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Sample records for 7-12ign co-cu 13ign

  1. Extraordinary diffusion in Co/Cu grain boundaries

    Usually, Cu atoms hardly diffuse in Co because of the very low solid solubility limit. However, this letter shows by transmission electron microscopy that extraordinary diffusion of Cu in the Co phase occurred in Co/Cu bicrystal fabricated by diffusion joining and that many dislocations were found in the Co phase. First-principles calculations suggested that the extraordinary diffusion of Cu in Co is related to the movement of dislocations which Cu atoms adhere to

  2. The measurement of total mass attenuation coefficients of CoCuNi alloys

    The total mass attenuation coefficients for Co, Cu, Ni elements and CoCu, CoCuNi alloys were measured at different energies with 11.88, 13.93, 17.59, 21.09 and 26.00 keV emitted an 241Am point source using transmission arrangement. The gamma rays were counted by a Si(Li) detector with a resolution of 160 eV at 5.9 keV. Also the mass attenuation coefficients of each alloy (CoCu, CoCuNi) were estimated using mixture rule. The measured values were compared with estimated values for alloys

  3. Microstructural Characterisation of Giant Magnetoresistive Co/Cu Multilayers

    Antiferromagnetically-coupled Co/Cu multilayers prepared by magnetron sputtering exhibit pronounced giant magnetoresistance (GMR) effect at room temperature. Using both diffraction and imaging techniques, we studied the in-plane and out-of-plane crystallographic and layering microstructural features of these multilayers. Dominant characteristic features associated with the multilayers, such as lateral and vertical columnar grain orientations as well as layer undulations and regularity, were identified. By deliberately introducing microstructural changes to the materials system using buffer layer and heat treatment, detailed microstructural analysis have provided an insight into the dependence of GMR on microstructures of the multilayers.

  4. Microstructural Characterisation of Giant Magnetoresistive Co/Cu Multilayers

    Antiferromagnetically-coupled Co/Cu multilayers prepared by magnetron sputtering exhibit pronounced giant magnetoresistance (GMR) effect at room temperature. Using both diffraction and imaging techniques, we studied the in-plane and out-of-plane crystallographic and layering microstructural features of these multilayers. Dominant characteristic features associated with the multilayers, such as the lateral and vertical columnar grain orientations as well as layer undulations and regularity, were identified. By deliberately introducing microstructural changes to the materials system using buffer layer and heat treatment, detailed microstructural analysis had provided an insight into the dependence of GMR on the microstructures of the multilayers.

  5. Atomic simulation of grain boundary sliding in Co/Cu two-phase bicrystals

    Molecular dynamic simulations of grain boundary sliding were performed on Cu/Cu one-phase bicrystal and Co/Cu two-phase bicrystal models. The grain boundary sliding and migration behaviors of the Co/Cu bicrystals were different from those of the Cu/Cu bicrystals, and the Co/Cu sliding behavior was less related to the free volume, than that of Cu/Cu. In the Co/Cu(2 2 1) grain boundary model, the pore structure units were formed on the Cu side very near the Co/Cu interface, not just at the interface. The onset of grain boundary sliding in the Co/Cu bicrystals was due to the uncorrelated atomic shuffling induced by the pore structure units.

  6. CO-induced inversion of the layer sequence of a model CoCu catalyst

    Collinge, Greg; Xiang, Yizhi; Barbosa, Roland; McEwen, Jean-Sabin; Kruse, Norbert

    2016-06-01

    Experimental X-ray photoelectron spectroscopy (XPS) and theoretical density functional theory (DFT) calculations reveal the electronic and structural properties of CoCu catalysts before and after CO adsorption. DFT calculations show that, prior to CO adsorption, CoCu has a high tendency to self-assemble into a Co@Cu core-shell structure, which is in accordance with previous atom probe tomography (APT) results for CoCu-based systems and the known mutually low miscibility of Co and Cu. We demonstrate that Co and Cu are electronically immiscible using a density of states (DOS) analysis wherein neither metal's electronic structure is greatly perturbed by the other in "mixed" CoCu. However, CO adsorption on Co is in fact weakened in CoCu compared to CO adsorption on pure Co despite being electronically unchanged in the alloy. Differential charge density analysis suggests that this is likely due to a lower electron density made available to Co by Cu. CO adsorption at coverages up to 1.00 ML are then investigated on a Cu/Co(0001) model slab to demonstrate CO-induced segregation effects in CoCu. Accordingly, a large driving force for a Co surface enrichment is found. At high coverages, CO can completely invert the layer sequence of Co and Cu. This result is echoed by XPS evidence, which shows that the surface Co/Cu ratio of CoCu is much larger in the presence of CO than in H2.

  7. Morphology transition in a heteroepitaxial system: Co/Cu(111)

    WU Fengmin; LU Hangjun; FANG Yunzhang

    2006-01-01

    The initial stages of multilayer Co thin film grown on Cu(111) surface were simulated by means of kinetic Monte Carlo (KMC) method, where the realistic growth model and physical parameters were presented. The effects of edge diffusion along the islands and mass transport between interlayers were included in the simulationmodel. Emphasis was placed on revealing the transition of growth morphology in heteroepitaxial Co/Cu(111) system with the changing of surface temperature. The simulation results show that the dendritic islands form at low temperature ( T=210 K), while compact islands grow at room temperature (RT). The Volmer-Webber (three-dimensional, 3D) growth mode is presented due to the relative higher Ehrlich-Schwoebel (ES) barrier. Our simulation results are in good agreement with the real scanning tunneling microscopy (STM) experiments.

  8. Structural and magnetoresistive properties of Co/Cu multilayers

    Co/Cu multilayers (ML) were thermally evaporated at very low deposition rates on Si substrates covered with buffer layers of different metals (Ag, Cu, In, Pb, Bi). Structural characterisation of samples was performed by X-ray reflectometry (XRR), X-ray diffraction (XRD) and atomic force microscopy (AFM). Magnetoresistance measurements were carried out at room temperature using a standard four-probe DC method with current in the plane of the sample. It seems that a choice of buffer type has no significant effect on the magnitude of GMR. Since the thickness of single layers is of similar magnitude as the interfacial roughness in samples we suggest that the observed small value of GMR effect can be attributed rather to the interruption of film continuity and creation of magnetic bridges between Co layers, resulting in direct ferromagnetic coupling of magnetic films

  9. Spin-valve magnetoresistance in Co/Si/(Co/Cu/Co) multilayers

    SHEN Hong-lie; LI Guan-xiong

    2005-01-01

    A series of Co/Si/(Co/Cu/Co) multilayers and Co/Si/Co sandwiches were prepared by high vacuum electron-beam evaporation. It was found that a Si spacer (≥0.9nm) could greatly decrease the interlayer coupling in Co/Si/Co sandwiches and there was no magnetoresistance(MR) or spin-valve MR in them due to the high resistivity of Si spacer. While in Co/Si/(Co/Cu/Co) multilayers, we observed a spin-valve MR of about 0.5% through a nominal 2.7nm Si spacer at room temperature. The spin-valve MR in Co/Si/(Co/Cu/Co) multilayers was attributed to the enhanced spin polarization of conduction electrons caused by the top Co/Cu/Co sandwich with GMR mechanism and high spin-dependent scattering at Co/Cu interface.

  10. Structural evolution of Co/Cu nanostructures under 1 MeV ion-beam irradiation

    Co/Cu multilayers with composition wavelength ranging from 2 to 10 nm have been deposited and irradiated at various doses from 1x1014 to 3x1016 ions/cm2 using 1 MeV Si+ ions. The ion-beam-induced variation in structural properties such as interfacial mixing, interface roughness, crystallographic texture, and grain size, are characterized by a variety of x-ray scattering techniques. Irradiating Co/Cu multilayers generate metastable Co-Cu alloys whose electrical and magnetic properties have been found to be very similar to the Co-Cu alloys fabricated by other nonequilibrium methods. Fitting to the low-angle x-ray reflectivity spectra using a standard optical model yields a mixing efficiency comparable to the prediction of a ballistic ion-beam mixing model, and interfacial mixing widths consistent with the values estimated from saturation magnetization measurements

  11. Direct Measurement of the Metastable Liquid Miscibility Gap in Fe-Co-Cu Ternary Alloy System

    CAO Chong-De; Georg P.G(O)RLER

    2005-01-01

    @@ The metastable liquid-liquid phase separation in undercooled Fe-Co-Cu ternary alloy melts (XCu = 0.10-0.84;XCo:XFe = 1:3,1:1 and 3:1) is investigated by differential thermal analysis in combination with glass fluxing technique. In almost every case, the undercooling of the homogeneous alloy melt was sufficient to reach the boundary line of the submerged miscibility gap. The differential-thermal-analysis signals indicate that this separation into a (Fe, Co)-rich liquid phase L1 and a Cu-rich liquid L2 is exothermic and proceeds until the rapid solidification of the L1 phase occurs. At a given Cu concentration and with the increase of Co content, the phase separation temperatures decrease monotonically between the corresponding values of the boundary systems Fe-Cu and Co-Cu. The boundary lines of the miscibility gap, which are determined for the three quasi-binary cross-sections of the (Fe, Co)-Cu alloy system, show remarkably flat domes. The occurrence of the liquid phase separation shows an evident influence on the subsequent γ-Fe(Co, Cu)→α-Fe(Co, Cu) solid phase transformation.

  12. Thermal stability of Py/Cu and Co/Cu giant magnetoresistance (GMR) multilayer systems

    Vovk, V.

    2008-01-01

    NiFe/Cu und Co/Cu Multilagen werden in Bezug auf die thermische Stabilität des Riesen-Magnetowiderstand-Effekts untersucht. Die unterschiedlichen thermodynamischen Eigenschaften der betrachteten Systeme führen zu jeweils anderen Mechanismen von GMR-Effekt Abnahme. Nach den Ergebnissen der Nanoanalyse tritt der GMR-Zusammenbruch in Py/Cu-Systemen aufgrund der Verbreiterung der Grenzfläche nach der Wärmebehandlung über 200°C auf. Im Gegensatz dazu bleiben Co/Cu Mehrfachschichtsysteme wegen der ...

  13. The effect of substrate on magnetic properties of Co/Cu multilayer nanowire arrays

    Ren Yong; Wang Jian-Bo; Liu Qing-Fang; Han Xiang-Hua; Xue De-Sheng

    2009-01-01

    Ordered Co/Cu multilayer nanowire arrays have been fabricated into anodic aluminium oxide templates with Ag and Cu substrate by direct current electrodeposition.This paper studies the morphology,structure and magnetic properties by transmission electron microscopy,selective area electron diffraction,x-ray diffraction,and vibrating sample magnetometer.X-ray diffraction patterns reveal that both as-deposited nanowire arrays films exhibit face-centred cubic structure.Magnetic measurements indicate that the easy magnetization direction of Co/Cu multilayer nanowire arrays films on Ag substrate is perpendicular to the long axis of nanowire,whereas the easy magnetization direction of the sample with Cu substrate is parallel to the long axis of nanowire.The change of easy magnetization direction attributed to different substrates,and the magnetic properties of the nanowire arrays are discussed.

  14. Influence of Si buffer layer on the giant magnetoresistance effect in Co/Cu/Co sandwiches

    李冠雄; 沈鸿烈; 沈勤我; 李铁; 邹世昌

    2000-01-01

    The Co/Cu/Co sandwiches with a semiconductor Si buffer layer were prepared by high vacuum electron-beam evaporation. The influence of the Si buffer layer with different thickness on the giant magnetoresistance (GMR) effect in the Co/Cu/Co sandwiches was investigated. It was found that the GMR showed an obvious anisotropy when the thickness of Si buffer layer was larger than or equal to 0.9 nm, and that the GMR was basically isotropic with an Si buffer layer thinner than 0.9 nm. The anisotropic behavior of GMR can be ascribed to the in-plane magnetic anisotropy in the sandwiches. Due to the interdiffusion at the Si buffer/Co interface, a Co2Si interface layer with a good (301) texture formed and induced the in-plane magnetic anisotropy in the sandwiches. The dependence of the crystalline texture of the sandwiches on the thickness of Si buffer layer was also studied.

  15. Néel coupling in Co/Cu/Co stripes with unidirectional interface roughness

    We investigate the influence of interlayer Néel coupling on the magnetization reversal processes in epitaxial Co(5 nm)/Cu(5 nm)/Co(5 nm) stripes by experimental methods and computer modeling. The stripes with a width of 900 and 1800 nm were formed on a step-bunched Si(111) substrate by molecular beam epitaxy and focused ion beam etching. Uniaxial magnetic anisotropy with the easy axis of the magnetization along the steps is induced in the stripes by the steps of the Si(111) substrate. The stepped structure of the layers in the multilayered stripes reproduces the morphology of the Si(111) substrate. Néel coupling between the Co layers is realized due to the unidirectional roughness at the Co/Cu interfaces caused by the steps of the substrate. Interlayer Néel coupling at the interfaces overcomes antiparallel magnetostatic interaction realized through the sides of the Co layers in the trilayered stripes. We used a modified Néel model in the simulation of the magnetization reversal in the multilayered system with unidirectional interface roughness. The surface energy of Néel coupling was spatially varied against the direction of the magnetization relative to the step edge. The results of micromagnetic simulations of the Co/Cu/Co stripes with spatially non-uniform and averaged surface energies of interlayer Néel coupling are compared and discussed. - Highlights: • We investigated Co/Cu/Co stripes with unidirectional roughness at the interfaces. • Results obtained by MOKE and MFM are compared to micromagnetic simulations. • A modified Néel model was used in the micromagnetic simulation of the Co/Cu/Co system. • The surface energy of Néel coupling depends on the direction of the magnetization

  16. Domain wall pinning in FeCoCu bamboo-like nanowires

    Berganza, Eider; Bran, Cristina; Vazquez, Manuel; Asenjo, Agustina

    2015-01-01

    The pinning effect of the periodic diameter modulations on the domain wall propagation in FeCoCu individual nanowires is determined by Magnetic Force Microscopy, MFM. A main bistable magnetic configuration is firstly concluded from MFM images characterized by the spin reversal between two nearly single domain states with opposite axial magnetization. Complementary micromagnetic simulations confirm a vortex mediated magnetization reversal process. A refined MFM imaging procedure under variable...

  17. Fabrication and evaluation of atmospheric plasma spraying WC-Co-Cu-MoS2 composite coatings

    Research highlights: → Protective WC-Co-based coatings containing solid lubricant Cu and MoS2 used in wear applications were investigated in this study. → It was found that the MoS2 composition in the feed powder was kept in WC-Co-Cu-MoS2 coatings, and the decomposition and decarburization of WC in APS process were improved. → Combining the wear resistance of WC with the lubricating properties of Cu and MoS2 has an extremely beneficial effect on improving the tribological performance of the resulting coating. - Abstract: Protective WC-Co-based coatings containing solid lubricant Cu and MoS2 used in wear applications were investigated in this study. These coatings were deposited on mild steel substrates by atmospheric plasma spraying (APS). The feedstock powders were prepared by mechanically mixing the solid lubricant powders and WC-Co powder, followed by sintering and crushing the mixtures to avoid different particle flighting trajectories at plasma. The tribological properties of the coatings against stainless steel balls were examined by ball-on-disk (BOD) tribometer under normal atmospheric condition. The microstructure of the coatings was studied by optical microscope, scanning electron microscope and X-ray diffraction. It was found that the MoS2 composition in the feed powder was kept in WC-Co-Cu-MoS2 coatings, and the decomposition and decarburization of WC in APS process were improved, which were attributed to the protection of Cu around them. The friction and wear behaviors of all the WC-Co-Cu-MoS2 coatings were superior to that of WC-Co coating. Such behavior was associated to different wear mechanisms operating for WC-Co coating and the WC-Co-Cu-MoS2 coatings.

  18. The geochemical profile of Mn, Co, Cu and Fe in Kerteh Mangrove Forest, Terengganu

    The geochemical profile of Kerteh mangrove sediments was analyzed for the vertical and horizontal distribution. The 100 cm core sediment sample and 15 surface sediments samples were taken from the field. The geochemical elements of Mn, Co, Cu and Fe of the sediments were analyzed. Geochemical proxy of Mn, Co, Cu and Fe were analyzed by using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The mean concentrations of Mn, Co, Cu and Fe for the vertical distribution were 210.18 μg/ g, 15.55 μg/ g, 43.65 μg/ g and 1.88 μg/ g respectively. on the other hand, the mean concentrations of the geochemical elements for horizontal distributions were 230.50 μg/ g for Mn, 17.57 μg/ g for Co, 43.381 μg/ g for Cu and 2.93 μg/ g for Fe. Enrichment factor and normalization was used to point out the level of pollution. The EF and the normalization indicated that all the geochemical elements were from the natural sources. (author)

  19. Thermal stability of Py/Cu and Co/Cu giant magnetoresistance (GMR) multilayer systems

    Vovk, Vitaliy

    2007-07-01

    NiFe/Cu and Co/Cu multilayer systems have been studied regarding the mechanisms of thermal degradation of the giant magnetoresistance effect (GMR). The different thermodynamics of the studied systems results in different mechanisms of the GMR degradation as shown by highest resolution nanoanalysis using the three dimensional wide angle tomographic atom probe. According to the TAP analysis, GMR deterioration in Py/Cu system occurs due to the broadening of the layer interfaces observed at 250 C. In contrast, due to the strong demixing tendency, Co/Cu multilayers remain stable up to 450 C. At higher temperatures ferromagnetic bridging of the neighboring Co layers takes place leading to the GMR breakdown. In both Py/Cu and Co/Cu systems recrystallization is induced at 350-450 C, which is accompanied by a change in the crystallographic orientation from <111> to <100> wire texture. The reaction may be utilized to produce GMR sensor layers of remarkable thermal stability. Although the systems of interest are equivalent in respect of the observed phenomenon, the Ni{sub x}Fe{sub 1-x}/Cu system is chosen for a detailed analysis because it allows a precise control of the lattice constant by varying the Fe content in the Ni{sub x}Fe{sub 1-x} layer. It is shown that the crystallographic reorientation is triggered by the minimization of lattice mismatch elastic energy. Moreover, the counteraction between the elastic and interfacial energy minimizations exerts a critical influence on the recrystallization probability. (orig.)

  20. Effect of field deposition and pore size on Co/Cu barcode nanowires by electrodeposition

    We have studied the effect of an external magnetic field applied during electrodeposition of Co/Cu barcode nanowires in anodic aluminum oxide nanotemplates. The magnetic properties of the barcode nanowires were greatly enhanced for 50 nm pore diameter regardless of segment aspect ratio, but field deposition has little effect on the 200 nm nanowires. The magnetic improvement is correlated with a structural change, attributed to field modification of the growth habit of the barcode nanowires. A mechanism of growth subject to geometric confinement is proposed

  1. Effect of field deposition and pore size on Co/Cu barcode nanowires by electrodeposition

    Cho, Ji Ung [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Wu, J.-H. [Research Institute of Engineering and Technology, Korea University, Seoul 136-713 (Korea, Republic of)]. E-mail: feitianshenhu@yahoo.com; Min, Ji Hyun [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Lee, Ju Hun [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Liu, H.-L. [Institute for Nano Science, Korea University, Seoul 136-713 (Korea, Republic of); Kim, Young Keun [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of)]. E-mail: ykim97@korea.ac.kr

    2007-03-15

    We have studied the effect of an external magnetic field applied during electrodeposition of Co/Cu barcode nanowires in anodic aluminum oxide nanotemplates. The magnetic properties of the barcode nanowires were greatly enhanced for 50 nm pore diameter regardless of segment aspect ratio, but field deposition has little effect on the 200 nm nanowires. The magnetic improvement is correlated with a structural change, attributed to field modification of the growth habit of the barcode nanowires. A mechanism of growth subject to geometric confinement is proposed.

  2. Determination of the electronic density of states near buried interfaces: Application to Co/Cu multilayers

    Nilsson, A.; Sthör, J.; Wiell, T.; Aldén, M.; Bennich, P.; Wassdahl, N.; Samant, M.G.; Parkin, S.S.P.; Mårtensson, N.; Nordgren, J.; Johansson, B.; Skriver, Hans Lomholt

    1996-01-01

    High-resolution L(3) x-ray absorption and emission spectra of Co and Cu in Co/Cu multilayers are shown to provide unique information on the occupied and unoccupied density of d states near buried interfaces. The d bands of both Co and Cu interfacial layers are shown to be considerably narrowed re...... relative to the bulk metals, and for Cu interface layers the d density of states is found to be enhanced near the Fermi level. The experimental results are confirmed by self-consistent electronic structure calculations....

  3. Effect of biquadratic coupling on current induced magnetization switching in Co/Cu/Ni-Fe nanopillar

    Aravinthan, D.; Sabareesan, P.; Daniel, M.

    2016-05-01

    The effect of biquadratic coupling on spin current induced magnetization switching in a Co/Cu/Ni-Fe nanopillar device is investigated by solving the free layer magnetization switching dynamics governed by the Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation. The LLGS equation is numerically solved by using Runge-Kutta fourth order procedure for an applied current density of 5 × 1012 Am-2. Presence of biquadratic coupling in the ferromagnetic layers reduces the magnetization switching time of the nanopillar device from 61 ps to 49 ps.

  4. Diffusion during growth and annealing of Co/Cu (111) films

    Su Run; Qian Hai Jie; Kurash

    2002-01-01

    Electronic structure of MBE-grown Co/Cu (111) films was studied by synchrotron radiation angular-resolved photoemission spectra and auger electron spectra during the process of growth and annealing. The experiment reveals that: the energy shift of s-d sub z sup 2 -hybridized band of copper increases with thickening of the coverage of cobalt, which proves that atomic intermixing occurs at the interface, and there is mainly surface diffusion, not bulk interdiffusion during annealing. The authors attribute the diffusion in the two different processes to one driving force, i.e. the surface free energy of cobalt is remarkably larger than that of copper

  5. Importance of the interband contribution to the magneto-refractive effect in Co/Cu multilayers

    The optical properties of Co/Cu multilayers are investigated theoretically using a multiband tight-binding model and the results are compared to experimental data on the magneto-refractive effect (MRE). The optical conductivity of both parallel and antiparallel configurations of Co/Cu multilayers is calculated using the Kubo-Greenwood formula. The Kramers-Kronig relations are utilized to obtain the imaginary part of the conductivity and the real part of the dielectric function. The conductivity is decomposed into the intraband and interband terms, so that their different contributions to the MRE may be analysed. In particular, we find that the competition between the intraband and interband contributions leads to a change of sign in the MRE as a function of frequency, a feature which is also observed experimentally in the infrared region. This is in contrast to the predictions of the Drude model, where only the intraband part of the conductivity is considered and the MRE curve always takes the same sign. Therefore, it is vital to include the interband contribution for a full spectral study of the origin of the infrared MRE data. (letter to the editor)

  6. Wide frequency band ESR study of Co - Cu multilayers with variable thickness of Co layers

    Layered magnetic/nonmagnetic conductors (Co/Cu, Fe/Ni/Cu, Fe/Cr, others.) excite now certain interest of researches because they show remarkable vary of resistivity while applying the static magnetic field of quite small value (Giant Magnetic Resistance - GMR effect). As well the giant magneto impedance phenomenon (GMI) is revealed for alternative current. Study of nature of GMI phenomenon promising to give a certain profit for high-frequency physics and technology, especially millimeter wavelength band on the reason of very small switching time restricted mainly the spin-spin relaxation time of the multilayers material (10''-''9s - 10''-''1''3s). Therefore the study of magnetic properties of such structures by high-frequency techniques and in the frequency band of their presumptive application is of large significance. In this report a results of study some key features of Co/Cu multilayered structure, by the Electron Spin Resonance (ESR) technique for the frequency range from 9.5 to 37 GHz for variable thickness of magnetic layers are under discussion

  7. Assessing Cd, Co, Cu, Ni, and Pb Sorption on montmorillonite using surface complexation models

    Akafia, Martin M.; Reich, Thomas J. [Department of Geosciences, Western Michigan University, Kalamazoo, MI 49008 (United States); Koretsky, Carla M., E-mail: carla.koretsky@wmich.edu [Department of Geosciences, Western Michigan University, Kalamazoo, MI 49008 (United States)

    2011-06-15

    Highlights: > Cd, Co, Cu, Ni, and Pb sorption on montmorillonite is measured at 6 distinct conditions. > The data are used to develop a diffuse layer model with variable charge and fixed charge sites. > The DLM lacked the robustness to accurately predict adsorption at all conditions. - Abstract: Cadmium, Co, Cu, Ni and Pb adsorption is measured on montmorillonite as a function of pH (3-11), ionic strength (0.001-0.1 M NaNO{sub 3}), and sorbate concentration (0.1-10 {mu}M metal on 0.5 g/L solid). Sorption of all metals shows strong dependence on ionic strength and sorbate concentration, as well as a break in the slope of the edge, indicative of a 2-site interaction with montmorillonite. The resulting adsorption edges are used to parameterize diffuse layer surface complexation models (DLMs) for each metal. A 2-site DLM with a bidentate variable charge surface hydroxyl site and a bidentate permanent charge exchange site produced good fits for the individual experiments, but lacked the robustness to accurately predict adsorption across the entire experimental range. Other models, such as CCM, TLM, or CD-MUSIC may be required for more accurate predictions across broad ranges of solution conditions.

  8. Co-Cu Nanoparticles: Synthesis by Galvanic Replacement and Phase Rearrangement during Catalytic Activation.

    Nafria, Raquel; Genç, Aziz; Ibáñez, Maria; Arbiol, Jordi; Ramírez de la Piscina, Pilar; Homs, Narcís; Cabot, Andreu

    2016-03-01

    The control of the phase distribution in multicomponent nanomaterials is critical to optimize their catalytic performance. In this direction, while impressive advances have been achieved in the past decade in the synthesis of multicomponent nanoparticles and nanocomposites, element rearrangement during catalyst activation has been frequently overseen. Here, we present a facile galvanic replacement-based procedure to synthesize Co@Cu nanoparticles with narrow size and composition distributions. We further characterize their phase arrangement before and after catalytic activation. When oxidized at 350 °C in air to remove organics, Co@Cu core-shell nanostructures oxidize to polycrystalline CuO-Co3O4 nanoparticles with randomly distributed CuO and Co3O4 crystallites. During a posterior reduction treatment in H2 atmosphere, Cu precipitates in a metallic core and Co migrates to the nanoparticle surface to form Cu@Co core-shell nanostructures. The catalytic behavior of such Cu@Co nanoparticles supported on mesoporous silica was further analyzed toward CO2 hydrogenation in real working conditions. PMID:26878153

  9. Microstructure and the properties of FeCoCuNiSnx high entropy alloys

    Highlights: ► Based on a new alloying design idea, new FeCoCuNiSnx alloys are prepared. ► The crystal structure of alloys is a single FCC solution when Sn content is small. ► The elongation strain and tensile strength of the alloy reach 19.8% and 633 MPa. - Abstract: FeCoCuNiSnx high-entropy alloys (x denotes the adding the elements amount in atomic percentage) are prepared by an arc furnace. Their microstructure and mechanical properties are investigated. The results show that the alloys have a single FCC solution when Sn content is small, the microstructure of the alloys with increasing Sn content is FCC solution and Cu81Sn22 intermetallic compounds. The alloys possess the high strength and the plasticity. When Sn content is between 0.05 and 0.07, the maximum elongation strain and the maximum tensile strength can reach 19.8% and 633 MPa, respectively. The adding of Sn leads to the increase of tensile strength.

  10. Magnetic Configurations in Co/Cu Multilayered Nanowires: Evidence of Structural and Magnetic Interplay.

    Reyes, D; Biziere, N; Warot-Fonrose, B; Wade, T; Gatel, C

    2016-02-10

    Off-axis electron holography experiments have been combined with micromagnetic simulations to study the remnant magnetic states of electrodeposited Co/Cu multilayered nanocylinders. Structural and chemical data obtained by transmission electron microscopy have been introduced in the simulations. Three different magnetic configurations such as an antiparallel coupling of the Co layers, coupled vortices, and a monodomain-like state have been quantitatively mapped and simulated. While most of the wires present the same remnant state whatever the direction of the saturation field, we show that some layers can present a change from an antiparallel coupling to vortices. Such a configuration can be of particular interest to design nano-oscillators with two different working frequencies. PMID:26783831

  11. RELATIONSHIP BETWEEN INFRARED RADIATION AND CRYSTAL STRUCTURE IN Fe-Mn-Co-Cu-O SPINELS

    Y. Zhang; D.J. Wen

    2008-01-01

    Ni3+ and Cr3+ doped Fe-Mn-Co-Cu-O spinels have been prepared by solid phase sinfeting. The valence states and distribution of transition ions in the spinel crystals are inferred by the consideration of thermodynamic principle and crystalline field theory. The microstructure and performance of those are studied by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and IRE-2 infrared radiant instrument. Ni3+ and Cr3+ occupy the vacancies or substitute the other ions in the spinel structures and form diverse spinel structures, which exhibit infrared integral emissivities of 0.93 in the whole band, and 0.94 in the band within 14-25 um too. The content of Fe2O3 and MnO2 in the spinel crystals changes, maybe it induces infrared radiativity of spinels differently.

  12. Domain wall pinning in FeCoCu bamboo-like nanowires.

    Berganza, Eider; Bran, Cristina; Jaafar, Miriam; Vázquez, Manuel; Asenjo, Agustina

    2016-01-01

    The three dimensional nature of cylindrical magnetic nanowires has opened a new way to control the domain configuration as well as the magnetization reversal process. The pinning effect of the periodic diameter modulations on the domain wall propagation in FeCoCu individual nanowires is determined by Magnetic Force Microscopy, MFM. A main bistable magnetic configuration is firstly concluded from MFM images characterized by the spin reversal between two nearly single domain states with opposite axial magnetization. Complementary micromagnetic simulations confirm a vortex mediated magnetization reversal process. A non-standard variable field MFM imaging procedure allows us to observe metastable magnetic states where the propagating domain wall is pinned at certain positions with enlarged diameter. Moreover, it is demonstrated that it is possible to control the position of the pinned domain walls by an external magnetic field. PMID:27406891

  13. Co-Cu-Mg-Al四元类水滑石的合成与表征%Synthesis and Characterization of CoCuMgAl Hydrotalcite-like Compounds

    刘炳华

    2006-01-01

    以共沉淀法合成了1.5Co/0.5Cu/Al, 1.25Co/0.25Cu/0.5Mg/Al, Co/0.5Cu/0.5Mg/Al和Co/Cu/Al等样品,采用TG-DSC和XRD进行了表征.结果表明,1.5Co/0.5Cu/Al,1.25Co/0.25Cu/0.5Mg/Al和Co/0.5Cu/0.5Mg/Al样品都形成类水滑石(HTLcs),而Co/Cu/Al样品因Jahn-Teller效应未能形成HTLcs.

  14. Formation and corrosion behavior of glassy Ni-Nb-Ti-Zr-Co(-Cu) alloys

    Bulk glassy Ni55Nb20Ti10Zr8Co7 alloy with a critical diameter of 2 mm was synthesized by copper-mold casting and the glass transition temperature, crystallization temperature and supercooled liquid region are 858 K, 911 K and 52 K, respectively. High corrosion resistance in 1N HCl and H2SO4 solutions was recognized for the glassy alloys Ni55Nb20Ti10Zr8Co7 together with Ni53Nb20Ti10Zr8Co6Cu3 which possesses higher glass-forming ability. They are spontaneously passivated with low passive current densities of the order of 10-2 A/m2 and their corrosion rate was less than 10-3 mm/year in the solutions. A small amount addition of Cu (3 at.%) in the Ni-Nb-Ti-Zr-Co glassy alloy system has little effect on corrosion behavior and surface film composition. Niobium-rich passive films form on the glassy Ni-Nb-Ti-Zr-Co(-Cu) alloys, which could be responsible for the high corrosion resistance

  15. Correlation between interface structure and GMR in electrodeposited Co-Cu/Cu multilayers

    In a magnetic field, Co/Cu multilayers exhibit a large drop in resistance, and this so-called giant magnetoresistance (GMR) effect has made these materials attractive for applications in magneto-resistive devices. An attempt has been made to understand the correlation between the interface structure and the GMR properties by measurements performed on a multilayer series produced by galvanostatic electrodeposition under the application of a capacitance connected parallel to the electrochemical cell. As a result of this capacitance, the current pulse form was changed from the ideal rectangular shape to a trapezoidal current pulse shape and this was expected to increase the width of the chemically intermixed interface between the magnetic and non-magnetic layer. The film compositions were determined by energy-dispersive X-ray analysis in a scanning electron microscope, and were also estimated from the lattice parameters determined by X-ray diffraction measurements. The microstructure of the samples was studied by atomic force and transmission electron microscopy. (Authors)

  16. Current induced magnetization switching in Co/Cu/Ni-Fe nanopillar with orange peel coupling

    Aravinthan, D.; Daniel, M. [Centre for Nonlinear Dynamics, School of Physics, Bharathidasan University, Tiruchirappalli - 620 024 (India); Sabareesan, P. [Centre for Nonlinear Science and Engineering, School of Electrical and Electronics Engineering, SASTRA University, Thanjavur - 613 401 (India)

    2015-07-15

    The impact of orange peel coupling on spin current induced magnetization switching in a Co/Cu/Ni-Fe nanopillar device is investigated by solving the switching dynamics of magnetization of the free layer governed by the Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation. The value of the critical current required to initiate the magnetization switching is calculated analytically by solving the LLGS equation and verified the same through numerical analysis. Results of numerical simulation of the LLGS equation using Runge-Kutta fourth order procedure shows that the presence of orange peel coupling between the spacer and the ferromagnetic layers reduces the switching time of the nanopillar device from 67 ps to 48 ps for an applied current density of 4 × 10{sup 12}Am{sup −2}. Also, the presence of orange peel coupling reduces the critical current required to initiate switching, and in this case, from 1.65 × 10{sup 12}Am{sup −2} to 1.39 × 10{sup 12}Am{sup −2}.

  17. Ion-beam irradiation of Co/Cu nanostructures: Effects on giant magnetoresistance and magnetic properties

    We have studied the effects of ion irradiation at low doses (14 ions/cm2) on the structural properties, giant magnetoresistance (GMR), and interlayer magnetic coupling in Co/Cu multilayers. X-ray analysis combined with magnetic and resistivity measurements reveal that intermixing is promoted by ion irradiation while the periodic structure and crystallographic properties of the multilayers are not significantly altered. The GMR ratio of a multilayer decreases monotonically with ion dose. However, thermal annealing on an irradiated multilayer results in sharp recovery of the reduced GMR, and can be associated with a backdiffusion process in metastably intermixed regions. Hence, using ion irradiation and subsequent annealing, the GMR of a single multilayer can be altered reversibly over a wide range. The variation of GMR upon irradiation (or annealing) is accompanied by significant suppression (or improvement) of the antiferromagnetic interlayer coupling. The correlation between GMR and AF coupling, as well as the role of enhanced electron scattering at interfaces during these processes are discussed

  18. Studies on mass attenuation coefficients, effective atomic numbers and electron densities for CoCuAg alloy thin film

    Apaydın, G.; Cengiz, E.; Tıraşoğlu, E.; Aylıkcı, V.; Bakkaloğlu, Ö. F.

    2009-05-01

    The mass attenuation coefficients for the elements Co, Cu and Ag and a thin film of CoCuAg alloy were measured in the energy range 4.029-38.729 keV. Effective atomic numbers and electron densities were calculated by using these coefficients. The energies were obtained by using secondary targets that were irradiated with gamma-ray photons of 241Am. The x-rays were counted by using a Canberra Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV. The results were compared with theoretical calculated values and fairly good agreement was found between them within an average experimental error. The mass attenuation coefficients, effective atomic numbers and electron densities were plotted versus photon energy.

  19. Studies on mass attenuation coefficients, effective atomic numbers and electron densities for CoCuAg alloy thin film

    The mass attenuation coefficients for the elements Co, Cu and Ag and a thin film of CoCuAg alloy were measured in the energy range 4.029-38.729 keV. Effective atomic numbers and electron densities were calculated by using these coefficients. The energies were obtained by using secondary targets that were irradiated with gamma-ray photons of 241Am. The x-rays were counted by using a Canberra Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV. The results were compared with theoretical calculated values and fairly good agreement was found between them within an average experimental error. The mass attenuation coefficients, effective atomic numbers and electron densities were plotted versus photon energy.

  20. Measurement of resonant x-ray magnetic scattering from induced Cu polarizations in exchange-coupled Co/Cu multilayers

    An avalanche photodiode detector has been commissioned to measure weak resonant x-ray magnetic scattering (RXMS) from induced magnetic polarizations in Cu layers in exchange-coupled Co/Cu multilayers using circularly polarized x-rays from synchrotron sources. The detector can count x-rays at rates of 107 photons s-1, giving good estimates of the RXMS at superlattice Bragg peaks in a reasonably short time when count losses due to the time structure of the synchrotron x-rays are corrected for. RXMS superlattice Bragg peaks as small as 1 x 10-4 in flipping ratio have been measured from a Co/Cu multilayer at the K absorption edge of Cu. The data are fitted by an oscillatory model magnetization profile in the Cu layers derived from a Ruderman-Kittel-Kasuya-Yosida theory of exchange coupling adapted to a planar geometry

  1. Fabrication and evaluation of atmospheric plasma spraying WC-Co-Cu-MoS{sub 2} composite coatings

    Yuan Jianhui [Key Laboratory of Inorganic Coating Materials, Shanghai Institute of Ceramics (SIC), Chinese Academy of Sciences (CAS), Dingxi 1295, Changning, Shanghai, 200050 (China); Zhu Yingchun, E-mail: yzhu@mail.sic.ac.cn [Key Laboratory of Inorganic Coating Materials, Shanghai Institute of Ceramics (SIC), Chinese Academy of Sciences (CAS), Dingxi 1295, Changning, Shanghai, 200050 (China); Zheng Xuebing; Ji Heng; Yang Tao [Key Laboratory of Inorganic Coating Materials, Shanghai Institute of Ceramics (SIC), Chinese Academy of Sciences (CAS), Dingxi 1295, Changning, Shanghai, 200050 (China)

    2011-02-03

    Research highlights: > Protective WC-Co-based coatings containing solid lubricant Cu and MoS{sub 2} used in wear applications were investigated in this study. > It was found that the MoS{sub 2} composition in the feed powder was kept in WC-Co-Cu-MoS{sub 2} coatings, and the decomposition and decarburization of WC in APS process were improved. > Combining the wear resistance of WC with the lubricating properties of Cu and MoS{sub 2} has an extremely beneficial effect on improving the tribological performance of the resulting coating. - Abstract: Protective WC-Co-based coatings containing solid lubricant Cu and MoS{sub 2} used in wear applications were investigated in this study. These coatings were deposited on mild steel substrates by atmospheric plasma spraying (APS). The feedstock powders were prepared by mechanically mixing the solid lubricant powders and WC-Co powder, followed by sintering and crushing the mixtures to avoid different particle flighting trajectories at plasma. The tribological properties of the coatings against stainless steel balls were examined by ball-on-disk (BOD) tribometer under normal atmospheric condition. The microstructure of the coatings was studied by optical microscope, scanning electron microscope and X-ray diffraction. It was found that the MoS{sub 2} composition in the feed powder was kept in WC-Co-Cu-MoS{sub 2} coatings, and the decomposition and decarburization of WC in APS process were improved, which were attributed to the protection of Cu around them. The friction and wear behaviors of all the WC-Co-Cu-MoS{sub 2} coatings were superior to that of WC-Co coating. Such behavior was associated to different wear mechanisms operating for WC-Co coating and the WC-Co-Cu-MoS{sub 2} coatings.

  2. Sulfides from Martian and Lunar Basalts: Comparative Chemistry for Ni Co Cu and Se

    J Papike; P Burger; C Shearer; S Sutton; M Newville; Y Choi; A Lanzirotti

    2011-12-31

    Here Mars and Moon are used as 'natural laboratories' with Moon displaying lower oxygen fugacities ({approx}IW-1) than Mars ({approx}IW to FMQ). Moon has lower concentrations of Ni and Co in basaltic melts than does Mars. The major sulfides are troilite (FeS) in lunar basalts and pyrrhotite (Fe{sub 1-x}S) in martian basalts. This study focuses on the concentrations of Ni, Co, Cu, and Se. We chose these elements because of their geochemical importance and the feasibility of analyzing them with a combination of synchrotron X-ray fluorescence (SXRF) and electron microprobe (EPMA) techniques. The selenium concentrations could only be analyzed, at high precision, with SXRF techniques as they are <150 ppm, similar to concentrations seen in carbonaceous chondrites and interplanetary dust particles (IDPs). Nickel and Co are in higher concentrations in martian sulfides than lunar and are higher in martian olivine-bearing lithologies than olivine-free varieties. The sulfides in individual samples show very large ranges in concentration (e.g., Ni ranges from 50 000 ppm to <5 ppm). These large ranges are mainly due to compositional heterogeneities within individual grains due to diffusion and phase separation. Electron microprobe wavelength-dispersive (WDS) mapping of Ni, Co, and Cu show the diffusion trajectories. Nickel and Co have almost identical diffusion trajectories leading to the likely nucleation of pentlandite (Ni,Co,Fe){sub 9}S{sub 8}, and copper diffuses along separate pathways likely toward chalcopyrite nucleation sites (CuFeS{sub 2}). The systematics of Ni and Co in lunar and martian sulfides clearly distinguish the two parent bodies, with martian sulfides displaced to higher Ni and Co values.

  3. Characterization and reactivity of nanoscale La(Co,Cu)O 3 perovskite catalyst precursors for CO hydrogenation

    Tien-Thao, Nguyen; Alamdari, Houshang; Kaliaguine, Serge

    2008-08-01

    The characterization of La(Co,Cu)O 3 perovskites has been performed by several techniques including XRD, BET, H 2-TPR, O 2-TPO, TPRS, and the solids tested as catalysts for the hydrogenation of CO. The reducibility of the perovskites is strongly affected by the preparation route, calcination temperature, catalyst morphology, and the amount of remnant alkali. Compared with the citrate-derived perovskite, LaCoO 3 sample prepared by mechano-synthesis has various distinct Co 3+ ions in perovskite lattice, which are reduced at different temperatures. Under typical conditions, the reduction of cobalt ions occurs in two consecutive steps: Co 3+/Co 2+ and Co 2+/Co 0, while the intra-lattice copper ions are directly reduced from Cu 2+ to Cu 0. The reducibility of cobalt ions is promoted by the presence of metallic copper, which is formed at a lower reduction temperature. The re-oxidation of the reduced lanthanum cobaltite perovskite could regenerate the original structure, whereas that of the reduced Co-Cu-based samples is less reversible under the same experimental conditions. The cobalt atom in the reduced perovskites plays an important role in the dissociation of CO, but the presence of a neighboring copper along with remnant sodium ions on the catalyst surface has remarkably affected the reactivity of cobalt for CO hydrogenation. The addition of copper into the perovskite framework leads to a change in the product distribution of CO hydrogenation and a decrease in reaction temperature. An increased copper content leads to a substantial decline in the rate of methanation and an increase in the formation of higher alcohols. A close proximity between cobalt and copper sites on the Na +-modified catalyst surface of the reduced nanocrystalline Co-Cu-based perovskites plays a crucial role in the synthesis of higher alcohols from syngas.

  4. Magnetic behaviour investigation on symmetric spin valves of Co/Cu/NiFe and NiFe/Cu/Co

    李铁; 沈鸿烈

    2002-01-01

    In this paper, we have obtained and investigated the magnetic behaviours of the ferromagnetic layer in thesymmetric spin valves of Co/Cu/NiFe and NiFe/Cu/Co by measuring with a vibrating sample magnetometer andanalysing in terms of the multi-domain Ising models. It has been found that some magnetic layer can have quitedifferent magnetic behaviours in different structures of spin valves, depending on the properties of the under-layer. Inour investigation, we have found that the magnetic behaviour of a Co layer depends mainly on the magnetization of theunder-layer, whereas this is not the case for the NiFe layer.

  5. Magnetic anisotropy studies on the cobalt-based chain molecular magnet CoCu(opba)(DMSO)3

    The present paper reports on a study of the magnetic anisotropy of the Co-based chain molecular magnet CoCu(opba)(DMSO)3. The magnetic anisotropy measurements were performed on microgram monocrystalline samples using a cantilever magnetometer at low temperatures down to 1.5 K and magnetic fields up to 7 T. The field dependence of the magnetic torque confirms an ordered ferrimagnetic structure at low temperature, TC=6 K, with a very small coercive field. Magnetic torque measurements as a function of the angle within the a-c and b-c planes suggest the emergence of biaxial behavior at low temperatures. Our results suggest that the resulting ferromagnetic moment lies perpendicular to both the CuCo-chains and hard magnetic axis

  6. The isothermal section at 923 K of the Co-Cu-Ti ternary system measured by using diffusion triple

    The isothermal section at 923 K in the Co-Cu-Ti system was experimentally studied by using the diffusion triple technique together with scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). High solubility of Cu, up to 22.5 at.% (substituting Co) in CoTi was observed at this temperature; and the solubility of Co (substituting Cu) in CuTi is also large which is up to 14.0 at.%. For other binary compounds CoTi2, CuTi2, Cu4Ti3 and Cu3Ti2, the ternary solubilities are remarkable too. No ternary compound has been detected. Nine three-phase equilibria were determined and three others in the Ti-enriched corner were estimated. Further investigations are essential to confirm the possible ternary phase reported and to determine the invariant reactions in the ternary system

  7. Lateral electric-field control of giant magnetoresistance in Co/Cu/Fe/BaTiO3 multiferroic heterostructure

    We report lateral electric-field-driven sizable changes in the magnetoresistance of Co/Cu/Fe tri-layered wires on BaTiO3 single crystal. While the observed change is marginal in the tetragonal phase of BaTiO3, it reaches over 40% in the orthorhombic and rhombohedral phases with an electric field of 66 kV/cm. We attribute it to possible electric-field-induced variations of the spin-dependent electronic structures, i.e., spin polarization, of the Fe via interfacial strain transfer from BaTiO3. The contrasting results for the different phases of BaTiO3 are discussed, associated with the distinct aspects of the ferroelectric polarization switching processes in each phase

  8. The effects of small metal additions (Co, Cu, Ga, Mn, Al, Bi, Sn) on the magnetocaloric properties of the Gd5Ge2Si2 alloy

    Shull, R. D.; Provenzano, V.; Shapiro, A. J.; Fu, A.; Lufaso, M. W.; Karapetrova, J.; Kletetschka, Günther; Mikula, V.

    2006-01-01

    Roč. 99, č. 8 (2006), s. 8-8. ISSN 0021-8979 Institutional research plan: CEZ:AV0Z30130516 Keywords : magnetocaloric * (Co, Cu, Ga, Mn, Al, Bi, Sn) additions * Cryogenic properties Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.316, year: 2006

  9. Mineralogy and trace element geochemistry of the Co- and Cu-bearing sulfides from the Shilu Fe-Co-Cu ore district in Hainan Province of South China

    Wang, Zhilin; Xu, Deru; Zhang, Zhaochong; Zou, Fenghui; Wang, Li; Yu, Liangliang; Hu, Mingyue

    2015-12-01

    Hosted within the metamorphosed, neritic siliciclastic rocks and sedimentary carbonates of the Proterozoic Shilu Group, the Shilu Fe-Co-Cu ore district in Hainan Province of South China comprises the upper Fe- and the lower Co-Cu ore layers. Combined with the field observation, the mineralogical and geochemical studies of sulfides using electron microprobe and laser ablation ICP-MS analyses recognized three types of Co-Cu ores. Type I is represented by massive ores and mainly comprises the first generation of pyrite (PyI) which occurred either as recrystallized, subhedral to euhedral microcrystal aggregates (PyIa) or as elongated, fine-grained euhedral grains (PyIb) with an orientated alignment parallel to S1 foliation. Type II is banded, disseminated and brecciated ores, and composed of the second generation of pyrite (PyII) which displays internal rhythmic growth zoning, the first generations of chalcopyrite (CcpI) and pyrrhotite (PoI), and associated Co-(Ni)-(As)-sulfide minerals. Type III occurring as veins or veinlets mainly consists of the third generation of pyrite (PyIII) and the second generations of chalcopyrite (CcpII) and pyrrhotite (PoII), of which PyIII appears as subhedral to euhedrall grains or as rims of composite pyrite. The moderate Co and As, and high Ni contents as well as the low Co/Ni ratios (∼2-5) in PyI indicate a sedimentary-metamorphic origin for Type I ores. The higher Co, Ni and As concentrations in PyIb relative to PyIa likely was related to an inhomogeneous deformation-metamorphism. The highest Co (av. 51,195 ppm) in PyII and Ni (av. 3374 ppm) in PoI most likely were linked to the preferred incorporation of Co into pyrite and Ni into pyrrhotite. Combined with the high Ag concentrations in CcpI (av. 266 ppm) and PyII (av. 13.32 ppm), the high Co/Ni ratios in PyII (av. 1241) suggest the derivation of Type II ores from a Co-Cu-Ni-Ag-rich hydrothermal fluid. Further, up to 9 wt.% Co concentrations in PyII show a temperature condition of

  10. Expansion Hamiltonian model for a diatomic molecule adsorbed on a surface: Vibrational states of the CO/Cu(100) system including surface vibrations

    Molecular-surface studies are often done by assuming a corrugated, static (i.e., rigid) surface. To be able to investigate the effects that vibrations of surface atoms may have on spectra and cross sections, an expansion Hamiltonian model is proposed on the basis of the recently reported [R. Marquardt et al., J. Chem. Phys. 132, 074108 (2010)] SAP potential energy surface (PES), which was built for the CO/Cu(100) system with a rigid surface. In contrast to other molecule-surface coupling models, such as the modified surface oscillator model, the coupling between the adsorbed molecule and the surface atoms is already included in the present expansion SAP-PES model, in which a Taylor expansion around the equilibrium positions of the surface atoms is performed. To test the quality of the Taylor expansion, a direct model, that is avoiding the expansion, is also studied. The latter, however, requests that there is only one movable surface atom included. On the basis of the present expansion and direct models, the effects of a moving top copper atom (the one to which CO is bound) on the energy levels of a bound CO/Cu(100) system are studied. For this purpose, the multiconfiguration time-dependent Hartree calculations are carried out to obtain the vibrational fundamentals and overtones of the CO/Cu(100) system including a movable top copper atom. In order to interpret the results, a simple model consisting of two coupled harmonic oscillators is introduced. From these calculations, the vibrational levels of the CO/Cu(100) system as function of the frequency of the top copper atom are discussed

  11. Nano-Scale Interface Modification of the Co/Cu System: Metallic Surface Modifiers in the Growth of Smooth Thin Films

    This review is a collection of twelve original papers concerning growth and interface modification in the Co/Cu system. Most of this research has been carried out in the Laboratory of Surface and Thin Film Physics at the Institute of Nuclear Physics. The Laboratory was created by the author of this review in 1996 in strong collaboration with the Institute of Nuclear Physics Wilhelms-Universitaet in Muenster, Germany and the Institute of Applied Physics Ukrainian Academy of Science in Sumy, Ukraine. The big international team worked under the leadership of Dr Marta Marszalek, initially developing a multicomponent ultrahigh vacuum setup for thin film preparation and analysis, and next accompanying her in studies of the structural, magnetic and magnetotransport properties of Co/Cu multilayers. Systems that exhibit giant magnetoresistance effect have been receiving intensive attentions over recent years since they are possible candidates for applications in ultrahigh-density data storage and magnetoelectronic devices. The focus of this research is the growth of magnetic Co/Cu multilayers modified by using metallic surface modifiers called surfactants. The different approaches have been used. Surfactant metals were introduced once into growth process as a buffer layer or they were deposited sequentially at each interface of Co/Cu multilayers. The growth was performed by molecular beam epitaxy technique which allows to tailor carefully deposition conditions. The results showed that two approaches gave different results. Surfactant buffer layers resulted in loss of layered character of multilayers being a kind of an intermediate cluster-like phase combined with a layered area. Small amount of surfactants introduced at each interface lead to well-ordered structures with small roughness and smoother interfaces than in the case of pure Co/Cu multilayers. Despite of the differences, in both cases the improvement of magnetoresistance value was observed. The atomic scale study

  12. Synthesis, Characterization of Heterodinuclear Co-Cu Complex and Its Electrocatalytic Activity towards 02 Reduction: Implications for Cytochrome c Oxidase Active Site Modeling

    卢卫兵; 汪存信; 周晓海; 任建国

    2003-01-01

    A new dinudeating ligand consisting of a tetraphanylporphyrin derivative covalently linked with tris(2-benzimidazylmethyl)-amine and its homodinudear Co-Co and heterodinnelear Co-Cu complexes were synthesized and spectroscopically character-ized. The heterobimetallie cobalt-copper complex bearing three benzimidazole ligands for copper, as cytochrome c oxidase ac-tive site model, was applied to the surface of glassy carbon elec-trode to show electrocatalytie activity for O2 reduction in aque-ous solution at an addity level dose to physiological pH value.The kinetic parameters of this electrocatalytic process were ob-tained.

  13. Certification of trace element contents (As, Cd, Co, Cu, Fe, Mn, Hg, Na, Pb and Zn) in a fly ash obtained from the combustion of pulverised coal

    The element contents of As, Cd, Co, Cu, Fe, Mn, Hg, Na, Pb and Zn of a fly ash from pulverised coal are certified. The procedures and their results for the homogenisation, the contamination and homogeneity checks and the analytical campaign are reported. The certified mass fractions and indicative values for Cr, Ni, Th, V and water soluble sulphate are given. The work was carried out within the framework of the activities of the Community Bureau of Reference (BCR) of the Commission of the European Communities. (orig.)

  14. Self-regulating homogenous growth of high-quality graphene on Co-Cu composite substrate for layer control

    Lin, Tianquan; Huang, Fuqiang; Wan, Dongyun; Bi, Hui; Xie, Xiaoming; Jiang, Mianheng

    2013-06-01

    layer. High quality single-layered graphene films with a 98% yield were prepared on an 80 nm-Co-coated Cu foil and insensitive to growth temperature and time. More importantly, this type of composite substrate has also been developed to grow AB-stacked bilayers and three-layer graphene with 99% surface coverage and absence of defects. The approach is opening up a new avenue for high-quality graphene production with precise layer control through composite substrate design. Electronic supplementary information (ESI) available: Additional characteristics of graphene films with different layer (optical microscope and SEM images, Raman mapping of FWHM, XPS profiles); measurements of electrical properties; explanation for tolerance of Co-Cu substrate to variations; calculation procedures of minimum thickness for Co layer. See DOI: 10.1039/c3nr33124e

  15. Microstructural evolution and the magnetic properties of melt-spun Sm-Co-Cu-B and Sm-Co-Fe-Cu-B ribbons

    An attempt has been made to obtain nanocomposite from Sm-Co-Cu-based alloys. Sm12Co60Cu26B2 and Sm16.7Co48.3Fe25Cu8.3B1.7 alloys were selected by considering the two-phase region of the Sm-Co-Cu ternary phase diagram and the phase equilibria of Sm-Co-Fe. Sm12Co60Cu26B2 melt-spun ribbon transformed from TbCu7 (1:7 H) type to Th2Ni17 (2:17 H)-type phase on annealing at 600 deg. C for 10 min and exhibited coercivity (iHc) of ∼8.0 kOe. Co23B6 precipitates were found either within the grains or at the grain boundary of the hard magnetic phase, and recoil curves in the demagnetization curve indicated exchange coupling between the two phases. Sm16.7Co48.3Fe25Cu8.3B1.7 melt-spun ribbon showed an intermediate value of coercivity (iHc∼3-5 kOe). (FeCo)-B precipitates were found at the grain boundaries of SmCo5 hard magnetic phase

  16. Use of anomalous scattering for synchrotron X-ray reflectivity studies of Fe-Cr and Co-Cu double layers

    Prokert, F; Gorbunov, A

    2003-01-01

    Double layers of Fe-Cr and Co-Cu, respectively, were prepared on oxidized Si substrates by pulsed laser deposition (PLD). The interfacial roughness structure was studied by synchrotron X-ray reflectivity measurements at the absorption K-edges using the contrast enhancement due to resonant scattering. The results are determined from simulations of the measured specular and diffuse scans. Whereas in Fe-Cr double layers the sigma sub r sub m sub s -interface width for Fe deposition on Cr (sigma sub C sub r =0.70+-0.1 nm) is not very different from that of Cr deposition on Fe (sigma sub F sub e =0.85+-0.1 nm), in Co-Cu double layers, in contrast, for Cu deposition on Co, the width (sigma sub C sub o =0.65+-0.1 nm) is much smaller than for Co deposition on Cu (sigma sub C sub u =1.5+-0.15 nm). On the basis of the fractal model to describe the interface roughness morphology, from the off-specular scans the lateral roughness correlation length, xi and the roughness exponent, h, were determined. For both types of dou...

  17. Structure and magnetism of S = 1/2 kagome antiferromagnets NiCu3(OH)6Cl2 and CoCu3(OH)6Cl2

    We have successfully synthesized S = 1/2 kagome antiferromagnets MCu3(OH)6Cl2 (M = Ni and Co) by a hydrothermal method with a rotating pressure vessel. Structural characterization shows that both compounds have similar crystal structure to ZnCu3(OH)6Cl2 with R 3-bar m symmetry. As with ZnCu3(OH)6Cl2, the compounds show no obvious hysteresis at 2 K. A spin-glass transition is found in both NiCu3(OH)6Cl2 and CoCu3(OH)6Cl2 at low temperatures (6.0 and 3.5 K respectively) by AC susceptibility measurements. This indicates no long-range magnetic order and a strong spin frustration. The substitution of Zn2+ by magnetic ions Ni2+ or Co2+ effectively enhances the interlayer exchange coupling and changes the ground state of the kagome spin system.

  18. Vortex domain wall propagation in periodically modulated diameter FeCoCu nanowire as determined by the magneto-optical Kerr effect.

    Palmero, Ester M; Bran, Cristina; Del Real, Rafael P; Vázquez, Manuel

    2015-11-20

    Control over the magnetization reversal process of nanowires is essential to current advances in modern spintronic media and magnetic data storage. Much effort has been devoted to permalloy nanostrips with rectangular cross section and vanishing crystalline anisotropy. Our aim was to unveil and control the reversal process in FeCoCu nanowires with significant anisotropy and circular cross section with tailored periodical modulations in diameter. Magneto-optical Kerr effect measurements and their angular dependence performed on individual nanowires together with their analysis allow us to conclude that the demagnetization process takes place due to the propagation of a single vortex domain wall which is eventually pinned at given modulations with slightly higher energy barrier. In addition these results create new expectations for further controlling of the propagation of single and multiple domain walls. PMID:26501722

  19. Investigation of exchange bias in 0.1MFe2O4/0.9BiFeO3 (M=Co, Cu, Ni) nanocomposite

    The 0.1MFe2O4/0.9BiFeO3 (M=Co, Cu, Ni) nanocomposite samples were synthesized by the sol–gel method. Phase composition analysis was carried out, which showed that these bulk samples were composed of a ferrimagnetic MFe2O4 (M=Co, Cu, Ni) and a ferroelectric antiferromagnet (FEAF) BiFeO3 phases, respectively. The magnetic properties of all the samples were investigated by measuring their magnetization as a function of temperature and magnetic field. These results indicated that the magnetic hysteresis loops of 0.1CuFe2O4/0.9BiFeO3 sample sintered in air atmosphere at 550 °C for 3 h exhibited a negative shift and an enhanced coercivity at low temperature ascribed to strong exchange coupling between the BiFeO3 and CuFe2O4 grains. However, there were no magnetic hysteresis loops in both the 0.1CoFe2O4/0.9BiFeO3 sample and the 0.1NiFe2O4/0.9BiFeO3 sample. In view of these results, we tend to think the CuFe2O4/BiFeO3 nanocomposite system may be a useful multifunctional material. - Highlights: ► Exchange bias effect in ferroelectric antiferromagnet (FEAF)/ferromagnet (FM) nanocomposites. ► Exchange bias effect is only observed in the 0.1CuFe2O4/0.9BiFeO3 nanocomposite. ► Lower saturation magnetization is important for producing exchange bias in FEAF/FM system.

  20. Structural and magnetic characterization of as-prepared and annealed FeCoCu nanowire arrays in ordered anodic aluminum oxide templates

    Rodríguez-González, B., E-mail: jbenito@uvigo.es [CACTI, University of Vigo, E-36310 Vigo (Spain); International Iberian Nanotechnology Laboratory, INL. Av. Mestre J. Veiga, 4715-330 Braga (Portugal); Bran, C.; Warnatz, T.; Vazquez, M. [Institute of Materials Science of Madrid, CSIC, 28049 Madrid (Spain); Rivas, J. [International Iberian Nanotechnology Laboratory, INL. Av. Mestre J. Veiga, 4715-330 Braga (Portugal)

    2014-04-07

    Herein, we report on the preparation, structure, and magnetic characterization of FeCoCu nanowire arrays grown by DC electrodeposition inside self-assembled ordered nanopores of anodic aluminum oxide templates. A systematic study of their structure has been performed both in as-prepared samples and after annealing in the temperature range up to 800 °C, although particular attention has been paid to annealing at 700 °C after which maximum magnetic hardening is achieved. The obtained nanowires have a diameter of 40 nm and their Fe{sub 0.28}Co{sub 0.67}Cu{sub 0.05} composition was confirmed by energy dispersive X-ray spectroscopy (EDS). Focused ion-beam lamellas of two samples (as-prepared and annealed at 700 °C) were prepared for their imaging in the high-resolution transmission electron microscopy (HRTEM) perpendicularly to the electron beam, where the obtained EDS compositional mappings show a homogeneous distribution of the elements. X-ray diffraction analysis, and selected area electron diffraction (SAED) patterns confirm that nanowires exhibit a bcc cubic structure (space group Im-3m). In addition, bright-dark field images show that the nanowires have a polycrystalline structure that remains essentially the same after annealing, but some modifications were observed: (i) an overall increase and sharpening of recrystallized grains, and (ii) an apparent shrinkage of the nanowires diameter. Obtained SAED patterns also show strong textured components with determined <111> and <112> crystalline directions parallel to the wires growth direction. The presence of both directions was also confirmed in the HRTEM images doing Fourier transform analyses. Magnetic measurements show strong magnetic anisotropy with magnetization easy axis parallel to the nanowires in as-prepared and annealed samples. The magnetic properties are tuned by suitable thermal treatments so that, maximum enhanced coercivity (∼2.7 kOe) and normalized remanence (∼0.91 Ms) values are

  1. Geochemical and Nd isotopic constraints on provenance and depositional setting of the Shihuiding Formation in the Shilu Fe-Co-Cu ore district, Hainan Province, South China

    Yu, Liangliang; Zou, Shaohao; Cai, Jianxin; Xu, Deru; Zou, Fenghui; Wang, Zhilin; Wu, Chuanjun; Liu, Meng

    2016-04-01

    The Shihuiding Formation, a subordinate succession hosting the Fe-Co-Cu ores, is a suite of Neoproterozoic terrigenous clastic rocks occurring in the Shilu Fe-Co-Cu ore district of the Hainan Island, South China. Integrated petrographical, geochemical, and Nd isotopic analyses have been carried out on 23 sandstone specimens of the Shihuiding Formation in order to understand their provenance and the tectonic setting of their deposition. The samples can be divided into two groups, quartzose sandstones (13 samples) and ferruginous sandstones (10 samples). The ferruginous sandstones have average SiO2 and Fetotal contents of 77.23 wt.% and 18.09 wt.%, respectively, and this contrasts with the higher average SiO2 (94.04 wt.%) and lower Fetotal (2.67 wt.%) contents of the quartzose sandstones. The bivariant Th/Sc and Zr/Sc ratios indicate a predominantly recycled sedimentary provenance, and the low to medium degrees of weathering are commonly indicated by an average chemical index of maturity (CIM) of 81 and an average chemical index of alteration (CIA) of 68. The Shihuiding Formation sandstones have REE contents of 21-249 ppm, with LREE/HREE = 9.18 and δEu = 0.67. The εNd (970 Ma) values of -5.7 to -3.4, and model (TDM) ages of 2099-1773 Ma are compatible with a source mainly from the Paleo- to Mesoproterozoic Baoban Group, a suite of metamorphosed sedimentary rocks intruded by ca. 1450 Ma granites. Quantitative provenance modeling indicates that the Shihuiding Formation sandstones are best modeled with a mixture of 29% plagioclase-amphibole gneiss (29 P), 38% quartz-muscovite schist (38 Q), and 33% granite (33 G) detritus. Mixing the εNd values of the sandstones, calculated at 970 Ma, indicates that the sediment received 22-47% (average 34%) of its detritus from the Baoban Group quartz-muscovite schists. Components from hydrothermal fluids may also have been involved during deposition of the Shihuiding Formation sandstones, as revealed by a bivariant Al/(Al + Fe + Mn

  2. Surface composition changes of redox stabilized bimetallic CoCu nanoparticles supported on silica under H-2 and O-2 atmospheres and during reaction between CO2 and H-2 : in situ X-ray spectroscopic characterization.

    Alayoglu, S.; Beaumont, Simon K.; Melaet, G.; Lindeman, A.E.; Musselwhite, N.; Brooks, C J; Marcus, M. A.; Guo, J. G.; Liu, Z.; Kruse, N; Somorjai, G.A.

    2013-01-01

    In this paper, we report the colloidal synthesis and detailed characterization of 11 nm bimetallic CoCu nanoparticle catalysts. Presently Co and Cu is an attractive combination because of their respective properties for industrially important Fischer–Tropsch and methanol synthesis reactions of CO (and CO2) with H2. We report the preparation of catalysts by deposition of bimetallic metal nanoparticles, both within mesoporous silica (MCF-17) and on the native oxide surface of a silicon wafer. S...

  3. Temporal dynamics of pore water concentrations of Cd, Co, Cu, Ni, and Zn and their controlling factors in a contaminated floodplain soil assessed by undisturbed groundwater lysimeters

    We aimed to assess the dynamics of pore water concentrations of Cd, Co, Cu, Ni, Zn and their controlling factors (EH, pH, DOC, Fe, Mn, and SO42−) in a contaminated floodplain soil under different flood-dry-cycles. Two parallel undisturbed groundwater lysimeters (mean values presented) were used for long term (LT; 94 days) and short term (ST; 21 days) flood-dry-cycles. Reducing conditions under LT lead to low EH and pH, while DOC, Co, Fe, Mn, and Ni increased. Cadmium, Cu, Zn, and SO42− increased under oxidizing conditions during ST. Cobalt and Ni revealed a similar behavior which seem to governed by EH/pH, Mn, Fe, and DOC. Cadmium, Cu, and Zn reveal a similar fate; their dynamics were affected by EH/pH, DOC, and SO42−. Our findings suggest that a release of Cd, Cu, Co, Fe, Mn, Ni, and Zn under different flood-dry-cycles can assumed what might create potential environmental risks in using metal-enriched floodplain soils. - Highlights: • Flooding durations and frequency affect soil metal dynamics in undisturbed lysimeters. • Long term flooding released DOC, Co, Fe, Mn, and Ni to soil solution. • During short term cycles Cd, Cu, Zn, and SO42− tended to be mobilized at high EH. • Dynamics of Co and Ni were controlled mainly by chemistry of Fe, Mn, and DOC. • Dynamics of Cd, Cu, and Zn were governed mainly by DOC and SO42−. - Flooding duration and frequency affect dynamics of metals in a floodplain soil

  4. Enhanced photocatalytic H2-production activity of CdxZn1−xS nanocrystals by surface loading MS (M = Ni, Co, Cu) species

    Highlights: ► CdxZn1−xS solid solution was prepared by co precipitation reflux method. ► MS (M = Ni, Co, Cu) provides active sites for CdxZn1−xS hydrogen evolution. ► The hydrogen production rate of MS/Cd0.4Zn0.6S is 5 times higher than Cd0.4Zn0.6S. ► MS causes fast diffusion of photoelectrons generated from Cd0.4Zn0.6S toward MS. - Abstract: To investigate the role of metal sulfides as co-catalyst for photocatalytic hydrogen production under visible light irradiation, we have loaded small amounts of transition-metal sulfides (MS), such as NiS, CoS and CuS, onto the surface of CdxZn1−xS solid solution. It can be found that the rate of H2 evolution over the MS/Cd0.4Zn0.6S was 5 times higher than that of the pure Cd0.4Zn0.6S, and is comparable to the Cd0.4Zn0.6S modified with 1 wt% platinum (Pt) co-catalysts. The MS/Cd0.4Zn0.6S photocatalysts were characterized by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), UV–visible spectrophotometer (UV–vis), and photoluminescence (PL) spectroscopy. It can be speculated that the MS provided active sites for H2 production and caused the migration of excited electrons from Cd0.4Zn0.6S toward MS, leading to the enhancement of photocatalytic activity.

  5. Layered perovskite PrBa0.5Sr0.5CoCuO5+δ as a cathode for intermediate-temperature solid oxide fuel cells

    Highlights: • A single-phase layered-perovskite PrBa0.5Sr0.5CoCuO5+δ (PBSCCu) is prepared by the EDTA–citrate complexing method. • PBSCCu cathode has a good chemical compatible with GDC electrolyte. • Partial substitution of Cu for Co can efficiently lower the thermal expansion coefficient. • Performances of PrBa0.5Sr0.5CoCuO5+δ cathode based on Gd0.1Ce0.9O1.95 electrolyte is reported firstly. - Abstract: Layered perovskite PrBa0.5Sr0.5CoCuO5+δ (PBSCCo) oxide is synthesized by EDTA–citrate complexing method and investigated as a novel cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs). X-ray diffraction results show that PBSCCo is chemical compatible with Gd0.1Ce0.9O1.95 (GDC) electrolyte below 950 °C. The thermal expansion coefficient of PBSCCo is 17.58 × 10−6 K−1 between 30 °C and 900 °C. The maximum electrical conductivity of PBSCCo is 483 S cm−1 at 325 °C. The polarization resistance of PBSCCo cathode on GDC electrolyte is as low as 0.06 Ω cm2 at 800 °C. The maximum power density of the electrolyte-supported single cell with PBSCCo cathode achieves 521 mW cm−2 at 800 °C. Preliminary results indicate that PBSCCo is a potential cathode material for application in IT-SOFCs

  6. Energy Parameters of Interfacial Layers in Composite Systems: Graphene – (Si, Cu, Fe, Co, Au, Ag, Al, Ru, Hf, Pb and Semiconductor (Si,Ge – (Fe, Co, Cu, Al, Au, Cr, W, Pb

    B.P. Koman

    2015-12-01

    Full Text Available On the basis of the non-equilibrium thermodynamics relations and the surface physics phenomena we calculate adhesion and energy parameters to characterize the interfacial interactions in graphene – (Si, Cu, Fe, Co, Au, Ag, Al, Ru, Hf, Pb and semiconductor (Si, Ge – (Fe, Co, Cu, Al, Au, Cr, W, Pb systems. We analyze trends of the interfacial energy, interfacial tension, work of adhesion and the energy of adhesive bonds on the contacting element’s atomic number in the periodic table and on the electronegativity difference of interacting elements. Thus, this work provides theoretical basis for the development of new composite materials.

