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

  1. Spin-dependent Peltier effect in Co /Cu multilayer nanowires

    Science.gov (United States)

    Gravier, Laurent; Serrano-Guisan, Santiago; Ansermet, J.-Ph.

    2005-05-01

    Heat transport perpendicular to the plane of magnetic multilayers is monitored with ac temperature gradients in the presence of a direct charge current. A very strong dependence on the applied magnetic field of the voltage response to the ac gradient is observed using Co /Cu multilayered nanowires. The effect is interpreted as a Peltier effect for a one-dimensional heat flux.

  2. Co/Cu spin valves electrodeposited on Si

    Energy Technology Data Exchange (ETDEWEB)

    Seligman, L.; Sartorelli, M.L. E-mail: sart@fisica.ufsc.br; Pasa, A.A.; Schwarzacher, W.; Kasyutich, O.I

    2001-05-01

    Co/Cu spin-valve structures have been electrodeposited from a single bath directly onto n-type (1 0 0) Si substrates. The structures were based on the fact that Co layers on Si show a dependence of coercive field on layer thickness. By sandwiching a stack of 3, 5 or 8 hard antiferromagnetic-coupled Co/Cu multilayers between two soft Co layers, it was possible to obtain low-field-sensitive magnetoresistive structures, showing MR ratios ranging from 5.9% to 8.6%, as well as field sensitivities in the range of 0.10% Oe at 15-40 Oe. Samples with 8.6% MR ratio were obtained by stacking up to 10 magnetic layers.

  3. 2D magnetic texture analysis of Co-Cu films

    Energy Technology Data Exchange (ETDEWEB)

    Bayirli, Mehmet; Karaagac, Oznur; Kockar, Hakan [Balikesir Univ. (Turkey). Physics Dept.; Alper, Mursel [Uludag Univ., Bursa (Turkey). Physics Dept.

    2017-08-01

    The magnetic textures for the produced magnetic materials are important concepts in accordance with technical applications. Therefore, the aim of this article is to determine 2D magnetic textures of electrodeposited Co-Cu films by the measurement of hysteresis loops at the incremented angles. For that, Co-Cu films were deposited with different Co{sup 2+} in the electrolyte. In addition, the easy-axis orientation in the films from the squareness values of the angles, M{sub p}(β) obtained by the hysteresis loops have been numerically studied using the Fourier series analysis. The differences observed in the magnetic easy-axis distributions were attributed to changes of the incorporation of Co in the films with the change of Co{sup 2+} in the electrolyte. The coefficients of Fourier series (A{sub 0} and A{sub 2n}) were also computed for 2D films. It is seen that a systematic and small decrease in A{sub 0} and an obvious decrease in A{sub 2n} (n=1) were observed with increasing incorporated Co in the films. Results imply that interactions cause slightly demagnetization effect accordance with higher incorporation of Co in the films. Furthermore, the crystal structure of the Co-Cu films analysed by X-ray diffraction revealed that the films have dominantly face-centred cubic structure. Film contents analysed by energy-dispersive X-ray spectroscopy and film morphologies observed by scanning electron microscope also support the magnetic texture analysis results found by numerical computation.

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

    Science.gov (United States)

    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.

  5. Direct laser sintered WC-10Co/Cu nanocomposites

    Science.gov (United States)

    Gu, Dongdong; Shen, Yifu

    2008-04-01

    In the present work, the direct metal laser sintering (DMLS) process was used to prepare the WC-Co/Cu nanocomposites in bulk form. The WC reinforcing nanoparticles were added in the form of WC-10 wt.% Co composite powder. The microstructural features and mechanical properties of the laser-sintered sample were characterized by X-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscope (SEM), energy dispersive X-ray spectroscope (EDX), and nanoindentation tester. It showed that the original nanometric nature of the WC reinforcing particulates was well retained without appreciable grain growth after laser processing. A homogeneous distribution of the WC reinforcing nanoparticles with a coherent particulate/matrix interfacial bonding was obtained in the laser-sintered structure. The 94.3% dense nanocomposites have a dynamic nanohardness of 3.47 GPa and a reduced elastic modulus of 613.42 GPa.

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

    Institute of Scientific and Technical Information of China (English)

    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.

  7. Electrochemical deposition and modification of Cu/Co-Cu multilayer

    Energy Technology Data Exchange (ETDEWEB)

    Uhlemann, M.; Gebert, A.; Herrich, M.; Krause, A.; Cziraki, A.; Schultz, L

    2003-09-30

    Multilayers of Cu/Co-Cu were electrodeposited from a citrate electrolyte on quartz with Au and Si substrates with a Permalloy/Cu seedlayer by means of the potentiostatic double-pulse technique simultaneously controlled by microgravimetric measurements. The influence of a superimposed magnetic field and of annealing conditions on the microstructure has been studied. When an external magnetic field is parallel-orientated toward the electrode, an increase of the Cu deposition rate was observed due to magnetohydrodynamic effects. In contrast, the deposition rate of Co decreases. Microstructural investigations have shown that both a superimposed uniform magnetic field up to 600 mT and an inhomogeneous field of an SmCo permanent magnet change the microstructure and improve the GMR effect. X-ray diffraction measurements revealed that all grains are arranged in the <1 1 1> direction in contrast to layers formed without magnetic field with only 75% of the grains having a (1 1 1) texture. Isothermal heat treatment at different temperatures increases the GMR effect corresponding to an increase of grain size with preferred (1 1 1) orientation.

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

    Institute of Scientific and Technical Information of China (English)

    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.

  9. Effect of sputter gas on the physical and magnetic microstructure of Co/Cu multilayers

    NARCIS (Netherlands)

    Donnet, D.M.; Tsutsumi, K.; Haan, de P.; Lodder, J.C.

    1996-01-01

    The physical structure of Co/Cu multilayers, sputtered in different gases (Ar, Kr, and Xe) together with the domain structures that these films support have been investigated using electron microscopy in an attempt to explain the differences in their measured magnetoresistance (MR). Both planar and

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

    DEFF Research Database (Denmark)

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

    2007-01-01

    Spin-transfer torque effects are reported in nanowires consisting in Co/Cu/Co trilayers electrodeposited on an anodic alumina template. Using a nanolithography process based on electrically controlled nanoindentation of the alumina template, we are able to investigate the spin transport propertie...

  11. Magnetic properties and interlayer coupling of epitaxial Co/Cu films on Si

    Energy Technology Data Exchange (ETDEWEB)

    Mansell, R.; Petit, D. C. M. C.; Fernández-Pacheco, A.; Lavrijsen, R.; Lee, J. H.; Cowburn, R. P. [Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom)

    2014-08-14

    Thin films of Co and Co/Cu/Co trilayers with wedged Cu interlayers were grown epitaxially on Cu buffer layers on hydrogen passivated Si(001) wafers. We find that single Co layers have a well-defined four-fold anisotropy but with smaller in-plane anisotropies than observed in Co grown on Cu crystals. Ruderman–Kittel–Kasuya–Yosida (RKKY) interlayer coupling is observed in one Co/Cu/Co sample which is the smoothest of the films as measured by atomic force microscopy. Some of the films also form a dot-like structure on the surface. Intermixing at elevated temperatures between the Cu buffer and Si limits the ability to form flat surfaces to promote RKKY coupling.

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

    DEFF Research Database (Denmark)

    Nilsson, A.; Sthör, J.; Wiell, T.

    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.......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...

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

    Institute of Scientific and Technical Information of China (English)

    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.

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

    Institute of Scientific and Technical Information of China (English)

    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.

  15. Magnetic properties of Co/Cu and Co/Pt bimetallic clusters

    Science.gov (United States)

    Lu, Q. L.; Zhu, L. Z.; Ma, L.; Wang, G. H.

    2005-05-01

    The ground state structures of Co/Cu and Co/Pt clusters are obtained by empirical genetic algorithm, and further optimized using the density functional theory with generalized gradient approximation. For Co 13, Pt 13 and Cu 13, they show perfect Ih symmetry. The structures of bimetallic clusters are slightly distorted configuration of Co 13. The average magnetic moment of Co 13 is 2.38 μB/atom, and that of Cu 13 and Pt 13 is nonzero. The local moments of the central atom are smaller than that of the surface ones for Co 13 and Cu 13. But the cases are not held for Pt 13. The total magnetic moment of clusters Co/Pt monotonously decreases with increasing the concentration of Pt atoms. But the things are much more complicated for clusters Co/Cu, and the reasons are discussed in detail.

  16. Magnetic and Structural Properties in Co/Cu/Co Sandwiches with Ni and Cr Buffer Layers

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The magnetic and structural properties in Co/Cu/Co sandwiches with Ni and Cr buffer layers were investigated. It was found that the coercivity in Ni layer buffered samples decreases with increasing Ni layer thickness, while that in Cr layer buffered ones increases with increasing Cr layer thickness, leading to a large difference in field sensitivity of their giant magnetoresistance (GMR) properties. X-ray diffraction and high resolution transmission electron microscope images exhibited that there is a strong fcc (111) texture in the samples with Ni buffer layer. But there are only randomly oriented polycrystalline grains in Cr buffered sandwiches. According to atomic force microscope topography, the surface roughness of Cr buffered sandwiches is smaller than that of Ni buffered ones. It is demonstrated that buffer layer influences both magnetic and structural properties in Co/Cu/Co sandwiches as well as their GMR characteristics.

  17. Separation of spin Seebeck effect and anomalous Nernst effect in Co/Cu/YIG

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Dai [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States); State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433 (China); Li, Yufan; Qu, D.; Chien, C. L., E-mail: clchien@jhu.edu [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Jin, Xiaofeng [State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433 (China)

    2015-05-25

    The spin Seebeck effect (SSE) and Anomalous Nernst effect (ANE) have been observed in Co/Cu/YIG (yttrium iron garnet) multi-layer structure, where the ferromagnetic insulator YIG acts as the pure spin injector and the ferromagnetic metal Co layer acts as the spin current detector. With the insertion of 5 nm Cu layer, the two ferromagnetic layers are decoupled, thus allowing unambiguous separation of the SSE and ANE contributions under the same experimental conditions in the same sample.

  18. Separation of spin Seebeck effect and anomalous Nernst effect in Co/Cu/YIG

    Science.gov (United States)

    Tian, Dai; Li, Yufan; Qu, D.; Jin, Xiaofeng; Chien, C. L.

    2015-05-01

    The spin Seebeck effect (SSE) and Anomalous Nernst effect (ANE) have been observed in Co/Cu/YIG (yttrium iron garnet) multi-layer structure, where the ferromagnetic insulator YIG acts as the pure spin injector and the ferromagnetic metal Co layer acts as the spin current detector. With the insertion of 5 nm Cu layer, the two ferromagnetic layers are decoupled, thus allowing unambiguous separation of the SSE and ANE contributions under the same experimental conditions in the same sample.

  19. Investigation on the structural variation of Co-Cu nanoparticles during the annealing process.

    Science.gov (United States)

    Ju, Shin-Pon; Lo, Yu-Chieh; Sun, Shih-Jye; Chang, Jee-Gong

    2005-11-10

    This study uses molecular dynamics simulations to investigate the crystalline process of Co-Cu nanoparticles of high and low Co concentrations (5 and 25%) during the annealing process. The modified many-body tight-binding potential involving magnetic contribution is adopted to accurately model the Cu-Cu, Co-Co, and Co-Cu pair interactions. The Co-Co bond length increases, while the Co-Cu bond length decreases as the temperature gradually drops from 2000 K to the upper melting point. During that process, the Cu-Cu bond length remains constant and the value of the first peak of the radial distribution function (RDF) increases, which indicates that Cu atoms increase their short-range order by mutual rearrangement. At temperatures lower than the upper melting point, the bond length of each pair decreases while the value of the first peak increases as the temperature is continuously reduced. Because the kinetic energy of an individual atom is not enough for rearrangement, the variations of bond length and the first RDF peak can be attributed to the shrinking effect.

  20. Magnetic Properties and Structural Study of Ni-Co/Cu Multilayers Prepared by Electrodeposition Method

    Directory of Open Access Journals (Sweden)

    M. Jafari Fesharaki

    2015-07-01

    Full Text Available Ni-Co/Cu multilayers have been grown by electrodeposition method from a single electrolyte (based on Ni(SO4.6H2O, Co(SO4.7H2O, Cu(SO4 and H3BO3 using galvanostatic control on titanium sublayers. The X-ray diffraction (XRD patterns confirmed the multilayered structure with the nanometer thicknesses. Also, electron diffraction x-ray (EDX  analysis confirmed the purity of deposited samples. The morphology of the samples was estimated by scanning electron microscope (SEM. Magnetoresistance (MR measurements were carried out at room temperature for the Ni-Co/Cu multilayers by measuring the resistivity in a magnetic fields varying between ±6kOe as a function of the Ni-Co and Cu layer thicknesses; (1 dCu(nm 4 and 3 dNi-Cu(nm 5. The Maximum value of giant magnetoresistance (GMR was obtained when the Ni-Co and Cu thicknesses were 4.0nm and 4.0nm respectively. The hysteresis loop of the samples at room temperature was studied using an alternating gradient force magnetometer (AGFM. Finally, the temperature dependence of magnetization for Ni-Co/Cu multilayers; (dNi-Cu(4nm/dCu(2nm and dNi-Cu(3nm/dCu(3nm measured by Faraday balance and decreasing the magnetization with increasing the temperature discussed according to electron scattering due to spin fluctuation.

  1. Magnetic and magnetoresistance studies of nanometric electrodeposited Co films and Co/Cu layered structures: Influence of magnetic layer thickness

    Science.gov (United States)

    Zsurzsa, S.; Péter, L.; Kiss, L. F.; Bakonyi, I.

    2017-01-01

    The magnetic properties and the magnetoresistance behavior were investigated for electrodeposited nanoscale Co films, Co/Cu/Co sandwiches and Co/Cu multilayers with individual Co layer thicknesses ranging from 1 nm to 20 nm. The measured saturation magnetization values confirmed that the nominal and actual layer thicknesses are in fairly good agreement. All three types of layered structure exhibited anisotropic magnetoresistance for thick magnetic layers whereas the Co/Cu/Co sandwiches and Co/Cu multilayers with thinner magnetic layers exhibited giant magnetoresistance (GMR), the GMR magnitude being the largest for the thinnest Co layers. The decreasing values of the relative remanence and the coercive field when reducing the Co layer thickness down to below about 3 nm indicated the presence of superparamagnetic (SPM) regions in the magnetic layers which could be more firmly evidenced for these samples by a decomposition of the magnetoresistance vs. field curves into a ferromagnetic and an SPM contribution. For thicker magnetic layers, the dependence of the coercivity (Hc) on magnetic layer thickness (d) could be described for each of the layered structure types by the usual equation Hc=Hco+a/dn with an exponent around n=1. The common value of n suggests a similar mechanism for the magnetization reversal by domain wall motion in all three structure types and hints also at the absence of coupling between magnetic layers in the Co/Cu/Co sandwiches and Co/Cu multilayers.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.)

  3. Spin-Polarized Electron Injection in Co/Cu/Fe Sandwich Structure

    Institute of Scientific and Technical Information of China (English)

    WANG Shou-Guo; CHEN Yan-Xue; WANG Zhi-He; CHEN Qiang; XIE Shi-Jie; MEI Liang-Mo

    2000-01-01

    A material asymmetry Co/Cu/Fe junction structure has been prepared for studying the spin-polarized electron injection at 77K. The sample performance was demonstrated to be analogous to that of a bipolar transistor. The maximal value of the output pulse voltage between Cu and Fe layers could reach the order of severalμV when the bias current between Co and Cu layers was 10μA. The interface roughness, photograph of material, magnetic loop and injection characteristic curves have been measured. Some important points on this topic have been discussed.

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

    CERN Document Server

    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. Giant magnetoresistance effect in Ni buffered Co/Cu/Co sandwich

    Institute of Scientific and Technical Information of China (English)

    LI; Tie(李铁)

    2002-01-01

    The effects of Ni buffer layer on the giant magnetoresistance structure of Co/Cu/Co sandwich are investigated systematically in this paper.It is found that Ni buffer layer can induce the crystallization of the lower Ni/Co layer and produce small coercivity,thus enlarging the difference in the magnetic behavior between the two magnetic layers in the sandwich.Moreover,the use of the Ni buffer layer can also improve the interface flatness in the sandwich.All these factors enhance the sensitivity of the Ni buffered sandwich.``

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

    Science.gov (United States)

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

    2016-03-08

    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.

  7. Dealloying Behavior of NiCo and NiCoCu Thin Films

    Directory of Open Access Journals (Sweden)

    Benjamin E. Peecher

    2016-01-01

    Full Text Available Porous metals and alloys, such as those fabricated via electrochemical dealloying, are of interest for a variety of energy applications, ranging from their potential for enhanced catalytic behavior to their use as high surface area supports for pseudocapacitor materials. Here, the electrochemical dealloying process was explored for electrodeposited binary NiCo and ternary NiCoCu thin films. For each of the four different metal ratios, films were dealloyed using linear sweep voltammetry to various potentials in order to gain insight into the evolution of the film over the course of the linear sweep. Electrochemical capacitance, scanning electron microscopy, and energy dispersive X-ray spectroscopy were used to examine the structure and composition of each sample before and after linear sweep voltammetry was performed. For NiCo films, dealloying resulted in almost no change in composition but did result in an increased capacitance, with greater increases occurring at higher linear sweep potentials, indicating the removal of material from the films. Dealloying also resulted in the appearance of large pores on the surface of the high nickel percentage NiCo films, while low nickel percentage NiCo films had little observable change in morphology. For NiCoCu films, Cu was almost completely removed at linear sweep potentials greater than 0.5 V versus Ag/AgCl. The linear sweep removed large Cu-rich dendrites from the films, while also causing increases in measured capacitance.

  8. Contribution to Analysis of Co/Cu Substituted Ni-Zn Ferrites

    Directory of Open Access Journals (Sweden)

    G. S. V. R. K. Choudary

    2013-01-01

    Full Text Available In this communication, Co/Cu substituted Ni-Zn ferrites processed through sol-gel synthesis using polyethylene glycol (PEG as a chelating agent are studied, intending to aid in understanding and choosing the optimum ferrite material for high frequency applications. Lattice constant and average crystallite size have been estimated from FWHM of the X-ray diffraction peaks, and these parameters are understood by considering the ionic radii of the substituted as well as the replacing ions. Observed variations in saturation magnetization and initial permeability for these ferrites have been explained on the basis of anisotropy contribution for cobalt and segregation of copper at grain boundaries evident from scanning electron micrographs.

  9. Domain wall pinning in FeCoCu bamboo-like nanowires

    Science.gov (United States)

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

    2016-07-01

    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.

  10. Impact of CrSiTi and NiSi on the Thermodynamics, Microstructure, and Properties of AlCoCuFe-Based High-Entropy Alloys

    Science.gov (United States)

    Wang, Xiao-Rong; Wang, Zhao-Qin; Lin, Tie-Song; He, Peng; Sekulic, Dusan P.

    2016-05-01

    Aiming to solve the problem of spontaneous combustion on titanium via electrospark deposition (ESD), two AlCoCuFe-based high-entropy alloys (HEAs), AlCoCuFe- x ( x = CrSiTi, NiSi), were produced by vacuum arc melting as electrodes in ESD process. The thermodynamic analysis of AlCoCuFe-based HEAs were carried out using the concept of mixing enthalpy matrix and a powerful thermodynamic calculation toolbox (HEA-Thermo-Calcu). The microstructure and mechanical properties of the two alloys were investigated. The AlCoCuFeCrSiTi alloy contains a body-centered cubic (BCC) phase and a face-centered cubic (FCC) phase. The AlCoCuFeNiSi alloy is composed of two BCC phases and an FCC phase. Addition of CrSiTi and NiSi to AlCoCuFe-based alloys makes the enthalpy of mixing to be sizably more negative than for the other AlCoCuFe-based HEAs. Notwithstanding the fact that the thermodynamic parameters do not agree with Yang's proposition, the two alloys form simple solid solutions. The electronegativity difference (Δ χ) favors a formation of the solid solution when Δχ ≤ 14.2. The hardness of AlCoCuFe- x ( x = CrSiTi, NiSi) alloys reaches 935 HV and 688 HV, respectively. The yield strength, fracture strength, and ultimate strain of AlCoCuFeNiSi are larger, i.e., 29, 30, and 45%, respectively, than those of the AlCoCuFeCrSiTi alloy.

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

    Institute of Scientific and Technical Information of China (English)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Pang, S.J. [Department of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China); Department of Physics and Materials Science, City University of Hong Kong (Hong Kong); Shek, C.H. [Department of Physics and Materials Science, City University of Hong Kong (Hong Kong); Asami, K. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Inoue, A. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Zhang, T. [Department of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China)]. E-mail: zhangtao@buaa.edu.cn

    2007-05-31

    Bulk glassy Ni{sub 55}Nb{sub 20}Ti{sub 10}Zr{sub 8}Co{sub 7} 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 H{sub 2}SO{sub 4} solutions was recognized for the glassy alloys Ni{sub 55}Nb{sub 20}Ti{sub 10}Zr{sub 8}Co{sub 7} together with Ni{sub 53}Nb{sub 20}Ti{sub 10}Zr{sub 8}Co{sub 6}Cu{sub 3} which possesses higher glass-forming ability. They are spontaneously passivated with low passive current densities of the order of 10{sup -2} A/m{sup 2} and their corrosion rate was less than 10{sup -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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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}.

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

    Directory of Open Access Journals (Sweden)

    D. Aravinthan

    2015-07-01

    Full Text Available 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 × 1012Am−2. Also, the presence of orange peel coupling reduces the critical current required to initiate switching, and in this case, from 1.65 × 1012Am−2 to 1.39 × 1012Am−2.

  15. Correlation of magnetotransport and structure in sputtered Co/Cu multilayers

    CERN Document Server

    Paul, A; Bürgler, D E; Stein, S; Kohlstedt, H; Grünberg, P A

    2003-01-01

    Magnetic multilayer structures of Co/Cu prepared by dc magnetron sputtering are studied with respect to changing number of bilayers (N) for different thicknesses of the Cu spacer layer corresponding to different coupling conditions according to the oscillatory interlayer exchange coupling. X-ray reflectivity and diffuse scattering show that the multilayers become smoother with increasing N. The growth exponent of the roughness is found to be lower for a multilayer than for a single-layer film of similar thickness. The roughness of subsequent interfaces along the stack is conformal, and the lateral correlation does not change with the period number, but depends on the thickness of the spacer layers. The improved layer structure for larger N increases the antiferromagnetic coupling fraction as inferred from magneto-optic Kerr effect measurements and thereby increases the giant magnetoresistance (GMR) ratio up to 35% for N = 10. Thus, the first few bilayers do not contribute to the GMR but act as a buffer to imp...

  16. Influence of sample width on the magnetoresistance and planar Hall effect of Co/Cu multilayers

    Science.gov (United States)

    C. Lima, S.; Baibich, M. N.

    2016-01-01

    We have studied Co/Cu multilayers to understand the effect of the sample's width on their magnetoresistance (MR). By keeping constant both the length and the thickness and exploring the widths within the range of usual magnetic domain sizes in those nanostructures, we were able to observe effects on the MR curve, as well as infer linked changes in the magnetization process. Associating MR and Planar Hall Effect (PHE) measurements, coupled to an analysis of the MR plots' symmetry, we were able to establish that, apart from the expected antiferromagnetic coupling, reducing the width forces the magnetization to stay aligned to the current channel, thus inducing more symmetric, closer to model Giant Magnetoresistance (GMR). Also, the sample edges might contribute by adding extra coupling through magnetostatic interaction. The added effects result in a counter-intuitive trend that goes from the near ideal wide samples through intermediate sizes with fairly abrupt changes in MR, and finally to the closer to bell-shaped ideal GMR at narrow widths.

  17. Selective removal and patterning of a Co/Cu/Co trilayer created by femtosecond laser processing

    Energy Technology Data Exchange (ETDEWEB)

    Ulmeanu, M.; Filipescu, M.; Scarisoreanu, N.D.; Georgescu, G.; Rusen, L.; Zamfirescu, M. [National Institute for Laser, Plasma and Radiation Physics, Laser Department, Atomistilor Str. 409, P.O. Box MG-36, Magurele-Bucharest (Romania)

    2011-07-15

    The selective removal and patterning of a typical pseudo-spin-valve structure, consisting of a Co(20 nm)/ Cu(6 nm)/Co(3 nm) trilayer, by femtosecond laser has been examined in terms of irradiation parameters and layer structure. Ablation thresholds of the individual Co and Cu thin films and the SiO{sub 2}/Si substrate have been measured for single-shot irradiation with a 200 femtosecond (fs) laser pulses of a Ti:sapphire laser operating at 775 nm. Ablation of the entire trilayer structure was characterized by a sequential removal of the layers at a threshold level of fluence of 0.28 J/cm{sup 2}. Atomic Force Microscopy, optical microscopy, profilometry and Sputtered Neutral Mass Spectroscopy were employed to characterize the laser-induced single-shot laser selective removal and patterned areas. As a result, two phenomena were found to characterize the laser process: (i) selective removal of the Co and Cu layer due to the change of the laser fluence and (ii) regular pillars' area of Co/Cu/Co could be achieved in a regular manner with the lowest pillar width size of 1.5 {mu}m. Ablation through the layers was accompanied by the formation of bulges at the edges of the pillars, which was the biggest inconvenience in lowering the pillar size through the femtosecond laser process. (orig.)

  18. Effects of magnetic field orientation and injected current density on the output of nano-structured Co/Cu/Fe junctions

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Co/Cu/Fe nano-sized sandwich thin films have been prepared by electron beam evaporation. 5 μm×5 μm Co/Cu/Fe sandwich heterojunction was made using photolithography and lift-off process. The bipolar output signal of Co/Cu/Fe junctions has been measured and analyzed. The effects of applied magnetic field angle (referring to the normal of the junction plane) and injecting spin-polarized current on the output signals have been studied, and the measured results were discussed.

  19. Structural and magnetic studies of CoCu granular alloy obtained by ion implantation of Co into a Cu matrix

    Energy Technology Data Exchange (ETDEWEB)

    Errahmani, H.; Berrada, A.; Colis, S.; Schmerber, G.; Dinia, A. E-mail: aziz@ipcms.u-strasbg.fr; Muller, D

    2001-05-01

    CoCu granular alloys have been prepared at room temperature using ion implantation of Co{sup +} ions into Cu host at 160 keV. The Cu layer has been deposited on silicon substrate by DC sputtering at room temperature. The as-implanted and annealed CoCu alloys at different temperatures have been characterized by X-ray diffraction, Rutherford back scattering (RBS) for the structural properties, resistivity and magnetization measurements for the magneto-transport properties. Magnetization measurements show a classical superparamagnetic behavior as expected for granular alloy. The observation of the giant magnetoresistance (GMR) at 300 deg. C annealing temperature indicates the beginning of Co phase decomposition. The decrease of the GMR at high annealing temperature is due to the atomic Co and Cu diffusion into Si substrate as supported by X-ray and RBS analysis.

  20. Magnetic anisotropy and magneto optical property of Fe/Co/Cu(001): role of the interface alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dongyoo; Yang, Jeonghwa; Hong, Jisang [Pukyong National University, Busan (Korea, Republic of)

    2010-01-15

    Using the full potential linearized augmented plane wave (FLAPW) method, we have investigated the role of interface alloy type on the thickness dependent magnetic properties of ultrathin Fe/Co/Cu(001) films. We have observed that the Co underlayer induces an antiferromagnetic (AFM) state in Fe/Co/Cu(001) film, but the position of AFM layer is strongly sensitive to both Fe and Co coverage. It is found that the magnetic anisotropy of Fe/Co/Cu alloy films is significantly influenced by the alloy type and the Fe film thickness. For instance, a thickness-dependent spin reorientation transition from in-plane to perpendicular to the film surface or vice versa is observed in CoFe alloy configuration whereas the perpendicular magnetization is always achieved in CuCo alloy. In particular, a large perpendicular magnetic anisotropy energy (MAE) about 270 {mu}eV /atom at 4 ML Fe thickness is observed in the CuCo alloy. In addition, we find that the magnitude of Kerr rotation angle in the presence of antiferromagnetic layer is greatly suppressed compared with that of fully ferromagnetic films.

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

    Science.gov (United States)

    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.

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

    Institute of Scientific and Technical Information of China (English)

    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.

  3. Al元素对AlxFeCrCoCuV高熵合金组织及摩擦性能的影响%Effects of Al Addition on Microstructure and Wear Properties of AlxFeCrCoCuV High-entropy Alloys

    Institute of Scientific and Technical Information of China (English)

    谢红波; 刘贵仲; 郭景杰; 周敏; 刘德飘; 毛炜乾

    2016-01-01

    采用非自耗电弧熔炼炉制备了AlxFeCrCoCuV(x=0,0.5,1.0)多组元高熵合金.用XRD,SEM,EDS和DSC技术探究了合金的微观组织,并测试了其硬度及耐磨性能.研究表明:随着Al的加入,Al0.5 FeCrCoCuV合金和Al1.0 FeCrCoCuV合金由FeCrCoCuV合金单一的BCC相变为由枝晶BCC和晶间FCC共同组成的双相组织;Al1.0 FeCrCoCuV合金的硬度大于Al0.5 FeCrCoCuV合金.合金的摩擦磨损测试主要以黏着磨损为主,合金的耐磨性能与硬度成正比.3种合金的摩擦因数都是随着时间的增加而减小,主要原因是随着摩擦时间的增加,合金表面生成了一层氧化物提高了合金的耐磨性能.%The AlxFeCrCoCuV (x= 0 ,0 .5 ,1 .0 )high-entropy alloys were fabricated by non-consuma-ble vacuum arc melting furnace,the characteristics including microstructure,hardness and wear prop-erties were examined by XRD,SEM,EDS and DSC.The results show that with the addition of aluminum,Al0.5 CrFeCoCuV and Al1.0 CrFeCoCuV alloys from single BCC phase of FeCrCoCuV to a transition duplex FCC/BCC phase;the hardness of Al1.0 CrFeCoCuV alloy is larger than Al0.5 CrFe-CoCuV alloy.The alloys show adhesive wear behaviors,the wear-resisting performance of the alloys is proportional to its hardness.With the increase of friction time,the three alloys generate a layer of oxide on the surface and attach to the friction surfaces to improve the wear resistance.

  4. Effect of Ti content on structure and properties of Al{sub 2}CrFeNiCoCuTi{sub x} high-entropy alloy coatings

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, X.W., E-mail: fallenrain922@163.com [School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710048 (China); Sichuan College of Architectural Technology, Deyang 618000 (China); Zhang, Y.P. [School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710048 (China); Liu, C.G. [Sichuan College of Architectural Technology, Deyang 618000 (China)

    2014-02-05

    Highlights: • Al{sub 2}CrFeNiCoCuTi{sub x} high-entropy alloy coatings were prepared by laser cladding. • Al{sub 2}CrFeNiCoCuTi{sub x} coatings show excellent corrosion resistance and wear resistance. • Al{sub 2}CrFeNiCoCuTi{sub x} coatings play a good protective effect on Q235 steel. • Ti element promotes the formation of a BCC structure in a certain extent. -- Abstract: The Al{sub 2}CrFeNiCoCuTi{sub x} high-entropy alloy coatings were prepared by laser cladding. The structure, hardness, corrosion resistance, wear resistance and magnetic property were studied by metallurgical microscope, scanning electron microscopy with spectroscopy (SEM/EDS), X-ray diffraction, micro/Vickers hardness tester, electrochemical workstation tribometer and multi-physical tester. The result shows that, Al{sub 2}CrFeNiCoCuTi{sub x} high-entropy alloy samples consist of the cladding zone, bounding zone, heat affected zone and substrate zone. The bonding between the cladding layer and the substrate of a good combination; the cladding zone is composed mainly of equiaxed grains and columnar crystal; the phase structure of Al{sub 2}CrFeNiCoCuTi{sub x} high-entropy alloy coatings simple for FCC, BCC and Laves phase due to high-entropy affect. Ti element promotes the formation of a BCC structure in a certain extent. Compared with Q235 steel, the free-corrosion current density of Al{sub 2}CrFeNiCoCuTi{sub x} high-entropy alloy coatings is reduced by 1–2 orders of magnitude, the free-corrosion potential is more “positive”. With the increasing of Ti content, the corrosion resistance of Al{sub 2}CrFeCoCuNiTi{sub x} high-entropy alloy coatings enhanced in 0.5 mol/L HNO{sub 3} solution. Compared with Q235 steel, the relative wear resistance of Al{sub 2}CrFeCoCuNiTi{sub x} high-entropy alloy coatings has improved greatly; both the hardness and plasticity are affecting wear resistance. Magnetization loop shows that, Ti{sub 0.0} high-entropy alloy is a kind of soft magnetic materials.

  5. Analysis of spin transfer torque in Co/Cu/Co pseudo-spin-valve with perpendicular magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Jalil, Mansoor Bin Abdul, E-mail: elembaj@nus.edu.s [Information Storage Materials Laboratory, Electrical and Computer Engineering Department, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Guo, Jie, E-mail: elegj@nus.edu.s [Information Storage Materials Laboratory, Electrical and Computer Engineering Department, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Tan, Seng Ghee, E-mail: TAN_Seng_Ghee@dsi.a-star.edu.s [Data Storage Institute, 5 Engineering Drive 1, (Off Kent Ridge Crescent), Singapore 117608 (Singapore)

    2009-05-01

    Perpendicular-magnetized pseudo-spin-valves (PSV) boast the advantages of lower aspect ratio, greater magnetic stability and thermal stability; and hence constitute a promising candidate for achieving higher integration area density. In this paper, we investigate the spin transport and spin transfer torque in a Co/Cu(1 1 1)/Co perpendicular PSV structure where the magnetization of the Co layers are oriented in the out-of-plane direction, in the presence of a spin-polarized current in the perpendicular-to-plane (CPP) geometry. Both ballistic spin-dependent transmission/reflection at the two Co-Cu interfaces and diffusive spin relaxation within the Co and Cu layers are considered in our model. The ballistic calculations predict an absorbed spin current component at the Cu-free Co interface, which constitutes the main source (approx90%) of the total spin transfer torque in the free Co layer. The remaining torque arises from the spin relaxation of transmitted spin current within the free Co layer. Our model predicts a lower range of the critical current density of less than 10{sup 7} A/cm{sup 2} for perpendicularly magnetized PSVs, while that for in-plane magnetized PSVs is of the order of several 10{sup 7} A/cm{sup 2}. Additionally, perpendicularly magnetized PSVs also possess other practical advantages which make them promising candidates for future MRAM applications.

  6. Microstructure and properties of Al{sub 2}CrFeCoCuTiNi{sub x} high-entropy alloys prepared by laser cladding

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Xing-Wu, E-mail: fallenrain922@163.com [Department of Materials Engineering, Sichuan College of Architectural Technology, Deyang 618000 (China); Liu, Chun-Ge [Department of Transportation and Municipal Engineering, Sichuan College of Architectural Technology, Deyang 618000 (China)

    2013-03-15

    Highlights: ► We use a new method (laser cladding) to prepare Al{sub 2}CrFeCoCuTiNi{sub x} high-entropy alloys. ► We studied the effect of Ni content on alloys’ properties. ► Alloys show high microhardness, excellent corrosion resistance and wear resistance. ► The laser cladding layers play a good protective effect on Q235 steel. -- Abstract: The Al{sub 2}CrFeCoCuTiNi{sub x} high-entropy alloys were prepared by laser cladding. Using metallurgical microscope, scanning electron microscopy with spectroscopy (SEM/EDS), X-ray diffraction, micro/Vickers hardness tester, electrochemical workstation and tribometer the structure and hardness, corrosion resistance and wear resistance of Al{sub 2}CrFeCoCuTiNi{sub x} high-entropy alloys were tested. The result shows that, Al{sub 2}CrFeCoCuTiNi{sub x} high-entropy alloy samples consist of the cladding zone, bounding zone and heat affected zone. The bounding zone is between cladding layer and the substrate of a good combination; the cladding zone is composed mainly of axis crystal, nanocrystalline and fine white crystals. The Al{sub 2}CrFeCoCuTiNi{sub x} high-entropy alloys coating phase structure samples (FCC and BCC structure) due to high-entropy effect. The surface microhardness of Al{sub 2}CrFeCoCuTiNi{sub x} high-entropy alloys samples up to 1102 HV, about 4 times as the substrate, and the hardness increases with increasing Ni content. Al{sub 2}CrFeCoCuTiNi{sub x} high-entropy alloys coating has good corrosion resistance in 1 mol/L NaOH solution and 3.5% NaCl solution. With the increase of Ni content, the corrosion resistance first increases and then decreases. The relative wear resistance of Al{sub 2}CrFeCoCuTiNi{sub x} high-entropy alloys coating shows a first increased and then a decreased trend with the increase of Ni content. Both the hardness and ductility are affected by wear resistance. The coating can play a good protective role on substrate Q235 steel.

  7. Lateral electric-field control of giant magnetoresistance in Co/Cu/Fe/BaTiO{sub 3} multiferroic heterostructure

    Energy Technology Data Exchange (ETDEWEB)

    Savitha Pillai, S.; Kojima, H.; Itoh, M.; Taniyama, T., E-mail: taniyama.t.aa@m.titech.ac.jp [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama 226-8503 (Japan)

    2015-08-17

    We report lateral electric-field-driven sizable changes in the magnetoresistance of Co/Cu/Fe tri-layered wires on BaTiO{sub 3} single crystal. While the observed change is marginal in the tetragonal phase of BaTiO{sub 3}, 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 BaTiO{sub 3}. The contrasting results for the different phases of BaTiO{sub 3} are discussed, associated with the distinct aspects of the ferroelectric polarization switching processes in each phase.

  8. Crystallographic Features and State Stability of the Decagonal Quasicrystal in the Al-Co-Cu Alloy System

    Science.gov (United States)

    Nakayama, Kei; Mizutani, Akito; Koyama, Yasumasa

    2016-11-01

    In the Al-Co-Cu alloy system, both the decagonal quasicrystal with the space group of Poverline{10}m2 and its approximant Al13Co4 phase with monoclinic Cm symmetry are present around 20 at. % Co-10 at. % Cu. In this study, we examined the crystallographic features of prepared Al-(30 - x) at. % Co-x at. % Cu samples mainly by transmission electron microscopy in order to make clear the crystallographic relation between the decagonal quasicrystal and the monoclinic Al13Co4 structure. The results revealed a coexistence state consisting of decagonal quasicrystal and approximant Al13Co4 regions in Al-20 at. % Co-10 at. % Cu alloy samples. With the help of the coexistence state, the orientation relationship was established between the monoclinic Al13Co4 structure and the decagonal quasicrystal. In the determined relationship, the crystallographic axis in the quasicrystal was found to be parallel to the normal direction of the (010)m plane in the Al13Co4 structure, where the subscript m denotes the monoclinic system. Based on data obtained experimentally, the state stability of the decagonal quasicrystal was also examined in terms of the Hume-Rothery (HR) mechanism on the basis of the nearly-free-electron approximation. It was found that a model based on the HR mechanism could explain the crystallographic features such as electron diffraction patterns and atomic arrangements found in the decagonal quasicrystal. In other words, the HR mechanism is most likely appropriate for the stability of the decagonal quasicrystal in the Al-Co-Cu alloy system.

  9. Lattice effects of surface cell: Multilayer multiconfiguration time-dependent Hartree study on surface scattering of CO/Cu(100)

    Science.gov (United States)

    Meng, Qingyong; Meyer, Hans-Dieter

    2017-05-01

    To study the scattering of CO off a movable Cu(100) surface, extensive multilayer multiconfiguration time-dependent Hartree (ML-MCTDH) calculations are performed based on the SAP [R. Marquardt et al., J. Chem. Phys. 132, 074108 (2010)] potential energy surface in conjunction with a recently developed expansion model [Q. Meng and H.-D. Meyer, J. Chem. Phys. 143, 164310 (2015)] for including lattice motion. The surface vibration potential is constructed by a sum of Morse potentials where the parameters are determined by simulating the vibrational energies of a clean Cu(100) surface. Having constructed the total Hamiltonian, extensive dynamical calculations in both time-independent and time-dependent schemes are performed. Two-layer MCTDH (i.e., normal MCTDH) block-improved-relaxations (time-independent scheme) show that increasing the number of included surface vibrational dimensions lets the vibrational energies of CO/Cu(100) decrease for the frustrated translation (T mode), which is of low energy but increase those of the frustrated rotation (R mode) and the CO-Cu stretch (S mode), whose vibrational energies are larger than the energies of the in-plane surface vibrations (˜79 cm-1). This energy-shifting behavior was predicted and discussed by a simple model in our previous publication [Q. Meng and H.-D. Meyer, J. Chem. Phys. 143, 164310 (2015)]. By the flux analysis of the MCTDH/ML-MCTDH propagated wave packets, we calculated the sticking probabilities for the X + 0D, X + 1D, X + 3D, X + 5D, and X + 15D systems, where "X" stands for the used dimensionality of the CO/rigid-surface system and the second entry denotes the number of surface degrees of freedom included. From these sticking probabilities, the X + 5D/15D calculations predict a slower decrease of sticking with increasing energy as compared to the sticking of the X + 0D/1D/3D calculations. This is because the translational energy of CO is more easily transferred to surface vibrations, when the vibrational

  10. The effects of shape anisotropy and exchange coupling on spin precession frequencies in exchange coupled Co/Cu/Py trilayers

    Science.gov (United States)

    Keramati, Sam; Singh, Uday; Kurfman, Seth; Binek, Ch.; Adenwalla, S.

    2015-03-01

    Ultrafast high-power laser systems have successfully opened up the field of magnetization dynamics, studying subpicosecond laser-induced spin precession dynamics, demagnetization processes and magnetization reorientation. Here we investigate laser-induced magnetization dynamics in a series of photolithographically patterned microstructures of exchange coupled trilayers of Co/Cu/Py grown on Si substrates. The microstructures have different shape anisotropies as well as different exchange coupling parameters. The latter determines the magnetization state, varying from ferromagnetically to anti-ferromagnetically coupled. We explore how the different spin precession frequencies of the constituent exchange coupled magnetic layers with unequal relaxation times can trade-off with the differing shape anisotropies. The key physical point is that the precession frequency of ferromagnetic materials and their damping parameter vary with the effective field which depends on both the shape anisotropy, and exchange coupling, while their corresponding effects can be modulated through the action of the intense pump beam. Precession frequency maps of the behavior of the exchange coupling parameter of the samples with respect to their shape anisotropy and their laser-induced modulated precession frequencies will be generated through a pump-probe experiment to address the above-mentioned objective of our work. This work is supported by NSF Grant No. 1409622 and MRSEC DMR-0820521.

  11. Perpendicular Giant Magnetoresistance and Magnetic Properties of Co/Cu Nanowire Arrays Affected by Period Number and Copper Layer Thickness

    Directory of Open Access Journals (Sweden)

    Juan Han

    2016-01-01

    Full Text Available One-dimensional magnetic nanowires have attracted much attention in the last decades due to their unique physical properties and potential applications in magnetic recording and spintronics. In this work, ordered arrays of Co/Cu multilayered nanowires which can be exploited to develop magnetoresistive sensors were successfully prepared using porous anodic alumina (PAA templates. The structure and morphology of the multilayered nanowire arrays were characterized by transmission electron microscopy and scanning electron microscopy. The nanowire arrays are highly ordered and the average diameter is about 50 nm, which is controlled by the pore diameter of the PAA templates. The influences of period number and Cu layer thickness on the magnetic and the giant magnetoresistance (GMR properties were investigated. The coercivity and remanence ratio increase first and then gradually tend to be stable with the increase of period number and the Cu layer thickness, while the GMR ratio increases first and then decreases with the increase of the period number accompanied by an oscillatory behavior of GMR as the Cu layer thickness changes, which are ascribed to the spin dependence electron scattering in the multilayers. The optimum GMR of −13% appears at Co (50 nm/Cu (5 nm with 200 deposition cycles in our experimental conditions.

  12. Effect of Zr Addition on Microstructure and Corrosion Properties of AlFeCrCoCuZrx High-entropy Alloys

    Directory of Open Access Journals (Sweden)

    XIE Hong-bo

    2016-06-01

    Full Text Available The microstructure, hardness and the corrosion resistance in 3.5% NaCl solution of the as-cast AlFeCrCoCuZrx(x=0, 0.5, 1 high-entropy alloys were investigated. The results show that typically cast dendrite structure is formed in the alloys. With the increase of Zr addition, phases in the dendrite region change from single BCC structure to two phases, while phase in the interdendrite region is Cu-rich FCC structure and kept unchanged. The hardness of the alloys increases with the increase of Zr addition and hardness AlFeCrCoCuZr alloy reaches the maximum of HV 698. The corrosion resistance of these alloys in 3.5% NaCl solution is better than that of 304L stainless steel, however as the Zr content increases, the corrosion resistance of alloys is degenerated.

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

    Science.gov (United States)

    Meng, Qingyong; Meyer, Hans-Dieter

    2015-10-28

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Qingyong, E-mail: mengqingyong@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, 116023 Dalian (China); Meyer, Hans-Dieter, E-mail: hans-dieter.meyer@pci.uni-heidelberg.de [Theoretische Chemie, Physikalisch-Chemisches Institut, Ruprecht-Karls Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg (Germany)

    2015-10-28

    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.

  15. [Quantitative surface analysis of Pt-Co, Cu-Au and Cu-Ag alloy films by XPS and AES].

    Science.gov (United States)

    Li, Lian-Zhong; Zhuo, Shang-Jun; Shen, Ru-Xiang; Qian, Rong; Gao, Jie

    2013-11-01

    In order to improve the quantitative analysis accuracy of AES, We associated XPS with AES and studied the method to reduce the error of AES quantitative analysis, selected Pt-Co, Cu-Au and Cu-Ag binary alloy thin-films as the samples, used XPS to correct AES quantitative analysis results by changing the auger sensitivity factors to make their quantitative analysis results more similar. Then we verified the accuracy of the quantitative analysis of AES when using the revised sensitivity factors by other samples with different composition ratio, and the results showed that the corrected relative sensitivity factors can reduce the error in quantitative analysis of AES to less than 10%. Peak defining is difficult in the form of the integral spectrum of AES analysis since choosing the starting point and ending point when determining the characteristic auger peak intensity area with great uncertainty, and to make analysis easier, we also processed data in the form of the differential spectrum, made quantitative analysis on the basis of peak to peak height instead of peak area, corrected the relative sensitivity factors, and verified the accuracy of quantitative analysis by the other samples with different composition ratio. The result showed that the analytical error in quantitative analysis of AES reduced to less than 9%. It showed that the accuracy of AES quantitative analysis can be highly improved by the way of associating XPS with AES to correct the auger sensitivity factors since the matrix effects are taken into account. Good consistency was presented, proving the feasibility of this method.

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

    Institute of Scientific and Technical Information of China (English)

    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.

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

    CERN Document Server

    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...

  18. Spin-orbit torques and spin accumulation in FePt/Pt and Co/Cu thin films from first principles: The role of impurities

    Science.gov (United States)

    Géranton, Guillaume; Zimmermann, Bernd; Long, Nguyen H.; Mavropoulos, Phivos; Blügel, Stefan; Freimuth, Frank; Mokrousov, Yuriy

    2016-06-01

    Using the Boltzmann formalism based on the first principles electronic structure and scattering rates, we investigate the current-induced spin accumulation and spin-orbit torques in FePt/Pt and Co/Cu bilayers in the presence of substitutional impurities. In FePt/Pt bilayers we consider the effect of intermixing of Fe and Pt atoms in the FePt layer and find a crucial dependence of spin accumulation and spin-orbit torques on the details of the distribution of these defects. In Co/Cu bilayers we predict that the magnitude and sign of the spin-orbit torque and spin accumulation depend very sensitively on the type of the impurities used to dope the Cu substrate. Moreover, simultaneously with impurity-driven scattering, we consider the effect of an additional constant quasiparticle broadening of the states at the Fermi surface to simulate phonon scattering at room temperature and discover that even a small broadening of the order of 25 meV can drastically influence the magnitude of the considered effects. We explain our findings based on the analysis of the complex interplay of several competing Fermi surface contributions to the spin accumulation and spin-orbit torques in these structurally and chemically nonuniform systems.

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

    Science.gov (United States)

    Li, Yue-sheng; Zhang, Qing-ming

    2013-01-16

    We have successfully synthesized S = 1/2 kagome antiferromagnets MCu(3)(OH)(6)Cl(2) (M = Ni and Co) by a hydrothermal method with a rotating pressure vessel. Structural characterization shows that both compounds have similar crystal structure to ZnCu(3)(OH)(6)Cl(2) with R3m symmetry. As with ZnCu(3)(OH)(6)Cl(2), the compounds show no obvious hysteresis at 2 K. A spin-glass transition is found in both NiCu(3)(OH)(6)Cl(2) and CoCu(3)(OH)(6)Cl(2) 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 Zn(2+) by magnetic ions Ni(2+) or Co(2+) effectively enhances the interlayer exchange coupling and changes the ground state of the kagome spin system.

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

    Science.gov (United States)

    Li, Yue-sheng; Zhang, Qing-ming

    2013-01-01

    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\\bar {3}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.

  1. Direct simultaneous determination of Co, Cu, Fe, Ni and V in pore waters by means of adsorptive cathodic stripping voltammetry with mixed ligands.

    Science.gov (United States)

    Santos-Echeandía, Juan

    2011-07-15

    An analytical procedure is proposed for the direct simultaneous determination in a single scan of Co, Cu, Fe, Ni and V in sediment pore waters by means of adsorptive cathodic stripping voltammetry (ACSV) with mixed ligands (DMG and catechol). Optimum conditions for the determination of these five elements were studied. Detection limits of the technique depended upon the reproducibility of the procedure blank, and were found to be 0.04 nM Co, 0.09 nM Cu, 1.29 nM Fe, 0.46 nM Ni and 2,52 nMV making the method suitable for the direct simultaneous determination of these five metals in pore waters, estuarine waters and probably coastal waters. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. Fast emulsion-based method for simultaneous determination of Co, Cu, Pb and Se in crude oil, gasoline and diesel by graphite furnace atomic absorption spectrometry.

    Science.gov (United States)

    Luz, Maciel S; Nascimento, Angerson N; Oliveira, Pedro V

    2013-10-15

    A method for the simultaneous determination of Co, Cu, Pb and Se in crude oil, gasoline and diesel samples using emulsion-based sampling and GF AAS is proposed. 400mg of sample was weighted in volumetric flask following the sequential addition of 125 µL of hexane and 7.5 mL of Triton X-100(®) (20% mv(-1)). Subsequently, the mixture was stirred in ultrasonic bath, during 30 min, before dilution to 25 mL with deionized water. Aliquots of 20 μL of reference solution or sample emulsion were co-injected into the graphite tube with 10 μL of 2 g L(-1) Pd(NO3)2. The pyrolysis and atomization temperatures were 1300°C and 2250°C, respectively. The limits of detection (n=10, 3σ) and characteristic masses were 0.02 μg g(-1) (0.32 μg L(-1)) and 18 pg for Co, 0.03 μg g(-1) (0.48 μg L(-1)) and 15 pg for Cu, 0.04 μg g(-1) (0.64 μg L(-1)) and 48 pg for Pb, and 0.11 μg g(-1) (1.76 μg L(-1)) and 47 pg for Se. The reliabilities of the proposed method for Co and Se were checked by SRM(®) 1634c Residual Oil analysis. The found values are in accordance to the SRM at 95% confidence level (Student's t-test). Each sample was spiked with 0.18 μg g(-1) of Co, Cu, Pb and Se and the recoveries varied from 92% to 116% for Co, 83% to 117% for Cu, 72% to 117% for Pb, and 82% to 122% for Se.

  3. 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

    Science.gov (United States)

    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

  4. Electronic, magnetic and spectroscopic properties of doped Mn(1-x) A x WO4 (A  =  Co, Cu, Ni and Fe) multiferroic: an experimental and DFT study

    Science.gov (United States)

    Mal, Priyanath; Bera, G.; Rambabu, P.; Turpu, G. R.; Chakraborty, Brahmananda; Ramaniah, Lavanya M.; Singh, R. P.; Sen, Pintu; Das, Pradip

    2017-02-01

    The influence of dopants (Co, Cu, Fe and Ni) on the optical, electronic and magnetic properties of multiferroic MnWO4 was studied using Raman spectroscopy, ultraviolet-visible spectroscopy (UV-Vis), magnetization measurements and density functional theory (DFT) calculations. The evolution of Raman spectra with different elemental substitutions at the Mn site was also studied, where the peak width increased with doping of higher mass elements (Co, Cu, Fe and Ni). UV-Vis diffuse reflectance spectroscopy on polycrystalline Mn(1-x) A x WO4 (A  =  Co, Cu, Fe and Ni) (0  ⩽  x   ⩽  0. was performed. The evaluated electronic band gap decreasing with successive Co, Cu and Fe doping reflected the lower ionic radius of the substituted element, and for Ni-doped MnWO4 the band gap increased slightly compared to the parent MnWO4. Bader charge transfer and a partial density of states (PDOS) analysis from DFT simulations predict the appearance of impurity states in the band gap region (of pure MnWO4) from the d orbital of the dopant (Co, Cu and Fe) hybridized with the p orbital of the bonded O atoms due to charge transfer from O to the dopant, and reduced the band gap of Co, Cu and Fe-doped MnWO4. On the other hand, for Ni-doped MnWO4 strong W-O hybridization occurring due to large charge transfer from oxygen to tungsten leads to an increase in the band gap. The band gap, computed using the GGA  +  U method, is close to the experimental value. The signature of the d-d transition observed in the UV spectra is explained in terms of the crystal field stabilization energy caused by the octahedral distortion present in the lattice. Three different antiferromagnetic phases (AF1, AF2 and AF3) are identified in MnWO4 and also for the Co (18.75%)-doped sample. For Cu-doped samples, suppression of the AF1 phase and stabilization of the AF2 phase is observed up to 2 K. Successive doping of Cu leads to the diminution of magnetic frustration. A new

  5. Effect of Doping Cerium in the Support of Catalyst Pd-Co/Cu-Co-Mn Mixed Oxides on the Oxidative Carbonylation of Phenol%掺杂Ce对Pd-Co/Cu-Co-Mn混合氧化物催化体系氧化羰基化法合成碳酸二苯酯

    Institute of Scientific and Technical Information of China (English)

    梁英华; 郭红霞; 陈红萍; 吕敬德; 张波波

    2009-01-01

    Effect of doping cerium in the support on the catalytic activity and side product of the reaction in the oxidative carbonylation of phenol to diphenyl carbonate (DPC) over the catalyst Pd-Co/Cu-Co-Mn mixed oxides was studied. The specific surface areas, crystal phase, valency, and content of the element on the surface of the catalysts were determined, and the products were detected by gas chromatograph/mass spectrometry (GC-MS). It is found that the catalyst without Ce shows higher activity than that with Cc, and the yields of DPC for the two catalysts can reach 30% and 23%, respectively. However, doping cerium can prevent the formation of 2-hydroxyphenyl benzoate and p-bromophenyl phenyl carbonate.

  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

    Directory of Open Access Journals (Sweden)

    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

    Directory of Open Access Journals (Sweden)

    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. Analysis of molecular structure, spectroscopic properties (FT-IR, micro-Raman and UV-vis) and quantum chemical calculations of free and ligand 2-thiopheneglyoxylic acid in metal halides (Cd, Co, Cu, Ni and Zn).

    Science.gov (United States)

    Gökce, Halil; Bahçeli, Semiha

    2013-12-01

    In this study, molecular geometries, experimental vibrational wavenumbers, electronic properties and quantum chemical calculations of 2-thiopheneglyoxylic acid molecule, (C6H4O3S), and its metal halides (Cd, Co, Cu, Ni and Zn) which are used as pharmacologic agents have been investigated experimentally by FT-IR, micro-Raman and UV-visible spectroscopies and elemental analysis. Meanwhile the vibrational calculations were verified by DFT/B3LYP method with 6-311++G(d,p) and LANL2DZ basis sets in the ground state, for free TPGA molecule and its metal halide complexes, respectively, for the first time. The calculated fundamental vibrational frequencies for the title compounds are in a good agreement with the experimental data.

  9. FT-IR, micro-Raman and UV-vis spectroscopic and quantum chemical investigations of free 2,2'-dithiodipyridine and its metal (Co, Cu and Zn) halide complexes.

    Science.gov (United States)

    Gökce, Halil; Bahçeli, Semiha

    2013-10-01

    In this study the elemental analysis results, molecular geometries, vibrational and electronic absorption spectra of free 2,2'-dithiodipyridine(C10H8N2S2), (or DTDP) (with synonym, 2,2'-dipyridyl disulfide) and M(C10H8N2S2)Cl2 (M=Co, Cu and Zn) complexes have been reported. Vibrational wavenumbers of free DTDP and its metal halide complexes have been calculated by using DFT/B3LYP calculation method with 6-31++G(d,p) and Lanl2DZ basis sets, respectively, in the ground state, for the first time. The calculated fundamental vibrational frequencies are in a good agreement with experimental data. The HOMO, LUMO and MEP analyses of all compounds are performed by DFT method.

  10. 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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Ionic liquid-based dispersive liquid-liquid microextraction combined with high performance liquid chromatography-UV detection for simultaneous preconcentration and determination of Ni, Co, Cu and Zn in water samples

    Directory of Open Access Journals (Sweden)

    Asghari Alireza

    2014-01-01

    Full Text Available Ionic liquid-based dispersive liquid-liquid microextraction (IL-DLLME coupled with high performance liquid chromatography (HPLC-UV detection was developed for simultaneous extraction and determination of nickel, cobalt, copper and zinc ions. In the proposed approach, salophen (N,N'-bis(salisyliden-1,2-phenylenediamine was used as a chelating agent; the ionic liquid, 1-hexeyl-3-methylimidazolium hexafluorophosphate, and acetone were selected as extracting and dispersive solvents, respectively. After extraction, phase separation was performed by centrifugation and the sedimented phase (ionic liquid was solubilized in acetonitrile and directly injected into the HPLC for subsequent analysis. Baseline separation of metal ion complexes was achieved on a RP-C18 column using a gradient elution of the mixtures of methanol-acetonitrile-water as the mobile phase at a flow rate of 1.0 mL min-1. The influence of variables such as sample pH, concentration of the chelating agent, amount of ionic liquid (extraction solvent, disperser solvent volume, extraction time, salt effect and centrifugation speed were studied and optimized. Under the optimum conditions, the enrichment factor of 222 was obtained. The detection limits for Ni, Co, Cu and Zn were 0.8, 1.6, 1.9 and 2.8 μg L−1, respectively. The relative standard deviations (RSDs were in the range of 3.6-5.0 % for all of the investigated metal ions. The proposed procedure was successfully applied to the determination of the studied metal ions in water samples.

  12. Fluid sources and metallogenesis in the Blackbird Co-Cu-Au-Bi-Y-REE district, Idaho, U.S.A.: Insights from major-element and boron isotopic compositions of tourmaline

    Science.gov (United States)

    Trumbull, R.B.; Slack, J.F.; Krienitz, M.-S.; Belkin, H.E.; Wiedenbeck, M.

