

    1984-01-01

    Strontium in silicate rocks was determined by the following procedure. A rock powder sample prepared to pass through a 100-mesh size sieve (0.1--0.5g) was taken in a Teflon beaker, and 6ml of 46% hydrofluoric acid and 1 ml of 70% perchloric acid were added. After being allowed to stand for over one day, the mixture in the beaker was concentrated by heating on a hot plate until white fumes of the perchloric acid appeared. The content in the beaker was transferred to a glass beaker with 2ml of 61% nitric acid and 0.5ml of the perchloric acid, and concentrated until white fumes appeared. Further, 2ml of 20% hydrochloric acid was added and warmed. After cooling, the rock solution was made up to 100ml with water. To a 50-ml stoppered centrifugal tube, a 10-ml portion of the rock solution was transferred, and 1ml of 2% 8-quinolinol solution was added. Then the solution was adjusted to pH 5 with both saturated sodium acetate solution and hydrochloric acid, and made up to 15ml. The decomposed rock sample solution with 20ml of chloroform was shaken for 5min. The decomposed rock sample solution was shaken with 20ml of chloroform for 5min, and then centrifuged at 2500rpm for 5min to separate an aqueous phase from an organic one. After adding 1ml of 2% lanthanum solution into a 10ml portion of the aqueous phase, strontium was determined by atomic absorption spectrometry at 460.7nm. This method was applied to the rock reference materials, JB-1 and JG-1, issued from the Geological Survey of Japan. Analytical values of strontium in the rocks were almost consistent with their certified and recommended values. (author)

  19. Synthesis and magnetic properties of strontium hexaferrite from celestite ore

    Energy Technology Data Exchange (ETDEWEB)

    Hessien, M.M. [Central Metallurgical Research and Development Institute (CMRDI), P.O. Box 87 Helwan, Cairo (Egypt)], E-mail: hessienmahmoud@yahoo.com; Rashad, M.M.; Hassan, M.S.; El-Barawy, K. [Central Metallurgical Research and Development Institute (CMRDI), P.O. Box 87 Helwan, Cairo (Egypt)

    2009-05-12

    Nanocrystalline strontium hexaferrite (SrFe{sub 12}O{sub 19}) powders have been synthesized from Egyptian celestite ore (SrSO{sub 4}), as a source of strontium, via co-precipitation route. The raw celestite ore was first dissolved in hydrochloric acid to remove about 10% CaO and the acid soluble impurities associated with the ore. Then, the treated celestite was washed and dried followed by a reduction with carbon to give acid-water soluble strontium sulfide SrS. The ferrite precursors were obtained from a precipitation of the produced SrS dissolved in dil. HCl and pure ferric chloride at pH 10 using 5 M sodium hydroxide. These precursors were annealed at 1000 deg. C for constant time 2 h in open atmosphere. The effect of Fe{sup 3+}/Sr{sup 2+} mole ratio on the formation, crystallite size, morphology and magnetic properties were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and VSM, respectively. The results obtained showed that the single phase SrFe{sub 12}O{sub 19} powders was achieved at the Fe{sup 3+}/Sr{sup 2+} mole ratios 8.57 and 8.00 at annealing temperature 1000 deg. C for 2 h. The maximum saturation magnetization (74.15 emu/g) was achieved at the Fe{sup 3+}/Sr{sup 2+} mole ratio to 8.57 and annealing temperature 1000 deg. C due to the formation of a uniform-like hexagonal shape structure. Moreover, wide coercivities can be obtained at different synthesis conditions (2011-3504 Oe)

  20. Theoretical and experimental study of the incorporation of tobramycin and strontium-ions into hydroxyapatite by means of co-precipitation

    Science.gov (United States)

    Wang, Baochang; Lilja, Mirjam; Ma, Taoran; Sörensen, Jan; Steckel, Hartwig; Ahuja, Rajeev; Strømme, Maria

    2014-09-01

    Antibiotic incorporation into hydroxyapatite (HA) coatings by co-precipitation and the impact of bone relevant doping elements on the adsorption kinetics are investigated from both theoretical and experimental points of view. Tobramycin interactions with bioactive TiO2 and HA surfaces are analyzed using density functional theory. According to the calculations, the drug molecule has larger adsorption energy than the Ca+ ion on both surfaces under study in Phosphate Buffered Saline (PBS). The results support the experimental observations that HA nucleation and growth are strongly limited on TiO2 surfaces in the presence of clinically relevant antibiotic concentrations in PBS. The drug molecule is more likely to adopt parallel arrangement onto the HA surface, as the adsorption energy of such arrangement is higher compared to a perpendicular one. Strontium substitution of the HA surface is found to results in a weaker drug-surface interaction, and leads also to a decrease in coating thickness. However, the presence of strontium gives rise to a coating morphology with enhanced drug incorporation capacity and slower antibiotic release compared to non-substituted, co-precipitated counterparts. Our theoretical calculation results were found to be in excellent agreement with experimental data and provide a powerful tool to understand the interaction mechanism between drug and different surface chemistries necessary for development of future versatile orthopedic and dental implant surfaces.

  1. Influence of nickel substitution on crystal structure and magnetic properties of strontium ferrite preparation via sol-gel auto-combustion route

    Science.gov (United States)

    Roohani, Ebrahim; Arabi, Hadi; Sarhaddi, Reza

    2018-01-01

    In this research, SrFe12‑xNixO19 (x = 0 ‑ 1) hexagonal ferrites were prepared by sol-gel auto-combustion method. Effect of Ni substitution on structural, morphological and magnetic properties of nanoparticles was investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM), respectively. The XRD results confirmed that all samples with x ≤ 0.5 have single phase M-type strontium ferrite structure, whereas for the SrFe12‑xNixO19 samples with x > 0.5, the spinel NiFe2O4 phase has also appeared. The lattice parameters and crystallite sizes of the powders were concluded from the XRD data and Williamson-Hall method. Magnetic analyses showed that the coercivity of powders decreased from 5672 Oe to 639 Oe while the saturation magnetization increased from 74 emu/g to 81 emu/g with nickel substitution. The results of this study suggest that the strontium hexaferrites doped with Ni are suitable for applications in high density magnetic recording media as well as microwave devices because of their promising magnetic properties.

  2. Frequency stability measurement of pulsed superradiance from strontium

    Science.gov (United States)

    Norcia, Matthew; Cline, Julia; Robinson, John; Ye, Jun; Thompson, James

    2017-04-01

    Superradiant laser light from an ultra-narrow optical transition holds promise as a next-generation of active frequency references. We have recently demonstrated pulsed lasing on the milliHertz linewidth clock transition in strontium. Here, we present the first frequency comparisons between such a superradiant source and a state of the art stable laser system. We characterize the stability of the superradiant system, and demonstrate a reduction in sensitivity to cavity frequency fluctuations of nearly five orders of magnitude compared to a conventional laser. DARPA QUASAR, NIST, NSF PFC.

  3. 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)

  4. 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)

  5. Migration Behaviour of Strontium in Czech Bentonite Clay

    OpenAIRE

    Lucie Baborova; Dušan Vopálka; Eva Hofmanová; Aleš Vetešník

    2016-01-01

    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 th...

  6. 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

  7. 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

  8. Enhanced flexoelectricity through residual ferroelectricity in barium strontium titanate

    International Nuclear Information System (INIS)

    Garten, Lauren M.; Trolier-McKinstry, Susan

    2015-01-01

    Residual ferroelectricity is observed in barium strontium titanate ceramics over 30 °C above the global phase transition temperature, in the same temperature range in which anomalously large flexoelectric coefficients are reported. The application of a strain gradient leads to strain gradient-induced poling or flexoelectric poling. This was observed by the development of a remanent polarization in flexoelectric measurements, an induced d 33 piezoelectric response even after the strain gradient was removed, and the production of an internal bias of 9 kV m −1 . It is concluded that residual ferroelectric response considerably enhances the observed flexoelectric response

  9. Enhanced flexoelectricity through residual ferroelectricity in barium strontium titanate

    Energy Technology Data Exchange (ETDEWEB)

    Garten, Lauren M., E-mail: lmg309@psu.edu; Trolier-McKinstry, Susan [Department of Materials Science and Engineering and Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2015-03-07

    Residual ferroelectricity is observed in barium strontium titanate ceramics over 30 °C above the global phase transition temperature, in the same temperature range in which anomalously large flexoelectric coefficients are reported. The application of a strain gradient leads to strain gradient-induced poling or flexoelectric poling. This was observed by the development of a remanent polarization in flexoelectric measurements, an induced d{sub 33} piezoelectric response even after the strain gradient was removed, and the production of an internal bias of 9 kV m{sup −1}. It is concluded that residual ferroelectric response considerably enhances the observed flexoelectric response.

  10. Enhanced flexoelectricity through residual ferroelectricity in barium strontium titanate

    Science.gov (United States)

    Garten, Lauren M.; Trolier-McKinstry, Susan

    2015-03-01

    Residual ferroelectricity is observed in barium strontium titanate ceramics over 30 °C above the global phase transition temperature, in the same temperature range in which anomalously large flexoelectric coefficients are reported. The application of a strain gradient leads to strain gradient-induced poling or flexoelectric poling. This was observed by the development of a remanent polarization in flexoelectric measurements, an induced d33 piezoelectric response even after the strain gradient was removed, and the production of an internal bias of 9 kV m-1. It is concluded that residual ferroelectric response considerably enhances the observed flexoelectric response.

  11. 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

  12. The effect of CHA-doped Sr addition to the mechanical strength of metakaolin dental implant geopolymer composite

    Science.gov (United States)

    Sunendar, Bambang; Fathina, Afiya; Harmaji, Andrie; Mardhian, Deby Fajar; Asri, Lia; Widodo, Haris Budi

    2017-09-01

    The prospective material for implant plate required sufficient mechanical properties to maintain fracture fixation and resist physiological stress until bone healing process finished. Various problem implant plate based on metal and polymer materials when used as fixation for bone defect case induced developmental of bioceramic for implant plate materials. Materials that now has been attract a lot of attention is carbonate apatite and strontium as doping which known to have good biocompability along with biointegrity and mechanical charateristics. Other materials that have been known to have good mechanical properties are metakaolin and use of chitosan as coupling agent. Metakaolin and carbonate apatite can be produced by sol-gel methode which simpler, economical and energy-saving procedure furthermore use of chitosan which is widely found in the nature of Indonesia can be used to encourage the utilization of natural resources. The aim fo this paper is to investigated effect of CHA-doped Sr 5 (%) mol addition to the mechanical strength of metakaolin dental implant geoploymer composite. In this paper metakaolin is used as geopolymerization precursors. The test results have shown that addition of filler of apatite carbonate doped 5% mol strontium can be said to increase the value of mechnical properties but high concentration of calcium in the nanocomposite also can complicate the equilibrium of the geopolymerization process and induce alkali aggregate reactivity (AAR). The sample group of nanocomposite of metakaolin and carbonate apatite-doped 5% mol strontium (2: 1% wt) with 2% chitosan as a coupling agent based on geopolymerization for implant plate application has the best mechanical properties among all sample groups but does not qualify as an implant plate on cortical bone but can be used for the application of the implant plate on the trabecular bone specifically and potentially as a bone initiator.

  13. Isolation of strontium pools and isotope ratios in modern human hair

    Energy Technology Data Exchange (ETDEWEB)

    Tipple, Brett J., E-mail: brett@isoforensics.com [IsoForensics Inc, 421 Wakara Way, Suite 100, Salt Lake City, UT 84108 (United States); University of Utah, Department of Biology, 257 South 1400 East, Salt Lake City, UT 84112 (United States); Chau, Thuan [IsoForensics Inc, 421 Wakara Way, Suite 100, Salt Lake City, UT 84108 (United States); Chesson, Lesley A. [IsoForensics Inc, 421 Wakara Way, Suite 100, Salt Lake City, UT 84108 (United States); University of Utah, Department of Biology, 257 South 1400 East, Salt Lake City, UT 84112 (United States); Fernandez, Diego P. [University of Utah, Department of Geology and Geophysics, 115 South 1460 East, Salt Lake City, UT 84112 (United States); Ehleringer, James R. [IsoForensics Inc, 421 Wakara Way, Suite 100, Salt Lake City, UT 84108 (United States); University of Utah, Department of Biology, 257 South 1400 East, Salt Lake City, UT 84112 (United States)

    2013-10-10

    Graphical abstract: -- Highlights: •Analytical methodologies were developed to analyze the {sup 87}Sr/{sup 86}Sr ratio of human hair. •Interior and exterior Sr signals to human hair were distinguished. •Environmental {sup 87}Sr/{sup 86}Sr signals could be isolated from internal {sup 87}Sr/{sup 86}Sr signatures. •{sup 87}Sr/{sup 86}Sr ratios across the transverse cross-section profile of a hair varied. •Cleaning method must be considered when comparing {sup 87}Sr/{sup 86}Sr ratios of hair. -- Abstract: The elements of human hair record specific information about an individual's health, diet, and surrounding environment. Strontium isotope ratios of human hair have attracted interest as they potentially record an individual's environment. Yet, separating the external environmental signals from the internal dietary indicators has remained a challenge. Here, we examined the effects of five different hair-cleaning methodologies to determine the extent that internal and external strontium signals can be isolated from human hair. In the first study of its kind, we employed an in-line strontium purification methodology and a multi-collector inductively coupled plasma mass spectrometer to obtain high-precision strontium isotope ratio of human hair and of leachates of the different washing treatments. We found that the different applications of an individual treatment removed a consistent amount of strontium from hair and that replicate analyses showed each treatment altered the strontium isotope ratios of hair consistently. A mass-balance approach was applied to demonstrate that strontium was quantitatively removed and was accounted for in either the treated hair or the leachate. We observed that strontium isotope ratio varied as a function of treatment aggressiveness so as to suggest that there was a fine-scale structuring of strontium within hair (transverse cross-sectional variations); these variations existed as differences in strontium concentrations

  14. Isolation of strontium pools and isotope ratios in modern human hair

    International Nuclear Information System (INIS)

    Tipple, Brett J.; Chau, Thuan; Chesson, Lesley A.; Fernandez, Diego P.; Ehleringer, James R.

    2013-01-01

    Graphical abstract: -- Highlights: •Analytical methodologies were developed to analyze the 87 Sr/ 86 Sr ratio of human hair. •Interior and exterior Sr signals to human hair were distinguished. •Environmental 87 Sr/ 86 Sr signals could be isolated from internal 87 Sr/ 86 Sr signatures. • 87 Sr/ 86 Sr ratios across the transverse cross-section profile of a hair varied. •Cleaning method must be considered when comparing 87 Sr/ 86 Sr ratios of hair. -- Abstract: The elements of human hair record specific information about an individual's health, diet, and surrounding environment. Strontium isotope ratios of human hair have attracted interest as they potentially record an individual's environment. Yet, separating the external environmental signals from the internal dietary indicators has remained a challenge. Here, we examined the effects of five different hair-cleaning methodologies to determine the extent that internal and external strontium signals can be isolated from human hair. In the first study of its kind, we employed an in-line strontium purification methodology and a multi-collector inductively coupled plasma mass spectrometer to obtain high-precision strontium isotope ratio of human hair and of leachates of the different washing treatments. We found that the different applications of an individual treatment removed a consistent amount of strontium from hair and that replicate analyses showed each treatment altered the strontium isotope ratios of hair consistently. A mass-balance approach was applied to demonstrate that strontium was quantitatively removed and was accounted for in either the treated hair or the leachate. We observed that strontium isotope ratio varied as a function of treatment aggressiveness so as to suggest that there was a fine-scale structuring of strontium within hair (transverse cross-sectional variations); these variations existed as differences in strontium concentrations and isotope ratios. As a result, the Sr isotope ratio

  15. 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.

  16. Studies on Nano Barium Strontium Titanate/Cellulose Derivatives Composites

    Directory of Open Access Journals (Sweden)

    Y. Hamzeh

    2009-12-01

    Full Text Available Studies were carried out on the preparation and properties of the composites made from cellulose acetate butyrate and cellulose acetate propionate with various amounts of barium strontium titanate nano-particle. The nano-particles of barium strontium titanate (BST with formulation of Ba0.77Sr0.23TiO3 were made by sol-gel method and their purity and particle size were analyzed by X-ray diffraction (XRD. The composites were prepared with BST nano-particle loading of 10 to 50 vol%, and their distribution in the composites studied using SEM imaging. The dielectric constant of the composites was measured at 1 kHz and 100 kHz at room temperature. It was found that the adopted procedure produced dense and uniform composites. The dielectric constant of the composites increased with the solid contentof BST and followed the modified Lichtenecker equation. The increasing rate of dielectric constant with increased BST content was more pronounced for the BST/CAP composite. The dielectric constant of the composites decreased withincreasing the frequency which was more obvious at higher loading of BST nano-particle

  17. Studies on the Inhibition of Intestinal Absorption of Radioactive Strontium

    Science.gov (United States)

    Waldron-Edward, Deirdre; Paul, T. M.; Skoryna, Stanley C.

    1964-01-01

    A method is reported which permits selective suppression of absorption of radioactive strontium from ingested food material, permitting calcium to be available to the body. Studies were carried out by measuring bone uptake of Sr89 and Ca45 when various amounts of sodium alginate were fed with the diet. Long-term studies were made in which two different levels of radioactivity were used, to determine the pattern of Sr89 deposition with continuous intake of binding agent. It was found that administration of sodium alginate as a jelly overcomes the problem of constipation and effectively reduces Sr89 uptake, up to 83%. This fact represents a significant finding with respect to the use of the compound in human subjects. Addition of sodium alginate to drinking water is effective with low levels of Sr89 intake. This naturally occurring water-soluble macromolecular substance possesses several advantages in use for the suppression of absorption of radioactive strontium when compared with synthetic ion exchange resins: there is no disturbance of electrolyte balance; efficiency is not reduced by treatment over a prolonged period of time; and finally, the product is palatable. PMID:14222668

  18. 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.

  19. Strontium leachability of hydrofracture grouts for sludge-slurries

    International Nuclear Information System (INIS)

    Morgan, M.T.; McDaniel, E.W.; Moore, J.G.; Devaney, H.E.; Dole, L.R.

    1982-01-01

    A series of experiments to determine the strontium leachability of cement-based sludge-slurry hydrofracture grouts is summarized. The hydrofracture process has been used at ORNL since 1966 for the routine disposal of intermediate-level waste (ILW) solutions. In this process, cement and other additives are mixed with a waste stream to form grout, which is then injected into a shale bed at a pressure sufficient to cause fracturing along the horizontal bedding planes. This injected grout soon hardens, fixing the radionuclides between layers of the massive Conasauga shale formation. Modified IAEA dynamic leach tests on hydrofracture grout specimens showed improved leach resistance (by a factor of 3 to 5) as the curing time increased from 28 d to 91 d. A weak trend toward lower leachability with increased amounts of dry solids was observed. The moving boundary-plus-diffusion leach model fits the dynamic leach data successfully in most cases. An apparent diffusion coefficient of 5 x 10 - 12 cm 2 /s and a moving boundary coefficient of 1 x 10 - 7 s - 1 were obtained when one of the best grout compositions was leached in distilled water. Assuming that vertical fractures produce the leachable surfaces in a grout sheet, the release rate of strontium calculated with these coefficients is well below the NRC maximum of 10 - 5 fraction per year

  20. 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.

  1. 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.

  2. [Doping and sports].

    Science.gov (United States)

    Lippi, G; Guidi, G

    1999-09-01

    Doping is widely known as the use of banned substances and practices by athletes in an attempt to improve sporting performances. The term doping likely derives from "dope", an ancient expression referred to a primitive alcoholic drink that was used as a stimulant in South African ceremonial dances; gradually, the term was extended and finally adopted his current significance. There are at least two essential reasons to support the fight against doping: the potential harmful effects on athletes and the depth corruption of the fair competition. An exhaustive list of banned substances and methods has been drawn by the International Olympic Committee and further accepted by other International Sport Authorities and Federations. This list, regularly updated, is basically divided into doping substances (stimulants, narcotic analgesics, anabolic agents, diuretics, peptide and glycoprotein hormones and analogues), doping methods (blood doping, pharmacological, chemical and physical manipulation) and drugs subjected to certain restrictions (alcohol, marijuana, local anesthetics, corticosteroids and beta-blockers). Although there might be some medical conditions, which could legitimate the need of these substances or methods, there is no place for their use in sport. Thus, an athlete's consume of any of these substances or methods will result in disqualification. Aim of the present review is to provide a synthetic description of both the desirable effects and the potentially harmful consequences of the use of some of the major doping substances and methods.

  3. 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

  4. 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.

  5. 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

  6. Pore-Scale Transport of Strontium During Dynamic Water Content Changes in the Unsaturated Zone

    Science.gov (United States)

    Weaver, W.; Kibbey, T. C. G.; Papelis, C.