  7. Estudo de metais pesados (Co, Cu, Fe, Cr, Ni, Mn, Pb e Zn na Bacia do Tarumã-Açu Manaus (AM Heavy metal (Co, Cu, Fe, Cr, Ni, Mn, Pb e Zn study in the Tarumã-Açu Basin Manaus (AM

    Genilson Pereira Santana

    2007-01-01

    Full Text Available Os resíduos gerados em domicílios incluem diversos produtos, como pesticidas, produtos farmacêuticos, detergentes, óleos de cozinha, metais pesados contidos em baterias e outros utensílios. Esses resíduos são lançados continuamente em aterro sanitário ou lixões em cidades como Manaus. O chorume produzido nesses aterros, quando não tratados, contamina recursos hídricos superficiais e subterrâneos. Neste estudo foi feita uma avaliação das conseqüências da liberação do chorume no sistema hídrico da bacia do Tarumã-Açu. Amostras de água e sedimento foram coletadas nos igarapés Matrinxã, Acará, Bolívia, bacia do Tarumã-Açu e dentro do aterro sanitário (Manaus - Amazonas - Brasil em março 2001. As amostras de água foram filtradas em filtro Milipore (0,45 mm de poro e, em seguida, tratadas com HNO3 concentrado. As amostras de sedimento foram peneiradas em malha de 0,053 mm e digeridas com HCl:HNO3 (1:3 a 150ºC. As concentrações de alguns metais pesados (Co, Cu, Fe, Cr, Ni, Mn, Pb e Zn foram determinadas nas amostras de água e sedimento por espectrometria de absorção atômica de chama. Os resultados revelaram que a concentração dos metais pesados é muito acima dos permitidos pela resolução 357/2005 do CONAMA em praticamente todos os locais amostrados, mostrando que o Aterro Sanitário é um dos principais responsáveis pelo impacto ambiental observado nos corpos hídricos estudados. As análises dos componentes principais (PCA e hierárquica de cluster (HCA, revelam que os pontos de coleta localizados dentro do aterro sanitário apresentam características diferentes dos outros locais amostrados. Além disso, o HCA e PCA mostraram que existe uma similaridade entre os pontos de coleta localizados fora do aterro o que permite afirmar que o chorume do aterro se dissolve por todo corpo hídrico estudado.Domestic sewage involves several products, such as pesticides, pharmaceutics products, detergents, soybean oil

  8. Intermetallic compound formation in Sn-Co-Cu, Sn-Ag-Cu and eutectic Sn-Cu solder joints on electroless Ni(P) immersion Au surface finish after reflow soldering

    The interfacial reactions between Sn-0.4Co-0.7Cu eutectic alloy and immersion Au/electroless Ni(P)/Cu substrate were investigated after reflow soldering at 260 deg. C for 2 min. Common Sn-4.0Ag-0.5Cu and eutectic Sn-0.7Cu solders were used as reference. Two types of intermetallic compounds (IMC) were found in the solder matrix of the Sn-0.4Co-0.7Cu alloy, namely coarser CoSn2 and finer Cu6Sn5 particles, while only one ternary (Cu, Ni)6Sn5 interfacial compound was detected between the solder alloy and the electroless nickel and immersion gold (ENIG) coated substrate. The same trend was also observed for the Sn-Ag-Cu and Sn-Cu solder joints. Compared with the CoSn2 particles found in the Sn-Co-Cu solder and the Ag3Sn particles found in the Sn-Ag-Cu solder, the Cu6Sn5 particles found in both solder systems exhibited finer structure and more uniform distribution. It was noted that the thickness of the interfacial IMCs for the Sn-Co-Cu, Sn-Ag-Cu and Sn-Cu alloys was 3.5 μm, 4.3 μm and 4.1 μm, respectively, as a result of longer reflow time above the alloy's melting temperature since the Sn-Ag-Cu solder alloy has the lowest melting point

  9. Intermetallic compound formation in Sn-Co-Cu, Sn-Ag-Cu and eutectic Sn-Cu solder joints on electroless Ni(P) immersion Au surface finish after reflow soldering

    Sun Peng [Key State Lab for New Displays and System Integration (Chinese Ministry of Education), SMIT Center, Shanghai University, 200072 Shanghai (China) and Department of Microtechnology and Nanoscience, SMIT Center, Chalmers University of Technology, 412-96 Goeteborg (Sweden)]. E-mail: peng.sun@mc2.chalmers.se; Andersson, Cristina [Department of Microtechnology and Nanoscience, SMIT Center, Chalmers University of Technology, 412-96 Goeteborg (Sweden); Wei Xicheng [Key State Lab for New Displays and System Integration (Chinese Ministry of Education), SMIT Center, Shanghai University, 200072 Shanghai (China); Cheng Zhaonian [Department of Microtechnology and Nanoscience, SMIT Center, Chalmers University of Technology, 412-96 Goeteborg (Sweden); Shangguan Dongkai [Flextronics International, San Jose, CA (United States); Liu Johan [Key State Lab for New Displays and System Integration (Chinese Ministry of Education), SMIT Center, Shanghai University, 200072 Shanghai (China); Department of Microtechnology and Nanoscience, SMIT Center, Chalmers University of Technology, 412-96 Goeteborg (Sweden)

    2006-11-25

    The interfacial reactions between Sn-0.4Co-0.7Cu eutectic alloy and immersion Au/electroless Ni(P)/Cu substrate were investigated after reflow soldering at 260 deg. C for 2 min. Common Sn-4.0Ag-0.5Cu and eutectic Sn-0.7Cu solders were used as reference. Two types of intermetallic compounds (IMC) were found in the solder matrix of the Sn-0.4Co-0.7Cu alloy, namely coarser CoSn{sub 2} and finer Cu{sub 6}Sn{sub 5} particles, while only one ternary (Cu, Ni){sub 6}Sn{sub 5} interfacial compound was detected between the solder alloy and the electroless nickel and immersion gold (ENIG) coated substrate. The same trend was also observed for the Sn-Ag-Cu and Sn-Cu solder joints. Compared with the CoSn{sub 2} particles found in the Sn-Co-Cu solder and the Ag{sub 3}Sn particles found in the Sn-Ag-Cu solder, the Cu{sub 6}Sn{sub 5} particles found in both solder systems exhibited finer structure and more uniform distribution. It was noted that the thickness of the interfacial IMCs for the Sn-Co-Cu, Sn-Ag-Cu and Sn-Cu alloys was 3.5 {mu}m, 4.3 {mu}m and 4.1 {mu}m, respectively, as a result of longer reflow time above the alloy's melting temperature since the Sn-Ag-Cu solder alloy has the lowest melting point.

  10. Evolution with time of 12 metals (V, Cr, Mn, Co, Cu, Zn, Ag, Cd, Ba, Pb, Bi and U) and of lead isotopes in the snows of Coats Land (Antarctica) since the 1830's

    This work shows that it is now possible to get reliable data on the occurrence of numerous heavy metals at ultra low levels in Antarctic snow, by combining ultra clean field sampling and laboratory sub-sampling procedures and the use of ultra sensitive analytical techniques such as ICP-SFMS and TIMS. It has allowed us to determine concentrations of twelve metals (V, Cr, Mn, Co, Cu, Zn, Ag, Cd, Ba, Pb, Bi et U) and lead isotopic composition in the ultra clean series of snow samples collected at Coats Land, in the Atlantic sector of Antarctica. This work presents a 150 years record of metal inputs from natural and anthropogenic sources to Antarctica from the 1830's to the early 1990's. Lead atmospheric pollution begins as early as the end of the 19. century, peaks during the 1970's-1980's and then falls sharply during recent decades. Evolution in lead isotopic abundance shows that Pb inputs to Antarctica reflect a complex blend of contributions originating from the Southern part of South America and Australia. For Cr, Cu, Zn, Ag, Bi and U, concentrations in the snow show significant increases from 1950 to 1980. These enhancements which cannot be explained by variations in natural inputs, illustrate that atmospheric pollution for heavy metals linked with anthropogenic activities in the Southern Hemisphere countries such as for example ferrous and non-ferrous metal mining and smelting is really global. Study of the time period 1920-1990, has allowed us to detail short-term (intra and inter annual) heavy metals concentration's changes. The large short-term variability, observed in Coats Land snow, shows the complex patterns of metal inputs to Antarctica, associated for instance to changes in long-range transport processes from mid-latitude to polar zone and to variability in the different natural sources, such local volcanic activity, sea-salt spray or crustal dust inputs. (author)

  11. Studies of Ti1.5Zr5.5V0.5(MxNi1-x)9.5 (M = Cr, Mn, Fe, Co, Cu, Al): Part 2. Hydrogen storage and electrochemical properties

    In Part 2 of this two part series of papers, the gas phase and electrochemical properties of the quinary alloy Ti1.5Zr5.5V0.5(MxNi1-x)9.5 with M = Cr, Mn, Fe, Co, Cu, or Al and x = 0.1 or 0.2 are studied and compared to the structural properties reported in Part 1. The electrochemical properties of the alloys are strongly related to the non-Laves phases. For example, the Zr7Ni10 phase provides a more catalytic surface and improves the high rate discharge capability of the alloy at the expense of discharge capacity due to the higher Ni to Zr ratio; the Zr9Ni11 phase, on the contrary, improves the discharge capacity but hinders the high rate discharge capability. In the Laves phases, C14 provides a stable hydride with lower equilibrium pressure, higher gas phase storage capacity and lower electrochemical rate capability. The C15 phase provides a less stable hydride with higher equilibrium pressure, lower gas phase storage capacity and higher electrochemical storage capacity. The main effect of each modifying element can be summarized as follows: Mn is the most beneficial substitution element found in this study. Mn increases both the gas phase and electrochemical capacities with good reversibility; it also improves the activation, hydrogen diffusion, surface reaction, and high rate discharge capability. Co increases the degree of disorder in the alloy, reduces both gas phase and electrochemical capacities, destabilizes the hydride, improves activation, and reduces surface reactivity. Fe decreases the gas phase capacity but improves the electrochemical discharge capacity. Fe facilities activation, but its surface reaction is the least active among the substituents used in this study. Al, Cr, and Cu are less desirable because they reduce: (1) the electrochemical and gas phase capacities, (2) the reversibility, and (3) the rate capability. They also slow activation.

  12. Constraints on the timing of Co-Cu ± Au mineralization in the Blackbird district, Idaho, using SHRIMP U-Pb ages of monazite and xenotime plus zircon ages of related Mesoproterozoic orthogneisses and metasedimentary rocks

    Aleinikoff, John N.; Slack, John F.; Lund, Karen; Evans, Karl V.; Fanning, C. Mark; Mazdab, Frank K.; Wooden, Joseph L.; Pillers, Renee M.

    2012-01-01

    The Blackbird district, east-central Idaho, contains the largest known Co reserves in the United States. The origin of strata-hosted Co-Cu ± Au mineralization at Blackbird has been a matter of controversy for decades. In order to differentiate among possible genetic models for the deposits, including various combinations of volcanic, sedimentary, magmatic, and metamorphic processes, we used U-Pb geochronology of xenotime, monazite, and zircon to establish time constraints for ore formation. New age data reported here were obtained using sensitive high resolution ion microprobe (SHRIMP) microanalysis of (1) detrital zircons from a sample of Mesoproterozoic siliciclastic metasedimentary country rock in the Blackbird district, (2) igneous zircons from Mesoproterozoic intrusions, and (3) xenotime and monazite from the Merle and Sunshine prospects at Blackbird. Detrital zircon from metasandstone of the biotite phyllite-schist unit has ages mostly in the range of 1900 to 1600 Ma, plus a few Neoarchean and Paleoproterozoic grains. Age data for the six youngest grains form a coherent group at 1409 ± 10 Ma, regarded as the maximum age of deposition of metasedimentary country rocks of the central structural domain. Igneous zircons from nine samples of megacrystic granite, granite augen gneiss, and granodiorite augen gneiss that crop out north and east of the Blackbird district yield ages between 1383 ± 4 and 1359 ± 7 Ma. Emplacement of the Big Deer Creek megacrystic granite (1377 ± 4 Ma), structurally juxtaposed with host rocks in the Late Cretaceous ca. 5 km north of Blackbird, may have been involved in initial deposition of rare earth elements (REE) minerals and, possibly, sulfides. In situ SHRIMP ages of xenotime and monazite in Co-rich samples from the Merle and Sunshine prospects, plus backscattered electron imagery and SHRIMP analyses of trace elements, indicate a complex sequence of Mesoproterozoic and Cretaceous events. On the basis of textural relationships

  13. Microstructural observation and chemical dating on monazite from the Shilu Group, Hainan Province of South China: Implications for origin and evolution of the Shilu Fe-Co-Cu ore district

    Xu, Deru; Kusiak, Monika A.; Wang, Zhilin; Chen, Huayong; Bakun-Czubarow, Nonna; Wu, Chuanjun; Konečný, Patrik; Hollings, Peter

    2015-02-01

    New monazite chemical U-Th-total-Pb (CHIME) ages, combined with microstructural observations, mineral compositions, and whole-rock geochemistry, indicate that the large-scale, banded iron formation (BIF)-type Shilu Fe-Co-Cu ore district in Hainan Province, South China is a multistage product of sedimentation, metamorphism, and hydrothermal-metasomatic alteration associated with multiple orogenies. Two types of monazite, i.e. "polygenetic" and "metamorphic", were identified. The "polygenetic monazite" comprises a magmatic and/or metamorphic core surrounded by a metamorphic rim, and shows complex zoning. Breakdown corona structure, with a core of monazite surrounded by a mantle of fluorapatite, allanite, and/or epidote as concentric growth rings, is commonly observed. This type of monazite yielded three main CHIME-age peaks at ca. 980 Ma, ca. 880 Ma and ca. 450 Ma. The ages which range up to ca. 880 Ma for detrital cores, record a pre-deformational magmatic and/or metamorphic event(s), and is considered to be the depositional time-interval of the Shilu Group and interbedded BIFs in a marine, back-arc foreland basin likely due to the Grenvillian or South China Sibao orogeny. After deposition, the Shilu district was subjected to an orogenic event, which is recorded by the syndeformational metamorphic monazite with ca. 560-450 Ma population. Probably this event not only caused amphibolite facies metamorphism and associated regional foliation S1 but also enriched the original BIFs, and most likely corresponds to the "Pan-African" and/or the South China Caledonian orogeny. The post-deformational "metamorphic" monazite occurs mostly as inclusions in garnet and shows ca. 260 Ma age. It likely represents the Late Permian post-magmatic hydrothermal and related retrograde event(s) initiated by the Indosinian orogeny due to the closure of the Paleo-Tethys. The breakdown of monazite to secondary coronal mineral phases as well as the Fe-remobilization and associated skarnization

  14. Detrital zircon U-Pb ages of the Proterozoic metaclastic-sedimentary rocks in Hainan Province of South China: New constraints on the depositional time, source area, and tectonic setting of the Shilu Fe-Co-Cu ore district

    Wang, Zhilin; Xu, Deru; Hu, Guocheng; Yu, Liangliang; Wu, Chuanjun; Zhang, Zhaochong; Cai, Jianxin; Shan, Qiang; Hou, Maozhou; Chen, Huayong

    2015-12-01

    The Shilu Fe-Co-Cu ore district, located at Hainan Province of South China, is well known for high-grade hematite-rich Fe ores and also two Precambrian host successions, i.e. the Shilu Group and the overlying Shihuiding Formation. This district has been interpreted as a banded iron formation (BIF) deposit-type, but its depositional time, source area and depositional setting have been in debate due to poor geochronological work. Detrital zircon U-Pb dating aided by cathodoluminescence imaging has been carried out on both the Shilu Group and Shihuiding Formation. Most of the zircon grains from both the successions are subrounded to rounded in morphology and have age spectra between 2000 Ma and 900 Ma with two predominant peaks at ca. 1460-1340 Ma and 1070 Ma, and three subordinate peaks at ca. 1740-1660 Ma, 1220 Ma and 970 Ma. The similar age distribution suggests the same depositional system for both successions. Linked to the geological and paleontological signatures, the Shihuiding Formation is better re-interpreted as the top, i.e. Seventh member of the Shilu Group, rather than a distinct Formation. The youngest statistical zircon age peaks for both successions, i.e. ca. 1070-970 Ma may define the maximum depositional time of the Shilu Group and interbedded BIFs. At least two erosional sources are required for deposition of the studied detrital zircons, with one proximal to provide the least abraded zircons and the other distal or recycled to offer the largely abraded zircons. The predominance of rounded or subrounded zircons over angular zircons probably implies a relatively stable tectonic setting during deposition. Given the Precambrian tectonics of Hainan Island, a retro-arc foreland basin is proposed for the deposition of the Shilu Group and interbedded BIFs. In comparison with those from the South China and other typical Grenvillian orogens, the detrital zircon age populations reveal that Hainan Island had crystalline basement similar to neither the Yangtze

  15. London penetration depth measurements in Ba (Fe1-xTx)2As2(T=Co,Ni,Ru,Rh,Pd,Pt,Co+Cu) superconductors

    Gordon, Ryan T. [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    The London penetration depth has been measured in various doping levels of single crystals of Ba(Fe1-xTx)2As2 (T=Co,Ni,Ru,Rh,Pd,Pt,Co+Cu) superconductors by utilizing a tunnel diode resonator (TDR) apparatus. All in-plane penetration depth measurements exhibit a power law temperature dependence of the form Δλab(T) = CTn, indicating the existence of low-temperature, normal state quasiparticles all the way down to the lowest measured temperature, which was typically 500 mK. Several different doping concentrations from the Ba(Fe1-xTx)2As2 (T=Co,Ni) systems have been measured and the doping dependence of the power law exponent, n, is compared to results from measurements of thermal conductivity and specific heat. In addition, a novel method has been developed to allow for the measurement of the zero temperature value of the in-plane penetration depth, λab(0), by using TDR frequency shifts. By using this technique, the doping dependence of λab(0) has been measured in the Ba(Fe1-xCox)2As2 series, which has allowed also for the construction of the doping-dependent superfluid phase stiffness, ρs(T) = [λ(0)/λ(T)]2. By studying the effects of disorder on these superconductors using heavy ion irradiation, it has been determined that the observed power law temperature dependence likely arises from pair-breaking impurity scattering contributions, which is consistent with the proposed s±-wave symmetry of the superconducting gap in the dirty scattering limit. This hypothesis is supported by the measurement of an exponential temperature dependence of the penetration depth in the intrinsically clean LiFeAs, indicative of a nodeless superconducting gap.

  16. Enhanced photocatalytic H{sub 2}-production activity of Cd{sub x}Zn{sub 1-x}S nanocrystals by surface loading MS (M = Ni, Co, Cu) species

    Wang Jian [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taoyuan South Road 27, Taiyuan 030001 Shanxi (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Li Bo [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Chen Jiazang [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taoyuan South Road 27, Taiyuan 030001 Shanxi (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Li Na; Zheng Jianfeng [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taoyuan South Road 27, Taiyuan 030001 Shanxi (China); Zhao Jianghong, E-mail: zjh_sx@sxicc.ac.cn [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taoyuan South Road 27, Taiyuan 030001 Shanxi (China); Zhu Zhenping, E-mail: zpzhu@sxicc.ac.cn [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taoyuan South Road 27, Taiyuan 030001 Shanxi (China)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Cd{sub x}Zn{sub 1-x}S solid solution was prepared by co precipitation reflux method. Black-Right-Pointing-Pointer MS (M = Ni, Co, Cu) provides active sites for Cd{sub x}Zn{sub 1-x}S hydrogen evolution. Black-Right-Pointing-Pointer The hydrogen production rate of MS/Cd{sub 0.4}Zn{sub 0.6}S is 5 times higher than Cd{sub 0.4}Zn{sub 0.6}S. Black-Right-Pointing-Pointer MS causes fast diffusion of photoelectrons generated from Cd{sub 0.4}Zn{sub 0.6}S toward MS. - Abstract: To investigate the role of metal sulfides as co-catalyst for photocatalytic hydrogen production under visible light irradiation, we have loaded small amounts of transition-metal sulfides (MS), such as NiS, CoS and CuS, onto the surface of Cd{sub x}Zn{sub 1-x}S solid solution. It can be found that the rate of H{sub 2} evolution over the MS/Cd{sub 0.4}Zn{sub 0.6}S was 5 times higher than that of the pure Cd{sub 0.4}Zn{sub 0.6}S, and is comparable to the Cd{sub 0.4}Zn{sub 0.6}S modified with 1 wt% platinum (Pt) co-catalysts. The MS/Cd{sub 0.4}Zn{sub 0.6}S photocatalysts were characterized by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), UV-visible spectrophotometer (UV-vis), and photoluminescence (PL) spectroscopy. It can be speculated that the MS provided active sites for H{sub 2} production and caused the migration of excited electrons from Cd{sub 0.4}Zn{sub 0.6}S toward MS, leading to the enhancement of photocatalytic activity.

  17. Interfacial properties of immiscible Co-Cu alloys

    Egry, I.; Ratke, L.; Kolbe, M.;

    2010-01-01

    Using electromagnetic levitation under microgravity conditions, the interfacial properties of an Cu75Co25 alloy have been investigated in the liquid phase. This alloy exhibits a metastable liquid miscibility gap and can be prepared and levitated in a configuration consisting of a liquid cobalt-ri...... experiment carried out on board the TEXUS 44 sounding rocket....

  18. Hydrostatic pressure experiments with granular Co-Cu alloys

    Lachowicz, H. K.; Závěta, Karel

    2002-01-01

    Roč. 335, - (2002), s. 9-15. ISSN 0925-8388 R&D Projects: GA ČR GA202/01/0780 Grant ostatní: ICA1-CT-2000(XX) 70018PAS Institutional research plan: CEZ:AV0Z1010914 Keywords : nanostructured materials * transition metal alloys * rapid solidification * magnetic measurements * high pressure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.014, year: 2002

  19. Thermodynamic properties and phase transitions of ternary Co-Cu-Si alloys with equiatomic Co/Cu ratio

    Zhai, Wei; Hu, Liang; Zhou, Kai; Wei, Bingbo

    2016-04-01

    Different amounts of Si element were introduced into binary Co50Cu50 alloy to investigate the thermodynamic properties and phase transitions of ternary Co50-x/2Cu50-x/2Si x (x  =  10, 20, 30, 40 and 50 at%) alloys. Their liquidus and solidus temperatures versus Si content were determined by the differential scanning calorimetry (DSC) method. It was found that the addition of Si element depressed both the liquidus and solidus temperatures as compared with binary Co50Cu50 alloy. In particular, the additions of 10 and 20 at% Si remarkably reduced the critical undercooling for liquid demixing to only 3 and 1 K, whereas no liquid phase separation took place in other Co50-x/2Cu50-x/2Si x alloys. The relationship between the enthalpy of fusion and alloy composition was also established by a polynomial function on the basis of the measured data. The solidification microstructures of the DSC samples were investigated corresponding to the calorimetric signals, based on which the solidification pathway for each Co50-x/2Cu50-x/2Si x alloy was elucidated. The Si element displays stronger affinity with the Co element than the Cu element. As Si content rises, the pseudobinary eutectic (Co  +  Co2Si), (Co2Si  +  CoSi), (CoSi  +  CoSi2) and (Cu3Si  +  Si) structures were successively formed, and there were no ternary intermetallic compounds in these alloys. The thermal diffusivity of solid ternary Co50-x/2Cu50-x/2Si x alloys was determined by a laser flash method in a wide temperature range from 300 to 1180 K, which showed a decreasing tendency with the increase of Si content.

  20. Atomic level mixing induced by Kr irradiation of FeCo/Cu multilayers

    The effects of Kr ion irradiation of FexCo1-x/Cu multilayers are investigated by means of magnetic and x-ray measurements. The irradiation was performed at room temperature with 600 keV of Kr, and the fluences were ranged from 1x1015 to 5x1015 ions/cm2. X-ray diffraction patterns show that the irradiation was able to produce a significant grain growth and, at the same time, it triggered a strain release. The x-ray absorption measurements around Fe K edge have shown that the FeCo environment changed from bcc, for the as-deposited multilayer, to fcc after appropriate fluence, depending on the Cu thickness and on the Fe/Co content. For 50 A of Cu, the phase transformation occurs even for the lowest fluence, regardless the Fe/Co concentration. For 25 A of Cu, it depends on the Fe/Co concentration. After irradiation, the saturation magnetization suffers a strong decrease, especially for 50 A of Cu. The temperature for the onset of irreversibility also decreases with irradiation, again being the effect stronger for 50 A of Cu. These data indicate that Kr irradiation induced mixing between Cu and FeCo, even though Cu is immiscible with Fe and Co in the equilibrium state

  1. Multisegmented FeCo/Cu nanowires: electrosynthesis, characterization, and magnetic control of biomolecule desorption

    Özkale, B.; Shamsudhin, N.; Chatzipirpiridis, G.; Hoop, M.; Gramm, F.; Chen, Y.; Martí, Xavier; Sort, J.; Pellicer, E.; Pané, S.

    2015-01-01

    Roč. 7, č. 13 (2015), s. 7389-7396. ISSN 1944-8244 Institutional support: RVO:68378271 Keywords : multisegmented nanowires * template-assisted electrodeposition * tunable magnetic properties * magnetically triggered release Subject RIV: BE - Theoretical Physics Impact factor: 6.723, year: 2014

  2. Structural and magnetic study of LaBaCoCuO5+δ

    The structure and magnetic properties of the compound LaBaCuCoO5+δ have been studied for the non-stoichiometric oxygen concentration δ≅0.6. The structure is pseudo-cubic with a tripled perovskite unit cell. The crystal structure was determined by a combined Rietveld fit to neutron and synchrotron x-ray powder diffraction data in the orthorhombic Pmmm space group, with cell parameters a=3.9223(3) A, b=3.9360(3) A, c=11.7073(8) A, and V=180.74(2) A3 (room temperature). Antiferromagnetic ordering of Cu and Co magnetic moments is observed below 205(4) K. The magnetic structure with cell aM=2a, bM=2b, and cM=2c, could be described with the Shubnikov space group Fmmm'. The magnetic moments of both equivalent Cu/Co sites were determined at 50 and 170 K to be 0.83(3)μB and 0.58(3)μB, respectively, consistent with one unpaired electron per atom. The fit of the intensities to a simple mean field magnetic model appeared to be insufficient to account for the variation of moments at temperatures close to TN while a three dimensional Heisenberg model could improve the fit. Susceptibility measurements between 4 and 350 K also show irreversibility below 150 K. The local environments of Cu and Co were studied by extended x-ray absorption fine structure spectroscopy at both absorption edges. Cu atoms adopt an elongated octahedral or square-based pyramidal oxygen environment which suggests mainly the presence of Cu(II) in the structure. Co adopts different local environments, depending on the electronic and spin states

  3. High coercivity and giant magnetoresistance of CoAg, CoCu granular films

    We report our study on the structure, magnetic and giant magnetoresistance properties of two systems: Co x Ag1-x (x=33, 48, 49, 52 at%) and Co y Cu1-y (y=11, 13, 15, 17 at%) granular films prepared by RF sputtering. The thermal transition measured by the SDT 2960 apparatus revealed exothermal peaks at 400 deg. C, corresponding to the crystallization of FCC-Co crystallites. The studied films were annealed in a temperature range of 300-450 deg. C for 1 h. The structure and particle size were determined from the X-ray diffraction data. Superparamagnetic state was shown in as-deposited films. After appropriate heat treatment, coercivity increased up to 1100 Oe in the Co52Ag48 film annealed at 350 deg. C, and 690 Oe in the Co13Cu87 film annealed at 400 deg. C. Maximum magnetoresistance up to 4.25% in the Co48Ag52 film, and 5.4% in the Co15Cu85 film annealed at 400 deg. C was obtained. Our values for magnetoresistance are quite high compared with recent studies

  4. Reverse depth profiling of electrodeposited Co/Cu multilayers by SNMS

    Csik, A.; Vad, K.; Langer, G A; Katona, G. L.; Toth-Kadar, E.; Peter, L

    2009-01-01

    The overall quality of multilayer thin films prepared by electrodeposition is strongly influenced by the surface and interface roughness which increases with the layer number. For that very reason the reliable analysis of the first few layers can be necessary. However, in depth profiling methods based on sputtering techniques the first layer is always found at the bottom of the sputtered crater. Since the depth resolution decreases during sputtering, the analysis of the first few layers are d...

  5. Metastable phase separation and rapid solidification of undercooled Co-Cu alloy under different conditions

    Cao Chong-De

    2006-01-01

    The metastable liquid phase separation and rapid solidification behaviours of Co61.8Cu38.2 alloy were investigated by using differential thermal analysis (DTA) in combination with glass fluxing,electromagnetic levitation (EML) and drop tube techniques.It is found that the liquid phase separation process and the solidification microstructures intensively depend on the experimental processing parameters,such as undercooling level,cooling rate,gravity level,liquid surface tension and the wetting state of crucible.Large undercooling and surface tension difference of the two liquids tend to facilitate further separation and cause severe macrosegregation.On the other hand,rapid cooling and low gravity effectively suppress the coalescence of the minority phase.Severe macrosegregation patterns are formed in the bulk samples processed by both DTA and EML.In contrast,disperse structures with fine spherical Cu-rich spheres homogeneously distributed in the matrix of Co-rich phase have been obtained in drop tube.

  6. Structure of Sm-Co-Cu-Fe-Zr alloys for permanent magnets

    Linetskij, Ya.L.; Savich, A.N.; Knizhnik, E.G.; Menushenkova, N.V.; Polunin, V.V.; Korovyatskaya, M.V. (Moskovskij Inst. Stali i Splavov (USSR))

    1982-02-01

    Structure changes in the 25 Sm - 50 Co - (10-15) Fe - (8-12) Cu - 2 Zr alloys during their processing for the state with high magnetic properties are investigated by means of optical, electron microscopy and X-ray diffraction analysis. Dendrite non-uniformity is removed during the alloy sintering and the Th/sub 2/Zn/sub 17/ type phase turns to be the basic structural constituent. Tempering at 800 deg C results in transformation of solid solution in the result of which canted cellular and banded structures are formed.

  7. Spin momentum transfer effects observed in electrodeposited Co/Cu/Co nanowires

    Blon, T.; Mátéfi-Tempfli, Mária; Piraux, L.;

    2007-01-01

    reversals are driven by a spin-polarized current. The critical current densities needed for the magnetization reversals are in the 107 A/ cm2 range and the dependence of the critical currents with the applied field is consistent with the spin-transfer mechanism. For large applied magnetic fields, the...... of single nanowires at room temperature. For small applied magnetic fields, we have measured resistance changes above a critical direct-current (dc) injected current that corresponds to the change in resistance observed in the magnetoresistance curves at low current. We conclude that magnetic...... differential resistance exhibits some peaks that we attribute to the onset of high-frequency excitations of the free-layer magnetization. According to the high density of electrodeposited nanowires in alumina templates, our results are promising for synchronized spin-transfer oscillators. © 2007 American...

  8. Optimisation of 2/17 permanent magnets using the quinary Sm-Co-Cu-Fe-Zr phase diagram

    The combination of high magnetisation and high Curie temperature of the Sm2Co17 type magnets makes them attractive for a number of applications requiring high-energy products and long term stability for continuous operating up to 300 C. In order to optimise the elaboration process, it was necessary to investigate phase equilibria in the Sm-Co-Zr-Cu-Fe system. The presented part of the work concerns two regions of interest near 1150 C and 850 C. A specific method is proposed to represent the diagram where a two dimension projection of the different domains is coupled with a three dimensional one. This representation appears as a tool to understand the metallurgical process and to obtain better reproducibility of the alloys magnetic properties. Then an optimisation could be made. Magnetic behaviour of alloys is discussed. (orig.)

  9. Factors that Influence the Price of Al, Cd, Co, Cu, Fe, Ni, Pb, Rare Earth Elements, and Zn

    Papp, John F.; Bray, E. Lee; Edelstein, Daniel L.; Fenton, Michael D.; Guberman, David E.; Hedrick, James B.; Jorgenson, John D.; Kuck, Peter H.; Shedd, Kim B.; Tolcin, Amy C.

    2008-01-01

    This report is based on a presentation delivered at The 12th International Battery Materials Recycling Seminar, March 17-20, 2008, Fort Lauderdale, Fla., about the factors that influence prices for aluminum, cadmium, cobalt, copper, iron, lead, nickel, rare earth elements, and zinc. These are a diverse group of metals that are of interest to the battery recycling industry. Because the U.S. Geological Survey (USGS) closely monitors, yet neither buys nor sells, metal commodities, it is an unbiased source of metal price information and analysis. The authors used information about these and other metals collected and published by the USGS (U.S. production, trade, stocks, and prices and world production) and internationally (consumption and stocks by country) from industry organizations, because metal markets are influenced by activities and events over the entire globe. Long-term prices in this report, represented by unit values, were adjusted to 1998 constant dollars to remove the effects of inflation. A previous USGS study in this subject area was 'Economic Drivers of Mineral Supply' by Lorie A. Wagner, Daniel E. Sullivan, and John L. Sznopek (USGS Open File Report 02-335). By seeking a common cause for common behavior of prices among the various metal commodities, the authors found that major factors that influence prices of metal commodities were international events such as wars and recessions, and national events such as the dissolution of the Soviet Union in 1991 and economic growth in China, which started its open door policy in the 1970s but did not have significant market impact until the 1990s. Metal commodity prices also responded to commodity-specific events such as tariff or usage changes or mine strikes. It is shown that the prices of aluminum, cadmium, copper, iron, lead, nickel, and zinc are at historic highs, that world stocks are at (or near) historic lows, and that China's consumption of these metals had increased substantially, making it the world's leading consumer of these metals.

  10. Relation between martensitic transformation temperature range and lattice distortion ratio of NiMnGaCoCu Heusler alloys

    In order to study the relation between martensitic transformation temperature range ΔT (where ΔT is the difference between martensitic transformation start and finish temperature) and lattice distortion ratio (c/a) of martensitic transformation, a series of Ni46Mn28−xGa22Co4Cux (x = 2–5) Heusler alloys is prepared by arc melting method. The vibration sample magnetometer (VSM) experiment results show that ΔT increases when x > 4 and decreases when x < 4 with x increasing, and the minimal ΔT (about 1 K) is found at x = 4. Ambient X-ray diffraction (XRD) results show that ΔT is proportional to c/a for non-modulated Ni46Mn28−xGa22Co4Cux (x = 2–5) martensites. The relation between ΔT and c/a is in agreement with the analysis result obtained from crystal lattice mismatch model. About 1000-ppm strain is found for the sample at x = 4 when heating temperature increases from 323 K to 324 K. These properties, which allow a modulation of ΔT and temperature-induced strain during martensitic transformation, suggest Ni46Mn24Ga22Co4Cu4 can be a promising actuator and sensor. (interdisciplinary physics and related areas of science and technology)

  11. A Facile Synthesis of MPd (M=Co, Cu) Nanoparticles and Their Catalysis for Formic Acid Oxidation

    Mazumder, Vismadeb [Brown University; Chi, Miaofang [ORNL; Mankin, Max [Brown University; Liu, Yi [Brown University; Metin, Onder [Ataturk University; Sun, Daohua [Xiamen University, China; More, Karren Leslie [ORNL; Sun, Shouheng [Brown University

    2012-01-01

    Monodisperse CoPd nanoparticles (NPs) were synthesized and studied for catalytic formic acid (HCOOH) oxidation (FAO). The NPs were prepared by coreduction of Co(acac)2 (acac = acetylacetonate) and PdBr2 at 260 C in oleylamine and trioctylphosphine, and their sizes (5-12 nm) and compositions (Co10Pd90 to Co60Pd40) were controlled by heating ramp rate, metal salt concentration, or metal molar ratios. The 8 nm CoPd NPs were activated for HCOOH oxidation by a simple ethanol wash. In 0.1 M HClO4 and 2 M HCOOH solution, their catalytic activities followed the trend of Co50Pd50 > Co60Pd40 > Co10Pd90 > Pd. The Co50Pd50 NPs had an oxidation peak at 0.4 V with a peak current density of 774 A/gPd. As a comparison, commercial Pd catalysts showed an oxidation peak at 0.75 V with peak current density of only 254 A/gPd. The synthesis procedure could also be extended to prepare CuPd NPs when Co(acac)2 was replaced by Cu(ac)2 (ac = acetate) in an otherwise identical condition. The CuPd NPs were less active catalysts than CoPd or even Pd for FAO in HClO4 solution. The synthesis provides a general approach to Pd-based bimetallic NPs and will enable further investigation of Pd-based alloy NPs for electro-oxidation and other catalytic reactions.

  12. Assessing comparative terrestrial ecotoxicity of Cd, Co, Cu, Ni, Pb, and Zn: The influence of aging and emission source

    Owsianiak, Mikolaj; Holm, Peter E.; Fantke, Peter; Christiansen, Karen S.; Borggaard, Ole K.; Hauschild, Michael Zwicky

    2015-01-01

    influence of aging time on the reactivity of metals from anthropogenic sources in soils. Thus, for calculating comparative toxicity potentials of man-made metal contaminations in soils, we recommend using time-horizon independent accessibility factors derived from source-specific reactive fractions....

  13. Photocatalytic production of hydrogen over pure and TM (Fe, Co, Cu, Ni, and Zn)-Wo/sub 3/ composites

    Photocatalysis is a promising approach for the production of hydrogen from water and sunlight. In this article H/sub 2/ production via photocatalytic water splitting process over pure WO/sub 3/ and a series of surface modified transition metal oxide-WO/sub 3/ composites, using a 355 nm laser as light source, has been discussed. Various analytical techniques such as UV/visible spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning Electron Microscopy (SEM) were used to characterize the pure and synthesized doped powders. The effect of electron scavengers such as Ag+ and Fe/sub 3/+ in suppressing the e-h+ recombination process, for the pure WO/sub 3/, was also examined. In-situ measurement of pH changes during the photocatalytic water splitting (PWS) process was found useful in explaining and correlating the effect on product yield. For composite photocatalysts various charge transfer processes, Involved during the process, were also estimated. (author)

  14. Investigation into phase composition and fine structure of type Sm(Co, Cu, Fe, Zr)sub(7. 4) magnets

    Reznichenko, K.N.; Savich, A.N.; Samartseva, G.P.; Andreeva, A.V.

    The structure and phase composition of the sintered Sm(Cosub(0.67)Fesub(0.21)Cusub(0.10)Zrsub(.0.013))sub(7.4) alloy after homogenization (at 1180 and 1190 deg C) and ageing (at 800-400 deg C) are studied by the methods of microstructural, electronoscopic, X-ray and microsound analyses. It is stated that phase precipitations along the grain boundaries belong in both cases to the 2:17 type compound with the composition slightly differing from the matrix. Cellular decomposition having coarse nature in the homogenized and more fine - in the aged state is observed in the alloy structure.

  15. Low-dimensional multiplexing: the magneto-optical Kerr effect in an individual FeCoCu nanowire

    Torres-Torres, C.

    2016-01-01

    Due to their selective and fascinating effects, metallic nanoparticles have become a very significant topic for science. A modification in morphology and structure of low-dimensional materials can result in extraordinary ultrafast physical phenomena. New findings related to electronic, optical and magnetic processes have emerged from surface plasmon resonance excitations in nanoparticles. Moreover, multi-functional systems can be obtained from the integration of different elements in a nanostructured configuration. Recently, Palmero et al (2015 Nanotechnology 26 461001) have reported magneto-optical Kerr effect explorations in individual FeCuCo nanowires; the influence of tailored morphologies exhibited by particular samples was analyzed. An important magnetization reversal action was revealed and it was concluded that the demagnetization may be responsible for vortex domain wall propagation. The report can provide a solid base for future research and immediate applications in modern spintronics or magnetic data storage can be contemplated.

  16. Electrical resistivity of YbRh2Si2 and EuT2Ge2 (T=Co,Cu) at extreme conditions of pressure and temperature

    This investigation addresses the effect that pressure, p, and temperature, T, have on 4f states of the rare-earth elements in the isostructural YbRh2Si2, EuCo2Ge2, and EuCu2Ge2 compounds. Upon applying pressure the volume of the unit cell reduces, enforcing either the enhancement of the hybridization of the 4f localized electrons with the ligand or a change in the valence state of the rare-earth ions. Here, we probe the effect of a pressure-induced lattice contraction on these system by means of electrical-resistivity measurements, ρ(T), from room temperature down to 100 mK. (orig.)

  17. Half-lives and branchings for {\\beta}-delayed neutron emission for neutron-rich Co-Cu isotopes in the r-process

    Hosmer, P; Aprahamian, A; Arndt, O; Clement, R R C; Estrade, A; Farouqi, K; Kratz, K -L; Liddick, S N; Lisetskiy, A F; Mantica, P F; Möller, P; Mueller, W F; Montes, F; Morton, A C; Ouellette, M; Pellegrini, E; Pereira, J; Pfeiffer, B; Reeder, P; Santi, P; Steiner, M; Stolz, A; Tomlin, B E; Walters, W B; Wöhr, A; 10.1103/PhysRevC.82.025806

    2010-01-01

    The {\\beta} decays of very neutron-rich nuclides in the Co-Zn region were studied experimentally at the National Superconducting Cyclotron Laboratory using the NSCL {\\beta}-counting station in conjunction with the neutron detector NERO. We measured the branchings for {\\beta}-delayed neutron emission (Pn values) for 74Co (18 +/- 15%) and 75-77Ni (10 +/- 2.8%, 14 +/- 3.6%, and 30 +/- 24%, respectively) for the first time, and remeasured the Pn values of 77-79Cu, 79,81Zn, and 82Ga. For 77-79Cu and for 81Zn we obtain significantly larger Pn values compared to previous work. While the new half-lives for the Ni isotopes from this experiment had been reported before, we present here in addition the first half-life measurements of 75Co (30 +/- 11 ms) and 80Cu (170+110 -50 ms). Our results are compared with theoretical predictions, and their impact on various types of models for the astrophysical rapid neutron-capture process (r-process) is explored. We find that with our new data, the classical r-process model is bet...

  18. Thermal Analysis and Flame-Retarded Mechanism of Composites Composed of Ethylene Vinyl Acetate and Layered Double Hydroxides Containing Transition Metals (Mn, Co, Cu, Zn

    Lili Wang

    2016-05-01

    Full Text Available The effects of transition metals on the hydrophobicity of nano–structured layered double hydroxides (LDHs and the compatibility of LDHs/ethylene vinyl acetate (EVA composites have seldom been reported. NiMgAl–LDHs slightly surface–modified with stearate and doped with transition metal cations (Mn2+, Co2+, Cu2+, Zn2+ are investigated. Compared to the pure EVA, not only were the maximal degradation–rate temperatures (Tmax of the ethylene–based chains enhanced, but also the smoke production rate (SPR and the production rate of CO (COP were sharply decreased for all the composites. Most importantly, a new flame retardant mechanism was found, namely the peak heat release rate (pk-HRR time, which directly depends on the peak production rate of CO2 (pk-CO2 time for EVA and all composites by cone calorimeter test. Moreover, the Mn–doped LDH S–NiMgAl–Mn shows more uniform dispersion and better interfacial compatibility in the EVA matrix. The cone calorimetric residue of S–NiMgAl–Mn/EVA has the intumescent char layer and the compact metal oxide layer. Therefore, S–NiMgAl–Mn/EVA shows the lowest pk-HRR and the longest pk-HRR time among all the composites.

  19. Hydrogen decrepitation as a method of powder preparation of a 2:17-type, Sm(Co, Cu, Fe, Zr)sub(8.92) magnetic alloy

    The present work has shown that hydrogen decrepitation of a 2:17-type Sm(Cosub(0.673)Cusub(0.080)Fesub(0.222)Zrsub(0.025))sub(8.92) alloy is a very rapid and convenient means of producing powdered material for the production of polymer-bonded permanent magnets. The magnets made from the hydrogen decrepitated powder (average particle size approx. 100 μm) exhibited improved demagnetization loop shapes, higher intrinsic coercivities and improved elevated temperature stability when compared with the magnets produced from the standard milled powder material (average particle size approx. 40 μm). These differences in properties have been related to the differences in the character of the powders produced by the two methods of decrepitation. (author)

  20. Influence of alloying effect on X-ray fluorescence parameters of Co and Cu in CoCuAg alloy films

    Aylikci, Nuray Kup; Tiraşoğlu, Engin; Apaydin, Gökhan; Cengiz, Erhan; Aylikci, Volkan; Bakkaloğlu, Ömer Faruk

    2009-06-01

    In this study, K β/K α X-ray intensity ratios, σ, σ production cross-sections and ωK fluorescence yields of Co and Cu and L β/L α X-ray intensity ratios, σ, σ production cross-sections and ϖ average fluorescence yields of Ag in pure metals and in different alloy compositions were measured. In this study, alloying effects on the σ production cross-sections of Co and Cu were investigated and changes interpreted according to the rearrangement of valance state electrons and the charge transfer process between the 3d elements (Co and Cu) and Ag.

  1. Ferromagnetic mechanism of (Co, Cu)-codoped ZnO films with different Co concentrations investigated by X-ray photoelectron spectroscopy

    Yuan, Huan; Du, Xiaosong; Xu, Ming

    2016-05-01

    Cobalt/copper-codoped ZnO nanoparticles, synthesized with different Co concentrations by a sol-gel method using ethanol as solvent, were studied via XPS. Hexagonal wurtzite structure was found in all samples, with no evidence of any secondary phase. The average crystallite size of the samples was around 20-30 nm, altered significantly with increasing Co concentration. Copper ions and Cobalt ions are indeed substituted into the ZnO lattice at the Zn2+ site, as shown by XRD and XPS. Further studies showed dramatic changes of Cu valence from +2 to +1 as the Co concentration level exceeds 1%, accompanied by a blue-shift of the optical bandgap from 3.01 to 3.13 eV. Ferromagnetism of the Co-doped Zn0.95Cu0.05O thin films was observed and found to be tunable - a phenomenon associated with the valence state of the Cu ions and the existence of some defects like oxygen vacancies in the films.

  2. Determination of Trace Metals (Co, Cu, Cd, Pb, Fe, Ni and Mn in Selected Sweets of Different Shops of Karachi City by Atomic Absorption Spectroscopy

    M. Akhyar Farrukh

    2004-01-01

    Full Text Available The study presented was concerned with the determination of level of iron, nickel, cobalt, copper, lead, manganese and cadmium in different sweets (Gulab Jamun, White Chum Chum, Colored Chum Chum, Khopre ki Mithai, Qalaqand, Bhashani Chum Chum, Basin ka Lado and Patesa collected from selected shops of Karachi city. Concentration of selected trace metals were estimated using atomic absorption spectrometer. Results obtained from study show high concentration of iron and manganese in all the sweets. High concentration of iron may be due to the cooking utensils rich of iron. Use of manganese in alloys may be responsible of such high concentration of manganese in sweets. Metal load in sweets of all shops seem in the limits offered by RDA for respective metals. All food colors used in making sweets are permitted food colors, because sweets show no abnormal metal load.

  3. Concentration- and thickness-dependent magnetic properties of NixMn100−x in epitaxially grown NixMn100−x/Ni/(Co/)Cu3Au(001)

    Magnetic proximity effects in single-crystalline NixMn100−x/Ni(/Co) bilayers on Cu3Au(001) are investigated for in-plane (IP) and out-of-plane (OoP) magnetization by means of the longitudinal and polar magneto-optical Kerr effect. Attention is paid to the influence on concentration- and thickness-dependent antiferromagnetic ordering (TAFM) and blocking (Tb) temperatures as well as the exchange bias field (Heb). For all the NixMn100−x films under study in contact with IP Ni, increasing TAFM is observed with decreasing Ni concentration from ∼50 to ∼20%, whereas only a slight change in TAFM is observed for the OoP case. Between ∼28% and ∼35% Ni concentration, a crossover temperature exists below which TAFM for the IP samples is higher than for the OoP samples and vice versa. Tb is higher for the IP case than for OoP, except for an equi-atomic NiMn film, while Heb increases significantly for both magnetization directions with decreasing x. These results are attributed to: (i) a rotation of the non-collinear 3Q-like spin structure of NixMn100−x from the more-OoP to the more-IP direction for decreasing Ni concentration x, along with an associated increased magnetic anisotropy, and (ii) a smaller domain wall width within the NixMn100−x films at smaller x, leading to a smaller thickness required to establish exchange bias at a fixed temperature. (paper)

  4. Electrical resistivity of YbRh{sub 2}Si{sub 2} and EuT{sub 2}Ge{sub 2} (T=Co,Cu) at extreme conditions of pressure and temperature

    Dionicio, G.A.

    2006-07-01

    This investigation addresses the effect that pressure, p, and temperature, T, have on 4f states of the rare-earth elements in the isostructural YbRh{sub 2}Si{sub 2}, EuCo{sub 2}Ge{sub 2}, and EuCu{sub 2}Ge{sub 2} compounds. Upon applying pressure the volume of the unit cell reduces, enforcing either the enhancement of the hybridization of the 4f localized electrons with the ligand or a change in the valence state of the rare-earth ions. Here, we probe the effect of a pressure-induced lattice contraction on these system by means of electrical-resistivity measurements, {rho}(T), from room temperature down to 100 mK. (orig.)

  5. Structural/magnetic phase transitions and superconductivity in Ba(Fe1-xTMx)2As2 (TM=Co, Ni, Cu, Co/Cu, Rh and Pd) single crystals

    Ni, Ni

    2009-08-15

    Since its discovery in 1911, superconductivity has been one of the most actively studied fields in condensed matter physics and has attracted immense experimental and theoretical effort. At this point in time, with more and more superconductors discovered in elements, alloys, intermetallic compounds and oxides, it is becoming clear that superconductivity is actually not so rare in nature. Almost half of the elements in the periodic table and hundreds of compounds have been found to be superconducting. Fig. 1.1 shows the milestones in discovering higher T{sub c} superconductors. Among the elemental superconductors, Niobium has the highest superconducting transition temperature, T{sub c}, of 9.5 K. This record held for more than ten years, until the discovery of niobium nitride which superconducts below 16 K. It took another thirty years for T{sub c} to increase from 16 K in niobium nitride to 23 K in niobium germanium.

  6. Structural/magnetic phase transitions and superconductivity in Ba(Fe1-xTMx)2As2 (TM = Co, Ni, Cu, Co / Cu, Rh and Pd) single crystals

    Since its discovery in 1911, superconductivity has been one of the most actively studied fields in condensed matter physics and has attracted immense experimental and theoretical effort. At this point in time, with more and more superconductors discovered in elements, alloys, intermetallic compounds and oxides, it is becoming clear that superconductivity is actually not so rare in nature. Almost half of the elements in the periodic table and hundreds of compounds have been found to be superconducting. Fig. 1.1 shows the milestones in discovering higher Tc superconductors. Among the elemental superconductors, Niobium has the highest superconducting transition temperature, Tc, of 9.5 K. This record held for more than ten years, until the discovery of niobium nitride which superconducts below 16 K. It took another thirty years for Tc to increase from 16 K in niobium nitride to 23 K in niobium germanium.

  7. Theoretical electron scattering amplitudes and spin polarizations. Electron energies 100 to 1500 eV Part II. Be, N, O, Al, Cl, V, Co, Cu, As, Nb, Ag, Sn, Sb, I, and Ta targets

    Wildhaber, M. L.; Wikle, C. K.; Anderson, C. J.; Franz, K. J.; Moran, E. H.; Dey, R.

    2012-12-01

    Recent decades have brought substantive changes in land use and climate across the earth, prompting a need to think of population and community ecology not as a static entity, but as a dynamic process. Increasingly there is evidence of ecological changes due to climate change. Although much of this evidence comes from ground-truth observations of biogeographic data, there is increasing reliance on models that relate climate variables to biological systems. Such models can then be used to explore potential changes to population and community level ecological systems in response to climate scenarios as obtained from global climate models (GCMs). A key issue associated with modeling ecosystem response to climate is GCM downscaling to regional and local ecological/biological response models that can be used in vulnerability and risk assessments of the potential effects of climate change. The need is for an explicit means for scaling results up or down multiple hierarchical levels and an effective assessment of the level of uncertainty surrounding current knowledge, data, and data collection methods with these goals identified as in need of acceleration in the U.S. Climate Change Science Program FY2009 Implementation Priorities. In the end, such work should provide the information needed to develop adaptation and mitigation methodologies to minimize the effects of directional and nonlinear climate change on the Nation's land, water, ecosystems, and biological populations. We are working to develop an approach that includes multi-scale and hierarchical Bayesian modeling of Missouri River sturgeon population dynamics. Statistical linkages are defined to quantify implications of climate on fish populations of the Missouri River ecosystem. This approach is a hybrid between physical (deterministic) downscaling and statistical downscaling, recognizing that there is uncertainty in both. The model must include linkages between climate and habitat, and between habitat and population. A key advantage of the hierarchical approach used in this study is that it incorporates various sources of observations and includes established scientific knowledge, and associated uncertainties. The goal is to evaluate the potential distributional changes in an ecological system, given distributional changes implied by a series of linked climate and system models under various emissions/use scenarios. The predictive modeling system being developed will be a powerful tool for evaluating management options for coping with global change consequences and assessing uncertainty of those evaluations. Specifically for the endangered pallid sturgeon (Scaphirhynchus albus), we are already able to assess potential effects of any climate scenario on growth and population size distribution. Future models will incorporate survival and reproduction. Ultimately, these models provide guidance for successful recovery and conservation of the pallid sturgeon. Here we present a basic outline of the approach we are developing and a simple pallid sturgeon example to demonstrate how multiple scales and parameter uncertainty are incorporated.

  8. Structural/magnetic phase transitions and superconductivity in Ba(Fe1-xTMx)2As2 (TM=Co, Ni, Cu, Co/Cu, Rh and Pd) single crystals

    Ni, Ni [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    Since its discovery in 1911, superconductivity has been one of the most actively studied fields in condensed matter physics and has attracted immense experimental and theoretical effort. At this point in time, with more and more superconductors discovered in elements, alloys, intermetallic compounds and oxides, it is becoming clear that superconductivity is actually not so rare in nature. Almost half of the elements in the periodic table and hundreds of compounds have been found to be superconducting. Fig. 1.1 shows the milestones in discovering higher Tc superconductors. Among the elemental superconductors, Niobium has the highest superconducting transition temperature, Tc, of 9.5 K. This record held for more than ten years, until the discovery of niobium nitride which superconducts below 16 K. It took another thirty years for Tc to increase from 16 K in niobium nitride to 23 K in niobium germanium.

  9. Self-encapsulation of [MII(phen)2(H2O)2]2+ (M=Co, Zn) in one-dimensional nanochannels of [MII(H2O)6(BTC)2]4- (M=Co, Cu, Mn): a high HQ/CAT ratio catalyst for hydroxylation of phenols.

    Bi, Jianhong; Kong, Lingtao; Huang, Zixiang; Liu, Jinhuai

    2008-06-01

    Four novel three-dimensional (3D) microporous supramolecular compounds containing nanosized channels, namely, [Co(phen)2(H2O)2]2[Co(H2O)6].2BTC.21.5H2O (1), [Co(phen)2(H2O)2]2[Cu(H2O)6].2BTC.21.5H2O (2), [Co(phen)2(H2O)2]2[Mn(H2O)6].2BTC.18H2O (3), and [Zn(phen)2(H2O)2]2[Mn(H2O)6].2BTC.22.5H2O (4), were synthesized from 1,3,5-benzenetricarboxylate (BTC), 1,10-phenanthroline (phen), and the transition-metal salt(s) by self-assembly. Single-crystal X-ray structural analysis showed that the resulting 3D microporous supramolecular frameworks consist of a two-dimensional (2D) hydrogen-bonded host framework of [MII(H2O)6(BTC)2]4- (M=Co for 1, Cu for 2, Mn for 3, 4) with rectangular-shaped cavities containing [MII(phen)2(H2O)2]2+ (M=Co for 1-3, Zn for 4) guests. The guest complex is encapsulated in the 2D hydrogen-bonded host framework by hydrogen bonding and aromatic pi-pi stacking interactions, forming the 3D hydrogen-bonded framework. The catalytic activities of 1, 2, 3, and 4 were studied using hydroxylation of phenols with 30% aqueous H2O2 as a test reaction. The compounds displayed a good phenol conversion ratio and excellent channel selectivity in the hydroxylation reaction, with a maximum hydroquinone (HQ)/catechol (CAT) ratio of 3.9. PMID:18439004

  10. Controllable irregular melting induced by atomic segregation in bimetallic clusters with fabricating different initial configurations

    The melting process of Co, Co-Cu and Co-Ni clusters with different initial configurations is studied in molecular dynamics by a general embedded atom method. An irregular melting, at which energy decreases as the temperature increase near the melting point, is found in the onion-like Co-Cu-Co clusters, but not in the mixed Co-Cu and onion-like Co-Ni-Co clusters. From the analysis of atomic distributions and energy variation, the results indicate the irregular melting is induced by Cu atomic segregation. Furthermore, this melting can be controlled by doping hetero atoms with different surface energies and controlling their distributions.

  11. Actividad catalítica de metales de transición en la descomposición de peróxido de hidrógeno

    José G. Carriazo

    2012-01-01

    Full Text Available This paper compares the catalytic activities of some transition metal ions (Fe3+, Co2+, Cu2+, Ni2+, Zn2+ in the H2O2 decomposition in homogenous and heterogeneous processes, including solid mixed systems (Fe-Cu-Co/Al2O3, Fe-Cu/Al2O3, Fe-Co/Al2O3 and Co-Cu/Al2O3. The solids were characterised by X-ray diffraction to explore evolution of phases or possible changes. Different trends of the catalytic activity were observed: in homogeneous medium the most active species was Fe3+, whereas in heterogeneous one the higher activities were shown for Co/Al2O3 and Co-Cu/Al2O3. A strong cooperative effect for the Co-Cu/Al2O3 system was observed, which can be considered as a new catalyst of interest for this type of reactions.

  12. Influence of atomic tip structure on the intensity of inelastic tunneling spectroscopy data analyzed by combined scanning tunneling spectroscopy, force microscopy, and density functional theory

    Okabayashi, Norio; Gustafsson, Alexander; Peronio, Angelo; Paulsson, Magnus; Arai, Toyoko; Giessibl, Franz J.

    2016-04-01

    Achieving a high intensity in inelastic scanning tunneling spectroscopy (IETS) is important for precise measurements. The intensity of the IETS signal can vary by up to a factor of 3 for various tips without an apparent reason accessible by scanning tunneling microscopy (STM) alone. Here, we show that combining STM and IETS with atomic force microscopy enables carbon monoxide front-atom identification, revealing that high IETS intensities for CO/Cu(111) are obtained for single-atom tips, while the intensity drops sharply for multiatom tips. Adsorption of the CO molecule on a Cu adatom [CO/Cu/Cu(111)] such that the molecule is elevated over the substrate strongly diminishes the tip dependence of IETS intensity, showing that an elevated position channels most of the tunneling current through the CO molecule even for multiatom tips, while a large fraction of the tunneling current bypasses the CO molecule in the case of CO/Cu(111).

  13. Co and Cu co-doped ZnO epitaxial films—A magnetically soft nano-composite

    Ney, V.; Venkataraman, V.; Henne, B.; Ollefs, K.; Wilhelm, F.; Rogalev, A.; Ney, A.

    2016-04-01

    A series of Co/Cu co-doped ZnO epitaxial films has been grown on sapphire substrates to investigate the possibilities of tailoring the magnetic properties in functional ZnO-Co/Cu nano-composites. The growth was performed using reactive magnetron sputtering varying the oxygen partial pressure to tune the incorporation of the dopants and the resulting valence state. At high oxygen pressures, Co2+ is formed and the resulting magnetic properties are very similar to phase pure paramagnetic Co-doped ZnO samples. However, the formation of a secondary CuO phase reduces the overall structural quality of the layers and virtually no substitutional incorporation of Cu2+ in ZnO could be evidenced. At low oxygen pressures, a significant fraction of metallic Co and Cu forming nanometer-sized superparamagnetic precipitates of a Co/Cu alloy can be evidenced which are embedded in a ZnO host matrix.

  14. Mean lives of nuclear levels determined by resonance scattering of Bremsstrahlung

    The mean lives of various nuclear levels, between 1,400 and 1,650 keV, in natural Ni, Co, Cu and In have been determined by resonance. They are consistent with each other and with those previously obtained for levels below 1,400 keV under similar conditions

  15. Influence of metal-containing carbon fibers on the properties of carbon-filled plastics based on aromatic polyamide

    Burya, A. I.; Safonova, A. M.; Rula, I. V.

    2012-07-01

    The influence of metal-containing carbon fibers on the thermal properties of carbon-filled phenylone-based plastics has been investigated. It has been shown that carbometallic fibers containing in their composition 20- 30 mass % of a finely dispersed metal (Co, Cu) are promising fillers of phenylone C-2 for making carbonfilled plastics working in frictional units of various machines and mechanisms.

  16. Influence of Copper Oxidation State on the Bonding and Electronic Structure of Cobalt-Copper Complexes

    Eisenhart, Reed J.; Carlson, Rebecca K.; Clouston, Laura J.; Young, Jr., Victor G.; Chen, Yu-Sheng; Bill, Eckhard; Gagliardi, Laura; Lu, Connie C. (UC); (UMM); (MXPL)

    2016-03-04

    Heterobimetallic complexes that pair cobalt and copper were synthesized and characterized by a suite of physical methods, including X-ray diffraction, X-ray anomalous scattering, cyclic voltammetry, magnetometry, electronic absorption spectroscopy, electron paramagnetic resonance, and quantum chemical methods. Both Cu(II) and Cu(I) reagents were independently added to a Co(II) metalloligand to provide (py3tren)CoCuCl (1-Cl) and (py3tren)CoCu(CH3CN) (2-CH3CN), respectively, where py3tren is the triply deprotonated form of N,N,N-tris(2-(2-pyridylamino)ethyl)amine. Complex 2-CH3CN can lose the acetonitrile ligand to generate a coordination polymer consistent with the formula “(py3tren)CoCu” (2). One-electron chemical oxidation of 2-CH3CN with AgOTf generated (py3tren)CoCuOTf (1-OTf). The Cu(II)/Cu(I) redox couple for 1-OTf and 2-CH3CN is reversible at -0.56 and -0.33 V vs Fc+/Fc, respectively. The copper oxidation state impacts the electronic structure of the heterobimetallic core, as well as the nature of the Co–Cu interaction. Quantum chemical calculations showed modest electron delocalization in the (CoCu)+4 state via a Co–Cu σ bond that is weakened by partial population of the Co–Cu σ antibonding orbital. By contrast, no covalent Co–Cu bonding is predicted for the (CoCu)+3 analogue, and the d-electrons are fully localized at individual metals.

  17. Hyperfine Fields in Complex Metallic Systems: Co Clusters Embedded in Cu

    Frota-Pessoa, S., E-mail: sfpessoa@macbeth.if.usp.br; Legoas, S. B. [Universidade de Sao Paulo, Instituto de Fisica (Brazil)

    2001-03-15

    We have used first-principles linear muffin tin orbital (LMTO-ASA) electronic structure calculations, implemented directly in real space (RS) to theoretically investigate the behavior of the hyperfine field of Co clusters embedded in fcc Cu. We find that the magnitude of the dominant contact contribution to the hyperfine field decreases significantly as one goes from the Co site at the center of the cluster to those at the Co-Cu interface. To better understand this behavior, we use a simple model which closely reproduces the first-principles calculations, but is physically more transparent. Our approach can partially deconvolute the several dependences, calling attention to the processes which regulate the hyperfine field behavior in these complex Co-Cu systems.

  18. Úprava laboratorních odpadních vod obsahujících těžké kovy

    Krištof, Ondřej

    2009-01-01

    Bakalářská práce je zaměřena na problematiku těžkých kovů, jako Cr, Hg, Pb, Co, Cu, Ag, obsažených v odpadních vodách laboratoře anorganické chemie. Zabývá se bilancí těchto kovů u jednotlivých úloh, srovnáním bilance s praktickými výsledky studentů. Navrhuje také možné způsoby jejich izolace z odpadních roztoků s ohledem na ekonomický dopad. This bachelor‘s thesis is focused on problematics of heavy metals such as Cr, Hg, Pb, Co, Cu, Ag, which are present in wastewater from anorganic labo...

  19. Evidence of the nature of core-level photoemission satellites using angle-resolved photoemission extended fine structure

    Moler, E.J.; Kellar, S.A.; Huff, W.R.A. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    The authors present a unique method of experimentally determining the angular momentum and intrinsic/extrinsic origin of core-level photoemission satellites by examining the satellite diffraction pattern in the Angle Resolved Photoemission Extended Fine Structure (ARPEFS) mode. They show for the first time that satellite peaks not associated with chemically differentiated atomic species display an ARPEFS intensity oscillation. They present ARPEFS data for the carbon 1s from ({radical}3x{radical}3)R30 CO/Cu(111) and p2mg(2xl)CO/Ni(110), nitrogen 1s from c(2x2) N{sub 2}/Ni(100), cobalt 1s from p(1x1)Co/Cu(100), and nickel 3p from clean nickel (111). The satellite peaks and tails of the Doniach-Sunjic line shapes in all cases exhibit ARPEFS curves which indicate an angular momentum identical to the main peak and are of an intrinsic nature.

  20. Functional Nanowires Array Electrodeposited into Nano-porous Membrane Thin Films

    Ni, Co, Fe and Co/Cu multilayered nanowires were electrodeposited into a nano-well template to synthesize novel functional ferromagnetic devices. Growth rate of Co/Co multilayered nanowires was around 40 nm.sec−1 and the cylindrical shape was precisely transferred from the nanochannels to the nanowires and the aspect ratio reached up to ca. 150. Magnetic hysteresis loops of Ni, Co and Fe nanowires with diameter 40 nm showed typical perpendicular magnetization behavior due to the uni-axial shape anisotropy and the coercive force reached up to around 1 kOe. 2% of anisotropic magnetoresistance effect was observed in Ni nanowires electrodeposited into anodized aluminum oxide template, while 20% of giant magnetoresistance effect was observed in Co/Cu multilayered nanowires.

  1. Influence of copper content on the electrocatalytic activity toward methanol oxidation of CoχCuy alloy nanoparticles-decorated CNFs

    Ghouri, Zafar Khan; Barakat, Nasser A. M.; Kim, Hak Yong

    2015-11-01

    In this study, CoCu alloy nanoparticles-incorporated carbon nanofibers are introduced as effective non precious electrocatalyst for methanol oxidation in alkaline medium. The introduced electrocatalyst has been synthesized by simple and effective process; electrospinning. Typically, calcination, in nitrogen atmosphere, of electrospun nanofibers composed of cobalt acetate, copper acetate and poly (vinyl alcohol) leads to form carbon nanofibers decorated by CoCu nanoparticles. The nanofibrous morphology and alloy structure have been confirmed by SEM, TEM and XRD analyses. Investigation of the electrocatalytic activity indicates that copper content has strong influence, the alloy nanoparticles having the composition Cu5%Co95% showed distinct high performance; 100 times higher than other formulations. Overall, the introduced study revealed the veil about the distinct role of copper in enhancing the electrocatalytic activity of cobalt-based materials.

  2. Preparation of Mg-based hydrogen storage materials from metal nanoparticles

    By hydrogen plasma metal reaction method, we obtained Mg, Ni, Co, Cu and Fe nanoparticles. Mg nanoparticles show larger average particle size than Ni, Co, Cu and Fe ones. From these metal nanoparticles, Mg-based hydrogen storage alloys (Mg2Ni, Mg2Co and Mg2Cu) and hydrides (Mg2NiH4, Mg2CoH5 and Mg2FeH6) were prepared by solid-solid and gas-solid reactions. Powder X-ray diffraction (XRD) was used to define the structure and composition information. The preparation results in different atmosphere were compared and discussed. Hydrogen and nanostructure play important roles in the preparation of Mg-based hydrogen storage alloys/hydrides in convenient conditions from metal nanoparticles

  3. Detecting Rashba fields at the interface between Co and Si oxide by ferromagnetic resonance

    Verhagen, T. G. A.; Leermakers, I.; van Ruitenbeek, J. M.; Aarts, J.

    2015-05-01

    We report ferromagnetic resonance (FMR) experiments on thin magnetic Co layers either sandwiched symmetrically between Cu and Pt, or sandwiched asymmetrically between a Cu or Pt layer on one side and a SiOx substrate on the other. In the symmetric samples, we find well-known behavior, namely, the FMR linewidth Δ Hp p is significantly larger for the case of Pt than for the case of Cu. This is due to the larger spin scattering in the Pt layer. However, for the asymmetric Co/Cu bilayers, the linewidth is much larger than for the symmetric Cu/Co/Cu trilayers and not much different from the linewidth of Co/Pt bilayers. We argue this to be due to the Rashba effect at the SiOx/Co interface, which gives rise to effective magnetic fields interacting with the electron spins in the Co layer and which can be measured without reverting to transport measurements.

  4. Instrumental neutron activation analysis of the hair of metallurgical workers

    Hair samples were collected from 20 metallurgical workers (10 males and 10 females) and from 59 control subjects (32 males and 27 females), whose jobs do not indicate a specific occupational exposure. The concentrations of ten minor and trace elements (Al, Co, Cu, Fe, Mg, Mn, Sb, Se, V and Zn) were determined by instrumental neutron activation analysis (INAA). The statistical data distributions, the sex and age influences in these elemental concentrations and the average values obtained for the control group were compared with published data. The effect of occupational exposure to the metallic elements was reflected in elemental compositon of hair by significant higher concentration levels of Al, Co, Cu, Fe, Mg, Mn, Sb, V and Zn in the hair of the exposed group, when compared with the control group. (author)

  5. Metal grids with high-porous surface as structured catalysts: preparation, characterization and activity in propane total oxidation

    Yuranov, I.; Dunand, N.; Kiwi-Minsker, L; Renken, A.

    2002-01-01

    Metal nickel and copper grids are shown to be suitable supports for structured combustion catalysts. The increase of sp. surface area (SSA) of metal grids was achieved due to the porous outer layer with the structure of Raney metal developed on the wire surface. Transition metals (Co, Cu, Mn, Cr) oxides were deposited as active components on the pre-oxidized support and tested in total propane oxidn. Cobalt oxide demonstrated the highest activity. Reductive pre-treatment in the flow of hydrog...

  6. Assessment of Metal Toxicity in Marine Ecosystems: Comparative Toxicity Potentials for Nine Cationic Metals in Coastal Seawater

    Dong, Yan; Rosenbaum, Ralph K.; Hauschild, Michael Zwicky

    2016-01-01

    ecotoxicity data and take account of metal speciation and bioavailability. CTPs were developed for nine cationic metals (Cd, Cr(III), Co, Cu(II), Fe(III), Mn, Ni, Pb and Zn) in 64 Large Marine Ecosystems (LMEs) covering all coastal waters in the world. The results showed that the CTP of a specific metal...... occurring in coastal seawaters, Fe acts not as a toxic agent but an essential nutrient and thus has CTPs of zero....

  7. Trace elements determination in high salinity petroleum produced formation water by high-resolution continuum source graphite furnace atomic absorption spectrometry after matrix separation using Chelex-100 Registered-Sign resin

    Freire, Aline Soares [Departamento de Geoquimica, Universidade Federal Fluminense, Outeiro Sao Joao Batista s/n, Centro, Niteroi/RJ, 24020-150 (Brazil); Departamento de Quimica Analitica, Universidade Federal do Rio de Janeiro Av. Athos da Silveira Ramos 149, Centro de Tecnologia, Bloco A, Cidade Universitaria, Rio de Janeiro/RJ, 21941-909 (Brazil); Santelli, Ricardo Erthal, E-mail: santelli@iq.ufrj.br [Departamento de Geoquimica, Universidade Federal Fluminense, Outeiro Sao Joao Batista s/n, Centro, Niteroi/RJ, 24020-150 (Brazil); Departamento de Quimica Analitica, Universidade Federal do Rio de Janeiro Av. Athos da Silveira Ramos 149, Centro de Tecnologia, Bloco A, Cidade Universitaria, Rio de Janeiro/RJ, 21941-909 (Brazil)

    2012-05-15

    This study describes a procedure used for the determination of trace metals (Co, Cu, Mn, Ni and Pb) in high salinity petroleum produced formation water (PFW) employing high-resolution continuum source graphite furnace atomic absorption spectrometry for detection and Chelex-100 Registered-Sign resin for matrix elimination and analytes preconcentration. Using 15.0 mL of PFW for the separation/preconcentration, detection limits of 0.006, 0.07, 0.03, 0.08 and 0.02 {mu}g L{sup -1} were obtained for Co, Cu, Mn, Ni and Pb, respectively. The accuracy of the proposed method was evaluated by analyzing three seawater certified reference materials and by recovery tests, and the data indicate that the methodology can be successfully applied to this kind of samples. The precision values, expressed as relative standard deviation (% RSD, n = 10) for 2.0 {mu}g L{sup -1}, were found to be 3.5, 4.0, 9.0, 5.3 and 5.9 for Co, Cu, Mn, Ni and Pb, respectively. The proposed procedure was applied for the determination of these metals in medium and high salinity PFW samples obtained from Brazilian offshore petroleum exploration platforms. - Highlights: Black-Right-Pointing-Pointer Petroleum-produced formation water were analyzed for Co, Cu, Mn, Ni and Pb determination. Black-Right-Pointing-Pointer In batch analyte preconcentration/matrix separation using Chelex-100 Registered-Sign was used. Black-Right-Pointing-Pointer Detection limits between 0.006 and 0.08 {mu}g L{sup -1} were found by using HR-CS-GFAAS. Black-Right-Pointing-Pointer Trace elements characterization is possible using the developed method. Black-Right-Pointing-Pointer Maximum trace element concentrations found could support future Brazilian directives.

  8. ANALYSIS OF SOME ESSENTIAL ELEMENTS IN MEDICINAL PLANTS USED IN AYURVEDA

    Om Prakash Rout; Rabinarayan Acharya; Rakshapal Gupta; Sagar Kumar Mishra; Rashmibala Sahoo

    2013-01-01

    This study presents a preliminary data of occurrence of elemental concentration in medicinal plants i.e Apium graveolens (seed), Sida cordifolia (root), Solanum surattense (whole plant), Tribulus terrestris(fruit) and Withania somnifera (root) used in Ayurveda, using Atomic absorption spectrometer (AAS) following standard procedures. The elemental concentration i.e. Mn, Na, K, Cl, Ca, Cr, Co, Cu, Fe, Pb, Zn, Ni, Cd and Hg were found in various proportions. The data obtained from the study can...

  9. Interface magnetism of 3d transition metals

    Niklasson, A. M. N.; Johansson, B.; Skriver, Hans Lomholt

    1999-01-01

    The layered resolved magnetic spin moments of the magnetic 3d bilayer interfaces Fe/V bcc, Fe/Co bcc, Fe/Cu bcc, Co/V bcc, Co/Ni fee, Co/Cu fee, Ni/V fee, Ni/Cr fcc, Ni/Cu fee and the magnetic surfaces Fe bcc, Co bcc, Co fee, and Ni fee are calculated for the (001), (011), and (111) orientations by...

  10. Current-driven, electrically detected ferromagnetic resonance in electrodeposited spin valves

    We investigate the ferromagnetic resonance of Co/Cu/Co trilayers by use of AC-spin-transfer torque excitations. Magnetic structures are grown in a 6-μm-thick commercial nanoporous polycarbonate membranes by use of electrodeposition in a cobalt/copper single bath. We show that microwave magnetic excitations corresponding to the uniform mode of the two cobalt layers are electrically detected as a change of the DC voltage of the system.

  11. Theoretische Untersuchung der thermischen Stabilität und morphologischer Umwandlungen in nanoskaligen Multischichten

    Ullrich, Albrecht

    2003-01-01

    Nanoskalige Multischichten besitzen attraktive physikalische Eigenschaften wie den Riesenmagnetwiderstand, die sehr sensibel von der Struktur der Grenzfläche und der Einzelschichtdicke abhängen. Mit Hilfe einer Wärmebehandlung wird versucht, den Riesenmagnetwiderstand der durch Sputtern abgeschiedenen Schichten zu erhöhen. In entmischenden System Co/Cu wird bei Einzelschichtdicken von 2nm eine Erhöhung des Riesenmagnetwiderstandes gemessen. Allerdings verringert sich der Widerstand bei höhere...