    2011-01-01

    Tourmaline is a widespread mineral in the Mesoproterozoic Blackbird Co-Cu-Au-Bi-Y-REE district, Idaho, where it occurs in both mineralized zones and wallrocks. We report here major-element and B-isotope compositions of tourmaline from stratabound sulfide deposits and their metasedimentary wallrocks, from mineralized and barren pipes of tourmaline breccia, from late barren quartz veins, and from Mesoproterozoic granite. The tourmalines are aluminous, intermediate in the schorl-dravite series, with Fe/(Fe + Mg) values of 0.30 to 0.85, and 10 to 50% X-site vacancies. Compositional zoning is prominent only in tourmaline from breccias and quartz veins; crystal rims are enriched in Mg, Ca and Ti, and depleted in Fe and Al relative to cores. The chemical composition of tourmaline does not correlate with the presence or absence of mineralization. The ??11B values fall into two groups. Isotopically light tourmaline (-21.7 to-7.6%o) occurs in unmineralized samples from wallrocks, late quartz veins and Mesoproterozoic granite, whereas heavy tourmaline (-6.9 to +3.2%o) is spatially associated with mineralization (stratabound and breccia-hosted), and is also found in barren breccia. At an inferred temperature of 300??C, boron in the hydrothermal fluid associated with mineralization had ??11B values of-3 to +7%o. The high end of this range indicates a marine source of the boron. A likely scenario involves leaching of boron principally from marine carbonate beds or B-bearing evaporites in Mesoproterozoic strata of the region. The ??11B values of the isotopically light tourmaline in the sulfide deposits are attributed to recrystallization during Cretaceous metamorphism, superimposed on a light boron component derived from footwall siliciclastic sediments (e.g., marine clays) during Mesoproterozoic mineralization, and possibly a minor component of light boron from a magmatic-hydrothermal fluid. The metal association of Bi-Be-Y-REE in the Blackbird ores suggests some magmatic input

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  14. 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

    Science.gov (United States)

    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

  15. 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

    Science.gov (United States)

    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

  16. Effect of composition of FeCoCu pre-alloyed powders on sintering characters used for diamond tools%金刚石工具用FeCoCu预合金粉组成对烧结特性的影响

    Institute of Scientific and Technical Information of China (English)

    谢德龙; 陈超; 肖乐银; 万隆; 宋冬冬; 王帅; 林峰; 吕智; 方啸虎; 潘晓毅; 秦海青

    2016-01-01

    The FeCoCu pre-alloyed powders were manufactured by co-precipitation method. The microstructure was characterized, the sintering experiments were carried out, the mechanical properties and wear loss were tested and the combination condition between diamond and the powders was analyzed. The results show that the mesophases, such as Co3Fe7, CoFe15.7 and FeCu4, are formulated in the three powders, and all the powders have irregular shapes, interconnected fine particles and large surface areas. Although the solid solutions are formed, the sintering, mechanical properties and mass loss of the three powders are based on the Fe-Cu ratios. With Fe content increasing, the ideal sintering temperatures, hardness and three point bend strength raise. The relative density decreases, the wear loss becomes better. Fe-Cu ratio has important influence on the powders microstructure. The mechanical retention is the main strength in the matrix and graphitization has occurred in the diamond surface after sintering with the FeCoCu pre-alloyed powders.%通过共沉淀法制备不同Fe-Cu配比的FeCoCu预合金粉,并对其微观结构进行表征与分析。同时,对3种粉体进行不同温度下的烧结实验和对烧结试样块进行力学性能及磨损质量损失进行测试,并对预合金粉与金刚石的界面结合情况进行探讨。结果表明:预合金粉中形成了Co3Fe7、CoFe15.7、FeCu4等中间相,在一定程度上实现合金化。3种预合金粉末的形状均为不规则状,粉末颗粒较细,且相互连接,表面疏松,有利于烧结。3种预合金粉中单质相仍占有较大比例,单质配比对烧结体性能有重要影响。Fe含量增加时,试样的理想烧结温度及烧结体力学性能均升高。Fe-Cu配比会对微观结构产生重要影响,胎体对金刚石以机械包镶为主,结合XRD及Raman光谱可知,与预合金粉烧结后的金刚石表面发生石墨化。

  17. Interfacial properties of immiscible Co-Cu alloys

    DEFF Research Database (Denmark)

    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......-rich core surrounded by a liquid copper-rich shell. Exciting drop oscillations and analysing the frequency spectrum, both surface and (liquid–liquid) interfacial tension can be derived from the observed oscillation frequencies. This paper briefly reviews the theoretical background and reports on a recent...

  18. Electronic Structures and Giant Magnetoresistance of Co/Cu Superlattices with Different Orientations

    Institute of Scientific and Technical Information of China (English)

    SHANG Jia-Xiang; ZHAO Xiao-Dan

    2006-01-01

    @@ The electronic structures of Co3 Cu3 superlattices with the orientations of (100), (110) and (111) are calculated by the first-principle method within the framework of the density functional theory. It has been found that the spin-dependent scattering and charge transfers are prominent at interfaces compared to the interior layers for the three orientation superlattices. We also evaluate the magnetoresistance ratio by using the two-current model The results show that the giant magnetoresistance ratio decreases in the order of (110), (100), (111) orientations for Co3Cu3 models (49. 4%, 37. 7%, 29.3%, respectively). Further analysis shows that an expansion of average atomic volume would enhance the magnetic moment of Co, which is consistent with other calculation and experimental results. In addition, the giant magnetoresistance effect is analysed from the point of charge transfer.

  19. Cu Diffusion in Co/Cu/TiN Films for Cu Metallization

    Institute of Scientific and Technical Information of China (English)

    Xiuhua CHEN; Xinghui WU; Jinzhong XIANG; Zhenlai ZHOU; Heyun ZHAO; Liqiang CHEN

    2006-01-01

    Some information on how to use in-situ determined diffusion coefficient of Cu to make barrier layer of Cu metallization in ultra large scale integrations (ULSIs) was provided. Diffusion coefficients of Cu in Co at low temperature were determined to analyze Cu migration to Co surface layer. The diffusion depths were analyzed using X-ray photoelectron spectroscopy (XPS) depth profile to investigate the diffusion effect of Cu in Co at different temperatures. The possible pretreatment temperature and time of barrier layer can be predicted according to the diffusion coefficients of Cu in Co.

  20. A facile synthesis of MPd (M = Co, Cu) nanoparticles and their catalysis for formic acid oxidation.

    Science.gov (United States)

    Mazumder, Vismadeb; Chi, Miaofang; Mankin, Max N; Liu, Yi; Metin, Önder; Sun, Daohua; More, Karren L; Sun, Shouheng

    2012-02-08

    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 PdBr(2) at 260 °C in oleylamine and trioctylphosphine, and their sizes (5-12 nm) and compositions (Co(10)Pd(90) to Co(60)Pd(40)) 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 HClO(4) and 2 M HCOOH solution, their catalytic activities followed the trend of Co(50)Pd(50) > Co(60)Pd(40) > Co(10)Pd(90) > Pd. The Co(50)Pd(50) NPs had an oxidation peak at 0.4 V with a peak current density of 774 A/g(Pd). As a comparison, commercial Pd catalysts showed an oxidation peak at 0.75 V with peak current density of only 254 A/g(Pd). 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 HClO(4) 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. © 2012 American Chemical Society

  1. Glass forming ability of Zr-Al-Ni(Co,Cu) understood via cluster sharing model

    Institute of Scientific and Technical Information of China (English)

    Jixiang Chen; Yi Cheng

    2014-01-01

    Clusters are shared atoms in different ways with their neighboring clusters in the crystalline phases. Cluster formula [effective cluster]1(glue atom)x can be used to describe crystalline phases, and the effective cluster means the true cluster composition due to cluster overlapping in the phase structure. Degree of cluster sharing of Zr6Al2Ni (InMg2), Zr2Co (Al2Cu) and Zr2Cu (MoSi2) phases is investigated in this paper. Ni3Zr9, Co3Zr8 and Cu5Zr10 clusters are highlighted because they have the least degree of sharing and can best represent the local atomic short-range order features of the formed phases. It is pointed out that the least sharing clusters are correlated with metallic glass formation and are verified by experiments.

  2. Magnetic and thermoelectrical measurement of multi-segmented Co/Cu nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Lie, Bastian; Boehnert, Tim; Kimling, Johannes; Nielsch, Kornelius [Institut fuer Angewandte Physik, Universitaet Hamburg, Hamburg (Germany)

    2010-07-01

    Nanostructures, e.g. modulated nanowires, reveal quantum effects due to their size which are advantageous for thermoelectrical applications. The thermoelectric properties depend on phonon- and electron-scattering in a material. We prepared high aspect-ratio multisegmented cobalt/copper nanowires and measured the thermal conductivity and the giant magnetoresistance (GMR). The desired approach for the preparation is the bottom-up method. In our case the single-bath-electrodepostion of cobalt and copper in eloxated alumina templates is applied by means of galvanostatic and potentiostatic deposition to fabricate alternating segments with a thickness of several nm's. The thickness of the copper layer is varied to validate the oscillation of the GMR-ratio dependent on the spin diffusion length. We present details of the sample processing, magnetoresistance measurements and 3{omega}-measurements.

  3. High-field magnetization process of granular Co-Cu alloys prepared by melt spinning

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    High solid-solubility Co15Cu35 alloys have been prepared by melt spinning and submitted to isothermal and anisothermal annealing to obtain granular alloys.The X-ray diffraction(XRD) patterns were measured to invesugate the decomposition of supersaturated solid solution induced by annealing.The atomic diffusion and structural evolution during the heat treatment were investigated.In view of the problems limiting their appllcation.the high-field magneazation curves were measured.By a fit to the high-field magnetization curves,the granuiar alloys are found hard to be magnetically saturated at the early stage of nucleation and growth.The magnetization behavior was correlaced to the annealed-induced structureal evolution and also to the magnetoresistance effect.

  4. Co-Cu-Zn-Pb-Ni-Cl-H2O体系的热力学分析%Thermodynamic Analysis of Co-Cu-Zn-Pb-Ni-Cl-H2O System

    Institute of Scientific and Technical Information of China (English)

    郭万根; 石玉臣; 王含渊; 张吉贵; 黄蕴成; 许新启

    2011-01-01

    根据配位化学热力学平衡原理,通过热力学平衡计算绘制出了298.15 K时钴电解液体系中5种金属离子(Co2+、Cu2+、Zn2+、pb2+、Ni2+)及其配离子的c-lg c[Cl]r图和c-pH图.热力学计算显示,pH为2.5时钴电解液中铅、锌主要以配合阴离子形式存在,钴、铜、镍主要以阳离子形式存在,可以采用阴离子树脂交换法将微量铅、锌与钴、铜、镍有效分离.对所绘的热力学平衡图分析表明,高浓度氯离子有利于与金属形成配合离子,提高铅锌的配合阴离子含量,有利于阴离子树脂交换除铅、锌.%c-lg c[cl]T and c-pH diagrams for complex ions(Co2+ ,Cu2+ ,Zn2+ ,Pb2+ ,Ni2+ ) at 298.15 K were drawn respectively based on the thermodynamic equilibrium principle of complex chemistry. The results show that in cobalt electrolysis solution, the occurrence states of cobalt, copper and nickel are free ions and complex cations at pH 2. 5, while the lead and zinc exist as complex anions which can be removed by anion exchange resin. In addition, the amount of complex anions of lead and zinc are increased with the improving of Cl- concentration, which is beneficial to the removing process of lead and zinc.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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.

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

    DEFF Research Database (Denmark)

    Owsianiak, Mikolaj; Holm, Peter E.; Fantke, Peter

    2015-01-01

    Metal exposure to terrestrial organisms is influenced by the reactivity of the solid-phase metal pool. This reactivity is thought to depend on the type of emission source, on aging mechanisms that are active in the soil, and on ambient conditions. Our work shows, that when controlling for soil p...

  8. On the Evolution of Quasicrystalline and Crystalline Phases in Rapidly Quenched Al-Co-Cu-Ni Alloy

    OpenAIRE

    Yadav, T. P.; Mukhopadhyay, N. K.; Tiwari, R. S.; O. N. Srivastava

    2006-01-01

    The occurrence of stable decagonal quasicrystalline phase in Al-Co-Ni and Al-Cu-Co alloys through conventional solidification is well established. Earlier, we have studied the effect of Cu substitution in place of Co in the Al70 Co15Ni15 alloy. Here we report the structural/micro-structural changes with substitution of Cu for Ni in rapidly solidified Al-Co-Ni alloys. The melt-spun ribbons have been characterized using X-ray diffractometry (XRD), Scanning and transmission electron microscopy (...

  9. Room temperature ferromagnetism and gas sensing in ZnO nanostructures: Influence of intrinsic defects and Mn, Co, Cu doping

    Science.gov (United States)

    Mhlongo, Gugu H.; Shingange, Katekani; Tshabalala, Zamaswazi P.; Dhonge, Baban P.; Mahmoud, Fawzy A.; Mwakikunga, Bonex W.; Motaung, David E.

    2016-12-01

    Undoped and transition metal (Cu, Co and Mn) doped ZnO nanostructures were successfully prepared via a microwave-assisted hydrothermal method followed by annealing at 500 °C. Numerous characterization facilities such as X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM) were employed to acquire the structural and morphological information of the prepared ZnO based products. Combination of defect structure analysis based on photoluminescence (PL) and electron paramagnetic resonance (EPR) indicated that co-existing oxygen vacancies (VO) and zinc interstitials (Zni) defects are responsible for the observed ferromagnetism in undoped and transition metal (TM) doped ZnO systems. PL analysis demonstrated that undoped ZnO has more donor defects (VO and Zni) which are beneficial for gas response enhancement. Undoped ZnO based sensor exhibited a higher sensor response to NH3 gas compared to its counterparts owing to high content of donor defects while transition metal doped sensors showed short response and recovery times compared to undoped ZnO.

  10. Effects of electronic relaxation processes on vibrational linewidths of adsorbates on surfaces: The case of CO/Cu(100)

    Science.gov (United States)

    Novko, D.; Alducin, M.; Blanco-Rey, M.; Juaristi, J. I.

    2016-12-01

    We investigate nonadiabatic effects for the vibrational stretch mode of the CO molecule adsorbed on the top site of the Cu(100) surface. By studying the long-wavelength (q ≈0 ) imaginary and real parts of the density functional theory based phonon self-energy due to the electron-phonon coupling Πλ we obtain the phonon linewidth and the frequency renormalization of the CO stretch mode, respectively. To simulate electronic scattering processes that lead to further damping of the phonon modes we include a phenomenological damping in the phonon self-energy, as well as in the single-electron spectral function that enters Πλ, through the momentum distribution function. For the specific case of electron-impurity scattering we explicitly show how this process opens the indirect intraband channel and broadens the linewidth of the CO stretch mode. To emphasize the importance of accounting for electronic scattering processes we compare the phonon linewidths in the clean noninteracting limit (infinite electron lifetime) and when electronic scattering processes are phenomenologically included (finite electron lifetime) with available experimental data. We find that the agreement with experiments is improved in the latter case.

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

    DEFF Research Database (Denmark)

    Owsianiak, Mikolaj; Holm, Peter E.; Fantke, Peter;

    2015-01-01

    Metal exposure to terrestrial organisms is influenced by the reactivity of the solid-phase metal pool. This reactivity is thought to depend on the type of emission source, on aging mechanisms that are active in the soil, and on ambient conditions. Our work shows, that when controlling for soil p...

  12. Distribution of Fe, Mn, Ni, Co, Cu and Zn in non-lithogenous fractions of sediments of Gulf of Kutch

    Digital Repository Service at National Institute of Oceanography (India)

    Paropkari, A.L.; Topgi, R.S.; Rao, Ch.M.; Murty, P.S.N.

    be attributed to compositional differences in the individual samples. From an evaluation of the processes of incorporation of elements into sediments in association with non-lithogenous fractions, it is tentatively concluded that the elements particularly trace...

  13. Hydrogen production by low-temperature reforming of bioethanol over ZnO-supported Co-Ni and Co-Cu catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Llorca, J.; Homs, N.; Ramirez de la Piscina, P.

    2005-07-01

    The use of a renewable, non-toxic biomass-derived source, like bioethanol, to produce hydrogen is actually very attractive. In such domain, the search of a catalytic system highly effective for the selective steam-reforming process is of current research interest, CH3CH2OH+3H2O.6H2+2CO2. The steam-reforming of ethanol involves numerous steps and usually competes with several parallel reactions that originate undesired products like CO and CH4, resulting in lower hydrogen yields and difficult practical application. Copper- and nickel-based catalysts, including catalysts containing both metals, have been extensively studied in the steam-reforming of ethanol [1-3]. It has been well established that copper favours the dehydrogenation reaction and nickel the breaking of C-C bonds. Moreover, the presence of basic supports and Cu-Ni alloys prevent the formation of carbon deposits [1-3]. On the other hand, we have shown that ZnO-supported cobalt catalysts are very selective to hydrogen and CO2 from the steam reforming of bioethanol mixtures below 673 K [4]. In addition, sodium addition to ZnO-supported cobalt catalysts results in a major stability by suppressing the deposition of carbon [5]. Here we present the catalytic behaviour at low temperature of sodium-promoted, bimetallic cobalt-nickel and cobalt copper catalysts supported on ZnO and compare their performance with mono metallic ZnO-supported Ni and Cu samples. Catalysts have been tested in the steam-reforming reaction of bioethanol at atmospheric pressure (C2H5OH:H2O1:4 v/v) and characterised by means of X-ray diffraction (XRD), transmission electron microscopy techniques (TEM) and X-ray photoelectron spectroscopy (XPS) before and after reaction. The effect of introduction of copper or nickel on cobalt-based catalysts is discussed in relation to their catalytic performances. (Author)

  14. The magnetic properties and magnetocaloric effects in binary R–T (R = Pr, Gd, Tb, Dy, Ho, Er, Tm; T = Ga, Ni, Co, Cu) intermetallic compounds

    Science.gov (United States)

    Zheng, Xin-Qi; Shen, Bao-Gen

    2017-02-01

    Not Available Project supported by the National Natural Science Foundation of China (Grant Nos. 11274357, 51501005, 51590880, and 11674008), the Fundamental Research Funds for the Central Universities, China (Grant No. FRF-TP-15-010A1), the China Postdoctoral Science Foundation (Grant No. 2016M591071), and the Key Research Program of the Chinese Academy of Sciences (Grant No. KJZD-EW-M05).

  15. Biotransfer, bioaccumulation and effects of herbivore dietary Co, Cu, Ni, and Zn on growth and development of the insect predator Podisus maculiventris (Say)

    Science.gov (United States)

    Increased metal availability in the environment can detrimentally impact the growth and development of organisms at all trophic levels of a food web, in part because metals can be biotransferred or bioaccumulated between trophic levels. We evaluated the survival, growth, and development of a general...

  16. Physico-chemical properties studies of Co-Cu oxide ores and their impacts on the dissolution of cobalt and copper bearing minerals

    OpenAIRE

    2013-01-01

    M.Sc. (Chemistry) Cobalt is mainly associated with copper, both in the primary ores and in the oxidation zone. In Southern Africa cobalt metal is produced as a by-product of the extraction of copper, nickel and platinum group metals. The hydrometallurgical route is commonly used, since cobalt bearing materials are acid leached prior to the clarification and impurity removal process preceding the electrowinning of the value. In order to understand the dissolution behaviour of cobalt and cop...

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

    CERN Document Server

    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. Distribution of Al, Mn, Ni, Co & Cu in the non-lithogenous fractions of sediments of the northern half of the western continental shelf of India

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, P.S.N.; Rao, Ch.M.; Paropkari, A.L.; Topgi, R.S.

    of the outer shelf region with high calcium carbonate content and all the elements covary with each other in the environment. From an evaluation of the role of different processes with the incorporation of elements, particularly trace elements...

  19. Effects of Cd, Co, Cu, Ni and Zn on asexual reproduction and early development of the tropical sea anemone Aiptasia pulchella.

    Science.gov (United States)

    Howe, Pelli L; Reichelt-Brushett, Amanda J; Clark, Malcolm W

    2014-11-01

    Currently few studies present sub-lethal toxicity data for tropical marine species, and there are no routine toxicity tests using marine cnidarians. The symbiotic sea anemone Aiptasia pulchella has been identified as a useful species for ecotoxicological risk assessment, and would provide a tropical marine cnidarian representative. Chronic sub-lethal toxicity tests assessing the effects of 28-day trace metal exposure on asexual reproduction in A. pulchella were investigated, and concentration-dependant reductions in the number of offspring that were produced were evident for all metal exposures. Metal concentration estimates causing 50% reductions in the numbers of asexually-reproduced juveniles after 28-day exposures (28-day effect concentrations 50%: EC50s) were 14 µg/L for copper, 63 µg/L for zinc, 107 µg/L for cobalt, 145 µg/L for cadmium, and 369 µg/L for nickel. Slightly higher 28-day EC50s of 16 µg/L for copper, 192 µg/L for zinc, 172 µg/L for cobalt, 185 µg/L for cadmium, and 404 µg/L for nickel exposures and were estimated based on reductions in the total number of live developed and undeveloped offspring. These sensitive and chronic sub-lethal toxicity estimates help fill the knowledge gap related to metal effects on cnidarians over longer exposure periods, and this newly-developed bioassay may provide a much needed tool for ecotoxicological risk assessment relevant to tropical marine environments.

  20. Cr-free Co-Cu/SBA-15 catalysts for hydrogenation of biomass-derivedα-,β-unsaturated aldehyde to alcohol

    Institute of Scientific and Technical Information of China (English)

    Sanjay Srivastava; Pravakar Mohanty; Jigisha K. Parikh; Ajay K. Dalai; S. S. Amritphale; Anup K. Khare

    2015-01-01

    Cr-free bi-metallic SBA-15-supported Co–Cu catalysts were examined in the conversion of bio-mass-derived α-, β-unsaturated aldehyde (furfural) to value-added chemical furfuryl alcohol (FOL). Co–Cu/SBA-15 catalysts with a fixed Cu loading of 10 wt% and varying Co loadings (2.5, 5, and 10 wt%) were prepared by the impregnation method. The catalysts were characterized by X-ray dif-fraction, N2 sorption, H2 temperature-programmed reduction, scanning electron microscopy, ener-gy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, CO chemi-sorption, and inductively coupled plasma mass spectrometry. The influence of different reaction parameters such as temperature, pressure, catalyst dosage, and furfural concentration on the cata-lyst performance was evaluated. Relative to catalysts supported on amorphous silica, the current SBA-15-supported Co–Cu catalysts displayed higher performance, attaining a furfural conversion of 99% and furfuryl alcohol selectivity of 80%. The catalytic reactions were conducted in a 100-mL autoclave at 170 °C and 2 MPa H2 pressure for 4 h.

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

    Directory of Open Access Journals (Sweden)

    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.

  2. Ordered mesoporous MFe(2)O(4) (M = Co, Cu, Mg, Ni, Zn) thin films with nanocrystalline walls, uniform 16 nm diameter pores and high thermal stability: template-directed synthesis and characterization of redox active trevorite.

    Science.gov (United States)

    Haetge, Jan; Suchomski, Christian; Brezesinski, Torsten

    2010-12-20

    In this paper, we report on ordered mesoporous NiFe(2)O(4) thin films synthesized via co-assembly of hydrated ferric nitrate and nickel chloride with an amphiphilic diblock copolymer, referred to as KLE. We establish that the NiFe(2)O(4) samples are highly crystalline after calcination at 600 °C, and that the conversion of the amorphous inorganic framework comes at little cost to the ordering of the high quality cubic network of pores averaging 16 nm in diameter. We further show that the synthesis method employed in this work can be readily extended to other ferrites, such as CoFe(2)O(4), CuFe(2)O(4), MgFe(2)O(4), and ZnFe(2)O(4), which could pave the way for innovative device design. While this article focuses on the self-assembly and characterization of these materials using various state-of-the-art techniques, including electron microscopy, grazing incidence small-angle X-ray scattering (GISAXS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), X-ray photoelectron spectroscopy (XPS), as well as UV-vis and Raman spectroscopy, we also examine the electrochemical properties and show the benefits of combining a continuous mesoporosity with nanocrystalline films. KLE-templated NiFe(2)O(4) electrodes exhibit reasonable levels of lithium ion storage at short charging times which stem from facile pseudocapacitance.

  3. Carboxymethyl cellulose (CMC)-loaded Co-Cu doped manganese ferrite nanorods as a new dual-modal simultaneous contrast agent for magnetic resonance imaging and nanocarrier for drug delivery system

    Science.gov (United States)

    Abbasi Pour, Sajjad; Shaterian, Hamid Reza; Afradi, Mojgan; Yazdani-Elah-Abadi, Afshin

    2017-09-01

    We synthesized Co0.25Cu0.25Mn0.5Fe2O4@CMC (CCMFe2O4@CMC) nanorods as a new dual-modal simultaneous for magnetic resonance imaging contrast agent and nanocarrier for drug delivery system. Impact of CCMFe2O4@CMC nanorods were investigated on the longitudinal (T1), transverse (T2) and transverse (T2∗) relaxation times for in vitro MRI contrast agent in water and also for drug delivery system, L-dopa was coated on CCMFe2O4@CMC nanorods and then in vitro drug release test was carried out at three PHs values and different temperatures. In vitro MR imaging demonstrated that r2 value of CCMFe2O4@CMC nanorods is 138.33 mM-1 s-1, CCMFe2O4@CMC is useful as T2 contrast agent relative to other T2 contrast agants. In vitro drug release test shows the amount of released L-dopa from CCMFe2O4@CMC nanorods at medium with pH = 1.2 is more than pH = 5.3 and 7.4.

  4. 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

    Science.gov (United States)

    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.

  5. 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

    Energy Technology Data Exchange (ETDEWEB)

    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.)

  6. Possible use of wild-living rats (Rattus norvegicus) as bioindicators for heavy metal pollution. Part I. Sex and age-related quantification of Al, As, Cd, Co, Cu, Mn, Ni, Pb, Sr, Ti, Tl and Zn in liver, heart, lung, kidney, muscle, brain and bones, and the establishment of distribution patterns; Untersuchungen zur Eignung wildlebender Wanderratten (Rattus norvegicus) als Indikatoren der Schwermetallbelastung. T. I. Alters- und geschlechtsspezifische Quantifizierung der Verteilung von Al, As, Cd, Co, Cu, Mn, Ni, Pb, Sr, Ti, Tl und Zn in den Organen Herz, Leber, Lunge, Niere, Muskulatur, Gehirn und Knochen

    Energy Technology Data Exchange (ETDEWEB)

    Wuenschmann, S. [Internationales Hochschulinstitut Zittau (Germany). Lehrstuhl fuer Umweltverfahrenstechnik; Hochschule fuer Technik, Wirtschaft und Sozialwesen Zittau/Goerlitz (FH), Zittau (Germany). Fachbereich Mathematik/Naturwissenschaften; Oehlmann, J. [J. W. Goethe-Univ. Frankfurt, Zoologisches Inst., Frankfurt/M. (Germany); Delakowitz, B. [Hochschule fuer Technik, Wirtschaft und Sozialwesen Zittau/Goerlitz (FH), Zittau (Germany). Fachbereich Mathematik/Naturwissenschaften; Markert, B. [Internationales Hochschulinstitut Zittau (Germany). Lehrstuhl fuer Umweltverfahrenstechnik

    2001-07-01

    The objective of the current attempt was to investigate the suitability of wild-living rats (Rattus norvegicus) as a passive bioindicator using quantitative determinations of 12 chemical elements in different organs taken from rats which were caught in the Zoological Garden of Zittau. Aside from the determinations of so-called background levels, the focus of interest was with accumulations of certain elements within the organs depending on either sex or age of the rats. There were different affinities of the elements towards certain organs. Because of apparent sex and age-related differences in element concentrations and accumulation features, a well-planned sampling strategy for the use of rats as possible passive bioindicators is indeed required. The consideration of element distribution patterns within the organ system of Rattus norvegicus (based on body burden calculations (in part 2 of this work)) allows an effective use of the rat for purposes of integrative monitoring. (orig.) [German] Durch die Quantifizierung von 12 chemischen Elementen im Organsystem von wildlebenden Ratten (Rattus norvegicus) aus dem Tierpark Zittau (Sachsen) sollte die Eignung dieser Spezies als passiver Bioindikator untersucht werden. Neben der Ermittlung von sogenannten Hintergrundkonzentrationen standen insbesondere Fragen zur geschlechts- und altersspezifischen Akkumulation einzelner Elemente im Organsystem von Rattus norvegicus im Vordergrund. Spezifisch zeigten dabei einzelne Elemente unterschiedliche Affinitaeten zu den entsprechenden Geweben und Organen. Insbesondere die hierbei ermittelten geschlechts- und altersspezifischen Charakteristika einzelner Elemente macht eine detaillierte Ausarbeitung einer Beprobungsstrategie fuer den spaeteren Einsatz als passiver Bioindikator zwingend. Unter Beruecksichtigung des durch die Berechnung des Body Burden (Koerperlast) im 2. Teil der Arbeit ermittelten typischen Verteilungsmusters einzelner Elemente ist Rattus norvegicus zum integrativen Monitoringeinsatz praedestiniert. (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  8. Piezoelectric, dielectric and magnetic properties of (1-x)Pb[Zr, Ti, (Mg{sub 1/2}W{sub 1/2}), (Ni{sub 1/3}Nb{sub 2/3})]O{sub 3}+x(Ni, Co, Cu)FeO{sub 4} composites

    Energy Technology Data Exchange (ETDEWEB)

    Chao Xiaolian [Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an, 710062 Shaanxi (China); Yang Zupei, E-mail: yangzp@snnu.edu.c [Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an, 710062 Shaanxi (China); Dong Mingyuan; Zhang Yi [Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an, 710062 Shaanxi (China)

    2011-08-15

    The phase structure, microstructure, piezoelectric properties, dielectric characteristic and the ME effect of magnetoelectric Pb[Zr{sub 0.23}Ti{sub 0.36}+0.02(Mg{sub 1/2}W{sub 1/2})+0.39(Ni{sub 1/3}Nb{sub 2/3})]O{sub 3} (PZT)+xNi{sub 0.8}Co{sub 0.1}Cu{sub 0.1}Fe{sub 2}O{sub 4} (NCCF) composite ceramics were prepared by the conventional solid state reaction method. The structural analysis of both the constituent phases and their composites was carried out by X-ray diffraction, energy dispersive spectrometry and scanning electron microscopy. The results showed cubic spinel structure for ferrite phase and tetragonal perovskite structure for ferroelectric phase. The piezoelectric constant, dielectric constant, Curie temperature, remanent polarization and coercive electric field decreased with increase of ferrite content. The coercive field strength, saturation magnetization and remanent magnetization increased with increasing ferrite content. - Highlights: (1-x)Pb[Zr{sub 0.23}Ti{sub 0.36}+0.02(Mg{sub 1/2}W{sub 1/2})+0.39(Ni{sub 1/3}Nb{sub 2/3})] O{sub 3}+xNi{sub 0.8}Co{sub 0.1}Cu{sub 0.1}Fe{sub 2}O{sub 4} composites have been prepared by the conventional ceramics technique. However, there is little work that can give piezoelectric characteristics of ME. In this work, the magnetoelectric and piezoelectric properties of magnetoelectric composites are investigated.

  9. MgO负载金属双功能催化剂用于生物基山梨醇氢解制丙二醇、乙二醇和甘油%Sorbitol hydrogenolysis to glycerol and glycols over M-MgO (M=Ni, Co, Cu) nanocomposite:A comparative study of active metals

    Institute of Scientific and Technical Information of China (English)

    王喜成; 刘晓然; 徐悦; 彭功名; 曹泉; 牟新东

    2015-01-01

    The activities and selectivities of MgO-supported Ni, Cu, and Co catalysts have been compared in aqueous-phase hydrogenolysis of sorbitol to glycerol and glycols. All catalysts effectively catalyzed the sorbitol conversion into C2 and C3 polyols like glycerol, 1,2-propylene glycol, and ethylene gly-col, but with different product distributions. The differences in activities and selectivities are as-cribed to their different dehydrogenation/hydrogenation activities. The influences of base promot-er, temperature, H2 pressure, and reaction time were also studied. Added base promoter and pro-longed reaction time enhanced sorbitol conversion for the three catalysts, but led to product degra-dation and decreased selectivity over Ni-MgO and Co-MgO, whereas selectivity maintained almost unchanged over Cu-MgO.%甘油、丙二醇和乙二醇是非常重要的化工原料和合成聚酯类、聚醚类树脂的单体,也可作为功能化合物直接应用于化妆品、食品及制冷等领域.随着生物炼制行业的发展,其作为生物基平台化合物在未来可以获得更为广泛的应用.从富含氧原子的纤维素出发制备甘油和二元醇,符合绿色化学化工的原子经济性、工艺经济性和生产过程清洁等原则,也是生物质资源化利用的重要途径.因此,近年来以纤维素及其衍生物糖和糖醇为原料,通过氢解反应制备甘油和二元醇的研究在国外已广泛开展.在目前已报道的氢解糖和糖醇研究中,几乎均采用包含金属催化剂和液体碱助剂的耦合催化体系,所用液体碱为NaOH, KOH和Ca(OH)2等,使用量很大.这些碱性助剂可以提高金属催化剂对糖醇加氢和氢解反应的催化活性,促进底物转化,但同时也不可避免地加剧了二醇产物进一步氢解和自身缩合反应,使产物选择性降低.在产物分离和提纯过程中,过高的碱浓度也会诱导甘油和二醇产品自身缩合,使分离困难,提高了分离成本.反应液的强碱性还增加了生产过程的设备成本.本文以固体碱MgO为载体,分别负载Ni, Co和Cu等金属制备出Ni-MgO, Co-MgO和Cu-MgO等双功能催化剂,应用于糖醇氢解反应,从而减少或避免使用液体碱添加剂.木质纤维素降解得到的单糖中含量最大的是六碳糖,本文以六碳糖加氢衍生物山梨醇为模型底物,考察了所制MgO负载金属双功能催化剂催化糖醇氢解制甘油和二元醇的活性和选择性,研究了反应条件对山梨醇氢解生成二醇和甘油的影响. ;山梨醇氢解反应在不锈钢反应釜中进行.采用气相色谱-质谱联用对氢解产物进行定性分析,采用气相色谱和离子色谱分别对反应中低沸点和高沸点产物进行定量分析.结果表明,在Ni-MgO, Co-MgO和Cu-MgO (其中活性金属和载体MgO的比例为1:3)三种催化剂上山梨醇均能高效转化为乙二醇、1,2-丙二醇和甘油;无论是否添加Ca(OH)2,山梨醇氢解活性顺序均为Ni-MgO>Co-MgO>Cu-MgO.三种催化剂上产物选择性有较大差异, Ni-MgO和Co-MgO对乙二醇和1,2-丙二醇具有较好的选择性,其中1,2-丙二醇与乙二醇比例约为2,而Cu-MgO催化剂对1,2-丙二醇选择性较高,1,2-丙二醇与乙二醇比例约为7.同时,考察了反应温度、压力和反应时间对三种催化剂上山梨醇转化活性和产物选择性的影响.随着温度升高,所有催化剂活性均显著增加,其中Ni-MgO和Cu-MgO催化山梨醇氢解对反应条件较为敏感,而Cu-MgO催化剂对反应条件不敏感.在Ni-MgO催化剂上,可以在较低的反应温度下获得较高的产物选择性.

  10. Simultaneous Determination of Cd, Co, Cu, Mg,Mn, Ni, Pb, Zn and Ca in Laterite Nickel Ore by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES)%电感耦合等离子体原子发射光谱法(ICP-AES)测定红土镍矿中的Cd、Co、Cu、Mg、Mn、Ni、Pb、Zn、Ca9种元素

    Institute of Scientific and Technical Information of China (English)

    何飞顶; 李华昌; 冯先进

    2011-01-01

    提出了使用电感耦合等离子体-原子发射光谱法同时测定红土镍矿中Cd、Co、Cu、Mg、Mn、Ni、Pb、Zn、Ca的分析方法.采用盐酸、硝酸和氢氟酸处理样品,以盐酸作为测定介质,在选定的仪器工作条件下直接测定.各元素的测定检出限为0.0001~0.0033μg/mL,相对标准偏差(RSD,n=6)为0.15%~1.89%.对样品进行加标回收试验,回收率在91.4%~107.2%之间.经比对试验证明,本法测定值与火焰原子吸收光谱法测定值一致.

  11. Metal concentration in some seaweeds of Goa (India)

    Digital Repository Service at National Institute of Oceanography (India)

    Agadi, V.V.; Bhosle, N.B.; Untawale, A.G.

    Seventeen species of marine algae collected from five localities of Goa, were analysed for Co, Cu, Fe, Mn, Ni, Pb and Zn, using atomic absorption spectrophotometer. All the seven metals showed considerable variations in their concentration. The role...

  12. Possible Impactor Remnants on Shatter Cone Surfaces from the Steinheim Basin, SW Germany

    Science.gov (United States)

    Buchner, E.; Schmieder, M.

    2015-07-01

    Surfaces of Steinheim shatter cones are covered by mineral coatings that consist of Fe, Ni, Co, Cu, Pt, and Au mineral assemblages. A plausible explanation is that they represent impactor matter remobilized in an impact-induced hydrothermal system.

  13. Comparison between Top and Bottom NiO-pinning Spin Valves: Effect of Interfacial Roughness on Specular Reflection

    Institute of Scientific and Technical Information of China (English)

    Liang SUN; Jun DU; Xiaoshan WU; Shiming ZHOU; Xixiang ZHANG; An HU

    2006-01-01

    Top and bottom NiO-pinning spin valves of Si/Ta/NiO/Co/Cu/Co/Ta and Si/Ta/Co/Cu/Co/NiO/Ta wereprepared by magnetron sputtering, and X-ray diffraction and giant magnetoresistance (GMR) ratio were measured in the temperature range from 5 to 300 K. For the bottom spin valve, the interfacial roughness at NiO/Co is much smaller than that of Co/NiO in the top one. The Co/Cu and Cu/Co interfaces have the same roughness in the bottom and the top spin valves. NiO, Co, and Cu layers have (111) preferred orientations in the top one and random orientations in the bottom one. The GMR ratio of the bottom spin valve is larger than that of the top one at all temperatures and their difference increases with decreasing temperature.

  14. Calculating formation range of binary amorphous alloys fabricated by electroless plating

    Science.gov (United States)

    Zhang, Bangwei; Liao, Shuzhi; Shu, Xiaolin; Xie, Haowen

    2016-06-01

    A lot of amorphous alloy deposits in the binary (Ni, Co, Cu)-(P, B) alloy systems fabricated by electroless plating (EP) have been reported up to date. But no one reported their theoretical modeling of the amorphous formation and calculated their concentration range of amorphous formation (RAF). Using Miedema model and subregular model scheme, the RAFs for the six EP (Ni, Co, Cu)-(P, B) alloys and three Ni-Cu, Ni-Co and Co-Cu alloys have been calculated systematically for the first time. The calculated results are in agreement with experimental observations. Experiments and calculations for the RAFs in the latter three alloy systems reveal that not any RAF formed except crystalline states. The huge difference between the six metal-metalloid alloys and three metal-metal alloys in RAF has been discussed in detail in the paper.

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

    Directory of Open Access Journals (Sweden)

    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.

  16. Thermodynamic investigations on the component dependences of high-entropy alloys

    Science.gov (United States)

    Arslan, Huseyin; Dogan, Ali

    2016-12-01

    In the present research, a study on the thermodynamical properties of the quinary Co-Cu-Cr-Fe-Ni high-entropy alloys and ternary Ca-Sb-Yb is carried out by the models Kohler, Chou's general solution method (GSM) and Muggianu. The dependences of composition variation on thermodynamic properties, such as enthalpy of mixing of Co-Cu-Cr-Fe-Ni alloys in simple FCC phase are investigated at the temperatures 1273, 1373, and 1473 K. Moreover, a comparison between the results of the three models and those of other theoretical models shows good mutual agreement.

  17. Probe molecule studies: Active species in alcohol synthesis. Final report, July 1993--July 1994

    Energy Technology Data Exchange (ETDEWEB)

    Blackmond, D.G.; Wender, I.; Oukaci, R.; Wang, Jian

    1994-07-01

    The objectives of this project are to investigate the role(s) of cobalt and copper in constructing the active sites for the formation of higher alcohols from CO/H{sub 2} over the Co-Cu based catalysts by using different reduction treatments and applying selected characterization tools such as TPR, TPD, XRD and XPS as well as to generate mechanistic information on the reaction pathway(s) and key intermediate(s) of higher alcohol synthesis from CO/H{sub 2} over Co-Cu/ZnO catalysts by the approach of in-situ addition of a probe molecule (nitromethane).

  18. Perpendicular hot electron spin-valve effect in a new magnetic field sensor: The spin-valve transistor

    NARCIS (Netherlands)

    Monsma, D.J.; Lodder, J.C.; Popma, T.J.A.; Dieny, B.

    1995-01-01

    A new magnetic field sensor is presented, based on perpendicular hot electron transport in a giant magnetoresistance (Co/Cu)4 multilayer, which serves as a base region of an n-silicon metal-base transistor structure. A 215% change in collector current is found in 500 Oe (77 K), with typical

  19. Concentration and Health Implication of Heavy Metals in Drinking ...

    African Journals Online (AJOL)

    The study was undertaken to assess the status of drinking water quality in the ... pH, and turbidity and ten heavy metals,viz., As, Cd, Co, Cu, Cr, Fe, Mn, Ni, Pb, and ... treatment practices in the areas, which in turn have important human health ...

  20. Kinetic, equilibrium and thermodynamic modelling of the sorption of ...

    African Journals Online (AJOL)

    2013-07-04

    Jul 4, 2013 ... remove metals (Co, Cu, Fe, Mg, Mn, Ni, U and Zn) from mine waters. The metal ..... The effect of pH on adsorption was assessed over the pH range 2–10 and ..... ization of surface-bound Zr(IV) and its application to removal of.

  1. Heavy metals in bottom sediments of Lake Umbozero in Murmansk Region, Russia

    DEFF Research Database (Denmark)

    Jernström, Jussi; Lehto, J.; Dauvalter, A.;

    2010-01-01

    Sediment cores collected from different locations of Lake Umbozero were studied with respect to concentration and mobility of trace and heavy metals Co, Cu, Fe, Mn, Ni, Pb, U, and Zn. Lake Umbozero is the second largest lake in the Murmansk Region and subjected to contamination by air-borne emiss...

  2. Trace metals in suspended particulate matter and sediments from the Severnaya Dvina estuary, Russian Arctic

    NARCIS (Netherlands)

    Koukina, S.E.; Calafat-Frau, A.; Hummel, H.; Palerud, R.

    2001-01-01

    A geochemical study of the Severnaya Dvina estuary was carried out during two oceanographic cruises to the White Sea. The amount and distribution of trace (Mn, Co, Cu, Ni, Pb, and Zn) and major (Al and Fe) elements in suspended particulate matter and sediments were determined. The main source of

  3. Bias-dependent contact resistance in rubrene single-crystal field-effect transistors

    NARCIS (Netherlands)

    Molinari, A.; Gutiérrez, I.; Hulea, I.N.; Russo, S.; Morpurgo, A.F.

    2007-01-01

    The authors report a systematic study of the bias-dependent contact resistance in rubrene single-crystal field-effect transistors with Ni, Co, Cu, Au, and Pt electrodes. They show that the reproducibility in the values of contact resistance strongly depends on the metal, ranging from a factor of 2 f

  4. Resources of Selected Metals in Parent Bodies of Ordinary Chondrites

    Science.gov (United States)

    Łuszczek, K.; Przylibski, T. A.

    2013-09-01

    Certain metals in OC exceed mean content of these metals in the Earth’s crust. Content of Fe and Ni in OC is even higher than in Earth's deposits. Parent bodies of OC, can be regarded as Fe-Ni deposits, while accompanying ores are Mn,Cr,Co,Cu,Ag,Au.

  5. On the stability of the CO adsorption-induced and self-organized CuPt surface alloy

    DEFF Research Database (Denmark)

    Andersson, Klas Jerker; Chorkendorff, Ib

    2010-01-01

    ) from room temperature to 673 K. No indications of substantial changes in surface structure were observed under the latter conditions compared to CO alone whereas the O-2 oxidation resulted in CO removal and the build-up of an ultrathin CuOx-film. However, the oxidized CO/CuPt surface alloy could...

  6. The absorption of carbon monoxide in COSORB solutions : absorption rate and capacity

    NARCIS (Netherlands)

    Hogendoorn, J.A.; Swaaij, W.P.M. van; Versteeg, G.F.

    1995-01-01

    Absorption rate experiments and equilibrium experiments were carried out for the COSORB reaction at 300 K. The equilibrium data at 300 K could reasonably well be described with the following relation: Keq=3.4×10^3=([CuAlCl4.tol.CO][tol])/([CO][CuAlCl4.tol2]) Determination of the kinetics and mechani

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

    DEFF Research Database (Denmark)

    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...

  8. Thermodynamic assessment of the Sn-Co lead-free solder system

    Science.gov (United States)

    Liu, Libin; Andersson, Cristina; Liu, Johan

    2004-09-01

    The Sn-Co-Cu eutectic alloy can be a less expensive alternative for the Sn-Ag-Cu alloy. In order to find the eutectic solder composition of the Sn-Co-Cu system, the Sn-Co binary system has been thoroughly assessed with the calculation of phase diagram (CALPHAD) method. The liquid phase, the FCC and HCP Co-rich solid solution, and the BCT Sn-rich solid solution have been described by the Redlich-Kister model. The Hillert-Jarl-Inden model has been used to describe the magnetic contributions to Gibbs energy in FCC and HCP. The CoSn2, CoSn, Co3Sn2_β, and Co3Sn2_α phases have been treated as stoichiometric phases. A series of thermodynamic parameters have been obtained. The calculated phase diagram and thermodynamic properties are in good agreement with the experimental data. The obtained thermodynamic data was used to extrapolate the ternary Sn-Co-Cu phase diagram. The composition of the Sn-rich eutectic point of the Sn-Co-Cu system was found to be 224°C, 0.4% Co, and 0.7% Cu.

  9. Formation and emission of fine particles from two coal-fired power plants

    DEFF Research Database (Denmark)

    Nielsen, M.T.; Livbjerg, H.; Fogh, C.L.

    2002-01-01

    , and Fe under reducing conditions. Several other ash-contained elements, e.g., P, Ba, Co, Cu, Mn, Ni, Ph, V, and Zn, are partly vaporized in the boiler and enrich the small particles when they condense during cooling of the flue gas. Due to the higher penetration of the small particles through the filter...

  10. Spin-dependent Peltier effect of perpendicular currents in multilayered nanowires

    Science.gov (United States)

    Gravier, Laurent; Serrano-Guisan, Santiago; Reuse, François; Ansermet, J.-Ph.

    2006-02-01

    Heat and charge transport perpendicular to Co/Cu multilayers are characterized by magnetoresistance and magnetothermoelectrical power. Furthermore, a very large voltage response to temperature oscillations under a dc current is observed, which depends strongly on the applied magnetic field. This effect is ascribed to a Peltier effect and its field dependence to a spin dependence of the Peltier coefficient.

  11. Soil-plant-animal transfer models to improve soil protection guidelines: A case study from Portugal

    NARCIS (Netherlands)

    Rodrigues, S.M.; Pereira, M.E.; Duarte, A.C.; Römkens, P.F.A.M.

    2012-01-01

    Food chain models are essential tools to assess risks of soil contamination in view of product quality including fodder crops and animal products. Here we link soil to plant transfer (SPT) models for potentially toxic elements (PTEs) including As, Ba, Cd, Co, Cu, Hg, Ni, Pb, Sb, U and Zn with models

  12. Synthesis, structural and magnetic properties of spin ladder compound Ca{sub 1-x}Co{sub x}Cu{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Sekar, C., E-mail: Sekar2025@gmail.com [Department of Bioelectronics and Biosensors, Alagappa University, Karaikudi 630003 (India); Department of Physics, Periyar University, Salem 636011 (India); Paulraj, S. [Department of Physics, Periyar University, Salem 636011 (India); Krabbes, G. [Leibniz-Institute for Solid State and Materials Research, IFW-Dresden, 01171 Dresden (Germany); Kanagaraj, M.; Arumugam, S. [Centre for High Pressure Research, Bharathidasan University, Trichy 620024 (India); Kumar, Ravhi S. [High Pressure Science and Engineering Centre and Department of Physics, University of Nevada Las Vegas, Las Vegas, NV 89154 (United States)

    2011-12-15

    MCu{sub 2}O{sub 3} (M=Ca and Co) system has two-leg spin ladder structure similar to that of the prototype SrCu{sub 2}O{sub 3} system except that the rungs are buckled with an angle of 123{sup o} and 105{sup o} for CaCu{sub 2}O{sub 3} and CoCu{sub 2}O{sub 3} compounds, respectively. We have synthesized powder samples of (Ca{sub 1-x}Co{sub x})Cu{sub 2}O{sub 3} (x=0.00-1.00) by the solid state reaction method and their structural and magnetic properties have been investigated. All the synthesized compounds crystallize in orthorhombic structure with space group Pmmn. Lattice parameters of (Ca{sub 1-x}Co{sub x})Cu{sub 2}O{sub 3} decrease with the increase in Co content. DC magnetic susceptibility {chi}(T) results of the end products CaCu{sub 2}O{sub 3} and CoCu{sub 2}O{sub 3} show antiferromagnetic transition (T{sub N}) at 27 and 215 K, respectively. Co doping into (Ca{sub 1-x}Co{sub x})Cu{sub 2}O{sub 3} enhances its T{sub N} systematically with increasing Co concentration. The {chi}(T) of CoCu{sub 2}O{sub 3} shows a broad transition with the peak temperature around 215 K and it was found to be field independent up to 90 kOe. The ambiguity concerning the transition was ruled out by recording the temperature dependent X-ray diffraction pattern on CoCu{sub 2}O{sub 3} system, which indicated that there is no structural transition in the investigated temperature range of 115-300 K. Further, specific heat measurement on CoCu{sub 2}O{sub 3} confirms the magnetic phase transition by the appearance of a sharp peak at 215 K. - Highlights: > Powder sample of (Ca{sub 1-x}Co{sub x})Cu{sub 2}O{sub 3} (x=0.00-1.00) has been synthesized by the solid state reaction method for the first time. > DC magnetic susceptibility {chi}(T) results of CaCu{sub 2}O{sub 3} and CoCu{sub 2}O{sub 3} show antiferromagnetic shift (T{sub N}) at 27 and 215 K in that order. > {chi}(T) of CoCu{sub 2}O{sub 3} shows a broad transition with the peak temperature around 215 K.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  16. Dispersive liquid-liquid microextraction based on the solidification of floating organic drop followed by ICP-MS for the simultaneous determination of heavy metals in wastewaters

    Science.gov (United States)

    Li, Yong; Peng, Guilong; He, Qiang; Zhu, Hui; Al-Hamadani, Sulala M. Z. F.

    2015-04-01

    In the present work, a dispersive liquid-liquid microextraction based on the solidification of floating organic drop (DLLME-SFO) combined with inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of Pb, Co, Cu, Ni, Zn. The influences of analytical parameters, including pH, extraction solvent volume, disperser solvent volume, concentration of chelating agent on the quantitative recoveries of Pb, Co, Cu, Ni, Zn were investigated. The effect of the interfering ions on the analytes recovery was also investigated. Under the optimized conditions, the limits of detection were 0.97-2.18 ng L-1. The relative standard deviations (RSDs) were 2.62-4.51% (n = 7, C = 20 ng L-1). The proposed method was successfully applied for the analysis of ultra trace metals in wastewater samples.

  17. Seasonal Investigations into the Level of Toxic Elements in Marine Organisms (Fish and Mollusk along the Coast of Ghana Using Neutron Activation Analysis

    Directory of Open Access Journals (Sweden)

    L.A. Sarsah

    2011-04-01

    Full Text Available Seasonal investigation was conducted into the occurrence and extent of potentially toxic heavy metals along the coast of Ghana using marine organisms as bioindicators of pollution. The marine organisms sampled were analysed using Instrumental Neutron Activation Analysis coupled with conventional counting system. All the four samples (Dentex macrophthalmus, Sardinella maderensis, Engraulis encrasicolus and Cymbium cymbium recorded detectable levels of potentially toxic elements which fluctuates between <0.07mg/kg Cd and 699 mg/kg Al. Cymbium cymbium recorded the highest level of (As, Co, Cu, Zn whiles Engraulis encrasicolus accumulated appreciable amount of V. Al was the most abundant of all the elements. The coast of Ghana was found to be mildly polluted with respect to the elements Al, As, Cd, Co, Cu, Cr, Ni, Hg, V and Zn.

  18. Storage capacity and oxygen mobility in mixed oxides from transition metals promoted by cerium

    Science.gov (United States)

    Perdomo, Camilo; Pérez, Alejandro; Molina, Rafael; Moreno, Sonia

    2016-10-01

    The oxygen mobility and storage capacity of Ce-Co/Cu-MgAl or Ce-MgAl mixed oxides, obtained by hydrotalcite precursors, were evaluated using Toluene-temperature-programmed-reaction, 18O2 isotopic exchange and O2-H2 titration. The presence of oxygen vacancies-related species was evaluated by means of Electron Paramagnetic Resonance. A correlation was found between the studied properties and the catalytic activity of the oxides in total oxidation processes. It was evidenced that catalytic activity depends on two related processes: the facility with which the solid can be reduced and its ability to regenerate itself in the presence of molecular oxygen in the gas phase. These processes are enhanced by Cu-Co cooperative effect in the mixed oxides. Additionally, the incorporation of Ce in the Co-Cu catalysts improved their oxygen transport properties.

  19. Giant magnetoresistance An ab-initio description

    CERN Document Server

    Binder, J

    2000-01-01

    A new theoretical concept to study the microscopic origin of Giant Magnetoresistance (GMR) from first principles is presented. The method is based on ab-initio electronic structure calculations within the spin density functional theory using a Screened KORRINGA-KOHNROSTOKER method. Scattering at impurity atoms in the multilayers is described by means of a GREEN's-function method. The scattering potentials are calculated self-consistently. The transport properties are treated quasi-classically solving the BOLTZMANN equation including the electronic structure of the layered system and the anisotropic scattering. The solution of the BOLTZMANN equation is performed iteratively taking into account both scattering out and scattering in terms (vertex corrections). The method is applied to Co/Cu and Fe/Cr multilayers. Trends of scattering cross sections, residual resistivities and GMR ratios are discussed for various transition metal impurities at different positions in the Co/Cu or Fe/Cr multilayers. Furthermore the...

  20. Electronic and magnetic properties of TM atoms adsorption on 2D silicon carbide by first-principles calculations

    Science.gov (United States)

    Luo, M.; Shen, Y. H.; Yin, T. L.

    2017-02-01

    The magnetic properties of different transition-metal (TM) atoms (TM=Co, Cu, Mn, Fe, and Ni) adsorption on SiC monolayer are investigated using density functional theory (DFT). Magnetism appears in the cases of Co, Cu, Mn, and Fe. Among all the magnetic cases, the Co-adsorbed system has the most stable structure. Therefore, we further study the interaction in the two-Co-adsorbed system. Our results show that the interaction between two Co atoms is always FM and the p-d hybridization mechanism results in such ferromagnetic states. However, the FM interaction is obviously depressed by the increasing Co-Co distance, which could be well explained by the Zener-RKKY theory. Moreover, different magnetic behavior is observed in the two-Mn-adsorbed system and a long-range AFM state is showing. Such multiple magnetic properties may suggest promising applications of TM-adsorbed SiC monolayer in the future.

  1. Modification of the Cu-ZSM-5 zeloite by cobalt: Influence on activity and stability in ethane oxidation and N{sub 2}O decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Kucherov, A.V.; Kucherova, T.N.; Nissenbaum, V.D. [Zelinskii Inst. of Organic Chemistry, Moscow (Russian Federation)] [and others

    1995-09-01

    Catalytic properties of Cu-ZSM-5, Co-ZSM-5, and Co/Cu-ZSM-5 are compared in C{sub 2}H{sub 6} oxidation and N{sub 2}0 decomposition. ESR spectroscopy is used for monitoring both valence and coordination states of CU{sup 2+} in the samples. It is shown that a solid-state promotion of Cu-ZSM-5 zeolite by cobalt ions results in an over-additive increase of the catalyst activity in the C{sub 2}H{sub 6} total oxidation and in a noticeable rise in the thermostability of the catalyst. The stabilization of both ions inside zeolitic channels for the bicationic Co/Cu-ZSM-5 system is assumed.

  2. 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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  3. Phase diagrams for surface alloys

    DEFF Research Database (Denmark)

    Christensen, Asbjørn; Ruban, Andrei; Stoltze, Per

    1997-01-01

    is based on density-functional calculations using the coherent-potential approximation and on effective-medium theory. We give self-consistent density-functional results for the segregation energy and surface mixing energy for all combinations of the transition and noble metals. Finally we discuss...... in detail the cases Ag/Cu(100), Pt/Cu(111), Ag/Pt(111), Co/Cu(111), Fe/Cu(111), and Pd/Cu(110) in connection with available experimental results....

  4. Interface magnetism of 3d transition metals

    DEFF Research Database (Denmark)

    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...

  5. Production and characterization of a bovine liver candidate reference material

    Science.gov (United States)

    Bianchi, S. R.; Peixoto, A. M. J.; Souza, G. B.; Tullio, R. R.; Nogueira, A. R. A.

    2016-07-01

    The preparation of a bovine liver candidate reference material and the steps are taken to confirm its homogeneity, long and short term stabilities, and consensus values are described. Details of the sample preparation and the final collaborative exercise are presented. The material elemental composition was characterized by 17 elements (As, Ca, Cd, Co, Cu, Fe, K, Mg, Mo, Mn, Na, P, Pb, Se, Sr, V, and Zn) of nutritional and toxicological significance.

  6. Differential tolerance of Sulfolobus strains to transition metals

    Science.gov (United States)

    Miller, K.W.; Sass, Risanico S.; Risatti, J.B.

    1992-01-01

    Sulfolobus acidocaldarius strains 98-3 and B12, and S. solfataricus ATCC 35091 were evaluated for tolerance to Cd, Co, Cu, Ni, Zn and Mg. The tolerance of strains 98-3 and ATCC 35091 to these metals was Mg > Zn > Cd > Cu ??? Co > Ni. For B12, however, the order of tolerance was Mg > Cd > Zn = Co > Ni > Cu. Tolerance to these metals is also presented as a potentially useful taxonomic indicator.

  7. ONR Far East Scientific Information Bulletin

    Science.gov (United States)

    1990-09-01

    thicker. Next, the mag- perpendicular magnetic anisotropy constants. netostriction was measured. In Co/Cu, Co/ The magneto-optical Kerr effect increases Ag...Multilayers: Magneto- is induced on the Pr. Sign and behavior of optical properties are studied at wavelengths perpendicular magnetic anisotropy depend...of Ag, Cu, and La in the perpendicular magnetic anisotropy several transition metals, combinations that energyofthelaminatedDy/Fefilmsfallsoff show up

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  9. Investigation into the effect on structure of oxoanion doping in Na2M(SO4)2·2H2O

    Science.gov (United States)

    Driscoll, L. L.; Kendrick, E.; Wright, A. J.; Slater, P. R.