    2016-12-01

    Dynamic water content changes in the unsaturated zone caused by natural and manmade processes, such as evaporation, rainfall, and irrigation, have an effect on contaminant mobility. In general, in the unsaturated zone, evaporation causes an increase in contaminant concentrations, potentially leading to sorption of contaminants on aquifer materials or precipitation of crystalline or amorphous phases. On the other hand, increase of water content may result in dissolution of precipitated phases and increased mobility of contaminants. The objective of this study was to develop a quantitative model for the transport of strontium through sand under dynamic water content conditions, as a function of strontium concentration, pH, and ionic strength. Strontium was selected as a surrogate for strontium-90, a by-product of nuclear reactions. The dynamic water content was determined using an automated device for rapidly measuring the hysteretic capillary pressure—saturation relationship, followed by ambient air evaporation, and gravimetric water content measurement. Strontium concentrations were measured using inductively coupled plasma mass spectrometry (ICP-MS). Flow interruption experiments were conducted to determine whether equilibrium conditions existed for a given flowrate. Scanning electron microscopy (SEM) was used to visualize the treated quartz sand particles and the distribution of strontium on sand grains was determined using elemental maps created by energy-dispersive x-ray spectroscopy (EDX). Strontium behavior appears to be pH dependent as well as ionic strength dependent under these conditions.

  7. Doped graphene supercapacitors

    Science.gov (United States)

    Ashok Kumar, Nanjundan; Baek, Jong-Beom

    2015-12-01

    Heteroatom-doped graphitic frameworks have received great attention in energy research, since doping endows graphitic structures with a wide spectrum of properties, especially critical for electrochemical supercapacitors, which tend to complement or compete with the current lithium-ion battery technology/devices. This article reviews the latest developments in the chemical modification/doping strategies of graphene and highlights the versatility of such heteroatom-doped graphitic structures. Their role as supercapacitor electrodes is discussed in detail. This review is specifically focused on the concept of material synthesis, techniques for electrode fabrication and metrics of performance, predominantly covering the last four years. Challenges and insights into the future research and perspectives on the development of novel electrode architectures for electrochemical supercapacitors based on doped graphene are also discussed.

  8. Direct Local Measurement of the Superconducting Energy Gap of Nb doped SrTiO3

    Science.gov (United States)

    Ha, Jeonghoon; Khalsa, Guru; Natterer, Fabian; Baek, Hongwoo; Cullen, William G.; Kuk, Young; Stroscio, Joseph A.

    Strontium titanate (STO) is a perovskite metal oxide insulator that can be electron doped by substitution of Ti or Sr sites with Nb or La, respectively, or by oxygen vacancies. When doped to high electron densities with concentration in the range of 5x1019 cm- 3 to 2x1020 cm-3, STO becomes superconducting with a transition temperature below 400 mK, at a value highly dependent on the doping concentration. Previous observations were made on bulk crystals or films of doped STO by measuring the transitions in resistivity, magnetic susceptibility or thermal conductivity as a function of temperature or magnetic field. In this work, we use an ultra-low temperature scanning tunneling microscope(STM) to investigate the local electronic structure of the surface of Nb doped STO. The tunneling spectra taken at a sample temperature of ~10 mK reveal a BCS energy gap of Δ = 40 ueV. Temperature and magnetic field dependent tunneling measurements show a critical temperature of ~250 mK and upper critical field of ~0.07 T. This is the first report of direct measurement of superconducting STO using an STM.

  9. To dope or not to dope

    DEFF Research Database (Denmark)

    Overbye, Marie Birch; Knudsen, Mette Lykke; Pfister, Gertrud Ursula

    2013-01-01

    tAim: This study aims to examine the circumstances which athletes say affect their (hypothetical) consid-erations of whether to dope or not and explore the differences between athletes of different gender, ageand sport type.Methods: 645 elite athletes (mean age: 22.12; response rate: 43%) represe......tAim: This study aims to examine the circumstances which athletes say affect their (hypothetical) consid-erations of whether to dope or not and explore the differences between athletes of different gender, ageand sport type.Methods: 645 elite athletes (mean age: 22.12; response rate: 43...... a more decisive factor. Top incentives were related toqualified medical assistance, improved health or faster recovery from injury, the low risk of being caughtand the threat posed to an elite career.Conclusions: Our results reveal that numerous circumstances affect athletes’ thoughts on doping...

  10. Osteogenic efficacy of strontium hydroxyapatite micro-granules in osteoporotic rat model.

    Science.gov (United States)

    Chandran, Sunitha; Babu S, Suresh; Vs, Hari Krishnan; Varma, H K; John, Annie

    2016-10-01

    Excessive demineralization in osteoporotic bones impairs its self-regeneration potential following a defect/fracture and is of great concern among the aged population. In this context, implants with inherent osteogenic ability loaded with therapeutic ions like Strontium (Sr 2+ ) may bring forth promising outcomes. Micro-granular Strontium incorporated Hydroxyapatite scaffolds have been synthesized and in vivo osteogenic efficacy was evaluated in a long-term osteoporosis-induced aged (LOA) rat model. Micro-granules with improved surface area are anticipated to resorb faster and together with the inherent bioactive properties of Hydroxyapatite with the leaching of Strontium ions from the scaffold, osteoporotic bone healing may be promoted. Long-term osteoporosis-induced aged rat model was chosen to extrapolate the results to clinical osteoporotic condition in the aged. Micro-granular 10% Strontium incorporated Hydroxyapatite synthesized by wet precipitation method exhibited increased in vitro dissolution rate and inductively coupled plasma studies confirmed Strontium ion release of 0.01 mM, proving its therapeutic potential for osteoporotic applications. Wistar rats were induced to long-term osteoporosis-induced aged model by ovariectomy along with a prolonged induction period of 10 months. Thereafter, osteogenic efficacy of Strontium incorporated Hydroxyapatite micro-granules was evaluated in femoral bone defects in the long-term osteoporosis-induced aged model. Post eight weeks of implantation in vivo regeneration efficacy ratio was highest in the Strontium incorporated Hydroxyapatite implanted group (0.92 ± 0.04) compared to sham and Hydroxyapatite implanted group. Micro CT evaluation further substantiated the improved osteointegration of Strontium incorporated Hydroxyapatite implants from the density histograms. Thus, the therapeutical potential of micro-granular Strontium incorporated Hydroxyapatite scaffolds becomes relevant, especially as bone void

  11. 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

  12. 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...

  13. 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

  14. 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...

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

    DEFF Research Database (Denmark)

    Hagen, Anke

    2011-01-01

    The potential NOx-reduction electro catalyst lanthanum strontium cuprate has been characterized with an in situ X-ray spectrochemical gas reaction cell. In a series of samples with increasing substitution of trivalent lanthanum by divalent strontium ions, the oxidation state of copper increased......, 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...

  16. 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

  17. Surface Complexation Model for Strontium Sorption to Amorphous Silica and Goethite

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, S; Robers, S; Criscenti, L; O' Day, P

    2007-11-30

    Strontium sorption to amorphous silica and goethite was measured as a function of pH and dissolved strontium and carbonate concentrations at 25 C. Strontium sorption gradually increases from 0 to 100% from pH 6 to 10 for both phases and requires multiple outer-sphere surface complexes to fit the data. All data are modeled using the triple layer model and the site-occupancy standard state; unless stated otherwise all strontium complexes are mononuclear. Strontium sorption to amorphous silica in the presence and absence of dissolved carbonate can be fit with tetradentate Sr{sup 2+} and SrOH{sup +} complexes on the {beta}-plane and a monodentate Sr{sup 2+} complex on the diffuse plane to account for strontium sorption at low ionic strength. Strontium sorption to goethite in the absence of dissolved carbonate can be fit with monodentate and tetradentate SrOH{sup +} complexes and a tetradentate binuclear Sr{sup 2+} species on the {beta}-plane. The binuclear complex is needed to account for enhanced sorption at high strontium surface loadings. In the presence of dissolved carbonate additional monodentate Sr{sup 2+} and SrOH{sup +} carbonate surface complexes on the {beta}-plane are needed to fit strontium sorption to goethite. Modeling strontium sorption as outer-sphere complexes is consistent with quantitative analysis of extended X-ray absorption fine structure (EXAFS) on selected sorption samples that show a single first shell of oxygen atoms around strontium indicating hydrated surface complexes at the amorphous silica and goethite surfaces. Strontium surface complexation equilibrium constants determined in this study combined with other alkaline earth surface complexation constants are used to recalibrate a predictive model based on Born solvation and crystal-chemistry theory. The model is accurate to about 0.7 log K units. More studies are needed to determine the dependence of alkaline earth sorption on ionic strength and dissolved carbonate and sulfate

  18. Surface complexation model for strontium sorption to amorphous silica and goethite

    Directory of Open Access Journals (Sweden)

    Criscenti Louise J

    2008-01-01

    Full Text Available Abstract Strontium sorption to amorphous silica and goethite was measured as a function of pH and dissolved strontium and carbonate concentrations at 25°C. Strontium sorption gradually increases from 0 to 100% from pH 6 to 10 for both phases and requires multiple outer-sphere surface complexes to fit the data. All data are modeled using the triple layer model and the site-occupancy standard state; unless stated otherwise all strontium complexes are mononuclear. Strontium sorption to amorphous silica in the presence and absence of dissolved carbonate can be fit with tetradentate Sr2+ and SrOH+ complexes on the β-plane and a monodentate Sr2+complex on the diffuse plane to account for strontium sorption at low ionic strength. Strontium sorption to goethite in the absence of dissolved carbonate can be fit with monodentate and tetradentate SrOH+ complexes and a tetradentate binuclear Sr2+ species on the β-plane. The binuclear complex is needed to account for enhanced sorption at hgh strontium surface loadings. In the presence of dissolved carbonate additional monodentate Sr2+ and SrOH+ carbonate surface complexes on the β-plane are needed to fit strontium sorption to goethite. Modeling strontium sorption as outer-sphere complexes is consistent with quantitative analysis of extended X-ray absorption fine structure (EXAFS on selected sorption samples that show a single first shell of oxygen atoms around strontium indicating hydrated surface complexes at the amorphous silica and goethite surfaces. Strontium surface complexation equilibrium constants determined in this study combined with other alkaline earth surface complexation constants are used to recalibrate a predictive model based on Born solvation and crystal-chemistry theory. The model is accurate to about 0.7 log K units. More studies are needed to determine the dependence of alkaline earth sorption on ionic strength and dissolved carbonate and sulfate concentrations for the development of

  19. Knudsen cell-mass spectroscopic studies of strontium vapour pressures over strontium oxide/uranium dioxide mixtures and solid solutions

    International Nuclear Information System (INIS)

    Sunder, S.; O'Connor, R.F.

    2003-01-01

    High temperature, Knudsen cell-mass spectroscopic (KC-MS) experiments were performed to determine the volatility of strontium oxide dissolved in UO 2 fuel. KC-MS experiments were carried out with finely ground and pre-heated mixtures of SrO and UO 2 and 'solid solutions' of SrO in UO 2 , prepared using the sob-gel method. It was found that the main strontium gaseous species over these samples was Sr atoms. The KC-MS experiments showed that the vapour pressures of Sr over pre-heated-mixtures of SrO and UO 2 , at high temperatures, were similar to those over pure SrO. The vapour pressures of Sr, over 'sol-gel prepared solid solutions' of compositions SrO:UO 2 equal to 1:100 and 2:100 were similar to each other and to those reported over pure SrO by Lamoreaux et al. (for congruent vapourization); but were lower than those over pure SrO observed in this work, and over SrUO 3 reported by Huang et al. and Yamawaki et al. (author)

  20. The effect of the host composition on the lifetime decay properties of barium/strontium aluminates compounds

    International Nuclear Information System (INIS)

    Rezende, Marcos V. dos S.; Andrade, A. B.; Valerio, Mário E. G.; Montes, Paulo J. R

    2014-01-01

    This paper reports the influence of the structural change on the luminescence of Eu-doped barium/strontium aluminates when excited with monochromatic X-rays (also known as X-ray excited optical luminescence—XEOL). Ba 1−x Sr x Al 2 O 4 samples, with 0  2+ and Eu 3+ transitions, although no Eu 2+ was observed in the X-ray absorption spectra. The XEOL intensities while the sample is under irradiation decreased as a function of the irradiation time, indicating the buildup of radiation damage. The saturation level of the XEOL is directly correlated to the amount of damages induced by the irradiation and the sample composition. The Ba-rich samples are the ones with higher XEOL yield. X-ray induced long lasting phosphorescence (LLP) was also observed for all samples and it was found that the duration of the phosphorescence emission also depends on the sample composition. In Sr-rich samples, the LLP has a slower decay time constant than in Ba-rich samples. A model of the radiation induced luminescence is presented and all these features are discussed in terms of the energetic costs and the type of defects generated in the sample

  1. Magnetic and electrical properties of M-type nano-strontium hexaferrite prepared by sol-gel combustion method

    Science.gov (United States)

    Naeem Ashiq, Muhammad; Sami Asi, Abdul; Farooq, Saima; Najam-ul-Haq, Muhammad; Rehman, Sidra

    2017-12-01

    Herein, we report the synthesis of M-type nano-strontium hexaferrites co-doped with hetrovalent cations (Dy-Ni) having composition Sr(1-x)DyxFe12-yNiyO19 (x = 0.00-0.20, y = 0.00-0.80). The synthesized compounds were analyzed by XRD, FE-SEM, VSM, along with electrical resistivity and dielectric property analyses. XRD peak patterns revealed the magnetoplumbite-type hexagonal crystal structure of the synthesized materials. The SEM micrographs reflected the spherical and hexagonal shaped particles with an average size 40-50 nm. The magnetic squareness ratio (Mr/Ms) of the synthesized nano-ferrites particles lies in the range of 0.60-0.68 assuring their single magnetic domain nature. The rise in the values of saturation magnetization, remanence and coercivity reflect that the fabricated compounds can be beneficial for the perpendicular magnetic recording media. Both the electrical resistivity increment and decrease in dielectric energy loss with increasing Dy-Ni substitution level authenticates that such materials can find applications in magnetic recording media and microwave device fabrication.

  2. Effects of strontium and titanium on the microstructure, tensile properties and creep behavior of AM50 alloys

    International Nuclear Information System (INIS)

    Zhao Peng; Wang Qudong; Zhai Chunquan; Zhu Yanping

    2007-01-01

    The microstructure, tensile properties and creep behavior of Mg-5Al based alloys with strontium and titanium additions were investigated. Small additions of strontium mainly dissolved into Mg 17 Al 12 particles and increased the thermal stability and creep strength, since they did not cause the formation of any new phase in the microstructure. Small additions of strontium could refine the as-cast microstructure and improve the mechanical properties. A strontium addition higher than 0.4 wt% could result in Al 4 Sr phase information, which suppressed the formation of Mg 17 Al 12 phases. Addition of 1% strontium decreased the tensile strength and elongation though improved the yield strength at room temperature. However, greater amounts of strontium can improve the mechanical properties at high temperature. Creep strength of the alloy increased with the strontium content. Further additions of Ti increased the alloy mechanical properties both at room and high temperature though slightly reduce the creep strength. Creep mechanisms of alloys with 0.1% and 1% strontium for different temperature/stress regimes were proposed, which showed that the alloys underwent different creep mechanisms with the change of strontium content. These observations indicated that alloys show two different strengthening mechanisms in the strontium content range of 0.02-1 wt%

  3. Removal of strontium from drinking water by conventional treatment and lime softening in bench-scale studies.

    Science.gov (United States)

    O'Donnell, Alissa J; Lytle, Darren A; Harmon, Stephen; Vu, Kevin; Chait, Hannah; Dionysiou, Dionysios D

    2016-10-15

    The United States Environmental Protection Agency Contaminant Candidate List 3 lists strontium as a contaminant for potential regulatory consideration in drinking water. Very limited data is available on strontium removal from drinking water and as a result, there is an immediate need for treatment information. The objective of this work is to evaluate the effectiveness of coagulation/filtration and lime-soda ash softening treatment methods to remove strontium from surface and ground waters. Coagulation/filtration jar test results on natural waters showed that conventional treatment with aluminum and iron coagulants were able to achieve only 12% and 5.9% strontium removal, while lime softening removed as high as 78% from natural strontium-containing ground water. Controlled batch experiments on synthetic water showed that strontium removal during the lime-soda ash softening was affected by pH, calcium concentration and dissolved inorganic carbon concentration. In all softening jar tests, the final strontium concentration was directly related to the initial strontium concentration and the removal of strontium was directly associated with calcium removal. 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 was likely incorporated in the calcium carbonate crystal lattice and was likely responsible for removal during lime softening. Copyright © 2016. Published by Elsevier Ltd.

  4. Treatment of gastroesophageal reflux disease: two new oral formulations dexlansoprazole MR and esomezol (esomeprazole strontium).

    Science.gov (United States)

    Parekh, Parth J; Oldfield, Edward C; Johnson, David A

    2014-06-01

    The prevalence of gastroesophageal reflux disease continues to increase with the aging population and the obesity epidemic. Therapeutic failures can have significant detrimental effects in patients. Recently, dexlansoprazole MR and esomeprazole strontium were introduced to the class of proton pump inhibitors (PPIs). This article will review the pharmacodynamics and pharmacokinetics of dexlansoprazole MR and esomeprazole strontium. Using the keywords 'dexlansoprazole MR' and 'esomeprazole strontium' in the search engines of PubMed, Cochrane Reviews and Google, we were able to identify peer-reviewed publications, abstracts and presentations at national society educations meetings and present a balanced view of the available data. Dexlansoprazole MR and esomeprazole strontium offer an innovative delivery mechanism compared to conventional PPIs. Further trials are necessary in order to establish superiority.

  5. Review and assessment of technologies for the separation of strontium from alkaline and acidic media

    Energy Technology Data Exchange (ETDEWEB)

    Orth, R.J.; Kurath, D.E.

    1994-01-01

    A literature survey has been conducted to identify and evaluate methods for the separation of strontium from acidic and alkaline media as applied to Hanford tank waste. The most promising methods of solvent extraction, precipitation, and ion exchange are described. The following criteria were used for evaluating the separation methods: Appreciable strontium removal must be demonstrated; Strontium selectivity over bulk components must be demonstrated; The method must show promise for evolving into a practical and fairly simple process; The process should be safe to operate; The method must be robust (i.e., capable of separating strontium from various waste types); Secondary waste generation must be minimized; and The method must show resistance to radiation damage. The methods discussed did not necessarily satisfy all of the above criteria; thus, key areas requiring further development are also given for each method. Less promising solvent extraction, precipitation, and ion exchange methods were also identified; areas for potential development are included in this report.

  6. Application of dicyclohexyl-18-crown-6 to selective extraction of radioactive strontium from waters

    International Nuclear Information System (INIS)

    Yakshin, V.V.; Myasoedov, B.F.; Vilkova, O.M.; Tuzova, A.M.; Fedorova, A.T.; Rodionova, I.M.

    1989-01-01

    Influence of various factors on strontium extraction in the system nitric acid-dicyclohexyl-18-crown-6 was studied to develop the technique for determining 89 Sr and 90 Sr content in natural waters and aqueous salt solutions. Conditions for selective strontium extraction from complex salt systems containing Ba, Cs, Ru, Ce and other radionuclides were found. It is shown that coefficient of strontium distribution is sufficiently higher, as compared to coefficients of Cs, Ru, Ce distribution. Extraction performance under chosen conditions enables to elevate sufficiently the distribution coefficient of these substances. The scheme of radiochemical analysis is given. Strontium content in natural waters and salt solutions was determined with the use of described radiochemical method

  7. The concentration of active and inactive strontium in some Danube river samples

    International Nuclear Information System (INIS)

    Koshutich, K.; Lulich, S.

    1985-01-01

    The following fish species were investigated: Barbus barbus, Acipencer ruthenus, Abramis brama, Stizostedion lucioperca, Silurus glanis, Cyprinus caprio. The samples were collected during 1981. The inactive strontium in the water residue (after evaporation), sediment and fishes ewrw determined by nondestructive neutron activation analysis by using gamma couting system consisted of a 40 cm 3 Ge(Li) semiconductor rystal attached to a 4096-channel pulsehight analyser. The standard solution contained 5x10 -5 g of strontium per 100 lambda. Radioactive strontium was measured after several separation procedures. 90 SrCO 3 in equilibrium with its daughter 90 Y was detected in the β-low-level counting anticoincident system with gas-flow detector. The results confirmed the literature data that the sediment concentrations of the total strontium and the active 90 Sr are several times greater than those in water

  8. Effect of ionic substitutions on the magnetic properties of strontium hexaferrite: A first principles study

    Directory of Open Access Journals (Sweden)

    Vivek Dixit

    2017-11-01

    Full Text Available We investigated the effect of substitution of various ions at the Fe sites on magnetic properties of strontium hexaferrite (SrFe12O19 using first principles method based on density functional theory. The site occupancies of substituted atoms were estimated by calculating the substitution energies of different configurations. The formation probabilities of configurations were used to calculate magnetic properties of substituted strontium hexaferrite. A total of 21 elements (M were screened for their possible substitution in strontium hexaferrite, SrFe12−xMxO19 with x = 0.5. In each case the site preference of the substituted atom and the magnetic properties were calculated. We found that Bi, Sb, Sn, and Sc can effectively increase the magnetization and P, Co, Al, Ga, and Ti can enhance the anisotropy field when substituted into strontium hexaferrite.