  12. Physicochemical properties and catalytic activity of metal tetraphenyl porphins in the oxidation of alkylaromatic hydrocarbons

    Kobotaeva, N. S.; Skorokhodova, T. S.; Kokova, D. A.

    2013-06-01

    We consider the effect of complexing metal in a tetraphenylporphin molecule on its catalytic activity in oxidizing alkylaromatic hydrocarbons by molecular oxygen. The catalytic activity of metal porphyrins (Co, Cu, Zn, Mn, and In TPP) is found to depend on their oxidation potentials and the distribution of electron density in the molecule. The electron-donating compound imidazole is shown to affect the oxidation rate.

  13. Geochemical study of main elements and trace elements in soils of three profiles in the state of Santa Catarina

    The total concentrations of the main components (Si, Al, Fe, Ca, Mg, Mn, Ti, Na and K) and of nine trace elements (Ba, Co, Cu, La, Li, Mo, Ni, V and Zn are measured. The elements are determined by several atomic absorption and emission spectroscopic methods. Some properties such as granulometry, mineralogy of the clay fraction, organic matter, etc, are studied. (M.J.C.)

  14. Sintering-modified oxymanganospinel ceramics for NTC thermistor application

    Hadzaman, I.; Klym, H.; Shpotyuk, O.; Brunner, M; Balitska, V.

    2012-01-01

    Mixed Ni-Co-Cu oxymanganospinels of Cu0.1Ni0.8Co0.2Mn1.9O4 chemical composition are first developed for possible application as high-precise NTC thermistors using nanophase segregation effects controlled by sintering technological route. It is shown that rack-salt NiO phase in these ceramics occurs a decisive role on parasitic degradation caused by thermal storage of the ceramics at the elevated temperatures.

  15. A mineralized breccia pipe in Monhawk Canyon, Arizona

    This book reports on hundreds of solution-collapse breccia pipes in northern Arizona. High-grade U ore, and potentially economic concentrations of Ag, Co, Cu, Ni, Pb, and Zn in some pipes, has stimulated mining activity there. More than 900 confirmed and suspected breccia pipes have been mapped by this study. One pipe was chosen for exploration drilling in 1984 because it exhibited all preestablished exploration criteria. Five rotary and core holes were drilled into this pipe; they contained mineralized breccia

  16. Heavy Metal Accumulation in Lake Sediments, Fish (Oreochromis niloticus and Serranochromis thumbergi), and Crayfish (Cherax quadricarinatus) in Lake Itezhi-tezhi and Lake Kariba, Zambia

    Nakayama, Shouta M. M.; IKENAKA, Yoshinori; Muzandu, Kaampwe; Choongo, Kennedy; Oroszlany, Balazs; Teraoka, Hiroki; Mizuno, Naoharu; Ishizuka, Mayumi

    2010-01-01

    We measured the level of heavy metal accumulation in lake sediments, herbivorous (Oreochromis niloticus) and carnivorous (Serranochromis thumbergi) fish, and crayfish (Cherax quadricarinatus) from Lake Itezhi-tezhi (ITT) and Lake Kariba. We used atomic absorption spectrophotometry to quantify the levels of seven heavy metals (Cr, Co, Cu, Zn, Cd, Pb, and Ni). The sediment and the herbivorous fish O. niloticus accumulated a very high concentration of Cu in Lake ITT, most likely due to the disc...

  17. Coordination chemistry of poly(thioether)borate ligands

    Riordan, Charles G.

    2010-01-01

    This review traces the development and application of the tris(thioether)borate ligands, tripodal ligands with highly polarizable thioether donors. Areas of emphasis include the basic coordination chemistry of the mid-to-late first row transition metals (Fe, Ni, Co, Cu), and the role of the thioether substituent in directing complex formation, the modeling of zinc thiolate protein active sites, high-spin organo-iron and organo-cobalt chemistry, the preparation of monovalent complexes of Fe, C...

  18. High-energy sintered Nd-Dy-Fe-B magnets with Co and Cu additions

    Simultaneous Co and Cu additions to sintered Nd-Dy-Fe-B magnets refine the microstructure and improve the energy density. This is due to the replacement of the conventional Nd-rich constituents by RE-(Co,Cu) phases with low melting points, such as RECu or RE3Co. A remanence of 1.41 T and an energy density of 383 kJ/m3 could be achieved. (orig.)

  19. Heavy metal uptake and stress responses of hydroponically cultivated garlic (Allium sativum L.)

    Soudek, P. (Petr); Petrová, Š. (Šárka); Vaněk, T. (Tomáš)

    2011-01-01

    The accumulation of toxic metals (Cd, Co, Cu and Ni) by Allium sativum plants was followed under hydroponic conditions. The toxic metals were applied at two concentrations (0.05 and 0.25 mM). The effects of heavy metals on chlorophyll and carotenoid content, root length and amino acid exudation were examined to evaluate the impact of heavy metal accumulation on plant growth and development. A significant hyperaccumulation of cadmium by garlic roots was observed. Cobalt stimulated carotenoid p...

  20. Fe and Co nanostructures embedded into the Cu(100) surface: Self-Organization and magnetic properties

    The self-organization and magnetic properties of small iron and cobalt nanostructures embedded into the first layer of a Cu(100) surface are investigated using the self-learning kinetic Monte Carlo method and density functional theory. The similarities and differences between the Fe/Cu(100) and the Co/Cu(100) are underlined. The time evolution of magnetic properties of a copper monolayer with embedded magnetic atoms at 380 K is discussed

  1. Second Harmonic Detection of Spin-Dependent Transport in Magnetic Nanostructures

    Yu, Hai-Ming; Granville, S.; Yu, Da-Peng; J-ph., Ansermet

    2010-02-01

    Detection of the second harmonic response of magnetic nanostructures to an ac current is shown to be a very sensitive probe of the magnetization reversal process. A temperature oscillation is obtained by Joule heating instead of using a laser as the heat source, as in thermo-galvanic voltage measurements (TGV). Joule heating is used to produce a large local temperature gradient in asymmetric Co/Cu/Co spin valves. Evidence is found for an effect of a heat current on magnetization.

  2. Assessment of physico-chemical properties and metal contents of water and sediments of Bodo Creek, Niger Delta, Nigeria

    Vincent-Akpu, Ijeoma Favour; Tyler, Andrew N.; Wilson, Clare; MacKinnon, Gillian

    2015-01-01

    Some physico-chemical properties and the concentrations of the metals Fe, Mn, Ni, Cd, Cr, Co, Cu, Pb, and Zn in water and sediments were examined from September 2011 to January 2012 in Bodo Creek, where oil spills have been recurrent. Temperature, pH, total dissolved solid, conductivity, salinity, dissolved oxygen, biological oxygen demand (BOD), chemical oxygen demand (COD), total hardness, sulfate, nitrate, and phosphate were determined in surface water. Particle size, total organic matter ...

  3. Spin-transfer induced ultrafast precessional switching enhanced by interface anisotropy in a ferromagnetic nanopillar

    Spin-transfer induced ultrafast precessional switching of magnetization in the Co/Cu/Co nanopillar device is studied. Micromagnetic calculations show that, precessional magnetization switching occurs above a threshold current. The presence of interface uniaxial anisotropy in the Co-thin film free layer, influences heavily the current and energy required to initiate the switching in the device, and the speed of the precessional switching. The threshold current and the precessional switching time are significantly reduced by this effect. (author)

  4. Highly efficient spin filtering of ballistic electrons

    Steinmuller, S. J.; Trypiniotis, T.; Cho, W. S.; Hirohata, A.; Lew, W. S.; Vaz, C. A.; Bland, J. A.

    2004-04-01

    Spin dependent electron transport in hybrid Au/Co/Cu/NiFe/n-GaAs spin valve Schottky barrier structures was investigated using photoexcitation at various wavelengths. For excitation with the photon energy well above the Schottky barrier height we found a ˜2400% increase in helicity dependent photocurrent on switching the spin valve from parallel to antiparallel alignment. Our observations provide clear evidence for highly efficient spin filtering of spin polarized ballistic electrons.

  5. Fe and Co nanostructures embedded into the Cu(100) surface: Self-Organization and magnetic properties

    Kolesnikov, S. V., E-mail: kolesnikov@physics.msu.ru; Klavsyuk, A. L.; Saletsky, A. M. [Moscow State University, Faculty of Physics (Russian Federation)

    2015-10-15

    The self-organization and magnetic properties of small iron and cobalt nanostructures embedded into the first layer of a Cu(100) surface are investigated using the self-learning kinetic Monte Carlo method and density functional theory. The similarities and differences between the Fe/Cu(100) and the Co/Cu(100) are underlined. The time evolution of magnetic properties of a copper monolayer with embedded magnetic atoms at 380 K is discussed.

  6. Coupling time scales for simulation of structure transformation: an attempt to combine molecular dynamics and phase-field theory

    Liu, Zhi-Rong; Gao, Huajian

    2002-01-01

    A multiscale scheme combining molecular dynamics (MD) and microscopic phase-field theory is proposed to study the structural phase transformations in solids with inhomogeneous strain field. The approach calculates strain response based on MD and atomic diffusion based on the phase field theory. Simulations with the new technique are conducted in two examples. The first involves interface roughening in a Co/Cu thin film, where interfacial undulations due to lattice mismatch is demonstrated. Th...

  7. Imaging of lateral spin valves with soft X-ray microscopy

    Mosendz, O.; Mihailovic, G.; Pearson, J. E.; Fischer, P.; Im, M.-Y; Bader, S. D.; Hoffmann, A

    2009-01-01

    We investigated Co/Cu lateral spin valves by means of high-resolution transmission soft x-ray microscopy with magnetic contrast that utilizes x-ray magnetic circular dichroism (XMCD). No magnetic XMCD contrast was observed at the Cu L$_3$ absorption edge, which should directly image the spin accumulation in Cu. Although electrical transport measurements in a non-local geometry clearly detected the spin accumulation in Cu, which remained unchanged during illumination with circular polarized x-...

  8. Minerals in plant food: effect of agricultural practices and role in human health. A review

    Martínez-Ballesta, M.C.; Dominguez-Perles, R.; Moreno, D. A.; Muries, B.; Alcaraz-López, C.; Bastías, E.; García-Viguera, C; Carvajal, M.

    2010-01-01

    Interest in nutrient absorption and accumulation is derived from the need to increase crop productivity by better nutrition and also to improve the nutritional quality of plants as foods and feeds. This review focuses on contrasting data on the importance for human health of food mineral nutrients (Ca, Mg, K, Na and P) and also the trace elements considered essential or beneficial for human health (Cr, Co, Cu, Fe, Mn, Mo, Ni, Se and Zn). In addition, environmental stresses such as salinity, d...

  9. Fe and Co nanostructures embedded into the Cu(100) surface: Self-Organization and magnetic properties

    Kolesnikov, S. V.; Klavsyuk, A. L.; Saletsky, A. M.

    2015-10-01

    The self-organization and magnetic properties of small iron and cobalt nanostructures embedded into the first layer of a Cu(100) surface are investigated using the self-learning kinetic Monte Carlo method and density functional theory. The similarities and differences between the Fe/Cu(100) and the Co/Cu(100) are underlined. The time evolution of magnetic properties of a copper monolayer with embedded magnetic atoms at 380 K is discussed.

  10. Geochemistry of polymetallic nodules from the Central Indian Ocean basin

    Valsangkar, A.B.; Khadge, N.H.; Desa, J.A.E.

    ; \\[\\] > l0 cm. Pacific Ocean; A nodules; x sediments. Average shale values from Piper (1974). POLYMETALLIC NODULES FROM THE CENTRAL INDIAN OCEAN BASIN TABLE 3A Inter-element relationship in the CIOB nodules Moisture Mn Fe Cu Ni Co Cu + Ni + Co Moisture...-242. Lyle, M., 1982. Estimating growth rates of ferromanganese nodules from chemical composition: implications for nodule formation processes. Geochim. Cosmochem. Acta., 46: 2301- 2306. Piper, D.Z., 1974. Rare earth elements and the sedimentary cycle: A...

  11. Spatial–temporal variations, sources, and transport of airborne inhalable metals (PM10) in urban and rural areas of northern China

    X. S. Luo; C. C. M. Ip; Li, W; S. Tao; Li, X.D.

    2014-01-01

    Atmospheric particle pollution is a serious environmental issue in China, especially the northern regions. Ambient air loadings (ng m−3), pollution sources and apportionment, and transport pathways of trace (Cd, Co, Cu, Ni, Pb, V, and Zn) and major (Al, Ca, Fe, and Mg) metals associated with inhalable particulate matters (PM10 aerosols) were characterized in urban, rural village, and rural field areas of seven cities (from inland in the west to the coast in the ...

  12. Reversal mode instability and magnetoresistance in perpendicular (Co/Pd)/Cu/(Co/Ni) pseudo-spin-valves

    Davies, J. E.; Gilbert, D. A.; Mohseni, S. M.; Dumas, R. K.; Åkerman, J.; Liu, Kai

    2013-01-01

    We have observed distinct temperature-dependent magnetization reversal modes in a perpendicular (Co/Pd)4/Co/Cu/(Co/Ni)4/Co pseudo-spin-valve, which are correlated with spin-transport properties. At 300 K, magnetization reversal occurs by vertically correlated domains. Below 200 K the hysteresis loop becomes bifurcated due to laterally correlated reversal of the individual stacks. The magnetic configuration change also leads to higher spin disorders and a significant increase in the giant magn...

  13. Microstructural study and numerical simulation of phase decomposition of heat treated Co–Cu alloys

    A.M. Mebed

    2014-12-01

    Full Text Available The influence of heat treatment on the phase decomposition and the grain size of Co–10 at% Cu alloy were studied. Few samples were aged in a furnace for either 3 or 5 h and then quenched in iced water. The materials and phase compositions were investigated using energy dispersive spectrometry and X-ray diffraction techniques. X-ray diffraction analysis showed that the samples contained Co, Cu, CuO, CoCu2O3, CoCuO2 phases in different proportions depending on the heat treatment regimes. The formation of dendrite Co phase rendered the spinodal decomposition while the oxidations prevent the initiation of the spinodal decomposition even for a deep long aging inside the miscibility gap. Since the Bragg reflections from different phases of Co–Cu alloy significantly overlap, the crystal structural parameters were refined with FULLPROF program. The shifts in the refined lattice constants (a, b and c, the space group and the grain size were found to be phase- and heat treatment-dependant. Two-dimensional computer simulations were conducted to study the phase decomposition of Co–Cu binary alloy systems. The excess free energy as well as the strain energy, without a priori knowledge of the shape or the position of the new phase, was precisely evaluated. The results indicate that the morphology and the shape of the microstructure agree with SEM observation.

  14. Coercivity behavior in Gd(Co1−xCux)5 system as function of the microstructureevolution

    Magnetic measurements, X-ray diffraction and scanning electron microscopy (SEM) experiments were carried out in the as-cast Gd(Co1−xCux)5 samples with different Co/Cu content. Already in the as cast state, this system shows high coercive field for x=0.3 and a magnetization driven by nucleation of reversal domain. SEM micrograph and microanalysis show possible spinodal decomposition in the as-cast state, hence regions with different Co/Cu-content are observed, while the Gd-content almost does not change. High resolution X-ray diffraction patterns show a main CaCu5-type structure with traces of a secondary phase and distorted peak profiles as function of the Cu content. The evolution of the microstructure is discussed in relation with the Cu incorporation into the CaCu5-type structure. The Cu addition avoids the formation of the 2:7 phase within the 1:5 matrix, favoring the formation of a more homogeneous Gd(Co,Cu)5 phase. The relation between the observed microstructure and the magnetic behavior is also discussed

  15. Analysis of human materials by microwave induced plasma-mass spectrometry

    When various kinds of element concentrations in human materials or environmental samples were analysed, microwave induced plasma-mass spectrometry (MIP-MS) was used for elements below ppm levels and flame atomic absorption spectrophotometry for relatively high concentrations. First, standard materials of hair, serum and milk were analysed. In the hair material of the Bureau Communautaire Reference (BCR) CRM-397, which had the certified values of Cd, Hg, Pb, Se and Zn, our analytical results agreed well with the certified values. In the National Institute for Environmental Studies (NIES) No. 13 Hair Material, which bad the certified values of Ca, Cu, Hg, Pb, Sb, Se and Zn, and the reference values of 12 elements, our results agreed well with the certified values, except Sb, for which our result was 1.38 times higher. Our results for Ca, Co, Cr, Fe, Mn and Na were within 10% of the reference values. In the hair material of GBW-07601 prepared in China, which has the certified values of 39 elements and the information values of 23 elements, our analytical results of Mn, Fe, Co, Cu, Se, Sr, Ba, Bi, Mg, Na and Zn were within 10% of the certified values. In National Institute of Standards and Technology (NIST) SRM-1598 Bovine Serum and NIST SRM-1549 Non-fat Milk Powder, our analytical values of Co, Cu, Mn, Mo, Rb, Se and Zn in Bovine Serum, and Co, Cu, K, Mg, Mn, Na, P, Pb, Rb, Se and Zn in the Non-fat Milk Powder showed good agreement. It is interesting that the contents of the various elements in these materials may reflect the environments, living habits and other existing conditions of the countries producing the materials. When the results by MIP-MS were ascertained, inductively coupled plasma-mass spectrometry was used. After evaluating the technical method, human hair, serum and milk samples were analysed. The analytical results are presented in the paper. (author)

  16. Influence of the Amazon River on dissolved and intra-cellular metal concentrations in Trichodesmium colonies along the western boundary of the sub-tropical North Atlantic Ocean

    S. A. Sañudo-Wilhelmy

    2011-01-01

    Full Text Available Despite the ecological importance of Trichodesmium spp. for the global oceanic nitrogen budget, there is limited information on their trace metal composition in field samples. We report dissolved (Trichodesmium populations collected in the western subtropical North Atlantic Ocean (April–May 2003 within the influence of the Amazon River plume. Dissolved element distributions were strongly influenced by the River discharge, with concentrations of some elements varying directly (i.e. Cd, Mo and V or inversely (Ag, Co, Cu, Fe, Ni, P and Pb with surface salinity. Intracellular metal values to phosphorous ratios (mol:mol for Cd, Co, Cu, Fe, Mn, Mo, Ni and V ranged from 9.0 × 10−6 for Cd to 4.4 × 10−2 for Fe. Although total metal composition was significantly correlated with the intracellular content in the Trichodesmium colonies for some elements (e.g., Co, Cu, V, metal pools in the phytoplankton did not co-vary with the dissolved metal concentrations, suggesting that water column measurements may not be good predictors of the intracellular metal concentrations. The impact of physical parameters and bioactive elements on biological processes such as nitrogen fixation, carbon drawdown and biomass production in Trichodesmium colonies was explored by using a principal component analysis test (PCA. The analysis indicated that the biological drawdown of dissolved inorganic carbon (DIC by Trichodesmium seems to be influenced by the internal content of Fe, Co, Cd, and Cu, while nitrogen fixation seems more influenced by mixed layer depth and dissolved Fe and Ni concentrations.

  17. Influence of the Amazon River on dissolved and intra-cellular metal concentrations in Trichodesmium colonies along the western boundary of the sub-tropical North Atlantic Ocean

    S. A. Sañudo-Wilhelmy

    2010-08-01

    Full Text Available Despite the ecological importance of Trichodesmium spp. for the global oceanic nitrogen budget, there is limited information on their trace metal composition in field samples. We report dissolved (Trichodesmium populations collected in the western subtropical North Atlantic Ocean (April–May 2003 within the influence of the Amazon River plume. Dissolved element distributions were strongly influenced by the River discharge, with concentrations of some elements varying directly (i.e. Cd, Mo and V or inversely (Ag, Co, Cu, Fe, Ni, P and Pb with surface salinity. Intracellular metal values to phosphorous ratios (mol:mol for Cd, Co, Cu, Fe, Mn, Mo, Ni and V ranged from 9.0×10−6 for Cd to 4.4×10−2 for Fe. Although total metal composition was significantly correlated with the intracellular content in the Trichodesmium colonies for some elements (e.g., Co, Cu, V, metal pools in the phytoplankton did not co-vary with the dissolved metal concentrations, suggesting that water column measurements may not be good predictors of the intracellular metal concentrations. The impact of physical parameters and bioactive elements on biological processes in Trichodesmium such as nitrogen fixation, carbon drawdown and biomass production was explored by using a principal component analysis test (PCA. The analysis indicates that the biological drawdown of dissolved inorganic carbon (DIC by Trichodesmium seems to be influenced by the internal content of Fe, Co, Cd, Cu and Mn, while nitrogen fixation seems more influenced by the internal concentration of Mo, Ni and V and by the dissolved phosphorous concentrations.

  18. Ferrite thin films: Synthesis, characterization and gas sensing properties towards LPG

    Rao, Pratibha; Godbole, R.V. [Department of Physics, Abasaheb Garware College, Karve Road, Pune 411 004 (India); Phase, D.M. [UGC-DAE CSR Centre, Indore (India); Chikate, R.C. [Department of Chemistry, Abasaheb Garware College, Karve Road, Pune 411 004 (India); Bhagwat, Sunita, E-mail: smb.agc@gmail.com [Department of Physics, Abasaheb Garware College, Karve Road, Pune 411 004 (India)

    2015-01-15

    Nanocrystalline (Co, Cu, Ni, Zn) ferrite thin films have been deposited onto the Si (100) and alumina substrates by spray pyrolysis deposition technique. Respective metal chlorides and iron chloride were used as precursors. The structural properties of (Co, Cu, Ni, Zn) ferrite thin films were investigated by X-ray diffraction (XRD) technique which confirms polycrystalline nature and single phase spinel structure. The surface morphology was studied using scanning electron microscopy (SEM) which reveals spherical morphology for these films except NiFe{sub 2}O{sub 4} films that exhibit petal like structure. The optical transmittance and reflectance measurements were recorded using a double beam spectrophotometer. The optical studies reveal that the transition is direct band gap energy. The VSM analyzes reveal the predominant ferrimagnetic nature for CuFe{sub 2}O{sub 4} films. The gas sensing properties towards Liquid Petroleum Gas (LPG) revealed that ZnFe{sub 2}O{sub 4} films are sensitive at lower temperature while NiFe{sub 2}O{sub 4} films show steep rise at higher temperature. - Highlights: • (Co, Cu, Ni, Zn) ferrite thin films are synthesized by simple spray pyrolysis technique. • Homogenization of substituent within ferrite structure. • CuFe{sub 2}O{sub 4} film exhibits predominantly ferrimagnetic nature. • LPG sensing at lower temperature for ZnFe{sub 2}O{sub 4} film. • High sensitivity for NiFe{sub 2}O{sub 4} film at higher temperature due to defects created in the structure.

  19. Monitoring of trace-levels of herbicides in the Cachoeira River in Bahia State, Brazil, by neutron activation analysis

    A systematic study was undertaken in order to find out which of the most relevant elements can be determined in water normal conditions by non-destructive neutron activation and a suitable mono standard method. Standardized water from Cachoeira river and croustaceous samples were brought to dryness by freeze-drying and irradiated in quartz at a neutron flux of 1014 cm-2 s-1. Trace element contents in quartz ampoules from different origins were determined separately. The following elements were preliminarily identified: Cr, Co, Cu, Br, Sb, Cs, Ce, Nb, Au, Pa, Zn, La, Sm. (author). 10 refs., 2 tabs

  20. Application of paper chromatography to the determination of some elements in minerals and rocks

    This publication describes our work in applying paper chromatography to the fields of mineralogy and geology. We have studied the separation and determination of the following elements: Nb, Ta, Ti, Co, Cu, Mn, Sn, Ge, As, Sb, Bi, U, Th, Be, Au, Pb, Zn, V and Mo. The development of separation methods for these various elements has led us to solve many interference problems. These methods make it possible to separate and measure mineral components. They also enable us to search for trace elements in ores, rocks soils and carbonaceous materials. Finally let us point out that this technique may equally be used for analysis in very radioactive environment. (author)

  1. Electrothermal atomization atomic absorption spectrometric determination of trace metals in uranium-plutomium fuel materials

    Atomic absorption spectrometric methods using the electrothermal mode of atomization developed for the determination of Ag, Be, Ca, Cd, Cr, Co, Cu, Fe, Li, Mn, Na, Ni, Sn and Zn in (U, Pu) solution with 4% plutonium have been described. The carbon rod atomizer has been adapted for glove box operation to enable handling of plutonium containing solution samples. Multielement solution standards with graded concentrations of the analytes and fixed concentration of the matrix are used in the standardization process. Nanogram to sub-nanogram quantities of the analytes have been determined with a precision of better than 9% RSD using 5 μl of the sample aliquots. (orig.)

  2. Magnetoresistive multilayers deposited on the AAO membranes

    Malkinski, Leszek M. [Advanced Materials Research Institute, University of New Orleans, 2000 Lakeshore Drive, New Orleans, LA 70148 (United States)]. E-mail: lmalkins@uno.edu; Chalastaras, Athanasios [Advanced Materials Research Institute, University of New Orleans, 2000 Lakeshore Drive, New Orleans, LA 70148 (United States); Vovk, Andriy [Advanced Materials Research Institute, University of New Orleans, 2000 Lakeshore Drive, New Orleans, LA 70148 (United States); Jung, Jin-Seung [Department of Chemistry, Kangnung National University, Kangnung 210702 (Korea, Republic of) ; Kim, Eun-Mee [Department of Chemistry, Kangnung National University, Kangnung 210702 (Korea, Republic of) ; Jun, Jong-Ho [Department of Applied Chemistry, Kunkuk University, Chungju 151747 (Korea, Republic of) ; Ventrice, Carl A. [Advanced Materials Research Institute, University of New Orleans, 2000 Lakeshore Drive, New Orleans, LA 70148 (United States)

    2005-02-01

    Silicon and GaAs wafers are the most commonly used substrates for deposition of giant magnetoresistive (GMR) multilayers. We explored a new type of a substrate, prepared electrochemically by anodization of aluminum sheets, for deposition of GMR multilayers. The surface of this AAO substrate consists of nanosized hemispheres organized in a regular hexagonal array. The current applied along the substrate surface intersects many magnetic layers in the multilayered structure, which results in enhancement of giant magnetoresistance effect. The GMR effect in uncoupled Co/Cu multilayers was significantly larger than the magnetoresistance of similar structures deposited on Si.

  3. ANALYSIS OF SOME ESSENTIAL ELEMENTS IN MEDICINAL PLANTS USED IN AYURVEDA

    Om Prakash Rout

    2013-02-01

    Full Text Available This study presents a preliminary data of occurrence of elemental concentration in medicinal plants i.e Apium graveolens (seed, Sida cordifolia (root, Solanum surattense (whole plant, Tribulus terrestris(fruit and Withania somnifera (root used in Ayurveda, using Atomic absorption spectrometer (AAS following standard procedures. The elemental concentration i.e. Mn, Na, K, Cl, Ca, Cr, Co, Cu, Fe, Pb, Zn, Ni, Cd and Hg were found in various proportions. The data obtained from the study can be used to evaluate the potentiality of these plants in their used for Ayurvedic drugs

  4. Effect of planar doping in Co/SiO2-Ni/Cu/Co structures

    The effect of interfacial planar doping with insulating granular layer in a sandwiched structure was studied. By inserting a thin SiO2-Ni layer into the sandwiched Co/Cu/Co structures, the magnetoresistance curve as a function of the magnetic field changed significantly because of reduction of interlayer coupling and the change of its switching mechanism of the magnetizations by the interface modification. The switching fields are 10 and 60 Oe for the magnetization reversals in two magnetic layers. The MR peaks are square-shaped with the width of about 30 Oe and the peak MR ratio of 3.3%

  5. Multielemental analysis of vegetarian human diets and dietary components by neutron activation

    Two vegetarian diet samples representative of the Indian sub-continent were prepared (in raw form) by the proportionate blending method for adolescent and adult age groups. These along with its components, viz. wheat, rice flours and pulses, were analyzed for 12 minor and trace elements by instrumental neutron activation analysis (INAA) and high resolution γ-ray spectrometry. Bowen's kale was also analyzed to check the accuracy of the method. The concentrations of Br, Co, Cu, Fe, K, Mn and P are comparable to the non-vegetarian American and European diets. Zinc concentrations are however lower than the recommended dietary allowances (RDA) and the western non-vegetarian diets. (orig.)

  6. INAA and ICP-MSHS. Metal pollutants in fish tissues Nile tilapia (Oreochromic niloticus) in Pampulha Lake, Belo Horizonte city, Minas Gerais State, Brazil

    Pampulha Lake, Minas Gerais, Brazil, is being polluted via its tributaries, Sarandi and Ressaca. Instrumental neutron activation analysis and inductively coupled plasma mass spectrometry high resolution were applied to determine Al, As, B, Ba, Co, Cr, Cs, Cu, Fe, K, Mg, Mn, Mo, Na, P, Pb, Rb, Zn and Ti in Nile tilapia fish, Oreochromis niloticus. The organs analyzed were: intestine, spleen, heart, testicle, kidney, liver, gills and muscle. The results demonstrated relatively high concentrations of Al, Co, Cu, Fe, P and Ti in gills, Al and Cu in liver, Al in intestine and Fe in muscle and spleen. (author)

  7. A mineralized breccia pipe in Mohawk Canyon, Arizona; lithologic and geophysical logs

    Hundreds of solution-collapse breccia pipes crop out in northern Arizona. High-grade U ore, and potentially economic concentrations of Ag, Co, Cu, Ni, Pb, and Zn in some pipes, has stimulated mining activity there. More than 900 confirmed and suspected breccia pipes have been mapped by this study. One pipe was chosen for exploration drilling 1984 because it exhibited all preestablished exploration criteria. Five rotary and core holes were drilled into this pipe; they contained mineralized breccia and zones of U-, Cu-, and Ni-mineralized rock

  8. Use of energy dispersive X-ray fluorescence analysis on the characterization and estimation of microelements concentrations in vinasse

    By using the energy dispersive X-ray fluorescence analysis and radioisotopic excitation was possible to evaluate the micro element concentrations of Mn, Fe, Co, Cu and Zn available in solution, carrying out the sample pre-concentrations with chelant agent APDC. The element contents in the particulate material could be also determined through a simple, inexpensive and fast way. This methodology seems to be suitable for the microelements determination in vinasse deriving from different musts, and through the elemental relations is possible to identify the origin of these vinasse, like as deriving from molasses, mixed or juice must. (author). 7 refs, 4 figs, 4 tabs

  9. Determination of trace elements in human hair by neutron activation analysis

    F, Al, Cl, Cr, Fe, Co, Cu, Zn, Se, Ag, I and Au have been determined in human hair with the aid of neutron activation analysis. In comparison to values given in literature the Se concentration of 0.3 ppm is low. Increased concentrations have been found of Cr and Mn in the hair of welders and of F in the hair of persons working with fluorine compounds. Women with mammary or thyroid carcinoma showed higher Zn values. In patients with goitre reduced concentrations of I have been determined. (author)

  10. PIXE analysis of ancient Chinese Changsha porcelain

    Lin, E.K.; Yu, Y.C.; Wang, C.W.; Liu, T.Y.; Wu, C.M.; Chen, K.M.; Lin, S.S

    1999-04-02

    In this work, proton induced X-ray emission (PIXE) method was applied for the analysis of ancient Chinese Changsha porcelain produced in the Tang dynasty (AD 618-907). A collection of glazed potsherds was obtained in the complex of the famous kiln site at Tongguan, Changsha city, Hunan province. Studies of elemental composition were carried out on ten selected Changsha potsherds. Minor and trace elements such as Ti, Mn, Fe, Co, Cu, Rb, Sr, and Zr in the material of the porcelain glaze were determined. Variation of these elements from sample to sample was investigated. Details of results are presented and discussed.

  11. CATALYST-ASSISTED CONVERSION OF PYROLYSIS BIO-OIL INTO FUELS

    Mikulec, Jozef; Polakovičova, Gabriela

    2015-01-01

    The aldol condensation of model compounds furfural and acetone on the selected base catalysts have been performed. The activity of MgO was compared with industrially produced hydrotalcite and the series laboratory prepared hydrotalcites. Si×MAl2O4 hydrotalcites (M = Mg, Zn, Ni, Co, Cu, and Fe) were prepared by the sol-gel method at low calcination temperature of 300°C. The properties of the catalysts were evaluated by XRD and BET technique and they had a mesoporous structure. The aldol co...

  12. Four-state magnetic configuration in a tri-layer asymmetric ring

    Popescu, Horia; Fortuna, Franck; Delaunay, Renaud; Spezzani, Carlo; Lopez-Flores, Victor; Jaouen, Nicolas; Sacchi, Maurizio

    2015-11-01

    Ring-shaped multilayered sub-micron dots have the potential for the development of non-volatile multi-bit devices. We show that a Co/Cu/FeNi asymmetric ring can take four distinct remanent magnetic states, each one stabilized by applying a magnetic field pulse along one of four in-plane orthogonal directions. We use element selective x-ray holography for imaging the Co magnetic configuration following a magnetic pulse. Micro-magnetic simulations support our experimental findings; they also provide an estimate of the system magnetization dynamics, setting out the conditions for further time-resolved experiments.

  13. Activation analysis of particulates emitted from aircraft jet engines

    Particulate matter in emission gas from aircraft jet engines was subjected to instrumental neutron activation analysis and the compositions of trace elements, such as Na, Al, Cl, Sc, V, Cr, Mn, Fe, Co, Cu, Zn, Br, Sb and Th were determined. For comparison, airborne dust samples collected in and around the airport and a soot sample collected in a jet nozzle were also analyzed. The analytical results obtained involve some ambiguous points mainly resulting from the imperfect sampling method. The analytical sensitivity was insufficient because of the too small amount of collected samples. These should be improved in future studies. (auth.)

  14. Imaging of lateral spin valves with soft x-ray microscopy

    Mosendz, O.; Mihajlovic, G.; Pearson, J. E.; Fischer, P.; Im, M.-Y.; Bader, S. D.; Hoffmann, A.

    2009-05-01

    We investigated Co/Cu lateral spin valves by means of high-resolution transmission soft x-ray microscopy with magnetic contrast that utilizes x-ray magnetic circular dichroism (XMCD). No magnetic XMCD contrast was observed at the Cu L{sub 3} absorption edge, which should directly image the spin accumulation in Cu. Although electrical transport measurements in a non-local geometry clearly detected the spin accumulation in Cu, which remained unchanged during illumination with circular polarized x-rays at the Co and Cu L{sub 3} absorption edges.

  15. Heavy metals in some French forest soils : Distribution, origin and controlling factors

    Probst, Anne; Hernandez, Laura; Probst, Jean-Luc; Ulrich, Erwin

    2003-01-01

    The lowest heavy metal contents are observed in acid soils while the highest contents are in the mollic andosol and in the calcaric cambisol. Cr and Ni concentrations increase with depth in all soils, except the podzol. Co, Cu, Zn behaviour depends on the soil. Cu and Zn decrease with depth in some acid soils. Pb and Cd accumulate in all surface horizons. In the dystric planosol and stagnic luvisol, heavy metals accumulate in deep soil horizons (important clay content). The abundance order of...

  16. Trace elements, pesticides and PCBs levels in sediments of a bay influenced by anthropogenic activities (Thermaikos bay, N.W. Aegean Sea)

    Surface sediment samples recovered from the study area over a grid of 13 stations during 1995 were examined for organic carbon, Fe, Cr, Ni, Mn, Zn, Co, Cu, Pb, herbicides, DDTs and polychlorinated biphenyls (PCBs). The organic carbon was obtained according to Gaudette et al. The extraction of the metals was achieved with 2N HCl and the determination of the metal content was performed on a Perkin-Elmer 305B AAS. The pesticides and PCBs after extraction on a Soxhlet apparatus and clean-up on an alumina column were determined by gas chromatography on a Varian 3400 Gas Chromatograph equipped with TSD and ECD

  17. Multi-element analysis of Macedonian wines by inductively coupled plasma–mass spectrometry (ICP–MS) and inductively coupled plasma–optical emission spectrometry (IP–OES) for regional classification

    Ivanova, Violeta; Wiltsche, Helmar; Stafilov, Trajče; Stefova, Marina; Motter, Herber; Lankmayr, Ernst

    2013-01-01

    Major, minor, and trace elements in wines from the Republic of Macedonia were determined in this study. Both inductively coupled plasma–mass spectrometry (ICP-MS) and inductively coupled plasma– optical emission spectrometry (ICP-OES) were used for accurate determination of the concentration of 42 elements (Ag, Al, Au, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Ho, La, Lu, Mg, Mn, Mo, Na, Nd, Ni, P, Pb, Pr, S, Sm, Tb, Ti, Tl, Tm, U, V, Yb, Zn, Zr) in 25 Macedonian white, r...

  18. Inductively coupled plasma - mass spectrometry (ICP-MS) and inductively coupled plasma – optical emission spectrometry (IP-OES) analysis of elements in Macedonian wines

    Ivanova, Violeta; Wiltsche, Helmar; Stafilov, Trajče; Motter, Herber; Stefova, Marina; Lankmayr, Ernst

    2013-01-01

    In this study the major, minor and trace elements in 25 Macedonian white, rose and red wines from different wine regions were determined. Analysis was performed with inductively coupled plasma - mass spectrometry (ICP-MS) and inductively coupled plasma – optical emission spectrometry (ICP-OES) for accurate determination of the concentration of 42 elements (Ag, Al, Au, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Ho, La, Lu, Mg, Mn, Mo, Na, Nd, Ni, P, Pb, Pr, S, Sm, Tb, Ti, T...

  19. Figures of merit of inductively coupled plasma mass spectrometry for compliant analysis of waters and wastes using USEPA standard operating procedures

    The scope of this study is to critically review the performance of the ICP-MS instrumentation and aspects of the analytical methodology for compliant determination of Al, Sb, As, Ba, Be, Cd, Cr, Co, Cu, Fe, Pb, Mn, Ni, Se, Ag, Tl, V, and Zn in surface and subsurface water, soil, sludge, sediments and various solid wastes. The evaluation was performed using conventional and practical figures of analytical merit detailed in using USEPA SW (Solid Waste) 846 procedures and ISO/EC 17025

  20. Erosion resistance in a stationary arc of powder materials on the base of heat resisting alloys

    Minakova, R.V.; Kostenetskaya, L.I.; Krusanova, A.P.; Kukhtikov, V.A.; Smirnov, A.V.; Lugovskaya, E.S. (AN Ukrainskoj SSR, Kiev. Inst. Problem Materialovedeniya)

    1983-08-01

    Comparison investigations of some properties of the Mo-Cu, Mo-Ni(Co)-Cu materials and the W-Cu, W-Ni-Cu compositions used at the present time as well as contact pairs prepared from them is conducted. It is shown that electroerosion wear of the contacts is connected not only with the material properties but also with features of structural changes in the working layer under effect of arc discharge. It is shown also that directed alloying with respect to the origin of phase transition in the electrode material and the medium effect during current commutation promotes electroerosion resistance.

  1. Influence of the Buchim copper leaching factory on the environ around the active Buchim copper mine

    Serafimovski, Todor; Nikolov, Nikolajco; Konzulov, Gerasim; Tasev, Goran; Sarafiloski, Sare

    2014-01-01

    Within this paper we are going to present a review of results for some particular contaminants such are: Co, Cu, Cd, Al, Fe, U etc., until the 2011 as well as review of results of monitoring (2012-2013) following the construction of the copper leaching facility. For the period covering period 1979-2011, in marked contrast, the water from the mine used to be acidic (pH 0.5 mg/L) 24 km downstream, where the River Madenska joins the River Bregalnica. Positive effects in regards to en...

  2. Actividad catalítica de metales de transición en la descomposición de peróxido de hidrógeno

    José G. Carriazo; Luis. F. Bossa-Benavides; Eliana Castillo

    2012-01-01

    This paper compares the catalytic activities of some transition metal ions (Fe3+, Co2+, Cu2+, Ni2+, Zn2+) in the H2O2 decomposition in homogenous and heterogeneous processes, including solid mixed systems (Fe-Cu-Co/Al2O3, Fe-Cu/Al2O3, Fe-Co/Al2O3 and Co-Cu/Al2O3). The solids were characterised by X-ray diffraction to explore evolution of phases or possible changes. Different trends of the catalytic activity were observed: in homogeneous medium the most active species was Fe3+, whereas in hete...

  3. Assorted morphosynthesis: access to multi-faceted nano-architectures from a super-responsive dual π-functional amphiphilic construct.

    Asthana, Deepak; Shukla, Jyoti; Dana, Srikanta; Rani, Varsha; Ajayakumar, M R; Rawat, Kamla; Mandal, Kalyanashis; Yadav, Premlata; Ghosh, Subhasis; Mukhopadhyay, Pritam

    2015-10-25

    An electronically segmented amphiphile was created by conjugating two π-functional units hydroxyquinoline and naphthalenediimide (HQ/NDI) for the first time. The differential electrostatic potential of the π-surfaces, H-bonding units, etc. trigger a manifold response and direct the assembly of a unique collection of seven diverse nano-architectures. Chiral assembly, distinct classes of fibers, 3-D sheets, and metallo-spheres/fibrils with μM levels of Co/Cu/Zn(ii) ions emerged from this new approach of assorted morphosynthesis under ambient conditions. PMID:26194349

  4. A new method for separating first row transition metals and actinides from synthetic melt glass

    A new method was developed for separating Co, Fe, and Sc from complex debris matrices using the extraction chromatography resin DGA. The activation products Co-58, Mn-54, and Sc-46 were used to characterize the separation of the synthetic melt glass solutions. In the separation scheme that was developed, Au, Co, Cu, Fe, Sc, and Ti were separated from the rest of the sample constituents. In this paper, the synthetic melt glass separation method, efficiency, recoveries, and the length of procedure will be discussed. Batch contact adsorption studies for Na and Sc for DGA resin are discussed as well. (author)

  5. Current-induced resonant depinning of a transverse magnetic domain wall in a spin valve nanostrip

    Metaxas, P. J.; Anane, A.; Cros, V.; Grollier, J.; Deranlot, C.; Lemaître, Y.; Xavier, S.; Ulysse, C.; Faini, G.; Petroff, F.; Fert, A.

    2010-11-01

    We study the impact of rf and dc currents on domain wall depinning in the soft layer of a 120 nm wide Co/Cu/NiFe spin valve nanostrip. A strong resonant reduction in the depinning field (from ˜75 to 25 Oe) is observed for rf currents near 3.5 GHz. Notably, the features of the resonant depinning depend not only on the rf current but also on the simultaneously applied dc current. Consequently, we discuss both the role of the adiabatic spin torque at resonance and that of the current generated Oersted fields.

  6. Analysis of standard substance human hair

    The human hair samples as standard substances were analyzed by the neutron activation analysis (NAA) on the miniature neutron source reactor. 19 elements, i.e. Al, As, Ba, Br, Ca, Cl, Cr, Co, Cu, Fe, Hg, I, Mg, Mn, Na, S, Se, V and Zn, were measured. The average content, standard deviation, relative standard deviation and the detection limit under the present research conditions were given for each element, and the results showed that the measured values of the samples were in agreement with the recommended values, which indicated that NAA can be used to analyze standard substance human hair with a relatively high accuracy. (authors)

  7. Thermoelectric properties of p—type Bi—Sb—Te Compositionally Graded thermodelectric materials with different barriers

    GuyingXu; ChangchunGe; 等

    2002-01-01

    In order to find more suitable materials as barriers and to improve the thermoelectric properties,p-type(Bi1-xSbx)2Te3(x=0.85,0.9) two segments compositionally graded thermoelectric materials(CGTM) with different barriers were fabricated by conventional hot pressure method.Metals Fe,Co,Cu and Al were used as barriers between two segments.The effects of different barriers on thermoelectric properties of CGTM were investigated.The results show that metal Fe is more stable and suitable as the barrier.

  8. Thermoelectric properties of p-type Bi-Sb-Te compositionally graded thermoelectric materials with different barriers

    2002-01-01

    In order to find more suitable materials as barriers and to improve the thermoelectric properties, p-type (BiSb)2Te3 (0.85, 0.9) two segments compositionally graded thermoelectric materials (CGTM) with different barriers were fabricated by conventional hot pressure method. Metals Fe, Co, Cu and Al were used as barriers between two segments. The effects of different barriers on thermoelectric properties of CGTM were investigated. The results show that metal Fe is more stable and suitable as the barrier.

  9. Geo-chemical analysis of beach rock samples of Andaman island using energy dispersive X-ray fluorescence (EDXRF) spectrometry

    Elemental concentrations of beach rock samples have been analyzed using non-destructive technique of energy dispersive X-ray fluorescence (EDXRF) spectrometry. The samples were collected from three different locations of Andaman Island. The concentrations of Al, Ca, K, Fe, Ti, Si, V, Co, Cu, Ba, Zn, Pb, Cd and Mn were determined. The geochemical behavior of elements in the region is discussed. Present study shows that elemental concentrations of beach rock samples from Andaman Islands are much below the values of both earth crust and that of Tamilnadu region. However, the Biogenic element (Ca) showed high concentration compared to all other elements. (author)

  10. Analysis of toxic elements in two pigeonpea (Cajanus cajan (L.) Millsp) cultivars, in fertilized soils, by neutron activation

    Samples of whole leaves, from thirty-six plants belonging to two pigeonpea cultivars were analysed by Instrumental Neutron Activation Analysis. Each plant was cultivated under either single dose or double one of some mineral fertilizers, such as, B, Co, Cu, Fe, Mn, Mo, V and Zn, individually, to the soil; besides limestone and phosphorus. The aim of this paper is to evaluate the contribution of these treatments to the increase in the concentrations of As, Sb, Th and U, since these elements can be toxic to plants and animals. (author)

  11. Elemental analysis of some herbal plants used in the treatment of cardiovascular diseases by NAA and AAS

    Elemental analysis of some herbal plants used in the ayurveda for curing of cardiovascular diseases has been performed using the techniques of neutron activation analysis and atomic absorption spectroscopy. The concentration of elements Mn, Na, K and Cl has been estimated by NAA using a 252Cf neutron source and a high purity germanium detector coupled to a multichannel analyzer, while the elements, Ca, Cr, Co, Cu, Fe, Pb, Zn, Ni, Cd and Hg were analysed by ASS using a Perkin Elmer 3100 instrument. (author)

  12. Spin Pumping and Inverse Spin Hall Effect in Platinum: The Essential Role of Spin-Memory Loss at Metallic Interfaces

    Rojas-Sánchez, J. -C.; Reyren, N.; Laczkowski, P.; Savero, W.; Attané, J. -P.; Deranlot, C.; Jamet, M.; George, J.-M.; Vila, L.; Jaffrès, H.

    2013-01-01

    Through combined ferromagnetic resonance, spin-pumping and inverse spin Hall effect experiments in Co|Pt bilayers and Co|Cu|Pt trilayers, we demonstrate consistent values of spin diffusion length $\\ell_{\\rm sf}^{\\rm Pt}=3.4\\pm0.4$ nm and of spin Hall angle $\\theta_{\\rm SHE}^{\\rm Pt}=0.051\\pm0.004$ for Pt. Our data and model emphasize on the partial depolarization of the spin current at each interface due to spin-memory loss. Our model reconciles the previously published spin Hall angle values...

  13. Twenty-eight element concentrations in mane hair samples of adult riding horses determined by particle-induced X-ray emission.

    Asano, Kimi; Suzuki, Kazuyuki; Chiba, Momoko; Sera, Koichiro; Asano, Ryuji; Sakai, Takeo

    2005-11-01

    The concentrations of 28 elements (Al, Br, Ca, Cl, Co, Cu, Cr, Fe, Ga, Hg, K, Mg, Mn, Mo, Na, Nb, Ni, P, Pb, Rb, S, Se, Si, Sr, Ti, V, Y, and Zn) were measured in mane hair by the particle-induced X-ray emission method. Except for Br, Cl, K, S, and P, the trace element concentrations in mane hair of horses are similar to literature values for human hair. The values obtained are not dependent on the horse's age, breed, and sex and could be used as reference values in the assessment of diseases and nutritional status in equines. PMID:16217138

  14. Study of heavy metal toxic pollutants in sewage sludges of different origins from Bombay city

    In order to assess the pollution repercussions of sewage and its alternative productive uses, Instrumental Neutron Activation Analysis (INAA) has been employed for the determination of about 20 elements (As, Au, Ba, Br, Cr, Co, Cu, Eu, Fe, Hf, Hg, K, La, Mg, Mn, Na, P, Sb, Sc, Se, Th, Zn etc.) in sludges from domestic, industrial and municipal areas of Bombay. A comparison of the elemental contents shows significant differences for As, Br, Ba, Co, Cr, Hg, Mn, Sb, Zn etc. An attempt has been made to explain the elemental contents vis-a-vis industrial development and pollution status of the respective locations. (author). 4 refs., 1 tab

  15. The contents of fifteen essential, trace and toxic elements in some green tea samples and in their aqueous extracts

    The content of fifteen elements such as Ca, Mg, Na, K, Mn, Zn, Co, Cu, Cr, Ni, Pd, Cd, Ba and Al were determined in Green Tea samples imported from different countries such as India, China, Kenya and Bangladesh in packets and without packets were purchased from authorized tea dealers in Peshawar. Wet ashing procedures were employed for decomposing the organic matter in the tea samples. Aqueous extract of each green tea sample was also prepared by heating with de-ionized water at 80 /sup o/C on electric heating plates. (author)

  16. Application of total reflection X-ray fluorescence spectrometry for evaluation of macronutrients and micronutrients in sea water

    Marine ecosystem has been subjected to impact of industrialisation and urbanization. The study has been carried out in the creek ecosystem of Mumbai receiving the effluents from industrial and urban settlements. The trace elements such as P, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pb, As, Rb and Sr were analysed in the creek water using TXRF. It was found that the concentration of P, Ca, Mn, Fe, Co, Cu, Zn, Pb and As were found higher in the industrial side of the creek whereas V, Cr and Ni concentration were found higher in the samples collected from the side receiving city effluent. (author)

  17. The structure of decagonal Al-Cu-Co-Si: an electron channelling study

    The planarity of the (00001) planes in the decagonal quasicrystal Al65Cu16Co15Si4 is investigated by a further developed electron channeling technique, which is based on the dependence of the X-ray yield on the direction of the incident electron beam. It is found that Si atoms are located midway between the (00001) planes containing the Co, Cu and Al atoms. This result is discussed in terms of the electronic properties of Al and Si. A straightforward explanation is given for the phase transition of Al65-xCo20Cu15Six from decagonal (x 4.5). (author)

  18. Trace element analysis of human blood serum by neutron activation analysis

    An attempt was made to determine if there is any correlation between trace element concentrations in human blood serum and some specific diseases. The serum samples of the patients suffering from cancer, Down syndrome, and Banti syndrome were analyzed by the neutron activation method and compared with the trace element concentrations observed among clinically healthy men. The cancer patients had concentrations in Rb, Mn, Fe, Co, Cu, Zn, Al and Se below normal. The Down syndrome patients were found to have similar deficiencies in Cr, Mn, Fe, Co, Zn, Cu and Sb. (author)

  19. Coordination chemistry of poly(thioether)borate ligands.

    Riordan, Charles G

    2010-08-01

    This review traces the development and application of the tris(thioether)borate ligands, tripodal ligands with highly polarizable thioether donors. Areas of emphasis include the basic coordination chemistry of the mid-to-late first row transition metals (Fe, Ni, Co, Cu), and the role of the thioether substituent in directing complex formation, the modeling of zinc thiolate protein active sites, high-spin organo-iron and organo-cobalt chemistry, the preparation of monovalent complexes of Fe, Co and Ni, and dioxygen and sulfur activation by monovalent nickel complexes. PMID:20607091

  20. Reducción catalítica de NOx con Pt soportado sobre zeolitas MFI modificadas con Cu, Co, Fe, Mn.

    Sarah Briceño

    2008-05-01

    Full Text Available The selective catalytic reduction of NO by propane in the presence of excess oxygen has been studied over catalysts based on Pt supported on Fe-ZSM-5, Co-ZSM-5, Cu- ZSM-5 and MnZSM-5. Pure Pt based catalysts are highly active, but produce large amounts of N2O. The bimetallic catalyst was found to offer wider temperature window than that of monocatalysts, and show a synergistic effect by combining high stability and activity of Pt catalysts with the high N2 selectivity of Fe, Co, Cu, Mn supported on MFI catalysts.

  1. Cobalt-catalyzed intermolecular C(sp(2))-O cross-coupling.

    Kundu, Debasish; Tripathy, Manisha; Maity, Pintu; Ranu, Brindaban C

    2015-06-01

    Cobalt(II)-catalyzed C(sp(2) )O cross-coupling between aryl/heteroaryl alcohols and vinyl/aryl halides in the presence of Cu(I) has been achieved under ligand-free conditions. In this reaction, copper plays a significant role in transmetalation rather than being directly involved in the CO coupling. This unique Co/Cu-dual catalyst system provides an easy access to a library of aryl-vinyl, heteroaryl-styryl, aryl-aryl, and heteroaryl-heteroaryl ethers in the absence of any ligand or additive. PMID:25926040

  2. Human contribution to trace elements in urban areas as measured in holm oak (Quercus ilex L.) bark.

    Minganti, Vincenzo; Drava, Giuliana; Giordani, Paolo; Malaspina, Paola; Modenesi, Paolo

    2016-06-01

    The effect of human activities on the presence of trace elements in the atmosphere was evaluated by analyzing samples of holm oak bark, collected in Italy in a large city, in a small town, and in a reference area, scarcely inhabited. In all cases, point sources of pollution were excluded (e.g., industries and incinerators). The concentrations of As, Cd, Co, Cu, Fe, Mn, Ni, Pb, V, and Zn were measured using inductively coupled plasma optical emission spectrometry (ICP-OES). The element concentrations in the small town are not different from the reference area, except for Pb and Cu, while the samples collected in the large city show higher concentrations of Co, Cu, Fe, Ni, Pb, V, and Zn with respect to the rural area. In particular, the Pb levels in the large city are approximately 16 times higher than in the reference site, and five times higher than in the small town. Most element concentrations are correlated in the large city, while in the reference site, only a few significant correlations between elements were found. Even in the absence of specific sources of pollution, populations living in big cities are exposed to higher concentrations of trace elements than those living in rural environments or in small urban centers. PMID:27000118

  3. Application of paper chromatography to the determination of some elements in minerals and rocks; Application de la chromatographie sur papier a la determination de certains elements dans les mineraux et les roches

    Agrinier, H. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1964-11-01

    This publication describes our work in applying paper chromatography to the fields of mineralogy and geology. We have studied the separation and determination of the following elements: Nb, Ta, Ti, Co, Cu, Mn, Sn, Ge, As, Sb, Bi, U, Th, Be, Au, Pb, Zn, V and Mo. The development of separation methods for these various elements has led us to solve many interference problems. These methods make it possible to separate and measure mineral components. They also enable us to search for trace elements in ores, rocks soils and carbonaceous materials. Finally let us point out that this technique may equally be used for analysis in very radioactive environment. (author) [French] Dans cette etude, nous etendons le champ d'application de la chromatographie sur papier aux domaines de la mineralogie et de la geologie. Nous avons etudie la separation et la determination des elements suivants: Nb, Ta, Ti, Co, Cu, Mn, Sn, Ge, As, Sb, Bi, U, Th, Be, Au, Pb, Zn, V et Mo. La mise au point des methodes de separation concernant ces differents elements nous a amenes a resoudre de nombreux problemes d'interference. Ces methodes permettent la separation et le dosage des constituants des mineraux, ainsi que la recherche d'elements en traces dans les minerais, les roches, les sols et les materiaux carbonnes. Signalons pour terminer que cette technique peut egalement trouver son utilisation dans le domaine de l'analyse en milieu tres radio-actif. (auteur)

  4. Total and labile metals in surface sediments of the tropical river-estuary system of Marabasco (Pacific coast of Mexico): Influence of an iron mine.

    Marmolejo-Rodríguez, Ana Judith; Prego, Ricardo; Meyer-Willerer, Alejandro; Shumilin, Evgueni; Cobelo-García, Antonio

    2007-01-01

    Marabasco is a tropical river-estuary system comprising the Marabasco river and the Barra de Navidad Lagoon. The river is impacted by the Peña Colorada iron mine, which produces 3.5 million tons of pellets per year. Thirteen surface sediment samples were collected in May 2005 (dry season) in order to establish background levels of Al, Cd, Co, Cu, Fe, Ni, Pb, and Zn in the system and to ascertain the potential mobility of metals in the sediments. Analyses were carried out in the fraction finer than 63 microm, and labile metals extracted according the BCR procedure. Certified reference materials were used for validation of methods. Total concentrations of Cd, Co, Cu, Ni, Pb, and Zn were in the range of 0.05-0.34, 6-95, 0.7-31, 9-26, 2-18, and 53-179 mgkg(-1), respectively; Al and Fe ranges of 24-127, and 26-69 mgg(-1) correspondingly. Cadmium was found to be significantly labile in the sediments (20-100%), followed by Co (0-35%), Ni (3-16%) and Zn (0-25%), whereas the labile fraction for Cu, Fe and Pb was almost negligible (<4%). According with the total metal concentrations, background levels and normalised enrichment factors (NEF) of the metals studied, the impact of the Peña Colorada iron mine on the Marabasco system is lower than expected when compared with other similar World systems influenced by mining activities. PMID:17997460

  5. Total and labile metals in surface sediments of the tropical river-estuary system of Marabasco (Pacific coast of Mexico): Influence of an iron mine

    Marmolejo-Rodriguez, Ana Judith [Centro Interdisciplinario de Ciencias Marinas, (IPN) La Paz, B.C.S. (Mexico); Instituto de Investigaciones Marinas, (CSIC), Vigo (Spain)], E-mail: amarmole@ipn.mx; Prego, Ricardo [Instituto de Investigaciones Marinas, (CSIC), Vigo (Spain); Meyer-Willerer, Alejandro [Centro Universitario de Investigaciones Oceanologicas, Universidad de Colima, Col. (Mexico); Shumilin, Evgueni [Centro Interdisciplinario de Ciencias Marinas, (IPN) La Paz, B.C.S. (Mexico); Cobelo-Garcia, Antonio [Instituto de Investigaciones Marinas, (CSIC), Vigo (Spain)

    2007-07-01

    Marabasco is a tropical river-estuary system comprising the Marabasco river and the Barra de Navidad Lagoon. The river is impacted by the Pena Colorada iron mine, which produces 3.5 million tons of pellets per year. Thirteen surface sediment samples were collected in May 2005 (dry season) in order to establish background levels of Al, Cd, Co, Cu, Fe, Ni, Pb, and Zn in the system and to ascertain the potential mobility of metals in the sediments. Analyses were carried out in the fraction finer than 63 {mu}m, and labile metals extracted according the BCR procedure. Certified reference materials were used for validation of methods. Total concentrations of Cd, Co, Cu, Ni, Pb, and Zn were in the range of 0.05-0.34, 6-95, 0.7-31, 9-26, 2-18, and 53-179 mg kg{sup -1}, respectively; Al and Fe ranges of 24-127, and 26-69 mg g{sup -1} correspondingly. Cadmium was found to be significantly labile in the sediments (20-100%), followed by Co (0-35%), Ni (3-16%) and Zn (0-25%), whereas the labile fraction for Cu, Fe and Pb was almost negligible (<4%). According with the total metal concentrations, background levels and normalised enrichment factors (NEF) of the metals studied, the impact of the Pena Colorada iron mine on the Marabasco system is lower than expected when compared with other similar World systems influenced by mining activities.

  6. Total and labile metals in surface sediments of the tropical river-estuary system of Marabasco (Pacific coast of Mexico): Influence of an iron mine

    Marabasco is a tropical river-estuary system comprising the Marabasco river and the Barra de Navidad Lagoon. The river is impacted by the Pena Colorada iron mine, which produces 3.5 million tons of pellets per year. Thirteen surface sediment samples were collected in May 2005 (dry season) in order to establish background levels of Al, Cd, Co, Cu, Fe, Ni, Pb, and Zn in the system and to ascertain the potential mobility of metals in the sediments. Analyses were carried out in the fraction finer than 63 μm, and labile metals extracted according the BCR procedure. Certified reference materials were used for validation of methods. Total concentrations of Cd, Co, Cu, Ni, Pb, and Zn were in the range of 0.05-0.34, 6-95, 0.7-31, 9-26, 2-18, and 53-179 mg kg-1, respectively; Al and Fe ranges of 24-127, and 26-69 mg g-1 correspondingly. Cadmium was found to be significantly labile in the sediments (20-100%), followed by Co (0-35%), Ni (3-16%) and Zn (0-25%), whereas the labile fraction for Cu, Fe and Pb was almost negligible (<4%). According with the total metal concentrations, background levels and normalised enrichment factors (NEF) of the metals studied, the impact of the Pena Colorada iron mine on the Marabasco system is lower than expected when compared with other similar World systems influenced by mining activities

  7. Strain field due to transition metal impurities in Ni and Pd

    Hitesh Sharma; S Prakash

    2003-01-01

    The strain field due to body centered substitutional transition metal impurities in Ni and Pd metals are investigated. The calculations are carried out in the discrete lattice model of the metal using Kanzaki lattice static method. The effective ion–ion interaction potential due to Wills and Harrison is used to evaluate dynamical matrix and the impurity-induced forces. The results for atomic displacements due to 3d, 4d and 5d impurities (Fe, Co, Cu, Nb, Mo, Pd, Pt and Au) in Ni and (Fe, Co, Cu, Ni, Nb, Mo, Pt and Au) impurities in Pd are given up to 25 NN’s of impurity and these are compared with the available experimental data. The maximum displacements of 4.6% and 3.8% of 1NN distance are found for NiNb and PdNb alloys respectively, while the minimum displacements of 0.63% and 0.23% of 1NN distance are found for NiFe and PdFe alloys respectively. Except for Cu, the atomic displacements are found to be proportional to the core radii and d state radius. The relaxation energies for 3d impurities are found less than those for 4d and 5d impurities in Ni and Pd metals. Therefore, 3d impurities may easily be solvable in these metals.

  8. Anthropogenic contamination of metals in sediments of the Santa Rosalía harbor, Baja California peninsula.

    Shumilin, Evgueni; Jiménez-Illescas, Ángel Rafael; López-López, Silverio

    2013-03-01

    To know the environment impact on a harbor of the Santa Rosalía port on the Baja California peninsula, the concentrations of metals (Cd, Co, Cu, Mn, Pb, U and Zn) in harbor sediments were determined for 13 stations and compared with their average upper Earth´s crust abundance. The mean enrichment factors, calculated using Al as a normalizer, were higher than the unity for Ag, Ba, Bi, Cd, Co, Cu, Mn, Ni, Pb, Sb, U, V and Zn. Concentrations of slightly enriched Cd in the sediments are below the effect range low (ERL) sediment quality guidelines value only at three stations. The levels of Pb in the harbor sediments at four stations (1, 6, 9 and 11) are between the ERL (46.7 mg kg(-1)) and the effect range medium (ERM) (218 mg kg(-1)), and Pb content in the rest of the sediment samples is higher than the ERM, demonstrating the high extent of the anthropogenic impact of this metal on the sedimentary environment. The total concentrations of the potentially toxic elements Cu (3,390 ± 804 mg kg(-1)) and Zn (1,916 ± 749 mg kg(-1)) very strongly exceed their ERM, showing a high possibility of toxicological danger for marine biota, living inside or entering the harbor. PMID:23277367

  9. Direct evidence for the nature of core-level photoemission satellites using angle-resolved photoemission extended fine structure

    Photoemission satellites from several systems have been found to exhibit exactly the same angle-resolved photoemission extended fine structure (ARPEFS) as found in the main peaks, when referred to the equivalent photoelectron wave number k for their own photoelectrons. This provides a direct and powerful method for experimentally determining the angular momentum parameters and the intrinsic/extrinsic nature of core-level photoemission satellites. We present ARPEFS satellite data for nitrogen 1s line in c(2x2)N2/Ni(100), the nickel 3p line in clean nickel (111), the carbon 1s lines in (√(3)x√(3))R30 CO/Cu(111) and p2mg(2x1)CO/Ni(110), and the cobalt 1s line in p(1x1) Co/Cu(100). For the last two cases the open-quotes satelliteclose quotes structure is actually the low-energy tail of a Doniach-Sunjic line shape. The satellite peaks and the tails of the Doniach-Sunjic line shapes exhibit ARPEFS curves that in all cases except one indicate angular-momentum parameters identical to the main peak and an intrinsic nature. copyright 1997 The American Physical Society

  10. A study on toxic and essential elements in wheat grain from the Republic of Kazakhstan.

    Tattibayeva, Damira; Nebot, Carolina; Miranda, Jose M; Abuova, Altynai B; Baibatyrov, Torebek A; Kizatova, Maigul Z; Cepeda, Alberto; Franco, Carlos M

    2016-03-01

    Little information is currently available about the content of different elements in wheat samples from the Republic of Kazakhstan. The concentrations of toxic (As, Cd, Cr, Hg, Pb, and U) and essential (Co, Cu, Fe, Mn, Ni, Se, and Zn) elements in 117 sampled wheat grains from the Republic of Kazakhstan were measured. The results indicated that the mean and maximum concentrations of most investigated elements (As, Cd, Co, Cr, Mn, Se, Pb, and U) were higher in samples collected from southern Kazakhstan. The mean and maximum concentrations of toxic elements such as As, Cd, Hg, and Pb did not exceed levels specified by European, FAO, or Kazakh legislation, although the hazard quotient (HQ) values for Co, Cu, Mn, and Zn were higher than 1 and the hazard index (HI) was higher than 1 for samples collected from all areas of Kazakhstan. This indicates that there should be concern about the potential hazards of the combination of toxic elements in Kazakh wheat. PMID:26573314

  11. Health risk assessment of urban population exposure to contaminants in the soils of the Southern Kuzbass

    Osipova, N. A.; Tarasova, N. P.; Osipov, K. Yu.; Maximova, D. I.

    2015-11-01

    This study concerns the human health risk due to exposure of Co, Cu, As, Mn contained in soils of the Southern Kuzbass, where the coal industry is developed. Soil samples of 200 were taken in Mezhdurechensk - city with intensive coal mining and processing industries. The content of heavy metals in samples were determined using the electron spectroscopy. Several samples were also investigated by methods of the instrumental neutron activation analysis (INAA) and the inductively coupled plasma mass spectrometry (ICP-MS). With regard to the effects of heavy metals on the adult population health the total Hazard Index (HI) for ingestion and inhalation routes was 0.87×10-1 and 7.8×10-1 respectively. According to the contribution of Co, Cu, As, Mn to the total HI the elements form the decreasing series Mn (0,42-0,50)> Co (0.18-0.20)> Cu (0,13-0,19 )> As (0,05-0,09). These chemical elements are present in the organic and inorganic forms in coals and coal wastes. Ranking the city territory has shown that administrative districts have different HI values (8.4 10-1 - 8.8 10-1). When analyzing the human health risks of coal mining and coal-processing enterprises the impact of heavy metals as components of coals and combustion products should be taken into account.

  12. Single Molecule Mechanochemistry

    Li, Shaowei; Zhang, Yanxing; Ho, Wilson; Wu, Ruqian; Ruqian Wu, Yanxing Zhang Team; Wilson Ho, Shaowei Li Team

    Mechanical forces can be used to trigger chemical reactions through bending and stretching of chemical bonds. Using the reciprocating movement of the tip of a scanning tunneling microscope (STM), mechanical energy can be provided to a single molecule sandwiched between the tip and substrate. When the mechanical pulse center was moved to the outer ring feature of a CO molecule, the reaction rate was significantly increased compared with bare Cu surface and over Au atoms. First, DFT calculations show that the presence of CO makes the Cu cavity more attractive toward H2 Second, H2 prefers the horizontal adsorption geometry in the Cu-Cu and Au-Cu cavities and no hybridization occurs between the antibonding states of H2 and states of Cu atoms. While H2 loses electrons from its bonding state in all three cavities, the filling of its anti-bonding state only occurs in the CO-Cu cavity. Both make the CO-Cu cavity much more effectively to chop the H2 molecule. Work was supported by the National Science Foundation Center for Chemical Innovation on Chemistry at the Space-Time Limit (CaSTL) under Grant No. CHE-1414466.

  13. Effects of oxygen and carbon on the magnetic properties and microstructure of Sm2Co17 permanent magnets

    TIAN Jianjun; ZHANG Shengen; QU Xuanhui

    2007-01-01

    The research on the sintered Sm2Co17 permanent magnets prepared by metal injection molding is still at the exploratory stage. Carbon and oxygen are two key factors that influence the magnetic properties. In this article, the effects of oxygen and carbon on the properties and microstructure of the magnets have been studied. The results indicate that oxygen consumes the effective Sm content of the magnets and forms Sm2O3-the non-magnetism phase, which result in the deterioration of the magnetic properties. Besides, the magnetic properties decrease in evidence with increasing carbon content. The main factor that affects the magnetic properties is the deterioration of the microstructure of the magnets. The Sm(Co, Cu)5 phase decreases, whereas the cell size increases with the increase of the carbon content. When the carbon content is above 0.43 wt.%, the Sm(Co, Cu)5 phase is not enough to form a uniform cellular microstructure. Thus the magnetic properties disappear. ZrC is detected in the magnets by XRD when the carbon content is above 0.21 wt.%. ZrC also reduces the properties of the magnets.

  14. Spontaneous incorporation of gold in palladium-based ternary nanoparticles makes durable electrocatalysts for oxygen reduction reaction

    Wang, Deli; Liu, Sufen; Wang, Jie; Lin, Ruoqian; Kawasaki, Masahiro; Rus, Eric; Silberstein, Katharine E.; Lowe, Michael A.; Lin, Feng; Nordlund, Dennis; Liu, Hongfang; Muller, David A.; Xin, Huolin L.; Abruña, Héctor D.

    2016-06-01

    Replacing platinum by a less precious metal such as palladium, is highly desirable for lowering the cost of fuel-cell electrocatalysts. However, the instability of palladium in the harsh environment of fuel-cell cathodes renders its commercial future bleak. Here we show that by incorporating trace amounts of gold in palladium-based ternary (Pd6CoCu) nanocatalysts, the durability of the catalysts improves markedly. Using aberration-corrected analytical transmission electron microscopy in conjunction with synchrotron X-ray absorption spectroscopy, we show that gold not only galvanically replaces cobalt and copper on the surface, but also penetrates through the Pd-Co-Cu lattice and distributes uniformly within the particles. The uniform incorporation of Au provides a stability boost to the entire host particle, from the surface to the interior. The spontaneous replacement method we have developed is scalable and commercially viable. This work may provide new insight for the large-scale production of non-platinum electrocatalysts for fuel-cell applications.

  15. Elemental Composition and Geochemical Characteristics of Iron-Manganese Nodules in Main Soils of China

    TAN Wen-Feng; LIU Fan; LI Yong-Hua; HU Hong-Qing; HUANG Qiao-Yun

    2006-01-01

    Elemental composition and geochemical characteristics of iron-manganese nodules from nine main soils in China were studied by chemical and multivariate statistical analyses to better understand the reactions and functions of ironmanganese nodules in soils and sediment. Compared to the corresponding soils, Mn, Ba, Cd, Co and Pb had strong accumulation, Ni had moderate accumulation, while Ca, Cu, Fe, Na, P, Sr and Zn accumulated to a minor degree in the iron-manganese nodules. In contrast, Si, Al, K, Mg and Ti were reduced in the iron-manganese nodules. The contents of Ba, Cd, Co, Cu, Ni, Pb and Zn were positively and significantly correlated with that of MnO2 in the iron-manganese nodules, while the contents of Cr, Cu, Ni, Pb and Zn were positively and significantly correlated with that of Fe2O3 in soils. Based on a principle component analysis, the elements of iron-manganese nodules were divided into four groups: 1)Mn, Ba, Cd, Co, Cu, Li, Ni, Pb and Zn that were associated with Mn oxides, 2) Fe, Cr and P that were associated with Fe oxides, 3) Si, K, and Mg that were included in the elemental composition of phyllosilicate, and 4) Ca, Na, Al and Ti that existed in todorokite, birnessite, lithiophorite and phyllosilicate. It was suggested that accumulation, mineralization and specific adsorption were involved in the formation processes of soil iron-manganese nodules.

  16. Changes in trace elements of cerebrospinal fluid after subarachnoid hemorrhage, and effects of trace elements on vasospasm

    Sato, N.; Kuroda, K.; Suzuki, M.; Ogawa, A.; Sera, K

    1999-04-02

    Various causal factors have been proposed for cerebral vasospasm after subarachnoid hemorrhage (SAH), such as serotonin, acetylcholine, angiotensin, thrombin and thromboxane A2. However, none of them explain the whole pathomechanism of vasospasm. To evaluate the role of trace elements on vasospasm, we have examined these sequential changes in the cerebrospinal fluid (CSF) after SAH by PIXE, and have investigated the relation between trace elements and vasospasm. We obtained the CSF samples from cisternal drainage in patients with SAH who underwent radical surgery within 48 h from the onset. The drainage was placed into basal cisterns at the end of the operation. Three sampling times (3-5, 7-9 and 12-14 days from the onset) has been scheduled because vasospasm is likely to occur from day 4 to day 14 after the onset. In this study, we focused on the levels of Mg, Ca, Mn, Al, Zn, P, Pb, Sr, Br, Co, Cu, Si, Ti, Mn,Co, Cu, Zn, Br, Sr, Mo and Pb, and we found a significantly lower level of Mg in the CSF of patients with vasospasm on days 7-9 after the onset. These results suggest that Mg in the CSF may ameliorate vasoconstriction due to Ca in the pathomechanism of vasospasm.