    2016-10-01

    In this paper an investigation into the effect of transition metal ion and selenate/fluorophosphate doping on the structures of Na2M(SO4)2·2H2O (M=transition metal) materials is reported. In agreement with previous reports, the monoclinic (Kröhnkite) structure is adopted for M=Mn, Fe, Co, Cu, while for the smallest first row divalent transition metal ion, M=Ni, the triclinic (Fairfieldite structure) is adopted. On selenate doping there is a changeover in structure from monoclinic to triclinic for M=Fe, Co, Cu, with the larger Fe2+ system requiring the highest level of selenate to complete the changeover. Thus the results suggest that the relative stability of the two structure types is influenced by the relative size of the transition metal: oxoanion group, with the triclinic structure favoured for small transition metals/large oxoanions. The successful synthesis of fluorophosphate doped samples, Na2M(SO4)2-x(PO3F)x·2H2O was also obtained for M=Fe, Co, Cu, with the results showing a changeover in structure from monoclinic to triclinic for M=Co, Cu for very low levels (x=0.1) of fluorophosphate. In the case of M=Fe, the successful synthesis of fluorophosphates samples was achieved for x≤0.3, although no change in cell symmetry was observed. Rather in this particular case, the X-ray diffraction patterns showed evidence for selective peak broadening, attributed to local disorder as a result of the fluorophosphate group disrupting the H-bonding network. Overall the work highlights how isovalent doping can be exploited to alter the structures of Na2M(SO4)2·2H2O systems.

  10. Tuning metal sites of DABCO MOF for gas purification at ambient conditions

    OpenAIRE

    Chemchuen, Somboon; Zhou, Kui; Kabir, Nawsad Alam; Chen, Yao; Ke, Xiaoxing; Tendeloo, van, G; Verpoort, Francis

    2015-01-01

    Abstract: Metalorganic frameworks (MOFs) have emerged as new porous materials for capture and separation of binary gas mixtures. Tuning the metal sites in MOF structures has an impact on properties, which enhance affinity of gas adsorption and selectivity (e.g., surface area, cavity, electric field, etc.). The synthesis and characterization of a M-DABCO series (M = Ni, Co, Cu, Zn) of MOFs are described in this study. The experiments were conducted using multicomponent gas mixtures and the Ide...

  11. Accumulation of Heavy Metal Ions from Tanneries Wastes: An Approach For Chromium Removal Using Activated Charcoal

    OpenAIRE

    Tahir, H; 1G. Yasmeen; Akhtar, N; Sultan, M.; 1M. Qadri

    2012-01-01

    The environment is under increasing pressure from solid and liquid wastes emanating from the leather industry. These are inevitable by-products of the leather manufacturing process and causes significant pollution unless treated in some way prior to discharge. The tanneries wastes samples were collected from Lahore Pakistan. The samples were digested by wet oxidation method and the concentrations of metals: Cr, Co, Cu, Cd, Mn, Zn, Ni and Pb were estimated in sediments and liquid waste samples...

  12. Electrothermal atomic absorption spectrometric determination of cobalt, copper, lead and nickel traces in aragonite following flotation and extraction separation.

    Science.gov (United States)

    Zendelovska, D; Pavlovska, G; Cundeva, K; Stafilov, T

    2001-03-30

    A method of determination of Co, Cu, Pb and Ni in nanogram quantities from aragonite is presented. Flotation and extraction of Co, Cu, Pb and Ni is suggested as methods for elimination matrix interferences of calcium. The method of flotation is performed by iron(III) hexamethylenedithiocarbamate, Fe(HMDTC)(3), as a colloid precipitate collector. The liquid-liquid extraction of Co, Cu, Pb and Ni is carried out by sodium diethyldithiocarbamate, NaDDTC, as complexing reagent into methylisobutyl ketone, MIBK. The electrothermal atomic absorption spectrometry (ETAAS) is used for determination of analytes. The detection limits of ETAAS followed by flotation are: 7.8 ng.g(-1) for Co, 17.1 ng.g(-1) for Cu, 7.2 ng.g(-1) for Pb and 9.0 mug.g(-1) for Ni. The detection limits of ETAAS followed by extraction are found to be: 12.0 ng.g(-1) for Co, 51.0 ng.g(-1) for Cu, 24.0 ng.g(-1) for Pb and 21.0 ng.g(-1) for Ni.

  13. Coercivity behavior in Gd(Co{sub 1−x}Cu{sub x}){sub 5} system as function of the microstructureevolution

    Energy Technology Data Exchange (ETDEWEB)

    Pentón-Madrigal, A. [Facultad de Física, Universidad de La Habana, San Lazaro y L. C.P. 10400, C. Habana (Cuba); Oliveira, L.A.S. de, E-mail: laso.luiz@gmail.com [Instituto de Física “Gleb Wataghin”, Universidade Estadual de Campinas, Barão Geraldo, Campinas, SP (Brazil); Sinnecker, J.P.; Souza, D.M. [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud, 150—Urca, 22290-180, Rio de Janeiro (Brazil); Grössinger, R. [Institute für Festkörperphysik, TU Wien, Wiedner Hauptstr. 8-10, A-1040, Vienna (Austria); Concepción-Rosabal, B.; Estévez-Rams, E.; Diaz-Castañon, S. [Instituto de Ciencia y Tecnología de Materiales (IMRE), Zapata y G, Vedado. CP 10400, C. Habana (Cuba)

    2013-04-01

    Magnetic measurements, X-ray diffraction and scanning electron microscopy (SEM) experiments were carried out in the as-cast Gd(Co{sub 1−x}Cu{sub x}){sub 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 CaCu{sub 5}-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 CaCu{sub 5}-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){sub 5} phase. The relation between the observed microstructure and the magnetic behavior is also discussed.

  14. The electrochemical and physical properties of nanostructured magnetic multilayers

    CERN Document Server

    Dulal, S M S I

    2003-01-01

    The dissolution of Cu/Co-Cu/Cu has been studied using a rotating ring disc electrode. It has been found that cobalt and copper dissolve independently from the sandwich and cobalt dissolution occurs beneath the copper over-layer. When nickel is added to the electrolyte, cobalt dissolution is prevented due to the passivation of nickel, which acts as 'cement' and traps cobalt in the alloy layer. The dissolution of the ferromagnetic components during pulse plating of Ni-Co(Cu)/Cu multilayers suppresses before the formation of a monolayer of copper on the previously deposited ferromagnetic layer. The extent of the dissolution is a function of nickel concentration in the electrolyte. Ni-Co(Cu)/Cu multilayers with varied amounts of constituent metals have been deposited by controlling various electrochemical process parameters. It has been found that multilayers with a lower copper impurity in the ferromagnetic layers can be produced at greater high-pulse potentials. The variation of the electrolyte concentration ha...

  15. Faster extraction of heavy metals from soils using vacuum and ultrasonic energy.

    Science.gov (United States)

    Pontes, Fernanda V M; Carneiro, Manuel C; de da Souza, Evelyn M F; da Silva, Lílian I D; Monteiro, Maria Inês C; Neto, Arnaldo A

    2013-01-01

    A fast vacuum- and ultrasound-assisted acid extraction of Co, Cu, Fe, Mn, Pb, and Zn from soils using a homemade system has been investigated. Preliminarily, a full factorial design with two levels and three variables (extracting agent, extraction temperature, and sonication time) was applied to optimize the extraction conditions (without vacuum) for some heavy metals (Cu, Mn, Pb, and Zn). The best results were obtained with a 3:1 HCI extraction solution, temperature of 80 degrees C, and time of 2 h. As this sonication time was too long, a vacuum pump was used to produce air bubbles in order to increase the contact between the sample and the extracting agent and to prevent the sample sedimentation. This improvement drastically reduced the sonication time to 2 min. Under these conditions, Co, Cu, Mn, and Zn were totally extracted (recoveries of 86-99%), while recoveries of 73-76 and 74% were obtained for Fe and Pb, respectively. The LOD values using flame atomic absorption spectrometry for determination of Co, Cu, Fe, Mn, Pb, and Zn were 3.2, 7.5, 37.5, 7.5, 22.5, and 3.8 micro glg, respectively. The RSDs were lower than 11% (n = 3).

  16. Magnetoimpedance of Electroplated Wires with Large Core Diameters

    Institute of Scientific and Technical Information of China (English)

    C. Sirisathitkul; P. Jantaratana

    2009-01-01

    Monolayered Co and trilayered Co/Cu/Co were electroplated on 485 Μm-diameter Cu wires using the bath pH 2.5. These wires can be functioned as magnetic sensors owing to their magnetoimpedance (Ml) effect. By measuring at four different frequencies (100, 250, 500, and 1000 kHz) and Co thicknesses (2.5, 5.0, 10.0, and 25.0Μm), the Ml ratio of electroplated Co on Cu wires tended to increase with increasing Co thickness and frequency of the driving current. The Co/Cu/Co on Cu wires exhibited even higher Ml ratio. The magnetic layer also regulated the magnetic inductions and anisotropy regardless of the size of nonmagnetic core. Nevertheless, the diameter of the Cu core had a significant effect on the Ml ratio. By comparing with the 47.7 μm-diameter Ag cores electroplated by Co and Co/Cu/Co of the same thickness, the Cu cores with a larger diameter gave rise to a larger Ml ratio because their lower electrical resistance enhanced the crossing effect. Substantial Ml ratio was observed even in a low frequency regime because the skin effect occurred at a low frequency in the case of electroplated wires with large core diameters.

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

    Directory of Open Access Journals (Sweden)

    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.

  18. Interlayer Coupling of Co/NM/FM(NiFe and Co) Nano-Sandwich Films%Co/NM/FM(NiFe and Co)纳米多层膜的层间耦合效应

    Institute of Scientific and Technical Information of China (English)

    马晓艳; 毕晓昉; 宫声凯; 徐惠彬

    2003-01-01

    巨磁电阻自旋阀多层膜作为磁敏传感器材料与磁随机存储器(MRAM)材料,具有高的可靠性与灵敏度,在航空航天等高科技领域有着极大的应用前景.研究多层膜各层间的耦合效应与各层厚度、磁学性能之间的内在关系,对提高自旋阀的巨磁电阻效应、磁灵敏性等具有重要的作用.本研究采用磁控溅射沉积制备了(Cu/Co、Cu/NiFe, Ta/NiFe双层膜与 Co/Cu/Co、Co/Cu/NiFe、Co/Ta/NiFe)三明治结构薄膜.采用振动样品磁强计对薄膜磁性、四探针法对薄膜磁阻性能进行了测试研究,采用洛仑兹电子显微镜法观察了薄膜的磁畴结构.研究结果表明,层间耦合效应不仅与非磁性中间层的厚度相关,而且与中间层材料的特性相关.磁阻与磁畴观察均表明层间耦合效应随中间层厚度的增加而减小,而Cu作为中间层的多层膜的层间耦合大于Ta作为中间层的层间耦合.%Cu/Co, Cu/NiFe, Ta/NiFe bilayers and Co/Cu/Co, Co/Cu/NiFe, Co/Ta/NiFe sandwich films were deposited by a magnetron sputtering method. Magnetic properties were evaluated by VSM and spin valve magnetoresistance was investigated by a four-probe method to study the interlayer coupling of the two magnetic layers. It has been found that the interlayer coupling depended not only on the layer thickness of the nonmagnetic spacer but also on the nature of the spacer. The interlayer coupling was reduced as the spacer layer thickness increased. The result was consistent with those from observations of the magnetic domain for the trilayers by means of Lorentz Electron Microscope. The trilayers with Cu spacer layer have shown a stronger coupling than those with Ta spacer layer.

  19. Level and Contamination Assessment of Environmentally Sensitive Elements in Smaller than 100 μm Street Dust Particles from Xining, China

    Directory of Open Access Journals (Sweden)

    Ni Zhao

    2014-02-01

    Full Text Available Concentrations of the environmentally sensitive elements (ESEs As, Co, Cu, Mn, Ni, Pb, V and Zn in smaller than 100 μm street dust particles from Xining were measured using X-ray fluorescence spectrometry and their contamination levels were assessed based on enrichment factor (EF, geoaccumulation index (Igeo and pollution load index (PLI. The concentrations of As, Co, Cu, Mn, Ni, Pb, V and Zn in smaller than 100 μm street dust particles from Xining are 0.1–0.8, 2.7–10.9, 0.7–5.2, 0.3–1.1, 0.6–2.5, 1.2–11.1, 0.7–1.3 and 0.4–2.9 times the background values of Qinghai soil, respectively. The calculated EF and Igeo values reveal the order Co > Pb > Cu > Zn > V > Ni > Mn > As. The EF and Igeo values of Co, Cu, Pb and Zn are higher indicating that there is considerable pollution by these elements in smaller than 100 μm street dust particles, especially for Co. The EF and Igeo of Mn, Ni and V are lower and the assessment results indicate an absence of distinct Mn, Ni and V pollution in the studied samples. The mean value of PLIsite is 1.14, indicating a slightly pollution in the whole city of Xining. The order of PLIarea for the five tested districts is Center District (CD > East District (ED > West District (WD > North District (ND > South District (SD, showing that ESEs pollution in the South District is the lightest while it is the highest in the Central District.

  20. Hylocomium splendens (Hedw.) B.S.G. and Pleurozium schreberi (Brid.) Mitt. as trace element bioindicators: statistical comparison of bioaccumulative properties.

    Science.gov (United States)

    Dołegowska, Sabina; Migaszewski, Zdzisław M; Michalik, Artur

    2013-02-01

    The principal objective of this study was to compare bioaccumulative properties of two terrestrial moss species Hylocomium splendens and Pleurozium schreberi from the Kielce area (south-central Poland), using various statistical techniques. Forty-six moss samples from 23 sampling sites located within the city limits were analyzed for 33 trace elements. The results indicated that 17 elements (Ba, Ce, Co, Cu, Eu, Fe, Gd, Hg, La, Mo, Nd, Ni, Pb, Pr, Sm, V, Y) dominated in H. splendens, whereas only three elements (Mn, Sr, Zn) occurred in excessive amounts in P. schreberi. No differences in the distribution pattern of Dy, Er, Ho, Sn, Tb, Th and Yb were observed. The element concentration ratio (PI/Hy) varied from 0.50 to 1.19. For 14 elements (Ce, Co, Cu, Fe, Gd, Hg, La, Mo, Nd, Ni, Pb, Sm, Th, V), PI/Hy 1; for 7 elements (Ba, Dy, Er, Eu, Pr, Y, Yb), PI/Hy = equalled 1. Czekanowski's method showed similarities in rare earth element concentrations for both moss species. The cluster analysis exhibited three significant clusters at D(link)/D(max) x 100 < 50 for both moss species. Strong positive Spearman correlations between both moss species were recorded for the following pairs: Ba-Ba, Co-Co, Er-Er, Eu-Eu, Gd Gd, Mn-Mn, Ni-Ni, Pb-Pb, Pr-Pr, Sm-Sm, Th-Th, Y-Y, and Yb-Yb. Nonparametric tests (Sign test, Wilcoxon tests) showed statistically significant differences only for Cd, Ce, Co, Cu, Hg, Mo, Ni, Pb and Sr. The scanning electron microscope study of H. splendens and P. schreberi revealed a different morphology of these species with no injuries.

  1. Hylocomium splendens (Hedw.) B.S.G. and Pleurozium schreberi (Brid.) Mitt. as trace element bioindicators: Statistical comparison of bioaccumulative properties

    Institute of Scientific and Technical Information of China (English)

    Sabina Dol(e)gowska; Zdzistaw M.Migaszewski; Artur Michalik

    2013-01-01

    The principal objective of this study was to compare bioaccumulative properties of two terrestrial moss species Hylocomium splendens and Pleurozium schreberi from the Kielce area (south-central Poland),using various statistical techniques.Forty-six moss samples from 23 sampling sites located within the city limits were analyzed for 33 trace elements.The results indicated that 17 elements (Ba,Ce,Co,Cu,Eu,Fe,Gd,Hg,La,Mo,Nd,Ni,Pb,Pr,Sm,V,Y) dominated in H.splendens,whereas only three elements (Mn,Sr,Zn) occurred in excessive amounts in P.schreberi.No differences in the distribution pattern of Dy,Er,Ho,Sn,Tb,Th and Yb were observed.The element concentration ratio (PI/Hy) varied from 0.50 to 1.19.For 14 elements (Ce,Co,Cu,Fe,Gd,Hg,La,Mo,Nd,Ni,Pb,Sm,Th,V),PI/Hy < 1; for 4 elements (Cd,Mn,Sr,Zn),PI/Hy > 1; for 7 elements (Ba,Dy,Er,Eu,Pr,Y,Yb),PI/Hy =equalled 1.Czekanowski's method showed similarities in rare earth element concentrations for both moss species.The cluster analysis exhibited three significant clusters at Dlink/Dmax × 100 < 50 for both moss species.Strong positive Spearman correlations between both moss species were recorded for the following pairs:Ba-Ba,Co-Co,Er-Er,Eu-Eu,Gd Gd,Mn-Mn,Ni-Ni,Pb-Pb,Pr-Pr,Sm-Sm,Th-Th,Y-Y,and Yb-Yb.Nonparametric tests (Sign test,Wilcoxon tests) showed statistically significant differences only for Cd,Ce,Co,Cu,Hg,Mo,Ni,Pb and Sr.The scanning electron microscope study of H.splendens and P.schreberi revealed a different morphology of these species with no injuries.

  2. 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

    Directory of Open Access Journals (Sweden)

    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.

  3. 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

    Directory of Open Access Journals (Sweden)

    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.

  4. Preparation and structural, optical, magnetic, and electrical characterization of Mn{sup 2+}/Co{sup 2+}/Cu{sup 2+} doped hematite nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Srikrishna Ramya, S.I., E-mail: ramyaskr@gmail.com; Mahadevan, C.K.

    2014-03-15

    Pure and Mn{sup 2+} / Co{sup 2+} / Cu{sup 2+} doped (1 and 2 at.%) spherical hematite (α-Fe{sub 2}O{sub 3})nanocrystals have been synthesized by a simple solvothermal method using a domestic microwave oven. XRD measurements confirm that all the seven nanocrystals prepared consist of nanocrystalline hematite phase without any other phases. The energy dispersive X-ray and Fourier transform infrared spectral analyses confirm the phase purity of the nanocrystals prepared. TEM analysis shows the average particle sizes within the range 33–51 nm. Optical absorption measurements indicate that all the three dopants enhance the optical transmittance and reflectance. A red shift is observed in the bandgap energy values estimated from optical absorption and reflectance spectra. Results of magnetic measurements made at room temperature using a vibrating sample magnetometer indicate significant changes in the magnetic properties (coercivity, retentivity and saturationmagnetization) due to doping. Results of magnetic measurements indicate significant changes in the magnetic properties. Results of AC electrical measurements made at various temperatures in the range 40–130 °C and frequencies in the range 100 Hz –1 MHz indicate low dielectric constants and AC electrical conductivities and consequently show the occurrence of nanoconfined states. -- Graphical abstract: The indexed X-ray diffraction (XRD) patterns of all the seven nanocrystals indicate the rhombohedral structure of hematite (JCPDS card No.13-0534). No impurity phase like oxides of Mn or Co or Cu was detected above equipment limit. The average crystallite (grain) sizes estimated using the Scherrer's formula. Highlights: • Pure and Mn/Co/Cu-doped hematite nanocrystals have been prepared. • The method adopted for the preparation is simple, economical and scalable. • Prepared nanocrystals are spherical in shape with good crystallinity and phase purity. • Mn/Co/Cu-doping enhances the optical

  5. Multielement trace determinations in A1 2O 3 ceramic powders by inductively coupled plasma mass spectrometry with special reference to on-line trace preconcentration

    Science.gov (United States)

    Pollmann, D.; Leis, F.; Tölg, G.; Tschöpel, P.; Broekaert, J. A. C.

    1994-12-01

    The use of inductively coupled plasma mass spectrometry (ICP-MS) for the determination of trace elements in Al 2O 3 powders is reported. Special interest is given to a preconcentration of the trace elements by on-line coupling of chromatography to ICP-MS. This is based on the complexation of Co, Cu, Cr, Fe, Ga, Mn, Ni, V and Zn with hexamethylene-dithiocarbamate (HMDC), their preconcentration on a C18 RP column by reversed phase liquid chromatography and their elution with CH 3OH-H 2O mixtures. A direct coupling of the HPLC system to the ICP-MS has been realized by high pressure pneumatic nebulization using desolvation. With the Chromatographie method developed, removal of the AI by at least 99% was achieved. For the trace elements V, Fe, Ni, Co, Cu and Ga, high and reproducible recoveries (ranging from 96-99%) were reached. The method developed has been shown to considerably enhance the power of detection as compared with direct procedures, namely down to 0.02-0.16 ( μg/g for V and Fe, respectively. The possibilities of the method are shown by the determinations of V, Mn, Fe, Ni, Co, Cu, Zn and Ga at the μg/g level in A1 2O 3 powders. The accuracy of the method at the 0.06 to 9.0 μg/g level for Co and Fe, respectively, is demonstrated by a comparison with results of independent methods from the literature.

  6. Microstructural changes during the slow-cooling annealing of nanocrystalline SmCo 2:17 type magnets

    Energy Technology Data Exchange (ETDEWEB)

    Romero, S.A. [Instituto de Fisica da Universidade de Sao Paulo, Sao Paulo (Brazil); Escola Politecnica da Universidade de Sao Paulo, Sao Paulo (Brazil); Campos, M.F. de, E-mail: mcampos@metal.eeimvr.uff.br [PUVR - Universidade Federal Fluminense, Av. dos Trabalhadores 420, Vila Santa Cecilia, Volta Redonda, RJ 27255-125 (Brazil); Castro, J.A. de [PUVR - Universidade Federal Fluminense, Av. dos Trabalhadores 420, Vila Santa Cecilia, Volta Redonda, RJ 27255-125 (Brazil); Moreira, A.J. [Escola Politecnica da Universidade de Sao Paulo, Sao Paulo (Brazil); Landgraf, F.J.G. [Escola Politecnica da Universidade de Sao Paulo, Sao Paulo (Brazil); Instituto de Pesquisas Tecnologicas do Estado de Sao Paulo, Sao Paulo (Brazil)

    2013-02-25

    Highlights: Black-Right-Pointing-Pointer Use of the Stoner-Wohlfarth Callen Liu Cullen model in 2:17 type magnets. Black-Right-Pointing-Pointer Data suggest exchange coupling between Sm2(CoFe)17 and Sm(CoCu)5 phases. Black-Right-Pointing-Pointer It is given structural data for phase Sm0.33Zr0.67TM3, with TM=Co,Fe,Cu. Black-Right-Pointing-Pointer The beneficial effect of the slow cooling treatment is explained. - Abstract: The microstructure and magnetic properties of 2:17 type isotropic magnets were investigated. The slow cooling heat treatment (cooling at 1 Degree-Sign C/min from 820 to 400 Degree-Sign C, and isothermal treatment during 24 h) was interrupted after the temperatures of 820, 700, 600 and 500 Degree-Sign C and their hysteresis were measured with fields up to 9 T. The fully heat treated sample presented coercivity ({mu}{sub 0}H) of 3.32 T, after 24 h at 400 Degree-Sign C. The microstructure was investigated with SEM-FEG (Scanning Electron Microscope with Field Emission Gun) and X-ray Diffraction Rietveld analysis. The application of the Stoner-Wohlfarth-Callen-Liu-Cullen (SW-CLC) model points out exchange coupling between ferromagnetic Sm{sub 2}(CoFe){sub 17} nanocells and ferromagnetic Sm(CoCu){sub 5} present at the cell boundary phase. The results are interpreted with the double shell model: first-a cobalt-rich ferromagnetic Sm(CoCu){sub 5} shell originates exchange coupling and second-a copper-rich paramagnetic Sm(CuCo){sub 5} shell produces magnetic decoupling. This double shell helps to maximize coercivity and remanence. The anisotropy field of the Sm{sub 2}(CoFe){sub 17} cell phase was estimated in 7 T with the SW-CLC model.

  7. Temperature derivative of the resistance of spin valves

    Energy Technology Data Exchange (ETDEWEB)

    Granville, Simon, E-mail: simon.granville@epfl.c [Institut de Physique des Nanostrutures, Ecole Polytechnique Federale de Lausanne, Station 3, CH-1015 Lausanne (Switzerland); Yu Haiming [Institut de Physique des Nanostrutures, Ecole Polytechnique Federale de Lausanne, Station 3, CH-1015 Lausanne (Switzerland); State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Dubois, Julie [Institut de Physique des Nanostrutures, Ecole Polytechnique Federale de Lausanne, Station 3, CH-1015 Lausanne (Switzerland); Ecole des Mines, 60 bd Saint Michel 75006 Paris (France); Gravier, Laurent; Ansermet, Jean-Philippe [Institut de Physique des Nanostrutures, Ecole Polytechnique Federale de Lausanne, Station 3, CH-1015 Lausanne (Switzerland)

    2010-05-15

    Spin-dependent transport properties of nanowires containing individual Co/Cu/Co pseudo-spin valves were investigated by monitoring an AC voltage induced by a temperature oscillation under a continuous DC current. We observed sharp peaks in the field-dependent AC voltage response. These peaks only appear close to the magnetic field range where conventional magnetoresistance shows a reversible and gradual transition. The effect is interpreted as an extra dissipation process with a distinct temperature dependence that occurs in non-collinear magnetic configurations when transverse moment relaxation takes place.

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

    Institute of Scientific and Technical Information of China (English)

    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.

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

    Institute of Scientific and Technical Information of China (English)

    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.

  10. The distribution and fixation of trace elements by the Vertisols of Malaga, southern Spain

    Energy Technology Data Exchange (ETDEWEB)

    Castillo-Carrion, Mercedes [Instituto Geologico y Minero de Espana (IGME), Centro de Laboratorios, C/ La Calera 1, 28760 Tres Cantos, Madrid (Spain)]. E-mail: m.castillo@igme.es; Martin-Rubi, Juan Antonio [Instituto Geologico y Minero de Espana (IGME), Centro de Laboratorios, C/ La Calera 1, 28760 Tres Cantos, Madrid (Spain)]. E-mail: ja.martin@igme.es; Ortega Bernaldo de Quiros, Eduardo [Departamento de Edafologia y Quimica Agricola, Universidad de Granada, Facultad de Farmacia Campus Universitario de Cartuja s/n Granada (Spain)]. E-mail: eortega@ugr.es

    2007-05-25

    The response of Vertisols to contamination by heavy metals (As, Cd, Pb, Hg) and micronutrients (Co, Cu, Cr, Ni, V, Zn) in toxic concentrations was studied in a series of experiments undertaken with soil samples from the province of Malaga, in Southern Spain. The soil samples were placed in methacrylate columns, passing through a contaminant solution of selected elements in order to study their distribution and fixation the soil. Systematic sampling and sequential extraction analysis show that the Vertisols behave as a buffer to all elements, except cadmium.

  11. Ag-CuO钎料与BaCo0.7Fe0.2Nb0.1O3-δ透氧膜陶瓷润湿及界面反应机理的研究%The wetting and interface reaction mechanism of Ag-Cu-O brazes on BaCo0.7Fe0.2Nb0.1O3-δ oxygen-permeable membrane ceramic

    Institute of Scientific and Technical Information of China (English)

    张齐飞; 耿振; 张玉文; 侯丽娟; 王海海; 丁伟中; 鲁雄刚

    2012-01-01

    The wetting and interface reaction mechanism of Ag-Cu-O brazes on BaCo0.7Fe0.2Nb0.1O3-δ(BCFNO) oxygen-permeable membrane ceramic were investigated by the sessile drop wetting experiment and SEM/EDS test.The results indicate that the wetting of Ag-Cu-O brazes on BCFNO follow the wetting mechanism of interface reaction,with the Cu content and temperature increased,wetting angle rapid decreased.When the content of Cu was 3.3mol%,in BCFNO side at the interface a layer of reactive layer was generated.The existence of reactive layer reduced the liquid-solid interfacial energies,then improved the wettability of interface and enhanced the mutual metallurgy effect.Reactive layer are caused by the interface reaction(CuOx+BaCoFeNbO→Ba-Cu-O + Co-Cu-O) occurs in the interface.The complex oxide Ba-Cu-O,Co-Cu-O in the grain boundary of BCFNO matrix show island shape distributed.%利用座滴法润湿实验,借助SEM和EDS测试,研究了Ag-CuO钎料与BaCo0.7Fe0.2Nb0.1O3-δ透氧膜陶瓷润湿及界面反应机理。结果表明Ag-Cu-O/BCFNO间的润湿遵从界面反应润湿机制,随Cu含量增加和温度升高,润湿角快速减小。当Cu含量为3.3%(摩尔分数)时,在界面处BCFNO侧开始生成1层反应层,反应层的存在降低了固液界面能,使界面润湿性得到改善,相互冶金作用增强。反应层产生的原因是界面处发生了界面反应CuOx+BaCoFeNbO→Ba-Cu-O+Co-Cu-O,生成的复杂氧化物Ba-Cu-O、Co-Cu-O在BCFNO基体的晶粒边界上呈岛状分布。

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

    Directory of Open Access Journals (Sweden)

    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.

  13. Avaliação do risco ambiental em sedimento dos lagos do Riacho Cambé, em Londrina, pela distribuição de metais Avaliation of the environmental risk by metal distribution in sediments from lakes formed by Cambé Stream at Londrina

    Directory of Open Access Journals (Sweden)

    Dílson Norio Ishikawa

    2009-01-01

    Full Text Available The proposal of this study was to obtain the profile of these metals distribution Al, Co, Cu, Pb, Cr, Ni, Co and Zn in sediments from lakes in the city of Londrina-PR and evaluate the environmental risk resulting from such distribution. The parameters of comparison were the values of geological occurrence of these metals in soil from this region, the concentrations of metals in soil samples in the surroundings of the sediments collection points, the guiding values from CETESB and resulting rate risk from RAC criterion application. The result shows that the numerical scale RAC alone is incomplete to this evaluation.

  14. Avaliação do risco ambiental em sedimento dos lagos do Riacho Cambé, em Londrina, pela distribuição de metais Avaliation of the environmental risk by metal distribution in sediments from lakes formed by Cambé Stream at Londrina

    OpenAIRE

    2009-01-01

    The proposal of this study was to obtain the profile of these metals distribution Al, Co, Cu, Pb, Cr, Ni, Co and Zn in sediments from lakes in the city of Londrina-PR and evaluate the environmental risk resulting from such distribution. The parameters of comparison were the values of geological occurrence of these metals in soil from this region, the concentrations of metals in soil samples in the surroundings of the sediments collection points, the guiding values from CETESB and resulting ra...

  15. Avaliação do risco ambiental em sedimento dos lagos do Riacho Cambé, em Londrina, pela distribuição de metais

    OpenAIRE

    2009-01-01

    The proposal of this study was to obtain the profile of these metals distribution Al, Co, Cu, Pb, Cr, Ni, Co and Zn in sediments from lakes in the city of Londrina-PR and evaluate the environmental risk resulting from such distribution. The parameters of comparison were the values of geological occurrence of these metals in soil from this region, the concentrations of metals in soil samples in the surroundings of the sediments collection points, the guiding values from CETESB and resulting ra...

  16. 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 {sup 12}CO - {sup 14}CO mixture (1962); Contribution a l'etude d'une methode de mesure continue de l'effet isotopique. Recherche d'un effet isotopique dans la reduction de l'oxyde cuivreux par le melange {sup 12}CO - {sup 14}CO (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Richard, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-15

    The determination of an isotopic effect between the two reactions: {sup 12}CO + Cu{sub 2}O {yields} {sup 12}CO{sub 2} + 2 Cu 'light' reaction {sup 14}CO + Cu{sub 2}O {yields} {sup 14}C{sub O}2 + 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) [French] La determination d'un effet isotopique entre les deux reactions: {sup 12}CO + Cu{sub 2}O {yields} {sup 12}CO{sub 2} + 2 Cu reaction 'legere' {sup 14}CO + Cu{sub 2}O {yields} {sup 14}C{sub O}2 + 2 Cu reaction 'lourde' est rendue possible par la connaissance de leurs cinetiques respectives. La condensation, au cours de la reaction, du gaz carbonique forme et la mesure en fonction du temps de la pression de l'oxyde de carbone residuel, permet d'obtenir, de facon continue, la cinetique de la reaction 'legere'. La cinetique de la reaction lourde est determinee par la mesure continue, in situ, du taux de radioactivite du reactif gazeux residuel en fonction du temps. Le dispositif employe dans ce but est un compteur a scintillateur plastique. Une courbe d'etalonnage, du taux mesure de

  17. Variation des éléments présents à l'état de traces dans les glaces polaires pendant la fin du quartenaire, notamment en liaison avec les retombées de matière extraterrestre

    OpenAIRE

    Gabrielli, Paolo

    2004-01-01

    The determination of trace elements in deep polar ice cores provides important environmental information concerning natural sources, long-range transport and deposition processes of the aerosol during the late Quaternary (Iast few hundred thousands years). ln this work, we have measured various trace elements (Li, Mg, V, Cr, Mn, Co, Cu, As, Rb, Sr, Cd, Ba, Ir, Pt, Hg (including MeHg and Hg2+), Pb (including Pb isotopes), Bi and U) in various sections of three deep ice cores which were drilled...

  18. Stress induced grain boundaries in thin Co layer deposited on Au and Cu

    Science.gov (United States)

    Zientarski, Tomasz; Chocyk, Dariusz

    2016-10-01

    In this work, the structure and stress evolution in Co/Au and Co/Cu two-layer systems during deposition were studied. The growth of this system is evaluated by employing molecular dynamic simulations with potentials based on the embedded atom method theory. We used the kinematical scattering theory and the Ackland-Jones bond-angle method to the structural characterisation of deposited layers. In both systems, only compressive stress is observed during the deposition process and process relaxation of stress is visible. In Co/Au systems, creation of grains and grain boundaries is observed.

  19. Manipulation of pure spin current in ferromagnetic metals independent of magnetization

    Science.gov (United States)

    Tian, Dai; Li, Yufan; Qu, D.; Huang, S. Y.; Jin, Xiaofeng; Chien, C. L.

    2016-07-01

    Upon the injection of a pure spin current, a ferromagnet, similar to a nonmagnetic metal, also exhibits inverse spin Hall effect (ISHE). We show in Co/Cu/YIG, where the thin Cu layer allows transmission of spin current from YIG into Co but decouples the two ferromagnets, that the interaction between ISHE and ferromagnetic ordering in Co can be unambiguously investigated. By switching on and off the pure spin current contribution, we demonstrate that the ISHE in Co is independent of the direction of the Co magnetization, which clearly suggests that the ISHE in Co is dominated not by the extrinsic impurity scatterings, but from the intrinsic origin.

  20. 几块铁陨石的火花源质谱分析

    Institute of Scientific and Technical Information of China (English)

    李肇辉

    1979-01-01

    Iron meteorites from Nandan, Guangxi ; Wushike, Xinjiang; Shangdu, Hebei and Huangling, Hubei are investigated with a spark souree mass speetrometer for their Cr, Ni, Co, Cu, Zn, Ga, Ge, As, Mo, Ru, Rh, Pd, Os and Ir contents. The accuracy of the results and the factors affecting it are discussed. It is preliminarily concluded,while textural evidences of these meteorites are also taken into account, that the Nandan, Wushike and Shangdu meteorites belong to IA, Ⅲ .4 and ⅢE groups respectively. The Ni, Ga and Ge contents in the Huangling iron meteorite come close to that of mesosiderites.

  1. Electrochemical and optical characterization of cobalt, copper and zinc phthalocyanine complexes.

    Science.gov (United States)

    Lee, Jaehyun; Kim, Se Hun; Lee, Woosung; Lee, Jiwon; An, Byeong-Kwan; Oh, Se Young; Kim, Jae Pil; Park, Jongwook

    2013-06-01

    New phthalocyanine (Pc) derivatives that include the alkyl group in ligand were synthesized based on three core metals such as zinc (Zn), copper (Cu), and cobalt (Co). Electrochemical behaviors and optical properties of the new phthalocyanine derivatives with ligand and different core metal were investigated by using cyclic voltammetry, UV-Visible (UV-Vis) spectroscopy and photoluminescence (PL) spectroscopy. In UV-Vis data, maximum values of 2H, Co, Cu, and Zn complexes were 708 nm and 677 nm, 686 nm, 684 nm, respectively.

  2. Sequential-injection on-line preconcentration using chitosan resin functionalized with 2-amino-5-hydroxy benzoic acid for the determination of trace elements in environmental water samples by inductively coupled plasma-atomic emission spectrometry

    OpenAIRE

    2007-01-01

    A new chelating resin using chitosan as a base material was synthesized. Functional moiety of 2-amino-5-hydroxy benzoic acid (AHBA) was chemically bonded to the amino group of cross-linked chitosan (CCTS) through the arm of chloromethyloxirane (CCTS-AHBA resin). Several elements, such as Ag, Be, Cd, Co, Cu, Ni, Ph, U, V, and rare earth elements (REEs), could be adsorbed on the resin. To use the resin for on-line pretreatment, the resin was packed in a mini-column and installed into a sequenti...

  3. Electronically induced atom motion in engineered CoCun nanostructures.

    Science.gov (United States)

    Stroscio, Joseph A; Tavazza, Francesca; Crain, Jason N; Celotta, Robert J; Chaka, Anne M

    2006-08-18

    We have measured the quantum yield for exciting the motion of a single Co atom in CoCu(n) linear molecules constructed on a Cu(111) surface. The Co atom switched between two lattice positions during electron excitation from the tip of a scanning tunneling microscope. The tip location with highest probability for inducing motion was consistent with the position of an active state identified through electronic structure calculations. Atom motion within the molecule decreased with increased molecular length and reflected the corresponding variation in electronic structure.

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

    OpenAIRE

    MIRJANA D. MARJANOVIĆ; MARIJA M. VUKČEVIĆ; DUŠAN G. ANTONOVIĆ; SUZANA I. DIMITRIJEVIĆ; ĐORĐE M. JOVANOVIĆ; Milan N. Matavulj; MIRJANA Đ. RISTIĆ

    2009-01-01

    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 a...

  5. Analysis of toxic elements in two pigeonpea (Cajanus cajan (L.) Millsp) cultivars, in fertilized soils, by neutron activation; Analise de elementos toxicos em duas variedades de guandu (Cajanus cajan (L.) Millsp), cultivadas em solos tratados, por ativacao com neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Piasentin, Ricardo M.; Armelin, Maria Jose A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Divisao de Radioquimica; Primavesi, Odo [Empresa Brasileira de Pesquisa Agropecuaria (EMBRAPA), Sao Carlos, SP (Brazil). Centro de Pesquisa de Pecuaria do Sudeste

    2000-07-01

    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)

  6. PIXE analysis of ancient Chinese Changsha porcelain

    Energy Technology Data Exchange (ETDEWEB)

    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.

  7. Systematic B-metal substitution in CaNi5

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Bjerrum, Niels

    1999-01-01

    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...... be concluded that CaNi5 is much less tolerant towards B-metal substitution than LaNi5. This fact makes it less possible that the problem with cycling stability of Ca-based hydride electrodes can be solved by substitutions. (C) 1999 Elsevier Science S.A. All rights reserved....

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

    Directory of Open Access Journals (Sweden)

    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

  9. Cobalt-rich alloys electrodeposited on silicon; Filmes de ligas ricas em cobalto eletrodepositado sobre silicio

    Energy Technology Data Exchange (ETDEWEB)

    Spada, E.R.; Dotto, M.E.R.; Sartorelli, M.L. [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Departamento de Fisica. Lab. de Sistemas Nanoestruturados; Paula, F.R. de, E-mail: depaula@dfq.feis.unesp.br [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Ilha Solteira, SP (Brazil). Departamento de Fisica e Quimica

    2014-07-01

    We report the electrodeposition (ED) of cobalt-rich alloy films on n-type Si (100) substrates in aqueous solution. A small amount of copper sulphate in the bath improved the quality of cobalt-rich films. The bath proved to be appropriate for the production of electrodeposited magnetic antidote structures prepared by nanosphere lithography technique. X-ray measurements indicate a mixture of hcp and fcc CoCu structures and strong texture in the (001) hcp and (111) fcc direction. Magnetic behavior was shown to be dependent on the thickness, which directly affects the domain wall pinning and the presence of superparamagnetism. (author)

  10. Modelling of habitat conditions by self-organizing feature maps using relations between soil, plant chemical properties and type of basaltoides

    Directory of Open Access Journals (Sweden)

    Piotr Kosiba

    2011-01-01

    Full Text Available The paper shows the use of Kohonen's network for classification of basaltoides on the base of chemical properties of soils and Polypodium vulgare L. The study area was Lower Silesia (Poland. The archival data were: chemical composition of types of basaltoides from 89 sites (Al2O3, CaO, FeO, Fe2O3, K2O, MgO, MnO, Na2O, P2O5, SiO2 and TiO2, elements contents in soils (Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb, S, Ti and Zn and leaves of P. vulgare (Ca, Cd, Co, Cu, Fe, K, Mg, Mn, Mo, N, Ni, P, Pb, S, Ti and Zn from 20 sites. Descriptive statistical parameters of soils and leaves chemical properties have been shown, statistical analyses using ANOVA and relationships between chemical elements were carried out, and SOFM models have been constructed. The study revealed that the ordination of individuals and groups of neurons in topological maps of plant and soil chemical properties are similar. The constructed models are related with significantly different contents of elements in plants and soils. These models represent different chemical types of soils and are connected with ordination of types of basaltoides worked out by SOFM model of TAS division. The SOFM appeared to be a useful technique for ordination of ecological data and provides a novel framework for the discovery and forecasting of ecosystem properties.

  11. The London penetration depth in BaFe{sub 2}As{sub 2} superconductors at high electron doping level

    Energy Technology Data Exchange (ETDEWEB)

    Martin, C; Kim, H; Gordon, R T; Ni, N; Thaler, A; Kogan, V G; Bud' ko, S L; Canfield, P C; Tanatar, M A; Prozorov, R, E-mail: cmartin@phys.ufl.ed [Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States)

    2010-06-15

    We compare the temperature dependences of the in-plane London penetration depth ({Delta}{lambda}{sub ab}(T)) for several Ba(Fe{sub 1-x}TM{sub x}){sub 2}As{sub 2} (TM = Co, Ni, Pd, Co + Cu) superconductors at high concentration of electrons, n{sub e}, added per Fe site. We show that regardless of the transition metal TM, for n{sub e} {>=} 0.12, the penetration depth has a power-law temperature dependence {Delta}{lambda}{sub L}(T){proportional_to}T{sup n}, but with the exponent n{approx}1.65, thus significantly lower than the value n {>=} 2 previously reported for lower electron concentrations. On doping with electrons from the 3d shells, the magnitude of the variation with temperature of {Delta}{lambda}{sub L}(T) is larger for Ni substitution than for Co substitution, and larger for Co + Cu co-doping than for Ni co-doping. However, comparing the effect of 3d and 4d electrons, for the isovalent elements Ni and Pd respectively, we found that the rates of change in penetration depth with temperature are nearly identical for the two compounds.

  12. The sticking probability for H-2 in presence of CO on some transition metals at a hydrogen pressure of 1 bar

    DEFF Research Database (Denmark)

    Johansson, Martin; Lytken, Ole; Chorkendorff, Ib

    2008-01-01

    The sticking probability for H-2 on Ni, Co, Cu, Rh, Ru, Pd, it and Pt metal films supported on graphite has been investigated in a gas mixture consisting of 10 ppm carbon monoxide in hydrogen at a total pressure of 1 bar in the temperature range 40-200 degrees C. Carbon monoxide inhibits the stic......The sticking probability for H-2 on Ni, Co, Cu, Rh, Ru, Pd, it and Pt metal films supported on graphite has been investigated in a gas mixture consisting of 10 ppm carbon monoxide in hydrogen at a total pressure of 1 bar in the temperature range 40-200 degrees C. Carbon monoxide inhibits...... in presence of CO relative to its value in pure hydrogen is largest for Pd and smallest for Pt and It. The high sensitivity to CO seen for It and Pt is explained by the fact that the difference in desorption energy for H and CO is largest for those metals. (C) 2008 Elsevier B.V. All rights reserved....

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

    Institute of Scientific and Technical Information of China (English)

    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.

  14. Magnetic stripe domains in coupled magnetic sandwiches%自旋转向相变中的条纹磁畴研究

    Institute of Scientific and Technical Information of China (English)

    吴义政

    2005-01-01

    用光激发电子显微镜研究了Fe/Ni铁磁膜和Co/Cu/Fe/Ni磁耦合膜中的条纹磁畴. 实验发现:在Fe/Ni体系中,条纹磁畴宽度随着铁层厚度趋近于自旋转向相变点呈指数下降;在Co/Cu/Fe/Ni体系中,Fe/Ni层中的条纹磁畴会沿着钴层磁矩的方向排列,其磁畴宽度会随着Co-Fe/Ni间的层间耦合强度呈指数下降. 理论上推导出条纹磁畴随着磁各向异性能和层间耦合强度变化的统一公式,而实验结果与理论符合得非常好.

  15. Facile method to synthesize dopamine-capped mixed ferrite nanoparticles and their peroxidase-like activity

    Science.gov (United States)

    Mumtaz, Shazia; Wang, Li-Sheng; Abdullah, Muhammad; Zajif Hussain, Syed; Iqbal, Zafar; Rotello, Vincent M.; Hussain, Irshad

    2017-03-01

    A facile single-step strategy to prepare stable and water-dispersible dopamine-functionalized ultra-small mixed ferrite nanoparticles MFe2O4-DOPA (where M is a bivalent metal atom i.e. Fe, Co Cu, Mn and Ni) at room temperature is described. The nanoparticles formed have narrow size distribution as indicated by their characterization using transmission electron microscopy (TEM) and dynamic light scattering. The surface chemistry of these nanoparticles was probed by FTIR spectroscopy indicating their successful capping with dopamine ligands, which was further confirmed using zetapotential measurements and thermogravimetric analysis. The comparative horseradish peroxidase (HRP)—like activity of these cationic mixed ferrites nanoparticles was studied at pH 4.6 using a negatively-charged 2, 2‧-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) as a chromogenic substrate in the presence of hydrogen peroxide. A time-dependent relative peroxidase-like activity follows the following order CoFe2O4-DOPA  >  MnFe2O4-DOPA  >  CuFe2O4-DOPA  >  NiFe2O4-DOPA  >  Fe3O4-DOPA. This diversity in HRP-like activity may be attributed to the different redox properties of ferrite nanoparticles when doped with M (Fe, Co Cu, Mn and Ni).

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

    Institute of Scientific and Technical Information of China (English)

    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.

  17. 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

    Energy Technology Data Exchange (ETDEWEB)

    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)

  18. Storage capacity and oxygen mobility in mixed oxides from transition metals promoted by cerium

    Energy Technology Data Exchange (ETDEWEB)

    Perdomo, Camilo [Estado Sólido y Catálisis Ambiental (ESCA), Departamento de Química, Facultad de Ciencias, Universidad Nacional de Colombia, Carrera 30 45-03, Bogotá (Colombia); Pérez, Alejandro [Grupo de Investigación Fitoquímica (GIFUJ), Departamento de Química, Facultad de Ciencias, Pontificia Universidad Javeriana, Carrera 7 No. 43-82, Bogotá D.C (Colombia); Molina, Rafael [Estado Sólido y Catálisis Ambiental (ESCA), Departamento de Química, Facultad de Ciencias, Universidad Nacional de Colombia, Carrera 30 45-03, Bogotá (Colombia); Moreno, Sonia, E-mail: smorenog@unal.edu.co [Estado Sólido y Catálisis Ambiental (ESCA), Departamento de Química, Facultad de Ciencias, Universidad Nacional de Colombia, Carrera 30 45-03, Bogotá (Colombia)

    2016-10-15

    Highlights: • Ce addition to the catalysts improves the availability of oxygen in the materials. • Mixed oxide with Co and Cu exhibits the best oxygen transport properties. • Co presence improves O{sub 2} mobility in the catalysts. • The presence of Cu in the solids improves redox properties. - Abstract: The oxygen mobility and storage capacity of Ce-Co/Cu-MgAl or Ce–MgAl mixed oxides, obtained by hydrotalcite precursors, were evaluated using Toluene-temperature-programmed-reaction, {sup 18}O{sub 2} isotopic exchange and O{sub 2}-H{sub 2} titration. The presence of oxygen vacancies-related species was evaluated by means of Electron Paramagnetic Resonance. A correlation was found between the studied properties and the catalytic activity of the oxides in total oxidation processes. It was evidenced that catalytic activity depends on two related processes: the facility with which the solid can be reduced and its ability to regenerate itself in the presence of molecular oxygen in the gas phase. These processes are enhanced by Cu-Co cooperative effect in the mixed oxides. Additionally, the incorporation of Ce in the Co-Cu catalysts improved their oxygen transport properties.

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

    Directory of Open Access Journals (Sweden)

    Hao Chen

    2016-06-01

    Full Text Available 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.

  20. Simultaneous determination of some trace metal impurities in high-purity sodium tungstate using coprecipitation and inductively coupled plasma atomic emission spectrometry

    Institute of Scientific and Technical Information of China (English)

    MA Xiaoguo; KUANG Tongchun; LIU Qianjun

    2004-01-01

    A method based on the combination of coprecipitation with inductively coupled plasma atomic emission spec trometry (ICP-AES) was developed for the determination of impurities in high-purity sodium tungstate. Six elements (Co,Cu, Fe, Mn, Ni, and Pb) were coprecipitated by lanthanum hydroxide so as to be concentrated and separated from the tungsten matrix. Effects of some factors on the recoveries of the analytes and on the residual amount of sodium tungstate were investigated, and the optimum conditions for the coprecipitation were proposed. Matrix-matching calibration curve method was used for the analysis. It is shown that the elements mentioned above can be quantitatively recovered. The detection limits for Co, Cu, Fe, Mn, Ni, and Pb are 0.07, 0.4, 0.2, 0.1, 0.6, and 1.3 μg.g-1, respectively. The recoveries vary from 92.5% to 108%, and the relative standard deviations (RSDs) are in the range of 3.1%-5.5%.

  1. Cobalt/copper-decorated carbon nanofibers as novel non-precious electrocatalyst for methanol electrooxidation

    Science.gov (United States)

    Barakat, Nasser A. M.; El-Newehy, Mohamed; Al-Deyab, Salem S.; Kim, Hak Yong

    2014-01-01

    In this study, Co/Cu-decorated carbon nanofibers are introduced as novel electrocatalyst for methanol oxidation. The introduced nanofibers have been prepared based on graphitization of poly(vinyl alcohol) which has high carbon content compared to many polymer precursors for carbon nanofiber synthesis. Typically, calcination in argon atmosphere of electrospun nanofibers composed of cobalt acetate tetrahydrate, copper acetate monohydrate, and poly(vinyl alcohol) leads to form carbon nanofibers decorated by CoCu nanoparticles. The graphitization of the poly(vinyl alcohol) has been enhanced due to presence of cobalt which acts as effective catalyst. The physicochemical characterization affirmed that the metallic nanoparticles are sheathed by thin crystalline graphite layer. Investigation of the electrocatalytic activity of the introduced nanofibers toward methanol oxidation indicates good performance, as the corresponding onset potential was small compared to many reported materials; 310 mV (vs. Ag/AgCl electrode) and a current density of 12 mA/cm2 was obtained. Moreover, due to the graphite shield, good stability was observed. Overall, the introduced study opens new avenue for cheap and stable transition metals-based nanostructures as non-precious catalysts for fuel cell applications.

  2. Accumulation of metallic elements by Amanita muscaria from rural lowland and industrial upland regions.

    Science.gov (United States)

    Lipka, Krzysztof; Falandysz, Jerzy

    2017-03-04

    This study was carried out on the accumulation and occurrence of Ag, Al, Ba, Ca, Cd, Co, Cu, Fe, Hg, K, Mg, Mn, Na, Rb, Sr and Zn in the mushroom Amanita muscaria and forest topsoil from two lowland sites in the Tuchola Pinewoods in the north-central region and an upland site in the Świetokrzyskie Mountains in the south-central region of Poland. Topsoil from the upland location showed Ag, Al, Ba, Ca, Cd, Co, Cu, Fe, Hg, Na and Zn at significantly higher concentration levels (pseudo-total fraction and often also the labile or extractable fraction) than at both lowland locations, where topsoil was richer in Mg, and similar in Rb. Amanita muscaria from the upland region differed from individuals collected in the lowland sites by higher concentration levels of Cd, Cu, Hg and Mn in caps. This could be related to higher concentration levels of the metallic elements in topsoil in the upland region. On other side, A. muscaria from the upland site was poorer in Co and Fe in caps, and in Ca, Co, Fe and Sr in stipes. In spite of the differences in content of the geogenic metallic elements in topsoil between the lowland and upland locations, A. muscaria from both regions was able to regulate uptake and accumulation of Ag, Al, Ba, Ca, K, Mg, Na, Rb and Zn, which were at similar concentration levels in caps but not necessarily in stipes.

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

    Science.gov (United States)

    Fujimori, Takashi; Takigami, Hidetaka; Agusa, Tetsuro; Eguchi, Akifumi; Bekki, Kanae; Yoshida, Aya; Terazono, Atsushi; Ballesteros, Florencio C

    2012-06-30

    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 (phazardous toxic metals (Pb and Cu). There is also a high health risk for children ingesting surface matrices from informal e-waste recycling sites.

  4. Optimization and/or acclimatization of activated sludge process under heavy metals stress.

    Science.gov (United States)

    El Bestawy, Ebtesam; Helmy, Shacker; Hussein, Hany; Fahmy, Mohamed

    2013-04-01

    The present study aimed to overcome the toxicity of the heavy metals load, discharged with the industrial effluents into Alexandria sewerage network, on the activated sludge treatment system through effective acclimation for organic matter and heavy metals removal. Optimization and/or acclimatization of the activated sludge process in the presence of Cu, Cd, Co and Cr contaminating mixed domestic-industrial wastewater was investigated. Acclimatization process was performed through abrupt and stepwise addition of tested metals using sequencing batch reactors treatment approach and evaluated as microbial oxygen uptake rate (OUR), dehydrogenase activity (DHA), organic matter (COD) and heavy metals removal. Abrupt addition of metals adversely affected sludge bioactivity leading to decline in the removal efficiency of the targeted contaminants and loss of floc structure. Metals IC50 confirmed that copper possessed the highest toxicity towards the OUR, DHA activity and COD removal with orders Cu > Cd > Cr > Co; Cu > Cd > Co = Cr and Cu > Cd > Cr > Co, respectively. The highest metal removal was recorded for Cd followed by Co, Cu and finally Cr, most of which was retained in the dissolved influent. However, controlled stepwise application of the tested metals exhibited high sensitivity of DHA and OUR activities only at the highest metal concentrations although enhanced at the lowest concentrations while COD removal was not significantly affected. In conclusion, this approach resulted in adaptation of the system where sludge microbes acquired and developed natural resistance to such metals leading to remarkable enhancement of both organic matter and heavy metals removal.

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

    Science.gov (United States)

    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.

  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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Indian Academy of Sciences (India)

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

    Science.gov (United States)

    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.

  9. Evaluation of heavy metal concentrations of edible wild-grown mushrooms from China.

    Science.gov (United States)

    Wang, Xuemei; Liu, Honggao; Zhang, Ji; Li, Tao; Wang, Yuanzhong

    2017-03-04

    The heavy metal contents (Co, Cu, Fe, Mn, Ni, and Zn) of eight species of wild edible mushrooms from China were determined. The analyses were performed using inductively coupled plasma atomic emission spectrophotometry after microwave digestion. The contents of Co, Cu, Fe, Mn, Ni, and Zn in caps of mushroom samples were 0.7-7.2, 16.2-70.4, 371-1315, 12.5-29.8, 7.1-58.5, and 77.8-187.4 mg kg(-1) dry matter (dm), respectively, while considerable differences were found to be 1.8-25.9, 9.8-36.3, 288-6762, 13.3-103.9, 5.9-78.7, and 38.7-118 mg kg(-1) dm for stipes. The results indicated that higher levels of Co, Fe, and Ni were found in the mushrooms samples analyzed. Zinc and manganese levels were similar to previous reports, whereas Cu was lower than literature values. Correlation analysis suggested that significant correlations were found between the minerals determined and the greatest amount of contamination is associated with Co, Mn, Ni, and Fe. The results of this study indicate that heavy metal contents in mushroom species are mainly related to the mineral resources of sampling sites.

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

    Science.gov (United States)

    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 < 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 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

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

    KAUST Repository

    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.

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

    Indian Academy of Sciences (India)

    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.

  13. Metal Contents in Lichens from Nature Reserves Adjacent to Urban Ecosystems

    Science.gov (United States)

    Meysurova, A. F.; Notov, A. A.

    2016-11-01

    The gross and average contents of 18 metals (Al, As, Cd, Ge, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, Pb, Sb, Sn, Ti, V, Zn) were determined by ICP-AES analysis in samples of Hypogymnia physodes collected from regional nature reserves (NR) in the cities of Tver and Konakovo. The average contents of six metals (Zn, Mo, Cr, Ti, Al, Fe) and the gross contents of eight metals (Zn, Mo, Co, Cu, Cr, Ti, Al, Fe) in these cities were higher than the background levels for Tver Region. The contents of other metals did not exceed background levels. The concentrations of most metals were higher in samples from Tver than in those from Konakovo due to the specifics of their economic infrastructures. The Bobachevskaya Grove NR (Tver) had the most pronounced technological metal pollution. Areas with significant fragments of forest communities were less polluted.

  14. Optimization of a microbial fuel cell for wastewater treatment using recycled scrap metals as a cost-effective cathode material.

    Science.gov (United States)

    Lefebvre, Olivier; Tan, Zi; Shen, Yujia; Ng, How Y

    2013-01-01

    Microbial fuel cell (MFC) for wastewater treatment is still hindered by the prohibitive cost of cathode material, especially when platinum is used to catalyze oxygen reduction. In this study, recycled scrap metals could be used efficiently as cathode material in a specially-designed MFC. In terms of raw power, the scrap metals ranked as follows: W/Co > Cu/Ni > Inconel 718 > carpenter alloy; however, in terms of cost and long term stability, Inconel 718 was the preferred choice. Treatment performance--assessed on real and synthetic wastewater--was considerably improved either by filling the anode compartment with carbon granules or by operating the MFC in full-loop mode. The latter option allowed reaching 99.7% acetate removal while generating a maximum power of 36 W m(-3) at an acetate concentration of 2535 mg L(-1). Under these conditions, the energy produced by the system averaged 0.1 kWh m(-3) of wastewater treated.