  9. Ability of phytoremediation for absorption of strontium and cesium from soils using Cannabis sativa

    Directory of Open Access Journals (Sweden)

    Parisa Seyed Hoseini

    2012-01-01

    Conclusion: Our findings suggest that strontium can be absorbed by Cannabis sativa, with the highest absorption by the roots, stems, and leaves. However, cesium does not reach the plant because of its single capacity and inactive complex formation.

  10. A Portable Source of Lattice-Trapped and Ultracold Strontium (PLUS), Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to demonstrate the portable source of lattice-trapped, ultracold strontium (PLUS) designed during Phase I. The device uses simplified and robust...

  11. Permeable Barrier Materials for Strontium Immobilization: - UFA Determination of Hydraulic Conductivity. - Column Sorption Experiments

    National Research Council Canada - National Science Library

    Moody, T

    1996-01-01

    Selected materials were tested to emulate a permeable barrier and to examine the: (1) capture efficiency of these materials relating to the immobilization of strontium-90 and hexavalent chromium in Hanford groundwater...

  12. A portable source of lattice-trapped and ultracold strontium (PLUS), Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to design and demonstrate a portable source of lattice-trapped, ultracold strontium (PLUS). The device uses simplified and robust techniques for loading...

  13. Complexation of the strontium cation with a macrocyclic lactam receptor: Experimental and theoretical study

    Czech Academy of Sciences Publication Activity Database

    Makrlík, E.; Záliš, Stanislav; Vaňura, P.

    2016-01-01

    Roč. 214, FEB 2016 (2016), s. 171-174 ISSN 0167-7322 Institutional support: RVO:61388955 Keywords : strontium cation * macrocyclic lactam receptor Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.648, year: 2016

  14. Controllable synthesis of hierarchical strontium molybdate by sonochemical method

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Wanquan; Zhu, Wei [Department of Chemistry, University of Science and Technology of China (USTC), Hefei 230026 (China); Peng, Chao; Yang, Fan; Xuan, Shouhu; Gong, Xinglong [CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, USTC, Hefei 230027 (China)

    2012-09-15

    Large-scale chrysanthemum-like strontium molybdate (SrMoO{sub 4}) with hierarchical structure has been successfully synthesized via a facile and fast ultrasound irradiation approach at room temperature. By varying the experimental conditions, SrMoO{sub 4} with different morphologies, such as spindles, peanuts, spheres, and rods, can be obtained. The products are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected-area electron diffraction (SAED). The influent parameters including concentration, pH value, and surfactants have been investigated. A possible growth mechanism is proposed and the shape evolution of the products is characterized. The as-prepared chrysanthemum-like SrMoO{sub 4} particles are used as the precursor for electrorheological fluid and their electrorheological property is investigated. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Single event upset immunity of strontium bismuth tantalate ferroelectric memories

    International Nuclear Information System (INIS)

    Benedetto, J.M.; Derbenwick, G.F.; Cuchiaro, J.D.

    1999-01-01

    An embedded 1Kbit non-volatile (NV) serial memory manufactured with strontium bismuth tantalate (SBT) ferroelectric (FE) technology was shown to be immune to effects of heavy ion irradiation. The memories did not lose any data in the non-volatile mode when exposed to xenon (maximum effective LET of 128 MeV-cm 2 /mg and a total fluence of 1.5 x 10 7 ions/cm 2 ). The ferroelectric memories also did not exhibit any loss in the ability to rewrite new data into the memory bits, indicating that no significant degradation of the FE dipoles occurred as a result of the heavy ion exposure. The fast read/write times of FE memories also means that single event gate rupture is unlikely to occur in this technology

  16. Strontium titanate/silicon-based terahertz photonic crystal multilayer stack

    International Nuclear Information System (INIS)

    Xin, J.Z.; Jim, K.L.; Tsang, Y.H.; Chan, H.L.W.; Leung, C.W.; Yang, J.; Gong, X.J.; Chen, L.Q.; Gao, F.

    2012-01-01

    A one-dimensional photonic crystal working in the terahertz (THz) range was designed and implemented. To facilitate the design, the transmission properties of strontium titanate crystals were characterized by THz-time-domain spectroscopy. Relatively high refractive index (∝18.5) and transmission ratio (0.08) were observed between 0.2 to 1 THz. A stacked structure of (Si d Si /STO d STO ) N /Si d Si was then designed, with transmission spectra calculated by the transfer matrix method. The effects of the filling ratio (d STO /(d Si +d STO )), periodicity (d Si +d STO ) and the number of repeats N on the transmission of PC were investigated. The effect of introducing a defect layer was also studied. Based on these, Si/STO multilayers with STO defect thickness of 125 μm and 200 μm were measured. The shift of the defect mode was observed and compared with the calculations. (orig.)

  17. Strontium isotopes in carbonate deposits at Crater Flat, Nevada

    International Nuclear Information System (INIS)

    Marshall, B.D.; Futa, K.; Peterman, Z.E.; Stuckless, J.S.

    1991-01-01

    Strontium isotope studies of carbonates from soils, veins, eolian dust and Paleozoic basement sampled near Crater Flat, southwest of Yucca Mountain, provide evidence for the origins of these materials. Vein and soil carbonates have nearly identical ranges of 87 Sr/ 86 Sr, and eolian material has 87 Sr/ 86 Sr ratios at the lower end of the pedogenic range. The average 87 Sr/ 86 Sr of Paleozoic basement from Black Marble Hill is similar to the 87 Sr/ 86 Sr in the eolian dust, perhaps indicating a local source for this material. Possible spring deposits have generally higher 87 Sr/ 86 Sr than the other carbonates. These data are compared with similar data from areas east of Yucca Mountain

  18. Early African Diaspora in colonial Campeche, Mexico: strontium isotopic evidence.

    Science.gov (United States)

    Price, T Douglas; Tiesler, Vera; Burton, James H

    2006-08-01

    Construction activities around Campeche's central park led to the discovery of an early colonial church and an associated burial ground, in use from the mid-16th century AD to the late 17th century. Remains of some individuals revealed dental mutilations characteristic of West Africa. Analyses of strontium isotopes of dental enamel from these individuals yielded unusually high (87)Sr/(86)Sr ratios, inconsistent with an origin in Mesoamerica, but consistent with an origin in West Africa in terrain underlain by the West Africa Craton, perhaps near the port of Elmina, a principal source of slaves for the New World during the 16th century. These individuals likely represent some of the earliest representatives of the African Diaspora in the Americas.

  19. Conoscopic study of strontium-barium niobate single crystals

    Science.gov (United States)

    Kolesnikov, Aleksandr; Grechishkin, Rostislav; Malyshkina, Olga; Malyshkin, Yury; Dec, Jan; Łukasiewicz, Tadeusz; Ivanova, Aleksandra

    2013-12-01

    Optically transparent single crystals of strontium-barium niobate, SrxBa1-xNb2O6, of different compositions (x = 0.26...0.7) were examined with the aid of conoscopic light interference figures. A regular change of the isochrome concentric ring number and diameters consistent with the temperature variation of the value of birefringence is demonstrated by direct observations of polar cuts of optically uniaxial samples. Anomalous violations of the conventional (uniaxial) interference patterns occur occasionaly in some samples being indicative of the existence of biaxial trait in their behaviour even though no voltage is applied. These features may depend on annealing treatments at elevated temperatures. The results of the study show that conoscopic images may serve as a sensitive indicator of the structural state of SBN crystals related to the effects of stress-induced change of optical anisotropy and temperature dependent birefringence parameters.

  20. Strontium isotopes in carbonate deposits at Crater Flat, Nevada

    International Nuclear Information System (INIS)

    Marshall, B.D.; Futa, K.; Peterman, Z.E.; Stuckless, J.S.

    1991-01-01

    Strontium isotope studies of carbonates from soils, veins, eolian dust and Paleozoic basement samples near Crater Flat, southwest of Yucca Mountain, provide evidence for the origins of these materials. Vein and soil carbonates have nearly identical ranges of 87 Sr/ 86 Sr ratios at the lower end of the pedogenic range. The average 87 Sr/ 86 Sr of Paleozoic basement from Black Marble Hill is similar to the 87 Sr/ 86 Sr in the eolian dust, perhaps indicating a local source for this material. Possible spring deposits have generally higher 87 Sr/ 86 Sr than the other carbonates. These data are compared with similar data from areas east of Yucca Mountain. 7 refs., 5 figs

  1. Effective use of strontium-89 in osseous metastases

    International Nuclear Information System (INIS)

    Kuroda, Isao

    2012-01-01

    Bone is one of the organs to which cancer metastasizes most frequently. However, it is not a vital organ, therefore, survival after the occurrence of osseous metastasis is relatively favorable. Improvements of medical treatment bring prolonged survival to patients with osseous metastases. But this makes us to recognize the importance of quality of life (QOL) due to several factors, including pain. It is important for oncologists to know how to deal with such painful osseous metastases, as pain relief may enable patients to live their remaining lives to the fullest. Strontium-89 (89Sr) has been used worldwide as in Japan, while being reported to have positive effects on pain relief and QOL improvement in patients with osseous metastases. This review paper is aimed to present not only the history, roles, and medical characters of 89Sr, but also new aspects, such as how to use bone turnover markers, which location of osseous metastases is suitable for effective use of 89Sr. (author)

  2. Study on a flexoelectric microphone using barium strontium titanate

    International Nuclear Information System (INIS)

    Kwon, S R; Huang, W B; Yuan, F G; Jiang, X N; Zhang, S J

    2016-01-01

    In this study, a flexoelectric microphone was, for the first time, designed and fabricated in a bridge structure using barium strontium titanate (Ba 0.65 Sr 0.35 TiO 3 ) ceramic and tested afterwards. The prototyped flexoelectric microphone consists of a 1.5 mm  ×  768 μm  ×  50 μm BST bridge structure and a silicon substrate with a cavity. The sensitivity and resonance frequency were designed to be 0.92 pC/Pa and 98.67 kHz, respectively. The signal to noise ratio was measured to be 74 dB. The results demonstrate that the flexoelectric microphone possesses high sensitivity and a wide working frequency range simultaneously, suggesting that flexoelectricity could be an excellent alternative sensing mechanism for microphone applications. (paper)

  3. Study on a flexoelectric microphone using barium strontium titanate

    Science.gov (United States)

    Kwon, S. R.; Huang, W. B.; Zhang, S. J.; Yuan, F. G.; Jiang, X. N.

    2016-04-01

    In this study, a flexoelectric microphone was, for the first time, designed and fabricated in a bridge structure using barium strontium titanate (Ba0.65Sr0.35TiO3) ceramic and tested afterwards. The prototyped flexoelectric microphone consists of a 1.5 mm  ×  768 μm  ×  50 μm BST bridge structure and a silicon substrate with a cavity. The sensitivity and resonance frequency were designed to be 0.92 pC/Pa and 98.67 kHz, respectively. The signal to noise ratio was measured to be 74 dB. The results demonstrate that the flexoelectric microphone possesses high sensitivity and a wide working frequency range simultaneously, suggesting that flexoelectricity could be an excellent alternative sensing mechanism for microphone applications.

  4. Strontium ranelate is a drug to treat osteoarthrosis

    Directory of Open Access Journals (Sweden)

    Oksana Anatolyevna Nikitinskaya

    2013-01-01

    Full Text Available To prevent disease progression in patients with osteoarthosis (OA remains a challenging problem. Despite the proposed drug, non-drug, and surgical treatments for OA, there is a clinical need for medications that have a structure-modifying effect and are able to delay or prevent cartilage degradation and to alleviate the clinical manifestations of the disease. A 3-year international randomized clinical trial has demonstrated strong evidence for the symptomand structure-modifying effect of strontium ranelate in female and male patients with clinical primary knee OA. The clinical use of the drug opens up new prospects for preventing the progression of the disease in patients with knee and hip OA.

  5. LIGHT INTENSITY INFLUENCE ON STRONTIUM TITANATE BASED PHOTO- ELECTROCHEMICAL CELLS

    Directory of Open Access Journals (Sweden)

    D. Hertkorn

    2017-07-01

    Full Text Available The influence of light intensity on photo-electrochemical cells (PECs consisting of an n-type strontium titanate (SrTiO₃ photoanode and nickel cathode in potassium hydroxide electrolyte is studied. The band levels of an electrolyte-metal-semiconductor-electrolyte system are presented and the effect of different light intensities on the energy levels is investigated. Photocurrent density, quantum efficiency, and open circuit potential measurements are performed on the processed PECs under different light intensities (375 nm. It is demonstrated that a threshold value of the light intensity has to be reached in order to obtain positive photo activity and that beyond this value the performance remains nearly constant.

  6. A novel solvothermal route for obtaining strontium titanate nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Marquez-Herrera, A., E-mail: alfredo.marquez@uaslp.mx [Universidad Autonoma de San Luis Potosi, Departamento de Ingenieria Mecanica Administrativa, Coordinacion Academica Region Altiplano (COARA) (Mexico); Ovando-Medina, Victor M.; Corona-Rivera, Miguel A. [Universidad Autonoma de San Luis Potosi, Departamento de Ingenieria Quimica, Coordinacion Academica Region Altiplano (COARA) (Mexico); Hernandez-Rodriguez, E.; Zapata-Torres, M. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Legaria IPN (Mexico); Campos-Gonzalez, E.; Guillen-Cervantes, A.; Zelaya-Angel, O.; Melendez-Lira, M. [CINVESTAV-IPN, Departamento de Fisica (Mexico)

    2013-04-15

    Strontium titanate (SrTiO{sub 3}) has attracted a lot of attention because of its possible applications in new microelectronic devices. It is a material with a high dielectric constant, low leakage current, and some of its properties can be changed by adding or modifying the concentration of a dopant, which can be used for a wide range of functional purposes, from simple capacitors to complicated microwave devices. Therefore, in this work, we report the development of a new route to synthesize SrTiO{sub 3} nanoparticles based on the solvothermal method by employing two precursor solutions: strontium chloride and titanium(IV) butoxide. Our route allows the production of cubic SrTiO{sub 3} nanoparticles with a narrow size distribution. The particle sizes range between 8 and 24 nm, forming agglomerates of SrTiO{sub 3} in the range of 128-229 nm. It was demonstrated that the Ti/Sr molar ratio employed into the precursor solution has an important effect onto the chemical composition of the resulting SrTiO{sub 3} nanoparticles: when using Ti/Sr < 1, the formation and incorporation of the SrCO{sub 3} compound into the nanoparticles was observed while with Ti/Sr {>=} 1 nanoparticles are free of contaminants. The as-prepared nanoparticles were characterized by energy-dispersive X-ray spectroscopy, X-ray diffraction, transmission electron microscopy, high-resolution TEM, selected area electron diffraction, scanning electron microscopy, and dynamic light scattering.

  7. Preclinical evaluation of strontium-containing bioactive bone cement

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhaoyang, E-mail: lizy@hku.hk [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Composite and Functional Materials, Tianjin 300072 (China); Department of Orthopaedics and Traumatology, The University of Hong Kong, Hong Kong (China); Yuan, Ning [Department of Laboratory Medicine, Tianjin Chest Hospital, Tianjin 300051 (China); Lam, Raymond Wing Moon [Department of Orthopaedics and Traumatology, The University of Hong Kong, Hong Kong (China); Cui, Zhenduo; Yang, Xianjin [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Composite and Functional Materials, Tianjin 300072 (China); Lu, William Weijia, E-mail: wwlu@hku.hk [Department of Orthopaedics and Traumatology, The University of Hong Kong, Hong Kong (China)

    2013-12-01

    Strontium (Sr) has become more attractive for orthopaedic applications as they can simultaneously stimulate bone formation and prevent bone loss. A Sr-containing bioactive bone cement (Sr-BC) has been designed to fix osteoporotic bone fracture. Sr is a trace element, so the safety of containing Sr is concerned when Sr-BC is implanted in human body. The preclinical assessment of biocompatibility of Sr-BC was conducted according to ISO 10993 standards. MTT assay showed that this bioactive bone cement was non-toxic to mouse fibroblasts, and it met the basic requirement for the orthopaedic implant. The three independent genetic toxicity studies including Ames, chromosome aberration and bone marrow micronucleus assays demonstrated absence of genotoxic components in Sr-BC, which reassured the safety concerns of this novel bone cement. The muscle implantation results in present study were also encouraging. The acute inflammation around the cement was observed at 1 week post-implantation; however, no significant difference was observed between control and Sr-BC groups. These responses may be attributed to the presence of the foreign body, but the tissue healed after 12 weeks implantation. In summary, the above preclinical results provide additional assurance for the safety of this implant. Sr-BC can be used as a potential alternative to the traditional bone cement. - Highlights: • Strontium-containing bioactive bone cement (Sr-BC) was designed. • The biocompatibility of Sr-BC was evaluated according ISO 10993 standards. • Preclinical results provide additional assurance for the safety of Sr-BC.

  8. Textured strontium titanate layers on platinum by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Blomberg, T., E-mail: tom.blomberg@asm.com [ASM Microchemistry Ltd., Vaeinoe Auerin katu 12 A, 00560 Helsinki (Finland); Anttila, J.; Haukka, S.; Tuominen, M. [ASM Microchemistry Ltd., Vaeinoe Auerin katu 12 A, 00560 Helsinki (Finland); Lukosius, M.; Wenger, Ch. [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Saukkonen, T. [Aalto University, Puumiehenkuja 3, 02150 Espoo (Finland)

    2012-08-31

    Formation of textured strontium titanate (STO) layers with large lateral grain size (0.2-1 {mu}m) and low X-ray reflectivity roughness ({approx} 1.36 nm) on Pt electrodes by industry proven atomic layer deposition (ALD) method is demonstrated. Sr(t-Bu{sub 3}Cp){sub 2}, Ti(OMe){sub 4} and O{sub 3} precursors at 250 Degree-Sign C were used to deposit Sr rich STO on Pt/Ti/SiO{sub 2}/Si Empty-Set 200 mm substrates. After crystallization post deposition annealing at 600 Degree-Sign C in air, most of the STO grains showed a preferential orientation of the {l_brace}001{r_brace} 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 {l_brace}111{r_brace} oriented platinum electrode. The combination of platinum bottom electrodes with ALD STO(O{sub 3}) shows a promising path towards the formation of single oriented STO film. - Highlights: Black-Right-Pointing-Pointer Amorphous strontium titanate (STO) on platinum formed a textured film after annealing. Black-Right-Pointing-Pointer Single crystal domains in 60 nm STO film were 0.2-1 {mu}m wide. Black-Right-Pointing-Pointer Most STO grains were {l_brace}001{r_brace} oriented.

  9. Bioactivity and fluoride release of strontium and fluoride modified Biodentine.

    Science.gov (United States)

    Simila, Hazel O; Karpukhina, Natalia; Hill, Robert G

    2018-01-01

    Biodentine™ is a novel tricalcium silicate based material used both as a coronal dentine replacement and in pulp therapy. Its multiple use in sealing perforations, pulp capping and as a temporary restoration arises from its ability to promote dentine formation and to confer an excellent marginal seal. However, there is still room for improvement of this cement as it lacks the anticariogenic effect typically conferred by fluoride ion release as seen in glass ionomer cement based dental materials. Therefore, this study was conducted to investigate the impact of bioactive glass addition to Biodentine™. was to compare the apatite formation capacity, specificity of the apatite type formed and fluoride ion release by Biodentine™ cements that have been modified by three different compositions of bioactive glasses. High fluoride, high strontium and high fluoride plus strontium containing bioactive glasses were synthesized, incorporated into Biodentine™ powder and four types of cements prepared. These cements were immersed in phosphate buffered saline solution and incubated for a period of 3 and 24h, 3, 7 and 14 days. Fourier transform infra-red spectroscopy, X-ray diffraction, magic angle spinning nuclear magnetic resonance and fluoride ion release studies were performed. Bioactive glass addition to Biodentine™ led to pronounced formation of apatite. Where the bioactive glass contained fluoride, fluorapatite and fluoride ion release were demonstrated. Eliciting fluorapatite formation and fluoride ion release from Biodentine™ is an important development as fluoride is known to have antibacterial and anticariogenic effects. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  10. Nitrate absorption and strontium accumulation. Final report, 1 August 1973--31 December 1976

    International Nuclear Information System (INIS)

    Jackson, W.A.

    1977-03-01

    Two basic objectives of this study to determine how strontium translocation, and discrimination between strontium and calcium in plants are influenced by nitrate uptake, assimilation, and translocation, and to characterize the relationships between nitrate uptake, nitrate assimilation, and nitrate translocation. Results are reported from studies using maize seedlings in which 85 Sr and 45 Ca were used as tracers. A list is included of publications that report the results of related studies

  11. Strontium-90 sorption from fresh waters in the process of barium manganite modification

    International Nuclear Information System (INIS)

    Ryzhen'kov, A.P.; Egorov, Yu.V.