  17. Heavy metal removal from sludge with organic chelators: Comparative study of N, N-bis(carboxymethyl) glutamic acid and citric acid.

    Suanon, Fidèle; Sun, Qian; Dimon, Biaou; Mama, Daouda; Yu, Chang-Ping

    2016-01-15

    The applicability and performance of a new generation of biodegradable chelator, N, N-Bis(carboxymethyl) glutamic acid (GLDA), for extracting heavy metals from sewage sludge was carried out and compared with citric acid (CA). Targeted metals included Cd, Co, Cu, Zn, Ni and Cr, and their contents in the raw sludge were 63.1, 73.4, 1103.2, 2060.3, 483.9 and 604.1 mg kg(-1) (dry sludge basis), respectively. Metals were divided into six fractions including water soluble, exchangeable, carbonates bound, Fe-Mn bound, organic matters bound and residual fraction via chemical fractionation. Washing results showed that in general GLDA exhibited better performance compared with CA, with removal efficiency of 83.9, 87.3, 81.2, 85.6, 89.3 and 90.2% for Cd, Co, Cu, Zn, Ni and Cr, respectively at equilibrium pH = 3.3. Residual metals were better stabilized in the GLAD-washed sludge than in the CA-washed sludge, and were mostly tightly bonded to the residual fraction. Furthermore, CA promoted phosphorus (P) release while GLDA had an opposite effect and tended to retain P within sludge, which could be beneficial for further application in agricultural use. Findings from this study suggested that GLDA could be a potential replacement for refractory and less environmentally-friendly chelators in the extraction of metals from sludge. PMID:26520041

  18. Determination of nickel, cobalt, copper, thorium and uranium in high-purity zinc metal by ICP-MS with on-line matrix separation

    Traces of Co, Cu, Ni, Th and U in high-purity zinc metal were determined by inductively coupled plasma mass spectrometry (ICP-MS) in combination with flow-injection (FI) on-line matrix separation (FI-ICP-MS). The anion-exchange separation method of an HCl system was applied to the separation of Ni, Co, Cu, Th and U from zinc matrix. The matrix element, zinc, was adsorbed on an anion-exchange (BIO·RAD AG1-X8) mini-column (2.0 mm i.d. x 300 mm bed length), while the analytes were directly introduced into the ICP-MS. The following detection limits (in ng g-1) were obtained: Ni, 3.1; Co, 1.2; Cu, 4.0; Th, 0.12 and U, 0.48. The reproducibility has proved to be satisfactory with a relative standard deviation of less than 5% (at the 10 ng ml-1 level, n=3). The method was successfully applied to determining trace impurities in three 6 and 7 nines grade of high-purity zinc metals and in three standard reference materials of high-purity zinc metal samples (from NIST). (author)

  19. Spontaneous incorporation of gold in palladium-based ternary nanoparticles makes durable electrocatalysts for oxygen reduction reaction.

    Wang, Deli; Liu, Sufen; Wang, Jie; Lin, Ruoqian; Kawasaki, Masahiro; Rus, Eric; Silberstein, Katharine E; Lowe, Michael A; Lin, Feng; Nordlund, Dennis; Liu, Hongfang; Muller, David A; Xin, Huolin L; Abruña, Héctor D

    2016-01-01

    Replacing platinum by a less precious metal such as palladium, is highly desirable for lowering the cost of fuel-cell electrocatalysts. However, the instability of palladium in the harsh environment of fuel-cell cathodes renders its commercial future bleak. Here we show that by incorporating trace amounts of gold in palladium-based ternary (Pd6CoCu) nanocatalysts, the durability of the catalysts improves markedly. Using aberration-corrected analytical transmission electron microscopy in conjunction with synchrotron X-ray absorption spectroscopy, we show that gold not only galvanically replaces cobalt and copper on the surface, but also penetrates through the Pd-Co-Cu lattice and distributes uniformly within the particles. The uniform incorporation of Au provides a stability boost to the entire host particle, from the surface to the interior. The spontaneous replacement method we have developed is scalable and commercially viable. This work may provide new insight for the large-scale production of non-platinum electrocatalysts for fuel-cell applications. PMID:27336795

  20. Contribution to the study of a method for measuring continuously the isotopic effect. The search for an isotopic effect during the reduction of cuprous oxide by a 12CO - 14CO mixture (1962)

    The determination of an isotopic effect between the two reactions: 12CO + Cu2O → 12CO2 + 2 Cu 'light' reaction 14CO + Cu2O → 14CO2 + 2 Cu 'heavy' reaction is possible if the respective kinetics are known. The condensation, during the reaction, of the carbon dioxide formed, and the measurement as a function of time of the residual carbon monoxide pressure, makes it possible to deduce, uninterruptedly, the 'light' reaction kinetics. The 'heavy' reaction kinetics are obtained by measuring continuously, in situ, the radioactivity of the residual reactant gas as a function of the time. The apparatus used for this is a plastic scintillator counter. A calibration curve of the measured radioactivity as a function of the reactant gas pressure in the absence of reaction makes it possible to compare the kinetics of the 'light' and 'heavy' reactions. The reaction temperature is chosen such that the reaction rate is sufficiently slow, so that the variation of the radioactivity during unit counting time is negligible. (author)

  1. Electrochemical oxidation of pulp and paper making wastewater assisted by transition metal modified kaolin

    The electrochemical oxidation of pulp and paper making wastewater assisted by transition metal (Co, Cu) modified kaolin in a 200 ml electrolytic batch reactor with graphite plate as electrodes was investigated. H2O2, which produced on the surface of porous graphite cathode, would react with the catalysts to form strong oxidant (hydroxyl radicals) that can in turn destruct the pollutants adsorbed on the surface of kaolin. The transition metal (Co, Cu) modified kaolin was also characterized by XRD and SEM before and after the modification and the results showed that the transition metals were completely supported on kaolin and formed a porous structure with big BET surface. The mechanism was proposed on the basis of XPS analysis of the catalyst after the degradation process. Series of experiments were also done to prove the synergetic effect of the combined oxidation system and to find out the optimal operating parameters such as initial pH, current density and amount of catalyst. From the results it can be founded that when the initial pH was at 3, current density was 30 mA cm-2; catalyst dose was 30 g dm-3, COD (chemical oxygen demand) removal could reach up to 96.8% in 73 min

  2. Identifying Hot-Spots of Metal Contamination in Campus Dust of Xi’an, China

    Chen, Hao; Lu, Xinwei; Gao, Tianning; Chang, Yuyu

    2016-01-01

    The concentrations of heavy metals (As, Ba, Co, Cr, Cu, Mn, Ni, Pb, V, and Zn) in campus dust from kindergartens, elementary schools, middle schools, and universities in the city of Xi’an, China, were determined by X-ray fluorescence spectrometry. The pollution levels and hotspots of metals were analyzed using a geoaccumulation index and Local Moran’s I, an indicator of spatial association, respectively. The dust samples from the campuses had metal concentrations higher than background levels, especially for Pb, Zn, Co, Cu, Cr, and Ba. The pollution assessment indicated that the campus dusts were not contaminated with As, Mn, Ni, or V, were moderately or not contaminated with Ba and Cr and were moderately to strongly contaminated with Co, Cu, Pb, and Zn. Local Moran’s I analysis detected the locations of spatial clusters and outliers and indicated that the pollution with these 10 metals occurred in significant high-high spatial clusters, low-high, or even high-low spatial outliers. As, Cu, Mn, Ni, Pb, V, and Zn had important high-high patterns in the center of Xi’an. The western and southwestern regions of the study area, i.e., areas of old and high-tech industries, have strongly contributed to the Co content in the campus dust. PMID:27271645

  3. Distribution of Some Geochemical Elements in the Surface Sediment of Kerteh Mangrove Forest, Terengganu, Malaysia

    Surface sediments collected from two transects (30 sampling points) in the Kerteh mangrove forest had been analyzed for Co, Cu, Pb, Zn and Cr concentrations with the Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The average concentration of Co was 8.91±1.89 μg/ g dry weight, Cu was 29.0±12.8 μg/ g dry weight, Pb was 11.7±6.85 μg/ g dry weight, Zn was 22.3±13.7 μg/ g dry weight and Cr was 13.2±9.07 μg/ g dry weight. Their concentrations are significantly higher near the front mangrove and decline as the sampling points of each transect near the back mangrove area. The calculated enrichment factors (EF) obtained for Zn and Cr can be considered to have the terigeneous in sources while Co, Cu and Pb, which had slightly higher value, were probably influenced by anthropogenic input. (author)

  4. Macrocyclic effects upon isomeric CuIIMII and MIICuII cores. Formation with unsymmetric phenol-based macrocyclic ligands

    Masami Yonemura; Yuuki Nakamura; Naoki Usuki; Hisashi Okawa

    2000-06-01

    This paper discusses coordination-position isomeric MIICuII and CuIIMII complexes, using unsymmetric dinucleating macrocycles (Lm;n)2- ((L2;2)2-, (L2;3)2- and (L2;4)2- that comprise two 2-(N-methyl)-aminomethyl-6-iminomethyl-4-bromophenonate entities, combined through the ethylene chain ( = 2) between the two amine nitrogens and through the ethylene, trimethylene or tetramethylene chain ( = 2, 3 or 4) between the two imine nitrogens. The macrocycles have dissimilar N(amine)2O2 and N(imine)2O2 metal-binding sites sharing the phenolic oxygens. The reaction of the mononuclear CuII precursors, [Cu(L2;2)], [Cu(L2;2)] and [Cu(L2;2)], with a MII perchlorate and a MII acetate salt formed (acetato)MII CuII complexes:[CoCu(L2;2)(AcO)]ClO4 0 5H2O] (1), [NiCu(L2;2) (AcO)]ClO4 (2), [ZnCu(L2;2((AcO)]ClO4 (3), [CoCu(L2;3)(AcO)]ClO4 0 5H2O (4), [NiCu(L2;3)(AcO)]ClO4 (5), [ZnCu(L2;3)(AcO)]ClO4 0 5H2O (6), [CoCu(L2;4)(AcO)(DMF)]ClO4 (7), [NiCu(L2;4)(AcO)]ClO4 2DMF (8) and [ZnCu(L2;4)(AcO)]ClO4 (9) (the formulation [MM (Lm;n)]2+ means that M resides in the aminic site and M in the iminic site). The site selectivity of the metal ions is demonstrated by X-ray crystallographic studies for 2 MeOH, 3, 5, 7, and 9. An (acetato)CuIIZnII complex, [CuZn(L2;3)(AcO)]ClO4 (10), was obtained by the reaction of [PbCu(L2;3)]-(ClO4)2 with ZnSO4 4H2O, in the presence of sodium acetate. Other complexes of the CuIIMII type were thermodynamically unstable to cause a scrambling of metal ions. The Cu migration from the iminic site to the aminic site in the synthesis of 10 is explained by the `kinetic macrocyclic effect’. The coordination-position isomers, 6 and 10, are differentiated by physicochemical properties.

  5. Surface distribution of dissolved trace metals in the oligotrophic ocean and their influence on phytoplankton biomass and productivity

    Pinedo-González, Paulina

    2015-10-25

    The distribution of bioactive trace metals has the potential to enhance or limit primary productivity and carbon export in some regions of the world ocean. To study these connections, the concentrations of Cd, Co, Cu, Fe, Mo, Ni, and V were determined for 110 surface water samples collected during the Malaspina 2010 Circumnavigation Expedition (MCE). Total dissolved Cd, Co, Cu, Fe, Mo, Ni, and V concentrations averaged 19.0 ± 5.4 pM, 21.4 ± 12 pM, 0.91 ± 0.4 nM, 0.66 ± 0.3 nM, 88.8 ± 12 nM, 1.72 ± 0.4 nM, and 23.4 ± 4.4 nM, respectively, with the lowest values detected in the Central Pacific and increased values at the extremes of all transects near coastal zones. Trace metal concentrations measured in surface waters of the Atlantic Ocean during the MCE were compared to previously published data for the same region. The comparison revealed little temporal changes in the distribution of Cd, Co, Cu, Fe, and Ni over the last 30 years. We utilized a multivariable linear regression model to describe potential relationships between primary productivity and the hydrological, biological, trace nutrient and macronutrient data collected during the MCE. Our statistical analysis shows that primary productivity in the Indian Ocean is best described by chlorophyll a, NO3, Ni, temperature, SiO4, and Cd. In the Atlantic Ocean, primary productivity is correlated with chlorophyll a, NO3, PO4, mixed layer depth, Co, Fe, Cd, Cu, V, and Mo. The variables salinity, temperature, SiO4, NO3, PO4, Fe, Cd, and V were found to best predict primary productivity in the Pacific Ocean. These results suggest that some of the lesser studied trace elements (e.g., Ni, V, Mo, and Cd) may play a more important role in regulating oceanic primary productivity than previously thought and point to the need for future experiments to verify their potential biological functions.

  6. Chelating resin immobilizing carboxymethylated polyethyleneimine for selective solid-phase extraction of trace elements: Effect of the molecular weight of polyethyleneimine and its carboxymethylation rate.

    Kagaya, Shigehiro; Kajiwara, Takehiro; Gemmei-Ide, Makoto; Kamichatani, Waka; Inoue, Yoshinori

    2016-01-15

    The effect of the molecular weight of polyethyleneimine (PEI), defined as a compound having two or more ethyleneamine units, and of its carboxymethylation rate (CM/N), represented by the ratio of ion-exchange capacity to the amount of N on the resin, on the selective solid-phase extraction ability of the chelating resin immobilizing carboxymethylated (CM) PEI was investigated. The chelating resins (24 types) were prepared by immobilization of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, PEI300 (MW=ca. 300), and PEI600 (MW=ca. 600) on methacrylate resins, followed by carboxymethylation with various amounts of sodium monochloroacetate. When resins with approximately the same CM/N ratio (0.242-0.271) were used, the recovery of Cd, Co, Cu, Fe, Ni, Pb, Ti, Zn, and alkaline earth elements increased with increasing the molecular weight of PEIs under acidic and weakly acidic conditions; however, the extraction behavior of Mo and V was only slightly affected. This was probably due to the increase in N content of the resin, resulting in an increase in carboxylic acid groups; the difference in the molecular weight of PEIs immobilized on the resin exerts an insignificant influence on the selective extraction ability. The CM/N ratio considerably affected the extraction behavior for various elements. Under acidic and neutral conditions, the recovery of Cd, Co, Cu, Fe, Ni, Pb, Ti, and Zn increased with increasing CM/N values. However, under these conditions, the recovery of alkaline earth elements was considerably low when a resin with low CM/N ratio was used. This is presumably attributed to the different stability constants of the complexes of these elements with aminocarboxylic acids and amines, and to the electrostatic repulsion between the elements and the protonated amino groups in the CM-PEI. The recovery of Mo and V decreased or varied with increasing CM/N values, suggesting that the extraction of these elements occurred mainly

  7. Surface distribution of dissolved trace metals in the oligotrophic ocean and their influence on phytoplankton biomass and productivity

    Pinedo-González, Paulina; West, A. Joshua; Tovar-Sánchez, Antonio; Duarte, Carlos M.; Marañón, Emilio; Cermeño, Pedro; González, Natalia; Sobrino, Cristina; Huete-Ortega, María.; Fernández, Ana; López-Sandoval, Daffne C.; Vidal, Montserrat; Blasco, Dolors; Estrada, Marta; Sañudo-Wilhelmy, Sergio A.

    2015-10-01

    The distribution of bioactive trace metals has the potential to enhance or limit primary productivity and carbon export in some regions of the world ocean. To study these connections, the concentrations of Cd, Co, Cu, Fe, Mo, Ni, and V were determined for 110 surface water samples collected during the Malaspina 2010 Circumnavigation Expedition (MCE). Total dissolved Cd, Co, Cu, Fe, Mo, Ni, and V concentrations averaged 19.0 ± 5.4 pM, 21.4 ± 12 pM, 0.91 ± 0.4 nM, 0.66 ± 0.3 nM, 88.8 ± 12 nM, 1.72 ± 0.4 nM, and 23.4 ± 4.4 nM, respectively, with the lowest values detected in the Central Pacific and increased values at the extremes of all transects near coastal zones. Trace metal concentrations measured in surface waters of the Atlantic Ocean during the MCE were compared to previously published data for the same region. The comparison revealed little temporal changes in the distribution of Cd, Co, Cu, Fe, and Ni over the last 30 years. We utilized a multivariable linear regression model to describe potential relationships between primary productivity and the hydrological, biological, trace nutrient and macronutrient data collected during the MCE. Our statistical analysis shows that primary productivity in the Indian Ocean is best described by chlorophyll a, NO3, Ni, temperature, SiO4, and Cd. In the Atlantic Ocean, primary productivity is correlated with chlorophyll a, NO3, PO4, mixed layer depth, Co, Fe, Cd, Cu, V, and Mo. The variables salinity, temperature, SiO4, NO3, PO4, Fe, Cd, and V were found to best predict primary productivity in the Pacific Ocean. These results suggest that some of the lesser studied trace elements (e.g., Ni, V, Mo, and Cd) may play a more important role in regulating oceanic primary productivity than previously thought and point to the need for future experiments to verify their potential biological functions.

  8. Using lead isotopes and trace element records from two contrasting Lake Tanganyika sediment cores to assess watershed – Lake exchange

    Highlights: • Trace element concentrations and lead isotopic ratios were measured in sediment. • Increased element fluxes driven by increased erosion rates linked to land use changes. • Lead isotopic ratios suggest the two sites received lead input from different sources. - Abstract: Lead isotopic and trace element records of two contrasting sediment cores were examined to reconstruct historic, industrial contaminant inputs to Lake Tanganyika, Africa. Observed fluxes of Co, Cu, Mn, Ni, Pb, and Zn in age-dated sediments collected from the lake varied both spatially and temporally over the past two to four centuries. The fluxes of trace elements were lower (up to 10-fold) at a mid-lake site (MC1) than at a nearshore site (LT-98-58), which is directly downstream from the Kahama and Nyasanga River watersheds and adjacent to the relatively pristine Gombe Stream National Park. Trace element fluxes at that nearshore site did not measurably change over the last two centuries (1815–1998), while the distal, mid-lake site exhibited substantial changes in the fluxes of trace elements – likely caused by changes in land use – over that period. For example, the flux of Pb increased by ∼300% from 1871 to 1991. That apparent accelerated weathering and detrital mobilization of lithogenic trace elements was further evidenced by (i) positive correlations (r = 0.77–0.99, p < 0.05) between the fluxes of Co, Cu, Mn, Ni, Pb, and Zn and those of iron (Fe) at both sites, (ii) positive correlations (r = 0.82–0.98, p < 0.01, n = 9) between the fluxes of elements (Al, Co, Cu, Fe, Mn, Ni, Pb, and Zn) and the mass accumulation rates at the offshore site, (iii) the low enrichment factors (EF < 5) of those trace elements, and (iv) the temporal consistencies of the isotopic composition of Pb in the sediment. These measurements indicate that accelerated weathering, rather than industrialization, accounts for most of the increases in trace element fluxes to Lake Tanganyika in spite

  9. Large Seebeck magnetic anisotropy in thin Co films embedded in Cu determined by ab initio investigations

    Popescu, Voicu; Kratzer, Peter

    2013-09-01

    The longitudinal thermopower of a Cu/Co/Cu trilayer system exhibits an oscillatory dependence on the thickness of the Co layer, a behavior related to the formation of quantum well states in the minority spin channel. In addition, it is found to be very sensitive to a switching between an in-plane and out-of-plane magnetization. The resulting magnetothermopower (MTP) is therefore much larger than anticipated from the conventional anisotropic magnetoresistance (AMR). Our calculations establish a direct connection between the magnitude of the MTP signal and the asymmetry of the AMR around the Fermi energy. An enhancement of MTP based on this understanding may offer the possibility of implementing an efficient spin read-out thermoelectric device based on a single ferromagnetic layer.

  10. Investigations on the growth kinetics of Laves phase precipitates in 12% Cr creep-resistant steels: Experimental and DICTRA calculations

    The growth kinetics of Laves phase precipitates (type Fe2W) in the early stage of creep (650 deg. C for 10,000 h) in two 12% Cr ferrite-martensitic steels has been investigated. In one alloy the Laves phase formed on tempering, while in the second alloy the Laves phase precipitated during creep. Kinetic simulations were performed using the software DICTRA. The particle size of the Laves phase was measured on transmission electron microscopy samples. The equilibrium phase fraction of the Laves phase was reached in the first thousand hours. Simulations of particle growth showed good agreement with the experimental results. Competitive growth between M23C6 and the Laves phase showed that M23C6 carbides reached their equilibrium after 12 days, whereas the Laves phase reached equilibrium after 3 months. Simulations of the influence of the interfacial energy and addition of Co, Cu and Si on Laves phase precipitation are presented.

  11. Spectrographic determination of impurities in beryllium oxide

    A method for the spectrographic determination of Al, B, Cd, Co, Cu, Cr, Fe, Mg, NaNi, Si and Zn in nuclear grade beryllium oxide has been developed. The determination of Co, Al, Na and Zn is besed upon a carrier distillation technique. Better results were obtained with 2% Ga2O3 as carrier in beryllium oxide. For the elements B, Cd, Cu, Fe, Cr, Mg, Ni and Si the sample is loaded in a Scribner-Mullin shallow cup electrode, covered with graphite powder and excited in DC arc. The relative standard deviation values for different elements are in the range of 10 to 20%. The method fulfills requirements of precision and sensitivity for specification analysis of nuclear grade beryllium oxide.(Author)

  12. Determination of metallic impurities in Al2O3 matrix by energy dispersive X-ray fluorescence technique

    The applicability of Energy Dispersive X-ray Fluorescence (EDXRF) spectrometry as an analytical technique for the determination of a number of common metallic impurities in Al2O3 matrix has been studied. The present paper deals with the direct determination of a number of common metallic impurities such as Ca, Cr, Co, Cu, Fe, Mn, Ni, Pb, V and Zn in Al2O3 matrix. A series of Al2O3 standards containing the analyte impurities of interest in the range 10-1000 ppm was prepared synthetically. The spectrometer conditions were optimized to obtain calibration plots for the various analytes under study, which could be further used for the analysis of real life samples. The present method serves a supplementary technique to the presently used AES method, particularly for those analytes which are expected to be present in the concentration range of 50-1000 ppm. (author)

  13. Intermolecular nonradiative energy transfer in clusters with plasmonic nanoparticles

    Kucherenko, M. G.; Stepanov, V. N.; Kruchinin, N. Yu.

    2015-01-01

    The influence of carbon (fullerenes, nanotubes) and metal (Ni, Co, Cu, Ag) nanoparticles on the nonradiative electronic excitation energy transfer between the molecules of organic dyes (acrylic orange as a donor and Nile blue as an acceptor) in alcohol solutions of polyvinylbutyral is studied. It is found that, at particular concentrations of the mixture components, plasmonic nanoparticles affect the nonradiative electronic excitation energy transfer, which is manifested in an increase in the intensity of sensitized fluorescence of acceptors with simultaneous quenching of the fluorescence of donors. A very simple model is proposed to illustrate the observed redistribution of luminescence intensity between the spectral bands of the general spectrum. Molecular-dynamic calculations of the structure of nanocomposites performed for the same purpose confirmed the formation of associated molecular plasmonic complexes fixed by macrochain links.

  14. Chemical fractionations in meteorites. VIII - Iron meteorites and the cosmochemical history of the metal phase

    Kelly, W. R.; Larimer, J. W.

    1977-01-01

    The chemical composition of the metal phase of iron meteorites is traced through an idealized traditional history from condensation, oxidation, and accretion in the nebula to melting, segregation, and freezing in a parent body, considering the following fifteen elements: Au, Co, Cu, Fe, Ga, Ge, Ir, Mo, Ni, Os, Pd, Pt, Re, Rh, and Ru. Twelve iron meteorite groups resolved by Scott and Wasson (1975) are considered in the framework of cosmochemical historical analysis. The parent bodies of five of these groups seem to have had a traditional history. The others seem to have had more unusual histories. For example, the composition of the metal in group IVB matches that predicted for the metal condensate at 1270 K, implying accretion at high temperatures; and the metal in group IVA has a composition indicative of aggregates undergoing progressive stages of partial melting.

  15. Trace element distribution in the hair of some sickle cell anemia patients and controls

    Hair samples of some young sickle cell anemia (SCA) and Control patients in Nigeria were analyzed for 12 elements, viz, Se, Hg, Cr, Fe, Zn, Co, Cu, Br, As, Sb, Na, and Sc, using instrumental Neutron Activation Analysis (INAA). With the exception of Cu, which was found to be significantly higher in the hair of SCA patients (at the 0.05 level of the t-test), there were generally no significant differences in elemental concentrations within the two groups. A preliminary study of the elemental contents of the fingernails of the same subjects showed a higher abundance of most of the elements in nail than in hair. These preliminary results were compared with similar studies form some other parts of the world

  16. Interaction of porphyrins with adenine and adenosine complexes. Effect of a metal nature

    Reactions of complex formation of 5,10,15,20-tetraphenylporphine (H2TPP) and tetra-tert-butylphthalocyanine (H2(t-Bu)4Pc) with adenine and adenosine complexes of d-metals (M=Cd, Co, Cu, Hg, Zn) in DMSO and ethanol are studied. It was found that H2TPP reacts with Cu(II) and Hg(II) adeninates and adenosinates in DMSO, but does not react with Zn(II), Co(II), and Cd(II) adeninates and adenosinates (with both bridging and monodentate type of the ligand coordination). H2(t-Bu)4Pc enters the complex formation reaction with adeninates and adenosinates of all studied metals in DMSO at almost equal rates. The states of adenine and adenosine complexes of different d-metals in DMSO and ethanol are proposed on the basis of kinetic data obtained

  17. Elemental data on human hair sampled from Indian student population and their interpretation for studies in environmental exposure

    The head hair samples from 260 students distributed over the country have been analysed by instrumental neutron activation analysis using high-resolution gamma-ray spectrometry through a combination of short and long irradiations. The elemental abundances for 21 elements (Na, Cl, K, Sc, Cr, Mn, Fe, Co, Cu, Zn, As, Se, Br, Rb, Ag, Cd, Sb, I, La, Ce and Au) computed using a secondary standard, developed in this laboratory, as a comparator are presented and compared with some of the published data. The elemental concentration data have been analysed to look for statistically significant differences between groups based on sex, diet, geographical location, section of hair, etc., and the trace element features have been processed through pattern recognition approach using principal components analysis and minimal spanning tree. The vegetarians and non-vegetarians form clearly distinct groups, while the clusters for general population seem to be based on geographical location. (author)

  18. Multielemental analysis of vegetarian human diets and dietary components by neutron activation

    Samudralwar, D.L. (Nagpur Univ. (India). Dept. of Chemistry); Garg, A.N. (Nagpur Univ. (India). Dept. of Chemistry)

    1994-03-01

    Two vegetarian diet samples representative of the Indian sub-continent were prepared (in raw form) by the proportionate blending method for adolescent and adult age groups. These along with its components, viz. wheat, rice flours and pulses, were analyzed for 12 minor and trace elements by instrumental neutron activation analysis (INAA) and high resolution [gamma]-ray spectrometry. Bowen's kale was also analyzed to check the accuracy of the method. The concentrations of Br, Co, Cu, Fe, K, Mn and P are comparable to the non-vegetarian American and European diets. Zinc concentrations are however lower than the recommended dietary allowances (RDA) and the western non-vegetarian diets. (orig.)

  19. Magnetization reversal via a Stoner–Wohlfarth model with bi-dimensional angular distribution of easy axis

    A numerical extension of the simple Stoner–Wohlfarth model to the case of bi-dimensional angular distributions of easy axis is provided. The results are particularized in case of step-like, Gaussian-like and user defined distributions. In spite of its simplicity, the model can be applied to magnetically textured thin films and multilayers with in-plane magnetic anisotropy, independently on the texture source. Exemplifications are provided for a simple ferromagnetic textured FeCo film as well as for a FeMn/FeCo/Cu/FeCo spin valve structure. - Highlights: • Magnetic texture effects are included in the Stoner–Wohlfarth problem. • Step-like, Gaussian-like and user defined angular EADs are discussed. • The magnetic texture is obtained from the overall magnetization reversal. • Results beyond the OR method can be provided for complex systems

  20. Experimentally tuning the ground state of BaFe2As2 by orbital differentiation

    Rosa, Priscila; Adriano, Cris; Garitezi, Thales; Grant, Ted; Fisk, Zachary; Urbano, Ricardo; Pagliuso, Pascoal

    2015-03-01

    The role of structural parameters in layered systems, such as iron pnictides/chalcogenides (Fe-Pn/Ch), cuprates and heavy fermions, has become crucial for the understanding of their properties. In this talk, I will discuss this subject using a combination of macroscopic and microscopic techniques to study Ba1-xEuxFe2-yMy As2 single crystals (M = Co, Cu, Mn, Ni, and Ru). Interestingly, a close connection arises between the spin-density wave (SDW) phase suppression and local distortions in the structure. Furthermore, these changes are reflected at the Fermi surface by an increase of anisotropy and localization of the Fe 3 d bands at the FeAs plane. Our results suggest that such increase in the planar (xy /x2 -y2) orbital symmetry seems to be a favorable ingredient for the emergence of superconductivity in this class of materials. This work was supported by FAPESP, CNPq, CAPES-Brazi and AFOSR MURI.

  1. Modern fluvial sediment provenance and pollutant tracing: a case study from the Dřevnice River Basin (eastern Moravia, Czech Republic)

    Nehyba, Slavomír; Adamová, Marie; Faimon, Jiří; Kuchovský, Tomáš; Holoubek, Ivan; Zeman, Josef

    2010-04-01

    Modern fluvial deposits of a small fluvial system were studied in the area of eastern Moravia (Czech Republic) with the aim of determining the provenance of the deposits and weathering processes. Identification of the source rocks and their alongstream variations were used for the evaluation of the natural or anthropogenic source of the heavy metals. Paleogene flysch sandstones, flysch mudstones and Quaternary loesses represent source rocks and reflect both the role of recycling and local sources. Provenance from sandstones dominate upstream whereas mudstones represent dominant source rock in the downstream part of the fluvial system. The contents of Pb and Zn are highly enhanced when compared with the natural background in the entire study area. Their anthropogenic source is connected with the rubber/shoe manufacturing industry and traffic. The contents of Cr, Co, Cu, Ni and V are usually lower in modern deposits than in the identified source rocks.

  2. Accumulation of some heavy metals in spice herbs in open-air hydroponics and soil cultures of the Ararat valley

    Peculiarities of some heavy metals (HM), (Mn, Ni, Ti, V, Co, Cu, Pb, Mo, Cr, Zr) accumulation have been studied in spice herbs (basil, dill, coriander, savory) grown in open-air hydroponics and soil cultures of the Ararat Valley. It turned out that the amount of HM content in spice herbs grown in open-air hydroponic conditions was less than in the ones grown in soil conditions. The content of Pb and Ni in spice herbs exceeded the allowed concentration limits (ACL), especially in soil plants. Practical recommendations on obtaining ecologically safe agricultural products have been prepared. The biotechnological hydroponics method of producing spice herbs in the Ararat Valley is ecologically more beneficial than the soil method. Practical proposals of obtaining ecologically safe agricultural products have been developed

  3. Synthesis and magnetic properties of one-dimensional metal oxalate networks as molecular-based magnets

    B P Singh; B Singh

    2000-02-01

    The homo- and heteropolymetallic assemblies of MM′(OX)2(H2O)4, where MM′ represents MnMn, CoMn, NiMn, CuMn, CoCo, NiCo, CuCo, NiNi, CuNi, and CuCu; and the respective complexes, numbered 1–10, have been prepared by reacting metal(II) salts—i.e. of Mn, Co, Ni, and Cu—and potassium oxalate monohydrate in hot water (90–100°C). The magnetic susceptibility data of the complexes 8 and 9 in the 300 K–20 K temperature range obeys the Curie–Weiss law and exhibits Weiss constants – 50 K and – 100 K, respectively. On lowering the temperature, the effective magnetic moment decreases gradually and is indicative of antiferromagnetic phase transition. The complexes have also been characterized by ES mass spectrometry, infrared (IR), electronic, and electron spin resonance (ESR) spectra.

  4. Optimal Cu buffer layer thickness for growing epitaxial Co overlayers on Si(111)7 x 7

    Using scanning tunneling microscopy, reflection high energy diffraction and magnetic optical Kerr effect measurements, growth mode and the magnetic properties of epitaxial Co films on Si(111) with epitaxial Cu(111) buffer layers of various thicknesses have been studied. The strained 3.5-monolayer-thick Cu/Si(111) film has been found to be an optimal buffer, in which case an almost ideal layer-by-layer like growth of Co is observed up to six Co monolayers, due to a negligible lattice mismatch. The coercivity of Co films grown in this layer-by-layer like fashion has been determined to be about 10 Oe, testifying to the high quality of the formed Co film and Co/Cu interface. Changeover of the Co film growth mode from layer-by-layer like to multilayer has been found to result in the transition of the film magnetic properties from isotropic to markedly uniaxially anisotropic.

  5. Study of some properties of bound levels and virtual levels excited with resonance neutrons

    Many neutron resonance parameters of some nuclei with a spin value I 3/2 (35Cl, 37Cl, 63Cu, 65Cu, 197Au) are determined to find the strength function S0 with accuracy. For those nuclei, the S0 value seems not to depend on the spin value J=1 or 2 but could be depend on neutron energy for 197Au. Total radiative width variation against mass number A and spacing distributions between resonances (for 197Au) are studied and discussed. Analysis methods of neutron capture experiments are described in detail and level schemes of Cl, Mn, Fe, Co, Cu, Tm, Hg are presented sometimes with the spin value. Intensities of E1 and M1 transitions with direct capture and interference effects are discussed in view of experimental results. (author)

  6. Stability and leaching of cobalt smelter fly ash

    Vítková, Martina; Hyks, Jiri; Ettler, Vojtěch;

    2013-01-01

    The leaching behaviour of fly ash from a Co smelter situated in the Zambian Copperbelt was studied as a function of pH (5–12) using the pH-static leaching test (CEN/TS 14997). Various experimental time intervals (48h and 168h) were evaluated. The leaching results were combined with the ORCHESTRA...... elements, the released concentrations were very similar after 48h and 168h, indicating near-equilibrium conditions in the system. Calcite, clinopyroxenes, quartz and amorphous phases predominated in the fly ash. Various metallic sulfides, alloys and the presence of Cu, Co and Zn in silicates and glass were...... release of Pb and Cu. However, there is a high risk of Co, Cu, Pb and Zn mobility in the acidic soils around the smelter facility. Therefore, potential local options for “stabilisation” of the fly ash were evaluated on the basis of the modelling results using the PHREEQC code....

  7. Thermodynamic description of heat and spin transport in magnetic nanostructures

    Gravier, Laurent; Serrano-Guisan, Santiago; Reuse, François; Ansermet, Jean-Philippe

    2006-01-01

    Spin-dependent heat and charge transport perpendicular to the plane of magnetic Co/Cu multilayers was studied experimentally and interpreted in the framework of the thermodynamics of irreversible processes. The thermogalvanic voltage(TGV) is introduced. It measures the ac voltage response to a small temperature oscillation while a dc current is driven through the sample. TGV presents a magnetic response (MTGV) of 50%, much larger than magnetoresistance (GMR) and the magneto-thermoelectrical power (MTEP). The linear equations for transport of heat, charge, and spin-polarized currents in magnetic and nonmagnetic mediums are applied to a multilayer structure. The role of spin mixing in GMR, MTEP, and MTGV is shown. In particular, the asymmetry of the spin-mixing gives rise to spin-dependent effective Peltier coefficients. The three measurements can be accounted for with two parameters expressing the spin dependence of the transport coefficients.

  8. Catalytic Decomposition of Toluene Using Various Dielectric Barrier Discharge Reactors

    YE Daiqi; HUANG Haibao; CHEN Weili; ZENG Ronghui

    2008-01-01

    Decomposition of toluene was experimentally investigated with various dielectric barrier discharge (DBD) reactors, such as wire-cylinder, wire-plate and plate-to-plate, combined with multi-metal oxides catalyst (Mn-Ni-Co-Cu-Ox/Al2O3) loaded on the cordierite honeycomb and nickel foam, respectively. The effects of some factors including the residence time, reactor configuration and catalyst, upon the toluene destruction were studied. Results revealed that the use of in-plasma catalysis was more helpful to enhancing the DRE (destruction and removal efficiency) and reducing the O3 formation than that of either post-plasma catalysis or plasma alone. It was demonstrated that the wire-plate reactor was favorable for the oxidation reaction of toluene and the nickel foam-supported catalysts exhibited good activity.

  9. High temperature electron beam ion source for the production of single charge ions of most elements of the Periodic Table

    A new type of a high temperature electron beam ion source (HTEBIS) with a working temperature up to 2500 deg. C was developed for production of single charge ions of practically all elements. Off-line tests and on-line experiments making use of the developed ion source coupled with uranium carbide targets of different density, have been carried out. The ionization efficiency measured for stable atoms of many elements varied in the interval of 1-6%. Using the HTEBIS, the yields and on-line production efficiency of neutron rich isotopes of Mn, Fe, Co, Cu, Rh, Pd, Ag, Cd, In, Sn and isotopes of heavy elements Pb, Bi, Po and some others have been determined. The revealed confinement effect of the ions produced in the narrow electron beam inside a hot ion source cavity has been discussed

  10. Environmental Monitoring of Toshki Region As a New Egyptian Community

    Some heavy metal pollutants namely Cd, Co, Cu, Fe, Mn, Ni, PI and Zn were measured in water, soil and some fruit plants; Citrus finensis, Orantte folia, Citrus aurantium and Vitis vinifera in Toshki region. These samples were collected in March 2005. The samples were treated according to the Standard Operation Procedures, digested and analyzed using an atomic absorption spectrophotometer. It was found that the mean concentrations of the mentioned elements in water samples are higher than those corresponding by environmental Law. While, the concentrations of those elements in soil samples are two folds higher than those found in plant samples. The results are related to those give by the Egyptian environmental Law No. 4/1994. In addition, natural radioactivity levels for 226Ra, 232Th, 40K and137Cs in soil were found to be lower than those corresponding for United Nations Scientific committee on the Effect of Atomic Radiation (UNSCEAR) values. The results are discussed and recommendations are suggested

  11. High-temperature electron irradiation and radiation-thermal technology for utilization, purification and production of some metals

    Solovetskii, Y; Lunin, V

    1998-01-01

    High-temperature irradiation by the beam of 1.2-1.6 MeV accelerated electrons has been used for production Pt, Pd, Mo, Co, Cu and Ni from desactivated Pt(Pd)-containing reforming catalysts, molybdenum sulfide hydrodesulphurization catalysts and hydrogenation catalyst waste material. The radiation-induced decomposition of supported Ni(Co)-Mo/Al sub 2 O sub 3 sulfide catalyst and organic fragments of hydrogenation catalyst wastes has been studied. Radiolysis product distributions are shown as function of time (time up to 1,0 h) and temperature (570-1400K). There was made a principle scheme of the first technological unit for radiation-thermal utilization, purification and production of some metals from solid wastes material.

  12. Diffusion behavior of the spin valve structure

    NiMn/NiFe/Co/Cu/Co/NiFe/seed layer (sample No. 1) and NiFe/CoFe/Cu/CoFe/Ru/CoFe/NiFe/NiMn/Seed layer (sample No. 2), are investigated by using high resolution analytical transmission electron microscopy and an imaging filter. The compositional analysis demonstrated that the diffusions of the Mn and Ni into the Cu/Co bilayer are only observed in sample No. 1. This result indicated that the Ru layer in sample No. 2 might not only act as the spacer of the synthetic antiferromagnet but also behaves as a good diffusion barrier for the Ni and Mn element in the spin valve structure. The diffusion coefficients of constituent elements are simply investigated using the Matano - Boltzmann method. The diffusion mechanisms of Cu in Co layer and Co in Cu layer were primarily dominated by the grain boundary. [copyright] 2001 American Institute of Physics

  13. Configuration and temperature dependence of magnetic damping in spin valves

    Joyeux, X.; Devolder, T.; Kim, Joo-Von; Gomez de la Torre, Y.; Eimer, S.; Chappert, C. [Institut d' Electronique Fondamentale, University Paris-Sud, 91405 Orsay (France); UMR8622, CNRS, University Paris-Sud, 91405 Orsay (France)

    2011-09-15

    Using vector-analyzer ferromagnetic resonance, we have studied the microwave susceptibility of a Py/Co/Cu/Co/MnIr spin valve over a large temperature range (5-450 K) and as a function of the magnetic configuration. An effective magnetization and Gilbert damping constant of 1.1 T and 0.021, respectively, are found for the permalloy free layer, with no discernible variation in temperature observed for either quantities. In contrast, the pinned layer magnetization is reduced by heating, and the exchange bias collapses near a temperature of 450 K. The ferromagnetic resonance linewidth of the free layer increases by 500 MHz when the layer magnetizations are aligned in antiparallel, which is attributed to a configuration-dependent contribution to the damping from spin pumping effects.

  14. Spectrochemical analysis of alloy-800

    An emission spectrographic method for the determination of seven elements in alloy-800 is described. The metal sample is converted to oxide and a 10 per cent carrier mixture (AgCl+LiF+C) is used for the determination of Al, Co, Cu, Mn, Mo and V. 45mg of this (sample + carrier) mixture is taken in a carrier distillation electrode and excited in a d.c. arc. The concentration ranges of the elements determined varies between 200ppm and 0.8 per cent and the coefficient of variation has been found to be around 15 per cent. For the determination of titanium, the sample oxide is glued to the flat tops of a pair of graphite electrodes and excited with a.c. spark. The concentration range covered is 0.35 to 2.0 per cent and the coefficient of variation is found to be ± 3 per cent. (author). 5 figs., 4 tabs

  15. Low-temperature steam-reforming of ethanol over ZnO-supported Ni and Cu catalysts

    Homs, Narcis; Llorca, Jordi; De la Piscina, Pilar Ramirez [Departament de Quimica Inorganica, Universitat de Barcelona, C/Marti i Franques 1-11, 08028 Barcelona (Spain)

    2006-08-15

    ZnO-supported Ni and Cu as well as bimetallic Co-Ni and Co-Cu catalysts containing ca. 0.7wt% sodium promoter and prepared by the co-precipitation method were tested in the ethanol steam-reforming reaction at low temperature (523-723K), using a bioethanol-like mixture diluted in Ar. Monometallic ZnO-supported Cu or Ni samples do not exhibit good catalytic performance in the steam-reforming of ethanol for hydrogen production. Copper catalyst mainly dehydrogenates ethanol to acetaldehyde, whereas nickel catalyst favours ethanol decomposition. However, the addition of Ni to ZnO-supported cobalt has a positive effect both on the production of hydrogen at low temperature (<573K), and on catalyst stability. Evidence for alloy formation as well as mixed oxides at the microstructural level was found in the bimetallic systems after running the ethanol steam-reforming reaction by HRTEM-EELS. (author)

  16. Determination of trace elements in acid rain by reversed phase extraction chromatography and neutron activation

    A preconcentration neutron activation analysis (PNAA) method has been developed for the simultaneous determination of selected trace elements in acid rain and other water samples. The method consists of preconcentration of the elements by reversed phase extraction chromatography using oxine-loaded Amberlite XAD-2 resin. Nearly 100% recoveries were obtained for Co, Cu, Hg, V and Zn at pH 6.0 and for Cd at pH 7.0. Manganese gave incomplete recoveries at the pH range of 4.0-8.0 studies. Various factors that can influence preconcentration of the elements have been investigated in detail. The precision and accuracy of measurements have been evaluated by analyzing certified reference materials. The detection limits have been found to be of the order of ppb. The PNAA method has been applied to a number of acid rain and other water samples

  17. Determination of trace elements in acid rain by reversed-phase extraction chromatography and neutron activation

    A preconcentration neutron activation analysis (PNAA) method involving reversed-phase extraction chromatography on 8-hydroxyquinoline-loaded Amberlite XAD-2 resin has been developed for the simultaneous determination of selected trace elements in acid rain and natural water samples. Quantitative retention has been achieved for Co, Cu, Hg, V and Zn at pH 6.0 and for Cd at pH 7.0. Various factors that can influence the preconcentration procedure have been studied in detail. Concentrations of the elements have been determined by the direct irradiation of the resin without eluting them from the column. Both precision and accuracy of the PNAA method are very good. The detection limits vary between 0.01 and 3 ppb. (author) 48 refs.; 2 figs.; 4 tabs

  18. Instrumental neutron activation analysis applied to the chemical composition of steel

    In the technological application of steel, the knowledge of its chemical composition is of fundamental importance as it is directly related to various properties, such as, mechanical properties, corrosion resistance, temperability and others. Instrumental Neutron Activation Analysis, INAA, is an appropriate technique in the evaluation of the chemical composition of steel and other metallurgical materials due to the possibility of simultaneous determination of a great number of elements without the inconvenience of sample dissolution. Element determination is achieved with good accuracy and precision for major and minor constituents as well as for trace elements. In this paper, INAA was used in the determination of As, Co, Cu, Mn, Mo, V and W in steel and iron samples and in certified reference materials. The obtained accuracy and precision were less than 10% for most of the elements confirming the possibility of its use in the study of metallic samples and in the certification of new reference materials. (author)

  19. Studies on CO2 decomposition over H2-reduced MFe2O4 (M = Ni, Cu, Co, Zn)

    Decomposition of CO2 over reduced MFe2O4 (M = Ni, Co, Cu, Zn) was studied by H2-TPR, H2-TG, and CO2-TG. XRD Rietveld analysis was used for determining phase composition and crystallite size of reduced and oxidized samples. The results indicate that spinel CoFe2O4 and CuFe2O4 are reduced to metals by H2, while ZnFe2O4 and NiFe2O4 only partly reduced at 350 C. The CoFe2O4 spinel ferrite shows the best activity in decomposing CO2 and the ZnFe2O4 shows the best recovery ability in the process of redox. (authors)

  20. Rehabilitation materials from surface- coal mines in western U.S.A. III. Relations between elements in mine soil and uptake by plants.

    Severson, R.C.; Gough, L.P.

    1984-01-01

    Plant uptake of Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn from mine soils was assessed using alfalfa Medicago sativa, sainfoin Onobrychis viciaefolia, smooth brome Bromus inermis, crested wheatgrass Agropyron cristatum, slender wheatgrass A. trachycaulum and intermediate wheatgrass A. intermedium; mine soil (cover-soil and spoil material) samples were collected from rehabilitated areas of 11 western US surface-coal mines in North Dakota, Montana, Wyoming and Colorado. Correlations between metals in plants and DTPA-extractable metals from mine soils were generally not statistically significant and showed no consistent patterns for a single metal or for a single plant species. Metal uptake by plants, relative to amounts in DTPA extracts of mine soil, was positively related to mine soil organic matter content or negatively related to mine soil pH. DTPA-extractable metal levels were significantly correlated with mine soil pH and organic-matter content.-from Authors

  1. Multielemental analysis of agroindustrial by-products employed in animal feeding by INAA

    Instrumental neutron activation analysis (INAA) with gamma-ray spectrometry was applied to determine As, Ca, Cd, Cl, Co, Cu, Cr, Fe, Hg, K, Mg, Mn, Mo, Na, Sb, Se and Zn in the Brazilian agroindustrial by-products. These materials are widely used in ruminant feeding. The results obtained were compared with requirement and maximum tolerable concentrations. The general conclusions from the data obtained were: (1) many by-products presented concentrations of some essential elements lower than the requirement concentrations, while in some samples the concentrations of Cr, Fe, Mg and Se exceeded by a little the maximum tolerable concentrations, (2) the elements As, Cd, Hg and Sb, generally considered toxic, showed concentrations lower than maximum tolerable values. (author)

  2. Characterization of ancient glass excavated in Enez (Ancient Ainos) Turkey by combined Instrumental Neutron Activation Analysis and Fourier Transform Infrared spectrometry techniques

    Akyuz, Sevim; Akyuz, Tanil; Mukhamedshina, Nuranya M.; Mirsagatova, A. Adiba; Basaran, Sait; Cakan, Banu

    2012-05-01

    Ancient glass fragments excavated in the archaeological district Enez (Ancient Ainos)-Turkey were investigated by combined Instrumental Neutron Activation Analysis (INAA) and Fourier Transform Infrared (FTIR) spectrometry techniques. Multi-elemental contents of 15 glass fragments that belong to Hellenistic, Roman, Byzantine, and Ottoman Periods, were determined by INAA. The concentrations of twenty six elements (Na, K, Ca, Sc, Cr, Mn, Fe, Co, Cu, Zn, As, Rb, Sr, Sb, Cs, Ba, Ce, Sm, Eu, Tb, Yb, Lu, Hf, Ta, Au and Th), which might be present in the samples as flux, stabilizers, colorants or opacifiers, and impurities, were examined. Chemometric treatment of the INAA data was performed and principle component analysis revealed presence of 3 distinct groups. The thermal history of the glass samples was determined by FTIR spectrometry.

  3. Use of neutron activation analysis for the control of air pollution of Algiers

    The urban zone needs clean air to assure public health. To achieve this goal several filter samples were collected in different sites in Algiers city. Toxic elements such as: Na, Mg, Cl, Sc, Cr, Ti, V, Fe, Co, Cu, Zn, Se, Br, Ag, Sb, Ce, La, Hf, Ta and Hg have been measured in the filters using neutron activation analysis technique. Irradiation of filter samples and standards were carried out in Es-Salem reactor. The experimental procedure and the results are discussed. We noted during this work that the upper limit values for suspended dusts and the high concentrations for some toxic elements found are due to the weather conditions and intense road traffic around collecting sites. (authors)

  4. Use of neutron activation analysis for the control of air pollution of Algiers; Utilisation de l'analyse par activation neutronique pour le controle de la pollution de l'air d'Alger

    Belamri, M.; Benrachedi, K. [Universite M' hamed Bouguarra, Lab. de Technologie Alimentaire, Boumerdes (Algeria)

    2010-07-15

    The urban zone needs clean air to assure public health. To achieve this goal several filter samples were collected in different sites in Algiers city. Toxic elements such as: Na, Mg, Cl, Sc, Cr, Ti, V, Fe, Co, Cu, Zn, Se, Br, Ag, Sb, Ce, La, Hf, Ta and Hg have been measured in the filters using neutron activation analysis technique. Irradiation of filter samples and standards were carried out in Es-Salem reactor. The experimental procedure and the results are discussed. We noted during this work that the upper limit values for suspended dusts and the high concentrations for some toxic elements found are due to the weather conditions and intense road traffic around collecting sites. (authors)

  5. Standard reference material certification: contribution of NAA with a TRIGA reactor

    Pavia has cooperative links with the major international agencies devoted to the certification of SRMs or CRMs as the Bureau Communautaire de Reference (BCR), the European Institute for Reference Materials and Measurement (IRMM), the USA National Institute of Standards and Technology (NIST) and the International Atomic Energy Agency (IAEA). During these cooperative works, a large amount of analytical data obtained with NAA has been compared, and meaningful methodological information achieved with respect to accuracy and precision in the analysis of several elements at different concentrations in various matrices. Analytical data on As, Cd, Cr, Co, Cu, Cs, Fe, Zn, K, Sc, U, Th, Al, Sb, Mn, V, Hg, Sr, Rb, Se,Pt, all the Rare Earths and halogens Br, Cl, I, have been obtained and contributed for the final certification

  6. A model of the response of GMR of metallic multilayers to external magnetic field

    Uba J.I.

    2015-12-01

    Full Text Available It has not been possible to transform resistivity models in terms of magnetic field in order to account for variation of giant magnetoresistance (GMR with external magnetic field, which would have led to determination of material properties. This problem is approached mathematically via variation calculus to arrive at an exponential function that fits observed GMR values. Using this model in free electron approximation, the mean Fermi vector, susceptibility and total density of states of a number of metallic multilayers are determined from their reported GMR values. Susceptibility is found to depend on interface roughness and antiferromagnetic (AF coupling; thus, it gives qualitative measure of interface quality and AF coupling. Comparison of susceptibilities and GMRs of electrodeposited and ion beam sputtered Co/Cu structures shows that a rough interface suppresses GMR in the former but enhances it in the latter.

  7. Leaching and toxicity behavior of coal-biomass waste cocombustion ashes.

    Skodras, G; Prokopidou, M; Sakellaropoulos, G P

    2006-08-01

    Land disposal of ash residues, obtained from the cocombustion of Greek lignite with biomass wastes, is known to create problems due to the harmful constituents present. In this regard, the leachability of trace elements from lignite, biomass, and blends cocombustion ashes was investigated by using the Toxicity Characteristic Leaching Procedure (TCLP) of the US Environmental Protection Agency (US EPA). In this work, the toxicity of the aqueous leachates and the concentrations of the metals obtained from the leaching procedure were measured using the Microtox test (Vibrio fischeri) and inductive coupled plasma-atomic emission spectrometer (ICP-AES), respectively. The toxic effects of most leachates on Vibrio fischeri were found to be significantly low in both 45% and 82% screening test protocols. However, the liquid sample originating from olive kernels fly ash (FA4) caused the highest toxic effect in both protocols, which can be attributed to its relatively high concentrations of As, Cd, Co, Cu, Mn, Ni, and Zn. PMID:16841309

  8. Applications of instrumental neutron activation analysis (INAA) for geological samples in AMD for uranium exploration programme

    Full text: Non-destructive Instrumental Neutron Activation Analysis has been used over last three decades in AMD for analysis of geological samples for estimation of Na, K, Ca, Sc, Cr, Fe, Co, Cu, Zn, Ga, As, Br, Zr, Ag, Sb, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Tm, Ho, Yb, Lu, Hf, Ta, W, Re, Os, Ir, Au, Th and U. The estimation has been done using various international standards. The irradiation of samples has been done in Cirus/Apsara Reactor in BARC, Mumbai. The measurement of desired gamma emission are carried out by Huge detector. The various geological samples from different parts of India are: 1. granites 2. charnokites 3. Basalts 4. Carbonatites 5. Xenotime 6. Monazite 7. Core samples 8. Black slabs. The efficiency modelling of HPGe detector was done using different sources and mathematical and statistical techniques. (author)

  9. Multielemental analysis of plant species together with their corresponding soils in egypt

    Different locations in the Nuclear Research Center (NRC) at Inshas area and the area nearby (about 30 km radius) were selected for collecting the vegetation samples together with their corresponding soils. Instrumental Scan Electron Microscope-Energy Dispersive X-ray Spectrometer (SEM-EDS) technique was applied to the determination of major and minor elements that are present at relatively high concentrations, while trace elements that are present at extremely low concentrations were determined by using: Inductively Coupled Plasma -Mass Spectrometer (ICP-MS). Two groups of elements have been determined directly in both plants and their corresponding soils. The first group is the major and the minor elements (Ca, Mg, K, P, Na, Cl and S ),and the second group is the trace elements (B ,V ,Cr, Mn, Ni, Co, Cu, Zn, Se, Mo, Sr, Cs, Th, U, As, Hg, Pb, and Cd). The results were inspected and the relation between different concentrations in both grasses and corresponding soil were considered

  10. Temperature dependence of exchange bias in Co/FeMn-structure induced by heating and cooling in magnetic field

    Using the method of angular dependence of ferromagnetic resonance field the magnetic properties of Si/SiO2/Cu/Co/FeMn/Cu and Si/SiO2/Cu/Co/Cu/FeMn/Cu structures were investigated. The layer deposition was carried out by magnetron sputtering in absence of an external magnetic field. It was established that thermal annealing with further cooling down in presence of a magnetic field can generate an exchange bias at anneal temperature significantly below the bulk antiferromagnetic Neel temperature. It was also shown that a thin interlayer between ferromagnetic and antiferromagnetic layers reduces the exchange bias effect at low anneal temperatures, however, makes this effect more stable at high annealing temperatures.

  11. Conductivity mechanisms in acceptor doped KTaO3 crystals

    This paper reports on the electrical conductivity of perovskite-structured KTaO3 crystals acceptor doped with Co, Cu or Fe investigated after treatments in oxidizing and reducing atmospheres under both wet and dry conditions. Isotope effect measurements (using H2O vs. D2O) show that, after treatments in wet gases of low P(O2), all the crystals are primarily protonic conductors, through a process of proton hopping with an activation energy close to 0.84 eV. Electron hole conduction dominates at high P(O2) in the case of Fe and Cu doping. For Co-doped crystals, the conductivity is independent of P(O2) up to 1 atm., indicating that ionic conduction predominates. There is no evidence of oxygen vacancy migration, leading to the conclusion that the activation energy for the process is relatively high

  12. Isolation, growth, ultrastructure, and metal tolerance of the green alga, Chlamydomonas acidophila (Chlorophyta).

    Nishikawa, K; Tominaga, N

    2001-12-01

    An acidophilic volvocine flagellate, Chlamydomonas acidophila (Volvocales) that was isolated from an acid lake, Katanuma, in Miyagi prefecture, Japan was studied for growth, ultrastructural characterization, and metal tolerance. Chlamydomonas acidophila is obligately photoautotrophic, and did not grow in the cultures containing acetate or citrate even in the light. The optimum pH for growth was 3.5-4.5. To characterize metal tolerance, the toxic effects of Cd, Co, Cu, and Zn on this alga were also studied. Effective metal concentrations, which limited the growth by 50%, EC50 were measured, after 72 h of static exposure. EC50s were 14.4 microM Cd2+, 81.3 microM Co2+, 141 microM Cu2+, and 1.16 mM Zn2+ for 72 h of exposure. Thus, this alga had stronger tolerance to these metals than other species in the genus Chlamydomonas. PMID:11826960

  13. Synthesis and characterizations of microwave sintered ferrite powders and their composite films for practical applications

    Shannigrahi, S. R.; Pramoda, K. P.; Nugroho, F. A. A.

    2012-01-01

    Phase pure single phase ferrite powders of (NixR1-x)0.5Zn0.5Fe2O4 (R=Mn, Co, Cu; x=0, 0.5) were manufactured using microwave sintering at 930 °C for 10 min in air atmosphere. The powders were characterized for their structure, microstructure, thermal, and magnetic properties. Selected powders were used as fillers to prepare their composite films using polymethyl methacrylate polymers as matrix. The composite films were prepared using the melt blending approach and were tested for their microstructure, thermal, and magnetic hysteresis loop as well as 3D magnetic field space mappings using an electromagnetic compatibility scanner. Among the studied ferrites, cobalt doped ferrites and their composites showed the best electromagnetic interference (EMI) shielding effectiveness value and have potential for practical EMI shielding applications.

  14. Leaching and toxicity behavior of coal-biomass waste cocombustion ashes

    Skodras, G.; Prokopidou, M.; Sakellaropoulos, G.P. [Aristotle University in Thessaloniki, Thessaloniki (Greece). Dept. for Chemical Engineering

    2006-08-15

    Land disposal of ash residues, obtained from the cocombustion of Greek lignite with biomass wastes, is known to create problems due to the harmful constituents present. In this regard, the leachability of trace elements from lignite, biomass, and blends cocombustion ashes was investigated by using the Toxicity Characteristic Leaching Procedure (TCLP) of the US Environmental Protection Agency (US EPA). In this work, the toxicity of the aqueous leachates and the concentrations of the metals obtained from the leaching procedure were measured using the Microtox test (Vibrio fischen) and inductive coupled plasma-atomic emission spectrometer (ICP-AES), respectively. The toxic effects of most leachates on Vibrio fischeri were found to be significantly low in both 45% and 82% screening test protocols. However, the liquid sample originating from olive kernels fly ash (FA4) caused the highest toxic effect in both protocols, which can be attributed to its relatively high concentrations of As, Cd, Co, Cu, Mn, Ni, and Zn.

  15. Accumulation of heavy metals in water, sediments and wetland plants of kizilirmak delta (samsun, Turkey).

    Engin, M S; Uyanik, A; Kutbay, H G

    2015-01-01

    In this study, concentrations of heavy metals (Fe, Mn, Ni, Co, Zn, Cu, and Pb) were measured in water bodies including streams, bottom sediments and various wetland plants of Kızılırmak Delta. Kızılırmak Delta is one of the largest and the most important natural wetlands in Turkey and has been protected by Ramsar convention since 1993. The heavy metal concentrations in water were found lower than that of national standards for protected lakes and reserves. In bottom sediments and wetland plants, however, the accumulated amounts of different heavy metals varied in the following order: Fe>Mn>Zn>Ni>Co>Cu>Pb, and Fe>Mn>Zn>Ni>Co respectively. Heavy metal uptake of Hydrocharis morsus-ranae and Myriophyllum verticillatum plants among others were found far above the toxic levels and they might be used as bio-indicators and heavy metal accumulators in polluted natural areas. PMID:25174426

  16. Factorial discriminant analysis of occupational exposure in metallurgy using INAA of hair samples

    A multivariate statistical technique - factorial discriminant analysis (FDA) - has been used to evaluate the occupational exposure of a group of metallurgy workers using the elemental composition of their scalp hair, as compared with a control group. The initial variables were the concentrations of ten minor and trace elements Al, Co, Cu, Fe, Mg, Mn, Sb, Se, V, and Zn determined in hair samples by using instrumental neutron activation analysis (INAA). A good discrimination between exposed and control subjects has been achieved after the normalization of the data (by log-transforming the initial variables) and considering sex-matched groups. To measure the accuracy of the classification and the predictive ability a cross-validation procedure was used. (author)

  17. Determination of trace elements in human head hair by neutron activation analysis

    Instrumental neutron activation analysis was used to measure concentrations of elements in hair samples from a group of patients of a medical clinic and from a control group. Elements Al, As, Br, Ca, Cd, Cl, Co, Cu, Fe, Hg, K, Mg, Mn, Na, Sb, Sc, Se, V and Zn were analyzed and comparisons were made between the results obtained for these two groups of individuals. Normal ranges for elemental hair by commercial laboratories are also presented, for comparison, with those results obtained for the control group of individuals living in Sao Paulo, Brazil. Precision and accuracy of the results were evaluated by analyzing NIES No. 5 Human Hair and SHINR GBW09101 Human Hair reference materials. (author)

  18. Workplace and occupational health: The first metal evaluation using nuclear and analytical techniques in the state of Minas Gerais - Brazil

    Belo Horizonte and surrounding areas is an important industrial centre and the galvanising industry is responsible for the majority of patients who look for medical assistance because of metal contamination. Hair samples and other biological matrixes will be used as bioindicators as well as airborne particulate matter. This work is related to an IAEA Co-ordinated Research Project whose goal is to make a survey of the exposures to metals related to occupational diseases which has been conducted by CDTN and Departments of Health. The hair samples were donated by galvanising factory workers in Belo Horizonte. The Al, Co, Cu, Cr, Mn and V concentrations determined in the workers' samples suggest endogenous contamination. (author)

  19. Major and minor elements analysis in soil samples by neutron activation analysis and X-ray fluorescence

    In the present work, Instrumental Neutron Activation Analysis (INAA) and X-Ray Fluorescence were employed to analyze major and minor elements in soil samples collected near Bandeirantes road. Elements of environmental interest, such as Al, Sb, As, Ba, Cd, Pb, Co, Cu, Cr, Fe, Mn, Mo, Ni, Se, V and Zn, which have reference background levels, were determined. The samples were dried in an oven at 40 deg C, were sieved (<2 mm), grinded and were analyzed by INAA and FRX. The aims of this work were: to evaluate the possible variations in the concentration levels in soil due to emission of particulate from vehicles and other anthropogenic sources; to compare the results obtained by using both techniques. This preliminary study showed that the concentration levels of the elements of environmental interest agree with reference values for tropical soils in the sampling sites, except for Ba, which presented higher values. (author)

  20. Application of High Resolution-Continuum Source Flame Atomic Absorption Spectrometry (HR-CS FAAS): determination of trace elements in tea and tisanes.

    Paz-Rodríguez, Beatriz; Domínguez-González, María Raquel; Aboal-Somoza, Manuel; Bermejo-Barrera, Pilar

    2015-03-01

    A new application of HR-CS FAAS (High Resolution-Continuum Source Flame Atomic Absorption Spectrometry) has been developed for the determination of several trace elements (Ca, Co, Cu, Fe, Mn, Ni, Na and Zn) in infusions made from tea, rooibos and tea with seaweed samples. The proposed methods are fast, inexpensive and show good performances: the mean analytical recovery was approximately 100%. The mean limit of detection was 29.4 μg/l, and the mean limit of quantification was 98.0 μg/l (both limits refer to the brewed samples). Due to the matrix effect observed, the standard addition method had to be applied. Preliminary classification (based on metal contents) using chemometric techniques such as PCA (Principal Component Analysis) and CA (Cluster Analysis), was successful for infusions made from rooibos and tea with seaweed, but inconclusive for black and green teas. PMID:25306375

  1. Sorption of radionuclides and metals to graphene oxide and magnetic graphene oxide

    Graphene oxide (GO) and two magnetic graphene oxide (MGO) composites with a different amount of magnetite were synthesized, characterized and used in sorption experiments. The effect of pH on sorption of Am(III) and Pu(IV) isotopes as well as Co(II), Ni(II), Cu(II) and Pb(II) to GO and MGO was studied in equilibrium and kinetic experiments. The adsorption capacities varied from 30 to 574 mg g-1 while rate constants ranged from 0.29 to 0.46 min-1 and increased in the following order Co, Cu, Pb and Ni. Large variations in the uptake of studied elements by adsorbents depending on initial and final pH of solutions were observed. (author)

  2. Elemental content in wheat products of Al-Qusim region, Saudi Arabia using the INAA technique

    Wheat is one of the most grown crops in Saudi Arabia. It is grown in various regions of the country. Accurate knowledge of the elemental concentrations in wheat and its products (bran and flour) is of great importance from a nutritional point of view. Wheat samples were obtained from the Al-Qusim region. 300 km northwest of Riyadh, and analyzed. Up to 50 elements (Al, Sb, As, Ba, Br, Cd, Ca, Cs, Cl, Cr, Co, Cu, Ga, Au, Hf, In, I, Ir, Fe, Mg, Mn, Hg, Mo, Ni, K, Rb, Sc, Se, Ag, Na, Sr, Ta, Te, Th, Sn, Ti, W, U, V, Zn, Zr, Ce, Dy, Eu, La, Lu, Nd, Sm, Tb and Yb) were determined in the wheat products. It was observed that the elemental content of bran was much higher than that of white flour. (author)

  3. Application of spouted bed elutriation in the recycling of lithium ion batteries

    Bertuol, Daniel A.; Toniasso, Camila; Jiménez, Bernardo M.; Meili, Lucas; Dotto, Guilherme L.; Tanabe, Eduardo H.; Aguiar, Mônica L.

    2015-02-01

    The growing environmental concern, associated with the continuous increase in electronic equipment production, has induced the development of new technologies to recycle the large number of spent batteries generated in recent years. The amount of spent lithium-ion batteries (LIBs) tends to grow over the next years. These batteries are composed by valuable metals, such as Li, Co, Cu and Al, which can be recovered. Thus, the present work is carried out in two main steps: In the first step, a characterization of the LIBs is performed. Batteries from different brands and models are dismantled and their components characterized regarding to the chemical composition and main phases. In the second step, a sample of LIBs is shredded and the different materials present are separated by spouted bed elutriation. The results show that spouted bed elutriation is a simple and inexpensive way to obtain the separation of the different materials (polymers, metals, active electrode materials) present in spent LIBs.

  4. Proton induced X-ray emission (PIXE) technique for determining multi-element composition of transformed hairy root cultures of Boerhaavia diffusa L. An important medicinal herb

    Therapeutically important inorganic elements in Agrobacterium rhizogenes-mediated genetically transformed hairy root cultures (HRCs) of a pharmaceutically significant herb Boerhaavia diffusa were quantified using proton induced X-ray emission technique. This was compared with that of roots from the naturally grown donor plant. Two macro-elements (Ca and K) and eight different trace elements namely V, Cr, Mn, Fe, Co, Cu Zn, and Ni were detected and their content was determined. In HRCs of a transformed rhizoclone, calcium and potassium had values which were significantly higher than that of in vivo roots. The concentrations of several trace elements, which are known to have a positive implication in human healthcare, were found to be either comparable (Fe) to that in the natural root samples or higher (Mn, Zn, Cr, Cu, Co) in the transformed rhizoclone. The genetically transformed HRCs can thus serve as a fast-proliferating renewable resource of medicinally useful minerals targeting specific diseases. (author)

  5. Nanosecond ligand migration and functional protein relaxation in ba3 oxidoreductase: Structures of the B0, B1 and B2 intermediate states.

    Nicolaides, Antonis; Soulimane, Tewfik; Varotsis, Constantinos

    2016-09-01

    Nanosecond time-resolved step-scan FTIR spectroscopy (nTRS (2) -FTIR) has been applied to literally probe the active site of the carbon monoxide (CO)-bound thermophilic ba3 heme-copper oxidoreductase as it executes its function. The nTRS (2) - snapshots of the photolysed heme a3 Fe-CO/CuB species captured a "transition state" whose side chains prevent the photolysed CO to enter the docking cavity. There are three sets of ba3 photoproduct bands of docked CO with different orientation exhibiting different kinetics. The trajectories of the "docked" CO at 2122, 2129 and 2137cm(-1) is referred to in the literature as B2, B1 and B0 intermediate states, respectively. The present data provided direct evidence for the role of water in controlling ligand orientation in an intracavity protein environment. PMID:27207588

  6. Síntese, caracterização e estudo das propriedades magnéticas de um polímero de coordenação contendo cobalto(II e cobre(II

    Tamyris T. da Cunha

    2012-01-01

    Full Text Available This work describes the synthesis and characterization of two new compounds with ligand opy (N-(2-pyridyloxamate: the copper(II precursor [Me4N]2[Cu(opy2].5H2O and CoII CuII coordination polymer {[CoCu(opy2]}n×4nH2O. This latter compound was obtained by reaction of [Me4N]2[Cu(opy2].5H2O and CoCl2.6H2O in water. The heterobimetallic CoII CuII chain was characterized by elemental analysis, IR spectroscopy, thermogravimetry and magnetic measurements. Magnetic characterization revealed typical behavior of one-dimensional (1D ferrimagnetic chain as shown in the curves of temperature (T dependence of magnetic susceptibility (χM, in the form of χMT versus T, and dependence of magnetization (M with applied field (H.

  7. Atomic Decay Data for Modeling K Lines of Iron Peak and Light Odd-Z Elements*

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

    2012-01-01

    Complete data sets of level energies, transition wavelengths, A-values, radiative and Auger widths and fluorescence yields for K-vacancy levels of the F, Na, P, Cl, K, Sc, Ti, V, Cr, Mn, Co, Cu and Zn isonuclear sequences have been computed by a Hartree-Fock method that includes relativistic corrections as implemented in Cowan's atomic structure computer suite. The atomic parameters for more than 3 million fine-structure K lines have been determined. Ions with electron number N greater than 9 are treated for the first time, and detailed comparisons with available measurements and theoretical data for ions with N less than or equal to 9 are carried out in order to estimate reliable accuracy ratings.

  8. Contamination at Todos os Santos Bay [Contaminação na Baía de Todos os Santos

    Gisele O. da Rocha

    2012-10-01

    Full Text Available Todos os Santos Bay (BTS is the second largest coastal bay in Brazil, which occupies an area of 1,233 km2 and 184 km of coastline perimeter. The BTS includes an urban area, including Salvador, with more than 3 million inhabitants and an extensive industrial area. This paper focuses on the chemical contamination of the atmosphere and marine coastal system of BTS, discussing the main sources of different compounds found. In several regions of the BTS atmospheric particulate matter, suspended particulate matter, algae, sediment and biota are enriched with trace elements (As, Cd, Pb, Zn, Hg, Mn, Co, Cu, Sb, among others and organic contaminants (PAH and n-alkanes at concentration levels above those considered "natural". Therefore, anthropogenic contributions (industrial discharges and domestic oil and gas extraction, power generation processes, vehicular emission and port activities contributed to the environmental levels of contaminants studied to date.