  15. Impact of tailings from the Kilembe copper mining district on Lake George, Uganda

    Science.gov (United States)

    Owor, Michael; Hartwig, Tina; Muwanga, Andrew; Zachmann, Dieter; Pohl, Walter

    2007-01-01

    The abandoned Kilembe copper mine in western Uganda is a source of contaminants, mobilised from mine tailings into R. Rukoki flowing through a belt of wetlands into Lake George. Water and sediments were investigated on the lakeshore and the lakebed. Metal associations in the sediments reflect the Kilembe sulphide mineralisation. Enrichment of metals was compared between lakebed sediments, both for wet and dry seasons. Total C in a lakebed core shows a general increment, while Cu and Co decrease with depth. The contaminants are predominant (> 65%) in the ≤ 63 μm sediment size range with elevated Cu and Zn (> 28%), while Ni, Pb and Co are low (extraction of Fe for lakeshore sediment samples reveals low Fe mobility. Relatively higher mobility and biological availability is seen for Co, Cu and S. Heavy metal contents in lake waters are not an immediate risk to the aquatic environment.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  17. Synthesis and characterization of BaFe{sub 2}As{sub 2} single crystals grown by in-flux technique

    Energy Technology Data Exchange (ETDEWEB)

    Garitezi, T.M.; Adriano, C.; Rosa, P.F.S.; Bittar, E.M.; Bufaical, L.; Almeida, R.L.; Granado, E.; Pagliuso, P.G., E-mail: thalesmg@ifi.unicamp.br [Universidade Estadual de Campinas (UNICAM), SP (Brazil). Instituto de Fisica Gleb Wataghin; Grant, T; Fisk, Z. [University of California, Irvine, CA (United States); Avila, M.A.; Ribeiro, R.A. [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil). Centro de Ciencias Naturais e Humanas; Kuhns, P.L.; Reyes, A.P.; Urbano, R.R. [National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL (United States)

    2013-08-15

    We report a detailed characterization of BaFe{sub 2}As{sub 2} single crystals grown by a metallic In-flux technique, an alternative to well-established growth routes using FeAs self- or Sn-flux. Electrical resistivity, magnetic susceptibility, nuclear magnetic resonance, and energy dispersive spectroscopy measurements showed no evidence of flux incorporation. More importantly, our results demonstrate that BaFe{sub 2}As{sub 2} single crystals grown by In-flux have extremely high quality. To explore the efficiency of the In-flux growth method, we have also prepared nearly optimally doped superconducting samples of Ba(Fe{sub 1} {sub -x} M {sub x} ){sub 2}As{sub 2} (M = Co, Cu, Ni, and Ru). Among other interesting features, this alternative chemical substitution method has led to enhancement of the maximum T{sub c} for most dopings. (author)

  18. Report of the Defense Science Board Task Force on Simulation, Readiness and Prototyping

    Science.gov (United States)

    1993-01-01

    3 Ll A.- CU m. -0 (A CuCA W3 > 00 Co W,~U " ’. u~ CE~~ .U0 0 E CuQ 0 4)C cu CD - ~ 0 0 40 co C .Cr_ 4)4& 0 0 a- 1 ca..u w.- )Q t u 4ao C u . u...CA ’ o~L C.> 0 O 0 10UO Cu~~ Cuca . - C m CI- -> -0 .u!uOt0U: r Ut, 02C )**** Cis j 0 ~~~C ~ E4 4) CO Cu C0 0 Cu0 0 Cu r m. U) >u C: o, oo - 4) O0

  19. Tutorial on Set-Up and Communications Delays for all UHF SATCOM DAMA Modes of Operation

    Science.gov (United States)

    2007-11-02

    2J 00 ~ - CU CUCA U C zo ca o2 ).caC 0 C *0 - _ C CU :2 U ~ U 4) - - 4)4)le 4) 0CU) U C 4) CAUC - U ~ . 2H = U o2 4) U, ) U, U e n u 2i- 2 2...C - U7 Cu U2.0. - U)Cu U) 0o6 ) Cu 0 fl)) co >Cu-d Cu CuC m2 0. 0u u Cuca C E4 4)CV X U Cu- Cu3 .. Cu CuU -U- z wU w WI- L U_ 0H t= w z <UP_ C) 0t I

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

    Energy Technology Data Exchange (ETDEWEB)

    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)

  1. Synthesis of New Benzimidazole and Benzothiazole Disulfide Metal Complexes as G-quadruplex Binding Ligands.

    Science.gov (United States)

    Saour, Kawkab; Lafta, Dunya

    2016-01-01

    Compounds that can bind and stabilize non-canonical DNA structures are named quadruplex and are of interest in anticancer drug design due to their selective inhibitions of telomerase and consequent effects on cell proliferation. In this study, we report novel Co/Cu [II] complex compounds as G-quadruplex DNA binding ligands. The results from the preliminary assay indicated that the introduction of a positively charged 6-membered tail to the aromatic terminal group of benzimidazole significantly enhanced the binding affinity with the quadruplex and exhibited anti-telomerase activity. These derivatives showed significant selectivities for the telomeric quadruplex over duplex nucleic acids. The stabilization of non-canonical forms estimated with the FRET DNA technology using different sequences, such as F21T, c-kit1 and c-kit2, in cancer cell lines were assessed. Three members of this family showed to be very selective in stabilizing one particular G-quadruplex.

  2. NHC–metal complexes based on benzimidazolium moiety for chemical transformation

    Directory of Open Access Journals (Sweden)

    Prashant Narayan Muskawar

    2016-11-01

    Full Text Available N-heterocyclic carbenes (NHC are now commonly encountered in organometallic and inorganic coordination chemistry because of its environmental friendly nature as solvent and catalyst, high activity, selectivity and easily recovered materials that were used to replace the traditional volatile organic solvents which generally suffered from environmental problems. Benzimidazole based ionic liquids (BILs offering a new possibility for developing environmentally-friendly basic catalyst with transition metal and non-transition metal (Ag, Au, Ru, Rh, Fe, Co, Cu, Cd and Pd. They are flexible, nonvolatile, noncorrosive and immiscible with many organic solvents. In this review, we wish to present an overview of the preparation and applications in various reactions like alkylation, arylation, etherification, benzoin reaction, aldol condensation and metal mediated catalyst in Suzuki, Suzuki–Miyaura, Heck cross coupling and reduction, also in electrochemical application (electrocatalyst, anion sensor, solar cell, proton conduction, malaria parasite, antimicrobial activity, etc.

  3. Arsenic and trace metals in commercially important bivalves, Anadara granosa and Paphia undulata

    Energy Technology Data Exchange (ETDEWEB)

    Mat, I. (Univ. of Malaya, Kuala Lumpur (Malaysia))

    1994-06-01

    The semi-culture of marine bivalves particularly Anadara granosa is of considerable economic importance in Malaysia. Currently, about 4-5000 ha of mudflats along the west coast are utilized for this purpose. Therefore, contamination of the highly productive mudflats with heavy metals tend to be accumulated in the filter feeding organisms such as bivalve molluscs which often serve as important environmental sinks of heavy metals. Bivalve molluscs, A. granosa and Paphia undulata are commercially important seafoods and popular among the locals in Malaysia. With this point in mind, it is intended to evaluate the concentration levels of arsenic as well as trace metals (Co, Cu, Ni, Cd, Zn, Cr and Pb) in both species derived from retail outlets in the city of Kuala Lumpur. Although this analysis may not indicate the site of capture but may act as a direct check on the contamination of seafoods available to the consumers. 17 refs., 2 tabs.

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

    DEFF Research Database (Denmark)

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

    2016-01-01

    This study is a first attempt to develop globally applicable and spatially differentiated marine Comparative Toxicity Potentials (CTPs) or ecotoxicity characterization factors for metals in coastal seawater for use in Life Cycle Assessment. The toxicity potentials are based exclusively on marine...... varies 3-4 orders of magnitude across LMEs, largely due to different seawater residence time. Therefore the highest toxicity potential for metals was found in the LMEs with the longest seawater residence times. Across metals, the highest CTPs were observed for Cd, Pb and Zn. At the concentration levels...... 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...

  5. Breakdown of the Hume-Rothery Rules in Sub-Nanometer-Sized Ta-Containing Bimetallic Small Clusters

    Science.gov (United States)

    Miyajima, Ken; Fukushima, Naoya; Himeno, Hidenori; Yamada, Akira; Mafuné, Fumitaka

    2009-11-01

    The Hume-Rothery rules are empirical rules to predict the solid solubility of metals. We examined whether the rules hold for sub-nanometer-sized small particles. We prepared bimetallic cluster ions in the gas phase by a double laser ablation technique. Taking advantage of the magic compositions of the bimetallic cluster ions relating to the distinguished stabilities, the coalescence or the segregation of Ta and another element in the sub-nanometer-sized clusters was discussed. It was found that W, Nb, and Mo readily coalesce with Ta, while Ag, Al, Au, Co, Cu, Fe, Hf, Ni, Pt, Ti, and V are segregated from Ta. On the basis of these results, we concluded that the Hume-Rothery rules do not hold for sub-nanometer-sized particles.

  6. Synthesis, characterization and conductivity studies of ZnFe{sub 2}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Narsimulu, D.; Satyanarayana, N., E-mail: nallanis2011@gmail.com [Department of Physics, Pondicherry University, Pondicherry 605 014 (India); Venkateswarlu, M. [R& D, Amara Raja batteries, Thirupathi 517 501 (India)

    2015-06-24

    Transition metal ferrites with general formula AB{sub 2}O{sub 4} (A=Co, Cu, Mn, Zn, B=Fe{sup +3}) could be used as an anode materials in lithium ion battery (LIB), because, lithium ion batteries fabricated using ferrite materials show the high capacity than commonly used graphite. The ZnFe{sub 2}O{sub 4} with cubic spinel structured material was prepared by acrylamide assisted citrate combustion process. Phase, structural coordination and thermal behavior of the prepared ZnFe{sub 2}O{sub 4} were confirmed by powder X-ray diffraction, FTIR spectra and TG/DTA thermogram respectively. Morphology and specific surface area of the ZnFe{sub 2}O{sub 4} were identified by SEM and BET surface analyzer respectively and its conductivity studies were made through impedance spectroscopy.

  7. New intermetallic compounds with the ErCuCd{sub 2} type of structure

    Energy Technology Data Exchange (ETDEWEB)

    Zelinska, O.Ya.; Solokha, P.G.; Pavlyuk, V.V

    2004-03-24

    The crystal structure of new RTZn{sub 2} intermetallic compounds (R=La, Ce, Tb; T=Co, Cu) was determined. The X-ray diffraction data showed that these compounds are isostructural to the new ternary compound ErCuCd{sub 2}, which was found to crystallize with a superstructure of the ErCd{sub 3} structure type (space group Cmcm, Pearson code oS16, a=0.7097(1) nm, b=1.0659(3) nm, c=0.4471(1) nm, V=0.3382(2) nm{sup 3}, Z=4). The obtained reliability factors are R{sub F}=0.0240 and R{sub w}=0.1127 for 235 unique reflections (vertical barF{sub 0} vertical bar>4.00{sigma}|F{sub 0}|)

  8. Polyelemental nanoparticle libraries

    Science.gov (United States)

    Chen, Peng-Cheng; Liu, Xiaolong; Hedrick, James L.; Xie, Zhuang; Wang, Shunzhi; Lin, Qing-Yuan; Hersam, Mark C.; Dravid, Vinayak P.; Mirkin, Chad A.

    2016-06-01

    Multimetallic nanoparticles are useful in many fields, yet there are no effective strategies for synthesizing libraries of such structures, in which architectures can be explored in a systematic and site-specific manner. The absence of these capabilities precludes the possibility of comprehensively exploring such systems. We present systematic studies of individual polyelemental particle systems, in which composition and size can be independently controlled and structure formation (alloy versus phase-separated state) can be understood. We made libraries consisting of every combination of five metallic elements (Au, Ag, Co, Cu, and Ni) through polymer nanoreactor-mediated synthesis. Important insight into the factors that lead to alloy formation and phase segregation at the nanoscale were obtained, and routes to libraries of nanostructures that cannot be made by conventional methods were developed.

  9. Synthesis, photophysical properties of novel fluorescent metal complexes from 3-(1,3-benzoxazol-2-ylnaphthalen-2-ol, and their antimicrobial activities

    Directory of Open Access Journals (Sweden)

    Vinod D. Gupta

    2012-01-01

    Full Text Available A series of novel metal complexes containing metal atoms such as Zn, Co, Cu, Cd, Ni, Mg and Sn have been synthesized from 3-(1,3-benzoxazol-2-ylnaphthalen-2-ol. The synthesized ligand was well characterized by IR, 1H-NMR and mass spectrometry. The electrochemical properties were studied by cyclic voltammetric analysis. The synthesized complexes are fluorescent and absorb in the range of 317 to 323 nm while emit in the range of 371 to 416 nm with good quantum yield. All metal complexes show significant in vitro antibacterial activity against E. coli and S. aureus strains and in vitro antifungal activity against C. albicans and A. niger strains by using serial dilution method. The antibacterial activities were expressed as the minimum inhibitory concentration (MIC in μg/mL.

  10. In-situ assessment of metal contamination via portable X-ray fluorescence spectroscopy: Zlatna, Romania.

    Science.gov (United States)

    Weindorf, David C; Paulette, Laura; Man, Titus

    2013-11-01

    Zlatna, Romania is the site of longtime mining/smelting operations which have resulted in widespread metal pollution of the entire area. Previous studies have documented the contamination using traditional methods involving soil sample collection, digestion, and quantification via inductively coupled plasma atomic emission spectroscopy or atomic absorption. However, field portable X-ray fluorescence spectroscopy (PXRF) can accurately quantify contamination in-situ, in seconds. A PXRF spectrometer was used to scan 69 soil samples in Zlatna across multiple land use types. Each site was georeferenced with data inputted into a geographic information system for high resolution spatial interpolations. These models were laid over contemporary aerial imagery to evaluate the extent of pollution on an individual elemental basis. Pb, As, Co, Cu, and Cd exceeded governmental action limits in >50% of the sites scanned. The use of georeferenced PXRF data offers a powerful new tool for in-situ assessment of contaminated soils.

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

    Science.gov (United States)

    Dang, Duc Huy; Lenoble, Véronique; Durrieu, Gaël; Omanović, Dario; Mullot, Jean-Ulrich; Mounier, Stéphane; Garnier, Cédric

    2015-03-15

    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.

  12. Chemical shift and spin-lattice relaxation time for two crystallographically inequivalent 133Cs sites in Cs2BBr4 (B=57Co, 63Cu, and 65Zn) using magic-angle spinning nuclear magnetic resonance

    Science.gov (United States)

    Lim, Ae Ran; Kim, Sun Ha

    2017-05-01

    The structural geometry around the 133Cs nuclei in Cs2BBr4 (B = 57Co, 63Cu, and 65Zn) was investigated by examining the chemical shifts and spin-lattice relaxation times in a rotating frame. Two crystallographically inequivalent Cs(1) and Cs(2) sites were differentiated. The spin-lattice relaxation times T1ρ of 133Cs nuclei in three crystals were measured to obtain detailed information about their structural dynamics. Cs(1) surrounded by eleven bromide ions was found to have a longer relaxation time than Cs(2) surrounded by nine bromide ions. The nuclear magnetic resonance (NMR) results were compared to previously reported results for Cs2BCl4. The halogen species in Cs2BX4 (X = Br, Cl) was not found to influence the relaxation time, whereas the B metal ion (B = Co, Cu, and Zn) was found to alter the relaxation time mechanism.

  13. The Formation of Carbonate Minerals and the Mobility of Heavy Metals during Water-CO2-Mafic Rock Interactions

    DEFF Research Database (Denmark)

    Olsson, Jonas

    the basaltic host rock and liberates cations. Ideally, the cations react with the dissolved CO2 and form long time stable carbonate minerals. However, dissolution of the basaltic rock can lead to mobility of toxic metals, which is a potential threat to groundwater supplies and surface waters. Besides carbonate...... with the process of carbonation, and (2) they can form a passivating layer, which inhibit dissolution of the basaltic material and slow down the carbonation process. The purpose of this thesis was to identify formation products, relevant to CarbFix, and assess their ability to immobilize toxic metals released from...... are consistent with values of controlled laboratory experiments from the literature for Ba, Cd, Co, Cu, Mg, Mn, Na, Ni, Sr and Zn. The calcium carbonates also scavenge other elements, including rare earth elements (REE) and the toxic metals As and Pb. This and the next study can be considered natural analogues...

  14. Bioaccumulation of trace metals in the submarine hydrothermal vent crab Xenograpsus testudinatus off Kueishan Island, Taiwan.

    Science.gov (United States)

    Peng, Shao-Hung; Hung, Jia-Jang; Hwang, Jiang-Shiou

    2011-01-01

    The concentrations of ten trace metals were determined in the gills, muscles, hepatopancreas, and exoskeleton tissues of Xenograpsus testudinatus that lives around shallow and acidic hydrothermal vents off Kueishan Island, northeastern Taiwan. The analytical results demonstrate that the metal concentrations vary significantly with the type of crab tissue. The concentrations of Al, Cd, Co, Cu, Fe, Ni, and Zn are highest in the gills, whereas the concentration of Mn is highest in the exoskeleton. Cr and Pb concentrations are similar across the different tissues. The enhanced accumulation of most metals in the gills suggests the metal accumulation via the respiration pathway rather than the uptake of food. The results also reveal that the distribution patterns of metals in tissues are similar in the hepatopancreas and muscles, but very different in both the gills and the exoskeleton, perhaps because of the different pathways of metal utilization in the different crab tissues. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. The effect of protonation on the spectra and stabilities of alkoxyl substituted phthalocyaninatometals

    Science.gov (United States)

    Lin, Mei-Jin; Fang, Xin; Xu, Meng-Bo; Wang, Jun-Dong

    2008-12-01

    The protonation abilities of phthalocyaninatometals (MPcs) increase but their stabilities reduce by the introduction of alkoxyl substituents at α position. In the toluene, the order of mono-protonation rate for the tetra-α-(2, 2, 4-trimethyl-3-pentoxy)phthalocyaninatometals sorts with the center metals is Zn > Co > Cu > Ni > Fe, which is opposite to the order of their wavelength difference between the Q bands and X bands. However, their mono-protonated species can be decomposed easily at the rate order FePc > CoPc > CuPc > NiPc > ZnPc, analogous to their decomposition abilities in the benzoylperoxide (BPO) oxidation. In addition, it is interesting that a more remarkable decomposition is found when partial CuPc was mono-protonated.

  16. The Influence of Copper Condensates Alloying with Co, Mo, Ta Transition Metals on the Structure and the Hall-Petch Dependence

    Directory of Open Access Journals (Sweden)

    M.A. Glushchenko

    2016-10-01

    Full Text Available The structure and mechanical properties of two-component copper based Cu-Co, Cu-Mo, Cu-Ta is investigated. It is shown that cobalt, molybdenum and tantalum disperse the grain structure of the copper matrix to submicron and nanometer dimension, form a supersaturated solid solution in the copper fcc lattice and heterophase structure. Reducing of the grain size of condensates is explained by the formation of adsorption layers of atoms of alloying elements on the surface of the copper matrix metal growing grains. The Hall-Petch dependences for the the yield strength are built. The dependences for Cu-Mo and Cu-Ta condensates have greater slope than a similar function for the single component copper. The observed effect is explained by the influence of monolayer grain boundary segregation of molybdenum and tantalum atoms and multilayer segregation of Co atoms.

  17. [Determination of 16 elements in the different pine pollen by TXRF].

    Science.gov (United States)

    Chen, Wei; Han, Xiao-feng; Lü, Jian-gang; Liu, Wei-wei; Tian, Yu-hong; Wu, Xu-ran

    2012-08-01

    After microwave digestion, 16 elements in pine pollen were simultaneously determined by TXRF. The results show that all the 16 elements were found in all pine pollens. There was a significant difference in the average content of the element such as Ca, Ti, Mn, Zn and Rb between different groups of pine pollen (P difference in the average content of the element such as K, V, Fe, Co, Cu and Sr between them (P difference in the average content of the element such as Cr, Ni, As, Pb and Se between them. The results also show that pine pollen has the spectral characteristics of warm property or cold property drug. They were closely related to the tree species and the growth environment or the growth area.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Yu. P.; Zotov, A. V. [School of Natural Science, Far Eastern Federal University, 690950 Vladivostok (Russian Federation); Institute of Automation and Control Processes, 690041 Vladivostok (Russian Federation); Ilin, A. I.; Davydenko, A. V. [School of Natural Science, Far Eastern Federal University, 690950 Vladivostok (Russian Federation)

    2011-10-15

    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.

  19. Oral intake of cadmium, cobalt, copper, iron, lead, nickel, manganese and zinc in the university student's diet.

    Science.gov (United States)

    Barberá, R; Farré, R; Mesado, D

    1993-01-01

    A duplicate diet meal study was carried out with a group of university students living in a hostel, in order to estimate the intake of Zn, Cd, Co, Cu, Fe, Mn, Ni and Pb. Zn, Cu, Fe, Mn and Ni were determined by flame atomic absorption spectrophotometry and Cd, Co and Pb by graphite furnace atomic absorption spectrophotometry after a nitric acid wet digestion procedure. The estimated intake values from the contents of breakfast, lunch, dinner and drinks were compared with the values of the Provisional Tolerable Daily Intake (PTDI) in the case of Cd and Pb, Recommended Dietary Allowances (RDA) of Co, Fe and Zn and Estimated Safe and Adequate Dietetic Daily Intake (ESADDI) of Cu and Mn. Neither excessive intake of Pb and Cd nor deficiencies in Zn, Co, Fe, Mn or Ni were observed, but Cu intake was lower than the ESADDI.

  20. Cationic schiff base amphiphiles and their metal complexes: Surface and biocidal activities against bacteria and fungi.

    Science.gov (United States)

    Negm, N A; Zaki, M F; Salem, M A I

    2010-05-01

    A series of cationic surfactants containing schiff base groups was synthesized by condensation of four fatty amines namely: dodecyl, tetradecyl, hexadecyl and octadecyl amine and 4-diethyl aminobenzaldehyde (1-4), as well as their metal complexes with divalent transition metal ions including Co, Cu and Mn (5-16). The surface activities of the synthesized surfactants were influenced by their chemical structures and the type of the transition metals. The biological activity measurements of the parent cationic schiff bases showed high efficacy against Gram positive and Gram negative bacterial strains and fungi. While on complexation, the biocidal activity was increased remarkably. The biocidal activity of the tested compounds against sulfur reducing bacteria showed promising results in the field of biocide applications.

  1. Long-chain terminal alcohols through catalytic CO hydrogenation.

    Science.gov (United States)

    Xiang, Yizhi; Chitry, Véronique; Liddicoat, Peter; Felfer, Peter; Cairney, Julie; Ringer, Simon; Kruse, Norbert

    2013-05-15

    We show that long-chain 1-alcohols can be produced with high selectivities using heterogeneous CO hydrogenation catalysis. This breakthrough is achieved through the targeted design of "CoCuMn" nanosized core-shell particles using co-precipitation of metal salts into oxalate precursors and subsequent thermal decomposition. Using stoichiometric CO/H2 feeds, the selectivities to 1-alcohols or combined 1-alcohols/1-alkenes are usually higher than 60% and occasionally up to 95%. The Anderson-Schulz-Flory chain-lengthening probabilities for these products are higher than 0.6, but usually below 0.9 so as to optimize the C8-C14 slate as feedstock for plasticizers, lubricants, or detergents.

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

    Science.gov (United States)

    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.

  3. Rations of Closely Related Elements in Soil and Their Inplications

    Institute of Scientific and Technical Information of China (English)

    XINGGUANG-XI; HOUWEN-HUA; 等

    1991-01-01

    This paper has investigated the ratios of closely related elements such as Mn,Cr,V,Ni,Co,Cu,Pb,Cd,Ba,Sr,La and Ce in the major soils of China,and the factors affecting them,and explored their use as indicators in soil formation,material transport and environmental pollution.Results show that the effect of soil-forming processes on the ratios of closely related elements varied with different elements,and became greater in the sequence of Ce/La grassland soils>desert soils and increasing gradually from the semi-arid subhumid zone soils>the temperate zone neutral soils>the north subtropic zone soils>tropical and subtropical acid soils.

  4. Effects of Annealing Temperature on Co30Cu70 Mechanical Alloys

    Directory of Open Access Journals (Sweden)

    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.

  5. Development of a polarized neutron beam line at Algerian research reactors using McStas software

    Science.gov (United States)

    Makhloufi, M.; Salah, H.

    2017-02-01

    Unpolarized instrumentation has long been studied and designed using McStas simulation tool. But, only recently new models were developed for McStas to simulate polarized neutron scattering instruments. In the present contribution, we used McStas software to design a polarized neutron beam line, taking advantage of the available spectrometers reflectometer and diffractometer in Algeria. Both thermal and cold neutron was considered. The polarization was made by two types of supermirrors polarizers FeSi and CoCu provided by the HZB institute. For sake of performance and comparison, the polarizers were characterized and their characteristics reproduced. The simulated instruments are reported. Flipper and electromagnets for guide field are developed. Further developments including analyzers and upgrading of the existing spectrometers are underway.

  6. Metal concentration in urban park soils of Sao Paulo 2. Buenos AiresPark; Concentracao de metais em solos de parques urbanos em Sao Paulo. 2. Parque Buenos Aires

    Energy Technology Data Exchange (ETDEWEB)

    Gumiero, Felipe C.; Figueiredo, Ana Maria G.; Camargo, Sonia P.; Pavese, Arthur [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil)], E-mail: anamaria@ipen.br, E-mail: felipegumiero@gmail.com; Sigolo, Joel B. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias], E-mail: jbsigolo@usp.br; Enzweiler, Jacinta [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Inst. de Geociencias], E-mail: jacinta@ige.unicamp.br; Milian, Felix Mas [Universidade Estadual de Santa Cruz (UESC), Ilheus, BA (Brazil)], E-mail: felixmasmilian@yahoo.com.br

    2007-07-01

    As part of a project which aims metal concentration assessment in urban park soils of Sao Paulo, in the present paper the concentration of the elements As, Ba, Cr, Co, Cu, Pb, Sb and Zn were determined in surface soil samples (0-5 cm and 0-20 cm) from Buenos Aires park of Sao Paulo. This park is located in central region of the city, and is surrounded by avenues and streets, with different traffic volumes. Instrumental Neutron Activation Analysis (INAA) and X-ray Fluorescence (FRX) were used for metal analysis. Preliminary results showed concentration levels of the analyzed elements higher than the values considered as reference values for soils in Sao Paulo, according to the Environmental Protection Agency of the State of Sao Paulo (CETESB). These results suggest that these elements have anthropogenic origin and indicate a potential risk for soil quality. (author)

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

    Science.gov (United States)

    Bastami, Kazem Darvish; Neyestani, Mahmoud Reza; Shemirani, Farzaneh; Soltani, Farzaneh; Haghparast, Sarah; Akbari, Atefeh

    2015-03-15

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  9. Formation of Device Structures Spin-valve Type Based on Co and Cu

    Directory of Open Access Journals (Sweden)

    I.V. Cheshko

    2016-10-01

    Full Text Available The study results of structural-phase state and magnetoresistive properties of spin-valve type nano-film based on Co and Cu are shown in this work. It is found that in these systems during the preparation and annealing at temperatures Tann  700 and 900 K solid solutions of Co atoms in Cu matrix are formed. Was shown that the spin-valve type film system Co (5/Cu(x/Co(20/S expedient modified using multilayers [Co/Cu]n instead one of the magnetic Co layer. This modification increases the magnetoresistance values up to 0,3 ÷ 0,5 %, increases the switching speed from one magnetic state to another and thermal stability of nanosystems to temperature 700 K. Although magnetic sensitivity decreases to a value SB  (0,1 ÷ 0 2  10 – 2 % / mT.

  10. First-principles determination of magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Wu Ruqian; Yang Zongxian; Hong Jisang [Department of Physics, University of California, Irvine, CA (United States)

    2003-02-12

    First-principles density functional theory calculations have achieved great success in the exciting field of low-dimension magnetism, in explaining new phenomena observed in experiments as well as in predicting novel properties and materials. As known, spin-orbit coupling (SOC) plays an extremely important role in various magnetic properties such as magnetic anisotropy, magnetostriction, magneto-optical effects and spin-dynamics. Using the full potential linearized augmented plane wave approach, we have carried out extensive investigations for the effects of SOC in various materials. Results of selected examples, such as structure and magnetic properties of Ni/Cu(001), magnetism and magnetic anisotropy in magnetic Co/Cu(001) thin films, wires and clusters, magnetostriction in FeGa alloys and magneto-optical effects in Fe/Cr superlattices, are discussed.

  11. Improving metallomics information related to transgenic and non-transgenic soybean seeds using 2D-HPLC-ICP-MS and ESI-MS/MS.

    Science.gov (United States)

    Mataveli, Lidiane Raquel Verola; Fioramonte, Mariana; Gozzo, Fabio César; Arruda, Marco Aurélio Zezzi

    2012-04-01

    This work reports the use of 2D-HPLC-ICP-MS to enlarge metallomics information when considering soybean seeds. Separations using size exclusion chromatography (SEC) allowed the identification of three metal fractions: the first corresponding to molecular weights from 38.1 to 181.1 kDa, the second from 8.2 to 17.2 kDa and the third from 0.4 to 3.8 kDa. In a second dimension, using anion exchange chromatography (AEX), three sub-fractions containing Fe, Mg and Mn, one containing Cu, and three containing Co, Cu, Mg, Mn and Zn were obtained. After these separations, 33 proteins were identified using the ESI-MS/MS technique, and divided into four functional categories: plant growth/cell division, protein destination and storage, metabolism and unclassified proteins. Among the identified proteins, proteins previously related to metals were found.

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

    CERN Document Server

    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.

  13. Electron-hole pair contributions to scattering, sticking, and surface diffusion: CO on Cu(100)

    Energy Technology Data Exchange (ETDEWEB)

    Kindt, J.T.; Tully, J.C. [Department of Chemistry, Yale University, New Haven, Connecticut 06511 (United States); Head-Gordon, M. [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Gomez, M.A. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    1998-09-01

    To assess the importance of coupling to electron-hole pair (ehp) excitations for molecular sticking, scattering, and diffusion dynamics at metal surfaces, simulations of the CO/Cu(100) system were performed using the {open_quotes}molecular dynamics with electronic frictions{close_quotes} method. Over a range of incident translational energies, energy losses to ehp excitations produce a moderate increase in sticking probability and account for 5{percent}{endash}10{percent} of initial translational energy in scattered molecules, significantly less than phonon losses. Vibrational excitation and deexcitation of scattered molecules, while remaining a minor pathway for energy flow, is strongly affected by the inclusion of ehp excitations. Finally, although equilibrium diffusion constants are unaffected by the inclusion of coupling to ehp, it causes a significant quenching of transient mobility following adsorption of translationally hot molecules. {copyright} {ital 1998 American Institute of Physics.}

  14. Spin pumping and inverse spin Hall effect in platinum: the essential role of spin-memory loss at metallic interfaces.

    Science.gov (United States)

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

    2014-03-14

    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 ℓsfPt=3.4±0.4  nm and θSHEPt=0.056±0.010 for the respective spin diffusion length and spin Hall angle for Pt. Our data and model emphasize 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 and explains the different scaling lengths for the ferromagnetic damping and the spin Hall effect induced voltage.

  15. A study on the austenite-to-ferrite phase transformation in binary substitutional iron alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wits, J.J.; Kop, T.A.; Leeuwen, Y. van; Seitsma, J.; Zwaag, S. van der [Delft Univ. of Technol. (Netherlands). Lab. of Mater. Sci.

    2000-05-15

    The massive transformation from austenite to ferrite ({gamma}{yields}{alpha}) in binary substitutional Fe-X alloys, where X represents successively about 1 or 2 at.% of Co, Cu, Mn, Cr or Al, is experimentally investigated by means of dilatometry. The resulting transformation curves have been modelled by an interface-controlled growth model, taking the characteristics of the austenitic microstructure into account. The assumption of an Arrhenian temperature dependence of the interface mobility, defined as the ratio between the interface velocity and the driving force, is found to give a consistent picture of the observations with an activation energy for atoms crossing the interface of 140 kJ mol{sup -1}. The spurious presence of interstitial nitrogen is shown to have a significant effect on the mobility, as large as a factor 8 at concentration levels on the order of 10{sup -4}. (orig.)

  16. Comparative bioaccumulation of trace elements between Nautilus pompilius and Nautilus macromphalus (Cephalopoda: Nautiloidea) from Vanuatu and New Caledonia.

    Science.gov (United States)

    Pernice, Mathieu; Boucher, Julien; Boucher-Rodoni, Renata; Joannot, Pascale; Bustamante, Paco

    2009-02-01

    The concentrations of 16 trace elements were investigated and compared for the first time in the digestive and excreting tissues of two Nautilus species (Cephalopoda: Nautiloidea) from two geologically contrasted areas: (1) N. macromphalus from New Caledonia, a region characterized by its richness in nickel ores and its lack of tectonic activities and (2) N. pompilius from the Vanuatu archipelago showing high volcanic and tectonic activities. In both Nautilus species, results clearly highlighted that the digestive gland played a key role in the bioaccumulation and storage of Ag, Cd, Ce, Co, Cu, Fe, La, Nd, V, and Zn whereas As, Cr, Mn, Ni, Pb, and Se were accumulated in a greater extent in the excreting tissues (i.e. pericardial and renal appendages). Despite contrasting environments, no significant difference (pVanuatu waters by specific environmental processes, such as volcanism or upwelling.

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

    CERN Document Server

    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.

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

    Indian Academy of Sciences (India)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  20. Giant Magnetoresistance Effect of [bcc-Fe(M)/Cu](M=Co,Ni)Multilayers

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    GMR effect of multilayers of bcc-Fe(M)(M=Co, Ni) alloy and Cu layers has been investigated. The maximum MR ratio is found at 1.1 nm Fe(Co) and 1.3~1.4 nm Cu layer thickness in [Fe(Co)/Cu], and at 1.6 nm Fe(Ni) and 1.4 nm Cu layer thickness in [Fe(Ni)/Cu]. Under the optimum annealing condition, the MR ratio increases up to 50% and 38% for Fe(Co) and Fe(Ni) systems, respectively. The origin of the increase of GMR is discussed, taking the progress of preferred orientation of Fe(Co)[100] or Fe(Ni)[100] by annealing into account.

  1. 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

    Energy Technology Data Exchange (ETDEWEB)

    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)

  2. Novel spin glasses by mechanical milling

    Institute of Scientific and Technical Information of China (English)

    周国富; H.Bakker

    1996-01-01

    Novel spin-glass alloys were synthesized by milling intermetallic compounds and also by milling mixtures of crystalline elemental powder in a high-energy ball mill.Spin glass behaviour was found in amorphous Co2Ge,which was amorphised by milling in mechanically disordered crystalline GdAl2 in ball-milled crystalline and amorphous CoZr,and in mechanically alloyed Co-Cu,which formed a supersaturated f.c.c.solid solution.All these materials are binary alloys and tlie concentration of the magnetic element is high,which makes them novel types of spin glasses.It is shown that ball milling may not only lead to structural metallic glasses,but can also generate the magnetic pendant of a structural glass,namely the spin glass.

  3. Elemental characterization of superficial waters contaminated by an abandoned sulfide-mining area, through neutron activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Canha, N.; Freitas, M.C.; Dionisio, I.; Anawar, H.M. [URSN-ITN, Sacavem (Portugal). Technological and Nuclear Inst.; Pacheco, A.M.G. [Technical Univ. of Lisbon (Portugal). CERENA-IST

    2011-07-01

    In this work, superficial waters of two small rivers flowing in the Sao Domingos' abandoned mining area were analyzed in order to infer on soil-water transfer of the elements determined. Instrumental neutron activation analysis was used for elemental concentration assessment. The following elements were found at the mg L{sup -1} level: As, Ba, Co, Cu, Fe, K, Na and Zn. The dry-mass residues varied between 70 mg and 1 g in 20-mL volumes. High enrichment relative to soil was found for most elements. Good statistical associations between Br and Na, between Cr and Sc, and between Ce, Co, Fe, Yb, and Zn, were found, suggesting a similar mechanism of soil-water, elemental transfer. Both the superficial waters' composition and their elemental levels indicate a potential risk of contamination of the underground waters and an actual health risk for the resident populations. (orig.)

  4. Heavy metals in emergent trees and pioneers from tropical forest with special reference to forest fires and local pollution sources in Sarawak, Malaysia.

    Science.gov (United States)

    Breulman, G; Markert, B; Weckert, V; Herpin, U; Yoneda, R; Ogino, K

    2002-02-21

    Leaf samples of tropical trees, i.e. Dryobalanops lanceolata (Kapur paji), Dipterocarpaceae and Macaranga spp. (Mahang), Euphorbiaceae were analyzed for 21 chemical elements. The pioneer Macaranga spp. exhibited higher concentrations for the majority of elements compared to the emergent species of Dryobalanops lanceolata, which was attributed to the higher physiological activity of the fast growing pioneer species compared to emergent trees. Lead showed rather high concentrations in several samples from the Bakam re-forestation site. This is suggested to be caused by emissions through brick manufacturing and related activities in the vicinity. A comparison of Dryobalanops lanceolata samples collected in 1993, 1995 and 1997 in the Lambir Hills National Park revealed that certain heavy metals, i.e. Co, Cu, Mn, Ni, Pb and Ti showed higher values in 1997 compared to the previous years, which could indicate an atmospheric input from the haze caused by the extensive forest fires raging in Borneo and other parts of Southeast Asia.

  5. Stability and leaching of cobalt smelter fly ash

    DEFF Research Database (Denmark)

    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...... 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....

  6. Autoclave decomposition method for metals in soils and sediments.

    Science.gov (United States)

    Navarrete-López, M; Jonathan, M P; Rodríguez-Espinosa, P F; Salgado-Galeana, J A

    2012-04-01

    Leaching of partially leached metals (Fe, Mn, Cd, Co, Cu, Ni, Pb, and Zn) was done using autoclave technique which was modified based on EPA 3051A digestion technique. The autoclave method was developed as an alternative to the regular digestion procedure passed the safety norms for partial extraction of metals in polytetrafluoroethylene (PFA vessel) with a low constant temperature (119.5° ± 1.5°C) and the recovery of elements were also precise. The autoclave method was also validated using two Standard Reference Materials (SRMs: Loam Soil B and Loam Soil D) and the recoveries were equally superior to the traditionally established digestion methods. Application of the autoclave was samples from different natural environments (beach, mangrove, river, and city soil) to reproduce the recovery of elements during subsequent analysis.

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

    Directory of Open Access Journals (Sweden)

    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.

  8. Digital Group Multiplexers (DGM). Volume 2. Section 3.0, 5.0, 7.0, 15.4

    Science.gov (United States)

    1980-02-01

    Protection X X * Automatic Input Power Det,:.or (AC/DC) X X X * Reverse Polarity Protection X X X * Power Supply Efficiency 1. AC Operation - 75% X x...surges through the relay, and prevents inadvertant DC polarity reversal. Figure 3-28 is a schematic of this circuit. A two pole circuit breaker is used...C)) Q) Cq ( aca a co 4-A -c co CU 0$o0 r--1. cq 4 - C~ <Q $4 U <.Le> c-i< mJ~ E > ~~’r C)(I 0.. 0.0o~ E 0 0 0~C Cu - -S S. * 0 0, 0 " 0 C* bDD 7-10

  9. Direct Conversion of Syngas-to-Hydrocarbons over Higher Alcohols Synthesis Catalysts Mixed with HZSM-5

    Energy Technology Data Exchange (ETDEWEB)

    Lebarbier Dagel, Vanessa M.; Dagle, Robert A.; Li, Jinjing; Deshmane, Chinmay A.; Taylor, Charles E.; Bao, Xinhe; Wang, Yong

    2014-09-10

    The synthesis of hydrocarbon fuels directly from synthesis gas (i.e. one step process) was investigated with a catalytic system comprised of HZSM-5 physically mixed with either a methanol synthesis catalyst or a higher alcohols synthesis (HAS) catalyst. The metal sites of the methanol or HAS synthesis catalyst enable the conversion of syngas to alcohols, whereas HZSM-5 provides acid sites required for methanol dehydration, and dimethyl ether-to-hydrocarbons reactions. Catalytic performance for HZSM-5 when mixed with either a 5 wt.% Pd/ZnO/Al2O3 methanol synthesis catalyst or a HAS catalyst was evaluated at 300°C, 70 bars, GHSV=700 h-1 and H2/CO=1 using a HZSM-5: alcohols synthesis catalyst weight ratio of 3:1. The major difference observed between the methanol synthesis and HAS catalyst mixtures was found in the production of durene which is an undesirable byproduct. While durene formation is negligible with any of the HAS catalysts mixed with the HZSM-5 evaluated in this study, it represents almost 50% of the C5+ fraction for the methanol synthesis catalyst (5 wt.% Pd/ZnO/Al2O3 ) mixed with HZSM-5. This presents an advantage for using HAS catalysts over the methanol synthesis catalyst to minimize the durene by-product. The yield toward the desired C5+ hydrocarbons is thus twice higher with selected HAS catalysts as compared to when HZSM-5 is mixed with 5 wt.% Pd/ZnO/Al2O3. Among all the HAS catalysts evaluated in this study, a catalyst with 0.5 wt.% Pd/FeCoCu catalyst was found the most promising due to higher production of C5+ hydrocarbons and low durene formation. The efficiency of the one-step process was thus further evaluated using the HZSM-5: 0.5 wt.% Pd/FeCoCu catalyst mixture under a number of process conditions to maximize liquid hydrocarbons product yield. At 300oC, 70 bars, GHSV = 700 h-1 and HZSM-5: 0.5 wt.% Pd/FeCoCu = 3:1 (wt.), the C5+ fraction represents 48.5% of the hydrocarbons. Unfortunately, it is more difficult to achieve higher selectivity

  10. The Formation of Carbonate Minerals and the Mobility of Heavy Metals during Water-CO2-Mafic Rock Interactions

    DEFF Research Database (Denmark)

    Olsson, Jonas

    are consistent with values of controlled laboratory experiments from the literature for Ba, Cd, Co, Cu, Mg, Mn, Na, Ni, Sr and Zn. The calcium carbonates also scavenge other elements, including rare earth elements (REE) and the toxic metals As and Pb. This and the next study can be considered natural analogues...... minerals, the reaction products are known to be manifold and reflect the complex composition of the basaltic material. Formation of secondary products, such aluminium and iron (hydr)oxides, are considered undesirable, because (1) they consume the cations that could be used to sequester CO2, thus compete...... with the process of carbonation, and (2) they can form a passivating layer, which inhibit dissolution of the basaltic material and slow down the carbonation process. The purpose of this thesis was to identify formation products, relevant to CarbFix, and assess their ability to immobilize toxic metals released from...

  11. STM tip-mediated mass transport on Cu surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Y.S.N. [College of Physical Science and Technology, Shenyang Normal University, Huanghe Street 253, Shenyang 110034 (China); Huang, R.Z., E-mail: renzhonghuang@synu.edu.cn [College of Physical Science and Technology, Shenyang Normal University, Huanghe Street 253, Shenyang 110034 (China); Gao, T.F. [College of Physical Science and Technology, Shenyang Normal University, Huanghe Street 253, Shenyang 110034 (China); Zhang, R.J. [School of Information Science and Engineering, Fudan University, Handan Road 220, Shanghai 200433 (China); Wang, Y.M. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, Shenyang 110016 (China)

    2015-02-01

    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.

  12. Speciation, sources, and risk assessment of heavy metals in suburban vegetable garden soil in Xianyang City, Northwest China

    Science.gov (United States)

    Wang, Lijun; Tao, Wendong; Smardon, Richard C.; Xu, Xue; Lu, Xinwei

    2017-07-01

    Intensive anthropogenic activities can lead to soil heavy metal contamination resulting in potential risks to the environment and to human health. To reveal the concentrations, speciation, sources, pollution level, and ecological risk of heavy metals in vegetable garden soil, a total of 136 soil samples were collected from three vegetable production fields in the suburbs of Xianyang City, Northwest China. These samples were analyzed by inductively coupled plasma- atomic emission spectrometry and atomic fluorescence spectrometry. The results showed that the mean concentrations of Cd, Co, Cu, Mn, Pb, Zn, and Hg in vegetable garden soil were higher than the corresponding soil element background values of Shaanxi Province. The heavy metals studied in vegetable garden soil were primarily found in the residual fraction, averaging from 31.26% (Pb) to 90.23% (Cr). Considering the non-residual fractions, the mobility or potential risk was in the order of Pb (68.74%)>Co (60.54%)>Mn (59.28%) >Cd (53.54%) ≫Ni (23.36%) >Zn (22.73%)>Cu (14.93%)>V (11.81%)>Cr (9.78%). Cr, Mn, Ni, V, and As in the studied soil were related to soilforming parent materials, while Cu, Hg, Zn, Cd, Co, and Pb were associated with the application of plastic films, fertilizers, and pesticides, as well as traffic emissions and industrial fumes. Cr, Ni, V, and As presented low contamination levels, whereas Co, Cu, Mn, Pb, and Zn levels were moderate, and Cd and Hg were high. Ecological risk was low for Co, Cr, Cu, Mn, Pb, Zn, and As, with high risk observed for Cd and Hg. The overall pollution level and ecological risk of these heavy metals were high.

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

    Directory of Open Access Journals (Sweden)

    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.

  14. Concentrations of trace elements in muscle of sturgeons in the Caspian Sea.

    Science.gov (United States)

    Agusa, Tetsuro; Kunito, Takashi; Tanabe, Shinsuke; Pourkazemi, Mohammad; Aubrey, David G

    2004-11-01

    Concentrations of 21 trace elements were determined in muscle of beluga (Huso huso), Persian sturgeon (Acipenser persicus), Russian sturgeon (Acipenser gueldenstaedtii), ship sturgeon (Acipenser nudiventris) and stellate sturgeon (Acipenser stellatus) collected from coastal regions of Azerbaijan, Iran, Kazakhstan and Turkmenistan, surrounding the Caspian Sea during 2000-2001. Concentrations of Mn, Co, Cu, Mo, Sn, Hg, Pb and Bi in the muscle were apparently different among the five species of sturgeons. Especially, beluga showed the highest concentrations of Hg, Pb and Mn in all the five species. In addition, more than half of the individuals of beluga exceeded the guideline level (0.3 microg/g wet wt.) of Hg for food in UK. However, V, Cr, Zn, Ga, Rb, Sr and Ba concentrations were similar among five sturgeons. Growth-dependent increase in Hg in beluga, Cu in Persian sturgeon, and Zn in Russian sturgeon were observed, whereas V, Mn, Co, Cu, Ga, Sr, Mo, Sn, Hg and Bi concentrations in Persian sturgeon, Pb in ship sturgeon, and Cr, Mn, and Rb in stellate sturgeon were negatively correlated with body length. All species of sturgeon in Azerbaijan showed the highest concentration of Sr and the lowest concentration of Rb, while the five sturgeons from Iran showed opposite trends. Concentration of V, which is present in oil, in sturgeons in the Caspian Sea was considerably lower than that of fish from Kuwait, but was comparable to that of Cambodia and the Gulf and Gulf of Oman. To our knowledge, this study provides the first extensive data on multielemental accumulation in sturgeons of the Caspian Sea.

  15. Multi-element analysis of urine using dynamic reaction cell inductively coupled plasma mass spectrometry (ICP-DRC-MS — A practical application

    Directory of Open Access Journals (Sweden)

    Renata Brodzka

    2013-04-01

    Full Text Available Objectives: The method for the determination of As, Al, Cd, Ni, Pb (toxic elements and Cr, Co, Cu, Fe, Mn, Zn (essential elements in human urine by the use of Inductively Coupled Plasma Mass Spectrometry (quadrupole ICP-MS DRCe Elan, Perkin Elmer with the dynamic reaction cell (DRC was developed. Materials and Methods: The method has been applied for multi-element analysis of the urine of 16 non-exposed healthy volunteers and 27 workers employed in a copper smelter. The analysis was conducted after initial 10-fold dilution of the urine samples with 0,1% nitric acid. Rhodium was used as an internal standard. The method validation parameters such as detection limit, sensitivity, precision were described for all elements. Accuracy of the method was checked by the regular use of certified reference materials ClinCheck®-Control Urine (Recipe as well as by participation of the laboratory in the German External Quality Assessment Scheme (G-EQUAS. Results: The detection limits (DL 3s of the applied method were 0.025, 0.007, 0.002, 0.004, 0.004, 0.086, 0.037, 0.009, 0.016, 0.008, 0.064 (μg/l for Al, As, Cd, Cr, Co, Cu, Fe, Mn, Ni, Pb, Zn in urine, respectively. For each element linearity with correlation coefficient of at least 0.999 was determined. Spectral interferences from some of the ions were removed using DRC-e with addition of alternative gas: methane for cobalt, copper, cadmium, chromium, iron, manganese, nickel and rhodium, and oxygen for arsenic. Conclusions: The developed method allows to determine simultaneously eleven elements in the urine with low detection limits, high sensitivity and good accuracy. Moreover, the method is appropriate for the assessment of both environmental and occupational exposure.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. Thermodynamic properties and phase equilibria of selected Heusler compounds

    Science.gov (United States)

    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.

  18. Analysis of indirect exchange interaction of conductivity electron on a magnetic interlayer exchange coupling%磁性夹层交换耦合中传导电子的间接交换作用分析

    Institute of Scientific and Technical Information of China (English)

    郑勇林; 葛泽玲; 杨维; 程浩; 郭红力; 包秀丽

    2012-01-01

    It is studies the oscillatory exchange coupling and its dependence on magnetic-layer thickness from quantum electronics theory and first principles for (100) and (110) oriented Co/Cu/Co sandwiches. The results of the calculations show that the change of the magnetic layer thickness can lead to a strong redistribution of weight between the different characteristic oscillations in the coupling energy, while the corresponding periods are unchanged. The electron structure will changing while thickness of the magnetic layer change. For thicker layers we find exchange coupling only small oscillations around an asymptotic value. The calculated exchange coupling energies is not only the periods but also the amplitudes and the phases of the oscillations are correctly accordance with existing experiment also the theories of Barnas and Bruno.%应用量子干涉理论和第一性原理研究了Co/Cu/Co夹层结构在[100]和[110]取向上振荡交换耦合及对磁层厚度的依赖,对夹层交换耦合振荡的计算结果表明:当相应的周期不变时,磁性层(Co)厚度的变化将导致在不同的RKKY振荡特征中势的再分配,磁层厚度发生变化时,磁性层上电子结构也发生变化,当磁性层较厚时,交换耦合仅在某一渐近值附近有一小的振荡.耦合振荡的周期、振幅和相位的测量与实验相一致,也与Barnas和Bruno理论吻合.

  19. The essential role of spin-memory loss at 3d/5d metallic interfaces in spin pumping

    Science.gov (United States)

    Jaffres, Henri

    2015-03-01

    I will present a review of experiments and theory of spin-pumping in Co/(Cu)/Pt 3d/5d metallic systems in the ferromagnetic resonance (FMR) regime of spin injection. By combining i) FMR analyses of the resonance linewidth of the Co spectra in contact with the Pt (or Cu/Pt) reservoir and ii) detection of the inverse spin-hall effect signal vs. Pt thickness, we were able to evidence two different lengthscales for the spin-current profile generated or absorbed at the interfaces. The first lenghscale, extracted from FMR analyses and of the order of 2 nm, represents a typical interface length characteristic of a spin memory loss at the Co/Pt and Co/Cu/Pt interfaces. This represent a typical region of spin-current dissipation by which almost 60-70 % of the total current generated is lost before conversion in bulk Pt. The second lengthscale, roughly equal to 3.4 nm, like determined by Inverse Spin Hall Effect (ISHE) transverse voltage measurement, is more characteristic of the spin-diffusion length of the bulk Pt that governs a part of the spin-to-charge conversion efficiency by ISHE. After careful analyses, we determined a spin-hall angle of 5.6 % for Pt and an intrinsic spin hall conductivity of 3200 (Ohm.cm)-1 for our corresponding Pt resistivity. In the end, I will focus on the physical description of our experiments within a derived Valet-Fert model describing the spin transport/relaxation in a diffusive approach and using relevant boundary conditions for spin-pumping (constant spin accumulation in the ferromagnet). The origin of the spin-memory loss and spin-current discontinuity, also proposed in a very recent work, will be explained in terms of atomic intermixing at interfaces or possible Rashba-split states at Co/Pt interfaces.

  20. Concentrations of trace element in human dentin by sex and age.

    Science.gov (United States)

    Kumagai, Akiko; Fujita, Yuji; Endo, Shigeatsu; Itai, Kazuyoshi

    2012-06-10

    Teeth are recently drawing attention for their potential as biological modeling investigation samples due to their ability to be collected and their slow substance metabolism. There is no active metabolism of elements after the completion of dentin. Dentin is surrounded by enamel and cementum, and is not affected by the oral environment. Therefore, the amount of trace elements in dentin may change with age, and this is considered to be a reliable biological load index. The objectives in this study are to demonstrate concentrations of elements in the dentin of healthy Japanese subjects by sex and age, and to reveal the relationship between element levels and age. 121 healthy teeth samples were extracted due to periodontal disease or orthodontic treatment. Each tooth was sliced from the crown to the root apex into 0.5-1mm thickness, then enamel, cementum, and the pulp were removed; the dentins were used as samples. The concentration of 10 trace elements (B, Mn, Co, Cu, Zn, Rb, Sr, Mo, Cd, and Pb) in the dentin was measured using inductively coupled plasma mass spectrometer (ICP-MS). The differences Co and Pb in the dentin between men and women were significant (p<0.01). Significant positive correlation was observed between B, Co, Cu, Zn, Sr and Pb concentrations in the dentin and age (p<0.001). The results of the present study suggest that human dentin is an appropriate substance for relativity with sex and age at further future research. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  1. 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.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Sequential-injection on-line preconcentration using chitosan resin functionalized with 2-amino-5-hydroxy benzoic acid for the determination of trace elements in environmental water samples by inductively coupled plasma-atomic emission spectrometry.

    Science.gov (United States)

    Sabarudin, Akhmad; Lenghor, Narong; Oshima, Mitsuko; Hakim, Lukman; Takayanagi, Toshio; Gao, Yun-Hua; Motomizu, Shoji

    2007-07-31

    A new chelating resin using chitosan as a base material was synthesized. Functional moiety of 2-amino-5-hydroxy benzoic acid (AHBA) was chemically bonded to the amino group of cross-linked chitosan (CCTS) through the arm of chloromethyloxirane (CCTS-AHBA resin). Several elements, such as Ag, Be, Cd, Co, Cu, Ni, Pb, U, V, and rare earth elements (REEs), could be adsorbed on the resin. To use the resin for on-line pretreatment, the resin was packed in a mini-column and installed into a sequential-injection/automated pretreatment system (Auto-Pret System) coupled with inductively coupled plasma-atomic emission spectrometry (ICP-AES). The sequential-injection/automated pretreatment system was a laboratory-assembled, and the program was written using Visual Basic software. This system can provide easy operation procedures, less reagent consumption, as well as less waste production. Experimental variables considered as effective factors in the improvement sensitivity, such as an eluent concentration, a sample and an eluent flow rate, pH of samples, and air-sandwiched eluent were carefully optimized. The proposed system provides excellent on-line collection efficiency, as well as high concentration factors of analytes in water samples, which results in highly sensitive detection of ultra-trace and trace analysis. Under the optimal conditions, the detection limits of 24 elements examined are in the range from ppt to sub-ppb levels. The proposed method was validated by using the standard reference material of a river water, SLRS-4, and the applicability was further demonstrated to the on-line collection/concentration of trace elements, such as Ag, Be, Cd, Co, Cu, Ni, Pb, U, V, and REEs in water samples.

  4. Enhancement of output power in spin torque nano-oscillator using heterogeneous layer

    Energy Technology Data Exchange (ETDEWEB)

    Bhoomeeswaran, H.; Sabareesan, P., E-mail: sendtosabari@gmail.com [Centre for Nonlinear Science and Engineering, School of Electrical and Electronics Engineering, SASTRA University, Thanjavur - 613 401 (India)

    2016-05-23

    The article mainly focuses on the enrichment of the output power obtained from Spin torque nano-oscillator by introducing the heterogeneous structure in multilayer nanopillar device. Here we devised two homogeneous and two heterogeneous devices having NiFe and Co materials. The dynamics of the devices are governed by a famous Landu- Lifshitz -Gilbert-Solencskwei (LLGS) equation which can be solved numerically using embedded RK-4 procedure. The current density and the external magnetic field for four devices are taken as 5×l0{sup 11}A/m{sup 2} and 6×l0{sup −3} A/m respectively. The applied dc current is converted into spin polarized dc current while it passes through pinned layer. The generated spin polarized dc currents produces spin transfer torque with the free layer magnetization via spacer. Thus the magnetization of the free layer gets a sustained oscillation. The results obtained from the heterogeneous STNOs are really fascinating. The frequency of the NiFe/ Cu/NiFe and Co/Cu/NiFe devices have the same frequency but there is a tremendous change in the output power which is exactly twice that the NiFe/Cu/NiFe device. The similar behaviour is also obtained from Co/Cu/Co and NiFe/Cu/Co devices. The line width and the Q-factor of the output microwave signal are also computed. Among the four devices, the NiFe/Cu/Co heterogeneous device has low linewidth (408 MHz) and high Q-factor (4.77).

  5. Early High-Fat Feeding Induces Alteration of Trace Element Content in Tissues of Juvenile Male Wistar Rats.

    Science.gov (United States)

    Tinkov, Alexey A; Gatiatulina, Eugenia R; Popova, Elizaveta V; Polyakova, Valentina S; Skalnaya, Anastasia A; Agletdinov, Eduard F; Nikonorov, Alexandr A; Skalny, Anatoly V

    2017-02-01

    The primary objective of the current study was to assess the influence of early high-fat feeding on tissue trace element content in young male Wistar rats. Twenty weanling male Wistar rats were divided into two groups fed standard (STD) or high-fat diet (HFD) containing 10 and 31.6 % of total calories from fat, respectively, for 1 month. Serum lipid spectrum, apolipoproteins, glucose, insulin, adiponectin, and leptin levels were assessed. The level of trace elements was estimated using inductively coupled plasma mass spectrometry. High-fat feeding significantly increased epidydimal (EDAT) and retroperitoneal adipose tissue (RPAT), as well as total adipose tissue mass by 34, 103, and 59 %, respectively. Serum leptin levels in HFD animals were twofold higher than those in the control rats. No significant difference in serum lipid spectrum, apolipoproteins, glucose, adiponectin, and insulin was detected between the groups. HFD significantly altered tissue trace element content. In particular, HFD-fed animals were characterized by significantly lower levels of Cu, I, Mn, Se, and Zn in the liver; Cr, V, Co, Cu, Fe, and I content of EDAT; Co, Cu, I, Cr, V, Fe, and Zn concentration in RPAT samples. At the same time, only serum Cu was significantly depressed in HFD-fed animals as compared to the control ones. Hair Co, Mn, Si, and V levels were significantly increased in comparison to the control values, whereas Se and I content was decreased. HFD feeding induced excessive adiposity and altered tissue trace element content in rats without insulin resistance, adiponectin deficiency, and proatherogenic state. Hypothetically, trace element disbalance may precede obesity-associated metabolic disturbances.

  6. Effect of metal ions on the molecular weight distribution of humic substances derived from municipal compost: ultrafiltration and size exclusion chromatography with spectrophotometric and inductively coupled plasma-MS detection.

    Science.gov (United States)

    Wrobel, Kazimierz; Sadi, Baki B M; Wrobel, Katarzyna; Castillo, Juan R; Caruso, Joseph A

    2003-02-15

    The effect of metal ions (Co, Cu, Ni, Pb, Zn) on the molecular weight distribution of humic substances (HSs) obtained from compost is studied. We believe this is the first of this type of study applied in this way to humic substances. Size exclusion chromatography is coupled with two on-line detection systems (spectrophotometric and ICPMS) to study the binding of metal ions by humic substances leached from compost. ICPMS provided highly specific, sensitive, and multielement analytical information that enabled obtaining direct experimental evidence for the participation of metal ions in molecular size distributions of humic compounds. The compost extract or its high molecular weight fraction (>5,000) was put in contact with EDTA or citrate ions, thereby competing with HSs for binding metals. The experiments were carried out by varying the pH maintained by Tris-HCl or CAPS buffer (pH 8.0 and 10.3) and keeping the ionic strength constant. The elution profile of humic substances using UV/ visible detection was compared with those from ICPMS detection of Co, Cu, Ni, Pb, and Zn in the same chromatographic runs. The results obtained suggested that both bridging between small molecules and complexation/ chelation by individual molecules are involved in metal ion binding to humic substances. The use of ICPMS to study the role of metal ions in aggregation/disassociation of humic substances proposed in this work is promising. Coupling element-specific detection with SEC or other separation systems allows better understanding of the mobility and bioaccessibility of elemental species in the environment and further elucidation of the dissolved humic structure.