    1995-01-01

    Strontium-90 extraction by barium manganite from fresh water (natural non-salty water in open ponds) may be increased adding to the solution the sulfate anion containing reagents that modify a sorbent and chemically bind a sorbate. Heterogeneous anion-exchanging reaction of barium manganite transformation into barium sulfate-manganese dioxide and simultaneous coprecipitation of strontium sulfate (microelement) occur as a result of it. 9 refs., 4 figs., 1 tab

  12. Metastable equilibrium solubility behavior of carbonated apatite in the presence of solution strontium.

    Science.gov (United States)

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

    2004-01-01

    The purpose of this study was to use the concept of metastable equilibrium solubility (MES) to describe the anomalous solubility behavior of carbonated apatite (CAP) in the presence of solution strontium. A CAP sample (4.8 wt% CO(3), synthesized at 70 degrees C) was prepared by precipitation. 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. In order to assess the influence of strontium, MES profiles were then determined in a similar fashion with 20, 30, 40, 50, 60, 70, and 80% of the solution calcium being replaced on an equal molar basis by solution strontium. From the compositions of the equilibrating buffer solutions, ion activity products (IAPs) of the form Ca(10-n)Sr(n)(PO(4))(6)(OH)(2) (n = 0-10) were calculated in an attempt to determine the correct function governing the dissolution of the CAP preparation. The results demonstrate the following important findings: (a) at high solution strontium/calcium ratios (i.e., when 60% or more of the solution calcium was replaced by strontium), the MES profiles in all the experiments were found to be essentially superimposable when the solution IAPs were calculated using the stoichiometry of Ca(6)Sr(4)(PO(4))(6)(OH)(2), and (b), at low solution strontium/calcium ratios (i.e., when 40% or less of the solution calcium was replaced by strontium), the stoichiometry yielding MES data superpositioning was found to be that of hydroxyapatite. When other stoichiometries were assumed, good superpositioning of the data was not possible.

  13. Competitive adsorption of cesium, cobalt and strontium in conditioned clayey soil suspensions

    International Nuclear Information System (INIS)

    Gutierrez, M.; Fuentes, H.R.; Texas Univ., El Paso, TX

    1991-01-01

    Competitive adsorption of the ions (solutes) cesium, cobalt and strontium by soil samples from Hudspeth County, Texas, was investigated in laboratory experiments. Binary and ternary mixtures containing same weight percentage of each ion were placed in contact with the soil, at constant soil:solution ratio, temperature and pressure, until equilibrium was reached. Once it was determined that the adsorption of single adsorbates was well represented by the Freundlich equation, the Sheindorf-Rehbun-Sheintuck (SRS) equation was used to obtain the competitive coefficients for each component of the binary mixtures. The SRS-equation for ternary mixtures predicts the adsorption of each ion based on the parameters of its respective single-analog isotherm and the competitive coefficients obtained for binary mixtures. Predicted values were very close to those obtained experimentally for ternary mixtures. Competition coefficients vary from 0.15 to 0.20 for cobalt in the presence of strontium and 1.0 to 1.3 in the presence of cesium: 0.3 to 0.6 for cesium in the presence of strontium and 0.4 to 0.8 in the presence of cobalt; 3.0 to 6.3 for strontium in the presence of cesium, and 4.5 in the presence of cobalt. These values suggest heterogeneous interactions between ions and adsorption sites: cobalt and cesium do not compete for adsorption sites as much as cobalt does with strontium, or cesium with strontium. (author)

  14. Induction of a program gene expression during osteoblast differentiation with strontium ranelate

    International Nuclear Information System (INIS)

    Zhu Lingling; Zaidi, Samir; Peng Yuanzhen; Zhou Hang; Moonga, Baljit S.; Blesius, Alexia; Dupin-Roger, Isabelle; Zaidi, Mone; Sun Li

    2007-01-01

    Strontium ranelate, a new agent for the treatment of osteoporosis, has been shown stimulate bone formation in various experimental models. This study examines the effect of strontium ranelate on gene expression in osteoblasts, as well as the formation of mineralized (von Kossa-positive) colony-forming unit-osteoblasts (CFU-obs). Bone marrow-derived stromal cells cultured for 21 days under differentiating conditions, when exposed to strontium ranelate, displayed a significant time- and concentration-dependent increase in the expression of the master gene, Runx2, as well as bone sialoprotein (BSP), but interestingly without effects on osteocalcin. This was associated with a significant increase in the formation of CFU-obs at day 21 of culture. In U-33 pre-osteoblastic cells, strontium ranelate significantly enhanced the expression of Runx2 and osteocalcin, but not BSP. Late, more mature osteoblastic OB-6 cells showed significant elevations in BSP and osteocalcin, but with only minimal effects on Runx2. In conclusion, strontium ranelate stimulates osteoblast differentiation, but the induction of the program of gene expression appears to be cell type-specific. The increased osteoblastic differentiation is the likely basis underlying the therapeutic bone-forming actions of strontium ranelate

  15. Strontium-90 accumulation in fowl and its migration into egg following chromic intake with forage

    International Nuclear Information System (INIS)

    Koldaeva, K.A.; Sarapul'tsev, I.A.

    1975-01-01

    Accumulation of strontium-90 in different organs of hens and its transfer ot eggs have been studied at chronic feeding with the isotope. The feed consisted of potato and wheat grown on plots artificially contaminated with strontium-90. The duration of the experiment is 30 days during which the hens lay 35 eggs. Strontium-90 and calcium are determined in the femur, shoulder, breastbone, skull, rib, vertebrae, and muscles. Determination errors do not exceed 10 and 5% for the isotope and calcium respectively. Concentration of stronium-90 and calcium in different bones and in muscles of laying hens and roosters after a month's feeding with the isotope presented. The isotope concentration in bones of hens 3 to 4 times higher than in bones of roosters while the muscle concentration is similar in both cases. The higher content of strontium-90 per g of bone tissue calcium in hens can be explained by a higher level of calcium metabolism during the laying period. Data on strontium-90 and calcium concentration in eggs are also presented. The bulk of the isotope accumulates in the eggshell (96.4%). One egg contains an average of 31% of the daily strontium intake

  16. Bactericidal strontium-releasing injectable bone cements based on bioactive glasses.

    Science.gov (United States)

    Brauer, Delia S; Karpukhina, Natalia; Kedia, Gopal; Bhat, Aditya; Law, Robert V; Radecka, Izabela; Hill, Robert G

    2013-01-06

    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, giving compressive strength of up to 35 MPa. Strontium release was dependent on BG composition with increasing strontium substitution resulting in higher concentrations in the medium. Bactericidal effects were tested on Staphylococcus aureus and Streptococcus faecalis; cell counts were reduced by up to three orders of magnitude over 6 days. Results show that bactericidal action can be increased through BG strontium substitution, allowing for the design of novel antimicrobial and bone enhancing cements for use in vertebroplasty or kyphoplasty for treating osteoporosis-related vertebral compression fractures.

  17. Powder XRD, TEM, FTIR and thermal studies of strontium tartrate nano particles

    Science.gov (United States)

    Lathiya, U. M.; Jethva, H. O.; Joshi, M. J.; Vyas, P. M.

    2017-05-01

    Strontium tartrate finds several applications, e.g., as non-linear optical and dielectric material, in tracer composition and ammunition unit, in treating structural integrity of bone. The growth of single crystals of strontium tartrate in silica gel has been widely reported. In the present study, strontium tartrate nano particles were synthesized by wet chemical method using strontium chloride, tartaric acid and sodium meta-silicate solutions in the presence of Triton X -100 surfactant. It was found that the presence of sodium meta-silicate facilitated the reaction for strontium tartrate product. The powder XRD study of strontium tartrate nano-particles suggested monoclinic crystal system and the average crystallite size was found to be 40 nm determined by applying Scherrer's formula. The TEM analysis indicated that the nano particles were spherical in nature. The FTIR spectrum confirmed the presence of various functional groups such as O-H,C-H, and C=O stretching mode. The thermal analysis was carried out by using TGA and DTA studies. The nano-particles were found to be stable up to 175°C and then decomposed through various stages. The results are compared with the bulk crystalline material available in the literature.

  18. Sorption of strontium on uranyl peroxide: implications for a high-level nuclear waste repository.

    Science.gov (United States)

    Sureda, Rosa; Martínez-Lladó, Xavier; Rovira, Miquel; de Pablo, Joan; Casas, Ignasi; Giménez, Javier

    2010-09-15

    Strontium-90 is considered the most important radioactive isotope in the environment and one of the most frequently occurring radionuclides in groundwaters at nuclear facilities. The uranyl peroxide studtite (UO2O2 . 4H2O) has been observed to be formed in spent nuclear fuel leaching experiments and seems to have a relatively high sorption capacity for some radionuclides. In this work, the sorption of strontium onto studtite is studied as a function of time, strontium concentration in solution and pH. The main results obtained are (a) sorption is relatively fast although slower than for cesium; (b) strontium seems to be sorbed via a monolayer coverage of the studtite surface, (c) sorption has a strong dependence on ionic strength, is negligible at acidic pH, and increases at neutral to alkaline pH (almost 100% of the strontium in solution is sorbed above pH 10). These results point to uranium secondary solid phase formation on the spent nuclear fuel as an important mechanism for strontium retention in a high-level nuclear waste repository (HLNW). Copyright 2010 Elsevier B.V. All rights reserved.

  19. Borazino-Doped Polyphenylenes.

    Science.gov (United States)

    Marinelli, Davide; Fasano, Francesco; Najjari, Btissam; Demitri, Nicola; Bonifazi, Davide

    2017-04-19

    The divergent synthesis of two series of borazino-doped polyphenylenes, in which one or more aryl units are replaced by borazine rings, is reported for the first time, taking advantage of the decarbonylative [4 + 2] Diels-Alder cycloaddition reaction between ethynyl and tetraphenylcyclopentadienone derivatives. Because of the possibility of functionalizing the borazine core with different groups on the aryl substituents at the N and B atoms of the borazino core, we have prepared borazino-doped polyphenylenes featuring different doping dosages and orientations. To achieve this, two molecular modules were prepared: a core and a branching unit. Depending on the chemical natures of the central aromatic module and the reactive group, each covalent combination of the modules yields one exclusive doping pattern. By means of this approach, three- and hexa-branched hybrid polyphenylenes featuring controlled orientations and dosages of the doping B 3 N 3 rings have been prepared. Detailed photophysical investigations showed that as the doping dosage is increased, the strong luminescent signal is progressively reduced. This suggests that the presence of the B 3 N 3 rings engages additional deactivation pathways, possibly involving excited states with an increasing charge-separated character that are restricted in the full-carbon analogues. Notably, a strong effect of the orientational doping on the fluorescence quantum yield was observed for those hybrid polyphenylene structures featuring low doping dosages. Finally, we showed that Cu-catalyzed 1,3-dipolar cycloaddition is also chemically compatible with the BN core, further endorsing the inorganic benzene as a versatile aromatic scaffold for engineering of molecular materials with tailored and exploitable optoelectronic properties.

  20. Bio sorption of strontium from aqueous solution by the new strain of bacillus sp. strain GT-83

    International Nuclear Information System (INIS)

    Tajer Mohammad Ghazvini, P.; Ghorbanzadeh Mashkani, S.; Mazaheri, M.

    2009-01-01

    An attempt was made to isolate bacterial strains capable of removing strontium biologically. In this study ten different water samples collected from Neydasht spring in the north of Iran and then the bacterial species were isolated from the water samples. The initial screening of a total of 50 bacterial isolates resulted in selection of one strain.The isolated strain showed a maximum adsorption capacity with 55 milligrams strontium/g dry wt. It was tentatively identified as Bacillus sp. According to the morphological and biochemical properties, and called strain GT-83. Our studies indicated that Bacillus sp. GT-83 is able to grow aerobically in the presence of 50 mM SrCl 2 , but its growth was inhibited at high levels of strontium concentrations. The bio sorption capacity of Bacillus sp. GT-83 depends strongly on the p H solution. Hence the maximum strontium sorption capacity of Bacillus sp. GT-83 was obtained at pah 10, independent of absence or presence of MgCl 2 of different concentrations. Strontium-salt bio sorption studies were also performed at this p H values. The equilibrium bio sorption of strontium was elevated by increasing the strontium concentration, up to 250 milligrams/l for Bacillus sp. GT-83. The maximum bio sorption of strontium was obtained at temperatures in the range of 30-35 d eg C . The Bacillus sp. GT-83 bio sorbed 97 milligrams strontium/g dry wt at 100 milligrams/l initial strontium concentration without MgCl 2 . When MgCl 2 concentration increased to 15%(w/v), these values dropped to 23.6 milligrams strontium/g dry wt at the same conditions. Uptake of strontium within 5 min of incubation was relatively rapid and the absorption continued slowly thereafter

  1. Structural, magnetic and microwave absorption behavior of Co-Zr substituted strontium hexaferrites prepared using tartaric acid fuel for electromagnetic interference suppression

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Prabhjyot, E-mail: prabhjyot.2525@gmail.com [Department of Chemistry, Centre for Advanced Studies-I, Guru Nanak Dev University, Amritsar 143005 (India); Chawla, S.K., E-mail: sschawla118@gmail.com [Department of Chemistry, Centre for Advanced Studies-I, Guru Nanak Dev University, Amritsar 143005 (India); Narang, Sukhleen Bindra, E-mail: sukhleen2@yahoo.com [Department of Electronics Technology, Guru Nanak Dev University, Amritsar 143005 (India); Pubby, Kunal, E-mail: kunalpubby02@gmail.com [Department of Electronics Technology, Guru Nanak Dev University, Amritsar 143005 (India)

    2017-01-15

    Strontium hexaferrites, doped with varying Co-Zr content (x) have been synthesized by sol-gel auto-combustion route using tartaric acid as fuel at 800 °C. X-ray diffraction and Fourier transform Infra-red have been carried out to confirm the phase formation, particle size (average 21.9–36.8 nm) and the bond formation respectively. Magnetic properties are scrutinized using vibrating sample magnetometer. Techniques like scanning electron microscopy, transmission electron microscopy and energy dispersive scattering have been employed to explore the surface morphology, particle size and composition of the nano-powders. Electromagnetic characterization of the prepared ferrites has been done using Vector Network Anlyzer in 12.4–18 GHz frequency range. The effect of calcination temperature (500–1000 °C) on the structure, morphology and magnetic properties has also been studied for x=0.2 and 800 °C has been found to be the most suitable temperature with the best magnetic properties. Increase in doping has resulted in resonance peaks in dielectric and magnetic loss spectra, leading to microwave absorption peaks. Ferrites with x=0.2, 0.8 and 1.0 have appropriate reflection loss less than −10 dB and bandwidth in Ku-band, hence can be used as effective absorbers in suppression of electromagnetic interference (EMI). The governance of impedance matching in deciding the absorption properties has been proved by using input impedance calculations. - Highlights: • Co-Zr doped strontium hexaferrite nanopowders have been prepared by sol-gel route. • 800 °C was most suitable temperaturewith best structural and magnetic properties. • Samples have M-type hexagonal structure with an average particle size of 36.47 nm. • Samples x=0.2, 0.8 and 1.0 are suitable for suppression of EM waves in Ku-band. • The origin of absorption peaks: impedance matching and losses has been explained.

  2. Nationwide registry-based analysis of cardiovascular risk factors and adverse outcomes in patients treated with strontium ranelate

    DEFF Research Database (Denmark)

    Abrahamsen, Bjarke; Grove, E L; Vestergaard, P

    2013-01-01

    National registers showed that a large proportion of patients treated with strontium ranelate have conditions that may now contraindicate use. The risk of death in strontium ranelate-treated patients was significantly higher than that seen in users of other osteoporosis drugs even after adjusting...... for cardiovascular risk factor profile.......National registers showed that a large proportion of patients treated with strontium ranelate have conditions that may now contraindicate use. The risk of death in strontium ranelate-treated patients was significantly higher than that seen in users of other osteoporosis drugs even after adjusting...

  3. Strontium concentration in the Baltic Sea in 1974-1975 and its correlation with some hydrodynamic characteristics

    International Nuclear Information System (INIS)

    Stankajtis, A.K.; Styro, D.B.

    1978-01-01

    Strontium concentration data in the surface and deep layers of the Baltic Sea water are presented. Strontium concentration in the surface layer varies from 1.6 mg/1 to 2.2 mg/1 and that at a depth of 50 m - from 2.0 to 3.2 mg/1. Maximum concentration (4.5 mg/1) is at a depth of 440 m. Strontium concentration data are correlated with some hydrometeorological parameters (wind velocity and direction, water temperature, salinity). It has been indicated that water mass transfer in the Baltic Sea may be traced using the data on strontium concentration variations

  4. A comparison of the palliative effects of strontium-89 and external beam radiotherapy in metastatic prostate cancer

    International Nuclear Information System (INIS)

    Quilty, P.M.; Kirk, D.; Bolger, J.J.; Dearnaley, D.P.; Mason, M.D.; Lewington, V.J.; Reed, N.S.E.; Russell, J.M.; Yardley, J.

    1994-01-01

    From 1988 to 1991, 284 patients with prostatic cancer and painful bone metastases were treated with either radiotherapy or strontium-89 (200 MBq). Patients were first stratified according to suitability for local or hemibody radiotherapy, then randomly allocated that form of treatment or strontium-89 (i.v. injection). After 4,8 and 12 weeks pain sites were mapped, toxicity monitored, and all additional palliative treatments recorded. There was no significant difference in median survival (after >80% had died); 33 weeks following strontium 8 9 and 28 weeks following radiotherapy (p=0.1). All treatments provided effective pain relief; improvement was sustained to 3 months in 63.6% after hemibody radiotherapy compared with 66.1% after strontium-89, and in 61% after local radiotherapy compared with 65.9% in the comparable strontium 8 9 group. Fewer patients reported new pain sites after strontium-89 than after local or hemibody radiotherapy (p < 0.05). Radiotherapy to a new site was required by 12 patients in the local radiotherapy group compared with 2 after strontium-89 (p < 0.01), although there was no significant difference between hemibody radiotherapy (6 patients) and strontium-89 (9 patients) in this respect. Platelets and leukocytes fell by an average 30-40% after strontium-89 but sequelae were uncommon, and other symptoms rare

  5. Sanctions for doping in sport

    Directory of Open Access Journals (Sweden)

    Mandarić Sanja

    2014-01-01

    Full Text Available Top-level sport imposes new and more demanding physical and psychological pressures, and the desire for competing, winning and selfassertion leads athletes into temptation to use prohibited substances in order to achieve the best possible results. Regardless of the fact that the adverse consequences of prohibited substances are well-known, prestige and the need to dominate sports arenas have led to their use in sports. Doping is one of the biggest issues in sport today, and the fight against it is a strategic objective on both global and national levels. World Anti-Doping Agency, the International Olympic Committee, international sports federations, national anti-doping agencies, national sports federations, as well as governments and their repressive apparatuses are all involved in the fight against doping in sport. This paper points to a different etymology and phenomenology of doping, the beginnings of doping in sport, sports doping scandals as well as the most important international instruments regulating this issue. Also, there is a special reference in this paper to the criminal and misdemeanor sanctions for doping in sport. In Serbia doping in sport is prohibited by the Law on Prevention of Doping in Sports which came into force in 2005 and which prescribes the measures and activities aimed at prevention of doping in sport. In this context, the law provides for the following three criminal offenses: use of doping substances, facilitating the use of doping substances, and unauthorized production and putting on traffic of doping substances. In addition, aiming at curbing the abuse of doping this law also provides for two violations. More frequent and repetitive doping scandals indicate that doping despite long-standing sanctions is still present in sports, which suggests that sanctions alone have not given satisfactory results so far.