  9. NOVEL PREPARATION AND MAGNETO CHEMICAL CHARACTERIZATION OF NANOPARTICLE MIXED ALCOHOL CATALYSTS

    Seetala V. Naidu; Upali Siriwardane

    2005-05-24

    We have developed and streamlined the experimental systems: (a) Laser-induced solution deposition (LISD) photosynthesis, ball-milling, and chemical synthesis of Fe, Co, and Cu nanoparticle catalysts; (b) Sol-gel method for mesoporous {gamma}-Al{sub 2}O{sub 3}, SiO{sub 2}, hybrid alumina/silica granular supports; (c) Three sol-gel/oil-drop catalyst preparation methods to incorporate metal nanoparticles into mesoporous 1 mm granular supports; (d) Low-cost GC-TCD system with hydrogen as carrier gas for the determination of wide spectrum of alkanes produced during the F-T reactions; and (e) Gas-flow reactor and microchannel reactor for fast screening of catalysts. The LISD method could produce Co, Cu, and Fe (5 nm) nanoparticles, but in milligram quantities. We could produce nanoparticles in gram quantities using high-energy ball milling and chemical synthesis methods. Ball milling gave wide particle size distribution compared to the chemical synthesis method that gave almost uniform size ({approx}5 nm) particles. Metal nanoparticles Cu, Co, Fe, Cu/Co, Cu/Fe and Co/Fe were loaded (2-12 wt%) uniformly into {gamma}-Al{sub 2}O{sub 3}, SiO{sub 2}, or alumina/silica hybrid supports by combined sol-gel/oil-drop methods followed by calcination and hydrogenation steps, prior to syngas FT reaction studies. The properties of metal loaded {gamma}-Al{sub 2}O{sub 3} granules were compared for the two precursors: aluminum tri-sec-butoxide (ALTSB) and aluminum tri-iso-propoxide (ALTIP). The effect of solgel supports alumina, silica, and alumina/silica hybrid were examined on catalytic properties. Metal loading efficiencies for pure metal catalysts increased in the order Co, Cu and Fe in agreement with solubility of metal hydroxides. In case of mixed metals, Co and Cu seams to interfere and reduce Fe metal loading when metal nitrate solutions are used. The solubility differences of metal hydroxides would not allow precise control of metal loading. We have overcome this problem by

  10. Preparation and certification of certified reference materials JAERI-Z21, Z22 and Z23 for analysis of zirconium and its alloys

    The Sub-Committee on Chemical Analysis of Nuclear Materials was organized in April 1987, under the Committee on Analytical Chemistry of Nuclear Fuels and Reactor Materials, JAERI, for renewal of certified reference materials of zirconium base alloys and zirconium metal. Collaborative analysis was carried out among ten participating laboratories for the certification of the JAERI CRMs Z21 to Z23. As a results of the collaborative works, the certified values for sixteen elements (Sn, Fe, Ni, Cr, Hf, Al, Si, Co, Cu, Ti, Mn, Pb, U, Cd, B and W) in the CRMs were given. In this report, preparation of raw materials, homogeneity test, chemical analysis for certification by collaborative works during April 1987 to March 1990 are described. (author)

  11. NQR-NMR studies of higher alcohol synthesis Cu-Co catalysts

    1991-01-14

    Copper and cobalt are the key elements in syngas conversion catalyst systems used for higher alcohol synthesis. Their proximity and synergy sensitively control the selectivity and efficiency of the process. It is believed that their outer electronic charge distribution which is responsible for their electrical and magnetic properties might be governing their catalytic properties also. To examine the correlation between catalytic and magnetic properties, a series of copper cobalt catalysts (Co/Cu ratio 5:1 to 5:5) with and without a support were prepared. The nuclear quadrupole resonance spectrum of copper and (zero-field) nuclear magnetic resonance spectrum of cobalt and magnetization and hysteresis character of the catalyst were analyzed. Similar to the catalytic results, the magnetic results also were found to be very sensitive to the preparation technique. The results indicate possible electron exchange between copper and cobalt, and cobalt and the support Titania.

  12. NQR-NMR studies of higher alcohol synthesis Cu-Co catalysts. Quarterly technical progress report, September 14--December 15, 1990

    1991-01-14

    Copper and cobalt are the key elements in syngas conversion catalyst systems used for higher alcohol synthesis. Their proximity and synergy sensitively control the selectivity and efficiency of the process. It is believed that their outer electronic charge distribution which is responsible for their electrical and magnetic properties might be governing their catalytic properties also. To examine the correlation between catalytic and magnetic properties, a series of copper cobalt catalysts (Co/Cu ratio 5:1 to 5:5) with and without a support were prepared. The nuclear quadrupole resonance spectrum of copper and (zero-field) nuclear magnetic resonance spectrum of cobalt and magnetization and hysteresis character of the catalyst were analyzed. Similar to the catalytic results, the magnetic results also were found to be very sensitive to the preparation technique. The results indicate possible electron exchange between copper and cobalt, and cobalt and the support Titania.

  13. Radioprotective effects in mice by a single dose of subcutaneous administration of cobaltous chloride post γ-rays irradiation with a sublethal dose

    Radioprotective effects were investigated in mice which received subcutaneously a single dose of each inorganic metal: Co, Cu, Rb, Sr, Mo and W 24 hours post irradiation of 60Co γ-rays with a sublethal dose. The effects were observed in mice injected with Co at an optimum dosage of 20 mg/kg·body weight. Then to elucidate mechanisms of the effects, mice were injected with Co containing the radioactive tracer (60Co) following the radiation exposure, measured elimination of the radioactivity for 7 days, then sacrificed and divided to some tissues and organs. The radioactivity in whole body during this period resulted in a markedly higher retention than that for mice injected with [60Co] alone, as well as liver in the organs. These higher retentions appeared to be related to the radioprotective effects. (author)

  14. High post-annealing stability for perpendicular [Co/Ni] n multilayers by preventing interfacial diffusion

    Li, Xu-Jing; Jiang, Shao-Long; Zhang, Jing-Yan; Han, Gang; Liu, Qian-Qian; Liu, Yi-Wei; Wang, Dong-Wei; Feng, Chun; Li, Ming-Hua; Yu, Guang-Hua

    2016-05-01

    This paper reports that by introducing an appropriate thickness of Cu spacer at a Co/Ni interface, the perpendicular magnetic anisotropy of [Co/Cu/Ni] n multilayers can be maintained at the annealing temperature as high as 400 °C, implying high post-annealing stability. X-ray reflectivity results demonstrate that the multilayers with Cu spacer exhibit good multilayer structure, indicating the weak intermixing of Co and Ni, which is one important reason for the enhanced post-annealing stability of perpendicular magnetic anisotropy. The result is of great importance for out-of-plane magnetized spintronic devices which need to be combined with complementary metal-oxide semiconductors.

  15. A statistical study of environmental factors controlling concentrations of heavy metals in the burrowing bivalve Scrobicularia plana and the polychaete Nereis diversicolor

    Luoma, Samuel N.; Bryan, G. W.

    1982-07-01

    Multiple regression analyses indicate that the most important factors controlling Ag, Cd, Co, Cu, Pb and Zn concentrations in the estuarine bivalve Scrobicularia plana and the polychaete Nereis diversicolor are the concentrations of these metals in surface sediments and the partitioning of sediment-bound metals between different sediment constituents. Extraction of the sediments with 1-N HCl provides more information about the bioavailability of the metals than do extractions with five other techniques. Biologically available Cd and Co in solution contribute significantly to Cd and Co concentrations in both Scrobicularia and Nereis. Concentrations of Ag in Scrobicularia are reduced where Cu concentrations in sediments are high. An unexplained increase in concentrations of Cu in Scrobicularia at specific stations in six estuaries suggests that under certain very anoxic conditions the availability of copper may be exceptionally high.

  16. Effects of Annealing Temperature on Co30Cu70 Mechanical Alloys

    Watcharee RATTANASAKULTH

    2006-06-01

    Full Text Available Physical properties of Co30Cu70 mechanical alloys prepared by ball milling were investigated. After milling for 50 h, the powder contained Co-rich, Cu-rich clusters as well as Co-Cu solid solution. Annealing at 200 - 300 °C for 30 min modified thermal behaviors but only slightly affected magnetic properties. Higher temperature annealing (400 - 500 °C led to substantial oxidation of Co and Cu and deteriorated magnetic properties. Pressed Co30Cu70 pellets exhibited 0.6 - 2 % giant magnetoresistance (GMR but showed modest GMR after heat treatment. GMR disappeared by annealing at 500 °C as large fractions of Co and Cu were converted into oxides.

  17. PIXE trace element analysis of a selection of wines

    The University of Montreal EN Tandem accelerator and a Si (Li) X-ray detector were used for a PIXE (Proton Induced X-ray emission) trace element analysis of a selection of wines. Quantitative measurements of the concentrations of the sixteen trace elements Na, Mg, Al, Si, P, S, Cl, K, Ca, Cr, Mn, Fe, Co, Cu, Zn, and Br were made. To optimize the sensitivity, spectra were recorded at 1.0 MeV proton energy for elements with Z 19. The absolute concentrations of the trace elements were determined by doping the samples of wine with 1000 ppm of vanadium for the 1.0 MeV bombardments, and 1000 ppm of yttrium for the 3.0 MeV irradiations. The targets were prepared by depositing a few microliters of the wine onto a Nuclepore filter

  18. Heavy metals concentration in soils from parks and green areas in Belgrade

    MIRJANA D. MARJANOVIĆ

    2009-06-01

    Full Text Available The current study included the investigation of several metals and their distribution in urban soils from parks and green areas in the city of Belgrade. The soils were sampled in January and February 2008. The concentrations of Cd, Co, Cu, Pb, Mn and Zn were measured, as well as the pH values and organic matter contents. The obtained results showed that there was a significant level of contamination in some samples, especially with lead, and that it was most probably caused by anthropogenic activities, mostly from traffic. The results were compared with the National legislation and Netherlands standards. Also, the recent results were compared with the data from previous work and it was concluded that there has been a certain increase of the Pb concentration in the past three years. The level of pollution in playground soil was very high and each analyzed sample exceeded the Dutch target value for Cd, Co and Pb.

  19. Heavy metal pollution assessment in relation to sediment properties in the coastal sediments of the southern Caspian Sea

    Highlights: • Heavy metals and major elements were determined in surface sediments from the southern Caspian Sea. • EF values indicated minimal to significant enrichment. • AS, Cr and Cu were above ERL values; however, Ni exceeded the ERM values. - Abstract: This study aimed to evaluate major elements and heavy metal concentrations of Arsenic (As), Copper (Cu), Chromium (Cr), Cobalt (Co), Vanadium (V), Nickel (Ni), lead (Pb) and Zinc (Zn) in surface sediments of the southern Caspian Sea. Metal contents in the sediment were observed in the order of: V > Cr > Zn > Ni > Co > Cu > Pb > As. Correlations between elements showed that sediment TOM, grain size and chemical composition are the main factors that influence the distribution of heavy metals. According to the pollution load index (PLI), sediments from some sampling sites were polluted. Concentrations of Ni, As, Cr and Cu were higher than sediment quality guidelines at some sampling sites, implying potential adverse impacts of these metals

  20. High temperature electron beam ion source for the production of single charge ions of most elements of the Periodic Table

    Panteleev, V N; Barzakh, A E; Fedorov, D V; Ivanov, V S; Moroz, F V; Orlov, S Y; Seliverstov, D M; Stroe, L; Tecchio, L B; Volkov, Y M

    2003-01-01

    A new type of a high temperature electron beam ion source (HTEBIS) with a working temperature up to 2500 deg. C was developed for production of single charge ions of practically all elements. Off-line tests and on-line experiments making use of the developed ion source coupled with uranium carbide targets of different density, have been carried out. The ionization efficiency measured for stable atoms of many elements varied in the interval of 1-6%. Using the HTEBIS, the yields and on-line production efficiency of neutron rich isotopes of Mn, Fe, Co, Cu, Rh, Pd, Ag, Cd, In, Sn and isotopes of heavy elements Pb, Bi, Po and some others have been determined. The revealed confinement effect of the ions produced in the narrow electron beam inside a hot ion source cavity has been discussed.

  1. Spatial distribution of metals in soils in Baltimore, Maryland: Role of native parent material, proximity to major roads, housing age and screening guidelines

    We investigated the spatial distribution of heavy metal above-background (anthropic) contents of Cd, Co, Cu, Cr, Fe, Mn, Ni, Pb, Ti, V, and Zn in Baltimore City surface soils and related these levels to potential contaminating sources. Composite soil samples (0-10 cm depth) were digested using a nitric and hydrochloric extraction technique. Slightly more than 10% of plots exceeded United States Environmental Protection Agency screening guidelines for Pb. In a principal component analysis, the first component corresponded to Co, Cr, and Fe, which are constituents of local mafic rocks. The second component corresponded to Cu, Pb, and Zn which were significantly higher within than beyond a 100 m buffer of the major roads within the city; furthermore, Pb and Zn were higher in older residential lots. - Spatial distribution of metals in soils of an older US city (Baltimore) was affected by parent material, proximity to major roads, and housing age

  2. Study of magnetic multilayers by RBS with nanometer resolution

    The interface roughness of thermally grown giant magnetoresistance (GMR) multilayers was investigated with nanometer depth scale by Rutherford backscattering spectroscopy (RBS) using a high-resolution magnetic spectrograph. Co/Cu multilayers were prepared by electron beam evaporation under ultra-high vacuum conditions in an MBE system. The samples were measured by RBS under several scattering angles to obtain the concentration depth profiles. Ion beam mixing effects deduced from the experimental data and theoretical models were used to unfold the experimental spectra, giving the initial interface roughness. It is shown that the interface roughness, comparable to the amount of surface roughness, is probably not responsible for the extremely weak GMR effect, found in this type of samples

  3. Magnetization reversal via a Stoner–Wohlfarth model with bi-dimensional angular distribution of easy axis

    Kuncser, A. [National Institute of Materials Physics, 105 bis Atomistilor Street, 077125 Bucharest-Magurele (Romania); Faculty of Physics, University of Bucharest, 405 Atomistilor Street, 077125 Bucharest-Magurele (Romania); Kuncser, V., E-mail: kuncser@infim.ro [National Institute of Materials Physics, 105 bis Atomistilor Street, 077125 Bucharest-Magurele (Romania)

    2015-12-01

    A numerical extension of the simple Stoner–Wohlfarth model to the case of bi-dimensional angular distributions of easy axis is provided. The results are particularized in case of step-like, Gaussian-like and user defined distributions. In spite of its simplicity, the model can be applied to magnetically textured thin films and multilayers with in-plane magnetic anisotropy, independently on the texture source. Exemplifications are provided for a simple ferromagnetic textured FeCo film as well as for a FeMn/FeCo/Cu/FeCo spin valve structure. - Highlights: • Magnetic texture effects are included in the Stoner–Wohlfarth problem. • Step-like, Gaussian-like and user defined angular EADs are discussed. • The magnetic texture is obtained from the overall magnetization reversal. • Results beyond the OR method can be provided for complex systems.

  4. Exchange Coupling of Spin-Crossover Molecules to Ferromagnetic Co Islands.

    Gueddida, Saber; Gruber, Manuel; Miyamachi, Toshio; Beaurepaire, Eric; Wulfhekel, Wulf; Alouani, Mebarek

    2016-03-01

    The properties of Fe(1,10-phenanthroline)2(NCS)2 (Fe-phen) molecules deposited on Co/Cu(111) are studied with scanning tunneling microscopy (STM) operated in ultrahigh vacuum at low temperature (4 K) and ab initio calculations. Both the experimental and theoretical results are used to identify the high-spin (HS) state of Fe-phen. Additionally, the calculations reveal a strong spin-polarization of the density of states (DOS) and is validated experimentally using the spin sensitivity of spin-polarized STM. Finally, it is shown that the magnetic moment of the Fe-ion within HS Fe-phen is strongly magnetically coupled to the underlying magnetic Co through the NCS groups. These findings enable promising spintronic perspectives. PMID:26895075

  5. Quantitative assessment of atmospheric emissions of toxic heavy metals from anthropogenic sources in China: historical trend, spatial variation distribution, uncertainties and control policies

    H. Z. Tian

    2015-04-01

    Full Text Available Anthropogenic atmospheric emissions of typical toxic heavy metals have received worldwide concerns due to their adverse effects on human health and the ecosystem. By determining the best available representation of time-varying emission factors with S-shape curves, we established the multiyear comprehensive atmospheric emission inventories of 12 typical toxic heavy metals (Hg, As, Se, Pb, Cd, Cr, Ni, Sb, Mn, Co, Cu and Zn from primary anthropogenic activities in China for the period of 1949–2012 for the first time. Further, we allocated the annual emissions of these heavy metals in 2010 at a high spatial resolution of 0.5° × 0.5° grid with ArcGIS methodology and surrogate indexes, such as regional population and gross domestic product (GDP. Our results show that the historical emissions of Hg, As, Se, Cd, Cr, Ni, Sb, Mn, Co, Cu and Zn during the period of 1949–2012, have been increased by about 22–128 times at an annual average growth rate of 5.1–8.0%, amounting to about 79 570 t in 2012. Nonferrous metal smelting, coal combustion of industrial boilers, brake and tyre wear, and ferrous metals smelting represent the dominant sources for Hg / Cd, As / Se / Pb / Cr / Ni / Mn / Co, Sb / Cu, and Zn, respectively. In terms of spatial variation, the majority of emissions were concentrated in relatively developed regions, especially for the northern, eastern and southern coastal regions. In addition, because of the flourishing nonferrous metals smelting industry, several southwestern and central-southern provinces play a prominent role in some specific toxic heavy metals emissions, like Hg in Guizhou and As in Yunnan. Finally, integrated countermeasures are proposed to minimize the final toxic heavy metals discharge on accounting of the current and future demand of energy-saving and pollution reduction in China.

  6. Assessment of heavy metal contamination in water and sediments of Trepça and Sitnica rivers, Kosovo, using pollution indicators and multivariate cluster analysis.

    Ferati, Flora; Kerolli-Mustafa, Mihone; Kraja-Ylli, Arjana

    2015-06-01

    The concentrations of As, Cd, Cr, Co, Cu, Ni, Pb, and Zn in water and sediment samples from Trepça and Sitnica rivers were determined to assess the level of contamination. Six water and sediment samples were collected during the period from April to July 2014. Most of the water samples was found within the European and Kosovo permissible limits. The highest concentration of As, Cd, Pb, and Zn originates primarily from anthropogenic sources such discharge of industrial water from mining flotation and from the mine waste eroded from the river banks. Sediment contamination assessment was carried out using the pollution indicators such as contamination factor (CF), degree of contamination (Cd), modified degree of contamination (mCd), pollution load index (PLI), and geo-accumulation index (Igeo). The CF values for the investigated metals indicated a high contaminated nature of sediments, while the Cd values indicated a very high contamination degree of sediments. The mCd values indicate a high degree of contamination of Sitnica river sediment to ultrahigh degree of contamination of Trepça river sediment. The PLI values ranged from 1.89 to 14.1 which indicate that the heavy metal concentration levels in all investigated sites exceeded the background values and sediment quality guidelines. The average values of Igeo revealed the following ranking of intensity of heavy metal contamination of the Trepça and Sitnica river sediments: Cd > As > Pb > Zn > Cu > Co > Cr > Ni. Cluster analysis suggests that As, Cd, Cr, Co, Cu, Ni, Pb, and Zn are derived from anthropogenic sources, particularly discharges from mining flotation and erosion form waste from a zinc mine plant. In order to protect the sediments from further contamination, the designing of a monitoring network and reducing the anthropogenic discharges are suggested. PMID:25958086

  7. Impact of metals in surface matrices from formal and informal electronic-waste recycling around Metro Manila, the Philippines, and intra-Asian comparison

    Highlights: ► We quantified 11 metals in surface matrices from e-waste recycling sites at the Philippines. ► Dust had statistical higher levels of metal contamination and health risk compared to soil. ► Formal and informal sites had different metal contaminations. ► Intra-Asian comparison provided common insight on metal contamination from e-waste recycling. - Abstract: We report concentrations, enrichment factors, and hazard indicators of 11 metals (Ag, As, Cd, Co, Cu, Fe, In, Mn, Ni, Pb, and Zn) in soil and dust surface matrices from formal and informal electronic waste (e-waste) recycling sites around Metro Manila, the Philippines, referring to soil guidelines and previous data from various e-waste recycling sites in Asia. Surface dust from e-waste recycling sites had higher levels of metal contamination than surface soil. Comparison of formal and informal e-waste recycling sites (hereafter, “formal” and “informal”) revealed differences in specific contaminants. Formal dust contained a mixture of serious pollutant metals (Ni, Cu, Pb, and Zn) and Cd (polluted modestly), quite high enrichment metals (Ag and In), and crust-derived metals (As, Co, Fe, and Mn). For informal soil, concentration levels of specific metals (Cd, Co, Cu, Mn, Ni, Pb, and Zn) were similar among Asian recycling sites. Formal dust had significantly higher hazardous risk than the other matrices (p < 0.005), excluding informal dust (p = 0.059, almost significant difference). Thus, workers exposed to formal dust should protect themselves from hazardous toxic metals (Pb and Cu). There is also a high health risk for children ingesting surface matrices from informal e-waste recycling sites.

  8. Minerogenesis of Shilu Iron Ores with Special Reference to Sm—Nd Isotope Geochemical Characteristics of Shilu Group Bimodal Volcanic Rocks in Hainan Island

    方中; 赵建新; 等

    1994-01-01

    Presented in this paper are Sm-Nd isotope and major, trace and rare-earth element analyses of bimodal volcanic rocks of the Shilu Group and other stratigraphic units in northwestern Hainan Is-land ,South China. It is shown that there are some N-MORB-type basalts(spilites) in the western part of the bimodal volcanic belt, in addition to some E-MORB-type and initial rift-type tholeiites (IRT) in th emiddle and eastern parts.Sm-Nd model ages of these basalts range from 545 Ma to 460Ma .The other extremes of the bimodal volcanics are porphyritic quartz rhyolites, which are characteristic of crustal material source.Sm-Nd model ages of the rhyolites range from 1562 Ma to 1371 Ma .The bimodal volcanic rocks are almost distributed in fifts or faulted depressions,as well as in the Upper Paleozoic rift of Hainan Island.Tholeiites of the Shilu Group can be compared with Cenozoic basalts in the middle and south-ern parts of the Red Sea Rift Belt in petrology, elemental geochemistry and Sm-Nd isotope geology. Shilu iron ores are closely associated with N-MORB-type basalts located in the western bimodal vol-canic belt.It is very interesting to note that the Shilu Fe-Co-Cu deposit can also be compared with Atlantis II Deep in the Red Sea Rift Belt.Therefore ,the present authors believe that the Shilu depos-it is a kind of hydrothermal deposit related to ocean volcanic belt ,where the geotectonic setting be-longs to initial extensional rifts in the oceanic crust.On the other hand, the largest Fe-Co-Cu ore de-posit in China used to be influenced by Hercynian granites after mineralization ,as is clearly observed on both εNd(T)-1/Nd and εNd(T)-147Sm/144Nd diagrams.

  9. Growth and magnetic properties dependence of the Co–Cu/Cu films electrodeposited under high magnetic fields

    Franczak, Agnieszka, E-mail: agnieszka.franczak@mtm.kuleuven.be [Laboratoire d’Ingénierie et Sciences des Matériaux (LISM EA 4695), Université de Reims Champagne-Ardenne, UFR Sciences et Naturelles, Bat. 6, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2 (France); Department of Materials Science (MTM), KU Leuven, Kasteelpark Arenberg 44, 3001 Haverlee (Leuven) (Belgium); Levesque, Alexandra [Laboratoire d’Ingénierie et Sciences des Matériaux (LISM EA 4695), Université de Reims Champagne-Ardenne, UFR Sciences et Naturelles, Bat. 6, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2 (France); Zabinski, Piotr [Laboratory of Physical Chemistry and Electrochemistry, Faculty of Non-Ferrous Metals, AGH University of Science and Technology, al. A. Mickiewicza 30, 30059 Krakow (Poland); Li, Donggang [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, 314 Box, 110004 Shenyang (China); Czapkiewicz, Maciej [Department of Electronics, AGH University of Science and Technology, al. A. Mickiewicza 30, 30059 Krakow (Poland); Kowalik, Remigiusz [Laboratory of Physical Chemistry and Electrochemistry, Faculty of Non-Ferrous Metals, AGH University of Science and Technology, al. A. Mickiewicza 30, 30059 Krakow (Poland); Bohr, Frédéric [Laboratoire d’Ingénierie et Sciences des Matériaux (LISM EA 4695), Université de Reims Champagne-Ardenne, UFR Sciences et Naturelles, Bat. 6, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2 (France); and others

    2015-07-15

    The present work is focused on the investigations of magnetic properties dependence on microstructure of Co–Cu/Cu films electrodeposited under superimposed high magnetic field. The experimental results indicate a strong effect of an external magnetic field on the morphology of deposited films, more precisely on the Co:Cu ratio that determines the film growth. It is shown that the Co–Cu/Cu films electrodeposited without superimposed magnetic field consisted of two clearly visible features: compact film with incorporated granular particles. Under a superimposed external high magnetic field the privilege growth of the particles was induced. As a consequence, development of the well-defined branched structure of Co–Cu/Cu film was observed. In contrary, the phase compositional investigations do not reveal any changes in the phase formation during electrodeposition under magnetic field conditions. Thus, it is assumed that a strong growth of Co–Cu/Cu films in (111) direction under magnetic or non-magnetic electrodeposition conditions is related with the growth of Cu (111) plane and embedded into it some of the Co fcc atoms of same (111) orientation, as well as the Co hcp atoms that grows in the (002) direction. This non-equilibrium growth of Co–Cu/Cu films under magnetic deposition conditions affects strongly the magnetic properties of deposited films, revealing that films obtained under magnetic fields higher than 3 T were no more magnetic materials. - Highlights: • Co–Cu/Cu electrodeposits were obtained at elevated temperature under HMFs. • The effects of HMFs on microstructure and magnetic properties were investigated. • Interesting morphological changes due to HMFs has been observed. • Changes in Co:Cu ratio due to HMFs modified the magnetic properties of deposits.

  10. Growth and magnetic properties dependence of the Co–Cu/Cu films electrodeposited under high magnetic fields

    The present work is focused on the investigations of magnetic properties dependence on microstructure of Co–Cu/Cu films electrodeposited under superimposed high magnetic field. The experimental results indicate a strong effect of an external magnetic field on the morphology of deposited films, more precisely on the Co:Cu ratio that determines the film growth. It is shown that the Co–Cu/Cu films electrodeposited without superimposed magnetic field consisted of two clearly visible features: compact film with incorporated granular particles. Under a superimposed external high magnetic field the privilege growth of the particles was induced. As a consequence, development of the well-defined branched structure of Co–Cu/Cu film was observed. In contrary, the phase compositional investigations do not reveal any changes in the phase formation during electrodeposition under magnetic field conditions. Thus, it is assumed that a strong growth of Co–Cu/Cu films in (111) direction under magnetic or non-magnetic electrodeposition conditions is related with the growth of Cu (111) plane and embedded into it some of the Co fcc atoms of same (111) orientation, as well as the Co hcp atoms that grows in the (002) direction. This non-equilibrium growth of Co–Cu/Cu films under magnetic deposition conditions affects strongly the magnetic properties of deposited films, revealing that films obtained under magnetic fields higher than 3 T were no more magnetic materials. - Highlights: • Co–Cu/Cu electrodeposits were obtained at elevated temperature under HMFs. • The effects of HMFs on microstructure and magnetic properties were investigated. • Interesting morphological changes due to HMFs has been observed. • Changes in Co:Cu ratio due to HMFs modified the magnetic properties of deposits

  11. Annual variations of elemental quantities in brown sea algae hijiki Hizikia fusiforme

    Quantitative variation of 12 elements such as K, Ca, Fe, Co, Cu, Zn, As, Br, Sr, Rb, I and Pb in a brown algae, hijiki, Hizikia fusiforme, was observed from June 1982 through July 1983, using simultaneous multi-element analysis of PIXE. The patterns of variation on the elemental concentration were found to be classified into three groups. Br and Sr were complex in their annual variation patterns, showing minimum values in Jan., Mar. and Aug., which may relate to the physiological aspects of the sea algae concerned. Though three hollows were also found for Ca, its variation was typical in demonstrating minimum values just after the respective harvestings by fishermen. Fe, Co, Cu, Rb and Pb were elements with peaks showing a maximum only in Aug., probably influenced by environmental causes such as atmospheric pollution or seasonal changes of tides and currents around the experimental area. No variation was found for the element K, which is considered as a main component of algae tissues. A similar pattern was observed for such element as As, which also behaves as essential elements in the algae tissue. Iodine showed an irregular variation pattern, presenting triple peaks during the period. How-ever, the corresponding hollows did not coincide with the results given by elements like Sr and Br, which had similar patterns. The ranges of the variations between maximum and minimum values had a factor of 2-3. Radioecologically, the differences may explain significance of the results as certain indicators, when submitting more precise radiation doses applying concentration factors for radionuclides released from nuclear facilities into the sea

  12. Effect of nanoscale zero-valent iron and magnetite (Fe3O4) on the fate of metals during anaerobic digestion of sludge.

    Suanon, Fidèle; Sun, Qian; Mama, Daouda; Li, Jiangwei; Dimon, Biaou; Yu, Chang-Ping

    2016-01-01

    Anaerobic digestion (AD) is one of the most widely used processes to stabilize waste sewage sludge and produce biogas renewable energy. In this study, two different iron nanoparticles [nanoscale zero-valent iron (nZVI) and magnetite (Fe3O4)] were used in the mesophilic AD processes (37 ± 1 °C) to improve biogas production. In addition, changes of heavy metal (Cd, Co, Cu, Zn, Ni and Cr) speciation during AD of sludge with and without iron nanoparticles have been investigated. Concentrations of metals in the initial sludge were as follows: 63.1, 73.4, 1102.2, 2060.3, 483.9 and 604.1 mg kg(-1) (dry sludge basis) for Cd, Co, Cu, Zn, Ni and Cr, respectively. Sequential fractionation showed that metals were predominantly bonded to organic matter and carbonates in the initial sludge. Compared with AD without iron nanoparticles, the application of iron nanoparticles (at dose of 0.5% in this study) showed positive impact not only on biogas production, but also on improvement of metals stabilization in the digestate. Metals were found concentrated in Fe-Mn bound and residual fractions and little was accumulated in the liquid digestate and most mobile fractions of solid digestate (water soluble, exchangeable and carbonates bound). Therefore, iron nanoparticles when properly used, could improve not only biogas yield, but also regulate and control the mobilization of metals during AD process. However, our study also observed that iron nanoparticles could promote the immobilization of phosphorus within the sludge during AD, and more research is needed to fully address the mechanism behind this phenomenon and the impact on future phosphorus reuse. PMID:26613183

  13. Effects of elevated CO2 concentrations and fly ash amended soils on trace element accumulation and translocation among roots, stems and seeds of Glycine max (L.) Merr

    The carbon dioxide (CO2) levels of the global atmosphere and the emissions of heavy metals have risen in recent decades, and these increases are expected to produce an impact on crops and thereby affect yield and food safety. In this study, the effects of elevated CO2 and fly ash amended soils on trace element accumulation and translocation in the root, stem and seed compartments in soybean [Glycine max (L.) Merr.] were evaluated. Soybean plants grown in fly ash (FA) amended soil (0, 1, 10, 15, and 25% FA) at two CO2 regimes (400 and 600 ppm) in controlled environmental chambers were analyzed at the maturity stage for their trace element contents. The concentrations of Br, Co, Cu, Fe, Mn, Ni, Pb and Zn in roots, stems and seeds in soybeans were investigated and their potential risk to the health of consumers was estimated. The results showed that high levels of CO2 and lower concentrations of FA in soils were associated with an increase in biomass. For all the elements analyzed except Pb, their accumulation in soybean plants was higher at elevated CO2 than at ambient concentrations. In most treatments, the highest concentrations of Br, Co, Cu, Fe, Mn, and Pb were found in the roots, with a strong combined effect of elevated CO2 and 1% of FA amended soils on Pb accumulation (above maximum permitted levels) and translocation to seeds being observed. In relation to non-carcinogenic risks, target hazard quotients (TQHs) were significant in a Chinese individual for Mn, Fe and Pb. Also, the increased health risk due to the added effects of the trace elements studied was significant for Chinese consumers. According to these results, soybean plants grown for human consumption under future conditions of elevated CO2 and FA amended soils may represent a toxicological hazard. Therefore, more research should be carried out with respect to food consumption (plants and animals) under these conditions and their consequences for human health.

  14. In situ evaluation of DGT techniques for measurement of trace metals in estuarine waters: a comparison of four binding layers with open and restricted diffusive layers.

    Shiva, Amir Houshang; Bennett, William W; Welsh, David T; Teasdale, Peter R

    2016-01-01

    Four different DGT binding layers were used to make selective measurements of trace metals in coastal waters within The Broadwater (Gold Coast, Queensland). Chelex and PAMPAA (polyacrylamide-polyacrylic acid) binding layers were used to measure cations (Cd, Co, Cu, Mn, Ni, Pb, Zn), and Metsorb was used to measure anions (Al, As, Mo, Sb, V, W). A mixed binding layer (MBL) containing both Chelex and Metsorb was used to measure each of the trace metals and determine diffusive boundary layer (DBL) thicknesses. DGT measurements that were not corrected for the DBL thickness (0.049-0.087) were underestimated by 70% on average. Good agreement was observed between DGT-MBL and DGT-Chelex for measurement of Cd, Co, Cu, Ni, Pb and Zn, and between DGT-MBL and DGT-Metsorb for As, Sb and V. DGT-MBL measured significantly higher concentrations for Mn (compared with DGT-Chelex) and Al (compared with DGT-Metsorb). DGT-Chelex measured only 6-8% of Al species measured by either DGT-MBL or DGT-Metsorb. DGT-PAMPAA measurements of Cu, Pb and Al were lower than those of either DGT-MBL or DGT-Chelex varying from 74-81% for Cu to 54-70% for Pb and 51-55% for anionic Al(OH)4(-), suggesting that this binding layer may make more selective measurements. All measured trace metal concentrations were well below ANZECC water quality guidelines, except for Cu which was 2 to 10 times higher than trigger values. Each of the DGT techniques was deployed using both open and restricted diffusive layers (ODL and RDL). Most trace metal measurements were not significantly different with ODL and RDL for all binding layers. However, concentrations of Cu (CRDL/CODL = 0.68-0.75) and Al (CRDL/CODL = 0.73-0.79) were significantly different with DGT-MBL, DGT-Chelex and DGT-Metsorb. PMID:26678534

  15. Electrochemical recovery of cobalt and copper from spent Li-ion batteries as multilayer deposits

    Freitas, M.B.J.G.; Celante, V.G.; Pietre, M.K. [Universidade Federal do Espirito Santo, Departamento de Quimica, Laboratorio de Eletroquimica Aplicada, Av. Fernando Ferrari 514, Goiabeiras, Vitoria-ES, CEP: 29070-910 (Brazil)

    2010-05-15

    In this work, spent Li-ion batteries were used to form cobalt and copper multilayers by electrodeposition. The effects of pH on the nucleation and growth mechanism, morphology and crystalline structure were studied. The instantaneous nucleation mechanism occurs at pH 2.7 and progresses at pH 5.4 for cobalt electrodeposition on platinum, vitreous carbon and aluminum. Copper can be electrodeposited on cobalt by an instantaneous mechanism at pH 2.7 and progressively at pH 5.4. Using scanning electron microscopy, we verified a more porous electrodeposit at pH 5.4 than at pH 2.7. X-ray diffractograms showed the peaks of Cu{sub 2}O, CuO and the Co and Cu cubic centered face structures for both pH values at a charge density of 2.00 and 10.0 C cm{sup -2}. The electric circuit obtained by electrochemical impedance spectroscopy for Co-Cu multilayer growth at both pH 2.7 and 5.4 with a charge density equal to 2.0 and 10.0 C cm{sup -2} on Al has the form R{sub s}(R{sub p}QL). The presence of the constant phase element (Q) is attributed to the irregularity of the Co-Cu multilayer electrodeposits, and the inductive element (L) is associated with cobalt dissolution in acidic solution. (author)

  16. Thermodynamic properties and phase equilibria of selected Heusler compounds

    Yin, Ming

    Heusler compounds are ternary intermetallics with many promising properties such as spin polarization and magnetic shape memory effect. A better understanding of their thermodynamic properties facilitates future design and development. Therefore, standard enthalpies of formation and heat capacities from room temperature to 1500 K of selected Heusler compounds X2YZ (X = Co, Fe, Ni, Pd, Rh, Ru; Y = Co, Cu, Fe, Hf, Mn, Ni, Ti, V, Zr; Z = Al, Ga, In, Si, Ge, Sn) and half-Heusler compounds XYSn (X = Au, Co, Fe, Ir, Ni, Pd, Pt, Rh; Y = Hf, Mn, Ti, Zr) were measured using high temperature direct reaction calorimetry. The measured standard enthalpies of formation were compared with those predicted from ab initio calculations and the extended semi-empirical Miedema's model. Trends in standard enthalpy of formation with respect to the periodic classification of elements were discussed. The effect of a fourth element (Co, Cu, Fe, Pd; Ti, V; Al, Ga, In, Si, Ge) on the standard enthalpy of formation of Ni2MnSn was also investigated. Lattice parameters of the compounds with an L21 structure were determined using X-ray powder diffraction analysis. Differential scanning calorimetry was used to determine melting points and phase transformation temperatures. Phase relationships were investigated using scanning electron microscopy with an energy dispersive spectrometer. The isothermal section of the Fe-Sn-Ti ternary system at 873 K was established using equilibrated alloys. Three ternary compounds including the Heusler compound Fe2SnTi were observed. A new ternary compound Fe5Sn9Ti 6 was reported and the crystal structure of FeSnTi2 was determined for the first time.

  17. Occurrence of metal ions in rice produced in Uruguay

    Mario Rivero

    2011-04-01

    Full Text Available The United Nations General Assembly declared the year 2004 the International Year of Rice under the concept "Rice is Life". The largest nutritional problems occurring globally are protein-energy malnutrition, Ca, Fe, I, Zn and vitamin A deficiencies. Being rice the staple food more consumed worldwide, outstanding care is taken on its composition levels.Uruguay has emerged as medium-size rice producer and Latin America's major rice exporter, and is now amongst the world's top ten. Thus, the knowledge of toxic as well as micronutrient elements is very important. Here is reported the determination in forty nine samples of rice (Oryza sativa L. of As, Cd, Cr, and Pb by ET AAS in samples digested by dry ashing, and Ca, Co, Cu, Fe, K, Mg, Mo, Mn, Na, Ni and Zn by FAAS and Hg by CV AAS using microwave-assisted decomposition.The amount of all the metal ions studied in this work fall within the range typical of rice around the world. All the rice samples tested showed lower levels of As, Cd, Hg and Pb than the maximum limit permitted by governmental and international organizations.Potassium was the most abundant mineral followed by Mg and Ca and amongst microelements the presence of Cu, Fe, Mo, Mn, Na and Zn was outstanding.The milling process highly affects the contents of K, Mg, Mn, Na and Zn while little influence has on Ca, Co, Cu and Fe concentrations.Unexpected loss of Ca, Fe and Mn during parboiling process was detected. 

  18. Certification of Trace Element Mass Fractions in IAEA-457 Marine Sediment Sample

    The primary goal of the IAEA Environment Laboratories in Monaco (NAEL) is to help Member States understand, monitor and protect the marine environment. The major impact exerted by large coastal cities on marine ecosystems is therefore of great concern to the IAEA and its Environment Laboratories. Given that marine pollution assessments of such impacts depend on accurate knowledge of contaminant concentrations in various environmental compartments, the NAEL has assisted national laboratories and regional laboratory networks through its Reference Products for Environment and Trade programme since the early 1970s. Quality assurance (QA), quality control (QC) and associated good laboratory practice are essential components of all marine environmental monitoring studies. QC procedures are commonly based on the analysis of certified reference materials and reference samples in order to validate analytical methods used in monitoring studies and to assess reliability and comparability of measurement data. QA can be realized by participation in externally organized laboratory performance studies, also known as interlaboratory comparisons, which compare and evaluate analytical performance and measurement capabilities of participating laboratories. Data that are not based on adequate QA/QC can be erroneous and their misuse can lead to incorrect environmental management decisions. A marine sediment sample with certified mass fractions for Ag, Al, As, Cd, Cr, Co, Cu, Fe, Hg, Li, Mn, Ni, Pb, Sn, Sr, V and Zn was recently produced by the NAEL in the frame of a project between the IAEA and the Korea Institute of Ocean Science and Technology. This report describes the sample preparation methodology, the material homogeneity and stability study, the selection of laboratories, the evaluation of results from the certification campaign and the assignment of property values and their associated uncertainty. As a result, reference values for mass fractions and associated expanded

  19. Availability of metals in samples of phosphogypsum and phosphate fertilizers used in agriculture

    The Brazilian phosphate fertilizer is obtained by wet reaction of the igneous phosphate rock with concentrated sulphuric acid, giving as final product, phosphoric acid, and dehydrated calcium sulphate (phosphogypsum) as by-product. Part of this phosphogypsum is stored in stacks at open air and part has been used in agriculture, as soil amendment. To assure a safe utilization of phosphogypsum it is important to determine the levels of impurities, particularly of metals, present in phosphogypsum. In this paper, the concentration of metals (As, Ba, Cd, Cr, Co, Cu, Hg, Ni, Pb, Se, Zn and rare earth elements) present in Brazilian phosphogypsum and also in single super phosphate (SSP), triple super phosphate (TSP), monoammonium phosphate (MAP) and diammonium phosphate (DAP) were determined. The metals Cd, Cu, Ni, Pb and Zn were determined following the procedure 'EPA 3052'. The same elements, As and Se were also determined following the procedure 'EPA 3050B', recommended by Ministerio da Agricultura, Pecuaria e Abastecimento (MAPA). All these metals are controlled by environmental and agriculture regulation institutes in Brazil. The concentrations obtained for the metals analyzed by using the two procedures were different. Ba, Co, Cr and rare earth elements were determined by neutron activation analysis. In order to evaluate the availability of these metals As, Cd, Cr, Co, Cu, Ni, Pb, Se and Zn to the environment, the content of the same elements were determined following a procedure established by the EC (European Community), which includes an initial attack of the samples with EDTA-NH4 0.05M, at pH 7.0. In all these cases, phosphogypsum presented metals concentration lower than the phosphate fertilizers, and the results are below the limits adopted by MAPA and Companhia Ambiental do Estado de Sao Paulo (CETESB). The results obtained using the methodology with mild attack show that the metals are not available to the environment, giving evidence that the application of

  20. An approach to studying heavy metal pollution caused by modern city development in Nanjing, China

    Zhang Hui [Ineer Mongolia Univ., Huhehot, NM (China). Dept. of Ecology and Environmental Science; Ma Dongsheng [Nanjing Univ. (China). State Key Lab. for Research of Mineral Deposits; Xie Qinglin [Guilin Inst. of Technology (China). Dept. of Natural Resources and Environmental Engineering; Chen Xiaoling [Wuhan Technical Univ. of Surveying and Mapping (China). National Lab. for Information Engineering in Surveying, Mapping and Remote Sensing

    1999-09-01

    Nanjing is currently one of the fastest developing regions in terms of construction and economy in China. Heavy metal pollution is becoming more serious with the expansion of production and life scales. Four environmental units (highway, refinery, rubbish dumps associated with human daily life, and shoal of the Yangtse River) were selected from the region according to the geneses of the pollution to study and evaluate the distribution and mechanism of the contamination, the speciations of the polluting elements, and the geneses of the pollution in the soils and sediments. The purposes of the study are to understand generally the current situation and the cause of the pollution, and to provide a scientific basis to prevent and solve the pollution problem. At the same time, it would be helpful to probe the effective way of studying heavy metal pollution resulting from the development of modern cities and to accumulate data. It is indicated by the study that the heavy metals contained in the soil of the environmental unit of the highway are Pb, Co and Cr; in the soil of the refinery Cr, V, Pb, Ni, and Co; in the soil of the rubbish plot Co, Cu, and Sb; in the sediments of the shoal Pb, Co, Cu, and Ni. Fe-Mn oxide is given the first place to the speciations in polluting heavy metals transmitted by air. Carbonate is more in speciations of polluting heavy metals transmitted by water than in speciations of the metals transmitted by air. In the ten elements studied, Pb is most directly poisonous to the plants in the region; Co and Cu are the next, and Ni is the least. Heavy metal pollution has been occurring in the soils and sediments of the region and the situation will worsen if some effective measures are not taken. (orig.)

  1. STM tip-mediated mass transport on Cu surfaces

    Highlights: • Tip-induced atomic motion of Co atoms embedded in the Cu (0 0 1) surface in the presence of vacancies. • Interlayer mass transport at the island edge is found to depend strongly on the tip height and the lateral distance from the tip. • The jumping and the Ehrlich–Schwoebel (E–S) diffusion barrier can be reduced by tip manipulation. - Abstract: Atomic-scale simulations are performed to study atomic motion on Cu surfaces to illustrate the effect of the scanning tunneling microscopy tip on mass transport (MT) in the surfaces and on top of the Co island in heteroepitaxial Co/Cu(0 0 1) and Co/Cu(1 1 1) systems. First we investigate tip-induced atomic motion of Co atoms embedded in the Cu(0 0 1) surface at zero bias voltage. With the help of the tip, the Co atom in the surface can freely diffuse toward its nearby vacancy site. So-called vacancy mechanism is used to interpret this phenomenon. Then tip-mediated atomic motion of Co adatoms on the Co islands supported by a Cu(1 1 1) surface is studied. It is revealed that the tip has a significant effect on the diffusion of adatoms on the islands and interlayer mass transport at the island edge. Interlayer mass transport at the island edge is found to depend strongly on the tip height and the lateral distance from the tip. By calculating the diffusion barriers, it is found that the jumping diffusion barrier on the island can be zero by the tip vertical manipulation while the Ehrlich–Schwoebel diffusion barrier at the island edge can be reduced by the tip lateral manipulation. Thus, the quality of thin films can be improved by controlling MT in and/or on the surface

  2. Heavy Metals Analysis and Sediment Quality Values in Urban Lakes

    Aboud S. Jumbe

    2009-01-01

    Full Text Available Problem statement: The objective of this research was to evaluate the degree of heavy metal contamination in lakes and the extent to which the sediment quality of the lakes of Bangalore city has deteriorated. Approach: In this study, heavy metals such as Cd, Co, Cu, Cr, Mn, Pb, Ni and Zn in lake bed sediments were analyzed using comparative sediment quality guidelines from various derived criteria. The selection of sampling points was based upon inflow and outflow regions of the lakes; geographical proximity of industrial units in relation to their effluent discharges; proximity of residential sites located on the banks of the wetland systems; drainage patterns and accessibility towards the lakes. Digestion and analysis of the samples were done by microwave-assisted digestion and atomic absorption spectrophotometry respectively. Results: The extent of sediment quality deterioration was more pronounced in Cu (203.50 ppm and Ni (97.64 ppm followed by Pb (206.0 ppm and Cd (8.38 ppm. Cr (96.70 ppm failed a single sediment quality guideline while Zn (220.0 ppm, Mn (176.0 ppm and Co (47.7 ppm remained within the safety levels of sediment quality guidelines prescribed for the study. The Sediment Geo-accumulation Index showed that Co, Cu and Pb showed moderate levels of pollution while the Pollution Load Index (PLI between heavy metals in the lakes produced the following outputs: Ni > Pb > Cd > Cu > Cr > Co > Zn > Mn. Conclusion: This study proves that the level of sustained metal contamination of the fragile urban wetlands has not receded even after the recent urban wetlands rejuvenation works were completed. This prolonged presence in excessive levels of the studied heavy metals in the bed sediments casts doubt on the choice and effectiveness of the any mitigation measures in the long run.

  3. Factorial discriminant analysis of occupational exposure in metallurgy using INAA of hair samples

    A multivariate statistical technique - factorial discriminant analysis (FDA) - has been applied to evaluate the occupational exposure of a group of metallurgy workers using the elemental composition of their scalp hair, as compared with a control group. The initial variables were the concentrations of ten minor and trace elements determined in hair samples by using instrumental neutron activation analysis (INAA) : Al, Co, Cu, Fe, Mg, Mn, Sb, Se, V, and Zn. The elemental concentrations in the hair samples collected from 20 metallurgical workers and 59 controls showed a great variability. A wide variety of factors can account for this: sex, age, hair structure, general health, diet, socioeconomic status, occupation and environmental pollution. The concentration levels of Al, Co, Cu, Fe, Mg, Mn, Sb, V, and Zn are evidently higher in the hair of metallurgy workers, as compared with control group. Most of the variables showed log-normal distributions, except for Zn and Se, which had normal distributions. The univariate statistical analyses for these elemental concentrations have proved that the occupational exposure to metallic elements is reflected in hair composition. In this study FDA was applied to the same INAA data in order to test the possibility of developing linear classifiers that can separate the subjects exposed to metallic elements from unexposed ones, using the elemental content of their scalp hair. This would permit to evaluate the prediction ability of the classification rules obtained where unknown subjects are concerned. A good discrimination between exposed and control subjects (100 percent classification abilities) has been achieved after the normalization of the data (by log-transforming the initial variables) and considering sex-matched groups. To measure the accuracy of the classification and the predictive ability a cross-validation procedure was used. The predictive abilities obtained with our classifiers were 100 percent for exposed males and

  4. Quantitative assessment of atmospheric emissions of toxic heavy metals from anthropogenic sources in China: historical trend, spatial distribution, uncertainties, and control policies

    Tian, H. Z.; Zhu, C. Y.; Gao, J. J.; Cheng, K.; Hao, J. M.; Wang, K.; Hua, S. B.; Wang, Y.; Zhou, J. R.

    2015-09-01

    Anthropogenic atmospheric emissions of typical toxic heavy metals have caused worldwide concern due to their adverse effects on human health and the ecosystem. By determining the best available representation of time-varying emission factors with S-shape curves, we establish the multiyear comprehensive atmospheric emission inventories of 12 typical toxic heavy metals (Hg, As, Se, Pb, Cd, Cr, Ni, Sb, Mn, Co, Cu, and Zn) from primary anthropogenic activities in China for the period of 1949-2012 for the first time. Further, we allocate the annual emissions of these heavy metals in 2010 at a high spatial resolution of 0.5° × 0.5° grid with ArcGIS methodology and surrogate indexes, such as regional population and gross domestic product (GDP). Our results show that the historical emissions of Hg, As, Se, Cd, Cr, Ni, Sb, Mn, Co, Cu, and Zn, during the period of 1949-2012, increased by about 22-128 times at an annual average growth rate of 5.1-8.0 %, reaching about 526.9-22 319.6 t in 2012. Nonferrous metal smelting, coal combustion of industrial boilers, brake and tyre wear, and ferrous metal smelting represent the dominant sources of heavy metal emissions. In terms of spatial variation, the majority of emissions are concentrated in relatively developed regions, especially for the northern, eastern, and southern coastal regions. In addition, because of the flourishing nonferrous metal smelting industry, several southwestern and central-southern provinces play a prominent role in some specific toxic heavy metals emissions, like Hg in Guizhou and As in Yunnan. Finally, integrated countermeasures are proposed to minimize the final toxic heavy metals discharge on account of the current and future demand of energy-saving and pollution reduction in China.

  5. Study of some properties of bound levels and virtual levels excited with resonance neutrons; Etude de quelques proprietes de niveaux lies et de niveaux virtuels excites a l'aide de neutrons de resonance

    Alves, R.N. [Commissariat a l' Energie Atomique, 91 - Saclay (France). Centre d' Etudes Nucleaires

    1968-05-01

    Many neutron resonance parameters of some nuclei with a spin value I 3/2 ({sup 35}Cl, {sup 37}Cl, {sup 63}Cu, {sup 65}Cu, {sup 197}Au) are determined to find the strength function S{sub 0} with accuracy. For those nuclei, the S{sub 0} value seems not to depend on the spin value J=1 or 2 but could be depend on neutron energy for {sup 197}Au. Total radiative width variation against mass number A and spacing distributions between resonances (for {sup 197}Au) are studied and discussed. Analysis methods of neutron capture experiments are described in detail and level schemes of Cl, Mn, Fe, Co, Cu, Tm, Hg are presented sometimes with the spin value. Intensities of E{sub 1} and M{sub 1} transitions with direct capture and interference effects are discussed in view of experimental results. (author) [French] On determine les parametres des resonances de quelques noyaux de spin I 3/2 ({sup 35}Cl, {sup 37}Cl, {sup 63}Cu, {sup 65}Cu, {sup 197}Au) en nombre suffisant pour obtenir la fonction densite S{sub 0} avec precision. Cette valeur S{sub 0} apparat pour ces noyaux etre independante de la valeur du spin J=1 ou 2 mais para?t, dans le cas de {sup 197}Au, dependre de l'energie. On etudie et on essaie d'interpreter la variation de la largeur radiative totale {gamma}{sub {gamma}} en fonction du nombre de masse A et les distributions des espacements entre resonances pour {sup 197}Au. On expose en detail les methodes d'analyse des experiences de capture et on presente les schemas des niveaux des noyaux: Cl, Mn, Fe, Co, Cu, Tm, Hg. Les intensites des transitions de type E{sub 1} et M{sub 1} ainsi que les effets d'interference et de capture directe sont discutes. (auteur)

  6. Impact of metals in surface matrices from formal and informal electronic-waste recycling around Metro Manila, the Philippines, and intra-Asian comparison

    Fujimori, Takashi, E-mail: fujimori.takashi@nies.go.jp [Center for Material Cycles and Waste Management Research, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, 305-8506, Ibaraki (Japan); Takigami, Hidetaka [Center for Material Cycles and Waste Management Research, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, 305-8506, Ibaraki (Japan); Agusa, Tetsuro; Eguchi, Akifumi [Center for Marine Environmental Studies, Ehime University, 2-5 Bunkyo-cho, Matsuyama, 790-8577, Ehime (Japan); Bekki, Kanae [Center for Material Cycles and Waste Management Research, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, 305-8506, Ibaraki (Japan); Division of Pharmaceutical Chemistry and Biology, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-cho, Kanazawa, 920-1192, Ishikawa (Japan); Yoshida, Aya; Terazono, Atsushi [Center for Material Cycles and Waste Management Research, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, 305-8506, Ibaraki (Japan); Ballesteros, Florencio C. [College of Engineering, University of the Philippines Diliman, Quezon City, 1101 (Philippines)

    2012-06-30

    Highlights: Black-Right-Pointing-Pointer We quantified 11 metals in surface matrices from e-waste recycling sites at the Philippines. Black-Right-Pointing-Pointer Dust had statistical higher levels of metal contamination and health risk compared to soil. Black-Right-Pointing-Pointer Formal and informal sites had different metal contaminations. Black-Right-Pointing-Pointer Intra-Asian comparison provided common insight on metal contamination from e-waste recycling. - Abstract: We report concentrations, enrichment factors, and hazard indicators of 11 metals (Ag, As, Cd, Co, Cu, Fe, In, Mn, Ni, Pb, and Zn) in soil and dust surface matrices from formal and informal electronic waste (e-waste) recycling sites around Metro Manila, the Philippines, referring to soil guidelines and previous data from various e-waste recycling sites in Asia. Surface dust from e-waste recycling sites had higher levels of metal contamination than surface soil. Comparison of formal and informal e-waste recycling sites (hereafter, 'formal' and 'informal') revealed differences in specific contaminants. Formal dust contained a mixture of serious pollutant metals (Ni, Cu, Pb, and Zn) and Cd (polluted modestly), quite high enrichment metals (Ag and In), and crust-derived metals (As, Co, Fe, and Mn). For informal soil, concentration levels of specific metals (Cd, Co, Cu, Mn, Ni, Pb, and Zn) were similar among Asian recycling sites. Formal dust had significantly higher hazardous risk than the other matrices (p < 0.005), excluding informal dust (p = 0.059, almost significant difference). Thus, workers exposed to formal dust should protect themselves from hazardous toxic metals (Pb and Cu). There is also a high health risk for children ingesting surface matrices from informal e-waste recycling sites.

  7. Metals and trace elements concentration in water and sediments of the hydrographic basins from Mogi-Guacu and Pardo rivers in the State of Sao Paulo, Brazil; Avaliacao de metais e elementos-traco em aguas e sedimentos das bacias hidrograficas dos rios Mogi-Guacu e Pardo, Sao Paulo

    Lemes, Marcos Jose de Lima

    2001-07-01

    interstitial phase showed 2 to 30 fold values than natural water. For supernatant and interstitial water, the most elements still at same concentration both phases, except for Al, Co and Cu that showed larger concentration on interstitial phase. The principal components analyzed was written six factors: the first and second factors (Ba, Ca, Fe, Mo, Mg, Na, Co, Cu and P) suggest geological formation; the third factor (Cl{sup -}, SO{sub 4}{sup 2-} and pluviometry) the possibility of an anthropogenic influence for natural water. For treatment water the software written 4 factors: the first and second factors (Mg, Ca, Ba, K{sup +} and P) have the possibility to be associated to geological formation, and the third and fourth factors (F{sup -}, Cl{sup -} and NO{sub 3}{sup -}) could be from used compounds at Water Treatment Station. The component principals analyze for supernatant and interstitial phases wrote three factors for both: the first factor (Mg, Ca, Mn and Fe) would be linkage to Granite-gneiss Complex, the second and third factors (Cu, Ba, P and Ni) suggest a linkage to metabasic and Pocos de Caldas alkaline rocks. The sediment samples also were analyzed by principal components and were got five factors: the first, second and third (Mn, Fe, Co, Cu, Cd Al, Ca and Ba), Fe, Co, Cu, Cd Al, Ca and Ba) factors suggests geological formation; the fourth factor (P) could be from Pocos de Caldas Complex. This study did not show the correlation among bioavailable metals with organic matter. (author)

  8. NOVEL PREPARATION AND MAGNETO CHEMICAL CHARACTERIZATION OF NANO-PARTICLE MIXED ALCOHOL CATALYSTS

    Seetala V. Naidu; Upali Siriwardane

    2005-01-14

    We have developed effective nanoparticle incorporated heterogeneous F-T catalysts starting with the synthesis of Fe, Co, Cu nanoparticles using Fe(acac){sub 3}, Co(acac){sub 2}, and Cu(acac){sub 2} precursors and incorporating the nanoparticles into alumina sol-gel to yield higher alkanes production. SEM/EDX, XRD, BET, VSM and SQUID experimental techniques were used to characterize the catalysts, and GC/MS were used for catalytic product analysis. The nanoparticle oxide method gave the highest metal loading. In case of mixed metals it seems that Co or Cu interferes and reduces Fe metal loading. The XRD pattern for nanoparticle mixed metal oxides show alloy formation between cobalt and iron, and between copper and iron in sol-gel prepared alumina granules. The alloy formation is also supported by DTA and VMS data. The magnetization studies were used to estimate the catalyst activity in pre- and post-catalysts. A lower limit of {approx}40% for the reduction efficiency was obtained due to hydrogenation at 450 C for 4 hrs. About 85% of the catalyst has become inactive after 25 hrs of catalytic reaction, probably by forming carbides of Fe and Co. The low temperature (300 K to 4.2 K) SQUID magnetometer results indicate a superparamagnetic character of metal nanoparticles with a wide size distribution of < 20 nm nanoparticles. We have developed an efficient and economical procedure for analyzing the F-T products using low cost GC-TCD system with hydrogen as a carrier gas. Two GC columns DC 200/500 and Supelco Carboxen-1000 column were tested for the separation of higher alkanes and the non-condensable gases. The Co/Fe on alumina sol-gel catalyst showed the highest yield for methane among Fe, Co, Cu, Co/Fe, Cu/Co, Fe/Cu. The optimization of CO/H{sub 2} ratio indicated that 1:1 ratio gave more alkanes distribution in F-T process with Co/Fe (6% each) impregnated on alumina mesoporous catalyst.

  9. Synthesis of subnanometer-diameter vertically aligned single-walled carbon nanotubes with copper-anchored cobalt catalysts

    Cui, Kehang; Kumamoto, Akihito; Xiang, Rong; An, Hua; Wang, Benjamin; Inoue, Taiki; Chiashi, Shohei; Ikuhara, Yuichi; Maruyama, Shigeo

    2016-01-01

    We synthesize vertically aligned single-walled carbon nanotubes (VA-SWNTs) with subnanometer diameters on quartz (and SiO2/Si) substrates by alcohol CVD using Cu-anchored Co catalysts. The uniform VA-SWNTs with a nanotube diameter of 1 nm are synthesized at a CVD temperature of 800 °C and have a thickness of several tens of μm. The diameter of SWNTs was reduced to 0.75 nm at 650 °C with the G/D ratio maintained above 24. Scanning transmission electron microscopy energy-dispersive X-ray spectroscopy (EDS-STEM) and high angle annular dark field (HAADF-STEM) imaging of the Co/Cu bimetallic catalyst system showed that Co catalysts were captured and anchored by adjacent Cu nanoparticles, and thus were prevented from coalescing into a larger size, which contributed to the small diameter of SWNTs. The correlation between the catalyst size and the SWNT diameter was experimentally clarified. The subnanometer-diameter and high-quality SWNTs are expected to pave the way to replace silicon for next-generation optoelectronic and photovoltaic devices.We synthesize vertically aligned single-walled carbon nanotubes (VA-SWNTs) with subnanometer diameters on quartz (and SiO2/Si) substrates by alcohol CVD using Cu-anchored Co catalysts. The uniform VA-SWNTs with a nanotube diameter of 1 nm are synthesized at a CVD temperature of 800 °C and have a thickness of several tens of μm. The diameter of SWNTs was reduced to 0.75 nm at 650 °C with the G/D ratio maintained above 24. Scanning transmission electron microscopy energy-dispersive X-ray spectroscopy (EDS-STEM) and high angle annular dark field (HAADF-STEM) imaging of the Co/Cu bimetallic catalyst system showed that Co catalysts were captured and anchored by adjacent Cu nanoparticles, and thus were prevented from coalescing into a larger size, which contributed to the small diameter of SWNTs. The correlation between the catalyst size and the SWNT diameter was experimentally clarified. The subnanometer-diameter and high

  10. Availability of metals in samples of phosphogypsum and phosphate fertilizers used in agriculture; Disponibilidade de metais em amostras de fosfogesso e fertilizantes fosfatados utilizados na agricultura

    Bourlegat, Fernanda Melo le

    2010-07-01

    The Brazilian phosphate fertilizer is obtained by wet reaction of the igneous phosphate rock with concentrated sulphuric acid, giving as final product, phosphoric acid, and dehydrated calcium sulphate (phosphogypsum) as by-product. Part of this phosphogypsum is stored in stacks at open air and part has been used in agriculture, as soil amendment. To assure a safe utilization of phosphogypsum it is important to determine the levels of impurities, particularly of metals, present in phosphogypsum. In this paper, the concentration of metals (As, Ba, Cd, Cr, Co, Cu, Hg, Ni, Pb, Se, Zn and rare earth elements) present in Brazilian phosphogypsum and also in single super phosphate (SSP), triple super phosphate (TSP), monoammonium phosphate (MAP) and diammonium phosphate (DAP) were determined. The metals Cd, Cu, Ni, Pb and Zn were determined following the procedure 'EPA 3052'. The same elements, As and Se were also determined following the procedure 'EPA 3050B', recommended by Ministerio da Agricultura, Pecuaria e Abastecimento (MAPA). All these metals are controlled by environmental and agriculture regulation institutes in Brazil. The concentrations obtained for the metals analyzed by using the two procedures were different. Ba, Co, Cr and rare earth elements were determined by neutron activation analysis. In order to evaluate the availability of these metals As, Cd, Cr, Co, Cu, Ni, Pb, Se and Zn to the environment, the content of the same elements were determined following a procedure established by the EC (European Community), which includes an initial attack of the samples with EDTA-NH{sub 4} 0.05M, at pH 7.0. In all these cases, phosphogypsum presented metals concentration lower than the phosphate fertilizers, and the results are below the limits adopted by MAPA and Companhia Ambiental do Estado de Sao Paulo (CETESB). The results obtained using the methodology with mild attack show that the metals are not available to the environment, giving

  11. Effects of organic or inorganic cobalt, copper, manganese, and zinc supplementation to late-gestating beef cows on productive and physiological responses of the offspring.

    Marques, R S; Cooke, R F; Rodrigues, M C; Cappellozza, B I; Mills, R R; Larson, C K; Moriel, P; Bohnert, D W

    2016-03-01

    Eighty-four multiparous, nonlactating, pregnant Angus × Hereford cows were ranked by pregnancy type (56 AI and 28 natural service), BW, and BCS and allocated to 21 drylot pens at the end of their second trimester of gestation (d 0). Pens were assigned to receive forage-based diets containing 1) sulfate sources of Cu, Co, Mn, and Zn (INR); 2) an organic complexed source of Cu, Mn, Co, and Zn (AAC; Availa 4; Zinpro Corporation, Eden Prairie, MN); or 3) no supplemental Cu, Co, Mn, and Zn (CON). Diets were offered from d 0 until calving and formulated to meet requirements for energy, protein, macrominerals, Se, I, and vitamins. The INR and AAC diets provided the same daily amount of Cu, Co, Mn, and Zn. Cow BW and BCS were recorded and liver samples were collected on d -10 and 2 wk (d 75) before the calving season. Within 3 h after calving, calf BW was recorded, liver samples were collected, and the expelled placenta was retrieved ( = 47 placentas). Calves were weaned on d 283 of the experiment, preconditioned for 45 d (d 283 to 328), transferred to a growing lot on d 328, and moved to a finishing lot on d 440 where they remained until slaughter. Liver Co, Cu, and Zn concentrations on d 75 were greater ( ≤ 0.05) for INR and AAC cows compared with CON cows, whereas INR cows had reduced ( = 0.04) liver Co but greater ( = 0.03) liver Cu compared with AAC cows. In placental cotyledons, Co concentrations were greater ( ≤ 0.05) in AAC and INR cows compared with CON cows, whereas Cu concentrations were increased ( = 0.05) only in AAC cows compared with CON cows. Calves from INR and AAC cows had greater ( calves from CON cows. Liver Cu and Zn concentrations at birth were greater ( ≤ 0.05) in calves from AAC cows compared with cohorts from CON cows. Weaning BW was greater ( ≤ 0.05) in calves from AAC cows compared with cohorts from CON cows, and this difference was maintained until slaughter. In the growing lot, calves from AAC cows had reduced ( disease compared with

  12. Report on the intercomparison run NAT-5 for the determination of trace and minor elements in two lichen samples

    An intercomparison exercise was organized for two lichen materials, one from an unpolluted area in Portugal, the other from a mining area in Austria. 15 laboratories from 15 countries participated in the analysis providing 17 sets of results and using the following analytical methods: neutron activation analysis (NAA), inductive coupled plasma atomic emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), atomic absorption spectrometry (AAS) and particle induced X-ray emission analysis (PIXE). In all results were obtained for 51 elements for the sample lichen L-1, and for 47 elements for the sample lichen L-2. For the sample lichen L-1, more than 4 individual laboratory mean values were reported for 28 elements. Out of these, there was good agreement for the results obtained by different methods for 17 elements (Ba, Br, Ca, Cd, Cl, Co, Cu, Hg, K, La, Mn, Na, Pb, Rb, Sc, V, and Zn). Results for As, Ce, Cs, Sb and Se were available only by NAA. Statistical evaluation of the data revealed satisfactory values for Fe, Mg and Cr. In other cases the wide range of results did not permit a thorough evaluation. The final results for Al, Ni and Ti were unsatisfactory due to excessive dispersion observed in the reported ranges. For Ag, Au, Bi, Dy, Eu, Ga, Hf, I, Lu, Mo, Nd, P, S, Si, Sm, Sr, Ta, Tb, u, W, Yb and Zr only a few mean values were reported, and statistical evaluation was not possible. These results are simply listed in the Appendices I and II without any statistical data. For the sample lichen L-2, which was actually the IAEA reference material IAEA-336, 15 elements out of the 26 evaluated showed good agreement between different methods (Br, Ca, CI, Co, Cu, Fe, Hg, La, Mn, Na, Ni, Pb, Rb, V and Zn). For As, Ce, Cs, Sb, Sc and Se only NAA was used. Acceptable values were revealed for K, Mg and Cr. The results obtained for Al and Ti were unsatisfactory because the values showed excessive dispersion. Less than 5 laboratory means were

  13. Easy-Magnetization-Axis Arrangements of Sm2Co17 and RE2Fe14B

    2006-01-01

    In order to prepare the bulk samples with high residual magnetization of magnetic compounds, such as (Sm,La)2(Co,Cu,Fe,Zr)17, (Sm,La)1(Co,Cu,Fe)5, Nd2Fe14B, and Pr2Fe14B, directly prepared by solidification, or hot-deformation, it is the first thing to explore the possibilities of the easy magnetization axis of the whole bulk samples to be arranged in one designed direction. α is defined as the angle between the axis and the direction. In Sm-La-Co-Fe-Cu-Zr system, whether α is equal to 0° or 90° depends upon not only alloy compositions but also the ratio of the temperature gradient at the solid/liquid interface and the crystal growth rate. To some alloys, α can be changed from 90° to 0° if the ratio is increased to be higher than a critical value, so the c-axis texture orientation can be obtained. In Nd-Fe-B system, the easy magnetization axis of Nd2Fe14B is always perpendicular to the preferential growth direction [100], and the easy magnetization axes of Nd2Fe14B grains are randomly distributed in the plane normal to the growth direction even if the growth rate is decreased from 250 to 12 μm·s-1. But if the magnetization axis of the anisotropic magnet substrate is perpendicular to the heat flux direction of the laser melting solidification layer, c-axis texture of the columnar Nd2Fe14B grains in the layer can be obtained, which is the same as that of the substrate, if the laser scanning rate is not less than 25 μm·s-1. Also the c-axis texture [006] can be achieved through hot-deformation of PrxFe93.5-xB5Cu1.5 (x=15~19) under the conditions of hot-pressing temperature 973~1273 K, strain rate 10-3 S-1, and strain 50%~80%.

  14. Topsoil investigation on two different urban areas in West Hungary

    Horváth, Adrienn; Bidló, András

    2015-04-01

    Heavy metal contents of urban soils in two different urban areas have been investigated in Sopron town (169.01 km2) and in Szombathely town 97.50 km2) in Hungary. In a standard network 208 samples have been collected Sopron from 0 to 10 and from 10 to 20 cm depth. 164 samples have been taken on 88 points in the area of Szombathely. We analysed all of the soil samples with ICP equipment applying Lakanen-Erviö method (Ammonium Acetate - EDTA (pH 4.65)) and we focused on Co, Cu, Ni, Pb and Zn during the evaluation. The soils of suburb are determined largely by the bedrock, but in the downtown the soil pH was alkaline in soils of Sopron. Therefore, the toxic elements are still accumulated in the topsoil. The lead content was very high (suggested pollution limit >25 mg Pb/kg) in both layers on the whole area of the town. Urban soils with high copper content (among 611 mg and 1221 mg Cu/kg) have been collected from garden and viticulture areas. According to our measurements we found the highest average values in the soils of parks. The pH of urban topsoils of Szombathely was mostly neutral and it was lower in soil of agricultural areas on the suburb, where the artificial fertiliser is still used. The Pb content was high (more than 25 mg Pb/kg) in case of 13 samples next to traffic roads of the town. The Co, Cu and Ni results were below the suggested Hungarian background limits. The Zn values were above the suggested Hungarian pollution (20 mg Zn/kg) and interventional limits (>40 mg Zn/kg) in most cases. According to the results we found the highest average values of heavy metals in the soil of traffic areas or next to the Gyöngyös creek, which could be originated from traffic contamination, binding in the soil of urban green spaces, thus possibly affects human health. The research is supported by the "Agroclimate-2" (VKSZ_12-1-2013-0034) joint EU-national research project. Keywords: anthropogenic effects, heavy metal content, lead pollution, polluted urban soils

  15. Effects of elevated CO{sub 2} concentrations and fly ash amended soils on trace element accumulation and translocation among roots, stems and seeds of Glycine max (L.) Merr

    Rodriguez, J.H. [Multidisciplinary Institute of Plant Biology, Pollution and Bioindicator Section, Faculty of Physical and Natural Sciences, National University of Cordoba, Av. Velez Sarsfield 1611, X5016CGA Cordoba (Argentina); Klumpp, A.; Fangmeier, A. [Institute of Landscape and Plant Ecology (320), Plant Ecology and Ecotoxicology, Universitaet Hohenheim, August-von-Hartmann-Str. 3, 70599 Stuttgart (Germany); Pignata, M.L., E-mail: pignata@com.uncor.edu [Multidisciplinary Institute of Plant Biology, Pollution and Bioindicator Section, Faculty of Physical and Natural Sciences, National University of Cordoba, Av. Velez Sarsfield 1611, X5016CGA Cordoba (Argentina)

    2011-03-15

    The carbon dioxide (CO{sub 2}) levels of the global atmosphere and the emissions of heavy metals have risen in recent decades, and these increases are expected to produce an impact on crops and thereby affect yield and food safety. In this study, the effects of elevated CO{sub 2} and fly ash amended soils on trace element accumulation and translocation in the root, stem and seed compartments in soybean [Glycine max (L.) Merr.] were evaluated. Soybean plants grown in fly ash (FA) amended soil (0, 1, 10, 15, and 25% FA) at two CO{sub 2} regimes (400 and 600 ppm) in controlled environmental chambers were analyzed at the maturity stage for their trace element contents. The concentrations of Br, Co, Cu, Fe, Mn, Ni, Pb and Zn in roots, stems and seeds in soybeans were investigated and their potential risk to the health of consumers was estimated. The results showed that high levels of CO{sub 2} and lower concentrations of FA in soils were associated with an increase in biomass. For all the elements analyzed except Pb, their accumulation in soybean plants was higher at elevated CO{sub 2} than at ambient concentrations. In most treatments, the highest concentrations of Br, Co, Cu, Fe, Mn, and Pb were found in the roots, with a strong combined effect of elevated CO{sub 2} and 1% of FA amended soils on Pb accumulation (above maximum permitted levels) and translocation to seeds being observed. In relation to non-carcinogenic risks, target hazard quotients (TQHs) were significant in a Chinese individual for Mn, Fe and Pb. Also, the increased health risk due to the added effects of the trace elements studied was significant for Chinese consumers. According to these results, soybean plants grown for human consumption under future conditions of elevated CO{sub 2} and FA amended soils may represent a toxicological hazard. Therefore, more research should be carried out with respect to food consumption (plants and animals) under these conditions and their consequences for human

  16. Bioaccumulation of heavy metals and metalloids in luffa (luffa cylindrica l.) irrigated with domestic wastewater in jhang, pakistan: a prospect for human nutrition

    In the present study, 12 heavy metals (Cr, Mn, Ni, Cd, Co, Cu, Pb, Zn, Fe, Se, As, and Mo) were assessed in a potential vegetable Luffa cylindrica. The vegetable was collected randomly from two different sites located at Jhang, Punjab Pakistan. The analyses of variance of data collected from soil showed non-significant effect on Se, Zn, As, Cr, Ni, Mo and Pb while significant effect on Fe, Co, Mn, Cu and Cd metals. Concentrations of all 12 heavy metals in the soil samples were low at sampling site-I as compared to those at site-II except Ni. These concentrations were found below the safe limits except that of Cd. At site-I, the concentrations recorded for different heavy metals were: As > Fe > Pb > Mn > Cd > Co > Cu > Mo > Zn > Ni > Se > Cr while at site-II were: As > Fe > Mn > Pb > Co > Cd > Cu > Mo > Zn > Ni > Se > Cr. Enrichment co-efficient of Cr was higher which showed that root of luffa plant accumulated more Cr concentration from the contaminated soil. The order of enrichment co-efficient was recorded at site-I as: Cr > Zn > Mn > Cu > Fe > Ni > Mo > Pb > As > Se > Co > Cd, and at site-II Cr > Zn > Mn > Ni > Cu > Fe > Mo > Pb > Se > As > Co > Cd. The transfer co-efficient of Mn was higher which indicates that more contents of Mn were transferred from roots to upper edible part. The order of transfer co-efficient at site-I was: Ni > Se > Mo > Cr > Zn > Fe > Mn > Cd > Pb > As > Cu > Co and at site-II was Mn > Zn > As > Fe > Pb > Se > Cd > Co > Mo > Cu > Ni > Cr. Correlation analysis showed that Mn, Se, Co, Cd, Ni, Mo and Pb had positive non-significant correlation, whereas a negative and non-significant correlation for Zn, As, Fe and Cr. The order of pollution load index at site-I was Cd > Mo > Se > Pb > Cu > Co > As > Fe > Mn > Ni > Zn > Cr and at site-II: Cd > Mo > Se > Pb > Cu > Co > As > Fe > Mn > Ni > Zn > Cr. Overall, at both sites, lowest concentration of Cr and highest of As were observed which need substantial awareness. Health risk index depends on

  17. Declining metal levels at Foundry Cove (Hudson River, New York): Response to localized dredging of contaminated sediments

    This study examines the effectiveness of remediating a well-recognized case of heavy metal pollution at Foundry Cove (FC), Hudson River, New York. This tidal freshwater marsh was polluted with battery-factory wastes (1953-1979) and dredged in 1994-1995. Eight years after remediation, dissolved and particulate metals (Cd, Co, Cu, Pb, Ni, and Ag) were found to be lower than levels in the lower Hudson near New York City. Levels of metals (Co, Ni, Cd) on suspended particles were comparatively high. Concentrations of surface sediment Cd throughout the marsh system remain high, but have decreased both in the dredged and undredged areas: Cd was 2.4-230 mg/kg dw of sediment in 2005 vs. 109-1500 mg/kg in the same area in 1983. The rate of tidal export of Cd from FC has decreased by >300-fold, suggesting that dredging successfully stemmed a major source of Cd to the Hudson River. - Dredging of a hotspot of metal-contaminated sediment is associated with a recognizable local and river-wide decline in cadmium in the Hudson River, New York

  18. Determination of 11 major and minor elements in chondritic meteorites by inductively coupled plasma mass spectrometry.