  7. Occurrence of metal ions in rice produced in Uruguay

    Directory of Open Access Journals (Sweden)

    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. 

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  9. Interrogating the variation of element masses and distribution patterns in single cells using ICP-MS with a high efficiency cell introduction system.

    Science.gov (United States)

    Wang, Hailong; Wang, Meng; Wang, Bing; Zheng, Lingna; Chen, Hanqing; Chai, Zhifang; Feng, Weiyue

    2017-02-01

    Cellular heterogeneity is an inherent condition of cell populations, which results from stochastic expression of genes, proteins, and metabolites. The heterogeneity of individual cells can dramatically influence cellular decision-making and cell fate. So far, our knowledge about how the variation of endogenous metals and non-metals in individual eukaryotic cells is limited. In this study, ICP-MS equipped with a high efficiency cell introduction system (HECIS) was developed as a method of single-cell ICP-MS (SC-ICP-MS). The method was applied to the single-cell analysis of Mn, Fe, Co, Cu, Zn, P, and S in human cancer cell lines (HeLa and A549) and normal human bronchial epithelial cell line (16HBE). The analysis showed obvious variation of the masses of Cu, Fe, Zn, and P in individual HeLa cells, and variation of Fe, Zn, and P in individual A549 cells. On the basis of the single-cell data, a multimodal distribution of the elements in the cell population was fitted, which showed marked differences among the various cell lines. Importantly, subpopulations of the elements were found in the cell populations, especially in the HeLa cancer cells. This study demonstrates that SC-ICP-MS is able to unravel the extent of variation of endogenous elements in individual cells, which will help to improve our fundamental understanding of cellular biology and reveal novel insights into human biology and medicine. Graphical abstract The variations of masses and distribution patterns of elements Mn, Fe, Co, Cu, Zn, P, and S in single cells were successfully detected by ICP-MS coupled with a high efficiency cell introduction system (HECIS).

  10. Impact of inorganic contaminants on microalgae productivity and bioremediation potential.

    Science.gov (United States)

    Torres, Eric M; Hess, Derek; McNeil, Brian T; Guy, Tessa; Quinn, Jason C

    2017-05-01

    As underdeveloped nations continue to industrialize and world population continues to increase, the need for energy, natural resources, and goods will lead to ever increasing inorganic contaminants, such as heavy metals, in various waste streams that can have damaging effects on plant life, wildlife, and human health. This work is focused on the evaluation of the potential of Nannochloropsis salina to be integrated with contaminated water sources for the concurrent production of a biofuel feedstock while providing an environmental service through bioremediation. Individual contaminants (As, Cd, Cr, Co, Cu, Pb, Ni, Hg, Se, and Zn) at various concentrations ranging from a low concentration (1X) to higher concentrations (10X, and 40X) found in contaminated systems (mine tailings, wastewater treatment plants, produced water) were introduced into growth media. Biological growth experimentation was performed in triplicate at the various contaminant concentrations and at 3 different light intensities. Results show that baseline concentrations of each contaminant slightly decreased biomass growth to between 89% and 99% of the control with the exception of Ni which dramatically reduced growth. Increased contaminant concentrations resulted in progressively lower growth rates for all contaminants tested. Lipid analysis shows most baseline contaminant concentrations slightly decrease or have minimal effects on lipid content at all light levels. Trace contaminant analysis on the biomass showed Cd, Co, Cu, Pb, and Zn were sorbed by the microalgae with minimal contaminants remaining in the growth media illustrating the effectiveness of microalgae to bioremediate these contaminants when levels are sufficiently low to not detrimentally impact productivity. The microalgae biomass was less efficient at sorption of As, Cr, Ni, and Se. Copyright © 2017 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

    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.

  12. Plant growth and development vs. high and low levels of plant-beneficial heavy metal ions

    Directory of Open Access Journals (Sweden)

    Namira Arif

    2016-11-01

    Full Text Available Heavy metals (HMs exists in the environment in both forms as essential and non-essential. These HM ions enter in soil biota from various sources like natural and anthropogenic. Essential HMs such as cobalt (Co, copper (Cu, iron (Fe, manganese (Mn, molybdenum (Mo, nickel (Ni, and zinc (Zn plays a beneficial role in plant growth and development. At optimum level these beneficial elements improves the plant’s nutritional level and also several mechanisms essential for the normal growth and better yield of plants. The range of their optimality for land plants is varied. Plant uptake heavy metals as a soluble component or solubilized them by root exudates. While their presence in excess become toxic for plants that switches the plant’s ability to uptake and accumulate other nonessential elements. The increased amount of HMs within the plant tissue displays direct and indirect toxic impacts. Such direct effects are the generation of oxidative stress which further aggravates inhibition of cytoplasmic enzymes and damage to cell structures. Although, indirect possession is the substitution of essential nutrients at plant’s cation exchange sites. These ions readily influence role of various enzymes and proteins, arrest metabolism, and reveal phytotoxicity. On account of recent advancements on beneficial HMs ions Co, Cu, Fe, Mn, Mo, Ni, and Zn in soil-plant system, the present paper: overview the sources of HMs in soils and their uptake and transportation mechanism, here we have discussed the role of metal transporters in transporting the essential metal ions from soil to plants. The role played by Co, Cu, Fe, Mn, Mo, Ni, and Zn at both low and high level on the plant growth and development and the mechanism to alleviate metal toxicity at high level have been also discussed. At the end, on concluding the article we have also discussed the future perspective in respect to beneficial HM ions interaction with plant at both levels.

  13. Preconcentration and determination of trace elements with 2,6-diacetylpyridine functionalized Amberlite XAD-4 by flow injection and atomic spectroscopy.

    Science.gov (United States)

    Kara, Derya; Fisher, Andrew; Hill, Steve J

    2005-11-01

    An on-line flow injection method for the direct determination of trace elements in environmental samples is described. A mini-column packed with 2,6-diacetylpyridine functionalized Amberlite XAD-4 was used to preconcentrate and separate 8 trace metals (Cd, Co, Cu, Mn, Ni, Pb, U and Zn) from water and extracts from solid samples. The metals were eluted with 0.1 M HNO(3) directly to the detection system (either inductively coupled plasma-mass spectrometry (ICP-MS) or flame atomic absorption spectrometry (FAAS)). As well as demonstrating that the resin could be used to preconcentrate ultra-trace analytes from natural waters, it was also shown to work well at a pH of 5.5. Therefore, after treatment of sample digests with sodium fluoride, samples that contain extremely large concentrations of iron may be analysed for trace analytes without the excess iron overloading the capacity of the resin. To this end, the analytes Cd, Co, Cu and Ni were preconcentrated from acid extracts of certified soil/sediment samples and then eluted with nitric acid to be determined on-line. Limits of detection (3sigma) of Cd = 0.33 microg l(-1), Co = 0.094 microg l(-1), Cu = 0.34 microg l(-1), Mn = 0.32 microg l(-1), Ni = 0.30 microg l(-1), Pb = 0.43 microg l(-1), U = 0.067 microg l(-1) and Zn = 0.20 microg l(-1) for the FI-ICP-MS system and Cd = 22 microg l(-1), Co = 60 microg l(-1), Cu = 10 microg l(-1) and Ni = 4.8 microg l(-1) for the FI-FAAS system were obtained. Analysis of certified reference materials showed good agreement with the certified values using the two methods.

  14. Giant magnetic coercivity in CaCu{sub 5}-type SmNi{sub 3}TSi (T=Mn–Cu) solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Jinlei; Yan, Xu [Research Center for Solid State Physics and Materials, School of Mathematics and Physics, Suzhou University of Science and Technology, Suzhou 215009 (China); Morozkin, A.V., E-mail: morozkin@tech.chem.msu.ru [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation)

    2015-12-15

    The effects of transition metal substitution for Ni on the magnetic properties of the CaCu{sub 5}-type SmNi{sub 3}TSi (T=Mn, Fe, Co, Cu) solid solutions have been investigated. SmNi{sub 3}MnSi, SmNi{sub 3}FeSi, SmNi{sub 3}CoSi and SmNi{sub 3}CuSi show ferromagnetic ordering at 125 K, 190 K, 46 K and 12 K and field induced transitions at 65 K, 110 K, 30 K and 6 K, respectively. The magnetocaloric effects of SmNi{sub 3}TSi (T=Mn, Fe, Co, Cu) were calculated in terms of isothermal magnetic entropy change (ΔS{sub m}). The magnetic entropy ΔS{sub m} reaches value of −1.1 J/kg K at 130 K for SmNi{sub 3}MnSi, −0.4 J/kg K at 180 K for SmNi{sub 3}FeSi, −0.37 J/kg K at 45 K for SmNi{sub 3}CoSi and −0.5 J/kg K at 12 K for SmNi{sub 3}CuSi in field change of 0–50 kOe around the ferromagnetic ordering temperature. They show positive ΔS{sub m} of +2.4 J/kg K at 30 K for SmNi{sub 3}MnSi, −2.6 J/kg K at 65 K for SmNi{sub 3}FeSi, +0.73 J/kg K at 15 K for SmNi{sub 3}CoSi and −0.5 J/kg K at 6 K for SmNi{sub 3}CuSi in field change of 0–50 kOe around the metamagnetic-like transition temperature. Below the field induced transition temperature, SmNi{sub 3}TSi (T=Mn, Fe, Co, Cu) exhibits giant magnetic coercivity of 80 kOe at 20 K for SmNi{sub 3}MnSi, 87 kOe at 40 K for SmNi{sub 3}FeSi, 27 kOe at 20 K for SmNi{sub 3}CoSi and 54 kOe at 5 K for SmNi{sub 3}CuSi. - Graphical abstract: CaCu{sub 5}-type SmNi{sub 3}MnSi, SmNi{sub 3}FeSi, SmNi{sub 3}CoSi and SmNi{sub 3}CuSi show ferromagnetic ordering at 125 K, 190 K, 46 K and 12 K and field induced transitions at 65 K, 110 K, 30 K and 6 K, respectively. The magnetic entropy ΔS{sub m} reaches value of −1.1 J/kg K at 130 K for SmNi{sub 3}MnSi, −0.4 J/kg K at 180 K for SmNi{sub 3}FeSi, −0.37 J/kg K at 45 K for SmNi{sub 3}CoSi and −0.5 J/kg K at 12 K for SmNi{sub 3}CuSi in field change of 0–50 kOe around the ferromagnetic ordering temperature. They show positive ΔS{sub m} of +2.4 J/kg K at 30 K for SmNi{sub 3}MnSi, −2

  15. Fabrication and magnetic properties of Co7oCu3o alloy nanowire arrays with high coercivity%高矫顽力的C0(70)Cu(30)合金纳米线阵列的制备及磁性研究

    Institute of Scientific and Technical Information of China (English)

    刘晓旭; 赵兴涛; 张颖; 朱岩; 吴光恒

    2012-01-01

    利用直流电化学沉积法,在多孔阳极氧化铝模板中首次制备出了具有[220]取向的单晶面心立方结构的CoCu固溶体合金纳米线阵列,其Co含量高达70%.透射电子显微镜显示纳米线均匀连续,具有较高的长径比,约为300.磁性测量表明所制备的Co(70)Cu(30)合金纳米线具有超高的矫顽力Hc//=2438 Oe(1 Oe=79.5775 A/m)和较高的矩形比S//=0.76,远高于以往报道的CoCu合金纳米线的磁性,分析表明磁性好的主要原因是由于较高Co含量和高形状各向异性.通过磁性测量和模型计算,得到Co(70)Cu(30)合金纳米线阵列在反磁化过程中遵从对称扇型转动的球链模型,并从结构的角度分析了Co(70)Cu(30)合金纳米线阵列的反磁化行为.%CoCu solid solution alloy nanowire arrays which exhibit the face-centered cubic structure with strong [220] orientation along the nanowire axes are fabricated for first time in the anodic aluminum oxide template by electrodeposition. The proportion of Co ingredient in CoCu alloy nanowire arrays is up to 70%. Transmission electron microscopy revealts that the nanowire arrays are uniform and continuous and have a large aspect ratio of about 300. The magnetic hysteresis loop demonstrates that the Cor0Cua0 alloy nanowire arrays have a large coercivity of about 2438 Oe and relatively large squareness of about 0.76 parallel to nanowire arrays which greatly exceeds the value previousely reported. Good magnetic properties are achieved due mainly to the larger proportion of Co ingredient than that in the normal CoCu alloy nanowire arrays and the large shape anisotropy. The results of magnetic measurement and the calculations from formula demonstrate that the symmetric fanning mechanism of sphere chains model could be employed to explain the magnetization reversal process which is related to the structure of the Co70Cu3o nanowire arrays.

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

    Institute of Scientific and Technical Information of China (English)

    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%.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  18. The use of electrothermal vaporizer coupled to the inductively coupled plasma mass spectrometry for the determination of arsenic, selenium and transition metals in biological samples treated with formic acid

    Energy Technology Data Exchange (ETDEWEB)

    Tormen, Luciano, E-mail: lucianotormen@hotmail.com [Departamento de Quimica, Universidade Federal de Santa Catarina, Depto. Quimica, Campus Trindade, 88040-900 Florianopolis, SC (Brazil); Universidade Federal da Fronteira Sul - UFFS, Campus Laranjeiras do Sul, 85303-775 Laranjeiras do Sul, PR (Brazil); Gil, Raul A. [Instituto de Quimica de San Luis (UNSL-CONICET), Chacabuco y Pedernera, D5700BWQ San Luis (Argentina); Frescura, Vera L.A. [Departamento de Quimica, Universidade Federal de Santa Catarina, Depto. Quimica, Campus Trindade, 88040-900 Florianopolis, SC (Brazil); Martinez, Luis Dante [Instituto de Quimica de San Luis (UNSL-CONICET), Chacabuco y Pedernera, D5700BWQ San Luis (Argentina); Curtius, Adilson J. [Departamento de Quimica, Universidade Federal de Santa Catarina, Depto. Quimica, Campus Trindade, 88040-900 Florianopolis, SC (Brazil)

    2012-03-02

    Highlights: Black-Right-Pointing-Pointer Simple sample treatment of biologic samples with formic acid is proposed. Black-Right-Pointing-Pointer The treatment with formic acid is easy, rapid, less expensive and environmental friendly allowing a high sample throughput. Black-Right-Pointing-Pointer External calibration with aqueous standard allows the simultaneous determination of As, Co, Cu, Fe, Mn, Ni, Se and V. Black-Right-Pointing-Pointer The use of ETV avoids plasma instability, carbon deposit on the cones and does not require sample digestion. - Abstract: A fast method for the determination of As, Co, Cu, Fe, Mn, Ni, Se and V in biological samples by ETV-ICP-MS, after a simple sample treatment with formic acid, is proposed. Approximately 75 mg of each sample is mixed with 5 mL of formic acid, kept at 90 Degree-Sign C for 1 h and then diluted with nitric acid aqueous solution to a 5% (v/v) formic acid and 1% (v/v) nitric acid final concentrations. A palladium solution was used as a chemical modifier. The instrumental conditions, such as carrier gas flow rate, RF power, pyrolysis and vaporization temperatures and argon internal flow rate during vaporization were optimized. The formic acid causes a slight decrease of the analytes signal intensities, but does not increase the signal of the mainly polyatomic ions ({sup 14}N{sup 35}Cl{sup +}, {sup 14}N{sup 12}C{sup +}, {sup 40}Ar{sup 12}C{sup +}, {sup 13}C{sup 37}Cl{sup +}, {sup 40}Ar{sup 36}Ar{sup +}, {sup 40}Ar{sup 35}Cl{sup +}, {sup 35}Cl{sup 16}O{sup +}, {sup 40}Ar{sup 18}O{sup +}) that affect the analytes signals. The effect of charge transfer reactions, that could increase the ionization efficiency of some elements with high ionization potentials was not observed due to the elimination of most of the organic compounds during the pyrolysis step. External calibration with aqueous standard solutions containing 5% (v/v) formic acid allows the simultaneous determination of all analytes with high accuracy. The

  19. Formation of Fe-oxyhydroxides from the East Pacific Rise near latitude 13°N:Evidence from mineralogical and geochemical data

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The mineralogical and geochemical characteristics of Fe-oxyhydroxide samples from one dredge station (long. 103°54.48’W, lat. 12°42.30’N, water depth 2655 m) on the East Pacific Rise near lat 13°N were analyzed by XRD, ICP-AES, and ICP-MS. Most Fe-oxyhydroxides are amorphous, with a few sphalerite microlites. In comparison with Fe-oxyhydroxides from other fields, the variable ranges in the chemical composition of Fe-oxyhydroxide samples are very narrow; their Fe, Si, and Mn contents were 39.90%, 8.92%, and 1.59%, respectively; they have high Cu (0.88%―1.85%) and Co (65×10?6―704×10?6) contents, and contain Co+Cu+Zn+Ni> 1.01%. The trace-element (As, Co, Ni, Cu, Zn, Ba, Sr) and major-element (Fe, Ca, Al, Mg) contents of these samples are in the range of hydrothermal sulfide from the East Pacific Rise near 13°N, reflecting that this type of Fe-oxyhydroxide constitutes a secondary oxidation product of hydrothermal sulfide. The Fe-oxyhydroxide samples from one dredge station on the East Pacific Rise near 13°N are lower in ΣREE (5.44×10?6―17.01×10?6), with a distinct negative Ce anomaly (0.12 ― 0.28). The Fe-oxyhydroxide samples have similar chondrite-normalized rare-earth-element (REE) patterns to that of seawater, and they are very different from the REE composition characteristics of hydrothermal plume particles and hydrothermal fluids, showing that the REEs of Fe-oxyhydroxide are a major constituent of seawater and that the Fe-oxyhydroxides can become a sink of REE from seawater. The quick settling of hydrothermal plume particles resulted in the lower REE content and higher Mn content of these Fe-oxyhydroxides, which are captured in part of the V and P from seawater by adsorption. The Fe-oxyhydroxides from one dredge station on the East Pacific Rise near 13°N were formed by secondary oxidation in a low temperature, oxygenated environment. In comparison with the elemental (Zn, Cd, Pb, Fe, Co, Cu) average content of hydrothermal sulfide samples

  20. Preparación de Materiales Fotocatalizadores Basados en Bi4Ti3O12 Dopados con Metales de Transición

    Directory of Open Access Journals (Sweden)

    Jardiel, T.

    2012-02-01

    Full Text Available The production of hydrogen from water using ceramic semiconductors with photocatalytic 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 photocatalysts 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 photocatalytic 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.La producción de hidrógeno a partir de agua mediante el empleo de semiconductores cerámicos con propiedades fotocatalíticas ha adquirido especial relevancia en los últimos años, debido a su potencial uso para la obtención de hidrógeno de un modo directo y limpio. En la búsqueda de nuevos materiales que presenten propiedades fotocatalíticas en la región visible del espectro solar, el dopado con metales de transición ha demostrado ser un método eficaz de adecuar los valores de band gap del semiconductor. En este trabajo se aborda el estudio del efecto de la adición de distintos dopantes (Fe, Ni, Cr, Mn, Co, Cu sobre la estructura y valor de band gap del Bi4Ti3O12, con el objetivo de mejorar su actividad fotocatalítica y hacerlo activo en el visible. En este sentido se han preparado materiales dopados basados en BIT por procesamiento en estado s

  1. 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

    Energy Technology Data Exchange (ETDEWEB)

    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

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

    Science.gov (United States)

    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

  3. Evaluating top soil trace element pollution in the vicinity of a cement plant and a former open-cast uranium mine in central Argentina

    Energy Technology Data Exchange (ETDEWEB)

    Bermudez, Gonzalo M.A.; Pignata, Maria Luisa [Cordoba Univ. Nacional (AR). Inst. Multidisciplinario de Biologia Vegetal (IMBIV); Moreno, Monica; Invernizzi, Rodrigo; Pla, Rita [Comision Nacional de Energia Atomica (CAE), Buenos Aires (Argentina). Tecnicas Analiticas Nucleares

    2010-10-15

    Heavy metals are especially dangerous because of their persistence and toxicity. Soil behaves as a sink of heavy metals by aerial deposition of particles emitted by different human activities. The aims of this work were to identify the levels and sources of heavy metal and trace elements in agricultural and residential areas in Argentina and to evaluate the enrichment of total and HCl-extracted heavy metals. Materials and methods: Ninety-four topsoil samples were collected in Cordoba, Argentina (0-10 cm). The majority of the samples were subject to agricultural practices. The possible metal pollution sources were a cement plant and an industrial waste incinerator, a former open-cast uranium mine, petrochemical, and mechanical and metallurgical industries among others. The elements As, Ba, Ca, Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Na, Nd, Rb, Sb, Sc, Se, Sm, Ta, Tb, Th, U, Yb, and Zn were measured by neutron activation analysis, and Co, Cu, Fe, Mn, Ni, Pb, and Zn were partially extracted by 0.5-M HCl and measured using atomic absorption spectroscopy. Several nonparametric statistics were performed to the dataset in order to accomplish the objectives of the study. Results and discussion: The mean total Ba concentration exceeded soil quality guidelines for residential areas, with the maximum total As and Co concentrations surpassing the agricultural and residential limits stated in national and international legislations. The elements As and Ba were found to be controlled by parent factors, whereas Ca, Co, Cr, Cu, Mn, Ni, Pb, and Zn were controlled by both anthropogenic and pedogenic factors. A cement plant was the main source of Ca, Co, Cr, Cu, Mn, Ni, Pb, and Zn, whereas lanthanides, Fe, K, U, and also Zn were associated with a former open-cast operation uranium mine. A correlation analysis showed that soil organic matter and pH had strong associations with 0.5-M HCl-extracted Co, Cu, Mn, Ni, Pb, and Zn. Conclusions: Fe-normalized enrichment factors calculated for

  4. Trace metals partitioning among different sedimentary mineral phases and the deposit-feeding polychaete Armandia brevis

    Energy Technology Data Exchange (ETDEWEB)

    Díaz-de-Alba, Margarita [Department of Analytical Chemistry, Institute of Biomolecules (INBIO), Faculty of Sciences, CEI-MAR, University of Cadiz, Campus Rio S. Pedro, E-11510, Puerto Real, Cadiz (Spain); Huerta-Diaz, Miguel Angel, E-mail: huertam@uabc.edu.mx [Instituto de Investigaciones Oceanológicas, Universidad Autónoma de Baja California, Campus Ensenada, Km. 103 Carr. Tijuana-Ensenada, Ensenada 22800, Baja California (Mexico); Delgadillo-Hinojosa, Francisco [Instituto de Investigaciones Oceanológicas, Universidad Autónoma de Baja California, Campus Ensenada, Km. 103 Carr. Tijuana-Ensenada, Ensenada 22800, Baja California (Mexico); Hare, Landis [Centre Eau Terre Environnement, 490, rue de la Couronne, Québec, Québec G1K 9A9 (Canada); Galindo-Riaño, M. Dolores [Department of Analytical Chemistry, Institute of Biomolecules (INBIO), Faculty of Sciences, CEI-MAR, University of Cadiz, Campus Rio S. Pedro, E-11510, Puerto Real, Cadiz (Spain); Siqueiros-Valencia, Arturo [Instituto de Investigaciones Oceanológicas, Universidad Autónoma de Baja California, Campus Ensenada, Km. 103 Carr. Tijuana-Ensenada, Ensenada 22800, Baja California (Mexico)

    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{sup 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 (< 25%) while degrees of sulfidization (DOS) were high (~ 50%) because of the contribution of acid volatile sulfide. DOP values correlated with DTMP values (p ≤ 0.001), indicating that metals are gradually incorporated into pyrite as this mineral is formed. Significant correlations were also found between DTMP values and − log(K{sub sp(MeS)}/K{sub sp(pyr)}) for both harbors, indicating that incorporation of trace metals into the pyrite phase is a function of the solubility product of the corresponding metal sulfide. The order in which elements were pyritized in both harbors was Zn ≈ Mn < Fe < Cd ≈ Pb < Ni ≈ Co < < Cu. Lastly, a strong correlation (r{sup 2} = 0.87, p < 0.01) was found between average reactive trace metal concentrations and metal concentrations measured in Armandia brevis (a deposit-feeding Opheliid polychaete), suggesting that these labile sedimentary metals are

  5. Mineralogical and geochemical characterization of weathering profiles developed on mylonites in the Fodjomekwet-Fotouni section of the Cameroon Shear Zone (CSZ), West Cameroon

    Science.gov (United States)

    Tematio, P.; Tchaptchet, W. T.; Nguetnkam, J. P.; Mbog, M. B.; Yongue Fouateu, R.

    2017-07-01

    The mineralogical and geochemical investigation of mylonitic weathering profiles in Fodjomekwet-Fotouni was done to better trace the occurrence of minerals and chemical elements in this area. Four representative soil profiles were identified in two geomorphological units (upland and lowland) differentiating three weathering products (organo-mineral, mineral and weathered materials). Weathering of these mylonites led to some minerals association such as vermiculite, kaolinite, goethite, smectite, halloysite, phlogopite and gibbsite. The minerals in a decreasing order of abundance are: quartz (24.2%-54.8%); kaolinite (8.4%-36.0%); phlogopite (5.5%-21.9%); goethite (7.8%-16.1%); vermiculite (6.7%-15.7%); smectite (10.2%-11.9%); gibbsite (9.0%-11.8%) and halloysite (5.6%-11.5%) respectively. Patterns of chemical elements allow highlighting three behaviors (enriched elements, depleted elements and elements with complex behavior), depending on the landscape position of the profiles. In the upland weathering products, K, Cr and REEs are enriched; Ca, Mg, Na, Mn, Rb, S and Sr are depleted while Si, Al, Fe, Ti, Ba, Co, Cu, Ga, Mo, Nb, Ni, Pb, Sc, V, Y, Zn and Zr portray a complex behavior. Contrarily, the lowland weathering profiles enriched elements are Fe, Ti, Co, Cr, Cu, V, Zr, Pr, Sm, Tb, Dy, Er and Yb; while depleted elements are Ca, Mg, K, Na, Mn, Ba, Ga, S, Sr, Y, Zn, La, Ce and Nd; and Si, Al, Mo, Nb, Ni, Pb, Rb, Sc evidenced complex behaviors. In all the studied weathering products, the REEs fractionation was also noticeable with a landscape-position dependency, showing light REEs (LREEs) enrichment in the upland areas and heavy REEs (HREEs) in lowland areas. SiO2, Al2O3 and Fe2O3 are positively correlated with most of the traces and REEs (Co, Cu, Nb, Ni, Mo, Pb, Sc, V, Zn, Zr, La, Ce, Sm, Tb, Dy, Er, Yb), pointing to the fact that they may be incorporated into newly formed clay minerals and oxides. Ba, Cr, Ga, Rb, S, Sr, Y, Pr and Nd behave like alkalis and

  6. Biomonitoring of essential and toxic metals in single hair using on-line solution-based calibration in laser ablation inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Dressler, Valderi L; Pozebon, Dirce; Mesko, Marcia Foster; Matusch, Andreas; Kumtabtim, Usarat; Wu, B; Sabine Becker, J

    2010-10-15

    Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been established as a powerful and sensitive surface analytical technique for the determination of concentration and distribution of trace metals within biological systems at micrometer spatial resolution. LA-ICP-MS allows easy quantification procedures if suitable standard references materials (SRM) are available. In this work a new SRM-free approach of solution-based calibration method in LA-ICP-MS for element quantification in hair is described. A dual argon flow of the carrier gas and nebulizer gas is used. A dry aerosol produced by laser ablation (LA) of biological sample and a desolvated aerosol generated by pneumatic nebulization (PN) of standard solutions are carried by two different flows of argon as carrier or nebulizer gas, respectively and introduced separately in the injector tube of a special ICP torch, through two separated apertures. Both argon flows are mixed directly in the ICP torch. External calibration via defined standard solutions before analysis of single hair was employed as calibration strategy. A correction factor, calculated using hair with known analyte concentration (measured by ICP-MS), is applied to correct the different elemental sensitivities of ICP-MS and LA-ICP-MS. Calibration curves are obtained by plotting the ratio of analyte ion M(+)/(34)S(+) ion intensities measured using LA-ICP-MS in dependence of analyte concentration in calibration solutions. Matrix-matched on-line calibration in LA-ICP-MS is carried out by ablating of human hair strands (mounted on a sticky tape in the LA chamber) using a focused laser beam in parallel with conventional nebulization of calibration solutions. Calibrations curves of Li, Na, Mg, Al, K, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, Sr, Mo, Ag, Cd, I, Hg, Pb, Tl, Bi and U are presented. The linear correlation coefficients (R) of calibration curves for analytes were typically between 0.97 and 0.999. The limits of detection (LODs) of

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

    Energy Technology Data Exchange (ETDEWEB)

    Setala V. Naidu

    2003-01-01

    We have produced Co, Cu, and Fe nano-particles by Laser-induced solution deposition (LISD) as evidenced by TEM investigations. Sizes of the nano-particles created are in the order of 5 nm. The LISD system could generate nano-particles in quantities only in the order of a milligram. This may be mainly due to the limited photo induced reactions taking place on the surface of the solutions. We have designed experiments to use drop flow technique with LISD for nano-particle deposition on microreactors. Preliminary work has been done on Co and Fe thin film deposited microreactors. We are also investigating the catalytic properties of nano-particles of FeO and CoO prepared by ball milling and dispersed into sol-gel prepared alumina granules. We have continued our investigation of catalytic reactions of Cu, Co, Fe, Cu/Co, Cu/Fe and Co/Fe on alumina support. The metal oxides were first reduced with hydrogen and used for the conversion of CO/H{sub 2}. The surface area of the catalysts has been determined by nitrogen disorption. They are in the range of 200-300 m{sup 2}/g. Cu, Co, Fe, Co/Fe, Cu/Co and Cu/Fe showed increasing order of catalytic activity for CO/H{sub 2} conversion. We are also studying catalytic conversion rates for CO{sub 2}/H{sub 2} and CO/CO{sub 2}/H{sub 2} mixtures using these catalysts. Our investigations of Co and Fe thin film deposited microreactors showed higher CO/H{sub 2} conversion for Fe compared to Co. We have used vibrating sample magnetometer (VSM) to study the magnetic characteristics of as prepared, reduced, post-reaction catalysts. Comparative study of the ferromagnetic component of these samples gives the reduction efficiency and the changes in metal centers during catalytic reactions. Magnetic studies of post-reaction Co and Fe micro-reactors show that more carbide formation occurs for iron compared to cobalt.

  8. Feasibility of pressurization to speed up enzymatic hydrolysis of biological materials for multielement determinations.

    Science.gov (United States)

    Moreda-Piñeiro, Antonio; Bermejo-Barrera, Adela; Bermejo-Barrera, Pilar; Moreda-Piñeiro, Jorge; Alonso-Rodríguez, Elia; Muniategui-Lorenzo, Soledad; López-Mahía, Purificación; Prada-Rodríguez, Darío

    2007-03-01

    The feasibility of pressurized solvents (liquids at a high pressure and/or high temperature without the subcritical point being reached) has been newly investigated to accelerate enzymatic hydrolysis processes of mussel tissue for multielement determinations. The target elements (Al, As, Cd, Co, Cu, Fe, Hg, Li, Mn, Pb, Se, Sr, V, and Zn) were released from dried mussel tissue by action of two proteases (pepsin and pancreatin), and they have been evaluated by inductively coupled plasma optical emission spectrometry (ICP-OES). Variables inherent to the enzymatic activity (pH, ionic strength, temperature, and enzyme mass) and factors affecting pressurization (static time, pressure, and number of cycles) were simultaneously studied by applying a Plackett-Burman design (PBD) as the screening method. Results showed that pH, ionic strength, and temperature were the most statistically significant factors (confidence interval of 95%) under pressurized conditions for pepsin, while pH and ionic strength affected pancreatin activity. This means that metal extraction is mostly attributed to enzymatic activity. The static time (enzymatic hydrolysis time) was found statistically nonsignificant for most of the elements, meaning that the hydrolysis procedure can be finished within a 2-15 min range. For pepsin, optimized conditions (pH 1.0, temperature 40 degrees C, pressure 1500 psi, static time 2 min, and number of cycles 3) gave quantitative extractions for As, Cd, Co, Cu, Hg, Li, Mn, Pb, Se, Sr, V, and Zn. The pepsin mass was 0.05 g, and the solution was Milli-Q water at pH 1.0 (adjusted with hydrochloric acid). For pancreatin, quantitative recoveries were only reached for As, Cd, Cu, Li, Pb, and Sr at room temperature, at a pressure of 1500 psi, for a static time of 2 min and a number of cycles of 3. The extraction solution was a 0.3 M potassium dihydrogen phosphate/potassium hydrogen phosphate buffer at a pH of 7.5 working at room temperature. Around 0.5 g of diatomaceous

  9. Microstructures and magnetic properties of meta-stable Co{sub 50−X}M{sub X}Pt{sub 50} (M = Cu or Ru) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sun, An-Cheng, E-mail: acsun@saturn.yzu.edu.tw; Huang, Chuan-Fa; Chen, Sheng-Fu; Chen, Yu-Shen

    2014-11-03

    Co{sub 50−X}M{sub X}Pt{sub 50} (M = Cu or Ru) films were magnetron sputtered on textured Pt(111) underlayer on glass substrate at 350 °C. The results show that perpendicular magnetic anisotropy of superlattice L1{sub 1} phase can be maintained well with doping Cu element into CoPt film. Out-of-plane coercivity (H{sub c⊥}) was also increased with the increase of Cu content. However, disordered A1(111) structure and lower H{sub c⊥} were obtained with the addition of Ru element in CoPt film. The magnetic force microscopy images indicated that doping Cu diminished the domain size. Oppositely, doping Ru made the domain reversed incompletely. Surface morphology of Co{sub 24}Cu{sub 26}Pt{sub 50} thin film was much smoother than that of Co{sub 23}Ru{sub 27}Pt{sub 50} thin film, indicative of maintenance of the epitaxial growth of L1{sub 1}(111) from flat Pt(111) underlayer. The transmission electron microscopy (TEM) images show that the Cu element could be incorporated in L1{sub 1} CoPt grains; however, the RuPt alloy was segregated at CoPt grain boundary. The cross section TEM pictures showed that the columnar structures starting from Pt(111) underlayer and extending into magnetic CoCuPt(111) layer confirmed that epitaxy existed at CoCuPt/Pt interface. Our research demonstrates that replacing Co with Cu = 23–26 at.% effectively increases the perpendicular magnetic properties of L1{sub 1} CoPt phase, which largely increase the potential of L1{sub 1} films for the application of perpendicular magnetic media and advance spintronic device. - Highlights: • Strengthen superstructural CoPt phase with perpendicular magnetic anisotropy • Enhanced coercivity in L1{sub 1} CoPt thin films with doping 3rd elements • Impedances of domain wall motion adjusted the coercivity.

  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

    Energy Technology Data Exchange (ETDEWEB)

    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. Cytotoxicity of alloying elements and experimental titanium alloys by WST-1 and agar overlay tests.

    Science.gov (United States)

    Song, Yo-Han; Kim, Min-Kang; Park, Eun-Jin; Song, Ho-Jun; Anusavice, Kenneth J; Park, Yeong-Joon

    2014-09-01

    This study was performed to evaluate the biocompatibility of nine types of pure metals using 36 experimental prosthetic titanium-based alloys containing 5, 10, 15, and 20wt% of each substituted metal. The cell viabilities for pure metals on Ti alloys that contain these elements were compared with that of commercially pure (CP) Ti using the WST-1 test and agar overlay test. The ranking of pure metal cytotoxicity from most potent to least potent was: Co>Cu>In>Ag>Cr>Sn>Au>Pd>Pt>CP Ti. The cell viability ratios for pure Co, Cu, In, and Ag were 13.9±4.6%, 21.7±10.4%, 24.1±5.7%, and 24.8±6.0%, respectively, which were significantly lower than that for the control group (p<0.05). Pure Pd and Pt demonstrated good biocompatibility with cell viabilities of 93.8±9.6% and 97.2±7.1%, respectively. The Ti-5Pd alloy exhibited the highest cell viability (128.4±21.4%), which was greater than that of CP Ti. By alloying pure Co or Cu with Ti, the cell viabilities for the Ti-xCo and Ti-xCu alloys increased significantly up to 10wt% of the alloying element followed by a gradual decrease with a further increase in the concentration of the alloying element. Based on the agar overlay test, pure Ag, Co, Cr, Cu, and In were ranked as 'moderately cytotoxic', whereas all Ti alloys were ranked as 'noncytotoxic'. The cytotoxicity of pure Ag, Co, Cr, Cu, and In suggests a need for attention in alloy design. The cytotoxicity of alloying elements became more biocompatible when they were alloyed with titanium. However, the cytotoxicity of titanium alloys was observed when the concentration of the alloying element exceeded its respective allowable limit. The results obtained in this study can serve as a guide for the development of new Ti-based alloy systems. Copyright © 2014 Academy of Dental Materials. All rights reserved.

  12. Co and Cu modified Ni/Al2 O3 steam reforming catalysts for hydrogen production from model bio-oil%Ni/Al2 O3改性催化剂催化重整生物油模拟物制氢研究

    Institute of Scientific and Technical Information of China (English)

    谢登印; 张素平; 陈志远; 陈振奇; 许庆利

    2015-01-01

    制备了 Ni/Al2 O3、Ni-Cu/Al2 O3、Ni -Co/Al2 O3和 Ni -Co-Cu/Al2 O3催化剂,研究了 Co 和 Cu 对生物油水蒸气催化重整的影响。实验表明,Co 能促进水汽变换(WGS)反应,提高氢气的产率,Cu 能抑制反应中焦炭的形成,提高催化剂的稳定性。对催化剂 Ni-Co-Cu/Al2 O3进行工艺条件考察,当900℃、水油比为6 g/g、质量空速(WHSV)为1 h-1时,碳选择性达到87.5%,氢气产率达到84.2%,潜在氢气产率达到92.4%。%Ni/Al2 O3 cat aly st was selected as the reference catalyst for steam reformi ng of mo del bio-oil to produce hydrog en.Ni-Cu/Al2 O3 , Ni-Co/Al2 O3 and Ni-Co-Cu /Al2 O3 were prepared to investigate the influence of Co and Ni on steam reforming of bio-oil.The results show that Co can enhance the water gas shift (WGS) reaction rate, and Cu can prevent the formation of coke.The reaction conditions for the steam re formi ng of bio-oil with the Ni-Co-Cu/Al2 O3 catalyst were optimized as the follows: te mper ature of900 ℃, wat er-oil ratio (the mass ratio of steam to oil) of 6 g/g and weight hourly space velocity (WHSV) of 1 h-1 .The carbon selectivity of 87.5%, hydrogen yield of 84.2% and potential hydrogen yield of 92.4% can be obtained at the optimum conditions.

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

    Energy Technology Data Exchange (ETDEWEB)

    Setala V. Naidu

    2003-01-01

    We have produced Co, Cu, and Fe nano-particles by Laser-induced solution deposition (LISD) as evidenced by TEM investigations. Sizes of the nano-particles created are in the order of 5 nm. The LISD system could generate nano-particles in quantities only in the order of a milligram. This may be mainly due to the limited photo induced reactions taking place on the surface of the solutions. We have designed experiments to use drop flow technique with LISD for nano-particle deposition on microreactors. Preliminary work has been done on Co and Fe thin film deposited microreactors. We are also investigating the catalytic properties of nano-particles of FeO and CoO prepared by ball milling and dispersed into sol-gel prepared alumina granules. We have continued our investigation of catalytic reactions of Cu, Co, Fe, Cu/Co, Cu/Fe and Co/Fe on alumina support. The metal oxides were first reduced with hydrogen and used for the conversion of CO/H{sub 2}. The surface area of the catalysts has been determined by nitrogen disorption. They are in the range of 200-300 m{sup 2}/g. Cu, Co, Fe, Co/Fe, Cu/Co and Cu/Fe showed increasing order of catalytic activity for CO/H{sub 2} conversion. We are also studying catalytic conversion rates for CO{sub 2}/H{sub 2} and CO/CO{sub 2}/H{sub 2} mixtures using these catalysts. Our investigations of Co and Fe thin film deposited microreactors showed higher CO/H{sub 2} conversion for Fe compared to Co. We have used vibrating sample magnetometer (VSM) to study the magnetic characteristics of as prepared, reduced, post-reaction catalysts. Comparative study of the ferromagnetic component of these samples gives the reduction efficiency and the changes in metal centers during catalytic reactions. Magnetic studies of post-reaction Co and Fe micro-reactors show that more carbide formation occurs for iron compared to cobalt.

  14. Partitioning, bioavailability and origin of heavy metals from the Nador Lagoon sediments (Morocco) as a basis for their management

    Science.gov (United States)

    González, I.; Águila, E.; Galán, E.

    2007-08-01

    Nador Lagoon sediments show low trace element concentrations, and, in relation to the lagoon geochemical baseline, only some anomalies for As, Cd, Cu and Pb in the NW of the lagoon deserve to be outstanding. The distribution of major, minor and trace elements in the lagoon allows a breakdown in four zones. Between “Beni Ensar” and “Atelouane” (zone A), a quite confined zone rich in organic matter and S, the most important trace-element anomalies (As, Cd, Co, Cu, Mn, Pb, Zn) were found, mainly around industry and old mining activities. In the surrounding of the city of Nador (zone B), the anomalies correspond to Mn, Cu and Zn. The coastal barrier and Kebdana channel (zone C) show moderately concentrations of Cd, Cr and Ni at specific sites. The less polluted area is the SE of the lagoon (zone D), with no outstanding anomaly. In lagoon sediments, metal bioavailability is very low. The metal partitioning patterns show that Cu, Pb and Zn present a low availability because they are bounded to the residual, non-mobile phases of the sediments. Only in some sites, the fraction was associated with organic matter, which could be liberated easily. Arsenic is concentrated in both the residual phases and the organic matter, the latter being more available. Cadmium is mainly concentrated in some samples in the interchangeable fraction, which could be considered as a potentially toxic element because it is easily released. Concerning the origin of these trace elements, those found in zone A correspond mostly to a natural source by weathering of mount Gourougou volcanic rocks (As, Co, Cu, Pb and Zn), and to an anthropogenic origin (Cd) owing to the presence of industry and old mines. In zone B, contributions of Cu and Zn enter the lagoon through soil weathering and river-borne, and as anthropogenic pollution from urban wastes. In zone C the most important pollutant is Cd deduced to be of anthropogenic origin from the close industry and intensive agriculture area. In spite

  15. Pt/MOx/SiO2, Pt/MOx/TiO2, and Pt/MOx/Al2O3 Catalysts for CO Oxidation

    Directory of Open Access Journals (Sweden)

    Hongmei Qin

    2015-04-01

    Full Text Available Conventional supported Pt catalysts have often been prepared by loading Pt onto commercial supports, such as SiO2, TiO2, Al2O3, and carbon. These catalysts usually have simple metal-support (i.e., Pt-SiO2 interfaces. To tune the catalytic performance of supported Pt catalysts, it is desirable to modify the metal-support interfaces by incorporating an oxide additive into the catalyst formula. Here we prepared three series of metal oxide-modified Pt catalysts (i.e., Pt/MOx/SiO2, Pt/MOx/TiO2, and Pt/MOx/Al2O3, where M = Al, Fe, Co, Cu, Zn, Ba, La for CO oxidation. Among them, Pt/CoOx/SiO2, Pt/CoOx/TiO2, and Pt/CoOx/Al2O3 showed the highest catalytic activities. Relevant samples were characterized by N2 adsorption-desorption, X-ray diffraction (XRD, transmission electron microscopy (TEM, H2 temperature-programmed reduction (H2-TPR, X-ray photoelectron spectroscopy (XPS, CO temperature-programmed desorption (CO-TPD, O2 temperature-programmed desorption (O2-TPD, and CO2 temperature-programmed desorption (CO2-TPD.

  16. Trace metal pollution in Eastern Finnmark, Norway and Kola Peninsula, Northwestern Russia as evidenced by studies of lake sediment

    Energy Technology Data Exchange (ETDEWEB)

    Norton, S.A.; Appleby, P.G.; Dauvalter, V.; Traaen, T.S.

    1996-04-01

    The eastern part of Finnmark county in Northern Norway borders against the northwestern part of Russia. On the Russian side are the smelters of the Pechenga-Nikel Company. Sediment cores from two lakes, Hundvatn on the Norwegian side and Shuonijarvi on the Russian side, were analysed as described in the present report. Caesium from Chernobyl was detected in Shuonijarvi sediment. Americium distribution in the sediment was consistent with {sup 210}Pb dating chronology. The last century has seen increased concentrations and fluxes of Cd, Co, Cu, Ni, Pb and Zn. Except for Pb, all the fluxes are highest northeast of Nikel. Together with other data this indicates that the smelters of the Pechenga-Nikel Company have been a major source of metal pollution since their start-up. No regional pollution of the metals except Pb is evident in sediment prior to the 20th century. The histories of Pb fluxes and concentrations indicate a pollution history probably exceeding 2000 years. 17 refs., 5 figs., 6 tabs.

  17. Effect of Sm-rich liquid phase on magnetic properties and microstructures of sintered 2:17-type Sm-Co magnet

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wenchen; ZHAO Rui; FANG Yikun; ZHOU Mingge; ZHU Minggang; LI Wei

    2011-01-01

    The effect of Sm-rich liquid phase (Sm2Co3) on magnetic properties and microstructure of 2:17-type Sm-Co magnet was studied.Three phases existed in liquid phase ingot,and took on white,dark grey and grey,respectively.It was found that the composition of the grey area was similar to the nominal one.Our results indicated that the optimal composition was obtained at 3 wt.% liquid phase added,and the magnetic properties were Br=11.58 kGs,Hci>26 kOe,(BH)m=29.51 MGOe.Br increased by 3%,Hci was 13 times larger,and (BH)m was 6 times bigger than none liquid phase magnets.Moreover,with the aging time decreasing from 20 to 8 h,the squareness of the demagnetization curves got better,while the coercivity of the samples decreased.It revealed that Sm(Co,Cu)5 phase also precipitated at particle boundaries.It maybe also enhanced the coercivity.

  18. Geochemistry of trace elements and Sr- Nd isotopes of foraminifera shell from the Okinawa Trough

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Trace elemental associations and Sr - Nd isotopic compositions are of important to recognition of biogenic material from mixed marine sediments. The foraminifera shell from the Okinawa Trough strongly enrichesSr, P, Mn andBa, enriches Li, U, Th, Sc, Co, Cu, Pb, Zn, Cr, Rb, Y, Sb and light rare earth elements, slightly enriches V, Ga, Zr, Nb, Cd and middle rare earth elements,is short of Mo, In, Sn, Cs, Hf, Ta, W, Ti, Bi and heavy rare earth elements. The mechanism of elemental enrichment in forminifera is the concentrations of trace elements in sea water and selective absorption of trace elements during foraminifera living, as well as the geochemical affinity between major elements and trace elements. The REE (rare earth elements) partition pattern of foraminifera shell of the Okinawa Trough shows enrichment of middle rare earth elements with slightly negative Ce anomaly,which are different from those of foraminifera of the Pacific Ocean. The Sr, Nd isotopic ratios of the Okinawa Trough foraminifera are 0.709 769 and 0.512 162, respectively, which are different not only from those of oceanic water, but also from those of river water of China's Mainland, the former is slightly higher than those of oceanic water, but much lower than those of river water; the latter is slightly lower than those of oceanic water, but higher than those of river water, demonstrating that the Okinawa Trough sea water has been influenced by river water of China's Mainland.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. Sol-gel synthesis and structure of cordierite/tialite glass-ceramics

    Directory of Open Access Journals (Sweden)

    Lachezar Radev

    2009-09-01

    Full Text Available In the present work the results of the research on the sol-gel synthesis and structure of cordierite (2MgO·2Al2O3·5SiO2, tialite (Al2O3·TiO2 and cordierite/tialite glass-ceramics as well cordierite containing 2 wt.% of Co and Co+Cu have been described and discussed. The sol-gel synthesis was carried out using different kind of precursors as follows: Al(NO3×9H2O, Si(OC2H54 , Ti(OC4H94 , Mg(NO32×6H2O, chlorides or nitrates of corresponding metals, H2O, C2H5OH, Aqua Regia, NH4F and PEG. The synthesized gels were dried and thermally treated in the temperature range from 800°C to 1200°C. The sol-gel processes and structure of the cordierite, tialite and cordierite/tialite glass-ceramics have been investigated by means of XRD, FTIR, TEM, SEM and EPMA.

  1. Magnetic interactions in compositionally modulated nanowire arrays

    Science.gov (United States)

    Palmero, Ester M.; Béron, Fanny; Bran, Cristina; del Real, Rafael P.; Vázquez, Manuel

    2016-10-01

    Series of high hexagonally ordered compositionally modulated nanowire arrays, with different Cu layer and FeCoCu segment thicknesses and a constant diameter of 35 nm, were fabricated by electroplating from a single electrolytic bath into anodic aluminum oxide membranes. The objective of the study was to determine the influence of ferromagnetic (FM) segment and non-ferromagnetic (NFM) layer thickness on the magnetic properties, particularly coercivity and magnetic interactions. First-order reversal curve (FORC) measurements and simulations were performed to quantify the effect of the inter-/intra-nanowire magnetostatic interactions on the coercivity and interaction field distributions. The FORC coercivity increases for a thick NFM layer and long FM segments due to decoupling of the the FM segments and the increased shape anisotropy, respectively. On the other hand, the interaction field presents a parallel strong reduction for a thick NFM layer and thin FM segments, which is ascribed to a similar NFM/FM thickness ratio and degree of FM segment decoupling along the nanowire.

  2. A thermodynamic model of nickel smelting and direct high-grade nickel matte smelting processes: Part I. Model development and validation

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  4. Migration of trace elements from basalt substrate to co-located vegetation (lichens and mosses) at the Wudalianchi volcanos, Northeast China

    Science.gov (United States)

    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.

  5. 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)

    Energy Technology Data Exchange (ETDEWEB)

    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)

  6. The impact of the hyperacid Ijen Crater Lake. Part I: Concentrations of elements in crops and soil.

    Science.gov (United States)

    Heikens, Alex; Widianarko, Budi; Dewi, Inge C; De Boer, Jan L M; Seinen, Willem; van Leeuwen, Kees

    2005-09-01

    In Asembagus (East Java, Indonesia) irrigation water is contaminated with effluent from the hyperacid Ijen Crater Lake resulting in a low pH and high levels of various elements. As a first step towards a risk assessment, locally produced food items (rice, maize, cassava leaf, cassava root, peanuts) were collected and concentrations of As, B, Ca, Cd, Co, Cu, Fe, Mg, Mn, Mo, Ni, Pb, V, Zn were compared to samples from a reference area and with literature values. Further, concentrations in rice were compared to total soil concentrations in paddy fields. Compared to the reference area, food items produced in the contaminated area had increased levels of Cd, Co, Ni and Mn in particular, while levels of Mo were lower. In contrast, total soil concentrations of Cd and Mn in particular have decreased whereas especially Mo was increased. In combination with the observed soil acidification, it is likely that the bioavailable concentration of most elements in the contaminated soil is higher (except for Mo) due to an increased weathering rate and/or input via the contaminated irrigation water. In terms of human health, concentrations in foods were generally within normal literature values. However, it was observed that essential elements (in particular Fe) known for their inhibitory effects on e.g. Cd and Mn toxicity did not accumulate in crops whereas Cd and Mn did.

  7. 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

    Energy Technology Data Exchange (ETDEWEB)

    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)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  9. Synchrotron radiation X-ray fluorescence analysis on altered mineral muscovite in gold deposit

    Institute of Scientific and Technical Information of China (English)

    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.

  10. Characterization of bentonite, fibrous and kaolinite clays with regard to their use in pelotherapy; Caracterizacion de bentonitas, arcillas fibrosas y arcillas caoliniferas para su empleo en peloterapia

    Energy Technology Data Exchange (ETDEWEB)

    Pozo Martin, E.; Martin Rubi, J. A.; Pozo Rodriguez, M.

    2011-07-01

    We have characterized the mineralogical and chemical contents of several Spanish special clays (bentonite, fibrous clays and kaolin). Mineralogical analyses revealed that the samples were composed mainly of phyllosilicates (78 %-99 %) with a notable presence of dioctahedral and trioctahedral smectites in the bentonite, kaolinite in the kaolin and sepiolite or palygorskite in the fibrous clays. Illite was the common subordinate mineral in the bentonite, kaolin and palygorskite. Quartz, calcite, dolomite and feldspars were found as associate minerals with the occasional presence of zeolites and amphiboles. The chemical analysis was consistent with the mineralogy. With regard to trace elements (V, Cr, Ni, Co, Cu, Zn, As, Mo, Ba, Sb, Pb, U), the whole samples of the magnesium bentonite and sepiolite were found to have the lowest trace-element contents (<257,28 ppm ), whilst the aluminium bentonite, kaolin and particularly the palygorskite had higher contents than the other clays, with some elements occasionally exceeding the contents of previously studied common clays. Nevertheless, all the trace elements were found in lower quantities than the recommended toxicity levels and those quantities currently used in pelotherapy in Spanish spas. (Author)

  11. Sulfide assemblages in granulite xenoliths from Hannuoba Basalt, Hebei Province, China

    Institute of Scientific and Technical Information of China (English)

    Jiuhua Xu; Yuling Xie; Xuelei Chu; Jianming Liu; Qian Mao

    2005-01-01

    Granulite xenoliths are important samples for understanding the forming and evolution of the crust. The granulite xenoliths enclosed in Cenozoic basalt of Hannuoba, Hebei Province, China, contain four types of sulfide assemblages: isolate rotundity enclosed sulfides, intergranular sulfides between minerals, secondary sulfide inclusions ranging in linear, and fissure-filling sulfides.Electron microprobe analysis shows that the components of sulfides are Ni-poor pyrrhotite with the molar ratios of (Ni+Co+Cu)/Fe less than 0.2. The molar ratios of (Fe+Cu+Co+Ni)/S are less than 0.875 of normal pyrrhotite, and are less than those of mantle xenoliths, reflecting a sulfur-saturated environment. Pyrrhotite in various occurrences contains some Au and Ag, with the averages of 0.19wt%-0.22wt% Au and 0.01 wt%-0.02wt% Ag, showing the gold mineralization related to the granulitization of low crust. Ni, Co and Cu have a normal correlation with S in pyrrhotite, indicating that heavy metal elements have a same source similar to sulfur because of the degasification of upper mantle.

  12. Microbial community induces a plant defense system under growing on the lunar regolith analogue

    Science.gov (United States)

    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.

  13. Comparative trace elemental analysis of cancerous and non-cancerous tissues of rectal cancer patients using PIXE

    Science.gov (United States)

    Naga Raju, G. J.; Sarita, P.; Murthy, K. S. R.

    2017-08-01

    Particle Induced X-ray Emission (PIXE), an accelerator based analytical technique has been employed in this work for the analysis of trace elements in the cancerous and non-cancerous tissues of rectal cancer patients. A beam of 3 MeV protons generated from 3 MV Pelletron accelerator at the Ion Beam Laboratory of Institute of Physics, Bhubaneswar, India was used as projectile to excite the atoms present in the tissues samples. PIXE technique, with its capability to detect simultaneously several elements present at very low concentrations, offers an excellent tool for trace element analysis. The characteristic X-rays emitted by the samples were recorded by a high resolution Si (Li) detector. On the basis of the PIXE spectrum obtained for each sample, the elements Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, and Br were identified and their relative concentrations were estimated in the cancerous and non-cancerous tissues of rectum. The levels of Mn, Fe, Co, Cu, Zn, and As were higher (p < 0.005) while the levels of Ca, Cr and Ni were lower (p < 0.005) in the cancer tissues relative to the normal tissues. The alterations in the levels of the trace elements observed in the present work are discussed in this paper with respect to their potential role in the initiation, promotion and inhibition of cancer of the rectum.

  14. First-principles study of the stability, magnetic and electronic properties of Fe and Co monoatomic chains encapsulated into copper nanotube

    Science.gov (United States)

    Ma, Liang-Cai; Ma, Ling; Zhang, Jian-Min

    2017-07-01

    By using first-principles calculations based on density-functional theory, the stability, magnetic and electronic properties of Fe and Co monoatomic chains encapsulated into copper nanotube are systematically investigated. The binding energies of the hybrid structures are remarkably higher than those of corresponding freestanding TM chains, indicating the TM chains are significantly stabilized after encapsulating into copper nanotube. The formed bonds between outer Cu and inner TM atoms show some degree of covalent bonding character. The magnetic ground states of Fe@CuNW and Co@CuNW hybrid structures are ferromagnetic, and both spin and orbital magnetic moments of inner TM atoms have been calculated. The magnetocrystalline anisotropy energies (MAE) of the hybrid structures are enhanced by nearly fourfold compared to those of corresponding freestanding TM chains, indicating that the hybrid structures can be used in ultrahigh density magnetic storage. Furthermore, the easy magnetization axis switches from that along the axis in freestanding Fe chain to that perpendicular to the axis in Fe@CuNT hybrid structure. The large spin polarization at the Fermi level also makes the hybrid systems interesting as good potential materials for spintronic devices.

  15. Continuous One-Step Synthesis of Porous M-XF6 -Based Metal-Organic and Hydrogen-Bonded Frameworks.

    Science.gov (United States)

    Guillerm, Vincent; Garzón-Tovar, Luis; Yazdi, Amirali; Imaz, Inhar; Juanhuix, Jordi; Maspoch, Daniel

    2017-05-17

    Metal-organic frameworks (MOFs) built up from connecting M-XF6 pillars through N-donor ligands are among the most attractive adsorbents and separating agents for CO2 and hydrocarbons today. The continuous, one-step spray-drying synthesis of several members of this isoreticular MOF family varying the anionic pillar (XF6 =[SiF6 ](2-) and [TiF6 ](2-) ), the N-donor organic ligand (pyrazine and 4,4'-bipyridine) and the metal ion (M=Co, Cu and Zn) is demonstrated here. This synthetic method allows them to be obtained in the form of spherical superstructures assembled from nanosized crystals. As confirmed by CO2 and N2 sorption studies, most of the M-XF6 -based MOFs synthesised through spray-drying can be considered "ready-to-use" sorbents as they do not need additional purification and time consuming solvent exchange steps to show comparable porosity and sorption properties with the bulk/single-crystal analogues. Stability tests of nanosized M-SiF6 -based MOFs confirm their low stability in most solvents, including water and DMF, highlighting the importance of protecting them once synthesised. Finally, for the first time it was shown that the spray-drying method can also be used to assemble hydrogen-bonded open networks, as evidenced by the synthesis of MPM-1-TIFSIX. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Spin polarization and exchange coupling of Cu and Mn atoms in paramagnetic CuMn diluted alloys induced by a Co layer

    Science.gov (United States)

    Abes, M.; Atkinson, D.; Tanner, B. K.; Charlton, T. R.; Langridge, Sean; Hase, T. P. A.; Ali, M.; Marrows, C. H.; Hickey, B. J.; Neudert, A.; Hicken, R. J.; Arena, D.; Wilkins, S. B.; Mirone, A.; Lebègue, S.