  6. Biosorption of the strontium ion by irradiated Saccharomyces cerevisiae under culture conditions.

    Science.gov (United States)

    Qiu, Liang; Feng, Jundong; Dai, Yaodong; Chang, Shuquan

    2017-06-01

    As a new-emerging method for strontium disposal, biosorption has shown advantages such as high sorption capacity; low cost. In this study, we investigated the potential of Saccharomyces cerevisiae (S. cerevisiae) in strontium disposal under culture conditions and the effects of irradiation on their biosorption capabilities. We found that S. cerevisiae can survive irradiation and grow. Pre-exposure to irradiation rendered S. cerevisiae resistant to further irradiation. Surprisingly, the pre-exposure to irradiation can increase the biosorption capability of S. cerevisiae. We further investigated the factors that influenced the biosorption efficiency, which were (strongest to weakest): pH > strontium concentration > time > temperature. In our orthogonal experiment, the optimal conditions for strontium biosorption by irradiated S. cerevisiae were: pH 7, 150 mg L -1 strontium at the temperature of 32 °C with 30 h. The equilibrium of strontium biosorption was analyzed by Langmuir and Freundlich models, from which the formal model is found to provide a better fit for the experimental results. The kinetics of strontium biosorption by living irradiated S. cerevisiae was found to be comprised of three phases: dramatically increased during 0-9 h, decreased during 12-24 h, and increased during 30-50 h. These results provide a systematic understanding of the biosorption capabilities of irradiated S. cerevisiae, which can contribute to the development of remediating nuclear waste water. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Preparation and investigation of bulk and thin film samples of strontium ferrite

    Directory of Open Access Journals (Sweden)

    A Poorbafrani

    2008-07-01

    Full Text Available   In this article, bulk and thin film samples of strontium ferrite have been studied. Due to the high electrical resistivity in strontium ferrite, energy loss due to eddy currents reduces and because of this, it can be used in high frequency magnetic circuits. On the other hand, strontium ferrite has attracted much attention as a permanent magnet. At first, we study the preparation process of bulk samples of strontium ferrite by a solid state reaction technique. In preparation of samples, to optimize the magnetic properties, we have used the stoichiometry factor (n = Fe2O3 / SrO of 5.25. In addition, we have used additives such as CaO and SiO2 to control grain growth. The samples have been prepared in two series: Isotropic and Anisotropic. For preparation of anisotropic samples, the magnetic field of 1T has been used for orientation of the grains during the press. Then, X-ray diffraction, Scanning Electron Microscopy (SEM, EDAX analysis and Magnetometer, was used for analyzing and comparing of structural and magnetic properties of isotropic and anisotropic samples. The results indicate that, due to the applied magnetic field, the structural and Magnetic properties of anisotropic samples improved efficiently because of the orientation of the grains during the press. In the next stage, we used bulk samples to prepare strontium ferrite thin films by Pulsed Laser Deposition technique (PLD. The Si (111 substrate has been used to prepare the thin films. Then we have studied the microstructure of thin films by X-ray diffraction, SEM and EDAX analysis. These studies on different samples show that for the preparation of crystalline phase of strontium ferrite thin films, the substrate temperature must be higher than 800˚C. The optimum conditions for preparation of strontium, ferrite thin films have been achieved on the substrate temperature of 840˚C and oxygen pressure of 75 mtorr.

  8. Sources of strontium and calcium in desert soil and calcrete

    Science.gov (United States)

    Capo, Rosemary C.; Chadwick, Oliver A.

    1999-06-01

    The carbon-cycle significance of soil carbonate fluxes is subject to large uncertainties because it is not clear precisely how much calcium is derived from atmospheric sources compared with that from the chemical weathering of silicate minerals. In the petrocalcic horizon (calcrete) of a Pleistocene soil from the USDA-SCS Desert Project area near Las Cruces, NM, approximately 1.5 g Ca/cm 3 has been added, with an associated expansion of the profile of ˜200%. Strontium isotope values for the labile cations and carbonate from the A, B and K soil horizons have 87Sr/ 86Sr values that range from 0.7087 to 0.7093, similar to the values for easily soluble local dust and rain. The parent material, non-calcareous Camp Rice alluvial sediment, has a 87Sr/ 86Sr ratio of ˜0.7165. Mixing calculations indicate a minimum atmospheric contribution to soil carbonate calcium of ˜94%; the more likely scenarios indicate at least 98% of the Ca originated from atmospheric input. The variations in 87Sr/ 86Sr ratios of soil silicate (0.7131 to 0.7173) are consistent with weathering of volcanogenic sediments and neoformation of clay minerals in the petrocalcic horizon. Moreover, the Sr isotope data suggest that 50-70% of silicate in the uppermost 25 cm of the profile could be atmosphere-derived. The isotopic composition of labile strontium in the A horizon and the mass distribution of silicon and calcium indicate that the uppermost portion of the profile is the present zone for the release of cations due to silicate weathering. Steady-state models of the whole profile yield a Sr weathering flux ranging from ˜200 to 400 μg cm -2 Ma -1. The results indicate that both the present-day and long-term contribution of calcium from silicate weathering is less than 2% of that supplied from the atmosphere, and confirm that desert soil formation is not a significant sink for atmospheric carbon.

  9. Engineered Materials for Cesium and Strontium Storage. Final Technical Report

    International Nuclear Information System (INIS)

    McDeavitt, Sean M.

    2010-01-01

    Closing the nuclear fuel cycle requires reprocessing spent fuel to recover the long-lived components that still have useful energy content while immobilizing the remnant waste fission products in stable forms. At the genesis of this project, next generation spent fuel reprocessing methods were being developed as part of the U.S. Department of Energy's Advanced Fuel Cycle Initiative. One of these processes was focused on solvent extraction schemes to isolate cesium (Cs) and strontium (Sr) from spent nuclear fuel. Isolating these isotopes for short-term decay storage eases the design requirements for long-term repository disposal; a significant amount of the radiation and decay heat in fission product waste comes from Cs-137 and Sr-90. For the purposes of this project, the Fission Product Extraction (FPEX) process is being considered to be the baseline extraction method. The objective of this project was to evaluate the nature and behavior of candidate materials for cesium and strontium immobilization; this will include assessments with minor additions of yttrium, barium, and rubidium in these materials. More specifically, the proposed research achieved the following objectives (as stated in the original proposal): (1) Synthesize simulated storage ceramics for Cs and Sr using an existing labscale steam reformer at Purdue University. The simulated storage materials will include aluminosilicates, zirconates and other stable ceramics with the potential for high Cs and Sr loading. (2) Characterize the immobilization performance, phase structure, thermal properties and stability of the simulated storage ceramics. The ceramic products will be stable oxide powders and will be characterized to quantify their leach resistance, phase structure, and thermophysical properties. The research progressed in two stages. First, a steam reforming process was used to generate candidate Cs/Sr storage materials for characterization. This portion of the research was carried out at Purdue

  10. Engineered Materials for Cesium and Strontium Storage Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Sean M. McDeavitt

    2010-04-14

    Closing the nuclear fuel cycle requires reprocessing spent fuel to recover the long-lived components that still have useful energy content while immobilizing the remnant waste fission products in stable forms. At the genesis of this project, next generation spent fuel reprocessing methods were being developed as part of the U.S. Department of Energy's Advanced Fuel Cycle Initiative. One of these processes was focused on solvent extraction schemes to isolate cesium (Cs) and strontium (Sr) from spent nuclear fuel. Isolating these isotopes for short-term decay storage eases the design requirements for long-term repository disposal; a significant amount of the radiation and decay heat in fission product waste comes from Cs-137 and Sr-90. For the purposes of this project, the Fission Product Extraction (FPEX) process is being considered to be the baseline extraction method. The objective of this project was to evaluate the nature and behavior of candidate materials for cesium and strontium immobilization; this will include assessments with minor additions of yttrium, barium, and rubidium in these materials. More specifically, the proposed research achieved the following objectives (as stated in the original proposal): (1) Synthesize simulated storage ceramics for Cs and Sr using an existing labscale steam reformer at Purdue University. The simulated storage materials will include aluminosilicates, zirconates and other stable ceramics with the potential for high Cs and Sr loading. (2) Characterize the immobilization performance, phase structure, thermal properties and stability of the simulated storage ceramics. The ceramic products will be stable oxide powders and will be characterized to quantify their leach resistance, phase structure, and thermophysical properties. The research progressed in two stages. First, a steam reforming process was used to generate candidate Cs/Sr storage materials for characterization. This portion of the research was carried out at

  11. Fitness Doping and Body Management

    DEFF Research Database (Denmark)

    Thualagant, Nicole

    This PhD thesis examines in a first paper the conceptualization of fitness doping and its current limitations. Based on a review of studies on bodywork and fitness doping it is emphasised that the definition of doping does not provide insights into bodywork of both men and women. Moreover...... for body control and thus a management of the body....

  12. The intact strontium ranelate complex stimulates osteoblastogenesis and suppresses osteoclastogenesis by antagonizing NF-κB activation.

    Science.gov (United States)

    Yamaguchi, Masayoshi; Weitzmann, M Neale

    2012-01-01

    Strontium ranelate, a pharmaceutical agent shown in clinical trials to be effective in managing osteoporosis and reducing fracture risk in postmenopausal women, is relatively unique in its ability to both blunt bone resorption and stimulate bone formation. However, its mechanisms of action are largely unknown. As the nuclear factor-kappa B (NF-κB) activation antagonists both stimulate osteoblastic bone formation and repress osteoclastic bone resorption, we hypothesized that strontium ranelate may achieve its anabolic and anti-catabolic activities by modulating NF-κB activation in bone cells. In this study, osteoclast and osteoblast precursors were treated with intact strontium ranelate or its individual components sodium ranelate and/or strontium chloride, and its effect on in vitro osteoclastogenesis and osteoblastogenesis and on NF-κB activation quantified. Although the activity of strontium ranelate has been attributed to the release of strontium ions, low dose intact strontium ranelate complex, but not sodium ranelate and/or strontium chloride, potently antagonized NF-κB activation in osteoclasts and osteoblasts in vitro, and promoted osteoblast differentiation while suppressing osteoclast formation. Taken together, our data suggest a novel centralized mechanism by which strontium ranelate promotes osteoblast activity and suppresses osteoclastogenesis, based on suppression of NF-κB signal transduction. We further demonstrate that the biological actions of strontium ranelate may be related to low dose of the intact molecule rather than dissociation and release of strontium ions, as previously thought. These data may facilitate the development of additional novel pharmacological agents for the amelioration of osteoporosis, based on NF-κB blockade.

  13. Elaboration et réactivité interfaciale d'oxydes pérovskites à base de Lanthane Strontium Chrome Ruthénium (LSCrRu) comme composés d'anode de piles à combustible à température intermédiaire (ITSOFC).

    OpenAIRE

    Combemale, L.

    2005-01-01

    New data on the interest of ruthenium doped lanthanum strontium chromite La1-xSrxCr1-yRuyO3δ (LSCrRu) as anode in ITSOFC are presented. Microwave synthesis of mixed oxides allowed shaping of half-cells and complete cells using sputtering and screen printing methods. LSCrRu methane reforming property had been studied in a mono-chamber system coupled with a mass spectrometer in collaboration with Institut de REcherche Hydro-Québec. Anode/electrolyte interfacial reactivity had been analysed usi...

  14. High-T sub c fluorine-doped YBa2Cu3O(y) films on ceramic substrates by screen printing

    Science.gov (United States)

    Bansal, Narottam P.

    1991-01-01

    Thick films of fluorine-doped YBa2Cu3O(y) were screen printed on highly polished alumina, magnesia spinel, strontium titanate, and yttria-stabilized zirconia (YSZ) substrates. They were annealed at 1000 C and soaked in oxygen at 450 C, followed by slow cooling to room temperature. The films were characterized by electrical resistivity measurements as a function of temperature and x-ray diffraction. The film on YSZ showed the best characteristics with a T sub c (onset) of 91 K, T sub c (R equals 0) of 88.2 K, and a transition width, delta T sub c (10-90 percent), of approximately 1.7 K. The film adhesion, probably controlled by interdiffusion of cations between the film and the substrate, was good in all cases except on strontium titanate where the film completely detached from the substrate.

  15. Thermoelectric properties of strontium titanate superlattices incorporating niobium oxide nanolayers

    KAUST Repository

    Sarath Kumar, S. R.

    2014-04-22

    A novel superlattice structure based on epitaxial nanoscale layers of NbOx and Nb-doped SrTiO3 is fabricated using a layer-by-layer approach on lattice matched LAO substrates. The absolute Seebeck coefficient and electrical conductivity of the [(NbOx) a/(Nb-doped SrTiO3)b]20 superlattices (SLs) were found to increase with decreasing layer thickness ratio (a/b ratio), reaching, at high temperatures, a power factor that is comparable to epitaxial Nb-doped SrTiO3 (STNO) films (∼0.7 W m-1 K-1). High temperature studies reveal that the SLs behave as n-type semiconductors and undergo an irreversible change at a varying crossover temperature that depends on the a/b ratio. By use of high resolution X-ray photoelectron spectroscopy and X-ray diffraction, the irreversible changes are identified to be due to a phase transformation from cubic NbO to orthorhombic Nb2O5, which limits the highest temperature of stable operation of the superlattice to 950 K. © 2014 American Chemical Society.

  16. Alveolar bone repair with strontium- containing nanostructured carbonated hydroxyapatite

    Directory of Open Access Journals (Sweden)

    André Boziki Xavier do Carmo

    2018-01-01

    Full Text Available ABSTRACT Objective: This study aimed to evaluate bone repair in rat dental sockets after implanting nanostructured carbonated hydroxyapatite/sodium alginate (CHA and nanostructured carbonated hydroxyapatite/sodium alginate containing 5% strontium microspheres (SrCHA as bone substitute materials. Methods: Twenty male Wistar rats were randomly divided into two experimental groups: CHA and SrCHA (n=5/period/group. After one and 6 weeks of extraction of the right maxillary central incisor and biomaterial implantation, 5 μm bone blocks were obtained for histomorphometric evaluation. The parameters evaluated were remaining biomaterial, loose connective tissue and newly formed bone in a standard area. Statistical analysis was performed by Mann-Withney and and Wilcoxon tests at 95% level of significance. Results: The histomorphometric results showed that the microspheres showed similar fragmentation and bio-absorbation (p>0.05. We observed the formation of new bones in both groups during the same experimental periods; however, the new bone formation differed significantly between the weeks 1 and 6 (p=0.0039 in both groups. Conclusion: The CHA and SrCHA biomaterials were biocompatible, osteoconductive and bioabsorbable, indicating their great potential for clinical use as bone substitutes.

  17. Source of Lake Vostok Cations Constrained with Strontium Isotopes

    Directory of Open Access Journals (Sweden)

    William Berry Lyons

    2016-08-01

    Full Text Available Lake Vostok is the largest sub-glacial lake in Antarctica. The primary source of our current knowledge regarding the geochemistry and biology of the lake comes from the analysis of refrozen lake water associated with ice core drilling. Several sources of dissolved ions and particulate matter to the lake have been proposed, including materials from the melted glacier ice, the weathering of underlying geological materials, hydrothermal activity and underlying, ancient evaporitic deposits. A sample of Lake Vostok Type 1 accretion ice has been analyzed for its 87Sr/86Sr signature as well as its major cation and anion and Sr concentrations. The strontium isotope ratio of 0.71655 and the Ca/Sr ratio in the sample strongly indicate that the major source of the Sr is from aluminosilicate minerals from the continental crust. These data imply that at least a portion of the other cations in the Type 1 ice also are derived from continental crustal materials and not hydrothermal activity, the melted glacier ice, or evaporitic sources.

  18. Strontium titanate/silicon-based terahertz photonic crystal multilayer stack

    Energy Technology Data Exchange (ETDEWEB)

    Xin, J.Z.; Jim, K.L.; Tsang, Y.H.; Chan, H.L.W.; Leung, C.W. [Hong Kong Polytechnic University, Department of Applied Physics and Materials Research Centre, Kowloon, Hong Kong (China); Yang, J.; Gong, X.J.; Chen, L.Q.; Gao, F. [Chinese Academy of Sciences, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Shenzhen (China)

    2012-04-15

    A one-dimensional photonic crystal working in the terahertz (THz) range was designed and implemented. To facilitate the design, the transmission properties of strontium titanate crystals were characterized by THz-time-domain spectroscopy. Relatively high refractive index ({proportional_to}18.5) and transmission ratio (0.08) were observed between 0.2 to 1 THz. A stacked structure of (Si d{sub Si}/STO d{sub STO}){sub N} /Si d{sub Si} was then designed, with transmission spectra calculated by the transfer matrix method. The effects of the filling ratio (d{sub STO}/(d{sub Si}+d{sub STO})), periodicity (d{sub Si}+d{sub STO}) and the number of repeats N on the transmission of PC were investigated. The effect of introducing a defect layer was also studied. Based on these, Si/STO multilayers with STO defect thickness of 125 {mu}m and 200 {mu}m were measured. The shift of the defect mode was observed and compared with the calculations. (orig.)

  19. Application of nanofiltration to separate strontium from seawater

    International Nuclear Information System (INIS)

    Shinoda, Yusuke; Maeda, Yasushi; Tsuzuki, Shintaro; Das, Supriyo; Jove, Elbir; Beardsley, Scott; Parker, Garth; Rosenberg, Steven

    2014-01-01

    Removal of radioactive substances from the seawater in the port has now been one of the most critical issues in the Fukushima Daiichi Nuclear Power Plant. To solve the issues, nanofiltration (NF) process was evaluated to selectively separate strontium (Sr) ion from the seawater. Four (4) types of NF membranes were examined to evaluate fundamental Sr removal capability and also evaluate other alkali earth metals, magnesium (Mg) and calcium (Ca) ion removal by a flat sheet membrane test with controlled operating conditions (flux, temperature, and pH). It was found that Sr can be rejected more than 90% by a certain type of NF membrane. It was also found that Mg and Ca removal rate is similar with Sr removal and it is difficult to separate Sr from Mg and Ca in the seawater. When evaluating the effect of flux, temperature, and pH for the removal of the above divalent ions, it was found that higher flux, lower temperature, and lower pH result in higher divalent cation rejection rates, which follow the theory of the membrane chemistry. The single element test and pilot test with six elements in series were also conducted with one type of NF membrane. It was confirmed that the same Mg, Ca, and Sr removal is achieved by the single element test as flat sheet membrane test result. As per the pilot test result, it was found that 2 pass system is required to achieve more than 99% Sr decontamination rate in the actual plant. (author)

  20. Experimental realization of an optical second with strontium lattice clocks.

    Science.gov (United States)

    Le Targat, R; Lorini, L; Le Coq, Y; Zawada, M; Guéna, J; Abgrall, M; Gurov, M; Rosenbusch, P; Rovera, D G; Nagórny, B; Gartman, R; Westergaard, P G; Tobar, M E; Lours, M; Santarelli, G; Clairon, A; Bize, S; Laurent, P; Lemonde, P; Lodewyck, J

    2013-01-01

    Progress in realizing the SI second had multiple technological impacts and enabled further constraint of theoretical models in fundamental physics. Caesium microwave fountains, realizing best the second according to its current definition with a relative uncertainty of 2-4 × 10(-16), have already been overtaken by atomic clocks referenced to an optical transition, which are both more stable and more accurate. Here we present an important step in the direction of a possible new definition of the second. Our system of five clocks connects with an unprecedented consistency the optical and the microwave worlds. For the first time, two state-of-the-art strontium optical lattice clocks are proven to agree within their accuracy budget, with a total uncertainty of 1.5 × 10(-16). Their comparison with three independent caesium fountains shows a degree of accuracy now only limited by the best realizations of the microwave-defined second, at the level of 3.1 × 10(-16).

  1. Flexoelectric sensing using a multilayered barium strontium titanate structure

    International Nuclear Information System (INIS)

    Kwon, S R; Huang, W B; Yuan, F G; Jiang, X N; Zhang, S J

    2013-01-01

    The flexoelectric effect has been recently explored for its promise in electromechanical sensing. However, the relatively low flexoelectric coefficients of ferroelectrics inhibit the potential to develop flexoelectric sensing devices. In this paper, a multilayered structure using flexoelectric barium strontium titanate (Ba 0.65 Sr 0.35 TiO 3 or BST) ceramic was fabricated in an attempt to enhance the effective flexoelectric coefficients using its inherent scale effect, and hence to improve the flexoelectric sensitivity. The performances of piezoelectric and flexoelectric cantilevers with the same dimensions and under the same conditions were compared. Owing to the flexoelectric scaling effect, under the same force input, the BST flexoelectric structure generated a higher charge output than its piezoelectric P(VDF-TrFE) and PMN-30PT counterparts when its thickness was less than 73.1 μm and 1.43 μm, respectively. Also, amplification of the charge output using the multilayered structure was then experimentally verified. The prototyped structure consisted of three layers of 350 μm-thick BST plates with a parallel electric connection. The charge output was approximately 287% of that obtained using a single-layer structure with the same total thickness of the multilayered structure under the same end deflection input, which suggests high sensitivity sensing can be achieved using multilayer flexoelectric structures. (paper)

  2. Alveolar bone repair with strontium- containing nanostructured carbonated hydroxyapatite.

    Science.gov (United States)

    Carmo, André Boziki Xavier do; Sartoretto, Suelen Cristina; Alves, Adriana Terezinha Neves Novellino; Granjeiro, José Mauro; Miguel, Fúlvio Borges; Calasans-Maia, Jose; Calasans-Maia, Monica Diuana

    2018-01-18

    This study aimed to evaluate bone repair in rat dental sockets after implanting nanostructured carbonated hydroxyapatite/sodium alginate (CHA) and nanostructured carbonated hydroxyapatite/sodium alginate containing 5% strontium microspheres (SrCHA) as bone substitute materials. Twenty male Wistar rats were randomly divided into two experimental groups: CHA and SrCHA (n=5/period/group). After one and 6 weeks of extraction of the right maxillary central incisor and biomaterial implantation, 5 μm bone blocks were obtained for histomorphometric evaluation. The parameters evaluated were remaining biomaterial, loose connective tissue and newly formed bone in a standard area. Statistical analysis was performed by Mann-Withney and and Wilcoxon tests at 95% level of significance. The histomorphometric results showed that the microspheres showed similar fragmentation and bio-absorbation (p>0.05). We observed the formation of new bones in both groups during the same experimental periods; however, the new bone formation differed significantly between the weeks 1 and 6 (p=0.0039) in both groups. The CHA and SrCHA biomaterials were biocompatible, osteoconductive and bioabsorbable, indicating their great potential for clinical use as bone substitutes.