    Wolf, Stephen F; Compton, Joseph R; Gagnon, Christopher J L

    2012-10-15

    We have developed a new method for the quantification of 11 major and minor elements (Na, Mg, Al, P, S, K, Ca, Cr, Mn, Fe, and Ni) in chondritic meteorites by ICPMS using external calibration with a matrix-matched standard prepared from the Allende Standard Reference Meteorite. We have demonstrated the method's accuracy and assessed three different measures of precision by performing replicate dissolutions and analyses of 0.10-g samples of a homogenized samples of the CM2 meteorite Murchison and compared our results to literature values. We subsequently applied this method to the analysis of a set of four chondritic meteorites possessing a relatively wide range of chondritic compositions with results in accord with previously published values. Because our method is designed to use the same instrumentation and can use samples and standards prepared according to methods previously validated for the determination of a comprehensive suite of minor, trace, moderately and highly volatile trace elements (i.e., Li, Sc, Ti, V, Mn, Co, Cu, Zn, Ga, As, Se, Rb, Sr, Y, Zr, Nb, Mo, Ru, Pd, Ag, Cd, In, Sn, Sb, Te, Cs, Ba, all 14 naturally occurring lanthanoids, Hf, W, Re, Ir, Pt, Tl, Bi, Th, and U) it complements these methods and allows a single laboratory to determine the concentrations of 60 elements in semimicroscopic amounts of chondritic material. PMID:23141337

  19. Determination of selected toxic elements in leaves of White Hawthorn grown in a remote area

    Zeiner M.

    2013-04-01

    Full Text Available One important plant of the Rosaceae family which is commonly used as phytopharmaceutical in Europe and North America is Hawthorn (Crataegus monogyna. The fruits, the leaves together with their extracts are applied in patients suffering mild cardiac disorders or nervosity. Since the leaves as well as the berries act as diuretics a sufficient micronutrient supply has to be guaranteed. On the other the quantities of toxic elements present in the plant parts should be at levels without harmful effects on human health. For this purpose Hawthorn leaves and flowers were collected in a remote area in 2011 and 2012 and analysed for their elemental composition. The metals uptaken from the soil were supposed to be in a similar range, thus the impact of airborne contamination by heavy metal translocation could be studied. The elements investigated were Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr, and Zn. After harvesting the samples were dried, homogenized, digested and then analysed by ICP-AES. The contents of all elements are in the μg/g range. In the samples of 2012 higher concentrations were found for Co, Cu, Mn, Ni, and Zn, lower concentrations were registered for Ba, Pb, and Sr. The amounts of Cd and Cr were statistically insignificantly lower in 2012 than 2011.

  20. Hydrothermal synthesis and magnetic properties of Co0.2Cu0.03Fe2.77O4 nanoparticles

    Co0.2Cu0.03Fe2.77O4 nanoparticles with different morphologies have been synthesized directly via a simple hydrothermal method. The effects of pH value, precursor concentration, reaction temperature and surfactant on the particle size were discussed. X-ray diffraction analyses showed that the as-synthesized Co0.2Cu0.03Fe2.77O4 nanoparticles possessed typical spinel structure. Scanning electron microscope images showed different morphologies of the particles, including truncated octahedron and octahedron. It was indicated that well-dispersed Co0.2Cu0.03Fe2.77O4 nanoparticles can be synthesized at pH values ranging from 11 to 13, and reaction temperature of 160 oC. The particle size decreased from 18 to 10 nm after the addition of sodium dodecyl sulphate at the pH value of 9. The magnetic measurement showed that the as-prepared Co-Cu spinel ferrite nanoparticles possessed hard magnetic property.

  1. Characterization of ancient glass excavated in Enez (Ancient Ainos) Turkey by combined Instrumental Neutron Activation Analysis and Fourier Transform Infrared spectrometry techniques

    Akyuz, Sevim, E-mail: s.akyuz@iku.edu.tr [Physics Department, Science and Letters Faculty, Istanbul Kultur University, Atakoy Campus, Bakirkoy 34156, Istanbul (Turkey); Akyuz, Tanil [Physics Department, Science and Letters Faculty, Istanbul Kultur University, Atakoy Campus, Bakirkoy 34156, Istanbul (Turkey); Mukhamedshina, Nuranya M.; Mirsagatova, A. Adiba [Institute of Nuclear Physics, Uzbek Academy of Sciences, 702132, Ulugbek, Tashkent (Uzbekistan); Basaran, Sait; Cakan, Banu [Department of Restoration and Conservation of Artefacts, Letters Faculty, Istanbul University, Vezneciler, Istanbul (Turkey)

    2012-05-15

    Ancient glass fragments excavated in the archaeological district Enez (Ancient Ainos)-Turkey were investigated by combined Instrumental Neutron Activation Analysis (INAA) and Fourier Transform Infrared (FTIR) spectrometry techniques. Multi-elemental contents of 15 glass fragments that belong to Hellenistic, Roman, Byzantine, and Ottoman Periods, were determined by INAA. The concentrations of twenty six elements (Na, K, Ca, Sc, Cr, Mn, Fe, Co, Cu, Zn, As, Rb, Sr, Sb, Cs, Ba, Ce, Sm, Eu, Tb, Yb, Lu, Hf, Ta, Au and Th), which might be present in the samples as flux, stabilizers, colorants or opacifiers, and impurities, were examined. Chemometric treatment of the INAA data was performed and principle component analysis revealed presence of 3 distinct groups. The thermal history of the glass samples was determined by FTIR spectrometry. - Highlights: Black-Right-Pointing-Pointer INAA was performed to determine elemental compositions of ancient glass fragments. Black-Right-Pointing-Pointer Basic, coloring/discoloring elements and impurities have been determined. Black-Right-Pointing-Pointer PCA discriminated the glasses depending on their chronological order. Black-Right-Pointing-Pointer The thermal history of the glass samples was determined by FTIR spectrometry.

  2. Elemental analysis of brazing alloy samples by neutron activation technique

    Two brazing alloy samples (C P2 and C P3) have been investigated by Neutron activation analysis (NAA) technique in order to identify and estimate their constituent elements. The pneumatic irradiation rabbit system (PIRS), installed at the first egyptian research reactor (ETRR-1) was used for short-time irradiation (30 s) with a thermal neutron flux of 1.6 x 1011 n/cm2/s in the reactor reflector, where the thermal to epithermal neutron flux ratio is 106. Long-time irradiation (48 hours) was performed at reactor core periphery with thermal neutron flux of 3.34 x 1012 n/cm2/s, and thermal to epithermal neutron flux ratio of 79. Activation by epithermal neutrons was taken into account for the (1/v) and resonance neutron absorption in both methods. A hyper pure germanium detection system was used for gamma-ray acquisitions. The concentration values of Al, Cr, Fe, Co, Cu, Zn, Se, Ag and Sb were estimated as percentages of the sample weight and compared with reported values. 1 tab

  3. Uraniferous mineralizations in the Kuusamo Schist Belt, northeastern Finland

    The Kouveraara Co-Cu-Au mineralization was found in 1982 with the aid of a geophysical ground survey. This survey was connected with research on the Kouvervaara uranium mineralization in the Early Proterozoic Kuusamo Schist Belt, located just south of the Arctic Circle. In further work, using the Kouvervaara sulphide mineralization as a reference, six Co and Au bearing sulphide mineralizations were discovered, with the help of low altitude aerial geophysical techniques. The Co-Au mineralizations, hosted by the Sericite Quartzite Formation, occur within the hydrothermally altered zones. These zones consist of chloritization, carbonatization, sulphidization, sericitization and albitization, the latter being the most extensive. Excluding the Juomasuo mineralization, uranium is only a trace element in these mineralizations. Other characteristic trace elements are molybdenum and tungsten. The Sivakkaharju and Konttiaho Co-Au-U-Mo mineralizations were found by radiometric ground surveys carried out in 1985 and 1986. These hydrothermal mineralizations occur within brecciated quartz-albite-carbonate rocks and are good manifestations of the positive correlation between uranium and gold in the Kuusamo area. Compared with the other sulphide mineralizations, the Au, U, and Mo contents are remarkably high. Genetically, the mineralizations in the Kuusamo area are associated with deep seated fracture and fault zones, controlled by ancient intracontinental hot spot activity and continental rifting. (author). 31 refs, 6 figs, 2 tabs

  4. Simultaneous determination of sub μg·g-1 levels of nine impurities in high purity iron by horizontal cation exchange resin mini-column and ICP-atomic emission spectrometry

    Inductively coupled plasma-atomic emission spectrometry (ICP-AES) has been applied to the simultaneous determination of trace impurities in high purity iron after simultaneous separation. Sub μg·g-1 levels of Ca, Cd, Co, Cu, Mg, Mn, Ni, Pb and Zn in high purity iron which had been dissolved in hydrofluoric acid and hydrogen peroxide were separated from the iron matrix using a horizontal cation exchange resin mini-column. Flow rates and flow directions of solutions through the mini-column were controlled by a peristaltic pump. Adsorbed elements on the resin mini-column were rapidly eluted using a reverse flow of the eluant against the flow for the adsorption. The eluted elements were determined by ICP-AES using an internal standard method and good results were obtained. A 100-fold enrichment of analytes was obtained with this preconcentration system using 1 g of the sample in comparison with an ordinary sample solution in which 0.5 g of the sample was dissolved in 100 cm3 without separation. (author)

  5. Seasonal variations of coastal sedimentary trace metals cycling: Insight on the effect of manganese and iron (oxy)hydroxides, sulphide and organic matter

    Highlights: • Multivariate statistic treatment (PCA) classified main elements and samples groups. • Trace metals mobility in porewater showed seasonal variations. • Strong control of Fe and Mn on metals dynamics at surface sediments. • Influence of dissolved organic matter on metal-sulphide equilibrium. - Abstract: The combination of analysis, multivariate treatment (PCA) and chemical speciation calculation confirmed the control of Fe, Mn, sulphide and organic matter on metals dynamics in coastal sediments (0–5 cm surface sediments and sediments cores) of Toulon Bay (NW Mediterranean). The temporal monitoring of the physic-chemical parameters as well as the dissolved/particulate minor (Fe/Mn) and trace elements (i.e. Ag, Cd, Co, Cu, Ni, Pb, Zn, …) concentrations in porewaters and sediments were assessed. Multivariate treatment revealed different behaviours for marine elements, terrestrial ones and contaminants. Seasonal variations of metals mobilization in porewater were observed, related to diagenesis activity. Element mobility was studied by selective extractions (ascorbate, acid and alkaline) on sediments. Thermodynamic simulation (PHREEQC) was performed to calculate the elemental dissolved speciation, the mineral saturation index and then to simulate the solid/liquid interaction through precipitation processes, studying the contrasted influence of dissolved organic matter and sulphide

  6. Local structure of nanosized tungstates revealed by evolutionary algorithm

    Timoshenko, Janis; Anspoks, Andris; Kuzmin, Alexei [Institute of Solid State Physics, University of Latvia, Riga (Latvia); Kalinko, Alexandr [Institute of Solid State Physics, University of Latvia, Riga (Latvia); Synchrotron SOLEIL, l' Orme des Merisiers, Saint-Aubin, Gif-sur-Yvette (France)

    2015-02-01

    Nanostructured tungstates, such as CoWO{sub 4} and CuWO{sub 4}, are very promising catalytic materials, particularly for photocatalytic oxidation of water. The high catalytic activity of tungstate nanoparticles partially is a result of their extremely small sizes, and, consequently, high surface-to-volume ratio. Therefore their properties depend strongly on the atomic structure, which differ significantly from that of the bulk material. X-ray absorption spectroscopy is a powerful technique to address the challenging problem of the local structure determination in nanomaterials. In order to fully exploit the structural information contained in X-ray absorption spectra, in this study we employ a novel evolutionary algorithm (EA) for the interpretation of the Co and Cu K-edges as well as the W L{sub 3}-edge extended X-ray absorption fine structure (EXAFS) of nanosized CoWO{sub 4} and CuWO{sub 4}. The combined EA-EXAFS approach and simultaneous analysis of the W L{sub 3} and Co(Cu) K-edge EXAFS spectra allowed us for the first time to obtain a 3D structure model of the tungstate nanoparticles and to explore in details the effect of size, temperature and transition metal type. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Investigations on the growth kinetics of Laves phase precipitates in 12% Cr creep-resistant steels: Experimental and DICTRA calculations

    Prat, O. [Max Planck Institute fuer Eisenforschung GmbH, Max Planck Strasse 1, 40237 Duesseldorf (Germany)] [Universidad de Concepcion, Departamento de Ingenieria de Materiales, Edmundo Larenas 270, Concepcion (Chile); Garcia, J., E-mail: jose.garcia@helmholtz-berlin.de [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Rojas, D. [Max Planck Institute fuer Eisenforschung GmbH, Max Planck Strasse 1, 40237 Duesseldorf (Germany); Carrasco, C. [Universidad de Concepcion, Departamento de Ingenieria de Materiales, Edmundo Larenas 270, Concepcion (Chile); Inden, G. [Max Planck Institute fuer Eisenforschung GmbH, Max Planck Strasse 1, 40237 Duesseldorf (Germany)

    2010-10-15

    The growth kinetics of Laves phase precipitates (type Fe{sub 2}W) in the early stage of creep (650 deg. C for 10,000 h) in two 12% Cr ferrite-martensitic steels has been investigated. In one alloy the Laves phase formed on tempering, while in the second alloy the Laves phase precipitated during creep. Kinetic simulations were performed using the software DICTRA. The particle size of the Laves phase was measured on transmission electron microscopy samples. The equilibrium phase fraction of the Laves phase was reached in the first thousand hours. Simulations of particle growth showed good agreement with the experimental results. Competitive growth between M{sub 23}C{sub 6} and the Laves phase showed that M{sub 23}C{sub 6} carbides reached their equilibrium after 12 days, whereas the Laves phase reached equilibrium after 3 months. Simulations of the influence of the interfacial energy and addition of Co, Cu and Si on Laves phase precipitation are presented.

  8. Heavy metals levels in muscle, gonads and gills of Brazilian fishes using SRTXRF

    Calza, Cristiane; Pereira, Marcelo O.; Lopes, Ricardo Tadeu [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Lab. de Instrumentacao Nuclear]. E-mail: ccalza@lin.ufrj.br; ricardo@lin.ufrj.br; Anjos, Marcelino Jose dos [Universidade do Estado, Rio de Janeiro, RJ (Brazil). Inst. de Fisica]. E-mail: marcelin@lin.ufrj.br; Araujo, Francisco Gerson [Universidade Federal Rural do Rio de Janeiro, RJ (Brazil). Lab. de Ecologia de Peixes]. E-mail: gerson@uffrj.br

    2005-07-01

    This work evaluated heavy metals levels in selected tissues of G. brasiliensis, O. hepsetus, H. luetkeni and H. affinis collected at the Paraiba do Sul River, Brazil. The muscle analysis was performed to evaluate the possible transfer of heavy metals to human beings through fish consumption; gonads were used to study the possible transfer and/or influence of metals, through the reproductive processes, to later generations of fishes; and gills are considered the primary action site for most metals, which are absorbed through fish breathing and/or ionic exchanges. The digestion procedure of samples was performed with HNO{sub 3} 65% in Teflon bombs, with heating at about 120 deg C. The analysis, using Total Reflection X-Ray Fluorescence with Synchrotron Radiation (SRTXRF), was performed at the LNLS (Brazilian Synchrotron Light Laboratory) using white beam and a Si(Li) detector with resolution of 165 eV. The elements identified were: Ti, Cr, Mn, Fe, Co, Cu, Zn, Rb, Sr, Ba and Pb. Fe and Zn exhibited the highest concentrations in the four species investigated. Comparing the results with the Brazilian Food Legislation Cr, Cu, Zn and Pb exceeded the maximum permissible limits in fish tissues. (author)

  9. [Heavy Metals Pollution in Topsoil from Dagang Industry Area and Its Ecological Risk Assessment].

    Zhang, Qian; Chen, Zong-juan; Peng, Chang-sheng; Li, Fa-sheng; Gu, Qing-bao

    2015-11-01

    Based on previous studies and field investigation of Dagang industry area in Tianjin, a total of 128 topsoil samples were collected, and contents of 10 heavy metals (As, Cd, Cr, Co, Cu, Pb, Ni, V, Zn and Hg) were determined. The geoaccumulation index and geostatistics were applied to examine the degree of contamination and spatial distribution of heavy metals in topsoil. The assessment on ecological risk of heavy metals was carried out using Hakanson's method, and the main resources of the heavy metals were analyzed as well. It was found that As, Cd and Co had the highest proportions exceeding Tianjin background value, which were 100%, 97.66% and 96.88%, respectively; the heavy-metal content increased to some extent comparing with that in 2004, and the pollutions of As and Cd were the worst, and other metals were at moderate pollution level or below. The ecological risks of heavy metals were different in topsoil with different land use types, the farmland soil in the southwest as well as soils adjacent to the industrial land were at relatively high potential ecological risk level, and the integrated ecological risk index reached up to 1 437.37. Analysis of correlation and principal component showed that traffic and transportation as well as agricultural activities might be the main resources of heavy metals in the area, besides, the industrial activities in the region might also affect the accumulation of heavy metals. PMID:26911014

  10. Mechanism for silicide formation in Ag(Cu)/Si and Ag(Co)/Si upon annealing

    Ag(Co) alloy and Ag(Cu) alloy films were prepared on HF-cleaned Si by using DC magnetron sputtering and were then annealed in vacuum (3 X 10-5 Torr) to investigate the effects of Co and Cu precipitation on the material properties of the Ag alloy films and on the reaction between alloy element (Co, Cu) and Si. The annealing of a Ag(Cu)/Si structure for 30 min at 200 .deg. C produced a uniform Cu3Si layer at the Ag(Cu)-Si interface, as a result of reaction of the segregated Cu with Si. This lowered the resistivity from 5.3 to 3.2 μΩ-cm, and also led to improved adhesion properties. In contrast, the annealing of a Ag(Co)/Si structure at 400 .deg. C produced a cobalt silicide in the Ag(Co) film, resulting from reaction of the diffused Si with Co precipitates, probably at the grain boundaries. The Co silicide formed at 400 .deg. C slightly increased the resistivity, which continued to decrease at temperatures of 500 .deg. C and higher. The different diffusing species in formation of Co silicide and Cu silicide may be attributed to the difference in the temperature of silicde formation and the mobility of the species.

  11. Risk assessment of hazardous impacts on urbanization and industrialization activities based upon toxic substances

    T. Salem

    2016-03-01

    Full Text Available A risk assessment study was conducted to predict the expected hazardous influence on the ecosystem resulted from urbanization and industrialization activities at Helwan area, Egypt. To achieve these goals, soils, plants and water samples were collected from Helwan area, and their total concentrations of inorganic contaminants (Cd, Cr, Co, Cu, Fe, Mn, Ni, Pb, and Zn and organic pollutants; such as Phenol and hydrocarbons were measured. The obtained results showed that, the concentrations of organic contaminants in water streams and surrounding soils recorded high concentration values than the permissible limits, while inorganic elements were within the safe limits for irrigation. In addition, soils irrigated with the effluents of industrial units recorded high values of inorganic and organic contaminants. Consequently, the levels of these contaminants were high in plant tissues grown thereon; especially the edible parts. Risk assessment based on available Predicted No Effect Concentration values for the aquatic and terrestrial environment was performed. Inorganic elements were expected to cause serious hazard problems for both aquatic organisms and soil microorganisms. The impact of these pollutants on human health was calculated using daily metals intake of inorganic metals via consumption of edible plants. Hazard index values proved that concentrations of Cr may cause serious hazard problems for humans in this area; especially, children.

  12. Theoretical study of CO chemisorption on nickel and copper surfaces

    Yu, H. L.

    1978-01-01

    A comparative study of the chemisorption of CO on Ni(001) and Cu(001) surfaces has been performed. The study is based on an analysis of the electronic structure of (M)5CO clusters obtained from self-consistent field X alpha scattered-wave calculations. The electron orbital formed principally by the 5 sigma orbital on CO was found to be mainly responsible for the bonding of the CO molecule to the metal surface for both the CO/Ni and CO/Cu systems. The different occupation of the antibonding 7 a sub 1 orbital in the two clusters is believed to be the major reason for the large difference observed in the measured heats of adsorption of CO on Ni and Cu surfaces. It was found also that metal atoms transfer electronic charge to the antibonding pi(asterisk)-like orbital of CO. A possible correlation between the amount of the charge transfered and the relative ease of dissociation of CO molecules on metal surfaces is discussed.

  13. Trace elements in two marine fish cultured in fish cages in Fujian province, China

    Onsanit, Sarayut; Ke Caihuan; Wang Xinhong; Wang Kejian [State Key Laboratory for Marine Environmental Science, College of Oceanography and Environmental Science, Xiamen University, Xiamen 361005 (China); Wang Wenxiong, E-mail: wwang@ust.h [State Key Laboratory for Marine Environmental Science, College of Oceanography and Environmental Science, Xiamen University, Xiamen 361005 (China)

    2010-05-15

    Two cultured marine fish, the Japanese seabass (Lateolabrax japonicus) and red seabream (Pagrus major) were collected from eight fish cage sites along the coast of Fujian province in China. The concentrations of Ag, As, Cd, Co, Cu, Fe, Mn, Se, and Zn in their muscle, stomach and liver tissue were quantified. The risk of these trace elements to humans through fish consumption was then assessed. The highest concentrations of As, Cd, Se and Zn in fish feed from fish cages were found in Dongshan Station. Moreover, the As levels in the muscles of both species at all sites were generally higher than China's national standard (>1.0 mug/g). Trace element concentrations in two marine fish followed the order of livers > stomachs > muscles. Although the As levels in two marine caged fish exceeded the permissible standards, the estimated daily intake of As did not exceed the reference dose guideline established by US EPA. For other trace elements examined in this study, their concentrations did not exceed the permissible concentrations of the international standards. - As levels in two marine caged fish from China exceeded the permissible standards, whereas the levels of others trace elements did not exceed the permissible concentrations.

  14. Generation of Cu–In alloy surfaces from CuInO2 as selective catalytic sites for CO2 electroreduction

    Jedidi, Abdesslem

    2015-08-11

    The lack of availability of efficient, selective and stable electrocatalysts is a major hindrance for scalable CO2 reduction processes. Herein, we report the generation of Cu–In alloy surfaces for electrochemical reduction of CO2 from mixed metal oxides of CuInO2 as the starting material. The material successfully generates selective active sites to form CO from CO2 electroreduction at mild overpotentials. Density functional theory (DFT) indicates that the site occupation of the inert In occurs more on the specific sites of Cu. In addition, while In atoms do not preferentially adsorb H or CO, Cu atoms, which neighbor the In atoms, alters the preference of their adsorption. This preference for site occupation and altered adsorption may account for the improved selectivity over that observed for Cu metal. This study demonstrates an example of a scalable synthesis method of bimetallic surfaces utilized with the mixed oxide precursor having the diversity of metal choice, which may drastically alter the electrocatalytic performance, as presented herein.

  15. Very accurate (definitive) methods by radiochemical NAA and their significance for quality assurance in trace analysis

    The idea of very accurate (definitive) methods by RNAA for the determination of individual trace elements in selected matrices is presented. The approach is based on combination of neutron activation with selective and truly quantitative post-irradiation isolation of an indicator radionuclide by column chromatography followed by high resolution γ-ray spectrometric measurement. The method should be, in principle, a single element method to optimize all conditions with respect to determination of this particular element. Radiochemical separation scheme should assure separation of the analyte from practically all accompanying radionuclides to provide interference-free γ-ray spectrometric measurement and achieving best detection limits. The method should have some intrinsic mechanisms incorporated into the procedure preventing any possibility of making gross errors. Several criteria were formulated which must be simultaneously fulfilled in order to acknowledge the analytical result as obtained by definitive method. Such methods are not intended for routine measurements but rather for verifying the accuracy of other methods of analysis and certification of the candidate reference materials. The usefulness of such methods is illustrated on the example of Cd and references are given to similar methods elaborated for the determination of several other elements (Co, Cu, Mo, Ni and U) in biological materials. (author)

  16. Chemical composition of selected Saudi medicinal plants

    Ihsanullah Daur

    2015-05-01

    Full Text Available Medicinal plants are important in traditional medicine and modern pharmaceutical drugs; therefore, the interest in the analysis of their chemical composition is increasing. In this study, selected medicinal plants including Achillea fragrantissima (Forssk Sch., Amaranthus viridis L., Asteriscus graveolens (Forssk. Less., Chenopodium album L., and Conyza bonariensis (L. Cronquist were collected from the rangeland of western regions (Bahra and Hada areas of Saudi Arabia to study their chemical composition. Eight minerals (Mg, Ca, Cr, Mn, Fe, Co, Cu, and Zn, total phenolic contents, antioxidant activity, and free-radical scavenging ability were examined in order to evaluate the medicinal potential of these plants. All the plants were found to be rich sources of minerals and antioxidants, although there were significant differences (p < 0.05 in their chemical composition, which may provide a rationale for generating custom extracts from specific plants depending on the application. The findings of this study will thus facilitate herbalists in their efforts to incorporate these plants into various formulations based on their chemical composition.

  17. Trace Elements in Teeth by ICPMS

    Teeth are reported to be suitable indicators of trace element exposure from environment and nutritional status. Inductively coupled plasma mass spectrometry (ICP-MS) is used to compare the trace element content of children's primary teeth and adult teeth. Primary teeth are collected from 28 children and 42 adult from non-industrial City. The data are assessed statistically using t-tests. The adult teeth contained significantly greater concentrations of Na, Mg, Al, Fe, Ni, Cu, Sr, Cd, Ba, Pb and U and significantly less Mn, Co, As, Se, Mo and Bi than the children teeth. Additional measurements on adult teeth pulps are performed. Comparison between trace element concentrations in health and caries teeth pulps show that the mean concentrations of Na, Al, K, Cr, Mn, Co, Cu, Zn, Mo, Ag, Bi and U are lower in caries than healthy teeth pulps. On the other hand, the mean concentrations of Mg, Cd and Pb are higher in caries samples than healthy teeth pulps

  18. Preparation of Photo catalytic Materials Based on Bi4Ti3O12 Doped with Transition Metals

    The production of hydrogen from water using ceramic semiconductors with photo catalytic properties has gained special relevance in the last years, due to their potential use for the generation of hydrogen in a direct and clean way. Doping with transition metals has demonstrated to be an effective method to obtain new active photo catalysts in the visible range of the solar spectrum by changing the band gap of the material. In this paper we study the effect of the addition of various dopants (Fe, Ni, Cr, Mn, Co, Cu) in the structure and band gap of Bi4Ti3O12, in order to improve its photo catalytic activity and make it visible light active. Accordingly, doped BIT based materials have been obtained by solid state processing and different amounts of an additional phase with sillenite structure, Bi12TiO20, have been detected. With the dopant a shift of the absorption spectra is produced towards higher wavelengths and consequently towards lower band gap values. The band gap values obtained for many of the prepared compositions are quite promising, promoting the study of their catalytic properties.. (Author)

  19. Preparation of Photo catalytic Materials Based on Bi{sub 4}Ti{sub 3}O{sub 1}2 Doped with Transition Metals; Preparacion de Materiales Fotocatalizadores Basados en Bi{sub 4}Ti{sub 3}O{sub 1}2 Dopados con Metales de Transicion

    Calatalyud, D. G.; Rodriguez, M.; Gallego, B.; Fernandez-Hevia, D.; Jardiel, T.

    2012-07-01

    The production of hydrogen from water using ceramic semiconductors with photo catalytic properties has gained special relevance in the last years, due to their potential use for the generation of hydrogen in a direct and clean way. Doping with transition metals has demonstrated to be an effective method to obtain new active photo catalysts in the visible range of the solar spectrum by changing the band gap of the material. In this paper we study the effect of the addition of various dopants (Fe, Ni, Cr, Mn, Co, Cu) in the structure and band gap of Bi{sub 4}Ti{sub 3}O{sub 1}2, in order to improve its photo catalytic activity and make it visible light active. Accordingly, doped BIT based materials have been obtained by solid state processing and different amounts of an additional phase with sillenite structure, Bi{sub 1}2TiO{sub 2}0, have been detected. With the dopant a shift of the absorption spectra is produced towards higher wavelengths and consequently towards lower band gap values. The band gap values obtained for many of the prepared compositions are quite promising, promoting the study of their catalytic properties.. (Author)

  20. Occurrence and distribution of selected heavy metals and boron in groundwater of the Gulf of Khambhat region, Gujarat, India.

    Upadhyaya, Devang; Survaiya, Mayur D; Basha, Shaik; Mandal, Subir K; Thorat, R B; Haldar, Soumya; Goel, Sangita; Dave, Himal; Baxi, Krushnakant; Trivedi, Rohit H; Mody, Kalpana H

    2014-03-01

    The concentration of selected heavy metals, like As, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn as well as B, was measured by inductively coupled plasma-optical emission spectrometry (ICP-OES) in groundwater samples from various locations in the Gulf of Khambhat (GoK), an inlet of the Arabian Sea in the state of Gujarat, India, during post-monsoon, winter, and pre-monsoon seasons in a year. Most heavy elements are characterized by low mobility under slightly alkaline and reducing conditions; concentrations in confined aquifers are smaller than the maximum permissible values for drinking water. The temporal changes indicate that a majority of metals is entering the aquifer during monsoon. Principle component analysis of the heavy metal data suggests that Co, Cu, Cd, and Zn are interrelated with each other and derived significantly from anthropogenic route, while input of Pb and Cr may be due to atmospheric deposition in the study area. Both weathering of rocks and anthropogenic input were found to be main sources of elements in the groundwater. The heavy metal levels in groundwaters of the GoK region in comparison with some of the European and Asian sites were higher; however, these metal levels were found to be comparable with few urban sites in the world. PMID:24293301

  1. Laboratory Performance Evaluation in Terms of Water Analysis Through an External Quality Control

    This paper presents the results of participation of Institut National des Sciences et Techniques Nucleaires-Madagascar (INSTN-Madagascar) in interlaboratory comparisons organized annually, since 2007, by Southern African Development Community WaterLab Association. The following text describes an overview of the utility of provided proficiency testing programs used as an external quality control with respect to proving consistency and reliability of water analysis at INSTN-Madagascar. Total reflection X-Ray Fluorescence spectrometry and Atomic Absorption Spectrometry are both used to measure the following trace metals: Al, Cr, Mn, Fe, Ni, Co, Cu, Zn, As, Cd, Pb. The analysis of minor and major ions such as Cl-, F-, NO3-, SO42-, PO43-,K+, Na+, Ca2+, Mg2+ are conducted by using Ion Chromatography. To illustrate, graphical distributions of z-scores calculated from the results of water measurements are presented. During the consecutive proficiency testing rounds, INSTN-Madagascar has succeeded to have more than 80% of the values within tolerance limits on 2007, 2008, 2010, 2011, 2012 and 2013. This paper shows some of the considerations for participating to proficiency testing exercises which could be used to obtain certain value from the schemes.

  2. Trace element content of medicinal plants from Algeria

    Neutron activation analysis (INAA) has been applied to multielemental determination of eleven medicinal plants used to cure the urinary tract diseases observed in Algeria. These plants include Androgena Citratus, Ceratonia Siliquata, Punica Granatum, Glyryrrhiza Glabra, Lausaunia Alba, Fragaria Vesca, Arbutus Unedol, Hordeum Vulgaris, Papieteria Officinalis, Zea Mays L, and Davallia Seae. Concentrations of twenty elements Ba, Br, Ca, Cl, Co, Cu, Cr, Fe, I, Mn, Na, Mg, Rb, Sb, Se, Sc, Sr, Ti, V, and Zn have been determined by short, and long irradiation times with a thermal and epithermal flux of 1.4 x 1012 n x cm-2 x s-1 and 1.4 x 1011 n x cm-2 x s-1, respectively. These analyses were performed in conjunction with Compton suppression. In almost herbs studied the Co, Cr, Cu, Rb, Sb , Sc, Se and V are found to be present at trace levels, Br, Mn, and Zn at the minor level, and Ca, Cl, Fe, Mg and Na are generally at the major level. The accuracy of the measurements has been evaluated by analyzing NISTbotanical references materials. (author)

  3. Metals in sediments of San Andres lagoon, Tamaulipas, Mexico

    Vazquez, F.G.; Aguilera, L.G. (Instituto de Ciencias del Mar y Limnologia, Universitaria (Mexico)); Sharma, V.K. (Texas A M Univ., Corpus Christi, TX (United States))

    1994-03-01

    Heavy metal pollution in water is generally associated with industrial and municipal discharges into rivers, estuaries and lagoons. Once metals are in the water column, they may be taken up by organisms, deposited in the sediments or remain for some period in the water itself. The deposition rate in sediments depends on, among other factors, metal concentration in surface sediments. The concentrations of heavy metals in sediments of coastal, estuarine and lagoon environments have been determined by many workers. For the past several years, we have been interested in determining trace and heavy metal concentrations in the lagoons in Mexico to establish the levels of metal pollution. The work reported here is the completion of our ongoing study in San Andres lagoon. San Andres lagoon is located north of two industrial ports, Tampico and Altamira. In this industrial zone, the basins of the Panuco and Tamesi Rivers are localized and have industrial effluent throughout the year. All these activities and the input of the Tigre River, which runs through an agricultural and cattle-raising region, may affect the biogeochemistry of the San Andres lagoon. In the present work, we report concentrations of Cd, Co, Cu, Fe, Mn, Ni, Zn and Pb in sediments of San Andres lagoon. The measurements were made in different seasons; Rain-84 (August-September 1984); North (October-December 1984); Dry (April 1985); and Rain-85 (April-June 1985). 13 refs., 1 fig., 2 tabs.

  4. Evaluation of diffusive gradients in thin film (DGT) samplers for measuring contaminants in the Antarctic marine environment.

    Larner, Bronwyn L; Seen, Andrew J; Snape, Ian

    2006-10-01

    This work has been the first application of DGT samplers for measuring metals in water and sediment porewater in the Antarctic environment, and whilst DGT water sampling was restricted to quantification of Cd, Fe and Ni, preconcentration using Empore chelating disks provided results for an additional nine elements (Sn, Pb, Al, Cr, Mn, Co, Cu, Zn, As). Although higher concentrations were measured for some metals (Cd, Ni, Pb) using the Empore technique, most likely due to particulate-bound or colloidal species becoming entrapped in the Empore chelating disks, heavy metal concentrations in the impacted Brown Bay were found to be comparable with the non-impacted O'Brien Bay. Sediment porewater sampling using DGT also indicated little difference between Brown Bay and O'Brien Bay for many metals (Cd, Al, Cr, Co, Ni, Cu), however, greater amounts of Pb, Mn, Fe and As were accumulated in DGT probes deployed in Brown Bay compared with O'Brien Bay, and a higher accumulation of Sn was observed in Brown Bay inner than any of the other three sites sampled. Comparison of DGT derived porewater concentrations with actual porewater concentrations showed limited resupply of Cd, Pb, Al, Cr, Mn, Co, Ni, Cu, Zn and As from the solid phase to porewater, with these metals appearing to be strongly bound to the sediment, however, resupply of Fe and Sn was apparent. Based upon our observations here, we suggest that Sn, and to a lesser extent Pb, are critical contaminants. PMID:16709425

  5. Detailed uranium hydrogeochemical and stream sediment reconnaissance data release for the eastern portion of the Montrose NTMS Quadrangle, Colorado, including concentrations of forty-five additional elements

    In September and October 1979, the Los Alamos Scientific Laboratory (LASL) conducted a detailed geochemical survey for uranium primarily in the Sawatch Range in the eastern part of the Montrose National Topographic Map Series (NTMS) quadrangle, Colorado, as part of the National Hydrogeochemical and Stream Sediment Reconnaissance (HSSR). Totals of 1034 water and 2087 sediment samples were collected from streams and springs from 2088 locations within a 5420-km2 area. Statistical data for uranium concentrations in water and sediment samples are presented. Elemental concentration, field measurement, weather, geologic, and geographic data for each sample location are listed for waters and for sediments in appendices. Uranium/thorium ratios for sediment samples are also included. This report contains uranium analyses for water samples and multielement analyses for sediment samples. Sediments were analyzed for uranium and thorium as well as Al, Sb, As, Ba, Be, Bi, Cd, Ca, Ce, Cs, Cl, Cr, Co, Cu, Dy, Eu, Au, Hf, Fe, La, Pb, Li, Lu, Mg, Mn, Ni, Nb, K, Rb, Sm, Sc, Se, Ag, Na, Sr, Ta, Tb, Sn, Ti, W, V, Yb, Zn, and Zr. All elemental analyses were performed at the LASL. Water samples were analyzed for uranium by fluorometry. Sediments were analyzed for uranium by delayed neutron counting. Other elemental concentrations in sediments were determined by neutron activation analysis for 31 elements, by x-ray fluorescence for 12 elements, and by arc-source emission spectrography for 2 elements. Descriptions of procedures as analytical precisions and detection limits are given in the appendix

  6. Irradiation Effect of Argon Ion on Interfacial Structure Fe(2nm/Si(tsi=0.5-2 nm Multilayer thin Film

    S. Purwanto

    2010-04-01

    Full Text Available Investigation includes formation of interfacial structure of Fe(2nm/Si(tSi= 0.5-2 nm multilayer thin film and the behavior of antiferromagnetic coupling between Fe layers due to Argon ion irradiation was investigated. [Fe(2nm/Si]30 multilayers (MLs with a thickness of Si spacer 0.5 - 2 nanometer were prepared on n-type (100 Si substrate by the helicon plasma sputtering method. Irradiation were performed using 400keV Ar ion to investigate the behavior of magnetic properties of the Fe/Si MLs. The magnetization measurements of Fe/Si MLs after 400keV Ar ion irradiation show the degradation of antiferromagnetic behavior of Fe layers depend on the ion doses. The Magnetoresistance (MR measurements using by Four Point Probe (FPP method also confirm that MR ratio decrease after ion irradiation. X-ray diffraction (XRD patterns indicate that the intensity of a satellite peak induced by a superlattice structure does not change within the range of ion dose. These results imply that the surface of interface structures after ion irradiation become rough although the layer structures are maintained. Therefore, it is considered that the MR properties of Fe/Si MLs also are due to the metallic superlattice structures such as Fe/Cr and Co/Cu MLs.

  7. Chemical characterization of biomass burning deposits from cooking stoves in Bangladesh

    Biomass burning smoke deposits were characterized from cooking stoves in Brahmondi, Narsingdi, Bangladesh. Arjun, bamboo, coconut, madhabilata, mahogany, mango, rice husk coil, plum and mixed dried leaves were used as biomasses. Smoke deposits were collected from the ceiling (above the stove) of the kitchen on aluminum foil. Deposits samples were analyzed with X-ray fluorescence (XRF) spectroscopy for trace elements determination. UV–visible spectrophotometer was used for ions analysis. The surface morphology of the smoke deposits was studied with scanning electron microscope (SEM). Elevated concentrations of the trace elements were observed, especially for toxic metals (Pb, Co, Cu). The highest concentration of lead was observed in rice husk coil among the determined biomasses followed by mahogany and arjun, whereas the lowest concentration was observed in bamboo. Potassium has the highest concentration among the determined trace elements followed by calcium, iron and titanium. Trace elements such as potassium, calcium, iron showed significant variation among different biomass burning smoke deposits. The average concentrations of sulfate, nitrate, and phosphate were 38.0, 0.60, 0.73 mg kg−1, respectively. The surface morphology was almost similar for these biomass burning deposit samples. The Southeast Asian biomass burning smoke deposits had distinct behavior from European and USA wood fuels combustion. -- Highlights: •Elevated concentrations of trace elements were observed in biomass burning deposits. •Very high concentration of lead was observed in biomasses burring deposits •Elevated toxic trace elements concentrations in kitchens need further surveillance

  8. The Influence of Heavy Metals on Growth and Development of Eichhornia crassipes Species, Cultivated in Contaminated Water

    Erzsebet BUTA

    2011-11-01

    Full Text Available Many plants are capable of accumulating heavy metals (called hyperacumulators, one of which is the water hyacinth Eichhornia crassipes Mart. The roots of this water plant naturally absorb pollutants, including heavy metals such as Pb, Hg, Zn, Co, Cd, and Cu and can be used for wastewater treatment. The aim of this study was to assess the influence of heavy metals on growth and development of water hyacinth and to determinate the uptake capacity of heavy metals of this species. It was evaluated for its effectiveness in reducing pollution potential in wastewater. From the combination of experimental factors 11 variants resulted. The results showed that Eichhornia absorbed a high quantity of Pb (504 mg/kg dry matter and Cu (561 mg/kg dry matter in their roots. More Cu accumulated in the root compared to Pb. The level of Zn absorption was lower in roots (84 mg/kg dry matter and also in stem plus leaves (51 mg/kg dry matter. A high quantity of Cd (281 mg/kg dry matter was removed from stem plus leaves of Eichhornia while the level of Co was very low (45 mg/kg dry matter. Regarding the growth and development of this plant it was found that in tanks with Pb plants had a better development and had flowers also, and in the case of Cd, Co, Cu at a double dose of maximum admissible limits, the plants died and the growing period was shorter.

  9. Phase stability and site preference of Sm(Fe,T)12

    The structure of intermetallics Sm(Fe,T)12 is analyzed via a quasi-ab initio pair potentials PHIFe-Fe(r), PHISm-Fe(r), PHISm-Sm(r), PHISm-T(r), PHIFe-T(r) and PHIT-T(r). The calculation results show that each of Cr, V, Mo and Ti significantly decreases the cohesive energy of Sm(Fe,T)12, and thus stabilizes its structure of ThMn12. The calculated lattice constants coincide quite well with experimental values. The sequence of site preference occupation is 8i, 8j and 8f, with the 8i occupation corresponding to the greatest energy decrease. The calculated results also show that each of Co, Cu, Ni and Sc does not stabilize the system with the structure of ThMn12. The calculated crystal structure can recover after either an overall wide-range macro-deformation or atomic random motion, demonstrating that an Sm-Fe-T system has the stable structure of ThMn12. The crystal space group remaining consistent at different temperatures is also shown in this paper. All of the results verify that the first principle potentials based on the lattice inversion technique are effective

  10. STUDIES ON THE CATALYTIC REACTION OF NITROGEN OXIDE ON METAL MODIFIED ACTIVATED CARBON FIBERS

    FU Ruowen; DU Xiuying; LIN Yuansheng; XU Hao; HU Yiongjun

    2003-01-01

    The catalytic reaction of NO with CO and decomposition of NO over metal modified ACFs were investigated and compared with other carriers supported catalysts. It is demonstrated that Pd/ACF and Pd/Cu/ACF have high catalytic activity for the reaction of NO/CO, while Pt/ACF.Pt/Cu/ACF and Co/Cu/ACF have very Iow catalytic activity in similar circumstance. Pd-modified ACF possesses high catalytic decomposition of NO at 300 ℃. Pd/CB and Pd/GAC present good catalytic decomposition ability for NO only at low flowrate. Pd/G, Pd/ZMS and Pd/A however, do not show any catalytic activity for NO decomposition even at 400 ℃. Catalytic temperature, NO flowrate and loading of metal components affect the decomposition rate of NO. The coexistence of Cu with Pd on Cu/Pd/ACF leads to crystalline of palladium to more unperfected so as to that increase the catalytic activity.

  11. Acid mine drainage treatment using by-products from quicklime manufacturing as neutralization chemicals.

    Tolonen, Emma-Tuulia; Sarpola, Arja; Hu, Tao; Rämö, Jaakko; Lassi, Ulla

    2014-12-01

    The aim of this research was to investigate whether by-products from quicklime manufacturing could be used instead of commercial quicklime (CaO) or hydrated lime (Ca(OH)2), which are traditionally used as neutralization chemicals in acid mine drainage treatment. Four by-products were studied and the results were compared with quicklime and hydrated lime. The studied by-products were partly burnt lime stored outdoors, partly burnt lime stored in a silo, kiln dust and a mixture of partly burnt lime stored outdoors and dolomite. Present application options for these by-products are limited and they are largely considered waste. Chemical precipitation experiments were performed with the jar test. All the studied by-products removed over 99% of Al, As, Cd, Co, Cu, Fe, Mn, Ni, Zn and approximately 60% of sulphate from acid mine drainage. However, the neutralization capacity of the by-products and thus the amount of by-product needed as well as the amount of sludge produced varied. The results indicated that two out of the four studied by-products could be used as an alternative to quicklime or hydrated lime for acid mine drainage treatment. PMID:25193795

  12. Leaching of metals from copper smelter flue dust (Mufulira, Zambian Copperbelt)

    Vítková, Martina; Ettler, Vojtěch; Hyks, Jiri;

    2011-01-01

    The leaching behaviour of electrostatic precipitator dust from the Mufulira Cu smelter (Copperbelt, Zambia) was studied using a 48-h pH-static leaching experiment (CEN/TS 14997). The release of metals (Cd, Co, Cu, Ni, Pb and Zn) and changes in mineralogical composition using X-ray diffraction and...... PHREEQC-2 modelling were investigated in the pH range of 3–7. The highest concentrations of metals were released at pH 3–4.5, which encompasses the natural pH of the dust suspension (∼4.3). About 40% of the total Cu was leached at pH3, yielding 107g/kg. Chalcanthite (CuSO4·5H2O), magnetite (Fe3O4) and...... delafossite (CuFeO2) represented the principal phases of the studied dust. In contact with water, chalcanthite was dissolved and hydrated Cu sulphates precipitated at pH4–7. Gypsum (CaSO4·2H2O) and secondary Fe or Al phases were observed in the leached residues. Serious environmental impact due to leaching...

  13. Cyclic M2(RL)2 coordination complexes of 5-(3-[N-tert-Butyl-N-aminoxyl]phenyl)pyrimidine with paramagnetic transition metal dications.

    Baskett, Martha; Lahti, Paul M; Paduan-Filho, Armando; Oliveira, Nei F

    2005-09-19

    5-(3-(N-tert-Butyl-N-aminoxyl)phenyl)pyrimidine (RL = 3NITPhPyrim) forms isostructural cyclic M2(RL)2 cyclic dimers with M(hfac)2 (M = Mn, Co, Cu; hfac = hexafluoroacetylacetonate). Mn2(hfac)4(RL)2 exhibits strong antiferromagnetic Mn-RL exchange, with weak ferromagnetic exchange (0.7 cm(-1)) between Mn-RL units that is consistent with a spin polarization exchange mechanism. The magnetic moment of Co2(hfac)4(RL)2 at higher temperatures is consistent with strongly antiferromagnetic exchange within the Co-NIT units and tends toward zero below 50 K at lower magnetic fields. Cu2(hfac)4(RL)2 shows more complex behavior, with no high-temperature plateau in chiT(T) up to 300 K but a monotonic decrease down to about 100 K. The Cu(II)-nitroxide bonds decrease by 0.2-0.3 A over the same temperature range, corresponding to a change of nitroxide coordination from axial to equatorial. This thermally reversible Jahn-Teller distortion leads to a thermally induced spin state conversion from a high-spin, paramagnetic state at higher temperature to a low-spin state at lower temperature. This spin state conversion is accompanied by a reversible solid-state thermochromic change between dull yellow-brown at room temperature and green at 77 K. PMID:16156631

  14. Preparation and certification of Sargasso seaweed reference material

    Sargasso seaweed reference material was prepared from Sargassum felvellum obtained from an unpolluted area in Japan. The sargasso samples were washed, freeze-dried, pulverized, sieved to pass a 80-mesh screen and finally homogenized. Collaborative studies on the elemental analysis of the sargasso reference material were performed using various analytical techniques. Certified values are provided for Ag, As, Ca, Cd, Co, Cu, Fe, K, Mg, Mn, Na, Pb, Rb, Sr, V and Zn, based on results of determinations by at least three independent analytical techniques. Reference values are reported for Al, Br, Cl, Cr, Cs, Hg, I, P, S, Sb, Sc, Se, Ti and U. The sargasso certified reference material contains high levels of alkali metals, alkaline earth metals, I, Br, As and U, while the concentration of trace elements may be considered to be at the lower end of the range of reported values for marine brown algae. The sargasso sample will be of practical use in marine and environmental sciences as a certified reference material having an elemental composition close to background levels. (author)

  15. Preparation and certification of Sargasso seaweed reference material

    Okamoto, Kensaku

    1988-01-01

    Sargasso seaweed reference material was prepared from Sargassum felvellum obtained from an unpolluted area in Japan. The sargasso samples were washed, freeze-dried, pulverized, sieved to pass a 80-mesh screen and finally homogenized. Collaborative studies on the elemental analysis of the sargasso reference material were performed using various analytical techniques. Certified values are provided for Ag, As, Ca, Cd, Co, Cu, Fe, K, Mg, Mn, Na, Pb, Rb, Sr, V and Zn, based on results of determinations by at least three independent analytical techniques. Reference values are reported for Al, Br, Cl, Cr, Cs, Hg, I, P, S, Sb, Sc, Se, Ti and U. The sargasso certified reference material contains high levels of alkali metals, alkaline earth metals, I, Br, As and U, while the concentration of trace elements may be considered to be at the lower end of the range of reported values for marine brown algae. The sargasso sample will be of practical use in marine and environmental sciences as a certified reference material having an elemental composition close to background levels.

  16. Minor and trace element concentrations in adjacent kamacite and taenite in the Krymka chondrite

    Meftah, N.; Mostefaoui, S.; Jambon, A.; Guedda, E. H.; Pont, S.

    2016-04-01

    We report in situ NanoSIMS siderophile minor and trace element abundances in individual Fe-Ni metal grains in the unequilibrated chondrite Krymka (LL3.2). Associated kamacite and taenite of 10 metal grains in four chondrules and one matrix metal were analyzed for elemental concentrations of Fe, Ni, Co, Cu, Rh, Ir, and Pt. The results show large elemental variations among the metal grains. However, complementary and correlative variations exist between adjacent kamacite-taenite. This is consistent with the unequilibrated character of the chondrite and corroborates an attainment of chemical equilibrium between the metal phases. The calculated equilibrium temperature is 446 ± 9 °C. This is concordant with the range given by Kimura et al. (2008) for the Krymka postaccretion thermal metamorphism. Based on Ni diffusivity in taenite, a slow cooling rate is estimated of the Krymka parent body that does not exceed ~1K Myr-1, which is consistent with cooling rates inferred by other workers for unequilibrated ordinary chondrites. Elemental ionic radii might have played a role in controlling elemental partitioning between kamacite and taenite. The bulk compositions of the Krymka metal grains have nonsolar (mostly subsolar) element/Ni ratios suggesting the Fe-Ni grains could have formed from distinct precursors of nonsolar compositions or had their compositions modified subsequent to chondrule formation events.

  17. Semi-quantitative spectrographic determination of traces of elements in igneous rocks

    A semi-quantitative spectrographic technique based on Harveys'method, using background radiation as internal standard is described for the analysis of trace elements in igneous rocks by the total energy method. A certain amount of the sample was completely vapourized in a DC arc with anodic excitation under argon and oxygen atmosphere, using graphite electrodes of standard dimensions. In the processed film, selected lines and adjancent backgrounds were evaluated by densitometry and the corresponding intensity ratios were calculated. Sensitivity factors were determined for the analytical lines of Co, Cu, Ga, Ni, Sc, Sr, V, Y, Zn, and Zr in geological standards (G-2, BCR-1, AGV-1, GSP-1) from the United States Geological Survey. Matrix effects between samples and standards were minimized by using the above mentioned geological standards. An average value of the sensitivity factors was employed for the calculation of the concentration of the elements in the samples. A comparison between the results obtained by this method and those from the analysis of zinc by atomic absorption is presented. This method enabled the analyses of igneous rock samples having SiO2 contents between 40 and 80%, with an error in the determinations of trace elements less than 30%.(Author)

  18. Forensic identification of trunk mat by trace element analysis of single fiber with laser ablation ICP-MS

    The application of LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometry) to the chemical characterization of single trunk mat fibers made of PET was investigated in order to establish a forensic analytical method for the discrimination of samples of different origins. The analytical conditions of LA-ICP-MS equipped with a 213 nm Nd : YAG laser were optimized to analyze trace elements, such as Cu, Sb, and Ba at ppm levels. A total of 31 samples produced by 7 car manufactures in Japan were used for analysis. The concentrations of Li, Mg, Al, P, Ca, Ti, Co, Cu, Ge, Nb, Sb, Ta, and Pb were successfully measured from a single fiber sample with a diameter of ca. 20 μm. It was possible to discriminate all 31 samples based on the analytical results of a single fiber by LA-ICP-MS combined with those of FT-IR and SEM-EDS. LA-ICP-MS has good analytical sensitivity, and requires a much shorter preparation time and a smaller sample size than any other conventional element analysis methods. This paper demonstrates for the first time that this method is practically useful as a powerful tool for the forensic identification of a single trunk mat fiber. (author)

  19. Particulate Trace Element Cycling in a Diatom Bloom at Station ALOHA

    Weisend, R.; Morton, P. L.; Landing, W. M.; Fitzsimmons, J. N.; Hayes, C. T.; Boyle, E. A.

    2014-12-01

    Phytoplankton in oligotrophic marine deserts depend on remote sources to supply trace nutrients. To examine these sources, marine particulate matter samples from the central North Pacific (Station ALOHA) were collected during the July-August 2012 HOE-DYLAN cruises and analyzed for a suite of trace (e.g., Fe, Mn) and major (e.g. Al, P) elements. Daily surface SPM samples were examined for evidence of atmospheric deposition and biological uptake, while five vertical profiles were examined for evidence of surface vertical export and subsurface horizontal transport from nearby sources (e.g., margin sediments, hydrothermal plumes). Maxima in surface particulate P (a biological tracer) corresponded with a diatom bloom, and surprisingly also coincided with maxima in particulate Al (typically a tracer for lithogenic inputs). The surface particulate Al distributions likely result from the adsorption of dissolved Al onto diatom silica frustules, not from atmospheric dust deposition. In addition, a subsurface maximum in particulate Al and P was observed four days later at 75m, possibly resulting from vertical export of the surface diatom bloom. The distributions of other bioactive trace elements (e.g. Cd, Co, Cu) will be presented in the context of the diatom bloom and other biological, chemical and physical features. A second, complementary poster is also being presented which examines the cycling of trace elements in lithogenic particles (Morton et al., "Trace Element Cycling in Lithogenic Particles at Station ALOHA").

  20. Sedimentary input of trace metals from the Chukchi Shelf

    Aguilar-Islas, A. M.; Seguré, M.; Rember, R.; Nishino, S.

    2014-12-01

    The distribution of trace metals in the Arctic Ocean has implications for their global cycles, yet until recently few trace metal observations were available from this rapidly changing ocean. Profiles of dissolved Fe from recent Japanese field efforts in the Western Canada Basin (2008, 2010) indicate the broad Chukchi Shelf as a source of Fe to the halocline of the Western Canada Basin. Here we present dissolved and particulate data for crustal (Al, Mn, Fe) and non-crustal elements (Co, Cu, Zn) from the productive Chukchi Sea to characterize the sedimentary input of these metals to shelf waters contributing to the halocline layer of the Canada Basin. Water column profiles were collected in late summer 2013 onboard the R/V Mirai at 10 stations from the Bering Strait to the slope, and at a time-series (10 days) station located over the outer shelf. A narrow and variable (5-10 m) benthic boundary layer was sampled at the time-series station with highly elevated dissolved and suspended particulate metal concentrations. High metal concentrations were also observed in the subsurface at a station over Barrow Canyon where mixing is enhanced. Reactivity of suspended particulate metals was determined by the leachable vs. refractory fractions. Metal concentrations were determined by ICP-MS. Trace metal transport from the shelf to the interior will be discussed in context with shelf mechanisms contributing to this export, and to expected future changes in the Arctic Ocean.

  1. Trace element structure of the most widespread plants of genus PulmonariaFNx01

    Dmitriy Kruglov

    2012-01-01

    Full Text Available Aim: The aim of this work was a comparative research of trace element structure of various organs of three Pulmonaria species. Materials and Methods: The aerial parts of the most widespread plants of genus Pulmonaria such as Pulmonaria officinalis L., Pulmonaria obscura Dumort. and Pulmonaria mollis Wulf. ex Hornem., which were collected in ending of flowering and were used as the research objects. The amount of trace elements (B, K, P, V, Ca, Co, Cu, Fe, Mg, Mn, Mo, Na, Si, Zn, Ag, Al, Ba, Br, Cr, I, Ni, Se, Sr, and Ti was determined by means of mass spectroscopy with inductively coupled plasma. Results: The data clustering has shown that floral shoots and rosellate leaves possess essentially various trace element status. At the same time, the trace elements′ status of organs of researched plants poorly depends on a taxonomic position of the plant. Thereupon, it is obvious that pharmacological activity is defined by organs of plants from which medicines were made, but not by a species of the used plant. Conclusions: The significant distinction in pharmacological activity of preparations depends on the trace elements′ status of used medicinal vegetative raw materials.

  2. Heavy metal accumulation in lake sediments, fish (Oreochromis niloticus and Serranochromis thumbergi), and crayfish (Cherax quadricarinatus) in Lake Itezhi-tezhi and Lake Kariba, Zambia.

    Nakayama, Shouta M M; Ikenaka, Yoshinori; Muzandu, Kaampwe; Choongo, Kennedy; Oroszlany, Balazs; Teraoka, Hiroki; Mizuno, Naoharu; Ishizuka, Mayumi

    2010-08-01

    We measured the level of heavy metal accumulation in lake sediments, herbivorous (Oreochromis niloticus) and carnivorous (Serranochromis thumbergi) fish, and crayfish (Cherax quadricarinatus) from Lake Itezhi-tezhi (ITT) and Lake Kariba. We used atomic absorption spectrophotometry to quantify the levels of seven heavy metals (Cr, Co, Cu, Zn, Cd, Pb, and Ni). The sediment and the herbivorous fish O. niloticus accumulated a very high concentration of Cu in Lake ITT, most likely due to the discharge of Cu waste from a mining area 450 km upstream. The aquatic species we sampled in Lake Kariba had higher concentrations of Cr, Ni, and Pb relative to those in Lake ITT. This is most likely due to anthropogenic activities, such as the use of leaded petrol and antifouling agents in marine paints. Interestingly, we observed a negative correlation between the coefficient of condition (K) and Ni concentration in the crayfish hepatopancreas. Both O. niloticus and the crayfish had much higher biota-sediment accumulation factors (BSAF) for Cu, Zn, and Cd relative to Cr, Co, Pb, and Ni. The rank of BSAF values for O. niloticus (Cu>Cd>Zn) and C. quadricarinatus (Zn>Cd>Cu) differed from the expected ranks based on the general order of affinity of metals (Cd>Zn>Cu). PMID:20162262

  3. Catalysis of methanol deep oxidation by metallocomplex compounds of nitrogen containing coal

    Metallocomplex compounds of nitrogen-containing coal (MCCNC) were synthesized where M is Cu, Cr and Co-Cu. These compounds with different content of metals (1.5 - 6 weight %) were tested as catalysts in the process of methanol deep oxidation. For comparison the experiments were carried out also in the presence of Cu O. The research was carried out with the mixture of 1.5 vol.% CH3OH in the au in the temperature interval of 150-400 degree at atmospheric pressure. It has been established that MCCNC with 3% Cu is active (80% conversion), selective (100 vol.%) and steady catalyst in the process of deep oxidation of CH5OH in CO2 and H2O. The catalyst Cu O possesses high catalytic activity (93% conversion), selectivity (100% on CO2) and stable performance under the conditions of alternating treatment (during 5 min) with the H2O2-air mixture (-0.1 vol.% H2O2) after every hour exposition in methanol-air mixture. It is supposed that the active forms of oxygen including peroxide groups detected on the surface of MCCNC play the role of 'self-purifiers' preventing the formation of sealing products blocking the active surface of catalysts

  4. INTERRELATION OF VARIOUS FORMS OF COMPOUNDS HEAVY METALS IN AN ARABLE LAYER OF EARTH AND THEIR ACCUMULATION IN GRAIN OF WINTER CROPS

    Gaydukova N. G.

    2015-09-01

    Full Text Available In the article we consider the influence of agricultural technologies of cultivation of winter crops on existence of various forms of heavy metals in an arable layer of earth in the conditions and their accumulation in grain production. The gross content of compounds of copper in an arable layer of black leached soil is above background values (maximum concentration limit 1,5-1,7, a share of the fixed connections makes 75 %. The gross content of zinc exceeds background value for chernozems (1,25 clark. The correlation of the water mode of the soil and the content of mobile compounds of heavy metals in an arable layer - a straight line for Cu and the return for Mn , Pb, Cd and Co. Supplement of an arable layer of earth with mobile forms of copper, zinc and cobalt low, manganese - corresponds to the average level. Speaking of the degree of actual mobility the studied elements settle down in sequence: Cd> Mn> Co> Pb> Zn> Cu. Degree of potential availability decreases among: Zn> Mn>Pb> Co> Cu. The existence of Mn, Cu, Zn and Co in grain of wheat is lower than maximum concentration limit, and accumulation of Pb and Cd is higher than maximum concentration limit in grain production for baby food for 10-15 %, that increases individual risk of death to the maximum permissible level

  5. Investigation of the elemental contents of some environmental samples from the Blue Nile and White Nile around Khartoum area

    This work was performed to evaluate the environmental pollution at the Blue Nile (BN) and White Nile (WN) around Khartoum state. Samples of soil, sediments, plants, fish and water were collected from the studied area and analyzed. The concentrations of some elements (K, Ca, Ti, Fe, Cr, Co, Cu, Ni, Sr, Rb, Na, P, Zn, Br, Y, Zr, and Pb) were determined using the following analytical methods; atomic absorption spectroscopy (AAS), x-ray fluorescence (XRF), flame photometry, colorimetry and ultra violet spectrometry (UV). The data obtained was compared with the data from literature. The data was statistically analyzed to compare the results obtained by the different methods. The results of most elements determined by more than one method were significantly similar. The statistical analysis together with the chemical analysis revealed that the soil and sediments of the BN and WN are significantly different. The extent of pollution was determined by calculating the enrichment factors. The enrichment factors in sediments were calculated using both Fe and Ti as reference elements where values were almost equal. Some elements were slightly enriched at some sites but not to a degree to indicate a serious pollution. The accumulation of elements in plants as a clue for pollution was also calculated. Some elements; P, Cu and Zn were accumulated. The elemental concentrations in fish and water were not that high but water was still higher than the WHO recommended concentrations. (Author)

  6. A twelve month study of PM2.5 and PM10 fine particle aerosol composition in the Sydney region using ion beam analysis techniques. Appendix 2

    The accelerator based ion beam (IBA) analysis techniques of PIXE, PIGME, PESA, and RBS have been used to characterise fine particles at selected sites in the Sydney region. The four techniques operating simultaneously provide elemental concentrations on 24 chemical species, including H, Q N, 0, F, Na, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Cu, Ni, Zn, Br and Pb. The total mass and the elemental carbon by laser integrated plate techniques were also measured. A stacked filter system, built by the University of Gent, Belgium and supplied by the IAEA was used to provide fine particle data on PM2.5 and PM10 particles. While a cyclone sampler, built at ANSTO, Lucas Heights, was used to provide data on PM2.5 particles only. The two different types of units were operated along side each other for the whole of 1994 and the results compared. The use of the multi-elemental IBA techniques also allowed for some fine particle source fingerprinting to be performed. (author)

  7. Uranium-radiu relation concerning there migration from ore and waste dumps

    Popescu, M.; Georgescu, D.P.; Sporea, A.; Petrescu, S.; Popescu, C.; Georgescu, A. [Research and Design Inst. for Rare and Radioactive Metals, Bucharest (Romania)

    1998-12-31

    The study refers to uranium-radium migration from the dumps affected by alteration as well as recycling process due to the geochemical barriers in different dispersive media. The problem of correct understanding and interpretation of the contamination due to the mining activities (ore and waste dumps) is a difficult one. It has to be correlated with elements migration from the mineralization determining radioactive aureole in water, soil and vegetation (which are, in fact the means to locate some deposits). Migration and pollution phenomena in different dispersive media have been studied for uranium, radium and other accompanying elements from several deposits. Data obtained from the geochemical studies of the mineralization show a large variety of accompanying elements: Mo, Pb, Bi, Co, Cu, Ag, Tl, As and Li. In order to study the pollution processes, rock, soil, sediments, water and plants samples have been drown and analyzed for uranium, radium, and other twenty elements, determination using fluorimetry atomic absorption spectrometry and emission spectrography. Environmental pollution may be influenced by:mine waters draining in the hydrographic ne and hypergenetic levigation processes of uranium and radium from rocks and ores on the dumps and their transport into the rivers and sediments. (orig.)

  8. Unified picture of spin-dependent transport in GMR multilayered structures and bulk ferromagnetic alloys

    Schroeder, P. A.; Holody, P.; Loloee, R.; Vouille, C.; Barthelemy, A.; Fert, A.; Hsu, S. Y.

    1998-01-01

    We have observed a positive (inverse) CPP-MR in magnetic multilayers of the forms: (a) ( XY/Cu/Co/Cu) n with XY being the alloys FeCr, FeV, NiCr, CoCr, and (b) (Z/Cr/NiFe/Cr) n with Z = Fe and Co. For (a) the inverted results arise primarily from spin-dependent scattering in the bulk of the alloy, and are linked consistently to: (1) their magnetization; (2) band-structure calculations and (3) resistivity of bulk alloys. For (b) samples, the inverse MRs arise primarily from the scattering at the Fe/Cr and Co/Cr interfaces. Inverse MR for X/Y interfaces and XY alloys (eg. Fe/Cr and FeCr) arises from the similarity of the matching problem of X and Y d levels at interfaces and in alloys. For all XY the CIP-MR was negative, confirming that CIP-MR is strongly influenced by channeling effect and current inhomogenieties.

  9. One-step synthesis of carbon nanotubes-copper composites for fabricating catalyst supports of methanol electrooxidation

    Zhang Shaoyan; Fan Guoli; Zhang Chunfang [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, P.O. Box 98, Beijing 100029 (China); Li Feng, E-mail: lifeng_70@163.com [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, P.O. Box 98, Beijing 100029 (China)

    2012-07-16

    One-step synthesis of carbon nanotubes-copper composites was established by catalytic chemical vapor deposition (CCVD) of acetylene over Co-Cu-Al mixed metal oxides derived from layered double hydroxides (LDHs). Power X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Raman spectra, thermogravimetric and differential thermal analysis (TG-DTA) and N{sub 2} adsorption-desorption measurements revealed that multi-walled carbon nanotubes were synthesized during cobalt-catalyzed CCVD, and copper nanoparticles were simultaneously in situ formed in CNTs matrix. Electrodes modified with platinum particles supported on as-fabricated CNTs-Cu composites showed much higher electrocatalytic activity for the oxidation of methanol than that modified with Pt particles supported on the commercial CNTs. The present study greatly enlarges the practical application of hybrid CNTs-based nanocomposites. - Highlights: Black-Right-Pointing-Pointer Carbon nanotubes-copper composites were prepared directly. Black-Right-Pointing-Pointer Copper nanoparticles were simultaneously in situ formed in carbon nanotubes. Black-Right-Pointing-Pointer Electrodes were modified with platinum particles supported on such composites. Black-Right-Pointing-Pointer Electrodes showed excellent electrocatalytic activity for oxidation of methanol.

  10. Atomic emission and atomic absorption spectrometric analysis of high-purity powders for the production of ceramics

    Direct analysis methods and multistage combined analytical procedures for the determination of impurities at the μg/g level and the upper ng/g level in high-purity powders of Al2O3, AlN, Si3N4 and SiC are described. Results obtained with a novel direct slurry-atomization technique using a Babington nebulizer and inductively coupled plasma optical emission spectrometry (ICP-OES) are presented. A comparison of analysis results of combined analytical procedures including wet chemical decomposition and determinations with graphite furnace atomic absorption spectrometry (ETAAS) or ICP-OES with those of slurry-atomization ICP-OES show the capabilities of this technique for routine analysis in production control. Detection limits for Al, B, Ca, Co, Cu, Fe, Mg, Mn, Si, Ti, W, V, and Zn in the matrices mentioned are between 0.03 and 2.5 μg/g. For elemental concentrations ≥10 μg/g relative standard deviations of the measurements are generally below 10%. The technique is shown to be a powerful tool for trace determinations in powder samples. This is shown by its use for analysis of a series of the ceramic powders mentioned and comparative results of other direct techniques such as total reflection X-ray fluorescence spectrometry and instrumental neutron activation analysis. (orig.)

  11. Cu O-CeO2 catalysts for the CO preferential oxidation (CO PROX)

    The aim of this work is to synthesize and characterize Cu-Ce catalysts prepared by homogeneous precipitation with urea and, also, to evaluate their catalytic activity for the preferential oxidation of CO.Cu-Ce precursors with different copper content were prepared (the atomic ratio of copper to total metal was varied between 0 and 60%). Upon mild thermal treatment under air atmosphere (T = 723 K) powders are readily converted into nano-CeO2 with high superficial area.The catalysts were characterized by X-ray diffraction, it was found that all of them contained CeO2 (cerianite), and only the sample with the highest copper content contained Cu O (tenorite).The samples were evaluated in the catalytic reaction of preferential oxidation of CO in the temperature range between 373 and 523 K.It was found that they are very active and selective.The best catalytic performance was shown by the catalysts with a copper to total metal ratio of 10 to 20%

  12. PREPARATION AND CHARACTERIZATION OF NANOSTRUCTURED GRANULAR SUPPORT PARTICLES AND CATALYTIC MATERIALS; F

    We have set up successfully two experimental systems during the past time of the project. The first system is sol-gel chemical method for preparing(gamma)-Al(sub 2)O(sub 3), SiO(sub 2), Cr(sub 2)O(sub 3) granular support particles. The second system is the laser-induced solution deposition (LISD) technique for nanoparticle catalysts containing Fe/Cu, and Co/Cu on the granular support. We have successfully deposited(gamma)-Al(sub 2)O(sub 3), SiO(sub 2), Cr(sub 2)O(sub 3) granular support particles by sol-gel method and Co and CoO nanoparticles by LISD novel fabrication technique. The characterization methods we have used include scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM) and X-Ray diffraction (XRD). The research toward to the proposed direction is in good progress. We have given three presentations in national and local materials meetings and have submitted another two papers in another two key national meetings in nanotechnology and American Physical Annual March Meeting 2002. A couple of papers are in preparation

  13. Trace elements and Pb isotope records in Dome C (East Antarctica ice over the past 800,000 years

    Hong S.