    2010-11-01

    Using the surface, interface, and element specificity of x-ray resonant magnetic scattering in combination with x-ray magnetic circular dichroism, we have spatially resolved the magnetic spin polarization, and the associated interface proximity effect, in a Mn-based high-susceptibility material close to a ferromagnetic Co layer. We have measured the magnetic polarization of Mn and Cu3d electrons in paramagnetic CuMn alloy layers in [Co/Cu(x)/CuMn/Cu(x)]20 multilayer samples with varying copper layer thicknesses from x=0 to 25Å . The size of the Mn and CuL2,3 edge dichroism shows a decrease in the Mn-induced polarization for increasing copper thickness indicating the dominant interfacial nature of the Cu and Mn spin polarization. The Mn polarization is much higher than that of Cu. Evidently, the Mn moment is a useful probe of the local spin density. Mn atoms appear to be coupled antiferromagnetically with the Co layer below x=10Å and ferromagnetically coupled above. In contrast, the interfacial Cu atoms remain ferromagnetically aligned to the Co layer for all thicknesses studied.

  17. Vacuum Brazing of WC-8Co Cemented Carbides to Carbon Steel Using Pure Cu and Ag-28Cu as Filler Metal

    Science.gov (United States)

    Zhang, X. Z.; Liu, G. W.; Tao, J. N.; Shao, H. C.; Fu, H.; Pan, T. Z.; Qiao, G. J.

    2017-02-01

    The wetting and spreading behavior of commercial pure Cu and Ag-28Cu alloy on WC-8Co cemented carbide were investigated by the sessile drop technique. The contact angle of both systems obviously decreases with moderately increasing the wetting temperature. Vacuum brazing of the WC-8Co cemented carbide to SAE1045 steel using the pure Cu or Ag-28Cu as filler metal was further carried out based on the wetting results. The interfacial interactions and joint mechanical behavior involving microhardness, shear strength and fracture were analyzed and discussed. An obvious Fe-Cu-Co transition layer is detected at the WC-8Co/Cu interface, while no obvious reaction layer is observed at the whole WC-8Co/Ag-28Cu/SAE1045 brazing seam. The microhardness values of the two interlayers and the steel substrate near the two interlayers increase more or less, while those of WC-8Co cemented carbide substrates adjacent to the two interlayers decrease. The WC-8Co/SAE1045 joints using pure Cu and Ag-28Cu alloy as filler metals obtain average shear strength values of about 172 and 136 MPa, and both of the joint fractures occur in the interlayers.

  18. Gel for simultaneous chemical imaging of anionic and cationic solutes using diffusive gradients in thin films.

    Science.gov (United States)

    Kreuzeder, Andreas; Santner, Jakob; Prohaska, Thomas; Wenzel, Walter W

    2013-12-17

    We report on a novel gel based on diffusive gradients in thin films (DGT) for the simultaneous measurement of cations and anions and its suitability for high resolution chemical imaging by using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). The new high resolution mixed binding gel (HR-MBG) is based on zirconium-hydroxide and suspended particulate reagent-iminodiacetate (SPR-IDA) as resin materials which are embedded in an ether-based urethane polymer hydrogel. The use of this polymer hydrogel material allows the production of ultrathin, highly stable and tear-proof resin gel layers with superior handling properties compared to existing ultrathin polyacrylamide gels. The gel was characterized regarding its uptake kinetics, the anion and cation capacities, and the effects of pH, ionic strength, and aging on the performance of the HR-MBG. Our results demonstrate the capability of this novel gel for concomitant sampling of anions and cations. The suitability of this new gel type for DGT chemical imaging at submm spatial resolution in soils using LA-ICPMS is shown. 2D images of P, As, Co, Cu, Mn, and Zn distributions around roots of Zea mays L. demonstrate the new opportunities offered by the HR-MBG for high-resolution mapping of solute dynamics in soil and sediment hotspots, such as the rhizosphere, by simultaneous observation of anionic and cationic solute species.

  19. Density functional theory study of the effects of alloying additions on sulfur adsorption on nickel surfaces

    Science.gov (United States)

    Malyi, Oleksandr I.; Chen, Zhong; Kulish, Vadym V.; Bai, Kewu; Wu, Ping

    2013-01-01

    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.

  20. Assessment of heavy metals in Averrhoa bilimbi and A. carambola fruit samples at two developmental stages.

    Science.gov (United States)

    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.

  1. Wastewater characterization of IPEN facilities - a preliminary study

    Energy Technology Data Exchange (ETDEWEB)

    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)

  2. The isotypic family of the diarsenates MM'As{sub 2}O{sub 7} (M = Sr, Ba; M' = Cd, Hg)

    Energy Technology Data Exchange (ETDEWEB)

    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.

  3. Mineralogical-chemical composition and environmental risk potential of pond sediments at the geothermal field of Los Azufres, Mexico

    Science.gov (United States)

    Birkle, P.; Merkel, B.

    2002-01-01

    Since 1982, estimated amounts of 9,400 t, 15,000 kg, 720 kg and 105 kg of Si, Fe, As and Cs respectively have accumulated at the bottom of 18 evaporation ponds as part of the geothermal production cycle at Los Azufres. This accumulation is caused by precipitation of brine solutes during the evaporation of 10% of the total pond water volume before its re-injection into the reservoir. Extraction experiments with pond precipitates and geochemical simulations with the PHREEQC program indicate the high solubility of most precipitates under natural environmental conditions. The comparisons with the primary brine composition indicate that less than 1% of most dissolved brine solutes, except for Co, Cu, Mn, Pb, Ag, Fe and Si, are accumulated at the pond bottom. Arsenic has maximum values of 160 mg/kg in the pond sediments, and Mo, Hg and Tl also exceed international environmental standards for contaminated soils. Elevated concentrations and the mobility potential of several metals and non-metals require the application of remediation techniques for the final disposal of the sediments in the future.

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

    Directory of Open Access Journals (Sweden)

    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.

  5. Bioavailability assessment of essential and toxic metals in edible nuts and seeds.

    Science.gov (United States)

    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.

  6. Bioremediation of toxic heavy metals using acidothermophilic autotrophes.

    Science.gov (United States)

    Umrania, Valentina V

    2006-07-01

    Investigations were carried out to isolate microbial strains from soil, mud and water samples from metallurgically polluted environment for bioremediation of toxic heavy metals. As a result of primary and secondary screening various 72 acidothermophilic autotrophic microbes were isolated and adapted for metal tolerance and biosorption potentiality. The multi-metal tolerance was developed with higher gradient of concentrations of Ag, As, Bi, Cd, Cr, Co, Cu, Hg, Li, Mo, Pb, Sn and Zn. The isolates were checked for their biosolubilization ability with copper containing metal sulfide ores. In case of chalcopyrite 85.82% and in covellite as high as 97.5% copper solubilization occurred in presence of 10(-3) M multi-heavy metals on fifth day at 55 degrees C and pH 2.5. Chemical analyses were carried out by inductively coupled plasma spectroscopy (ICP) for metal absorption. The selected highly potential isolate (ATh-14) showed maximum adsorption of Ag 73%, followed by Pb 35%, Zn 34%, As 19%, Ni 15% and Cr 9% in chalcopyrite.

  7. Heavy metal pollution in topsoils near a cement plant: the role of organic matter and distance to the source to predict total and hcl-extracted heavy metal concentrations.

    Science.gov (United States)

    Bermudez, Gonzalo M A; Moreno, Mónica; Invernizzi, Rodrigo; Plá, Rita; Pignata, María Luisa

    2010-01-01

    Heavy metal and trace element concentrations were examined in topsoils to evaluate a cement plant and an industrial waste incinerator as pollution sources. As, Ba, Ca, Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Na, Nd, Rb, Sb, Sc, Se, Sm, Ta, Tb, Th, U, Yb and Zn were measured by Neutron Activation Analysis (NAA), and Co, Cu, Fe, Ni, Pb and Zn by a 0.5M-hydrochloric extraction technique using an Atomic Absorption Spectrophotometer (AAS). The Cr total concentration and HCl-extracted Co and Mn were possibly related to wind transportation from an industrial area in the north of Córdoba city (Argentina). Cu, Pb and Zn in partial HCl extraction were influenced by the cement plant and the industrial area in the north of Córdoba city. The mean total Ba concentration was above the residential and agricultural land use limits stated in national and international legislation and was related to the distance to the cement plant. The concentrations of HCl-extracted heavy metals could be predicted by the organic matter percentage and the distance to the cement plant (with R(2) values of 0.50-0.74). The Ca total concentration was seen to have little influence whereas the organic matter percentage strongly affected HCl-extracted heavy metals according to the correlation analysis and multiple regression models. According to soil quality guidelines for environmental health, the human and wildlife populations in Yocsina might be experiencing toxic Ba and Cr effects.

  8. Three-way principal component analysis as a tool to evaluate the chemical stability of metal bearing residues from wastewater treatment by the ferrite process.

    Science.gov (United States)

    Pardo, Rafael; Vega, Marisol; Barrado, Enrique; Castrillejo, Yolanda; Sánchez, Isabel

    2013-11-15

    The chemical fractionation patterns of eight metals (Cd, Co, Cu, Cr, Mn, Ni, Pb and Zn) have been determined in 27 metal-bearing residues by using the BCR sequential extraction procedure. The residues were generated as by-products during the optimization of a semi-continuous reactor for metal removal from wastewater based on ferrite synthesis by co-precipitation. The three-dimensional X dataset (samples×metals×fractions) obtained by applying the BCR procedure has been analyzed by multivariate methods: matrix augmentation (MA-PCA) and three-way principal component analysis, 3-PCA (PARAFAC and Tucker3 models). MA-PCA and PARAFAC methods led to two-factor models giving a satisfactory but incomplete picture of the metal fractionation patterns, but the Tucker3 [2,1,2] model allowed to simultaneously describe both the 'pseudo-total' (acid-soluble) contents and the chemical fractionation by means of two non-null interactions g111 and g212 which explain 53.5% and 18.0% of the total variance, respectively. The A-mode loadings of the g212 interaction showed the close relationship between the magnetic character of the solid residues, i.e. the crystalline structure, and the chemical fractionation patterns of the metals resulting from the application of the BCR sequential extraction procedure.

  9. Removal of ethylene from air stream by adsorption and plasma-catalytic oxidation using silver-based bimetallic catalysts supported on zeolite.

    Science.gov (United States)

    Trinh, Quang Hung; Lee, Sang Baek; Mok, Young Sun

    2015-03-21

    Dynamic adsorption of ethylene on 13X zeolite-supported Ag and Ag-M(x)O(y) (M: Co, Cu, Mn, and Fe), and plasma-catalytic oxidation of the adsorbed ethylene were investigated. The experimental results showed that the incorporation of Ag into zeolite afforded a marked enhancement in the adsorptivity for ethylene. The addition of transition metal oxides was found to have a positive influence on the ethylene adsorption, except Fe(x)O(y). The presence of the additional metal oxides, however, appeared to somewhat interrupt the diffusion of ozone into the zeolite micro-pores, leading to a decrease in the plasma-catalytic oxidation efficiency of the ethylene adsorbed there. Among the second additional metal oxides, Fe(x)O(y) was able to reduce the emission of ozone during the plasma-catalytic oxidation stage while keeping a high effectiveness for the oxidative removal of the adsorbed ethylene. The periodical treatment consisting of adsorption followed by plasma-catalytic oxidation may be a promising energy-efficient ethylene abatement method. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Leaching of metals from copper smelter flue dust (Mufulira, Zambian Copperbelt)

    DEFF Research Database (Denmark)

    Vítková, Martina; Ettler, Vojtěch; Hyks, Jiri

    2011-01-01

    ) 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...... 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......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...

  11. Synthesis, spectral, computational and thermal analysis studies of metalloceftriaxone antibiotic

    Science.gov (United States)

    Masoud, Mamdouh S.; Ali, Alaa E.; Elasala, Gehan S.

    2015-03-01

    Binary ceftriaxone metal complexes of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II) and six mixed metals complexes of (Fe, Cu), (Fe, Co), (Co, Ni), (Co, Cu), (Ni, Cu) and (Fe, Ni) were synthesized and characterized by elemental analysis, IR, electronic spectra, magnetic susceptibility and ESR spectra. The studies proved that the ligand has different combination modes and all complexes were of octahedral geometry. Molecular modeling techniques and quantum chemical methods have been performed for ceftriaxone to calculate charges, bond lengths, bond angles, dihedral angles, electronegativity (χ), chemical potential (μ), global hardness (η), softness (σ) and the electrophilicity index (ω). The thermal decomposition of the prepared metals complexes was studied by TGA, DTA and DSC techniques. The kinetic parameters and the reaction orders were estimated. The thermal decomposition of all the complexes ended with the formation of metal oxides and carbon residue as a final product except in case of Hg complex, sublimation occurs at the temperature range 297.7-413.7 °C so, only carbon residue was produced during thermal decomposition. The geometries of complexes may be altered from Oh to Td during the thermal decomposition steps. Decomposition mechanisms were suggested.

  12. Seasonal study of contamination by metal in water and sediment in a sub-basin in the southeast of Brazil

    Directory of Open Access Journals (Sweden)

    WAC. Chiba

    Full Text Available The spatial and temporal occurrence of heavy metals (Al, Cd, Pb, Zn, Cr, Co, Cu, Fe, Mn and Ni in water and sediment samples was investigated in a sub-basin in the southeast of Brazil (São Carlos, SP. All samples were analysed using the USEPA adapted metal method and processed in an atomic absorption spectrophotometer. The discriminant analysis demonstrated that there are significant seasonal differences of metal distribution in the water data, but there are no differences to sediment. The basin studied has high levels of contamination by toxic metals in superficial water and sediment. The superficial water, in the rainy season, presented high levels of Cr, Ni, Pb and Cd, while in the dry season it presented high levels of Zn and Ni. The Principal Component Analysis demonstrated that the season has a huge influence on the levels, types and distribution of metals found in water. The source of contamination was probably diffuse, due to products such as batteries and fluorescent lamps, whose dump discharge can contaminate the bodies of water in the region in the rainy season. Due to fires from the harvest of sugar cane, high levels of Zn were found into the environment, in the dry season.

  13. 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

    Energy Technology Data Exchange (ETDEWEB)

    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)

  14. Chemical composition of selected Saudi medicinal plants

    Directory of Open Access Journals (Sweden)

    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.

  15. Sedimentary input of trace metals from the Chukchi Shelf

    Science.gov (United States)

    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.

  16. Effect of Cu{sup 2+} (S= 1/2 ) substitution on the antiferromagnetic ordered phases Co{sub 2}(OH)XO{sub 4} (X = P, As)

    Energy Technology Data Exchange (ETDEWEB)

    Pedro, Imanol de; Rojo, Jose M; Rojo, Teofilo [Departamento de Quimica Inorganica Facultad de Ciencia y TecnologIa, Universidad del Pais Vasco, 48080 Bilbao (Spain); Rodriguez Fernandez, Jesus, E-mail: depedrovm@unican.e [CITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander (Spain)

    2010-01-01

    The isostructural Co{sub 1.5}Cu{sub 0.5}(OH)(XO{sub 4}) (X = P, As) phases have been prepared from hydrothermal synthesis and characterized from powder X-ray diffraction. The structure consists of a three-dimensional framework in which M(1)O{sub 5}-trigonal bipyramid dimers and M(2)O{sub 6}-octahedral chains M = (Cu and Co) are simultaneously present. Magnetization measurements of Co{sub 1.5}Cu{sub 0.5}(OH)(PO{sub 4}) show the presence of one maxima at ca. 60 K attributed to a three-dimensional antiferromagnetic ordering. This behaviour was confirmed from the ac measurements. Below T{sub N}, a significant irreversibility appears in ZFC-FC measurements suggesting the presence of some ferromagnetic contributions. When PO{sub 4}{sup 3-} is substituted by AsO{sub 4}{sup 3-} anions, the irreversibility exhibited for the Co-Cu hydroxi-phosphate disappears showing a broad maximum around 44 K accompanied by a large decrease below this temperature.

  17. Research progress in transition metal oxides based on conversion mechanism as the anode materials for Li-ion batteries%转化型过渡金属氧化物负极材料的研究进展

    Institute of Scientific and Technical Information of China (English)

    曾晖; 王强; 王康平; 宋金保

    2014-01-01

    综述了近年来过渡金属氧化物 MxOy (M= Fe,Ni,Co,Cu)作为锂离子电池负极材料在锂离子电池中的应用。我们分别将过渡金属氧化物的两种形态(粉体和薄膜),与电化学性能之间的关联性进行了总结和探讨,并对过渡金属氧化物作为锂离子电池负极材料的发展前景进行了展望。%In recent years,research progress on transition metal oxides MxOy(M= Fe,Ni,Co,Cu) as anode materials for lithium ion batteries was reviewed.Emphasis is placed on the generaliza-tion and discussion of the relationship between the two status (powder and films )and electro-chemical properties of transition metal oxides materials.And the development prospect of transi-tion metal oxides as anode materials is also reviewed.

  18. Phytoremediating a copper mine soil with Brassica juncea L., compost and biochar.

    Science.gov (United States)

    Rodríguez-Vila, Alfonso; Covelo, Emma F; Forján, Rubén; Asensio, Verónica

    2014-10-01

    The soils at a depleted copper mine in Touro (Galicia, Spain) are chemically degraded. In order to determine the effect of amendments and vegetation on the chemical characteristics of a mine soil and on the plant uptake of metals, a greenhouse experiment was carried out for 3 months. A settling pond soil was amended with different percentages of a compost and biochar mixture and vegetated with Brassica juncea L. The results showed that the untreated settling pond soil was polluted by Cu. Amendments and planting mustards decreased the pseudototal concentration of this metal, reduced the extreme soil acidity and increased the soil concentrations of C and TN. Both treatments also decreased the CaCl2-extractable Co, Cu and Ni concentrations. However, the amendments increased the pseudototal concentration of Zn in the soil, provided by the compost that was used. The results also showed that mustards extracted Ni efficiently from soils, suggesting that B. juncea L. is a good phytoextractor of Ni in mine soils.

  19. Morphology and electronic properties of Co nanorods on Cu(110)-p(2 x 3)N

    Energy Technology Data Exchange (ETDEWEB)

    Wedekind, Sebastian; Oka, Hirofumi; Rodary, Guillemin; Sander, Dirk; Kirschner, Juergen [Max-Planck-Institut fuer Mikrostrukturphysik, Halle (Germany); Donati, Fabio [Max-Planck-Institut fuer Mikrostrukturphysik, Halle (Germany); NEMAS, Politecnico di Milano, Milano (Italy)

    2010-07-01

    Copper nitride systems are of high current interest in nanoscience as they offer a venue towards decoupling the electronic properties of nanostructures or adatoms from those of the substrate. We have prepared a Cu(110)-p(2 x 3) (Cu{sub 3}N) substrate by N-ion bombardment (600 eV, 30 min, 550 K) of clean Cu(110). Deposition of Co leads to the formation of several ten nm long Co wires, extending along. Our scanning tunneling microscopy and spectroscopy studies at 8 K reveal the positions of all atoms within the rectangular surface unit cell, where we measure unit vectors of 1.094 and 0.502 nm for the Cu{sub 3}N structure. Surprisingly, spectroscopy on clean Cu{sub 3}N and on Co nanowires on Cu{sub 3}N shows very similar results. No special spectroscopic features are identified near the Fermi energy, but peaks at +1.8 and +3.5 eV of presently unknown electronic character of the unoccupied sample states are observed for both Cu{sub 3}N and Co/Cu{sub 3}N. This suggests a rather strong electronic coupling between substrate and nanowire, questioning the electronic decoupling between this copper nitride system and nanostructures deposited on top.

  20. Lanthanide complexes of tritopic bis(hydrazone) ligands: single-molecule magnet behavior in a linear Dy(III)3 complex.

    Science.gov (United States)

    Anwar, Muhammad U; Tandon, Santokh S; Dawe, Louise N; Habib, Fatemah; Murugesu, Muralee; Thompson, Laurence K

    2012-01-16

    Tritopic pyridinebis(hydrazone)-based ligands typically produce square M(9) [3 × 3] grid complexes with first-row transition-metal ions (e.g., M = Mn, Fe, Co, Cu, Zn), but with larger lanthanide ions, such coordination motifs are not produced, and instead linear trinuclear complexes appear to be a preferred option. The reaction of 2pomp [derived from pyridine-2,6-bis(hydrazone) and 2-acetylpyridine] with La(III), Gd(III), and Dy(III) salts produces helical linear trinuclear [Ln(3)(2pomp)(2)]-based complexes, where each metal ion occupies one of the three tridentate ligand pockets. Two ligands encompass the three metal ions, and internal connections between metal ions occur through μ-O(hydrazone) bridges. Coligands include benzoate, nitrate, and N,N-dimethylformamide. The linear Dy(III)(3) complex exhibits single-molecule magnet behavior, demonstrated through alternating-current susceptibility measurements. Slow thermal magnetic relaxation was detected in an external field of 1800 Oe, where quantum-tunneling effects were suppressed (U(eff) = 14 K).

  1. Effects of alloying elements on elastic properties of Al by first-principles calculations

    Directory of Open Access Journals (Sweden)

    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.

  2. Effect of Zr, V, Nb, Mo, and Ta substitutions on magnetic properties and microstructure of melt-spun SmCo5 magnets.

    Science.gov (United States)

    Fukuzaki, Tomokazu; Iwane, Hiroaki; Abe, Kazutomo; Doi, Toshihiro; Tamura, Ryuji; Oikawa, Tadaaki

    2014-05-07

    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.

  3. Determination of toxic metals, trace and essentials, and macronutrients in Sarpa salpa and Chelon labrosus: risk assessment for the consumers.

    Science.gov (United States)

    Afonso, Aridani; Gutiérrez, Angel J; Lozano, Gonzalo; González-Weller, Dailos; Rubio, Carmen; Caballero, José M; Hardisson, Arturo; Revert, Consuelo

    2017-04-01

    Due to increased environmental pollution, monitoring of contaminants in the environment and marine organisms is a fundamental tool for assessing the existence of risk from their consumption to human health. The levels of toxic heavy metals (Cd, Pb, and Al), trace and essential metals (B, Ba, Co, Cu, Cr, Fe, Li, Mn, Mo, Ni, Sr, V, and Zn), and macronutrients (Ca, K, Mg, Na) in two species of fish for human consumption were quantified in the present study. Eighty samples of muscle tissue and 80 samples of liver tissue belonging to two species of Osteichthyes fish; Sarpa salpa and Chelon labrosus were analyzed. The studied specimens were caught on the northern coast of Gran Canaria (Canary Islands) with fishing rods. As they caught from the shore, they are suitable samples for assessing the toxic levels of representative species caught by local amateur fishermen. The results show that both species are fit for human consumption since they have toxic levels of heavy metals (Cd, Pb, and Al) which are below the maximum established levels; however, the toxic levels of the liver samples are several orders of magnitude higher than the muscle samples, so we discourage their regular consumption. The risk assessment indicated that the two species of fish are safe for the average consumer; however, if the livers of these species are consumed, there could be risks because they exceed the PTWI for Pb and the TWI for Cd.

  4. Influence of taxa, trophic level, and location on bioaccumulation of toxic metals in bird's feathers: a preliminary biomonitoring study using multiple bird species from Pakistan.

    Science.gov (United States)

    Abbasi, Naeem Akhtar; Jaspers, Veerle Leontina Bernard; Chaudhry, Muhammad Jamshed Iqbal; Ali, Sakhawat; Malik, Riffat Naseem

    2015-02-01

    Increasing concentrations of heavy metals in the environment and their effects on ecosystems and biota is still an imminent threat, particularly in developing parts of the globe. The aim of the present study was to screen the heavy metal concentrations in multiple bird species across Pakistan and to preliminary evaluate the influence of taxa, trophic level, and geographical location on heavy metal accumulation in various bird species. For this purpose, we measured the concentration of 9 heavy metals (Pb, Cd, Cr, Ni, Co, Cu, Fe, Zn and Mn) in feathers of 48 bird species from different localities in Pakistan. Species exhibited heterogeneous levels of heavy metals in feathers with marked inter and intra specific variations. Mean concentrations of studied metals in feathers followed the trend Fe>Zn>Cu>Pb>Mn>Cr>Ni>Co>Cd. Species belonging to closely related taxa (families) showed comparable metal concentrations in their feathers, inferring potential phylogenetic similarities in metal exposure or accumulation. In general, concentrations of metals were greatest in carnivorous species followed by omnivorous and insectivorous birds, and granivores showing minimal levels (pmetals varied significantly between locations (ptoxic metal accumulation was also statistically corroborated through principal component analysis (PCA). This study highlights that despite restricted emissions, heavy metals persist in the local environment and may pose elevated risks for the studied bird species in Pakistan. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Trace element structure of the most widespread plants of genus PulmonariaFNx01

    Directory of Open Access Journals (Sweden)

    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.

  6. Insights into solid phase characteristics and release of heavy metals and arsenic from industrial sludge via combined chemical, mineralogical, and microanalysis.

    Science.gov (United States)

    Dung, Tran Thi Thu; Golreihan, Asefeh; Vassilieva, Elvira; Phung, Nguyen Ky; Cappuyns, Valérie; Swennen, Rudy

    2015-02-01

    This study investigates the solid phase characteristics and release of heavy metals (i.e., Cd, Co, Cu, Cr, Mo, Ni, Pb, and Zn) and arsenic (As) from sludge samples derived from industrial wastewater treatment plants. The emphasis is determining the influence of acidification on element mobilization based on a multidisciplinary approach that combines cascade and pHstat leaching tests with solid phase characterization through X-ray diffraction (XRD), field emission gun electron probe micro analysis (FEG-EPMA), and thermodynamic modeling (Visual MinteQ 3.0). Solid phase characterization and thermodynamic modeling results allow prediction of Ni and Zn leachabilities. FEG-EPMA is useful for direct solid phase characterization because it provides information on additional phases including specific element associations that cannot be detected by XRD analysis. Cascade and pHstat leaching test results indicate that disposal of improperly treated sludges at landfills may lead to extreme environmental risks due to high leachable concentrations of Zn, Ni, Cu, Cr, and Pb. However, high leachabilities under acid conditions of Ni and Zn as observed from pHstat leaching test results may provide a potential opportunity for acid extraction recovery of Ni and Zn from such sludges.

  7. Induced magnetization spiral in a nonmagnetic metal sandwiched between two ferromagnets

    Energy Technology Data Exchange (ETDEWEB)

    Mathon, J.; Umerski, A.; Villeret, Murielle E-mail: m.a.villeret@city.ac.uk; Muniz, R.B.; Edwards, D.M

    2000-07-01

    Calculation of the magnetic moment induced in a non-magnetic metal, sandwiched between two ferromagnets with magnetizations at an arbitrary angle, is reported. It is found that the induced magnetization rotates along a complex three-dimensional spiral and can undergo many complete 360 deg. rotations. A simple free-electron model is used to derive an analytic formula for the twist angle phi inside the spacer. This demonstrates that, contrary to the behavior of magnetization inside a domain wall in a ferromagnet, phi varies non-uniformly inside the spacer and exhibits plateaus of almost constant rotation separated by regions of sharp rotations by large angles. The calculation is extended to the case of a realistic Co/Cu/Co(0 0 1) trilayer described by s, p, d tight-binding bands fitted to an ab initio band structure. An analytic formula for the components of the induced moment (and hence, for phi) is derived using the stationary phase approximation. Its validity is tested against a fully numerical calculation using the same band structure. The formula shows that the components of the induced magnetization each oscillate with a predominant short period determined by the Cu Fermi surface neck extrema. The twist angle again displays the same remarkable behavior as in the free-electron model and depends in an intricate manner on geometrical properties of the spacer Fermi surface as well as on the degree of confinement of carriers in the spacer quantum well.

  8. Preliminary studies on trace element contamination in dumping sites of municipal wastes in India and Vietnam

    Science.gov (United States)

    Agusa, T.; Kunito, T.; Nakashima, E.; Minh, T. B.; Tanabe, S.; Subramanian, A.; Viet, P. H.

    2003-05-01

    The disposal of wastes in dumping sites has increasingly caused concem about adverse health effects on the populations living nearby. However, no investigation has been conducted yet on contamination in dumping sites of municipal wastes in Asian developing countries. In this study, concentrations of 11 trace elements (V, Cr, Mn, Co, Cu, Zn, Mo, Ag, Cd, Sb and Pb) were detennined in scalp hair from the population living nearby and in soil from dumping sites and control sites of India and Vietnam. Soil samples in dumping site in India showed significantly higher concentrations of some trace elements than soils in control site, whereas this trend was not notable in Vietnam. This is probably due to the fact that the wastes were covered with the soil in the dumping site of Vietnam. Cadmium concentrations in some hair samples of people living near dumping site in India and Vietnam exceeded the level associated with learning disorder in children. Levels of most of the trace elements in hair were significantly higher in dumping site than those in control site in India and Vietnam, suggesting direct or indirect exposure to those elements from dumping wastes. To our knowledge, this is the first study of trace element contamination in dumping sites in India and Vietnam.

  9. Evaluation of metal enrichment and trophic status on the basis of biogeochemical analysis of shelf sediments of the southeastern Arabian Sea, India

    Science.gov (United States)

    Cheriyan, Eldhose; Sreekanth, Athira; Mrudulrag, S. K.; Sujatha, C. H.

    2015-10-01

    The present study investigated the distribution of environmentally relevant metals and organic matter in the shelf sediments of the southeastern Arabian Sea using biogeochemical proxies for the assessment of environmental quality and trophic status. The distribution of metals in the study site followed the order: Fe>Mg>Pb>Ni>Mn>Co>Cu>Zn>Cd. High biological productivity associated with upwelling leads to significant accumulation of Cd higher than crustal abundance in the shelf region. The enrichment factor (EF) of metals demonstrate enrichment of Pb and Co which suggests the anthropogenic influence and not redox conditions. The sediment quality guidelines (SQG) in comparison with metal concentration revealed adverse effects, possibly occurring in marine benthic species. The spatial trend of metal enrichment along transects is appreciably controlled by the adsorption to fine grained sediments. The multivariate statistical analyses, such as correlations and principal component analysis (PCA) clearly indicated the control of texture, association of clay minerals in the degree of trace metal (Cd, Pb, Ni and Co) contamination from anthropogenic as well as natural sources. Low levels of Zn, preferably display scavenging by Fe/Mn metal oxides. Biochemical descriptors in sediments indicated meso-oligotrophic conditions prevailing in the summer monsoon. The ratios among various biogeochemical parameters such as total organic carbon/total nitrogen (TOC/TNcontamination from a potential fishery zone of Indian exclusive economic zone.

  10. Trace metal analysis in sea grasses from Mexican Caribbean Coast by particle induced X-ray emission (PIXE)

    Energy Technology Data Exchange (ETDEWEB)

    Solis, C.; Issac O, K. [Instituto de Fisica, Departamento de Fisica Experimental, UNAM, Apartado Postal 20-364, 01000 Mexico D. F. (Mexico); Martinez, A.; Lavoisier, E.; Martinez, M. A. [Instituto de Investigaciones en Materiales, UNAM, Ciudad Universitaria, 04510 Mexico D. F. (Mexico)

    2008-02-15

    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)

  11. Direct trace-elemental analysis of urine samples by laser ablation-inductively coupled plasma mass spectrometry after sample deposition on clinical filter papers.

    Science.gov (United States)

    Aramendía, Maite; Rello, Luis; Vanhaecke, Frank; Resano, Martín

    2012-10-16

    Collection of biological fluids on clinical filter papers shows important advantages from a logistic point of view, although analysis of these specimens is far from straightforward. Concerning urine analysis, and particularly when direct trace elemental analysis by laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) is aimed at, several problems arise, such as lack of sensitivity or different distribution of the analytes on the filter paper, rendering obtaining reliable quantitative results quite difficult. In this paper, a novel approach for urine collection is proposed, which circumvents many of these problems. This methodology consists on the use of precut filter paper discs where large amounts of sample can be retained upon a single deposition. This provides higher amounts of the target analytes and, thus, sufficient sensitivity, and allows addition of an adequate internal standard at the clinical lab prior to analysis, therefore making it suitable for a strategy based on unsupervised sample collection and ulterior analysis at referral centers. On the basis of this sampling methodology, an analytical method was developed for the direct determination of several elements in urine (Be, Bi, Cd, Co, Cu, Ni, Sb, Sn, Tl, Pb, and V) at the low μg L(-1) level by means of LA-ICPMS. The method developed provides good results in terms of accuracy and LODs (≤1 μg L(-1) for most of the analytes tested), with a precision in the range of 15%, fit-for-purpose for clinical control analysis.

  12. Acid mine drainage treatment using by-products from quicklime manufacturing as neutralization chemicals.

    Science.gov (United States)

    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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Evaluation of tissue metal and trace element content in a rat model of non-alcoholic fatty liver disease using ICP-DRC-MS.

    Science.gov (United States)

    Gatiatulina, Eugenia R; Popova, Elizaveta V; Polyakova, Valentina S; Skalnaya, Anastasia A; Agletdinov, Eduard F; Nikonorov, Alexandr A; Skalny, Anatoly V; Tinkov, Alexey A

    2017-01-01

    The primary objective of the study was to assess the level of metals and trace elements in liver, serum, and hair of rats with diet-induced non-alcoholic fatty liver disease (NAFLD) using inductively coupled plasma dynamic reaction cell mass spectrometer (ICP-DRC-MS). 56 female 3-months-old Wistar rats divided into two equal groups were fed either standard (10% calories from fat) or high-fat high-carbohydrate diet (60% calories from fat in chow and 10% sucrose solution) for 6 weeks. Serum was examined for insulin resistance markers, lipid profile, and alanine aminotransferase (ALT) activity. Liver histology was assessed after hematoxylin and eosin staining. Metal and trace element concentrations were assessed by means of ICP-DRC-MS. Overfed animals were characterized by higher values of morphometric parameters. Liver examination revealed large and small droplet steatosis, hepatocyte ballooning and necrosis, being characteristic for NAFLD. Animals with NAFLD were characterized by insulin resistance, atherogenic changes of lipid profile and increased ALT activity. Significantly decreased hepatic Co, Cu, I, Li, Mn, Se, Zn levels were observed in rats with NAFLD. At the same time, only hepatic Mn and Se levels remained decreased after adjustment for total protein. Overfed animals were characterized by significantly lower I, Li, and Mn levels in blood serum, whereas concentration of Co, Se, V, and Sr exceeded the control values. In general, the results of the study demonstrate that NAFLD significantly affects metal and trace element status in experimental animals.

  14. Immobilized copper(II) macrocyclic complex on MWCNTs with antibacterial activity

    Science.gov (United States)

    Tarlani, Aliakbar; Narimani, Khashayar; Mohammadipanah, Fatemeh; Hamedi, Javad; Tahermansouri, Hasan; Amini, Mostafa M.

    2015-06-01

    In a new approach, a copper(II) tetraaza macrocyclic complex (CuTAM) was covalently bonded on modified multi-walled carbon nanotubes (MWCNTs). To achieve this purpose, MWCNTs were converted to MWCNT-COCl and then reacted to NH groups of TAM ligand. The prepared material was characterized by Fourier Transform Infrared (FT-IR), X-ray diffraction (XRD), Raman spectroscopy, thermal gravimetric analysis (TGA), and FESEM (field emission scanning electron microscopy). FT-IR and TGA demonstrated the presence of the organic moieties, and XRD proved that the structure of MWCNTs remained intact during the three modification steps. An increase in the ID/IG ratio in Raman spectra confirmed the surface modifications. Finally, the samples were subjected to an antibacterial assessment to compare their biological activity. The antibacterial test showed that the grafted complex on the surface of the nanotube (MWCNT-CO-CuTAM) has higher antibacterial activity against Bacillus subtilis ATCC 6633 than the MWCNT-COOH and CuTAM with 1000 and 2000 μg/mL.

  15. Evaluation of the ecological effects of heavy metals on the assemblages of benthic foraminifera of the canals of Aveiro (Portugal)

    Science.gov (United States)

    Martins, V.; da Silva, E. Ferreira; Sequeira, C.; Rocha, F.; Duarte, A. C.

    2010-04-01

    Aveiro is a town with 80,000 inhabitants situated in the central west coast of Portugal. It is located at the centre of the Ria de Aveiro, a coastal lagoon that functions as a multi-estuarine area. This town is crossed by several canals which are connected with lagoon channels through canal locks. The operation of the canal locks influences the hydro dynamism in Aveiro's canal and this and other human activities have left a sedimentary record. The study of these records was based on the sediments grain size and composition, mineralogy (by XRD techniques), geochemical (by ICP-MS), total organic carbon (TOC), and microfaunal (benthic foraminifera) content in 15 grab-samples collected in 2006 in Aveiro's canal. The total elemental concentrations evaluated by total digestion of the sediment fraction canals, related to legacies of past industrial activities. These "hot spots" have, for instance, higher available concentrations of Al, Cd, Co, Cu, Fe, Pb, Mn and Zn (evaluated by sequential chemical extractions) and are located in Paraíso, Alboi, Botirões and Cojo Canals, at sites where the sediments are finer and richer in TOC. Abiotic and biotic variables submitted to principal component analysis and cluster analysis highlights the hydrodynamics and human effects on the system and the negative influence of pollutants on the benthic organisms (foraminifera).

  16. Possible unconventional superconductivity in substituted BaFe2As2 revealed by magnetic pair-breaking studies

    Science.gov (United States)

    Rosa, P. F. S.; Adriano, C.; Garitezi, T. M.; Piva, M. M.; Mydeen, K.; Grant, T.; Fisk, Z.; Nicklas, M.; Urbano, R. R.; Fernandes, R. M.; Pagliuso, P. G.

    2014-01-01

    The possible existence of a sign-changing gap symmetry in BaFe2As2-derived superconductors (SC) has been an exciting topic of research in the last few years. To further investigate this subject we combine Electron Spin Resonance (ESR) and pressure-dependent transport measurements to investigate magnetic pair-breaking effects on BaFe1.9M0.1As2 (M = Mn, Co, Cu, and Ni) single crystals. An ESR signal, indicative of the presence of localized magnetic moments, is observed only for M = Cu and Mn compounds, which display very low SC transition temperature (Tc) and no SC, respectively. From the ESR analysis assuming the absence of bottleneck effects, the microscopic parameters are extracted to show that this reduction of Tc cannot be accounted by the Abrikosov-Gorkov pair-breaking expression for a sign-preserving gap function. Our results reveal an unconventional spin- and pressure-dependent pair-breaking effect and impose strong constraints on the pairing symmetry of these materials. PMID:25176407

  17. Phytoremediation trials on metal- and arsenic-contaminated pyrite wastes (Torviscosa, Italy)

    Energy Technology Data Exchange (ETDEWEB)

    Vamerali, Teofilo [Department of Environmental Sciences, University of Parma, Viale G.P. Usberti 11/A, 43100 Parma (Italy)], E-mail: teofilo.vamerali@unipd.it; Bandiera, Marianna; Coletto, Lucia; Zanetti, Federica [Department of Environmental Agronomy and Crop Sciences, University of Padova, Viale dell' Universita 16, 35020 Legnaro - Padova (Italy); Dickinson, Nicholas M. [Faculty of Science, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF (United Kingdom); Mosca, Giuliano [Department of Environmental Agronomy and Crop Sciences, University of Padova, Viale dell' Universita 16, 35020 Legnaro - Padova (Italy)

    2009-03-15

    At a site in Udine, Italy, a 0.7 m layer of As, Co, Cu, Pb and Zn contaminated wastes derived from mineral roasting for sulphur extraction had been covered with an unpolluted 0.15 m layer of gravelly soil. This study investigates whether woody biomass phytoremediation is a realistic management option. Comparing ploughing and subsoiling (0.35 m depth), the growth of Populus and Salix and trace element uptake were investigated in both pot and field trials. Species differences were marginal and species selection was not critical. Impaired above-ground productivity and low translocation of trace elements showed that bioavailable contaminant stripping was not feasible. The most significant finding was of coarse and fine roots proliferation in surface layers that provided a significant sink for trace elements. We conclude that phytostabilisation and effective immobilisation of metals and As could be achieved at the site by soil amelioration combined with woody species establishment. Confidence to achieve a long-term and sustainable remediation requires a more complete quantification of root dynamics and a better understanding of rhizosphere processes. - In As- and metal-contaminated pyrite wastes, contaminant stripping is not feasible, and root foraging and quantification of root dynamics holds the key to stabilisation in woody species.

  18. Coexistence of localization and superconductivity in underdoped BSCCO: Are the Cooper pairs formed by spatially localized carriers?

    Science.gov (United States)

    Beschoten, B.; Güntherodt, G.; Quitmann, C.; Ma, Jian; Kelley, R. J.; Onellion, M.; Almeras, P.; Berger, H.; Margaritondo, H.

    1998-03-01

    In underdoped Bi_2Sr_2CaCu_2Oy we relate changes in the electronic structure seen in angle-resolved photoemission (ARPES) to changes in the electronic transport. The substitution of Pr for Ca or Co for Cu induces potential disorder leading to spatial localization of electronic states near the Fermi level for T>T_c. This indicates that Cooper pairs are formed by spatially localized electronic states. An anisotropic one-band model is given suggesting that localization seen in transport (ρ and μ(T)=R_H(T)/ρ(T)) for T>Tc can either be isotropic in k-space as for Co/Cu doping or anisotropic as for Pr/Ca doping. Spectroscopic evidence for this anisotropy is given by ARPES. Localization seen in ρ and μ, respectively, correlates with a supression of the band dispersion of electronic states along the symmetry directions in k-space from (0,0) to (0,π) and to (π,π). Supported by DFG/SFB 341, U.S. NSF.

  19. Simultaneous analysis 26 mineral element contents from highly consumed cultured chicken overexposed to arsenic trioxide by inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    He, Ying; Sun, Bonan; Li, Siwen; Sun, Xiao; Guo, Ying; Zhao, Hongjing; Wang, Yu; Jiang, Guangshun; Xing, Mingwei

    2016-11-01

    This study assessed the impacts of dietary arsenic trioxide (As2O3) on 26 mineral element contents in the liver and kidney of chicken. A total of 100 male Hy-line cocks were randomly divided into 2 groups (50 chickens in each group), including an arsenic-treated group (basic diet supplemented with As2O3 at 30 mg/kg) and a control group (basal diet). The feeding experiment lasted for 90 days and the experimental animals were given free access to feed and water. We determined 26 mineral elements in the liver and kidney by inductively coupled plasma mass spectrometry (ICP-MS). The results showed that nine element levels (Al, Mn, Co, Cu, Zn, Se, Cd, Ba, and Pb) were significantly decreased (P chickens exposed to As2O3 compared to the control chickens where three element levels (Ni, As, and Hg) increased significantly (P chickens exposed to As2O3 compared to the control chickens where four element levels (Mo, As, Cd, and Hg) increased significantly (P chicken, and the effects vary from organ to organ. The aim of this study is to provide references for further study of heavy metal poisoning by detecting the contents of minerals induced by arsenic in chicken.

  20. Assessment of background levels of trace metals in water and soil from a remote region of Himalaya.

    Science.gov (United States)

    Shah, Munir H; Iqbal, Javed; Shaheen, Nazia; Khan, Nadeem; Choudhary, Muhammad Aziz; Akhter, Gulraiz

    2012-03-01

    Selected trace metals were estimated by atomic absorption spectrometry in the water and soil samples collected from the remote region of Himalaya. The soil samples were analysed for soluble and acid extractable fraction of trace metals. In water samples, Ca, Na, Mg and K emerged as dominant contributors, whereas, Ca, Na, K, Mg, Fe and Pb were estimated at comparatively higher levels in the water extract of the soil. In case of acid extract of the soil samples, Ca, K, Fe, Mg, Mn and Na were found at elevated concentrations. Based on mean levels of the metals, following decreasing concentration order was observed in water samples: Ca > Na > Mg > K > Pb > Co > Cu > Zn > Mn > Cr > Fe > Cd > Li, however, in the acid extract of the soil, following order was noted: Ca > K > Fe > Mg > Mn > Na > Pb > Zn > Cr > Li > Cu > Co > Cd. The correlation study revealed appreciably diverse mutual relationships of trace metals in the water and soil samples. The multivariate cluster analyses exhibited divergent apportionment of trace metals in water and soil samples. Among the trace metals, Cd, Pb, Li, Zn, Cr, Cu, Mn and Co exhibited extreme to significant anthropogenic enrichment in the soil samples, while the rest of the metals were mostly contributed by the natural processes.

  1. Local structure of nanosized tungstates revealed by evolutionary algorithm

    Energy Technology Data Exchange (ETDEWEB)

    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)

  2. Spectral, thermal and in vitro antimicrobial studies of cyclohexylamine- N-dithiocarbamate transition metal complexes

    Science.gov (United States)

    Mamba, Saul M.; Mishra, Ajay K.; Mamba, Bhekie B.; Njobeh, Patrik B.; Dutton, Mike F.; Fosso-Kankeu, Elvis

    2010-10-01

    Transition metal complexes of the type [M(L) 2] and those containing monodentate phosphines of the type [M(L) 2(PPh 3)] {M = Ni, Co, Cu and Zn; L = cyclohexylamine- N-dithiocarbamate; PPh 3 = triphenylphosphine} have been synthesized. The complexes were characterized using IR, UV-vis, NMR spectroscopy, and thermal analysis (TGA). The 1H NMR, 13C NMR and 31P NMR showed the expected signals for the dithiocarbamate and triphenylphosphine moieties. The spectral studies in all compounds revealed that the coordination of metals occurs via the sulphur atom of the dithiocarbamate ligand in a bidentate fashion. Thermal behavior of the complexes showed that the complexes were more stable than their parent ligands. The ligand moiety is lost in the first step and the rest of the organic moiety decomposes in the subsequent steps. Furthermore, the ligand and their metal complexes were screened in vitro for their antibacterial activity against Escherichia coli, Staphylococcus aureus, Salmonella typhi, Enterococcus faecalis, Pseudomonas aeruginosa and Bacillus cereus and antifungal activities against Aspergillus flavus, Aspergillus carbonarius, Aspergillus niger and Aspergillus fumigatus. The metal complexes exhibited higher antimicrobial activity than the parent ligands. Generally, the zinc complexes were effective against the growth of bacteria with Zn(L) 2 displaying broad spectrum bacteriocidal activity at concentrations of 50 μg/mL; and Ni(L) 2 was more effective against the growth of fungi at concentrations of 100-400 μg/mL under laboratory conditions.

  3. Leaching of Major and Minor Elements during the Transport and Storage of Coal Ash Obtained in Power Plant

    Directory of Open Access Journals (Sweden)

    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. Analysis of heavy metal sources in soil using kriging interpolation on principal components.

    Science.gov (United States)

    Ha, Hoehun; Olson, James R; Bian, Ling; Rogerson, Peter A

    2014-05-06

    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.

  5. A comparison of an optimised sequential extraction procedure and dilute acid leaching of elements in anoxic sediments, including the effects of oxidation on sediment metal partitioning.

    Science.gov (United States)

    Larner, Bronwyn L; Palmer, Anne S; Seen, Andrew J; Townsend, Ashley T

    2008-02-11

    The effect of oxidation of anoxic sediment upon the extraction of 13 elements (Cd, Sn, Sb, Pb, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As) using the optimised Community Bureau of Reference of the European Commission (BCR) sequential extraction procedure and a dilute acid partial extraction procedure (4h, 1 molL(-1) HCl) was investigated. Elements commonly associated with the sulfidic phase, Cd, Cu, Pb, Zn and Fe exhibited the most significant changes under the BCR sequential extraction procedure. Cd, Cu, Zn, and to a lesser extent Pb, were redistributed into the weak acid extractable fraction upon oxidation of the anoxic sediment and Fe was redistributed into the reducible fraction as expected, but an increase was also observed in the residual Fe. For the HCl partial extraction, sediments with moderate acid volatile sulfide (AVS) levels (1-100 micromolg(-1)) showed no significant difference in element partitioning following oxidation, whilst sediments containing high AVS levels (>100 micromolg(-1)) were significantly different with elevated concentrations of Cu and Sn noted in the partial extract following oxidation of the sediment. Comparison of the labile metals released using the BCR sequential extraction procedure (SigmaSteps 1-3) to labile metals extracted using the dilute HCl partial extraction showed that no method was consistently more aggressive than the other, with the HCl partial extraction extracting more Sn and Sb from the anoxic sediment than the BCR procedure, whilst the BCR procedure extracted more Cr, Co, Cu and As than the HCl extraction.

  6. Risk assessment of hazardous impacts on urbanization and industrialization activities based upon toxic substances

    Directory of Open Access Journals (Sweden)

    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.

  7. Concentration levels and spatial distribution of sulphur and metals in fine-grained sediments in western Finland

    Directory of Open Access Journals (Sweden)

    M. ÅSTRÖM

    2008-12-01

    Full Text Available On the coastal plains of Finland, widespread Holocene marine and lacustrine sediments have developed into acid sulphate soil as a result of extensive artificial drainage for agricultural purposes. This has caused a variety of environmental problems. The aim of this study was to determine the concentration levels and spatial distribution of sulphur, carbon and metals [titanium, vanadium, chromium, manganese (Mn, iron, cobalt (Co, nickel (Ni, copper (Cu, zinc (Zn] in these sediments, in order to increase the geochemical understanding of the parent materials from which acid sulphate soil develops. Sediment samples were collected at 317 sites from a depth of 1.5–3 m. While the sediments have high S (sulphide concentrations (median = 0.54% and thus a strong acidification potential, they carry transition metals mainly in smallsized silicates close to “background concentrations” far below contamination limits. The previously documented extensive release of Co, Cu, Mn, Ni and Zn from oxidised and acidified layers of these sediments (i.e. acid sulphate soil is thus not explained by anomalously high natural or anthropogenic metal concentrations of the soils/sediments, but by an inherent highly mobile metal pool. Spatial-distribution maps highlight areas of elevated S and Mn concentrations, where it is likely that ditching and subsequent oxidation will result in an exceptionally large release of protons and Mn respectively.;

  8. Geochemical evidences of the anthropogenic alteration of trace metal composition of the sediments of Chiricahueto marsh (SE Gulf of California)

    Energy Technology Data Exchange (ETDEWEB)

    Soto-Jimenez, M.; Paez-Osuna, F.; Ruiz-Fernandez, A.C

    2003-10-01

    Principal component analysis allowed separation of natural from anthropogenic origin metals. - Seven sediment cores (60-80 cm) were collected at Chiricahueto marsh, a salt marsh influenced by agrochemical, domestic and industrial effluents. The concentrations of Ag, Al, Cd, Co, Cu, Fe, Li, Mn, Pb, V and Zn were studied in the solid phase at each 1-cm section. The profiles of Ag, Cd, Cu, Mn, Ni, Pb and Zn showed a slight recent pollution in the site with enrichment and anthropogenic factors higher than unity; and correlation analysis indicated a direct association with organic carbon. Al, Co, Cr, Fe, Li, and V concentration profiles displayed a negative correlation with organic C and positive with mud content and no consistent enrichment at surface. Based on the principal component analysis and correlation analysis, two principal groups of metals were identified. The first group includes Al, Co, Cr, Fe and Li, that are derived predominantly from the weathering of parent materials in the local bedrock; and the second group include most of the metals, which were relatively enriched at surficial sediments, that are produced mainly by anthropogenic activities such as agriculture (Cd, Cu and Zn), sewage effluents (Ag, Cd, Cu, Ni, Pb and Zn) and in lesser extent atmospheric deposition (Cd and Pb)

  9. Induced magnetization spiral in a nonmagnetic metal sandwiched between two ferromagnets

    CERN Document Server

    Mathon, J; Villeret, M; Muniz, R B; Edwards, D M

    2000-01-01

    Calculation of the magnetic moment induced in a non-magnetic metal, sandwiched between two ferromagnets with magnetizations at an arbitrary angle, is reported. It is found that the induced magnetization rotates along a complex three-dimensional spiral and can undergo many complete 360 deg. rotations. A simple free-electron model is used to derive an analytic formula for the twist angle phi inside the spacer. This demonstrates that, contrary to the behavior of magnetization inside a domain wall in a ferromagnet, phi varies non-uniformly inside the spacer and exhibits plateaus of almost constant rotation separated by regions of sharp rotations by large angles. The calculation is extended to the case of a realistic Co/Cu/Co(0 0 1) trilayer described by s, p, d tight-binding bands fitted to an ab initio band structure. An analytic formula for the components of the induced moment (and hence, for phi) is derived using the stationary phase approximation. Its validity is tested against a fully numerical calculation u...

  10. Multi-elemental contamination and historic record in sediments from the Santos-Cubatao Estuarine System, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    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)

  11. Characterization, distribution, and risk assessment of heavy metals in agricultural soil and products around mining and smelting areas of Hezhang, China.

    Science.gov (United States)

    Briki, Meryem; Ji, Hongbing; Li, Cai; Ding, Huaijian; Gao, Yang

    2015-12-01

    Mining and smelting have been releasing huge amount of toxic substances into the environment. In the present study, agricultural soil and different agricultural products (potato, Chinese cabbage, garlic bolt, corn) were analyzed to examine the source, spatial distribution, and risk of 12 elements (As, Be, Bi, Cd, Co, Cr, Cu, Hg, Ni, Pb, Sb, and Zn) in agricultural soil near mine fields, smelting fields, and mountain field around Hezhang County, west of Guizhou Province, China. Multivariate statistical analysis indicated that in mining area, As, Bi, Cd, Cu, Hg, Pb, Sb, and Zn were generated from anthropogenic sources; in smelting area, As, Be, Cd, Co, Cu, Pb, Sb, and Zn were derived from anthropogenic sources through zinc smelting ceased in 2004. The enrichment factors (EFs) and ecological risk index (RI) of soil in mining area are the most harmful, showing extremely high enrichment and very high ecological risk of As, Bi, Cd, Cu, Hg, Pb, Sb, and Zn. Zinc is the most significant enriched in the smelting area; however, mountain area has a moderate enrichment and ecological risk and do not present any ecological risk. According to spatial distribution, the concentrations depend on the nearby mining and smelting activities. Transfer factors (TFs) in the smelting area and mountain are high, implying a threat for human consumption. Therefore, further studies should be carried out taking into account the harm of those heavy metals and potential negative health effects from the consumption of agricultural products in these circumstances.

  12. Desalination of Water Using ZVI (Fe0

    Directory of Open Access Journals (Sweden)

    David D. J. Antia

    2015-07-01

    Full Text Available Batch treatment of water (0.2 to 240 L using Fe0 (44,000–77,000 nm in a diffusion environment operated (at −8 to 25 °C using: (a no external energy; (b pressurized (<0.1 MPa air; (c pressurized (<0.1 MPa acidic gas (CO2; (d pressurized (<0.1 MPa anoxic gas (N2; (e pressurized (<0.1 MPa anoxic, acidic, reducing gas (H2 + CO + CO2 + CH4 + N2, reduces the salinity of water. Desalination costs increase with increasing NaCl removal. The cost of reducing water salinity from: (i 2.65 to 1.55 g·L−1 (over 1–24 h is $0.002–$0.026 m−3; (ii 38.6 to 0.55 g·L−1 (over 210 days is $67.6–$187.2 m−3. Desalination is accompanied by the removal, from the water, of one or more of: nitrate, chloride, fluoride, sulphate, phosphate, As, B, Ba, Ca, Cd, Co, Cu, Fe, Mg, Mn, Na, Ni, P, S, Si, Sr, Zn. The rate of desalination is enhanced by increasing temperatures and increasing HCO3−/CO32− concentrations. The rate of desalination decreases with increasing SO42− removal under acidic, or pH neutral, operating conditions.

  13. 过渡金属正离子和卡宾配合物成键特征的理论分析%Theoretical Analyses of Bond Character of Transition-Metal Ions with Carbene Complexes

    Institute of Scientific and Technical Information of China (English)

    丁涪江

    2003-01-01

    在6-311G基组从头算的基础上对第一过渡系含偶数电子的金属正离子(Sc+,V+,Mn+,Co+,Cu+)与卡宾CH2的配合物的成键特征进行了细致的分析.用能级位移算符逐步降低分子片空轨道能级的方法代替分子片轨道冻结,使KSM能量分解的耦合项得以消除.能量分析结果表明,Sc+-CH2键是由σ供键,π供键与π反馈键组成的,不能忽略π供键.而Cu+-CH2键是由σ供键与σ,π反馈键组成的,不能忽略σ反馈键.同时对VCH+2,MnCH+2和CoCH+2的1A1电子态也进行了粗略的讨论.

  14. Effects of aeration frequency on leachate quality and waste in simulated hybrid bioreactor landfills.

    Science.gov (United States)

    Ko, Jae Hac; Ma, Zeyu; Jin, Xiao; Xu, Qiyong

    2016-12-01

    Research has been conducted to investigate the effects of daily aeration frequency on leachate quality and waste settlement in simulated hybrid landfill bioreactors. Four laboratory-scale reactors were constructed and operated for about 10 months to simulate different bioreactor operations, including one anaerobic bioreactor and three hybrid bioreactors with different aeration frequencies (one, two, and four times per day). Chemical oxygen demand (COD) and biochemical oxygen demand (BOD5) reduced more than 96% of the initial concentrations in all aerated bioreactors. The differences of COD and BOD5 reductions among tested aeration frequencies were relatively small. For ammonia nitrogen, the higher aeration frequency (two or four times per day) resulted in the quicker reduction. Overall, the concentrations of heavy metals (Cr, Co, Cu, Mn, Ni, and Zn) decreased over time except Cd and Pb. The reduction of redox-sensitive metal concentrations (Mn, Co, Ni, and Cu) was greater in aerated bioreactors than in anaerobic bioreactor. Settlement of municipal solid waste (MSW) was enhanced with higher frequency of aeration events (four times per day). In recent years, hybird bioreactor landfill technology has gained a lot of attention. Appropriate aeration rate is crucial for hybrid bioreactor operation, but few studies have been done and different results were obtained. Research was conducted to investigate the effects of daily aeration frequency on leachate quality and waste settlement. Results indicated that aeration can effectively accelerate waste stabilization and remove organic carbon concentration and total nitrogen in the leachate.

  15. Soil amendments for heavy metals removal from stormwater runoff discharging to environmentally sensitive areas

    Science.gov (United States)

    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).

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

    Energy Technology Data Exchange (ETDEWEB)

    Mackie, Joshua A. [Moss Landing Marine Laboratories, Invertebrate Zoology, 8272 Moss Landing Road, CA 95039-9647 (United States)], E-mail: jmackie@mlml.calstate.edu; Natali, Susan M.; Levinton, Jeffrey S. [Stony Brook University, Department of Ecology and Evolution, Stony Brook, NY 11794-5245 (United States); Sanudo-Wilhelmy, Sergio A. [Stony Brook University, Department of Ecology and Evolution, Stony Brook, NY 11794-5245 (United States); University of Southern California, Marine and Environmental Biology, Los Angeles, CA 90089-0371 (United States)

    2007-09-15

    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.

  17. Spatial Gradients in Trace Metal Concentrations in the Surface Microlayer of the Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    Antonio eTovar-Sanchez

    2014-12-01

    Full Text Available The relationship between dust deposition and surface water metal concentrations is poorly understood. Dissolution, solubility, and partitioning reactions of trace metals from dust particles are governed by complex chemical, biological, and physical processes occurring in the surface ocean. Despite that, the role of the sea surface microlayer (SML, a thin, but fundamental component modulating the air-sea exchange of materials has not been properly evaluated. Our study revealed that the SML of the Mediterranean Sea is enriched with bioactive trace metals (i.e., Cd, Co, Cu and Fe, ranging from 8 (for Cd to 1000 (for Fe times higher than the dissolved metal pool in the underlying water column. The highest enrichments were spatially correlated with the atmospheric deposition of mineral particles. Our mass balance results suggest that the SML in the Mediterranean Sea contains about 2 tonnes of Fe. However, we did not detect any trends between the concentrations of metals in SML with the subsurface water concentrations and biomass distributions. These findings suggest that future studies are needed to quantify the rate of metal exchange between the SML and the bioavailable pool and that the SML should be considered to better understand the effect of atmospheric inputs on the biogeochemistry of trace metals in the ocean.