  3. 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.

  4. High-frequency strontium vapor laser for biomedical applications

    Science.gov (United States)

    Hvorostovsky, A.; Kolmakov, E.; Kudashev, I.; Redka, D.; Kancer, A.; Kustikova, M.; Bykovskaya, E.; Mayurova, A.; Stupnikov, A.; Ruzankina, J.; Tsvetkov, K.; Lukyanov, N.; Paklinov, N.

    2018-02-01

    Sr-laser with high pulse repetition rate and high peak radiation power is a unique tool for studying rapidly occurring processes in time (plasma diagnostics, photoablation, etc.). In addition, the study of the frequency characteristics of the active medium of the laser helps to reveal the physics of the formation of an inverse medium in metal vapor lasers. In this paper, an experimental study of an Sr-laser with an active volume of 5.8 cm3 in the pulse repetition frequency range from 25 to 200 kHz is carried out, and a comparison with the frequency characteristics of media with large active volumes is given. We considered the frequency characteristics of the active medium in two modes: at a constant energy in the excitation pulse CU2 / 2 and at a constant average power consumed by the rectifier. In the presented work with a small-volume GRT using the TASITR-5/12 TASITRON switch, a laser was generated for Pairs of strontium at a CSF of 200 kHz. The behavior of the characteristics of the generation lines of 6.456 μm, 1 μm, and 3 μm at increased repetition frequencies is considered. Using the example of large-volume GRT, it is shown that tubes with a large active volume increase their energy characteristics with the growth of the CSF. The possibility of laser operation at pulse repetition rates above 200 kHz is shown.

  5. Osteodifferentiation of Human Preadipocytes Induced by Strontium Released from Hydrogels

    Directory of Open Access Journals (Sweden)

    Valeria Nardone

    2012-01-01

    Full Text Available In recent years, there has been an increasing interest in interactive application principles of biology and engineering for the development of valid biological systems for tissue regeneration, such as for the treatment of bone fractures or skeletal defects. The application of stem cells together with biomaterials releasing bioactive factors promotes the formation of bone tissue by inducing proliferation and/or cell differentiation. In this study, we used a clonal cell line from human adipose tissue-derived mesenchymal stem cells (hADSCs or preadipocytes, named PA2-E12, to evaluate the effects of strontium (Sr2+ released in the culture medium from an amidated carboxymethylcellulose (CMCA hydrogel enriched with different Sr2+ concentrations on osteodifferentiation. The osteoinductive effect was evaluated through both the expression of alkaline phophatase (ALP activity and the hydroxyapatite (HA production during 42 days of induction. Present data have shown that Sr2+ released from CMCA promotes the osteodifferentiation induced by an osteogenic medium as shown by the increase of ALP activity at 7 and 14 days and of HA production at 14 days. In conclusion, the use of biomaterials able to release in situ osteoinductive agents, like Sr2+, could represent a new strategy for future applications in bone tissue engineering.

  6. 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

  7. Tetrahidrokanabinol kao doping

    OpenAIRE

    Milošević, Marcela

    2015-01-01

    Doping je jedan od glavnih problema suvremenog sporta. Definira se kao kršenje jednog ili više antidopinških pravila definiranih odredbama Svjetskog antidopinškog kodeksa. Prema tri WADA-ina kriterija među doping sredstva spada i tetrahidrokarabinol, porijeklom iz biljke Cannabis sativa, Cannabinaceae. To je spoj iz skupine kanabinoida s najjačim psihoaktivnim djelovanjem. Za njegovo djelovanje zaslužni su mehanizmi farmakokinetike i farmakodinamike. Ovisno o načinu primjene apsorpcija mu var...

  8. X-ray fluorescence analysis of strontium in environmental water by using barium carbonate coprecipitation method

    International Nuclear Information System (INIS)

    Nishioka, Hiroshi; Yoneda, Akio; Maeda, Yoshimichi; Azumi, Takatugu

    1986-01-01

    Determination of strontium in environmental water was studied by a coprecipitation method with barium carbonate and the subsequent X-ray fluorescence analysis. Fifty mg of barium ion and 1 g of sodium carbonate were added to sample water, which was then mixed for one hour by a magnetic stirrer. Precipitate was gathered onto a membrane filter paper to measure its XF intensity. The amount of strontium from 2 to 150 μg could be repeatedly determined by means of the calibration curve method, and the limit of detection was found to be 0.6 μg of strontium. A large amount of calcium and magnesium ions was found to interfere with the coprecipitation of strontium ion. However, this interference could be eliminated by using a small amount of sample water. Strontium in several environmental waters was determined by the above method. The results obtained from the calibration curve method and the standard addition method agreed with each other, and also agreed with those from the atomic absorption spectrometry. (author)

  9. Development of an Age- and Gender-specific Model for Strontium Metabolism in Humans

    International Nuclear Information System (INIS)

    Shagina, N. B.; Degteva, M. O.; Tolstykh, E. I.

    2004-01-01

    This paper presents a development of a new biokinetic model for strontium, which accounts for age and gender differences of metabolism in humans. This model was developed based on the long-term follow-up of the residents living on the banks of the Techa River (Southern Urals, Russia) contaminated with 89,90Sr in 1950-1956. The new model uses the structure of ICRP model for strontium but model parameters have been estimated to account for age, gender and population differences in strontium retention and elimination. Estimates of age- and gender-specific model parameters were derived from (a) the results of long-term measurements of 90Sr-body burden for the Techa River population; (b) experimental studies of calcium and strontium metabolism in humans and (c) non-radiological data regarding bone metabolism (mineral content of the body, bone turnover, etc). As a result, the new model satisfactorily describes data on long-term retention of 90Sr in residents of the Techa River settlements of all ages and both genders and also data from studies during the period of global fallout in the UK and the USA and experimental data on strontium retention in humans. The new model can be used to calculate dose from 89,90Sr for the Techa River residents and also for other populations with similar parameters of skeletal maturation and also for other populations with similar parameters of skeletal maturation and involution. (Author) 27 refs

  10. Solvent extraction of strontium(II) as ion-pairs with tetraphenylborate anion

    International Nuclear Information System (INIS)

    Sekine, Tatsuya; Komatsu, Yu

    1975-01-01

    Solvent extraction of strontium(II) and sodium(I) as ion-pairs with tetraphenylborate ion(TBP - ) into nitrobenzene or hexane containing trioctylphosphine oxide (TOPO) has been determined under various conditions. The extraction of strontium(II) from water into nitrobenzene is rather independent of the extractant concentration but that into TOPO-hexane is second order dependent on the extractant, while the extraction of this metal ion from 0.1 mol dm -3 sodium perchlorate solution into nitrobenzene is second order dependent on the extractant concentration. The extraction of strontium(II) at a certain extractant concentration into nitrobenzene is greatly impaired by an addition of sodium perchlorate, while that into TOPO-hexane is not very much affected by the added salt. The extraction of sodium(I) with TPB - into TOPOP-hexane is complicated. On the basis of these results, separation of strontium(II) from cesium(I) or potassium(I) by extraction as ion-pairs with TPB - into nitrobenzene was considered. It was concluded that the separation is not possible in the absence of co-existing sodium salt in the aqueous phase; an effective masking agent for strontium(II) is necessary under such conditions. On the other hand, the separation is good in the presence of a sodium salt in the aqueous phase and the separation improves as the extractant concentration decreases. (author)

  11. [Adsorption behavior of immobilized nanometer barium-strontium titanate for cadmium ion in water].

    Science.gov (United States)

    Zhang, Dong; Zhang, Wen-Jie; Guan, Xin; Gao, Hong; He, Hong-Bo

    2009-03-01

    Nanometer barium-strontium titanate immobilized on silica gel G was successfully prepared by the citrate acid sol-gel method and characterized using X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transform infrared spectrophotometer (FTIR). By means of the determination of flame atomic absorption spectrometry (FAAS), the adsorption behavior of immobilized nanometer-barium strontium titanate for cadmium ion was investigated. The results showed that the nanometer barium-strontium titanate was immobilized on the silica gel G firmly, gaining a new sort of adsorbent. And the cadmium ion studied could be quantitatively retained in the pH value range of 4-7. The adsorption behavior followed a Freundlich adsorption isotherm and a pseudo-second-order kinetic model. The thermodynamic constants of the adsorption process, such as enthalpy changes (deltaH), Gibbs free energy changes (deltaG) and entropy changes (deltaS), were evaluated. These showed that the adsorption of cadmium ion by immobilized nanometer barium-strontium titanate was endothermic and spontaneous physical process. The cadmium ion adsorbed could be completely eluted using 1 mol x L(-1) HNO3. A new method for the determination of trace cadmium ion in water based on this immobilized nanometer barium-strontium titanate preconcentration and FAAS determination was proposed. The method has been applied to the determination of trace cadmium ion in tap water and river water with satisfactory results.

  12. Spontaneous reossification of the sella in transsphenoidal reoperation associated with strontium ranelate

    Directory of Open Access Journals (Sweden)

    Maria Mercedes Pineyro

    2017-07-01

    Full Text Available Spontaneous reossification of the sellar floor after transsphenoidal surgery has been rarely reported. Strontium ranelate, a divalent strontium salt, has been shown to increase bone formation, increasing osteoblast activity. We describe an unusual case of a young patient with Cushing’s disease who was treated with strontium ranelate for low bone mass who experienced spontaneous sellar reossification after transsphenoidal surgery. A 21-year-old male presented with Cushing’s features. His past medical history included delayed puberty diagnosed at 16 years, treated with testosterone for 3 years without further work-up. He was diagnosed with Cushing’s disease initially treated with transsphenoidal surgery, which was not curative. The patient did not come to follow-up visits for more than 1 year. He was prescribed strontium ranelate 2 g orally once daily for low bone mass by an outside endocrinologist, which he received for more than 1 year. Two years after first surgery he was reevaluated and persisted with active Cushing’s disease. Magnetic resonance image revealed a left 4 mm hypointense mass, with sphenoid sinus occupation by a hyperintense material. At repeated transsphenoidal surgery, sellar bone had a very hard consistency; surgery was complicated and the patient died. Sellar reossification negatively impacted surgery outcomes in this patient. While this entity is possible after transsphenoidal surgery, it remains unclear whether strontium ranelate could have affected sellar ossification.

  13. Decomposition pathways of polytetrafluoroethylene by co-grinding with strontium/calcium oxides.

    Science.gov (United States)

    Qu, Jun; He, Xiaoman; Zhang, Qiwu; Liu, Xinzhong; Saito, Fumio

    2017-06-01

    Waste polytetrafluoroethylene (PTFE) could be easily decomposed by co-grinding with inorganic additive such as strontium oxide (SrO), strontium peroxide (SrO 2 ) and calcium oxide (CaO) by using a planetary ball mill, in which the fluorine was transformed into nontoxic inorganic fluoride salts such as strontium fluoride (SrF 2 ) or calcium fluoride (CaF 2 ). Depending on the kind of additive as well as the added molar ratio, however, the reaction mechanism of the decomposition was found to change, with different compositions of carbon compounds formed. CO gas, the mixture of strontium carbonate (SrCO 3 ) and carbon, only SrCO 3 were obtained as reaction products respectively with equimolar SrO, excess SrO and excess SrO 2 to the monomer unit CF 2 of PTFE were used. Excess amount of CaO was needed to effectively decompose PTFE because of its lower reactivity compared with strontium oxide, but it promised practical applications due to its low cost.

  14. Equilibrium sorption of cobalt, cesium, and strontium on Bandelier Tuff: analysis of alternative mathematical modeling

    International Nuclear Information System (INIS)

    Polzer, W.L.; Fuentes, H.R.; Essington, E.H.; Roensch, F.R.

    1985-01-01

    Sorption isotherms are derived from batch equilibrium data for cobalt, cesium and strontium on Bandelier Tuff. Experiments were conducted at an average temperature of 23 0 C and equilibrium was defined at 48 hours. The solute concentrations ranged from 0 to 500 mg/L. The radioactive isotopes 60 Co, 137 Cs, and 85 Sr were used to trace the sorption of the stable solutes. The Linear, Langmuir, Freundlich and a Modified Freundlich isotherm equations are evaluated. The Modified Freundlich isotherm equation is validated as a preferred general mathematical tool for representing the sorption of the three solutes. The empirical constants derived from the Modified Freundlich isotherm equation indicate that under dynamic flow conditions strontium will move most rapidly and cobalt least rapidly. On the other hand, chemical dispersion will be greatest for cesium and least for strontium. Hill Plots of the sorption data suggest that in the region of low saturation sorption of all three solutes is impeded by interactions among sorption sites; cobalt exhibits the greatest effect of interactions and strontium shows only a minimal effect. In the saturation region of 50% or more, sorption of cobalt is enhanced slightly by interactions among sorption sites whereas sorption of cesium and strontium appears to be independent of site interactions. 9 references, 4 figures, 2 tables

  15. Fabrication of gelatin-strontium substituted calcium phosphate scaffolds with unidirectional pores for bone tissue engineering.

    Science.gov (United States)

    Wu, Yu-Chun; Lin, Wei-Yu; Yang, Chyun-Yu; Lee, Tzer-Min

    2015-03-01

    This study fabricated homogeneous gelatin-strontium substituted calcium phosphate composites via coprecipitation in a gelatin solution. Unidirectional porous scaffolds with an oriented microtubular structure were then manufactured using freeze-drying technology. The resulting structure and pore alignment were determined using scanning electron microscopy. The pore size were in the range of 200-400 μm, which is considered ideal for the engineering of bone tissue. The scaffolds were further characterized using energy dispersive spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. Hydroxyapatite was the main calcium phosphate compound in the scaffolds, with strontium incorporated into the crystal structure. The porosity of the scaffolds decreased with increasing concentration of calcium-phosphate. The compressive strength in the longitudinal direction was two to threefold higher than that observed in the transverse direction. Our results demonstrate that the composite scaffolds degraded by approximately 20 % after 5 weeks. Additionally, in vitro results reveal that the addition of strontium significantly increased human osteoblastic cells proliferation. Scaffolds containing strontium with a Sr-CaP/(gelatin + Sr-CaP) ratio of 50 % provided the most suitable environment for cell proliferation, particularly under dynamic culture conditions. This study demonstrates the considerable potential of composite scaffolds composed of gelatin-strontium-substituted calcium phosphate for applications in bone tissue engineering.

  16. Strontium-90 and cesium-137 in soil (from May 1985 to Jul. 1985)

    International Nuclear Information System (INIS)

    1985-01-01

    This report is aimed at listing measurements of strontium-90 and cesium-137 in soil made at eight places across Japan during the period from May to July in 1985. Collection and pretreatment methods are described for samples of rain and dry fallout, airborne dust, service water and freshwater, soil, sea water, sea sediments, total diet, rice, milk, vegetables, tea, as well as fish, shellfish and seaweeds. The methods for the preparation of these samples for analysis are also outlined. Sample solutions were neutralized with sodium hydroxide, and the precipitate of strontium and calcium carbonates was separated after sodium carbonate was added. The supernatant solution was retained for cesium-137 determination. After being precipitated as oxalates, strontium and calcium were separated by successive fuming nitric acid separations. For the determination of stable strontium, calcium and potassium, soil and sediment were treated with sodium hydroxide and hydrochloric acid for extraction while other samples were ashed and digested. Calcium, separated as oxalate, was determined by titration while stable strontium and potassium were determined by atomic absorption and flame emission spectroscopy, respectively. Couting for activity was carried out using low background beta counters normally for 60 min. (Nogami, K.)

  17. Removal of Strontium from Drinking Water by Conventional Treatment and Lime Softening in Bench-Scale Studies

    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 immedia...

  18. Development of technology for the production of pure strontium carbonate (99.95%) from the celestite ore

    International Nuclear Information System (INIS)

    Malik, M.S.; Iqbal, M.J.; Hussain, S.I.

    2004-01-01

    The objective of these studies is to develop a simple and economically viable process for the production of strontium carbonate of high purity (99.95 %) utilizing the indigenous deposits of the celestite ore which on the average contain 91.75 % strontium sulphate as the major primary constituent. A composite sample of celestite ore was pulverized and upgraded to contain 99.01 % strontium sulphate by treating with 10 % hydrochloric acid at room temperature, thus iron and carbonates of calcium and magnesium present in the ore were leached out. The beneficiated or the upgraded ore thus obtained was treated with 20 % excess soda ash at 80 degree C for 90 minutes. The crude strontium carbonate was again treated with dilute hydrochloric acid at room temperature and the resultant solution of strontium chloride so obtained was treated with 15 % solution of sodium carbonate. Pure strontium carbonate produced was thoroughly washed with deionized water and dried at 105 degree C for 12 hrs. Thus at optimum parameters of the process, 98.5 % strontium sulphate contained in the upgraded ore was converted to strontium carbonate and the final product obtained was of high purity (99.95 %). (author)

  19. Research on a pellet co-precipitation micro-filtration process for the treatment of liquid waste containing strontium

    International Nuclear Information System (INIS)

    Xin Luo; North China Institute of Science and Technology, Beijing; Guanghui Zhang; Xue Wang; Ping Gu

    2013-01-01

    The chemical precipitation method for radioactive wastewater treatment has the advantages of being simple and cost-effective. However, difficulties with the solid–liquid separation and sludge concentration restrict the application of this method. In this paper, a pellet co-precipitation micro-filtration (PCM) process was studied for treating strontium-containing wastewater on a laboratory scale. The seed was prepared by CaCO 3 powders. Sr 2+ and CO 3 2- were constantly crystallised on the seed surface, with Na 2 CO 3 as the precipitating agent in the pellet reactor. The following membrane separator with the addition of FeCl 3 enhanced the treatment effect. The average strontium concentrations in the raw water and in the effluent were 12.0 and 0.0220 mg/L, respectively. The strontium decontamination factor (DF) increased with the operation time, with an average value of 577. The precipitate particles formed gradually grew larger, with good sedimentation properties. When the experiment was complete, the formed precipitate was separated easily from the liquid phase and directly discharged. The concentration factor (CF) was 1,958. In the PCM process, crystallisation was the main mechanism for strontium removal, with the influent strontium level playing an important role. Membrane pore blockage and cake layer formation could help to further intercept the strontium crystallites. Furthermore, ferric chloride coagulation in the membrane separator also contributed to strontium removal. The PCM process has potential for wider application in the removal of strontium from wastewater. (author)

  20. 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

  1. Determination of strontium and lead isotope ratios of grains using high resolution inductively coupled plasma mass spectrometer with single collector

    International Nuclear Information System (INIS)

    Shinozaki, Miyuki; Ariyama, Kaoru; Kawasaki, Akira; Hirata, Takafumi

    2010-01-01

    A method for determining strontium and lead isotope ratios of grains was developed. The samples investigated in this study were rice, barley and wheat. The samples were digested with nitric acid and hydrogen peroxide, and heated in a heating block. Strontium and lead were separated from the matrix by adding an acid digested solution into a column packed with Sr resin, which has selectivity for the absorption of strontium and lead. Strontium and lead isotope ratios were determined using a high-resolution inductively coupled plasma mass spectrometer (HR-ICP-MS) with a single collector. The intraday relative standard deviations of 87 Sr/ 86 Sr and lead isotope ratios ( 204 Pb/ 206 Pb, 207 Pb/ 206 Pb, 208 Pb/ 206 Pb) by HR-ICP-MS measurements were < 0.06% and around 0.1%, respectively. This method enabled us to determine strontium and lead isotope ratios in two days. (author)

  2. Ecological Dose Modeling of Aquatic and Riparian Receptors to Strontium-90 with an Emphasis on Radiosensitive Organs

    Energy Technology Data Exchange (ETDEWEB)

    Poston, Ted M.; Traub, Richard J.; Antonio, Ernest J.

    2011-07-20

    The 100-NR-2 site is the location of elevated releases of strontium-90 to the Columbia River via contaminated groundwater. The resulting dose to aquatic and riparian receptors was evaluated in 2005 (DOE 2009) and compared to U.S. Department of Energy (DOE) dose guidance values. We have conducted additional dose assessments for a broader spectrum of aquatic and riparian organisms using RESRAD Biota and specific exposure scenarios. Because strontium-90 accumulates in bone, we have also modeled the dose to the anterior kidney, a blood-forming and immune system organ that lies close to the spinal column of fish. The resulting dose is primarily attributable to the yttrium-90 progeny of strontium-90 and very little of the dose is associated with the beta emission from strontium-90. All dose modeling results were calculated with an assumption of secular equilibrium between strontium-90 and yttrum-90.

  3. Doping in sport

    African Journals Online (AJOL)

    Objective. To determine the attitudes, beliefs and knowledge of talented young athletes residing in Gauteng regarding prohibited performance-enhancing drugs (PEDs) and anti-doping rules and regulations. Methods. This was a survey study using a quantitative research approach. South African TuksSport academy ...