    2013-04-01

    Full Text Available Trace elements (V, Cr, Mn, Fe, Co, Cu, Zn, As, Rb, Sr, Mo, Cd, Sb, Ba, Tl, Pb, Bi, Th and U and Pb isotopic compositions from the EPICA (European Project for Ice Coring in Antarctica Dome C ice core have been determined using inductively coupled plasma sector field mass spectrometry (ICP-SFMS and thermal ionization mass spectrometry (TIMS, covering the period from ~533 kyr BP to ~800 kyr BP, respectively. Our data have enabled us to extend the previous EDC records of trace elements and Pb isotopes from the Holocene back to the Marine Isotopic Stage 20.2, ~800 kyr BP. We here discuss the EDC records of Ba, Rb, Mo, Sb, Cd, Tl, Bi and Pb isotopes. Crustal elements such as Ba and Rb show well defined variations in concentrations in relation to climatic conditions with lower values during the interglacial periods and much higher values during the coldest periods of the last eight climatic cycles. Volcanogenic Cd, Tl and Bi show a less pronounced relationship between concentrations and climatic conditions. The isotopic signatures of Pb suggest that changes in the provenance of dust reaching the East Antarctic Plateau from Potential Source Areas occurred during the interglacial periods before the MBE. Our data suggest that the main factors affecting deposition fluxes and sources of natural trace elements over Antarctica are most likely linked to a progressive coupling of the climates of Antarctica and lower latitudes over the past 800 kyr.

  14. Analysis of heavy metal sources in soil using kriging interpolation on principal components.

    Ha, Hoehun; Olson, James R; Bian, Ling; Rogerson, Peter A

    2014-05-01

    Anniston, Alabama has a long history of operation of foundries and other heavy industry. We assessed the extent of heavy metal contamination in soils by determining the concentrations of 11 heavy metals (Pb, As, Cd, Cr, Co, Cu, Mn, Hg, Ni, V, and Zn) based on 2046 soil samples collected from 595 industrial and residential sites. Principal Component Analysis (PCA) was adopted to characterize the distribution of heavy metals in soil in this region. In addition, a geostatistical technique (kriging) was used to create regional distribution maps for the interpolation of nonpoint sources of heavy metal contamination using geographical information system (GIS) techniques. There were significant differences found between sampling zones in the concentrations of heavy metals, with the exception of the levels of Ni. Three main components explaining the heavy metal variability in soils were identified. The results suggest that Pb, Cd, Cu, and Zn were associated with anthropogenic activities, such as the operations of some foundries and major railroads, which released these heavy metals, whereas the presence of Co, Mn, and V were controlled by natural sources, such as soil texture, pedogenesis, and soil hydrology. In general terms, the soil levels of heavy metals analyzed in this study were higher than those reported in previous studies in other industrial and residential communities. PMID:24693925

  15. Bioavailability assessment of essential and toxic metals in edible nuts and seeds.

    Moreda-Piñeiro, Jorge; Herbello-Hermelo, Paloma; Domínguez-González, Raquel; Bermejo-Barrera, Pilar; Moreda-Piñeiro, Antonio

    2016-08-15

    Bioavailability of essential and toxic metals in edible nuts and seeds has been assessed by using an in vitro dialyzability approach. The samples studied included walnuts, Brazil nuts, Macadamia nuts, pecans, hazelnuts, chestnuts, cashews, peanuts, pistachios and seeds (almond, pine, pumpkin and sunflower). Metals were measured by inductively coupled plasma-mass spectrometry in dialyzates and also in samples after a microwave assisted acid digestion pre-treatment. Low dialyzability percentages were found for Al, Fe and Hg; moderate percentages were found for Ba, Ca, Cd, Co, Cu, K, Li, Mg, Mn, Mo, P, Pb, Se, Sr, Tl and Zn; and high dialyzability ratios were found for As, Cr and Ni. The highest dialyzability percentages were found in raw chestnuts and raw hazelnuts. Metal dialyzability was found to be negatively affected by fat content. Positive correlation was found between carbohydrate content and metal dialyzability ratios. Protein and dietary fibre content did not influence metal bioavailability. Predicted dialyzability for some metals based on fat and protein content could also be established. PMID:27006225

  16. Trace element uptake by Eleocharis equisetina (spike rush) in an abandoned acid mine tailings pond, northeastern Australia: Implications for land and water reclamation in tropical regions

    This study was conducted to determine the uptake of trace elements by the emergent wetland plant species Eleocharis equisetina at the historic Jumna tin processing plant, tropical Australia. The perennial emergent sedge was found growing in acid waters (pH 2.45) and metal-rich tailings (SnAsCuPbZn). E. equisetina displayed a pronounced acid tolerance and tendency to exclude environmentally significant elements (Al, As, Cd, Ce, Co, Cu, Fe, La, Ni, Pb, Se, Th, U, Y, Zn) from its above-substrate biomass. This study demonstrates that geobotanical and biogeochemical examinations of wetland plants at abandoned mined lands of tropical areas can reveal pioneering, metal-excluding macrophytes. Such aquatic macrophytes are of potential use in the remediation of acid mine waters and sulfidic tailings and the reclamation of disturbed acid sulfate soils in subtropical and tropical regions. - Highlights: → In tropical Australia, Eleocharis equisetina grows in an acid mine tailings pond. → Eleocharis equisetina excludes environmentally significant elements from its biomass. → Inspections of equatorial mined lands can reveal metal-excluding aquatic macrophytes. → Such plants are of use in land and water remediation in tropical regions. - The metal-excluding aquatic macrophyte Eleocharis equisetina is of use in land and water remediation in tropical regions.

  17. Proficiency assessment through interlaboratory comparison: case of water testing and calibration in terms of minor and major ions and trace metals at INSTN-Madagascar

    The present report is focused on proficiency assessment in which INSTN-Madagascar takes part. The results of interlaboratory comparisons organized, since 2007, annually by SADC WaterLab Association are presented. It is about results from consecutive six years allowing INSTN-Madagascar to evaluate its performance and capabilities as far as water tests are concerned. Total Reflection X-ray Fluorescence spectrometry and Atomic Absorption Spectrometry are used to measure the following trace metals: Al, Cr, Mn, Fe, Ni, Co, Cu, Zn, As, Cd, Pb. On the other hand, the analyses of minor and major ions such as Cl-, F-, NO3-, SO42-, PO43-, K+, Na+, Ca2+, Mg2+ are conducted by using Ion Chromatograph. Effectively, the proficiency assessment program is a mechanism by which a laboratory can demonstrate its competence based on practical evaluation in order to produce technically valid data and results. Consequently, the laboratory has a valuable opportunity to demonstrate its commitment to stake holders and clients that its analytical staff has confidence in their abilities. To illustrate, a graphical distribution of z-scores calculated from the results of water measurements is presented. The PT exercises were carried out at INSTN-Madagascar during the period of 2007 to 2012. To conclude, INSTN-Madagascar has succeeded to have more than 80% of the values within tolerance limits on 2007, 2008, 2010, 2011 and 2012.

  18. Determination of trace metals in river sediment

    This study forms part of the NIWR's series of interlaboratory comparison studies involving southern African laboratories engaged in water and wastewater analysis, and is concerned with the analysis by 21 laboratories of a standard reference sample of river sediment for arsenic, cadmium, cobalt, copper, lead, manganese, mercury, nickel and zinc. The results obtained are evaluated and discussed, along with some of the advantages and disadvantages of various sample pretreatment techniques. The mean values of the results obtained for Cu, Hg, Pb, Ni and Zn were found to be in good agreement with the certified values for the standard reference sample, but those for Cd and Mn were considerably lower than the corresponding certified values. A fairly wide range of acid extraction or digestion procedures for pretreatment of the sample was used by the participating laboratories, most of whom employed direct flame atomic absorption spectrophotometry for the measurement of Cd, Co, Cu, Pb, Mn, Ni, and Zn. The few laboratories who determined As and Hg did so mainly by means of vapour generation/atomic absorption techniques

  19. Simultaneous Determination of 30 Trace Elements in Cancerous and Noncancerous Human Tissue Samples with Gamma-ray Spectrometry

    The following trace elements were quantitatively determined by gamma-ray spectrometry in T samples of non-cancerous and 5 samples of cancerous human tissue: P, Ca, Cr, Fe, Co, Cu, Zn, As, Se, Br, Rb, Mo, Ag, Cd, Sb, Cs, La, Au, and Hg. In some of the samples the following elements were qualitatively determined: Ti+Sc, Ga, Sr, In, Ba, Ce, Hf, Os, Pt, and U. Most of the trace elements were found to be present in much higher concentrations in the non-cancerous than in the corresponding cancerous liver samples. In a typical run one sample each of cancerous and non-cancerous tissue was irradiated together with standards of the elements to be determined in a thermal flux of 2.1013 n/cm2/sec. for 24 hours. The radioactive trace elements were separated into 16, and in some cases 18, groups by means of a chemical group separation method. Subsequently, the gamma spectrometric measurements were performed. Two persons can manage the chemical separations and measure the different activities from a run in 1,5 days. A new method of comparing unknown samples with standards was developed

  20. Surfactant action in heteroepitaxy: Growth of Co on (4x4)Pb/Cu(111) studied by LEED and STM

    The magnetic properties of ultrathin Co films and Co/Cu heterostructures grown on Cu(111) have been shown to improve when Pb is used as a surfactant: the thickness range of Co films displaying perpendicular magnetic anisotropy is extended and a complete antiferromagnetic coupling between them is made possible. In this paper, we aim to understand the origin of these magnetic properties by illuminating the crystallographic structure and morphology of the films. We apply low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM) to ultrathin epitaxial Co films grown on the Cu(111) surface precovered by 1 monolayer (ML) of Pb in the (4x4) superstructure. The Pb layer is found to segregate to the surface of the growing films and STM images show that the growth of Co proceeds in the layer-by-layer mode for coverages higher than 2 ML. For lower coverages, a coexistence of 1 ML and 2 ML high islands is observed on the terraces. A quantitative comparison of experimental LEED spectra shows that the structural transition from fcc to hcp stacking with increasing thickness of the Co films deposited on the Cu(111) substrate is not significantly affected by the surfactant. Instead, the latter induces the formation of sharp interfaces that favor the interface contribution to the magnetic anisotropy and allow the growth of rather smooth films with well-defined thicknesses

  1. Electronic and magnetic properties at rough and sharp transition metal–metal interfaces: An augmented space approach

    The augmented space formalism (ASF) coupled with recursion method and a tight binding linear muffin-tin orbital basis has been applied to study the layerwise electronic and magnetic properties of (0 0 1) interfaces of body-centered cubic Fe/Ag and face centered cubic Co/Ag, Fe/Cu and Co/Cu. Three different thickness of interfaces are considered: mono, two and three layers of transition metals with metal substrates. Layers of an interface are considered disordered alloys with different degree of disorderedness due to interdiffusion of transition metal layer atoms and substrate atoms during growth process. We show that ASF is applicable to sharp interface also. Result of three layers of transition metal rough interface agrees well with available experimental result. - Highlights: • Study of rough interface of transition metals by augmented space formalism. • Same formalism is extended for nearly sharp interface. • Comparison is made for smooth, 1 layer and 4 layers roughed surfaces. • Layerwise magnetic moments and electronic properties are studied. • Rough interface with 3 layers of transition metals agrees with experiment

  2. Radionuclide X-ray fluorescence analysis of selected elements in drug samples with 8-hydroxyquinoline preconcentration

    The preconcentration performance characteristics of precipitation of Mn, Fe, Co, Cu, Zn, Pb, Ni and Hg with 8-hydroxyquinoline (8HQ) and subsequent filtration through cellulose nitrate membrane were investigated for the X-ray fluorescence spectrometry identification and determination of trace metal ions in drug samples. Several parameters of the method were optimised, including pH and amount of 8HQ. The investigated ions were collected on cellulose nitrate membrane filter (Pragopor 4) as their complexes after the reaction with 8HQ. To conclude, optimal reaction conditions were found out (pH 10.5 for Fe, Co and pH 11.5 for Mn, Cu Zn, Pb and Hg, volume of 20 μl of the 2 % solution of hydroxyquinoline). Thereafter, the content of these elements was determined in the active substances of the infusion and injection solutions, i.e. NaCl, glucose and dextrane, and the results were compared with those ones obtained after the preconcentration with thioacetamid. The rapidity of this method, its multi-element character and low detection limits proved this method to be a very promising in rapid screening in quality control of drugs. (author)

  3. Positive/negative magnetostrictive GMR trilayer systems as strain gauges

    Recently, highly sensitive strain gauges were developed, which are based on tunnel magnetoresistance (TMR) or giant magnetoresistance (GMR) effects combined with the inverse magnetostriction. GMR and TMR structures generally possess a symmetrical characteristic, which reflects the switching fields of the soft and hard layers, respectively. This characteristic can be changed by a stress field if the soft layer is replaced by a suitable magnetostrictive layer leading to a stress-induced rotation of the magnetostrictive layer with respect to the reference layer. Alternatively, both magnetic layers can be soft magnetic, one being positive and the other negative magnetostrictive. In this case, a stress applied on the stack leads to a reverse rotation of both layers due to the different sign in magnetostriction. This new approach is especially attractive since no reference layer is required which allows multilayering for GMR effect enhancement. This paper presents the stress biased characteristics of (FeCo/Cu/Ni) GMR trilayers in which the positive magnetostrictive FeCo and the negative magnetostrictive Ni replace the sensing and reference layer of a conventional GMR stack. The results can be interpreted by a simple model taking into account the magnetization direction of the individual layers and their response to mechanical strain in the range of 0.1-1%o

  4. Trace metals partitioning among different sedimentary mineral phases and the deposit-feeding polychaete Armandia brevis.

    Díaz-de-Alba, Margarita; Huerta-Diaz, Miguel Angel; Delgadillo-Hinojosa, Francisco; Hare, Landis; Galindo-Riaño, M Dolores; Siqueiros-Valencia, Arturo

    2016-02-01

    Trace metals (Cd, Co, Cu, Fe, Mn, Ni, Pb, Zn) were determined in two operationally defined fractions (HCl and pyrite) in sediments from Ensenada and El Sauzal harbors (Mexico). The HCl fraction had significantly higher metal concentrations relative to the pyrite fraction in both harbors, underlining the weak tendency of most trace metals to associate with pyrite. Exceptionally, Cu was highly pyritized, with degrees of trace metal pyritization (DTMP) >80% in both harbors. Dissolved Fe flux measurements combined with solid phase Fe sulfide data indicated that 98 mt of Fe are precipitated as iron sulfides every year in Ensenada Harbor. These Fe sulfides (and associated trace metals) will remain preserved in the sediments, unless they are perturbed by dredging or sediment resuspension. Calculations indicate that dredging activities could export to the open ocean 0.20±0.13 to (0.30±0.56)×10(3) mt of Cd and Cu, respectively, creating a potential threat to marine benthic organisms. Degrees of pyritization (DOP) values in Ensenada and El Sauzal harbors were relatively low (making it a useful biomonitor of sedimentary metal exposure. PMID:26595396

  5. Temporal changes of 210Po in temperate coastal waters

    The temporal variation of Polonium-210 (210Po) was examined in coastal sea water, the mussel Mytilus edulis, the winkle Littorina littorea and green algae Ulva lactuca in order to investigate the entry of 210Po into the marine food chain. More than 99% of 210Po in the water column occurred in the particulate phase. Dissolved 210Po concentrations peaked during the spring phytoplankton bloom and it is suggested this is related to preferential scavenging of 210Po by the increased numbers of bacteria, viruses and small dissolved particulates. Changes in L. Littorea 210Po specific activity are thought not to be related to food, but to a drop in body weight following spawning. Much of the 210Po accumulated by M. edulis was located in the digestive gland. The specific activity of 210Po in the digestive gland of M. edulis was shown to be strongly correlated with changes in sea water suspended particulate specific activity. Examination of other trace metal (Ag, Al, As, Ca, Cd, Cr, Co, Cu, Fe, Hg, K, Mg, Mn, Na, Ni Sb, Se, Sn and Zn) variations in the digestive gland revealed that class B and borderline metals had a strong positive correlation with 210Po. On-going work is investigating whether the accumulation and loss of 210Po is affected by the presence of metallothioneins

  6. Synthesis, characterization and study of the magnetic properties of a coordination polymer containing cobalt(II) and copper(II); Sintese, caracterizacao e estudo das propriedades magneticas de um polimero de coordenacao contendo cobalto(II) e cobre(II)

    Cunha, Tamyris T. da; Stumpf, Humberto O.; Pereira, Cynthia L.M., E-mail: cynthialopes@ufmg.br [Departamento de Quimica, Instituto de Ciencias Exatas, Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil); Pires, Heber S.; Oliveira, Luiz F.C. de [Departamento de Quimica, Instituto de Ciencias Exatas, Universidade Federal de Juiz de Fora, MG (Brazil); Pedroso, Emerson F. [Departamento de Quimica, Centro Federal de Educacao Tecnologica de Minas Gerais, Belo Horizonte, MG (Brazil); Nunes, Wallace C. [Instituto de Fisica, Universidade Federal Fluminense, Niteroi, RJ (Brazil)

    2012-07-01

    This work describes the synthesis and characterization of two new compounds with ligand opy (N-(2-pyridyl)oxamate): the copper(II) precursor [Me{sub 4}N]{sub 2}[Cu(opy){sub 2}].5H{sub 2}O and Co{sup II} Cu{sup II} coordination polymer {l_brace}[Co Cu(opy){sub 2}]{r_brace}{sub n}x4nH{sub 2}O. This latter compound was obtained by reaction of [Me{sub 4}N]{sub 2}[Cu(opy){sub 2}].5H{sub 2}O and CoCl{sub 2}.6H{sub 2}O in water. The heterobimetallic Co{sup II} Cu{sup II} chain was characterized by elemental analysis, IR spectroscopy, thermogravimetry and magnetic measurements. Magnetic characterization revealed typical behavior of one-dimensional (1D) ferrimagnetic chain as shown in the curves of temperature (T) dependence of magnetic susceptibility ({chi}{sub M}), in the form of {chi}{sub M}T versus T, and dependence of magnetization (M) with applied field (H). (author)

  7. Determination of Heavy Metals in Eight Barley Cultivars Collected from Wheat Research Station Tandojam, Sindh, Pakistan

    Fateh M. Soomro

    2013-06-01

    Full Text Available Barley (Hordeum Vulgare L. is one of the most important foods for animals and possesses high nutritional value. In this paper, we have focused our study to find out the chemical parameters, especially metal content of this class of food commodity and its soil, which is not frequently used for human food. Wet digestion method was used to destroy the organic matrix to determine the content of eleven metals i.e. Iron, Zinc, Manganese, Copper, Cobalt, Chromium, Nickel, Lead, Cadmium, Barium and Aluminium, from eight Pakistani barley cultivars. The highest level of elements were determined in order; Cd < Ni < Pb < Cr < Co < Cu < Ba < Al < Mn < Zn < Fe in mg/kg. All analysis was carried out by using air- acetylene except Al and Ba where as both of these metals analysed on air-acetylene and nitrous oxide flame on Atomic Absorption Spectrophotometer. Among all these entries, maximum concentration of Fe was detected in B6, Zn in B5, Mn, & Cu in B2 & B5, Co in B1, Ba in B7, Al in B8 and rest of the elements i.e. Cr, Pb, Ni and Cd were found to be with little difference of concentration among cultivars.

  8. Thickness and ordering temperature of surface NiO/Ni systems

    Ying-Ta Shih

    2014-02-01

    Full Text Available We estimate the thickness and ordering temperature of an antiferromagnetic and passivation surface oxide through exchange bias coupling. The surface NiO, which is generated through the exposure of a Ni/Cu(001 surface to oxygen, is taken as a model system on which to perform the estimation. Since no exchange bias is found in the surface NiO/Ni/Cu(001, we have built a sandwich structure of NiO/n ML Ni/10 ML Co/Cu(001 to measure the n dependence of exchange bias. With n ⩽ 2, a large exchange bias field is found above 300 K, which could be due to the direct contact between the oxides and the Co layer. With 3 ⩽ n ⩽ 6, a smaller exchange bias field is found with a blocking temperature of 190 K. This implies that the thickness of NiO is, at most, 3 ML. Discovering the thickness and ordering temperature of the surface NiO provides us to explore the potential applications by using surface NiO.

  9. Microbial community induces a plant defense system under growing on the lunar regolith analogue

    Zaetz, Irina; Mytrokhyn, Olexander; Lukashov, Dmitry; Mashkovska, Svitlana; Kozyrovska, Natalia; Foing, Bernard H.

    The lunar rock considered as a potential source of chemical elements essential for plant nutrition, however, this substrate is of a low bioavailability. The use of microorganisms for decomposition of silicate rocks and stimulation of plant growth is a key idea in precursory scenario of growing pioneer plants for a lunar base (Kozyrovska et al., 2004; 2006; Zaetz et al., 2006). In model experiments a consortium of well-defined plant-associated bacteria were used for growing of French marigold (Tagetes patula L.) in anorthosite, analogous to a lunar rock. Inoculated plants appeared better seed germination, more fast development and also increased accumulation of K, Mg, Mn, Co, Cu and lowered level of the toxic Zn, Ni, Cr, comparing to control tagetes'. Bacteria regulate metal homeostasis in plants by changing their bioavailability and by stimulating of plant defense mechanisms. Inoculated plants were being accommodated to growth under stress conditions on anorthosite used as a substrate. In contrast, control plants manifested a heavy metal-induced oxidative stress, as quantified by protein carbonyl accumulation. Depending on the plant organ sampled and developmental stage there were increases or loses in the antioxidant enzyme activities (guaiacol peroxidase and glutathione-S-transferase). These changes were most evident in inoculated plants. Production of phenolic compounds, known as antioxidants and heavy metal chelators, is rised in variants of inoculated marigolds. Guaiacol peroxidase plays the main role, finally, in a reducing toxicity of heavy metals in plant leaves, while glutathione-S-transferase and phenolics overcome stress in roots.

  10. The isotypic family of the diarsenates MM'As{sub 2}O{sub 7} (M = Sr, Ba; M' = Cd, Hg)

    Weil, Matthias [Technische Univ. Wien (Austria). Inst. for Chemical Technologies and Analytics

    2016-08-01

    The diarsenates MM'As{sub 2}O{sub 7} (M = Sr, Ba; M' = Cd, Hg) were prepared under hydrothermal conditions (∝200 C, autogenous pressure), starting from As{sub 2}O{sub 5} and the corresponding metal oxides or precursor compounds thereof in aqueous solutions. Structure analyses on the basis of single crystal X-ray data revealed the four structures to be isotypic. They are the first diarsenates to crystallize in the triclinic BaZnP{sub 2}O{sub 7} structure type (space group P anti 1, Z = 2, a ∼ 5.8 Aa, b ∼ 7.3 Aa, c ∼ 7.6 Aa, α ∼ 101 , β ∼ 91 , γ ∼ 98 ). All related MM'As{sub 2}O{sub 7} diarsenates reported so far (M = Sr, Ba, Pb; M' = Mg, Co, Cu, Zn) crystallize in the monoclinic α-Ca{sub 2}P{sub 2}O{sub 7} structure type (P2{sub 1}/n, Z = 4). Hence, the size of the divalent M' cation determines which of the two structure types is adopted.

  11. A water-in-oil emulsion containing Kelex-100 for the speciation analysis of trace heavy metals in water

    A water-in-oil (w/o) emulsion containing Kelex-100 (7-dodecenyl-8-quinolinol) and Span-80 (sorbitan monooleate, non-ionic surfactant) was ultrasonically prepared from 1.0 mol l-1 hydrochloric acid and a (1 + 3) mixture of toluene and n-heptane. The resulting emulsion was gradually injected into water sample and dispersed as numerous tiny globules (0.01-0.1 mm in diameter). Dissolved inorganic species (free metal species) of heavy metals (e.g., Fe, Co, Cu, Cd, and Pb) were selectively transported through the oil layer into the internal aqueous phase of the emulsion, leaving other species, such as humic complexes and suspended particles (larger than 1 μm), in the sample solution. After collecting the dispersed emulsion globules, they were demulsified and the heavy metals in the segregated aqueous phase were determined by graphite-furnace atomic absorption spectrometry. The emulsion-based separation method allowed the selective collection of free metal species with a high concentration factor of 100, whereas the conventional solvent extraction did not offer such discrimination. This unique property of the emulsion method was successfully applied to the selective determination of free species of heavy metals in fresh water samples

  12. Aerobic methylcyclohexane-promoted epoxidation of stilbene over gold nanoparticles supported on Gd-doped titania

    Mendez, Violaine

    2010-01-01

    Aerobic partial oxidations of alkanes and alkenes are important processes of the petrochemical industry. The radical mechanisms involved can be catalyzed by soluble salts of transition metals (Co, Cu, Mn...). We show here that the model methylcyclohexane/stilbene co-oxidation reaction can be efficiently catalyzed at lower temperature by supported gold nanoparticles. The support has little influence on gold intrinsic activity but more on the apparent reaction rates which are a combination of catalytic activity and diffusion limitations. These are here minimized by using gadolinium-doped titania nanocrystallites as support for gold nanoparticles. This material is obtained by mild hydrolysis of a new Gd4TiO(OiPr)14 bimetallic oxoalkoxide. It leads to enhanced wettability of the < 3 nm gold particles in the tert-butyl hydroperoxide (TBHP)-initiated epoxidation of stilbene in methylcyclohexane; Au/TiO2:Gd3+ is in turn as active as the state-of-the-art hydrophobic Au/SiO2 catalyst. The rate-determining step of this reaction is identified as the gold-catalyzed homolytic decomposition of TBHP generating radicals and initiating the methylcyclohexane-mediated epoxidation of stilbene, yielding a methylcyclohexan-1-ol/trans-stilbene oxide mixture. Methylcyclohexan-1-ol can also be obtained in the absence of the alkene in the gold-catalyzed solvent-free autoxidation of methylcyclohexane, evidencing the catalytic potential of gold nanoparticles for low temperature C-H activation. © 2010 The Royal Society of Chemistry.

  13. Assessment of heavy metals in Averrhoa bilimbi and A. carambola fruit samples at two developmental stages.

    Soumya, S L; Nair, Bindu R

    2016-05-01

    Though the fruits of Averrhoa bilimbi and A. carambola are economically and medicinally important, they remain underutilized. The present study reports heavy metal quantitation in the fruit samples of A. bilimbi and A. carambola (Oxalidaceae), collected at two stages of maturity. Heavy metals are known to interfere with the functioning of vital cellular components. Although toxic, some elements are considered essential for human health, in trace quantities. Heavy metals such as Cr, Mn, Co, Cu, Zn, As, Se, Pb, and Cd were analyzed by atomic absorption spectroscopy (AAS). The samples under investigation included, A. bilimbi unripe (BU) and ripe (BR), A. carambola sour unripe (CSU) and ripe (CSR), and A. carambola sweet unripe (CTU) and ripe (CTR). Heavy metal analysis showed that relatively higher level of heavy metals was present in BR samples compared to the rest of the samples. The highest amount of As and Se were recorded in BU samples while Mn content was highest in CSU samples and Co in CSR. Least amounts of Cr, Zn, Se, Cd, and Pb were noted in CTU while, Mn, Cu, and As were least in CTR. Thus, the sweet types of A. carambola (CTU, CTR) had comparatively lower heavy metal content. There appears to be no reason for concern since different fruit samples of Averrhoa studied presently showed the presence of various heavy metals in trace quantities. PMID:27080855

  14. Elemental analysis of granite by instrumental neutron activation analysis (INAA) and X-ray fluorescence analysis (XRF).

    El-Taher, A

    2012-01-01

    The instrumental neutron activation analysis technique (INAA) was used for qualitative and quantitative analysis of granite samples collected from four locations in the Aswan area in South Egypt. The samples were prepared together with their standards and simultaneously irradiated in a neutron flux of 7×10(11)n/cm(2)s in the TRIGA Mainz research reactor. Gamma-ray spectra from an hyper-pure germanium detector were analyzed. The present study provides the basic data of elemental concentrations of granite rocks. The following elements have been determined Na, Mg, K, Fe, Mn, Sc, Cr, Ti, Co, Zn, Ga, Rb, Zr, Nb, Sn, Ba, Cs, La, Ce, Nd, Sm, Eu, Yb, Lu, Hf, Ta, Th and U. The X-ray fluorescence (XRF) was used for comparison and to detect elements, which can be detected only by XRF such as F, S, Cl, Co, Cu, Mo, Ni, Pb, Se and V. The data presented here are our contribution to understanding the elemental composition of the granite rocks. Because there are no existing databases for the elemental analysis of granite, our results are a start to establishing a database for the Egyptian granite. It is hoped that the data presented here will be useful to those dealing with geochemistry, granite chemistry and related fields. PMID:21992845

  15. Migration of trace elements from basalt substrate to co-located vegetation (lichens and mosses) at the Wudalianchi volcanos, Northeast China

    Bao, Yuan; Ju, Yiwen; Li, Boping; Sun, Yimin

    2016-03-01

    Vegetation (e.g., lichens and mosses) living on the basalt substrate have potential to accumulate trace elements in their tissues. Here, we analyze the trace elements in basalt (collected from major volcanic center to jet plate places, representing four different eruption phases) and adjacent lichens and mosses to assess their elemental source-receptor relation. The results indicate that As, Sr, Mo, Cd, and Ba are enriched in basalt, and depleted in lichens and mosses. However, Zn, Hg, and Pb are enriched in lichens and mosses and depleted in basalt. Moreover, with the increase of basalt age, Cr, Mn, Fe, Ni, and Cu are gradually enriched in lichen and moss, but gradually depleted in basalt. Compared with transition metals, large ion lithophiles, the platinum group, and rare earth elements, Cr, Co, Cu, Zn, and Os are more easily absorbed by No. 1 lichen. Specifically, S is highly assimilated in vegetation, with a highest value of 166, followed by I, C, Pb, Zn, and Hg. In addition, the hydrogen and oxygen isotopic compositions of water samples suggest that the surface water in the Wenbo area came from meteoric waters in summer with a high humidity, while the underground water in the Beiyaoquan area came from meteoric waters in winter with a low humidity.

  16. Radionuclide activities and metal concentrations in sediments of the Sebou Estuary, NW Morocco, following a flooding event.

    Laissaoui, A; Mas, J L; Hurtado, S; Ziad, N; Villa, M; Benmansour, M

    2013-06-01

    This study presents metal concentrations (Fe, Mg, Mn, Co, Cu, Zn, Pb, As, Sr and V) and radionuclide activities ((40)K, (137)Cs, (210)Pb, (226)Ra, (228)Ac, (234)Th and (212)Pb) in surface deposits and a sediment core from the Sebou Estuary, Northwest Morocco. Samples were collected in April 2009, about 2 months after a flooding event, and analysed using a well-type coaxial gamma-ray detector and inductively coupled plasma-quadrupole mass spectrometry. Activities of radionuclides and concentrations of almost all elements in surface samples displayed only moderate spatial variation, suggesting homogenous deposition of eroded local soil in response to intense precipitation. Excess (210)Pb displayed relatively constant activity throughout the sediment core, preventing dating and precluding determination of the historical accumulation rates of pollutants at the core site. Some elements showed non-systematic trends with depth and displayed local maxima and minima. Other elements presented relatively systematic concentration trends or relatively constant levels with discrete maxima and/or minima. Except for Mn, Sr and Cr, all metal concentrations in sediment were below levels typical of polluted systems, suggesting little human impact or losses of metals from sediment particles. PMID:23054286

  17. Trace metals and radionuclides in macroalgae from Moroccan coastal waters.

    Benkdad, Azzouz; Laissaoui, Abdelmourhit; Tornero, Maria Victoria; Benmansour, Moncef; Chakir, ElMahjoub; Garrido, Ignacio Moreno; Moreno, Julian Blasco

    2011-11-01

    Macroalgae species Codium sp, Bangia atropurpurea, Membranoptera alata, Plocamium cartilagineum, Dictyota dichotoma, Fucus spiralis and Stypocaulon scoparia were collected from seven stations along the north coast of Morocco. Samples were analysed to determine activities of naturally occurring radionuclides ((210)Pb, U isotopes and (40)K) and concentrations of metals (Zn, Fe, Co, Cu, Ni, Mn, Pb, Cd, As and Cr) using radiometric and ICP-OES techniques, respectively. Metal concentrations were within ranges reported in the scientific literature, and concentrations of bio-essential elements were in the order Mn>Fe> Zn>Cu in all samples. Brown algae had the highest concentrations of almost all metals, and concentrations decreased in the order brown>red>green algae. With respect to radionuclides, the red alga P. cartilagineum had the highest activities of (210)Pb, in most cases an order of magnitude higher than for the green alga Codium sp. (234)U and (238)U activities in all algae samples were in the range 0.96- 7.61 and 1.16-6.14 Bq/kg dry weight, respectively. Our analyses of radionuclide activities and metal concentrations in marine macroalgae showed large differences among taxa. These results provide insights into which algal species should be used for biomonitoring programmes. PMID:21298402

  18. Methods for neutron activation determination of metallic microconcentrations in oils and bitumens

    The neutron activation method for determining Co, Na, Mn, Br, Cu, Zn, Ga, As, and Sc is discussed. A quartz ampoule containing petroleum coke or oil (0.5 to 1 g) and a standard sample are placed into an aluminium cylindrical case. Irradiation is carried out with a neutron flux of 1.2x1013 per cm2xc for 30 to 60 min, followed by a delay of several hours. Repeated spectra measurements during 7 to 10 days are made with a scintillation counter (with a 40x50 mm NaI crystal and a 6.5% resolution for the 1.33 MeV line of 60Co) having an AI-100 or an AI-256 pulse analyser. When a quantitative analysis is made the gamma-peak intensities of the standard sample and the specimen are compared. The reproducibility evaluated by independent determination of Co, Na, and Br in oils is characterized by a 20% mean-root-square error in a single determination. The Co, Cu, Ga, Zn, and Mn analysis features are described

  19. PREPARATION,COMPLEX MECHANISM AND STRUCTURE MODEL OF METALLOPHTHALOC- YANINE-Fe3O4 NANOPARTICLES COMPOSITE

    2000-01-01

    MPc-Fe3O4-nanoparticles composite(M=Co, Cu, Ni, Mn) have been prepared and the factors that influence their mean size have been studied. The mean size of the nanoparticles composite increase with the increase of complex temperature. The interaction of MPc with Fe3O4 nanoparticles has been studied. There are M-O covalent bonding and ionic bonding between MPc and Fe3O4 nanoparticles. The intensities of M-O bonding and ionic bonding are in vestigated .The complex mechanism of MPc with Fe3O4 nanoparticles have been studied. First, there are complex between MPc and all Fe3O4 nanoparticles. Then, Fe3O4 nanoparticles accumulate together to form the accumulators, MPc have the function of cohering Fe3O4 nanoparticles. A considerable number of MPc combine with Fe3O4 nanoparticles on the surface of the accumulators to form MPc-Fe3O4 nanoparticles composite. All the above proesses take place spontaneously. The structure model of MPc-Fe3O4 nanoparticles composite has also been investigated. Inside the MPc-Fe3O4 nanoparticles composite, Fe3O4 nanoparticles accumulate together without order, on the surface of the composite, MPc form molecular dispersion layer. The threshold of molecular dispersion layer are also investigated.

  20. Study on the Properties of Metallophthalocyanine-Fe3O4 Nanoparticles Composite

    2001-01-01

    The solubility,antioxidation ability,thermal stability,coercivity Hc and long term stability of MPc-Fe3O4-nanoparticles composite(M=Co,Cu,Ni,Mn) have been studied.The results show that MPc-Fe3O4 nanoparticles composite can be easily dissolved in dilute acid.The dissolving rate of different MPc-Fe3O4 nanoparticles composite is in the following order:M=Mn~M=Co<M=Cu<M=Ni.The antioxidation ability of Fe3O4 nanoparticles are improved greatly after their complex with MPc and there is good relationship between Toxidation of Fe3O4 nanoparticles and n ,the complex layers of MPc on the surface of the composite.The results also show that the thermal stability of Fe3O4 nanoparticles increases greatly and the Hc of them decreases dramatically after Fe3O4 nanoparticles form nanoscale composite with MPc.MPc-Fe3O4 nanoparticles composite have high long term stability.

  1. Two-stage nuclear refrigeration with enhanced nuclear moments

    Experiments are described in which an enhanced nuclear system is used as a precoolant for a nuclear demagnetisation stage. The results show the promising advantages of such a system in those circumstances for which a large cooling power is required at extremely low temperatures. A theoretical review of nuclear enhancement at the microscopic level and its macroscopic thermodynamical consequences is given. The experimental equipment for the implementation of the nuclear enhanced refrigeration method is described and the experiments on two-stage nuclear demagnetisation are discussed. With the nuclear enhanced system PrCu6 the author could precool a nuclear stage of indium in a magnetic field of 6 T down to temperatures below 10 mK; this resulted in temperature below 1 mK after demagnetisation of the indium. It is demonstrated that the interaction energy between the nuclear moments in an enhanced nuclear system can exceed the nuclear dipolar interaction. Several experiments are described on pulsed nuclear magnetic resonance, as utilised for thermometry purposes. It is shown that platinum NMR-thermometry gives very satisfactory results around 1 mK. The results of experiments on nuclear orientation of radioactive nuclei, e.g. the brute force polarisation of 95NbPt and 60CoCu, are presented, some of which are of major importance for the thermometry in the milli-Kelvin region. (Auth.)

  2. Capturing Guest Dynamics in Metal-Organic Framework CPO-27-M (M = Mg, Zn) by (2)H Solid-State NMR Spectroscopy.

    Xu, Jun; Sinelnikov, Regina; Huang, Yining

    2016-06-01

    Metal-organic frameworks (MOFs) are promising porous materials for gas separation and storage as well as sensing. In particular, a series of isostructural MOFs with coordinately unsaturated metal centers, namely, CPO-27-M or M-MOF-74 (M = Mg, Zn, Mn, Fe, Ni, Co, Cu), have shown exceptional adsorption capacity and selectivity compared to those of classical MOFs that contain only fully coordinated metal sites. Although it is widely accepted that the interaction between guest molecules and exposed metal centers is responsible for good selectivity and large maximum uptake, the investigation of such guest-metal interaction is very challenging because adsorbed molecules are usually disordered in the pores and undergo rapid thermal motions. (2)H solid-state NMR (SSNMR) spectroscopy is one of the most extensively used techniques for capturing guest dynamics in porous materials. In this work, variable-temperature (2)H wide-line SSNMR experiments were performed on CPO-27-M (M = Mg, Zn) loaded with four prototypical guest molecules: D2O, CD3CN, acetone-d6, and C6D6. The results indicate that different guest molecules possess distinct dynamic behaviors inside the channel of CPO-27-M. For a given guest molecule, its dynamic behavior also depends on the nature of the metal centers. The binding strength of guest molecules is discussed on the basis of the (2)H SSNMR data. PMID:27183247

  3. Density functional theory study of the effects of alloying additions on sulfur adsorption on nickel surfaces

    Highlights: ► We study sulfur adsorption on metal doped and undoped Ni surfaces. ► Hybridization of Ni-3d and S-3p states plays the most important role in the formation of Ni-S bonds. ► Au, Ag, Al, Bi, Cd, Sb, Sn, Zn additions can significantly increase sulfur tolerance of Ni. ► Sn, Sb, and Bi alloying additions have the strongest effects on sulfur adsorption. - Abstract: Reactions of hydrogen sulfide (H2S) with Nickel/Ytrria-doped zirconia (Ni/YDZ) anode materials might cause degradation of the performance of solid oxide fuel cells when S containing fuels are used. In this paper, we employ density functional theory to investigate S adsorption on metal (M)-doped and undoped Ni(0 0 1) and Ni(1 1 1) surfaces. Based on the performed calculations, we analyze the effects of 12 alloying additions (Ag, Au, Al, Bi, Cd, Co, Cu, Fe, Sn, Sb, V, and Zn) on the temperature of transition between clean (S atoms do not adsorb on the surfaces) and contaminated (S atoms can adsorb on the surfaces spontaneously) M-doped Ni surfaces for different concentrations of H2S in the fuel. Predicted results are consistent with many experimental studies relevant to S poisoning of both Ni/YDZ and M-doped Ni/YDZ anode materials. This study is important to understand S poisoning phenomena and to develop new S tolerant anode materials.

  4. Mineral supplementation for grazing ruminants

    Grazing ruminants to which concentrate feeds cannot be economically fed must rely on self-feeding of mineral supplements. A number of factors affect mineral consumption of free-choice mixtures. Livestock exhibit little nutritional wisdom and will select palatable mixtures in preference to mixtures designed to meet their requirements. Palatability and appetite stimulators are often used to achieve a more uniform herd-wide consumption. It is best to formulate free-choice mixtures on the basis of analyses or other available data. However, when no information on mineral status is known, a free-choice complete mineral supplement is warranted. A 'complete' mineral mixture usually includes salt, a low fluoride P source, Ca, Co, Cu, I, Mn and Zn. Selenium, Mg, K, S, Fe or additional elements can be incorporated into a mineral supplement as new information suggests a need. The detriment to ruminant production caused by providing Ca, Se and Cu in excess can be greater than any benefit derived by providing a mineral supplement. In regions where high forage Mo predominates, three to five times the Cu content in mineral mixtures is needed to counteract Mo toxicity. Supplemental minerals are most critical during the wet season, when cattle are gaining weight rapidly and energy and protein supplies are adequate. Economic return on mineral supplementation is high. (author)

  5. Characterization of ancient glass excavated in Enez (Ancient Ainos) Turkey by combined Instrumental Neutron Activation Analysis and Fourier Transform Infrared spectrometry techniques

    Ancient glass fragments excavated in the archaeological district Enez (Ancient Ainos)–Turkey were investigated by combined Instrumental Neutron Activation Analysis (INAA) and Fourier Transform Infrared (FTIR) spectrometry techniques. Multi-elemental contents of 15 glass fragments that belong to Hellenistic, Roman, Byzantine, and Ottoman Periods, were determined by INAA. The concentrations of twenty six elements (Na, K, Ca, Sc, Cr, Mn, Fe, Co, Cu, Zn, As, Rb, Sr, Sb, Cs, Ba, Ce, Sm, Eu, Tb, Yb, Lu, Hf, Ta, Au and Th), which might be present in the samples as flux, stabilizers, colorants or opacifiers, and impurities, were examined. Chemometric treatment of the INAA data was performed and principle component analysis revealed presence of 3 distinct groups. The thermal history of the glass samples was determined by FTIR spectrometry. - Highlights: ► INAA was performed to determine elemental compositions of ancient glass fragments. ► Basic, coloring/discoloring elements and impurities have been determined. ► PCA discriminated the glasses depending on their chronological order. ► The thermal history of the glass samples was determined by FTIR spectrometry.

  6. Effects of alloying elements on elastic properties of Al by first-principles calculations

    Wang J.

    2014-01-01

    Full Text Available The effects of alloying elements (Co, Cu, Fe, Ge, Hf, Mg, Mn, Ni, Si, Sr, Ti, V, Y, Zn, and Zr on elastic properties of Al have been investigated using first-principles calculations within the generalized gradient approximation. A supercell consisting of 31 Al atoms and one solute atom is used. A good agreement is obtained between calculated and available experimental data. Lattice parameters of the studied Al alloys are found to be depended on atomic radii of solute atoms. The elastic properties of polycrystalline aggregates including bulk modulus (B, shear modulus (G, Young’s modulus (E, and the B/G ratio are also determined based on the calculated elastic constants (cij’s. It is found that the bulk modulus of Al alloys decreases with increasing volume due to the addition of alloying elements and the bulk modulus is also related to the total molar volume (Vm and electron density (nAl31x with the relationship of nAl31x=1.0594+0.0207√B/Vm. These results are of relevance to tailor the properties of Al alloys.

  7. Systematic B-metal substitution in CaNi5

    Jensen, Jens Oluf; Bjerrum, Niels

    The aim of this work has been to study the effect of B metal substitutions in CaNi5 (AB(5)) which is known to suffer from poor cycling stability as a hydride electrode material. Systematic monosubstitutions of nickel with the most common other B metals (i.e. Al, Cr, Mn, Fe, Co, Cu, Zn and Sn) and...... Mg were performed. The overall composition was in all cases CaNi5-xMx (x=0.5 or 1) where M is the substituting element. The alloys were prepared by mechanical alloying. The hydrogen storage capacity was measured electrochemically ranging from 39 to 390 mAh/g, but none of the substitutions increased...... the cycling stability to any significant extend compared to pure CaNi5. X-ray diffraction patterns of the alloys revealed that only in a few cases the hexagonal CaCu5 structure of a true AB(5) alloy was preserved. In most cases diffraction patterns matching Ca2Ni7, CaNi3 or CaNi2 were seen. It can be...

  8. Application of instrumental neutron activation analysis to plant medicines in Ghana. A review

    Some essential elements in eleven plant medicines used at the Center for Scientific Research into Plant Medicine (CSRPM), Mampong-Akwapim, Ghana, for the management and cure of various diseases were determined by instrumental neutron activation analysis (INAA), using thermal neutrons at a flux of 5 x 1011 n x s-1 x cm-2. The plant medicines were: Sirappac powder-E, Tina-A powder, Blighia powder, Aphrodisiac powder, Ninga powder and Lippia tea. The others are Olax powder, Ritchiea powder, Momordica powder, Kenken and Fefe powder. Concentrations of seventeen elements namely Al, Br, Ca, Cl, Co, Cu, Cr, K, Mn, Mg, Na, Rb, Sb, Sc, Ta, V, and Zn have been determined by short, medium and long irradiation times. Of these elements Co, Sb, and Sc are found to be present at the trace level, Br, Cu, Cr, Mn, Rb, Ta, V and Zn at the minor level, while Al, Ca, Cl, K, Mg and Na were generally at major level. The differences in the concentration of the elements are attributed mainly to soil composition and climate in which the plants grow. Standard reference material NIST SRM-1571 (Orchard Leaf) was analyzed simultaneously with the samples. The precision and accuracy of the method were evaluated using real samples and the standard reference material. It was found that the elemental concentrations measured in the NIST SRM-1571 were within ±10% of the reported values. The importance of these elements as related to human health and nutrition has been discussed. (author)

  9. Evaluation of the availability of heavy metals in lake sediments using SR-TXRF

    de Vives, Ana Elisa Sirito; Brienza, Sandra Maria Boscolo; Moreira, Silvana; Zucchi, Orghêda Luiza Araújo Domingues; Barroso, Regina Cely; do Nascimento Filho, Virgilio Franco

    2007-08-01

    The analytical technique Synchrotron Radiation Total Reflection X-ray Fluorescence (SR-TXRF) was used to evaluate the contamination and bioavailability of heavy metals in samples of sediment collected at different depths. The samples were collected in one of the lakes located next to ceramic industries in Santa Gertrudes, São Paulo state in the southwest region of Brazil during the rainy season. In order to determine the concentration of bioavailable metals (mobile fraction) and metals that are representative of the geological matrix (residual fraction) in sediment samples, procedures of acid extraction were implemented. All measurements were carried out in the Synchrotron Light Source Laboratory (LNLS), located in Campinas, São Paulo state. For sample excitation, a polychromatic beam of approximately 2 mm (width) and 0.3 mm (height) was used, and for the detection of the characteristic X-rays produced, a Si(Li) detector was employed. The net areas of the X-ray peaks were obtained from the program (Quantitative X-ray Analysis System; QXAS). The elements V, Cr, Co, Cu, Zn and Pb, which are considered to cause higher environmental damage, showed high availability. The concentrations of these elements are above the reference values which correspond to soil protection and underground water quality of São Paulo state. The concentrations obtained indicate that the area in study is contaminated.

  10. Association Analysis of SSR Markers with Phenology, Grain, and Stover-Yield Related Traits in Pearl Millet (Pennisetum glaucum (L. R. Br.

    Baskaran Kannan

    2014-01-01

    Full Text Available Pearl millet is a staple food crop for millions of people living in the arid and semi-arid tropics. Molecular markers have been used to identify genomic regions linked to traits of interest by conventional QTL mapping and association analysis. Phenotypic recurrent selection is known to increase frequencies of favorable alleles and decrease those unfavorable for the traits under selection. This study was undertaken (i to quantify the response to recurrent selection for phenotypic traits during breeding of the pearl millet open-pollinated cultivar “CO (Cu 9” and its four immediate progenitor populations and (ii to assess the ability of simple sequence repeat (SSR marker alleles to identify genomic regions linked to grain and stover yield-related traits in these populations by association analysis. A total of 159 SSR alleles were detected across 34 selected single-copy SSR loci. SSR marker data revealed presence of subpopulations. Association analysis identified genomic regions associated with flowering time located on linkage group (LG 6 and plant height on LG4, LG6, and LG7. Marker alleles on LG6 were associated with stover yield, and those on LG7 were associated with grain yield. Findings of this study would give an opportunity to develop marker-assisted recurrent selection (MARS or marker-assisted population improvement (MAPI strategies to increase the rate of gain for pearl millet populations undergoing recurrent selection.

  11. Application of the sanderson polar covalence model to energetics of CO adsorption

    Frese, Karl W.

    1988-08-01

    The model of polar covalence developed by R.T. Sanderson was used to calculate energies of chemisorption of CO g on metal surfaces. Internal energies of adsorption were calculated for four stereochemical possibilities including linear, two site bridge bonded, and dissociated CO on fourteen first, second, and third row transition metals. The influence of surface steps, other defects, and CO-CO interactions were not calculated, although the influence of steps on certain metals is discussed. The effect of metal site coordination number was also calculated. Higher coordination numbers, are generally associated with longer bond lengths and smaller heats of adsorption. Very good agreement, less than 3 kcal mol -1 difference between experiment and calculation, was observed for molecularly adsorbed CO. The enthalpy and Gibbs energy of dissociative adsorption at 298 K were calculated for seventeen transition metals and Si. CO dissociation is thermodynamically allowed on Mn, Cr, Fe, Ni, Re, W and Si at both 10 -10 Torr and 1 atm CO. Dissociation is forbidden on Ru, Rh, Ir, Ag, Pd, Au, and Pt at both pressures. Dissociation is forbidden at 10 -10 Torr, but allowed at 1 atm CO on Co, Cu, Mo, and Os.

  12. A thermodynamic model of nickel smelting and direct high-grade nickel matte smelting processes: Part I. Model development and validation

    Tan, Pengfu; Neuschütz, Dieter

    2001-04-01

    A thermodynamic model has been developed to predict the distribution behavior of Ni, Cu, Co, Fe, S, As, Sb, and Bi in the Outokumpu flash-smelting process, the Outokumpu direct high-grade matte smelting process, and the INCO flash-smelting process. In this model, as many as 16 elements (Ni, Cu, Co, Fe, As, Sb, Bi, S, O, Al, Ca, Mg, Si, N, C, and H) are considered, and two nickel sulfide species are used to allow for modeling of sulfur-deficient mattes. The compositions of the matte, slag, and gaseous phases in equilibrium are calculated using Gibbs free energies of formation and the activity coefficients of the components derived from the experimental data. The model predictions are compared with the known industrial data from the Kalgoorlie Nickel Smelter (Kalgoorlie, Australia), the Outokumpu Harjavalta Nickel Smelter (Harjavalta, Finland), the INCO Metals Company (Sudbury, Canada), and from a number of experimental data. An excellent agreement is obtained. It was found that the distribution behaviors of Ni, Co, Cu, Fe, S, As, Sb, and Bi in the nickel smelting furnace depend on process parameters such as the smelting temperature, matte grade, and partial pressure of oxygen in the process.

  13. Alloying behavior of Ni3M-type GCP compounds

    The site preference of ternary additions in Ni3M-type GCP compounds was determined from the direction of solubility lobe of the GCP phase on the ternary phase diagram that have been experimentally reported. In Ni3Nb (D0a), Co and Cu preferred the substitution for Ni-site, Ti, V and W the substitution for Nb-site, and Fe the substitution for both sites. In Ni3V (D022), Co preferred the substitution for Ni-site, Cr the substitution for both sites, and Ti the substitution for V-site. In Ni3Ti (D024), Fe, Co, Cu, and Si preferred the substitution for Ni-site, Nb, Mo and V the substitution for Ti-site. The thermodynamic model, which was based on the change in total bonding energy of the host compound by a small addition of ternary solute, was applied to predict the site preference of ternary additions. The bond energy of each nearest neighbor pair used in the thermodynamic calculation was derived from the heat of compound formation by Miedema's formula. The agreement between the thermodynamic model and the result of the literature search was excellent. From both experimental and theoretical results, it was shown in three Ni3M-type GCP compounds that both transition and B-subgroup elements have two possibilities, i.e., the case of substitution for Ni-site or the case for M-site, depending on the relative value of two interaction energies.

  14. Synthesis of Multimetal-Graphene Composite by Mechanical Milling

    Saiphaneendra, Bachu; Srivastava, Avi Krishna; Srivastava, Chandan

    2016-06-01

    Multimetal-graphene composites were synthesized using the ball milling technique. To prepare the composite, graphite powder was mixed with Fe, Cr, Co, Cu and Mg powders. This mixture was then mechanically milled for 35 h in toluene medium. After milling, the multimetal-graphite mixture was mixed with sodium lauryl sulfate and sonicated for 2 h. Sonication led to the exfoliation of graphene sheets. Formation of graphene was confirmed from x-ray diffraction and Raman spectroscopy. Transmission electron microscopy-based analysis revealed the formation of multimetal deposits over the graphene surface. Compositional analysis of the multimetal deposits revealed fairly uniform distribution of all the five component metal atoms over the graphene sheet. The average composition of the multimetal deposit was determined to be 11.4 ± 4 at.% Mg, 33.8 ± 19 at.% Cr, 21.8 ± 16 at.% Fe, 9.4 ± 5.7 at.% Co and 23.6 ± 12 at.% Cu.

  15. Participation of the IPEN/CNEN/SP Environmental Diagnostic Division on programs of laboratory intercomparisons in environmental samples; Participacao da Divisao de Diagnostico Ambiental do IPEN/CNEN/SP em programas de intercomparacao laboratoriais em amostras ambientais

    Cotrim, Marycel Barboza; Sato, Ivone Mulako; Salvador, Vera Lucia R.; Dantas, Elizabeth Sonoda Keiko; Cantagallo, Maria Ines; Lemes, Marcos Jose L.; Scapin, Marcos Antonio; Sisti, Cristina; Silveira, Elias Santana; Furusawa, Helio Akira; Pires, Maria Aparecida Faustino [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], e-mail: mecotrim@ipen.br, e-mail: imsato@ipen.br, e-mail: vsalvado@ipen.br, e-mail: esdantas@ipen.br, e-mail: cantagal@ipen.br, e-mail: mjllemes@ipen.br, e-mail: helioaf@ipen.br, e-mail: mapires@ipen.br

    2003-07-01

    The present work presents the participation of the Environmental Diagnostic Division Laboratories (MQA) at the intercomparison national and international laboratories, (PI/SABESP - Interlaboratory Sao Paulo, Brazil, Program; Program for Interlaboratorial Analytic Quality Control of Metals in Water (CBM/COMETRO); Programa para La Calidad de las Mediciones Quimicas (PCQM/INTI) - Argentine, and the Commission d'Etablissement des Methodes d'Analyse, France (CETAMA/CEA). Those essay providers have using statistical tests such as the t-Student, Zscore and Cochran and Grubbs for the data evaluations. The obtained results are presented involving the analytical such as atomic absorption spectrometry: flame, graphite oven and hydride generation (AAS), emission spectrometry with induced plasma (ICP-OES), X-ray fluorescence WD-XRFS), ion chromatography and voltametry (VRA). The elements such as B, Al, K, Mg, Ca, Cr, Fe, Co, Cu, Zn and Pb, and the anions such as Cl-, NO{sub 3}{sup -}, SO{sub 4}{sup 2-} and F{sup -}, were determined at trace level (mgL{sup -1}), and the elements such as Cr, As, Cd, Pb e Hg, at the trace level ({mu}gL{sup -1}) in water matrices. The evaluation of analytical results, in the period 1997 to 2002, demonstrate a continuous improvement evidencing the importance of Laboratories participation at those type of exercises.

  16. Soil amendments for heavy metals removal from stormwater runoff discharging to environmentally sensitive areas

    Trenouth, William R.; Gharabaghi, Bahram

    2015-10-01

    Concentrations of dissolved metals in stormwater runoff from urbanized watersheds are much higher than established guidelines for the protection of aquatic life. Five potential soil amendment materials derived from affordable, abundant sources have been tested as filter media using shaker tests and were found to remove dissolved metals in stormwater runoff. Blast furnace (BF) slag and basic oxygenated furnace (BOF) slag from a steel mill, a drinking water treatment residual (DWTR) from a surface water treatment plant, goethite-rich overburden (IRON) from a coal mine, and woodchips (WC) were tested. The IRON and BOF amendments were shown to remove 46-98% of dissolved metals (Cr, Co, Cu, Pb, Ni, Zn) in repacked soil columns. Freundlich adsorption isotherm constants for six metals across five materials were calculated. Breakthrough curves of dissolved metals and total metal accumulation within the filter media were measured in column tests using synthetic runoff. A reduction in system performance over time occurred due to progressive saturation of the treatment media. Despite this, the top 7 cm of each filter media removed up to 72% of the dissolved metals. A calibrated HYDRUS-1D model was used to simulate long-term metal accumulation in the filter media, and model results suggest that for these metals a BOF filter media thickness as low as 15 cm can be used to improve stormwater quality to meet standards for up to twenty years. The treatment media evaluated in this research can be used to improve urban stormwater runoff discharging to environmentally sensitive areas (ESAs).

  17. Determination of eight trace elements in doped crystal ALN by inductively coupled plasma atomic emission spectrometry

    Complete text of publication follows. In this paper, an accurate and simple method has been developed for the determination of trace Cr, Co, Cu, Fe, Mg, Mn ,Ni and Zn in doped AlN crystal using inductively coupled plasma atomic emission spectrometry (ICP-AES). AlN crystal becomes ideal substrate for the epitaxial growth of GaN, AlGaN with high Al ingredient and AlN which are used to fabricate ultraviolet LEDs, blue- ultraviolet solid state LDs, lasers, ultraviolet detectors. At present, It is a very important aspect for scientific workers to promote in the transition metals elements doped AlN showing ferromagne. Owing its low detection limits and multi-element capability, ICP-AES has been used in many fields.The optimum instrument working conditions are selected .AlN crystal was fused with KOH and the fusion product was dissolved in dilute aqua regia. Matrix effect from KOH and interference to the spectral lines of the elements to be determined were investigated and corrected by matrix matching and background correction method. Detection limits of elements were 0.01% to 0.0002% The recoveries for elements were 98% to 104%. The relative standard deviation was 0.5% to 4.0%.

  18. Simultaneous determination of trace elements in river-water samples by ICP-MS in combination with a discrete microsampling technique after enrichment with a chitosan-based chelating resin

    A new technique for the preconcentration of trace elements and matrix elimination with a chitosan-based chelating resin was proposed as a useful pretreatment prior to a measurement by inductively coupled plasma-mass spectrometry (ICP-MS). A small volume of the sample solution (80 μl) was discretely introduced into a nebulizer of ICP-MS using a segmented flow injection (SFI) system; a maximum of fifteen elements were simultaneously measured by a single injection. A chitosan-based chelating resin containing iminodiacetate (IDA) functional groups was used for matrix elimination and enrichment of analyte metal ions. Several metal ions, such as Al, Fe, Ni, Co, Cu, Zn, Ag, Cd, Pb and U, were quantitatively retained on the IDA chelating resin in a micro-column (resin: 1 ml) at pH 6, whereas Na, K, Mg and Ca were completely eluted from the column by washing with an ammonium acetate solution. The concentrations of 24 and 26 elements in river water certified reference materials, JAC 0031 and JAC 0032, respectively, were determined by the proposed SFI/ICP-MS system after pretreating the samples with the proposed technique, as well as without any pretreatment. The thus-obtained analytical data were evaluated by comparing them with the reference values, as well as with those obtained in other studies. (author)

  19. Determination of trace elements in natural water samples by sir-segmented flow-injection/ICP-MS after preconcentration with a chitosan-based chelating resin

    Ultratrace elements in natural water samples were determined simultaneously by air-segmented flow-injection/inductively coupled plasma-mass spectrometry (SFI/ICP-MS). A small volume of the sample solutions (80 μl) was introduced into a nebulizer by an air-segmented flow-injection (SFI) system, and a maximum of fifteen elements were measured during each run. A chitosan-based chelating resin containing functional groups of iminodiacetate was used to separate and enrich analyte metal ions. A 50-fold preconcentration using 50 ml of sample solutions was achieved by the proposed method, where 1 ml of 0.1 M nitric acid was added to residues after drying the chelating column effluent. At pH 6, several heavy metals (Fe, Ni, Co, Cu, Zn, Ag, Cd, Pb and U) and rare earth elements (REEs) were quantitatively retained on the chelating resin column, whereas alkali and alkaline earth metals were eluted from the column by rinsing with 5 ml of a 0.2 M ammonium acetate solution. Metals adsorbed on the chelating resin column were recovered by elution with 10 ml of 1 M nitric acid. The proposed method was applied to the determination of trace elements in several natural water samples, such as river water and mineral drinking water. (author)

  20. Determination of trace elements in natural water samples by sir-segmented flow-injection/ICP-MS after preconcentration with a chitosan-based chelating resin

    Lee, K.H.; Oshima, Mitsuko; Motomizu, Shoji [Department of Chemistry, Faculty of Science, Okayama University, Okayama (Japan)

    2000-07-01

    Ultratrace elements in natural water samples were determined simultaneously by air-segmented flow-injection/inductively coupled plasma-mass spectrometry (SFI/ICP-MS). A small volume of the sample solutions (80 {mu}l) was introduced into a nebulizer by an air-segmented flow-injection (SFI) system, and a maximum of fifteen elements were measured during each run. A chitosan-based chelating resin containing functional groups of iminodiacetate was used to separate and enrich analyte metal ions. A 50-fold preconcentration using 50 ml of sample solutions was achieved by the proposed method, where 1 ml of 0.1 M nitric acid was added to residues after drying the chelating column effluent. At pH 6, several heavy metals (Fe, Ni, Co, Cu, Zn, Ag, Cd, Pb and U) and rare earth elements (REEs) were quantitatively retained on the chelating resin column, whereas alkali and alkaline earth metals were eluted from the column by rinsing with 5 ml of a 0.2 M ammonium acetate solution. Metals adsorbed on the chelating resin column were recovered by elution with 10 ml of 1 M nitric acid. The proposed method was applied to the determination of trace elements in several natural water samples, such as river water and mineral drinking water. (author)

  1. Simultaneous determination of trace elements in river-water samples by ICP-MS in combination with a discrete microsampling technique after enrichment with a chitosan-based chelating resin

    Lee, K.H.; Oshima, Mitsuko; Takayanagi, Toshio; Motomizu, Shoji [Department of Chemistry, Faculty of Science, Okayama University, Okayama (Japan)

    2000-07-01

    A new technique for the preconcentration of trace elements and matrix elimination with a chitosan-based chelating resin was proposed as a useful pretreatment prior to a measurement by inductively coupled plasma-mass spectrometry (ICP-MS). A small volume of the sample solution (80 {mu}l) was discretely introduced into a nebulizer of ICP-MS using a segmented flow injection (SFI) system; a maximum of fifteen elements were simultaneously measured by a single injection. A chitosan-based chelating resin containing iminodiacetate (IDA) functional groups was used for matrix elimination and enrichment of analyte metal ions. Several metal ions, such as Al, Fe, Ni, Co, Cu, Zn, Ag, Cd, Pb and U, were quantitatively retained on the IDA chelating resin in a micro-column (resin: 1 ml) at pH 6, whereas Na, K, Mg and Ca were completely eluted from the column by washing with an ammonium acetate solution. The concentrations of 24 and 26 elements in river water certified reference materials, JAC 0031 and JAC 0032, respectively, were determined by the proposed SFI/ICP-MS system after pretreating the samples with the proposed technique, as well as without any pretreatment. The thus-obtained analytical data were evaluated by comparing them with the reference values, as well as with those obtained in other studies. (author)

  2. Investigation of the Elemental Contents of Some Samples of Soil, Sediments and Fish from the Blue Nile and the White Nile Around Khartoum Using Atomic Absorption and X- Ray Fluorescence Spectrometry

    This work was performed to evaluate the environmental pollution at the Blue Nile (B.N) and the White Nile (W.N) around Khartoum state. Samples of soil, sediments ( > 63 μm size) and fish were collected from the studied area and analyzed. The concentrations of some elements (K, Ca, Ti, Mn, Fe, Cr, Co, Cu, Ni, Sr, Rb, Zn, Br, Y, Zr, and Pb) were determined using two analytical methods; atomic absorption (AAS) and X- ray fluorescence (XRF) spectrometry. The data was statistically analyzed to compare the results obtained by the two analytical methods. The results of most elements determined by the two methods were significantly similar. Generally, the elemental concentrations of sediments from the BN were higher than the WN. The extent of pollution was determined by calculating the enrichment factors. The enrichment factors in sediments were calculated using both Fe and Ti as reference elements and bulk soil composition as a reference material. Some elements were slightly enriched at some sites but not to a degree to indicate a serious pollution. The elemental concentrations in fish were not that high. We can conclude that the extent of pollution with heavy elements at the B.N and W.N around Khartoum State is not a serious environmental problem so far.(author)

  3. Investigation of the elemental contents of some samples of soil, sediments and fish from the Blue Nile and the White Nile around Khartoum using atomic absorption and x-ray fluorescence spectrometry

    This work was performed to evaluate the environmental pollution at the Blue Nile (B.N) and the White Nile (W.N) around Khartoum State. Samples of soil, sediments (> 63 μm size) and fish were collected from the studied area and analyzed. The concentrations of some elements (K, Ca, Ti, Mn, Fe, Cr, Co, Cu, Ni, Sr, Rb, Zn, Br, Y, Zr, and Pb) were determined using two analytical methods, atomic absorption (AAS) and x-ray fluorescence (XRF) spectrometry. The data was statistically analyzed to compare the results obtained by the two analytical methods. The results of most elements determined by the two methods were significantly similar. Generally, the elemental concentrations of sediments from the B.N were higher than the W N. The extent of pollution was determined by calculating the enrichment factors. The enrichment factors in sediments were calculated using both Fe and Ti as reference elements and bulk soil composition as a reference material. Some elements were slightly enriched at some sites but not to a degree to indicate a serious pollution. The elemental concentrations in fish were not that high. We can conclude that the extent of pollution with heavy elements at the B.N and W.N around Khartoum State is not a serious environmental problem so far. (Author)

  4. Mobility behavior and environmental implications of trace elements associated with coal gangue: a case study at the Huainan Coalfield in China.

    Chuncai, Zhou; Guijian, Liu; Dun, Wu; Ting, Fang; Ruwei, Wang; Xiang, Fan

    2014-01-01

    The potential environmental hazards posed by trace elements have assumed serious proportions due to their toxicity, bioavailability and geochemical behavior. The toxicity and mobility of trace elements in coal gangue is dependent on the elements' chemical properties, therefore, the quantification of the different forms of trace elements is more significant than the estimation of their total concentrations. In this study, the mobility behavior of trace elements in coal gangue from the Huainan Coalfield was studied to evaluate the potential eco-toxicity of the trace elements. Sequential extraction was employed to analyze the fractionation behavior of trace elements in coal gangue. The selected trace elements (As, Co, Cr, Cu, Mn, Ni, Se, Sn, V and Zn) are predominantly found in silicate-bound, sulfide-bound and carbonate-bound fractions. The correlation of the element concentration with ash yield, aluminum, calcium and iron-sulfur indicates that As, Co, Cu, Ni, Se and Zn in coal gangue are mainly associated with sulfide minerals, which could release from coal gangue easily and can disperse into the environment as a result of long-term natural weathering. The Risk Assessment Code reveals that the trace elements (Mn, Cr, Se, Ni, Zn, As and Cu) can pose serious environmental risks to the ecosystem. The fractionation profiles of other elements (Co, Sn and V) indicate no risk or low risk to the environment. PMID:24050719

  5. Analysis of Mineral and Heavy Metal Content of Some Commercial Fruit Juices by Inductively Coupled Plasma Mass Spectrometry

    Adriana Dehelean

    2013-01-01

    Full Text Available The presence of potentially toxic elements and compounds in foodstuffs is of intense public interest and thus requires rapid and accurate methods to determine the levels of these contaminants. Inductively coupled plasma mass spectrometry is a powerful tool for the determination of metals and nonmetals in fruit juices. In this study, 21 commercial fruit juices (apple, peach, apricot, orange, kiwi, pear, pineapple, and multifruit present on Romanian market were investigated from the heavy metals and mineral content point of view by ICP-MS. Our obtained results were compared with those reported in literature and also with the maximum admissible limit in drinking water by USEPA and WHO. For Mn the obtained values exceeded the limits imposed by these international organizations. Co, Cu, Zn, As, and Cd concentrations were below the acceptable limit for drinking water for all samples while the concentrations of Ni and Pb exceeded the limits imposed by USEPA and WHO for some fruit juices. The results obtained in this study are comparable to those found in the literature.

  6. Multiple Prompt Gamma-ray Analysis of Environmental Materials

    The k0-standardization method has been applied and evaluated at Hot Lab. Center, using the prompt gamma ray neutron activation analysis (PGNAA) facility of the Cf-252 neutron source. This method has been designed and calibrated and has proven useful for the analytical purpose. Ten sediment samples of Manzala Lake at the end of Egyptian Nile River were analyzed for elemental contents. Prompt gamma my activation analysis (PGAA) due to neutron capture was carded out using integrated system using 252Cf isotopic neutron source with a flux of 6.16E8 n/cm2.sec. TheK0-prompt gamma activation analysis were determined versus the 1951.1 KeV gamma-my of the 35CI(n,gamma) 36CI reaction as comparator. Validation of thc K0-PGAA or mono standard comparator method was applied in analyzing a standard reference material IAEA (soil-7) which gave a good agreement with literature. A method was set up to estimate high neutron absorbing elements like Cd, Sm and Gd in an environmental samples as well as the light and heavy elements B, Na, Mg, Si, P, S, CI, K, Ca, Sc, Fe, Co, Cu, As, Br and Ba concentrations in EI-Manzala Lake sediment samples. The average concentration values of these elements were calculated

  7. Installation and measurement capacity of 3 x 592 GBq 241Am-Be neutron irradiation cell

    In this study, the installation and measurement capacity of the neutron irradiation system are investigated. First of all an irradiation geometry enabling optimum irradiation was designed for three 241Am-Be sources each of it having 592 GBq activity. Neutron irradiation system was installed after design and optimization of the system including the design of appropriate moderator and shielding were completed. Radiation safety standards of the Neutron Research Laboratory fulfilling the requirements of national regulation were achieved with unique configuration of the shielding materials. In this study the results of qualitative and quantitative detection limits obtained for Na, Al, Cl, K, Ti, V, Mn, Fe, Co, Cu, Zn, Ga, Ge, As, Se, Br, Rb, Sr, Y, Mo, Ru, Ag, Cd, In, Sb, I, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Yb, Lu, Hf, W, Pt, Au, Th and U elements by using the neutron irradiation cell comprising 3 x 592 GBq 241Am-Be isotopic neutron source are presented and discussed. (orig.)

  8. Single-step solubilization of milk samples with N,N-dimethylformamide for inductively coupled plasma-mass spectrometry analysis and classification based on their elemental composition.

    Azcarate, Silvana M; Savio, Marianela; Smichowski, Patricia; Martinez, Luis D; Camiña, José M; Gil, Raúl A

    2015-10-01

    A single-step procedure for trace elements analysis of milk samples is presented. Solubilization with small amounts of dymethylformamide (DMF) was assayed prior to inductively coupled plasma mass spectrometry (ICPMS) detection with a high efficiency sample introduction system. All main instrumental conditions were optimized in order to readily introduce the samples without matrix elimination. In order to assess and mitigate matrix effects in the determination of As, Cd, Co, Cu, Eu, Ga, Gd, Ge, Mn, Mo, Nb, Nd, Ni, Pb, Pr, Rb, Sm, S, Sr, Ta, Tb, V, Zn, and Zr, matrix matching calibration with (103)Rh as internal standard (IS) was performed. The obtained limits of detection were between 0.68 (Tb) and 30 (Zn) μg L(-1). For accuracy verification, certified Skim milk powder reference material (BCR 063R) was employed. The developed method was applied to trace elements analysis of commercially available milks. Principal components analysis was used to correlate the content of trace metals with the kind of milk, obtaining a classification according to adults, baby or baby fortified milks. The outcomes highlight a simple and fast approach that could be trustworthy for routine analysis, quality control and traceability of milks. PMID:26078129

  9. Effect of Zr, V, Nb, Mo, and Ta substitutions on magnetic properties and microstructure of melt-spun SmCo5 magnets.

    Fukuzaki, Tomokazu; Iwane, Hiroaki; Abe, Kazutomo; Doi, Toshihiro; Tamura, Ryuji; Oikawa, Tadaaki

    2014-05-01

    We have investigated effects of metal substitutions on the magnetic properties and microstructure of melt-spun Sm-Co-Cu-Fe-M (M = Zr, V, Nb, Mo, Ta) magnets. We prepared melt-spun ribbons with compositions of Sm(Co1- x Cu x )5Fe0.54- y M y (x = 0.1-0.5, y = 0-0.43, M = Zr, V, Nb, Mo, Ta). For compositions of Sm(Co1- x Cu x )5Fe0.54 (x = 0.1-0.5), coercivity increased with increasing of annealing temperature, and a high coercivity of 17.6 kOe was obtained at a Cu content of x = 0.3. The coercivity was found to increase with increasing melting point of the substitution element. A high coercivity of 24.5 kOe was obtained for a composition of Sm(Co0.7Cu0.3)5Fe0.34Ta0.2. PMID:24753631

  10. Large reduction of the depinning field for a transverse domain wall under application of rf and dc currents

    Metaxas, P. J.; Anane, A.; Cros, V.; Grollier, J.; Deranlot, C.; Petroff, F.; Fert, A.; Ulysse, C.; Faini, G.