  18. Adsorption-Driven Surface Segregation of the Less Reactive Alloy Component

    DEFF Research Database (Denmark)

    Andersson, Klas Jerker; Calle Vallejo, Federico; Rossmeisl, Jan;

    2009-01-01

    Counterintuitive to expectations and all prior observations of adsorbate-induced surface segregation of the more reactive alloy component (the one forming the stronger bond with the adsorbate), we show that CO adsorption at elevated pressures and temperatures pulls the less reactive Cu to the sur......Counterintuitive to expectations and all prior observations of adsorbate-induced surface segregation of the more reactive alloy component (the one forming the stronger bond with the adsorbate), we show that CO adsorption at elevated pressures and temperatures pulls the less reactive Cu...... to the surface of a CuPt near-surface alloy. The Cu surface segregation is driven by the formation of a stable self-organized CO/CuPt surface alloy structure and is rationalized in terms of the radically stronger Pt−CO bond when Cu is present in the first surface layer of Pt. The results, which are expected...... to apply to a range of coinage (Cu, Ag)/Pt-group bimetallic surface alloys, open up new possibilities in selective and dynamical engineering of alloy surfaces for catalysis....

  19. Milli-PIXE determination of trace elements in osmium-rich platinum-group minerals from the Witwatersrand basin, South Africa

    Energy Technology Data Exchange (ETDEWEB)

    Merkle, R.K.W. E-mail: rkwm@scientia.up.ac.za; Franklyn, C.B

    1999-09-02

    Osmium-rich platinum-group minerals (PGM), like osmiridium or native osmium, are an integral, though rare, part of the mineralogy of the Witwatersrand paleoplacer. Usually these grains are small, on average <100 {mu}m in size, and the characteristics of their source areas are unknown. In the mineralogical literature on these PGM in the Witwatersrand gold reefs, no information on the trace elements in these minerals is available. The milli-PIXE system at the van de Graaff accelerator at the Atomic Energy Corporation of South Africa was used in a first attempt to determine a range of minor and trace elements, such as Co, Cu, Fe, Rh and Ru, in PGM from the Witwatersrand basin. This attempt is directed towards fingerprinting individual grains and to obtain possible information on the sources for these grains. It also serves as a first step towards a database of trace elements, which could allow a genetical classification of Os-rich PGM of unknown provenance.

  20. PCDD/F and metal concentrations in soil and herbage samples collected in the vicinity of a cement plant.

    Science.gov (United States)

    Schuhmacher, M; Bocio, A; Agramunt, M C; Domingo, J L; de Kok, H A M

    2002-07-01

    In May 2000, the levels of a number of metals (As, Cd, Pb, Hg, Zn, Co, Cu, Mn, Sn, Tl, Cr, Ni and V) were determined in 16 soil and herbage samples collected in the vicinity of a cement plant from Sta. Margarida i els Monjos (Catalonia, Spain). Metal concentrations were also analyzed in air filters from three sampling stations placed nearthe facility. For most metals, concentrations were similar or even lower than previously reported values for other areas from Catalonia. On the other hand, the levels of polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) were also determined in four soil and 16 herbage samples. Mean values were 0.37 and 0.16 ng I-TEQ/kg for soils and herbage, respectively, values which in comparison with data from other surveys are rather low. No significant differences between metal and PCDD/F concentrations in samples collected at distances lower or greater than 3.5 km of the facility were noted. The current results show that the cement plant has a low impact on the metal and PCDD/F levels in the environment under direct influence of the facility. These results should be of interest to assess future temporal variations in the levels of metals and PCDD/Fs in this area.

  1. Cu-Precipitation Strengthening in Ultrahigh-Strength Carburizing Steels

    Science.gov (United States)

    Tiemens, Benjamin L.; Sachdev, Anil K.; Olson, Gregory B.

    2012-10-01

    Ultrahigh hardness levels greater than 700 VHN can be obtained in secondary hardening carburizing steels but depend on costly Co alloying additions to maximize hardness achieved through M2C-type carbide precipitation strengthening. This study aims to incorporate nanometer-scale bcc Cu precipitates to both provide strength as well as catalyze M2C nucleation in the absence of or with reduced Co. Cu additions of 1.0 and 3.7 wt pct were investigated, using a series of mechanistic models coupled with thermodynamic computational tools to derive final compositions. Thirty-pound experimental heats were cast of each designed alloy, samples of which were carburized and tempered to determine their hardness response. Characterization revealed the successful incorporation of Cu alloying additions into this family of steels, demonstrating a secondary hardening response even in the absence of Co. Matrix strength levels were close to those predicted by design models; however, all four alloys demonstrated a hardness deficit of approximately 200 VHN at the carburized surface, suggesting recalibration of the M2C precipitation strengthening model may be required in these alloys.

  2. Distribution, source identification, and ecological risk assessment of heavy metals in wetland soils of a river-reservoir system.

    Science.gov (United States)

    Jiang, Xiaoliang; Xiong, Ziqian; Liu, Hui; Liu, Guihua; Liu, Wenzhi

    2017-01-01

    The majority of rivers in the world have been dammed, and over 45,000 large reservoirs have been constructed for multiple purposes. Riparian and reservoir shorelines are the two most important wetland types in a dammed river. To date, few studies have concerned the heavy metal pollution in wetland soils of these river-reservoir systems. In this study, we measured the concentrations of ten heavy metals (Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr, and Zn) in surface soils collected from riparian and reservoir shorelines along the Han River in different seasons. Our results found that the Co, Cu, and Ni concentrations in riparian wetlands were significantly lower than those in reservoir shorelines. In riparian wetlands, only soil Sr concentration significantly increased after summer and autumn submergence. Multivariate statistical analyses demonstrated that Ba and Cd might originate from industrial and mining sources, whereas Sr and Mn predominantly originated from natural rock weathering. The ecological risk assessment analysis indicated that both riparian and reservoir shorelines along the Han River in China exhibited a moderate ecological risk in soil heavy metals. The upper Han River basin is the water resource area of China's Middle Route of the South-to-North Water Transfer Project. Therefore, to control the contamination of heavy metals in wetland soils, more efforts should be focused on reducing the discharge of mining and industrial pollutants into the riparian and reservoir shorelines.

  3. Sedimentology, geochemistry, pollution status and ecological risk assessment of some heavy metals in surficial sediments of an Egyptian lagoon connecting to the Mediterranean Sea.

    Science.gov (United States)

    El-Said, Ghada F; Draz, Suzanne E O; El-Sadaawy, Manal M; Moneer, Abeer A

    2014-01-01

    Spatial distribution of heavy metals (Co, Cu, Ni, Cr, Mn, Zn and Fe) was studied on Lake Edku's surface sediments in relation to sedimentology and geochemistry characteristics and their contamination status on the ecological system. Lake Edku's sediments were dominated by sandy silt and silty sand textures and were enriched with carbonate content (9.83-58.46%). Iron and manganese were the most abundant heavy metals with ranges of 1.69 to 8.06 mg g(-1) and 0.88 to 3.27 mg g(-1), respectively. Cobalt and nickel showed a harmonic distribution along the studied sediments. The results were interpreted by the statistical means. The heavy metal pollution status and their ecological risk in Lake Edku was evaluated using the sediment quality guidelines and the contamination assessment methods (geoaccumulation, pollution load and potential ecological risk indices, enrichment factor, contamination degree as well as effect range median (ERM) and probable effect level (PEL) quotients). Amongst the determined heavy metals, zinc had the most ecological risk. Overall, the heavy metals in surface sediments showed ecological effect range from moderate to considerable risk, specially, in the stations in front of the seawater and in drain sources that had the highest toxic priority.

  4. Assessing heavy metal pollution in the recent bottom sediments of Mabahiss Bay, North Hurghada, Red Sea, Egypt.

    Science.gov (United States)

    Attia, Osama E A; Ghrefat, Habes

    2013-12-01

    Thirty-nine samples of recent bottom sediments were collected from Mabahiss Bay, north of Hurghada City, Red Sea, Egypt. The collected samples were subjected to a total digestion technique and analyzed by absorption spectrometer for metals including Pb, Zn, Cd, Ni, Co, Cu, and Mn. Concentration data were processed using correlation analysis, principal component analysis, and hierarchical cluster analysis. Multivariate statistical analysis classified heavy metals in the study area into different groups. The pollution level attributed to these metals was evaluated using geoaccumulation index and contamination factor in order to determine anthropogenically derived sediment contamination. The results of both geoaccumulation index and contamination factor results reveal that the study area is not contaminated with respect to Zn, Ni, Cu, and Mn; uncontaminated to moderately contaminate with Pb; and moderately to strongly contaminate with Cd. The high contents of Pb, Cd, and Co in the study area result from various anthropogenic activities including dredging, land filling, localized oil pollution, using of antifouling and anticorrosive paints from fishing and tourist boats, and sewage discharging from various sources within the study area.

  5. The bark of the branches of holm oak (Quercus ilex L.) for a retrospective study of trace elements in the atmosphere.

    Science.gov (United States)

    Drava, Giuliana; Brignole, Daniele; Giordani, Paolo; Minganti, Vincenzo

    2017-04-01

    Tree bark has proved to be a useful bioindicator for trace elements in the atmosphere, however it reflects an exposure occurring during an unidentified period of time, so it provides spatial information about the distribution of contaminants in a certain area, but it cannot be used to detect temporal changes or trends, which is an important achievement in environmental studies. In order to obtain information about a known period of time, the bark collected from the annual segments of tree branches can be used, allowing analyses going back 10-15 years with annual resolution. In the present study, the concentrations of As, Cd, Co, Cu, Fe, Mn, Ni, Pb, V and Zn were measured by atomic emission spectrometry in a series of samples covering the period from 2001 to 2013 in an urban environment. Downward time trends were significant for Cd, Pb and Zn. The only trace element showing an upward time trend was V. The concentrations of the remaining six trace elements were constant over time, showing that their presence in bark is not simply proportional to the duration of exposure. This approach, which is simple, reliable and widely applicable at a low cost, allows the "a posteriori" reconstruction of atmospheric trace element deposition when or where no monitoring programme is in progress and no other natural archives are available. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Distribution and accumulation of trace amounts in forest ecosystems. Verteilung und Akkumulation von Spurenstoffen in Waldoekosystemen

    Energy Technology Data Exchange (ETDEWEB)

    Lamersdorf, N.

    1988-01-01

    The work focuses on the comparison of the contents in trace amounts of individual compartments (needles, the bark of branches and stem, stem wood, different root fractions, organic ground cover, mineral soil) of three spruce forest ecosystems. Moreover a comparison of sites was made by examining spot samples from a spruce forest ecosystem (needles, bark), a beech forest ecosystem (bark, wood), and two forest stands of different leaf trees (beech, English oak; organic ground covers). The following elements were examined in varying intensities in the groups of samples: As, Bi, Pb, Cd, Se, Tl, Cr, Co, Cu, Mn, Ni, Zn, Sb, Be, Hg, Fe, Mo and V. The analytical effort involved depended for one thing on the wish to complete available knowledge on the distribution of trace amounts in forest ecosystems, and for the other on the desire to verify by means of a damaged spruce stand, whether the accumulation or depletion of trace amounts are in part responsible for forest disease in the north-west German coastal region. In parallel to these investigations, available data regarding the bills for main substances and trace amounts from other research projects were made use of. As a basis for characterizing and judging the trace substance concentrations ascertained in the forest ecosystems, the book gives an overview of the state of knowledge in the form of a bibliography.

  7. Factors to consider for trace element deposition biomonitoring surveys with lichen transplants

    Science.gov (United States)

    Ayrault, S.; Clochiatti, R.; Carrot, F.; Daudin, L.; Bennett, J.P.

    2007-01-01

    A trace element deposition biomonitoring experiment with transplants of the fruticose lichen Evernia prunastri was developed, aimed at monitoring the effects of different exposure parameters (exposure orientation and direct rain) and to the elements Ti, V, Cr, Co, Cu, Zn, Rb, Cd, Sb and Pb. Accumulations were observed for most of the elements, confirming the ability of Evernia transplants for atmospheric metal deposition monitoring. The accumulation trends were mainly affected by the exposure orientation and slightly less so by the protection from rain. The zonation of the trace elements inside the thallus was also studied. It was concluded that trace element concentrations were not homogeneous in Evernia, thus imposing some cautions on the sampling approach. A nuclear microprobe analysis of an E. prunastri transplanted thallus in thin cross-sections concluded that the trace elements were mainly concentrated on the cortex of the thallus, except Zn, Ca and K which were also present in the internal layers. The size of the particles deposited or entrapped on the cortex surface averaged 7????m. A list of key parameters to ensure the comparability of surveys aiming at observing temporal or spatial deposition variation is presented. ?? 2006 Elsevier B.V. All rights reserved.

  8. Geochemical characteristics of late Quaternary sediments from the southern Aegean Sea (Eastern Mediterranean

    Directory of Open Access Journals (Sweden)

    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.

  9. Chemometric Study of Trace Elements in Hard Coals of the Upper Silesian Coal Basin, Poland

    Directory of Open Access Journals (Sweden)

    Adam Smoliński

    2014-01-01

    Full Text Available The objective of the study was the analysis of trace elements contents in coals of the Upper Silesian Coal Basin (USCB, which may pose a potential threat to the environment when emitted from coal processing systems. Productive carbon overburden in central and southern zones of the USCB is composed mostly of insulating tertiary formations of a thickness from a few m to 1,100 m, and is represented by Miocene and Pliocene formations. In the data study the geological conditions of the coal seams of particular zones of the USCB were taken into account and the hierarchical clustering analysis was applied, which enabled the exploration of the dissimilarities between coal samples of various zones of the USCB in terms of basic physical and chemical parameters and trace elements contents. Coals of the northern and eastern zones of the USCB are characterized by high average Hg and low average Ba, Cr, and Ni contents, whereas coals of southern and western zones are unique due to high average concentrations of Ba, Co, Cu, Ni, and V. Coals of the central part of the USCB are characterized by the highest average concentration of Mn and the lowest average concentrations of As, Cd, Pb, V, and Zn.

  10. Metal uptake capability of Cyperus articulatus L. and its role in mitigating heavy metals from contaminated wetlands.

    Science.gov (United States)

    Galal, Tarek M; Gharib, Fatma A; Ghazi, Safia M; Mansour, Khalid H

    2017-07-27

    Wetland plants are biological filters that play an important role in maintaining aquatic ecosystem and can take up toxic metals from sediments and water. The present study investigated the seasonal variation in the accumulation potential of heavy metals by Cyperus articulatus in contaminated watercourses. Forty quadrats, distributed equally in 8 sites (six contaminated sites along Ismailia canal and two uncontaminated sites along the River Nile), were selected seasonally for sediment, water, and plant investigations. Autumn was the flourishing season of C. articulatus with the highest shoot density, length, and diameter as well as aboveground biomass, while summer showed the least growth performance. The photosynthetic pigments were markedly reduced under contamination stress. C. articulatus plants accumulated concentrations of most heavy metals, except Pb, in their roots higher than the shoots. The plant tissues accumulated the highest concentrations of Fe, Cd, Ni, and Zn during autumn, while Cu and Mn during spring, and Cr and Co during winter. It was found that Cd, Cu, Ni, Zn, Pb, and Co had seasonal bioaccumulation factor (BF) > 1 with the highest BF for Cd, Ni, and Zn during autumn, Co, Cu, and Pb in winter, spring, and summer, respectively. The translocation factor of most heavy metals, except Pb in spring, was pollution in contaminated wetlands.

  11. PREPARATION AND CHARACTERIZATION OF NANOSTRUCTURED GRANULAR SUPPORT PARTICLES AND CATALYTIC MATERIALS

    Energy Technology Data Exchange (ETDEWEB)

    Zhenchen Zhong

    2002-01-15

    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.

  12. Emprego de nebulizador pneumático de ICP-MS como câmara de diluição em sistemas de injeção em fluxo para determinações multielementares Pneumatic nebulizer as a dilution chamber in a flow-injection system for multielement analysis by ICP-MS

    Directory of Open Access Journals (Sweden)

    José Anchieta Gomes Neto

    1998-07-01

    Full Text Available An automatic dispenser based on a flow-injection system used to introduce sample and analytical solution into an inductively coupled plasma mass spectrometer through a spray chamber is proposed. Analytical curves were constructed after the injection of 20 to 750 µL aliquots of a multielement standard solution (20.0 µg L-1 in Li, Be, Al, V, Cr, Mn, Ni, Co, Cu, Zn, As, Se, Sr, Ag, Cd, Ba, Tl, Pb and the acquisition of the integrated transient signals. The linear concentration range could be extended to ca. five decades. The performance of the system was checked by analyzing a NIST 1643d reference material. Accuracy could be improved by the proper selection of the injected volume. Besides good precision (r.s.d. < 2%, the results obtained with the proposed procedure were closer to the certified values of the reference material than those obtained by direct aspiration or by injecting 125 µL of several analytical solutions and samples.

  13. 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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  14. Irradiation Effect of Argon Ion on Interfacial Structure Fe(2nm/Si(tsi=0.5-2 nm Multilayer thin Film

    Directory of Open Access Journals (Sweden)

    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.

  15. Urban and industrial contribution to trace elements in the atmosphere as measured in holm oak bark

    Science.gov (United States)

    Drava, Giuliana; Brignole, Daniele; Giordani, Paolo; Minganti, Vincenzo

    2016-11-01

    The concentrations of As, Cd, Co, Cu, Fe, Mn, Ni, Pb, V and Zn were measured by ICP-OES in samples of bark of the holm oak (Quercus ilex L.) collected from trees in different urban environments (residential and mixed residential/industrial). The use of tree bark as a bioindicator makes it easy to create maps that can provide detailed data on the levels and on the spatial distribution of each trace element. For most of the elements considered (As, Co, Fe, Mn, Ni, V and Zn), the concentrations in the industrial sites are about twice (from 1.9 to 2.8 times higher) of those in the residential area. Arsenic, Fe and Zn show the highest concentrations near a steel plant (operational until 2005), but for the other elements it is not possible to identify any localized source, as evident from the maps. In areas where urban pollution is summed up by the impact of industrial activities, the population is exposed to significantly higher amounts of some metals than people living in residential areas.

  16. Fluorine content in soils of Northern Pomoravlje

    Directory of Open Access Journals (Sweden)

    Jakovljević Miodrag D.

    2002-01-01

    Full Text Available Soil sampling was carried out in the Velika Morava river valley, covering the area from Velika Plana to the mouth of Morava to the Danube. The composite soil samples, representing alluvial soils (22 samples, cambisols (14 and smonitzas (4, were taken from plough layers, based on a regular square grid with intervals set at 5x5 km, covering total area of 100,000 ha. The total and available fluorine contents were determined in the soils samples. The highest average amount of total fluorine was found for alluvial soils (391 mg kg-1, then for smonitzas (348 mg kg-1 and the lowest one for cambisols (285 mg kg-1. These amounts are within normal fluorine content for soils (150-400 mg kg-1, although the maximum found levels were even about 500 mg kg-1. The available fluorine content was very low (< 1 mg kg-1, being mostly less than 0.2 % from its total amount, so it could be concluded that there was no danger from fluorine accumulation in the plants. Statistically significant correlation coefficient between total and available fluorine contents was not obtained. The total and available fluorine contents have mostly been in the correlation (with positive sign with soil pH and the content of mechanical fraction silt+clay. Significant correlation coefficients between total fluorine content and the content of some heavy metals (Cr, Ni, Co, Cu, As were also found, which indicated their mutual geochemical origin.

  17. Temporal and spatial variation of trace elements in atmospheric deposition around the industrial area of Puchuncaví-Ventanas (Chile) and its influence on exceedances of lead and cadmium critical loads in soils.

    Science.gov (United States)

    Rueda-Holgado, F; Calvo-Blázquez, L; Cereceda-Balic, F; Pinilla-Gil, E

    2016-02-01

    Fractionation of elemental contents in atmospheric samples is useful to evaluate pollution levels for risk assessment and pollution sources assignment. We present here the main results of long-term characterization of atmospheric deposition by using a recently developed atmospheric elemental fractionation sampler (AEFS) for major and trace elements monitoring around an important industrial complex located in Puchuncaví region (Chile). Atmospheric deposition samples were collected during two sampling campaigns (2010 and 2011) at four sampling locations: La Greda (LG), Los Maitenes (LM), Puchuncaví (PU) and Valle Alegre (VA). Sample digestion and ICP-MS gave elements deposition values (Al, As, Ba, Cd, Co, Cu, Fe, K, Mn, Pb, Sb, Ti, V and Zn) in the insoluble fraction of the total atmospheric deposition. Results showed that LG location, the closest location to the industrial complex, was the more polluted sampling site having the highest values for the analyzed elements. PU and LM were the next more polluted and, finally, the lowest elements concentrations were registered at VA. The application of Principal Component Analysis and Cluster Analysis identified industrial, traffic and mineral-crustal factors. We found critical loads exceedances for Pb at all sampling locations in the area affected by the industrial emissions, more significant in LG close to the industrial complex, with a trend to decrease in 2011, whereas no exceedances due to atmospheric deposition were detected for Cd.

  18. Improved detection of transition and rare earth elements in marine samples with the CETAC DSX-100 preconcentration/matrix elimination system and ICP-MS

    Energy Technology Data Exchange (ETDEWEB)

    Kuehn, M. [Technical Univ., Hamburg-Harburg (Germany). Inst. of Water Management and Water Supply; Kriews, M. [Alfred-Wegener-Institut fuer Polar- und Meeresforschung, Bremerhaven (Germany)

    2000-07-01

    A new method for detection of trace metals in saline samples is described using batch preconcentration with subsequent ICP-MS analyses after direct sample insertion of the analyte loaded chelating resin. The samples were prepared using a CETAC DSX-100 system, which preconcentrates analytes and removes matrix components by a suspended particulate reagent (SPR). The SPR is consisting of polymeric beads of 0.2 {mu}m size that selectively binds the trace metals by iminodiacetic chelating groups. The beads with bound analytes are then nebulized directly into the ICP-MS. The enrichment factors lay between 40 and 48 due to the enrichment of 120 mL suspension to 2.5-3.0 mL eluate. The method was applied and validated to the successful determination of traces of the transition metals Mn, Fe, Ni, Co, Cu, Zn, Cd, and Pb in the Open Ocean Seawater certified reference material NASS-4 and the Coastal Seawater certified reference material CASS-3. In addition to the certified constituents the rare earth elements La, Ce, Eu, Gd, Yb, and Lu were determined. (orig.)

  19. Association Analysis of SSR Markers with Phenology, Grain, and Stover-Yield Related Traits in Pearl Millet (Pennisetum glaucum (L. R. Br.

    Directory of Open Access Journals (Sweden)

    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.

  20. Selenite modulates the level of phenolics and nutrient element to alleviate the toxicity of arsenite in rice (Oryza sativa L.).

    Science.gov (United States)

    Chauhan, Reshu; Awasthi, Surabhi; Tripathi, Preeti; Mishra, Seema; Dwivedi, Sanjay; Niranjan, Abhishek; Mallick, Shekhar; Tripathi, Pratibha; Pande, Veena; Tripathi, Rudra Deo

    2017-04-01

    Arsenic (As) contamination of paddy rice is a serious threat all over the world particularly in South East Asia. Selenium (Se) plays important role in protection of plants against various abiotic stresses including heavy metals. Moreover, arsenite (AsIII) and selenite (SeIV) can be biologically antagonistic due to similar electronic configuration and sharing the common transporter for their uptake in plant. In the present study, the response of oxidative stress, phenolic compounds and nutrient elements was analyzed to investigate Se mediated As tolerance in rice seedlings during AsIII and SeIV exposure in hydroponics. Selenite (25µM) significantly decreased As accumulation in plant than As (25µM) alone treated plants. Level of oxidative stress related parameters viz., reactive oxygen species (ROS), lipid peroxidation, electrical conductivity, nitric oxide and pro-oxidant enzyme (NADPH oxidase), were in the order of As>As+Se>control>Se. Selenium ameliorated As phytotoxicity by increased level of phenolic compounds particularly gallic acid, protocatechuic acid, ferulic acid and rutin and thiol metabolism related enzymes viz., serine acetyl transferase (SAT) and cysteine synthase (CS). Selenium supplementation enhanced the uptake of nutrient elements viz., Fe, Mn, Co, Cu, Zn, Mo, and improved plant growth. The results concluded that Se addition in As contaminated environment might be an important strategy to reduce As uptake and associated phytotoxicity in rice plant by modulation of phenolic compounds and increased uptake of nutrient elements.

  1. Magnetism of coherent Co and Ni thin films on Cu(111) and Au(111) substrates: An ab initio study

    Science.gov (United States)

    Zelený, Martin; Dlouhý, Ivo

    2017-02-01

    We present an ab initio study of structural and magnetic properties of coherent Co and Ni thin films on Cu(111) and Au(111) substrates with thicknesses of up to 6 monolayers. All studied films on Cu(111) substrates prefer structures close their ground state (hcp for Co and fcc for Ni), whereas only the hcp stacking sequence has been found for both films on Au(111) substrates. All studied films exhibit instability of the first monolayer with respect to decomposition into 2-monolayer- or 3-monolayer-high islands, which is in agreement with experimental findings. All studied films are also ferromagnetic, nevertheless the Ni/Cu(111) films reduce their magnetic moments in the layer adjacent to the substrate due to a stronger Cu-Ni interaction at the interface. The magnetic anisotropy of a Co film does not depend on the film thickness: all the studied Co/Au(111) films exhibit a perpendicular magnetic anisotropy, whereas all the Co/Cu(111) films prefer in-plane magnetization. On the other hand, both Ni films change their preference for in-plane orientation of their easy axis to out-of-plane orientation at a critical thickness of 2 monolayers, however, the magnetic anisotropy energies for films thicker than 1 monolayer are smaller than 1 meV/Ni atom. These behaviors of magnetic anisotropy do not depend on the structure of the studied films.

  2. Assessment of heavy metals contamination in sediments from three adjacent regions of the Yellow River using metal chemical fractions and multivariate analysis techniques.

    Science.gov (United States)

    Ma, Xiaoling; Zuo, Hang; Tian, Mengjing; Zhang, Liyang; Meng, Jia; Zhou, Xuening; Min, Na; Chang, Xinyuan; Liu, Ying

    2016-02-01

    Metal chemical fractions obtained by optimized BCR three-stage extraction procedure and multivariate analysis techniques were exploited for assessing 7 heavy metals (Cr, Pb, Cd, Co, Cu, Zn and Ni) in sediments from Gansu province, Ningxia and Inner Mongolia Autonomous Regions of the Yellow River in Northern China. The results indicated that higher susceptibility and bioavailability of Cr and Cd with a strong anthropogenic source were due to their higher availability in the exchangeable fraction. A portion of Pb, Cd, Co, Zn, and Ni in reducible fraction may be due to the fact that they can form stable complexes with Fe and Mn oxides. Substantial amount of Pb, Co, Ni and Cu was observed as oxidizable fraction because of their strong affinity to the organic matters so that they can complex with humic substances in sediments. The high geo-accumulation indexes (I(geo)) for Cr and Cd showed their higher environmental risk to the aquatic biota. Principal component analysis (PCA) revealed that high toxic Cr and Cd in polluted sites (Cd in S10, S11 and Cr in S13) may be contributed to anthropogenic sources, it was consistent with the results of dual hierarchical clustering analysis (DHCA), which could give more details about contributing sources.

  3. Interrelationships of metal transfer factor under wastewater reuse and soil pollution.

    Science.gov (United States)

    Papaioannou, D; Kalavrouziotis, I K; Koukoulakis, P H; Papadopoulos, F; Psoma, P

    2017-04-20

    The transfer of heavy metals under soil pollution wastewater reuse was studied in a Greenhouse experiment using a randomized block design, including 6 treatments of heavy metals mixtures composed of Zn, Mn, Cd, Co, Cu, Cr, Ni, and Pb, where each metal was taking part in the mixture with 0, 10, 20, 30, 40, 50 mg/kg respectively, in four replications. The Beta vulgaris L (beet) was used as a test plant. It was found that the metal transfer factors were statistically significantly related to the: (i) DTPA extractable soil metals, (ii) the soil pollution level as assessed by the pollution indices, (iii) the soil pH, (iv) the beet dry matter yield and (v) the interactions between the heavy metals in the soil. It was concluded that the Transfer Factor is subjected to multifactor effects and its real nature is complex, and there is a strong need for further study for the understanding of its role in metal-plant relationships. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Potential Health Benefits and Metabolomics of Camel Milk by GC-MS and ICP-MS.

    Science.gov (United States)

    Ahamad, Syed Rizwan; Raish, Mohammad; Ahmad, Ajaz; Shakeel, Faiyaz

    2017-02-01

    None of the research reports reveals the metabolomics and elemental studies on camel milk. Recent studies showed that camel milk possesses anticancer and anti-inflammatory activity. Metabolomics and elemental studies were carried out in camel milk which showed us the pathways and composition that are responsible for the key biological role of camel milk. Camel milk was dissolved in methanol and chloroform fraction and then vortexed and centrifuged. Both the fractions were derivatized by N,O-bis-(trimethylsilyl)trifluoroacetamide (BSTFA) and TMCS after nitrogen purging and analyzed by GC-MS. Camel milk was also analyzed by ICP-MS after microwave digestion. We found that higher alkanes and fatty acids are present in the chloroform fraction and amino acids, sugars and fatty acid derivatives are present in aqueous fractions. All the heavy metals like As, Pb, Cd, Co, Cu, and Ni were in the safe limits in terms of maximum daily intake of these elements. Na, K, Mg, and Ca were also present in the safe limits in terms of maximum daily intake of these elements. These results suggested that the camel milk drinking is safe and there is no health hazard. The present data of GC-MS and ICP-MS correlate the activities related to camel milk.

  5. Combinatorial methods for discovery of new photocatalytic materials for hydrogen synthesis

    Energy Technology Data Exchange (ETDEWEB)

    McFarland, E.W.; Baeck, S.-H.; Brandli, C.; Ivanovskaya, A.; Jaramillo, T. [California Univ., Santa Barbara, CA (United States). Dept. of Chemical Engineering

    2001-06-01

    Hydrogen is considered to be an alternative, renewable energy source that can replace fossil fuels, but the high cost of efficient photoelectrochemical synthesis is prohibitive. New materials for hydrogen production by photosynthesis from water are under investigation using a combination of methods based on electrochemistry. Parallel and serial rapid electrosynthesis systems have been developed for obtaining a mixed metal oxide collection of materials. High-throughput materials screening was achieved by direct detection of hydrogen using a two-dimensional WO{sub 3}/Pd based chemo-optical sensor system. It was also achieved indirectly by the measured photocurrents. Hundreds of different compositions were automatically synthesized on glass, metal or semiconductor hosts. New compositions indicate that performance is promising and show that the use of combinatorial chemistry methods is a powerful method to produce hydrogen. The potential photocatalysts were metal oxide semiconductor hosts (TiO{sub 2}, Fe{sub 2}O{sub 3}, WO{sub 3} and CU{sub 2}O) doped with different cations of Ru, Pt, Cr, Zn, Co, Cu, Ni, Mn, Fe, and Sn. Zero bias photocurrents were plotted for each material. 17 refs., 8 figs.

  6. The partitioning behavior of trace element and its distribution in the surrounding soil of a cement plant integrated utilization of hazardous wastes.

    Science.gov (United States)

    Yang, Zhenzhou; Chen, Yan; Sun, Yongqi; Liu, Lili; Zhang, Zuotai; Ge, Xinlei

    2016-07-01

    In the present study, the trace elements partitioning behavior during cement manufacture process were systemically investigated as well as their distribution behaviors in the soil surrounding a cement plant using hazardous waste as raw materials. In addition to the experimental analysis, the thermodynamic equilibrium calculations were simultaneously conducted. The results demonstrate that in the industrial-scale cement manufacture process, the trace elements can be classified into three groups according to their releasing behaviors. Hg is recognized as a highly volatile element, which almost totally partitions into the vapor phase. Co, Cu, Mn, V, and Cr are considered to be non-volatile elements, which are largely incorporated into the clinker. Meanwhile, Cd, Ba, As, Ni, Pb, and Zn can be classified into semi-volatile elements, as they are trapped into clinker to various degrees. Furthermore, the trace elements emitted into the flue gas can be adsorbed onto the fine particles, transport and deposit in the soil, and it is clarified here that the soil around the cement plant is moderately polluted by Cd, slightly polluted by As, Cr, Ba, Zn, yet rarely influenced by Co, Mn, Ni, Cu, Hg, and V elements. It was also estimated that the addition of wastes can efficiently reduce the consumption of raw materials and energy. The deciphered results can thus provide important insights for estimating the environmental impacts of the cement plant on its surroundings by utilizing wastes as raw materials.

  7. Reduction of magnetic damping and isotropic coercivity and increase of saturation magnetization in Rh-incorporated CoIr system

    Science.gov (United States)

    Wong, H. S.; He, S. K.; Chung, H. J.; Zhang, M. S.; Cher, Kelvin; Low, Melvin; Zhou, T. J.; Yang, Y.; Wong, S. K.

    2016-11-01

    Replacing Ir with Rh in a CoIr system possessing negative uniaxial magnetocrystalline anisotropy (K u ) substantially reduces its magnetic damping and coercivity by more than half while retaining its high negative K u . Moreover, a higher saturation magnetization (M s ) and more isotropic coercivity are achieved. Such material development makes it particularly suitable for use as the soft underlayer (SUL) of magnetic recording media for reducing noise, and as the oscillation layer of a spin-torque oscillator (STO) for achieving higher oscillation frequency, larger AC magnetic field and lower driving current, which can be readily integrated with the current recording head for microwave-assisted magnetic recording. Finally, we recommend a composite free layer by coupling CoIr with a spin polarizer (Co or Co/Cu/Co) for the enhancement of the spin-polarization rate and, therefore, the improvement of STO efficiency. These could pave the way for CoIr-based materials to be implemented in devices requiring a negative Ku with low damping and high ‘softness’, such as oscillators.

  8. Contamination by trace elements at e-waste recycling sites in Bangalore, India.

    Science.gov (United States)

    Ha, Nguyen Ngoc; Agusa, Tetsuro; Ramu, Karri; Tu, Nguyen Phuc Cam; Murata, Satoko; Bulbule, Keshav A; Parthasaraty, Peethmbaram; Takahashi, Shin; Subramanian, Annamalai; Tanabe, Shinsuke

    2009-06-01

    The recycling and disposal of electronic waste (e-waste) in developing countries is causing an increasing concern due to its effects on the environment and associated human health risks. To understand the contamination status, we measured trace elements (TEs) in soil, air dust, and human hair collected from e-waste recycling sites (a recycling facility and backyard recycling units) and the reference sites in Bangalore and Chennai in India. Concentrations of Cu, Zn, Ag, Cd, In, Sn, Sb, Hg, Pb, and Bi were higher in soil from e-waste recycling sites compared to reference sites. For Cu, Sb, Hg, and Pb in some soils from e-waste sites, the levels exceeded screening values proposed by US Environmental Protection Agency (EPA). Concentrations of Cr, Mn, Co, Cu, In, Sn, Sb, Tl, Pb and Bi in air from the e-waste recycling facility were relatively higher than the levels in Chennai city. High levels of Cu, Mo, Ag, Cd, In, Sb, Tl, and Pb were observed in hair of male workers from e-waste recycling sites. Our results suggest that e-waste recycling and its disposal may lead to the environmental and human contamination by some TEs. To our knowledge, this is the first study on TE contamination at e-waste recycling sites in Bangalore, India.

  9. Aerobic methylcyclohexane-promoted epoxidation of stilbene over gold nanoparticles supported on Gd-doped titania

    KAUST Repository

    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.

  10. Effect of metal accumulation on metallothionein level and condition of the periwinkle Littorina littorea along the Scheldt estuary (the Netherlands).

    Science.gov (United States)

    Van den Broeck, Heidi; De Wolf, Hans; Backeljau, Thierry; Blust, Ronny

    2010-05-01

    Metal (i.e. Ag, As, Ca, Cd, Co, Cu, Mn, Pb and Zn) and metallothionein (MT) concentrations in the soft tissue of Littorina littorea were measured along the heavily polluted Western Scheldt (WS) and relatively clean Eastern Scheldt (ES) estuary. Along the WS metal and MT levels in periwinkles reflected the known downstream decreasing pollution gradient. Surprisingly in ES animals As, Mn and Zn concentrations decreased from east to west reflecting past pollution. Compared to the WS metal concentrations of ES periwinkles were significantly lower and both estuaries were maximally discriminated from each other based on their Cd soft tissue concentration using a canonical discriminant analysis. Furthermore, no overall difference was found in MT levels among animals from both estuaries. Using previously obtained condition data (i.e. dry/wet weight ratio and lipid content) the relation between soft tissue metal concentration (i.e. Cd, Cu and Zn) and fitness indicators (i.e. MT and condition data) was examined using a canonical correlation analysis. Periwinkles with a high metal load (i.e. Cd and Zn) also had high MT levels but were in a relatively poor condition.

  11. Effect of metal accumulation on metallothionein level and condition of the periwinkle Littorina littorea along the Scheldt estuary (the Netherlands)

    Energy Technology Data Exchange (ETDEWEB)

    Van den Broeck, Heidi, E-mail: Heidi.VandenBroeck@ua.ac.b [University of Antwerp - Groenenborger Campus, Laboratory of Ecophysiology, Biochemistry and Toxicology, Groenenborgerlaan 171, building U5, B-2020 Antwerp (Belgium); De Wolf, Hans [University of Antwerp - Groenenborger Campus, Laboratory of Ecophysiology, Biochemistry and Toxicology, Groenenborgerlaan 171, building U5, B-2020 Antwerp (Belgium); Backeljau, Thierry [University of Antwerp - Groenenborger Campus, Laboratory of Ecophysiology, Biochemistry and Toxicology, Groenenborgerlaan 171, building U5, B-2020 Antwerp (Belgium); Royal Belgian Institute of Natural Sciences, Department of Invertebrates, Vautierstraat 29, B-1000 Brussels (Belgium); Blust, Ronny [University of Antwerp - Groenenborger Campus, Laboratory of Ecophysiology, Biochemistry and Toxicology, Groenenborgerlaan 171, building U5, B-2020 Antwerp (Belgium)

    2010-05-15

    Metal (i.e. Ag, As, Ca, Cd, Co, Cu, Mn, Pb and Zn) and metallothionein (MT) concentrations in the soft tissue of Littorina littorea were measured along the heavily polluted Western Scheldt (WS) and relatively clean Eastern Scheldt (ES) estuary. Along the WS metal and MT levels in periwinkles reflected the known downstream decreasing pollution gradient. Surprisingly in ES animals As, Mn and Zn concentrations decreased from east to west reflecting past pollution. Compared to the WS metal concentrations of ES periwinkles were significantly lower and both estuaries were maximally discriminated from each other based on their Cd soft tissue concentration using a canonical discriminant analysis. Furthermore, no overall difference was found in MT levels among animals from both estuaries. Using previously obtained condition data (i.e. dry/wet weight ratio and lipid content) the relation between soft tissue metal concentration (i.e. Cd, Cu and Zn) and fitness indicators (i.e. MT and condition data) was examined using a canonical correlation analysis. Periwinkles with a high metal load (i.e. Cd and Zn) also had high MT levels but were in a relatively poor condition. - Studying the effect of metals on MT and condition revealed that Littorina littorea with a high metal load also had high MT levels but were in relatively poor condition.

  12. Absorção de metais pesados do lodo de esgoto pelo feijoeiro (Phaseolus vulgaris L. Heavy Metal Uptake Of The Sewage Sludge By Bean Plants(Phaseolus vulgaris L.

    Directory of Open Access Journals (Sweden)

    Mário Miyazawa

    1998-06-01

    Full Text Available Toxicity and uptake of heavy metals of sewage sludge by beans (Phaseolus vulgaris L. were evaluated in green house experiments. Treatments consisted of 1,0 ; 2,0 and 5,0% (m/m of dry sewage sludge, collected from Londrina (Bom Retiro and ETE-Sul and Curitiba (ETE-Belém and RALF. Bean ( variety IAPAR 57 was sown three times at 0, 120 and 240 days after the treatments have been applied. Contents of Cd, Cr, Co, Cu, Ni, and Pb in bean tissues cultivated with 5,0% (m/m of all sewage sludge were similar to the control and Ba contents were reduced by increasing the quantity of sewage sludge in the soil. The Zn content in tissue bean incresed from 86 mg kg-1 of control to 462 mg kg-1 by applying 5% (m/m of sewage sludge in soil, but plant beans did not show toxicity symptons. The addition of 5% (m/m of sewage sludge increased Mn content in plants, from 193 mg kg-1 of control to 1.960 mg kg-1, showing toxity in bean leaves when the contents were more than 500 mg kg-1. The addition of sewage sludges in soils increased only available Zn carbonate and Cu organic species.

  13. Potentially toxic element contamination in soil and accumulation in maize plants in a smelter area in Kosovo.

    Science.gov (United States)

    Nannoni, Francesco; Rossi, Sara; Protano, Giuseppe

    2016-06-01

    A biogeochemical field study was carried out in the industrial area of Kosovska Mitrovica in northern Kosovo, where agricultural soils were contaminated by potentially toxic elements due to smelting activity. Total and bioavailable contents of As, Cd, Co, Cu, Pb, Sb, U and Zn in soil and their concentrations in maize roots and grains were determined. Soil contamination by As, Cd, Cu, Pb, Sb and Zn was variable from slightly to highly contaminated soils and influenced both the bioavailable fraction and accumulation of these potentially toxic elements in maize tissues. The comparison between potentially toxic element concentrations in roots and grains indicated that maize is able to limit the transfer of non-essential elements to edible parts. The plant-to-soil bioconcentration indices suggested that the transfer of potentially toxic elements from soil to plant was predicted better by bioavailable concentrations than by the total contents. These indices further identified some competitions and interactions among these elements in root uptake and root-to-grain translocation.

  14. An Electronic Tongue Designed to Detect Ammonium Nitrate in Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Inmaculada Campos

    2013-10-01

    Full Text Available An electronic tongue has been developed to monitor the presence of ammonium nitrate in water. It is based on pulse voltammetry and consists of an array of eight working electrodes (Au; Pt; Rh; Ir; Cu; Co; Ag and Ni encapsulated in a stainless steel cylinder. In a first step the electrochemical response of the different electrodes was studied in the presence of ammonium nitrate in water in order to further design the wave form used in the voltammetric tongue. The response of the electronic tongue was then tested in the presence of a set of 15 common inorganic salts; i.e.; NH4NO3; MgSO4; NH4Cl; NaCl; Na2CO3; (NH42SO4; MgCl2; Na3PO4; K2SO4; K2CO3; CaCl2; NaH2PO4; KCl; NaNO3; K2HPO4. A PCA plot showed a fairly good discrimination between ammonium nitrate and the remaining salts studied. In addition Fuzzy Art map analyses determined that the best classification was obtained using the Pt; Co; Cu and Ni electrodes. Moreover; PLS regression allowed the creation of a model to correlate the voltammetric response of the electrodes with concentrations of ammonium nitrate in the presence of potential interferents such as ammonium chloride and sodium nitrate.

  15. The effects of phosphorus additions on the sedimentation of contaminants in a uranium mine pit-lake.

    Science.gov (United States)

    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 (pRa-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 (p<0.05) with phosphorus load. Selenium and Mo did not respond to nutrient treatments. Our results suggest that phytoremediation 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.

  16. Study on the Properties of Metallophthalocyanine-Fe3O4 Nanoparticles Composite

    Institute of Scientific and Technical Information of China (English)

    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.

  17. PREPARATION,COMPLEX MECHANISM AND STRUCTURE MODEL OF METALLOPHTHALOC- YANINE-Fe3O4 NANOPARTICLES COMPOSITE

    Institute of Scientific and Technical Information of China (English)

    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.

  18. Geochemical characteristics of late Quaternary sediments from the southern Aegean Sea (Eastern Mediterranean

    Directory of Open Access Journals (Sweden)

    A. SIOULAS

    2000-12-01

    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.

  19. Analysis of Mineral and Heavy Metal Content of Some Commercial Fruit Juices by Inductively Coupled Plasma Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    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.

  20. The effect of Cu substitution on microstructure and thermoelectric properties of LaCoO3 ceramics.

    Science.gov (United States)

    Li, Fu; Li, Jing-Feng; Li, Jian-Hui; Yao, Fang-Zhou

    2012-09-21

    La(Co, Cu)O(3-δ) ceramics were prepared by pressureless sintering of citrate precursor powders, and their thermoelectric properties were investigated with an emphasis on the influence of Cu doping and phase structure as well as microstructure. It was found that a secondary phase first appeared in the form of a network along the grain boundaries and then changed to dispersion with increasing Cu content, which effectively reduced the lattice thermal conductivity of the materials. The thermal conductivity was only 1.21 W m(-1) K(-1) for the sample LaCo(0.75)Cu(0.25)O(3-δ), being much lower as for the thermoelectric oxide materials. In addition, a small amount of Cu substitution for Co increased the electrical conductivity greatly and the absolute Seebeck coefficient, whose sign was also reversed from negative to positive. The dimensionless figure of merit, ZT, of LaCoO(3-δ) oxides at low and middle temperatures can be remarkably enhanced by substituting Co with Cu.

  1. Fourier transform infrared spectroscopic characterisation of heavy metal-induced metabolic changes in the plant-associated soil bacterium Azospirillum brasilense Sp7

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    Dong, Yan; Rosenbaum, Ralph K; Hauschild, Michael Z

    2016-01-05

    This study is a first attempt to develop globally applicable and spatially differentiated marine comparative toxicity potentials (CTPs) or ecotoxicity characterization factors for metals in coastal seawater for use in life cycle assessment. The toxicity potentials are based exclusively on marine 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 varies 3-4 orders of magnitude across LMEs, largely due to different seawater residence times. Therefore, the highest toxicity potential for metals was found in the LMEs with the longest seawater residence times. Across metals, the highest CTPs were observed for Cd, Pb, and Zn. At the concentration levels occurring in coastal seawaters, Fe acts not as a toxic agent but as an essential nutrient and thus has CTPs of zero.

  3. Effect of Sequence of Impregnation on the Structure and Catalytic Properties of Cu-Co-Al-Oxide System

    Institute of Scientific and Technical Information of China (English)

    Suzan A.Ali

    2004-01-01

    Twelve samples of Co-Cu/Al2O3 were prepared by impregnating Al2O3 with cobalt salt followed by copper salt or vice versa. The composition of the prepared samples varied in the molar ratios 1:1, 1:2 and 1:3 with respect to CuO:CoO or CoO:CuO, while Al2O3 content was kept at about 13-15 mol. The prepared solids were calcined at diflerent temperatures and the products were characterized by means of XRD-analysis. The catalytic activity of the calcined solids was tested in H2O2 decomposition. The XRD-analysis revealed that the sequence of impregnation affects much the structure of the samples. The loading of alumina with cobalt followed by copper salts produced sample with structure differs from that for sample firstly treated with copper followed by cobalt salts. XRD- analysis showed the formation of crystalline spinel Co1-x Cux Al2O4 with nearly the same crystal structure as CoAl2O4 even with high copper content. The examination of catalytic activity of these samples showed that catalysts with Co-loaded over Cu were more active than catalysts with Cu loaded over Co. In all cases the double oxides loaded over Al2O3 were more active than the single oxide over Al2O3.

  4. Factors to consider for trace element deposition biomonitoring surveys with lichen transplants

    Energy Technology Data Exchange (ETDEWEB)

    Ayrault, Sophie [Laboratoire des Sciences du Climat et de l' Environnement, CEA-CNRS-UVSQ, F-91198 Gif-sur-Yvette (France)]. E-mail: sophie.ayrault@lsce.cnrs-gif.fr; Clochiatti, Roberto [Laboratoire Pierre Suee, CEA-CNRS, CEA Saclay, F-91191 Gif-sur-Yvette (France); Carrot, Francine [Laboratoire Pierre Suee, CEA-CNRS, CEA Saclay, F-91191 Gif-sur-Yvette (France); Daudin, Laurent [Laboratoire Pierre Suee, CEA-CNRS, CEA Saclay, F-91191 Gif-sur-Yvette (France); Bennett, James P. [U. S. Geological Survey and Institute for Environmental Studies, University of Wisconsin, Madison, Wisconsin 53706 (United States)

    2007-01-01

    A trace element deposition biomonitoring experiment with transplants of the fruticose lichen Evernia prunastri was developed, aimed at monitoring the effects of different exposure parameters (exposure orientation and direct rain) and to the elements Ti, V, Cr, Co, Cu, Zn, Rb, Cd, Sb and Pb. Accumulations were observed for most of the elements, confirming the ability of Evernia transplants for atmospheric metal deposition monitoring. The accumulation trends were mainly affected by the exposure orientation and slightly less so by the protection from rain. The zonation of the trace elements inside the thallus was also studied. It was concluded that trace element concentrations were not homogeneous in Evernia, thus imposing some cautions on the sampling approach. A nuclear microprobe analysis of an E. prunastri transplanted thallus in thin cross-sections concluded that the trace elements were mainly concentrated on the cortex of the thallus, except Zn, Ca and K which were also present in the internal layers. The size of the particles deposited or entrapped on the cortex surface averaged 7 {mu}m. A list of key parameters to ensure the comparability of surveys aiming at observing temporal or spatial deposition variation is presented.

  5. Factors to consider for trace element deposition biomonitoring surveys with lichen transplants.

    Science.gov (United States)

    Ayrault, Sophie; Clochiatti, Roberto; Carrot, Francine; Daudin, Laurent; Bennett, James P

    2007-01-01

    A trace element deposition biomonitoring experiment with transplants of the fruticose lichen Evernia prunastri was developed, aimed at monitoring the effects of different exposure parameters (exposure orientation and direct rain) and to the elements Ti, V, Cr, Co, Cu, Zn, Rb, Cd, Sb and Pb. Accumulations were observed for most of the elements, confirming the ability of Evernia transplants for atmospheric metal deposition monitoring. The accumulation trends were mainly affected by the exposure orientation and slightly less so by the protection from rain. The zonation of the trace elements inside the thallus was also studied. It was concluded that trace element concentrations were not homogeneous in Evernia, thus imposing some cautions on the sampling approach. A nuclear microprobe analysis of an E. prunastri transplanted thallus in thin cross-sections concluded that the trace elements were mainly concentrated on the cortex of the thallus, except Zn, Ca and K which were also present in the internal layers. The size of the particles deposited or entrapped on the cortex surface averaged 7 microm. A list of key parameters to ensure the comparability of surveys aiming at observing temporal or spatial deposition variation is presented.

  6. Seasonal variations in the chemical composition of particulate matter: a case study in the Po Valley. Part II: concentration and solubility of micro- and trace-elements.

    Science.gov (United States)

    Canepari, S; Astolfi, M L; Farao, C; Maretto, M; Frasca, D; Marcoccia, M; Perrino, C

    2014-03-01

    Size distribution (fine and coarse fraction) and solubility distribution (extracted and residual fraction) of 20 elements (As, Ba, Be, Cd, Co, Cu, Fe, Li, Mn, Pb, Ni, Rb, S, Sb, Se, Sn, Sr, Ti, Tl, V) in atmospheric particulate matter (PM) were determined during a 5-year field study carried out in the Po Valley (peri-urban area of Ferrara, in Northern Italy). By studying the contribution of the two size fractions and the two solubility fractions to the atmospheric concentration of each element, it was possible to obtain interesting information about the variability of PM sources, to assess the role played by atmospheric stability in determining pollution episodes, and to obtain an estimate of the bio-accessible fraction. Atmospheric stability is confirmed to be one of the main causes of atmospheric pollution in this area and is to be responsible for the pronounced winter increase in both PM and elemental concentration. Long-range transport of natural and polluted air masses caused temporary increases in PM and elemental concentration, while local industrial emission seemed to play a secondary role. Regulated elements were well below their concentration limit, but many toxic elements were in the form of fine particles and soluble chemical species, more accessible to the environment, and the human body.

  7. Platinum Alloy Tailored All-Weather Solar Cells for Energy Harvesting from Sun and Rain.

    Science.gov (United States)

    Tang, Qunwei; Duan, Yanyan; He, Benlin; Chen, Haiyan

    2016-11-07

    Solar cells that can harvest energy in all weathers are promising in solving the energy crisis and environmental problems. The power outputs are nearly zero under dark conditions for state-of-the-art solar cells. To address this issue, we present herein a class of platinum alloy (PtMx , M=Ni, Fe, Co, Cu, Mo) tailored all-weather solar cells that can harvest energy from rain and realize photoelectric conversion under sun illumination. By tuning the stoichiometric Pt/M ratio and M species, the optimized solar cell yields a photoelectric conversion efficiency of 10.38 % under simulated sunlight irradiation (AM 1.5, 100 mW cm(-2) ) as well as current of 3.90 μA and voltage of 115.52 μV under simulated raindrops. Moreover, the electric signals are highly dependent on the dripping velocity and the concentration of simulated raindrops along with concentrations of cation and anion.

  8. Bioaccumulation of macro- and trace elements by European frogbit (Hydrocharis morsus-ranae L.) in relation to environmental pollution.

    Science.gov (United States)

    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.

  9. Heavy metals burden in kidney and heart tissues of Scarus ghobban fish from the eastern province of Saudi Arabia

    Directory of Open Access Journals (Sweden)

    Waqar Ashraf

    2010-04-01

    Full Text Available Levels of selected heavy metals (Pb, Co, Cu, Ni, Zn, Mn and Cd in the heart and kidney tissues of parrot fish, collected from the Arabian Gulf, Eastern Province of Saudi Arabia, were determined by wet-digestion based atomic absorption method. The results showed that accumulation pattern of analyzed metals in the kidney tissues followed the order; Zn > Cu > Co > Pb > Ni > Mn > Cd. In the heart tissue the analyzed metals followed similar pattern of metal accumulation. The average Pb (0.85 ± 0.50 ppm, Cd (0.12 ± 0.07 ppm, Ni (0.92 ± 0.35 ppm and Mn (0.86 ± 0.43 ppm were significantly lower in the heart tissue whereas Zn (26.4 ± 12.9 ppm and Cu (3.29 ± 2.18 ppm were higher in the kidney tissues. In general, the data indicated that marine fish from the sampling site of the Arabian Gulf contain relatively less burden of heavy metals in their tissues.

  10. Electronic and magnetic properties at rough and sharp transition metal–metal interfaces: An augmented space approach

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Concentration of selected trace elements in Xerocomus badius mushroom bodies - a health risk for humans?

    Directory of Open Access Journals (Sweden)

    Mirosław Mleczek

    2013-09-01

    Full Text Available Introduction. As regards a signifi cant intake of wild growing edible mushrooms, especially in East and Central Europe, concentrations of toxic elements should be periodically analysed. The aim of the study was to assess changes in concentrations of selected trace elements (Ba, Cd, Co, Cu, Fe, Hg, Mn, Ni, Pb, Sr and Zn in a mushroom species, Xerocomus badius. Material and methods. Xerocomus badius fruiting bodies were collected from fi ve regions of Poland within the last 20 years (selected years when these mushrooms were growing. Flame atomic absorption spectrometry (FAAS was used for determination of 10 elements while for Hg cold vapour atomic absorption spectrometry (CVAAS was used. Results. Generally the results show no signifi cant differences in the accumulation effi ciency of individual elements by mushrooms collected from different regions of Poland, but signifi cant differences were observed in the accumulation effi ciency of these elements by mushrooms collected in particular years of their harvest. The highest accumulation indicated by bioconcentration factors (BCFs was observed for Cu (10.03, Hg (148.15 and Zn (4.88. Conclusion. Concentrations of Cu, Fe, Mn, Zn in the tested mushrooms were found to be lower than the values of the recommended dietary allowances (RDA, therefore the levels of these elements are not toxic for people. In our opinion, occasional consumption of these mushroom fruiting bodies within the last 20 years in Poland did not provide signifi cant amounts of analysed trace elements (no more than other foods.

  12. Antiferromagnet-induced perpendicular magnetic anisotropy in ferromagnetic/antiferromagnetic/ferromagnetic trilayers

    Science.gov (United States)

    Wang, Bo-Yao; Lin, Po-Han; Tsai, Ming-Shian; Shih, Chun-Wei; Lee, Meng-Ju; Huang, Chun-Wei; Jih, Nae-Yeou; Wei, Der-Hsin

    2016-08-01

    This study demonstrates the effect of antiferromagnet-induced perpendicular magnetic anisotropy (PMA) on ferromagnetic/antiferromagnetic/ferromagnetic (FM/AFM/FM) trilayers and reveals its interplay with a long-range interlayer coupling between separated FM layers. In epitaxially grown 12 monolayer (ML) Ni/Co/Mn/5 ML Co/Cu(001) films, magnetic hysteresis loops and element-resolved magnetic domain imaging showed that the magnetization direction of the top layers of 12 ML Ni/Co films could be changed from the in-plane direction to the perpendicular direction, when the thickness of the Mn films (tMn) was greater than a critical value close to the thickness threshold associated with the onset of AFM ordering (tMn=3.5 ML). The top FM layers exhibited a significantly enhanced PMA when tMn increased further, and this enhancement can be attributed to a strengthened AFM ordering of the volume moments of the Mn films, as evidenced by the presence of induced domain frustration. By contrast, the long-range interlayer coupling presented clear effects only when tMn was at a lower coverage.

  13. Soil bacteria for remediation of polluted soils

    Energy Technology Data Exchange (ETDEWEB)

    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.

  14. Synthesis of Multimetal-Graphene Composite by Mechanical Milling

    Science.gov (United States)

    Saiphaneendra, Bachu; Srivastava, Avi Krishna; Srivastava, Chandan

    2016-10-01

    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. Evaluation of vapor generation for the determination of nickel by inductively coupled plasma-atomic emission spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Marrero, Julieta [Comision Nacional de Energia Atomica, Unidad de Actividad Quimica, Centro Atomico Constituyentes, Av. Gral. Paz 1499, 1650-San Martin, Pcia. de Buenos Aires (Argentina); Smichowski, Patricia [Comision Nacional de Energia Atomica, Unidad Proyectos Especiales de Suministros Nucleares, Av. Libertador 8250, 1429-Buenos Aires (Argentina)

    2002-09-01

    Volatile species of Ni were generated by merging acidified aqueous samples and sodium tetrahydroborate(III) in a continuous flow system. The gaseous analyte was subsequently introduced via a stream of Ar carrier into the inlet tube of the plasma torch. Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used for detection. The operating conditions (chemical and physical parameters) and the concentrations of different acids were evaluated for the efficient generation of Ni vapor. The detection limit (3 {sigma}{sub blank}) was 1.8 ng mL{sup -1}. The precision (RSD) of the determination was 4.2% at a level of 500 ng mL{sup -1} and 7.3% for 20 ng mL{sup -1} (n=10). The efficiency of the generation process was estimated to be 51%. The possible interfering effect of transition metals (Cd, Co, Cu, Cr, Fe, Mn, Zn), hydride forming elements (As, Ge, Pb, Sb, Se, Sn, Te), and Hg on Ni signal was examined. This study has demonstrated that Ni vapor generation is markedly free of interferences. (orig.)

  16. Generation of Cu–In alloy surfaces from CuInO2 as selective catalytic sites for CO2 electroreduction

    KAUST Repository

    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.