  4. Doped barium titanate nanoparticles

    Indian Academy of Sciences (India)

    We have synthesized nickel (Ni) and iron (Fe) ion doped BaTiO3 nanoparticles through a chemical route using polyvinyl alcohol (PVA). The concentration of dopant varies from 0 to 2 mole% in the specimens. The results from X-ray diffractograms and transmission electron micrographs show that the particle diameters in the ...

  5. Doped barium titanate nanoparticles

    Indian Academy of Sciences (India)

    Wintec

    Abstract. We have synthesized nickel (Ni) and iron (Fe) ion doped BaTiO3 nanoparticles through a chemical route using polyvinyl alcohol (PVA). The concentration of dopant varies from 0 to 2 mole% in the specimens. The results from X-ray diffractograms and transmission electron micrographs show that the particle ...

  6. Role Models on Dope

    DEFF Research Database (Denmark)

    Christiansen, Ask Vest; Gleaves, John

    2014-01-01

    Compared to football-players cyclists are virtuous role models. Yes, Lance Armstrong, Michael Rasmussen and other riders have doped, and because of this they have received the predicate as the most immoral athletes in the sporting world. But if morality is not only a question of whether a person...

  7. BLOOD DOPING AND RISKS

    Directory of Open Access Journals (Sweden)

    Goran Vasić

    2015-05-01

    Full Text Available Doping is the way in which athletes misuse of chemicals and other types of medical interventions (eg, blood replacement, try to get ahead in the results of other athletes or their performance at the expense of their own health. The aim of this work is the analysis of blood doping and the display of negative consequences that this way of increasing capabilities brings. Method: The methodological work is done descriptively. Results: Even in 1972 at the Stockholm Institute for gymnastics and sport, first Dr. Bjorn Ekblom started having blood doping. Taken from the blood, athletes through centifuge separating red blood cells from blood plasma, which is after a month of storage in the fridge, every athlete back into the bloodstream. Tests aerobic capacity thereafter showed that the concerned athletes can run longer on average for 25% of the treadmill than before. Discussion: Blood doping carries with it serious risks, excessive amount of red cells “thickens the blood,” increased hematocrit, which reduces the heart’s ability to pump blood to the periphery. All this makes it difficult for blood to flow through blood vessels, and there is a great danger that comes to a halt in the circulation, which can cause cardiac arrest, stroke, pulmonary edema, and other complications that can be fatal.

  8. Bench-scale treatability studies for simulated incinerator scrubber blowdown containing radioactive cesium and strontium

    International Nuclear Information System (INIS)

    Coroneos, A.C.; Taylor, P.A.; Arnold, W.D. Jr.; Bostick, D.A.; Perona, J.J.

    1994-12-01

    The purpose of this report is to document the results of bench-scale testing completed to remove 137 Cs and 90 Sr from the Oak Ridge K-25 Site Toxic Substances Control Act (TSCA) Incinerator blowdown at the K-25 Site Central Neutralization Facility, a wastewater treatment facility designed to remove heavy metals and uranium from various wastewaters. The report presents results of bench-scale testing using chabazite and clinoptilolite zeolites to remove cesium and strontium; using potassium cobalt ferrocyanide (KCCF) to remove cesium; and using strontium chloride coprecipitation, sodium phosphate coprecipitation, and calcium sulfate coprecipitation to remove strontium. Low-range, average-range, and high-range concentration blowdown surrogates were used to complete the bench-scale testing

  9. Forecast of strontium 90 accumulation in the crop of agricultural cultures

    International Nuclear Information System (INIS)

    Dergunov, I.D.; Moroz, V.D.

    1980-01-01

    A possibility to determine the level of contamination with strontium-90 of agricultural crops according to its content in young plants as studied. The investigations have been carried out under conditions of vegetational experiment with cotton on light, typical, dark grey soils and meadow spoils. The samples in the phase of 20 day old plants and in the period of ripening have been selected for radiometric analysis. Activity has been measured according to β-irradiation of nuclide. Tbe measurement results point to the existence of certain connection between radiostrontium content in young plants and in the fibre crops. Close connection is also found between strontium-90 content in young plants and in the cotton seeds. Direct proportional dependence between strontium-90 content in young and grown-up plants is established. Linear coefficients for cotton are obtained which can be used for forecasting the level of cotton fibre contamination with radiostrontium according to its content in 20 day old plants

  10. Strontium-90 and cesium-137 in freshwater (from Sept. 1983 to Dec. 1983)

    International Nuclear Information System (INIS)

    1983-01-01

    Fresh water, 100 l each, was collected, and to which the carriers of strontium and cesium were added immediately after the sampling. The sample was vigorously stirred and filtered, and passed through a cation exchange column. Strontium and cesium were eluted with hydrochloric acid from the cation exchange column. The eluate was used for radiochemical analysis. The chemical separation of strontium-90 and cesium-137 was carried out, and the chemical yields were determined. The precipitates were counted for the activity using low background beta counters normally for 60 min. The net sample counting rate was corrected for the counter efficiency, recovery, self-absorption and decay, to obtain the radioactivity per sample aliquot, and the concentrations of these nuclides in the original samples were calculated. The data at six sampling locations in Japan from September to December, 1983, on fresh water are reported. (Kako, I.)

  11. Corrosion protection performance of porous strontium hydroxyapatite coating on polypyrrole coated 316L stainless steel.

    Science.gov (United States)

    Gopi, D; Ramya, S; Rajeswari, D; Kavitha, L

    2013-07-01

    Polypyrrole/strontium hydroxyapatite bilayer coatings were achieved on 316L stainless steel (316L SS) by the electropolymerisation of pyrrole from sodium salicylate solution followed by the electrodeposition of porous strontium hydroxyapatite. The formation and the morphology of the bilayer coatings were characterised by Fourier transform infrared spectroscopy (FT-IR) and high resolution scanning electron microscopy (HRSEM), respectively. The corrosion resistance of the coated 316L SS specimens was investigated in Ringer's solution by electrochemical techniques and the results were substantiated with inductively coupled plasma atomic emission spectrometry (ICP-AES). The passive film underneath the polypyrrole layer is effective in protecting 316L SS against corrosion in Ringer's solution. Moreover, we believe that the top porous strontium hydroxyapatite layer can provide potential bioactivity to the 316L SS. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Fundamental studies of novel zwitterionic hybrid membranes: kinetic model and mechanism insights into strontium removal.

    Science.gov (United States)

    Zhu, Wen; Liu, Junsheng; Li, Meng

    2014-01-01

    A series of zwitterionic hybrid membranes were prepared via the ring opening of 1,3-propanesultone with the amine groups in the chains of TMSPEDA and a subsequent sol-gel process. Their kinetic models for strontium removal were investigated using three two-parameter kinetic equations (i.e., Lagergren pseudo-first order, pseudo-second order, and Elovich models). Adsorption mechanism was evaluated using intraparticle diffusion model, diffusion-chemisorption model, and Boyd equation. It was found that the adsorption of strontium ions on these zwitterionic hybrid membranes fitted well with the Lagergren pseudo-second order model. Mechanism insights suggested that diffusion-chemisorption was one of the main adsorption mechanisms. Boyd equation exhibited that film-diffusion mechanism might be the control process during the starting period. These findings are very useful in strontium removal from the stimulated radioactive wastewater.

  13. Fundamental Studies of Novel Zwitterionic Hybrid Membranes: Kinetic Model and Mechanism Insights into Strontium Removal

    Directory of Open Access Journals (Sweden)

    Wen Zhu

    2014-01-01

    Full Text Available A series of zwitterionic hybrid membranes were prepared via the ring opening of 1,3-propanesultone with the amine groups in the chains of TMSPEDA and a subsequent sol-gel process. Their kinetic models for strontium removal were investigated using three two-parameter kinetic equations (i.e., Lagergren pseudo-first order, pseudo-second order, and Elovich models. Adsorption mechanism was evaluated using intraparticle diffusion model, diffusion-chemisorption model, and Boyd equation. It was found that the adsorption of strontium ions on these zwitterionic hybrid membranes fitted well with the Lagergren pseudo-second order model. Mechanism insights suggested that diffusion-chemisorption was one of the main adsorption mechanisms. Boyd equation exhibited that film-diffusion mechanism might be the control process during the starting period. These findings are very useful in strontium removal from the stimulated radioactive wastewater.

  14. Effects of mineralogy on the 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.

    1990-01-01

    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 clinoptilolite based on the content of clinoptilolite in the Calico Hills Tuff. If sorption onto Calico Hills Tuff is solely due to the presence of clinoptilolite, then the ratios of the sorption ratios on tuff to those on clinoptilolite at similar conditions should be the weight fraction of the clinoptilolite in the tuff. The experimental evidence showed that the ratios were generally near 0.5 for both cesium and strontium sorption and that ion-exchange processes were operative for the clinoptilolite and the tuff. However, the ratios differed to a small extent for different conditions, and there were indications that other sorption processes were also involved. 7 refs., 7 figs., 2 tabs

  15. Studies of cesium and strontium migration in unconsolidated Canadian geological materials

    International Nuclear Information System (INIS)

    Gillham, R.W.; Lindsay, L.E.; Reynolds, W.D.; Kewen, T.J.; Cherry, J.A.; Reddy, M.R.

    1981-06-01

    Distribution coefficients (Ksub(d)) were measured for cesium and strontium in 16 samples of Canadian unconsolidated geological materials. The samples were collected to cover a wide range of grain size, clay-mineral composition, cation exchange capacity and carbonate mineral content. Distribution coefficients ranged between 10 2 and 2.0 x 10 4 ml/g for cesium and between 2.5 and 10 2 ml/g for strontium, indicating that most unconsolidated geological materials have a substantial ability to retard the migration of cesium, while strontium could generally be expected to be somewhat more mobile. The measured K values were not significantly correlated with the measured soil properties, but appeared to be significantly affected by the background concentration of stable isotopes of the respective radionuclides

  16. Strontium-90 and cesium-137 in soil from May 1984 to July 1984

    International Nuclear Information System (INIS)

    1984-01-01

    Strontium-90 and cesium-137 in soil measured throughout Japan from May to July 1984 are given in pCi/kg and mCi/km 2 . Sampling points are total of 8 from Kawabe-gun (Akita) to Ibasuki-gun (Kagoshima). 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. Soil was collected from the location in the spacious and flat area without past disturbance on the surface. Soil was taken from two layers of different depths, 0 aproximately 5 cm and 5 approximately 20 cm. After the radiochemical separation, the mounted precipitates were counted for activity using low background beta counters normally for 60 minutes. (Mori, K.)

  17. Preparation and characterization of nanofibers barium strontium titanate using electrospinning route

    International Nuclear Information System (INIS)

    Faraco, B.S.; Engel, A.B.; Alves, A.K.; Bergmann, C.P.

    2011-01-01

    The barium strontium titanate (BST) is a ferroelectric material well known for exhibiting a ferroelectric transition temperature that can be adjusted by varying the Ba /Sr ratio. The reduction of the Curie point can be achieved by the substitution of strontium for barium. Due to the combination of interesting properties, such as high crystallographic orientation of grains and high thermal stability, ferroelectric fibers have attracted considerable interest for their potential use as functional ceramic fibers in the reinforcement of ceramics and metals. The electrospinning process is an effective method for the preparation of nano ceramic fibers with uniform diameter and having different composition. The objective of this work was to product and to characterize the structure and morphology of barium strontium titanate nanofibers made using the electrospinning method. (author)

  18. Poisoning effect of bismuth on modification behaviour of strontium in LM25 alloy

    International Nuclear Information System (INIS)

    Farahany, S.; Ourdjini, A.; Idris, M.H.; Thai, L.T.

    2011-01-01

    Nucleation and growth, temperature measurements and microstructure observations of silicon phase are presented for strontium modified Al-7% Si (LM25) cast alloy treated with bismuth. The results show that addition of bismuth in strontium modified alloys may have a poisoning effect resulting in lost modification of the silicon phase. With increasing Bi/Sr ratio, thermal analysis measurements showed that the eutectic growth temperature increased remarkably to 573 deg C and recalescence decreased to 0.2 deg C and the morphology of silicon displayed the same flake-like structure as in the unmodified alloys. Microstructural observation showed that a minimum Bi/Sr ratio of 1.2 which is equivalent to a Sr/Bi ratio of 0.43 is required for effective strontium modification and neutralization of the poisoning effect of bismuth. (author)

  19. Bioactivity and corrosion properties of novel coatings containing strontium by micro-arc oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Kung, Kuan-Chen [Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan (China); Lee, Tzer-Min, E-mail: tmlee@mail.ncku.edu.t [Institute of Oral Medicine, National Cheng Kung University, Tainan, Taiwan (China); Lui, Truan-Sheng [Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan (China)

    2010-10-22

    Research highlights: The dental implant of titanium could be modified by anodic oxidation. It was found that incorporation of strontium ions into the matrix increase the bone formation. In this study, we try to investigate the effect of corrosion property and bioactivity on coatings containing strontium by anodic oxidation. The results suggest that coatings containing strontium on titanium by anodic oxidation has the potential to show the stability and bioactivity in the clinical use. - Abstract: Pure titanium (Ti) and titanium alloys are considered as bio-inert materials in clinical use. Bioactivity is the ability to induce bone-like apatite on the material surface. The micro-arc oxidation (MAO) technique is an effective method for improving the surface properties of titanium. The aim of this study was to investigate the bioactivity and corrosion behavior of MAO coatings containing strontium, which is beneficial for biological performance. The bioactivity of materials was evaluated based on the ability to induce a bond-like apatite layer on the surface in simulated body fluid (SBF), as proposed by Kokubo et al. After the materials were soaked in SBF for 1 day, precipitates formed on the surface of MAO coating. The surface of MAO coatings was completely covered with precipitates after 7 days. The precipitates, which were found to be composed of fiber structures, were identified as the apatite phase using thin film X-ray diffraction (TF-XRD). The results show that MAO coatings containing strontium can induce the formation of an apatite layer on their surface. In the potentiodynamic test, MAO coatings exhibited a more noble corrosion potential (E{sub corr}) than that of titanium in SBF. In the passive region, the current density of MAO coatings was lower than that of titanium. All findings in this study indicated that MAO coatings containing strontium have good bioactivity and corrosion resistance for clinical applications.

  20. Development of novel strontium containing bioactive glass based calcium phosphate cement.

    Science.gov (United States)

    D'Onofrio, A; Kent, N W; Shahdad, S A; Hill, R G

    2016-06-01

    The aim of this study was to investigate the effect on properties of increasing strontium substitution for calcium in bioactive glasses used as precursors for novel calcium phosphate cements. Glasses were produced by progressively substituting strontium for calcium. Cements were prepared by mixing the glass powder with Ca(H2PO4)2 powder with a 2.5% solution of Na2HPO4. Setting times and compressive strength were measured after 1h, 1 day, 7 days and 28 days immersion in Tris buffer solution. X-ray diffraction (XRD), Fourier transform infrared spectroscopy and radiopacity were measured and crystal morphology was assessed using scanning electron microscopy. A correlation between the phases formed, morphology of the crystallites, setting time and compressive strength were analyzed. Setting time increased proportionally with strontium substitution in the glass up to 25%, whereas for higher substitutions it decreased. Compressive strength showed a maximum value of 12.5MPa and was strongly influenced by the interlocking of the crystals and their morphology. XRD showed that the presence of strontium influenced the crystal phases formed. Octacalcium phosphate (Ca8H2(PO4)6·5H2O, OCP) was the main phase present after 1h and 1 day whereas after 28 days OCP was completely transformed to strontium-containing hydroxyapatite (SrxCa(10-x)(PO4)6(OH)2, SrHA). Radiopacity increased proportionally to strontium substitution in the glass. A novel method to develop a bone substitute forming in vitro SrHA as a final product by using a bioactive glass as a precursor was shown. These novel injectable bioactive glass cements are promising materials for dental and orthopedic applications. Further in vivo characterizations are being conducted. Copyright © 2016 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  1. Non-Fickian dispersive transport of strontium in laboratory-scale columns: Modelling and evaluation

    Science.gov (United States)

    Liu, Dongxu; Jivkov, Andrey P.; Wang, Lichun; Si, Gaohua; Yu, Jing

    2017-06-01

    In the context of environmental remediation of contaminated sites and safety assessment of nuclear waste disposal in the near-surface zone, we investigate the leaching and non-Fickian dispersive migration with sorption of strontium (mocking strontium-90) through columns packed with sand and clay. Analysis is based on breakthrough curves (BTCs) from column experiments, which simulated rainfall infiltration and source term release scenario, rather than applying constant tracer solution at the inlet as commonly used. BTCs are re-evaluated and transport parameters are estimated by inverse modelling using two approaches: (1) equilibrium advection-dispersion equation (ADE); and (2) continuous time random walk (CTRW). Firstly, based on a method for calculating leach concentration, the inlet condition with an exponential decay input is identified. Secondly, the results show that approximately 39%-58% of Br- and 16%-49% of Sr2+ are eluted from the columns at the end of the breakthrough experiments. This suggests that trapping mechanisms, including diffusion into immobile zones and attachment of tracer on mineral surfaces, are more pronounced for Sr2+ than for Br-. Thirdly, we demonstrate robustness of CTRW-based truncated power-law (TPL) model in capturing non-Fickian reactive transport with 0 2. The non-Fickian dispersion observed experimentally is explained by variations of local flow field from preferential flow paths due to physical heterogeneities. Particularly, the additional sorption process of strontium on clay minerals contributes to the delay of the peak concentration and the tailing features, which leads to an enhanced non-Fickian transport for strontium. Finally, the ADE and CTRW approaches to environmental modelling are evaluated. It is shown that CTRW with a sorption term can describe non-Fickian dispersive transport of strontium at laboratory scale by identifying appropriate parameters, while the traditional ADE with a retardation factor fails to reproduce

  2. Use of Strontium Chloride for the Treatment of Osteoporosis: A Case Report.

    Science.gov (United States)

    Westberg, Sarah M; Awker, Amy; Torkelson, Carolyn J

    2016-03-01

    Context • Strontium ranelate is an approved prescription medication for the treatment of osteoporosis in Europe. In the United States, the only available forms of strontium are those that are nonprescription, dietary supplements. Some patients with osteoporosis use those products because they prefer an alternate treatment to conventional therapy. Currently, no controlled trials have been conducted on the effectiveness of the supplements for treating osteoporosis. Objective • The study intended to examine how one woman responded to the use of strontium chloride. Design • This was a retrospective case study. Setting • The woman in the case study was a patient in an academic urban women's health clinic in Minneapolis, MN, USA. Participant • The participant was a postmenopausal woman with a history of vertebral fracture. Intervention • The participant took 680 mg daily of strontium chloride for 2.5 y. Outcome Measures • The patient had begun receiving dual-energy X-ray absorptiometry (DXA) scans in 2004 and continued to receive follow-up scans every 2 y. After beginning strontium therapy in December 2011, she received DXA scans in March 2012 and May 2014. Results • During the study, the analysis of the patient's DXA scans showed a positive increase in the bone mineral density (BMD) of her vertebrae and her right hip and maintenance of her BMD in her left hip. Conclusions • Although the current case report does not provide enough evidence to conclude that US dietary supplements of strontium are effective in preventing fractures, it demonstrates a positive experience for one patient.

  3. Separation of americium (III) and strontium (II) using TEHDGA and 18-crown-6

    Energy Technology Data Exchange (ETDEWEB)

    Sinharoy, Prithwish; Khan, Pasupati Nath; Nair, Deepika; Jagasia, Poonam; Dhami, P.S.; Kaushik, C.P.; Banerjee, Kalyan [Bhabha Atomic Research Centre, Mumbai (India). Nuclear Recycle Group; Anitha, M. [Bhabha Atomic Research Centre, Mumbai (India). Rare Earth Development Section; Sharma, J.N. [Bhabha Atomic Research Centre, Mumbai (India). Process Development Div.

    2017-06-01

    This work describes extraction of Am(III) and Sr(II) together with tetra(2-ethylhexyl) diglycolamide (TEHDGA) and selective back-extraction of strontium with a strontium complexant, 18-crown-6, leading to their separation from each other. 0.3 M TEHDGA+5% isodecyl alcohol/n-dodecane was used to extract Am(III) and Sr(II) from 4 M nitric acid into organic phase with very high D (D{sub Am}=1000, D{sub Sr}=22) and 0.1 M 18-crown-6 dissolved in 4 M nitric acid is used for selective stripping of Sr(II) from loaded extract phase. Am(III) left in the extract phase was then stripped with 0.01 M nitric acid. Stripping of Sr(II) was found to increase with increase in 18-crown-6 concentration, at 0.1 M 18-crown-6 dissolved in 4 M nitric acid, 83% of the loaded strontium (D{sub Sr}=0.20) was back-extracted in a single contact while loss of Am(III) was 0.8% (D{sub Am}=122.45). Stoichiometry limit of 1:1 was observed between strontium and 18-crown-6. Strontium was precipitated and separated from the complexant by Na{sub 2}SO{sub 4} or Na{sub 2}CO{sub 3}. This process was tested with simulated solution of high level waste and found suitable for quantitative recovery of strontium with high purity.