    2010-03-01

    A new generation of proposed spintronic devices are based on domain wall (DW) motion (DW-MRAM, DW logic, racetrack memory...). However, reliable depinning of domain walls remains elusive, especially in zero field. Here, we have studied the combined effect of rf and dc currents on the depinning of transverse walls in the soft NiFe layer of a 100 nm wide Co/Cu/NiFe spin valve wire. Using the GMR effect, we ensure that the domain wall is always prepared at the same intrinsic defect and then measure the depinning field for different applied dc and rf currents. Notably, for a narrow range of rf frequencies at around 3GHz, we evidence a strong reduction in the depinning field (from ˜80 Oe to ˜30 Oe). Our results are suggestive of a very efficient resonant depinning effect in our spin valve wire which depends not only on the rf power but also on the polarity and amplitude of the accompanying dc current.

  11. Bioaccumulation of macro- and trace elements by European frogbit (Hydrocharis morsus-ranae L.) in relation to environmental pollution.

    Polechońska, Ludmiła; Samecka-Cymerman, Aleksandra

    2016-02-01

    The aim of present study was to investigate the level of trace metals and macroelements in Hydrocharis morsus-ranae collected from regions differing in the degree and type of pollution. Concentrations of 17 macro- and microelements were determined in roots and shoots of European frogbit as well as in water and bottom sediments from 30 study sites. Plants differed in concentrations of elements and bioaccumulation capacity depending on the characteristics of dominant anthropogenic activities in the vicinity of the sampling site. Shoots of H. morsus-ranae growing in the vicinity of organic chemistry plants and automotive industry contained particularly high levels of Cd, Co, and S. Plants from area close to heat and power plant, former ferrochrome industry and new highway, were distinguished by the highest concentrations of Cr, Cu, and Pb. European frogbit from both these regions contained more Fe, Hg, Mn, Ni, and Zn than plants from agricultural and recreational areas. The concentrations of alkali metals and Co, Fe, and N in H. morsus-ranae were elevated in relation to the natural content in macrophytes irrespectively to their content in the environment. Based on the values of Bioaccumulation and Translocation Factors, European frogbit is an accumulator for Co, Cr, Cu, Fe, K, Mn, Ni, Pb, and Zn and a good candidate for phytoremediation of water polluted with Co, Cu, Hg, K, Mn, and Ni. The amount of Co and Mn removed from water and accumulated in the plant biomass during the vegetation season was considerably high. PMID:26490926

  12. Accumulation of metals in the soil of an overland flow wastewater treatment system.

    Stefanutti, Ronaldo; Packer, Ana Paula; Filho, Bruno Coraucci; Mattiazzo, Maria Emilia; de Figueiredo, Roberto F

    2002-12-01

    Accumulation of Co, Cu, Cr, Mo, Ni, Pb and Zn was evaluated in a soil profile of an overland flow system used for the post-treatment of urban wastewater. A pilot version of the overland flow system received urban wastewater from five up-flow anaerobic filters filled with bamboo (Bambusa tuldoides) rings. The anaerobic effluent was applied as feed over 18 months at rates varying from 7 to 28 L min(-1), to a vegetated slope length covered with Tifton 85 (Cynodon) sp. grass. Soil and plant samples were collected in triplicate from the top to the bottom of the slope. In addition, the soils were sampled at the depths 0-20 and 20-40 cm. The metal concentrations found in the overall system were compared to those obtained in a control area located at the beginning of the slope onto which nothing was applied. A month of monitoring the urban wastewater of Limeira City (São Paulo State, Brazil) showed a drastic change in metals concentration due to the irregular discharge of industrial waste. This irregular discharge introduces Cr, Cu, Ni, Pb and Zn into the system used to treat domestic wastewater. The mass balance indicates the accumulation of metals in the soil and the translocation to the plants; also that they could be evapotranspirated, percolated and discharged. PMID:12509052

  13. Calibration of lichen transplants considering faint memory effects

    Biomonitoring is for more than 20 years now, a tool to study the dispersion of trace elements through the atmosphere and back to earth surface again. A qualitative improvement upon the use of biomonitors is their calibration against more traditional element availability variables like deposition or airborne concentration. Usually it is assumed that a linear regression between biomonitors concentration and availability average values provides a good calibration. In this work, an uptake experiment using transplants of lichen Parmelia sulcata carried out in Portugal during a two years period (1994/96) is described. Nuclear analytical techniques PIXE and INAA were used to analyse lichen and aerosol samples, and ICP-MS was used to analyse total deposition dry residue samples. A database of roughly 70,000 values was created and biomonitor calibration done considering also effects due to non-permanent memory. Data allowed to show, that if annual surveys are made by sampling lichens four times with a period of 3 months in-between sampling campaigns, availability mean, maxima and standard deviation, can be recovered from lichen data for: Al, Si, Cl, Ca, Ti, Fe, Co, Cu, Zn, Zr, Sm, Tb, Hf, Pb, and Th. (author)

  14. Wastewater characterization of IPEN facilities - a preliminary study

    Monteiro, Lucilena R.; Goncalves, Cristina; Terazan, Wagner R.; Cotrim, Marycel E.B.; Pires, Maria Aparecida F., E-mail: lrmonteiro@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    As part of IPEN's Environmental Monitoring Program, wastewater sample collection and analysis was implemented on a daily basis. CQMA- Centro de Quimica e Meio Ambiente was responsible for the determination of total, fixed and volatile solids, pH, metals (as Al, Sb, Ba, Cd, Pb, Co, Cu, Cr, Hg, Mo, Ni, Ag, Na, Zn, Ca, Mg, Be, Sn, Li, K, Sr, Ti and V), semimetals (As, B, Se and Si) and anions (such as chloride, nitrate, sulfate and fluoride). The results were compared to the legal values established by the Sao Paulo State regulation 8,468/76, which defines the maximum permitted values for most of the studied substances in wastewater, aiming its releasing in public wastewater treatment system. The evaluation of this parameters concentration on Ipen's effluent implies that 50% of the wastewater corresponds to organic matter due to the sanitary load and inorganic macro elements, mainly as sodium, potassium, calcium. The only parameter not found in accordance with Brazilian legislation was pH in four out of the one hundred and seven samples collected throughout 2009 (2.8% of the samples analyzed). This preliminary study showed the effluents generated at Ipen's facility is characterized by the presence of organic matter and macro elements, commonly found in sanitary wastewater and it is in compliance with Sao Paulo regulations. (author)

  15. Trace elements and Pb isotopes in soils and sediments impacted by uranium mining.

    Cuvier, A; Pourcelot, L; Probst, A; Prunier, J; Le Roux, G

    2016-10-01

    The purpose of this study is to evaluate the contamination in As, Ba, Co, Cu, Mn, Ni, Sr, V, Zn and REE, in a high uranium activity (up to 21,000Bq∙kg(-1)) area, downstream of a former uranium mine. Different geochemical proxies like enrichment factor and fractions from a sequential extraction procedure are used to evaluate the level of contamination, the mobility and the availability of the potential contaminants. Pb isotope ratios are determined in the total samples and in the sequential leachates to identify the sources of the contaminants and to determine the mobility of radiogenic Pb in the context of uranium mining. In spite of the large uranium contamination measured in the soils and the sediments (EF≫40), trace element contamination is low to moderate (2isotopic signature of the contaminated soils is strongly radiogenic. Measurements performed on the sequential leachates reveal inputs of radiogenic Pb in the most mobile fractions of the contaminated soil. Inputs of low-mobile radiogenic Pb from mining activities may also contribute to the Pb signature recorded in the residual phase of the contaminated samples. We demonstrate that Pb isotopes are efficient tools to trace the origin and the mobility of the contaminants in environments affected by uranium mining. PMID:27220101

  16. Thallium: a potential guide to mineral deposits

    A new method which is rapid and precise has been developed for the determination of Tl in geological materials at the ppb level. About 350 rocks from 4 mineralized areas in northeastern Washington and central Montana were analyzed for Tl by this method. Most of these rocks were also analyzed for SiO2, Al2O3, Fe2O3, MgO, CaO, Na2O, K2O, TiO2, P2O5, MnO, Ag, As, Au, Ba, Co, Cu, F, Li, Mo, Ni, Pb, Sr, Sb, Sn, Sr, Te, U, W, and Zn. The ore deposits of the areas studied include the uranium deposit of the Midnite mine. In all the mineralized areas there is significantly more Tl in hydrothermally altered rocks than in unaltered rocks. The very high abundance of Tl in the altered rocks of the North Moccasin gold district, and the significant positive correlations of Tl and K and Tl and Rb in the mineralized rocks of the other three areas suggest that Tl was concentrated in hydrothermal fluids. In altered rocks the average K/Rb and K/Tl ratios are lower, and the Rb/Sr and Tl/Sr ratios are higher. (orig.)

  17. Trace metal analysis in sea grasses from Mexican Caribbean Coast by particle induced X-ray emission (PIXE)

    The growing urban and tourist activity in the Mexican Caribbean coasts has resulted in an increase of chemical substances, metals in particular, discharged to the coastal waters. In order to reach an adequate management and conservation of these marine ecosystems it is necessary to perform an inventory of the actual conditions that reflect the vulnerability and the level of damage. Sea-grasses are considered good biological indicators of heavy metal contamination in marine systems. The goal of this preliminary work is to evaluate the concentrations of trace metals such as Cr, Mn, Fe, Co, Cu, Zn, and Pb in Thalassia testudinum, a very common sea-grass in the Mexican Caribbean Sea. Samples were collected from several locations in the coasts of the Yucatan Peninsula: Holbox, Blanquizal and Punta Allen, areas virtually uninfluenced by anthropogenic activities. Trace elements in different part plants were determined by particle induced X-ray emission (PIXE). This is a very suitable technique since it offers a fast, accurate and multi-element analysis. Also, the analysis by PIXE can be performed directly on powdered leaves without a laborious sample preparation. The trace metal concentration determined in sea-grasses growing in Caribbean generally fall in the range of the lowest valuables reported for sea grasses from the Gulf of Mexico. The results indicate that the studied areas do not present contamination by heavy metals. (Author)

  18. Palladium, platinum, rhodium, iridium and ruthenium in chromite- rich rocks from the Samail ophiolite, Oman.

    Page, N.J.; Pallister, J.S.; Brown, M.A.; Smewing, J.D.; Haffty, J.

    1982-01-01

    30 samples of chromitite and chromite-rich rocks from two stratigraphic sections, 250 km apart, through the basal ultramafic member of the Samail ophiolite were spectrographically analysed for platinum-group elements (PGE) and for Co, Cu, Ni and V. These data are reported as are Cr/(Cr + Al), Mg/(Mg + Fe) and wt.% TiO2 for most samples. The chromitite occurs as pods or lenses in rocks of mantle origin or as discontinuous layers at the base of the overlying cumulus sequence. PGE abundances in both sections are similar, with average contents in chromite-rich rocks: Pd 8 ppb, Pt 14 ppb, Rh 6 ppb, Ir 48 ppb and Ru 135 ppb. The PGE data, combined with major-element and petrographic data on the chromitite, suggest: 1) relatively larger Ir and Ru contents and highest total PGE in the middle part of each section; 2) PGE concentrations and ratios do not correlate with coexisting silicate and chromite abundances or chromite compositions; 3) Pd/PGE, on average, increases upward in each section; 4) Samail PGE concentrations, particularly Rh, Pt and Pd, are lower than the average values for chromite-rich rocks in stratiform intrusions. 2) suggests that PGEs occur in discrete alloy or sulphide phases rather than in the major oxides or silicates, and 4) suggests that chromite-rich rocks from the oceanic upper mantle are depleted in PGE with respect to chondrites. L.C.C.

  19. Spontaneous incorporation of gold in palladium-based ternary nanoparticles makes durable electrocatalysts for oxygen reduction reaction

    Wang, Deli; Liu, Sufen; Wang, Jie; Lin, Ruoqian; Kawasaki, Masahiro; Rus, Eric; Silberstein, Katharine E.; Lowe, Michael A.; Lin, Feng; Nordlund, Dennis; Liu, Hongfang; Muller, David A.; Xin, Huolin L.; Abruña, Héctor D.

    2016-01-01

    Replacing platinum by a less precious metal such as palladium, is highly desirable for lowering the cost of fuel-cell electrocatalysts. However, the instability of palladium in the harsh environment of fuel-cell cathodes renders its commercial future bleak. Here we show that by incorporating trace amounts of gold in palladium-based ternary (Pd6CoCu) nanocatalysts, the durability of the catalysts improves markedly. Using aberration-corrected analytical transmission electron microscopy in conjunction with synchrotron X-ray absorption spectroscopy, we show that gold not only galvanically replaces cobalt and copper on the surface, but also penetrates through the Pd–Co–Cu lattice and distributes uniformly within the particles. The uniform incorporation of Au provides a stability boost to the entire host particle, from the surface to the interior. The spontaneous replacement method we have developed is scalable and commercially viable. This work may provide new insight for the large-scale production of non-platinum electrocatalysts for fuel-cell applications. PMID:27336795

  20. Synthesis of subnanometer-diameter vertically aligned single-walled carbon nanotubes with copper-anchored cobalt catalysts.

    Cui, Kehang; Kumamoto, Akihito; Xiang, Rong; An, Hua; Wang, Benjamin; Inoue, Taiki; Chiashi, Shohei; Ikuhara, Yuichi; Maruyama, Shigeo

    2016-01-21

    We synthesize vertically aligned single-walled carbon nanotubes (VA-SWNTs) with subnanometer diameters on quartz (and SiO2/Si) substrates by alcohol CVD using Cu-anchored Co catalysts. The uniform VA-SWNTs with a nanotube diameter of 1 nm are synthesized at a CVD temperature of 800 °C and have a thickness of several tens of μm. The diameter of SWNTs was reduced to 0.75 nm at 650 °C with the G/D ratio maintained above 24. Scanning transmission electron microscopy energy-dispersive X-ray spectroscopy (EDS-STEM) and high angle annular dark field (HAADF-STEM) imaging of the Co/Cu bimetallic catalyst system showed that Co catalysts were captured and anchored by adjacent Cu nanoparticles, and thus were prevented from coalescing into a larger size, which contributed to the small diameter of SWNTs. The correlation between the catalyst size and the SWNT diameter was experimentally clarified. The subnanometer-diameter and high-quality SWNTs are expected to pave the way to replace silicon for next-generation optoelectronic and photovoltaic devices. PMID:26690843

  1. Geochemical characteristics of late Quaternary sediments from the southern Aegean Sea (Eastern Mediterranean

    A. SIOULAS

    2012-12-01

    Full Text Available Ten cores from the southern Aegean Sea have been logged for their lithological composition and seventy-three sub-samples were analysed for the determination of major and trace elements concentrations. Four lithological units were identified, namely, mud, volcanic, turbidite and sapropel. On the basis of the “Z-2” Minoan ash layer radiocarbon age sedimentation rates for the southern Aegean Sea were estimated at 3.26 to 4.15 cm kyr -1. Simple correlation analysis revealed three groups of elements associated with: (1 biogenic carbonates; (2 terrigenous alumino-silicates and (3 sapropelic layers. R-mode factor analysis applied on the carbonate-free corrected data-set defined four significant factors: (1 the “detrital alumino-silicate factor” represented by Si, Al, Na, K, Rb, Zr, Pb and inversely related to Ca, Mg, and Sr; (2 a “hydrothermal factor” loaded with Cr, Ni, Co, Cu, Fe; (3 the “volcanic ash factor” with high loadings for Ti, Al, Fe, Na and (4 a “sapropel factor” represented by Ba, Mo, and Zn. High factor scores for the “hydrothermal factor” were observed in sediment samples proximal to Nisyros Isl., suggesting a potential hydrothermal influence. Red-brown oxides and crusts dredged from this area support further this possibility. The use of factor analysis enabled for a better understanding of the chemical elements associations that remained obscured by correlation analysis.

  2. Admittance spectroscopy of CuPC-Si and CoPC-Si heterostructures

    The electronic properties of the interface between n-type Si and metallophthalocyanines (MPcs) have been investigated. Films of MPc (M = Co, Cu), with a thickness of 350 nm, were deposited at room temperature by thermal evaporation and subsequently subjected to heat treatment in air at the temperature range 293–500 K. The variation in the capacitance–voltage (C–V) and conductance–voltage (G–V) characteristics of the Al/MPc/n-Si/Al Schottky barrier devices have been systematically investigated as a function of frequencies in the frequency range of 42 Hz–5 MHz at different temperatures in the range of 210–473 K. The effects of density of interface states (Nss) and series resistance (Rs) on I–V, C–V and G–V characteristics were investigated. The high-frequency capacitance (Cm) and conductance (Gm) values measured under reverse bias were corrected to decrease the effects of series resistance. Those results show that the locations of interface states between n-Si/MPc and series resistance have a significant effect on electrical characteristics of the Al/MpC/n-Si SB devices

  3. NO decomposition in non-reducing atmospheres. Technical progress report, June 1995--August 1995

    Klier, K.; Herman, R.G.; Dedecek, J.

    1995-09-01

    Samples of Mn(II) Nafion, MN(II)-A zeolite, and various Co(II)-ZSM-5 zeolites were prepared by aqueous ion exchange techniques. Co(II)- and Mn(II)-containing ZSM-5, erionite, and mordenite were obtained from other sources. Co(II)-containing samples were studied by diffuse reflectance spectroscopy in the dehydrated state and after exposure to NO atmosphere. In addition, the magnetic susceptibilities of these samples were determined. It was shown that two NO molecules were adsorbed onto each Co(II) ion in ZSM-5 and erionite. The visible spectrum of these materials was complex and contained absorption bands corresponding to Co(II) ions in different coordination states. NO desorbed from Co(II) high silica zeolites at temperatures under 190{degrees}C, while it completely desorbed from Co(II) Nafion below 160{degrees}C. The catalytic activity of Co, Cu, and Mn Nafion samples for NO decomposition was probed, but no activity was observed. Optical absorption and luminescence studies are being initiated with Mn(II)-containing samples.

  4. Utilization of research reactor to the environmental application in Thailand. Air quality study in Saraburi Province, central Thailand

    Saraburi Province is facing difficulties due to high dust generating Industries which is the major economy of the area. Thus, the elemental composition of SPMs in Tumbon Na Phra Lan, Saraburi Province is being monitored. The samples were collected in each quarter from May 2005 to March 2006. Soil as well as fine particles from stacks of some selected manufacturers were also analyzed. The average weight of SPM was found lowest in wet season and highest in the middle of dry season. The average weight of SPM is also high in dry season and low in wet season. The elements found in the samples are Na, Mg, Al, As, Sr, Br, Si, P, S, Cl, K, Ca, Ti, V, Mn, Fe, Co, Cu, and Zn. Calcium is selected as the key elements since most postulated source of pollution is due industrial utilization of the limestone deposit. It is observed that the fine partials form stack are quite low which mean an effective emission control of fine particles form the selected manufacturers. The data is being utilized by the Pollution Control Department, Ministry of Natural Resources and Environment, the environmental authority in Thailand. The authority will use this data to find possible solution for air quality improvement of the area. Future collaboration with environmental authority will be on the study of Thalenoi conservation area in the southern part of Thailand. (author)

  5. Analysis of cathode materials of perovskite structure for solid oxide fuel cells, sofc s

    Fuel cells directly and efficiently convert the chemical energy of a fuel into electrical energy. Of the various types of fuel cells, the solid oxide (Sofc), combine the advantages in environmentally benign energy generation with fuel flexibility. However, the need for high operating temperatures (800 - 1000 grades C) has resulted in high costs and major challenges in relation to the compatibility the cathode materials. As a result, there have been significant efforts in the development of intermediate temperature Sofc (500 - 700 grades C). A key obstacle for operation in this temperature range is the limited activity of traditional cathode materials for electrochemical reduction oxygen. In this article, the progress of recent years is discussed in cathodes for Sofc perovskite structure (ABO3), more efficient than the traditionally used La1-xSrxMnO3-δ (LSM) or (La, Sr) CoO3. Such is the case of mixed conductors (MIEC) double perovskite structure (A A B2O5+δ) using different doping elements as La, Sr, Fe, Ti, Cr, Sm, Co, Cu, Pr, Nd, Gd, dy, Mn, among others, which could improve the operational performance of existing cathode materials, promoting the development of optimized intermediate temperature Sofc designs. (Author)

  6. The application of ion exchange chromatography to the determination of trace elements in manganese compounds, metal and ores

    A method is described in which trace elements are separated from relatively large amounts of manganese by cation exchange chromatography. A two-column operation is used. On a 30 g AG 50W-X8 resin column, elements are adsorbed from a 0.066 M HC1 solution. Hydrochloric acid-acetone solutions of varying concentrations are then used to elute Bi, Cd, Co, Cu(II), Fe(III), Ga, In, Pb, U(VI) and Zn in groups, while manganese is retained. On a 20 g resin column, elements are adsorbed from a solution containing 0.75 M HC1, 90% acetone and 0.05 % H2O2. Manganese is removed by elution with the same solution, while Al, Be, Ca, K, Li, Mg, Na, Ni and Ti(IV) are eluted in a stepwise manner with acidic aqueous solutions. Determination by flame atomic absorption spectrometry or spectrophotometry follows. The method was used successfully for the determination of trace elements in manganese chloride, manganese metal and in three manganese dioxide samples. The relative standard deviation, in general, was lower than 5%. Recoveries from synthetic solutions were better than 94%

  7. Electronic and magnetic properties at rough and sharp transition metal–metal interfaces: An augmented space approach

    Parida, Priyadarshini [Department of Physics and Astronomy, National Institute of Technology, Rourkela 769008 (India); Ganguli, Biplab, E-mail: biplabg@nitrkl.ac.in [Department of Physics and Astronomy, National Institute of Technology, Rourkela 769008 (India); Mookerjee, Abhijit, E-mail: abhijit.mookerjee61@gmail.com [Department of Physics and Materials Science, S.N. Bose National Centre for Basic Sciences, JD-III Salt Lake, Kolkata 700098 (India); Presidency University, College Street, Kolkata (India); Lady Brabourne College, Suhrawardy Avenue, Kolkata (India)

    2015-05-01

    The augmented space formalism (ASF) coupled with recursion method and a tight binding linear muffin-tin orbital basis has been applied to study the layerwise electronic and magnetic properties of (0 0 1) interfaces of body-centered cubic Fe/Ag and face centered cubic Co/Ag, Fe/Cu and Co/Cu. Three different thickness of interfaces are considered: mono, two and three layers of transition metals with metal substrates. Layers of an interface are considered disordered alloys with different degree of disorderedness due to interdiffusion of transition metal layer atoms and substrate atoms during growth process. We show that ASF is applicable to sharp interface also. Result of three layers of transition metal rough interface agrees well with available experimental result. - Highlights: • Study of rough interface of transition metals by augmented space formalism. • Same formalism is extended for nearly sharp interface. • Comparison is made for smooth, 1 layer and 4 layers roughed surfaces. • Layerwise magnetic moments and electronic properties are studied. • Rough interface with 3 layers of transition metals agrees with experiment.

  8. Environmental monitoring of the area surrounding oil wells in Val d'Agri (Italy): element accumulation in bovine and ovine organs.

    Miedico, Oto; Iammarino, Marco; Paglia, Giuseppe; Tarallo, Marina; Mangiacotti, Michele; Chiaravalle, A Eugenio

    2016-06-01

    In this work, environmental heavy metal contamination in the Val d'Agri area of Southern Italy was monitored, measuring the accumulation of 18 heavy metals (U, Hg, Pb, Cd, As, Sr, Sn, V, Ni, Cr, Mo, Co, Cu, Zn, Ca, Mn, Fe, and Al) in the organs of animals raised in the surrounding area (kidney, lung, and liver of bovine and ovine species). Val d'Agri features various oil processing centers which are potentially a significant source of environmental pollution, making it essential to perform studies that will outline the state of the art on which any recovery plans and interventions may be developed. The analysis was carried out using official and accredited analytical methods based on inductively coupled plasma mass spectrometry, and the measurements were statistically processed in order to give a contribution to risk assessment. Even though five samples showed Pb and Cd concentrations above the limits defined in the European Commission Regulation (EC) No 1881/2006, the mean concentrations of most elements suggest that contamination in this area is low. Consequently, these results also suggest that there is no particular risk for human exposure to toxic trace elements. Nevertheless, the findings of this work confirm that element accumulation in ovine species is correlated with geographical livestock area. Therefore, ovine-specific organs might be used as bioindicators for monitoring contamination by specific toxic elements in exposed areas. PMID:27165602

  9. Movement of magnetic domain walls induced by single femtosecond laser pulses

    Sandig, O.; Shokr, Y. A.; Vogel, J.; Valencia, S.; Kronast, F.; Kuch, W.

    2016-08-01

    We present a microscopic investigation of how the magnetic domain structure in ultrathin films changes after direct excitation by single ultrashort laser pulses. Using photoelectron emission microscopy in combination with x-ray magnetic circular dichroism in the resonant absorption of soft x rays, we find that individual laser pulses of ≈60 fs duration and a central wavelength of 800 nm lead to clear changes in the domain structure of a Co layer of three atomic monolayers thickness in an epitaxial Co/Cu/Ni trilayer on a Cu(001) single-crystal substrate. A relatively small enhancement of the sample base temperature by 40 K is sufficient to lower the threshold of laser fluence for domain wall motion by about a factor of two. Pump-probe measurements with a laser fluence just below this threshold indicate that the laser-induced demagnetization of the sample is far from complete in these experiments. Although the domain wall motion appears similar to thermal domain wall fluctuations, quantitatively it cannot be explained by pure thermal activation of domain wall motion by the transient rise of sample temperature after the laser pulse, but it is likely to be triggered by a laser-induced depinning of domain walls.

  10. Trace elements in a Pliocene-Pleistocene lignite profile from the Afsin-Elbistan field, eastern Turkey

    Karayigit, A.I.; Gayer, R.A.

    2000-01-01

    The authors present the results of proximate and ultimate analyses, mineralogical determination, and trace element analysis of a lignite profile from the Afsin-Elbistan field (eastern Turkey). The lignite, which developed during the Pliocene-Pleistocene transition under freshwater lacustrine conditions, contains white gastropod (Planorbidae) shells composed of calcite and a little aragonite. Other identifiable mineral constituents, analyzed by X-ray powder diffraction, include quartz, pyrite, clay minerals, and rare feldspares. Petrographical studies demonstrate the immature nature of these lignites and very low degree of compaction during diagenesis. The mean concentrations of trace elements in the lignite, determined by inductively coupled plasma mass spectrometry (ICP-MS), show relative enrichment in Mo (avg. 20 ppm), W (avg. 15 ppm) and U (avg. 25 ppm) when compared to the global range for most coals, while the others (Ti, p, Sc, Be, Mn, Co, Cu, Zn, Ga, As, Rb, Sr, Zr, Nb, Cs, Ba, Y, Ta, Tl, Pb, Bi, Th, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu) fall within their global ranges. Many of the trace elements show a good correlation with the ash yield, implying an inorganic affinity. However, Mo and Sr show a negative correlation with the ash yield and are thought to be organically associated. A lack of correlation of U with either the ash yield or the coal sulfur content, together with its relative enrichment, suggests secondary mobility of this element.

  11. Synchrotron radiation X-ray fluorescence analysis on altered mineral muscovite in gold deposit

    TANG Yun-Hui; YUAN Wan-Ming; WANG Li-Hua; HAN Chun-Ming; HUANG Yu-Ying; HE Wei

    2005-01-01

    Synchrotron radiation X-ray fluorescence (SRXRF) microprobe was used to ananlyse altered mineral muscovite and its surrounding feldspar in Yuerya gold deposit. The major, minor and trace elements of the two minerals were detected and analyzed. SRXRF analysis showed that the Yuerya muscovite had a complex chemical composition, containing K, Fe, Ca, Ti, Cr, Mn, Co, Cu, Zn and many trace or ultra-trace elements. Since muscovite resulted from the alteration of hydrothermal ore fluid acting on feldspar (plagioclase), the difference of chemical composition between the two minerals shows the components of ore fluid, which are characterized by the enrichment of alkaline and alkaline-earth metal elements K, Ca and ore-associated elements Fe, Cu, Zn. And gold, silver and platinum, invisible under microscope, were detected in some areas of muscovite, but not found in feldspar. Especially platinum, a mantle material, is rarely seen in the earth crust but now found in the gold deposit of magmatic sources; its appearance approves the idea of mantle flux participating in the gold mineralization, which suggests that the tectonic event controlling gold mineralization in the Yuerya district is a mantle phenomenon.

  12. Metal and metalloid contamination in roadside soil and wild rats around a Pb-Zn mine in Kabwe, Zambia

    Metal (Cr, Co, Cu, Zn, Cd, Pb, Ni) and metalloid (As) accumulation was studied in roadside soil and wild rat (Rattus sp.) samples from near a Pb-Zn mine (Kabwe, Zambia) and the capital city of Zambia (Lusaka). The concentrations of the seven metals and As in the soil samples and Pb in the rat tissue samples were quantified using atomic absorption spectroscopy. The concentrations of Pb, Zn, Cu, Cd, and As in Kabwe soil were much higher than benchmark values. Geographic Information System analysis indicated the source of metal pollution was mining and smelting activity. Interestingly, the area south of the mine was more highly contaminated even though the prevailing wind flow was westward. Wild rats from Kabwe had much higher tissue concentrations of Pb than those from Lusaka. Their body weight and renal Pb levels were negatively correlated, which suggests that mining activity might affect terrestrial animals in Kabwe. - The area around Kabwe, Zambia is highly polluted with metals and As. Wild rats from this area had high tissue concentrations of Pb and decreased body weight.

  13. Multiple effects of trace elements on methanogenesis in a two-phase anaerobic membrane bioreactor treating starch wastewater.

    Yu, Dawei; Li, Chao; Wang, Lina; Zhang, Junya; Liu, Jing; Wei, Yuansong

    2016-08-01

    For enhancing anaerobic membrane bioreactor (AnMBR) treating food processing wastewater due to speed-limited methanogenesis step, multiple effects of trace element (TE) supplementation on methanogenesis of a two-phase AnMBR were firstly investigated in batch tests. TE supplementation included individual element, combination and recovery of Fe, Ni, Co, Cu and Zn supplementation. Multiple effects of TE supplementation were highest stimulated by 22.4 ± 5.6 % (TE313) for chemical oxygen demand (COD) removal, 43.1 ± 12.5 % (TE303) for specific methanogenic activity (SMA) and 13.9 ± 3.7 % (TE405) for biomass growth, respectively, although only 7.5 ± 0.6 % (TE106) for methane production. Dosage of TEs played a critical role in methane production, COD removal and biomass growth of the AnMBR's methanogenesis. Low dosages of TE supplementation improved the COD removal and slightly stimulated the COD bioconverting to methane and biomass, but their specific methanation activities were inhibited in the initial rapid methanogenesis stage. Several methanation functional species were increased in abundance like Methanosarcina and Methanoculleus. PMID:26879957

  14. Heavy metals levels in muscle, gonads and gills of Brazilian fishes using SRTXRF

    This work evaluated heavy metals levels in selected tissues of G. brasiliensis, O. hepsetus, H. luetkeni and H. affinis collected at the Paraiba do Sul River, Brazil. The muscle analysis was performed to evaluate the possible transfer of heavy metals to human beings through fish consumption; gonads were used to study the possible transfer and/or influence of metals, through the reproductive processes, to later generations of fishes; and gills are considered the primary action site for most metals, which are absorbed through fish breathing and/or ionic exchanges. The digestion procedure of samples was performed with HNO3 65% in Teflon bombs, with heating at about 120 deg C. The analysis, using Total Reflection X-Ray Fluorescence with Synchrotron Radiation (SRTXRF), was performed at the LNLS (Brazilian Synchrotron Light Laboratory) using white beam and a Si(Li) detector with resolution of 165 eV. The elements identified were: Ti, Cr, Mn, Fe, Co, Cu, Zn, Rb, Sr, Ba and Pb. Fe and Zn exhibited the highest concentrations in the four species investigated. Comparing the results with the Brazilian Food Legislation Cr, Cu, Zn and Pb exceeded the maximum permissible limits in fish tissues. (author)

  15. Soil bacteria for remediation of polluted soils

    Springael, D.; Bastiaens, L.; Carpels, M.; Mergaey, M.; Diels, L.

    1996-09-18

    Soil bacteria, specifically adapted to contaminated soils, may be used for the remediation of polluted soils. The Flemish research institute VITO has established a collection of bacteria, which were isolated from contaminated areas. This collection includes microbacteria degrading mineral oils (Pseudomonas sp., Acinetobacter sp. and others), microbacteria degrading polycyclic aromatic hydrocarbons (genera Sphingomonas and Mycobacterium), microbacteria degrading polychlorobiphenyls (genus Ralstonia and strains related to beta-Proteobacteria), and metal resistant bacteria with plasmid borne resistances to Cd, Zn, Ni, Co, Cu, Hg, and Cr. Bench-scale reactors were developed to investigate the industrial feasibility of bioremediation. Batch Stirred Tank Reactors were used to evaluate the efficiency of oil degraders. Soils, contaminated with non-ferrous metals, were treated using a Bacterial Metal Slurry Reactor. It was found that the reduction of the Cd concentration may vary strongly from sample to sample: reduction factors vary from 95 to 50%. Is was shown that Cd contained in metallic sinter and biologically unavailable Cd could not be removed.

  16. Exploring the link between micro-nutrients and phytoplankton in the Southern Ocean during the 2007 austral summer

    Christel eHassler

    2012-07-01

    Full Text Available Bottle assays and large-scale fertilisation experiments have demonstrated that, in the Southern Ocean, iron often controls the biomass and the biodiversity of primary producers. To grow, phytoplankton need numerous other trace metals (micronutrients required for the activity of key enzymes and other intracellular functions. However, little is known of the potential these other trace elements have to limit the growth of phytoplankton in the Southern Ocean. This study investigates the link between the distribution of several micronutrients (Zn, Co, Cu, Cd, Ni and phytoplankton from samples collected during the SAZ-Sense oceanographic expedition (RV Aurora Australis, Jan.–Feb. 2007. Larger phytoplankton are usually associated with lower diffusive supply and higher micronutrient requirement; for this reason, the delineation between phytoplankton larger than 10 µm and those with a size ranging from 0.8–10 µm was made. In addition, different species of phytoplankton may have different requirements to sustain their growth; the phytoplankton biodiversity here was inferred using biomarker pigments. This study, therefore, attempts to elucidate whether micronutrients other than iron need to be considered as parameters for controlling the phytoplankton growth in the Australian sector of the Southern Ocean. Understanding of the parameters controlling phytoplankton is paramount, as it affects the functioning of the Southern Ocean, its marine resources and ultimately the global carbon cycle.

  17. The contents of fifteen essential trace and toxic elements in some green tea samples and in their infusions

    The content of fifteen elements i.e. Ca, Mg, Na, K, Fe, Mn, Zn, Co, Cu, Cr, Ni, Pd, Cd, Ba and Al were determined for 30 sample from three types of green tea samples using flame atomic absorption spectroscopy. The samples were purchased from authentic tea dealer in Peshawar imported from India, China and Kenya. However, some samples were taken which were locally produced in Pakistan with branded packing and without package. The NBS tea leaves. The wet digestion and infusion procedure reference material was also analyzed simultaneously with tea samples. The wet digestion and infusion procedures were employed for determination of total elements and aqueous extracted elements respectively. It was found that, considerable amount of essential and trace elements are present in total in tea infusion. The levels of toxic metals are low but level of aluminum is high in both forms. The results obtained from this analysis have shown good accuracy and reproducibility. The relative error and relative standard deviation were less than 10% for most of the elements analyzed. (author)

  18. Physiological adaptations in the lichens Peltigera rufescens and Cladina arbuscula var. mitis, and the moss Racomitrium lanuginosum to copper-rich substrate.

    Backor, Martin; Klejdus, Borivoj; Vantová, Ivana; Kovácik, Jozef

    2009-09-01

    Two lichen species (Peltigera rufescens and Cladina arbuscula subsp. mitis) and one moss species (Racomitrium lanuginosum) growing on a copper mine heaps (probably 200-300yr old) in the village of Spania dolina (Slovak Republic) were assessed for selected physiological parameters, including composition of assimilation pigments, chlorophyll a fluorescence, soluble proteins and free amino acid content. The lichen C. arbuscula subsp. mitis was collected also at a control locality where total copper concentration in the soil was approximately 3% that of the waste heaps. Concentrations of Al, Co, Cu, Ni, Sb and Zn were highest in thalli of Peltigera, while the moss Racomitrium contained the highest content of Fe and Pb. Thalli of Cladina contained less metals than the cyanolichen Peltigera, and except for Zn metal concentrations in Cladina from the control locality were lower than in thalli of the same species from copper mine heaps. Regardless of the species or locality, the composition of assimilation pigments and chlorophyll a fluorescence showed that the tested lichens and moss were in good physiological condition and adapted to increased copper levels in the soil. There were significantly different amounts of total free amino acids in Peltigera, Cladina and Racomitrium from the Cu-polluted field. However, differences in amount of free amino acids in control, as well as Cu-polluted thalli of Cladina were less pronounced. PMID:19595434

  19. Transition metal tungstates synthesized by co-precipitation method: Basic photocatalytic properties

    Transition metal tungstates with general formula M2+WO4 (M2+ = Co, Cu, Mn and Ni) were synthesized by the co-precipitation method at 400 °C. The prepared powders were characterized by X-ray powder diffraction (XRD), nitrogen adsorption–desorption isotherms and photoelectrochemical measurements. The quasi-Fermi potentials of electrons determined at pH 7 were −0.67, −0.54, −0.21 and −0.18 V (vs. NHE) for CoWO4, CuWO4, MnWO4 and NiWO4, respectively. Photodegradation of methanol and 4-chlorophenol was used to evaluate the photoactivity of the tungstate oxides under visible-light irradiation. The CuWO4 powders showed the best mineralization yields (about 12% for methanol after 25 h, and 23% for 4-chlorophenol after 6 h of irradiation). These results show the feasibility of organic photocatalytic mineralization using CuWO4.

  20. Risk assessment of particle dispersion and trace element contamination from mine-waste dumps.

    Romero, Antonio; González, Isabel; Martín, José María; Vázquez, María Auxiliadora; Ortiz, Pilar

    2015-04-01

    In this study, a model to delimit risk zones influenced by atmospheric particle dispersion from mine-waste dumps is developed to assess their influence on the soil and the population according to the concentration of trace elements in the waste. The model is applied to the Riotinto Mine (in SW Spain), which has a long history of mining and heavy land contamination. The waste materials are separated into three clusters according to the mapping, mineralogy, and geochemical classification using cluster analysis. Two of the clusters are composed of slag, fresh pyrite, and roasted pyrite ashes, which may contain high concentrations of trace elements (e.g., >1 % As or >4 % Pb). The average pollution load index (PLI) calculated for As, Cd, Co, Cu, Pb, Tl, and Zn versus the baseline of the regional soil is 19. The other cluster is primarily composed of sterile rocks and ochreous tailings, and the average PLI is 3. The combination of particle dispersion calculated by a Gaussian model, the PLI, the surface area of each waste and the wind direction is used to develop a risk-assessment model with Geographic Information System GIS software. The zone of high risk can affect the agricultural soil and the population in the study area, particularly if mining activity is restarted in the near future. This model can be applied to spatial planning and environmental protection if the information is complemented with atmospheric particulate matter studies. PMID:25190539

  1. The effects of phosphorus additions on the sedimentation of contaminants in a uranium mine pit-lake.

    Dessouki, Tarik C E; Hudson, Jeff J; Neal, Brian R; Bogard, Matthew J

    2005-08-01

    We investigated the usefulness of phytoplankton for the removal of surface water contaminants. Nine large mesocosms (92.2m(3)) were suspended in the flooded DJX uranium pit at Cluff Lake (Saskatchewan, Canada), and filled with highly contaminated mine water. Each mesocosm was fertilized with a different amount of phosphorus throughout the 35 day experiment to stimulate phytoplankton growth, and to create a range in phosphorus load (g) to examine how contaminants may be affected by different nutrient regimes. Algal growth was rapid in fertilized mesocosms (as demonstrated by chlorophyll a profiles). As phosphorus loads increased there were significant declines (puranium (p=0.065). The surface water concentrations of Ra-226, Mo, and Se showed no relationship to phosphorus load. Contaminant concentrations in sediment traps suspended at the bottom of each mesocosm generally showed the opposite trend to that observed in the surface water, with most contaminants (As, Co, Cu, Mn, Ni, Ra-226, U, and Zn) exhibiting a significant positive relationship (pphytoremediation has the potential to lower many surface water contaminants through the sedimentation of phytoplankton. Based on our results, we estimate that the Saskatchewan Surface Water Quality Objectives (SSWQO) for DJX pit would be met in approximately 45 weeks for Co, 65 weeks for Ni, 15 weeks for U, and 5 weeks for Zn. PMID:15979684

  2. Multi-elemental contamination and historic record in sediments from the Santos-Cubatao Estuarine System, Brazil

    Luiz-Silva, Wanilson [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Inst. de Geociencias; Machado, Wilson [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Dept. de Geoquimica; Matos, Rosa H.R. E-mail: wanilson@ige.unicamp.br

    2008-07-01

    This paper records for the first time the contamination history and identifies the sources of 38 elements in sediments from the Santos-Cubatao Estuarine System (SE Brazil), at one of the most industrialized areas in Latin America. The compositions of samples from a 260 cm long sediment core collected in the Morrao River estuary were determined by ICP-MS. Enrichment factors, principal component analysis, correlation matrixes, and the characterization of geochemical signatures permitted a consistent data evaluation. Contaminant elements such as Cr, Mn, Ni, Zn, Ga, Ag, Cd, Sn, Sb, Pb, and Bi were associated with steel plant-derived Fe concentrations, while Be, Ca, Sc, Co, Cu, Sr, Y, Zr, Nb, Hf, Ta, Th, and U were associated with fertilizer industry-derived P concentrations. An overlap of sedimentary Fe distribution and local steel plant production indicated that Fe is a reliable marker of the contamination history, allowing the estimation of sedimentation rates over a period of 45 years of industrial activities. (author)

  3. Leaching of Major and Minor Elements during the Transport and Storage of Coal Ash Obtained in Power Plant

    Rada Krgović

    2014-01-01

    Full Text Available In power plant, coal ash obtained by combustion is mixed with river water and transported to the dump. Sequential extraction was used in order to assess pollution caused by leaching of elements during ash transport through the pipeline and in the storage (cassettes. A total of 80 samples of filter ash as well as the ash from active (currently filled and passive (previously filled cassettes were studied. Samples were extracted with distilled water, ammonium acetate, ammonium oxalate/oxalic acid, acidic solution of hydrogen-peroxide, and a hydrochloric acid. Concentrations of the several elements (Al, As, Cd, Co, Cu, Cr, Fe, Ba, Ca, Mg, Ni, Pb, and Zn in all extracts were determined by inductively coupled plasma atomic emission spectrometry. Pattern recognition method was carried out in order to provide better understanding of the nature of distribution of elements according to their origins. Results indicate possible leaching of As, Ca, Cd, Cu, Zn, and Pb. Among these elements As, Cd, and Pb are toxicologically the most important but they were not present in the first two phases with the exception of As. The leaching could be destructive and cause negative effects on plants, water pollution, and damage to some life forms.

  4. Studies in atomic-fluorescence spectroscopy-V The fluorescence characteristics and determination of antimony.

    Dagnall, R M; Thompson, K C; West, T S

    1967-10-01

    Atomic-fluorescence of antimony may be generated in an air-propane flame by nebulizing aqueous solutions of antimony salts whilst irradiating the flame by means of a microwave-excited electrode-less discharge tube operating at 30 W. The strongest fluorescence is exhibited by the (4)S(11 2 ) --> (4)P(1 3 ) 2311 A resonance line and weaker signals are observed at the 2068 and 2176 A resonance lines and at four intercombination lines, at 2598, 2671, 2770 and 2878 A. A process of thermally assisted direct-line fluorescence is postulated to account for the otherwise inexplicable intensity of the 2598 A line emission. Atomic-fluorescence spectroscopy at 2176 A permits the determination of antimony in the range 0.1-120 ppm with a detection limit of 0.05 ppm. With the same equipment and source, the range of measurement for atomic-absorption was 6-120 ppm and the detection limit was 1 ppm. No interferences were observed from 100-fold molar amounts of Cd, Co, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, NH(4), Pb and Zn or from arsenate, chloride, nitrate, phosphate and sulphate. PMID:18960212

  5. Analysis of cathode materials of perovskite structure for solid oxide fuel cells, sofc s; Analisis de materiales catodicos de estructura perovskita para celdas de combustible de oxido solido, sofcs

    Alvarado F, J.; Espino V, J.; Avalos R, L. [Universidad Michoacana de San Nicolas de Hidalgo, Facultad de Ingenieria Quimica, Santiago Tapia 403, Morelia, Michoacan (Mexico)

    2015-07-01

    Fuel cells directly and efficiently convert the chemical energy of a fuel into electrical energy. Of the various types of fuel cells, the solid oxide (Sofc), combine the advantages in environmentally benign energy generation with fuel flexibility. However, the need for high operating temperatures (800 - 1000 grades C) has resulted in high costs and major challenges in relation to the compatibility the cathode materials. As a result, there have been significant efforts in the development of intermediate temperature Sofc (500 - 700 grades C). A key obstacle for operation in this temperature range is the limited activity of traditional cathode materials for electrochemical reduction oxygen. In this article, the progress of recent years is discussed in cathodes for Sofc perovskite structure (ABO{sub 3}), more efficient than the traditionally used La{sub 1-x}Sr{sub x}MnO{sub 3-δ} (LSM) or (La, Sr) CoO{sub 3}. Such is the case of mixed conductors (MIEC) double perovskite structure (A A B{sub 2}O{sub 5+δ}) using different doping elements as La, Sr, Fe, Ti, Cr, Sm, Co, Cu, Pr, Nd, Gd, dy, Mn, among others, which could improve the operational performance of existing cathode materials, promoting the development of optimized intermediate temperature Sofc designs. (Author)

  6. Local structure of nanosized tungstates revealed by evolutionary algorithm

    Nanostructured tungstates, such as CoWO4 and CuWO4, are very promising catalytic materials, particularly for photocatalytic oxidation of water. The high catalytic activity of tungstate nanoparticles partially is a result of their extremely small sizes, and, consequently, high surface-to-volume ratio. Therefore their properties depend strongly on the atomic structure, which differ significantly from that of the bulk material. X-ray absorption spectroscopy is a powerful technique to address the challenging problem of the local structure determination in nanomaterials. In order to fully exploit the structural information contained in X-ray absorption spectra, in this study we employ a novel evolutionary algorithm (EA) for the interpretation of the Co and Cu K-edges as well as the W L3-edge extended X-ray absorption fine structure (EXAFS) of nanosized CoWO4 and CuWO4. The combined EA-EXAFS approach and simultaneous analysis of the W L3 and Co(Cu) K-edge EXAFS spectra allowed us for the first time to obtain a 3D structure model of the tungstate nanoparticles and to explore in details the effect of size, temperature and transition metal type. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Trace element uptake by Eleocharis equisetina (spike rush) in an abandoned acid mine tailings pond, northeastern Australia: Implications for land and water reclamation in tropical regions

    Lottermoser, Bernd G., E-mail: Bernd.Lottermoser@utas.edu.au [School of Earth Sciences, University of Tasmania, Private Bag 79, Hobart, Tasmania 7001 (Australia); Ashley, Paul M. [Earth Sciences, University of New England, Armidale, New South Wales 2351 (Australia)

    2011-10-15

    This study was conducted to determine the uptake of trace elements by the emergent wetland plant species Eleocharis equisetina at the historic Jumna tin processing plant, tropical Australia. The perennial emergent sedge was found growing in acid waters (pH 2.45) and metal-rich tailings (SnAsCuPbZn). E. equisetina displayed a pronounced acid tolerance and tendency to exclude environmentally significant elements (Al, As, Cd, Ce, Co, Cu, Fe, La, Ni, Pb, Se, Th, U, Y, Zn) from its above-substrate biomass. This study demonstrates that geobotanical and biogeochemical examinations of wetland plants at abandoned mined lands of tropical areas can reveal pioneering, metal-excluding macrophytes. Such aquatic macrophytes are of potential use in the remediation of acid mine waters and sulfidic tailings and the reclamation of disturbed acid sulfate soils in subtropical and tropical regions. - Highlights: > In tropical Australia, Eleocharis equisetina grows in an acid mine tailings pond. > Eleocharis equisetina excludes environmentally significant elements from its biomass. > Inspections of equatorial mined lands can reveal metal-excluding aquatic macrophytes. > Such plants are of use in land and water remediation in tropical regions. - The metal-excluding aquatic macrophyte Eleocharis equisetina is of use in land and water remediation in tropical regions.

  8. Multilayer analysis using SIMS: interpretation of profiles at interfaces

    Secondary ion mass spectrometry (SIMS) is a well adapted analytical method for the chemical characterization of concentration profiles in layered or multilayered materials, particularly concerning the more or less abrupt interfaces bounding those layers. It is known that the fiability and accuracy of the interface characterization may be affected by methodological factors, which alter the depth resolution such as: macroscopical or microscopical initial roughness of the substrate and/or of the layers, ion-induced roughening, effects of differential sputtering of the various elements, transitory stage of the primary ion beam implantation, ion beam induced accelerated diffusion, balistic mixing or segregation; etc.. This communication describes several examples of SIMS analysis performed on metal multilayers (Co/Cu) and on epitaxial semiconductor layers (CdTe/GaAs), focussing the interest on the particular analytical problems raised by the initial roughness and the ion induced roughening effect. The interpretation of the measured profiles, the influence of analytical parameters (such as the nature of the primary ion beam, sputtering conditions, detected ion species), and the limitations of profilometry roughness measurements, are discussed. Solutions are proposed in order to improve the depth resolution of interface characterization, including a tentative modelization of roughness effects. (orig.)

  9. Multilayer analysis using SIMS: interpretation of profiles at interfaces. Analyse de couches ou multicouches par SIMS : interpretation du profil aux interfaces

    Aucouturier, M. (CNRS, Labs. de Meudon-Bellevue, 92 Meudon (France)); Grattepain, C. (CNRS, Labs. de Meudon-Bellevue, 92 Meudon (France)); Tromson-Carli, A. (CNRS, Labs. de Meudon-Bellevue, 92 Meudon (France)); Barbe, M. (CNRS, Labs. de Meudon-Bellevue, 92 Meudon (France)); Cohen-Solal, G. (CNRS, Labs. de Meudon-Bellevue, 92 Meudon (France)); Marfaing, Y. (CNRS, Labs. de Meudon-Bellevue, 92 Meudon (France)); Chevrier, F. (CNRS, Labs. de Meudon-Bellevue, 92 Meudon (France)); Gall, H. le (CNRS, Labs. de Meudon-Bellevue, 92 Meudon (France)); Imhoff, D. (CNRS, Labs. de Meudon-Bellevue, 92 Meudon (France))

    1993-11-01

    Secondary ion mass spectrometry (SIMS) is a well adapted analytical method for the chemical characterization of concentration profiles in layered or multilayered materials, particularly concerning the more or less abrupt interfaces bounding those layers. It is known that the fiability and accuracy of the interface characterization may be affected by methodological factors, which alter the depth resolution such as: macroscopical or microscopical initial roughness of the substrate and/or of the layers, ion-induced roughening, effects of differential sputtering of the various elements, transitory stage of the primary ion beam implantation, ion beam induced accelerated diffusion, balistic mixing or segregation; etc.. This communication describes several examples of SIMS analysis performed on metal multilayers (Co/Cu) and on epitaxial semiconductor layers (CdTe/GaAs), focussing the interest on the particular analytical problems raised by the initial roughness and the ion induced roughening effect. The interpretation of the measured profiles, the influence of analytical parameters (such as the nature of the primary ion beam, sputtering conditions, detected ion species), and the limitations of profilometry roughness measurements, are discussed. Solutions are proposed in order to improve the depth resolution of interface characterization, including a tentative modelization of roughness effects. (orig.).

  10. Fourier transform infrared spectroscopic characterisation of heavy metal-induced metabolic changes in the plant-associated soil bacterium Azospirillum brasilense Sp7

    Kamnev, A. A.; Antonyuk, L. P.; Tugarova, A. V.; Tarantilis, P. A.; Polissiou, M. G.; Gardiner, P. H. E.

    2002-06-01

    Structural and compositional features of whole cells of the plant-growth-promoting rhizobacterium Azospirillum brasilense Sp7 under standard and heavy metal-stressed conditions are analysed using Fourier transform infrared (FTIR) spectroscopy and compared with the FT-Raman spectroscopic data obtained previously [J. Mol. Struct. 563-564 (2001) 199]. The structural spectroscopic information is considered together with inductively coupled plasma-mass spectrometric (ICP-MS) analytical data on the content of the heavy metal cations (Co 2+, Cu 2+ and Zn 2+) in the bacterial cells. As a bacterial response to heavy metal stress, all the three metals, being taken up by bacterial cells from the culture medium (0.2 mM) in significant amounts (ca. 0.12, 0.48 and 4.2 mg per gram of dry biomass for Co, Cu and Zn, respectively), are shown to induce essential metabolic changes in the bacterium revealed in the spectra, including the accumulation of polyester compounds in bacterial cells and their enhanced hydration affecting certain IR vibrational modes of functional groups involved.

  11. Effect of Zn2+ Substitution on the Structure and Magnetic Properties of Co0.5Cu0.5Fe2O4 Synthesized by Solvothermal Method

    Huang, Xusheng; Zhou, Yuan; Wu, Wenwei; Xu, Jiawei; Liu, Shangqian; Liu, Dongsheng; Wu, Juan

    2016-06-01

    A series of Zn2+ doped Co-Cu ferrites with the formula Co0.5Cu0.5- x Zn x Fe2O4 (0.0 ≤ x ≤ 0.3) have been successfully synthesized using the solvothermal method. X-ray diffraction and scanning electron microscopy results indicate that a high-crystallized cubic Co0.5Cu0.5- x Zn x Fe2O4 with rod-like structure is obtained when the precursor is calcined at 800°C in air for 3 h. The lattice parameters increase with the increase of Zn2+ additional amount, attributed to the larger ionic radius of the substituted ion Zn2+ than Cu2+ ionic radius. Zn2+ substitution can improve the magnetic properties of Co0.5Cu0.5- x Zn x Fe2O4. Co0.5Cu0.4Zn0.1Fe2O4 obtained at 800°C has the highest specific saturation magnetization (73.7 ± 0.9 emu/g) and magnetic moment (3.13 ± 0.04 B.M.).

  12. Crystal structure, thermal expansion and high-temperature electrical conductivity of A-site deficient La2−zCo1+y(MgxNb1−x)1−yO6 double perovskites

    New La-deficient double perovskites with P21/n symmetry, La∼1.90(Co2+1−xMg2+x)(Co3+1/3Nb5+2/3)O6 with x=0, 0.13 and 0.33, and La2(Co2+1/2Mg2+1/2) (Co3+1/2Nb5+1/2)O6 were prepared by solid state reaction at 1450 °C. Their crystal structures were refined using time-of-flight neutron powder diffraction data. Our results show that certain cations such as Nb5+, with very strong B–O bonds in the perovskite structure, can induce A-site vacancies in double perovskites. Upon heating in N2 gas atmosphere at 1200 °C ∼1% O atom vacancies are formed together with a partial reduction of the Co3+ content. The average thermal expansion coefficient between 25 and 900 °C of La1.90(Co2+2/3Mg2+1/3)(Co3+1/3Nb5+2/3)O6 was determined to be 17.4 ppm K−1. Four-point electronic conductivity measurements showed that the compounds are semiconductors, with conductivities varying between 3.7·10−2 and 7.7·10−2 S cm−1 at 600 °C and activation energies between 0.77 and 0.81 eV. Partial replacement of La3+ with Sr2+ does not lead to any increase of conductivity, while replacement of Mg2+ with Cu2+ in La1.9CoCu1/3Nb2/3O6 and La1.8CoCu1/2Nb1/2O6 leads to ∼100 times larger conductivities at 600 °C, 0.35 and 1.0 S cm−1, respectively, and lower activation energies, 0.57 and 0.73 eV, respectively. - Highlights: • Double perovskites, P21/n, La2−z(Co2+1−xMg2+x)(Co3+1/3Nb5+2/3)O6 have been synthesized. • Crystal structures have been refined using neutron powder diffraction data. • Strong Nb–O bond and size ordering of Mg2+/Co2+ and Nb5+/Co~3+ leads to La-deficiency. • The compounds are semi conductors (~10−2 S cm−1) at 600 °C. • Replacement of Mg2+ with Cu2+ leads to higher conductivity (~1.0 S cm−1) at 600 °C

  13. Preservation of NOM-metal complexes in a modern hyperalkaline stalagmite: Implications for speleothem trace element geochemistry

    Hartland, Adam; Fairchild, Ian J.; Müller, Wolfgang; Dominguez-Villar, David

    2014-03-01

    We report the first quantitative study of the capture of colloidal natural organic matter (NOM) and NOM-complexed trace metals (V, Co, Cu, Ni) in speleothems. This study combines published NOM-metal dripwater speciation measurements with high-resolution laser ablation ICPMS (LA-ICPMS) and sub-annual stable isotope ratio (δ18O and δ13C), fluorescence and total organic carbon (TOC) analyses of a fast-growing hyperalkaline stalagmite (pH ˜11) from Poole’s Cavern, Derbyshire UK, which formed between 1997 and 2008 AD. We suggest that the findings reported here elucidate trace element variations arising from colloidal transport and calcite precipitation rate changes observed in multiple, natural speleothems deposited at ca. pH 7-8. We find that NOM-metal(aq) complexes on the boundary between colloidal and dissolved (˜1 nm diameter) show an annual cyclicity which is inversely correlated with the alkaline earth metals and is explained by calcite precipitation rate changes (as recorded by kinetically-fractionated stable isotopes). This relates to the strength of the NOM-metal complexation reaction, resulting in very strongly bound metals (Co in this system) essentially recording NOM co-precipitation (ternary complexation). More specifically, empirical partition coefficient (Kd) values between surface-reactive metals (V, Co, Cu, Ni) [expressed as ratio of trace element to Ca ratios in calcite and in solution] arise from variations in the ‘free’ fraction of total metal in aqueous solution (fm). Hence, differences in the preservation of each metal in calcite can be explained quantitatively by their complexation behaviour with aqueous NOM. Differences between inorganic Kd values and field measurements for metal partitioning into calcite occur where [free metal] ≪ [total metal] due to complexation reactions between metals and organic ligands (and potentially inorganic colloids). It follows that where fm ≈ 0, apparent inorganic Kd app values are also ≈0, but the

  14. Assessing the concentration, speciation, and toxicity of dissolved metals during mixing of acid-mine drainage and ambient river water downstream of the Elizabeth Copper Mine, Vermont, USA

    Balistrieri, L.S.; Seal, R.R., II; Piatak, N.M.; Paul, B.

    2007-01-01

    The authors determine the composition of a river that is impacted by acid-mine drainage, evaluate dominant physical and geochemical processes controlling the composition, and assess dissolved metal speciation and toxicity using a combination of laboratory, field and modeling studies. Values of pH increase from 3.3 to 7.6 and the sum of dissolved base metal (Cd + Co + Cu + Ni + Pb + Zn) concentrations decreases from 6270 to 100 ??g/L in the dynamic mixing and reaction zone that is downstream of the river's confluence with acid-mine drainage. Mixing diagrams and PHREEQC calculations indicate that mixing and dilution affect the concentrations of all dissolved elements in the reach, and are the dominant processes controlling dissolved Ca, K, Li, Mn and SO4 concentrations. Additionally, dissolved Al and Fe concentrations decrease due to mineral precipitation (gibbsite, schwertmannite and ferrihydrite), whereas dissolved concentrations of Cd, Co, Cu, Ni, Pb and Zn decrease due to adsorption onto newly formed Fe precipitates. The uptake of dissolved metals by aquatic organisms is dependent on the aqueous speciation of the metals and kinetics of complexation reactions between metals, ligands and solid surfaces. Dissolved speciation of Cd, Cu, Ni and Zn in the mixing and reaction zone is assessed using the diffusive gradients in thin films (DGT) technique and results of speciation calculations using the Biotic Ligand Model (BLM). Data from open and restricted pore DGT units indicate that almost all dissolved metal species are inorganic and that aqueous labile or DGT available metal concentrations are generally equal to total dissolved concentrations in the mixing zone. Exceptions occur when labile metal concentrations are underestimated due to competition between H+ and metal ions for Chelex-100 binding sites in the DGT units at low pH values. Calculations using the BLM indicate that dissolved Cd and Zn species in the mixing and reaction zone are predominantly inorganic

  15. Crystal structure, thermal expansion and high-temperature electrical conductivity of A-site deficient La{sub 2−z}Co{sub 1+y}(Mg{sub x}Nb{sub 1−x}){sub 1−y}O{sub 6} double perovskites

    Shafeie, S. [Department of Materials and Manufacturing Technology, Chalmers University of Technology, SE-412 96 Gothenburg (Sweden); Dreyer, B.; Awater, R.H.P [Department of Materials and Environmental Chemistry, Stockholm University, S-106 91 Stockholm (Sweden); Golod, T. [Department of Physics, Albanova University Center, Stockholm University, S-106 91 Stockholm (Sweden); Grins, J. [Department of Materials and Environmental Chemistry, Stockholm University, S-106 91 Stockholm (Sweden); Biendicho, J.J. [Department of Materials and Environmental Chemistry, Stockholm University, S-106 91 Stockholm (Sweden); The ISIS Facility, STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX (United Kingdom); Istomin, S.Ya. [Department of Chemistry, M.V. Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Svensson, G., E-mail: gunnar@mmk.su.se [Department of Materials and Environmental Chemistry, Stockholm University, S-106 91 Stockholm (Sweden)

    2015-09-15

    New La-deficient double perovskites with P2{sub 1}/n symmetry, La{sub ∼1.90}(Co{sup 2+}{sub 1−x}Mg{sup 2+}{sub x})(Co{sup 3+}{sub 1/3}Nb{sup 5+}{sub 2/3})O{sub 6} with x=0, 0.13 and 0.33, and La{sub 2}(Co{sup 2+}{sub 1/2}Mg{sup 2+}{sub 1/2}) (Co{sup 3+}{sub 1/2}Nb{sup 5+}{sub 1/2})O{sub 6} were prepared by solid state reaction at 1450 °C. Their crystal structures were refined using time-of-flight neutron powder diffraction data. Our results show that certain cations such as Nb{sup 5+}, with very strong B–O bonds in the perovskite structure, can induce A-site vacancies in double perovskites. Upon heating in N{sub 2} gas atmosphere at 1200 °C ∼1% O atom vacancies are formed together with a partial reduction of the Co{sup 3+} content. The average thermal expansion coefficient between 25 and 900 °C of La{sub 1.90}(Co{sup 2+}{sub 2/3}Mg{sup 2+}{sub 1/3})(Co{sup 3+}{sub 1/3}Nb{sup 5+}{sub 2/3})O{sub 6} was determined to be 17.4 ppm K{sup −1}. Four-point electronic conductivity measurements showed that the compounds are semiconductors, with conductivities varying between 3.7·10{sup −2} and 7.7·10{sup −2} S cm{sup −1} at 600 °C and activation energies between 0.77 and 0.81 eV. Partial replacement of La{sup 3+} with Sr{sup 2+} does not lead to any increase of conductivity, while replacement of Mg{sup 2+} with Cu{sup 2+} in La{sub 1.9}CoCu{sub 1/3}Nb{sub 2/3}O{sub 6} and La{sub 1.8}CoCu{sub 1/2}Nb{sub 1/2}O{sub 6} leads to ∼100 times larger conductivities at 600 °C, 0.35 and 1.0 S cm{sup −1}, respectively, and lower activation energies, 0.57 and 0.73 eV, respectively. - Highlights: • Double perovskites, P2{sub 1}/n, La{sub 2−z}(Co{sup 2+}{sub 1−x}Mg{sup 2+}{sub x})(Co{sup 3+}{sub 1/3}Nb{sup 5+}{sub 2/3})O{sub 6} have been synthesized. • Crystal structures have been refined using neutron powder diffraction data. • Strong Nb–O bond and size ordering of Mg{sup 2+}/Co{sup 2+} and Nb{sup 5+}/Co{sup ~3+} leads to La-deficiency. • The

  16. Trace elements in rock phosphates and P containing mineral and organo-mineral fertilizers sold in Germany.

    Kratz, Sylvia; Schick, Judith; Schnug, Ewald

    2016-01-15

    68 rock phosphates and 162 P containing (organo-)mineral fertilizers sold in Germany were evaluated with regard to trace element contents. While Al, As, B, Be, Cd, Cr, Mo, Ni, Pb, Sb, Se, Tl, U, and Zn were higher in sedimentary than in igneous rock phosphates, the opposite was true for Co, Cu, Sn, Mn, Ti, Fe, and Sr. Comparing element concentrations to the currently valid legal limit values defined by the German Fertilizer Ordinance, it was found that some PK and many straight P fertilizers (superphosphate, triple superphosphate, partly acidulated rock phosphates) exceeded the limit of 50 mg Cd/kg P2O5. Mean values for As, Ni, Pb, and Tl remained below legal limits in almost all cases. While no legal limit has been defined for U in Germany yet, the limit of 50 mg U/kg P2O5 for P containing fertilizers proposed by the German Commission for the Protection of Soils was clearly exceeded by mean values for all fertilizer types analyzed. A large share of the samples evaluated in this work contained essential trace elements at high concentrations, with many of them not being declared as such. Furthermore, trace elements supplied with these fertilizers at a fertilization rate leveling P uptake would exceed trace element uptake by crops. This may become most relevant for B and Fe, since many crops are sensitive to an oversupply of B, and Fe loads exceeding plant uptake may immobilize P supplies for the crops by forming Fe phosphate salts. The sample set included two products made from thermochemically treated sewage sludge ash. The products displayed very high concentrations of Fe and Mn and exceeded the legal limit for Ni, emphasizing the necessity to continue research on heavy metal removal from recycled raw materials and the development of environmentally friendly and agriculturally efficient fertilizer products. PMID:26328946

  17. Significant manipulation of output performance of a bridge-structured spin valve magnetoresistance sensor via an electric field

    Zhang, Yue; Yan, Baiqian; Ou-Yang, Jun; Zhu, Benpeng; Chen, Shi; Yang, Xiaofei, E-mail: hust-yangxiaofei@163.com [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China); Wang, Xianghao [School of Information Engineering, Wuhan University of Technology, Wuhan 430070 (China)

    2016-01-28

    Through principles of spin-valve giant magnetoresistance (SV-GMR) effect and its application in magnetic sensors, we have investigated electric-field control of the output performance of a bridge-structured Co/Cu/NiFe/IrMn SV-GMR sensor on a PZN-PT piezoelectric substrate using the micro-magnetic simulation. We centered on the influence of the variation of uniaxial magnetic anisotropy constant (K) of Co on the output of the bridge, and K was manipulated via the stress of Co, which is generated from the strain of a piezoelectric substrate under an electric field. The results indicate that when K varies between 2 × 10{sup 4 }J/m{sup 3} and 10 × 10{sup 4 }J/m{sup 3}, the output performance can be significantly manipulated: The linear range alters from between −330 Oe and 330 Oe to between −650 Oe and 650 Oe, and the sensitivity is tuned by almost 7 times, making it possible to measure magnetic fields with very different ranges. According to the converse piezoelectric effect, we have found that this variation of K can be realized by applying an electric field with the magnitude of about 2–20 kV/cm on a PZN-PT piezoelectric substrate, which is realistic in application. This result means that electric-control of SV-GMR effect has potential application in developing SV-GMR sensors with improved performance.

  18. Trace elemental analysis of carcinoma kidney and stomach by PIXE method

    Reddy, S. Bhuloka E-mail: sbr_r@yahoo.com; John Charles, M.; Naga Raju, G.J.; Vijayan, V.; Seetharami Reddy, B.; Ravi Kumar, M.; Sundareswar, B

    2003-07-01

    Trace elemental analysis was carried out in the biological samples of carcinoma kidney and stomach using particle induced X-ray emission technique. A 2 MeV proton beam was employed to excite the samples. From the present results, the levels of elements K, Ca, Fe, Ni and Se are lower and those of the elements Ti, Co, Zn, As and Cd are higher in the cancer tissue of kidney than those observed in the normal tissue. In the case of stomach, the concentrations of elements Cl, K, Ca, Ti, Mn, Fe, Co, Cu and Zn are lower while concentrations of elements Cr, Ni, As and Br are higher in the cancer tissue of stomach than those observed in the normal tissue. The observed deficiency or excess of certain elements is correlated to carcinogenesis of that organ. The present results of carcinoma stomach support the previous observations that nickel and chromium are carcinogenic agents. The low levels of selenium observed in the carcinoma tissue of kidney and the low levels of manganese observed in the carcinoma tissue of stomach support the view that selenium and manganese inhibit the growth of cancer in kidney and stomach respectively. The observed high levels of zinc in the cancer tissue of kidney suggest that zinc is involved in the tumor growth and development of neoplastic transformation in kidney while the observed low levels of zinc in the carcinoma tissue of stomach suggest that zinc inhibits the growth of cancer in this organ. For correctly assessing the role played by the trace elements in initiating, promoting or inhibiting cancer in various organs, there is a need for acquisition of more data by trace elemental analysis from several investigations of this type undertaken in different regions.

  19. Using lead isotopes and trace element records from two contrasting Lake Tanganyika sediment cores to assess watershed – Lake exchange

    Odigie, Kingsley; Cohen, A.D.; Swarzenski, Peter W.; Flegal, R

    2014-01-01

    Lead isotopic and trace element records of two contrasting sediment cores were examined to reconstruct historic, industrial contaminant inputs to Lake Tanganyika, Africa. Observed fluxes of Co, Cu, Mn, Ni, Pb, and Zn in age-dated sediments collected from the lake varied both spatially and temporally over the past two to four centuries. The fluxes of trace elements were lower (up to 10-fold) at a mid-lake site (MC1) than at a nearshore site (LT-98-58), which is directly downstream from the Kahama and Nyasanga River watersheds and adjacent to the relatively pristine Gombe Stream National Park. Trace element fluxes at that nearshore site did not measurably change over the last two centuries (1815–1998), while the distal, mid-lake site exhibited substantial changes in the fluxes of trace elements – likely caused by changes in land use – over that period. For example, the flux of Pb increased by ∼300% from 1871 to 1991. That apparent accelerated weathering and detrital mobilization of lithogenic trace elements was further evidenced by (i) positive correlations (r = 0.77–0.99, p Lake Tanganyika in spite of the development of mining and smelting operations within the lake’s watershed over the past century. The data also indicate that the mid-lake site is a much more sensitive and useful recorder of environmental changes than the nearshore site. Furthermore, the lead isotopic compositions of sediment at the sites differed spatially, indicating that the Pb (and other trace elements by association) originated from different natural sources at the two locations.

  20. Production of yellow cake from rock phosphate deposits and its characterization

    This study was carried out mainly to produce uranium trioxide (UO3), with the standard of commercial specifications from rock phosphate deposits in eastern part of Nuba mountains, south Kurdufan state. A simplified hydrometallurgical procedure has been adopted for production of yellow cake from the ore. Elemental analysis has shown that the ore is rich in Ca and deficient in elements of potential interest such as Fe, Cu and Zn. Uranium content in ore, phosphoric acid and purified yellow cake (UO3) obtained with different precipitants was analyzed using alpha-spectrometry. On the average, the activity concentration of uranium in ore corresponds to 82 ± 24 ppm (0.10%). From the data of pregnant liquor, it was observed that the addition of KCIO3 as an oxidant improves the dissolution of uranium from the ore by almost 20%. Data has also indicated that the yellow cake purified by hydrogen peroxide has higher concentration of uranium by 44.5% over the one purified by TBP extraction. Undesirable impurities in yellow cake as dictated by the function to which it is intended for were analyzed and compared with international standard specifications set for commercial products. Uranium as U3O8 was found to be 53% in yellow cake initially obtained as ammonium diuranate and purified by hydrogen peroxide and 38% in one, which is purified by TBP extraction. With the exception of Cr concentration, the values of the other critical impurities ( V, Mn, Co, Cu, Sr, Zr, Pb, Fe, Cl, Br, I) in UO3 precipitated by hydrogen peroxide are either typical or lower than those internationally specified as standards for commercial products. Among the impurities considered Cd, Th and Mo were undetectable. The most salient point to be mentioned here regarding impurities is that Cd, which is most undesirable in yellow cake because of its high neutron absorption cross section, was undetectable in both types of yellow cakes ( i.e. purified by TBP extraction and by hydrogen peroxide). (Author)