  17. Assessing the Heavy Metal Content in Forest Dormouse (Dryomys nitedula Pallas, 1778 from an Agricultural Region in Bulgaria

    Directory of Open Access Journals (Sweden)

    Georgi G. Markov

    2016-06-01

    Full Text Available The heavy metals load in the forest dormouse (Dryomys nitedula, inhabiting in forest shelter belts in the agricultural region was assessed. The concentrations of Cd, Co, Cu, Ni, Pb and Zn (expressed in mg/kg of dry tissue were established in the liver, using an atomic-absorption analysis. The fact that the highly toxic metals (Cd and Pb were found in considerable concentrations together with other metals with concentration dependent toxic effect (Cu, Ni, Zn and Co in the liver of forest dormice, suggests that it is necessary to carry out regular assessment and forecasting of accumulation of these metals in species, which are not direct targets of cultivation and control activities in agricultural ecosystems. The obtained values were used to create a baseline for estimation of heavy metal accumulation in the internal organs of the forest dormouse, both in anthropogenically transformed habitats and natural biotopes, as well as for using this species as a monitor of environmental status.

  18. Identifying the origin of atmospheric inputs of trace elements in the Prades Mountains (Catalonia) with bryophytes, lichens, and soil monitoring.

    Science.gov (United States)

    Achotegui-Castells, Ander; Sardans, Jordi; Ribas, Àngela; Peñuelas, Josep

    2013-01-01

    The biomonitors Hypnum cupressiforme and Xanthoria parietina were used to assess the deposition of trace elements and their possible origin in the Prades Mountains, a protected Mediterranean forest area of NE Spain with several pollution sources nearby. Al, As, Cd, Co, Cu, Cr, Ni, Pb, Sb, Ti, V, and Zn were determined in 16 locations within this protected area. Soil trace element concentrations were also ascertained to calculate enrichment factors (EF) and use them to distinguish airborne from soilborne trace element inputs. In addition, lichen richness was measured to further assess atmospheric pollution. EF demonstrated to be useful not only for the moss but also for the lichen. Cd, Cr, Cu, Ni, and Zn presented values higher than three in both biomonitors. These trace elements were also the main ones emitted by the potential sources of pollutants. The distance between sampling locations and potential pollution sources was correlated with the concentrations of Cu, Sb, and Zn in the moss and with Cr, Ni, and Sb in the lichen. Lichen richness was negatively correlated with lichen Cu, Pb, and V concentrations on dry weight basis. The study reflected the remarkable influence that the pollution sources have on the presence of trace elements and on lichen species community composition in this natural area. The study highlights the value of combining the use of biomonitors, enrichment factors, and lichen diversity for pollution assessment to reach a better overview of both trace elements' impact and the localization of their sources.

  19. Chemical and process mineralogical characterizations of spent lithium-ion batteries: an approach by multi-analytical techniques.

    Science.gov (United States)

    Zhang, Tao; He, Yaqun; Wang, Fangfang; Ge, Linhan; Zhu, Xiangnan; Li, Hong

    2014-06-01

    Mineral processing operation is a critical step in any recycling process to realize liberation, separation and concentration of the target parts. Developing effective recycling methods to recover all the valuable parts from spent lithium-ion batteries is in great necessity. The aim of this study is to carefully undertake chemical and process mineralogical characterizations of spent lithium-ion batteries by coupling several analytical techniques to provide basic information for the researches on effective mechanical crushing and separation methods in recycling process. The results show that the grade of Co, Cu and Al is fairly high in spent lithium ion batteries and up to 17.62 wt.%, 7.17 wt.% and 21.60 wt.%. Spent lithium-ion batteries have good selective crushing property, the crushed products could be divided into three parts, they are Al-enriched fraction (+2 mm), Cu and Al-enriched fraction (-2+0.25 mm) and Co and graphite-enriched fraction (-0.25 mm). The mineral phase and chemical state analysis reveal the electrode materials recovered from -0.25 mm size fraction keep the original crystal forms and chemical states in lithium-ion batteries, but the surface of the powders has been coated by a certain kind of hydrocarbon. Based on these results a flowsheet to recycle spent LiBs is proposed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Optimization of the operating conditions of solid sampling electrothermal vaporization coupled to inductively coupled plasma optical emission spectrometry for the sensitive direct analysis of powdered rice.

    Science.gov (United States)

    Sadiq, Nausheen; Beauchemin, Diane

    2014-12-03

    Two different approaches were used to improve the capabilities of solid sampling (SS) electrothermal vaporization (ETV) coupled to inductively coupled plasma optical emission spectrometry (ICP-OES) for the direct analysis of powdered rice. Firstly, a cooling step immediately before and after the vaporization step in the ETV temperature program resulted in a much sharper analyte signal peak. Secondly, point-by-point internal standardization with an Ar emission line significantly improved the linearity of calibration curves obtained with an increasing amount of rice flour certified reference material (CRM). Under the optimized conditions, detection limits ranged from 0.01 to 6ngg(-1) in the solid, depending on the element and wavelength selected. The method was validated through the quantitative analysis of corn bran and wheat flour CRMs. Application of the method to the multi-elemental analysis of 4-mg aliquots of real organic long grain rice (white and brown) also gave results for Al, As, Co, Cu, Fe, Mg, Se, Pb and Zn in agreement with those obtained by inductively coupled plasma mass spectrometry following acid digestion of 0.2-g aliquots. As the analysis takes roughly 5min per sample (2.5min for grinding, 0.5-1min for weighing a 4-mg aliquot and 87s for the ETV program), this approach shows great promise for fast screening of food samples.

  1. Petrosia testudinaria as a biomarker for metal contamination at Gulf of Mannar, southeast coast of India.

    Science.gov (United States)

    Rao, J Venkateswara; Kavitha, P; Reddy, N Chakra; Rao, T Gnaneshwar

    2006-10-01

    Coastal marine ecosystems in many parts of the world are under unrelenting stress caused by urban development, pollutants and other ecological impacts such as building of infrastructure, land reclamation for port and industrial development, habitat modification, tourism and recreational activities. The present work is a first extensive field study using the marine sponge, Petrosia testudinaria as a biomarker to detect heavy metal pollution between near and off shore environment of 'Gulf of Mannar', India. Sponges were collected from near shore (0.5-1 km) and offshore (5-7 km), locations and their metal concentrations were determined by inductively coupled plasma-mass spectrometry (ICPMS). Our results show that the near shore sponge accumulated greater concentrations of heavy metals (Al, Fe, Mn, As, Ni, Co, Cu, Se) ranging from 0.13 to 64 times higher concentration than the sponges located away from the shore. The results indicate that the accumulated metals alter the macromolecule composition (sugars, proteins and lipids) in near shore sponges. Frequent monitoring is necessary to assess the eco-health of the marine environment by choosing bioindicator species like sponges, which provide accurate, reliable measurement of environmental quality.

  2. A water-in-oil emulsion containing Kelex-100 for the speciation analysis of trace heavy metals in water

    Energy Technology Data Exchange (ETDEWEB)

    Matsumiya, Hiroaki [Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)]. E-mail: h-matsu@numse.nagoya-u.ac.jp; Ohkouchi, Ryohei [Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Hiraide, Masataka [Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2006-01-25

    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{sup -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 {mu}m), 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.

  3. Trace elements and electrolytes in human resting mixed saliva after exercise

    Science.gov (United States)

    Chicharro, J. L.; Serrano, V.; Urena, R.; Gutierrez, A. M.; Carvajal, A.; Fernandez-, H; Lucia, A.

    1999-01-01

    OBJECTIVES: Exercise is known to cause changes in the concentration of salivary components such as amylase, Na, and Cl. The aim of this investigation was to evaluate the effect of physical exercise on the levels of trace elements and electrolytes in whole (mixed) saliva. METHODS: Forty subjects performed a maximal exercise test on a cycle ergometer. Samples of saliva were obtained before and immediately after the exercise test. Sample concentrations of Fe, Mg, Sc, Cr, Mn, Co, Cu, Zn, Se, Sr, Ag, Sb, Cs, and Hg were determined by inductively coupled plasma mass spectrometry and concentrations of Ca and Na by atomic absorption spectrometry. RESULTS: After exercise, Mg and Na levels showed a significant increase (p < 0.05) while Mn levels fell (p < 0.05). Zn/Cu molar ratios were unaffected by exercise. CONCLUSIONS: Intense physical exercise induced changes in the concentrations of only three (Na, Mg, and Mn) of the 16 elements analysed in the saliva samples. Further research is needed to assess the clinical implications of these findings. 


 PMID:10378074

  4. Free-time and fixed end-point optimal control theory in dissipative media: application to entanglement generation and maintenance.

    Science.gov (United States)

    Mishima, K; Yamashita, K

    2009-07-07

    We develop monotonically convergent free-time and fixed end-point optimal control theory (OCT) in the density-matrix representation to deal with quantum systems showing dissipation. Our theory is more general and flexible for tailoring optimal laser pulses in order to control quantum dynamics with dissipation than the conventional fixed-time and fixed end-point OCT in that the optimal temporal duration of laser pulses can also be optimized exactly. To show the usefulness of our theory, it is applied to the generation and maintenance of the vibrational entanglement of carbon monoxide adsorbed on the copper (100) surface, CO/Cu(100). We demonstrate the numerical results and clarify how to combat vibrational decoherence as much as possible by the tailored shapes of the optimal laser pulses. It is expected that our theory will be general enough to be applied to a variety of dissipative quantum dynamics systems because the decoherence is one of the quantum phenomena sensitive to the temporal duration of the quantum dynamics.

  5. Comparison of some newly synthesized chemically modified Amberlite XAD-4 resins for the preconcentration and determination of trace elements by flow injection inductively coupled plasma-mass spectrometry (ICP-MS).

    Science.gov (United States)

    Kara, Derya; Fisher, Andrew; Hill, Steve J

    2006-11-01

    XAD copolymer resins may be functionalized with heavy metal ion-selective ligands either by covalent linkage to the polymer backbone or by impregnation. These resins may be tailored to be specific for certain heavy metals by adjusting the retention and elution parameters. For the synthesis of immobilized Amberlite XAD-4 copolymer resins that are expected to preconcentrate a number of transition and heavy metals, the Schiff base method was chosen. For this purpose the copolymer was nitrated, reduced to the corresponding amine and converted to the imine compounds via a Schiff base reaction using different organic aldehyde compounds. The interactions of 8 elements (Cd, Co, Cu, Mn, Ni, Pb, U and Zn) with the resins were qualitatively investigated. Optimal pH for retention was typically 6-8 for most resins although one could be used at pH 5 and elution was achieved using 0.1 M HNO3. The resins were characterized by FTIR, SEM and elemental analysis. It was demonstrated that the resins could be used to preconcentrate ultra-trace analytes from natural waters, and analysis of environmental certified reference materials using FI-ICP-MS showed good agreement with the certified values. Metal retention capacities were also calculated using a batch system and were found to compare favorably with other resins reported in the literature.

  6. Determination of trace heavy metals in soil and sediments by atomic spectrometry following preconcentration with Schiff bases on Amberlite XAD-4.

    Science.gov (United States)

    Kara, Derya; Fisher, Andrew; Hill, Steve J

    2009-06-15

    A matrix separation and analyte preconcentration system using Amberlite XAD copolymer resins functionalized by Schiff base reactions coupled with atomic spectrometry has been developed. Three different functionalized Amberlite XAD resins were synthesized using 4-phenylthiosemicarbazide, 2,3-dihydroxybenzaldehyde and 2-thiophenecarboxaldehyde as reagents. These resins could be used to preconcentrate transition and other trace heavy metal analytes from nitric acid digests of soil and sediment samples. Analyte retention was shown to work well at pH 6.0. After treatment of the digests with sodium fluoride and buffering to pH 6, samples that contain extremely large concentrations of iron were analysed for trace analytes without the excess iron overloading the capacity of the resin. The analytes Cd, Co, Cu, Ni and Pb were preconcentrated from acid extracts of certified soil/sediment samples and then eluted with 0.1M HNO(3) directly to the detection system. Flame atomic absorption spectrometry was used as a means of detection during the studies. The efficiency of the chelating resin and the accuracy of the proposed method were evaluated by the analysis of soil (SO-2) and sediment (LGC 6157 and MESS-3) certified reference materials.

  7. A study on toxic and essential elements in rice from the Republic of Kazakhstan: comparing the level of contamination in rice from the European Community.

    Science.gov (United States)

    Tattibayeva, D; Nebot, C; Miranda, J M; Cepeda, A; Mateyev, E; Erkebaev, M; Franco, C M

    2016-02-01

    Selected toxic elements (total As, Cd, Cr, Hg, Pb, Sr, U and V) and essential elements (Co, Cu, Fe, Mn and Zn) were analyzed using an inductively coupled plasma mass spectrometry (ICP-MS) in unpolished and milled rice collected from Kazakhstan and milled rice from Spain and Portugal to evaluate the potential health risk to the population. Arsenic species (arsenite, arsenate, arsenobetaine, dimethylarsinate and monomethilarsonate) were analyzed using HPLC-IC-MS. From 146 samples analyzed, none of them exceeded the maximum limit set by the European Legislation for Cd or Pb or values recommended by the Codex Alimentarius. Concentrations of Sr, U and V were below LOD and those of Hg, Pb, Co and Cr between Spain and in four from Portugal were above the limit. The estimated weekly intake of total or inorganic As(III, V), Cd, Hg and Pb for rice consumption by Kazakh, Spanish and Portuguese adults and children was lower than the provisional tolerable weekly intake established by Joint FAO/WHO Expert Committee on Food Additives and the European Food Safety Authority.

  8. Multilayer analysis using SIMS: interpretation of profiles at interfaces. Analyse de couches ou multicouches par SIMS : interpretation du profil aux interfaces

    Energy Technology Data Exchange (ETDEWEB)

    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.).

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

    Science.gov (United States)

    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. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Cyclic M2(RL)2 coordination complexes of 5-(3-[N-tert-Butyl-N-aminoxyl]phenyl)pyrimidine with paramagnetic transition metal dications.

    Science.gov (United States)

    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.

  11. Exploring the link between micro-nutrients and phytoplankton in the Southern Ocean during the 2007 austral summer

    Directory of Open Access Journals (Sweden)

    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.

  12. Vacuum Brazing of WC-8Co Cemented Carbides to Carbon Steel Using Pure Cu and Ag-28Cu as Filler Metal

    Science.gov (United States)

    Zhang, X. Z.; Liu, G. W.; Tao, J. N.; Shao, H. C.; Fu, H.; Pan, T. Z.; Qiao, G. J.

    2016-12-01

    The wetting and spreading behavior of commercial pure Cu and Ag-28Cu alloy on WC-8Co cemented carbide were investigated by the sessile drop technique. The contact angle of both systems obviously decreases with moderately increasing the wetting temperature. Vacuum brazing of the WC-8Co cemented carbide to SAE1045 steel using the pure Cu or Ag-28Cu as filler metal was further carried out based on the wetting results. The interfacial interactions and joint mechanical behavior involving microhardness, shear strength and fracture were analyzed and discussed. An obvious Fe-Cu-Co transition layer is detected at the WC-8Co/Cu interface, while no obvious reaction layer is observed at the whole WC-8Co/Ag-28Cu/SAE1045 brazing seam. The microhardness values of the two interlayers and the steel substrate near the two interlayers increase more or less, while those of WC-8Co cemented carbide substrates adjacent to the two interlayers decrease. The WC-8Co/SAE1045 joints using pure Cu and Ag-28Cu alloy as filler metals obtain average shear strength values of about 172 and 136 MPa, and both of the joint fractures occur in the interlayers.

  13. Wetting Properties and Interface Reaction Mechanism of Ag-Cu Brazes on Dual-phase Membrane Ceramic%Ag-Cu钎料与双相陶瓷透氧膜的润湿和界面反应研究

    Institute of Scientific and Technical Information of China (English)

    2016-01-01

    用座滴法测试Ag-Cu合金钎料对Ce0.8Gd0.2O2-δ-NdBaCo2O5+δ(CGO-NBCO)双相透氧膜的润湿性,利用SEM-EDS分析润湿和界面反应机理.结果表明:空气条件下Ag-Cu合金与CGO-NBCO间的润湿遵从界面反应润湿机制.随着Cu含量的增加,Ag-Cu合金对透氧膜润湿性能提高,Cu含量为6.6mol%/~ 15.8mol%时,润湿角在35°~20°左右.在润湿界面处出现Cu氧化物的富集,并且在透氧膜侧生成一层由Cu氧化物和CGO-NBCO双相透氧膜反应产生的Ba-Cu-O、Co-Cu-O和Nd-Ce-Cu-O等复杂氧化物相构成的产物层,新的界面反应层的生成有利于Ag基合金钎料的润湿,改善了钎料的润湿性能.

  14. Major and trace-element analyses of acid mine waters in the Leviathan mine drainage basin, California/Nevada - October, 1981 to October, 1982

    Energy Technology Data Exchange (ETDEWEB)

    Ball, J.W.; Nordstrom, D.K.

    1985-01-01

    Water issuing from the inactive Leviathan open-pit sulfur mine has caused serious degradation of the water quality in the Leviathan/Bryant Creek drainage basin which drains into the East Fork of the Carson River. This report presents the analytical results from this sampling survey. Sixty-seven water samples were filtered and preserved on-site at 45 locations and at 3 different times. Temperature, discharge, pH, and Eh and specific conductance were measured on-site. Concentrations of 37 major and trace constituents were determined later in the laboratory on preserved samples. The quality of the analyses was checked by using two or more techniques to determine the concentrations including d.c.-argon plasma emission spectrometry (DCP), flame and flameless atomic absorption spectrophotometry, UV-visible spectrophotometry, hydride-generation atomic absorption spectrophotometry and ion chromatography. Leviathan acid mine waters contain mg/L concentrations of As, Cr, Co, Cu, Mn, Ni, Tl, V and Zn, and hundreds to thousands of mg/L concentrations of Al, Fe, and sulfate at pH values as low as 1.8. Other elements including Ba, B, Be, Bi, Cd, Mo, Sb, Se and Te are elevated above normal background concentrations and fall in the microgram/L range. The chemical and 34 S/32 S isotopic analyses demonstrate that these acid waters are derived from pyrite oxidation and not from the oxidation of elemental sulfur. 16 refs., 17 figs., 5 tabs.

  15. Risk assessment of children’s exposure to potentially harmful elements (PHE in selected urban parks of the Silesian agglomeration

    Directory of Open Access Journals (Sweden)

    Kicińska Alicja

    2016-01-01

    Full Text Available The author determined the total contents of selected elements potentially hazardous for health (PHE: As, Be, Cd, Co, Cu, Ni and Sn in soils, sand of sandboxes and airborne dust collected in three urban parks of the Silesian agglomeration. The upper limit of Cd content (a Polish regulation was exceeded in the soils of two largest and most frequented parks, the Silesian Park and the Kościuszko Park. The mean Cd contents in soils are 9 and 7 mg/kg, respectively. The metal contents of the sand from sandboxes are generally much lower than those of the soils: Cu 28 times on average, As 13 times, and Cd and Ni around 4 times, while the Co and Sn contents of sand are comparable with those of soils. Airborne dusts are a significant source of metals: they contain Cd (1–20 mg/kg, Co (2–17 mg/kg and Cu (6–143 mg/kg. The quotients of the health risk indicate a potential health risk caused by As, Cd and Ni for children, particularly those with a low (below 15 kg body weight. The risk level of 1–4% PTMDI (Provisional Maximum Tolerable Daily Intake origins from an accidental swallowing of soil.

  16. Metal concentrations in sediments from tourist beaches of Miri City, Sarawak, Malaysia (Borneo Island).

    Science.gov (United States)

    Nagarajan, R; Jonathan, M P; Roy, Priyadarsi D; Wai-Hwa, L; Prasanna, M V; Sarkar, S K; Navarrete-López, M

    2013-08-15

    Forty-three sediment samples were collected from the beaches of Miri City, Sarawak, Malaysia to identify the enrichment of partially leached trace metals (PLTMs) from six different tourist beaches. The samples were analyzed for PLTMs Fe, Mn, Cr, Co, Cu, Ni, Pb, Sr and Zn. The concentration pattern suggest that the southern side of the study area is enriched with Fe (1821-6097 μg g(-1)), Mn (11.57-90.22 μg g(-1)), Cr (51.50-311 μg g(-1)), Ni (18-51 μg g(-1)), Pb (8.81-84.05 μg g(-1)), Sr (25.95-140.49 μg g(-1)) and Zn (12.46-35.04 μg g(-1)). Compared to the eco-toxicological values, Cr>Effects range low (ERL), Lowest effect level (LEL), Severe effect level (SEL); Cu>Unpolluted sediments, ERL, LEL; Pb>Unpolluted sediments and Ni>ERL and LEL. Comparative results with other regions indicate that Co, Cr, Cu, Ni and Zn are higher, indicating an external input rather than natural process.

  17. Determination of Trace Elements in Edible Nuts in the Beijing Market by ICP-M.

    Science.gov (United States)

    Yin, Liang Liang; Tian, Qing; Shao, Xian Zhang; Kong, Xiang Yin; Ji, Yan Qin

    2015-06-01

    Nuts have received increased attention from the public in recent years as important sources of some essential elements, and information on the levels of elements in edible nuts is useful to consumers. Determination of the elemental distributions in nuts is not only necessary in evaluating the total dietary intake of the essential elements, but also useful in detecting heavy metal contamination in food. The aim of this study was to determine the mineral contents in edible nuts, and to assess the food safety of nuts in the Beijing market. Levels of Li, Cr, Mn, Co, Cu, Zn, As, Se, Rb, Sr, Mo, Cd, Cs, Ba, Pb, Th, and U in 11 types of edible nuts and seeds (macadamia nuts, lotus nuts, pistachios, sunflower seeds, pine nuts, almonds, walnuts, chestnuts, hazelnuts, cashews, and ginkgo nuts) as well as raisins were determined by inductively coupled plasma mass spectrometry (ICP-MS). The accuracy of the method was validated using standard reference materials GBW10014 (cabbage) and GBW10016 (tea). Our results provide useful information for evaluating the levels of trace elements in edible nuts in the Beijing market, will be helpful for improving food safety, and will aid in better protecting consumer interests.

  18. Electronic structure and half-metallicity in new Heusler alloys CoYO2 (Y = Sc, Ti, V, Cr, Mn, Fe, Ni, Cu, and Zn)

    Science.gov (United States)

    Esteki, S.; Ahmadian, F.

    2017-09-01

    First-principles calculations based on density functional theory (DFT) using the self-consistent full-potential linearized augmented plane wave (FPLAPW) method were applied to study the electronic structures and magnetic properties of new Heusler alloys CoYO2 (Y = Sc, Ti, V, Cr, Mn, Fe, Ni, Cu, and Zn). The calculated formation energies of these compounds were negative, therefore, they can be synthesized experimentally. All compounds were stable in ferromagnetic AlCu2Mn-type structure. In AlCu2Mn-type structure, CoScO2, CoFeO2, and CoNiO2 compounds were HM ferromagnets, CoCuO2 was a nearly half-metal, CoZnO2 was a spin gapless semiconductor, and other compounds were conventional ferromagnets. In CuHg2Ti-type structure, CoTiO2 compound had a nearly HM characteristic, CoVO2 was a spin gapless semiconductor, and other compounds were conventional ferromagnets. The origin of the half-metallic band gap for CoScO2 alloy Heusler alloy was well understood. The total magnetic moments of the three HM compounds obeyed Slater-Pauling rules (Mtot = 22-Ztot and Mtot = 32-Ztot). CoScO2 had the widest region of half-metallicity between the three half-metals indicating its high robustness of half-metallicity with respect to the variation of lattice constants.

  19. Flow injection analysis as a tool for enhancing oceanographic nutrient measurements--a review.

    Science.gov (United States)

    Worsfold, Paul J; Clough, Robert; Lohan, Maeve C; Monbet, Philippe; Ellis, Peter S; Quétel, Christophe R; Floor, Geerke H; McKelvie, Ian D

    2013-11-25

    Macronutrient elements (C, N and P) and micronutrient elements (Fe, Co, Cu, Zn and Mn) are widely measured in their various physico-chemical forms in open ocean, shelf sea, coastal and estuarine waters. These measurements help to elucidate the biogeochemical cycling of these elements in marine waters and highlight the ecological and socio-economic importance of the oceans. Due to the dynamic nature of marine waters in terms of chemical, biological and physical processes, it is advantageous to make these measurements in situ and in this regard flow injection analysis (FIA) provides a suitable shipboard platform. This review, therefore, discusses the role of FIA in the determination of macro- and micro-nutrient elements, with an emphasis on manifold design and detection strategies for the reliable shipboard determination of specific nutrient species. The application of various FIA manifolds to oceanographic nutrient determinations is discussed, with an emphasis on sensitivity, selectivity, high throughput analysis and suitability for underway analysis and depth profiles. Strategies for enhancing sensitivity and minimizing matrix effects, e.g. refractive index (schlieren) effects and the important role of uncertainty budgets in underpinning method validation and data quality are discussed in some detail.

  20. Chemical effects on vibrational properties of adsorbed molecules on metal surfaces: Coverage dependence

    Science.gov (United States)

    Ueba, H.

    1987-10-01

    Vibrational properties of chemisorbed molecules on metal surfaces are studied with a focus on the coverage dependent chemical shift of the frequencies. Available experimental data of a CO adsorption on transition metal and noble metal surfaces are analyzed in the light of the coverage dependent back-donation into the 2 π* orbitals of chemisorbed CO molecules. The vibrational frequency ωCO of the intramolecular stretching mode exhibits a downward shift of varying magnitude, depending on the amount of back-donation into the 2 π* orbitals of the chemisorbed CO. On increasing the coverage θ, ωCO usually increases due to the dipole-dipole interaction. On Cu surfaces, however, the shifts are relatively small, or in some cases, negative. So far, this anomalous frequency shift with θ is understood as a result of competitive effect between the upward dipole Ωdip and the downward chemical shift Ωchem associated with back-donation. The purpose of this paper is to establish the possible origin of the downward frequency shift through the electronic properties of an incomplete monolayer of adsorbates. The adsorbate density of states ρa is calculated by means of the coherent potential approximation, in which the electron hopping between the adsorbates (band formation effect) and the depolarization effect due to the proximity of ionized adsorbed molecules are taken into account. The change of the occupied portion of ρa and ρa ( ɛF) at the Fermi level ɛF with increasing θ then manifests itself in the coverage dependent Ωchem not only due to the static back-donation, but also due to the dynamical charge fluctuation during vibrational excitation. It is found that in a weakly chemisorbed system, such as CO/Cu, the negative Ωchem amounts to Ωdip at low θ. Consequently the apparent total frequency shift remains almost constant. As the coverage increases, Ωchem becomes larger than Ωdip due to the band effect. It is also shown that the variation of the back

  1. Contaminação da microbacia de Caetés com metais pesados pelo uso de agroquímicos Heavy metals contamination of a watershed in Caetés by the use of agrochemicals

    Directory of Open Access Journals (Sweden)

    JAIR FELIPE GARCIA PEREIRA RAMALHO

    2000-07-01

    Full Text Available Com o objetivo de avaliar a contaminação do solo, sedimentos, água e plantas por metais pesados, decorrente do uso de agroquímicos, na microbacia de Caetés em Paty do Alferes, RJ, amostras de solo foram analisadas, em 1996, para obter os teores totais de Cd, Co, Cu, Mn, Ni, Pb e Zn de duas áreas com diferentes declividades (25% e 45% tendo, ambas, como cobertura vegetal, capoeira, pasto e olericultura. Os resultados referentes aos solos sob pastagem (antiga área de olericultura mostraram maiores teores de metais pesados do que a área de capoeira. Entretanto, esses valores não atingiram níveis críticos no solo, e esses elementos estavam presentes em formas químicas pouco disponíveis para absorção pelas plantas, como foi constatado na análise de metais pesados em tomate (Lycopersicum esculentum L., pimentão (Capsicum annuum L., repolho (Brassica oleracea L. e pepino (Cucumis sativus L., que apresentaram níveis baixíssimos desses elementos. Nas amostras de sedimentos, o comportamento dos metais pesados foi semelhante ao obtido nos solos, estando esses elementos distribuídos em maior porcentagem nas frações residual, ligadas a óxidos de Mn e Fe e ligadas à matéria orgânica. As amostras de água do córrego e do açude que cortam a microbacia apresentaram valores acima dos padrões internacionais com relação a Cd, Pb e Mn.To evaluate heavy metals contamination of soil, sediments, water and plants of the Caetés watershed, in Paty do Alferes, RJ, Brazil, by the use of agrochemicals, samples from two areas with different declivities (25% and 45% were analysed, in 1996, for total contents of Cd, Co, Cu, Mn, Ni, Pb and Zn. The results for the soils under pasture (lately horticulture showed higher heavy metals contents in comparison to the brushwood area. However, these contents didn't reach the critical levels for soils, and these elements were present in chemical forms of low disponibility for plant absorption, as it was seen

  2. Concentrations of As, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, Pb, and Zn in uruguayan rice determined by atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Mario E. Rivero Huguet

    2011-04-01

    Full Text Available The United Nations General Assembly declared the year 2004 the International Year of Rice and the concept "Rice is life". The largest nutritional problems occurring globally are protein-energy malnutrition, and Ca, Fe, I, Zn, and vitamin A deficiency. In this report, 49 rice samples (Oryza sativa L. were digested by dry ashing in order to determine As, Cd, Cr, and Pb by ETA-AAS; while Ca, Co, Cu, Fe, K, Mg, Mo, Mn, Na, Ni, and Zn were determined by FAAS; and Hg by CV-AAS using microwave-assisted decomposition. The following concentration ranges were obtained for Ca (9.1-15 mg/100 g, Cd (2.30-4.12 µg/kg, Co (41-60 µg/kg, Cu (1.33-180 mg/kg, Fe (4.41-7.15 mg/kg, K (167-217 mg/100 g, Mg (45-121 mg/100 g, Mo (0.52-0.97 mg/kg, Mn (5.45-25.4 mg/kg, Na (0.95-2.50 mg/100g, Ni (0.53-0.72 mg/kg, and Zn (5.86-12.6 mg/kg. Mean recoveries of elements from fortified rice were: 87±12% for As, 95.3±8.9% for Ca, 106.2±7.7% for Cd, 103.3±6.5% for Co, 89.4±8.1% for Cr, 99.3±4.6% for Cu, 103±10% for Fe, 96.3±9.3% for Hg, 95.4±12% for K, 98.3±8.0% for Mg, 93.4±7.8% for Mo, 95.3±9.9% for Mn, 89±12% for Na, 90.3±9.7% for Ni, 91.2±5.5% for Pb and 92.0±9.4% for Zn. The concentrations of the minerals and microelements studied fall within the typical range of rice grown around the world. Potassium was the most abundant mineral, followed by Mg and Ca; among microelements, the concentrations of Cu, Fe, Mo, Mn, Na, and Zn in rice were outstanding. It was also found that the milling process highly affects the K, Mg, Mn, Na, and Zn concentrations, while it has little influence on Ca, Co, Cu, and Fe. On the other hand, there is a loss of Ca, Fe, and Mn during the parboiling process. Recent studies have shown the potential to exploit the genetic variation of rice seeds with regard to the concentration of some minerals (Ca, Fe, Zn, etc. without affecting yield or adding new traits. All rice samples tested showed lower levels of As, Cd, Hg, and Pb in comparison

  3. Preparation and characterization of inexpensive heterogeneous catalysts for air pollution control. Two case studies

    Energy Technology Data Exchange (ETDEWEB)

    Utsumi, Shigenori; Vallejos-Burgos, Fernando E.; Garcia, Ximena; Gordon, Alfredo L. [Department of Chemical Engineering, University of Concepcion, Concepcion (Chile); Campos, Claudia M.; Pecchi, Gina [Department of Physical Chemistry, University of Concepcion, Concepcion (Chile); Radovic, Ljubisa R. [Department of Chemical Engineering, University of Concepcion, Concepcion (Chile); Department of Energy and Geo-Environmental Engineering, The Pennsylvania State University, University Park, PA 16802 (United States)

    2007-05-30

    Relatively inexpensive heterogeneous catalysts for two reactions of great importance in air pollution control, NO reduction and VOC combustion, were prepared and characterized. Apart from their common practical goal and the frequent need for simultaneous removal of air pollutants, these reactions share a similar redox mechanism, in which the formulation of more effective catalysts requires an enhancement of oxygen transfer. For NO reduction, supported catalysts were prepared by adding a metal (Cu, Co, K) using ion exchange (IE) and incipient wetness impregnation (IWI) to chars obtained from pyrolysis of a subbituminous coal. The effects of pyrolysis temperature, between 550 and 1000 C, on selected catalyst characteristics (e.g., BET surface area, XRD spectrum, support reactivity in O{sub 2}) are reported. For IE catalysts, the surface area increased in the presence of the metals while the opposite occurred for IWI catalysts. For the Co-IE catalysts, the highest surface area was obtained at 700 C. The XRD results showed that, except for Cu (which exhibited sharp Cu{sup 0} peaks), the catalysts may be highly dispersed (or amorphous) on the carbon surface. For the C-O{sub 2} reaction the order of (re)activity was K >> Co > Cu for IE catalysts and K > Cu > Co for IWI catalysts. For NO reduction the orders were K > Co > Cu (IE catalysts) and Cu > Co > K (IWI catalysts). In all cases the catalytic (re)activity for NO reduction was lower than that exhibited for the C-O{sub 2} reaction. The K-IE and Cu-IWI catalysts appeared to be the most promising ones, although further improvements in catalytic activity will be desirable. Some surprising results regarding CO and CO{sub 2} selectivity are also reported, especially for Co catalysts. In VOC combustion, the effect of the nature of ion B (Fe and Ni) on the partial substitution of ion A (Ca for La) in ABO{sub 3} perovskites (e.g., LaFeO{sub 3} and LaNiO{sub 3}) and on their catalytic activity was studied. The perovskite

  4. The Volatility and condensation behaviour of elements in dependence of T and fO2: a novel experimental approach

    Science.gov (United States)

    Ertel-Ingrisch, Werner; Dingwell, Don B.

    2010-05-01

    The volatility of elements is one of the most important variables during geological processes on Earth: its impact ranges from daily out gassing of volcanic vents to catastrophic emissions during volcanic eruptions which might scale up to global impacts on our climate. Volatility played, however, already a major role during the formation of our solar system: the nebular gases and their element budget passed through an elemental fractionation process based on differences in the evaporation and condensation behaviour of matter within the solar nebula - the origin of all the planets within our solar system. Precise knowledge of the parameters controlling volatility as well as condensation of elements is still lacking. Whether an element behaves volatile or refractory depends highly on the temperature and oxygen fugacity (fO2) conditions prevailing. To address this issue, we initiated a systematic study of the volatility of 18 volatile elements in respect to fO2 and temperature applying a modified mechanically assisted equilibration technique (MAE): Approx. 60 g of a haplobasaltic starting composition (An-Di) doped with up to 5000 ppm of volatile elements (Li, K, Na, Ti, Cr, Mn, Co, Cu, Cu, Zn, Ga, Rb, Cd, In, Sn, Sb, Cs, Tl) was heated to run temperatures. To investigate the fO2 dependence 2 experiments at logfO2 = -11.3 (~ IW -0.5) and - 0,7 (pure air) at a constant temperature of 1300 °C were performed, while T dependence was investigated at 1300 and 1500 °C at constant fO2 in pure air. The original MAE technique was modified by two Al2O3 plates extending from the hot spot region up to the upper, cooler regions of the muffle tube. These plates function as condensation traps. The temperature profile of the entire setup including the Al2O3 plates under run conditions was calibrated prior to any run. Experiments lasted for up two weeks while experimental conditions were kept strictly constant and were monitored. Up to 46 samples were taken from the melt by time

  5. 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

    Energy Technology Data Exchange (ETDEWEB)

    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

  6. Nanotechnological inventions considerably improve performance characteristics

    Directory of Open Access Journals (Sweden)

    VLASOV Vladimir Alexeevich

    2014-06-01

    Full Text Available The invention «The method of production of carbon nanomaterial (RU 2509053» can be used as an additive for concretes and polymers which significantly improves their performance characteristics. The method of production of carbon nanomaterial consists of the following stages: preliminary preparation of sphagnous moss when it is refined from foreign admixtures, dried up to 10% humidity and ground, then ground material is exposed to pyrolysis under the temperature 850–950оC for 1–2 hours and cooled up to the environment temperature. After that amorphous carbon obtained in pyrolysis is treated with mechanical activation in the variable planetary mill for 7–10 hours. The invention makes it possible to provide increased outcome of nanotubes with high cleanliness. The invention «The method of production of nanodispersed metal powders and alloys of them (RU 2509626» relates to the powder metallurgy. Powder metal chloride or powder mixture at least of two metal chlorides is treated in the environment of the water steam which is supplied in reaction space at the rate of 50–100 ml/min at the temperature 400–800оC at the presence of absorbent carbon or introducing carbon oxide (II obtained during dissolution of formic acid HCOOH. The invention provides reliable production of nanodispersed metal powders and alloys of them from 3-d metal range: Ni, Co, Cu, Fe, Zn which can be used in powder metallurgy to improve baking process, in chemical industry as the fillers of polymers and reaction catalysts; as additives to anticorrosive covers, etc.

  7. Preliminary studies on mud stabilization / solidification, from textile laundry treatments, for re-utilization as building mortar

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    Carmen Lúcia da Rocha Pietrobon

    2002-04-01

    Full Text Available The laundries and industrial dry cleaner's generate liquid effluents that, after treatment for matter in suspension floculation, produce sludge. This residue has varied chemical composition, due to the products used in the process. Such residue is considered inadequate for in natura disposition in the environment, and it should have, as final destination, an industrial landfill. In the studied case, such industrial landfill is not available and the residues are truck-driven for about 400 Km, causing a strong financial impact over the production of an emergent local textile industry market. This work presents the physical-chemical characterization of the sludge produced by an industrial laundry, studying its final disposition in the process of E/S addition in Portland cement, seeking its re-utilization in civil construction materials, to minimize this residue's final disposition costs. The analysis contemplated: COD total, fixed and volatile solids in the sludge, sludge density, pH and metals presence. The presence of the metals: Fe, Mg, Al, Sn, Ca, Cr, Co, Cu, Mn and Zn was detected in the sludge. The incorporation of this sludge in mortar was studied as residue final destination. Samples of this mortar were submitted to compression resistance analysis. Results demonstrate that the mortar with sludge contents lower than 25% in relation to the cement mass, after 28 days, shows mechanical resistance values larger than 10 Mpa, being fit to be used as civil construction secondary material, without structural function. Posterior studies will be necessary to evaluate the organic matter influence in the composite's durability.

  8. Molybdenum Carbides, Active and In Situ Regenerable Catalysts in Hydroprocessing of Fast Pyrolysis Bio-Oil

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jae-Soon; Zacher, Alan H.; Wang, Huamin; Olarte, Mariefel V.; Armstrong, Beth L.; Meyer, Harry M.; Soykal, I. Ilgaz; Schwartz, Viviane

    2016-06-16

    We assessed molybdenum carbides as a potential catalyst for fast pyrolysis bio-oil hydroprocessing. Currently, high catalyst cost, short catalyst lifetime, and lack of effective regeneration methods are hampering the development of this otherwise attractive renewable hydrocarbon technology. A series of metal-doped bulk Mo carbides were synthesized, characterized and evaluated in sequential low-temperature stabilization and high-temperature deoxygenation of a pine-derived bio-oil. During a typical 60-h run, Mo carbides were capable of upgrading raw bio-oil to a level suitable for direct insertion into the current hydrocarbon infrastructure with residual oxygen content and total acid number of upgraded oils below 2 wt% and 0.01 mg KOH g-1, respectively. The performance was shown to be sensitive to the type of metal dopant, Ni-doped Mo carbides outperforming Co-, Cu-, or Ca-doped counterparts; a higher Ni loading led to a superior catalytic performance. No bulk oxidation or other significant structural changes were observed. Besides the structural robustness, another attractive property of Mo carbides was in situ regenerability. The effectiveness of regeneration was demonstrated by successfully carrying out four consecutive 60-h runs with a reductive decoking between two adjacent runs. These results strongly suggest that Mo carbides are promising catalytic materials which could lead to a significant cost reduction in hydroprocessing bio-oils. This paper highlights areas for future research which will be needed to further understand carbide structure-function relationships and help design practical bio-oil upgrading catalysts based on Mo carbides.

  9. Trace elements and Pb isotopes in soils and sediments impacted by uranium mining.

    Science.gov (United States)

    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 (2

  10. Growth inhibition in early life-stage tests predicts full life-cycle toxicity effects of lead in the freshwater pulmonate snail, Lymnaea stagnalis.

    Science.gov (United States)

    Munley, Kathleen M; Brix, Kevin V; Panlilio, Jennifer; Deforest, David K; Grosell, Martin

    2013-03-15

    The freshwater pulmonate snail, Lymnaea stagnalis, is the most sensitive freshwater organism tested to date for several metals (Co, Cu, Pb, Ni) based on 28 d early life-stage (ELS) tests in which growth was the most sensitive endpoint. The United States Environmental Protection Agency (USEPA) has expressed concern that growth in 28 d ELS tests with mollusks may overpredict toxicity because of the potential for recovery in a full life-cycle (LC) test. Consequently, the USEPA only accepts the survival endpoint for these tests in establishing water quality criteria (WQC). To address this concern, the current study aimed to test the sensitivity of L. stagnalis to Pb in a 56 d full LC test evaluating survival, growth, reproductive and embryonic growth endpoints and compare the estimated effect levels to those established using the 28 d ELS test design. The most sensitive endpoints in this study were 28 d growth and 56 d egg mass production, both with a NOEC of Snails exposed to 1.0 and 2.7 μg L(-1) Pb showed full and partial recovery from growth inhibition between 28 and 56 d. While this recovery supports the USEPA's concern about the 28 d growth endpoint; considering the reproductive lifespan of L. stagnalis and the recovery dose-response, we conclude that the 28 d growth endpoint will be within a factor of 3 of full LC endpoints. This is consistent with the level of precision previously determined for fish ELS tests, which the USEPA accepts for WQC derivation, and suggests that tests using 28 d ELS growth endpoint for L. stagnalis may be acceptable for inclusion in WQC derivation.

  11. Biomonitoring of selected freshwater macrophytes to assess lake trace element contamination: a case study of Nal Sarovar Bird Sanctuary, Gujarat, India

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    Rita N. KUMAR

    2006-02-01

    Full Text Available A biomonitoring study was carried out at Nal Sarovar Bird Sanctuary, a proposed Ramsar site, Gujarat State, India, to ascertain the degree of trace element contamination. The study focused on assessment of trace element contamination in certain aquatic macrophytes to be used as biomonitors, in comparison with the sediments (abiotic monitor for heavy metal pollution. Good information was provided by analyzing roots, stems and leaves of native aquatic plants (biomonitors represented by eight species: Bergia odorata, Hydrilla verticillata, Ipomoea aquatica, Najas graminea, Nelumbo nucifera, Phragmites karka, Typha angustata and Vellisnaria spiralis, alongwith surface sediments and water, were analyzed for Cd, Co, Cu, Cu, Ni, Pb and Zn contamination. The highest concentrations of the trace elements were measured in Ipomoea aquatica and the lowest in Bergia odorata. Based on the concentration and toxicity status observed in the lake's vegetation, the six metals are arranged in the following decreasing order: Zn > Cu > Ni > Co > Pb > Cd. Compared with the standard, normal and critical toxicity range in plants, the detected values of Cd and Pb falls within normal range, while that of Co, Ni and Cu were within the critical range. However, Zn showed the highest concentration and alarming toxicity levels, which is considered as one of the most hazardous pollutants in Nal Sarovar Bird Sanctuary. Certain aquatic macrophytes species are also proposed as biomonitors for the investigated heavy metal pollutants. Such result was significant in the plant species such as Ipomoea aquatica and Phragmites karka, which are the two most useful species in biomonitoring studies due to their ability to accumulate elements in high concentration in the roots and their availability throughout the year. The results showed the significant difference in accumulation rate of some metals like Zn, Cu and Ni in different plant organs, which showed more accumulation in root than

  12. Metal adsorption capabilities of clinoptilolite and selected strains of bacteria from mine water

    Science.gov (United States)

    Mamba, B. B.; Dlamini, N. P.; Nyembe, D. W.; Mulaba-Bafubiandi, A. F.

    Small-scale mining has socio-economic advantages such as the reduction of unemployment and the general improvement of the economy. However, these operations if not properly managed or controlled have a potential to cause environmental damage, particularly with respect to the contamination of groundwater and water supplies that are not distant from where these mining activities take place. This paper focuses on metal removal from water contaminated by heavy metals emanating from small-scale mining operations using clinoptilolite and bacteria. Removal of As, Ni, Mn, Au, Co, Cu and Fe was carried out on mine water samples using original and HCl-activated (in 0.02 M and 0.04 M) natural clinoptilolite and bacterial strains (a mixed consortia of Bacillus strains ( Bacillus subtilis, Bacillus cereus, Bacillus firmus, Bacillus fusiformis, Bacillus macroides and Bacillus licheniformis), Pseudomonas spp., Shewanella spp. and a mixed consortia of Acidithiobcillus caldus, Leptospirillum spp., Ferroplasma spp. and Sulphobacillus spp.). The purpose of the study was to compare the removal efficiencies of the bacterial strains versus natural clinoptilolite adsorbents for metal cations. The Bacillus consortia removed most of the metals up to 98% metal removal efficiency with the exception of nickel where clinoptilolite showed good removal efficiency. The 0.02 M HCl-activated clinoptilolite also demonstrated excellent removal capabilities with Cu, Co and Fe removal efficiency of up to 98%. Both clinoptilolite and bacteria demonstrated capabilities of removing Cu 2+, Co 2+, Fe 2+, Mn 2+, As 3+ and Au from solution which augurs well for metal recovery from mining and mineral processing solutions, as well as in water decontamination.

  13. Year-round record of dissolved and particulate metals in surface snow at Dome Concordia (East Antarctica).

    Science.gov (United States)

    Grotti, Marco; Soggia, Francesco; Ardini, Francisco; Magi, Emanuele; Becagli, Silvia; Traversi, Rita; Udisti, Roberto

    2015-11-01

    From January to December 2010, surface snow samples were collected with monthly resolution at the Concordia station (75°06'S, 123°20'E), on the Antarctic plateau, and analysed for major and trace elements in both dissolved and particulate (i.e. insoluble particles, >0.45 μm) phase. Additional surface snow samples were collected with daily resolution, for the determination of sea-salt sodium and not-sea-salt calcium, in order to support the discussion on the seasonal variations of trace elements. Concentrations of alkaline and alkaline-earth elements were higher in winter (April-October) than in summer (November-March) by a factor of 1.2-3.3, in agreement with the higher concentration of sea-salt atmospheric particles reaching the Antarctic plateau during the winter. Similarly, trace elements were generally higher in winter by a factor of 1.2-1.5, whereas Al and Fe did not show any significant seasonal trend. Partitioning between dissolved and particulate phases did not change with the sampling period, but it depended only on the element: alkaline and alkaline-earth elements, as well as Co, Cu, Mn, Pb and Zn were for the most part (>80%) in the dissolved phase, whereas Al and Fe were mainly associated with the particulate phase (>80%) and Cd, Cr, V were nearly equally distributed between the phases. Finally, the estimated marine and crustal enrichment factors indicated that Cd, Cr, Cu, Pb and Zn have a dominant anthropogenic origin, with a possible contribution from the Concordia station activities.

  14. Accumulation of Heavy Metal Ions from Tanneries Wastes: An Approach For Chromium Removal Using Activated Charcoal

    Directory of Open Access Journals (Sweden)

    *H. Tahir

    2012-09-01

    Full Text Available The environment is under increasing pressure from solid and liquid wastes emanating from the leather industry. These are inevitable by-products of the leather manufacturing process and causes significant pollution unless treated in some way prior to discharge. The tanneries wastes samples were collected from Lahore Pakistan. The samples were digested by wet oxidation method and the concentrations of metals: Cr, Co, Cu, Cd, Mn, Zn, Ni and Pb were estimated in sediments and liquid waste samples by atomic absorption spectrophotometer. The results show that the concentrations of these metals were higher than the values given by the national environmental quality standards. Selective separation of Cr ion from other metals was investigated in sediment sample TS2 by adsorption method using low cost natural adsorbent activated charcoal. The adsorption studies were carried out under the optimized conditions of adsorption like pH, shaking time and amount of adsorbent. The concentration of Cr after removal was determined by atomic absorption spectrophotometer. The adsorption equilibrium data were fitted in adsorption isotherm equations like: Freundlich, and Dubinin-Radushkevich equations at temperatures ranges from 303 to 318 K. Thermodynamic parameters ∆H, ∆S and ∆G were also calculated. The values of sorption free energy were estimated by employing D-R equation. The percent removal data show that about 99% removal was achieved by employing low cost adsorbent. This method can be employed on industrial scale for the treatment of solid and liquid waste before discharge into the main streams.

  15. Water-quality trends for a stream draining the Southern Anthracite Field, Pennsylvania

    Science.gov (United States)

    Cravotta, C.A.; Bilger, M.D.

    2001-01-01

    Stream flow, chemical and biological data for the northern part of Swatara Creek, which drains a 112 km2 area in the Southern Anthracite Field of eastern Pennsylvania, indicate progressive improvement in water quality since 1959, after which most mines in the watershed had been flooded. Drainage from the flooded mines contributes substantially to base flow in Swatara Creek. Beginning in 1995, a variety of treatment systems and surface reclamation were implemented at some of the abandoned mines. At Ravine, Pa., immediately downstream of the mined area, median SO4 concentration declined from about 150 mg l-1 in 1959 to 75 mg l-1 in 1999 while pH increased from acidic to near-neutral values (medians: c. pH 4 before 1975; c. pH 6 after 1975). Fish populations rebounded from non-existent during 1959-1990 to 21 species identified in 1999. Nevertheless, recent monitoring indicates (1) episodic acidification and elevated concentrations and transport of Fe, Al, Mn, and trace metals during storm flow; (2) elevated concentrations of Fe, Mn, Co, Cu, Pb, Ni, and Zn in streambed sediments relative to unmined areas and to toxicity guidelines for aquatic invertebrates and fish; and (3) elevated concentrations of metals in fish tissue, notably Zn. The metals are ubiquitous in the fine fraction (acidic storm runoff derived mainly from low-pH rainfall. Declines in pH to values approaching 5.0 during storm flow events or declines in redox potential during burial of sediment could result in the remobilization of metals associated with suspended solids and streambed deposits.

  16. Population exposure to trace elements in the Kilembe copper mine area, Western Uganda: A pilot study.

    Science.gov (United States)

    Mwesigye, Abraham R; Young, Scott D; Bailey, Elizabeth H; Tumwebaze, Susan B

    2016-12-15

    The mining and processing of copper in Kilembe, Western Uganda, from 1956 to 1982 left over 15 Mt. of tailings containing cupriferous and cobaltiferous pyrite dumped within a mountain river valley. This pilot study was conducted to assess the nature and extent of risk to local populations from metal contamination arising from those mining activities. We determined trace element concentrations in mine tailings, soils, locally cultivated foods, house dust, drinking water and human biomarkers (toenails) using ICP-MS analysis of acid digested samples. The results showed that tailings, containing higher concentrations of Co, Cu, Ni and As compared with world average crust values had eroded and contaminated local soils. Pollution load indices revealed that 51% of agricultural soils sampled were contaminated with trace elements. Local water supplies were contaminated, with Co concentrations that exceeded Wisconsin (US) thresholds in 25% of domestic water supplies and 40% of Nyamwamba river water samples. Zinc exceeded WHO/FAO thresholds of 99.4mgkg(-1) in 36% of Amaranthus vegetable samples, Cu exceeded EC thresholds of 20mgkg(-1) in 19% of Amaranthus while Pb exceeded WHO thresholds of 0.3mgkg(-1) in 47% of Amaranthus vegetables. In bananas, 20% of samples contained Pb concentrations that exceeded the WHO/FAO recommended threshold of 0.3mgkg(-1). However, risk assessment of local foods and water, based on hazard quotients (HQ values) revealed no potential health effects. The high external contamination of volunteers' toenails with some elements (even after a washing process) calls into question their use as a biomarker for metal exposure in human populations where feet are frequently exposed to soil dust. Any mitigation of Kilembe mine impacts should be aimed at remediation of agricultural soils, regulating the discharge of underground contaminated water but also containment of tailing erosion. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Mineral status of llamas and sheep in the Bolivian Altiplano.

    Science.gov (United States)

    Espinoza, J E; McDowell, L R; Rodriguez, J; Loosli, J K; Conrad, J H; Martin, F G

    1982-12-01

    An experiment was conducted in the highlands (Altiplano) of Bolivia to establish the specific mineral status for growing llamas compared to sheep grazing unfertilized, native pastures. Animal tissues (plasma, liver and bone), forage and soil samples were collected during the wet and dry seasons and analyzed for mineral contents. During the wet season, forages were higher (P less than 0.05) in Ca, K, Fe and protein. Percent borderline to deficient forage concentrations during the wet and dry seasons, respectively, were found as follows: protein (less than 7.0%) 20 and 53; CCa (less than 0.30%) 10 and 40; Cu (less than 5 ppm) 20 and 47; K (less than 0.5%) 10 and 20; Mg (less than 0.08%) 10 and 20; Na (less than 0.1%) 30 and 69; P (less than 0.25%) 100 and 100; Zn (less than 30 ppm) 60 and 80; and Se (less than 0.1 ppm) 90 and 93% of the total forages, respectively. Concentrations of liver Mg, Co, Mn, Mo, Se and Zn, plasma Mg and Cu and rib (percent ash) Ca, Mg and P were all higher (P less than 0.05) during the wet than in the dry season. Compared to llamas, sheep had higher (P les than 0.05) concentrations of plasma Ca, Cu, Fe and Zn, rib (milligram/milliliter) P, Mg and Zn and liver Fe, but lower (P less than 0.05) concentrations of liver Co, Cu, Mn and MO. On the basis of forage and animal tissue analyses, the nutrients protein, P, Ca, Zn, Na and Se would be insufficient for optimum production of grazing livestock in the high plains of Bolivia.

  18. A dual site study of PM 2.5 and PM 10 aerosol chemistry in the larger region of Vienna, Austria

    Science.gov (United States)

    Puxbaum, H.; Gomiscek, B.; Kalina, M.; Bauer, H.; Salam, A.; Stopper, S.; Preining, O.; Hauck, H.

    The measurements of PM 2.5 and PM 10 at two sites—an urban site in Vienna (AUPHEP-1) and a rural site considered local background (AUPHEP-2)—indicated only low aerosol generation activity in the city on an annual basis. Defining the term "urban impact" as the difference between observations at the urban and the local background site we find an annually averaged urban impact for PM 2.5 of 3.4 μg m -3 and for PM C of 3.3 μg m -3 (the coarse fraction PM C=PM 10-PM 2.5). The relative increase of the particulate matter (PM) concentration at the urban site compared to the background site (AUPHEP-2) is annually averaged only 19% for PM 2.5, but 60% for PM C. The chemical main constituents of the PM 2.5 urban impact are black carbon (BC), organic carbon (OC), and sulfate; the main constituents of the PM C urban impact are OC and indicators for mineralic aerosol (Fe, Ca, Mg, Na, K). The BC/TC ratio of the PM 2.5 urban impact is typical as for combustion sources, e.g. automotive traffic, oil or coal combustion. Urban coarse OC is considered to originate from non-pyrogenic sources. From the trace metals investigated (As, Cd, Co, Cu, Cr, Mn, Ni, Pb, V, Zn) only Cd, Ni, Pb, and Zn exhibited a slight cold season enrichment in the urban airshed. From the weak signal of a seasonality of oil or coal combustion indicators we conclude that local domestic heating sources are using "clean fuels".

  19. Characterisation of nutrients wet deposition under influence of Saharan dust at Puerto-Rico in Caribbean Sea

    Science.gov (United States)

    Desboeufs, Karine; Formenti, Paola; Triquet, Sylvain; Laurent, Benoit; Denjean, Cyrielle; Gutteriez-Moreno, Ian E.; Mayol-Bracero, Olga L.

    2015-04-01

    Large quantities of African dust are carried across the North Atlantic toward the Caribbean every summer by Trade Winds. Atmospheric deposition of dust aerosols, and in particular wet deposition, is widely acknowledged to be the major delivery pathway for nutrients to ocean ecosystems, as iron, phosphorus and various nitrogen species. The deposition of this dustis so known to have an important impact on biogeochemical processes in the Tropical and Western Atlantic Ocean and Caribbean including Puerto-Rico. However, very few data exists on the chemical composition in nutrients in dusty rain in this region. In the framework of the Dust-ATTAcK project, rainwater was collected at the natural reserve of Cape San Juan (CSJ) (18.38°N, 65.62°W) in Puerto-Ricobetween 20 June 2012 and 12 July 2012 during thedusty period. A total of 7 rainwater events were sampled during various dust plumes. Complementary chemical analyses on aerosols in suspension was also determined during the campaign. The results on dust composition showed that no mixing with anthropogenic material was observed, confirming dust aerosols were the major particles incorporated in rain samples. The partitioning between soluble and particulate nutrients in rain samples showed that phosphorous solubility ranged from 30 and 80%. The average Fe solubility was around 0.5%, in agreement with Fe solubility observed in rains collected in Niger during African monsoon. That means that the high solubility measurements previously observed in Caribbean was probably due to an anthropogenic influence. Atmospheric wet deposition fluxes of soluble and total nutrients (N, P, Si, Fe, Co, Cu, Mn, Ni, Zn) to Caribbean Sea were determined. Atmospheric P and N inputs were strongly depleted relative to the stoichiometry of phytoplankton Fe, N, P and Si requirements.The nitrogen speciation was also determined and showed the predominance of ammonium form. 3-D modeling was used to estimate the spatial extend of these fluxes over the

  20. Isotopic and geochemical characterization of invader tilapia fishes from water bodies of West Bengal and Karnataka, India.

    Science.gov (United States)

    Chatterjee, Mousumi; Ghosh, Prosenjit; Ramdas, Leena; Chakrabarti, Ramananda

    2015-11-01

    The otoliths (N = 12) of freshwater invasive species tilapia (Tilapia mossambicus) collected from two water bodies located at Kolkata and Bangalore, India, were analyzed for stable isotopes (δ18O, δ14C) and major and trace elements in order to assess the suitability of using otoliths as a tracer of aquatic environmental changes. The stable isotope analysis was done using the dual inlet system of a Finnigan-MAT 253 isotope ratio mass spectrometer (Thermo-Fisher, Bremen, Germany). Concentrations of major and trace elements were determined using a Thermo X-Series II quadrupole mass spectrometer. The stable isotope composition in tilapia otolith samples from Bangalore and Kolkata water bodies are quite good agreeing with that of the respective lake/pond and rain water. Elemental composition revealed in a pattern of Ca>Fe>Na>Sr>K>Ba>Cr>Mg>As>Mn>Zn>Co>Cu>Cd>Pb. The otoliths from Kolkata pond water are more enriched in Ba, Zn, Pb, Mn, Se, Cu, Zn, Cd, and Ni whereas Cr and As were found to be higher in otolith samples from Bangalore lake. The enrichment factor (EF) values of Cr were higher for both the sampling location in comparison with other metals, although all the studied metals exhibited EF values>1. The PCA shows clustering of metals in the otolith which are related either with the metabolic and physiological attributes or waterborne source. The study demonstrated the potential of stable isotope techniques to distinguish otolith specimens from varied climatic zone, while elemental composition recorded the quality of water at both the locations. The role of climate driving the quality of water can be understood by detailed and continuous monitoring of otolith specimens in the future. Future method allows reconstruction of climate and water quality from old specimens from field exposures or museum collection.