  4. Strontium isotopes as an indicator for groundwater salinity sources in the Kirkuk region, Iraq

    Energy Technology Data Exchange (ETDEWEB)

    Sahib, Layth Y. [Institute for Applied Geosciences, Technische Universität Darmstadt, Schnittspahnstraße 9, 64287 Darmstadt (Germany); Geology Department, College of Science, University of Baghdad, Jadreya, Baghdad (Iraq); Marandi, Andres; Schüth, Christoph [Institute for Applied Geosciences, Technische Universität Darmstadt, Schnittspahnstraße 9, 64287 Darmstadt (Germany)

    2016-08-15

    The Kirkuk region in northern Iraq hosts some of the largest oil fields in the Middle East. Several anticline structures enabled vertical migration and entrapment of the oil. Frequently, complex fracture systems and faults cut across the Eocene and middle Oligocene reservoirs and the cap rock, the Fatha Formation of Miocene age. Seepage of crude oil and oil field brines are therefore a common observation in the anticline axes and contamination of shallow groundwater resources is a major concern. In this study, 65 water samples were collected in the Kirkuk region to analyze and distinguish mixing processes between shallow groundwater resources, uprising oil field brines, and dissolution of gypsum and halite from the Fatha Formation. Hydrochemical analyses of the water samples included general hydrochemistry, stable water isotopes, as well as strontium concentrations and for 22 of the samples strontium isotopes ({sup 87}Sr/{sup 86}Sr). Strontium concentrations increased close to the anticline axes with highest concentrations in the oil field brines (300 mg/l). Strontium isotopes proved to be a valuable tool to distinguish mixing processes as isotope signatures of the oil field brines and of waters from the Fatha Formation are significantly different. It could be shown, that mixing of shallow groundwater with oil field brines is occurring close to the major fault zones in the anticlines but high concentrations of strontium in the water samples are mainly due to dissolution from the Fatha Formation. - Highlights: • This field study evaluates the salinity sources in the groundwater in Kirkuk region. • Salinity is related to evaporates dissolving and/or mixing with oil field brine. • Strontium isotopes proved to be a valuable tool to distinguish mixing processes.

  5. The strontium isotopic composition of seawater, and seawater-oceanic crust interaction

    International Nuclear Information System (INIS)

    Spooner, E.T.C.

    1976-01-01

    The 87 Sr/ 86 Sr ratio of seawater strontium (0.7091) is less than the 87 Sr/ 86 Sr ratio of dissolved strontium delivered to the oceans by continental run-off (approximately 0.716). Isotope exchange with strontium isotopically lighter oceanic crust during hydrothermal convection within spreading oceanic ridges can explain this observation. In quantitative terms, the current 87 Sr/ 86 Sr ratio of seawater (0.7091) may be maintained by balancing the continental run-off flux of strontium (0.59 x 10 12 g/yr) against a hydrothermal recirculation flux of 3.6 x 10 12 g/yr, during which the 87 Sr/ 86 Sr ratio of seawater drops by 0.0011. A concomitant mean increase in the 87 Sr/ 86 Sr ratio of the upper 4.5 km of oceanic crust of 0.0010 (0.7029-0.7039) should be produced. This required 87 Sr enrichment has been observed in hydrothermally metamorphosed ophiolitic rocks from the Troodos Massif, Cyprus. The post-Upper Cretaceous increase in the strontium isotopic composition of seawater (approximately 0.7075-0.7091) covaries smoothly with inferred increase in land area. This suggests that during this period the main factor which has caused variability in the 87 Sr/ 86 Sr ratio of seawater strontium could have been variation in the magnitude of the continental run-off flux caused by variation in land area. Variations in land area may themselves have been partly a consequence of variations in global mean sea-floor spreading rate. (Auth.)

  6. Isolation of radioactive strontium from natural samples. Separation of strontium from alkaline and alkaline earth elements by means of mixed solvent anion exchange

    International Nuclear Information System (INIS)

    Grahek, Z.; Kosutic, K.; Lulic, S.; Kvastek, K.; Eskinja, I.

    1999-01-01

    This paper presents the results of studies which led to the procedures for the chromatographic separation of radioactive strontium from alkaline, earth-alkaline and other elements in natural samples, on columns filled with strong base anion exchangers using alcoholic solutions of nitric acid as eluents. It has been shown that potassium, caesium, calcium, barium, yttrium and strontium can be adsorbed on strong base anion exchangers of the Dowex and Amberlite type, which contain the quaternary ammonium group with nitrate as counter-ion, from solutions of nitric acid in alcohol. Adsorption strength increases in the order methanol 3 in methanol, while they are adsorbed from ethanol and propanol. The adsorption strength is influenced by the polarity of alcohol, by the concentration of nitrate and by pH. The strength with which strontium adsorbs on the exchangers increases in the interval from 0 to 0.25M NH 4 NO 3 in methanol, after which it starts to decrease. Strontium adsorbs to the exchangers from the alcoholic solution of ammonium nitrate twice as strongly as from the alcoholic solution of nitric acid, while a fraction of water in pure alcohol exceeding 10% prevents adsorption. In the mixture of alcohol and nitric acid, the adsorption strength for calcium and strontium increases with the increase of the volume fraction of alcohol with a lower dielectric constant. The rate and strength of adsorption of ions on the exchanger also increase in the series 0.25M HNO 3 in methanol 3 in ethanol 3 in 1-propanol for each individual ion, as well as in the Ca 3 in methanol, 0.25M HNO 3 in ethanol and 0.25M HNO 3 in propanol. Separation is also possible from alcohol mixtures. Strontium separation is most difficult from calcium, while the efficiency of separation increases with a decrease of the polarity of the used alcohol or alcohol mixture. The first group elements of the periodic table are not separated from each other in this way, while the elements of the second group are

  7. The Incredible, Embryological Egg: Calcium and Strontium Isotopes Recapitulate Ontogeny

    Science.gov (United States)

    Gordon, G. W.; Skulan, J. L.

    2011-12-01

    that caused by osteoporosis in humans. For both mass-dependent Ca and Sr isotopes, the isotopic value of the albumen is the highest natural value yet measured. The offset between the δ88/86Sr values of the albumen and shell is 0.45%, less than half that of the δ44/42Ca offset value (1.29%), as predicted by the relative mass differences. However, the yolk is 0.35% heavier than the shell in δ44/42Ca but 0.70% lighter in δ88/86Sr. In addition, the 87Sr/86Sr value of the shell (0.70854 ±0.000012, 2σ) is statistically the same as the albumen (0.70856 ±0.000018), but slightly offset from the yolk (0.70830 ±0.000014). The apparent decoupling of Ca and Sr, and the radiogenic offset between yolk and shell, may reflect differences in the residence time of calcium and strontium in different reproductive organs, as well as the contribution of medullary bone to shell formation. In addition, it may also reflect differential discrimination against Sr versus Ca in oviduct and uterus. Further studies could extend to thinning eggshells in wild avian populations, biochemical mechanisms of bone formation, and the mechanism of strontium ranelate in the treatment of osteoporosis.

  8. Strontium and calcium determination in sea fishes in neighborhood of Angra nuclear power plant

    International Nuclear Information System (INIS)

    Ferreira, L.M.J.

    1985-01-01

    Strontium-90 is an important radionuclide present in the liquid effluents of the Angra Nuclear Power Plant, located in the coastline of Rio de Janeiro State. It has a long effective half-life, easy entry into food chain due to its chemical similarity to calcium and stays for a long time in solution. With the aim of calculating the concentration factor (CF) for 90 Sr and observed ratio (OR) in the most abundant local fish, it was determined the strontium and calcium content in the edible fraction of nine species and in sea water by atomic absorption spectrophotometry. (author)

  9. Strontium and cesium extraction into hydrocarbons using alkyl cobalt dicarbollide and polyethylene glycols

    International Nuclear Information System (INIS)

    Chamberlin, R.M.; Abney, K.D.

    1999-01-01

    The extraction of strontium and cesium ions from high ionic strength acid, base, and salt solutions into an organic extractant consisting of alkyl cobalt dicarbollide and polyethylene glycol (PEG) in diethylbenzene was investigated. Adding hexaethylene glycol or PEG-400 improved the strontium extraction ≥ 100-fold, while cesium extraction was decreased at high PEG concentrations. The extractions are rapid and selective, even in the presence of molar concentrations of sodium ion, suggesting that alkyl cobalt dicarbollide extractants are useful for the treatment of alkaline nuclear wastes. A method for the synthesis of tetra-n-hexyl(cobalt dicarbollide) is described. (author)

  10. Decision document for the final disposition of cesium and strontium capsules

    Energy Technology Data Exchange (ETDEWEB)

    Claghorn, R.D., Fluor Daniel Hanford

    1997-03-01

    This report was prepared to document decisions regarding the disposition of cesium and strontium capsules. A Decision Support Board was established to consider the multiple drivers for decisions regarding disposition of cesium and strontium capsules and make decisions that form the near-term guidance for the project. The decision process included several Decision Board meetings, documented in this report, in which technical and programmatic information was presented by Tank Waste Remediation System (TWRS) technical staff and considered by the Decision Board. The process also included preparation of the decision documentation, which is presented in this report.

  11. Osteoblast Differentiation and Bone Formation Gene Expression in Strontium-inducing Bone Marrow Mesenchymal Stem Cell

    OpenAIRE

    SILA-ASNA, MONNIPHA; BUNYARATVEJ, AHNOND; Maeda, Sakan; Kitaguchi, Hiromichi; BUNYARATAVEJ, NARONG

    2007-01-01

    Osteoblastic differentiation from human mesenchymal stem cell (hMSCs) is animportant step of bone formation. We studied the in vitro induction of hMSCs byusing strontium ranelate, a natural trace amount in water, food and human skeleton.The mRNA synthesis of various osteoblast specific genes was assessed by means ofreverse transcription polymerase chain reaction (RT-PCR). In the hMSCs culture,strontium ranelate could enhance the induction of hMSCs to differentiate intoosteoblasts. Cbfa1 gene ...

  12. Water hyacinths and alligator weeds for removal of silver, cobalt, and strontium from polluted waters

    Science.gov (United States)

    Wolverton, B. C.; Mcdonald, R. C.

    1975-01-01

    Water hyacinths and alligator weeds demonstrated the ability to rapidly remove heavy metals from an aqueous system by root absorption and concentration. Water hyacinths demonstrated the ability to remove 0.439 mg of silver, 0.568 mg of cobalt, and 0.544 mg of strontium in an ionized form per gram of dry plant material in a 24-hour period. Alligator weeds removed a maximum of 0.439 mg of silver, 0.130 mg of cobalt, and 0.161 mg of strontium per gram of dry plant material per day.

  13. Investigations into the transfer of cesium 137 and strontium 90 in selected exposure pathways

    International Nuclear Information System (INIS)

    Roemmelt, R.; Hiersche, L.; Wirth, E.

    1991-12-01

    This research project investigates the behaviour of radiocesium and strontium 90 in natural conifer forest sites and derives corresponding transfer factors for radioecological calculations. As a point of particular interest the question was investigated in how far the requirements of the different mushroom species and the properties of the forest soil bear on the dynamics and transfer rate of radiocesium and strontium 90. To complement the investigations, autotrophic plants were included. The results of these studies are compared with the behaviour of the same radionuclides on farmland. The differences are discussed. (orig./HP) [de

  14. Drug rash with eosinophilia and systemic symptoms (DRESS) in patients receiving strontium ranelate.

    Science.gov (United States)

    Cacoub, P; Descamps, V; Meyer, O; Speirs, C; Belissa-Mathiot, P; Musette, P

    2013-05-01

    We have reviewed 47 drug rash with eosinophilia and systemic symptoms (DRESS) cases associated to strontium ranelate reported up to March 2011 to the Marketing Holder. The main signs were skin rash, fever, face oedema hypereosinophilia and liver involvement. For ten patients, persistence of DRESS symptoms was reported at the latest news obtained, and DRESS was identified as the direct cause of death in one case. The maximum incidence of DRESS associated with strontium ranelate was 1/24,112 [95 % CI (1/14,859; 1/42,194)] newly treated patients in France. Because DRESS is a severe drug reaction, the occurrence of a rash in a patient treated with strontium ranelate should lead to prompt and permanent treatment discontinuation. This study aims to describe cases of DRESS reported to the Marketing Authorisation Holder worldwide for patients receiving strontium ranelate by practitioner or by regulatory authorities. Spontaneously reported hypersensitivity events from the strontium ranelate pharmacovigilance database since marketing authorisation (2004) to March 2011 were reviewed by an expert committee. Cases of DRESS were classified as established, probable, possible or no DRESS according to expert judgement. National incidences of DRESS were estimated in relation to the number of newly treated patients. Up to March 2011, 325 cases of strontium ranelate-induced hypersensitivity events were assessed from which 47 DRESS cases were confirmed. Mean age was 68.7 years and besides skin rash, the main signs and symptoms were hypereosinophilia, liver involvement, fever and face oedema. Median time to skin reaction was 33.5 days after treatment start. Most patients (62 %) recovered at the time of reporting or were recovering. For ten patients, persistence of DRESS symptoms was reported at the latest news obtained. Relapses were observed in a single case. The mortality rate was 8.5 %. The maximum incidence of DRESS associated with strontium ranelate was 1/24,112 [95 % CI (1

  15. Analyses and quantitative determination of the strontium radioisotopes 89 and 90 in milk powder

    International Nuclear Information System (INIS)

    Jeanmaire, L.; Michon, G.

    1959-01-01

    The authors describe a procedure for the determination of the strontium radioisotopes 89 and 90. The concentration of strontium is made possible by the insolubility of its nitrate salt in strong nitric acid which allows the removal of greatest part of calcium. The purification is performed on a cation exchange column. The amount of radioisotope 90 is determined by means of its daughter product yttrium 90 necessary calibrations and computations are treated in special paragraphs. With regard to the reproducibility of the measurements, the fluctuations are less than 20 per cent. This seems satisfaction for such a technique which have great sensibility while being long and necessitative great carefulness. (author) [fr

  16. Cesium and Strontium Specific Exchangers for Nuclear Waste Effluent Remediation

    International Nuclear Information System (INIS)

    Clearfield, A.; Bortun, A. I.; Bortun, L. A.; Bhlume, E. A.; Sylvester, P.; Graziano, G. M.

    2000-01-01

    During the past 50 years, nuclear defense activities have produced large quantities of nuclear waste that now require safe and permanent disposal. The general procedure to be implemented involves the removal of cesium and strontium from the waste solutions for disposal in permanently vitrified media. This requires highly selective sorbents or ion exchangers. Further, at the high radiation doses present in the solution, organic exchangers or sequestrants are likely to decompose over time. Inorganic ion exchangers are resistant to radiation damage and can exhibit remarkably high selectivities. We have synthesized three families of tunnel-type ion exchangers. The crystal structures of these compounds as well as their protonated phases, coupled with ion exchange titrations, were determined and this information was used to develop an understanding of their ion exchange behavior. The ion exchange selectivities of these phases could be regulated by isomorphous replacement of the framework metals by larger or smaller radius metals. In the realm of layered compounds, we prepared alumina, silica, and zirconia pillared clays and sodium micas. The pillared clays yielded very high Kd values for Cs+ and were very effective in removing Cs+ from groundwaters. The sodium micas also had a high affinity for Cs+ but an even greater attraction for S42+. They also possess the property of trapping these ions permanently as the layers slowly decrease their interlayer distance as loading occurs. Sodium nonatitanate exhibited extremely high Kd values for Sr2+ in alkaline tank wastes and should be considered for removal of Sr2+ in such cases. For tank wastes containing complexing agents, we have found that adding Ca2+ to the solution releases the complexed Sr2+ which may then be removed with the CST exchanger

  17. Nd–Co substituted strontium hexaferrite powders with enhanced coercivity

    Energy Technology Data Exchange (ETDEWEB)

    Herme, C.A. [Facultad de Ingeniería, Universidad de Buenos Aires, LAFMACEL-INTECIN, Paseo Colón 850, 1063 Buenos Aires (Argentina); Bercoff, P.G., E-mail: bercoff@famaf.unc.edu.ar [Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba, IFEG, CONICET, Ciudad Universitaria, 5000 Córdoba (Argentina); Jacobo, S.E. [Facultad de Ingeniería, Universidad de Buenos Aires, LAFMACEL-INTECIN, Paseo Colón 850, 1063 Buenos Aires (Argentina)

    2012-11-15

    Graphical abstract: Display Omitted Highlights: ► Sr{sub 1−x}Nd{sub x}Fe{sub 11−x}Co{sub x}O{sub 19} was prepared by sol–gel auto-combustion method with 0 ≤ x ≤ 0.4. ► Coercivity increases 11% with 0.2 Nd–Co substitution, reaching a value of 68.9 A/m. ► The appearance of two magnetic orderings is noticed in susceptibility measurements. ► This is supported by Curie temperature and susceptibility data. -- Abstract: In this work we report the synthesis of Nd–Co substituted strontium hexaferrites of composition Sr{sub 1−x}Nd{sub x}Fe{sub 11−x}Co{sub x}O{sub 19} by the sol–gel auto-combustion method with further heat treatment. The analysis of the X-ray diffraction spectra shows the M-type hexagonal structure in samples treated at 1100 °C for 2 h. Coercivity increases 11% with 0.2 Nd–Co substitution, reaching a value of 68.9 A/m (5480 Oe) while saturation magnetization is reduced 6% to 91 A m{sup 2}/kg (91 emu/g). The behavior of magnetic susceptibility with an applied field shows two different maxima which are assigned to different magnetic orderings. This assumption is supported by the appearance of two experimental values of Curie temperatures (T{sub C}) for all the prepared samples. Magnetic susceptibility χ and T{sub C} measurements suggest an uneven distribution of the iron vacancies.

  18. Strontium Incorporation into Calcite Generated by Bacterial Ureolysis

    International Nuclear Information System (INIS)

    Yoshiko Fujita; George D. Redden; Jani C. Ingram; Marnie M. Cortez; Robert W. Smith

    2004-01-01

    Strontium incorporation into calcite generated by bacterial ureolysis was investigated as part of an assessment of a proposed remediation approach for 90Sr contamination in groundwater. Urea hydrolysis produces ammonium and carbonate and elevates pH, resulting in the promotion of calcium carbonate precipitation. Urea hydrolysis by the bacterium Bacillus pasteurii in a medium designed to mimic the chemistry of the Snake River Plain Aquifer in Idaho resulted in a pH rise from 7.5 to 9.1. Measured average distribution coefficients (DEX) for Sr in the calcite produced by ureolysis (0.5) were up to an order of magnitude higher than values reported in the literature for natural and synthetic calcites (0.02-0.4). They were also higher than values for calcite produced abiotically by ammonium carbonate addition (0.3). The precipitation of calcite in these experiments was verified by X-ray diffraction. Time-of-flight secondary ion mass spectrometry (ToF SIMS) depth profiling (up to 350 nm) suggested that the Sr was not merely sorbed on the surface, but was present at depth within the particles. X-ray absorption near edge spectra showed that Sr was present in the calcite samples as a solid solution. The extent of Sr incorporation appeared to be driven primarily by the overall rate of calcite precipitation, where faster precipitation was associated with greater Sr uptake into the solid. The presence of bacterial surfaces as potential nucleation sites in the ammonium carbonate precipitation treatment did not enhance overall precipitation or the Sr distribution coefficient. Because bacterial ureolysis can generate high rates of calcite precipitation, the application of this approach is promising for remediation of 90Sr contamination in environments where calcite is stable over the long term

  19. Strontium-90 content of human bone collected in 1967; Teneur en strontium 90 d'os humains preleves en 1967

    Energy Technology Data Exchange (ETDEWEB)

    Jeanmaire, L.; Patti, F. [Commissariat a l' Energie Atomique, Fontenay-Aux-Roses (France). Centre d' Etudes Nucleaires

    1969-07-01

    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) [French] Ce rapport fait suite au rapport CEA-R-3381 et indique les teneurs en strontium 90 d'os humains preleves au cours de l'annee 1967 dans la region parisienne. L'evolution generale des resultats est sensiblement la meme qu'au cours de l'annee 1966; nous assistons a une baisse de la contamination chez les enfants jusqu'a 5 ans. Au-dela de cet ge, les valeurs sont les memes, ou en legere augmentation. (auteurs)

  20. Fitness Doping and Body Management

    DEFF Research Database (Denmark)

    Thualagant, Nicole

    This PhD thesis examines in a first paper the conceptualization of fitness doping and its current limitations. Based on a review of studies on bodywork and fitness doping it is emphasised that the definition of doping does not provide insights into bodywork of both men and women. Moreover......, it is argued that the social and a cultural context are missing in the many epidemiological studies on the prevalence of doping. The second paper explores the difficulties of implementing an anti-doping policy, which was originally formulated in an elite sport context, in a fitness context and more...... specifically in a sport-for-all context. It is questioned whether the anti-doping policy contradicts some of the national sport-for-all organisation, DGI’s values of fostering fellowship, challenge and health. Last but not least, this thesis examines in a third paper the bodywork of the users’ of the club...